JP5226191B2 - Molding machine and control method thereof - Google Patents

Description

  The present invention relates to a molding machine and a control method thereof.

  Conventionally, in a molding machine, for example, an injection molding machine, a resin melted in a heating cylinder is filled into a cavity space in a mold apparatus, cooled in the cavity space, and solidified to obtain a molded product. It is designed to be molded.

  The injection molding machine includes a mold device, a mold clamping device, and an injection device, and the injection device includes a heating cylinder that heats and melts a resin, and an injection nozzle that injects the molten resin, and the heating device A screw is disposed in the cylinder so as to be rotatable and movable back and forth. Further, by moving the movable mold forward and backward by the mold clamping device, the mold device is closed, clamped and opened, and a cavity is formed between the fixed mold and the movable mold as the mold is clamped. A space is formed.

When the metering motor is driven to rotate the screw, the resin is weighed and the melted resin is stored in front of the screw head. Along with this, the screw is retracted. Next, when the injection motor is driven to advance the screw, the resin is injected from the injection nozzle and filled into the cavity space (see, for example, Patent Document 1).
JP-A-11-227016

  However, in the conventional injection molding machine, after starting up, the heater may be temporarily stopped, for example, when the take-out machine malfunctions. As a result, the resin continues to be heated, and the viscosity of the resin decreases. As a result, when the operation of the injection molding machine is resumed, the cavity space is excessively filled with resin, resulting in overpacking.

  In this case, an operator who is familiar with the molded product can prevent the overpack from occurring by adjusting the VP switching position, but the work for that is troublesome.

  An object of the present invention is to solve the problems of the conventional injection molding machine and to provide a molding machine that can easily prevent the occurrence of overpacking at the time of start-up and a control method therefor.

  Therefore, in the molding machine of the present invention, a cylinder member, an injection member disposed in the cylinder member so as to be rotatable and movable back and forth, and in the first measurement, the injection member is placed at a measurement start position. From the injection member to the predetermined position, and the first retreat processing means for forming the initial measurement space in front of the injection member, and the injection member at the predetermined position is held in the axial direction without moving in the axial direction. And an initial rotation processing means for rotating in such a state.

  According to the present invention, in the molding machine, the cylinder member, the injection member disposed in the cylinder member so as to be rotatable and movable back and forth, and the measurement start position of the injection member in the first measurement. From the injection member to the predetermined position, and the first retreat processing means for forming the initial measurement space in front of the injection member, and the injection member at the predetermined position is held in the axial direction without moving in the axial direction. And an initial rotation processing means for rotating in such a state.

  In this case, in the first measurement, the injection member is retracted from the measurement start position to a predetermined position without being rotated, and held in the axial direction without being moved in the axial direction at the predetermined position. Since it is rotated in the state, the density of the molding material stored ahead of the injection member can be reduced.

  Therefore, it is possible to prevent overpacking after the molding machine is started up. As a result, it is possible to prevent the mold apparatus from being damaged.

  Further, since it is not necessary for an operator who is familiar with the molded product to adjust the VP switching position to prevent overpacking, the operation can be simplified.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this case, an injection molding machine as a molding machine will be described.

  FIG. 1 is a view showing an injection molding machine according to an embodiment of the present invention, FIG. 2 is a time chart showing the operation of a weighing processing means in the embodiment of the present invention, and FIG. It is a figure which shows the example of a screen.

  In the figure, reference numeral 11 denotes a heating cylinder as a cylinder member, 12 denotes a screw as a measuring member which is rotatably and reciprocally arranged in the heating cylinder 11, and 13 is an injection member. An injection nozzle attached to the front end of the cylinder 11 (in FIG. 1, for convenience, the heating cylinder 11 and the injection nozzle 13 are integrally formed), 14 is a nozzle port formed in the injection nozzle 13, 16 Is a hopper that is attached to a resin supply port formed at a predetermined position near the rear end of the heating cylinder 11, accommodates resin as a molding material, and supplies the resin into the heating cylinder 11.

  A heater (not shown) for heating the resin through the heating cylinder 11 is disposed at a predetermined location on the outer periphery of the heating cylinder 11 to heat the resin in the heating cylinder 11. .

  The screw 12 includes a screw head 27 at the front end, and includes a spiral flight 23 formed on the outer surface of the screw 12 main body, that is, on the outer peripheral surface of the screw 12, along the flight 23. Thus, a spiral groove 24 is formed.

