TWI654067B - Injection molding machine - Google Patents

Abstract

The present invention provides an injection molding machine capable of stabilizing the quality of a molded product. The injection molding machine of the present invention includes a driving device for a compression member for compressing a molding material in a mold device, and a controller that controls the driving device, and the controller compresses compression of the molding material in the mold device. During the stroke, the control of the driving device is switched between position control and pressure control.

Description

Injection molding machine

This application claims priority based on Japanese Patent Application No. 2014-215728 filed on October 22, 2014. The entire contents of this Japanese application are incorporated herein by reference.

The present invention relates to an injection molding machine.

An injection molding machine (see, for example, Patent Document 1) having a driving device for compressing a compression member of a molding material in a mold device is known. By compressing the molding material with the compression member, a thin-walled molded product can be obtained.

(Prior technical literature) (Patent Literature)

Patent Document 1: Japanese Patent Application Publication No. 2012-187769

Conventionally, the quality variation of a molded product obtained by compressing a molding material has been large.

This invention is made in view of the said subject, The main objective is to provide the injection molding machine which can stabilize the quality of a molded article.

In order to solve the above-mentioned problems, according to an aspect of the present invention, there is provided an injection molding machine having a driving device for a compression member for compressing a molding material in a mold device, and a controller for controlling the driving device, The controller switches the control of the drive device between position control and pressure control during a compression stroke of compressing the molding material in the mold device.

According to one aspect of the present invention, an injection molding machine capable of stabilizing the quality of a molded product is provided.

30‧‧‧Mould device

32‧‧‧Fixed

33‧‧‧ movable mold

34‧‧‧Mould cavity space

36‧‧‧ Compression member

40‧‧‧ injection device

42‧‧‧Forming materials

50‧‧‧ intermediate device

51‧‧‧block

60‧‧‧ Ejector

61‧‧‧Ejector motor

61a‧‧‧Encoder

62‧‧‧Motion Conversion Agency

63‧‧‧ Ejection

64‧‧‧ ejector board

65‧‧‧Position sensor

66‧‧‧Pressure sensor

70‧‧‧controller

FIG. 1 is a diagram showing a state at the start of a compression stroke of an injection molding machine according to an embodiment of the present invention.

Fig. 2 is a diagram showing a state at the end of a compression stroke of an injection molding machine according to an embodiment of the present invention.

Fig. 3 is a flowchart showing a compression stroke of an injection molding machine according to an embodiment of the present invention.

Hereinafter, the embodiments for implementing the present invention will be described with reference to the drawings, and the same or corresponding components are labeled with the same or corresponding element symbols in each drawing to omit description.

FIG. 1 is a diagram showing a state at the start of a compression stroke of an injection molding machine according to an embodiment of the present invention. Fig. 2 is a diagram showing a state at the end of a compression stroke of an injection molding machine according to an embodiment of the present invention. As shown in FIGS. 1 and 2, the injection molding machine includes a frame Fr, a mold clamping device 10, an injection device 40, an intermediate device 50, an ejection device 60, a controller 70, and the like.

The mold clamping device 10 performs mold closing, mold clamping, and mold opening of the mold device 30. The mold device 30 includes a fixed mold 32 and a movable mold 33. The mold clamping device 10 includes a fixed platen 12, a movable platen 13, a rear platen 15, a tie rod 16, a toggle mechanism 20, a mold clamping motor 21, and a motion conversion mechanism 25. In the following description, the moving direction of the movable platen 13 when the mold is closed (the right direction in the first and second figures) is taken as the front, and the moving direction of the movable platen 13 when the mold is opened (the first and second figures) The middle direction is the left direction).

The fixed platen 12 is fixed to the frame Fr. A fixed die 32 is mounted on a surface of the fixed platen 12 that faces the movable platen 13.

The movable platen 13 can move freely along a guide (such as a guide rail) 17 laid on the frame Fr, and can move forward and backward relative to the fixed platen 12. The movable platen 13 faces the fixed platen 12 through the middle The device 50 is equipped with a movable mold 33.

