JPH0342114A - Method for controlling extruding speed - Google Patents

Abstract

PURPOSE:To speedily rise the control motion and to prevent the overshooting by stopping the controlling operation at the beginning time of extruding and beginning the controlling operation when the set value of signal becomes equal to the speed set value of signal with which the speed for optimum extruding is realized. CONSTITUTION:On the beginning time of extruding, the command to fully open the oil pressurizing valve 25 is outputted and the controlling operation is not executed. When the advancing speed of the stem 16 is approached the optimum extruding speed, by monitoring the movement of the stem 16 with the encoder 19, the set value of signal is dropped, then the opening degree of the oil pressurized valve 25 is lowered, and when the set value of signal becomes equal to the speed setting signal to realize the speed for optimum extruding, the process control motion is operated. The products 11 extruded from the die 12 are made good because the overshooting is prevented and the rise at the advancing speed of the stem 16 is also speedy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for controlling the extrusion speed of a molding device for extrusion molding a long metal bar.

[Conventional technology] Conventionally, in order to manufacture long metal objects such as aluminum sashes,
As shown in FIG. 7, the through hole 1 that defines the cross-sectional shape of the product 11
A die 12 in which a base material called a billet 15 is inserted is placed on the front side of a container 14 into which a base material called a billet 15 is inserted. A long product 1 is produced by extruding the base material through the provided through hole 13.
1 is molded.

In the molding and manufacturing of such long objects, the condition of the base material and the product 11
The optimum value of the extrusion speed of the product 11 is determined by the cross-sectional shape of the stem, etc. If the extrusion speed is faster than this optimum value, the surface of the product 11 will be rough, and if the extrusion is made slower, it will take more time to manufacture. While the extrusion speed of 16 was detected by the encoder 19, the extrusion speed was manually operated by the operator to maintain the optimum extrusion speed.

During this manual operation, at the start of extrusion, the valve 25 to the hydraulic cylinder 1 is opened wide to accelerate the rise of the extrusion speed, and as shown in Fig. 8, the extrusion speed reaches the optimum value immediately after the start of extrusion. Reach speed SP,
Although it is ideal to maintain the optimum extrusion speed Sp until the end of extrusion, as the stem 16 advances, the base material billet 15 first deforms to fill the void in the container 14, and in response to this deformation, the stem 16 After the base material is pushed forward into the through hole 13 of the die 12, the forward speed of the stem 16 is temporarily reduced, and then the base material is pushed out into the through hole 13 of the die 12.
The forward speed of the stem 16 increases while extruding the base material as the product 11. In this manner, the extrusion speed increases, and when the extrusion speed approaches the optimum extrusion speed sp, the valve 25 is throttled, thereby extruding the product 11 at a constant optimum extrusion speed Sp.

However, when the valve 25 is throttled, if the timing of throttling the valve 25 is delayed, the stem I
The forward speed of B exceeds the optimum extrusion speed Sp, causing an overshoot and roughening the surface of the product 11. Also, if the timing of tightening the valve 25 is too early, the optimum extrusion speed Sp will exceed the optimum extrusion speed Sp, as shown by the broken line in FIG. This will result in a delay in reaching the destination.

Furthermore, since this rising speed varies depending on the heating state of the fillet 15, the shape and cross-sectional area of the through hole 13, etc., the above operation requires skill, making it difficult to improve productivity.

For this reason, attempts are now being made to automate processes using process control, which is feedback control.

For this process control, a process controller 51 is used,
As shown in FIG. 10, the speed setting signal output from the speed setting device 28 was input to the process controller 51, and the value of the speed setting signal was set to a value giving the optimum extrusion speed, which was then measured by the encoder 19. Measured value and the speed setting device 2
Compare the set value of the speed setting signal set by 8,
While correcting the value of the speed setting signal by the value of the measured value signal, the process controller 51 sends a control signal with a value close to the value of the speed setting signal to the valve controller 23, and the valve controller 23 sends it to the extraction cylinder 18. There is a device that controls the opening degree of a valve 25 that sends pressure oil.

This process controller 51 is generally used in a PI controlled reactor that performs proportional action and integral action as process control actions.
As shown in FIG. 11, a differential amplifier 53 compares a set value and a measured value and amplifies the difference; an operational amplifier 55 amplifies the output of the differential amplifier 53 and outputs a control signal; Many of them have an integral capacitor 57 that integrates the output of the amplifier 55, an integral gain adjustment resistor 58, and a proportional gain: A adjustment resistor 56 that determines the amplification factor of the operational amplifier 55. There is also a PID control type process control operation that performs a process control operation that includes a differential operation, and as shown in FIG. In addition to 56, a differential capacitor 61 and a differential gain adjustment resistor 83 are added, and the differential amplifier 53 output is connected to a differential capacitor 61 and a differential gain: A? ! resistor 63
In many cases, the signal is inputted to the PI controlled reactor operational amplifier 55 via an operational amplifier 65 with an additional function.

