WO2017164420A1

WO2017164420A1 - Injection molding machine

Info

Publication number: WO2017164420A1
Application number: PCT/JP2017/012485
Authority: WO
Inventors: 羽野　勝之; 川王; 弾水原; 浩基常深
Original assignee: 住友重機械工業株式会社
Priority date: 2016-03-25
Filing date: 2017-03-27
Publication date: 2017-09-28
Also published as: CN108602225B; JP6721672B2; CN108602225A; JPWO2017164420A1

Abstract

An injection molding machine comprises: a mold attachment board to which one of a fixed mold and a movable mold is attached; a coupling board coupled to the mold attachment board with an interval placed therebetween in a mold opening/closing direction; a mold thickness adjustment mechanism that adjusts the interval to adjust mold thickness; and a control unit that controls the mold thickness adjustment mechanism. The mold thickness adjustment mechanism has a screw shaft formed in a rod that couples the mold attachment board and the coupling board to each other, a screw nut held by one of the mold attachment board and the coupling board, and a mold thickness adjustment motor that rotates one of the screw shaft and the screw nut threadedly engaged with each other. The control unit stores a reference position of a position of the screw nut relative to the screw shaft. When the position deviates from the reference position, the control unit resets the position to the reference position.

Description

Injection molding machine

The present invention relates to an injection molding machine.

An injection molding machine described in Patent Literature 1 includes a screw shaft formed on a tie bar that connects a fixed platen and a toggle support, a screw nut that is rotatably attached to the toggle support, and a screw nut that is screwed onto the screw shaft. And a mold thickness adjusting motor to be rotated. The injection molding machine adjusts the mold thickness by adjusting the position of the toggle support by driving the mold thickness adjusting motor.

Japanese Unexamined Patent Publication No. 2006-334944

However, the position of the screw nut with respect to the screw shaft may shift after completion of the mold thickness adjustment, and the stability of the mold clamping force is low.

The present invention has been made in view of the above problems, and has as its main object to provide an injection molding machine with improved stability of mold clamping force.

In order to solve the above problems, according to one aspect of the present invention,
A mold mounting board to which one of a fixed mold and a movable mold is mounted, a connecting board connected to the mold mounting board at an interval in the mold opening / closing direction, and adjusting the distance to adjust the mold thickness. A mold thickness adjusting mechanism to perform, and a control device for controlling the mold thickness adjusting mechanism,
The mold thickness adjusting mechanism includes: a screw shaft formed on a rod that connects the mold mounting plate and the connecting plate; a screw nut held on one of the mold mounting plate and the connecting plate; A mold thickness adjusting motor for rotating one of the screw shaft and the screw nut to be combined,
An injection molding machine is provided in which the control device stores a reference position of the position of the screw nut with respect to the screw shaft, and returns the position to the reference position when the position deviates from the reference position.

According to one aspect of the present invention, an injection molding machine with improved stability of mold clamping force is provided.

It is a figure which shows the state at the time of mold opening completion of the injection molding machine by one Embodiment. It is a figure which shows the state at the time of the mold clamping of the injection molding machine by one Embodiment. It is a flowchart which shows an example of the process by the control apparatus performed after completion of mold thickness adjustment. It is a flowchart which shows the modification of the process by the control apparatus performed after completion of mold thickness adjustment. It is a figure which shows the time change of the position of the screw nut with respect to the screw shaft of the type | mold thickness adjustment mechanism by one Embodiment.

Hereinafter, modes for carrying out the present invention will be described with reference to the drawings. In each drawing, the same or corresponding components are denoted by the same or corresponding reference numerals, and description thereof will be omitted.

FIG. 1 is a diagram illustrating a state when mold opening of an injection molding machine according to an embodiment is completed. FIG. 2 is a diagram illustrating a state during mold clamping of the injection molding machine according to the embodiment. 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 ejector device 50, and a control device 90. In the following description, the moving direction of the movable platen 13 when the mold is closed (right direction in FIGS. 1 and 2) is the front, and the moving direction of the movable platen 13 when the mold is opened (left direction in FIGS. 1 and 2). This will be described as the rear.

The mold clamping apparatus 10 performs mold closing, mold clamping, and mold opening of the mold apparatus 30. The mold clamping device 10 is a horizontal mold whose mold opening and closing direction is a horizontal direction. The mold clamping device 10 includes a fixed platen 12, a movable platen 13, a toggle support 15, a tie bar 16, a toggle mechanism 20, a mold clamping motor 25, and a motion conversion mechanism 26.

