JPS5910488B2 - Measuring method of contact pressure distribution between rolling mill rolls - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring contact pressure distribution between rolling mill rolls.

In rolling mill rolls, it is important that the contact pressure distribution between the rolls is always constant; if this is not maintained, the quality and shape of the product will be impaired.

Moreover, the life of the roll is also shortened. -For example, in a quadruple rolling mill where the contact pressure distribution between the work roll and the reinforcing roll becomes uneven, peeling called spalling occurs on the reinforcing roll where a large contact pressure is applied locally, which shortens the life of the roll. It is acknowledged that there has been an extreme decline. The main causes of this non-uniform contact pressure distribution are roll wear, thermal deformation, flexural deformation, etc. however,
To date, no method has been found to measure the contact pressure distribution between assembled rolls. If it were possible to measure the contact pressure distribution between assembled rolls, it would be possible to repair the rolls without significantly increasing the non-uniformity of the contact pressure distribution, extending the life of the rolls. This makes it possible to guarantee the quality and shape of the product.

It will also become useful for estimating rolling mill characteristics and roll wear characteristics. An object of the present invention is to measure the contact pressure distribution between assembled rolling mill rolls so that the rolls can be repaired at an early stage.

The present invention essentially consists in determining the contact pressure distribution by measuring the strain between the rolls installed in the rolling mill using a strain gauge when the rolling mill is stopped.

In this way, the contact pressure distribution between the assembled rolling mill rolls can be measured, and it becomes possible to repair the rolls without significantly increasing the contact pressure. Therefore, the quality and shape of the product can be guaranteed while extending the life of the roll. In the present invention, when the rolling mill is stopped means a state where the rolls are not rotating, and it does not matter whether the rolling operation is in the middle or at the end.

When determining the strain between rolls using a strain gauge, it is desirable to apply a load to the rolls and press the rolls against the strain gauge.

When inserting strain gauges between rolls, a plurality of strain gauges are fixed at predetermined positions on a metal beam.

In this way, the contact pressure distribution between the rolls can be quickly measured. In this case, the metal beam is made of a material whose elastic modulus is equal to or similar to the base material of the strain gauge.

FIG. 1 and FIG. 2 are one embodiment of the present invention, and show the structure of a contact pressure measuring device. The strain gauge 2 is a base material (hereinafter referred to as
pressure gauges), they are made of a metal beam 3 having a modulus of elasticity substantially equal to that of the pressure gauge 1.
embedded within.

The thickness of the pressure measuring element 1 sandwiched between the rolls is approximately equal to the thickness of the metal beam 3 at that position. A lead wire 4 is connected to the strain gauge 2, and the lead wire is drawn out through an outlet 5 provided in the metal beam 3 and connected to a strain measuring meter 6.

Reference numeral 7 denotes a changeover switch which is inevitably required since all the strains of each pressure gauge are measured by one strain measuring meter.

This changeover switch is not necessary if each lead wire is connected to each strain measurement meter. A metal beam 3 in which a pressure gauge 1 with a strain gauge 2 is embedded is inserted between rolling mill rolls so that the pressure gauge 1 is in contact with the roll surface.

3 and 4 show a state in which a metal beam 3 is inserted between a reinforcing roll 8 and a work roll 9 of a quadruple rolling mill. 10 is a material to be rolled.

In this state or when a load is further applied to the roll, strain is applied to the pressure measuring element 1, which is recorded on the strain measuring meter. In order to obtain a contact pressure distribution with high measurement accuracy, it is necessary to apply a load evenly to the entire mouth, and the metal beam 3 that receives this load has a thickness that is sandwiched between the rolls so that the pressure can be measured at that position. It is necessary that the thickness be substantially equal to the thickness of the child 1.

It is desirable that the metal beam 3 has an appropriate width so that it can be stably inserted between the rolls.

As a means for stable insertion, it is also desirable to provide a leaf spring 11 on the side surface of the metal beam 3, as shown in FIG. If there is a gap between the pressure probe 1 and the metal beam 3, or if there is a large difference in the elastic coefficients, this will result in measurement errors, so these differences should be minimized as much as possible.

