WO2023209988A1 - Determination device and determination method - Google Patents

Abstract

A determination device (70) is provided with: a load acquisition unit (82) that acquires a load (LO) applied to a screw (34) of an injection molding machine (10) as a resin is injected in a plurality of molding cycles; an operation information acquisition unit (86) that acquires operation information (INF) on the screw (34) before the load (LO) exceeds a first threshold (TH1); a statistical amount calculation unit (88) that calculates a statistical amount (ST) on the basis of a plurality of pieces of the operation information (INF); and a determination unit (92) that determines the quality of a state of the resin measured by the injection molding machine (10) on the basis of the statistical amount (ST).

Description

Judgment device and method

The present invention relates to a determination device and a determination method for determining the quality of resin measured in an injection molding machine.

An injection molding machine is an industrial machine that mass-produces molded products by repeatedly executing a molding cycle that includes multiple steps. The molding cycle includes a metering process and an injection process (see also JP-A-10-16016). The measuring process is a process for measuring the resin to be injected into the mold. The injection process is a process of injecting measured resin into a mold. The resin injected into the mold solidifies to complete the molded product.

The state of the measured resin may vary between multiple molding cycles. That is, the temperature, viscosity, density, amount of resin, etc. of the measured resin may vary between multiple molding cycles.

Variations in the condition of the weighed resin cause variations in the quality (mass, shape, etc.) of the molded product. However, it is difficult for an operator to determine whether the state of resin measured in a certain molding cycle varies compared to the state of resin measured in other molding cycles. That is, it is difficult for the operator to judge whether the measured resin is in good condition or not.

The present invention aims to solve the above-mentioned problems.

A first aspect of the present invention is a determination device that determines the quality of the resin weighed in an injection molding machine that includes a cylinder and a screw that injects the resin metered in the cylinder into a mold. a load acquisition unit that acquires the load applied to the screw in response to the resin being injected from the cylinder to the mold in a plurality of molding cycles; Obtaining operation information including at least one of the amount of movement, amount of rotation, and required time of the screw from when the screw starts an injection operation for injecting resin until the load exceeds a first threshold value. and a motion information acquisition unit that calculates at least one statistic of the movement amount, the rotation amount, and the required time based on a plurality of the motion information acquired during the plurality of molding cycles. The present invention is a determination device comprising: a statistic calculation unit that calculates a statistic; and a determination unit that determines whether the measured resin is in good condition based on the statistic.

A second aspect of the present invention is a determination method for determining the quality of the resin measured in an injection molding machine that includes a cylinder and a screw that injects the resin measured in the cylinder into a mold. a load acquisition step of acquiring the load applied to the screw in response to the injection of the resin from the cylinder into the mold in a plurality of molding cycles; Obtaining operation information including at least one of the amount of movement, amount of rotation, and required time of the screw from when the screw starts an injection operation for injecting resin until the load exceeds a threshold value. At least one statistic of the movement amount, the rotation amount, and the required time is calculated based on the movement information acquisition step and the plurality of movement information acquired in the plurality of molding cycles. The method includes a step of calculating a statistic, and a step of determining whether the measured resin is in good condition based on the statistic.

According to the present invention, it is possible to determine whether the condition of the weighed resin is good or bad.

FIG. 1 is a configuration diagram of an injection molding system according to an embodiment. FIG. 2 is a schematic configuration diagram of the injection device. FIG. 3 is a configuration diagram of the determination device according to the embodiment. FIG. 4 is a table illustrating a threshold table. FIG. 5 is a time chart illustrating the time course of the screw load (resin pressure) in the injection process of each molding cycle, with respect to molding cycles repeated three times. FIG. 6 is a flowchart illustrating the flow of the determination method according to the embodiment. FIG. 7 is a configuration diagram of a determination device according to modification 6. FIG. 8 is a configuration diagram of a determination device according to modification example 7. FIG. 9 is a flowchart illustrating the flow of the determination method according to Modification Example 7. FIG. 10 is a configuration diagram of an injection molding system according to modification 13. FIG. 11 is a configuration diagram of another injection molding system according to Modification 13.

[Embodiment]
FIG. 1 is a configuration diagram of an injection molding system SYS according to an embodiment.

The injection molding system SYS includes an injection molding machine 10 and a determination device 70.

The injection molding machine 10 includes a mold clamping device 12, an injection device 14, a machine stand 16, and a control device 18. Note that the arrow D1 in FIG. 1 indicates the forward direction in this embodiment. Arrow D2 in FIG. 1 indicates the rear direction in this embodiment. The posterior direction is the opposite direction to the anterior direction.

The mold clamping device 12 is a device that opens and closes the mold 20. The mold clamping device 12 is arranged in front of the injection device 14. Note that the mold 20 opens and closes in the front and rear directions. The mold 20 in the closed state forms a cavity 20c. The mold 20 in FIG. 1 is in a closed state. The mold clamping device 12 can apply clamping force to the mold 20 so that the mold 20 is maintained in a closed state. However, a more detailed explanation of the mold clamping device 12 will be omitted.

The machine stand 16 supports the mold clamping device 12 and the injection device 14. However, the machine stand 16 may support only the injection device 14 out of the mold clamping device 12 and the injection device 14. A guide rail 22 is installed on the machine stand 16. The guide rail 22 extends in the front-rear direction.

The injection device 14 is supported by a slide base 24. The slide base 24 is guided by the guide rail 22 and slides in the front and rear directions. Therefore, the injection device 14 slides in the front and back direction together with the slide base 24.

The injection device 14 includes a cylinder 26. The cylinder 26 is a cylindrical member that extends toward the front of the injection device 14 .

FIG. 2 is a schematic diagram of the injection device 14.

The axis LA of the cylinder 26 extends parallel to the front-rear direction. The cylinder 26 includes a hopper 28, a heater 30, a temperature sensor 31, a nozzle 32, and a screw 34. In addition, the injection device 14 further includes a first drive device 36, a second drive device 38, and a pressure sensor 40.

The hopper 28 is arranged at the rear end 26r of the cylinder 26. The hopper 28 stores resin solids (pellets). The resin is a raw material for molded products produced by the injection molding machine 10. Further, the hopper 28 has a supply port 28o. The resin in the hopper 28 is supplied into the cylinder 26 via the supply port 28o.

The heater 30 heats the cylinder 26. By heating the cylinder 26, the resin inside the cylinder 26 is heated. The heater 30 includes, for example, a plurality of band heaters. A plurality of band heaters are wrapped around the cylinder 26.

The temperature sensor 31 is a sensor that outputs a detection signal according to the temperature of the cylinder 26. A detection signal from the temperature sensor 31 is input to the control device 18 . The temperature sensor 31 is, for example, a thermocouple. The temperature sensor 31 is arranged on the surface of the cylinder 26 or in a hole formed in the surface of the cylinder 26. The cylinder 26 may include a plurality of temperature sensors 31 (see also FIG. 2). Note that a detailed explanation of the control device 18 will be given later.

The nozzle 32 is attached to the front end 26f of the cylinder 26. Further, the nozzle 32 is connected to the mold 20. The nozzle 32 has an injection port 32p for injecting resin. When the nozzle 32 and the mold 20 are connected, the resin inside the cylinder 26 is injected into the cavity 20c from the injection port 32p.

The screw 34 is arranged inside the cylinder 26. The axis LA of the cylinder 26 is also the axis of the screw 34. The screw 34 has a flight portion 42, a screw head 44, a check sheet 46, and a backflow prevention ring 48.

The flight portion 42 has a single spiral shape and is formed on the surface of the screw 34. However, the flight portion 42 may have a double helical shape. The flight portion 42 forms a flow path 50 inside the cylinder 26 together with the inner wall 26 i of the cylinder 26 . The flow path 50 is formed to guide the resin supplied into the cylinder 26 from the rear end 26r to the front end 26f.

The screw head 44 is the front end of the screw 34. The check sheet 46 is arranged behind the screw head 44. The backflow prevention ring 48 is arranged between the screw head 44 and the check sheet 46.

When forward pressure is applied to the backflow prevention ring 48, the backflow prevention ring 48 moves forward within the range between the screw head 44 and the check sheet 46 according to the pressure. By moving forward, the backflow prevention ring 48 moves away from the check sheet 46. This causes the backflow prevention ring 48 to open the flow path 50. When the backflow prevention ring 48 contacts the rear end of the screw head 44, the flow path 50 is opened to the maximum extent.

Furthermore, when rearward pressure is applied to the backflow prevention ring 48, the backflow prevention ring 48 moves rearward within the range between the screw head 44 and the check sheet 46 according to the pressure. The backflow prevention ring 48 approaches the check sheet 46 by moving backward. Thereby, the backflow prevention ring 48 closes the flow path 50. When the backflow prevention ring 48 contacts the front end of the check sheet 46, the flow path 50 becomes the narrowest.

The first drive device 36 is a device that rotates the screw 34. The first drive device 36 includes a first motor 52a, a first drive pulley 54a, a first belt member 56a, and a first driven pulley 58a.

