JP7128071B2 - Injection molding machine, injection molding system and injection control method - Google Patents

Description

Embodiments according to the present invention relate to an injection molding machine, an injection molding system and an injection control method.

An injection molding machine molds resin by pouring molten resin into a cavity between clamped molds. Depending on the shape of the product, a plurality of positions are provided for the molten resin to pass from the mold to the cavity. By providing a plurality of gates that can be opened and closed at these passing positions and shifting the opening and closing timing for each gate, it is possible to suppress appearance defects (for example, weld lines) and efficiently mold resin according to the product shape. . A valve gate device is generally used for such gate opening/closing control.

However, the filling of the molten resin is usually carried out at a substantially constant injection speed. Therefore, when any gate is newly opened during filling, the flow velocity of the molten resin passing through the newly opened gate increases rapidly. On the other hand, the flow velocity of molten resin passing through the gate, which has already been opened and the opening area of which remains unchanged, decreases sharply. When the flow velocity of the molten resin passing through the gate is rapidly reduced, the front end of the flowing molten resin tends to solidify, causing a problem of appearance defects such as flow marks in the vicinity of the gate. Further, when the flow velocity of the molten resin passing through the gate is rapidly reduced, the flow velocity of the molten resin inside the mold is also rapidly reduced. In this case, the solidified layer formed on the surface of the molten resin as it is cooled by the mold becomes thicker. In thin-walled parts of the product, the pressure in the direction of opening the mold increases as the molten resin flows through the narrow area between the solidified layers. Therefore, there is a problem that the pressure of the molten resin in the mold varies greatly, making it difficult to perform molding with an appropriate mold clamping force.

JP 2006-224499 A

Provided are an injection molding machine, an injection molding system, and an injection control method capable of suppressing appearance defects and molding resin with an appropriate mold clamping force.

The injection molding machine according to this embodiment includes an injection device that injects a molding material into a cavity between a first mold and a second mold by moving a screw within a barrel; A valve driving unit that controls the opening area of a gate that is provided in at least one of the two molds and allows the molding material to pass through the cavity, and the moving speed of the screw or the molding that is injected based on the opening area controlled by the valve driving unit. a control unit that calculates the flow rate of the material and controls the injection device to move the screw at the calculated moving speed or to inject the molding material at the calculated flow rate, wherein the control unit controls the opening area Calculate the transfer speed or flow rate by multiplying the maximum transfer speed or the maximum flow rate that indicates the maximum value of the flow rate by the ratio of the opening area during injection to the maximum opening area that indicates the maximum value of .

1 is a block diagram showing an example of the configuration of an injection molding machine according to a first embodiment; FIG. FIG. 2 is a block diagram showing an example of the configuration of an injection device, a control section, a fixed mold and a movable mold according to the first embodiment; The figure which expanded the gate which communicates with a cavity. FIG. 4 is a cross-sectional view of the gate taken along line AA of FIG. 3; The figure which shows an example of the operation|movement of the injection molding machine by 1st Embodiment. FIG. 4 is a flowchart showing an example of the operation of the injection molding machine according to the first embodiment; FIG. 5 is a block diagram showing an example of the configuration of an injection device, a control section, a fixed mold and a movable mold according to Modification 1;

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. This embodiment does not limit the present invention.

The drawings are schematic or conceptual, and the ratio of each part is not necessarily the same as the actual one. In the specification and drawings, the same reference numerals are given to the same elements as those described above with respect to the previous drawings, and detailed description thereof will be omitted as appropriate.

(First embodiment)
FIG. 1 is a block diagram showing an example of the configuration of an injection molding machine 1 according to the first embodiment. The injection molding machine 1 is a machine capable of repeatedly executing a series of injection molding operations, for example, repeating the operation of molding a molded product once as a cycle operation. The time taken to execute a series of cycle operations is called cycle time.

The injection molding machine 1 includes a frame 2, a stationary platen 3, a moving platen 4, tie bars 5, a mold clamping drive mechanism 6, an injection device 7, a control unit 8, an extrusion mechanism 9, a human machine, It has an interface 60, a storage unit 110, an injection pressure sensor S1, and a screw position sensor S2.

Frame 2 is the base of injection molding machine 1 . A stationary platen 3 is fixed on the frame 2 . A fixed mold 11 as a first mold is attached to the fixed platen 3 . One end of the tie bar 5 is fixed to the stationary platen 3 and the other end is fixed to the support platen 10 . The tie bars 5 extend from the fixed platen 3 through the movable platen 4 to the support platen 10 .

