JPH02210234A - Output detecting device for motor driven type molding machine - Google Patents

Abstract

PURPOSE:To securely and speedily control a moving force and a holding force by comparing the detected current and set current of a servo-motor with each other by a comparator. CONSTITUTION:When the servo-motor 35 is rotated forward while a transmission shaft is connected by a clutch mechanism 38, a rotary disk is rotated by the transmission shaft and a transmission gear and a screw shaft is fed out to convert rotary motion into linear motion, thereby closing a metallic mold. Large torque is generated by the closure of the metallic mold and a current increases. At this time, the value of a current setter 49 where torque matching necessary torque is set is compared with the detected current of a current detector 47 by a comparator 48 and when a confirmation signal for their coincidence is generated, a centralized controller 43 excites a mold clamping force holder 39 to fix the transmission shaft on a braking housing side. Thus, the transmission shaft is fixed and a movable disk maintains the mold clamping state. In this state, the turning force of the transmission shaft operates, so the clutch mechanism 38 is opened successively to the excitation of the holder 39 to disconnect the transmission shaft, so that the turning force of the motor 35 is used for injection, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an output detection method in an electric molding machine using a motor as a drive source, such as an injection molding machine, a compression molding machine, a transfer molding machine, etc.

[Prior Art] In an injection molding machine, the force for moving or holding a movable member is detected, such as by forcefully clamping a mold in a mold clamping device, controlling injection pressure in an injection device, or touching a nozzle to a mold. It is often necessary to do so. For example, this is the case when strong mold clamping is confirmed and detected and a command signal is given to start the next step, injection.

[Problem to be solved by the invention] In conventional hydraulic molding methods, pressure sensors such as pressure gauges are attached to each hydraulic actuator for mold clamping, injection, nozzle touch, etc., or to the conduit in its vicinity for detection. There were many things.

However, in a molding machine that uses a motor as a drive source and mechanically transmits its rotational force to move or hold movable members, it is necessary to This must be done by detecting the amount of compression applied to the transmission member and the amount of deformation of the movable member using a strain gauge or the like. Moreover, in addition to problems with installation space, durability, and cost, it is also vulnerable to environmental changes such as temperature and humidity (,
There were problems with using it in production machines, such as errors easily occurring and accuracy being difficult to maintain depending on the mounting position and method.

[Means for Solving the Problems] This invention is an electric! This machine was devised to solve the above-mentioned problems of a molding machine with a drive source of 21 machines, and its features include an electric motor, a rotating member that converts the rotational motion of the electric motor into linear motion, and a screw. In the electric molding machine having a force transmission mechanism equipped with a member, the transmission mechanism converts rotational force into a linear force and transmits it to a movable member, and moves or holds the movable member. fJJ I
is a servo motor, and includes a current detector to detect the current flowing through the servo motor, a current setting device to check the generation of output torque of the servo motor, and a detection current of the current detector and a setting current of the current setting device. and a comparator that compares the two and generates a match confirmation signal.

[Function] When a large torque is generated in the movable member and the current flowing to the servo motor increases, a comparator compares the current detected by the current setter and the current detector, which have a torque setting that corresponds to the torque. When a match confirmation signal occurs, the concentration $
control device is activated.

[Example] Hereinafter, the present invention will be described in detail by taking as an example the case of maintaining mold clamping force in the illustrated injection molding machine.

In the figure, 1 indicates a mold clamping mechanism, and 2 indicates an injection mechanism. The mold clamping mechanism 1 includes a tie bar 12 installed on a pair of fixed plates 10 and 11 on a machine stand 3, and a movable plate 13 movably attached to the tie bar 12. Molds 14 and 14 are provided on opposing surfaces of the fixed platen 11 and the movable platen 13, respectively.
Further, a screw shaft 15 is provided protruding from the opposite surface of the movable platen 13. This screw shaft 15 is screwed into a rotary member 116 rotatably attached to the other fixed M10, and a gear 17 is attached to the rotary disc 16, and the rotary disc 16 rotates together with the gear 17. When the screw @15 is twisted,
constitutes a mold opening device that moves together with the movable platen 13.

The injection mechanism 2 includes an injection heating cylinder 21 containing a screw 20.
and a movable housing 22 on the machine base that also serves to hold the injection heating cylinder 21. Inside the housing 22, a rear end portion of the screw 20 and a screw holding member 25 are housed so as to be slidable in the front and back direction.

Further, a screw rotation gear 24 is provided at the rear end of the screw 20.
The end of the extension shaft 26 is rotatably connected to the screw holding member 25.

Furthermore, a screw shaft 30 which is rotatably held by the housing wall 22a and is integral with the shaft portion 29 having the injection gear 28 is screwed into the screw receiving member 27 provided at the rear of the screw holding member 25. This constitutes a force transmission mechanism. Further, the outer end of the shaft portion 29 of the screw shaft 3o is connected to a brake 31 for back pressure control fixed to the housing wall portion 22a.
It is connected with. This brake 31 is equipped with a hysteresis brake inside.

32 is a power transmission shaft on the side of the mold clamping mechanism, which is attached to the fixed plate 10°1.
The transmission gear 33 is rotatably supported on the lower part of the fixed plate 1o, and has a transmission gear 33 at the outer end that meshes with the gear 17 in the vicinity of the stationary platen 1o, and a key or spline is provided at the inner end.

34 is a transmission shaft on the injection mechanism side, which is supported within the lower part of the housing 22 and also transmits! A drive belt 36 is mounted between the outer end of the l1IJ shaft 34 and a servo motor 35 installed on the lower side of the housing, and the transmission shaft 34 is rotated by the servo motor 35. Note that 35a is a tough meter generator.