The first motor 52a is, for example, a servo motor. The first motor 52a includes a first shaft 60a, a first position and speed sensor 62a, and a first current torque sensor 63a. The first shaft 60a rotates according to the drive current supplied to the first motor 52a. The first position and speed sensor 62a outputs a detection signal according to the rotational position of the first shaft 60a to the control device 18. The first current torque sensor 63a outputs a detection signal to the control device 18 according to the drive current supplied to the first motor 52a, the rotational torque of the first shaft 60a, and the like.

The first drive pulley 54a is connected to the first shaft 60a. The first drive pulley 54a rotates in accordance with the rotation of the first shaft 60a. The first belt member 56a spans the first drive pulley 54a and the first driven pulley 58a. Thereby, the rotation of the first drive pulley 54a is transmitted to the first driven pulley 58a via the first belt member 56a. As a result, the first driven pulley 58a also rotates in accordance with the rotation of the first drive pulley 54a.

The first driven pulley 58a is provided integrally with the screw 34. Therefore, the screw 34 also rotates in accordance with the rotation of the first driven pulley 58a. The screw 34 rotates around the axis LA. By rotating the screw 34, the resin inside the cylinder 26 can be caused to flow along the flow path 50. Note that the rotation direction of the first shaft 60a is switched according to the control of the control device 18. In response to the switching of the rotational direction of the first shaft 60a, the rotational direction of the screw 34 is also switched. By switching the rotational direction of the screw 34, the flow direction of the resin inside the cylinder 26 changes.

In the following description, the direction of rotation of the screw 34 when the resin flows forward is also referred to as the forward rotation direction. Further, the rotational movement of the screw 34 in the forward rotation direction is also referred to as forward rotation.

On the other hand, in the following description, the rotation direction of the screw 34 when the resin flows backward is also described as a reverse rotation direction. Further, the rotational movement of the screw 34 in the reverse rotation direction is also referred to as reverse rotation.

The second drive device 38 is a device that moves the screw 34 forward and backward inside the cylinder 26. The second drive device 38 includes a second motor 52b, a second drive pulley 54b, a second belt member 56b, a second driven pulley 58b, a ball screw 64, and a nut 66.

The second motor 52b is, for example, a servo motor. The second motor 52b includes a second shaft 60b, a second position and speed sensor 62b, and a second current torque sensor 63b. The second shaft 60b rotates according to the drive current supplied to the second motor 52b. The second position and speed sensor 62b outputs a detection signal according to the rotational position of the second shaft 60b to the control device 18. The second current torque sensor 63b outputs a detection signal to the control device 18 according to the drive current supplied to the second motor 52b, the rotational torque of the second shaft 60b, and the like.

The second drive pulley 54b is connected to the second shaft 60b. The second drive pulley 54b rotates in accordance with the rotation of the second shaft 60b. The second belt member 56b spans the second drive pulley 54b and the second driven pulley 58b. Thereby, the rotation of the second drive pulley 54b is transmitted to the second driven pulley 58b via the second belt member 56b. As a result, the second driven pulley 58b also rotates in accordance with the rotation of the second drive pulley 54b.

The second driven pulley 58b is connected to the ball screw 64. The second driven pulley 58b rotates in accordance with the rotation of the second drive pulley 54b transmitted via the second belt member 56b. Therefore, the ball screw 64 also rotates in accordance with the rotation of the second driven pulley 58b.

The nut 66 is screwed onto the ball screw 64. As the ball screw 64 rotates, the relative positional relationship between the nut 66 and the ball screw 64 changes in the axial direction of the ball screw 64. The axis of the ball screw 64 is parallel to the axis LA of the cylinder 26 (screw 34). Therefore, the relative positional relationship between the nut 66 and the ball screw 64 changes in parallel to the axis LA of the screw 34 in accordance with the rotation of the ball screw 64. That is, the relative positional relationship between the nut 66 and the ball screw 64 changes in the front-back direction according to the rotation of the ball screw 64.

The screw 34 and the ball screw 64 are connected so that the rotational force of the ball screw 64 (second shaft 60b) is not transmitted to the screw 34. Note that the connection method is known in the technical field. Therefore, a detailed explanation of the connection method will be omitted.

Since the screw 34 is connected to the ball screw 64, it moves back and forth inside the cylinder 26 as the relative positional relationship between the nut 66 and the ball screw 64 changes in the front and back direction. That is, the screw 34 moves forward and backward in accordance with the rotation of the ball screw 64. However, since the rotational force of the ball screw 64 is not transmitted to the screw 34, the screw 34 does not rotate in response to the rotation of the ball screw 64.

The rotation direction of the second shaft 60b is switched according to the control of the control device 18. In response to the switching of the rotational direction of the second shaft 60b, the rotational direction of the ball screw 64 is also switched. By switching the rotational direction of the ball screw 64, the moving direction of the nut 66 and the screw 34 is switched.

According to the injection device 14 described above, the resin supplied from the hopper 28 into the cylinder 26 flows forward along the flow path 50 as the screw 34 rotates in the forward rotation direction (forward rotation). . While flowing along the flow path 50, the resin melts under the influence of the heat of the heater 30 transmitted via the cylinder 26 and the shear heat generated in the resin by being sheared by the flight portion 42.

The resin located behind the backflow prevention ring 48 flows forward along the flow path 50 and reaches the backflow prevention ring 48 as the screw 34 continues to rotate forward. The resin that has reached the backflow prevention ring 48 presses the backflow prevention ring 48 in the forward direction. As a result, the backflow prevention ring 48 moves forward within the range between the screw head 44 and the check sheet 46 to open the flow path 50. The resin passes through the open channel 50 and reaches a region inside the cylinder 26 in front of the screw head 44 .

In the following description, the area inside the cylinder 26 in front of the screw head 44 is also referred to as a metering area. Further, in the following description, the amount of resin refers to the amount of resin stored in the measurement area unless otherwise specified.

The resin collected in the metering area presses the screw head 44 in the rearward direction. In the following description, the pressure of the resin refers to the pressure in the backward direction applied to the screw 34 by the resin in the metering area, unless otherwise specified.

The pressure sensor 40 is a sensor for detecting the pressure of resin. The pressure sensor 40 is, for example, a load cell. The pressure sensor 40 outputs a detection signal according to the pressure of the resin to the control device 18.

The control device 18 is, for example, a numerical control device. Control device 18 includes one or more processors and one or more memories. A predetermined control program 68 is stored in the memory of the control device 18 . The processor of the control device 18 controls the mold clamping device 12 and the injection device 14 by executing the control program 68. For example, the control device 18 executes the control program 68 to execute a metering process, a pressure reduction process, and an injection process, which will be described below.

Note that the initial position of the screw 34 (screw head 44) at the start of the metering process is the most forward position within the range of movement in the longitudinal direction inside the cylinder 26.

(Weighing process)
The control device 18 controls the first motor 52a to rotate the screw 34 in the forward direction. Thereby, the resin supplied from the hopper 28 into the cylinder 26 is forced forward along the flow path 50. The resin flowing forward inside the cylinder 26 reaches the metering area while being melted. The amount of resin gradually increases as the control device 18 continues to rotate the screw 34 in the forward direction.

Here, the control device 18 controls the first motor 52a so that the screw 34 rotates at a predetermined rotational speed. For example, the memory of the control device 18 stores a predetermined measurement condition value CV in advance. The metering condition value CV includes the target rotational speed of the screw 34 during the metering process. The target rotation speed may be any rotation speed specified by the operator, or may be a rotation speed specified by the manufacturer of the injection molding machine 10. The control device 18 sequentially rotates the screw 34 based on the target rotation speed.

Note that the rotation speed of the screw 34 is the amount of rotation of the screw 34 per unit time. The control device 18 sequentially rotates the screw 34 while appropriately calculating the rotation amount, rotation speed, etc. of the screw 34 based on the detection signal of the second position and speed sensor 62b.

The screw 34 retreats as the amount of resin increases. Here, the control device 18 controls the second motor 52b to prevent the screw 34 from retracting excessively. That is, the control device 18 controls the second motor 52b to adjust the retraction speed (rearward movement speed) of the screw 34. This prevents the pressure of the resin from decreasing excessively as the screw 34 retreats.

Here, the control device 18 controls the second motor 52b so that the pressure of the resin is adjusted to a predetermined pressure while the screw 34 rotates forward. For example, the measurement condition value CV includes a target pressure during the measurement process. Similar to the target rotational speed, the target pressure may be any pressure specified by the operator, or may be a pressure specified by the manufacturer of the injection molding machine 10. The control device 18 adjusts the retraction speed of the screw 34 during the metering process based on the target pressure.

Note that the retraction speed of the screw 34 is the amount of retraction of the screw 34 per unit time. The control device 18 retracts the screw 34 while appropriately calculating the retraction amount (movement amount), retraction speed, etc. of the screw 34 based on the detection signal of the first position and speed sensor 62a.

The screw 34, which retreats as the amount of resin increases, reaches a predetermined position (measuring position) regarding the position of the screw 34. The measuring position is a position behind the initial position of the screw 34 in the measuring process. The control device 18 can accumulate a predetermined amount of resin in the metering area by adjusting the resin pressure to the metering pressure and causing the screw 34 to reach the metering position. When the screw 34 reaches the metering position, the control device 18 controls the first motor 52a to stop the forward rotation of the screw 34. This completes the weighing process.