[Problems to be Solved by the Invention] Although attempts have been made to automate extrusion control at the optimum extrusion speed sp by using a process controller as described in +iii, extrusion molding usually takes several seconds to 19 seconds. Since the cycle ends at a certain point, it is necessary to make a response in a short time, and even if various adjustments are made to improve tracking performance, if the sensitivity of the proportional or integral action of the process controller is increased too much, Since the operation becomes unstable and causes oscillation, etc., there is a limit to improving the followability in the stable region depending on the adjustment of the proportional gain adjustment resistor, integral gain adjustment resistor, and differential gain adjustment resistor. As shown in the figure, there are cases where the extrusion speed becomes stable at the optimum extrusion speed Sp near the end of the extrusion operation, and cases where extrusion is completed before reaching the optimum extrusion speed sp.

In addition, the hardness of the billet 15 changes depending on the heating temperature,
The forward speed of the stem 16 also changes slightly due to the sliding resistance of the backing plate provided at the tip of the stem 16, so the characteristics of the extrusion speed change from cycle to cycle, and the state of occurrence of hunting also differs from cycle to cycle. , adjustment was difficult.

[Means for Solving the Problems] The present invention provides, when controlling the extrusion speed of an extrusion molding apparatus using a process controller, the advancement speed of the stem approaches the set optimum extrusion speed at the start of extrusion. Until the process control operation in the process controller is stopped, the value of the control signal is made approximately equal to the value of the set value signal, and the value of the set value signal input to the process controller is changed to a speed setting signal that gives the optimum extrusion speed. When the forward speed of the stem approaches the optimum extrusion speed, the value of the setpoint signal is lowered, and when the value of the setpoint signal is equal to the value of the speed setpoint signal that gives the optimum extrusion speed, the process The process control operation in the controller is started and the value of the set point signal is adjusted to the value of the speed set signal that provides the optimum extrusion speed.

In addition, in the extrusion speed control method described above, the value of the set value signal input to the process controller at the start of advancement of the stem is always set to a constant large value such as a value giving the maximum advancement speed of the stem, and the rise characteristics of the stem at this time are is detected, and thereby the gain is switched in the proportional operation in the process controller, and the timing and rate of descent of the set value signal from the value giving the maximum forward speed to the value giving the optimum extrusion speed are changed. shall be.

[Operation] Since the method according to the present invention stops the process control operation in the process W moderator at the start of extrusion, the process controller outputs the input setting value signal as it is as a control signal, and the forward speed of the stem is adjusted. Since the process control operation is initiated after the optimum extrusion speed is approached, the advancement speed of the stem can be controlled to match the optimum extrusion speed.

Furthermore, at the start of extrusion, the value of the set value signal input to the process controller is increased, so the value of the control signal output from the process controller is sufficiently increased, and the rise in the forward speed of the stem can be made quickly. can.

Furthermore, by adopting a method of detecting the rise characteristic of the stem at the start of extrusion, the hardness of the base material and the state of the extrusion device can be detected at the start of extrusion, and the drop when the value of the set value signal is lowered. By changing the start timing and rate of descent according to the rise characteristics, overshoot can be prevented even more reliably, and by switching the gain of the proportional operation, it is possible to easily make adjustments to prevent hunting.

[Example] Control for extrusion equipment implementing the method according to the present invention 1:l-
As shown in FIG. 1, the controller 30 is composed of a control means 31 storing a process control algorithm, a process controller 51, an operational amplifier 71, and a switch element 75. A first analog-to-digital conversion unit 41 that sends the speed setting signal inputted from the device 28 to the central processing unit 32 as a digital signal. A second analog-to-digital conversion unit 42 that sends the measurement value signal input from the encoder 18 as a digital signal to the central processing unit 32, an input conversion unit 43 to which the start signal from the start switch 29 is input, a speed control program, etc. ROM35 for storing and appropriate RAM3B,
Furthermore, based on the stored program, there is a digital-to-analog conversion unit 45 that outputs a set value signal for the extrusion speed as an analog signal, and a first person output device 46 that outputs a gain adjustment signal to the process controller 51 and a relay switch. A second person output device g! that outputs a switching signal to the switch element 75! i47, and the process controller to which the set value signal from the control means 31 is inputted is a PI sub-control type process X[i
In addition, a switch element 75 such as a relay switch and an operational amplifier 71 are added, and the added operational amplifier 71 receives a control signal which is an output signal of the process controller 51 and a setting value from the control means 31. Enter the signal and
This difference is amplified and outputted from the operational amplifier 71, and the output terminal of the operational amplifier 71 is connected to the integrating capacitor 57 in the process controller 51 via the switch element 75. The output can be applied to or cut off from the integrating capacitor 57. The control terminal of this switch element 75 is connected to the second output device 47 which outputs the switching signal of the control means 31, and the relay switch [i7, 88 control] which adjusts the proportional gain The terminal is connected to a first input/output device 46 that outputs a gain adjustment signal.

