JP3401669B2 - Safety device for mold clamping mechanism of injection molding machine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for an injection molding machine which detects that a safety door has been opened and stops the operation of a servomotor for driving a mold clamping mechanism. The present invention relates to a safety device for a fastening mechanism. 2. Description of the Related Art Conventionally, when a safety door disposed on a side of a mold clamping mechanism is opened, the operation of a servomotor for driving the mold clamping mechanism is immediately stopped to thereby provide safety to an operator. The safety device for the clamping mechanism of the injection molding machine that ensures
JP-B-4-11099 and JP-B-5-35662
This is known from Japanese Patent Publication No. This type of safety device for a mold clamping mechanism detects that a safety door has been opened by a limit switch (detection switch), and in response to the detection, a controller controls a servo circuit for driving a servomotor. It has a function to stop the operation of the servomotor by giving a command signal to stop the servomotor. [0004] However, the above-mentioned conventional safety device for a mold clamping mechanism has a problem in that the safety of the controller, the limit switch, and the motor encoder due to failure or malfunction due to a wiring trouble or the like. If the controller does not output a normal stop command signal to stop the servo motor despite opening the door, the servo motor cannot be stopped reliably, and as a result, the safety for the operator and the device There was a problem that the reliability could not be sufficiently secured. The present invention has been made to solve the problems existing in the prior art, and provides a safety for a mold clamping mechanism of an injection molding machine, which can greatly improve the safety for an operator and the reliability of the apparatus. The purpose is to provide the device. SUMMARY OF THE INVENTION The present invention is directed to a servo for driving a mold clamping mechanism Mcm by detecting that a safety door D disposed beside a mold clamping mechanism Mcm is opened. When configuring the safety device 1 for the mold clamping mechanism of the injection molding machine for stopping the operation of the motor 2, a first detection switch 4 for detecting that the safety door D is opened, and the first detection switch 4
Is detected by the controller 9 to the servo circuit 3 for controlling the drive of the servo motor 2.
Control system 5 for applying a stop command signal Sc for stopping the operation
A second detection switch 6 for detecting that the safety door D is opened, and a zero clamp switch 7 provided in the servo circuit 3 by the detection of the second detection switch 6.
Is switched to the zero clamp contact 7x side. Thus, when the safety door D is opened, the first detection switch 4 in the first control system 5 detects the signal, and the controller 9 applies the stop command signal Sc to the servo circuit 3 at the same time as the second control system. 8 second detection switch 6
Is detected, the zero clamp switch 7 provided in the servo circuit 3 is forcibly switched to the zero clamp contact 7x side and clamped to the zero level. As a result, the servo circuit 3 executes the stop control, and the operation of the servo motor 2 stops.
Therefore, even if the controller 9, the first detection switch 4 and the motor encoder malfunction or malfunction due to a failure or wiring trouble, and the first control system 5 does not function, the servo circuit 3 in the second control system 8 does not function. Is forcibly clamped to the zero level by the zero clamp switch 7, so that the operation of the servomotor 2 is reliably stopped. On the other hand, even if the second detection switch 6 and the zero clamp switch 7 malfunction or malfunction due to a wiring trouble or the like, and the zero clamp switch 7 of the second control system 8 does not switch to the zero clamp contact 7x side. Since the stop command signal Sc from the controller 9 is normally applied to the signal line of the servo circuit 3, the operation of the servo motor 2 is reliably stopped. Usually, a mechanical safety mechanism (not shown) is separately provided in this type of mold clamping mechanism Mcm, and the movement of the mold clamping mechanism Mcm (the rotation of the servo motor 2) is performed by operating the stopper mechanism. Mechanically and forcibly stopped. Next, preferred embodiments according to the present invention will be described in detail with reference to the drawings. First, the configuration of a safety device 1 for a mold clamping mechanism according to this embodiment will be described with reference to FIGS. In FIG. 1, a virtual line indicates an injection molding machine M. The injection molding machine M is roughly divided into an injection device Mi for injecting and filling a resin into a mold and a mold clamping device Mc for supporting the mold. Further, the mold clamping device Mc includes a mold clamping mechanism Mcm driven by the servomotor 2 and a safety door D disposed on a side of the mold clamping mechanism Mcm. The safety door D is slid in a horizontal direction. Can be opened and closed. On the other hand, the area inside the dotted line is a servo circuit 3 for controlling the drive of the servomotor 2. The output side of the servo circuit 3 is connected to the servomotor 2 and the input side is connected to a controller 9. The servo circuit 3 shows only a speed control system related to the present invention. The controller 9 has a computer function and gives various command signals to the servo circuit 3 for controlling the drive of the servomotor 2. Further, the servomotor 2 is provided with a motor encoder 11 for detecting the rotation of the servomotor 2. The detection information of the motor encoder 11 becomes a position detection value when the mold clamping mechanism Mcm is driven, and is provided to the controller 9 and also to an input of the speed conversion unit 12 provided in the servo circuit 3. On the other hand, the mold clamping device Mc is provided with a first detection switch 4 and a second detection switch 6 for detecting that the safety door D is opened. As shown in FIG. 2, the first detection switch 4 is mounted on the upper part of the fixed cover Cc located inside the safety door D so that the upper position of the safety door D can be detected. The first detection switch 4 has a built-in limit switch, and has an operation lever 23 having one end fixed to the operation rotation shaft 21 and having a