JPH0356653B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) The present invention relates to an injection molding machine, and particularly to an injection molding machine in which a movable platen of a mold clamping device and an injection screw of an injection device are driven by a single servo motor. It's about machines.

(Background Art) Conventionally, in the mold clamping device of an injection molding machine, a hydraulic cylinder is used as a drive means for a movable platen, and by moving the movable platen with this hydraulic cylinder, the gap between the movable platen and the fixed platen is It used to be common for mold clamping operations to be carried out using a servo motor, but in recent years, the movable platen Proposals have been made in which the plate is moved relative to a fixed plate.

By the way, in a mold clamping device that uses such a servo motor as a driving means for a movable platen, as with the hydraulic cylinder type, it is necessary to shorten the molding cycle as much as possible while protecting the mold, etc. Therefore, it is necessary to control the moving speed of the movable platen according to its position relative to the fixed platen. Therefore, conventionally, a limit switch detects when the movable plate has moved to a predetermined position, and based on the detection result, the reference rotation speed of the servo motor is switched and controlled. The rotational speed of the servo motor is controlled based on output signals from the servomotor so that the actual rotational speed matches the reference rotational speed. The moving speed of the movable platen was controlled by detecting the moving position of the movable platen using a limit switch and controlling the rotational speed of the servo motor based on the position information.

However, with such conventional mold clamping devices, when it becomes necessary to change the movement control speed of the movable platen due to changes in the mold, etc., the mounting position of the limit switch must be changed each time. There was a problem that the change operation was troublesome and time consuming. Furthermore, the accuracy of the mounting position is not necessarily high, and the relationship between the moving speed and the moving position of the movable platen, as well as the stop position of the movable platen, tend to vary. Furthermore, in order to shorten the injection molding cycle, that is, the mold opening/closing time, it is necessary to precisely control the moving speed of the movable platen, but with conventional mold clamping devices, the moving speed of the movable platen The more detailed the control, the more limit switches needed to be installed.

Therefore, in recent years, with the aim of eliminating such problems, a rotary encoder has been installed in the servo motor that drives the movable platen of the mold clamping device, and the pulses output from the rotary encoder are reversibly counted to move the movable platen. It has been proposed to detect the position and to switch and control the moving speed of the movable platen in relation to the detected moving position of the movable platen.

(Problem to be solved) However, in injection molding machines that adopt this method to control the movement of the movable platen, there is a risk that the counting contents of the reversible counting means may be disturbed by external noise. The cumulative counting error of the reversible counting means may cause trouble in the injection molding operation.

In particular, by rotating ball screw mechanisms provided in the mold clamping device and the injection device through a plurality of clutches by one servo motor, the mold opening/closing operation of the mold by the mold clamping device and In an injection molding machine in which the injection operation or screw rotation operation of the injection screw in the injection device is selectively performed, when output pulses from the rotary encoder are reversibly counted, the injection operation or screw rotation operation of the injection cylinder in the injection device is The output pulses during rotation were also counted, which affected the moving distance of the movable plate, and it was thought that practical control would be difficult.

(Solution Means) Here, the present invention was made against the background of the above-mentioned circumstances, and its gist is that, as described above, a single servo motor is used to drive a motor through a plurality of clutches. By rotating the respective ball screw mechanisms provided in the mold clamping device and the injection device, the mold opening/closing operation of the mold by the mold clamping device and the injection operation or screw rotation operation of the injection screw in the injection device can be selectively performed. (a) a current value register that reversibly counts and stores output pulses from a rotary encoder provided on the servo motor according to the rotational direction of the servo motor; (b) a reset means for resetting the current value register each time the mold clamping device starts opening the mold; and (c) a movable platen that is moved relative to the fixed platen by the mold clamping device. movable platen movement stroke setting means for setting a movement stroke; and (d) comparing the count value of the current value register with the movement stroke value set by the movable platen movement stroke setting means, and determining the fixation of the movable platen. a moving distance calculating means for calculating a moving distance with respect to the plate with the mold clamping position of the mold as the origin; By controlling the moving distance of the disk, the influence of the output pulse of the rotary encoder stored in the current value register is eliminated during the injection operation and screw rotation operation of the injection screw in the injection device.