Note that the measurement condition value CV may include the target temperature of the cylinder 26. In that case, the control device 18 may control the heater 30 based on the target temperature. Thereby, the temperature of the cylinder 26 during the metering process is adjusted based on the target temperature. By adjusting the temperature of the cylinder 26, the temperature of the resin within the cylinder 26 is adjusted. Here, the control device 18 controls the heater 30 while appropriately calculating the temperature of the cylinder 26 based on the detection signal of the temperature sensor 31, for example.

Additionally, as described above, a shear heat is generated as the flight portion 42 shears the resin. This shear heat affects the temperature of the cylinder 26. Here, the greater the rotational speed of the screw 34, the greater the shear heat. On the other hand, the lower the rotational speed of the screw 34, the more suppressed is the increase in shear heat. Based on this, the control device 18 may adjust the temperature of the cylinder 26 by adjusting the rotational speed of the screw 34.

(depressurization process)
After a predetermined amount of resin has been metered into the cylinder 26, the controller 18 begins the depressurization process. In the pressure reduction process, the control device 18 controls the first motor 52a to rotate the screw 34 in the reverse direction. When the screw 34 rotates in the opposite direction, the resin within the metering area flows backward. This reduces the amount of resin. As the amount of resin decreases, the pressure of the resin applied to the screw 34 is reduced.

Furthermore, inertia acts on the screw 34 that rotates in the forward direction during the metering process. Therefore, the screw 34 continues to rotate forward even after reaching the metering position in the metering process. As a result, the amount of resin immediately after measurement strictly exceeds the predetermined amount. The control device 18 can also adjust the resin amount to an amount closer to a predetermined amount by reducing the resin amount in accordance with the reverse rotation of the screw 34 in the pressure reduction process.

Note that the backflow prevention ring 48 is pressed by the resin flowing from the metering area to the rear of the backflow prevention ring 48 in response to the control device 18 rotating the screw 34 in the reverse direction. This causes the backflow prevention ring 48 to move rearward. When the backflow prevention ring 48 moves rearward, it comes into contact with the check sheet 46 located behind the backflow prevention ring 48 . When the backflow prevention ring 48 comes into contact with the check sheet 46, the flow path 50 is closed. By closing the flow path 50, the resin accumulated in the metering area cannot reach the rear of the backflow prevention ring 48. As a result, the amount of resin is prevented from decreasing more than necessary.

The control device 18 controls the screw 34 based on the target pressure reduction value. The target pressure reduction value indicates the target pressure of the resin pressure to be reduced in the pressure reduction step. The target pressure reduction value is, for example, atmospheric pressure. However, the operator or the manufacturer of the injection molding machine 10 may set the target pressure reduction value in the control device 18. The control device 18 ends the pressure reduction process when the resin pressure reaches the target pressure reduction value.

(injection process)
The control device 18 starts the injection process after the decompression process is completed. Note that the injection process is performed with the mold 20 in a closed state. Therefore, the control device 18 controls the mold clamping device 12 to close the mold 20 before the injection process is started.

In the injection process, the control device 18 controls the second motor 52b to advance the screw 34. Thereby, the resin within the metering area is injected toward the cavity 20c of the mold 20 via the nozzle 32. The injected resin is solidified within the cavity 20c to complete the molded product.

The molding cycle of the injection molding machine 10 includes the above-mentioned metering process, pressure reduction process, and injection process. The injection molding machine 10 can mass-produce molded products by repeatedly performing a molding cycle.

FIG. 3 is a configuration diagram of the determination device 70 according to the embodiment.

The determination device 70 is an electronic device (computer) that determines the quality of the resin measured by the injection molding machine 10.

The determination device 70 is communicably connected to the control device 18. For example, the determination device 70 communicates with the control device 18 via a predetermined network. Thereby, the determination device 70 and the control device 18 can mutually acquire owned data. The predetermined network may be a wireless network or a wired network. The predetermined network is realized using, for example, serial communication, optical communication, wireless LAN, or the like.

The determination device 70 includes a display section 72, an operation section 74, a storage section 76, and a calculation section 78.

The display unit 72 is a display device including a display screen 72d. The material of the display screen 72d includes, for example, liquid crystal or OEL (Organic Electro-Luminescence).

The operation unit 74 is an input device that accepts information input to the determination device 70. The operation unit 74 includes, for example, an operation panel 74a, a touch panel 74b, and the like. However, the operation unit 74 may include a keyboard, a mouse, and the like. The touch panel 74b is installed on the display screen 72d.

The storage unit 76 includes a storage circuit. This storage circuit includes one or more memories such as RAM (Random Access Memory) and ROM (Read Only Memory).

The storage unit 76 stores a determination program 80. The determination program 80 is a program for causing the determination device 70 to execute the determination method according to this embodiment.

Note that the data stored in the storage unit 76 is not limited to the determination program 80. As described above, the storage unit 76 may store various data as necessary. For example, the storage unit 76 may store the resin pressure obtained based on the detection signal of the pressure sensor 40. The storage unit 76 also stores, for example, the torque of the first motor 52a (first torque) obtained based on the detection signal of the first current torque sensor 63a, and the torque of the first motor 52a obtained based on the detection signal of the second current torque sensor 63b. The torque of the two motors 52b (second torque), etc. may be stored. Furthermore, the storage unit 76 may store, for example, the drive current and voltage of the first motor 52a or the second motor 52b, the temperature of the cylinder 26, and the like. All of the above pressure, first torque, second torque, drive current, voltage, temperature, etc. may be acquired from the control device 18.

The calculation unit 78 includes a processing circuit. This processing circuit includes, for example, one or more processors. However, the processing circuit of the calculation unit 78 may include an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). Further, the processing circuit of the calculation unit 78 may include a discrete device.

The calculation unit 78 includes a load acquisition unit 82, a threshold value determination unit 84, an operation information acquisition unit 86, a statistics calculation unit 88, a range determination unit 90, a determination unit 92, a correction command unit 94, and a display control unit 96. The load acquisition section 82, the threshold value determination section 84, the operation information acquisition section 86, the statistics calculation section 88, the range determination section 90, the determination section 92, the correction command section 94, and the display control section 96 are as follows: This is realized by the processor of the calculation unit 78 executing the determination program 80. However, the load acquisition section 82, the threshold value determination section 84, the operation information acquisition section 86, the statistics calculation section 88, the range determination section 90, the determination section 92, the correction command section 94, and the display control section 96. At least a portion of may be realized by the aforementioned integrated circuit, discrete device, or the like.

The load acquisition unit 82 acquires the load LO applied to the screw 34 in response to resin being injected from the cylinder 26 to the mold 20. The load LO is, for example, resin pressure. Therefore, the load acquisition unit 82 acquires the resin pressure from the control device 18, for example via a predetermined network.

The load acquisition unit 82 acquires the load LO in each of a plurality of molding cycles. The storage unit 76 may store a plurality of loads LO acquired in a plurality of molding cycles.

The threshold value determination unit 84 determines the first threshold value TH1 based on the threshold value table TB. The first threshold TH1 is a value used by the motion information acquisition unit 86 for processing. The processing contents of the motion information acquisition unit 86 will be described later. The threshold table TB is a data table in which a plurality of first threshold values TH1 are stored according to at least one of a plurality of types of screws 34 and a plurality of types of resin. The threshold table TB is stored in advance in the storage unit 76.

The threshold determining unit 84 searches the threshold table TB for a first threshold TH1 corresponding to the type of screw 34 provided in the injection molding machine 10 and the type of resin supplied to the inside of the cylinder 26. The type of screw 34 provided in the injection molding machine 10 and the type of resin to be supplied into the cylinder 26 are specified by the operator to the threshold determining unit 84 via the operating unit 74, for example.

FIG. 4 is a table illustrating the threshold table TB.

A plurality of types of screws 34 are stored in the first column (types of screws 34) of the threshold table TB illustrated in FIG. For illustrative purposes, FIG. 4 shows multiple types of screws 34, including a full-flight screw, a barrier-flight screw, and a highly plasticized screw. For example, as described above, the screw 34 rotates forward in the metering process to force-feed the resin supplied into the cylinder 26 forward along the flow path 50. Here, the ability to force-feed the resin supplied into the cylinder 26 in the forward direction along the flow path 50 differs depending on the type of the screw 34. Therefore, the measurement condition value CV for obtaining a good molded product differs depending on the type of screw 34.

A plurality of resin types are stored in the second column (resin type) of the threshold table TB illustrated in FIG. 4. For illustrative purposes, FIG. 4 shows PA (polyamide), PBT (polybutylene terephthalate), and PE (polyethylene) as a plurality of types of resin. For example, the temperature at which the resin melts, the viscosity of the resin melted in the measuring process, and the density of the resin melted in the measuring process differ depending on the type of resin.

The third column (first threshold) of the threshold table TB illustrated in FIG. 4 stores a plurality of first thresholds TH1 (th1 to th7) corresponding to each data in the first column and the second column. . The specific value of each of the plurality of first threshold values TH1 is determined in advance based on experiments. Note that, as shown in the bottom row of FIG. 4, the first threshold value TH1 depending on the type of screw 34 may be stored in the threshold value table TB regardless of the type of resin. Furthermore, regardless of the type of screw 34, the first threshold value TH1 depending on the type of resin may be stored in the threshold value table TB. Further, the injection molding machine 10 may produce a molded product using a mixed resin, which is a mixture of multiple types of resins, as a raw material. In that case, a plurality of first threshold values TH1 according to the proportions of various resins included in the mixed resin may be stored in the threshold table TB.

The operation information acquisition unit 86 acquires operation information INF regarding the screw 34. The operation information INF includes, for example, the time required from when the screw 34 starts an injection operation (forward operation) for injecting resin into the mold 20 until the load LO exceeds the first threshold value TH1.

The operation information acquisition unit 86 acquires operation information INF in a plurality of molding cycles. The storage unit 76 may store a plurality of pieces of operation information INF acquired by the operation information acquisition unit 86 in a plurality of molding cycles.

In the following description, unless otherwise specified, the required time refers to the time required from when the screw 34 starts the injection operation for injecting the resin into the mold 20 until the load LO exceeds the first threshold value TH1. .

The statistic calculation unit 88 calculates the statistic ST based on a plurality of pieces of operation information INF acquired during a plurality of molding cycles. For example, the statistics calculation unit 88 is based on a predetermined number of pieces of operation information INF acquired from a predetermined number of molding cycles before the last molding cycle to the last molding cycle. , calculate the statistic ST.

The predetermined number may be instructed by the operator to the statistics calculation unit 88 via the operation unit 74, or may be set in advance by the manufacturer of the injection molding machine 10. Further, the storage unit 76 may store the statistic ST calculated by the statistic calculation unit 88.

The statistic ST is, for example, a representative value of a plurality of required times. That is, the statistic calculation unit 88 calculates the average value, minimum value, maximum value, mode, or weighted median value of a plurality of required times obtained in a plurality of molding cycles as a statistic ST. Good too. Note that the average value may be any one of an arithmetic average value, a weighted average value, a weighted harmonic average value, a harmonic average value, a pruned average value, and a sum of squares average value.

The operator may also instruct the statistic calculation unit 88 via the operation unit 74 the type of value to be calculated as the statistic ST, among the average value, minimum value, maximum value, mode, or weighted median value. good. Further, the manufacturer of the injection molding machine 10 may preset the type of value to be calculated as the statistic ST among the average value, minimum value, maximum value, mode, or weighted median value of the required time. .

FIG. 5 is a time chart illustrating the time course of the load LO (resin pressure) on the screw 34 in the injection process of each molding cycle, with respect to a molding cycle that is repeated three times.

In FIG. 5, the vertical axis indicates the load LO (resin pressure). Further, in FIG. 5, the horizontal axis indicates time. FIG. 5 shows a first transition CYC1, a second transition CYC2, and a third transition CYC3. The first transition CYC1 indicates the transition of the resin pressure in the injection step of the first molding cycle among the three repeated molding cycles. The second transition CYC2 indicates the transition of the resin pressure in the injection process of the second molding cycle among the three repeated molding cycles. The third transition CYC3 indicates the transition of the resin pressure in the injection step of the third molding cycle among the three repeated molding cycles.

In FIG. 5, the first transition CYC1, the second transition CYC2, and the third transition CYC3 are drawn overlappingly with respect to the start time t0 of the injection process for comparison. Time point t1 indicates the time point in the first molding cycle when the resin pressure reaches the first threshold value TH1. The required time τ1 for the first molding cycle is the elapsed time from time t0 to time t1. Time t2 indicates the time when the resin pressure reaches the first threshold value TH1 in the second molding cycle. The required time τ2 for the second molding cycle is the elapsed time from time t0 to time t2. Time t3 indicates the time when the resin pressure reaches the first threshold value TH1 in the third molding cycle. The required time τ3 for the third molding cycle is the elapsed time from time t0 to time t3. The statistic ST calculated by the statistic calculation unit 88 using the three required times (τ1, τ2, τ3) in FIG. 5 is, for example, ST=(τ1+τ2+τ3)/3.

Note that, considering the possibility that outliers (abnormal values) may be accidentally included in a plurality of required times, it is preferable that the representative value is an average value, a mode, or a weighted median value. This reduces the risk of an outlier being selected as a representative value (maximum value, minimum value).

The range determining unit 90 determines the allowable range AR of the operation information INF (required time). The allowable range AR is determined based on the statistic ST (representative value). The range determining unit 90 determines the allowable range AR, for example, by adding a predetermined offset to the representative value.

For example, the operation information acquisition unit 86 acquires the required time for each of the first to Mth molding cycles (M: natural number, where M≧2). Further, the statistics calculation unit 88 calculates the average time of the plurality of required times obtained during the first to Mth molding cycles as a representative value. In this case, the range determining unit 90 calculates an upper limit value larger than the representative value and a lower limit value smaller than the representative value by adding a predetermined offset to the representative value. This determines the allowable range AR. The storage unit 76 may store the allowable range AR determined by the range determination unit 90.

Note that the range determining unit 90 may use different offsets depending on the type of representative value. For example, the range determining unit 90 may use different offsets depending on when the representative value is the maximum value and when the representative value is the mode.

For example, if the representative value is the maximum value, the range determining unit 90 may directly use the maximum value as the upper limit of the allowable range AR. Similarly, when the representative value is the minimum value, the range determining unit 90 may directly use the minimum value as the lower limit value of the allowable range AR. In connection with this, the above-mentioned statistic calculation unit 88 may calculate a plurality of types of statistic ST (representative value) as necessary.

Further, the range determining unit 90 may determine only one of the upper limit value and the lower limit value of the motion information INF. When only the upper limit value is determined, the entire range below the upper limit value is the allowable range AR. When only the lower limit value is determined, the entire range above the lower limit value is the allowable range AR.

The determination unit 92 determines the quality of the weighed resin using the allowable range AR based on the statistic ST. Based on the comparison between the allowable range AR and the operation information INF acquired by the operation information acquisition unit 86 in the molding cycle performed after the allowable range AR is determined, the determination unit 92 determines the resin weighed in the molding cycle. Determine whether the condition is good or bad.

For example, the range determining unit 90 determines the allowable range AR based on a plurality of required times acquired during the first to M-th molding cycles. After that, in the Nth molding cycle, the operation information acquisition unit 86 acquires the required time (N: natural number, where N>M). The determination unit 92 compares the allowable range AR with the required time acquired in the N-th molding cycle.

The time required for the Nth molding cycle may fall within the allowable range AR. In this case, the determining unit 92 determines that the resin in the N-th molding cycle is in a good state. That is, compared to the state of the resin measured in the first to Mth molding cycles, the state of the resin measured in the Nth molding cycle does not vary and is stable.

On the other hand, the time required for the Nth molding cycle may not fall within the allowable range AR. In that case, the determining unit 92 determines that the resin condition in the N-th molding cycle is not good. That is, compared to the state of the resin measured in the first to Mth molding cycles, the state of the resin measured in the Nth molding cycle varies widely and is not stable.

The correction command unit 94 outputs a correction signal based on the determination result of the determination unit 92. The correction signal is a signal for correcting the measurement condition value CV. The correction command unit 94 outputs a correction signal to the control device 18 when the determination unit 92 determines that the resin condition is not good.

If the required time compared with the allowable range AR is larger than the allowable range AR, the correction command unit 94 outputs a correction signal to correct the measurement condition value CV to be smaller than the current measurement condition value CV.

In that case, the control device 18 corrects the metric condition value CV to be smaller than the current metric condition value CV based on the input correction signal. That is, the control device 18 makes at least one of the target temperature of the cylinder 26, the target rotational speed of the screw 34, and the target pressure of the resin smaller than the current value based on the input correction signal. .

The reason why the time required for the N-th molding cycle exceeds the allowable time is that the viscosity of the resin in the N-th molding cycle is excessively lower than the viscosity of the resin in the 1st to M-th molding cycles. In other words, since the viscosity of the resin measured in the N-th measuring process is low, it takes a long time for the load LO to reach the first threshold value TH1 in the N-th injection process.

Therefore, if the time required for the Nth molding cycle exceeds the allowable time, the viscosity of the resin in the (N+1)th and subsequent molding cycles will be greater than the viscosity of the resin in the Nth molding cycle. Correct the measurement condition value CV. Thereby, variations in the state of the resin can be reduced in the (N+1)th and subsequent molding cycles.

On the other hand, if the required time compared with the allowable range AR is smaller than the allowable range AR, the correction command unit 94 outputs a correction signal to correct the measurement condition value CV to be larger than the current measurement condition value CV.

In that case, the control device 18 corrects the metric condition value CV to be larger than the current metric condition value CV based on the input correction signal. That is, the control device 18 makes at least one of the target temperature of the cylinder 26, the target rotational speed of the screw 34, and the target pressure of the resin larger than the current value based on the input correction signal. .

The reason why the time required for the N-th molding cycle is less than the allowable time is that the viscosity of the resin in the N-th molding cycle is excessively higher than the viscosity of the resin in the 1st to M-th molding cycles. That is, since the viscosity of the resin measured in the N-th measuring process is high, the load LO reaches the first threshold value TH1 in a short time in the N-th injection process.

