JP2990400B2 - Injection molding machine and control method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding machine and a control method therefor, and more particularly, to a toggle type clamping device for opening and closing and pressing a mold, wherein a mold is provided between a male mold and a female mold. The present invention relates to an injection molding machine capable of preventing a mold from being broken when foreign matter is sandwiched, and a control method thereof.

[0002]

2. Description of the Related Art In general, a toggle-type mold clamping device in an injection molding machine is configured by connecting a fixed plate and a pressure receiving plate with a tie bar to face each other, providing a movable plate between the fixed plate and the pressure receiving plate, and forming a link. Using a hydraulic cylinder to drive the toggle between the pressure receiving plate and the movable plate using a hydraulic cylinder, open / close and clamp the fixed die mounted on the front of the fixed plate and the movable die mounted on the movable plate facing the fixed die. Is what you do. In order to detect the mold clamping force, the strain is detected by measuring the amount of distortion of a tie bar connecting the fixed plate and the pressure receiving plate.

Further, a spring-type mold protection device is shown in FIG.
As shown in 6, insert the tie bar 3 into the fixed plate 1, fix the plate to the end of the tie bar 3, insert a spring between the fixed plate 1 and the plate, and detect the proximity of the fixed plate 1 and the plate. And a sensor LSb that detects the proximity of the fixed platen 1 and the movable platen 4, and detects an abnormality based on the order in which the sensor LSa and the sensor LSb operate.

[0004]

However, in the toggle-type mold clamping device using the above-described hydraulic cylinder, since the amount of distortion of the tie bar is very small, the error is large, and the accuracy of detecting the mold clamping force is improved. Was difficult. Further, in the toggle-type mold clamping device, since the mold clamping force after closing the mold rises steeply, it was difficult to control the low pressure in the initial stage of mold clamping. In addition, hydraulic cylinders are subject to oil leaks from piping and valves,
Maintenance of oil contamination is required, and the viscosity of hydraulic oil tends to change depending on the temperature and operating conditions.
The switching position of the driving speed and the stop accuracy varied.

Further, in the above-mentioned spring-type mold protector, when a foreign object is caught between the fixed mold and the movable mold, an abnormality is detected according to the order of operation of the two sensors. When the mold was combined with the mold clamping device, a considerable mold clamping force was already applied to the mold, and it was not possible to expect abnormality detection in the early stage of mold clamping. Furthermore, at least two or more sensors are required to detect an abnormality depending on the order of operation.

The present invention has been made in view of the above problem, and comprises a toggle-type mold clamping device capable of controlling a mold clamping force with high accuracy and detecting an abnormality in a mold at an early stage of mold clamping. An object of the present invention is to provide an injection molding machine and a control method thereof.

[0007]

In order to solve the above-mentioned problems, an injection molding machine according to a first aspect of the present invention is arranged such that a fixed plate and a pressure receiving plate are opposed to each other, and a tie bar is inserted and connected. A movable plate to be inserted into the tie bar is disposed between the tie bar and the pressure receiving plate, and the movable plate is connected to the pressure receiving plate via a toggle mechanism, and a plate is fixed to the fixed plate side end of the tie bar and the plate is separated from the fixed plate. And a sensor for detecting the proximity of the plate and the fixed plate is provided, a crosshead having a ball screw nut is connected to the toggle mechanism, a ball screw is screwed to the crosshead, and the ball screw is The position of the crosshead when the sensor detects that the plate and the fixed plate have come close to each other is rotatably connected to a motor having a position index detector, and the position of the cross head is detected by the motor. As a result, when the sensor detects that the plate and the fixed plate have come close to each other before reaching the origin, the mold clamping is stopped as there is a possibility of occurrence of an abnormality. It is characterized by operating.

According to another aspect of the present invention, there is provided a method for controlling an injection molding machine, wherein a fixed plate is inserted near one end of a tie bar and a pressure receiving plate is fixed near the other end. The movable plate is inserted between the fixed plate of the tie bar and the pressure receiving plate and connected to the pressure receiving plate via a toggle mechanism, and the plate is fixed to the fixed plate side end of the tie bar. The plate and the fixed plate are urged so as to be separated from each other, a sensor for detecting the proximity of the plate and the fixed plate is provided, and a crosshead having a ball screw nut is connected to the toggle mechanism. A method of controlling an injection molding machine in which a ball screw is screwed into a head, and the ball screw is rotatably connected to an electric motor having a position index detector, wherein the electric power is supplied when the toggle mechanism is extended. The temporary origin position of the machine is confirmed by the position index detector of the crosshead, and the pressure receiving plate is advanced by advancing the pressure receiving plate in a state where the toggle mechanism is extended, so that the pressure receiving plate corresponding to the mold is closed. Memorize the position,
The crosshead is retracted from the mold closed state to a position required for the mold clamping force, the pressure receiving plate is advanced again with the toggle mechanism contracted, the mold is closed, and the crosshead is advanced to start mold clamping. Then, it is detected by the sensor that the plate and the fixed plate have come close to each other against the bias due to the mold clamping, and the position of the crosshead at this time is reset as a final origin at the time of low-pressure mold clamping, and the origin is reset. If the sensor detects that the plate and the fixed plate have come close to each other before reaching, it is determined that there is a possibility of occurrence of an abnormality, and an operation is performed to stop the mold clamping.