(Operation/Effect) As described above, according to the present invention, the moving distance calculating means is provided with a reset means, and the output pulses of the rotary encoder provided in the servo motor are counted and stored, and the moving position of the movable platen is calculated. Since the current value register, which is represented by a count value, is reset each time the mold opening operation starts, the rotary value stored in the current value register is reset during the injection operation or screw rotation operation of the injection screw in the injection device. The influence of the encoder's output pulses is completely eliminated, and even if the current value register malfunctions due to external noise, the counting error caused by that external noise will be eliminated. Accumulation is better avoided, and therefore, it is also better avoided that such accumulated errors cause serious problems in the operation of the injection molding machine. Moreover, for the same reason, during the period from the closing of the mold to the opening of the mold, that is, while the injection device of the injection molding machine is operating, even if external noise Therefore, there is an advantage that even if the current value register malfunctions, it will not cause any substantial trouble to the injection molding operation.

(Example) Hereinafter, in order to clarify the present invention more specifically, one example thereof will be described in detail based on the drawings.

First, FIG. 1 is a diagram showing an injection molding machine which is an embodiment of the present invention. As shown therein, in this injection molding machine, a mold clamping device 10 and an injection device 12 are connected. , are driven by one common servo motor 14.

Here, the servo motor 14 has a rotating shaft 16 connected to a rotating input shaft 20 of the mold clamping device 10 via a clutch 18, and a gear 22 provided on the rotating shaft 16. , is meshed with a gear 26 provided on the rotational input shaft 24 of the injection device 12 via a gear 28, and the rotational power is transmitted to the rotational input shaft 20 of the mold clamping device 10 and the rotational input shaft 24 of the injection device 12. It is designed to be able to be transmitted to any of the following.

The rotation input shaft 20 on the side of the mold clamping device 10 is meshed with a gear 32 at a gear 30 provided on the shaft, and is meshed with a gear 36 via this gear 32. Also, this gear 36
is integrally provided in the nut member 34 of the ball screw mechanism which is the movable platen feeding mechanism of the mold clamping device 10.

Thereby, the rotational power from the servo motor 14 transmitted to the rotation input shaft 20 is transmitted to the nut member 34.

Further, this nut member 34 is rotatably supported by the base board 3 whose position is fixed, and is screwed together with a ball screw 42 fixed to a movable board 40 with a predetermined ball screw structure, so that the nut member 34 is rotated. Accordingly, the ball screw 42 and eventually the movable platen 4
0 is relatively moved in the direction of its axis. As a result, the movable platen 40 is moved relative to the fixed platen 44, and the movable mold 46 provided on the movable platen 40 and the fixed mold 48 provided in the fixed platen 44 are opened and closed. It's getting old. Note that 50 is a tie bar that connects the base plate 38 and the fixed plate 44 in a fixed position and supports the movable plate 40 in a slidable manner. Also, 52 is
During injection molding of injection resin material, the molds 46, 4
The molds 46, 4 are pressed against the injection resin pressure applied to the molds 46, 48.
This is a pressure increase device for maintaining the mold clamping state of 8.
It is adapted to be connected to the rotary input shaft 20 by a clutch 53.

On the other hand, the rotation input shaft 24 on the side of the injection device 12
are clutches 54 and 56 provided in parallel with each other.
and 58, respectively, a ball screw 60,
It is connected to the long shaft gear 62 and the rotating shaft 64, so that rotational power from the servo motor 14 can be transmitted to the ball screw 60, the long shaft gear 62, and the rotating shaft 64.