  By the way, the rear end of the heating cylinder 11 is attached to the front injection support 31, and a rear injection support 32 is disposed at a predetermined distance from the front injection support 31. A guide bar 33 is installed between the front injection support 31 and the rear injection support 32, and a pressure plate 34 is disposed along the guide bar 33 so as to freely advance and retract. The front injection support 31 and the rear injection support 32 are fixed to a slide base (not shown) with bolts (not shown).

  Further, a drive shaft 35 is connected to the rear end of the screw 12, and the drive shaft 35 is rotatably supported by the pressure plate 34 by bearings 36 and 37. An electric metering motor 41 as a metering drive unit is attached to the pressure plate 34, and includes a first pulley 42, 43 and a timing belt 44 between the metering motor 41 and the drive shaft 35. The rotational transmission part is arranged. By driving the metering motor 41, the screw 12 can be rotated in the forward direction or the reverse direction.

  The measuring motor 41 is provided with a rotational speed sensor 49 as a rotational speed detection unit. The rotational speed sensor 49 detects the rotational speed of the measuring motor 41 and sends a detection signal to the control unit 71. A rotation speed calculation processing means (rotation speed calculation processing section) (not shown) of the control unit 71 performs a rotation speed calculation process, reads a detection signal, and calculates the rotation speed of the screw 12 based on the rotation speed of the metering motor 41. To do.

  In this embodiment, a metering motor 41 composed of an electric servo motor is used as a metering drive unit. However, a hydraulic motor is used instead of the metering motor 41. be able to. In the present embodiment, an encoder is used as the rotation speed sensor 49, but a resolver can also be used.

  A ball screw 47 including a ball screw shaft 45 and a ball nut 46 screwed to each other is disposed behind the pressure plate 34, and the ball screw 47 causes the ball screw shaft 45 to rotate and move the ball nut 46. A motion direction conversion unit that converts to linear motion is configured, and the ball screw shaft 45 forms a first conversion element, and the ball nut 46 forms a second conversion element. The ball screw shaft 45 is rotatably supported by a bearing 48 with respect to the rear injection support 32, and the ball nut 46 is fixed to the pressure plate 34 via a plate 51 and a load cell 52. Further, an injection motor 53 as an injection drive unit is disposed, and a second rotation transmission unit including pulleys 54 and 55 and a timing belt 56 is provided between the injection motor 53 and the ball screw shaft 45. Arranged. Therefore, by driving the injection motor 53 and rotating the ball screw shaft 45, the ball nut 46 and the pressure plate 34 can be advanced and retracted, and the screw 12 can be advanced and retracted.

  The injection motor 53 is provided with a rotation speed sensor 66 as a rotation speed detection unit. The rotation speed sensor 66 detects the rotation speed of the injection motor 53 and sends a detection signal to the control unit 71. A position calculation processing unit (position calculation processing unit) (not shown) of the control unit 71 reads the detection signal and calculates the position of the screw 12, that is, the screw position based on the rotation speed of the injection motor 53.

  In the present embodiment, an injection motor 53 including an electric servo motor is used as an injection drive unit, but an injection cylinder is used instead of the injection motor 53. can do. In the present embodiment, an encoder is used as the rotation speed sensor 66, but a resolver can also be used.

  In the injection molding machine configured as described above, during the weighing process, a weighing processing unit (weighing processing unit) (not shown) of the control unit 71 performs the weighing process, drives the weighing motor 41, and rotates the screw 12 in advance. When rotating in the forward direction at Nk, the pellet-shaped resin in the hopper 16 enters the heating cylinder 11, advances in the groove 24, is melted by the heater, and is stored in front of the screw head 27. Accordingly, the screw 12 is retracted at the retracting speed Vk.

  In the measurement process, the screw 12 is accelerated from the measurement start position Sa to the acceleration end position to increase the reverse speed Vk, and from the acceleration end position to the deceleration start position (2 to 3 mm from the measurement completion position Sb). The rearward speed Vk is kept constant until the front position), and is decelerated from the deceleration start position to the measurement completion position Sb, and the rearward speed Vk is lowered. In this case, the reverse speed Vk is proportional to the rotational speed Nk of the metering motor 41 and further proportional to the rotational speed Ns of the screw 12. Therefore, in the processing in the control unit 71, the rotational speed is replaced with the reverse speed Vk. Ns is used. The rotational speed Nk is expressed as a function of the position of the screw 12. The rotational speed Nk can be expressed as a function of time.