Therefore, if the time required for the N-th molding cycle is less than the allowable time, the above-mentioned method is applied so that the viscosity of the resin in the (N+1)th and subsequent molding cycles is smaller than the viscosity of the resin in the N-th molding cycle. Correct the weighing condition value CV as shown below. Thereby, variations in the state of the resin can be reduced in the (N+1)th and subsequent molding cycles.

Note that the correction command unit 94 may include the correction amount of the measurement condition value CV in the correction signal. In that case, the control device 18 corrects the measurement condition value CV based on the correction amount included in the correction signal.

The amount of correction of the measurement condition value CV is determined, for example, according to the amount of deviation from the allowable range AR for a predetermined period of time. In that case, the correction command unit 94 may determine the correction amount using, for example, a data table in which a plurality of correction amounts are stored depending on the deviation amount. However, the correction amount may be a constant amount regardless of the amount of deviation from the allowable range AR for a predetermined period of time.

The display control unit 96 controls the display unit 72 to display various data stored in the storage unit 76 on the display screen 72d. The display control unit 96 displays various data on the display screen 72d, for example, in response to instructions from an operator.

Furthermore, it is preferable that the display control unit 96 controls the display unit 72 to display the determination result of the determination unit 92 on the display screen 72d. This allows the operator to know whether the condition of the resin is good or bad.

Based on the determination result displayed on the display screen 72d, the operator may instruct the determination device 70 (correction command unit 94) whether or not to correct the measurement condition value CV. Further, the operator may instruct the determination device 70 (correction command section 94) to correct the aforementioned measurement condition value CV based on the determination result displayed on the display screen 72d.

FIG. 6 is a flowchart illustrating the flow of the determination method according to the embodiment.

The determination device 70 can execute the determination method illustrated in FIG. 6. The determination method includes a load acquisition step S1, a load determination step S2, an operation information acquisition step S3, and a process selection step S4. The determination method in FIG. 6 further includes a calculation feasibility determination step S5, a statistic calculation step S6, a range determination step S7, a state determination step (determination step) S8, and a correction command step S9.

In the load acquisition step S1, the load acquisition unit 82 acquires the load LO of the screw 34. This load LO is the load LO applied to the screw 34 in response to the screw 34 performing an injection operation in the injection process. The load LO is, for example, resin pressure.

The load LO increases as the injection operation is performed. In the load determination step S2, for example, the operation information acquisition unit 86 determines whether the load LO exceeds the first threshold TH1.

Note that the first threshold value TH1 is determined by the threshold value determination unit 84 based on the type of screw 34 and the type of resin before the load determination step S2 is started. The timing at which the threshold value determination unit 84 determines the first threshold value TH1 is not particularly limited as long as it is before the load determination step S2 is performed. Therefore, the threshold value determination unit 84 may determine the first threshold value TH1, for example, before the injection molding machine 10 starts operating.

If the load LO does not exceed the first threshold TH1 (LO≦TH1), the load acquisition step S1 is continued. When the load LO exceeds the first threshold TH1 (LO>TH1), the operation information acquisition step S3 is started.

In the operation information acquisition step S3, the operation information acquisition unit 86 acquires operation information INF (required time). The acquired motion information INF is stored in the storage unit 76.

In the process selection step S4, for example, the range determining unit 90 determines whether the allowable range AR has been determined. This determination is made by checking whether the storage unit 76 stores the allowable range AR.

If the allowable range AR is undetermined (S4: NO), calculation possibility determination step S5 is started. If the allowable range AR has been determined (S4: YES), a state determination step S8 is started.

In calculation possibility determination step S5, for example, the statistic calculation unit 88 determines whether the statistic ST can be calculated. In the example of FIG. 6, the statistic ST is calculated using a predetermined number of motion information INF. Therefore, the statistic calculation unit 88 determines that the statistic ST can be calculated when the number of motion information INF stored in the storage unit 76 reaches a predetermined number.

If it is possible to calculate the statistic ST (S5: YES), a statistic calculation step S6 is started. If it is not possible to calculate the statistic ST (S5: NO), the flow from load acquisition step S1 to calculation feasibility determination step S5 is executed again in response to the injection molding machine 10 starting the next molding cycle. Ru. Note that since the operation information acquisition step S3 is performed every time a molding cycle is executed, the number of acquired operation information INF will eventually reach a predetermined number.

In the statistic calculation step S6, the statistic calculation unit 88 calculates the statistic ST. The statistic ST calculated in the example of FIG. 6 is a representative value of a predetermined number of motion information INF (required time). The calculated statistic ST is stored in the storage unit 76.

In the range determination step S7, the range determination unit 90 determines the allowable range AR based on the statistical amount ST. The determined allowable range AR is stored in the storage unit 76.

In the condition determination step S8, the determination unit 92 determines whether the condition of the resin is good or bad based on the allowable range AR and the operation information INF.

If the operation information INF (required time) falls within the allowable range AR, the determination unit 92 determines that the resin is in good condition. In this case, the determination method of FIG. 6 ends. However, as long as the injection molding machine 10 repeats the molding cycle, the determination device 70 may repeatedly execute the determination method of FIG. 6 (RETURN→START).

If the required time included in the operation information INF deviates from the allowable range AR, the determination unit 92 determines that the resin condition is not good. In this case, correction command step S9 is started.

In the correction command step S9, the correction command unit 94 outputs a correction signal to the control device 18. Thereby, the control device 18 can correct the measurement condition value CV based on the correction signal.

The determination method shown in FIG. 6 ends when the correction command step S9 is completed. However, as described above, the injection molding machine 10 can repeat the molding cycle even after the determination method of FIG. 6 is completed. In the molding cycle executed after the correction command step S9 is performed, control is performed based on the corrected measurement condition value CV.

As described above, according to this embodiment, it is possible to determine whether the condition of the measured resin is good or bad. Moreover, according to the present embodiment, the measurement condition value CV can be automatically corrected when it is determined that the resin condition is not good. This allows stable production to continue. Therefore, productivity is improved. Further, the operator of the injection molding machine 10 does not have to take the trouble of adjusting the measurement condition value CV. Therefore, the operator's work burden is reduced.

Additionally, there are recycled resins, fiber-reinforced resins, etc. as resins used for producing molded products. Recycled resin is resin containing recycled material. Fiber-reinforced resin is a resin containing reinforcing fibers as a material. The reinforcing fiber is, for example, glass fiber. The physical properties of the recycled resin and the fiber-reinforced resin are not stable compared to the physical properties of virgin material made from new materials. Therefore, when the injection molding machine 10 produces a molded product using recycled resin, fiber-reinforced resin, etc., the state of the resin accumulated in the measuring area in the measuring process may change during production. According to this embodiment, even when producing using recycled resin, fiber-reinforced resin, etc., the determination device 70 can determine the quality of the resin weighed during production. Furthermore, the injection molding machine 10 can automatically correct the measurement condition value CV based on a correction signal output according to the determination result. Therefore, the injection molding machine 10 can continue to perform good molding even when producing using recycled resin, fiber-reinforced resin, or the like.

[Modified example]
Modifications of the above embodiment will be described below. However, descriptions that overlap with those of the above embodiments will be omitted as much as possible in the following description. Elements already described in the embodiments are given the same reference numerals as in the embodiments, unless otherwise specified.

(Modification 1)
The operation information INF is not limited to the required time. For example, the operation information acquisition unit 86 provides operation information about the amount of movement of the screw 34 from when the screw 34 starts an injection operation for injecting resin into the mold 20 until the load LO exceeds the first threshold TH1. May be included in INF.

Further, when the screw 34 rotates during the injection process, the operation information acquisition unit 86 determines that the load LO exceeds the first threshold TH1 after the screw 34 starts the injection operation for injecting the resin into the mold 20. The amount of rotation of the screw 34 up to this point may be included in the operation information INF.

Note that the above case in which the screw 34 rotates during the injection process is not only a case in which the control device 18 controls the rotation of the first motor 52a to rotate the first shaft 60a, but also a case in which the excitation of the first motor 52a is canceled. This also includes a case where the first shaft 60a is in a free state. That is, when the first shaft 60a is in a free state during the injection process, the first shaft 60a rotates according to the viscous resistance of the resin acting on the flight portion 42 of the screw 34.

According to this modification, the operation information acquisition unit 86 determines the amount of movement, amount of rotation, and required time of the screw 34 from when the screw 34 starts the injection operation until the load LO exceeds the first threshold TH1. At least one of them is included in the operation information INF.

The statistic calculation unit 88 calculates at least one of the above-mentioned required time statistic ST, movement amount statistic ST, and rotation amount statistic ST. The operator instructs the determination device 70 (motion information acquisition section 86, statistics calculation section 88) which item to use to calculate the statistics ST among the above-mentioned required time, movement amount, and rotation amount. You may give instructions. The operator's instructions are given via the operation unit 74, for example. Further, the manufacturer of the injection molding machine 10 may preset in the determination device 70 which item is used to calculate the statistical amount ST among the above-mentioned required time, amount of movement, and amount of rotation. .

According to this modification, a plurality of statistics ST are calculated. The range determining unit 90 may determine a plurality of allowable ranges AR according to each statistic ST. For example, the range determining unit 90 may determine the allowable range AR based on representative values of a plurality of movement amounts and the allowable range AR based on representative values of a plurality of rotation amounts.