By moving the movable platen 13 forward and backward with respect to the fixed platen 12, the mold device 30 is closed, closed, and opened.

The rear platen 15 is connected to the fixed platen 12 at intervals, and is movably mounted on the frame Fr in the mold opening and closing direction. In addition, the rear pressure plate 15 may be configured to be movable along a guide member laid on the frame Fr. The guide of the rear pressure plate 15 may be used in common with the guide 17 of the movable pressure plate 13.

In addition, in this embodiment, the fixed platen 12 is fixed to the frame Fr, and the rear platen 15 is free to move in the mold opening and closing direction with respect to the frame Fr. However, the rear platen 15 may be fixed to the frame Fr, and the fixed platen 12 may be fixed to the frame Fr Move freely along the mold opening and closing direction.

The tie bar 16 connects the fixed platen 12 and the rear platen 15 at intervals. A plurality of tie rods 16 may be used. Each tie bar 16 is parallel to the mold opening and closing direction and extends in accordance with the mold clamping force. A clamping force detector 18 is provided on at least one tie rod 16. The clamping force detector 18 may be a strain ceremony, and detects the clamping force by detecting the deformation of the tie rod 16.

In addition, the clamping force detector 18 is not limited to a strain ceremony, but may be a piezoelectric type, a capacitive type, a hydraulic type, an electromagnetic type, and the like, and its installation position is not limited to the tie rod 16.

The toggle mechanism 20 is disposed between the movable platen 13 and the rear platen 15. The toggle mechanism 20 includes a cross head 20a, a plurality of links 20b, 20c, and the like. One of the links 20 b is swingably mounted on the movable platen 13, and the other link 20 c is swingably mounted on the rear platen 15. These links 20b and 20c are connected by a pin or the like to be expandable and contractible. By making The cross head 20a advances and retreats, and the plurality of links 20b, 20c expand and contract, thereby moving the movable platen 13 forward and backward relative to the rear platen 15.

The mold clamping motor 21 is attached to the rear platen 15 and advances and retracts the movable platen 13 by advancing and retreating the crosshead 20a. Between the mold clamping motor 21 and the crosshead 20a, there is provided a motion conversion mechanism 25 that converts the rotary motion of the mold clamping motor 21 into a linear motion and transmits the linear motion to the crosshead 20a. The motion conversion mechanism 25 is configured by, for example, a ball screw mechanism.

The operation of the mold clamping device 10 is controlled by a controller 70. The controller 70 controls a closed mold process, a mold closing process, an open mold process, and the like.

During the mold closing process, the mold clamping motor 21 is driven to advance the movable platen 13, thereby bringing the movable mold 33 into contact with the fixed mold 32. A compression member 36 is disposed on the movable mold 33 side, and a cavity space 34 is formed between the compression member 36 and the fixed mold 32. The compression member 36 is configured to be movable forward and backward in the mold device 30.

During the mold clamping process, the mold clamping force is generated by further driving the mold clamping motor 21. When the mold is closed, the injection device 40 fills the cavity space 34 with a liquid molding material 42. The compression member 36 is started to move in the mold device 30 in the middle of this filling, and thereby the compression of the molding material 42 is performed. After the filling process, a holding process and a cooling process are performed. During the holding process, pressure is applied to the molding material 42 in the cavity space 34. In the cooling process, the molding material 42 in the cavity space 34 is solidified to obtain a molded product.

During the mold opening process, the mold clamping motor 21 is driven to move the movable platen 13 backward, thereby separating the movable mold 33 from the fixed mold 32. After the mold-opening process is completed, the ejection device 60 ejects the molded product from the mold device 30.

The intermediate device 50 is disposed between the movable mold 33 and the movable platen 13. The intermediate device 50 includes, for example, a block 51. The rear end portion of the compression member 36 is inserted into the internal space 51 a of the block 51.

The ejection device 60 ejects the molded product from the mold device 30 after the mold is opened. The ejection device 60 includes, for example, an ejection motor 61, a motion conversion mechanism 62, and an ejection lever 63.

