JPS61222624A - Controlling method of hydraulic reduction - Google Patents

Abstract

PURPOSE:To prevent a delay of reduction response just before finishing of rolling at a pipe end by detecting a differential pressure at a servo-valve usually and changing gains in the electric control system continuously using a function of differential pressure-electric control system gains to make a flow rate of the servo-valve to constant. CONSTITUTION:When set value P60 is inputted in a comparator 7, the top or rear end of a rolling stock is selected, an opening of the servo-valve is indicated through a change-over contact 6-1 or 6-2 of a flow control circuit 6 and an amplifier 5 of the servo-valve, and an oil pressure is detected by an oil pressure detector 8. A flow rate into the servo-valve 4 is made constant by the fact that the differential pressure DELTAP is calculated using the detected hydraulic pressure the differential pressure DELTAP calculated using the detected oil pressure is inputted into the flow control circuit 6, a gain K o the electric control system is changed continuously using a function of the electric control system gain K-DELTAP.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for controlling a hydraulic reduction rolling mill using a servo valve, and in particular to changes in hydraulic control system gain due to load fluctuations in a tube elongation mill such as a mandrel mill. The present invention relates to a hydraulic pressure reduction control method that compensates for this by changing the electrical control system gain and prevents a delay in pressure reduction response.

Prior art and its problems As a method for controlling hydraulic reduction in a tube elongation rolling mill, especially in a mandlerumi/I/ In order to offset the thickening of a part, a method is known in which the thickness of the part is made thinner by controlling the reduction (Japanese Patent Publication No. 51-43825).
. However, in hydraulic reduction control where the flow rate is determined in proportion to the differential pressure at the servo valve, when rolling to thin the tube end, especially when thinning the tip, the control is terminated because the reduction control depends on the rolling load. At this point, fluctuations in the rolling load occur, and if the electrical control system gain is constant, a rolling response delay occurs.

As another method of hydraulic pressure reduction control, there is a known method in which pressure reduction control is performed by compensating for changes in the hydraulic control system gain due to load fluctuations by changing the electrical control system gain. 43465).

In this method, a gain control circuit consisting of multiple sets of variable resistors and relays is provided in the electrical control system, and the gain of the electrical control system is changed by detecting rolling rotation, etc., and switching the variable resistors and relays. It is a feature. However, if the electrical control system gains are fixed and selective, it is possible to achieve the control responsiveness and efficiency that are the characteristics of fast-response servo valves, but the continuous flow rate Control is not constant, and a rolling response delay inevitably occurs, especially in a very short period of time just before the end of tube end rolling. This delayed response portion becomes thinner than specified in the next process reducing mill, which significantly impedes the tube end reduction control effect.

Purpose of the Invention The present invention was made to solve the above-mentioned conventional problems, and provides a hydraulic reduction control method capable of preventing a delay in reduction response in a region where the rolling load rapidly decreases immediately before the end of tube end rolling. The purpose is to make suggestions.

Structure of the Invention The hydraulic pressure reduction control method according to the present invention includes a flow control circuit that is controlled by a function of an electric control system gain and a hydraulic control system gain, and the electric control is controlled by the function according to the differential pressure of the servo valve part. [Changing system gain] 7. This is characterized by controlling the flow rate of the servo valve part to be constant.

That is, the present invention constantly detects the differential pressure of the servo valve, changes the electrical control system gain from a function of the differential pressure and the electrical control system gain, and performs continuous constant flow rate control.
This is a method to fully demonstrate the tube end pressure reduction control effect.

Hereinafter, in order to further clarify the gist of the present invention, examples will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a mandrel mill control method according to an embodiment of the present invention.
) is the reduction cylinder, (3) is the reduction position detector, (4) is the servo valve, (5) is the servo valve amplifier, (6) is the flow control circuit, (7) is the comparator, and (8) is the oil pressure detection. and (9) indicate the hydraulic units, respectively.

