JPH07195437A - Device for returning to original point of injection molding machine driven by servomotor - Google Patents

Abstract

PURPOSE:To decrease errors in original point detection and thus perform control correctly by providing a detecting means and a position detector for detecting the original point of an injection driving device, clamp device and ejector, and making the driving of a corresponding servomotor stop by an original point- determination means at the time of receiving one rotational signal from the position detector. CONSTITUTION:A position detector PS is provided on an injection servomotor MS for shifting a screw to the axial direction by an injection driving device 2, and a position detector PC is also provided on a clamping servomotor MC for driving a clamping device 4 to open and close a mold. Furthermore, a position detector PE is provided on an ejector servomotor ME for driving an ejector 5. A sensor SS serves to perform the positioning of an injection molding machine, and in the same manner, a sensor SC serves to detect the original point position of the clamping device 4, and a sensor SE acts to detects the original point position of an ejector 5. As each detector means detects the original point, they receive one rotational signal from each detector means and stop the driving of each servomotor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw, a clamp device, and an ejector device in an injection molding machine driven by a servomotor.

[0002]

2. Description of the Related Art In a conventional injection molding machine, a hydraulic device such as a hydraulic cylinder drives an injection device for moving a screw in an axial direction, a clamp device, and an ejector device. Therefore, the origin of the screw, the clamp device, and the ejector device is a position where the hydraulic cylinder is operated to one side, and the origin is naturally set.

[0003]

When attempting to drive the above-mentioned injection device, clamp device, or ejector device, which had been hydraulically driven, by a servomotor, it is not possible to mechanically position it at the origin, and it is possible to achieve accurate positioning by some means. Need to be positioned. In particular, since the moving speed and torque are controlled by the position of the screw and the position of the movable plate in the clamp device, it is very important to know and control these positions accurately. Therefore, it is very important to accurately set and position the origin of these positions, that is, the coordinate position "0", but the present invention accurately positions the screw, the clamp device, and the ejector device at this origin. An object of the present invention is to provide an injection molding machine using a servo motor capable of performing the above.

[0004]

According to the present invention, servo motors for driving an injection drive device, a clamp device, and an ejector device are provided, and a sensor, a dog, and the like for detecting the origin of each device are provided. Providing detection means,
Further, each servo motor is provided with a position detector. Each device is provided with origin setting means for stopping the drive of the corresponding servo motor upon receiving the one rotation signal from the corresponding detector after receiving the origin detection signal of the corresponding detecting means. This has solved the said subject.

[0005]

When the origin return command is issued to each device, the corresponding servo motor is driven to drive the corresponding device. Then, when the corresponding detecting means detects the origin, the corresponding origin determining means receives the output of one rotation signal from the corresponding position detecting means and stops the corresponding servo motor, thereby obtaining the accurate origin. To stop each device and perform home return.

[0006]

FIG. 1 is a block diagram of an embodiment of the present invention.
1 is a mold, 3 is a heating cylinder, 2 is the heating cylinder 3
An injection drive device for moving the screw in the axial direction to perform injection (means for rotating the screw is not shown), MS is an injection servomotor for moving the screw in the axial direction by the injection drive device, PS is a position detector provided in the injection servomotor MS. Reference numeral 4 is a clamp device for opening and closing the mold 1, MC is a clamp servomotor for driving the clamp device 4, and PC is a position detector provided on the clamp servomotor MC. 5 is an ejector device for ejecting a product from the mold 1, M
E is a servomotor for an ejector that drives the ejector device, and PE is a position detector provided on the servomotor ME for the ejector. Reference numerals 6 to 8 are servo circuits for driving and controlling the servo motors MS, MC, ME for the injection, clamp, and ejectors.

Further, SS, SC, SE are sensors composed of proximity switches and the like, and as shown in FIG. 2, the sensor SS is a moving plate 9S which moves with the movement of the screw in the axial direction.
The dog DS provided on the base of the injection molding machine is detected to position the origin. Similarly, the sensor SC is provided on the moving plate 9C that moves together with the movable plate to which the mold 1 is attached, detects the dog DC provided on the base, and positions the origin of the clamp device 4. Further, the sensor SE is provided on the moving plate 9E provided on the product ejecting means of the ejector device 5, and the origin of the ejector device 5 is detected by the dog DE provided on the movable plate or the like.

Reference numeral 10 is a control device such as NC, 11 is a central processing unit (hereinafter referred to as CPU), and 12 is an output circuit connected to each servo circuit 6, 7, 8. An input circuit 13 is an A / D converter 17 for A / D converting the outputs of the position detectors PS, PC, PE and the sensors SS, SC, SE, and the temperature sensor ST for detecting the temperature of the heating cylinder. It is connected to the. Reference numeral 14 denotes a memory including a ROM for storing a control program for controlling the injection molding machine, a RAM for arithmetic processing, etc., and a reference numeral 15 denotes a manual operation input device for inputting various set values and commands. , 16
Is a bus.