The ejection motor 61 is attached to the rear of the movable platen 13. The ejection motor 61 includes an encoder 61a. The encoder 61 a detects a rotation angle of the output shaft of the ejection motor 61 and outputs a signal indicating the rotation angle to the controller 70.

The motion conversion mechanism 62 converts a rotary motion of the ejection motor 61 into a linear motion of the ejection lever 63. The motion conversion mechanism 62 is configured by, for example, a ball screw mechanism.

The ejection lever 63 is configured to move forward and backward freely in the through hole of the movable platen 13. A front end portion of the ejection lever 63 is in contact with a rear end surface of the ejection plate 64.

The ejection plate 64 is configured to be movable forward and backward in the internal space 51 a of the block 51. A front end surface of the ejection plate 64 is in contact with a rear end portion of the compression member 36.

The ejection motor 61 is driven to advance the ejection lever 63, thereby advancing the compression member 36. In addition, the ejection motor 61 is driven to retract the ejection lever 63, thereby retracting the compression member 36.

The ejection device 60 functions as a driving device for the compression member 36. The compression member 36 is used for (1) compressing a molding material in the mold device 30 and (2) ejecting a molded product from the mold device 30.

The controller 70 has a CPU (Central Processing Unit) 71 and Memory medium 72 such as memory. The controller 70 causes the CPU 71 to execute a program stored in the storage medium 72, thereby controlling the mold clamping device 10, the injection device 40, the ejection device 60, and the like.

The controller 70 switches the control of the ejection device 60 between the position control and the pressure control during the compression stroke of the molding material 42 in the compression cavity space 34. You can switch from position control to pressure control, or from pressure control to position control.

In the position control of the ejection device 60, the ejection motor 61 is controlled so that the position of the compression member 36 or a member that moves with the compression member 36 becomes the set position. This control may be any of feedback control or feedforward control. The setting position can be changed continuously or intermittently over time. Examples of the member that moves with the compression member 36 include an ejector lever 63 and an ejector plate 64.

The position of the compression member 36 or a member that moves with the compression member 36 is detected by a position sensor 65. The position sensor 65 is mounted on a fixed-side member (for example, the block 51 of the intermediate device 50 in FIGS. 1 and 2), but may be mounted on a movable-side member. In addition, as the position sensor 65, an encoder 61a of the ejection motor 61 can be used.

On the other hand, in the pressure control of the ejection device 60, the ejection motor 61 is controlled so that the pressure of the molding material 42 in the cavity space 34 becomes a set pressure. This control may be any of feedback control or feedforward control. The set pressure can be changed continuously or intermittently over time.

The pressure of the molding material 42 in the cavity space 34 is detected by a pressure sensor 66. The pressure sensor 66 is mounted on a member on the movable side (for example, the first 1 and 2 show the compression member 36), but it may be mounted on a fixed member (for example, the fixed mold 32). In addition, the pressure sensor 66 may detect the pressure of the molding material 42 in the cavity space 34 by detecting the deformation of the component of the ejection device 60 or the deformation of the component of the intermediate device 50.

According to this embodiment, the position control and the pressure control are switched in the middle of the compression stroke. Therefore, control corresponding to the filling condition of the molding material 42 in the cavity space 34 can be performed, and the quality of a molded product can be stabilized. The compression stroke is divided into a plurality of processes by switching between position control and pressure control.

For example, the controller 70 performs position control on at least one of the first process and the last process among the plurality of processes.

By performing position control in the initial process, the compression member 36 can be reliably advanced to the set position, and the front surface of the compression member 36 can be used to expand the molding material 42. When the compression stroke is started, the pressure of the molding material 42 in the cavity space 34 is not stable enough. Position control in the initial process stabilizes the quality of the molded product.

By performing pressure control in the middle of the process, the molding material 42 is fully pressed against the wall surface of the cavity space 34 to improve transferability. In addition, since the pressure of the molding material 42 is stable, the density of the molding material 42 is stable.

