JPS60108153A - Method for controlling injection speed - Google Patents

Abstract

PURPOSE:To make control simple, operation easy and device inexpensive by controlling injection speeds by using the injection speed, injection stroke position and patterns for changing the injection speed which can be selected. CONSTITUTION:A low injection speed V1 is adequately and preliminarily set prior to injection by a setter 14. The position C for changing the low-speed injection to high-speed injection is adequately selected by a setter 15 for the position for changing over to a high injection speed. Either of rising patterns I , II for the low injection speed is selected and commanded by a comander 16 and a high injection speed V4 is set by a setter 17. The time T required until the point B for changing the injection speed from the point A for changing over to the high- speed injection is attained is set by a timer 18 for changing the injection speed at the terminal end of the high-speed injection. Either pattern of patterns III, IVfor increasing and decreasing the speed is selected and commanded by a commander 19 for the pattern for increasing and decreasing the injection speed at the terminal part of the high-speed injection.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an injection speed control method in an injection molding apparatus such as a die casting machine or an injection molding machine.

[Prior art]

FIG. 1 is a block diagram of an injection cylinder and an injection speed control device of a die-casting machine that can be considered as a 46-inch die-casting machine. In the figure, an injection plunger 4 is connected to a piston rod 2 of an injection cylinder 1 via a coupling 3, and an injection sleeve 5 is attached to the tip of the injection plunger 4.
A plunger tip 6 sliding inside is fixed. When the plunger tip 6 is pushed within the injection sleeve 5 by the movement of the piston rod 2, the molten metal is injected into a not-shown metal hood. Further, a striker I is connected to the coupling 3, and the striker 7 sequentially turns on a plurality of limit switches 8a to 8e.
I'm trying to turn it off.

A limit switch 8a is provided at the retracting limit position of the piston rod 2, a limit switch 8b is located at position 6, and a limit switch 8c is located at position 6, where the low-speed injection is made even slower just before the molten metal to be injected reaches the gate of a mold (not shown).
is the position where a part of the molten metal passes through the gate of the mold and slightly enters the mold cavity and switches from low-speed injection to medium-high speed injection,
The limit switches 8d are provided at positions where the molten metal enters the mold cavity and the injection is switched from medium to high speed injection to high speed injection, and the limit switch 8e is provided at the forward movement limit position of the piston/rod 2.

On the other hand, the output signals of the limit switches 8a to 8e are input to a signal detector 9, and the output signals of this signal detector 9 are input to a control signal generator 10. control (nil signal generator 1
0, it is detected on the basis of this input signal whether the injection stroke of the injection plunger 4 has reached the point at which the injection speed changes. When the injection stroke reaches the injection speed change point, an analog signal corresponding to the target injection speed preset in the speed setting device 11 is sent from the control signal generator 10 to the hydraulically driven servo pulp 12. Ru. The servo pulp 12 is connected to the injection cylinder 1 by a hydraulic circuit 13, and its opening degree is controlled according to the input analog signal.
The amount of liquid introduced into the injection cylinder 1 is adjusted, and the moving speed of the injection plunger 4 connected to the piston rod 2 in the injection cylinder 1 is controlled.

That is, the injection speed is controlled to the target speed by the control signal sent at each change point.

FIG. 2 is a graph showing an example of an injection speed pattern that changes due to such control. The horizontal axis represents the stroke of the injection plunger, and the vertical axis represents the injection speed. Point a is a state in which the piston rod 2 to which the injection plunger 4 is connected is at the backward limit position, and at this time, all the limit switches 8 & - 8e are on. Then, as the injection plunger 4 moves forward, the switches 88 to 8
d is turned off sequentially. Here, first, injection plunger 4
is changed toward the target speed VIK, and in the low speed region in the first half of the stroke, this injection speed is maintained to fill the injection sleep with molten metal. Eventually, the limit switch 8 is activated at point b, just before the molten metal approaches the gate of the mold (not shown).
When b is turned off, the injection speed temporarily drops to v2, the gas entrainment of the molten metal is suppressed as much as possible, and the limit switch 8c is turned off at the 0 point when a part of the molten metal has entered the mold cavity. Then, the injection speed changes towards v3, and the molten metal enters the mold cavity,
When the limit switch 8d is turned off at point d, where there is almost no entrainment of gas in the molten metal even if the injection speed is extremely increased, the injection speed will rise to v4, and then rise to v4. Injection is performed while maintaining a high injection speed. When the cavity of the mold is sufficiently filled with the molten metal and the injection plunger 4 stops moving forward, the injection is completed.

The injection completion position is point f. Thereafter, once the injected molten metal has solidified and cooled, the injection plunger 4 also moves forward somewhat in accordance with the mold opening speed of the movable mold (not shown). and,
When the limit switch 8e is turned off at the forward limit of the injection plunger 4, the injection plunger 4 is moved backward. Of course, if more points are provided to change the injection speed during injection, a correspondingly larger number of limit switches will be required.

Furthermore, instead of providing a large number of limit switches, a Magnescale can be used to continuously detect the stroke position.

However, with such conventional devices, it is necessary to arrange a large number of limit switches and provide a magnetic scale as detection means to generate stroke position signals, making the device expensive and requiring a large number of individual limit switches. This method has the disadvantage that it is difficult and troublesome to set changes, and therefore workers on site are not happy with it.

[Object and structure of the invention]

The present invention has been made to solve these conventional drawbacks, and its purpose is to provide simple stroke position command means, speed command means, and injection speed change control that can be selected as appropriate. An object of the present invention is to provide an injection speed control method that can easily control the injection speed in a certain degree of pattern using the following method.

In order to achieve such an object, the present invention provides a low injection speed in a low speed range, an injection stroke position of a switching point from a low speed range to a high speed range, and 2 inputs previously input into the injection speed control device. Control is performed by commanding a low-speed rise pattern selected from one or more of nine consecutive low-speed patterns. A speed change pattern that is selected from an increasing pattern that tends to further increase the injection speed and a decreasing pattern that tends to decrease the injection speed in the latter half of the high-speed region where the injection speed has been maintained, and a starting point of the speed changing pattern are commanded. It was designed to be controlled by

〔Example〕

Hereinafter, the present invention will be explained in detail based on examples.

FIG. 3 is a configuration diagram of an injection speed control device to which an embodiment of the present invention is applied, and FIG. 4 is a cross-sectional structural diagram of its flow rate control valve.
FIG. 5 is a graph showing the pattern of injection speed. In the figure, the same parts as in FIG. 1.2 are given the same reference numerals.

In Figure 3, the striker T includes Magnescale T &
is installed. Reference numeral 7b is a magnetic head, and the moving position of the injection plunger 4 is inputted to the calculator 34 every moment by the movement of the magnet scale 7a and the action of the magnetic head rb.

14 is a low injection speed setting device, and 15 is a high injection speed switching position setting device for setting a switching position C from low injection speed vl to high injection speed v4. Therefore, the fifth
Point A in the figure is determined by the switching position C and the low injection speed v1. Note that when using the striker T and the limit switch 8c for commanding high speed switching without using the magnetscale 7a and the magnetic head 7b, the limit switch 8C
becomes a switch position C setting device for switching to high-speed injection speed v4.

Reference numeral 16 denotes a low-speed injection start-up turn command device which, at the start of injection, controls the low-speed injection start-up turn from when the injection speed starts from O until it reaches the low speed injection speed v1 in a comparative manner as shown by the solid line in FIG. The command is given by appropriately selecting either pattern I, which is a rapid rising state, or pattern (2), which is a relatively gradual force rising state, as shown by the two-dot chain line. Therefore, the trajectory of the curve from the start of injection to point A in FIG. .Of course, this low-speed injection start-up thick turn is not limited to two, and three or more may be provided.However,
Even if you provide a lot of slack, the devices will only come close to each other, and you will not be able to get a start-up state that is quite different from each other.
It is practical to use two or three patterns. Note that it is also possible to limit the number of turns to one (this pattern seems to be used most often) from the beginning.