Next, the operation of this embodiment will be described with reference to the operation flows of FIGS. When a home-return command is input from the manual operation input device 15, the CPU 11 first turns on the injection drive device, the clamp device, which is turned on when the home-return operation is performed.
All flags FS, FC, FE of the ejector device are O
It is judged whether or not it is N (step S1), and if all are ON, the origin return process is completed, but even one is ON.
If not, then if the screw has returned to the origin, it is judged whether or not the flag FS that is ON is ON (step S2). If it is ON, the process proceeds to step S5,
If it is not ON, it is judged whether or not the temperature of the cylinder is normal (step S3). If it is not normal, the process proceeds to step S5, and if it is normal, the screw origin return process (step S).
4) is performed.

As shown in FIG. 4, the process first determines whether or not the sensor SS is ON (step SB1), that is, whether or not the sensor SS detects the dog DS in FIG. If it is detected, the injection servomotor MS is driven to move the screw forward (leftward in FIG. 1). And the sensor SS
Does not detect the dog DS and waits until it is turned off (step SB3), and then the timer T1 is started (step SB4). Next, when the timer T1 times out (step SB5), the screw is retracted (step SB6). Therefore, sensor SS is dog D
When S is detected and turned on (step SB7), the timer T2 is started to decelerate the screw, retract the screw at a constant speed, and wait until the timer T2 times up (steps SB8 and SB9). When the timer T2 times out, it is then determined whether or not a one-rotation signal is output from the position detector PS (step B10). When one rotation signal is input, the screw movement is stopped and the flag FS is set to 0.
N is set (steps SB11 and SB12), the origin return of the screw is completed, and the process returns to the main routine of FIG.

Next, the CPU 11 judges whether or not the sensor SE of the ejector device 5 detects the dog DE and is ON (step S5). If it is not ON, the ejector servomotor ME is driven and the sensor SE is activated. Dog DE
The shaft of the ejector device is retracted until it detects that the ejector pin or the like is completely escaped from the mold 1 (step S
6). Next, it is determined whether or not the flag FC indicating the completion of the origin return of the clamp device is ON (step S7), and if the origin is returned, the process proceeds to step S9. Perform S8). The origin return process of the clamp device 4 is similar to the screw origin return process shown in FIG. 4, except that the sensor SS in steps SB1, SB3, SB7 is changed to the sensor SC, and steps SB2, SB6, SB11. Point of the screw on the axis of the clamp device, step SB
The operation is the same as the screw origin return processing described above except that the one-rotation signal in 10 changes to the one-rotation signal from the position detector PC, and the flag FS in step SB12 changes to the flag FC. The timer T
The values of 1 and T2 may be changed as necessary.

When the origin return processing (step S8) of the clamp device is completed as described above, the CPU 11 next reads the flag FE (step S9), and the flag FE is set to O.
If the origin return of the ejector device 5 is completed at N, the process proceeds to step S1. If the flag FE is not ON and the home return is not completed, the ejector device home return process (step S10) is performed. This process is also similar to the screw origin return process in FIG. 4, and the difference in FIG. 4 is that the sensor SS in steps SB1, SB3, SB7 is the sensor SE, and the screws in steps SB2, SB6, SB11 are the axes of the ejector device. , The one rotation signal of step SB10 becomes the signal from the position detector PE,
The operation is the same except that the flag FS of B12 is changed to the flag FE.

In the above embodiment, after the sensors SS, SC and SE are turned on in step SB7 of FIG. 4, the timer T2 is activated to retract each axis for a certain period of time (steps SB8 and SB9). The steps SB8, SB
It is also possible to eliminate 9 and stop each axis when one rotation signal is input after the sensors SS, SC, SE are turned on.

[0014]

According to the present invention, the servomotors are respectively provided as the drive sources of the injection drive device, the clamp device, and the ejector device, and the detection means for detecting the origin including the sensor such as the proximity switch and the dog provided for each device. Since the origin is detected by, and the position where one rotation signal is received from the position detector provided in each servo motor is set as the true origin of each device, the error of origin detection becomes very small. Since the position of the screw, the position of the movable plate of the clamp device, and the position of the ejector are determined based on
It is possible to accurately control the injection molding machine that controls the speed and torque based on the positions of the screw and the movable plate.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a sensor and a dog.

FIG. 3 is an operation processing flow of an embodiment of the present invention.

FIG. 4 is a flow chart of origin return processing in FIG. 4 and the same embodiment.

[Explanation of symbols] MS, MC, ME Servo motor PS, PC, PE Position detector SS, SC, SE Sensor DS, DC, DE Dog 1 Mold 10 Controller

Claims (2)

[Claims] 1. A servo motor provided for each device that drives an injection drive device, a clamp device, and an ejector device of an injection molding machine, and a detection unit that detects the origin of each device driven by each servo motor. A position detector provided in each servo motor, and an origin determining means for stopping the drive of the corresponding servo motor when receiving a one-rotation signal from the corresponding position detector after receiving the origin detection signal from the corresponding detecting means. A home-return device for an injection molding machine driven by a servo motor, which is provided for each device. 2. The origin determining means receives the origin detection signal from the corresponding detecting means, drives the corresponding servomotor at a constant low speed for a certain period of time, and then receives one rotation signal from the corresponding position detector. The origin returning device of an injection molding machine driven by the servo motor according to claim 1, which stops the servo motor.