TWI717456B - Injection molding machine - Google Patents

Abstract

The subject of the present invention is to provide an injection molding machine capable of suppressing the discontinuity of temperature control of the tie rod and improving the accuracy of the temperature control of the tie rod.

The injection molding machine of the solution of the present invention is provided with: a plurality of tie rods extending according to the clamping force; a heater to heat the tie rods; and a controller to control the heater, and the controller adjusts by the heating The temperature of the heating part of the tie rod heated by the device is adjusted to adjust the balance of the axial force of the plural tie rods, and the reference temperature of the heating part used in the adjustment of the balance is set to be higher than the non-heating based on the heater When the stable temperature of the heating section is higher.

Description

Injection molding machine

The invention relates to an injection molding machine.

The injection molding machine has a mold clamping device that performs mold closing, mold clamping, and mold opening. The mold clamping device has a plurality of tie rods extending in accordance with the mold clamping force (for example, refer to Patent Document 1). The clamping force is dispersed and applied to a plurality of tie rods, so that each tie rod extends. The force that hinders the extension of the tie rod is called the axial force.

When there is a difference in the effective length of a plurality of tie rods, a difference in axial force occurs between a tie rod with a shorter effective length and a tie rod with a longer effective length. Here, the effective length of the tie rod refers to the distance between the members connected by the tie rod, for example, it is measured in a state where the clamping force is not acting.

The effective length of the tie rod varies depending on the temperature of the tie rod. The higher the temperature of the tie rod, the longer the effective length of the tie rod. By adjusting the temperature of the tie rod, the effective length of the tie rod can be adjusted, and the balance of the axial force can be adjusted.

In the injection molding machine described in Patent Document 1, when adjusting the effective length of the tie rod, both a band heater for heating the tie rod and a water jacket for cooling the tie rod are used. Based on the heating capacity of the band heater and based on the water The amount of cooling in the sleeve is used as the amount of manipulation to manipulate the temperature of the tie rod.

(Prior technical literature) (Patent Document)

Patent Document 1: Japanese Patent Application Publication No. 2008-114513

In the past, the type of the manipulation amount of the temperature of the manipulation tie rod was switched, and the mechanism of the influence of the manipulation amount on the temperature was sometimes switched. As a result, the temperature control of the tie rod may become discontinuous, and the accuracy of the temperature control of the tie rod may decrease.

The present invention was made in view of the above-mentioned problems, and its main object is to provide an injection molding machine capable of suppressing the discontinuity of temperature control of the tie rod and improving the accuracy of the temperature control of the tie rod.

In order to solve the above-mentioned problems, an injection molding machine is provided according to one aspect of the present invention. The injection molding machine includes: a plurality of tie rods that extend according to the clamping force; a heater for heating the tie rods; and a controller , Control the heater, the controller adjusts the temperature of the heating part of the tie rod heated by the heater, adjusts the balance of the axial force of the plurality of tie rods, and is used for the heating part in the balance adjustment The reference temperature is It is set to a higher temperature than the stable temperature of the heating part during non-heating by the heater, and it has a heat transfer limiter that limits heat transfer from the heating part of the tie rod, and an axial force detector, The axial force of the tie rod is detected, and the axial force detector is based on the heat transfer limiter and is arranged on the opposite side of the heater.

According to one aspect of the present invention, there is provided an injection molding machine capable of suppressing the discontinuity of temperature control of the tie rod and improving the accuracy of the temperature control of the tie rod.

10: Mold clamping device

12: Fixed pressure plate

13: movable pressure plate

15: Rear pressure plate

16: tie rod

17: Guide (rail)

20: toggle mechanism

20a: cross head

20b: connecting rod

20c: connecting rod

21: Clamping motor

25: heater

26: Heat transfer limiter

27: Temperature detector

28: Axial force detector

30: Mould device

32: Fixed mold

33: Active mode

70: operating device

80: display device

90: Controller

91: CPU

92: memory media

Fr: frame

Fig. 1 is a diagram showing the state of the injection molding machine at the end of mold opening according to an embodiment.