Here, the ball screw 60 moves the injection device 12 along with its base 66 to the mold clamping device 10 as the ball screw 60 rotates.
It is for approaching or separating from the
The injection device 12 is configured to be able to press the nozzle 70 of the injection cylinder 68 against the fixed mold 48 by rotationally driving the ball screw 60.

Further, the long shaft gear 62 is a gear 7 fixed to the base of a screw 72 inserted into the injection cylinder 68.
4, and the rotational power from the servo motor 14 is transmitted to the screw 72. According to this rotational operation of the screw 72,
A predetermined injection resin material is delivered and accumulated at the tip of the injection cylinder 68.

Further, a gear 76 is provided on the rotating shaft 64, and in this gear 76, a ball screw 7
It is meshed with a gear 80 fixed to 8.
This ball screw 78 is screwed into a nut member 82 provided at the base of the screw 72, and as the ball screw 78 rotates, the nut member 82, and thus the screw 72, are moved in the axial direction thereof.

In other words, in this injection device 12, the piston of the screw 72 is driven by the rotational power transmitted to the rotating shaft 64 via the clutch 58, and as the screw 72 rotates, the injection The injection resin material delivered and accumulated at the tip of the cylinder 68 is transferred to the molds 46 and 48 of the mold clamping device 10 by driving the piston of the screw 72.
It is designed to be injected into a predetermined product cavity formed between them.

Note that 84 is a back pressure brake for applying a rotational load to the ball screw 78 when the screw 72 is driven to rotate, and by suppressing the rotation of the screw 72 by this back pressure brake 84, the screw 72 is rotated. It is adapted to be retracted based on the screw engagement with the ball screw 78. Further, 86 is a screw position detection sensor for detecting the moving position of the screw 72, and the position information of the screw 72 detected by this sensor 86 is sent to a sequence control device 88, which will be described later.
It is becoming increasingly possible to supply

Further, the servo motor 14 is provided with a rotary encoder 90, and the servo motor 1 detected by the rotary encoder 90
The rotation signal No. 4 is supplied to a servo controller 92 that controls the rotation speed of the servo motor 14.

In this injection molding machine, the clutch 1
8, 53, 54, 56, 58, back pressure brake 84
and servo controller 92 whose operation is controlled by sequence control device 88,
The servo motor 14 is a servo controller 92
By controlling the rotation speed by
The mold opening/closing and mold clamping operations of the mold clamping device 10 and the injection operation of the injection device 12, that is, the injection molding operation of the injection molding machine are performed.

That is, in this injection molding machine, when performing an injection molding operation, first, the clutch 18 is connected based on a control signal from the sequence control device 88, and the nut member 34 is rotated by the rotational power from the servo motor 14. , the movable platen 40 is the fixed platen 4
The molds 46 and 48 are moved close to each other.
A mold closing operation is performed. After this mold closing operation is completed, the clutch 53 is connected by a control signal from the sequence control device 88, and the pressure increase device 5
2, the molds 46 and 48 are clamped to perform a mold clamping operation. Note that the clutch 18 is disengaged after the mold clamping operation is completed.

On the other hand, when this mold clamping operation is completed, the clutch 54 is connected in accordance with the control signal from the sequence control device 88 under the mold clamping state, and as described above, the nozzle 70 of the injection cylinder 68 is connected to the mold clamping device 10. is pressed against a fixed mold 48. When the pressing operation of the nozzle 70 is completed, the clutch 54 is disengaged, while the clutch 56 is connected, and the screw 72 in the injection cylinder 68 is rotated in accordance with the rotation of the servo motor 14. A predetermined injection resin material is delivered and accumulated at the tip. Next, when the screw 72 is retracted to a predetermined position and it is detected that the desired amount of injected resin material has been accumulated based on the position signal from the screw position detection sensor 86, the clutch 56 is disengaged and the screw is released. 72
While the rotation of is stopped, the clutch 58 is connected, the ball screw 78 is rotated, and the screw 72 is pushed forward. As a result, the injection resin material accumulated at the tip of the injection cylinder 68 is injected into the product cavity between the molds 46 and 48. Furthermore, when connecting the clutch 56,
The back pressure brake 84 is activated and rotation of the ball screw 78 is suppressed.