The operation of the process controller 51 to which the operational amplifier 71 is added by the switch element 75 is as shown in FIG.
s, the voltage of the control signal output from the process controller 51 is VO, the output voltage of the differential amplifier 53 is VE, and the feedback voltage in the process controller 51 is r, VE = (Vs - Vp) g.

(However, go is the amplification factor of the differential amplifier) Vo = (VE - Vt ) gl (However, gl is the gain factor of the operational amplifier) Vr = (vo - Vs ) gl・Kp (However, gl
is the increase rate of the operational amplifier added to the process controller, KP
is the feedback factor of the proportional gain adjustment resistor).

If we rearrange the above formula, vo = gl ・ gl ・ KP II vs /
(l +g1g2 ・Kp)+g+ ・V[/
(1+g1 ・gl ・Kp), and if gl is made large enough, gl'g2 ・Kp)>1, and V, )=V5
+Vt 7g2' kp=Vs + (Vs-V, P
) go/g2″Kp VS.

Therefore, when the switch element 75 is in the on state, the process: A cylinder needle 51 is hardly affected by the input measurement value signal, and receives the value of the control signal output from the process controller 51. The value will be approximated to the value of the set value signal, and no process control operation will be performed.

Then, when the switch element 75 is cut off by the switching signal, the process;
A signal having a value close to the value of the set f dust signal is output as a control signal while being corrected by the value of the fixed value signal, and normal process control operation is performed.

The control program b-gram to be stored in the central processing unit 32 of the control means 31 is 1, for example, as shown in FIG. is the value S^, and the encoder 1 is set until the forward speed of the stem 18 reaches 80% of the optimum extrusion speed sp set by the speed setting device 28.
Measured value signal P from 9.

The value of the set value signal SV is maintained at VA while determining based on the value of
When it is detected by the measured value P that it has reached 80% of
The value of the set value signal Sv is lowered at the falling speed β, thereby setting the value of the set value signal S to the set value SP' that provides the optimum extrusion speed Sp, and thereafter.

The control means 3 uses the value SP' of the speed setting signal inputted from the speed setting device 28 as an instruction signal for the optimum extrusion speed SP.
1 until just before the end of the extrusion operation, and when the value of the set value signal Sv reaches the value SP° indicating the optimum extrusion speed Sp, the process adjustment is performed. Settings are made so that the input/output device 47 can output a switching signal for cutting off the switch element 75 added to the total 51.

Therefore, in the extrusion speed control method using the extrusion device controller 30, when a start signal is input from the start switch 29, a set value signal with a value SA for fully opening the valve 25 is output from the control means 31. Then, the valve 25 is fully opened by a control signal from the extrusion device controller 30, and the stem 16 starts to move forward. The forward speed of this stem 16 increases from the start of forward movement, and after once decreasing in the middle, the forward speed increases with the value of the set value signal as the target, so that the value of the first peak value Time tp until VX or first peak appears
, and the rate of change Δ■ up to the first peak is calculated by the central processing unit 3.
2, the forward speed of the stem 16 is accelerated with a constant valve opening.

Then, the forward speed of the stem 16 is 80, which is the optimum extrusion speed.
%, the value of the set value signal from the control means 31 is changed to S
^ to the set value SP' at a falling speed β, and when the value of the set value signal reaches SP', a switching signal is output from the second person output device 47 to open the switch element 75, and the process controller 51 is proportional to While performing the operation and the integral operation, the process control operation is performed with the target set value SP' output by the control means 31 as a set value signal.

In the method according to this embodiment, as described above, the process controller 51
An operational amplifier 71 and a switch element 7 such as a relay switch
5 and applies the output of the operational amplifier 71 to the integrating capacitor 57 to stop the process control operation. Therefore, at the start of extrusion, the switch element 75 is turned on and the output of the operational amplifier 71 is integrated. When applied to the capacitor 57, a control signal having a value close to the value of the set value signal SV input to the process controller 51 is output, and the speed control in section A shown in FIG. 2 is executed as program control. can do.