Fig. 2 is a diagram showing the state of the injection molding machine of the embodiment when the mold is closed.

Fig. 3 is a diagram showing the positional relationship of the tie rods of the injection molding machine of one embodiment, and is a diagram of the fixed platen viewed from the movable platen side.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding components are given the same or corresponding reference numerals, and their descriptions are omitted.

Fig. 1 is a diagram showing the state of the injection molding machine at the end of mold opening according to an embodiment. Fig. 2 is a diagram showing the state of the injection molding machine according to an embodiment when the mold is closed. The injection molding machine has a frame Fr, a mold clamping device 10, an operating device 70, a display device 80, a controller 90, and the like.

The controller 90 has a CPU (Central Processing Unit) 91 and a storage medium 92 such as a memory. The controller 90 causes the CPU 91 to execute a program stored in the storage medium 92, thereby controlling the mold clamping device 10, the operating device 70, the display device 80, and the like.

The controller 90 is connected to the operating device 70 and the display device 80. The operation device 70 and the display device 80 are constituted by, for example, a touch panel, and may be integrated. The operating device 70 receives input operations based on the user, and outputs signals corresponding to the input operations to the controller 90. The display device 80 displays an operation screen corresponding to the input operation in the operation device 70 under the control of the controller 90. The operation screen is used to set up the injection molding machine. Prepare multiple operation screens, switch display or overlap display. The user operates the operation device 70 while viewing the operation screen displayed on the display device 80, thereby setting the injection molding machine and the like.

In addition, the operating device 70 and the display device 80 of this embodiment are integrated, but they may be provided separately. In addition, a plurality of operating devices 70 may be provided.

The mold clamping device 10 performs mold closing, mold clamping, and mold opening of the mold device 30. The mold clamping device 10 has a fixed pressure plate 12, a movable pressure plate 13, a rear pressure plate 15, a tie rod 16, a toggle mechanism 20 and a mold clamping motor 21. Hereinafter, the moving direction of the movable platen 13 when the mold is closed (the right direction in Figures 1 and 2) is taken as the front, and the moving direction of the movable platen 13 when the mold is opened (in Figures 1 and 2) The left direction) will be described as the rear.

The fixed pressing plate 12 is fixed to the frame Fr. A fixed mold 32 is installed on the side of the fixed pressing plate 12 opposite to the movable pressing plate 13.

The movable pressing plate 13 is free to move along the guide (for example, a guide rail) 17 laid on the frame Fr, and is free to advance and retreat relative to the fixed pressing plate 12. A movable mold 33 is installed on the side of the movable pressing plate 13 opposite to the fixed pressing plate 12.

The movable pressing plate 13 is advanced and retreated relative to the fixed pressing plate 12, thereby performing mold closing, mold clamping, and mold opening. The fixed mold 32 and the movable mold 33 constitute a mold device 30.

The rear platen 15 is connected to the fixed platen 12 with an interval therebetween, and is placed on the frame Fr movably in the mold opening and closing direction. In addition, the rear pressure plate 15 can move freely along the guides laid on the frame Fr. The guide member of the rear pressure plate 15 can be shared with the guide member 17 of the movable pressure plate 13.

In addition, in this embodiment, the fixed pressing plate 12 is fixed to the frame Fr, and the rear pressing plate 15 is free to move in the mold opening and closing direction relative to the frame Fr. However, it may also be as follows: the rear pressing plate 15 is fixed to the frame Fr, and the fixed pressing plate 12 is relative to The frame Fr can move freely in the mold opening and closing direction.

The tie rod 16 connects the fixed pressing plate 12 and the rear pressing plate 15 at an interval. Use a plurality of tie rods 16. Each tie rod 16 is parallel along the mold opening and closing direction, and extends according to the mold clamping force. Each tie rod 16 is formed of metal or the like.

