JPH06103229B2 - Method for measuring rolling roll residual stress - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for measuring an internal residual stress remaining in a quenched rolling roll, and in particular, an end surface of a body is a tapered surface. The present invention relates to a method for measuring residual stress of a rolling roll.

(Prior Art) After forming, a rolling roll is quenched to increase the hardness of the outer peripheral surface of the body. Therefore, it is inevitable that a certain amount of stress remains inside the body. When the residual stress is large, the rolling roll has low durability. Therefore, it is required to measure the residual stress of the quenched rolling roll. In that case, the residual stress needs to be measured without damaging the rolling rolls, ie non-destructively.

As a method of nondestructively measuring the stress, X
There are methods using a linear stress measuring device and magnetism, but they only measure the stress near the very surface of the object, and internal stress measurement is not possible.

As a method for measuring the internal stress of an object, there is a method using ultrasonic waves. This utilizes the fact that when a transverse ultrasonic wave propagates in a stressed elastic body, there is a difference in sound velocity depending on the direction of the stress. The principal stress is obtained by transmitting and receiving two-direction transverse ultrasonic waves and measuring the sound velocity ratio.

Therefore, it is considered to utilize this ultrasonic stress measurement method for measuring the residual stress of the rolling roll.

(Problems to be Solved by the Invention) However, as shown in FIG. 4, both end surfaces 3, 3 of the body portion 2 of the rolling roll 1 are generally tapered surfaces. That is, the end surface 3 is inclined with respect to the axis of the rolling roll 1. For that purpose, a transverse wave probe 4 is provided on the end face 3.
Even if the ultrasonic wave is transmitted by applying the ultrasonic wave, the ultrasonic wave propagates in a direction inclined with respect to the axis of the rolling roll 1. On the other hand, it is known that the residual stress of the hardened rolling roll 1 is small in the radial direction and mainly stress in the circumferential direction. Therefore, in order to measure the residual stress, it is necessary to propagate ultrasonic waves in a direction parallel to the axis of the rolling roll 1 and measure the difference in sound velocity between the transverse wave in the radial direction and the transverse wave in the circumferential direction. There is.

For this reason, conventionally, it has been considered that the ultrasonic stress measurement method cannot be used to measure the residual stress of the rolling roll.

The present invention has been made in view of such circumstances, and an object thereof is to provide a measuring method capable of nondestructively measuring the internal residual stress of a rolling roll by ultrasonic waves.

(Means for Solving the Problem) In order to achieve this object, in the present invention, wedge-shaped members are attached in close contact with the inclined both end surfaces of the rolling roll, and the end surface of each wedge-shaped member is the axis of the rolling roll. Are located on straight lines parallel to each other and are parallel to each other and orthogonal to the axis. The wedge-shaped member is made of a material that propagates ultrasonic waves. Then, while transmitting the transverse ultrasonic wave from the end surface of the one wedge-shaped member and receiving the ultrasonic wave at the end surface of the other wedge-shaped member, the sound velocity of the transverse ultrasonic wave in the radial direction of the rolling roll and the transverse ultrasonic wave in the circumferential direction are transmitted. The residual stress of the rolling roll is calculated from the difference with the sound velocity of the sound wave.

(Operation) With this configuration, since the ultrasonic wave transmission surface is orthogonal to the axis of the rolling roll, the ultrasonic wave propagates in the rolling roll in a direction parallel to the axis. And
Since the ultrasonic waves are received by the end surface of the wedge-shaped member that is orthogonal to the axis of the rolling roll, it is possible to measure the sonic velocities of two transverse ultrasonic waves in the radial direction and the circumferential direction. In that case, since it is transmitted from the end surface of one wedge-shaped member and is received by the end surface of the other wedge-shaped member, the influence of the reflected echo of the ultrasonic wave in the wedge-shaped member is also eliminated.

Further, since the residual stress of the quenched rolling roll is small in the radial direction and large in the circumferential direction, by measuring the sound velocity of the transverse ultrasonic wave in the circumferential direction with reference to the sound velocity of the transverse ultrasonic wave in the radial direction, The residual stress in the circumferential direction can be obtained.

(Examples) Examples of the present invention will be described below with reference to the drawings.

In the drawings, FIG. 1 is an explanatory side view showing a state in which a method for measuring residual stress of a rolling roll according to the present invention is carried out, and FIG. 2 is a front view thereof. Further, FIG. 3 is an explanatory diagram showing the detected ultrasonic waveform.

As shown in FIGS. 1 and 2, a plurality of wedge-shaped members 14 are provided on the inclined end faces 12, 13 of the body 11 of the quenched rolling roll 10 at appropriate intervals in the radial direction. ,14,
...; 15,15, ... are attached. These wedges 1
4, 15 are made of a material that propagates ultrasonic waves, such as steel, and are adhered to the end faces 12, 13 of the body 11 by an adhesive so as to be completely in close contact therewith. The corresponding wedge-shaped members 14 and 15 are
It is located on a straight line parallel to the axis of the rolling roll 10. The end surfaces 14a, 15a of the wedge-shaped members 14, 15 are orthogonal to the axis of the rolling roll 10.