Also, once the injection operation of the injection resin material is completed,
While clutch 58 is disengaged, clutch 5
4 is connected for a certain period of time, and the nozzle 70 of the injection cylinder 68 is separated from the fixed mold 48 by a predetermined distance. Then, when a predetermined cooling period has elapsed, the clutch 53 is disconnected and the increasing pressure of the pressure increasing device 52 that maintains the mold clamping state of the molds 46 and 48 is released, while the clutch 18 is reconnected. ,
As the servo motor 14 rotates, the movable platen 40 is separated from the fixed platen 44, and the molds 46, 48 are opened. After this mold opening operation is completed, the injection molded product is released from the movable mold 46, and the injection molding operation is completed.

On the other hand, the servo controller 92 has a configuration as shown in FIG. 2, and controls the servo motor 14 under the control of the injection molding machine by the sequence control device 88.
According to the control state of the injection molding machine, the drive is controlled according to a preset reference rotation speed.

That is, in FIG. 2, 94 is a motor speed setting device, and the movable platen movement stroke setting device 9
6 and a speed/acceleration/deceleration ratio setting device 98.
Here, the movable platen movement stroke setting device 96 adjusts the movement stroke of the movable platen 40, that is, the molds 46 and 48.
Fixed platen 4 of movable platen 40 whose origin is the mold clamping position with
The device is for setting and storing the maximum moving distance for 4 as a digital value, and a mold closing signal that instructs the mold clamping device 10 to start a mold closing operation from the sequence control device 88 and a mold closing signal that instructs the start of a mold opening operation. The mold opening signal is inputted, and each time the mold closing signal and the mold opening signal are input, the
The value and the movement stroke set value are output to the command value register 100.

The speed/acceleration/deceleration ratio setter 98 also determines the movement distance (hereinafter simply referred to as movement distance) of the movable platen 40 from the origin at the clamping position of the molds 46 and 48 and the movement distance of the movable platen 40 from the reference rotational speed of the servo motor 14. It is for setting and storing digital values corresponding to the direction, or the movement position and movement direction of the screw 72,
By commanding the movement direction, movement distance (movement position), etc. of each of these driven members in combination with the rotational speed, acceleration/deceleration ratio, etc. of the servo motor 14, the servo motor at each movement position of each of these driven members can be commanded. 14 reference rotation speeds can be set. Based on the content of the control signal supplied from the sequence control device 88, the setting device 98 sets a reference rotational speed setting value signal or a reference acceleration/deceleration ratio corresponding to the moving direction and moving distance of the movable platen 40, respectively. The value signal is transferred to a logic circuit 102 (described later).
At the same time, the screw 72 and the injection cylinder 6
A reference rotational speed signal corresponding to the moving direction, moving position, or driving state of
It is now output to . Note that this speed
The acceleration/deceleration ratio setter 98 sets the reference movement speed of driven members such as the movable platen 40 and the screw 72 and the reference acceleration/deceleration ratio thereof.
It is also possible to automatically set the reference rotational speed and reference acceleration/deceleration ratio of No. 4.

Further, in FIG. 2, 106 is a current value register, and the rotation signal from the rotary encoder 90 is supplied via a changeover switch 108 which is operated in conjunction with the changeover switch 104. The pulses of the rotation signal supplied from the rotary encoder 90 are reversibly counted according to the rotation direction of the servo motor 14,
The subtracter 110 is supplied with a signal corresponding to the stored count value.
In addition, this current value register 106 also indicates that each time the mold clamping operation of the mold clamping device 10 is completed, more precisely, the molds 46 and 48 are clamped, and the injection operation of the injection device 12, which will be described later, is completed. Then, every time a mold opening signal is issued from the sequence control device 88, a reset signal is inputted from the sequence control device 88, thereby causing the mold 4 to open.
Each time the mold opening operation is started from the mold clamping state of 6 and 48, the count contents (count value) are reset to the "0" value. In other words, the current value register 106 is configured to supply a signal to the subtracter 110 that is proportional to the moving distance of the movable platen 40 with the origin at the clamping position of the molds 46 and 48.