[0009]

According to the first aspect of the present invention, the temporary origin position of the motor having the position index detector is confirmed in a state where the pressure receiving plate is retracted and the crosshead is advanced to extend the toggle mechanism. Next, dies are attached to the fixed plate and the movable plate, respectively, and the pressure receiving plate is advanced to close the die. The position of the crosshead is retracted to the position required for the mold clamping force of the mold, and the pressure receiving plate is advanced again with the toggle mechanism contracted to close the mold. The mold clamping force limit is set to the low pressure mold clamping value, and the crosshead is advanced to start mold clamping. The reaction force of the mold clamping in the toggle mechanism pulls the tie bar through the pressure receiving plate, the plate fixed to the end of the tie bar and the tie bar comes close to each other against the bias, and the sensor operates to stop the mold clamping. The position of the crosshead at this time is reset as the final origin at the time of low-pressure mold clamping. If the sensor is activated before reaching the set origin position, there is a gap between the crosshead position and the origin position, and there is an abnormality in the mold. . If there is no abnormality, the toggle mechanism is extended to perform pressure clamping.

According to the second aspect of the present invention, a temporary origin position of the electric motor when the toggle mechanism is extended is confirmed by a position index detector of the crosshead, and the pressure receiving state is determined in a state where the toggle mechanism is extended. The mold is closed by advancing the board. At this time, the position of the pressure receiving plate corresponding to the mold is stored. After that, the crosshead is retracted from this closed state to the position required for the mold clamping force, the pressure receiving plate is advanced again with the toggle mechanism contracted, the mold is closed, and the crosshead is advanced to close the mold. To start. Then, the sensor detects that the plate and the fixed plate have come close to each other against the bias due to the mold clamping, and resets the position of the crosshead at this time as the final origin at the time of low-pressure mold clamping. If the sensor detects that the plate and the fixed plate have come close to each other before reaching the origin, there is a deviation between the position of the crosshead and the origin, and it is determined that there is a possibility of occurrence of abnormalities and the mold clamping is performed. Operate to stop.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an injection molding machine according to the present invention will be described below with reference to FIGS. FIG. 1 is a front view of an injection molding machine. On a base 11, a general fixed plate 1 and a pressure receiving plate 2 facing the fixed plate 1 are mounted. The tie bar 3 is inserted. Fixed board
Movable platen 4 and plate 5 between 1 and pressure receiving plate 2 are tie bars
3, the plate 5 is located between the pressure receiving plate 2 and the movable plate 4, and supports one end of a ball screw 37 screwed to the pressure receiving plate 2 described later. The movable platen 4 and the pressure receiving platen 2 have a toggle mechanism.
6 are connected so as to retreat and approach freely.

The fixed platen 1 for mounting the fixed mold 7 has a substantially rectangular shape. A flange 13 is fixed to the right side of the base 11 by a bolt 12, and a hole 14 for inserting a nozzle is formed in the center of the flange 13. A tie bar 3 is inserted through the hole 15 near the corner. As shown in FIGS. 3 to 5, a plate 16 is located on the back surface of the fixed platen 1 along the upper and lower edges thereof. A threaded portion 17 is provided at the tip of the tie bar 3, and a nut 18 is fastened and fixed. Also, fixed platen 1 and plate
A compression spring 19 is interposed between the plates 16 to fix the plate 16
It is urged to separate from one. The biasing force of the compression spring 19 is set to such an elastic force that the fixed platen 1 and the plate 16 come into contact with each other between the time when the fixed mold 7 and the movable mold 8 are closed and the time when they are brought into close contact with each other. The compression spring of the plate
In order to regulate the range of movement by the urging of 19, a stopper bolt 20 having a large diameter head is penetrated through the plate 16 and fixed to a fixed platen. In addition, the tip thread of tie bar 3
A plate 21 is in contact with the end surface of the plate 17, and a bolt 22 is inserted into the corner of the plate 21 and fastened to the plate 16 to loosen the nut 18 screwed into the threaded portion 17 at the tip of the tie bar 3. Has been prevented.