roller 22 at the other end. The operation lever 23 is at a position indicated by a virtual line 23s in a natural state, and is off at this position. On the other hand, the operation lever 23 is rotatable against a spring at a position indicated by a solid line by an external force, and is turned on at this position. Further, an engagement projection 24 is attached to the inner surface of the safety door D. As a result, when the safety door D is completely closed, the engaging projection 24 engages with the roller 22 and pushes it, so that the operation lever 23 is rotated to the position shown by the solid line in FIG. 4 turns on. On the other hand, if the safety door D is opened by a certain amount or more, the operation lever 23 elastically returns to the position indicated by the imaginary line 23s and is turned off. Therefore, opening of the safety door D can be detected by turning off the first detection switch 4, and the detection result is given to the controller 9. As shown in FIG. 3, the second detection switch 6 is mounted on a fixed base Cb located inside the safety door D so that the lower position of the safety door D can be detected. . FIG. 3 is a layout viewed from the plane direction. The second detection switch 6 has a built-in limit switch, and has an operation lever 27 having one end fixed to the operation rotation shaft 25 and a roller 26 at the other end. The operation lever 27 is in a position shown by a solid line in a natural state, and is off in this position. On the other hand, the operation lever 27 can be rotationally displaced against a spring at a position indicated by a virtual line 27s by an external force, and is turned on at this position. Further, an engagement surface portion 28 is provided on the inner surface of the safety door D. Thus, when the safety door D is completely closed, the engagement between the engagement surface portion 28 and the roller 21 is released, so that the operation lever 27 elastically returns to the position shown by the solid line and is turned off. On the other hand, if the safety door D is opened by a certain amount or more, the engaging surface 28 moves the operation lever 27 to the position shown in FIG.
, The second detection switch 6 is turned on. Therefore, the second detection switch 6
Is turned on to detect that the safety door D has been opened, and this detection result is applied to the servo circuit 3 to be used for switching a zero clamp switch 7 described later. On the other hand, the servo circuit 3 includes a zero clamp switch 7 at a preceding stage. The zero clamp switch 7 includes a zero clamp contact 7x and a normal contact 7y as fixed contacts.
The zero clamp contact 7x is grounded to zero level, and the normal contact 7y is connected to the controller 9 side. Further, the movable contact 7z is connected to one comparison input unit of the speed deviation calculating unit 13 via the signal line L. The detection result of the second detection switch 6 described above is given to the servo circuit 3. If the second detection switch 6 is off (input "0" of the servo circuit 3), the zero clamp switch 7 is switched to the normal contact 7y side. On the other hand, if the second detection switch 6 is on (input "1" of the servo circuit 3), the zero clamp switch 7 is switched to the zero clamp contact 7x side. The output of the speed converter 12 is connected to the other comparison input of the speed deviation calculator 13.
A deviation output unit of the speed deviation calculation unit 13 is connected to one comparison input unit of the current deviation calculation unit 15 via the speed compensation unit 14. Further, a current detector 16 for detecting the operating current of the servomotor 2 is provided to the other comparison input of the current deviation calculator 15.
And the deviation output section of the current deviation calculation section 15 is connected to a driver section 17 including current compensation. And
The servo motor 2 is connected to the output section of the driver section 17. Next, the operation of the mold clamping mechanism safety device 1 according to the present embodiment will be described with reference to the flowchart shown in FIG. First, if the safety door D is completely closed,
The first detection switch 4 is turned on, and the second detection switch 6
Turns off. In this case, since the zero clamp switch 7 of the servo circuit 3 has been switched to the normal contact 7y side, various command signals for driving and controlling the servo motor 2 are given from the controller 9 to the servo circuit 3, and the normal control is performed. The operation is performed. Specifically, a command signal corresponding to a preset speed command value is applied from the controller 9 to the servo circuit 3, applied to one of the deviation input units of the speed deviation calculation unit 13, and detected by the motor encoder 11. The detected position value is converted into a detected speed value by the speed conversion unit 12 and provided to the other comparison input unit of the speed deviation calculation unit 13. Since the deviation amount between the position detection value and the position command value is obtained from the deviation output unit of the velocity deviation calculation unit 13, the deviation amount is compensated by the speed compensation unit 14, and then the deviation amount with respect to the current using the current deviation calculation unit 15. It is provided to the driver unit 17 via the minor loop control circuit. This allows
The drive of the servo motor 2 is controlled so as to match the speed command value. On the other hand, it is assumed that the safety door D is opened during the normal control operation (step S1). In this case, the first detection switch 4 of the first control system 5 is turned off (step S2), and the second detection switch 6 of the second control system 8 is turned on (step S3). When the first detection switch 4 is turned off, this detection result is given to the controller 9, and a stop command signal Sc for stopping the servo motor 2 is given from the controller 9 to the servo circuit 3 (steps S4, S5). . At the same time, when the second detection switch 6 is turned on, the zero clamp switch 7 provided in the servo circuit 3 is switched to the zero clamp contact 7x side, and the signal line L is forcibly clamped to the zero level (step S6). S7). Therefore, the stop command signal Sc is input to the signal line L or the signal line L is clamped at the zero level, and the operation of the servomotor 2 is stopped by the execution of the stop control by the servo circuit 3 (Step S).