17 is a high-speed injection speed setting device sb, which determines the high-speed injection speed (4). In addition, it is generally said that the steeper the start-up condition from low injection speed to high injection speed, the better the flow of the molten metal in the mold, and the better the injection product can be produced. , pulse motor 2 to be described later
The maximum rotational speed of 0 is always commanded, and the high-speed injection speed start-up turn is not changed.

Therefore, once the point A and the high injection speed v4 are determined,
Once the high injection speed is reached, the point will be determined by itself.

Of course, as shown in Figure 5, this high-speed injection speed start-up nine turns has an increasing speed characteristic where the speed increases smoothly at point A, and a decreasing acceleration where the speed smoothly stabilizes at a constant level at point A. If you want to create a pattern in which the characteristics are 9 and the high injection speed 4 can be reached as quickly as possible, control is performed by issuing a signal every time.

At the point near the end of high-speed injection, select either pattern 0, which instructs to further increase the injection speed, as shown by the solid line in Figure 5, or pattern ■, which lowers the injection speed, as shown by the two-dot chain line. That's how it is. 1B is the time T from when the injection set stroke reaches the point A until it reaches the point No. 1, which is the starting point of the speed change pattern, for example, 50
This is a timer that can be selected from ~80rnaec and set in advance. Note that the time T until reaching point C may be measured from the point of entry. In some cases, the stroke g may be used to indicate the point C. In any case, when point C is reached, a command is given to control the injection speed using pattern 1 or pattern 2.

Reference numeral 19 is an injection speed increase/decrease pattern command device at the end of high-speed injection.
It makes a choice and gives an instruction.

If you want to obtain an injection product that is dense and free of cavities, even if some particles are wiped off during injection, select pattern I.
If you want to obtain an injection product in which there may be some nests, but the bubbles do not blow up during injection and you do not want to perform post-processes such as removing the bubbles, select pattern ①. In the case of pattern I, the maximum injection speed v5 at the final point is set in advance to be, for example, 20% higher than the high-speed injection speed v4, and in the case of pattern ■, the injection speed after deceleration at the final point ■6 is , for example, is predetermined to be one-half of the high-speed injection speed v4. Of course, these increase/decrease ratios can be set to be constant at all times, or can be adjusted as appropriate.

Low speed injection speed setter 14. Position setting device for switching to high injection speed 15. Low speed injection start-up turn command device 16. High-speed injection speed setting device 17. Timer 18 for changing the injection speed at the end of high-speed injection. The electric signal from the injection speed increase/decrease pattern command unit 19 at the high-speed injection end portion is input to the arithmetic unit 34. Based on these input signals and the signal input from the magnetic head 7b, the computing unit 34 appropriately controls a signal for requesting speed control to obtain a predetermined injection speed at a predetermined point. output to the pulse generator 35,
Based on the signal, the control pulse generator 35 appropriately outputs a pulse signal for controlling the injection plunger 4 to a preset target speed. This pulse signal is
The number of pulses and the pulse period are determined by the speed difference and the time required to reach the target injection speed. The pulse motor 20 rotates by a rotation amount proportional to the number of input pulses and at a speed inversely proportional to the period. This rotation changes the opening degree of the flow control pulp 21, and the moving speed of the injection pump 2/jar, that is, the injection speed is controlled according to the opening degree. The setting devices 14, 15, 17, command devices 16, 19, etc. are provided on a control panel or the like.

The flow control pulp 21 is constructed as shown in FIG. 4, and the pulp body 22 is formed with a hydraulic oil inlet 23 from the axial direction and a hydraulic oil outlet 24 perpendicular to the axis. A spool 25 that moves in the axial direction is housed in the spool 25 . A nut shaft 26 is integrally formed at the rear of the spool 25, and a screw shaft 27 is mated to the inner shaft center of the nut shaft 26 via a ball screw 28, and this screw shaft 27 is connected to a joint 29. is connected to the shaft of the pulse motor 2Q.

