JPH05281201A - Method and apparatus for measurement of depth of quenched and hardened layer - Google Patents

Abstract

PURPOSE:To obtain a method wherein the depth of the quenched and hardened layer of forged steel or the like is measured non-destructively. CONSTITUTION:In the measuring method of the depth of a quenched and hardened layer, concentric and arbitrary multiple layers are set around the axial center in the circular cross section of a cylindrical object 1, under test, on which a quenched and hardened layer 2 has been formed in an outer-shell part. The attenuation rate of ultrasonic waves in a first layer is found from the following: the reception energy of ultrasonic beams which are transmitted in the chord direction of a depth corresponding to the depth (d1) of the first layer in the outermost layer of said object 1 under test; and the route length (between T and R) of a propagated chord. The attenuation rate of individual layers is found sequentially from the following in the same manner: the reception energy of ultrasonic beams corresponding to depths (d2), (d3) of the individual layers; and the route length of chords. The depth of the quenched and hardened layer 2 is estimated from the depth of a layer in which the attenuation rate of the ultrasonic beams is increased sharply.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nondestructive hardened layer measuring method and apparatus for nondestructively measuring the depth (boundary portion) of a hardened layer of an object whose outer shell is quench hardened.

[0002]

2. Description of the Related Art In a forged steel roll for rolling, etc., the depth of the quench-hardened layer on the surface affects the life of the roll, and therefore it is important to measure this depth from the viewpoint of quality assurance.

The depth of the hardened layer is measured by the conventional electromagnetic measurement method only on the surface layer of the sample or from the surface.
It was possible to measure only a relatively shallow portion of about 20 mm. Further, according to the method described in Japanese Patent Publication No. 63-26340, the distribution of the hardened layer can be measured with relatively high accuracy, but it takes a long time for the measurement, and particularly for the deep hardened layer, it takes time. I have a tendency to pass.

[0004]

DISCLOSURE OF THE INVENTION The object of the present invention is to eliminate the above-mentioned drawbacks and a method for non-destructively measuring the depth of a hardened layer in a relatively wide range from the surface layer portion to the inner layer portion of an object. The equipment is provided.

[0005]

[Means for Solving the Problems] The characteristics of ultrasonic waves were investigated using a forged steel roll cut test material whose surface layer was quenched and hardened as a test object. As a result, as shown in the schematic diagram of FIG. A rapid attenuation of ultrasonic waves was observed at the boundary with the uncured layer inside. As a result of investigating the relationship between the hardness distribution of the cross section and the attenuation factor of ultrasonic waves using the forged steel roll cut test material, as shown in FIG. 2, the quench hardened layer in which the hardness sharply decreases and the internal non-hardened layer A rapid attenuation of ultrasonic waves was observed at the boundary of the layers.

The present invention pays attention to this characteristic, devises so that the attenuation factor of the ultrasonic wave propagating in the object can be obtained in the depth direction, and the quench hardening layer and the non-hardening layer are determined from the change of the attenuation factor. The depth of the hardened layer is estimated by measuring the boundary part between and, and the summary is as follows.

(1) Arbitrary multiple layers concentric to the axis of the circular cross-section of a cylindrical object having a quench-hardened layer formed on the outer shell are set, and the first outermost layer of the object is The attenuation factor of the ultrasonic wave in the first layer is calculated from the received energy of the ultrasonic beam transmitted in the chord direction of the depth corresponding to the depth and the path length of the propagating chord, and the depth of each layer is sequentially determined by the same method. Quenching to estimate the depth of the quench hardening layer from the depth of the layer where the attenuation rate of the ultrasonic beam increases sharply by obtaining the attenuation rate of each layer from the received energy of the corresponding ultrasonic beam and the path length of the propagated string Hardened layer depth measurement method.