The movable platen 4 is mounted on linear guides, slide plates, rollers, or the like (not shown) provided on the frame 2 . The movable platen 4 is guided by tie bars 5 or linear guides and can move toward or away from the stationary platen 3 . A movable mold 12 as a second mold is attached to the movable platen 4 . The movable mold 12 faces the fixed mold 11 , approaches the fixed mold 11 together with the movable platen 4 , and is combined with the fixed mold 11 . A space corresponding to the shape of the product is formed between the movable mold 12 and the fixed mold 11 by bringing the movable mold 12 and the fixed mold 11 into contact with each other.

The mold clamping drive mechanism 6 includes a toggle mechanism 13 and a toggle mechanism drive section 14 . The toggle mechanism driving section 14 includes a mold clamping servomotor 21 , a ball screw 22 and a transmission mechanism 23 to drive the toggle mechanism 13 . A crosshead 15 is attached to the tip of the ball screw 22 . The rotation of the ball screw 22 moves the crosshead 15 closer to or away from the moving platen 4 . The transmission mechanism 23 transmits the rotation of the mold clamping servomotor 21 to the ball screw 22 to move the crosshead 15 .

When the toggle mechanism driving section 14 moves the crosshead 15, the toggle mechanism 13 operates. For example, when the crosshead 15 moves toward the movable platen 4, the movable platen 4 moves toward the fixed platen 3, and the molds 11 and 12 are clamped. Conversely, when the crosshead 15 moves away from the movable platen 4, the movable platen 4 moves away from the fixed platen 3, and the molds 11 and 12 are opened.

The extrusion mechanism 9 includes an extrusion servomotor 71 , a ball screw 72 , a transmission mechanism 73 and an extrusion pin 74 for removing the molded product from the moving mold 12 . The tip of the ejector pin 74 penetrates the inner surface of the moving mold 12 . As the ball screw 72 rotates, the ejector pin 74 ejects the product attached to the inner surface of the moving mold 12 . The transmission mechanism 73 transmits the rotation of the push-out servomotor 71 to the ball screw 72, and the ball screw 72 rotates to move the push-out pin 74 in the horizontal direction in FIG.

The injection device 7 includes a heating barrel (band heater) 41 , a screw 42 , a metering drive section 43 and an injection drive section 44 . The heating barrel 41 has a nozzle 41a for injecting molten resin into the cavity of the clamped mold. The heating barrel 41 heats and melts the resin from the hopper 45 and stores it, and injects the molten resin from a nozzle. The screw 42 is provided so as to be movable inside the heating barrel 41 while rotating or not rotating. In the metering process, the screw 42 rotates, and the injection amount of the molten resin injected from the barrel 41 is metered and determined by the amount of rotation (movement distance) of the screw 42 . In the injection process, the screw 42 moves without rotating and injects the molten resin from the nozzle.

The weighing drive unit 43 has a weighing servomotor 46 and a transmission mechanism 47 that transmits the rotation of the weighing servomotor 46 to the screw 42 . When the metering servomotor 46 is driven and the screw 42 is rotated within the heating barrel 41 , resin is introduced from the hopper 45 into the heating barrel 41 . The introduced resin is sent to the tip side of the heating barrel 41 while being heated and kneaded. The resin is melted and stored in the tip portion of the heating barrel 41 . The molten resin is injected from the barrel 41 by moving the screw 42 in the direction opposite to that during metering. At this time, the screw 42 moves without rotating and pushes the molten resin out of the nozzle. In this embodiment, the molten resin is used as the molding material, but the molding material is not limited to the molten resin, and may be metal, glass, rubber, carbonized compounds containing carbon fibers, or the like.

The injection drive section 44 has an injection servomotor 51 , a ball screw 52 and a transmission mechanism 53 . Rotation of the ball screw 52 causes the screw 42 to move in the horizontal direction in FIG. 1 within the heating barrel 41 . The transmission mechanism 53 transmits rotation of the injection servomotor 51 to the ball screw 52 . Accordingly, when the injection servomotor 51 rotates, the screw 42 moves. The screw 42 pushes out the molten resin stored at the tip of the heating barrel 41 from the nozzle 41a, thereby injecting the molten resin from the nozzle 41a.

The injection pressure sensor S1 detects the filling pressure when the molten resin is filled from the barrel 41 into the mold and the holding pressure in the holding pressure process. In the injection process, the injection pressure sensor S1 detects the injection pressure of the molten resin material from the barrel 41 to the mold. In the holding pressure process, the injection pressure sensor S1 detects the holding pressure of the molten resin after the holding pressure switching from speed control to pressure control.

A screw position sensor S2 detects the position of the screw 42 . Since the screw 42 moves as the injection servomotor 51 rotates, the screw position sensor S2 may detect the position of the screw 42 from the number of revolutions and angular position of the injection servomotor 51 . By detecting the position of the screw 42 for each predetermined control cycle, the speed and acceleration of the screw 42 can be known. Incidentally, the injection device 7 may be provided with the screw position sensor S2.