The fixed platen 12 is fixed to the frame Fr. A fixed mold 32 is attached to a surface of the fixed platen 12 facing the movable platen 13.

The movable platen 13 is movable along a guide (for example, guide rail) 17 laid on the frame Fr, and is movable forward and backward with respect to the fixed platen 12. A movable mold 33 is attached to the surface of the movable platen 13 facing the fixed platen 12.

The mold is closed, clamped, and opened by moving the movable platen 13 back and forth with respect to the fixed platen 12. The fixed mold 32 and the movable mold 33 constitute a mold apparatus 30.

The toggle support 15 is connected to the fixed platen 12 with an interval L, and is placed on the frame Fr so as to be movable in the mold opening / closing direction. The toggle support 15 may be movable along a guide laid on the frame Fr. The guide of the toggle support 15 may be the same as the guide 17 of the movable platen 13.

In the present embodiment, the fixed platen 12 is fixed to the frame Fr and the toggle support 15 is movable in the mold opening / closing direction with respect to the frame Fr. However, the toggle support 15 is fixed to the frame Fr and fixed to the fixed platen. 12 may be movable in the mold opening / closing direction with respect to the frame Fr.

The tie bar 16 connects the fixed platen 12 and the toggle support 15 with an interval L therebetween. A plurality of (for example, four) tie bars 16 may be used. Each tie bar 16 is parallel to the mold opening / closing direction and extends in accordance with the mold clamping force. At least one tie bar 16 is provided with a mold clamping force detector 18. The mold clamping force detector 18 detects the mold clamping force by detecting distortion of the tie bar 16 and sends a signal indicating the detection result to the control device 90.

The clamping force detector 18 is not limited to the strain gauge type, but may be a piezoelectric type, a capacitive type, a hydraulic type, an electromagnetic type, or the like, and the mounting position thereof is not limited to the tie bar 16.

The toggle mechanism 20 moves the movable platen 13 with respect to the fixed platen 12. The toggle mechanism 20 is disposed between the movable platen 13 and the toggle support 15. The toggle mechanism 20 includes a cross head 21 and a pair of link groups. Each link group includes a first link 22 and a second link 23 that are connected to each other by a pin or the like. The first link 22 is swingably attached to the movable platen 13 with a pin or the like, and the second link 23 is swingably attached to the toggle support 15 with a pin or the like. The second link 23 is coupled to the crosshead 21 via the third link 24. When the cross head 21 is advanced and retracted, the first link 22 and the second link 23 bend and extend, and the movable platen 13 advances and retracts with respect to the toggle support 15.

The configuration of the toggle mechanism 20 is not limited to the configuration shown in FIGS. For example, in FIGS. 1 and 2, the number of nodes is five, but may be four, and one end portion of the third link 24 may be coupled to the node between the first link 22 and the second link 23. .

The mold clamping motor 25 is attached to the toggle support 15 and operates the toggle mechanism 20. The mold clamping motor 25 advances and retracts the cross head 21 to bend and extend the first link 22 and the second link 23 and advance and retract the movable platen 13.

The motion conversion mechanism 26 converts the rotational motion of the mold clamping motor 25 into the linear motion of the cross head 21. The motion conversion mechanism 26 includes a screw shaft and a screw nut that is screwed onto the screw shaft. A ball or a roller may be interposed between the screw shaft and the screw nut.

The operation of the mold clamping device 10 is controlled by the control device 90. As shown in FIGS. 1 and 2, the control device 90 includes a CPU (Central Processing Unit) 91, a storage medium 92 such as a memory, an input interface 93, and an output interface 94. The control device 90 performs various controls by causing the CPU 91 to execute a program stored in the storage medium 92. Further, the control device 90 receives a signal from the outside through the input interface 93 and transmits a signal through the output interface 94 to the outside. The control device 90 controls a mold closing process, a mold clamping process, a mold opening process, and the like.

In the mold closing process, the mold clamping motor 25 is driven to advance the cross head 21 to the mold closing completion position at a set speed, thereby moving the movable platen 13 forward and causing the movable mold 33 to touch the fixed mold 32. The position and speed of the cross head 21 are detected using, for example, the encoder 25a of the mold clamping motor 25. The encoder 25 a detects the rotation of the mold clamping motor 25 and sends a signal indicating the detection result to the control device 90.