The toggle mechanism 20 is arranged between the movable pressing plate 13 and the rear pressing plate 15. The toggle mechanism 20 is composed of a crosshead 20a, a plurality of links 20b, 20c, and the like. One link 20b is swingably mounted on the movable pressing plate 13, and the other link 20c is swingably mounted on the rear pressing plate 15. The connecting rods 20b and 20c are flexibly connected by pins or the like. The crosshead 20a advances and retreats, so that the plurality of connecting rods 20b and 20c expand and contract, and the movable pressure plate 13 advances and retreats relative to the rear pressure plate 15.

The mold clamping motor 21 is installed on the rear pressing plate 15 and causes the cross head 20 a to advance and retreat, so that the movable pressing plate 13 advances and retreats. A movement conversion mechanism is provided between the mold clamping motor 21 and the crosshead 20a to convert the rotational movement of the mold clamping motor 21 into linear motion and transmit it to the crosshead 20a. The motion conversion mechanism is constituted by, for example, a ball screw mechanism.

The operation of the mold clamping device 10 is controlled by the controller 90. The controller 90 controls the mold closing process, the mold clamping process, the mold opening process, and the like.

During the mold closing process, the mold clamping motor 21 is driven to advance the movable pressing plate 13 so that the movable mold 33 is in contact with the fixed mold 32.

During the mold clamping process, the mold clamping motor 21 is further driven to generate a mold clamping force. When the mold is closed, a cavity space is formed between the movable mold 33 and the fixed mold 32, and the cavity space is filled with a liquid molding material. The molding material in the cavity space is hardened to become a molded product.

During the mold opening process, the mold clamping motor 21 is driven to retreat the movable pressing plate 13 so as to separate the movable mold 33 from the fixed mold 32.

In addition, the mold clamping device 10 of the present embodiment has a mold clamping motor 21 as a drive source for moving the movable platen 13, but may have a hydraulic cylinder instead of the mold clamping motor 21. Moreover, the mold clamping device 10 may have a linear motor used for mold opening and closing, and an electromagnet used for mold clamping.

Fig. 3 is a diagram showing the positional relationship of the tie bars of the injection molding machine according to one embodiment, and the fixed platen is viewed from the movable platen side. The injection molding machine has four tie rods 16. When viewed from the direction of opening and closing the mold, the four tie rods 16 are arranged symmetrically about the horizontal line L1 as the center, and arranged symmetrically about the vertical line L2 as the center. The upper side than the horizontal line L1 is called the top On the side, the side below the horizontal line L1 is referred to as the bottom side. In addition, the side closer to the operating device 70 than the vertical line L2 is called the operating side, and the side closer to the operating device 70 than the vertical line L2 is called the reverse operating side.

The clamping force is dispersed and applied to the four tie rods 16 so that each tie rod 16 extends. The force hindering the extension of each tie rod 16 is referred to as an axial force. When the effective lengths of the four tie rods 16 are different, a difference in axial force occurs between the tie rod 16 with a shorter effective length and the tie rod 16 with a longer effective length. Here, the effective length of the tie rod 16 refers to the distance between the fixed pressure plate 12 and the rear pressure plate 15 connected by the tie rod 16, for example, the measurement is performed in a state where the clamping force is not applied.

The balance of the axial force can be adjusted by adjusting the effective length of the tie rod 16. The balance of the axial force is set so that, for example, the surface pressure of the fixed mold 32 and the movable mold 33 becomes a target distribution when the mold is closed. The target distribution may be any one of uniform distribution and uneven distribution, and is set according to the situation. Can reduce molding defects.

The effective length of the tie rod 16 changes according to the temperature of the tie rod 16. The higher the temperature of the tie rod 16, the longer the effective length of the tie rod 16. By adjusting the temperature of the tie rod 16, the effective length of the tie rod 16 can be adjusted, so that the balance of the axial force can be adjusted.

