JPH04172117A - Method for measuring forward slip on hot rolling mill - Google Patents

Abstract

PURPOSE:To correctly measure the forward slip by assuring the delay of the road-relay starting up by using a delay circuit at the time of using pulse number generating per one rotation of the roll and the pulse number generating during the top end of the material to be rolled passing between rolls. CONSTITUTION:The delay circuit is provided in order to make the passing time of the top of material to be rolled correct when it passes between rolls, by using pulse number generating per one revolation of roll on the hot rolling mill and pulse number generating during the top end of the material to be rolled passing between rolls, in measuring the forward slip on the hot rolling mill. If the forward slip is measured without considering the time difference of the road relay starting up, and the frictional coefficient is obtained with a prescribed equation, it is a negative value on some times. If the delay circuit is provided, the delay of the road relay starting up is corrected to measure the forward slip, it is not negative, and the dispersion of the frictinal coefficient due to the difference of the measuring condition is also not produced. Therefore, the frictional coefficient between the work roll and the strip can be obtained correctly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for measuring the advance rate in a hot rolling mill.

[Conventional technology]

Generally, to measure the advance rate in a hot rolling mill, a load cell is installed on the front work roll, the rear work roll, or on each of the front stage and the rear stage. When the tip of the rolled material enters the preceding rolling mill, a load cell generates a bite signal, and this bite signal causes the pulse generator to start counting. When the leading end of the rolled material enters the subsequent rolling mill, a bite signal is generated from the load cell, and the counting of this pulse signal is stopped.

Assuming that the counted number of pulses is n, the number of pulses generated during one revolution of the front work roll is N, and the diameter of the roll is D, the advance rate f can be determined from equation (1) described below.

For example, Japanese Patent Application Laid-Open No. 53-24873.

[Issues with conventional technology]

It is very difficult to verify whether the advance rate can be measured using the method disclosed in Japanese Patent Application Laid-Open No. 53-24873.

Therefore, a load relay signal, which can easily be obtained as a bite signal, was used for measurement. When the coefficient of friction is determined from the advance rate using equation (3) described below, the coefficient of friction may be negative as shown in FIG. A negative coefficient of friction cannot physically exist, and it is clear that the value of the advanced rate was measured to be larger than the actual value.

This is because the term becomes negative if f is large.

[Means to solve the problem]

The present invention advantageously solves the problems of the prior art, and provides a method for measuring the advance rate in a hot rolling mill, in which the number of pulses generated per roll rotation in the hot rolling mill and the tip of the rolled material are measured. Using the number of pulses generated while passing between the rolls, a delay circuit is provided to ensure accurate passing time when the tip of the rolled material passes between the rolls, and compensates for the delay in the rise of the load relay. It is characterized by things.

The present invention will be explained below based on the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention.

1 is a lower work roll, 2 is an upper work roll, 3 is an upper backup roll, and 4 is a lower backup roll, which are roll groups located at the front stage of the finishing rolling mill. The steel plate 5 passes through the roll group at the front stage and then through the roll group at the rear stage. 6 is a lower work roll, 7 is an upper work roll, 8 is an upper backup roll, and 9 is a lower backup roll, which is a group of rolls located at the rear stage of the finishing mill. IO is a pulse generator that generates N pulses per revolution of the work roll 1. 11 is a load relay, which inserts a steel plate into the front roll group and starts the gate ON signal.

12 is also a load relay, and the steel plate enters the roll group at the front stage and starts the gate OFF signal. 13. ] 4 are delay circuits for gate ON and gate OFF signals, respectively,
The time delay compensation is made so that only one of the load relays 11 and 12 functions due to the difference in the rise time of the load relays 11 and 12.

The time it takes for the load relay to turn on after receiving the signal from the load cell generated when the front stage steel plate enters the front stage is 11.
, and the time it takes for the load relay to turn on after receiving the load cell signal that occurs when a steel plate enters the rear stage.
1+1, 1=1. -1. +, If the load relay rise time difference t determined by is positive, the delay circuit 14 is t.
It is set so that the gate OFF signal is output after t seconds, and if it is negative, the delay circuit 13 is set so that the gate OFF signal is output after t seconds. In this way, the time difference between the rise of the load relay is compensated for, and the pulse counter 16 counts the pulses generated by PLGlO from the time when the gate ON signal is input to the pulse gate 15 until the time when the gate OFF signal is input.

Further, if the number of pulses counted at this time is n, the advance rate can be obtained from (2). In this equation (1), L is the distance between the stands as shown in FIG. 1, and D7 is the diameter of the work roll l as shown in FIG. 1. In addition, when the delay circuits 13 and 14 are not used, if the roll circumferential speed V of the lower work roll l of the previous stage is measured, the number of pulses n in equation (2) can be calculated from the delay circuits 13 and 14.
This is the number of pulses when there is no .

The coefficient of friction between the work roll and the steel plate is determined using the advance ratio determined in this way. To calculate the friction coefficient, the following formula, which was experimentally determined from the relationship with the advance rate, is used.

Here f: Advanced ratio hl: Stand entry side plate thickness h2: Stand exit side plate thickness R', flat roll diameter Here, here R6・Roll radius C: Poisson's ratio (0, 3) E: Roll Young's modulus (21000) P : Rolling load (actual value) W: Plate width Equation (3) is obtained by numerical calculation based on rolling theory of 0Wan, and Equation (4) for determining the flat roll diameter is the well-known Hitchcock equation.

[Example] Figure 2 shows the results of measuring the advance rate without considering the load relay rise time difference and calculating the friction coefficient using formulas (3) and (41). Similarly, when calculating the coefficient of friction using conventional methods, it may become a negative value, a value that cannot physically exist.

According to the present invention, when the advance rate is measured in consideration of the rise time, it is not negative as shown in FIG. 3, and there is no variation in the coefficient of friction due to differences in measurement conditions, making it possible to accurately determine the value.

〔Effect of the invention〕

Theoretically, the ON and OFF signals cannot be detected directly from the load cell signal at the rear stand where the steel plate enters in a kiss-roll state, unless some kind of signal processing is performed by an electric circuit. According to the present invention, the advance rate can be measured very accurately using a load relay signal that does not cause any operational problems, so that the coefficient of friction between the work roll and the strip can be determined with high accuracy. It can also be applied to control the speed of each stand roll to maintain a constant mass flow when setting up a tandem mill.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention, FIG. 2 is a graph showing the friction coefficient determined by the conventional method, and FIG. 3 is a graph showing the friction coefficient determined by the method of the present invention. In Figure 1, 10 is a pulse generator, 11.12 is a load relay, 13.14 is a delay circuit, 15 is a pulse gate, 1
6 is a pulse counter. Applicant Minoru Aoyagi, patent attorney representing Nippon Steel Corporation, 1st prisoner °°. Kuku Ill huan, right?

Claims (1)

[Claims] 1. Using the number of pulses generated per roll rotation in a hot rolling mill and the number of pulses generated while the tip of the rolled material passes between the rolls, when the tip of the rolled material passes between the rolls, A method for measuring an advance rate in a hot rolling mill, which is characterized by providing a delay circuit to make the passing time accurate and compensating for a load relay start-up delay.