(2) An ultrasonic wave transmitting / receiving unit for transmitting / receiving ultrasonic waves, a wave transmitter for transmitting an ultrasonic beam into the subject by a transmission pulse from the ultrasonic wave transmitting / receiving unit, and an ultrasonic wave propagating in the subject. A holder that includes a wave receiver that receives a sound wave beam, and the ultrasonic wave beam is a holder that installs the wave transmitter and the wave receiver so that the ultrasonic wave penetrates a layer having an arbitrarily set depth in the subject, and the wave transmitter and A path length calculation unit that calculates the path length of the ultrasonic beam that has entered the subject from the relative position of the wave receiver, a received energy calculation unit that calculates the received energy from the received signal of the wave receiver, and An attenuation rate calculator for calculating the attenuation rate of the energy based on the output of the received energy calculator and the output of the path length calculator, and a memory section capable of recording and reading the attenuation rate of the energy calculated by the attenuation rate calculator. Equipped with Quench hardened layer depth of the measuring device.

By the way, in an object having a cylindrical surface such as a rolling roll, as shown in FIG. 3, the hardened layer 2 is distributed substantially concentrically with respect to the axis O of the object 1.
The hardest part is near the surface, and the hardness decreases as it approaches the axis O, and the boundary part (k layer) between the quench-hardened layer 2 and the non-hardened layer 3
The hardness tends to decrease sharply.

On the other hand, the rolling roll has a considerable length in the axial direction, and the end face of the roll is affected by the heat treatment effect, and the state of the hardened layer of all rolls cannot be known only from the information of the end of the roll. Can not.

Therefore, in the case of such a cylindrical object, the multiple layers (I,
II, III ...), so that the ultrasonic beam emitted from the wave transmitter is received by the wave receiver through a portion of the desired depth (d) in the object 1 to be transmitted. And the distance between the wave receivers can be arbitrarily set, and they are installed at two points T and R on the circumferential surface of the subject 1 to a desired depth (d).
The ultrasonic attenuation factor in the chord direction (between T and R) at is obtained.
The boundary portion (k) can be estimated from the distance between T and R at which the ultrasonic attenuation factor becomes the largest, and the depth d of the hardened layer can be obtained nondestructively.

[0012]

The hardened layer of the solid roll is the second layer, the third layer ,.
The attenuation factor of the ultrasonic wave propagating through the string (TR in FIG. 3) penetrating each of the layers is measured. The pitch of each layer from the 1st layer to the nth layer shall be set arbitrarily, and in particular, the pitch should be fine in the vicinity of the boundary layer between the quench-hardened layer and the non-hardened layer, and the pitch should be made coarse in other areas to shorten the measurement time. Measure

In the layer corresponding to the boundary layer between the quench-hardened layer and the non-hardened layer (layer k in FIG. 3), the attenuation rate of the ultrasonic waves transmitted in the chord direction is the largest, so the boundary layer is estimated from this. The depth of the hardened layer can be obtained.

[0014]

EXAMPLES The present invention will now be described based on examples.

FIG. 4 is characterized in that a converging type transmitting element 4 and a receiving element 5 in which a concave vibrator having a converging point of an ultrasonic beam is incorporated on the surface of the subject 1 are used.

According to this apparatus, the ultrasonic beam is focused on the surface of the subject 1, so that the path length in the subject 1 from the incident point to the wave receiver can be accurately measured. In addition, since the ultrasonic beam is diffused in the subject 1 and propagates through the layers of each depth, the incident angle of the focusing type transmitter 4 and the receiver 5 is changed each time when the attenuation rate of the ultrasonic wave is obtained. It is not necessary to do so, and moreover, both can be positioned with high accuracy.

FIG. 5 is a schematic view showing an embodiment of a measuring device capable of non-destructive hardened layer depth measurement. In the figure, both are covered by a holder 6 so that the ultrasonic beam emitted from the focusing type transducer 4 passes through a position of a desired depth in the subject 1 and is received by the focusing type transducer 5. It is held on the circumferential surface of the sample 1.

The ultrasonic beam emitted from the focusing type transmitter 4 in response to the received pulse from the ultrasonic transmitting / receiving section 7 is once focused at the incident point T of the subject 1 and then diffused in the subject 1. Of these, the ultrasonic beam heading to the wave receiving point Rn of the focusing type wave receiver 5 is received and is input to the full-wave rectifying circuit 8 via the amplification circuit of the ultrasonic wave transmitting / receiving unit 7. Since the ultrasonic waveform is a double swing amplitude waveform, the full-wave rectification circuit unit 8 full-wave rectifies and outputs the received ultrasonic waveform, and the next ultrasonic attenuation rate calculation unit 1
Input to 0.