If multiple allowable ranges AR are determined, the determination unit 92 may use each allowable range AR to determine whether the state of the resin is good or bad.

For example, the allowable range AR regarding the required time is determined based on the required time obtained during each of the first to Mth molding cycles. The determination unit 92 compares the required time obtained in the N-th molding cycle with the allowable range AR regarding the required time, and determines whether the state of the resin in the N-th molding cycle is good or bad.

Furthermore, an allowable range AR regarding the movement amount is determined based on the movement amount of the screw 34 obtained during each of the first to Mth molding cycles. The determination unit 92 also compares the amount of movement acquired in the N-th molding cycle with the allowable range AR regarding the amount of movement, and further determines whether the state of the resin in the N-th molding cycle is good or bad.

Furthermore, an allowable range AR regarding the amount of rotation is determined based on the amount of rotation of the screw 34 obtained during each of the first to Mth molding cycles. The determination unit 92 also compares the amount of rotation acquired in the N-th molding cycle with the allowable range AR regarding the amount of rotation, and further determines whether the state of the resin in the N-th molding cycle is good or bad.

According to the above example, the quality of the resin in the N-th molding cycle is determined based on three types of operation information INF: the required time, the amount of movement of the screw 34, and the amount of rotation of the screw 34. In this case, there is a possibility that the three types of determination results made regarding the state of the resin in the Nth molding cycle are different from each other.

For example, in the determination using the allowable range AR regarding the required time and the determination using the allowable range AR regarding the amount of movement, it is determined that the state of the resin in the N-th molding cycle is good. On the other hand, in the determination using the allowable range AR regarding the amount of rotation, there is a possibility that it will be determined that the condition of the resin in the N-th molding cycle is not good.

If the results of multiple determinations regarding the state of the resin in the same molding cycle are different from each other, the final determination result is determined using, for example, majority voting. For example, in the above example, the state of the resin in the Nth molding cycle is determined based on three types of operation information INF. Furthermore, the number of times the resin was determined to be in good condition in the N-th molding cycle is two types, which are the majority of the three types of operation information INF. In this case, the determination unit 92 ultimately determines that the resin in the N-th molding cycle is in good condition.

However, if the results of multiple determinations made regarding the condition of the resin in the same molding cycle are different from each other, the determining section 92 determines that the resin is in good condition only when it is determined that the resin condition is good in all of the multiple determinations. It is more preferable to determine that the condition is good.

For example, in the above example, the state of the resin in the N-th molding cycle is determined based on three types of operation information INF. In one type (rotation amount) of the three types of determination based on the operation information INF, it is determined that the condition of the resin in the N-th molding cycle is not good. In this case, the determining unit 92 ultimately determines that the resin condition in the N-th molding cycle is not good.

By determining that the resin is in good condition only when it is determined that the resin is in good condition in all of the multiple determinations, the risk of overlooking resin that is not in good condition is reduced.

(Modification 2)
Based on a comparison between the allowable range AR and the operation information INF acquired by the operation information acquisition unit 86 in the molding cycle performed before the allowable range AR was determined, the determination unit 92 determines whether the measured amount is measured in the molding cycle. It is also possible to judge whether the condition of the resin is good or bad.

For example, the range determining unit 90 determines the allowable range AR based on a plurality of required times acquired during the first to Mth molding cycles. The determination unit 92 may compare the allowable range AR with the required time acquired in the L-th molding cycle performed before the M-th molding cycle (L: natural number, where L≦M). Thereby, it is possible to determine whether the condition of the resin measured in the first to Mth molding cycles used to calculate the allowable range AR is good or bad.

(Modification 3)
In the embodiment, an example has been described in which the statistic ST is calculated based on a plurality of required times acquired during the first to Mth molding cycles. However, the plurality of required times may not include the required time acquired in the first molding cycle.

For example, the statistic calculation unit 88 may calculate the statistic ST based on a plurality of required times acquired during the K-th to M-th molding cycles (K: natural number, where 2≦K<M ). The allowable range AR is determined based on a plurality of required times obtained during the K-th to M-th molding cycles. Immediately after the injection molding machine 10 starts operating, the operating state may not be stable. In this regard, according to this modification, the statistic ST can be calculated by excluding the required time obtained in a molding cycle performed while the operating state of the injection molding machine 10 is not stable.

(Modification 4)
The operator may instruct the determination device 70 to set the first threshold TH1. In that case, the threshold determining section 84 may be omitted. However, the operator may change the first threshold value TH1 determined by the threshold value determination unit 84 via the operation unit 74.

The operator inputs the first threshold TH1 into the determination device 70, for example, via the operation unit 74. The operation information acquisition unit 86 acquires operation information INF based on a comparison between the input first threshold TH1 and the load LO applied to the screw 34.

(Modification 5)
The load acquisition unit 82 may acquire at least one of the torque of the first motor 52a (first torque) and the torque of the second motor 52b (second torque) as the load LO applied to the screw 34. The first threshold value TH1 with which the torque of the first motor 52a is compared and the first threshold value TH1 with which the torque of the second motor 52b is compared may be different.

The operation information acquisition unit 86 determines the shorter of the time required for the first torque to reach the first threshold TH1 and the time required for the second torque to reach the first threshold TH1 as the operation information INF. You can also obtain it as

However, the operation information acquisition unit 86 calculates the longer of the time required for the first torque to reach the first threshold value TH1 and the time required for the second torque to reach the first threshold value TH1. It may also be acquired as information INF.

Note that the first torque may be the disturbance load torque of the first motor 52a. Similarly, the second torque may be the disturbance load torque of the second motor 52b. In that case, the disturbance load torque of the first motor 52a or the second motor 52b may be estimated using a disturbance estimation observer.

(Modification 6)
FIG. 7 is a configuration diagram of a determination device 701 (70) according to modification 6.

The determination device 701 differs from the embodiment (see also FIG. 3) at least in that it includes a control restriction section 98 instead of the correction command section 94.

The control restriction section 98 outputs a predetermined control signal based on the determination result of the determination section 92. This control signal is a signal to limit the operation of the injection molding machine 10. The control restriction unit 98 outputs a control signal to the control device 18 when the determination unit 92 determines that the state of the resin is not good.

When a control signal is input from the control restriction section 98, the control device 18 stops the operation of the injection molding machine 10. As a result, when it is determined that the condition of the resin is not good, production of the molded product is temporarily interrupted. While the production of molded products is suspended, the operator can inspect the injection molding machine 10, adjust the weighing condition value CV, etc.

The determination device 701 may include both the control restriction section 98 and the correction command section 94. In this case, the correction command section 94 and the control restriction section 98 may be used depending on the amount of deviation of the operation information INF (required time) from the allowable range AR, for example.

For example, if the above deviation amount is less than a predetermined deviation amount, the correction command unit 94 outputs a correction signal to correct the measurement condition value CV. In this case, the control limiter 98 does not output a control signal. On the other hand, if the deviation amount is greater than or equal to the predetermined deviation amount, the control restriction section 98 outputs a control signal to restrict the operation of the injection molding machine 10. In this case, the correction command unit 94 does not output a correction signal. Thereby, it is possible to suppress an increase in the frequency with which the operation of the injection molding machine 10 is restricted.

(Modification 7)
FIG. 8 is a configuration diagram of a determination device 702 (70) according to Modification Example 7.

The statistic calculation unit 88 may calculate the degree of dispersion based on the plurality of pieces of motion information INF as the statistic ST. For example, the statistics calculation unit 88 may calculate the variance, deviation, or coefficient of variation based on the plurality of pieces of motion information INF. The deviation is, for example, standard deviation. However, the statistic calculation unit 88 may calculate the average deviation as the deviation.

The degree of dispersion indicates the degree of dispersion of the plurality of pieces of operation information INF. For example, the operation information INF includes the required time. In this case, the degree of dispersion indicates the degree of variation in required time between multiple molding cycles.

The determination unit 92 compares the degree of dispersion with a predetermined threshold (second threshold) TH2. The second threshold TH2 is stored in the storage unit 76 in advance. The second threshold TH2 is determined in advance based on experiments. Like the first threshold TH1, the second threshold TH2 may be determined depending on the type of screw 34 and the type of resin.

If the degree of dispersion is less than or equal to the second threshold TH2, the determination unit 92 determines that the resin is in good condition. On the other hand, if the degree of dispersion exceeds the second threshold TH2, the determination unit 92 determines that the resin is not in good condition.

Note that the resin determined based on the degree of dispersion is the resin that was weighed in the molding cycle in which a plurality of pieces of operation information INF for calculating the degree of dispersion were acquired.

For example, the degree of dispersion is calculated based on a plurality of pieces of operation information INF acquired during the K-th to M-th molding cycles (K: natural number, where 1≦K<M). The determination unit 92 uses the degree of dispersion to determine whether the condition of the resin measured during the K-th to M-th molding cycles is good or bad. If the degree of dispersion is less than or equal to the second threshold value TH2, it is determined that the resin measured in all the K-th to M-th molding cycles is in good condition. If the degree of dispersion exceeds the second threshold value TH2, it is determined that the condition of the resin measured in all the K-th to M-th molding cycles is not good.

FIG. 9 is a flowchart illustrating the flow of the determination method according to Modification 7.