In particular, the elastic modulus of both should be equal to K, and when the pressure gauge head 1 is made of steel, the metal beam 3 should also be made of steel, and combinations of cast iron and steel, steel, or cast iron and non-ferrous alloys should be avoided. In the case of a steel-to-steel combination, even if the material composition is different, there will not be a large difference in the elastic modulus, so a sufficiently high measurement accuracy can be guaranteed. It is sufficient to attach one strain gauge 2 to the pressure gauge 1.

However, it is more convenient to attach it to both sides of the pressure gauge head for strain adjustment and determination of the load position when no load is applied to the center of the width of the pressure gauge head 1. During use of a rolling mill, it is common to spray cold water onto the rolls.

Therefore, when inserting a metal beam between rolls, it is desirable to apply a moisture-proofing treatment to the strain gauge.
Furthermore, it is particularly desirable to apply moisture-proof coating to the drawer opening. This makes it possible to strengthen the fixation of the lead wire. The measured strain may be used as is to determine the contact pressure between the rolls.

However, since the contact pressure is generally expressed as a linear pressure (load per unit length in the roll axis direction), a method for determining the linear pressure from the measured strain will be described below. When the y coordinate is taken in the tangential direction of X1 in the axial direction of the roll, and a rectangular pressure gauge is used, the size of the pressure gauge is set as A, .
Assuming that b is in the y direction, the load Ps acting on the pressure probe is determined by the following equation.

Here, F(x) and G(y) are X. The number of cocoons represents the contact pressure distribution in the y direction, and w is the contact width between the metal beam and the roll. Furthermore, assuming that HOOke's law holds true between stress and strain, it is also possible to make the axial width a of the pressure probe so small that pressure changes can be ignored, or to consider the average pressure in the width a. For example, G(y) can be obtained by substituting equation (2) into equation (1) with F(x)=constant.

Therefore, the linear pressure P(x) is determined by the following equation. FIG. 6 shows an example of measurement results in a 56-inch quadruple continuous hot rolling mill.

The contact pressure distribution was measured by inserting a metal beam between both rolls as shown in Fig. 3 immediately after the work roll had been used for 3 hours and the reinforcing roll for 6 days, that is, when the rolling mill was stopped.
This was done by applying loads of 500 tons and 1500 tons and measuring the strain applied to the pressure probe.

As a result, as is clear from Figure 6, it was found that the contact pressure at the end of the roll body was abnormally high compared to the center of the body, and it was possible to experimentally prove the spalling phenomenon that occurs at the end of the body. did it.

As is clear from the above description, according to the present invention, the contact pressure distribution between rolling mill rolls can be measured in an assembled state.

This increases the reliability of measurement accuracy. Further, based on the measurement results, it is possible to set an appropriate crown and chamfer, and to determine an economical amount of modification to prevent spalling.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a contact pressure measuring device according to an embodiment of the present invention, FIG. 2 is a front view thereof, FIG. 3 is a front view showing a configuration for measuring contact pressure between rolls, and FIG. 4 is also a side view, FIG. 5 is a side view showing another embodiment of the present invention,
and FIG. 6 is a curve diagram showing a specific example of the measurement results of the contact pressure distribution between rolling mill rolls. Explanation of symbols, 1...Pressure probe, 2...
・Strain gauge, 3...Metal beam, 4...
...Lead wire, 5...Drawer opening, 6...
...Distortion measurement meter.

Claims (1)

[Claims] 1. When the rolling mill is stopped, a plurality of base materials having strain gauges are placed between the rolls installed in the rolling mill, and the elastic modulus is substantially equal to that of the base material, and the thickness is such that it is sandwiched between the rolls. is fixedly inserted at a predetermined position within a metal beam substantially equal to the thickness of the base material at the position, and the strain between the rolls is measured with the strain gauge to determine the contact pressure distribution. A method for measuring the contact pressure distribution between rolling mill rolls.