As a control signal to the valve controller 23, a set value signal from the control means 31 is sent to the process controller 5.
However, at the start of extrusion, the process control operation is stopped and the set value signal is output as a control signal, and the setting value output from the control means 31 is The value of the value signal SV is a value SP' giving the optimum extrusion speed SP in extrusion molding.
Since the f-direction SA is larger than that, the process controller 51
The value of the output signal of valve controller 2 rises rapidly.
3, the opening degree of the valve 25 can be quickly and sufficiently increased, and the forward speed of the ram 17 and stem 16 can be increased in a relatively short time.

Fourth, the forward speed of this stem IB etc. is the optimum extrusion speed S.
When reaching, for example, 80% of P, the value of the set value signal Sv from the control means 31 is changed to a value SP' that provides the optimum extrusion speed SP.
When the value of the set value signal Sv becomes equal to SP', the control means 31 outputs a switching signal and changes the switch element 75 to the on state, so that the proportional gain [! A control signal voltage is applied to the resistor 58 via the integrating capacitor 57, and the process controller 51 starts the process control operation, and the valve controller 23 is driven by the PI operation to provide the optimum extrusion speed SP. Since the process control is performed using the value sp" of the set value signal as the target value, the stem 1s etc. move smoothly forward so as to maintain a constant optimum extrusion speed Sp, as shown in section B of FIG.

Switching between the program control shown in section A and the process control shown in section B is performed by turning on and off the switch element 75 as described above, and the forward speed of the stem 16 etc. is optimal. Since switching is performed when the extrusion speed is close to SP, even if the switch element 75 is shut off, there is no sudden change in the value of the feedback signal in the process controller 51, and when switching from program control to process control, the process controller It is possible to perform relatively smooth switching without causing any fluctuation in the output signal of ij!51, as shown in FIG. , the extrusion speed can be increased quickly and the target speed can be maintained smoothly.

Further, in this embodiment, the process control operation is stopped when the difference between the value of the set value signal SV and the measured value Pv is large, and the process control operation is started after the value of the set value signal and the measured value become close to each other. Therefore, PI control is performed accurately, there is little possibility that the extrusion speed will exceed the optimum extrusion speed near the end of the extrusion operation, and adjustment of the integral gain and proportional gain becomes easy.

By the way, while repeating extrusion molding, when the value of the set value signal outputted by the control means 31 is lowered from ■^ to SPo, if the falling speed β is fast, the stem 16 moves forward as shown in FIG. The speed increase may be slow, and if extrusion is repeated at a constant falling speed, when the temperature of the billet 15 is high, the stem 16 rises quickly, and the value of the set value signal drops from ■^ to SPo. Stem 1 while
The forward speed of 6 may reach the controlled extrusion speed, causing overshoot.

Therefore, a plurality of values are set as the falling speed β in the control means 31, and the timing at which the value of the set value signal is lowered from the value S^ that fully opens the valve 25 is determined by the measured value signal. The forward speed of is 7 of the optimum extrusion speed Sp.
A program is also set to detect when 0% or 60% is detected, and as mentioned above, if the value of Δ■ based on the rise characteristic of the stem 16 measured at the start of extrusion is larger than the reference value, 1, for example, a set value signal is output. The value of the set value signal outputted from the control means 31 is changed to the set value S by making the start of descent from the value SA that fully opens the valve 25 as early as when it reaches 60% of the optimum extrusion speed SP. Stem 1 while descending to T
This prevents the forward speed of the stem 16 from exceeding the optimum extrusion speed Sp, and also speeds up the start of descent of the set value signal from S^ and reduces the falling speed β, thereby increasing the forward movement of the stem 16. The speed may be gradually increased to reach the optimum extrusion speed Pv.

The rising characteristics of the stem 16 depend on the hardness of the billet 15 as well as the shape of the product, that is, the through hole 13 formed in the die 12.
The value of the set value signal outputted from the control means 31 at the start of extrusion is limited to the value S^ that fully opens the valve 25, since the shape and cross-sectional area of the extrusion device are greatly affected by the extrusion capacity of the extrusion device. Instead, it is sufficient to set the opening degree of the valve 25 to a constant value that gives 90% opening degree or 80% opening degree, and always measure the rise characteristics at the same valve opening degree.