Note that 3θ is a key that prevents rotation of the nut shaft 26 and guides its movement in the axial direction, 31 is a permanent magnet provided on the nut shaft 26, 32 is an opposing casing, and 33 is a permanent magnet 31 provided on the opposing casing 32. This is a position detector facing the

When the pulse motor 20 rotates, the spool 25 moves back and forth in the axial direction in response to this rotation, instantaneously opening and closing the pulp and adjusting the opening degree to control the flow rate. That is, this flow rate control pulp 21 is configured such that the spool 25 is moved along the axis by the action of the pulse motor 20 within a cylindrical pulp body 22 that has a hydraulic oil inlet 23 at the end surface in the axial direction and a hydraulic oil outlet 24 at the side surface. (by rapidly reducing the axial thrust of the spool 25 caused by the hydraulic oil in accordance with the opening 11 of the spool 25 and the increase in the moving speed), the flow rate can be switched at high speed. This reduces the amount of driving force required. Therefore, the high-speed switching performance of the flow rate by the flow rate control pulp 21 is greatly improved, and the driving force is reduced.

In this flow control pulp 21, the amount of rotation, that is, the rotation angle of the pulse motor 20 is determined by the control pulse from the control pulse generator 35, and this rotation angle determines the rotation amount of the pulse motor 20.
5 is determined, and the flow rate to the injection cylinder 1 is controlled by this opening amount. Further, the rate of change of the flow rate, that is, the start-up state of the injection speed is determined by the magnitude of the rotational speed of the pulse motor 20.

With the flow rate control valve 21 having such a structure, it is possible to reduce the time from receiving a speed change command until the spool 25 actually starts opening to less than 1 millisecond at maximum, which is faster than a normal flow rate control valve. The responsiveness is extremely good, and the operability and operational precision of opening and closing the pulp are also improved.

Furthermore, since the position detector 33 constitutes a proximity switch that is sensitive to the movement of the permanent magnet 31, it is possible to detect the moving distance of the nut 11U126 and the spool 25 and feed it back to the control device. Further, the zero position of the spool 25 can be detected by this proximity switch and the pulse motor 20 can be accurately stopped at that position via the control pulse generator 35.

In this embodiment, such a pulse motor-driven flow control valve made of 414 is used, so that the inertia is small, the response is good, and the control can be performed reliably and easily. ! Also, it is possible to suppress the increase in spool thrust force.

Next, the operation of this embodiment will be explained with reference to FIG.

First, before performing injection, the low-speed injection speed V is appropriately set in advance using the low-speed injection speed setting device 14, and the switching position C from low-speed injection to high-speed injection is appropriately set using the high-speed injection speed switching position setting device 15. set, select one of the low-speed injection start-up patterns 1.1 with the low-speed injection rise pattern command device 16, set the high-speed injection speed v4 with the high-speed injection speed setting device 17, and select the high-speed injection start-up pattern command 1.1. The time T required for the FC from point A of switching to high-speed injection to point C of changing injection speed is set using the injection speed change timer 18 at A selection command is given to one of the speed increase/decrease patterns I and ff.

When a start signal (not shown) is input to the control pulse generator 35, a pulse output is sent to the pulse motor 20 to increase the injection speed to V in a predetermined pattern in accordance with the command information. As a result, the flow rate control valve 21
opens by a predetermined amount at a predetermined speed, and the injection plunger 4 accelerates to a speed corresponding to vl and then moves while maintaining that speed. Eventually, when point A is reached, the control pulse generator 35 changes the injection speed to v4 in a predetermined pattern according to the information stored in the calculator 34 based on the detection signal at the time of stroke C.
A pulse output is sent to the pulse motor 20 to increase the temperature. As a result, the flow control wholesale pulp 21 opens by a predetermined amount at a predetermined speed, and the injection plunger 4 accelerates to a speed corresponding to v4. Then, when a certain period of time i', 1 lilT (for example, 50.-80 milliseconds) has elapsed from the point of passing point A, the control pulse generator 35 sends a pulse output to the pulse generator 20, and the same The flow control valve 21 opens and the injection speed rapidly increases to v5 in a predetermined pattern or decelerates to v6 in a predetermined pattern. After the injection is completed, the injection plunger 4 moves forward according to the mold opening operation, and when the injection plunger 4 reaches its forward limit, a pulse output is sent from the control pulse generator 35 to reverse the pulse motor 20, and the flow rate control valve 21
is rapidly closed and the injection plunger 4 is retracted by normal hydraulic pump operation.