When measuring the residual stress of the rolling roll 10, the transverse wave probes 16 and 17 for transmitting and receiving ultrasonic waves are respectively applied to the end surfaces 14a and 15a of the corresponding wedge-shaped members 14 and 15, and the ultrasonic waves from one probe 16 are applied. To send. Then, the ultrasonic waves are transmitted to the wedge-shaped member 14
Through the inside of the body 11 of the rolling roll 10.
After propagating in the inside in a direction parallel to the axis of the rolling roll 10, it is received by the other probe 17 via the other wedge-shaped member 15. Thus, by transmitting ultrasonic waves from the end surface 14a of the one wedge-shaped member 14 and receiving the ultrasonic waves from the end surface 15a of the other wedge-shaped member 15, the rolling roll 10
Although the wedge-shaped members 14 and 15 which are separate from the above are used, the influence of the reflected echo of the ultrasonic waves in the wedge-shaped members 14 and 15 can be eliminated.

At this time, when the transmitting / receiving probes 16 and 17 are vibrated in the x and y directions shown in FIG. 2, transverse ultrasonic waves in the circumferential direction and the radial direction of the rolling roll 10 are transmitted and received. The shear wave propagation velocity is affected by stress.

The stresses in the x and y directions inside the rolling roll 10 are σ ₁ and σ ₂ , respectively, and the transverse wave sonic speeds in the x and y directions are respectively
If Vr ₁ and Vr ₂ and the velocity of sound when no stress is applied are Vr ₀ , according to the finite deformation elasticity theory, The relationship is established. Here, C _A is a sonoelastic constant, and if the rigidity is μ and the third-order elastic coefficient is ν ₃ , It is represented by.

Therefore, when there is a difference in stress between the x direction and the y direction, the ultrasonic wave transmitted from the probe 16 is received by the probe 17 as a transverse wave in the x direction and the y direction with a time lag. Become. In the case of the hardened rolling roll 10, since the residual stress in the radial direction is small and the stress in the circumferential direction is large, the transverse wave in the x direction is slower than the transverse wave in the y direction, and as shown in FIG. When the ultrasonic wave p is transmitted from the probe 16, a waveform such as x and y is detected in the probe 17.

Here, in general, the residual stress of the quenched rolling roll 10 in the radial direction, that is, the y direction is extremely small at 5 kg / mm ² or less, so if this is ignored, Vr ₂ = Vr ₀ σ ₂ = 0 in the above equation, Becomes

Therefore, the residual stress inside the rolling roll 10 can be estimated by measuring the sound velocity of the transverse wave in the x direction with reference to the sound velocity of the transverse wave in the y direction and obtaining the difference or ratio.

(Effects of the Invention) As is apparent from the above description, according to the present invention, wedge-shaped members are attached to the inclined both end surfaces of the body of the rolling roll, and the end surfaces of the wedge-shaped members are parallel to each other. Therefore, by transmitting ultrasonic waves from the end surface of one wedge-shaped member, it becomes possible to receive transverse wave ultrasonic waves in the radial direction and the circumferential direction of the rolling roll at the end surface of the other wedge-shaped member. Moreover, by transmitting the ultrasonic wave from one end face and receiving the ultrasonic wave at the other end face in this way, it is possible to prevent the influence of the reflection echo of the ultrasonic wave by the wedge-shaped member. Then, since the acoustic velocity of the transverse ultrasonic wave in the radial direction of the rolling roll and the acoustic velocity of the transverse ultrasonic wave in the circumferential direction are measured in this manner, the internal stress of the rolling roll can be obtained based on the measured velocity.

In this way, it becomes possible to measure the residual stress of the quenched rolling roll nondestructively.

[Brief description of drawings]

FIG. 1 is a schematic side view for explaining a state in which a method for measuring residual stress of a rolling roll according to the present invention is carried out, FIG. 2 is a front view thereof, and FIG. 3 shows a waveform detected by the method. Explanatory drawing, FIG. 4 is a side view of the rolling roll for demonstrating the conventional problem. 10 ... Rolling roll, 11 ... Body 12,13 ... Body end surface 14,15 ... Wedge-shaped member 14a, 15a ... Wedge-shaped end surface 16,17 ... Transverse wave probe

Claims (1)

[Claims] 1. A wedge-shaped member made of a material for propagating an ultrasonic wave is brought into close contact with a portion of each of the inclined both end surfaces of the body of a quenched rolling roll, which is located on a straight line parallel to the axis of the rolling roll. The wedge-shaped members so that the end surfaces of the wedge-shaped members are parallel surfaces orthogonal to the axis of the rolling roll, and ultrasonic waves are transmitted from the end surface of one of the wedge-shaped members.
The ultrasonic wave is received at the end face of the other wedge-shaped member, and the residual stress of the rolling roll is obtained from the difference between the acoustic velocity of the transverse ultrasonic wave in the radial direction of the rolling roll and the acoustic velocity of the transverse ultrasonic wave in the circumferential direction. And the method for measuring residual stress of rolling rolls.