Furthermore, if the rising speed Δ■ in the initial state is larger than the reference value, the relay switches 87 and 88 are made conductive by the gain adjustment signal to reduce the feedback to the operational amplifier by the proportional gain adjustment resistor 56, thereby increasing the PI Prevents vibration during control, that is, hunting. The proportional gain can be adjusted using the proportional gain adjustment resistor 5 as shown in Figure 1.
Turn on/off relay switch 87 and 88 connected in parallel with 6.
By turning off, the proportional gain becomes W? ! ! As shown in FIG. 6, the control means 31 is not limited to the case where 51 The gain adjustment signal from the input/output device 46 is sent to the servo control device 7.
8, the value of the proportional gain adjustment resistor 56 can also be adjusted by the servo motor 77.

In addition, in the above example, the process: Afli5 is 51 in total, and P
This is an embodiment using an I sub-control type process controller 51,
Even if a PID control type process controller is used, the PID control type process controller 51 is a PI sub-control type process controller 51.
Since the differential capacitor 81 and the differential gain adjustment resistor 63 are added to the same, even when using the PID control type process controller 51, quick startup, smooth control switching, and tracking of the target value can be achieved. It is possible.

In the above embodiment, the output signal of the extrusion device controller 30 is input to the valve controller 23, and the valve controller 23 controls the opening degree of the valve 25. It is also possible to control the operating speed of the hydraulic pump 21 by inputting it to a speed control device.

[Effects of the Invention] In the method according to the present invention, at the start of extrusion, the process control operation of the Bukosess controller is stopped until the forward speed of the stem approaches the optimum extrusion speed, and the value of the set value signal input to the process controller is Because it is thicker, the forward speed of the stem etc. rises quickly, and the process control operation is started after the forward speed of the stem approaches the optimum extrusion speed, making it easy to adjust the gain and reduce overshoot during extrusion. can be prevented.

In addition, the method of adjusting the gain and changing the start time and rate of descent of the set value signal by keeping the value of the set value signal constant at the start of extrusion and detecting the rise characteristic when the stem starts moving forward can prevent overshoot and hunting. can be more reliably prevented.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the controller for an extrusion device used in the present invention, FIG. 2 is a graph showing an example of speed control according to this embodiment, FIG. 3 is a graph showing the rise characteristic, and FIG. is the controller process Egij according to this embodiment.
Figure 5 is a graph showing an example of the forward speed of the stem, Figure 6 is a diagram showing an example of a controller for another extrusion device, and Figure 7 is a graph showing the signal voltage of each part of the meter. FIG. 8 and FIG. 9 are graphs showing changes in extrusion speed in the extrusion molding device, FIG. 10 is a diagram showing automatic control using a conventional process controller, and FIGS. FIG. 13 is a diagram showing an example of a circuit of a conventional process controller, and FIG. 14 is a graph showing speed control by the conventional process controller. 11=Product, 12=Dice, 14=Container,
15=billet, 16=stem, 18=hydraulic cylinder, 19=encoder, 21=hydraulic pump,
23=valve controller, 30=extrusion device controller, 31=control means, 32=central processing unit, 41.42=analog-digital conversion unit,
45 = digital-to-analog conversion unit, 51 = process controller, 53 = differential amplifier, 55 = operational amplifier, 5B = proportional gain adjustment resistor, 57 = integral capacitor, et = differential capacitor, 71 = operational amplifier,
75 = switch element. Sai 2 Zuzai Zu 3 Iku Zu Kyoko Zu Yo Zu Sai 1; Blade 2 Zu Sai Zu Sai 3

Claims (2)

[Claims] (1) When controlling the extrusion speed of the extrusion molding device using a process controller, at the start of extrusion, the process control operation in the process controller is stopped until the forward speed of the stem approaches the set optimal extrusion speed. thereby outputting the value of the set value signal as the value of the control signal, and
The value of the set value signal input to the process controller is set larger than the value of the speed set signal that gives the optimum extrusion speed, and when the forward speed of the stem approaches the optimum extrusion speed, the value of the set value signal is decreased, and the set value signal is When the value of becomes equal to the value of the speed setting signal that provides the optimum extrusion speed, starting a process control operation in the process controller and maintaining the value of the set value signal at the value of the speed setting signal that provides the optimum extrusion speed. A method for controlling extrusion speed in an extrusion molding device, characterized by: (2) In the extrusion speed control method according to claim 1, the value of the set value signal input to the process controller at the rise of the forward speed at the start of forward movement of the stem is set to a value giving the maximum forward speed of the stem, etc. is always set to a constant large value, and the rise characteristics of the stem at this time are detected to switch the gain in the proportional operation of the process controller.
An extrusion speed control method characterized by changing the time and rate of descent of a set value signal from a value giving a maximum forward speed to a value giving an optimum extrusion speed.