In other words, the mandrel slide A/ (11 is composed of two pairs of rolls (upper and lower) arranged at 45 degrees, each roll is driven by a rolling cylinder (2). Rolling stand company usually 7~ It consists of 8 stands.

The amount of movement of the reduction cylinder (2) is detected by a reduction position detector (3), is input to a comparator (7), and is compared with a set value Pbo. On the other hand, the hydraulic pressure of the servo valve (4) is detected by the oil pressure detector (8), and the differential pressure due to load fluctuation is input to the flow rate control circuit (6). It is becoming more and more driven.

The gain of the hydraulic pressure reduction control system is roughly divided into the gain of the electric control system and the gain of the hydraulic control system, and the flow rate gain changes depending on load fluctuations. The flow rate of oil flowing into and out of the compression cylinder (2) through the servo valve (4) is expressed by the following equation.

Q = K By changing the system gain, the flow rate to the pressure cylinder can be made constant.

FIG. 2 shows the flow rate control circuit (6). This flow rate control circuit (6) has switching contacts (6-IX6-2) at the front and rear ends of the rolled material in the region where the rolling load rapidly decreases, and has a function of differential pressure ΔP - servo valve opening coefficient. Therefore, the value of K is continuously changed in response to changes in ΔP, and the flow rate Q to the pressure reduction cylinder (2) is controlled to be constant at all times.

Function: To explain the method of this invention using the rolled material α0 shown in FIG. 3 as an example, when the comparator (7) K set value Pbo is input,
The leading end or trailing end of the rolled material is selected and the flow rate control circuit (6)
The servo valve opening degree is instructed through the switching contact (6-1) or (6-2) and the servo valve amplifier (5),
Oil pressure is detected by the oil pressure detector (8).

is input to the flow rate control circuit (6), and the electric control system gain K is continuously changed as a function of the electric control system gain - ΔP, so that the flow rate flowing to the servo valve (4) becomes constant.

Figure 4 shows an example of the rolling reduction control signal for rolled material αO.
In the conventional method, a rolling response delay occurs as shown by the broken line just before the end of tube end rolling, but according to the method of the present invention, the electrical control system gain K changes continuously as a function of the differential pressure ΔP, and the servo valve flow rate is Since it can be kept constant, there is no reduction response delay as shown by the solid line in FIG.

Effects of the Invention As explained above, the method of the present invention constantly detects the differential pressure at the servo valve, and continuously changes the electrical control system gain based on the function of the differential pressure - electrical control system gain to control the flow rate of the servo valve. This method has the effect of completely preventing rolling response delay in the region where the rolling load rapidly decreases immediately before the end of tube end rolling. Therefore, according to the method of the present invention, by eliminating the portion where the rolling response is delayed, thinning rolling can be carried out as specified in the next process reducing 9 rolling mill, etc., and the pipe end rolling control effect can be fully exhibited.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the control circuit configuration of a mandrel μM according to an embodiment of the present invention, FIG. 2 is an enlarged view of the same flow rate control circuit as above, and FIG. FIG. 4 is a longitudinal sectional view showing an example of the material, and FIG. 4 is a diagram showing a rolling control signal for the same rolled material. DESCRIPTION OF SYMBOLS 1... Mandrel mill reduction position detector, 4... Servo valve, 5... Servo valve amplifier, 6... Flow rate control circuit, 7... Comparator, 8...
...Hydraulic pressure detector, 9...Hydraulic unit. Applicant: Sumitomo Metal Industries, Ltd. Figure 2 Figure 3

Claims (1)

[Claims] In a hydraulic pressure reduction control method using a servo valve, a flow control circuit is provided that is controlled by a function of an electric control system gain and a hydraulic control system gain, and the electric control system gain is changed from the function according to the differential pressure at the servo valve part. A hydraulic pressure reduction control method characterized in that the flow rate of a servo valve is controlled to be constant.