On the other hand, the path length calculation unit 9 inputs the radius r of the subject 1 and the maximum depth d within the path length of the ultrasonic beam, and geometrically calculates the path length in each layer to obtain an electric value. When the path length is output automatically as a signal, and the path length is automatically calculated in conjunction with the set positions of the focusing type transmitter 4 and the wave receiver 5, an electric signal corresponding to the set interval L and the set angle θ is output by a potentiometer or the like. It is also possible to take out the data and calculate it in the path length calculation unit 9. The attenuation rates of the ultrasonic waves from the first layer to the nth layer are all stored in the memory unit 11 and output as needed. Then, the position of the change point of the attenuation rate in the depth direction is obtained from this output display, the quench hardening boundary layer is obtained, and the depth of the hardened layer is obtained.

[0020]

As described above, according to the present invention, the depth of the hardened layer can be easily and quickly measured in a wide range from the surface layer to the inside without damaging the specimen at all. Excellent as a means.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a relationship between a cross-sectional condition of a roll test material and an ultrasonic attenuation rate.

FIG. 2 is a graph showing the relationship between the hardness distribution of a roll test material and the ultrasonic attenuation rate.

FIG. 3 is a schematic diagram showing a distribution state of a hardened layer of a subject having a cylindrical cross section.

FIG. 4 is a schematic diagram illustrating a method of measuring a hardened layer by ultrasonic waves according to an embodiment of the present invention.

FIG. 5 is a conceptual diagram of an ultrasonic hardening layer measuring apparatus according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Subject, 2 ... Quench hardening layer, 3 ... Non-hardening layer, 4 ... Focusing type | formula wave element, 5 ... Focusing type wave element, 6 ... Holding tool, 7 ...
Ultrasonic wave transmission / reception unit, 8 ... Full wave rectification circuit unit, 9 ... Path length calculation unit, 10 ... Ultrasonic attenuation factor calculation unit, 11 ... Memory unit.

Front Page Continuation (72) Inventor Hirotoshi Kino 650, Kazunachi-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. FA Factory Department

Claims (2)

[Claims] 1. An arbitrary multi-layer concentric with the axis of a circular cross-section of a cylindrical test object having a quench-hardened layer formed on the outer shell thereof, and the depth of the first layer of the outermost surface of the test object is set. The attenuation factor of the ultrasonic wave in the first layer is calculated from the received energy of the ultrasonic beam transmitted in the chord direction of the depth corresponding to the depth and the path length of the propagating chord, and the depth of each layer is sequentially corresponded by the same method. The attenuation rate of each layer is calculated from the received energy of the ultrasonic beam and the path length of the propagated string, and the depth of the quench hardening layer is estimated from the depth of the layer where the attenuation rate of the ultrasonic beam rapidly increases. Characteristic method for measuring the depth of quench hardened layer. 2. An ultrasonic wave transmitting / receiving unit for transmitting and receiving ultrasonic waves, a wave transmitter for transmitting an ultrasonic beam into a subject by a transmission pulse from the ultrasonic wave transmitting / receiving unit, and an ultrasonic wave propagated in the subject. A holder for receiving the beam, and a holder for installing the wave transmitter and the wave receiver so that the ultrasonic beam penetrates a layer having an arbitrarily set depth in the subject, and the wave transmitter and the wave receiver. A path length calculation unit that calculates the path length of the ultrasonic beam that has entered the subject from the relative position of the wave element, a reception energy calculation unit that calculates the received energy from the received signal of the wave receiver, and the reception An attenuation rate calculation section for calculating the attenuation rate of the energy based on the output of the energy calculation section and the output of the path length calculation section; and a memory section capable of recording and reading the attenuation rate of the energy calculated by the attenuation rate calculation section. Having prepared Quench hardened layer depth of the measuring device according to claim.