8). Now, it is assumed that the controller 9, the first detection switch 4, and the motor encoder 11 are inoperable or malfunction due to failure or wiring trouble, and the first control system 5 does not function. In this case, the controller 9 does not output a normal stop command signal for stopping the servo motor 2, but the zero clamp switch 7 of the servo circuit 3 in the second control system 8 is switched to the zero clamp contact 7x side, so that the servo 9 The signal line L of the circuit 3 is forcibly clamped to the zero level, and the operation of the servomotor 2 is reliably stopped. On the other hand, it is assumed that the second control system 8 stops functioning due to failure or malfunction of the second detection switch 6 and the zero clamp switch 7 or wiring trouble. In this case, the zero clamp switch 7 may not be switched to the zero clamp contact 7x side. However, since the stop command signal Sc is normally given to the servo circuit 3 through the signal line L, the operation of the servo motor 2 is stopped. Stop reliably. Incidentally, a mechanical safety mechanism (stopper mechanism, not shown) is usually provided separately in this type of mold clamping mechanism Mcm, so that the detection by the first detection switch 4 and the second detection switch 6 Then, the stopper mechanism operates, and the movement of the mold clamping mechanism Mcm, that is, the rotation (inertia) of the servomotor 2 is mechanically and forcibly stopped. Therefore,
Even if one of the control systems 5 or 8 stops functioning, the other control system 8 or 5 functions, so that the safety for the worker and the reliability of the device are greatly improved. The embodiment has been described in detail above.
The present invention is not limited to such an embodiment,
The detailed configuration, method, etc. can be arbitrarily changed, added, or deleted without departing from the gist of the present invention. For example, although the first detection switch 4 and the second detection switch 6 are illustrated as limit switches, detection switches or sensors according to other embodiments may be used. Further, it is desirable that the first detection switch 4 and the second detection switch 6 are arranged apart from each other, but their positions are arbitrary. Further, regardless of whether the zero clamp switch 7 is a mechanical switch or an electronic switch, it is only necessary that the signal line L can be clamped to the zero level. Although the embodiment has exemplified the case where the speed control system is zero-clamped, the position may be locked by zero-clamping the position control system. As described above, the safety device for a mold clamping mechanism of an injection molding machine according to the present invention includes a first detection switch for detecting that a safety door is opened, and a detection of the first detection switch. A first control system that applies a stop command signal to a servo circuit that drives and controls a servo motor from a controller, and a second detection switch that detects that a safety door has been opened; and a second detection switch. , A second control system that switches the zero clamp switch provided in the servo circuit to the zero clamp contact side is provided, so that the safety for workers and the reliability of the device can be significantly improved. Play.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a safety device for a mold clamping mechanism according to an embodiment of the present invention. FIG. 2 is a side view of a first detection switch in the safety device for the mold clamping mechanism. FIG. 3 is a layout view of the second detection switch in the safety device for the mold clamping mechanism as viewed from the plane direction. FIG. 4 is a flowchart for explaining the operation of the safety device for the mold clamping mechanism. 1 Safety device for clamping mechanism 2 Servo motor 3 Servo circuit 4 First detection switch 5 First control system 6 Second detection switch 7 Zero clamp switch 7x Zero clamp contact 8 Second control system 9 Controller Mcm Mold clamping mechanism D Safety Door Sc stop command signal

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 45/00-45/84

Claims (1)

(57) [Claim 1] Injection molding for detecting that a safety door arranged on a side of a mold clamping mechanism is opened and stopping the operation of a servo motor for driving the mold clamping mechanism. In a safety device for a mold clamping mechanism of a machine, a first detection switch for detecting that a safety door is opened, and a servo circuit for driving and controlling the servomotor from a controller by detecting the first detection switch. A first control system for applying a stop command signal for stopping the servomotor, a second detection switch for detecting that the safety door has been opened, and a zero detection circuit provided in the servo circuit by detecting the second detection switch. A safety device for a mold clamping mechanism of an injection molding machine, comprising a second control system for switching a clamp switch to a zero clamp contact side.