Therefore, as shown in FIGS. 1 and 2, a heater 25, a heat transfer limiter 26, a temperature detector 27, an axial force detector 28, and the like are installed in each tie rod 16. The mold clamping device 10 includes a heater 25, a heat transfer limiter 26, a temperature detector 27, an axial force detector 28, and the like.

In order to adjust the effective length of the tie rod 16, the heater 25 controls the tie rod 16 Heat up. The range heated by the heater 25 is referred to as the heating part of the tie rod 16. The heater 25 is constituted by, for example, an electric heater such as a heater. In addition, the heater 25 is not limited to an electric heater, and may be constituted by a warm water jacket or the like, for example.

The heat transfer limiter 26 limits the heat transfer from the heating part of the tie rod 16. The time until the temperature of the entire mold clamping device 10 becomes stable can be shortened, and the time until the balance of the axial force becomes stable can be shortened. In addition, the range of the heating portion of the tie rod 16 can be managed, so the amount of change in the effective length based on the temperature change of the tie rod 16 can be managed with high accuracy, and the axial force can be adjusted with high accuracy.

The heat transfer limiter 26 may be arranged on both axial sides of the tie rod 16 with the heater 25 interposed therebetween. The time until the temperature of the entire mold clamping device 10 becomes stable can be further shortened, and the time until the balance of the axial force becomes stable can be further shortened. In addition, the amount of change in the effective length based on the temperature change of the tie rod 16 can be managed with higher accuracy, and the axial force can be adjusted with higher accuracy.

The heat transfer limiter 26 is constituted by, for example, a water cooling jacket. In addition, the heat transfer limiter 26 is not limited to a water cooling jacket, and may be constituted by, for example, a heat sink. The cooling method of the heat sink can use any of the forced air cooling method and the natural air cooling method of the heat sink.

The heat transfer limiter 26 is not used for the purpose of adjusting the effective length of the tie rod 16 but for the purpose of managing the range of the heating part of the tie rod 16. The effective length of the tie rod 16 is adjusted by the heater 25 instead of the heat transfer limiter 26. Therefore, the heat transfer limiter 26 may not be installed on the tie rod 16.

The temperature detector 27 detects the temperature of the heating part of the tie rod 16. For example, the temperature detector 27 is arranged in the vicinity of the heater 25 and arranged between the plurality of heat transfer limiters 26.

The temperature detector 27 outputs the detection result to the controller 90. The controller 90 controls the heater 25 based on the actual temperature detected by the temperature detector 27 and the set temperature. For example, the controller 90 controls the heater 25 so that the actual temperature becomes the set temperature. This control may be either feedback control or feedforward control.

The axial force detector 28 detects the axial force of the tie rod 16 heated by the heater 25. The axial force detector 28 is, for example, a strain gauge, and detects the axial force of the tie rod 16 by detecting the deformation of the tie rod 16.

In addition, the axial force detector 28 of the above-mentioned embodiment is a strain gauge, but it may be a piezoelectric type, a capacitive type, a hydraulic type, an electromagnetic type, or the like.

The axial force detector 28 outputs the detection result to the controller 90. The controller 90 measures the balance of the axial forces of the plurality of tie rods 16 through the axial force detector 28.

The axial force detector 28 is arranged on the side opposite to the heater 25 based on the heat transfer limiter 26. An axial force detector 28 is arranged outside the heating range by the heater 25. The temperature rise of the axial force detector 28 can be suppressed, and the measurement error of the axial force detector 28 can be reduced.

As shown in FIGS. 1 and 2, the axial force detector 28 is arranged, for example, on the rear side of the heat transfer limiter 26, and the heat transfer limiter 26 is arranged on the rear side of the heater 25. In addition, the axial force detector 28 is arranged in the The heat limiter 26 is further on the front side, and the heat transfer limiter 26 is arranged on the front side than the heater 25.