In the mold clamping process, a mold clamping force is generated by further driving the mold clamping motor 25 to further advance the cross head 21 from the mold closing completion position to the mold clamping position. A cavity space 34 is formed between the movable mold 33 and the fixed mold 32 during mold clamping, and the injection device 40 fills the cavity space 34 with a liquid molding material. A molded product is obtained by solidifying the filled molding material. A plurality of cavity spaces 34 may be provided, and in this case, a plurality of molded products can be obtained simultaneously.

In the mold opening process, the mold clamping motor 25 is driven to retract the cross head 21 to the mold opening completion position at a set speed, thereby retracting the movable platen 13 and separating the movable mold 33 from the fixed mold 32. Thereafter, the ejector device 50 projects the molded product from the movable mold 33.

By the way, the toggle mechanism 20 amplifies the driving force of the mold clamping motor 25 and transmits it to the movable platen 13. The amplification magnification is also called toggle magnification. The toggle magnification changes according to an angle θ formed by the first link 22 and the second link 23 (hereinafter also referred to as “link angle θ”). The link angle θ is obtained from the position of the cross head 21. When the link angle θ is 180 °, the toggle magnification is maximized.

When the thickness of the mold apparatus 30 changes due to the replacement of the mold apparatus 30 or the temperature change of the mold apparatus 30, the mold thickness adjustment is performed so that a predetermined mold clamping force can be obtained at the time of mold clamping. In the mold thickness adjustment, for example, the distance L between the fixed platen 12 and the toggle support 15 is set so that the link angle θ of the toggle mechanism 20 becomes a predetermined angle when the movable mold 33 touches the fixed mold 32. Adjust.

The mold clamping device 10 includes a mold thickness adjustment mechanism 60 that performs mold thickness adjustment by adjusting the distance L between the fixed platen 12 and the toggle support 15. The mold thickness adjusting mechanism 60 rotates a screw shaft 61 formed at the rear end portion of the tie bar 16, a screw nut 62 that is rotatably held by the toggle support 15, and a screw nut 62 that is screwed onto the screw shaft 61. And a mold thickness adjusting motor 63.

The screw shaft 61 and the screw nut 62 are provided for each tie bar 16. The rotation of the mold thickness adjusting motor 63 may be transmitted to a plurality of screw nuts 62 via a rotation transmitting unit 64 constituted by a belt, a pulley or the like. The plurality of screw nuts 62 can be rotated synchronously. It should be noted that the plurality of screw nuts 62 can be individually rotated by changing the transmission path of the rotation transmission unit 64.

In addition, the rotation transmission part 64 may be comprised with a gear etc. instead of a belt, a pulley, etc. In this case, a passive gear is formed on the outer periphery of each screw nut 62, a drive gear is attached to the output shaft of the mold thickness adjusting motor 63, and a plurality of passive gears and an intermediate gear that meshes with the drive gear are in the central portion of the toggle support 15. It is held rotatably.

The operation of the mold thickness adjusting mechanism 60 is controlled by the control device 90. The control device 90 drives the mold thickness adjusting motor 63 to rotate the screw nut 62, thereby adjusting the position of the toggle support 15 that holds the screw nut 62 rotatably with respect to the fixed platen 12. The interval L with the toggle support 15 is adjusted.

In this embodiment, the screw nut 62 is rotatably held with respect to the toggle support 15 and the tie bar 16 on which the screw shaft 61 is formed is fixed to the fixed platen 12, but the present invention is not limited to this.

For example, the screw nut 62 may be rotatably held with respect to the fixed platen 12, and the tie bar 16 may be fixed with respect to the toggle support 15. In this case, the interval L can be adjusted by rotating the screw nut 62.

Further, the screw nut 62 may be fixed to the toggle support 15 and the tie bar 16 may be held rotatably with respect to the fixed platen 12. In this case, the interval L can be adjusted by rotating the tie bar 16.

Furthermore, the screw nut 62 may be fixed to the fixed platen 12 and the tie bar 16 may be held rotatably with respect to the toggle support 15. In this case, the interval L can be adjusted by rotating the tie bar 16.

The mold thickness adjusting mechanism 60 adjusts the distance L by rotating one of the screw shaft 61 and the screw nut 62 that are screwed together. A plurality of mold thickness adjusting mechanisms 60 may be used, and a plurality of mold thickness adjusting motors 63 may be used.