On the left side of the base 11, a substantially square pressure receiving plate 2 opposing the fixed plate 1 is slidably mounted in a left-right direction in FIG. A through-hole 26 is provided near the corner of the pressure receiving plate 2, and the tie bar 3 is inserted through the hole 26 and connected to the fixed plate 1. As shown in FIG. 7, a nut 27 having a gear on the outer periphery is rotatably provided in each through-hole 26, and a threaded portion 28 is provided at an end of the tie bar 3 on the pressure receiving plate side. The tip screw portion 28 is screwed. In this embodiment, four geared nuts 27 are arranged as shown in FIG. 6, and at the center thereof, a timing gear 29 formed in an annular shape is rotatably provided on its inner periphery by a support roller 30. The gears are simultaneously meshed with the geared nuts 27 to synchronize the rotations of the geared nuts 27, and the rotation of the geared motor 31 is transmitted from the timing gear 29 to the geared nuts 27 via the gear 32 to be rotated.

In the center of the pressure receiving plate 2, a timing gear is provided.
A pulley 35 is provided concentrically with 29, and a shaft 36 of this pulley 35 is provided.
Is supported by the bearing of the pressure receiving plate 2, is mounted coaxially with the ball screw 37, and the rear end of the ball screw 37 is pivotally supported by the guide plate 5. A toothed belt 40 is wound around the pulley 35 of the ball screw 37 and the pulley 39 of the servomotor 38 with a rotary encoder, and the rotation of the servomotor 38 is transmitted to the ball screw 37 (see FIGS. 6 and 7). Pressure plate
On the front side of 2, a bracket 41 to which a link constituting the toggle mechanism 6 is connected is protruded. In order to memorize the position of the passive board 2 on the base 11 due to the difference in the mold thickness and to set the position of the passive board 2 when the mold is replaced, as shown in FIG. And pressure receiving plate 2 between potentiometer 42
Is mounted, and the position of the pressure receiving plate 2 moved by the geared motor 31 is detected.

The movable platen 4 on which the movable mold 8 is mounted has a substantially quadrangular shape, and the tie bar 3 is inserted through a through hole 45 provided at a corner thereof. On the back side of the movable platen 4, a bracket 46 to which a link constituting the toggle mechanism 6 is connected is protruded. The movable platen 4 moves in conjunction with the pressure receiving platen 2 by driving the geared motor 31 of the pressure receiving platen 2 and moves toward and away from the pressure receiving platen 2 by the toggle mechanism 6. In order to perform the movement without resistance, as shown in FIG.
Is provided.

As shown in FIGS. 7 to 9, the ball screw 37 is screwed with a cross head 53 having a ball screw nut 50 with a guide member 51 projecting left and right and a bracket 52 projecting up and down. Have been. As shown in FIG. 9, a pair of guide rods 54 is provided between the pressure receiving plate 2 and the movable plate 4 in parallel to the left and right of the ball screw 37, and a guide member 51 is inserted therethrough. A link constituting the toggle mechanism 6 is connected to the bracket 52.

The toggle mechanism 6 includes a bracket 41 of the pressure receiving plate 2.
Links 61 and 62 are connected to the bracket 46 of the movable platen 4 via a connecting portion 60, and the connecting portion 60 of these links and the bracket 52 of the crosshead 53 are connected by a link 63. I have. Note that the support plate 5 is provided between the pressure receiving plate 2 and the movable plate 4, but the outer end of the support plate 5 is in the case of the present embodiment so as not to interfere with the extension and bending operations of the toggle mechanism 6. The tie bar 3 is formed in a rectangular shape and is inserted through the tie bar 3 facing diagonally (see FIG. 8).

The ball screw is driven by the drive of the servo motor 38.
37 rotates and the crosshead screwed into this ball screw
53 extends and bends the connected toggle mechanism 6 forward and backward. Limit switches LS1 and LS2 are provided on the front surface of the pressure receiving plate 2 and the back surface of the support plate 5, respectively, in order to detect the forward limit and the backward limit of the crosshead 53. Also, in order to detect that the tie bar 3 was pulled through the pressure receiving plate 2 and the plate 16 was in contact with the fixed plate 1 during a period from when the toggle mechanism 6 was extended and the mold closing was completed and pressure clamping was started. , A single limit switch LS3.