Note that the current value register 106 is configured to add and count pulses from the rotary encoder 90 when the movable platen 40 is moved in the mold opening direction, while when the movable platen 40 is moved in the mold closing direction. When the pulse is activated, the pulse is subtracted and counted.

On the other hand, this subtracter 110 receives the command value signal from the command value register 100, that is, the mold clamping device 10.
During the mold closing operation, a command value signal corresponding to the "0" value is supplied, and during the mold opening operation, a command value signal corresponding to the travel stroke set value of the movable platen 40 is supplied. Then, the subtracter 110 is
An integrated signal (output signal) corresponding to the count value from the current value register 106 is subtracted from the command value signal, and a subtraction signal representing the result of the subtraction is supplied to the logic circuit 102 and the sequence control device 88. ing. From the subtracter 110,
The size is the actual moving distance of the movable platen 40 from the mold clamping position of the molds 46 and 48 (strictly speaking, the remaining moving distance to the target stop position). A subtraction signal is output that represents the difference between the moving stroke and the actual moving distance, and the sign of which represents the actual moving direction of the movable platen 40. This is supplied to the logic circuit 102 and the sequence control device 88. It is becoming more and more common.

As is clear from the above description, in this embodiment, the movable platen movement stroke setter 96 and the command value register 100 constitute the movable platen movement stroke setting means, and a reset signal is sent to the current value register 106. Supply sequence control device 88
These components constitute a reset means, and the subtracter 110 constitutes a moving distance calculation means.

Logic circuit 102 to which the subtraction signal is supplied
are a subtraction signal from the subtracter 110 representing the actual moving distance and moving direction of the movable platen 40, and a reference rotational speed setting value signal or reference acceleration/deceleration ratio setting value signal from the speed/acceleration/deceleration ratio setting device 98. Based on this, a reference rotational speed corresponding to the actual moving distance and moving direction of the movable platen 40 is sequentially determined, and a reference rotational speed signal representing this reference rotational speed is output to the changeover switch 104. It's getting old.

In addition, the sequence control device 88 detects that the mold closing operation is completed by confirming that this subtraction signal changes from a negative value to a "0" value, and changes from a positive value to a "0" value. By confirming that the mold opening operation has been completed, it is detected that the mold opening operation has been completed.

Further, the switching operation state of the changeover switch 104 is controlled by a changeover control signal from a sequence control device 88, and the speed and speed are controlled according to the changeover control signal from the sequence control device 88. The reference rotation speed signal from the acceleration/deceleration ratio setter 98 and the reference rotation speed signal from the logic circuit 102 are alternatively selected, and the D/A converter 11
2. That is, the movable plate 4
0, the reference rotation speed signal from the logic circuit 102 for controlling the moving speed of the movable platen 40 is selected, and the D/A converter 11
At other times, the speed/acceleration/deceleration ratio setting unit 98 is used to control the moving speed of the injection cylinder 68 and the moving speed or rotational speed of the screw 72. A reference rotational speed signal is selected and the D/A converter 112
It is now being supplied to In addition,
The changeover switch 108 is the changeover switch 1
When the reference rotational speed signal from the logic circuit 102 is selected by 04, as described above,
The rotation signal from the rotary encoder 90 is supplied to the current value register 106, and when the reference rotation speed signal from the speed/acceleration/deceleration ratio setter 98 is selected, the supply of the rotation signal is blocked. .