Here, the fixed platen 12 corresponds to the die mounting plate described in the claims, the toggle support 15 corresponds to the connecting plate described in the claims, and the tie bar 16 corresponds to the rod described in the claims. Corresponding to

For example, the control device 90 drives the mold thickness adjusting motor 63 in a state where the link angle θ of the toggle mechanism 20 is set to a predetermined angle and the mold clamping motor 25 is stopped, and the movable mold 33 touches the fixed mold 32. Detect type touch. A distance L between the fixed platen 12 and the toggle support 15 at the time when the mold touch is detected is set as a target distance L0 (not shown).

For detecting the mold touch, for example, the mold thickness adjusting motor 63 is driven to advance the toggle support 15 from the state in which the movable mold 33 is separated from the fixed mold 32, and the movable platen 13 connected to the toggle support 15 is advanced. To be done. That is, the detection of the mold touch is performed by closing the mold device 30.

¡When the movable mold 33 touches the fixed mold 32, the mold clamping force starts to increase. Therefore, the control device 90 monitors the mold clamping force while the mold thickness adjusting motor 63 is being driven, and detects a mold touch based on the mold clamping force. For example, the control device 90 may determine that the mold touch has been performed when the detection value of the mold clamping force detector 18 reaches a threshold value. For this determination, time differentiation of the detection value of the mold clamping force detector 18 may be used.

When the movable mold 33 touches the fixed mold 32, the torque of the mold thickness adjusting motor 63 starts to increase. Therefore, the control device 90 may monitor the torque of the mold thickness adjusting motor 63 while the mold thickness adjusting motor 63 is being driven, and detect the mold touch based on the torque. The control device 90 may determine that the type touch has been performed when the detection value of the torque detector 65 reaches a threshold value. For the determination, time differentiation of the detection value of the torque detector 65 may be used.

The control device 90 detects the mold touch by closing the mold device 30 with the mold thickness adjusting motor 63, but detects the mold touch by depressurizing the mold device 30 with the mold thickness adjusting motor 63. May be. The depressurization of the mold apparatus 30 is performed from the mold clamping state. When the detection value of the mold clamping force detector 18 reaches a threshold value, it may be determined that the state of the mold apparatus 30 has returned to the state of mold touch. Alternatively, when the detection value of the torque detector 65 reaches the threshold value, it may be determined that the state of the mold apparatus 30 has returned to the state of the mold touch.

Only one of the mold clamping force detector 18 and the torque detector 65 may be used for detecting the mold touch, or both of them may be used.

The control device 90 stops driving the mold thickness adjusting motor 63 after completing the mold thickness adjustment.

After the mold thickness adjustment is completed, the molding operation is repeatedly performed. Therefore, the mold clamping motor 25 repeatedly pressurizes and depressurizes the mold device 30, and the screw nut 62 is pushed backward when the mold device 30 is pressurized. When the mold apparatus 30 is depressurized, the screw nut 62 is pushed forward. As a result, the position of the screw nut 62 relative to the screw shaft 61 (hereinafter, also simply referred to as “position of the screw nut 62”) may be shifted after completion of the mold thickness adjustment.

Therefore, the control device 90 stores the position of the screw nut 62 when the mold thickness adjustment is completed as a reference position, and monitors the position of the screw nut 62. The position of the screw nut 62 is detected using, for example, the encoder 63a of the mold thickness adjusting motor 63. The encoder 63 a detects the rotation angle, rotation speed, rotation direction, and the like of the mold thickness adjustment motor 63 and sends a signal indicating the detection result to the control device 90.

FIG. 3 is a flowchart showing an example of processing performed by the control device after completion of mold thickness adjustment. The process shown in FIG. 3 is performed, for example, after the mold opening is completed and before the mold closing is started. The control device 90 may perform the processing shown in FIG. 3 for each cycle or periodically.

The control device 90 first determines whether or not the position of the screw nut 62 is deviated from the reference position (step S11). When the displacement of the screw nut 62 is outside the allowable range, it is determined that the position of the screw nut 62 is displaced from the reference position, and when the displacement of the screw nut 62 is within the allowable range, the position of the screw nut 62 is determined. It may be determined that there is no deviation from the reference position. The allowable range is set in advance based on the detection accuracy of the encoder 63a, the allowable variation range of the mold clamping force, and the like.

When the position of the screw nut 62 is not deviated from the reference position (step S11, NO), the control device 90 proceeds to step S13, and performs the processing after step S13.