At the inner end of the transmission shaft 34, a coupling 31 for connecting the transmission shaft 32 on the mold clamping mechanism side is connected to the electromagnetically actuated clutch mechanism 3.
8, and are connected to each other so as to be freely accessible and detachable.

This joint 31 has a shaft portion rotatably and slidably supported by the housing 22, and a keyway or spline formed integrally on the outer end of the shaft portion to receive the inner end of the transmission @32. The cylinder 37a is made up of a cylinder, and an electromagnetically operated mold clamping force retainer 39 is provided on the shaft portion. This mold clamping force retainer 39 is composed of a brake plate fixed to the housing wall and an electric gear keyed to the shaft part so as to be movable in the axial direction. ,
The mold clamping force is maintained through the transmission shaft 32.

In addition, in the figure, 40 is a transmission gear provided on the transmission shaft 34 together with an electromagnetically operated clutch mechanism 408, which meshes with the injection gear 28. A transmission gear 41 is provided on the transmission shaft 34 together with an electromagnetically operated clutch mechanism 418, and meshes with the screw rotation gear 24.

FIG. 2 shows a control device in which a speed setting device 45 and a torque setting device 4G are connected in parallel between a central control device @43 and a motor control amplifier 44 connected to a servo motor 35 and a tachometer generator 35a. It is provided for. A current detector 47 provided in the circuit of the servo motor 35 is connected to a current setter 49 via a comparator 48, and the comparator 48 is connected to the central control unit 11@43.

Furthermore, since this embodiment is for holding the mold clamping force, the central control device 43 includes a clutch mechanism 38, a mold clamping force holder 391 position detector 50, an operation switch 51, and a back pressure control brake 31. Each of the back pressure control amplifiers 52 is connected, but the moving force of the screw 20, etc.
The corresponding control 2II equipment is connected.

Next, we will explain the detection of force during mold clamping force retention.
With the transmission shafts 32 and 34 connected by the clutch mechanism 38, the servo motor 35 is rotated forward.

The rotary disk 16 is rotated by the transmission shaft 34, the transmission gear 33, and the gear 17, and the screw shaft 15 is sent out. Here, the rotational motion is converted into a linear motion, the movable platen 13 moves forward and the molds 14, 14 engage.

When the movable platen 13 stops due to the mold closing, a large torque is generated and the current is pushed upward. At this time, a comparator 48 compares the detected current in the current setting device 49, which has a torque setting corresponding to the required torque, and the current detected in the current detector 47, and when a confirmation signal of coincidence is generated, the central control device 43 controls the mold clamping force retainer 39. is excited, and the transmission shaft 32 is fixed to the brake housing side. By fixing this transmission shaft 32, the movable platen 1
3 will maintain the mold clamping state.

Also, if this continues, rotational force will act on the transmission shaft 32, so
Following the excitation of the mold clamping force retainer 39, the clutch mechanism 38
is electrically opened to disconnect from the transmission shaft 34. The rotational force generated by the servo motor 35 is used for nozzle touching and injection.

Although the above embodiment deals with detecting mold clamping force in an injection molding machine, similar means can be used to detect nozzle touch force, injection pressure, and screw rotational force. Furthermore, the present invention is not limited to the above embodiments, as it can be used to detect force in compression molding machines, transfer molding machines, etc. in addition to injection molding machines.

〔Effect of the invention〕

As described above, this invention has a force transmission mechanism that includes an electric motor, a rotating member that converts the rotational motion of the electric motor into linear motion, and a screw member, and uses the transmission mechanism to convert rotational force into linear force. In an electric molding machine that converts the current into a servo motor and transmits it to a movable member to move or hold the movable member, the electric motor is a servo motor, and a current detector that detects the current flowing through the servo motor, and an output of the servo motor. The output detection device consists of a current setting device for checking the generation of torque, and a comparator that compares the detected current of the current detector and the setting current of the current setting device and generates a confirmation signal of coincidence. Since the current flowing through the motor is detected to detect the moving force or holding force of the movable members, even when an electric motor is used as the drive source, the amount of compression applied to each member and the amount of deformation of the movable members can be easily detected. Detection can be performed without being affected by the movement, and moving force and holding force can be controlled reliably and quickly. In addition, even if there are multiple movable members, detection can be performed with a single current detector by adjusting the set current to be compared depending on the stroke, and the device configuration is simple and centralized control can be easily implemented. It has features that are very suitable for detecting force in electric molding machines.

[Brief explanation of the drawing]

FIG. 1 is a partially longitudinal front view of an electric molding machine, and FIG. 2 is a block diagram of a control device used in carrying out the present invention. 1... Mold clamping mechanism, 2... Injection mechanism, 3... Machine base, 13... Movable platen, 15... Screw shaft,
32.34... Transmission shaft, 35... Servo motor, 35a... Tachometer generator, 38... Clutch mechanism, 39... Mold clamping force retainer, 4
3... Centralized control device, 41... Current detector, 48.
...Comparator, 49...Current setting device. Patent applicant Nissei Resin Industries Co., Ltd.

Claims (1)

[Claims] It has a force transmission mechanism including an electric motor, a rotating member that converts rotational motion by the electric motor into linear motion, and a screw member, and the transmission mechanism converts rotational force into linear force and transmits it to the movable member, In an electric molding machine that moves or holds the movable member, the electric motor is a servo motor, and a current detector for detecting the current flowing through the servo motor and a current setting for checking the generation of output torque of the servo motor are provided. 1. An output detection device for an electric molding machine, comprising: a current detector, and a comparator that compares the detected current of the current detector and the set current of the current setter and generates a signal confirming a match.