JP2000334795A - Injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a molding material from leaking from the joining face of both molds. SOLUTION: An encoder for measuring a distance from the top face of a base 11 to the joining face of both molds 14 and 24 when both molds 14 and 24 are joined is provided. Driving data setting a relation between the distance measured by this encoder and amt. of driving of a motor 22 necessary from joining of the molds to completion of mold clamping are stored in an RAM. In addition, the amt. of driving of the motor is controlled by a CPU based on these driving data. As the result, even if heat of both molds 14 and 24 is transmitted to a guide bar 12 and length of the guide bar 12 is changed by the effect of the heat, there exists no possibility of that pressure of the movable mold 24 is weakened when locking is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an injection molding machine.

[0002]

2. Description of the Related Art Conventionally, an injection molding machine for molding a synthetic resin product is composed of a fixed die and a movable die which is provided so as to be able to approach and separate from the fixed die. The fixed type is supported by the tip of the guide bar. On the other hand, the movable mold is supported on a guide bar, and moves along the axial direction of the guide bar by driving a motor. The filling of the synthetic resin into the cavity formed by both molds is performed as follows.

First, a movable die is moved by rotating a motor, and the movable die is joined to a fixed die. Thereafter, the motor is further rotated to press the movable mold against the fixed mold to clamp the mold. After completion of the mold clamping, the cavity is filled with the molten synthetic resin through the gate. After the filled synthetic resin is cooled and hardened, the movable mold is moved in a direction away from the fixed mold to take out the synthetic resin product.

[0004]

However, in order to prevent the synthetic resin filled in the cavity from cooling and solidifying, it is necessary to heat both molds with a heater.
Therefore, when the injection molding machine is used for a long time, the heat of the mold is transmitted to the guide bar, and the guide bar expands under the influence of the heat. Then, with such a change in the length of the guide bar, the position of the fixed die shifts in the direction away from the movable die. Therefore, when the mold is clamped, there is a problem that the pressing force of the movable mold against the fixed mold is weakened, and the synthetic resin leaks from the gap between the joining surfaces of both molds.

[0005] In order to solve such a problem, there is a type provided with a pressure sensor for detecting a pressing force of a movable type against a fixed type. According to this configuration, based on the pressure detection signal output from the pressure sensor, the drive of the motor is controlled by the control unit from the time when the mold is joined to the time when the mold clamping is completed. However, in this method, it takes time not only to transmit the pressure detection signal from the pressure sensor to the control means, but also to take a long time for the arithmetic processing by the control means. Therefore, there is a problem that the pressing force of the movable mold against the fixed mold is not constant, and the mold clamping is not stable. Therefore, it was not possible to prevent the synthetic resin from leaking from the joint surface between the two molds.

Further, in addition to the conventional technology using the pressure sensor, there is a conventional technology in which setting data in which the relationship between the heating time of the heater and the moving amount of the movable mold is set is stored in the control means in advance. According to this configuration, the moving amount of the movable mold from the start of heating of the heater to the point in time when a predetermined time has elapsed is:
It is read from the setting data by the control means. However, this data sets the moving amount of the movable type based only on the lapse of time. Therefore, it is not possible to cope with a change in the amount of extension of the guide bar due to a rise in the outside air temperature of the injection molding machine or a difference in temperature when the power of the injection molding machine is turned on. Therefore, even in this case,
It was not possible to prevent the synthetic resin from leaking from the joint surface of both types.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an injection molding machine capable of preventing a molding material from leaking from a joining surface of both dies.

[0008]

According to the first aspect of the present invention, a pair of dies and at least one of the two dies are moved to open and close the dies. An injection molding machine comprising a driving unit, and after pressing the mold by the driving unit to join the two molds together, further presses the molds to clamp the molds together.
Measuring means for measuring the distance from the joint surface of the two molds to a predetermined reference position at the time of joining the two molds, the distance measured by the measuring means, and from the time of mold joining to the time of completion of mold clamping. And a control means for controlling the drive amount of the drive means based on the drive data.

According to a second aspect of the present invention, in the injection molding machine according to the first aspect, the driving means includes a motor, and the control means calculates a rotation angle of the motor based on the driving data. The main point is.

