JPH02169166A - Method for controlling position of cylinder - Google Patents

Abstract

PURPOSE:To effectively prevent raising of the pressure and to prevent burning and gnawing, etc., of a pressurizing plunger by applying lemination to the pressure in a cylinder chamber in the range of prescribed time or shifting stroke of cylinder piston. CONSTITUTION:When control of a feedback controller 15 starts to operate, a pressure control valve 6 is adjusted in every moment and the pressurized plunger 40 is controlled to follow to the aimed locus. When a pressure controller 14 does not reach to the setting time (t1) or shifting stroke (st1), the limit pressure (vs) is outputted as the capacity limit pressure of the pressure source. When the pressure controller 14 reaches to more than the setting time (t1) or shifting stroke (st1). the limit pressure (vs) is outputted as the setting limit pressure. That is, when output signal (v) of a setting part 8 is less than the setting limit pressure, the output signal (vo) of a gate 13 is made to equal to the output signal (v) of the setting part 8, and when output signal (c) of the setting part 8 is more than the setting limit pressure, the output signal (vo) of the gate 13 is made to equal to the setting limit pressure.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method and apparatus for controlling the position of a cylinder piston of a cylinder device, and particularly relates to a method and a device for controlling the position of a cylinder piston of a cylinder device, and in particular, a method and a device for controlling the position of a cylinder piston of a cylinder device, and in particular, a method and a device for controlling the position of a cylinder piston of a cylinder device. Injection cylinders and pressure cylinders for injection molding machines and die-casting machines.

The present invention relates to a method and apparatus for controlling the position of a cylinder piston of a cylinder for an extruder that extrudes material through a die.

[Prior Art] FIG. 2 is a longitudinal cross-sectional view showing the main parts of a die-casting machine for forming a disc wheel. As shown in the figure, an upper mold 33 that can be opened and closed in the vertical direction. The lower mold 35 and the four cores 34 movable in the water direction are combined and clamped from the F force direction in the figure by a mold clamping mechanism (not shown), and the injection is carried out into the cavity 38 formed thereby. The molten metal 37 in the sleeve 39 is filled with the rising action of the injection plunger 38 and the plunger tip 36a by the action of an injection cylinder (not shown) (the molten metal 37 is filled into the cavity 38 in the illustration).
7), after a predetermined time (pressurization time lag) has elapsed since the completion of filling the molten metal 37, the pressurization cylinder 3 is energized by energizing the solenoid 23a of the direction switching valve 23.
The pressurizing plunger 40 attached to the cylinder piston 32 of No. 1 is made to protrude into the cavity 38, and
The molten metal 37 in 8 is pressurized to perform a rising action. 5 is a pump, 4 is a motor that drives pump 5, 7 is a tank,
It constitutes a pressure source for driving the pressurizing cylinder 31.

At this time, it is best to control the operation of the pressurizing plunger 40 so that the history of its protrusion stroke into the cavity 38 follows a predetermined target trajectory as time passes from the start of the operation. This is because the pressure plunger 40. Although the upper die 33 undergoes dimensional changes, the condition is not uniform due to differences in the coefficient of thermal expansion and cooling conditions of the two, so simply controlling the operating pressure of the pressurizing plunger 40, that is, the feeder force, will not change the dimensions.
This is because the stroke of the pressurizing plunger 40 is not uniform due to external factors such as changes in frictional resistance and insertion of molten metal, and the above-mentioned feeder action is not stable. To achieve this, for example, we previously
The method and apparatus were presented in Japanese Patent Application No. 63-244552.

First, based on the time from the start of operation of the pressurizing plunger 40 (L=0), st is predetermined in the model section 9 as a one-mark trajectory for the movement stroke of the pressurizing plunger 40 into the cavity 38. Then, the moving stroke amount S [, which is the target trajectory, and the cylinder piston 32 detected by the position detector 3, that is, the pressurizing plunger 4
The deviation amount e from the actual movement stroke amount stb of 0 (e=st
-stb) is determined by the deviation detection unit lO, and this deviation amount e
The gain setting unit 8 processes the signal as appropriate and outputs a predetermined output signal V to the driver 12 in accordance with the received signal. The driver 12 adjusts the pressure regulating valve 6 according to the magnitude of the output signal V from the gain setting section 8 to control the pressure p of the pressure source. In addition, model part 9. The feedback controller 11 is controlled by the deviation detection section 10 and the gain setting section 8.

