JPH0229486B2 - SHASHUTSUSOCHINONOZURUTATSUCHIHOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for causing an injection device to touch a nozzle to a mold of a mold clamping device using an electric motor as a drive source.

(Prior Art) A method of touching a nozzle of an injection device to a mold using an electric motor is already known from Japanese Patent Laid-Open No. 59-2827. In this conventional method, the rotational force of the electric motor is transmitted to the screw shaft via the clutch mechanism and rotation means, and the nozzle touch is performed using the thrust of the screw shaft.The nozzle touch force is maintained by the injection device and the transmission. This is done by utilizing the elastic force of each member that makes up the mechanism.

(Problems to be Solved by the Invention) In the above conventional method, the nozzle touch force is maintained by using the elastic force of the mechanical parts, which are originally rigid bodies (the amount of strain against stress is small), so the thermal expansion of each mechanical part, In addition, the nozzle touch force changes due to thermal expansion of the heating tube, making it difficult to control the force accurately, and in some cases, resin may leak from the nozzle touch surface, or mechanical parts may be deformed or damaged. This was becoming a problem.

(Means for Solving the Problems) The present invention has been made in view of the above circumstances, and its purpose is to prevent the deformation of the constituent members from deforming and to reduce the The object of the present invention is to provide a new method that can maintain nozzle touch force.

This invention for the above purpose converts the rotational force of an electric motor into a thrust force for moving an injection device using a transmission mechanism consisting of a feed piece and a screw shaft that are screwed together, and the thrust force is used to move the injection device. In the method of touching the nozzle to the mold, the transmission mechanism is provided with a spring member that is compressed by the feeding piece and presses the injection device against the mold, and a timer that detects the position of the injection device immediately before the nozzle touch and stops the electric motor. The spring member is compressed by the feed piece that moves after the nozzle is touched until the motor stops when the timer finishes counting.
The above-mentioned conventional problems are solved by maintaining the nozzle touch force after the electric motor is stopped using the elastic force of the spring member.

This will be explained in detail with reference to illustrated embodiments.

(Example) In the figure, 1 is an injection device installed on a machine base 2 so as to be able to move forward and backward, 3 is a mold clamping mechanism, and a fixed platen 4 installed on the machine base in front of the injection device 1; A split mold 7 is attached to a movable platen 6 which is slidably provided on tie bars 5, 5 which are horizontally suspended.

8 is an electric motor, and 9 is a transmission mechanism that converts the rotational force of the electric motor 8 into thrust of the injection device 1.

The transmission mechanism 9 is configured to convert the rotational force of the electric motor 8 into thrust using a screw shaft 10 rotated by the electric motor 8 and a nut-shaped feed piece 11 screwed onto the screw shaft 10.

The screw shaft 10 is integrally formed at the tip of a rotating shaft 12 horizontally suspended in the lower part of the injection device 1, and the rotating shaft 12 is connected to a drive shaft 14 of an electric motor 8 attached to the rear wall of the injection device 1. be. Further, the screw shaft 10 is inserted into a casing 15 provided at the lower part of the fixed plate 4 and a through hole 16 bored in the fixed plate inside the casing, and the feed piece 11 is inserted into the casing 15.
It is fixed and housed in the fixed platen 4 using a pin 17 so that it can move only in the axial direction.

A disc spring 18 is provided between the feed piece 11 and the casing side wall 15a to press the feed piece 11 against the fixed platen 4.

Reference numeral 19 denotes a position detector of the injection device 1 using a proximity switch, which is activated by a dog 20 protruding from the injection device side, and is a timer that limits the rotation time of the electric motor 8 after the nozzle of the injection device 1 touches the mold 7. Emit a timing start signal.

28 is a brake for braking the rotating shaft 12;
A non-excited spring brake is shown.

FIG. 2 shows an example of a control circuit for the electric motor 8, in which the position detector 19 is connected to the controller 21 and the electric motor drive device 22, and the motor stop relay 3 is connected to the motor stop relay 3.
The nozzle advance command circuit 23 and the nozzle retreat command circuit 25 are provided with an OR logic circuit 26 and a brake release drive circuit. 27, a brake circuit 29 with a brake 28 is connected. Note that a b contact 31b of a brake command relay 31 is provided between the nozzle advance command circuit 23 and the OR logic circuit 26.

The controller 21 also has a timer 24 a.
Contact 24a and brake command relay drive circuit 30,
A circuit having a brake command relay 31 is connected thereto, and a circuit having a motor stop timing circuit 32, a motor stop relay drive circuit 33, and a motor stop relay 34 are connected to this circuit.

Note that 35 is a retraction limit switch of the injection device 1.

Next, a nozzle touch method using the above device will be explained.