According to a third aspect of the present invention, in the injection molding machine according to the first or second aspect, a plurality of types of the drive data are provided according to a temperature condition around the mold. .

Hereinafter, the "action" of the present invention will be described. According to the invention described in claim 1, the distance from the joining surface of the two dies to the predetermined reference position at the time of joining the dies,
It is measured by the measuring means. Based on the measured distance, the driving amount of the driving unit is calculated based on the driving data. Then, at the time of mold clamping, the drive unit is drive-controlled by the control unit based on the calculation result of the drive amount.
Therefore, the pressing force between the two molds does not decrease, and it is possible to prevent the molding material from leaking from the joint surface between the two molds.

According to the second aspect of the present invention, the rotation angle of the motor is calculated by the control means. Therefore, it is possible to control the pressing force between the dies at the completion of the mold clamping with high accuracy.

According to the third aspect of the present invention, a plurality of types of drive data are provided according to the temperature around the mold. Therefore, the control unit controls the driving unit based on the optimum driving data according to the temperature condition. Therefore, it is possible to control the pressing force between the dies at the completion of the mold clamping with higher accuracy.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. As shown in FIG. 1, a guide bar 12 as a guide member extending vertically is provided on the upper surface of the base 11, and a support member 13 is fixed to an upper end of the guide bar 12. .
A fixed die 14 is provided on a lower surface of the fixed support member 13.

Each of the guide bars 12 is provided with an extendable toggle mechanism 15. Each toggle mechanism 15 includes a pair of links 16 and 17. The lower link 17 is rotatably connected to a fixed support shaft 18 provided at the lower end of the guide bar 12. Upper link 16
Is rotatably connected to a movable support shaft 19 movable along the guide bar 12. The upper and lower link members 16 and 17 are connected to each other via a permanent support shaft 20 so as to be relatively rotatable.

Each of the movable support shafts 19 has a movable support member 23.
A movable mold 24 facing the fixed mold 14 is provided on the upper surface of the movable support member 23. The molds 14 and 24 are provided with heaters 14a and 24a, respectively. Each of the molds 14,
When the mold 24 is heated, the cavity formed at the time of joining the two dies 14 and 24 is smoothly filled with the molten synthetic resin.

The toggle mechanism 15 is provided with a servo motor 22 as a driving means. This motor 22
A mechanism (not shown) for converting the rotational motion of the motor 22 into a linear motion is provided between the motor and the toggle mechanism 15. When the motor 22 rotates in the forward direction, the toggle mechanism 15 extends, and the movable mold 24 approaches the fixed mold 14. When the motor 22 rotates in the reverse direction, the toggle mechanism 15
Is contracted, and the movable mold 24 is separated from the fixed mold 14.

As shown in FIG. 2, when the two dies 14 and 24 are joined, a pressing force is applied to the fixed die 14 by the movable die 24. The pressing force at this time is set to such a size that the guide bar 12 hardly extends along the axial direction. Also, as shown in FIG.
When the mold clamping of No. 4 is completed, the pressing force of the movable mold 24 against the fixed mold 14 is set to a magnitude such that the guide bar 12 extends a predetermined amount along the axial direction. Therefore, when the tightening of both dies 14 and 24 is completed, the base 11
A distance L2 (see FIG. 3) from the upper surface of the two molds 14 and 24 to the joining surface is longer than a distance L1 (see FIG. 2) when the two molds 14 and 24 are joined. When the mold clamping is completed, the guide bar 12 extends, so that the pressing force (clamping force) of the movable mold 24 required for mold clamping can be obtained. Therefore, the fixed mold 1 is
The pressing force applied to the mold 4 is larger when the mold clamping is completed than when the molds 14 and 24 are joined.

Next, the electrical configuration of the injection molding machine configured as described above will be described. As shown in FIG. 4, a central processing unit (CPU) 30 controls the operation of each part of the injection molding machine. The read only memory (ROM) 31 stores various control programs necessary for the operation of the injection molding machine. The random access memory (RAM) 32 temporarily stores data and the like obtained with the execution of the control program. The CPU 30, the ROM 31, and the RAM 32 constitute control means.