Next, a control method of the injection molding machine of the present invention will be described.
The operation sequence and operation when the injection molding machine configured as described above is used will be described with reference to FIGS. Before starting the injection molding, the pressure receiving plate 2 is retracted (to the left in the figure) and the crosshead 53 is advanced (to the right in the diagram) to check the state of the toggle mechanism 6 extended by the limit switch LS2. Then, a temporary origin position for retreating to the set position of the crosshead 53 necessary for the pressure tightening is confirmed by the rotary encoder of the servo motor 38 (see FIG. 10). In order to maintain the temporary origin position, the servo motor 38 is set in the servo lock state.

Next, the fixed platen 1 and the movable platen 4 are each provided with a fixed mold 7.
And the movable mold 8 are temporarily fixed, and the geared motor 31 is driven to advance the pressure receiving plate 2 to close the mold and fix the mold. The completion of mold closing is confirmed by the overload of the geared motor 31, and the pressure
Is stopped (see FIG. 11). Pressure plate 2 at this time
Is stopped by the potentiometer 42, and the position of the pressure receiving plate corresponding to the mold attached when the mold is replaced is stored.

The servo motor 38 is driven from the temporary origin position to rotate the ball screw 37, and the position of the crosshead 53 is retracted to a position required for the mold clamping force.
In the servo lock state (see FIG. 12). Then, the pressure receiving plate 2 is advanced by the drive of the geared motor 31, and the mold is closed (see FIG. 13). The completion of the mold closing is confirmed by the overload of the geared motor 31, and the brake is actuated so that the pressure receiving plate 2 stops moving forward and the pressure receiving plate does not move.

The servo motor 38 is driven by setting the torque limit value of the servo motor 38 to the value of the low pressure mold clamping. Toggle mechanism
The reaction force due to the mold clamping of 6 is the tie bar with the plate 16 fixed
3 is pulled to the left, the compression spring 19 is compressed, and the back of the fixed platen 1 comes in contact with the plate 16 to operate the limit switch LS3 (see FIG. 14). The position of the crosshead 53 at this time is detected by the rotary encoder of the servo motor 38, and this position is reset as the final origin position of the mold closing. If the limit switch LS3 is activated before the crosshead moves to the specified position and reaches the set mold clamping force, there is a possibility that an abnormality has occurred in the mold. You need to check the type. If there is no abnormality, change the torque limit value of the servo motor 38 to the value required for pressure clamping,
Drive and extend the toggle mechanism 6 to perform pressure clamping. Completion of the compression is confirmed by the limit switch LS2 (FIG. 15).
reference).

[0023]

Since the present invention is configured as described above, the following effects can be obtained.

According to the first aspect of the present invention, the mold clamping force is detected from the position of the crosshead with respect to the ball screw by the position index detector of the electric motor regardless of the amount of distortion of the tie bar. Since the origin of the crosshead for mold clamping is set in a state where a low-pressure mold clamping force is applied to the mold, it is possible to provide an injection molding machine capable of accurately controlling the mold clamping force. In addition, before performing injection molding, the origin of the mold clamping force is set using a single sensor, and when a single sensor detects that the plate and the fixed plate have come close to each other by performing mold clamping, position determination is performed. If the position of the crosshead detected by the detector is shifted from the origin position, it is assumed that an abnormal condition has occurred in which foreign matter has caught in the mold. Can be. Therefore, it is possible to provide an injection molding machine capable of preventing the mold from being damaged before a high pressure is applied to the mold. Furthermore, since a motor having a position index detector is used for driving the toggle-type mold clamping device, maintenance is easy, power consumption is low, and noise is low as compared with a hydraulic cylinder. Further, the drive by the electric motor has good controllability in a low speed range, and an injection molding machine excellent in repetitive control can be provided.

According to the second aspect of the present invention, the detection of the mold clamping force is detected based on the position of the crosshead with respect to the ball screw detected by the position index detector of the electric motor. Since the origin of the crosshead for mold clamping is set in a state where a low-pressure mold clamping force is applied to the fin, a method of controlling an injection molding machine that can accurately control the mold clamping force can be provided. When a single sensor detects that the plate and the fixed plate have approached each other before reaching the origin at the time of low-pressure mold clamping, the position of the crosshead detected by the position index detector and the set origin position are adjusted. Since the gap has occurred and an operation is performed to stop the mold clamping as a possibility of occurrence of an abnormality, the abnormal state can be detected at an early stage of the mold clamping. Therefore, it is possible to provide a control method for an injection molding machine that can prevent the mold from being damaged before high pressure is applied to the mold.