When a nozzle advance command signal is applied from the controller 21 to the nozzle advance command circuit 23, the signal is applied to the electric motor drive device 22 via the b contact 34b of the motor stop relay 34 to operate the electric motor 8. At the same time, the above signal is also given from the nozzle advance circuit 23 to the brake circuit 29, and the signal is given to the OR logic circuit 26 and the brake release drive circuit 27 via the b contact 31b of the brake command relay 31, which excites the brake 28. Release the rotating shaft 12.

When the rotating shaft 12 rotates as described above, the pin 17
The screw shaft 10 moves forward (leftward in the drawing) by the feed piece 11 which is fixed to the stationary platen 4 by the disc spring 18 and the injection device 1 moves in the same way.

When the injection device 1 moves forward and reaches just before the nozzle touch position, the dog 20 activates the proximity switch 19 and the timer 24 starts timing.

The injection device 1 continues to move forward as the timer 24 measures time, and the nozzle touches the mold 7. After that, the electric motor 8 continues to rotate, but no further movement occurs, so when the feed piece 11 is pulled back against the disc spring 18 and returned to the midpoint of the movable stroke of the disc spring 18, When the timer 24 finishes counting, the a contact 24a of the timer 24 becomes conductive, the brake command relay drive circuit 30 and the brake command relay 31 operate, and the b contact 31b of the brake command relay is disconnected, so the brake release drive circuit 2
7 is cut off, the brake 28 is demagnetized and the rotating shaft 12 is braked, and after a certain timing due to the action of the motor stop timing circuit 32, the motor stop relay drive circuit is activated and the motor stop relay is activated. As a result, the b contact 34b of the motor stop relay 34 is cut off, and the nozzle advance command circuit 23 is cut off, so the motor drive device 22 is cut off and the motor 8
stops.

As described above, the nozzle touch force is maintained by the resiliency of the disc spring 18. Further, a force is generated by the disc spring 18 to push back the injection device 1, but since the rotating shaft is held by the brake 28, the rotation does not reverse.

After the injection process is completed, when a signal is given from the controller 21 to the nozzle retraction command circuit 25, the brake circuit 29 is activated and the brake 28 is energized to release the rotating shaft in the same manner as described above, and the motor drive device 22 is activated. The motor rotates in the opposite direction when moving forward.

As a result, the rotating shaft 12 is also rotated in the reverse direction, so that the feeding piece 11 is returned by the disc spring 18 and comes into contact with the stationary platen 4, and thereafter the injection device 1 moves backward (upward in the right direction in the drawing) together with the rotating shaft 12.

When the injection device 1 reaches the retraction limit position and the retraction limit switch 35 is activated, the nozzle retraction command circuit is cut off and the electric motor is stopped.

In this embodiment, the force of the disc spring 18 to push back the injection device 1 was held by the brake 28;
If the screw lead angle of the screw shaft 10 is 5 degrees or less, the screw shaft 10 will not rotate in the opposite direction due to screw resistance, and the injection device 1 will be fixed in that position, so there is no need to apply a brake. .

(Effects of the Invention) As described above, in this invention, even after the nozzle of the injection device is touched to the injection mold, the rotation of the electric motor is continued within the range measured by the timer. Compress the parts,
The elastic force of the spring member allows the nozzle touch force to be maintained even when the electric motor is stopped, so it is possible to save energy by stopping the electric motor until the injection process is completed.

In addition, undue external force on the nozzle touch part caused by thermal expansion of various parts during the injection process can be absorbed within the range of the amount of deflection of the spring member, so deformation, damage, etc. of the nozzle touch part are prevented, and resin leakage does not occur.

Furthermore, since the position of the injection device immediately before the nozzle touch is detected and the timer that stops the motor starts counting, the timer is kept to the minimum necessary and the motor stop time after the nozzle touch is fixed regardless of the nozzle touch stroke. Since you can set
Not only is the setting easy, but the nozzle touch can be maintained under appropriate spring pressure.

[Brief explanation of drawings]

The drawings illustrate an apparatus capable of carrying out the present invention, and FIG. 1 is a partially longitudinal side view of an injection molding machine, and FIG. 2 is a control circuit diagram. DESCRIPTION OF SYMBOLS 1... Injection device, 8... Electric motor, 9... Transmission mechanism, 10... Screw shaft, 11... Feed piece, 18...
Belleville spring, 19...Position detector.

Claims (1)

[Claims] 1. A method in which the rotational force of an electric motor is converted into a thrust force for moving an injection device by a transmission mechanism consisting of a feed piece and a screw shaft that are screwed together, and the nozzle touch of the injection device to an injection mold is performed using the thrust force. The transmission mechanism is provided with a spring member that is compressed to press the injection device against the mold, detects the position of the injection device immediately before the nozzle touch, starts a timer to stop the electric motor, and ends the timer. A nozzle touch of an injection device characterized in that a spring member is compressed by the above-mentioned feeding piece that moves after the nozzle touch until the electric motor stops, and the nozzle touch force after the electric motor stops is maintained by the elastic force of the spring member. Method.