An encoder 35 as a measuring means detects the rotation angle of the motor 22 and outputs the detection signal to the CP.
Output to U30. By this detection, the distance L1 from the upper surface (predetermined reference position) of the base 11 at the time of joining the dies 14 and 24 to the joining surface of the dies 14 and 24 is measured. Further, the torque sensor 36 detects the torque of the motor 22 and outputs a detection signal to the CPU 30. The motor 22 is rotated by a drive signal from the CPU 30 via a drive circuit (not shown). Further, the temperature sensor 37
The outside air temperature around the two molds 14 and 24 is detected, and the detection signal is output to the CPU 30.

The RAM 32 stores drive data (drive map) 38 shown in FIG. On the vertical axis of the drive data 38, the distance L1 to the joint surface of the two dies 14, 24 measured by the encoder 35 is set. On the other hand, the horizontal axis of the driving data 38 indicates both types 1
The required amount of rotation of the motor 22 is set from the time of joining the 4, 24 to the time of completing the mold clamping. And the CPU 30
When a detection signal of the rotation angle of the motor 22 is input from the encoder 35, the rotation angle of the motor 22 from the time of mold joining to the time of completion of mold clamping is determined according to the rotation angle.

In the drive data 38, a plurality of types of pressing forces of the movable mold 24 at the time of completion of mold clamping are set as data. This is because the value of the pressing force required at the time of completion of mold clamping differs depending on the type of the product to be molded. In the present embodiment, the pressing force of the movable mold 24 at the time of completion of the mold clamping is set in the range of 10 to 40 t and at intervals of 10 t. Incidentally, the driving data 38 is shown in FIG.
This is derived based on the data shown in (b).
FIG. 6A is data showing the relationship between the pressing force of the movable mold 24 on the fixed mold 14 and the rotation angle of the motor 22 when the molds 14 and 24 are tightened. FIG. 6 (b)
From the upper surface of the base 11 when the mold clamping is completed,
4 is data showing the relationship with the distance L2 to the bonding surface.

FIG. 5 shows only the drive data 38 when the outside air temperature around the two dies 14 and 24 is 20 ° C. Actually, a plurality of types of drive data 38 are stored in the RAM 32 according to the outside air temperature around the dies 14 and 24. Then, the CPU 30 includes a temperature sensor 37
Based on the detection signal output from, an optimum one is selected from a plurality of types of drive data.

Next, the operation of the injection molding machine configured as described above will be described. This operation is performed in the ROM 3
CPU based on the control program stored in
It proceeds under the control of 30.

When the motor 22 is rotated in the forward direction with the two dies 14, 24 separated from each other, the toggle mechanism 15 extends upward, and the movable die 24 rises by a predetermined amount. When the movable mold 24 is joined to the fixed mold 14, the movable mold 24 hardly rises by the fixed mold 14. Therefore, it becomes a load and the torque of the motor 22 increases. When the torque sensor 36 detects that the torque of the motor 22 exceeds the threshold, the driving of the motor 22 is stopped. As a result, the two dies 14, 24 are held in a joined state.

In this state, one optimal drive data 38 is selected from a plurality of types of drive data 38 based on the detection signal of the temperature sensor 37. At the same time, the rotation angle of the motor 22 is detected by the encoder 35, and the distance L from the base 11 to the joint surface of the two dies 14, 24 is detected.
Measure 1. Then, based on the drive data 38, the remaining rotation angle of the motor 22 required from the time of joining the two dies 14, 24 to the time of completing the mold clamping is determined. For example, as shown in FIG. 5, when the pressing force of the movable mold 24 at the time of the completion of the mold clamping is to be set to 40 t and the distance L1 indicates the value of a, the rotation angle of the motor 22 corresponding to the distance L1 is This indicates the value of b.

Thereafter, the motor 22 is rotated by the remaining rotation angle calculated based on the drive data 38. As a result, the toggle mechanism 15 further extends as compared with the state in which the two dies 14 and 24 are joined. By this extension, each guide bar 12 is extended by a predetermined amount, and the pressing force of the movable mold 24 is reduced to a predetermined value (4
0t). After completion of the mold clamping, the molten synthetic resin is filled into the cavity through a gate.
After cooling and hardening the filled synthetic resin, the motor 22 is driven in the reverse direction to separate the movable mold 24 from the fixed mold 14 and take out the synthetic resin product.