[0026]

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of an injection molding machine according to the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a side view of a fixed board.

FIG. 4 is a front view of FIG. 3;

FIG. 5 is a cross-sectional plan view of FIG.

FIG. 6 is a left side view of FIG. 1;

FIG. 7 is a partial sectional view of a pressure receiving plate and a crosshead.

FIG. 8 is a cross-sectional view showing a relationship between a link mechanism and a crosshead, and a support plate and a movable plate.

FIG. 9 is a partial cross-sectional plan view showing a guide rod provided between a pressure receiving plate and a support plate in parallel with a ball screw.

FIG. 10 is a schematic diagram showing a state for confirming a temporary origin position of the servomotor.

FIG. 11 is a schematic diagram showing a state in which a mold is attached and the pressure receiving plate is advanced to close the mold.

FIG. 12 is a schematic diagram showing a state in which the crosshead is retracted to a set position required for mold clamping.

FIG. 13 is a schematic view showing a state where the pressure receiving plate is advanced again to close the mold.

FIG. 14 is a schematic view showing a state in which the crosshead is advanced to perform mold clamping.

FIG. 15 is a schematic view showing a state in which the crosshead is further advanced to perform pressure clamping.

FIG. 16 is a sectional view showing a mold protection device of a conventional injection molding machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed board 2 Pressure receiving board 3 Tie bar 4 Movable board 5 Support plate 6 Toggle mechanism 16 Plate 19 Compression spring 27 Nut with gear 28 Screw part 29 Timing gear 37 Ball screw 38 Servomotor with rotary encoder 50 Ball screw nut 53 Cross head LS3 Limit switch

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-279353 (JP, A) JP-A-4-86208 (JP, A) JP-A-60-115418 (JP, A) JP-A-4- 298317 (JP, A) JP-A-5-293386 (JP, A) JP-A-63-126659 (JP, A) JP-B-48-36410 (JP, B1) JP-B-40-27429 (JP, Y1) (58) Field surveyed (Int. Cl. ⁶ , DB name) B29C 45/64-45/84 B22D 17/26

Claims (2)

(57) [Claims] 1. A fixed plate and a pressure receiving plate facing each other, a tie bar being inserted and connected, a movable plate inserted through the tie bar being disposed between the fixed plate and the pressure receiving plate, and connected to the pressure receiving plate via a toggle mechanism. A plate is fixed to an end portion of the tie bar on the fixed platen side, a plate is urged to separate the plate from the fixed platen, and a sensor for detecting the proximity of the plate and the fixed platen is provided. A crosshead having a screw nut is connected, a ball screw is screwed into the crosshead, the ball screw is rotatably connected to an electric motor having a position index detector, and the plate and the fixed plate are closed by mold clamping.
The crosshead when the sensor detects proximity
The position of the motor is detected by the position index detector of the motor.
Out and set it as the final origin for low-pressure mold clamping.
The sensor detects that the plate and fixed plate have come close to each other
If this occurs, the mold clamping is stopped
An injection molding machine characterized in that it is operated so as to make it work. 2. A fixed plate is inserted near one end of the tie bar.
And the pressure receiving plate is inserted near the other end so that it faces the fixed plate.
The movable plate is inserted between the fixed plate of the tie bar and the pressure receiving plate.
And connected to the pressure receiving plate via a toggle mechanism,
The plate is fixed to the fixed plate end of the tie bar and
The plate and the fixed plate are urged to separate from each other, and the plate is
A sensor for detecting the rate and the proximity of the fixed plate is provided.
And a cross having a ball screw nut on the toggle mechanism.
The head is connected and a ball screw is screwed into the crosshead.
The ball screw has a position index detector.
Control method for an injection molding machine rotatably connected to a
hand, A temporary master of the electric motor when the toggle mechanism is extended.
The point position is determined by the cross head position index detector.
Confirmed, With the toggle mechanism extended, the pressure plate is advanced.
To close the mold,
Memorize the position, From the closed state of the mold to the position required for the mold clamping force,
Retreat With the toggle mechanism retracted, advance the pressure plate again
Close the mold, Move the crosshead forward to start mold clamping, and
The fact that the plate and the fixed plate approached against
Detected by the sensor and the crosshead Location
Is reset as the final origin at the time of low pressure mold clamping, The plate and the fixed plate approach each other before reaching the origin
Abnormality may occur if the sensor detects
It is characterized by operating to stop mold clamping as
Control method of injection molding machine.