JPH0246145B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an injection molding machine, and particularly to an injection molding machine using a servo motor as a drive source.

Prior Art Most conventional injection molding machines use a hydraulic drive source, and speed control, position control, pressure control, etc. are controlled using a limit switch or the like based on signals from the limit switch. In addition, since position control is the basis of speed control and pressure control, some systems used optical or magnetic linear scales to perform position control.

On the other hand, injection molding machines that use servo motors as drive sources have also been developed, but in injection molding machines that use servo motors, various mechanisms such as the mold clamping mechanism and injection mechanism are driven by the servo motors. It is necessary to establish the coordinate position of That is, it is necessary to determine the origin of each mechanism and to control not only the position but also the speed and pressure depending on the current position of each mechanism from the origin. Therefore, the servo motor that drives each mechanism is provided with a position detection path, which detects the current position of each mechanism. However, the position detector normally attached to the servo motor is an incremental type position detector. Therefore, in this incremental position detector, when the injection molding machine is powered on, it is necessary to perform a return-to-origin operation to determine the origin of each mechanism of the injection molding machine. In this return-to-origin operation, each mechanism is first manually moved to a position where the return-to-origin operation can be started, and then a command to start the return-to-origin operation is input. The servo motors of each mechanism are driven in rapid traverse, each mechanism is operated, and when the deceleration dog etc. turns on the limit switch, the servo motors are driven at low speed from then on, and the position detector is moved to the predetermined position.
That is, the servo motor is stopped at the origin position, and positioning to the origin is completed. The incremental position detector is inconvenient because the above-described return-to-origin operation must be performed every time the injection molding machine is powered on.

Furthermore, in the mold clamping mechanism, if the mold has three plates, links are provided between the molds.
In cases where the mold cannot be opened beyond a certain level,
In some cases, it was not possible to return to the origin due to the thickness of the mold, and it was necessary to remove the mold from the mold clamping mechanism in order to return to the origin. In addition, the injection mechanism has the disadvantage that it can only return to its origin after the heating cylinder has been sufficiently heated, and in the case of the ejector position,
A drawback was that the mold clamping mechanism could not be returned to the origin unless it was in a specific position. Furthermore, during the return to the origin, the servo motor rotates at high speed as described above, which causes each mechanism to be driven at high speed, which is dangerous.

Problems to be Solved by the Invention The present invention improves the drawbacks of the prior art described above, and
An object of the present invention is to provide an injection molding machine in which each mechanism is driven by a servo motor, which does not require a return-to-origin operation.

Means to solve the problem An absolute value pulse encoder is installed in the servo motor that drives the injection molding machine, which counts the pulses generated every time the servo motor rotates by a predetermined amount, and detects the absolute position based on the counted value. Install it so that the current position of a mechanism driven by a servo motor can be detected at all times.

Function: The current position of the mechanism driven by the servo motor is always detected by the absolute value pulse encoder, regardless of whether the injection molding machine is powered on or not. The injection molding machine can be started immediately without any additional steps.

Embodiment The figure is a main part block diagram of an embodiment of the present invention.
10 is a numerical control device with a built-in computer (hereinafter referred to as NC), and 10 is a microcomputer (hereinafter referred to as NC).
11 is a ROM that stores the control program that controls the entire injection molding machine, 12 is a RAM used for temporary storage of data, etc., and 13 is a non-volatile memory that stores various setting values. be. Reference numeral 14 denotes a manual input device for inputting various setting values such as molding conditions and various commands. 15
is an input/output circuit connected to the CRT unit 5. 16 is also an input/output circuit, and is connected to each servo circuit that drives and controls the servo motors for the injection mechanism, mold clamping mechanism, ejector device, metering, mold thickness adjustment, and nozzle touch of the injection molding machine. In the figure, only one servo motor 2 and servo circuit 4 are shown. 3 is an absolute value pulse encoder attached to the servo motor 2, which counts the pulses generated every time the servo motor 2 rotates by a predetermined amount, and detects the absolute position based on the counted value. Since a battery is built-in, the absolute value pulse encoder 3 is in operation even when the injection molding machine is not powered on, and even if the servo motor 2 is moved by an external force etc. during that time, the absolute value pulse encoder 3 remains in operation. The position of the servo motor 2, that is, the injection mechanism and mold clamping mechanism driven by the servo motor 2, is detected by detecting the amount of movement thereof. Then, when the power is turned on, the servo motor 2 detected by the absolute value pulse encoder 3
The current position of is sent to the counter 17 of NC1, and the current position is detected by the counter 17. The absolute value pulse encoder 3 and counter 17 are provided for each servo motor.
Further, 18 is a bus.

Next, the operation of this embodiment will be described.

First, when the assembly of the injection molding machine is completed or when it becomes necessary to reset the origin due to a problem, etc., drive the servo motor 2 by manual feed etc. to move it to the machine origin position, and at this machine origin position, the manual input device Input the origin instruction from 14. Upon receiving this origin command input, the CPU 10 causes the nonvolatile memory unit 13 to store the value of the counter 17, that is, the value of the absolute value pulse encoder 3 that detects the current position of the machine driven by the servo motor, as the origin position. In this way, when the origin position of each servo motor, that is, the origin position of the mechanism driven by each servo motor is stored in the nonvolatile memory 13, there is no need to perform a return-to-origin operation from now on. That is, when the power is turned on to the injection molding machine, the current position of the servo motor 2 is detected by the absolute value pulse encoder 3, so the value of this absolute value pulse encoder 3 is sent to the counter 17, and the CPU 10 of the NC1 is non-volatile. The current position of the servo motor 2 is detected from the origin position stored in the digital memory 13 and the value of the counter 17.
Therefore, when the power is turned on, the injection molding machine can immediately start the molding operation without performing a return-to-origin operation.

Effects of the Invention As described above, in the present invention, since the current position of each part of the injection molding machine controlled by NC is always detected, the injection molding machine can be driven immediately after turning on the power without performing a return to the origin. This greatly improves the ease of use of the injection molding machine.

[Brief explanation of the drawing]

The figure is a block diagram of essential parts of an embodiment of the present invention. 1... Numerical control device.

Claims (1)

[Claims] 1. In an injection molding machine that uses a servo motor as at least one of the driving sources for driving each mechanism of the injection molding machine, the pulses generated in the servo motor each time the servo motor rotates by a predetermined amount are counted, and the pulses are calculated. An absolute value pulse coder with a built-in battery that detects the absolute position by numerical values is installed, and a nonvolatile memory section is provided to store the count value of the absolute value pulse coder when the mechanism driven by the servo motor is positioned at the origin. , an injection driven by a servo motor with an absolute value pulse encoder that can always detect the current position of the mechanism driven by the servo motor from the counted value stored in the storage unit and the counted value detected by the absolute value pulse coder. Molding machine.