In addition, the axial force detector 28 of the present embodiment is arranged at a position opposite to the heater 25 with the heat transfer limiter 26 as a reference, but it may be arranged at a position overlapping with the heat transfer limiter 26. Even in this case, the temperature rise of the axial force detector 28 can be suppressed, and the measurement error of the axial force detector 28 can be reduced.

The controller 90 adjusts the temperature of the heating part of the tie rod 16 heated by the heater 25 and adjusts the balance of the axial forces of the plurality of tie rods 16. The reference temperature T0 of the heating part of the tie rod 16 used in the balance adjustment is set to a higher temperature than the stable temperature TS of the heating part of the tie rod 16 when the heater 25 is not heated.

The non-heating time by the heater 25 means, for example, when the heater 25 is an electric heater and the supply of electrodes to the electric heater is stopped, and when the heater 25 is a warm water jacket, the supply of warm water to the warm water jacket is stopped.

In addition, the stable temperature TS refers to the temperature of the heating part of the tie rod 16 when the temperature of the entire mold clamping device 10 becomes stable when the heater 25 is not heated. Here, the settings of devices other than the heater 25 (for example, a thermostat for adjusting the temperature of the mold device 30, an injection device for filling the mold device 30 with a liquid molding material, etc.) are the same.

The controller 90 measures, for example, the balance of the axial forces of the plurality of tie rods 16 when the temperature of the heating part of the tie rod 16 is the reference temperature T0. If the balance is within the allowable range, the controller 90 maintains the temperature of the heating part of the tie rod 16 at the reference temperature T0. On the other hand, if the balance is outside the allowable range, the controller 90 increases or decreases the temperature of the heating part of the tie rod 16 according to the difference. Then, the controller 90 measures the balance of the axial forces of the plurality of tie rods 16 again. Then, the temperature adjustment of the heating part of the tie rod 16 and the measurement of the balance of the axial force can be repeated until the balance is suppressed within the allowable range.

According to the present embodiment, as described above, the reference temperature T0 of the heating part of the tie rod 16 used in the adjustment of the balance is set to a temperature higher than the stable temperature TS. Thereby, it is possible to adjust both the temperature rise and the temperature drop from the reference temperature T0 only by the magnitude of the heating amount of the heater 25, without switching the type of the manipulation amount of the manipulation temperature, and also without switching the manipulation amount given to the temperature The mechanism of its influence. Thereby, the discontinuity of the temperature control of the tie rod 16 can be suppressed, and the accuracy of the temperature control of the tie rod 16 can be improved.

The adjustment range of the temperature of the heating part of the tie rod 16 used in the adjustment of the balance is a temperature range higher than the stable temperature TS of the heating part. Since the temperature of the tie rod 16 is adjusted only by the size of the heating amount of the heater 25, the type of the manipulation amount of the manipulation temperature is not changed, and the mechanism of the influence of the manipulation amount on the temperature is not changed. Thereby, the discontinuity of the temperature control of the tie rod 16 can be further suppressed, and the accuracy of the temperature control of the tie rod 16 can be further improved.

The reference temperature T0 of the heating part of the tie rod 16 used in the adjustment of the balance can be set to a temperature higher than the temperature around the heating part by a predetermined value. Here, the temperature around the heating unit is, for example, the temperature of the ambient atmosphere of the heating unit. Since the reference temperature T0 changes in accordance with the temperature change of the surrounding atmosphere of the heating unit, it is possible to adjust the balance corresponding to the temperature change of the surrounding atmosphere of the heating unit.

In addition, the controller 90 of the present embodiment controls the heater 25 and does not control the heat transfer limiter 26, but it may also control the heat transfer limiter 26. The controller 90 controls the heat transfer limiter 26 so that the temperature of the tie rod becomes the set temperature near the heat transfer limiter 26.

The embodiments 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 spirit of the present invention described in the scope of the patent application.

For example, in the above-mentioned embodiment, the heater 25, the heat transfer limiter 26, the temperature detector 27, the axial force detector 28, etc. are installed in all the tie rods 16, but may be installed in only a part of the tie rods 16. For example, when the controller 90 adjusts the balance of the axial force in the vertical direction (hereinafter referred to as "the balance of the vertical axial force") and the balance of the axial force in the horizontal direction, it can be set to 4 A heater 25, a heat transfer limiter 26, and a temperature detector 27 are installed in only three of the tie rods 16. Moreover, when the controller 90 adjusts only the vertical axial force balance, the heater 25, the heat transfer limiter 26, and the temperature detector 27 may be attached to the tie rod 16 on one of the top side and the bottom side. In addition, when the controller 90 only adjusts the vertical axial force balance, one of the two tie rods 16 on the top side and one of the two tie rods 16 on the bottom side can be installed with axial force detection.器28.

In addition, the mold clamping device 10 of the above-described embodiment is a horizontal type in which the mold opening and closing directions are horizontal, but may be a vertical type in which the mold opening and closing directions are in the vertical direction. The vertical mold clamping device has a lower pressing plate, an upper pressing plate, a toggle seat, a toggle mechanism and a tie rod. Either one of the lower pressing plate and the upper pressing plate is used as a fixed pressing plate, and the remaining one is used as a movable pressing plate. Install the lower mold on the lower platen, and Install the upper mold on the upper platen. The lower mold and the upper mold constitute a mold device. The lower mold can be installed on the lower platen via the turntable. The toggle seat is arranged under the lower pressing plate. The toggle mechanism is arranged between the toggle base and the lower pressing plate. The tie rod is parallel to the vertical direction, penetrates the lower pressing plate, and connects the upper pressing plate and the toggle seat. The number of tie rods is usually three. In addition, the number of tie rods is not particularly limited.

10‧‧‧Clamping device

12‧‧‧Fixed pressure plate

13‧‧‧Activating pressure plate

15‧‧‧Back pressure plate

16‧‧‧Tie rod

17‧‧‧Guide

20‧‧‧Toggle mechanism

20c‧‧‧Connecting rod

20a‧‧‧Crosshead

20b‧‧‧Connecting rod

21‧‧‧Clamping motor

25‧‧‧Heater

26‧‧‧Heat transfer limiter

27‧‧‧Temperature detector

28‧‧‧Axial force detector

30‧‧‧Mold device

32‧‧‧Fixed mold

33‧‧‧Activity Mode

70‧‧‧Operating device

80‧‧‧Display device

90‧‧‧Controller

91‧‧‧CPU

92‧‧‧Memory Media

Fr‧‧‧Frame

Claims (3)

An injection molding machine, comprising: a plurality of tie rods extending according to the clamping force; a heater for heating the tie rods; and a controller for controlling the heater, the controller adjusting the heating by the heater The temperature of the heating part of the tie rod is used to adjust the balance of the axial force of the plurality of tie rods, and the reference temperature of the heating part used in the adjustment of the balance is set to be higher than that of the heater when the heater is not heated. The stable temperature of the heating part is higher, and it has: a heat transfer limiter to limit the heat transfer from the heating part of the tie rod, and an axial force detector to detect the axial force of the aforementioned tie rod, and the aforementioned heat transfer limit The heater is used to manage the range of the heating part of the tie rod. The heater is arranged between the plurality of heat transfer limiters. The axial force detector is based on the heat transfer limiter and is arranged opposite to the heater One side. The injection molding machine described in the first item of the scope of patent application, wherein the adjustment range of the temperature of the heating part used in the adjustment of the balance is a temperature range higher than the stable temperature of the heating part. According to the injection molding machine described in item 1 or 2, wherein the reference temperature of the heating part used in the adjustment of the balance is set to a temperature higher than the temperature around the heating part by a predetermined value.

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