The determination device 702 can execute the determination method illustrated in FIG. The determination method includes a load acquisition step S1, a load determination step S2, an operation information acquisition step S3, a calculation feasibility determination step S5, a statistic calculation step S6, a state determination step S8, and a correction command step S9. include.

A description of the load acquisition step S1, the load determination step S2, the operation information acquisition step S3, the calculation possibility determination step S5, and the correction command step S9 will be omitted (see the embodiment).

The statistic calculation step S6 is similar to the embodiment in that the statistic calculation unit 88 calculates the statistic ST. However, in the statistic calculation step S6 in FIG. 9, the degree of dispersion is calculated as the statistic ST.

The condition determination step S8 is similar to the embodiment in that the determination unit 92 determines whether the condition of the resin is good or bad using the statistical amount ST. However, the statistic ST used by the determination unit 92 in the statistic calculation step S6 in FIG. 9 is not a representative value but a degree of dispersion. Further, in the state determination step S8 in FIG. 9, the quality of the resin measured from the start of the determination method until the start of the statistic calculation step S6 is determined.

Note that, after calculating the degree of dispersion once, the statistic calculation unit 88 may recalculate the degree of dispersion each time the molding cycle is repeated.

For example, the statistic calculation unit 88 calculates the degree of dispersion based on the plurality of required times obtained during the K-th to M-th molding cycles. The degree of dispersion is used to determine the quality of the resin weighed in the K-th to M-th molding cycles.

Thereafter, the statistics calculation unit 88 recalculates the degree of dispersion based on the plurality of required times obtained during the (K+1)th to (M+1)th molding cycles. The degree of dispersion can be used to determine the quality of the resin measured in the (K+1)th to (M+1)th molding cycles.

However, the state of the resin measured in the (K+1)th to Mth molding cycles has already been determined once. In this case, the determination based on the recalculated degree of dispersion is performed as a double check for the range of the (K+1)th to Mth molding cycles. Alternatively, the determination result based on the recalculated degree of dispersion may be ignored for the range of the (K+1)th to Mth molding cycles.

In the above example, the degree of dispersion is recalculated every time the M-th molding cycle is repeated. That is, in the above example, the calculation pace of the degree of dispersion is one cycle. However, the calculation pace of the degree of dispersion may be two or more cycles.

(Modification 8)
The statistic calculation unit 88 may calculate both the representative value and the variance value (see Modification 7). The determination unit 92 may determine whether the state of the resin is good or bad based on both the representative value and the variance value.

For example, the statistics calculation unit 88 calculates the deviation (degree of dispersion) of a plurality of required times obtained between the K-th to M-th molding cycles. The determination unit 92 uses the deviation to determine whether the condition of the resin measured during the K-th to M-th molding cycles is good or bad.

Furthermore, the statistics calculation unit 88 further calculates the average value (representative value) of the plurality of required times obtained during the K-th to M-th molding cycles. The range determining unit 90 determines the allowable range AR based on the average value. The determination unit 92 uses the allowable range AR to determine whether the condition of the resin measured in the N-th molding cycle is good or bad.

Note that the determination unit 92 may perform both determination based on the degree of dispersion and determination based on the representative value in order to determine the quality of the resin measured in the same molding cycle.

For example, a deviation and an average value are calculated based on a plurality of required times obtained between the first to Mth molding cycles. Furthermore, the allowable range AR is determined based on the average value. The determination unit 92 determines the state of the resin measured in the first to Mth molding cycles based on the deviation. Further, the determination unit 92 determines the state of the resin measured in the L-th molding cycle based on the allowable range AR (L: natural number, where L≦M). Thereby, the state of the resin in the L-th molding cycle is determined based on both the degree of dispersion and the representative value.

Here, there is a possibility that the determination result based on the degree of dispersion and the determination result based on the representative value are different. In that case, the determination unit 92 determines that the condition of the resin in the L-th molding cycle is good only in the determination based on the degree of dispersion and the determination based on the representative value. If the condition is finally determined to be good, it is favorable. This reduces the risk that resin in poor condition will be overlooked.

(Modification 9)
In order to reduce the pressure of the resin, the control device 18 may control the second motor 52b to perform suckback, which moves the screw 34 backward from the metering position.

(Modification 10)
The threshold value table TB may store a plurality of threshold values according to not only the type of screw 34 and the type of resin but also the type of nozzle 32.

(Modification 11)
The method in which the axis LA of the cylinder 26 and the axis of the screw 34 overlap is also referred to as an in-line (in-line screw) method. The injection molding machine 10 to which the in-line method is applied is also referred to as an in-line injection molding machine. The injection device (14) of the in-line injection molding machine (10) is easier to maintain than injection devices of other types.

However, the determination device 70 may be included in an injection molding machine 10 that is not an in-line type. A method other than the inline method is, for example, a pre-pura method.

(Modification 12)
The determination device 70 may be incorporated into the control device 18. In this case, the control device 18 and the determination device 70 are provided as one integrated electronic device.

(Modification 13)
FIG. 10 is a configuration diagram of an injection molding system SYS1 (SYS) according to modification 13.

The injection molding system SYS1 includes a plurality of injection molding machines 10 and a management device 100. The number of injection molding machines 10 provided in the injection molding system SYS1 is not particularly limited.

The management device 100 is, for example, an electronic device for managing a plurality of injection molding machines 10. The management device 100 is communicably connected to the control device 18 (181, 182, 183, . . . ) of each injection molding machine 10. The management device 100 communicates with a plurality of control devices 18 via a predetermined network. An operator can, for example, issue instructions to a plurality of control devices 18 at once via the management device 100.

The determination device 70 may be incorporated into the management device 100. In this case, the determination device 70 and the management device 100 are provided to the operator as one integrated electronic device.

The determination device 70 acquires a plurality of pieces of operation information INF from each of the plurality of injection molding machines 10. For example, the determination device 70 obtains a plurality of pieces of operation information INF from each of the control device 181, the control device 182, and the control device 183 via a predetermined network.

Furthermore, the determination device 70 determines the quality of the measured resin for each injection molding machine 10. For example, the determination device 70 determines whether the state of the resin measured by the injection molding machine 10 equipped with the control device 181 is good or bad based on a plurality of pieces of operation information INF acquired from the control device 181. Similarly, the determination device 70 determines whether the state of the resin measured by the injection molding machine 10 equipped with the control device 182 (183) is good or not, based on a plurality of pieces of operation information INF acquired from the control device 182 (183). Determine.

According to this modification, the quality of the resin measured in each of the plurality of injection molding machines 10 can be determined using one electronic device (determination device 70).

FIG. 11 is a configuration diagram of another injection molding system SYS2 (SYS) according to Modification 13.

The determination device 70 may be incorporated into one of the plurality of control devices provided in the injection molding system SYS (see also Modification 12).

For example, the injection molding system SYS2 includes at least three control devices 18 (185, 186, 187, . . . ). The determination device 70 is incorporated into the control device 185, for example. The determination device 70 communicates with other control devices 18 (187, 188) via a predetermined network. Thereby, the determination device 70 can be used not only for the injection molding machine 10 equipped with the control device 185 but also for example, for the injection molding machine 10 equipped with the control device 186 and the injection molding machine 10 equipped with the control device 187. It is possible to judge whether the condition of the weighed resin is good or bad in each case.

[Invention obtained from embodiment]
The inventions that can be understood from the above embodiments and modifications are described below.

<First invention>
A first invention provides a state of the resin measured in an injection molding machine (10) that includes a cylinder (26) and a screw (34) that injects the resin measured in the cylinder into the mold (20). A determination device (70) that determines the quality of the screw, wherein the load acquisition device (70) acquires the load (LO) applied to the screw in response to the resin being injected from the cylinder into the mold in a plurality of molding cycles. (82), and in a plurality of molding cycles, the screw is operated from when the screw starts an injection operation for injecting the resin into the mold until the load exceeds the first threshold value (TH1). an operation information acquisition unit (86) that acquires operation information (INF) including at least one of a movement amount, a rotation amount, and a required time; and a plurality of the operation information acquired during the plurality of molding cycles. a statistic calculation unit (88) that calculates at least one statistic (ST) of the movement amount, the rotation amount, and the required time based on the statistic; The determination device includes a determination unit (92) that determines whether the state of the resin is good or bad.

Thereby, it is possible to judge whether the condition of the measured resin is good or bad.

The load acquisition unit acquires as the load at least one of a first torque of a first motor (52a) that rotates the screw and a second torque of a second motor (52b) that advances the screw. It's okay. Thereby, the load on the screw can be detected based on the current torque sensor originally provided in the motor, so an increase in equipment cost for load detection can be suppressed.

The load acquisition unit may acquire the pressure of the resin in the cylinder as the load. Thereby, the load on the screw can be detected based on the pressure sensor originally provided in the injection molding machine, so an increase in equipment cost for load detection can be suppressed.

In the first invention, the first threshold value is determined based on a threshold table (TB) in which a plurality of first threshold values are stored according to at least one of the plurality of types of the screws and the plurality of types of the resin. The apparatus may further include a threshold determination section (84) for determining the motion information, and the motion information acquisition section may acquire the motion information using the first threshold determined by the threshold determination section. Thereby, operation information is acquired based on an appropriate threshold value depending on the screw, resin, etc. used in injection molding.