  Subsequently, during the injection process, an injection processing means (injection processing unit) (not shown) of the control unit 71 performs the injection processing, drives the injection motor 53, and rotates the ball screw shaft 45, whereby the pressure plate 34 is moved. The screw 12 is advanced and the screw 12 is advanced. Accordingly, the resin stored in front of the screw head 27 is injected from the injection nozzle 13 and filled in a cavity space of a mold apparatus (not shown). At this time, the injection processing means reads the detection signal, calculates the screw position, refers to a storage device (not shown) of the control unit 71, reads the screw speed corresponding to the screw position, and uses the screw speed as a command value. The injection motor 53 is driven to advance the screw 12. In this way, the resin is injected from the injection nozzle 13. In the storage device, screw positions and screw speeds are recorded in correspondence. Note that the relationship between the screw position and the screw speed is set by operating the setting device 72.

  In the mold apparatus, when the resin in the cavity space is cooled and solidified, a molded product is formed. Subsequently, the mold apparatus is opened and the molded product can be taken out by a take-out machine (not shown).

  By the way, after starting up the injection molding machine, the injection molding machine may be temporarily stopped when, for example, the take-out machine malfunctions. The resin continues to be heated and the viscosity of the resin decreases. As a result, when the operation of the injection molding machine is resumed, the mold apparatus may be damaged if the cavity space is excessively filled with resin and overpacking occurs.

  Therefore, when the injection molding machine is started up, the density of the resin stored in front of the screw head 27 is lowered at the first measurement, that is, at the first measurement, so that overpacking is prevented. Yes.

  For this purpose, in the fully automatic / semi-automatic mode, the initial weighing processing means (initial weighing processing section) of the weighing processing means performs the initial weighing processing and sets the number of times set in advance when the injection molding machine is started up. In the embodiment, one initial weighing is performed. The mass production measurement processing means (mass production measurement processing unit) of the measurement processing means performs mass production measurement processing, and performs mass production measurement, that is, mass production measurement, following the initial measurement.

  Then, the initial reverse processing means (initial reverse processing section) of the initial measurement processing means performs the initial reverse processing, drives the injection motor 53, and, as shown in FIG. 2, a predetermined position from the measurement start position Sa. In this embodiment, the section Z1 up to the measurement completion position Sb is moved backward at a preset reverse speed Vk without rotating the screw 12 (while maintaining the position in the rotation direction), and the initial reverse movement is performed. I do. At this time, the first retreat processing means simultaneously drives the metering motor 41 and holds a rotor (not shown) of the metering motor 41 so that the screw 12 is not rotated as the screw 12 is retracted. Accordingly, a space for initial measurement is formed in front of the screw 12 (in front of the screw head 27). However, since the screw 12 cannot be rotated, in principle, the resin in the hopper 16 is transferred into the heating cylinder 11. The initial weighing space is emptied.

  Subsequently, when it is confirmed that the temperature of the heating cylinder 11 is a moldable temperature, an initial rotation processing unit (initial rotation processing unit) of the initial weighing processing unit performs an initial rotation process, and the measurement completion position At Sb, the rotational speed at which the screw 12 is set for the preset measuring time τ1 without driving the measuring motor 41 and moving the screw 12 in the axial direction (while maintaining the position in the axial direction). Rotate with Nk. At this time, the first rotation processing means drives the injection motor 53 simultaneously with the metering motor 41 so that the injection motor 53 does not move in the axial direction as the screw 12 is rotated. A rotor (not shown) is held.

  Along with this, the resin in the hopper 16 enters the heating cylinder 11, is advanced in the groove 24, is melted by the heater, and is stored in the initial measurement space. During this time, since the resin is not filled in front of the screw head 27, it is not necessary to apply a back pressure to the screw 12.

  The metering time τ1 is set to a time sufficient for at least the first metering space to be filled with the resin with a predetermined pressure. Further, the rotational speed Nk is set to be equal to the rotational speed Ns of the screw 12 at the deceleration start position (the rotational speed Nk until immediately before the deceleration is started) in the subsequent mass production weighing process.