A human machine interface (HMI/F) 60 displays various information about the injection molding machine 1 . The HMI/F 60 may include, for example, a display and keyboard, or may be a touch panel display. A user can input settings such as instructions regarding the operation of the injection molding machine 1 through the HMI/F 60 . For example, in injection molding, a product is formed by an injection process of injecting molten resin into a mold and a holding pressure process of controlling the holding pressure of the molten resin in the mold.

The control unit 8 monitors sensor information received from various sensors (not shown) during the injection process, and controls the injection device 7 based on the sensor information. Further, the control section 8 controls the screw 42 according to the set value set through the HMI/F 60 . Furthermore, the control unit 8 causes the display unit 100 to display necessary data.

Storage unit 110 stores a plurality of pieces of operation information of injection molding machine 1 . The operation information is information indicating the operation of the molds 11 and 12, the mold clamping drive mechanism 6, or the injection device 7. FIG.

FIG. 2 is a block diagram showing an example of the configuration of the injection device 7, control unit 8, stationary mold 11 and movable mold 12 according to the first embodiment. Here, the injection molding machine 1 plus the fixed mold 11 and the movable mold 12 is called an injection molding system.

The stationary mold 11 has runners 80 and gates 81 .

The runner 80 allows the molten resin injected from the injection device 7 to pass through to the gate 81 at the boundary between the fixed mold 11 and the cavity C. As shown in FIG.

The gate 81 is provided inside the stationary mold 11 and communicates with the cavity C. As shown in FIG. The gate 81 includes a needle valve 82 , a valve drive section 83 and a gate control section 84 . The gate 81 according to the first embodiment is an electric valve gate. Note that the runner 80 and the gate 81 may be inside the moving mold 12 .

FIG. 3 is an enlarged view of the gate 81 communicating with the cavity C. As shown in FIG. The needle valve 82 moves in the horizontal direction (resin injection direction) in FIG. The area through which the resin passes through the gate 81 changes depending on the position of the needle valve 82 . The passing area is also the opening area of the gate 81 . By changing the opening area, the gate 81 allows the molten resin to pass into the cavity C or blocks the passage of the molten resin.

FIG. 4 is a cross-sectional view of gate 81 taken along line AA of FIG. The cross section of FIG. 4 is a cut surface in a direction substantially perpendicular to the moving direction of the needle valve 82 or the flowing direction of the molten resin. It is a cross section of the part where As shown in FIG. 4, the passing area (opening area) is the area S in the cross section of the gate 81 through which the molten resin can pass. The opening area S is variable depending on the position of the needle valve 82 . By changing the size of the opening area S, the flow rate (injection rate) of the molten resin changes.

A stationary mold 11 according to the first embodiment has a plurality of gates 81 . For example, the fixed mold 11 shown in FIG. 2 has two gates 81 . A plurality of gates 81 can be set to have different opening areas.

The valve drive unit 83 controls the opening area of the gate 81 by moving the position of the needle valve 82 as described above. As described above, since the gate 81 is an electric valve gate, the valve driving section 83 is ball screw driven by a motor (not shown). The opening area of a certain gate 81 varies from the minimum opening area (minimum passing area) indicating the minimum opening area to the maximum opening area (maximum passing area ) can be set or fine-tuned. The minimum opening area is an opening area where passage of the molten resin to the cavity C is blocked. A minimum opening area is, for example, 0 mm ² . The maximum opening area is the opening area when a certain gate 81 is fully open. Each gate 81 may have a different maximum opening area.

Also, the valve drive unit 83 has an opening area sensor (not shown). The opening area sensor detects the position of the motor. The position of this motor can be converted to the actual opening area of gate 81 . The valve drive unit 83 sends the detected motor position to the gate control unit 84 .

The gate control section 84 changes the opening area of the gate 81 by controlling the valve driving section 83 . The gate control unit 84 acquires the position of the motor from the opening area sensor of the valve drive unit 83, and feedback-controls the valve drive unit 83 based on the acquired position of the motor. Thereby, the gate control section 84 can change the opening area of the gate 81 to an arbitrary opening area. The gate control unit 84 also sends the motor position acquired from the valve drive unit 83 to the control unit 8 .

The controller 8 is connected to the injection device 7 and the gate controller 84 shown in FIG. The controller 8 acquires the position of the screw 42 detected by the screw position sensor S2 shown in FIG. 1 during the filling of the molten resin. The control unit 8 sends a command to change the opening area of the gate 81 to the gate control unit 84 . This is for controlling the weld line and efficiently molding the resin according to the shape of the product, as will be described later. The control unit 8 acquires the position of the motor of the valve driving unit 83 from the gate control unit 84 . As described above, since the position of the motor corresponds to the opening area of the gate 81, the control unit 8 controls the flow rate of the molten resin based on the position of the motor (the actual opening area of the gate 81) obtained from the gate control unit 84. , the injection speed of the injection device 7 is calculated. The injection speed is the moving speed (mm/sec) of the screw 42 in the injection process. The calculated injection speed is the injection speed of the screw 42 calculated to inject the molten resin at a flow rate suitable for the opening area of the gate 81 during injection. The control unit 8 sends the injection speed calculated at the change timing of the opening area to the injection device 7, and sets the speed of the screw 42 to the calculated injection speed during filling of the molten resin. Thereby, the injection device 7 can inject the molten resin at a flow rate suitable for the opening area of the gate 81 .

When the fixed mold 11 has a plurality of gates 81 , the sum of the opening areas of the plurality of gates 81 may be the opening area of the gates 81 . Even in this case, the controller 8 calculates the injection speed based on the opening area of the gate 81 during injection. Calculation of the injection speed will be described later with reference to FIGS. 5(A) to 5(D).

Also, the control unit 8 sends a command to the gate control unit 84 to control the timing of opening the gates 81 . A weld line may occur at a position where the molten resin from the plurality of gates 81 joins in the cavity C due to the plurality of gates 81 . A weld line is an appearance defect in which lines appear on the surface of a product, and it also causes a decrease in the strength of the product. The control unit 8 can control the weld line by changing the timing of opening the plurality of gates 81, for example, adjusting the weld line to an inconspicuous position on the product.

Also, the control unit 8 may change the timing of opening the plurality of gates 81 depending on the shape of the product. For example, a thicker portion of the product will take longer to solidify than a thinner portion. Therefore, the control unit 8 first causes the resin to flow through the thick portion, and after a predetermined period of time has passed, also causes the resin to flow through the thin portion. Thereby, the resin can be efficiently molded according to the shape of the product.

Next, calculation of the injection speed by the control unit 8 will be described with reference to FIGS. 5(A) to 5(D). As will be described below, the control unit 8 calculates the injection speed multiple times during filling of the molten resin in one molding cycle.

5A to 5D are diagrams showing an example of the operation of the injection molding machine 1 according to the first embodiment. 5A to 5D, fixed mold 11 has five gates VG1 to VG5. FIG. 5(A) shows the injection speed in one molding cycle. The vertical axis in the graph of FIG. 5(A) indicates the injection speed, and the horizontal axis indicates the position of the screw 42 . FIG. 5B shows the opening ratio of each gate VG1 to VG5, the total opening area during injection of all gates VG1 to VG5, the opening ratio of all gates VG1 to VG5, and the injection speed in each section. Each section is delimited by the position of the screw 42 . The boundary of the section shown in FIG. 5(B) corresponds to the position of the screw 42 shown in FIG. 5(A). The aperture ratio of each gate VG1-VG5 is the ratio of the aperture area of each gate VG1-VG5 to the maximum aperture area of each gate VG1-VG5. The aperture ratio of all gates VG1-VG5 is the ratio of the total open area during injection of all gates VG1-VG5 to the total maximum open area of all gates VG1-VG5. FIG. 5C shows the maximum opening area of each gate VG1-VG5 and the total maximum opening area of all gates VG1-VG5. FIG. 5D shows the injection speed (maximum injection speed) when all gates VG1 to VG5 are fully open (maximum opening area). The maximum injection speed is the maximum injection speed.

The section shown in FIG. 5B is divided into sections Z1 to Z7 from the start of filling to the completion of filling. The boundaries of each section are set as the positions of the screws 42 . A section Z1 is a section from the position of the screw 42 at the start of filling to the boundary position. Sections Z2 to Z6 are sections from one boundary position to the next boundary position. A section Z7 is a section from the boundary position to the completion of filling. Although the lengths of the sections Z1 to Z7 shown in FIGS. 5A and 5B are uniform, the lengths of the sections may differ from one section to another.

5(B), the opening ratio of each gate VG1 to VG5 in each section shown in FIG. 5(B), and the position of each gate VG1 to VG5 shown in FIG. 5(C). The maximum opening area and the maximum injection speed shown in FIG. 5(D) are preset as parameters by the user before the injection process. If the gate control section 84 has information on the maximum opening area of each of the gates VG1 to VG5, the control section 8 may acquire the information on the maximum opening area from the gate control section 84. FIG.

After starting the filling of the molten resin, in the section Z1, for example, the opening ratio of the gate VG1 is set to 50%, and the opening ratio of each of the gates VG2 to VG5 is set to 0%. Also, the injection speed at the start of filling is set to 10 mm/sec.

In section Z2, the aperture ratio of gate VG1, which was open in section Z1, is set to increase to 100%. Also, the gates VG3 and VG4 are newly opened, and the aperture ratio of each gate VG3 and VG4 is set to 50%. The control unit 8 sends a command to the gate control unit 84 so as to achieve the set aperture ratio, and acquires the actual aperture ratio (actual aperture area) of the gate 81 from the gate control unit 84 . In this embodiment, the actual aperture ratio is used for calculating the injection speed. Normally, the actual aperture ratio is the same as the aperture ratio set by feedback control. However, when the gate 81 is clogged with resin, the actual aperture ratio may differ from the set value of the aperture ratio. A case where the set aperture ratio differs from the actual aperture ratio and a case where the set aperture ratio is used to calculate the injection speed will be described later.

The maximum opening area of the gate VG1 shown in FIG. 5(C) is set to 100 mm ² . The control unit 8 calculates the opening area of the gate VG1 as 100 mm ² by multiplying the maximum opening area of the gate VG1 by the opening ratio (100%) (100 mm ² ×1). Similarly, since the maximum opening area of ^each of gates VG3 and VG4 shown in FIG. By multiplying (100 mm ² ×0.5), the opening area of each of the gates VG3 and VG4 is calculated as 50 mm ² . In this case, the opening areas of the gates VG1 to VG5 are 100 mm ² , 0 mm ² , 50 mm ² , 50 mm ² and 0 mm ² respectively. Therefore, the control unit 8 adds the opening areas of all the gates VG1 to VG5 and calculates 200 mm ² as the total opening area during injection.

The total maximum opening area of all gates VG1 to VG5 shown in FIG. 5(C) is set to 500 mm ² . Therefore, the control unit 8 determines the ratio of the total opening area during injection (200 mm ² ) of the gates VG1 to VG5 in section Z2 to the total maximum opening area (500 mm ² ) of all gates VG1 to VG5 (total opening area during injection/ The total maximum opening area) of 40% is calculated as the opening ratio of all gates VG1 to VG5.

When all the gates VG1 to VG5 are fully open as shown in FIG. 5(D), the maximum injection speed is set to 100 mm/sec. Therefore, the control unit 8 multiplies the maximum injection speed (100 mm/sec) by the opening ratio (40%) of all the gates VG1 to VG5 (100 mm/sec×0.4) to set the injection speed to 40 mm/sec. Calculate.

In interval Z3, gate VG2 is newly opened. The aperture ratio of gate VG2 is set to 25%. Also, the aperture ratio of each of the gates VG3 and VG4 is set to be increased to 75%. The aperture ratios of gates VG1 and VG5 remain 100% and 0%, respectively. The total open area during injection is therefore 275 mm ² (100 mm ² +25 mm ² +75 mm ² +75 mm ² ). The aperture ratio of all gates VG1 to VG5 is 55% (275 mm ² /500 mm ² ×100). The injection speed is 55 mm/sec (100 mm/sec×0.55).

In section Z4, the aperture ratio of gate VG2 is increased to 50%, and the aperture ratio of gates VG3 and VG4 is increased to 100%. Also, the gate VG5 is newly opened, and the aperture ratio of the gate VG5 is set to 25%. Also, the aperture ratio of the gate VG1 remains 100%. The total open area during injection is therefore 375 mm ² (100 mm ² +50 mm ² +100 mm ² +100 mm ² +25 mm ² ). The aperture ratio of all gates VG1 to VG5 is 75% (375 mm ² /500 mm ² ×100). The injection speed is 75 mm/sec (100 mm/sec×0.75).

In the section Z5, the aperture ratio of the gate VG2 is increased to 100% and the aperture ratio of the gate VG5 is increased to 50%. Also, the aperture ratio of the gates VG1, VG3, VG4 remains 100%. The total open area during injection is therefore 450 mm ² (100 mm ² +100 mm ² +100 mm ² +100 mm ² +50 mm ² ). The aperture ratio of all gates VG1 to VG5 is 90% (450 mm ² /500 mm ² ×100). The injection speed is 90 mm/sec (100 mm/sec×0.9).

In section Z6, the aperture ratio of gate VG5 is set to rise to 100%. Therefore, the control unit 8 calculates the total opening area as 500 mm ² , the opening ratio of all gates VG1 to VG5 as 100%, and the injection speed as 100 mm/sec.

In section Z7, the aperture ratio of each gate VG1, VG3 is set to decrease to 0%. Also, the aperture ratios of the gates VG2, VG4, and VG5 remain 100%. Therefore, the total opening area during injection is 300 mm ² , the opening ratio of all gates VG1 to VG5 is 60%, and the injection speed is 60 mm/sec. Also, at the end of zone Z7, injection device 7 completes filling. For example, when the filling completion time is reached after the start of filling, the injection device 7 completes filling and the opening ratio of each gate VG1 to VG5 becomes 0%.

Thus, the injection device 7 can automatically change the injection speed according to the change in the opening area of the gate 81 . For example, when the opening area or opening ratio of the gate 81 is increased, the injection speed of the screw 42 is increased accordingly. When the opening area or opening ratio of the gate 81 is reduced, the injection speed of the screw 42 is reduced accordingly. As a result, even if the opening area of the gate 81 changes during filling of the molten resin, the change in the flow velocity of the molten resin passing through the gate 81 can be suppressed. Therefore, it is possible to prevent the flow velocity of the molten resin passing through the gate 81 from decreasing and the leading end of the molten resin from easily solidifying. As a result, appearance defects such as flow marks near the gate 81 can be suppressed.

In addition, by suppressing the change in the flow velocity of the molten resin passing through the gate 81, the change in the flow velocity of the molten resin inside the mold is also suppressed. Therefore, the flow velocity of the molten resin in the mold is reduced, and it is possible to suppress the thickening of the solidified layer on the surface of the molten resin that is cooled by the molds 11 and 12 . For example, if a solidified layer is formed in a thin portion of the product, the molten resin may flow in a narrow area between the solidified layers, increasing the pressure of the molten resin. In contrast, according to the present embodiment, it is possible to suppress the local formation of a solidified layer of resin. Therefore, it is possible to suppress an increase in variations in the pressure of the molten resin in the mold, and perform molding with an appropriate mold clamping force.

Further, the control unit 8 according to the first embodiment obtains the actual opening area of the gate 81 from the gate control unit 84 that feedback-controls the position (opening area) of the motor using an opening area sensor, and calculates the injection speed. . If the gate 81 is clogged with resin, the movement of the needle valve 82 may be restricted. Even in such a case, in the present embodiment, the controller 8 calculates the injection speed using the actual opening area. can be calculated. For example, in the section Z2 shown in FIG. 5(B), even if the actual aperture ratio of the gate VG1 is only opened to 80% in response to the command for the aperture ratio of 100%, the control unit 8 will An injection speed (36 mm/sec) lower than the injection speed (40 mm/sec) without it can be calculated. Thereby, the molten resin can be filled at an injection speed suitable for the actual opening area of the gate 81 . Furthermore, even if the gate 81 is clogged, the flow rate of the molten resin passing through the gate 81 can be stably injected.

On the other hand, the controller 8 may calculate the injection speed based on the aperture ratio preset by the user without acquiring the actual aperture area from the gate controller 84 . In this case, it is not possible to calculate the injection speed in consideration of the clogging of the resin, but it is possible to calculate the injection speed more easily without obtaining the actual opening area by feedback control.

Next, operation of the injection molding machine 1 according to the first embodiment will be described with reference to FIG.

FIG. 6 is a flowchart showing an example of the operation of the injection molding machine 1 according to the first embodiment.

First, the user sets parameters for controlling the injection device 7 (S10). The parameters include, for example, the boundary position of each section, the filling completion time, the opening ratio of each gate 81, the maximum opening area of each gate 81, and the injection speed when all gates 81 are fully open. The parameters may include, as initial values, the filling start position of the screw 42 and the injection speed in the section Z1 shown in FIG. 5(B). The parameters may also include the filling completion position of the screw 42 .

Next, the injection device 7 starts filling (S20) and the screw 42 starts moving. The screw position sensor S2 sends the detected position of the screw 42 to the controller 8 . The control unit 8 compares the position of the screw 42 obtained from the screw position sensor S2 with the boundary positions of the sections Z1 to Z7 to determine whether the position of the screw 42 has reached the boundary position (S30). . If the position of the screw 42 has not yet reached the boundary position (NO in S30), the controller 8 continues the determination in step S30. When the position of the screw 42 reaches the boundary position (YES in S30), the controller 8 sends a command to change the opening area of the gate 81 to the gate controller 84 (S40). The gate control section 84 controls the valve driving section 83 to change the opening area. After changing the opening area, the valve drive unit 83 sends the position of the motor to the gate control unit 84 . The gate control unit 84 sends the motor position acquired from the valve drive unit 83 to the control unit 8 . The control unit 8 acquires the position of the motor from the gate control unit 84 and converts the position of the motor into the actual opening area of the gate 81 (S50). As described with reference to FIG. 5B, the controller 8 calculates the injection speed of the screw 42 based on the actual opening area of the gate 81 obtained from the gate controller 84 (S60). The controller 8 sets the calculated injection speed to the injection device 7 (S70).

Next, the control unit 8 compares the filling time and the filling completion time obtained from a timer (not shown) or the position of the screw 42 and the filling completion position to determine whether the filling completion time or the filling completion position has been reached. It is determined whether or not (S80). If the filling completion time or filling completion position has not yet been reached (NO in step S80), the injection device 7 continues filling. The controller 8 determines whether or not the position of the screw 42 has reached the next boundary position (S90). If the position of the screw 42 has not yet reached the boundary position (NO in S90), the controller 8 continues the determinations in steps S80 and S90. When the position of the screw 42 reaches the boundary position (YES in S90), the control section 8 executes steps S40 to S80. When the controller 8 determines that the filling completion time or the filling completion position has been reached (YES in step S80), the injection device 7 completes the filling (S100). Note that the control unit 8 can perform steps S30 to S90 while the screw 42 is moving.

As described above, in the injection molding machine 1 according to the first embodiment, based on the opening area of the gate 81 provided in at least one of the fixed mold 11 and the movable mold 12 and allowing the molten resin to pass through the cavity C, the injection device 7 injection speed (moving speed of the screw 42) is calculated. Also, the injection device 7 injects the molten resin at the calculated injection speed.

As a result, the injection device 7 automatically changes the injection speed according to the change in the opening area of the gate 81 during filling of the molten resin, thereby suppressing the change in the flow speed of the molten resin passing through the gate 81. be able to. As a result, as described above, appearance defects such as flow marks can be suppressed, and molding can be performed with an appropriate mold clamping force. Furthermore, by controlling the plurality of gates 81, appearance defects such as weld lines can be suppressed by controlling the weld lines, and the resin can be efficiently molded according to the shape of the product.

If the flow velocity of the molten resin in the cavity C decreases due to the change in the opening area of the gate 81, a solidified layer is likely to be formed on the surface of the molten resin flowing in the cavity C near the tip. In this case, even if the tips of the molten resin merge, the solidified layers are not completely joined together, so weld lines are likely to occur on the surface of the product.

However, since the injection molding machine 1 according to the first embodiment controls the injection speed of the screw 42 based on the opening area of the gate 81, the decrease in the flow speed of the molten resin inside the cavity C can be suppressed. Therefore, the tip portions of the molten resin can be merged before a solidified layer is formed on the surface of the molten resin near the tip portion. By forming the solidified layer after the ends of the molten resin are joined together, it is possible to facilitate weld lineless molding that suppresses the occurrence of weld lines.

The user may set the opening area of each gate 81 instead of the opening ratio of each gate 81 as a parameter.

Further, in the first embodiment, parameters such as the boundary position and the aperture ratio of each gate 81 are set in advance by the user. However, for example, flow analysis or the like may be used to automate the setting of parameters such as the boundary position and the opening ratio of each gate 81 so that the flow velocity of the molten resin in the cavity C is substantially constant.

Further, instead of the above injection speed and maximum injection speed, the resin flow rate (injection rate) and the resin maximum flow rate (maximum injection rate) may be used. This is because when the diameter of the screw 42 changes, the volume (flow rate) of the injected molten resin changes, so there are cases where the flow rate is controlled instead of the injection speed. The flow rate of resin is the volume of molten resin injected per unit time (cm ³ /sec).

(Modification 1)
Modification 1 of the first embodiment differs from the first embodiment in that the fixed mold 11 has one gate 81 .

Other configurations of the injection molding machine 1 according to Modification 1 are the same as the corresponding configurations of the injection molding machine 1 according to the first embodiment, so detailed description thereof will be omitted.

FIG. 7 is a block diagram showing an example of the configuration of the injection device 7, the control section 8, the fixed mold 11 and the movable mold 12 according to Modification 1. As shown in FIG.

If the fixed mold 11 does not have the gate 81, if the injection speed is changed abruptly in order to change the supply amount of the molten resin according to the position of the screw 42, the flow velocity of the molten resin flowing into the cavity C will be abruptly increased. change.

However, the gate 81 according to Modification 1 can change the opening area according to the change in the injection speed. Thereby, the change in the flow velocity of the molten resin passing through the gate 81 and the molten resin in the cavity C can be suppressed.

The injection molding machine 1 according to Modification 1 operates in the same manner as the injection molding machine 1 according to the first embodiment. Therefore, as in the first embodiment, the injection molding machine 1 according to Modification 1 can perform molding with an appropriate mold clamping force, and can suppress appearance defects such as flow marks. In addition, weld lineless molding can be facilitated.