The first invention may further include an operation section (74) for an operator to specify the first threshold value. This allows the operator to arbitrarily set the first threshold value.

The statistics calculation unit calculates at least one of a plurality of degrees of dispersion of the movement amount, a plurality of degrees of dispersion of the rotation amount, and a plurality of degrees of dispersion of the required time, based on the acquired motion information. and if the calculated degree of dispersion exceeds a second threshold (TH2), the determination unit determines that the resin weighed during the plurality of molding cycles is not in good condition. Good too. Thereby, it is possible to determine whether the condition of the measured resin is good or bad.

The statistic calculation unit calculates at least one of a plurality of representative values of the movement amounts, a plurality of representative values of the rotation amounts, and a plurality of representative values of the required times, and the determination device includes: The determination unit further includes a range determining unit (90) that determines an allowable range (AR) based on the calculated representative value, and in the molding cycle after the allowable range is determined, the determining unit The quality of the state of the resin may be determined based on the operation information and the allowable range. Thereby, it is possible to determine whether the condition of the measured resin is good or bad.

The injection molding machine controls the injection molding machine based on a measurement condition value (CV) including at least one of a target temperature of the cylinder, a target rotational speed of the screw, and a target pressure of the resin. , a control device (18) for measuring the resin, and the determination device further includes a correction command unit (94) that outputs a correction signal for correcting the measurement condition value based on the determination result of the determination unit. The control device corrects the measurement condition value based on the correction signal, and the correction signal adjusts the measurement condition value when the movement amount, the rotation amount, or the required time is larger than the allowable range. This is a signal to correct the value to be smaller than the current weighing condition value, and if the movement amount, the rotation amount, or the required time is smaller than the allowable range, the weighing condition value is corrected to be smaller than the current weighing condition value. It may also be a signal indicating that the value should be larger than the measurement condition value. Thereby, the measurement condition values are automatically corrected so that the quality of the molded product is stabilized.

The first aspect of the invention further includes a control restriction section (98) that outputs a predetermined control signal to a control device of the injection molding machine when the determination section determines that the state of the resin is not good. The control signal may be a signal to limit the operation of the injection molding machine. As a result, the operation of the injection molding machine is automatically restricted when there is a risk that the quality of the molded product may not be stable.

The first invention may further include a display control section (96) that controls the display device (72) and causes the display device to display information indicating the determination result of the determination section. This allows the operator to be informed of the determination result as to whether the condition of the resin is good or bad.

In a first aspect of the present invention, the condition of the measured resin may be determined for each injection molding machine by acquiring the load and the plurality of operation information from each of the plurality of injection molding machines. good. Thereby, the quality of the resin measured in each of the plurality of injection molding machines can be determined by one determination device.

The determination device may be incorporated into a management device (100) that manages a plurality of the injection molding machines. Thereby, the quality of the resin measured in each of the plurality of injection molding machines can be determined by one determination device (management device).

<Second invention>
A second invention provides a state of the resin measured in an injection molding machine (10) that includes a cylinder (26) and a screw (34) that injects the resin measured in the cylinder into the mold (20). The method includes a load acquisition step (S1) of acquiring the load (LO) applied to the screw in response to the injection of the resin from the cylinder into the mold in a plurality of molding cycles. ), the amount of movement and the amount of rotation of the screw from when the screw starts an injection operation for injecting the resin into the mold until the load exceeds a threshold value in a plurality of the molding cycles; a motion information acquisition step (S3) of acquiring motion information (INF) including at least one of the following: the amount of movement based on the plurality of motion information acquired during the plurality of molding cycles; a statistic calculating step (S6) of calculating at least one statistic (ST) of the rotation amount and the required time; and determining whether the condition of the weighed resin is good or bad based on the statistic. This is a determination method including a determination step (S8) for determining.

Thereby, it is possible to judge whether the condition of the measured resin is good or bad.

DESCRIPTION OF SYMBOLS 10... Injection molding machine 18... Control device 20... Mold 26... Cylinder 34... Screw 52a... First motor 52b... Second motor 70... Judgment device 72... Display section (display device) 74... Operation section 82... Load acquisition section 84...Threshold value determination unit 86...Operation information acquisition unit 88...Statistics calculation unit 90...Range determination unit 92...Judgment unit 94...Correction command unit 96...Display control unit 98...Control restriction unit 100...Management device AR...Tolerance range INF ...Operation information LO...Load ST...Statistics TB...Threshold table TH1...First threshold TH2...Second threshold

Claims (13)

Judgment to determine whether the condition of the resin measured by the injection molding machine (10) including a cylinder (26) and a screw (34) for injecting the resin measured in the cylinder into the mold (20) is good or bad. A device (70),
a load acquisition unit (82) that acquires a load (LO) applied to the screw in response to the resin being injected from the cylinder into the mold in a plurality of molding cycles;
In a plurality of molding cycles, the amount of movement and amount of rotation of the screw from when the screw starts an injection operation for injecting the resin into the mold until the load exceeds a first threshold (TH1). and a required time.
Statistics calculation of calculating at least one statistic (ST) of the movement amount, the rotation amount, and the required time based on the plurality of pieces of the operation information acquired in the plurality of molding cycles. Department (88) and
a determination unit (92) that determines the quality of the weighed resin based on the statistics;
A determination device comprising: The determination device according to claim 1,
The load acquisition unit acquires, as the load, at least one of a first torque of a first motor (52a) that rotates the screw and a second torque of a second motor (52b) that advances the screw. , determination device. The determination device according to claim 1,
The load acquisition unit is a determination device that acquires the pressure of the resin in the cylinder as the load. The determination device according to any one of claims 1 to 3,
a threshold determining unit that determines the first threshold based on a threshold table (TB) in which a plurality of first thresholds are stored according to at least one of the plurality of types of the screws and the plurality of types of the resin; 84) further comprising;
The motion information acquisition section is a determination device that acquires the motion information using the first threshold determined by the threshold determination section. The determination device according to any one of claims 1 to 3,
The determination device further includes an operation unit (74) for an operator to specify the first threshold value. The determination device according to any one of claims 1 to 5,
The statistics calculation unit calculates at least one of a plurality of degrees of dispersion of the movement amount, a plurality of degrees of dispersion of the rotation amount, and a plurality of degrees of dispersion of the required time, based on the acquired motion information. Calculate the
A determination device, wherein the determination unit determines that the resin measured during the plurality of molding cycles is not in good condition when the calculated degree of dispersion exceeds a second threshold (TH2). The determination device according to any one of claims 1 to 6,
The statistics calculation unit calculates at least one of a plurality of representative values of the movement amounts, a plurality of representative values of the rotation amounts, and a plurality of representative values of the required times,
The determination device further includes a range determination unit (90) that determines an allowable range (AR) based on the calculated representative value,
In the molding cycle after the tolerance range is determined, the determination unit determines whether the measured resin is in good condition based on the operation information and the tolerance range. The determination device according to claim 7,
The injection molding machine controls the injection molding machine based on a measurement condition value (CV) including at least one of a target temperature of the cylinder, a target rotational speed of the screw, and a target pressure of the resin. , comprising a control device (18) for metering the resin;
The determination device further includes a correction command unit (94) that outputs a correction signal for correcting the measurement condition value based on the determination result of the determination unit,
The control device corrects the measurement condition value based on the correction signal,
The correction signal is
If the movement amount, the rotation amount, or the required time is larger than the allowable range, it is a signal to correct the measurement condition value to be smaller than the current measurement condition value,
The determination device is a signal indicating that the measurement condition value is made larger than the current measurement condition value when the movement amount, the rotation amount, or the required time is smaller than the allowable range. The determination device according to any one of claims 1 to 7,
further comprising a control restriction unit (98) that outputs a predetermined control signal to a control device of the injection molding machine when the determination unit determines that the state of the resin is not good;
The determination device, wherein the predetermined control signal is a signal to limit operation of the injection molding machine. The determination device according to any one of claims 1 to 9,
A determination device further comprising a display control unit (96) that controls a display device (72) to display information indicating a determination result of the determination unit on the display device. The determination device according to any one of claims 1 to 10,
A determination device that determines the quality of the measured resin for each injection molding machine by acquiring the load and the plurality of operation information from each of the plurality of injection molding machines. The determination device according to claim 11,
The determination device is incorporated in a management device (100) that manages a plurality of injection molding machines. Judgment to determine whether the condition of the resin measured by the injection molding machine (10) including a cylinder (26) and a screw (34) for injecting the resin measured in the cylinder into the mold (20) is good or bad. A method,
a load acquisition step (S1) of acquiring a load (LO) applied to the screw in response to the resin being injected from the cylinder to the mold in a plurality of molding cycles;
In a plurality of the molding cycles, the amount of movement of the screw, the amount of rotation, and the required time from when the screw starts an injection operation for injecting the resin into the mold until the load exceeds a threshold value. an operation information acquisition step (S3) of acquiring operation information (INF) including at least one of the following;
Statistics calculation of calculating at least one statistic (ST) of the movement amount, the rotation amount, and the required time based on the plurality of pieces of the operation information acquired in the plurality of molding cycles. Step (S6) and
a determination step (S8) of determining the quality of the weighed resin based on the statistics;
Judgment method, including.

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