  Subsequently, an initial suck back processing means (initial suck back processing section) of the initial weighing processing means performs an initial suck back process, drives the injection motor 53, and moves from the weighing completion position Sb to the pre-filling position Sc. The section Z2 is moved backward without rotating the screw 12 (while maintaining the position in the rotational direction) at a preset backward speed Vs with a suckback amount L1 representing the preset backward distance. Perform a suckback. At this time, the initial suck back processing means simultaneously drives the metering motor 41 and holds the rotor of the metering motor 41 so that the screw 12 is not rotated as the screw 12 is retracted. Accordingly, the resin stored in front of the screw 12 is prevented from leaking from the injection nozzle 13.

  The initial suck back from the measurement completion position Sb to the pre-fill position Sc after the initial measurement is performed is not necessarily performed, and can be appropriately performed while observing the state of the molten resin.

  When the first metering is performed in this way, the injection processing means drives the injection motor 53 to advance the screw 12, and fills the cavity space of the mold apparatus with the resin stored in the first metering space. .

  Molded products molded in this way are not molded based on appropriate metering set values, and the metering time is shorter than usual, so overpacking can occur even when the resin viscosity is low. Can be prevented. As a result, it is possible to prevent the mold apparatus from being damaged. In addition, the molded product shape | molded with the initial measurement is handled as inferior goods.

  When the molded product formed by the initial measurement is taken out, the mass production rotation processing means (mass production rotation processing unit) of the mass production measurement processing means performs mass production rotation processing, drives the measurement motor 41, and starts the measurement start position. In the section Z1 from Sa to the measurement completion position Sb, the screw 12 is rotated at the rotational speed Nk. Accordingly, the resin in the hopper 16 enters the heating cylinder 11, advances in the groove 24, is melted by the heater, and is stored in front of the screw 12. Accordingly, the screw 12 is retracted.

  Subsequently, the mass production suck back processing means (mass production suck back processing unit) of the mass production weighing processing means performs mass production suck back processing, drives the injection motor 53, and moves from the measurement completion position Sb to the pre-fill position Sc. The section Z2 is retreated without sucking the screw 12 (while maintaining the position in the rotation direction) at a retreat speed Vs set in advance and a suck back amount L2 representing a retreat distance set in advance. I do. At this time, the mass production suck-back processing means simultaneously drives the weighing motor 41 and holds the rotor of the weighing motor 41 so that the screw is not rotated as the screw 12 is retracted. Accordingly, the resin stored in front of the screw 12 is prevented from leaking from the injection nozzle 13.

  In the mass production rotation process, if the time for the screw 12 to move from the measurement start position Sa to the measurement completion position Sb, that is, the measurement time is τ2, the measurement time τ1 is set to be shorter than the measurement time τ2.

  By the way, the operator can set various molding conditions of the injection molding machine. For this purpose, the setting device 72 is provided with a display unit and an operation unit. When an operator operates the operation unit, a display processing unit (display processing unit) (not shown) of the control unit 71 performs display processing. 3, a molding condition input screen as shown in FIG. 3 is formed on the display unit. When the operator operates the operation unit and inputs a predetermined molding condition on the molding condition input screen, the molding condition (not shown) of the control unit 71 is displayed. The setting processing means (molding condition setting processing unit) performs molding condition setting processing, sets the molding conditions of the metering process as the metering conditions, and sets the molding conditions of the injection process as the injection conditions for the injection device. Mold closing, mold clamping and mold opening molding conditions are set as mold opening / closing conditions.

  The display processing means displays the set molding conditions on the molding condition display screen.

  In FIG. 3, an area AR1 as the actual value display area includes a pre-filling position indicating the position of the screw 12 when starting the injection process, and a VP for switching between speed control and pressure control when the screw 12 is advanced. The switching position, the cushion position representing the forward limit position of the screw 12, the peak pressure representing the maximum value of the resin pressure when filling the resin, the pressure retaining complete position representing the position of the screw 12 that completes the pressure retaining, Screw position representing position, cycle time representing molding cycle time, filling time representing filling time, metering time representing time for metering, screw 12 rotational speed (screw rotational speed), screw 12 torque The displayed rotational torque and the like are displayed.

  The area AR2 as the set value display area displays the speed of the screw 12 (screw speed), the pressure holding time, and the pressure holding pressure for holding pressure, and the area AR3 displays the filling time for filling. The filling pressure, the position of the screw 12 (screw position), the speed of the screw 12 and the like are displayed.