By performing position control in the final process, the final size and shape of the cavity space 34 becomes stable, and the size and shape of the molded product become stable. By advancing the compression member 36 in the final process, the inside of the cavity space 34 is advanced. The molding material 42 is filled to end the filling of the molding material 42. After the filling process, a holding process and a cooling process are performed.

After the compression stroke is completed, the position control can be continued during the holding and cooling process to prevent the size of the cavity space 34 from changing. In this position control, movement of the compression member 36 is prohibited. This position control can also be performed until the mold opening process starts.

As shown in FIG. 3, the controller 70 can perform position control in both the initial process and the final process, and perform pressure control in processes located between these processes. In addition, in FIG. 3, the position control S11, the pressure control S12, and the position control S13 are sequentially performed in the compression stroke, but the number and order of switching are not particularly limited. For example, the controller 70 may end the pressure control S12 without switching the pressure control S12 to the position control S13. That is, only the position control S11 and the pressure control S12 may be performed sequentially. In addition, the controller 70 may perform the pressure control S12 without performing the position control S11. That is, only the pressure control S12 and the position control S13 may be performed sequentially. The compression stroke may be constituted by two or more processes, for example, it may be constituted by four or more processes.

The embodiments and the like of the injection molding machine have been described above, but the present invention is not limited to the above-mentioned embodiments and the like, and various modifications and improvements can be made within the scope of the gist of the present invention described in the patent application scope.

For example, in the above embodiment, the compression member 36 is used for (1) compressing the molding material in the mold device 30 and (2) ejecting the molded product from the mold device 30, but it may be used only for (1) compression , Not for (2) ejection. At this time, the ejection member is different from the compression member 36. The outside is disposed inside the mold device 30.

When the ejection member and the compression member 36 are separately provided, the ejection device 60 may function as a driving device that independently drives the ejection member and the compression member 36, or may function as a driving device that drives only the ejection member. In the latter case, a driving device for driving the compression member 36 is separately provided. For example, a hydraulic cylinder serving as the intermediate device 50 is used as a driving device for driving the compression member 36.

The compression member 36 of the above embodiment is disposed on the movable mold 33 side, but may be disposed on the fixed mold 32 side. At this time, the intermediate device 50 may be disposed between the fixed mold 32 and the fixed platen 12. In addition, the compression members 36 may be respectively disposed on both sides of the movable mold 33 and the fixed mold 32.

The start time of the compression stroke of the above embodiment is halfway through the filling molding material 42, but it is not particularly limited. For example, it may be performed before the filling is started, or may be performed at the same time as the filling is started.

The end time of the compression stroke of the above embodiment is substantially the same as the time at which the filling of the molding material 42 is completed, but it is not particularly limited. For example, it may be after the end of filling or before the end of filling.

Although the mold clamping device 10 of the above embodiment includes the mold clamping motor 21 as a drive source, it may include a hydraulic cylinder instead of the mold clamping motor 21. In addition, although the mold clamping device 10 includes a linear motor for mold opening and closing, it may include an electromagnet for mold clamping.

Claims (5)

An injection molding machine includes: a driving device for compressing a member that compresses a molding material by moving in a mold device; and a controller that controls the driving device that compresses the mold device. During the compression stroke of the molding material, the control of the driving device is switched between position control and pressure control. The injection molding machine described in the first item of the patent application scope, wherein the compression stroke is divided into a plurality of processes by switching between the position control and the pressure control, and the controller is configured in the plurality of processes. At least one of the first process and the last process in the process performs the aforementioned position control. The injection molding machine according to item 2 of the scope of patent application, wherein the controller performs the position control in the two processes of the initial process and the last process, and performs the pressure in the process located between the two processes. control. The injection molding machine according to any one of claims 1 to 3, wherein the driving device is an ejection device for ejecting a molded product from the mold device. The injection molding machine according to item 4 of the patent application scope, wherein the compression member is used to eject a molded product from the mold device.