On the other hand, when the position of the screw nut 62 is deviated from the reference position (step S11, YES), the control device 90 drives the mold thickness adjusting motor 63 to return the position of the screw nut 62 to the reference position (step S12). . Returning the position of the screw nut 62 to the reference position includes keeping the displacement of the screw nut 62 from outside the allowable range to within the allowable range. By returning the position of the screw nut 62 to the reference position, the stability of the clamping force can be improved. By returning the position of the screw nut 62 to the reference position, it is possible to prevent the displacement of the mold clamping force from increasing due to the accumulated displacement of the screw nut 62.

This effect is remarkable when a motor without a brake is used as the mold thickness adjusting motor 63 instead of a motor with a brake that limits the rotation of the output shaft when driving is stopped. By using a motor without a brake, it is possible to reduce the size and cost of the motor.

By the way, the thickness of the mold apparatus 30 may change due to a change in the temperature of the mold apparatus 30 after completion of the mold thickness adjustment. When the thickness of the mold apparatus 30 changes, the mold clamping force is shifted. When the mold clamping force is shifted, the control device 90 performs a process of correcting the mold clamping force.

The control device 90 determines whether or not the deviation of the mold clamping force is outside the allowable range (step S13). The deviation of the mold clamping force is a difference between the detected value of the mold clamping force and the set value of the mold clamping force. When the deviation of the mold clamping force is within the allowable range (step S13, NO), the control device 90 ends the current process.

On the other hand, when the deviation of the mold clamping force is outside the allowable range (step S13, YES), the control device 90 calculates the target displacement amount of the screw nut 62 based on the deviation of the mold clamping force (step S14). The relationship between the deviation of the mold clamping force and the target displacement amount is stored in the storage medium 92 in advance, and the control device 90 calculates the target displacement amount based on the stored data and the deviation of the mold clamping force. The larger the deviation of the mold clamping force, the larger the target displacement amount. The target displacement is calculated based on the difference between the detected value of the mold clamping force at the current position of the screw nut 62 and the set value of the mold clamping force, and is calculated so as to eliminate the difference.

Subsequently, the control device 90 corrects the reference position based on the calculated target displacement amount (step S15). The new reference position is obtained from the position at the time of target displacement calculation and the target displacement, and from the position at the time of target displacement calculation so that there is no difference between the detected value of mold clamping force and the set value of mold clamping force. The target displacement amount is moved. When the detected value of the mold clamping force is larger than the set value, the control device 90 changes the reference position in the direction in which the distance L between the toggle support 15 and the fixed platen 12 becomes wider. On the other hand, when the detected value of the mold clamping force is smaller than the set value, the control device 90 changes the reference position in the direction in which the distance L between the toggle support 15 and the fixed platen 12 is narrowed.

Subsequently, the control device 90 drives the mold thickness adjusting motor 63 to displace the position of the screw nut 62 to the corrected reference position (step S16), and ends the current process. By aligning the position of the screw nut 62 with the corrected reference position, the detected value of the mold clamping force matches the set value of the mold clamping force. Thereby, stability of mold clamping force can be improved more.

In addition, the process by the control apparatus 90 performed after completion | finish of mold thickness adjustment is not limited to the process shown in FIG. For example, the control device 90 may perform only steps S11 to S12 and may not perform the process of correcting the mold clamping force.

FIG. 4 is a flowchart showing a modification of the process performed by the control device after completion of mold thickness adjustment. The process shown in FIG. 4 is performed, for example, after the mold opening is completed and before the mold closing is started. The control device 90 may perform the process shown in FIG. 4 for each cycle or periodically.

The control device 90 first determines whether or not the mold clamping force correction for correcting the reference position of the screw nut 62 is being used (step S21). Whether or not to use the mold clamping force correction is switched by, for example, an input operation by the user.

When the mold clamping force correction is used (step S21, YES), the control device 90 determines whether or not the deviation of the mold clamping force is outside the allowable range (step S13). When the deviation of the mold clamping force is outside the allowable range (step S13, YES), the control device 90 proceeds to step S14 and performs the processes after step S14.

In step S14, as described above, the target displacement amount of the screw nut 62 is calculated based on the deviation of the clamping force. The relationship between the deviation of the mold clamping force and the target displacement amount is stored in the storage medium 92 in advance, and the control device 90 calculates the target displacement amount based on the stored data and the deviation of the mold clamping force. The larger the deviation of the mold clamping force, the larger the target displacement amount. The target displacement is calculated based on the difference between the detected value of the mold clamping force at the current position of the screw nut 62 and the set value of the mold clamping force, and is calculated so as to eliminate the difference.

In step S15 following step S14, the reference position is corrected based on the calculated target displacement amount as described above. The new reference position is obtained from the position at the time of target displacement calculation and the target displacement, and from the position at the time of target displacement calculation so that there is no difference between the detected value of mold clamping force and the set value of mold clamping force. The target displacement amount is moved. When the detected value of the mold clamping force is larger than the set value, the control device 90 changes the reference position in the direction in which the distance L between the toggle support 15 and the fixed platen 12 becomes wider. On the other hand, when the detected value of the mold clamping force is smaller than the set value, the control device 90 changes the reference position in the direction in which the distance L between the toggle support 15 and the fixed platen 12 is narrowed.

In step S16 following step S15, as described above, the mold thickness adjusting motor 63 is driven to displace the position of the screw nut 62 to the corrected reference position. By aligning the position of the screw nut 62 with the corrected reference position, the detected value of the mold clamping force matches the set value of the mold clamping force. Thereby, stability of mold clamping force can be improved more. After step S16, the control device 90 ends the current process.

On the other hand, when the mold clamping force correction is not used (step S21, NO), or when the mold clamping force correction is used (step S21, YES) and the deviation of the mold clamping force is within an allowable range (step S21, NO). In step S13, NO), the control device 90 proceeds to step S11 and performs the processes in and after step S11.

In step S11, as described above, it is determined whether or not the position of the screw nut 62 is shifted from the reference position. When the displacement of the screw nut 62 is outside the allowable range, it is determined that the position of the screw nut 62 is displaced from the reference position, and when the displacement of the screw nut 62 is within the allowable range, the position of the screw nut 62 is determined. It may be determined that there is no deviation from the reference position. The allowable range is set in advance based on the detection accuracy of the encoder 63a, the allowable variation range of the mold clamping force, and the like.

In step S11, when the position of the screw nut 62 is not deviated from the reference position (step S11, NO), the control device 90 ends the current process.

On the other hand, when the position of the screw nut 62 is shifted from the reference position in step S11 (step S11, YES), the control device 90 proceeds to step S12.

In step S12, as described above, the mold thickness adjusting motor 63 is driven to return the position of the screw nut 62 to the reference position. Returning the position of the screw nut 62 to the reference position includes keeping the displacement of the screw nut 62 from outside the allowable range to within the allowable range. By returning the position of the screw nut 62 to the reference position, the stability of the clamping force can be improved. By returning the position of the screw nut 62 to the reference position, it is possible to prevent the displacement of the mold clamping force from increasing due to the accumulated displacement of the screw nut 62.

FIG. 5 is a diagram showing a change with time of the position of the screw nut with respect to the screw shaft of the mold thickness adjusting mechanism according to one embodiment. In FIG. 5, the passage of time is represented by the number of shots. In addition, although the position of the screw nut 62 fluctuates linearly in FIG.

After the mold thickness adjustment is completed, the molding operation is repeatedly performed. Therefore, the mold clamping motor 25 repeatedly pressurizes and depressurizes the mold device 30, and the screw nut 62 is pushed backward when the mold device 30 is pressurized. The toggle support 15 is pushed backward.

As a result, the position of the screw nut 62 with respect to the screw shaft 61 may shift after completion of the mold thickness adjustment. The position of the screw nut 62 tends to shift in the direction in which the toggle support 15 moves backward and the interval L increases.

Therefore, the control device 90 stores the position of the screw nut 62 when the mold thickness adjustment is completed as the reference position 1, and monitors the position of the screw nut 62. The position of the screw nut 62 is detected using, for example, the encoder 63a of the mold thickness adjusting motor 63. The encoder 63 a detects the rotation angle, rotation speed, rotation direction, and the like of the mold thickness adjustment motor 63 and sends a signal indicating the detection result to the control device 90.

The control device 90 monitors whether or not the position of the screw nut 62 is shifted from the reference position 1. When the position of the screw nut 62 is out of the allowable range of the reference position 1, it is determined that the position of the screw nut 62 is deviated from the reference position 1. On the other hand, when the position of the screw nut 62 falls within the allowable range of the reference position 1, it is determined that the position of the screw nut 62 is not shifted from the reference position 1. The allowable range is set in advance based on the detection accuracy of the encoder 63a, the allowable variation range of the mold clamping force, and the like.

As shown in FIG. 5, the control device 90 drives the mold thickness adjusting motor 63 to correct the position of the screw nut 62 every time it determines that the position of the screw nut 62 is shifted from the reference position 1. The correction of the position of the screw nut 62 is to accurately return the position of the screw nut 62 to the reference position 1 in FIG. 5, but the position of the screw nut 62 may be within the allowable range of the reference position 1. By keeping the position of the screw nut 62 within the allowable range of the reference position 1, the stability of the clamping force can be improved.

By the way, the thickness of the mold apparatus 30 may change due to a change in the temperature of the mold apparatus 30 after completion of the mold thickness adjustment. Since the temperature of the mold apparatus 30 tends to increase with the passage of time, the thickness of the mold apparatus 30 tends to increase with the passage of time. However, the thickness of the mold apparatus 30 may be reduced.

When the thickness of the mold apparatus 30 changes, the mold clamping force may deviate from the target mold clamping force when the position of the screw nut 62 coincides with the reference position 1. Therefore, when the thickness of the mold apparatus 30 changes, the stability of the mold clamping force may be impaired only by monitoring the position of the screw nut 62.

Therefore, the control device 90 may monitor not only the position of the screw nut 62 but also the mold clamping force. The mold clamping force is detected by a mold clamping force detector 18. The control device 90 monitors whether or not the detection value of the mold clamping force is within the set value allowable range. When the detected value of the mold clamping force is within the allowable range of the set value, it is determined that the mold clamping force is not deviated from the target mold clamping force. On the other hand, when the detected value of the mold clamping force is out of the allowable range of the set value, it is determined that the mold clamping force is deviated from the target mold clamping force.

When the control device 90 determines that the mold clamping force is deviated from the target mold clamping force, the control device 90 performs correction to change the reference position of the screw nut 62 from the reference position 1 to the reference position 2 as shown in FIG. The correction amount is set so that the mold clamping force matches the target mold clamping force when the position of the screw nut 62 matches the reference position 2. Accordingly, the reference position of the screw nut 62 can be appropriately changed in accordance with the variation in the thickness of the mold apparatus 30, and the effect of monitoring the position of the screw nut 62 can be maximized.

After correcting the reference position, the control device 90 monitors whether the position of the screw nut 62 is deviated from the reference position 2 or not. When the position of the screw nut 62 is out of the allowable range of the reference position 2, it is determined that the position of the screw nut 62 is deviated from the reference position 2. On the other hand, when the position of the screw nut 62 falls within the allowable range of the reference position 2, it is determined that the position of the screw nut 62 is not shifted from the reference position 2. The allowable range is set in advance based on the detection accuracy of the encoder 63a, the allowable variation range of the mold clamping force, and the like.

As shown in FIG. 5, the control device 90 drives the mold thickness adjusting motor 63 to correct the position of the screw nut 62 every time it determines that the position of the screw nut 62 is shifted from the reference position 2. The position correction of the screw nut 62 is to accurately return the position of the screw nut 62 to the reference position 2 in FIG. 5, but the position of the screw nut 62 may be within the allowable range of the reference position 2. By keeping the position of the screw nut 62 within the allowable range of the reference position 2, the stability of the clamping force can be improved.

The embodiments of the injection molding machine have been described above, but the present invention is not limited to the above embodiments and the like, and various modifications are possible within the scope of the gist of the present invention described in the claims. Improvements are possible.

The mold clamping device 10 of the above embodiment is a horizontal mold whose horizontal direction is the mold opening / closing direction, but may be a vertical mold whose vertical direction is the mold opening / closing direction.

竪 The vertical mold clamping device has a lower platen, upper platen, toggle support, tie bar, toggle mechanism, mold clamping motor, mold thickness adjusting mechanism, and the like. One of the lower platen and the upper platen is used as a fixed platen, and the other is used as a movable platen. A lower mold is attached to the lower platen, and an upper mold is attached to the upper platen. The lower die and the upper die constitute a mold apparatus. The lower mold may be attached to the lower platen via a rotary table. The toggle support is disposed below the lower platen. The toggle mechanism is disposed between the toggle support and the lower platen. The tie bar is parallel to the vertical direction, passes through the lower platen, and connects the upper platen and the toggle support.

竪 The vertical mold thickness adjustment mechanism adjusts the mold thickness by adjusting the distance between the upper platen and the toggle support according to changes in the thickness of the mold apparatus. In this mold thickness adjustment, the interval between the upper platen and the toggle support is adjusted so that the link angle of the toggle mechanism becomes a predetermined angle at the time of mold touch when the lower mold and the upper mold touch. The link angle can be adjusted to a predetermined angle when mold closing is completed, and a predetermined mold clamping force can be obtained during mold clamping. The mold thickness adjusting mechanism includes a screw shaft formed on the tie bar, a screw nut held on one of the upper platen and the toggle support, and a mold thickness adjusting motor that rotates one of the screw shaft and the screw nut that are screwed together. Have. The mold thickness adjusting mechanism may further include a screw nut held on the other of the upper platen and the toggle support. The upper platen corresponds to the mold mounting plate described in the claims, the toggle support corresponds to the connecting plate described in the claims, and the tie bar corresponds to the rod described in the claims.

The mold clamping device 10 of the above embodiment has a toggle mechanism 20 and a mold clamping motor 25 that operates the toggle mechanism 20, but may have a linear motor for mold opening and closing and an electromagnet for mold clamping.

The electromagnet type mold clamping device has, for example, a fixed platen, a movable platen, a rear platen, a tie bar, a suction plate, a rod, and a mold thickness adjusting mechanism. The rear platen is disposed on the side opposite to the stationary platen with respect to the movable platen (that is, behind the movable platen). The tie bar connects the fixed platen and the rear platen at an interval in the mold opening / closing direction. The suction plate can move forward and backward together with the movable platen behind the rear platen. The rod is inserted into the through hole of the rear platen and connects the movable platen and the suction plate. An electromagnet is formed on at least one of the rear platen and the attracting plate, and an attracting force by the electromagnet acts between the rear platen and the attracting plate to generate a clamping force.

Electromagnet type mold thickness adjustment mechanism adjusts the mold thickness by adjusting the distance between the movable platen and the suction plate. In this mold thickness adjustment, the distance between the movable platen and the suction plate is adjusted so that a predetermined gap is formed between the suction plate and the rear platen at the time of the mold touch when the movable mold and the fixed mold touch. To do. A predetermined gap can be formed between the suction plate and the rear platen when the mold closing is completed, and a predetermined mold clamping force can be obtained at the time of mold clamping. The mold thickness adjusting mechanism includes a screw shaft formed on the rod, a screw nut held on one of the movable platen and the suction plate, and a mold thickness adjusting motor that rotates one of the screw shaft and the screw nut that are screwed together. Have. The mold thickness adjusting mechanism may further include a screw nut held on the other of the movable platen and the suction plate. The movable platen corresponds to the mold mounting plate described in the claims, and the suction plate corresponds to the connecting plate described in the claims.

This application claims priority based on Japanese Patent Application No. 2016-062418 filed with the Japan Patent Office on March 25, 2016, and the entire contents of Japanese Patent Application No. 2016-062418 are incorporated herein by reference. .

DESCRIPTION OF SYMBOLS 10 Clamping apparatus 12 Fixed platen 13 Movable platen 15 Toggle support 16 Tie bar 18 Clamping force detector 20 Toggle mechanism 21 Crosshead 25 Clamping motor 26 Motion conversion mechanism 30 Mold apparatus 40 Injection apparatus 50 Ejector apparatus 60 Mold thickness adjustment mechanism 61 Screw shaft 62 Screw nut 63 Mold thickness adjusting motor 64 Rotation transmission unit 65 Torque detector

Claims

A mold mounting board to which one of a fixed mold and a movable mold is mounted, a connecting board connected to the mold mounting board at an interval in the mold opening / closing direction, and adjusting the distance to adjust the mold thickness. A mold thickness adjusting mechanism to perform, and a control device for controlling the mold thickness adjusting mechanism,
The mold thickness adjusting mechanism includes: a screw shaft formed on a rod that connects the mold mounting plate and the connecting plate; a screw nut held on one of the mold mounting plate and the connecting plate; A mold thickness adjusting motor for rotating one of the screw shaft and the screw nut to be combined,
The said control apparatus memorize | stores the reference position of the position of the said screw nut with respect to the said screw shaft, and will return the said position to the said reference position if the said position shift | deviates from the said reference position.
2. The injection molding machine according to claim 1, wherein the control device corrects the reference position based on a difference between a detected value of the mold clamping force and a set value of the mold clamping force.