In this way, by changing the working pressure that drives the pressurizing plunger 40 according to the variation amount e between the target trajectory st and the actual movement stroke amount stb of the pressurizing plunger 40,
By controlling the moving stroke amount of the pressurizing plunger 40 with respect to time to follow the target trajectory, the factors of unstable operation such as fluctuations in the sliding resistance of the pressurizing plunger 40 mentioned above are eliminated. was.

[This is what the present invention attempts to solve! l! X! i7] As the number of moldings increases due to continuous operation, the pressurizing plunger 40 is forced into contact with the molten metal 37 every time, so its sliding surface (corresponding to the cylindrical side surface) inevitably becomes rough. However, even if the sliding resistance increases due to the action described above, the pressure applied to the pressurizing cylinder 31 is increased so as to control the target trajectory.1 For example, if the maintenance is poor, the sliding resistance increases. As a result, the working pressure will eventually rise to the capacity limit of the pressure source. If this happens, seizure may occur between the pressurizing plunger 40 and the upper mold 33, and the In some cases, the product could become welded and become completely inoperable.

[Means for Solving the Problems] In the present invention, the cylinder chamber pressure for operating the cylinder piston is changed in accordance with the deviation between the movement stroke amount of the cylinder piston, which is the target trajectory, and the ¥ movement stroke IT1. When controlling the movement stroke amount of the cylinder piston to follow r16@ trace,
The cylinder chamber pressure for operating the cylinder piston is limited within a predetermined time or within a range of movement strokes of the cylinder piston.

[Operation] In the present invention, the same operation as the control method shown in the means for solving the problems described above is performed. Since the cylinder chamber pressure for operating the cylinder piston is limited, it is possible to prevent the pressure acting on the limiting pressure device 1 from increasing.

Moreover, by limiting the cylinder chamber pressure to a predetermined time or within a predetermined cylinder piston movement stroke range, it can be applied effectively only in the range where ′i1 must be suppressed due to pressure abnormalities. can.

[Example] This will be explained with reference to FIG. In addition, for the elements whose functions are the same as those explained in Figure 2 above, the numbers will be the same.
A detailed explanation will be omitted here.

Model part 9. The signal V processed and outputted through the deviation detection section 1O and the gain setting section 8 is outputted to the driver 12 via the gate 13. The gate 13 receives and compares the output signal V from the gain setting section 8 and the output signal vs from the pressure limiter 14 (described later), and as shown in the following equation 11 equation II, when V is smaller than VS makes the output signal vO of gate 13 equal to V, and when V is greater than or equal to VS,
It has a function of making the output signal vO of the gate 13 equal to VS.

vo=v (when v<vs) --- (Formula I) yo=v
s (when v≧vS) - (Formula H) The pressure limiter 14 is
For example, the program is programmed as shown in FIG.
Or, when the movement stroke st1 is not reached, the limit pressure vs is set to the capacity limit pressure vmax of the pressure source, and the time t
1. Alternatively, when the movement stroke st1 or more is reached, vs is made equal to the set limit pressure VSS.

In addition, model part 9. Deviation detection section 1, gain setting section 8.
The gate 13 and the pressure limiter 14 constitute a feedback controller 15.

Now, when the operation of the pressurizing plunger 40 is commanded and the feedback controller 15 starts controlling, the pressure control valve 6 is adjusted from time to time in accordance with the above-mentioned action, and the pressurizing plunger 40 is adjusted to the target trajectory. is tracked and controlled. The pressure limiter 14 is.

