JPH04163018A - Controlling method for motorized injection molder - Google Patents

Abstract

PURPOSE:To prevent the backward movement of a screw before a plasticizing process from development and stabilize plasticizing state by a method wherein the controlling of the torque of an injection motor is performed so as to once lower the torque from the set value in the final stage of dwelling to the specified value at the process proceeding from a dwelling process to the plasticizing process and, after that, processed to the value of the back pressure in the plasticizing process. CONSTITUTION:Firstly, in a dwelling process A, an injection motor 1 is controlled by the torque command B of the injection motor 1 emitted from a first driver amplifier 17 on the basis of the set values, which are set in advance in a plurality of steps in a controlling device 16. When the dwelling process A terminates, the torque of the injection motor 1 is controlled so as to once fall from the set value E of the final stage of dwelling at the finish of dwelling in the dwelling process A to the torque value G just before plasticizing, which is lower than the set value E in the final stage of dwelling and, at the same time, 1-10% of the maximum value in the dwelling process, and then proceeded to the set value F in the first stage of plasticizing, which is the value of the back pressure in a plasticizing process C. Accordingly, the torque command B of the injection motor 1 does not come down to zero, resulting in allowing to prevent the backward movement of a screw before the plasticizing process C from occurring or restricting it as small as possible and the stabilize the plasticizing state.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention relates to a control method for an electric injection molding machine, and in particular, when transitioning from a pressure holding process to a plasticizing process, the torque command of the injection motor is This relates to a new improvement for stabilizing the plasticizing process by maintaining a certain torque value and preventing or minimizing the screw setback that occurs before the plasticizing process. There are various methods of controlling this type of electric injection molding machine that have been used in the past, but in the case of the commonly used method, as shown in FIG.
After completion of this step, the injection motor was started up from zero by giving a torque command to the injection motor, and the plasticizing step C was started.

(c) Problems to be Solved by the Invention Conventional control methods for electric injection molding machines have been configured in one or more ways, and have had the following problems.

In other words, after the pressure holding process is completed, the torque and speed commands of the injection motor are set to zero, so when the final stage setting of the pressure holding process is high, the residual amount of resin at the tip of the screw is compressed. Since the pushing force of the screw is zero, there is a serious problem in that the reaction force causes the screw to retreat several millimeters before the plasticization process begins, causing variations in the primary plasticization state. was. The present invention has been made to solve the above-mentioned problems. In particular, when transitioning from the holding pressure process to the plasticizing process, the torque command of the injection motor is zeroed from the holding pressure final stage setting value. Rather, once the torque is reduced to a certain value, that is, a value in the range of about 1 to 10% of the maximum value of the pressure holding process and lower than the final stage setting value of pressure holding,
After that, electric injection molding that stabilizes the plasticization process by controlling the back pressure to a value close to that of the plasticization process, thereby preventing or minimizing screw regression before the plasticization process. The purpose is to provide a method for controlling machines.

(d) Means for Solving the Problems The present invention provides a method for controlling the rotation of the injection motor 1 by a ball screw mechanism 11.
The screw 5 in the heating cylinder 2 is advanced to perform the injection process and the pressure holding process A, and the plasticizing motor 12 interlocked with the screw 5 is rotated. In a method for controlling an electric injection molding machine in which a plasticizing process C is performed in which resin is stored in a plasticizing process C, when transferring the torque command B of the injection motor 1 from the pressure holding process A to the plasticizing process C, The setting value E of the final stage of holding pressure in the holding pressure step A is lowered to a value lower than the final setting value E of holding pressure and 1 to 10% of the maximum value of the holding pressure step A, and then the back pressure of the plasticizing step C is lowered. The above problem is solved by shifting to the plasticization first stage set value F, which is a pressure value.

(E) Function In the control method for an electric injection molding machine according to the present invention, in the step of transitioning from the pressure holding process to the plasticizing process, the torque control of the injection motor is changed from the setting value of the final stage of holding pressure to the holding pressure stage once. The screw retreat that occurs before the plasticizing process is reduced by reducing the torque to a torque value that is 1 to 10 degrees from the maximum value and lower than the holding pressure final stage set value, and then shifting to the back pressure value for the plasticizing process. By preventing this and stabilizing the plasticized state, a stable molded product can be obtained.

(F) Embodiments Hereinafter, preferred embodiments of the control method for an electric injection molding machine according to the present invention will be described in detail with reference to the drawings.

In addition, the same reference numerals are attached to the same or equivalent parts as in the conventional art and the explanation will be given.

1 and 2 are a cross-sectional block diagram and a torque command characteristic diagram showing a control method for an electric injection molding machine according to the present invention.

What is indicated by the reference numeral 2' in the figure is a heating cylinder of an electric injection molding machine 3, and this heating cylinder 2 has a nozzle hole 2a at its tip and a guide hole 2b formed in the axial direction. is arranged such that a screw 5 having a connecting rod 4 can rotate and move in the axial direction.

The connecting rod 4 is connected to a cylindrical drive shaft 4A having a U-shaped cross section, and the drive shaft 4A is connected to a ball nut 7 via a thrust bearing 6. A gear 8 is integrally fitted to the ball nut 7.
A ball torsion is provided therein to be screwed together, and the output shaft 10 of the injection motor 1 is connected to one end of the second ball torsion. The ball screw mechanism 11 is formed into an ellipse by the ball screw 7 and the ball screw 9, and the ball screw mechanism 11 is rotated by rotating the output shaft 10 of the injection motor 1.
- The drive shaft 4A and the screw 5 can be moved in the axial direction through the door.

The rotating shaft 13 of the plasticizing motor 12 attached to the injection motor 1 is secured to a ball spline 14, and a flanged gear 15 is attached to the outer periphery of the ball spline 14 and has a pair of flanges 15a. The gear 8 is meshed with the drive shaft 4A, and the rotation of the rotation shaft 13 can rotate the drive shaft 4A.

The detection signal of the injection motor encoder IA provided on the front g% injection motor 1 is input to the control device 16, and the detection signal of the plasticization motor encoder 12A provided on the plasticization motor 12 is inputted to the control device 16. The signal is input to the M control device 16.

Said control device! The control signal from 16 is sent to the injection motor 1 and the plasticizing motor as a speed command H1 for the injection process and a torque command B and speed command for the pressure holding process via the first driver amplifier 17 and the second driver amplifier 18. 12
are applied to each.

The method for controlling an electric injection molding machine according to the present invention is configured as described above, and its operation will be explained below.

First, in the pressure holding step A, the first injection motor 1 is
The injection motor 1 is controlled by the torque command B from the driver amplifier 17.

When the above-mentioned holding pressure step A is completed, as shown in FIG. The torque value G immediately before plasticization is set to a value of 1 to 10% of the maximum value, and then the control is performed to shift to the plasticization first stage set value F, which is the back pressure value of the plasticization step C. Therefore,
The torque command B of the injection motor 1 does not become zero, and the screw retreat that occurs before the plasticizing process C can be prevented or minimized, and the plasticizing state can be stabilized.

The torque value G immediately before plasticization at the time of transition to the plasticization step C of this method may be automatically calculated and set by the pressure holding final stage setting value E, or may be set by the operator. ) As described in detail, the method for controlling an electric injection molding machine according to the present invention is configured as described above, so that the following effects can be obtained.

That is, in the process of transitioning from the pressure holding process to the plasticization process, the torque iw control of the injection motor is changed from the pressure holding final stage setting value to a torque value lower than the pressure holding final stage setting value and 1 of the pressure holding process maximum value. By lowering the angle to a value of ~109°, the torque command of the injection motor does not become zero before the plasticizing process, thereby preventing the screw from retreating before the plasticizing process and stabilizing the plasticizing state. This makes it possible to obtain a more stable molded product.

[Brief explanation of drawings]

Figures 1 and 2 are for showing the control method of an electric injection molding machine according to the present invention. Figure 1 is a block diagram with a cross section, Figure 2 is a torque command characteristic diagram, and Figure 3 is a conventional control method. Torque command characteristic diagram 1... Injection motor, 2... Heating cylinder, A... Pressure holding process, B... Torque command, C
...Plasticization process, E...Pressure final stage setting value, F.
・Plasticization first stage set value, G...Torque value immediately before plasticization, 5...Screw, 11...Ball screw mechanism, 12...Motor for plasticization. Figure 3

Claims (1)

[Claims] The rotation of the injection motor (1) is converted into linear motion via a ball screw mechanism (11), and the rotation of the injection motor (1) is
5) to perform the injection process and the pressure holding process (A), and the plasticizing motor (12) interlocked with the screw (5).
), the control method for an electric injection molding machine performs a plasticizing step (C) of accumulating resin in the heating cylinder (2) by rotating the injection motor (1), the torque command (B) of the injection motor (1) ) from the pressure holding process (A) to the plasticizing process (C), the pressure final stage setting value (E) in the pressure holding process (A) is changed once to the pressure holding final stage setting value (E). ) lower and to 1 to 10% of the maximum value in the holding pressure step (A), and then
A method for controlling an electric injection molding machine, characterized in that the pressure is shifted to a first stage plasticization set value (F), which is a back pressure value in the plasticization step (C).