Therefore, according to the present embodiment, the following effects can be obtained. (1) An encoder 35 is provided for measuring the distance L1 from the upper surface of the base 11 to the joint surface of the dies 14 and 24 when the dies 14 and 24 are joined. Drive data 38 is stored in the RAM 32 in which a relationship between the distance L1 measured by the encoder 35 and the drive amount of the motor 22 required from the time of mold joining to the time of completion of mold clamping is set.
The drive amount of the motor 22 is controlled by the CPU 30 based on the drive data 38.
Therefore, even if the heat of the two dies 14 and 24 is transmitted to the guide bar 12 and the length of the guide bar 12 changes under the influence of the heat, the pressing force of the movable die 24 is not weakened when the mold clamping is completed. Absent. Therefore, both dies 14, 24 are formed through the molding process.
The two can be securely joined together in a pressurized state, that is, the mold can be securely clamped. As a result, both types 14,
It is possible to reliably prevent the synthetic resin from leaking from the bonding surface of the bonding member 24.

(2) The drive amount of the motor 22 is controlled based on the drive data 38 stored in the RAM 32 in advance. Therefore, unlike the case where the pressing force of the movable mold 24 against the fixed mold 14 is detected in real time by the pressure sensor, the calculation processing does not take much time. Moreover, fixed type 1
There is no variation in the pressing force of the movable mold 24 against the movable mold 4.

(3) The distance L1 from the base 11 to the joint surface of the dies 14 and 24 when the dies 14 and 24 are joined.
Are parameters for determining the drive amount of the motor 22. Therefore, unlike the case where the moving amount of the movable mold 24 is determined based only on the lapse of time as in the related art, the two dies 14, 14 when the power of the injection molding machine is turned on.
The pressing force of the movable mold 24 can be optimized when the mold clamping is completed irrespective of the difference in the temperature around the mold 24.

(4) The rotation angle of the motor 22 is controlled by the CPU 30 to complete the mold clamping after the mold joining. Therefore, it is possible to control the pressing force of the movable mold 24 at the time of completion of the mold clamping with high accuracy.

(5) Both types 14, 24 are stored in the RAM 32.
A plurality of types of drive data 38 corresponding to the surrounding temperature conditions are stored. Therefore, control can be performed using the optimal drive data 38 selected by the CPU 30. Therefore, the pressing force between the dies at the time of the completion of the mold clamping can be controlled with higher accuracy.

The embodiment of the present invention may be modified as follows. In the above-described embodiment, the present invention is embodied in an injection molding machine of a type in which the movable mold 24 is moved in the vertical direction. In addition, it is also possible to embody the injection molding machine of the type in which the movable mold 24 moves in the horizontal direction.

In the above embodiment, the toggle mechanism 15 is used to press the movable mold 24 against the fixed mold 14. In addition, the toggle mechanism 15 may be omitted, or may be changed to another mechanism instead of the toggle mechanism 15.

In the above embodiment, the motor 22 is used to move the movable mold 24. Other than this, for example, a fluid cylinder such as a hydraulic cylinder or an electric cylinder may be used.

In the above embodiment, the distance L 1 between the base 11 and the joining surfaces of the two dies 14 and 24 at the time of joining was measured by the encoder 35. In addition, base 1
The distance from 1 to the fixed mold 14 may be measured. In this case, the drive data 38 is set based on the relationship between the distance from the base 11 to the fixed mold 14 and the rotation angle from the time of mold joining to the time of completion of mold clamping.

In the above-described embodiment, a plurality of types of drive data 38 are stored in the RAM 32 according to the outside air temperature around the dies 14 and 24. In addition, both types 1
The drive data 38 corresponding to the temperature of the guide bar 12 in the vicinity of the two dies 14 and 24 or the temperature of the guide bar 12 near the two dies 14 and 24
M32 may be stored. In this case, the temperature sensor 37 can measure the temperature of at least one of the dies 14 and 24 or the temperature of the guide bar 12 near the dies 14 and 24.

Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments will be listed below together with their effects. (1) The injection molding machine according to claim 2 or 3, wherein the position detection unit is an encoder that detects a rotation angle of the motor. According to this configuration, the rotation angle of the motor can be detected with high accuracy despite the simple configuration.

(2) In any one of claims 2, 3 and (1), the two dies are constituted by a fixed mold and a movable mold which can be moved toward and away from the fixed mold. An injection molding machine in which the driving means includes a motor and a toggle mechanism. According to this configuration, even if the driving force of the driving unit is small, the pressing force of the movable mold on the fixed mold can be increased.

(3) The guide member is provided with a fixed die, and the guide member is provided with a movable die that can be moved toward and away from the fixed die, and a toggle mechanism for moving the movable die toward and away from the fixed die is provided. A motor for operating the toggle mechanism is provided, and after pressing the molds based on the operation of the toggle mechanism by the rotational force of the motor to join the two molds together, further pressing force is applied to the two molds. In an injection molding machine for clamping the mold, measuring means for measuring the distance from the fixed mold to a predetermined reference position at the time of joining the two molds,
It has drive data that sets the relationship between the distance measured by the measurement means and the amount of drive of the drive means required from the time of mold joining to the time of completion of mold clamping, and based on the drive data, the drive means An injection molding machine comprising: a control unit for controlling a driving amount of the motor.

(4) A pair of dies, and a driving means for opening and closing the dies by moving at least one of the dies, and pressing the dies by the driving means to form the two dies. After joining the two molds, in a mold clamping method in an injection molding machine in which the two molds are further clamped by pressing each other, a predetermined surface is joined from the joint surface of the two molds at the time of joining the two molds. A drive that measures a distance to a reference position by a measuring unit and then sets a relationship between the distance measured by the measuring unit and a driving amount of the driving unit required from the time of mold joining to the time of completion of mold clamping. A mold clamping method in an injection molding machine, wherein a driving amount of a driving unit is calculated based on the distance measured by the measuring unit using data, and the driving amount of the driving unit is controlled based on the calculation result. .

[0042]

As described above in detail, according to the first aspect of the present invention, it is possible to prevent the molding material from leaking from the joint surface between the two dies.

According to the second aspect of the present invention, it is possible to control the pressing force between the dies at the completion of the mold clamping with high accuracy. According to the third aspect of the present invention, since the driving unit can be controlled based on the optimum driving data according to the temperature condition, the pressing force between the dies at the time of the completion of the mold clamping can be controlled with higher accuracy. can do.

[Brief description of the drawings]

FIG. 1 is a front view of an injection molding machine in a mold open state, showing the embodiment.

FIG. 2 is a front view of the injection molding machine in a mold bonding state.

FIG. 3 is a front view of the injection molding machine in a mold clamping state.

FIG. 4 is a block diagram showing an electrical configuration of the injection molding machine.

FIG. 5 is a diagram showing driving data.

FIGS. 6A and 6B are data for deriving drive data.

[Explanation of symbols]

14: fixed type (die), 22: motor (drive means), 2
4 movable type (die), 30 CPU (control means), 31
... ROM (control means), 32 ... RAM (control means), 3
5: encoder (measuring means), 38: drive data 38,
L1 ... distance.

Claims (3)

[Claims] 1. A vehicle comprising: a pair of molds; and driving means for moving at least one of the molds to open and close the molds.
After joining the two molds by pressing the mold by the driving means, the injection molding machine is further pressed to clamp the molds together. Measuring means for measuring a distance from a joining surface of the two dies to a predetermined reference position; and the distance measured by the measuring means, and driving of the driving means necessary from the time of mold joining to the time of completion of mold clamping. An injection molding machine comprising: drive data having a relationship with an amount, and control means for controlling a drive amount of the drive means based on the drive data. 2. The injection molding machine according to claim 1, wherein the driving unit includes a motor, and the control unit calculates a rotation angle of the motor based on the driving data. 3. The drive data is provided in a plurality of types according to a temperature condition around the mold.
3. The injection molding machine according to claim 1.