(Modification 2)
In the first embodiment, the valve drive section 83 is driven by a motor. In contrast, in Modification 2, the valve drive unit 83 is pneumatically driven or hydraulically driven. In the case of pneumatic drive or hydraulic drive, the valve drive section 83 can only set the opening area of the gate 81 to either the minimum opening area or the maximum opening area. That is, the valve drive unit 83 cannot finely adjust the opening area of the gate 81, and can only set it to either the closed state or the open state. In this case, a plurality of gates 81 having the same cross-sectional area may be provided, and the ratio of the number of gates 81 in the open state to the number of all gates 81 may be used as the aperture ratio. Alternatively, a plurality of gates 81 may be provided, and the ratio of the sum of the cross-sectional areas (open areas) of the gates 81 in the open state to the sum of the cross-sectional areas of all the gates 81 may be used as the aperture ratio. Even in this case, the effect of this embodiment is not lost.

At least part of the injection control method according to this embodiment may be configured by hardware or may be configured by software. When configured by software, a program that implements at least part of the functions of the injection control method may be stored in a recording medium such as a flexible disk or CD-ROM, and read and executed by a computer. The recording medium is not limited to a detachable one such as a magnetic disk or an optical disk, and may be a fixed recording medium such as a hard disk device or memory. Also, a program that implements at least part of the functions of the injection control method may be distributed via a communication line (including wireless communication) such as the Internet. Furthermore, the program may be encrypted, modulated, or compressed and distributed via a wired line or wireless line such as the Internet, or stored in a recording medium and distributed.

While several embodiments of the invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

1 injection molding machine, 7 injection device, 8 control section, 11 fixed mold, 12 movable mold, 42 screw, 81 gate, 84 gate control section

Claims (6)

an injection device that injects the molding material into the cavity between the first mold and the second mold by moving the screw within the barrel;
a valve drive unit that controls an opening area of a gate that is provided in at least one of the first mold and the second mold and allows the molding material to pass through the cavity;
The moving speed of the screw or the flow rate of the molding material to be injected is calculated based on the opening area controlled by the valve drive unit, and the screw is moved at the calculated moving speed, or a control unit that controls the injection device so as to inject the molding material at the flow rate set,
The control unit multiplies the maximum moving speed indicating the maximum value of the moving speed or the maximum flow rate indicating the maximum value of the flow rate by the ratio of the opening area during injection to the maximum opening area indicating the maximum value of the opening area. an injection molding machine that calculates the moving speed or the flow rate by 2. The injection molding machine according to claim 1, wherein said control unit calculates said moving speed or said flow rate at the timing of changing said opening area. 3. The injection molding machine according to claim 1, wherein the controller calculates the moving speed or the flow rate based on the opening area detected by an opening area sensor that detects the actual opening area. At least one of the first mold and the second mold has a plurality of gates that can be set to different opening areas,
The injection molding machine according to any one of claims 1 to 3, wherein the opening area is the sum of the opening areas of a plurality of gates. an injection device that injects the molding material into the cavity between the first mold and the second mold by moving the screw within the barrel;
a valve drive unit that controls an opening area of a gate that is provided in at least one of the first mold and the second mold and allows the molding material to pass through the cavity;
The moving speed of the screw or the flow rate of the molding material to be injected is calculated based on the opening area controlled by the valve drive unit, and the screw is moved at the calculated moving speed, or a control unit that controls the injection device so as to inject the molding material at the flow rate set,
The control unit multiplies the maximum moving speed indicating the maximum value of the moving speed or the maximum flow rate indicating the maximum value of the flow rate by the ratio of the opening area during injection to the maximum opening area indicating the maximum value of the opening area. an injection molding machine that calculates the moving speed or the flow rate by
the first mold;
and the second mold. an injection device for injecting molding material into a cavity between a first mold and a second mold by moving a screw within a barrel; and at least one of the first mold and the second mold. An injection control method for an injection molding machine, comprising: a valve driving section that controls an opening area of a gate that is provided to allow the molding material to pass through the cavity; and a control section that controls the injection device,
The valve drive unit controls the opening area;
The control unit calculates the moving speed of the screw or the flow rate of the molding material to be injected based on the opening area controlled by the valve driving unit, and moves the screw at the calculated moving speed. or controlling the injection device to inject the molding material at the calculated flow rate,
The control unit multiplies the maximum moving speed indicating the maximum value of the moving speed or the maximum flow rate indicating the maximum value of the flow rate by the ratio of the opening area during injection to the maximum opening area indicating the maximum value of the opening area. an injection control method, wherein the moving speed or the flow rate is calculated by

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