On the other hand, the D/A converter 112 converts the reference rotational speed signal supplied via the changeover switch 104 into an analog signal, and supplies the analog signal to the subtracter 114. Also, this subtractor 11
4 is connected to a speed calculator 116 that calculates the actual rotational speed of the servo motor 14 based on the rotation signal from the rotary encoder 90.
A signal representing the actual rotational speed of the motor is input. The subtracter 114 subtracts the reference rotational speed signals from the D/A converter 112 with the signal representing the actual rotational speed from the speed calculator 116, and generates a subtracted signal representing the difference between them. , are outputted to the drive amplifier 118. Then, from the drive amplifier 118,
A correction rotation signal corrected according to this difference is supplied to the servo motor 14, and by supplying this correction rotation signal to the servo motor 14, the actual rotation speed of the servo motor 14 is set as the reference. It is designed to match the rotation speed.

In other words, the movable platen 40 is connected to the motor speed setting device 94.
The moving stroke of the movable platen 40 is determined by the movable platen movement stroke setter 96 (the maximum moving distance from the mold clamping position of the molds 46, 48 as the origin), and the speed/acceleration/deceleration ratio setter 98 is used to set the movable platen 40. By setting in advance the reference rotational speed of the servo motor 14 corresponding to the moving direction and moving distance,
In both the mold-closing stroke and the mold-opening stroke, it is moved faithfully according to the speed curves set by the setting devices 96 and 98. In addition, the injection cylinder 68 and the screw 72 are also connected to the speed and speed of the motor speed setting device 94, similar to the movable platen 40.
By setting in advance the reference rotation speed of the servo motor 14 according to its movement direction, movement position, and driving state using the acceleration/deceleration ratio setter 98, the servo motor 14 can be moved faithfully or moved according to a desired speed curve. It is forced to rotate.

In this way, in this injection molding machine, the movable platen 40
The moving speed of the injection cylinder 68, the moving speed of the screw 72, and the rotating speed of the screw 72 can be easily set by simply setting the set values using the setters 96 and 98, respectively. If it becomes necessary to change the movement control speed of the movable platen 40 due to changes in the molds 46, 48, etc., or if the injection amount or material of the injection resin material changes, the rotation control speed or extrusion control of the screw 72 may be changed. If it is necessary to change the speed, simply use the setting devices 96, 98.
These movement control speeds and rotation control speeds can be easily changed by simply changing the set values.

In particular, when changing the movement control speed of the movable platen 40, there is no need for the troublesome operation of changing the mounting position of the limit switch each time, unlike in conventional mold clamping devices. This makes it extremely simple, and the time required for the change operation can be significantly shortened. In addition, in the mold clamping device 10 of this embodiment, unlike conventional devices, the accuracy of detecting the moving position of the movable platen 40 does not decrease based on the error in the mounting position of the limit switch, so the accuracy of the stop position of the movable platen 40 is reduced. Therefore, there is an advantage that the clamping position of the injection molded product at the time of demolding becomes extremely accurate.

Further, according to the mold clamping device 10 of this embodiment, the moving speed of the movable platen 40 can be easily and precisely controlled by a simple operation of simply performing detailed setting operations using the setting devices 96 and 98. Therefore, by setting the moving speed of the movable platen 40 to a more appropriate speed, the molds 46, 4
8, it becomes extremely easy to shorten the mold opening/closing time and, by extension, the injection molding cycle, and even in that case, there is an advantage that changing the moving speed of the movable platen 40 does not become so troublesome. There is.

Moreover, in the mold clamping device 10 of this embodiment, the reference rotational speed of the servo motor 14 when the movable platen 40 is moved is relative to the fixed platen 44 of the movable platen 40 with the mold clamping position of the molds 46 and 48 as the origin. The movable platen Compared to the case where the moving stroke end of the movable platen 40 is simply set according to a theoretically calculated value based on the dimensions of the molds 46, 48, etc., there is an advantage that the stop position accuracy is higher. Compared to the case where the reference rotational speed of the servo motor 14 is set based on the movement position of the fixed platen 44 as the absolute distance from the fixed platen 44, there is an advantage that the setting operation when changing the setting of the reference rotational speed is easier. It is.