In this way, each setting device
Signals are sent from 4.15.17, command unit 16.19, etc.

According to such a control method, a simple means for detecting the position of the injection plunger 4 and the piston rod 2 during the movement stroke is sufficient, and even when a limit switch is used for the cylinder, there is only a limit switch as far as the backward movement and a limit switch as far as the forward movement. In addition to the switch, it is only necessary to use one limit switch set at the switching position from low speed to high speed, and the timing of the shift point in the high speed range is obtained by the passage of a certain period of time from the switching point to high speed. Therefore, there is no need to line up a large number of limit switches for position detection. Furthermore, since the timer means for obtaining a certain period of time can be easily configured, the entire control device can be made low in cost.

〔Effect of the invention〕

As described above, according to the injection speed control method according to the present invention, one of two or more predetermined patterns for the injection start-up turn in the injection process is appropriately selected and commanded to increase the injection speed. The injection speed is changed after a certain period of time has elapsed from the point in time, and the injection speed is controlled by selecting one of the predetermined increase/decrease patterns. Control selection can be made extremely easily. Of course, it is possible to obtain injection control that roughly matches the desired injection conditions, so it is practical on-site.

In addition, when using a limit switch as a means of detecting the injection position, in addition to the limit switches for the front and rear limits, only one switch for position detection that operates at the end point of the low speed range is required, so the control device is not required. The number of parts including the parts is small and the construction is simple, and it is also easy to set the injection speed change point, which has the effect of lowering the cost of the device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional injection speed control device, FIG. 2 is a graph showing an example of its injection speed pattern, and FIG. 3 is a block diagram of an injection speed control device to which an embodiment of the present invention is applied. FIG. 4 is a cross-sectional structural diagram showing an example of the flow rate control pulp used in the injection speed control device, and FIG. 5 is a graph showing an example of the injection speed pattern. 1... Injection cylinder, 2... Piston rond,
Ta: Magnesqueal, 7b: Fist: Magnetic head, 4: Φ, Fighting pump 2, 13: Hydraulic pressure circuit,
14...Low-speed injection speed setting device, 15...Switching position setting device to high-speed injection speed, 16...Low-speed injection start-up shifter/command device, 17...High-speed injection speed setting device ,
18-...Timer for changing the injection speed at the high-speed injection end part, 19...Injection speed increase/decrease pattern command D, 2Q...Pulse motor, 21...
Flow rate control pulp, 34...computer, 35... control pulse generator. Figure 1 □□□□□Ika Figure 3 21'-7 w54 Figure 4 gfSs diagram

Claims (1)

[Claims] In an injection speed control method in which the injection speed has a low speed range in the first half of the process and a high speed range in the second half of the process, and the injection speed by the injection cylinder is controlled by operating a pulse motor-driven flow control valve, in the low speed range selects one of the low injection speed, the injection stroke position of the switching point from the low speed range to the high speed range, and two or more low simultaneous top turns that have been input in advance to the injection speed control device. In the high speed range, the injection speed is controlled by commanding a low continuous rise pattern, and an increasing pattern and injection that tend to further increase the injection speed in the latter half of the high speed range, which is input in advance to the injection speed control device. An injection speed control method comprising commanding and controlling a speed change pattern selected from among decreasing patterns that tend to decrease the speed and a starting point of the speed change pattern.