  In the area AR4, the cooling time, the rest time, the VP switching method, and the like are displayed. In the area AR5, the sucking back amount L2 from the measuring completion position Sb and the screw 12 at the time of sucking back are measured. The reverse speed Vs and the like are displayed.

  In the area AR6, ON / OFF indicating whether or not the first measurement is performed, a measurement time τ1, and the like can be set.

  As described above, in the present embodiment, at the time of the first measurement, the screw 12 is retracted without being rotated, and after the initial suckback, the screw 12 is rotated to move the resin forward of the screw head 27. Since it stores, the density of the resin stored ahead of the screw head 27 can be lowered.

  Therefore, after starting up the injection molding machine, for example, when the take-out machine malfunctions, it may be temporarily stopped, and at that time, the control of the heater is continued. Even if the resin continues to be heated and the viscosity of the resin decreases, the resin density is low, so when the operation of the injection molding machine is restarted, the cavity space is not excessively filled with resin, and overpacking occurs. Can be prevented. As a result, by temporarily stopping the injection molding machine, it is possible to prevent the mold apparatus from being damaged even if the state of the resin in the heating cylinder 11 changes.

  In addition, when the molding is started after the purge operation is performed in order to change the resin or the like, the initial measurement as described above can be performed. In this case, even if the resin is changed and the state of the resin melted in the heating cylinder 11 is changed, it is possible to prevent the mold apparatus from being damaged.

  Further, since it is not necessary for an operator who is familiar with the molded product to adjust the VP switching position to prevent overpacking, the operation can be simplified.

  In the present embodiment, in the initial retraction process, the screw 12 is retreated without rotating, but the screw 12 can be retreated while being rotated at a rotation speed lower than the rotation speed Ns in the mass production rotation process. it can.

  In addition, this invention is not limited to the said embodiment, It can change variously based on the meaning of this invention, and does not exclude them from the scope of the present invention.

It is a figure which shows the injection molding machine in embodiment of this invention. It is a time chart which shows operation | movement of the measurement processing means in embodiment of this invention. It is a figure which shows the example of the molding condition input screen in embodiment of this invention.

Explanation of symbols

11 Heating cylinder 12 Screw 41 Metering motor 53 Injection motor 71 Control unit 72 Setters AR1 to AR6 Area Sa Weighing start position Sb Weighing completion position Sc Pre-filling position

Claims (9)

(A) a cylinder member;
(B) an injection member disposed in the cylinder member so as to be rotatable and movable back and forth;
(C) in the first measurement, the injection member is retracted from a measurement start position to a predetermined position, and an initial reverse processing means for forming an initial measurement space in front of the injection member;
(D) A molding machine characterized by comprising an initial rotation processing means for rotating the injection member at the predetermined position while maintaining the position in the axial direction without moving the injection member in the axial direction.   The molding machine according to claim 1, wherein the first retreat processing unit retreats the injection member without rotating.   The molding machine according to claim 1, wherein the first retreat processing unit retreats the injection member by driving an injection drive unit.   The molding machine according to claim 1, wherein the first rotation processing unit rotates the injection member by driving a metering drive unit.   2. The molding machine according to claim 1, further comprising an initial suck back processing unit configured to retract the injection member from the predetermined position to the pre-filling position without rotating the injection member after the injection member is rotated at the predetermined position.   The molding machine according to claim 1, wherein the predetermined position is a measurement completion position. The molding machine according to claim 1, wherein the first retreat processing unit retreats the injection member while rotating the injection member at a rotation speed lower than a rotation speed in the mass production rotation process. (A) a display unit;
(B) having a display processing means for forming a molding condition input screen for inputting molding conditions to the display unit;
(C) The molding machine according to claim 1, wherein an area for setting each molding condition for initial weighing and subsequent weighing is formed on the molding condition input screen. In a control method of a molding machine having a cylinder member and an injection member that is rotatably and reciprocally disposed within the cylinder member,
(A) In the initial measurement, the injection member is retracted from a measurement start position to a predetermined position, and a space for initial measurement is formed in front of the injection member;
(B) an injection member at the predetermined position, without moving in the axial direction, the control method for a molding machine, characterized in that rotating while holding a position in the axial direction.

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