Furthermore, a current value register 106, which represents the moving position of the movable platen 40 with a count value (memory content) based on the mold clamping position of the molds 46, 48, generates a mold opening signal when the molds 46, 48 are in the mold clamping state. Every time it is uttered,
That is, since it is reset every time a mold opening operation is started, the output pulse of the rotary encoder 90 stored in the current value register 106 during the injection operation or screw rotation operation of the injection screw 72 in the injection device 12 In addition, even if a counting error occurs in the current value register 106 due to external noise, it will not be accumulated, and therefore the influence of external noise will be completely eliminated. Due to the accumulation of counting errors caused by
This effectively prevents a serious problem from occurring in the operating state of the movable platen 40 and, by extension, in the operation of the injection molding machine.Moreover, under the operating state of the injection device 12, even if the current value register 100 is not affected by external noise. Even if the injection molding machine malfunctions, it can be reliably prevented from causing a substantial problem in the operation of the injection molding machine.

In the above embodiment, the movement stroke of the movable platen 40 and the reference rotation speed setting value of the servo motor 14 are set separately by the setters 96 and 98, but the movement of the movable platen 40 It is also possible to automatically set the stroke by setting a reference rotational speed using the speed/acceleration/deceleration ratio setting device 98.

Further, in the above embodiment, of the nut member 34 and the ball screw 42 that constitute the ball screw mechanism that is the movable plate feeding mechanism, the nut member 34 is attached to the base plate 3.
The present invention has been applied to the mold clamping device 10 in which the ball screw 42 is provided on the movable platen 40 side, but the ball screw 42 is provided on the base plate 38 side and the nut member 34 is movable plate 4
The present invention can also be applied to a type of mold clamping device provided on the zero side.

In addition, although not listed one by one, the present invention may be modified without departing from its spirit.
What can be implemented with modifications, improvements, etc.
It goes without saying.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining an example of an injection molding machine according to the present invention, and FIG. 2 is a block diagram for explaining the servo controller of FIG. 1. 10: mold clamping device, 12: injection device, 14: servo motor, 34: nut member, 40: movable platen, 4
2: Ball screw, 44: Fixed plate, 46, 48: Mold, 68: Injection cylinder, 72: Screw, 8
8: Sequence control device, 90: Rotary encoder, 92: Servo controller, 94: Motor speed setter, 96: Movable plate movement stroke setter, 98: Speed/acceleration/deceleration ratio setter, 100: Command value register, 102: Logic circuit, 106: Current value register, 110, 114: Subtractor, 11
6: Speed calculator, 118: Drive amplifier.

Claims (1)

[Claims] 1. By rotating each ball screw mechanism provided in the mold clamping device and the injection device through a plurality of clutches by one servo motor, the mold clamping device can rotate the mold. In an injection molding machine that selectively performs a mold opening/closing operation and an injection operation or a screw rotation operation of an injection screw in the injection device, an output pulse from a rotary encoder provided on the servo motor is applied to the servo motor. a current value register that reversibly counts and stores according to the rotational direction; a reset means that resets the current value register each time the mold clamping device starts a mold opening operation of the mold; and the mold clamping device A movable platen movement stroke setting means for setting a movement stroke of the movable platen that is moved relative to the fixed platen, and a comparison between the counted value of the current value register and the movement stroke value set by the movable platen movement stroke setting means. and a moving distance calculation means for calculating a moving distance of the movable platen with respect to the fixed platen, using the mold clamping position of the mold as the origin, , by controlling the moving distance of the movable platen by the one servo motor, the influence of the output pulse of the rotary encoder stored in the current value register is reduced during the injection operation and screw rotation operation of the injection screw in the injection device. An injection molding machine characterized by eliminating