When the preset time 1+ or the movement stroke stl is not reached, the limit pressure V5 is output as the pressure source's capacity limit pressure vmax, so (Formula 1) is established at the gate 13, and the output signal Since vO is equal to the output signal V of the gain setting section 8, the feedback controller 15 of the present invention performs the same control as the feedback controller 11 of the prior art. However, when the time tl preset in the pressure limiter 14 or the movement stroke SL1 is exceeded, the pressure limiter 14 outputs the limit pressure vs as the set limit pressure VSS, so depending on the value of VSS, , gate 1.3
In this case, either (Formula 1) or (Formula (■)) holds true. That is, the output signal V of the gain setting section 8
When is smaller than the set limit pressure VSS, 13
The output signal vO of the gate 13 is made equal to V, and when V is greater than or equal to vSS, the output signal VO of the gate 13 is made equal to vss.

Here, as mentioned above, the range for pressure restriction is defined as time t+
, or the moving stroke st1 or more is set for the following reason. In other words, as shown in FIG. 3, the target locus of the pressurizing plunger 40 is generally in the first half of the range r! and the relatively gradual range r in the second half
2, and in order to follow this initial acceleration, an instantaneous high pressure is required as shown in the figure. Therefore, if the pressure is constantly restricted without limiting the range, the response when acceleration is required will be poor. For this reason, in the first example,
Although the movement of the pressurizing plunger 40 is relatively slow,
Shortcuts that require higher pressure! The pressure was limited in '-R area r2.

Figures 5(a), (b), and (c) are examples of the results.
It is an actual phase diagram of the history of pressure P (vertical axis) with respect to time 1 nt (horizontal axis). Figure 5(a) to Figure 5(b), Figure 5(
It can be seen that according to C), the number of moldings increases, and as a result, the sliding resistance increases, so in order to follow the target trajectory st, the pressure p applied to the pressurizing cylinder 31 increases. Further, in FIG. 5(C), the pressure of the present invention is limited at the final portion shown as pressure limiting portion A, thereby preventing seizure or galling of the pressurizing plunger 40.

Note that it is also possible to measure the frequency with which the output signal vo of the gate 13 is replaced with vss and the time period during which the output signal vo of the gate 13 is replaced, and to output an abnormal signal based on these.

[Effect of the invention] In the present invention, as described in the claims,
Since the pressure in the cylinder chamber that operates the cylinder piston is limited within a predetermined time or within the movement stroke iR of the cylinder piston, pressure rise can be effectively prevented only within the range that must be suppressed, and the pressure of the pressurizing plunger can be reduced. It can prevent burning, galling, etc.

Furthermore, when the present invention is applied to an injection cylinder of an injection molding machine or a die-casting machine, the pressure can be maintained at a necessary and sufficient pressure value by imposing a pressure restriction immediately before the filling of the molding material 1 into the mold is completed. It is possible to prevent the occurrence of Paris, etc.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of an apparatus used for carrying out the present invention;
Fig. 2 is a diagram showing a conventional example, Fig. 3 is a diagram showing another example of the time-stroke diagram in the model section shown in Fig. 1, and Fig. 4 is a diagram showing the pressure limiter shown in Fig. 1. Diagrams showing examples of program states in FIGS. 5(a), (b),
(c) is a time-pressure diagram showing actually measured values when the present invention is implemented. 3...Position detector, 6...Pressure regulating valve, 8
...gain setting section. 10... Deviation detection section, 11.15... Feedback controller. 12...driver, 13...-gate, 14
... Pressure limiter, 31 ... Pressure cylinder, 3
2...Cylinder piston. 38... Cavity, 40... Pressure plunger. 9...Model department,

Claims (1)

[Claims] A cylinder in which the moving stroke amount of the cylinder piston is determined in advance as a target trajectory with respect to time, and the cylinder piston is operated according to the deviation amount between the moving stroke amount of the cylinder piston, which is set as this target trajectory, and the actual moving stroke amount. When controlling the movement stroke amount of the cylinder piston to follow the target trajectory by changing the chamber pressure, limit the cylinder chamber pressure to operate the cylinder piston within a predetermined time or within the movement stroke amount range of the cylinder piston. A cylinder position control method characterized by adding: