JP7124744B2 - Residual stress estimation device, residual stress estimation method, program and quality control method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus and method for estimating the residual stress on the inner surface of a cylindrical member, a program for realizing them, and a cylindrical member quality control method using the apparatus.

Cylindrical members such as fuel injection pipes for diesel engines, which are used under high pressure, are required to have high fatigue strength. As a method for improving the fatigue strength of such a cylindrical member, self-tightening treatment is known. The self-stressing process is a process in which excessive internal pressure is applied to partially plastically deform the vicinity of the inner surface of the cylindrical member to generate compressive residual stress.

In order to properly manage the quality of self-sealed cylindrical members, it is necessary to know how much residual stress is generated on the inner surface of the cylindrical members by the self-sealing treatment. be. Conventionally, a method has been proposed for measuring the residual stress of a cylindrical member that has been subjected to self-stressing treatment (see, for example, Patent Document 1).

In the residual stress measuring method disclosed in Patent Document 1, the relationship between the amount of dimensional change of the object to be processed before and after self-stressing treatment and the residual stress (hereinafter referred to as a master curve) is known in advance. Then, the dimensional change amount of the object to be treated (hereinafter referred to as the object to be measured) having the same material as the object to be treated is measured before and after the self-heating process, and based on the measured dimensional change amount and the master curve, measurement is performed. Residual stresses of interest are estimated.

According to the method disclosed in Patent Document 1, if an appropriate master curve is created, it is possible to easily estimate the residual stress of the object to be measured based on the amount of dimensional change before and after self-tightening treatment of the object to be measured. Conceivable.

JP-A-4-24528

Edited by The Society of Materials Science, Japan, "X-ray Stress Measurement Standards (2002 Edition) - Iron and Steel Edition", March 2002

However, with current technology, it is difficult to actually measure the residual stress on the inner surface of the cylindrical member without dividing the cylindrical member. is difficult. For this reason, it is difficult to appropriately estimate the residual stress on the inner surface of the cylindrical member with the method of Patent Document 1, which estimates the residual stress based only on the master curve and the amount of dimensional change.

Therefore, the present invention provides a residual stress estimating device, a residual stress estimating method and program, and a quality control system using the residual stress estimating device, which can appropriately estimate the residual stress on the inner surface of a cylindrical member after self-heating treatment. It is intended to provide management methods.

The gist of the present invention is the following residual stress estimating device, residual stress estimating method, program and quality control method.

(1) A device for estimating the residual stress of a cylindrical member after self-heating treatment,
Measured value of residual stress on the outer surface of the cylindrical member after self-strengthening treatment, measured value of residual stress on the outer surface of the cylindrical member after self-straightening treatment and after halving, and after self-strengthening treatment and after halving an acquisition unit that acquires a measured value of residual stress on the inner surface of the cylindrical member;
The residual stress on the outer surface of the cylindrical member after self-strengthening treatment, the residual stress on the inner surface of the cylindrical member after self-strengthening treatment, the residual stress on the inner surface of the cylindrical member after self-strengthening treatment, and the residual stress after self-strengthening treatment and half The relationship between the residual stress on the outer surface of the cylindrical member after splitting, the residual stress on the inner surface of the cylindrical member after self-strengthening treatment and after splitting in half, and the measured value of each residual stress obtained by the obtaining unit an estimating unit for estimating the residual stress on the inner surface of the cylindrical member after the self-cooling treatment, based on
A residual stress estimator.

(2) the relationship is obtained using analytical models of a plurality of cylindrical members having different dimensions, and is associated with information about the dimensions of the cylindrical members;
The acquisition unit further acquires information about the dimensions of the cylindrical member,
The estimating unit estimates the residual stress of the inner surface of the cylindrical member after the self-straining treatment based on the information on the dimensions and the measured value of each residual stress acquired by the acquiring unit, and the relationship. , the residual stress estimating device according to the above (1).

(3) The residual stress estimating device according to (2) above, wherein the information on the dimensions is information on the outer diameter and the inner diameter of the cylindrical member.

(4) Any one of (1) to (3) above, further comprising a determination unit that determines whether the residual stress of the inner surface estimated by the estimation unit satisfies preset residual stress conditions. The residual stress estimating device according to .

(5) A method for estimating the residual stress of a cylindrical member after self-heating treatment by a computer,
(a) Measured value of residual stress on the outer surface of the cylindrical member after self-strengthening treatment, measured value of residual stress on the outer surface of the cylindrical member after self-straightening treatment and after halving, and after self-straightening treatment and half obtaining a measured value of the residual stress on the inner surface of the cylindrical member after splitting;
(b) the residual stress on the outer surface of the cylindrical member after the self-sealing treatment, the residual stress on the inner surface of the cylindrical member after the self-sealing treatment, and the self-sealing treatment obtained in advance using the analytical model of the cylindrical member; The relationship between the residual stress on the outer surface of the cylindrical member after halving and the residual stress on the inner surface of the cylindrical member after self-strengthening treatment and after halving, and each residual obtained in step (a) estimating the residual stress on the inner surface of the cylindrical member after the self-stressing treatment, based on the measured value of the stress;
A residual stress estimation method comprising:

(6) the relationship is obtained using analytical models of a plurality of cylindrical members having different dimensions, and is associated with information about the dimensions of the cylindrical members;
In step (a), further obtaining information about the dimensions of the cylindrical member;
In the step (b), the inner surface of the cylindrical member after the self-stressing treatment is determined based on the information on the dimensions and the measured values of each residual stress obtained in the step (a), and on the basis of the relationship. The residual stress estimation method according to (5) above, which estimates the residual stress of

(7) The residual stress estimation method according to (6) above, wherein the information on the dimensions is information on the outer diameter and the inner diameter of the cylindrical member.

(8) (c) further comprising a step of determining whether the residual stress on the inner surface estimated in step (b) satisfies preset residual stress conditions, from (5) to ( 7) The method for estimating residual stress according to any one of items.

(9) In order to estimate the residual stress of the cylindrical member after self-heating treatment, the computer
(a) Measured value of residual stress on the outer surface of the cylindrical member after self-strengthening treatment, measured value of residual stress on the outer surface of the cylindrical member after self-straightening treatment and after halving, and after self-straightening treatment and half obtaining a measured value of the residual stress on the inner surface of the cylindrical member after splitting;
(b) the residual stress on the outer surface of the cylindrical member after the self-sealing treatment, the residual stress on the inner surface of the cylindrical member after the self-sealing treatment, and the self-sealing treatment obtained in advance using the analytical model of the cylindrical member; The relationship between the residual stress on the outer surface of the cylindrical member after halving and the residual stress on the inner surface of the cylindrical member after self-strengthening treatment and after halving, and each residual obtained in step (a) estimating the residual stress on the inner surface of the cylindrical member after the self-stressing treatment, based on the measured value of the stress;
The program that causes the to run.

(10) the relationship is obtained using analytical models of a plurality of cylindrical members having different dimensions, and is associated with information regarding the dimensions of the cylindrical members;
In step (a), further obtaining information about the dimensions of the cylindrical member;
In the step (b), the inner surface of the cylindrical member after the self-stressing treatment is determined based on the information on the dimensions and the measured values of each residual stress obtained in the step (a), and on the basis of the relationship. The program according to (9) above, which estimates the residual stress of

(11) The program according to (10) above, wherein the information on dimensions is information on an outer diameter and an inner diameter of the cylindrical member.

(12) to the computer,
(c) determining whether or not the residual stress on the inner surface estimated in step (b) satisfies a preset residual stress condition; (9) to (11) A program as described in any of

(13) (A) a step of subjecting the cylindrical member to a self-stressing process;
(B) a step of actually measuring the residual stress on the outer surface of the cylindrical member that has been subjected to self-stress treatment in step (A);
(C) After halving the cylindrical member that has undergone the self-stressing treatment in step (A), measuring the residual stress on the outer and inner surfaces of the halved cylindrical member;
(D) Using the residual stress estimating apparatus according to any one of claims 1 to 4, the residual stress on the inner surface of the cylindrical member that has been subjected to the self-straining treatment in step (A) is estimated by using the residual stress estimator according to (B) and A step of estimating from each residual stress actually measured in step (C);
(E) a step of adjusting conditions for self-stressing treatment of other cylindrical members based on the residual stress estimated in step (D);
A method for quality control of a cylindrical member, comprising:

ADVANTAGE OF THE INVENTION According to this invention, the residual stress of the inner surface of the cylindrical member after self-heating treatment can be estimated appropriately, and the appropriate quality control of a cylindrical member is attained.

FIG. 1 is a diagram showing a schematic configuration of a residual stress estimating device according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of a cylindrical member after self-stressing, the residual stress of which is estimated by the estimation device. FIG. 3 is a block diagram specifically showing the configuration of the estimation device according to one embodiment of the present invention. FIG. 4 is a diagram for explaining a method of deriving a multivariable function. FIG. 5 is a diagram for explaining a method of deriving a multivariable function. FIG. 6 is a diagram for explaining a method of deriving a multivariable function. FIG. 7 is a diagram for explaining a method of deriving a multivariable function. FIG. 8 is a diagram for explaining a method of deriving a multivariable function. FIG. 9 is a flowchart showing the operation of the estimation device according to this embodiment. FIG. 10 is a block diagram showing an example of a computer that implements an estimation device according to one embodiment of the present invention.

Conventionally, the inventors of the present invention cut the cylindrical member after the self-heating treatment in half, and measured the residual stress on the inner surface of the cylindrical member after the half-halving for the quality control of the self-heating-treated cylindrical member. By measuring , the residual stress on the inner surface of the cylindrical member after self-heating treatment was relatively evaluated. Note that cutting in half means cutting the cylindrical member so that the cylindrical member is divided into two arcuate members when viewed from the axial direction.

However, in order to more appropriately manage the quality of the cylindrical member, it is preferable to quantitatively evaluate the residual stress on the inner surface of the cylindrical member after self-stressing treatment and before halving. Therefore, the present inventors have been researching a method for quantitatively evaluating the residual stress on the inner surface of a cylindrical member. In the study, the present inventors considered the residual stress on the outer surface of the cylindrical member before and after halving in addition to the residual stress on the inner surface of the cylindrical member after halving. In addition, evaluation of the residual stress on the inner surface of the cylindrical member before halving was examined.

The present inventors first performed numerical analysis (FEM analysis) under various conditions using an analytical model of a cylindrical member to be evaluated, and found that the residual stress ( calculated value). Specifically, the present inventors, first, numerically analyzed the residual stress σ _o1 on the outer surface of the cylindrical member after self-strengthening treatment and before halving, The residual stress σ _i1 on the inner surface, the residual stress σ _o2 on the outer surface of the cylindrical member after self-strengthening treatment and after halving, and the residual stress σ _i2 on the inner surface of the cylindrical member after self-strengthening treatment and after halving were determined. .

As a result of detailed examination of each residual stress obtained as described above, the present inventors found that the residual stress σ _i1 on the inner surface of the cylindrical member before halving is It was found that the residual stress σ _o1 on the outer surface, the residual stress σ _o2 on the outer surface of the halved cylindrical member, and the residual stress σ _i2 on the inner surface of the halved cylindrical member were used.

The present invention has been made based on the above findings. A residual stress estimation device, a residual stress estimation method, a program, and a quality control method according to embodiments of the present invention will be described below with reference to the drawings.

[Device configuration]
FIG. 1 is a diagram showing a schematic configuration of a residual stress estimating device according to an embodiment of the present invention. As shown in FIG. 1 , a residual stress estimation device 10 (hereinafter abbreviated as estimation device 10 ) according to this embodiment includes an acquisition unit 12 and an estimation unit 14 .

FIG. 2 is a diagram showing an example of a cylindrical member after self-straining treatment whose residual stress is estimated by the estimating device 10. As shown in FIG. In FIG. 2, (a) is a left side view of the cylindrical member 20 subjected to the self-sealing treatment, (b) is a front view of the cylindrical member 20 shown in (a), and (c). (a) is a left side view of a half sample 22 obtained by cutting the cylindrical member 20 shown in (a), and (d) is a front view of the half sample 22 shown in (c). In this specification, the term "cylindrical member after halving" means a halved sample obtained by halving a cylindrical member after self-strengthening treatment.

1 and 2, in the present embodiment, the residual stress σ _o1 of the outer surface 20a of the cylindrical member 20 after self-heating treatment, the residual stress σ _o2 of the outer surface 22a of the halved sample 22, and the halved sample Measured values of the residual stress σ _i2 of the inner surface 22 b of 22 are input to the estimating device 10 by the user and acquired by the acquiring unit 12 . In this embodiment, residual stress means residual stress in the circumferential direction of the cylindrical member 20 .

Referring to FIG. 2, the length L of the cylindrical member 20 when measuring the residual stress is preferably three times or more the outer diameter D of the cylindrical member 20, and can be, for example, about 30 mm. . When the cylindrical member 20 is cut in half, excessive heat generated due to the cutting affects the residual stress on the inner surface. For this reason, it is necessary to adopt a cutting method that generates as little heat as possible, and it is preferable to cut in half by wire-cut electrical discharge machining. At this time, in the side view of the half-divided sample 22, the distance X between the cut surface 22c of the half-divided sample 22 and the center of the outer surface 22a (the distance in the direction perpendicular to the cut surface 22c) is the radius r of the cylindrical member 20. It is preferable to control the range within ±5%.

The measurement of the residual stress is performed after removing the surface layer of the outer surface 20a of the cylindrical member 20 and the inner surface 22b of the half-split sample 22 in the range of 10 μm or less by electropolishing. As a measuring method, the sin ² ψ method by X-ray diffraction can be used, and the measurement can be performed in conformity with Non-Patent Document 1.

The estimating unit 14, based on the relationship obtained in advance using the analytical model of the cylindrical member 20 and the measured values of the residual stresses σ _o1 , σ _o2 , and σ _i2 obtained by the obtaining unit 12, , the residual stress σ _i1 of the inner surface 20b of the cylindrical member 20 is estimated. The above relationship is pre-stored, for example, in a storage device (not shown) included in the estimating device 10 or a storage device (not shown) connected to the estimating device 10 . In the present embodiment, the estimation unit 14 uses, for example, a function representing the relationship between the residual stress σ _i1 and the residual stresses σ _o1 , σ _o2 , and σ _i2 to obtain the residual stresses σ _o1 , σ An estimated value of the residual stress σ _i1 is calculated from the measured values of _o2 and σ _i2 . More specifically, the estimation unit 14 calculates the residual stress σ _i1 using, for example, a multivariable function whose variables are the residual stresses σ _o1 , σ _o2 and σ _i2 . The multivariable function used by the estimation unit 14 will be described later.

As described above, in the estimation device 10 according to the present embodiment, the relationship between the residual stress σ _i1 and the residual stresses σ _o1 , σ _o2 , and σ _i2 obtained by the numerical analysis using the analysis model, and the residual stress σ _o1 , σ _o2 , σ _i2 are used to calculate an estimate of the residual stress σ _i1 . In this case, the residual stress σ _i1 of the inner surface 20b of the cylindrical member 20, which is difficult to measure, can be obtained from the residual stresses σ _o1 , σ _o2 , and σ _i2 that can be measured by using the above relationship obtained by appropriate numerical analysis. can be properly estimated. As a result, the user can use the estimated value of the residual stress σ _i1 calculated by the estimating device 10 to appropriately manage the quality of the cylindrical member 20 that has undergone the self-stressing process.

Next, a specific configuration of the estimation device 10 will be described. FIG. 3 is a block diagram specifically showing the configuration of the estimation device according to one embodiment of the present invention.

As shown in FIG. 3 , the estimation device 10 further includes a determination unit 16 and an output unit 18 in addition to the acquisition unit 12 and the estimation unit 14 described above.

2 and 3, in this embodiment, in addition to the measured values of the residual stresses σ _o1 , σ _o2 , and σ _i2 , information on the dimensions of the cylindrical member 20 (in this embodiment, the outer diameter D and the inner diameter d) are input to the estimating device 10 and acquired by the acquiring unit 12 .

The estimating unit 14 obtains the relationship obtained in advance using the analytical model of the cylindrical member 20, the measured values of the residual stresses σ _o1 , σ _o2 , and σ _i2 obtained by the obtaining unit 12, and information about the dimensions of the cylindrical member 20. (In this embodiment, the residual stress σ _i1 of the inner surface 20b of the cylindrical member 20 is estimated based on the outer diameter D and the inner diameter d). In the present embodiment, the above relationship is obtained using analytical models of a plurality of cylindrical members 20 having different dimensions, and is associated with information on the dimensions of the cylindrical member 20 (the outer diameter D and the inner diameter d). there is In this embodiment, the estimating unit 14 uses, for example, residual stresses σ _o1 , σ _o2 , σ _i2 and values related to the dimensions of the cylindrical member 20 (in this embodiment, the outer diameter D and the inner diameter d) as variables. Calculate the residual stress σ _i1 using the function The multivariable function used by the estimation unit 14 will be described later.

The determination unit 16 determines whether or not the estimated value of the residual stress σ _i1 calculated by the estimation unit 14 satisfies preset conditions for the residual stress σ _i1 . In this embodiment, the condition of the residual stress σ _i1 means the range of the residual stress σ _i1 that should be generated on the inner surface 20 b of the cylindrical member 20 . The condition of the residual stress σ _i1 is determined based on past experience, and may be input by, for example, a user of the estimation device 10, and may be stored in a storage device (not shown) included in the estimation device 10 or connected to the estimation device 10. It may be stored in advance in a storage device (not shown).

The output unit 18 outputs the result of determination by the determination unit 16 . In the present embodiment, the output unit 18 outputs, for example, the determination result of the determination unit 16 to a display device (not shown) connected to the estimation device 10 . The determination result by the determining unit 16 includes the difference between the estimated value of the residual stress _σi1 calculated by the estimating unit 14 and the preset range of the residual stress _σi1 , the adjustment amount of the self-treatment pressure, and the like. may be included.

As described above, in the estimation device 10 according to the present embodiment, using the residual stresses σ _o1 , σ _o2 , and σ _i2 that can be actually measured, the outer diameter D of the cylindrical member 20, and the inner diameter d of the cylindrical member 20, , the residual stress σ _i1 of the inner surface 20b of the cylindrical member 20, which is difficult to measure, can be estimated. That is, the estimation device 10 according to this embodiment can estimate the residual stress σ _i1 of the inner surface 20b of the cylindrical member 20 of various dimensions. Therefore, the user can use the estimated value of the residual stress _σi1 calculated by the estimating device 10 to appropriately manage the quality of the cylindrical members 20 of various dimensions that have undergone the self-stressing process. .

[Multi-variable function]
An example of how to find the multivariable function used by the estimation unit 14 will be described below. In the following, the case of calculating the estimated value of the residual stress σ _i1 using a multivariable function with the residual stresses σ _o1 , σ _o2 , σ _i2 , the outer diameter D, and the inner diameter d as variables will be described.

In this embodiment, a multivariable function representing the residual stress σ _i1 is obtained by numerical analysis. Specifically, as shown in FIG. 4A, an arc-shaped analysis model 40 (1 /4 model). Although illustration is omitted, the analysis model 40 is divided into a plurality of elements (mesh). The physical property values of the analysis model 40 may be appropriately set according to the material of the cylindrical member 20. FIG. In this embodiment, the analytical model 40 is, for example, an elastic body.

First, in order to simulate the cylindrical member 20, as shown in FIG. 4B, constraint conditions are set so as to restrict the movement of both ends 40a and 40b in the circumferential direction of the analysis model 40. do. After that, as the initial state, a volumetric force that simulates the state of the cylindrical member 20 during the self-consistent treatment is set. Specifically, in the initial state, the inner surface 40c of the analysis model 40 is given a circumferential compressive residual stress (eg, -100 MPa). In the initial state, it is assumed that no stress is generated in a region between the outer surface 40d and the position P (the position indicated by the arc-shaped dashed line) separated in the radial direction of the analysis model 40 from the inner surface 40c. Furthermore, in the initial state, the stress distribution in the region between the inner surface 40c and the position P was linear such that the compressive stress gradually decreased from the inner surface 40c toward the position P. FIG. 4(b) and FIGS. 5 and 6, which will be described later, show the stress state at the end portion 40b. Hereinafter, the distance in the radial direction between the point P1 at which the compressive stress becomes zero on the end portion 40b and the inner surface 40c is referred to as the distance t, and the thickness of the analysis model 40 is referred to as the thickness T.

After installing the body forces as described above, an elastic analysis is performed to redistribute the stresses. This changes the stress state of the analysis model 40, for example, as shown in FIG. In addition, in FIG. 5, the position where the stress is 0 is indicated by a dashed line. A circumferential compressive stress is generated in the area inside the dashed line, and a circumferential tensile stress is generated in the area outside the dashed line. In the state shown in FIG. 5, the integrated value of the stress distribution of the entire analytical model 40 is zero. The stress state shown in FIG. 5 corresponds to the stress state of the cylindrical member 20 after the self-stressing treatment. In this embodiment, in the state _shown in FIG. The stress at the point of intersection with the portion 40b is obtained as the residual stress _σo1 of the outer surface 20a of the cylindrical member 20 after the self-strengthening treatment.

Next, in order to simulate the halved sample 22 (the cylindrical member 20 after halving), as shown in FIG. This further changes the stress state of the analytical model 40 . In addition, in FIG. 6, the position where the stress is 0 is indicated by a dashed line. In the example shown in FIG. 6, in the analysis model 40, tensile stress in the circumferential direction is generated in the central portion in the radial direction. directional compressive stress is generated. In the analysis model 40 shown in FIG. 6, the end portion 40a corresponds to the cut surface 22c (see FIG. 2) of the half-divided sample 22, and the end portion 40b corresponds to the central portion 22d (see FIG. 2) of the half-divided sample 22 in the circumferential direction. reference). In this embodiment, in the state shown in FIG. 6, the stress at the intersection of the inner surface 40c and the end 40b is obtained as the residual stress _σi2 of the inner surface 22b of the half-divided sample 22, and the intersection of the outer surface 40d and the end 40b is obtained as the residual stress σ _o2 of the outer surface 22 a of the half-split sample 22 .

For the cylindrical member 20 of arbitrary size, the above analysis described in FIGS. is changed to 0).

As a result of various studies by the present inventors, the thickness T of the cylindrical member 20, the distance t (see FIG. residual stress σ _o1 on the outer surface 20a (see FIG. 5), residual stress σ _i1 on the inner surface 20b of the cylindrical member 20 (see FIG. 5), residual stress σ _o2 on the outer surface 22a of the half-divided sample 22 (see FIG. 6), and It was found that there is a certain relationship between the residual stress σ _i2 (see FIG. 6) of the inner surface 22b of the half-split sample 22 .

Specifically, as shown in FIG. 7, the present inventors have found the relationship between the value of (t/T) ² and the value of (σ _i2 /−σ _i1 ) in the cylindrical member 20 after self-stressing treatment. It was found that there is a certain correlation between Then, the following equation (1) was obtained by linearly approximating the relationship between the value of (t/T) ² and the value of (σ _i2 /−σ _i1 ) using the least squares method. In addition, in the following formula (1), a and b are coefficients.
σ _i2 /(-σ _i1 )=a*(t/T) ² -b (1)

In addition, as shown in FIG. 8, the present inventors have found that the value of (t/T) ² and the value of ((σ _o2 −σ _o1 )/−σ _i1 ) in the cylindrical member 20 after self-stressing treatment We also found that there is a certain correlation between Then, the following equation (2) was obtained by linearly approximating the relationship between the value of (t/T) ² and the value of ((σ _o2 −σ _o1 )/−σ _i1 ) using the least squares method. In addition, in the following formula (2), c and d are coefficients.
(σ _o2 -σ _o1 )/(-σ _i1 )=-c*(t/T) ² -d (2)

From the above formula (1), the residual stress σ _i1 of the inner surface 20b of the cylindrical member 20 after the self-stressing treatment can be expressed by the following formula (3).
σ _i1 =(-σ _i2 )/(a*(t/T) ² -b) (3)

From the above formulas (1) and (2), (t/T) can be represented by the following formula (4).
t/T=((b*(σ _o2 -σ _o1 )-d*σ _i2 )/(a*(σ _o2 -σ _o1 )+c*σ _i2 )) ^1/2 (4)

By performing the above analysis on cylindrical members 20 of various sizes, the above equations (3) and (4) are determined for each size of cylindrical member 20 . Then, based on the above formulas (3) and (4) obtained for each dimension of the cylindrical member 20, the coefficient a is a value related to the dimensions of the cylindrical member 20 (in this embodiment, the outer diameter D and the inner diameter d). is expressed as a function with a variable. The coefficient a is represented, for example, by an exponential function whose variable is a constant multiple of the value of (D/d) ² . Although detailed description is omitted, each of the other coefficients b, c, and d is calculated as It is represented by a function with values (in this embodiment, the outer diameter D and the inner diameter d) as variables.

Residual stress σ _i1 can be expressed by a multivariable function whose variables are the residual stresses σ _o1 , σ _o2 , σ _i2 and the values related to the dimensions of the cylindrical member 20 (outer diameter D and inner diameter d in this embodiment).

Note that the method of obtaining the multivariable function used by the estimating unit 14 is not limited to the above example, and based on the residual stresses σ _o1 , σ _o2 , σ _i1 , and σ _i2 obtained by numerical analysis under various conditions, can be obtained as appropriate.

[Equipment operation]
Next, the operation of the estimation device 10 according to this embodiment will be described. FIG. 9 is a flowchart showing the operation of the estimation device 10 according to this embodiment. In addition, the residual stress estimation method according to one embodiment of the present invention is implemented by operating the estimation device 10 .

In the present embodiment, first, as described above, the acquiring unit 12 acquires the measured value of residual stress _{σo1 on the outer surface 20a of the cylindrical member 20, the measured value of residual stress σo2 on} the outer surface 22a of the halved sample 22, the half A measured value of the residual stress _σi2 of the inner surface 22b of the split sample 22, the outer diameter D of the cylindrical member 20, and the inner diameter d of the cylindrical member 20 are obtained (step S1).

Next, the estimating unit 14 calculates the relationship obtained in advance using the analytical model of the cylindrical member 20 as described above, and the measured values of residual stresses σ _o1 , σ _o2 , and σ _i2 obtained by the obtaining unit 12, A residual stress σ _i1 of the inner surface 20b of the cylindrical member 20 is estimated based on the outer diameter D and the inner diameter d (step S2).

Next, the determination unit 16 determines whether or not the estimated value of the residual stress σ _i1 calculated by the estimation unit 14 satisfies the preset condition of the residual stress σ _i1 as described above ( step S3). Finally, the output unit 18 outputs the determination result by the determination unit 16 as described above (step S4).

[program]
A program according to an embodiment of the present invention may be a program that causes a computer to execute the processes of steps S1 to S4 described above. By installing this program in a computer and executing it, the residual stress estimating device and residual stress estimating method according to this embodiment can be realized. In this case, the processor of the computer functions as the acquiring unit 12, the estimating unit 14, the determining unit 16, and the output unit 18 and performs processing.

Also, the program according to the present embodiment may be executed by a computer system constructed by a plurality of computers. In this case, each computer may function as the acquisition unit 12, the estimation unit 14, the determination unit 16, and the output unit 18, respectively.

[Physical configuration]
FIG. 10 is a block diagram showing an example of a computer that implements the estimation device 10 according to one embodiment of the present invention. The computer 110 realizes the estimation device 10 according to this embodiment by executing the program according to this embodiment.

As shown in FIG. 10 , computer 110 includes CPU 111 , main memory 112 , storage device 113 , input interface 114 , display controller 115 , data reader/writer 116 and communication interface 117 . These units are connected to each other via a bus 121 so as to be able to communicate with each other. The computer 110 may include a GPU (Graphics Processing Unit) or an FPGA (Field-Programmable Gate Array) in addition to the CPU 111 or instead of the CPU 111 .

The CPU 111 expands the programs (codes) of the present embodiment stored in the storage device 113 into the main memory 112 and executes them in a predetermined order to perform various calculations. The main memory 112 is typically a volatile storage device such as a DRAM (Dynamic Random Access Memory). Also, the program in the present embodiment is provided in a state stored in computer-readable recording medium 120 . It should be noted that the program in this embodiment may be distributed on the Internet connected via communication interface 117 .

Further, as a specific example of the storage device 113, in addition to a hard disk drive, a semiconductor storage device such as a flash memory can be cited. Input interface 114 mediates data transmission between CPU 111 and input devices 118 such as a keyboard and mouse. The display controller 115 is connected to the display device 119 and controls display on the display device 119 .

Data reader/writer 116 mediates data transmission between CPU 111 and recording medium 120 , reads programs from recording medium 120 , and writes processing results in computer 110 to recording medium 120 . Communication interface 117 mediates data transmission between CPU 111 and other computers.

Specific examples of the recording medium 120 include general-purpose semiconductor storage devices such as CF (Compact Flash (registered trademark)) and SD (Secure Digital); magnetic recording media such as flexible disks; An optical recording medium such as a ROM (Compact Disk Read Only Memory) can be used.

Note that the estimation device 10 according to the present embodiment may be realized by using hardware corresponding to each unit instead of a computer in which a program is installed. and the rest may be implemented in hardware.

[Quality control method]
Finally, a quality control method for the cylindrical member 20 performed using the estimation device 10 described above will be described.

Referring to FIG. 2, the quality control method according to one embodiment of the present invention comprises:
(a) a step of subjecting the cylindrical member 20 to a self-stressing process;
(b) a step of actually measuring the residual stress σ _o1 of the outer surface 20a of the cylindrical member 20 that has undergone self-stressing treatment in step (a) above;
(c) After halving the cylindrical member 20 that has been subjected to the self-cleaning process in step (a) above, the remaining outer surface 22a and inner surface 22b of the cylindrical member after halving (i.e., the halved sample 22) a step of actually measuring the stresses σ _o2 and σ _i2 ;
(d) The residual stress σ _i1 of the inner surface 20b of the cylindrical member 20, which has undergone self-stressing treatment in step (a) above, is actually measured in steps (b) and (c) above using the estimation device 10 described above. a step of estimating from each residual stress σ _o1 , σ _o2 , σ _i2 obtained from
(e) adjusting conditions for self-stressing treatment of the other cylindrical member 20 based on the residual stress σ _i1 estimated in step (d) above.

In the above step (a), the cylindrical member 20 is subjected to self-sealing treatment by a known self-sealing treatment method. Various steel pipes such as seamless steel pipes can be used as the cylindrical member 20 to which the self-sealing treatment is applied. The relationship between the pressure applied to the inner surface of the cylindrical member during the self-sealing treatment (hereinafter referred to as the self-sealing pressure) and the residual stress generated on the inner surface of the cylindrical member after the self-sealing treatment. The master curve shown may be obtained in advance by numerical analysis (FEM analysis) or the like. In this case, in the self-cooling step, the self-cooling pressure can be determined using a master curve so as to generate a desired residual stress on the inner surface of the cylindrical member.

In steps (b) and (c) above, each residual stress can be measured according to Non-Patent Document 1, as described above. In step (c), the residual stress at or near the central portion 22d of the outer surface 22a and the inner surface 22b of the halved sample 22 is measured.

The above steps (a) to (d) are performed, for example, when a plurality of cylindrical members manufactured from the same lot or from the same molten steel are subjected to self-straining treatment, the cylindrical member first subjected to self-straining treatment is carried out against

In the above step (e), for example, if the estimated value of the residual stress σ _i1 estimated by the estimation device 10 exceeds the preset upper limit value of the residual stress σ _i1 , the operator When the other cylindrical member 20 manufactured from a lot or the same molten steel is subjected to the self-heating treatment, the self-heating treatment pressure is lowered from the current set pressure. On the other hand, when the estimated value of the residual stress _σi1 estimated by the estimating device 10 is less than the preset lower limit value of the residual stress _σi1 , the worker instructs the other cylindrical member 20 to self-stress. , the self-heating treatment pressure is raised from the current set pressure. For example, when a plurality of cylindrical members manufactured from the same lot or from the same molten steel are subjected to self-straining treatment, the operator may set the estimated value of the residual stress σ _i1 in step (e) to the preset residual Steps (a) to (e) are repeatedly executed until the stress σ _i1 condition is satisfied. This enables proper quality control of the cylindrical member 20 .

ADVANTAGE OF THE INVENTION According to this invention, the residual stress of the inner surface of the cylindrical member after self-heating treatment can be estimated appropriately, and the appropriate quality control of a cylindrical member is attained.

10 estimation device 12 acquisition unit 14 estimation unit 16 determination unit 18 output unit 20 cylindrical member 20a outer surface 20b inner surface 22 half-divided sample 22a outer surface 22b inner surface 22c cut surface 22d central portion 40 analysis model 40a, 40b end 40c inner surface 40d outer surface

Claims (13)

A device for estimating the residual stress of a cylindrical member after self-heating treatment,
Measured value of residual stress on the outer surface of the cylindrical member after self-strengthening treatment, measured value of residual stress on the outer surface of the cylindrical member after self-straightening treatment and after halving, and after self-strengthening treatment and after halving an acquisition unit that acquires a measured value of residual stress on the inner surface of the cylindrical member;
The residual stress on the outer surface of the cylindrical member after self-strengthening treatment, the residual stress on the inner surface of the cylindrical member after self-strengthening treatment, the residual stress on the inner surface of the cylindrical member after self-strengthening treatment, and the residual stress after self-strengthening treatment and half The relationship between the residual stress on the outer surface of the cylindrical member after splitting, the residual stress on the inner surface of the cylindrical member after self-strengthening treatment and after splitting in half, and the measured value of each residual stress obtained by the obtaining unit an estimating unit for estimating the residual stress on the inner surface of the cylindrical member after the self-cooling treatment, based on
A residual stress estimator. The relationship is obtained using an analytical model of a plurality of cylindrical members having different dimensions, and is associated with information regarding the dimensions of the cylindrical member,
The acquisition unit further acquires information about the dimensions of the cylindrical member,
The estimating unit estimates the residual stress of the inner surface of the cylindrical member after the self-straining treatment based on the information on the dimensions and the measured value of each residual stress acquired by the acquiring unit, and the relationship. , The residual stress estimating device according to claim 1. 3. The residual stress estimating device according to claim 2, wherein said information on dimensions is information on an outer diameter and an inner diameter of said cylindrical member. 4. The residual stress estimation according to any one of claims 1 to 3, further comprising a determination unit that determines whether the residual stress on the inner surface estimated by the estimation unit satisfies preset residual stress conditions. Device. A method for estimating the residual stress of a cylindrical member after self-heating treatment by a computer,
(a) Measured value of residual stress on the outer surface of the cylindrical member after self-strengthening treatment, measured value of residual stress on the outer surface of the cylindrical member after self-straightening treatment and after halving, and after self-straightening treatment and half obtaining a measured value of the residual stress on the inner surface of the cylindrical member after splitting;
(b) the residual stress on the outer surface of the cylindrical member after the self-sealing treatment, the residual stress on the inner surface of the cylindrical member after the self-sealing treatment, and the self-sealing treatment obtained in advance using the analytical model of the cylindrical member; The relationship between the residual stress on the outer surface of the cylindrical member after halving and the residual stress on the inner surface of the cylindrical member after self-strengthening treatment and after halving, and each residual obtained in step (a) estimating the residual stress on the inner surface of the cylindrical member after the self-stressing treatment, based on the measured value of the stress;
A residual stress estimation method comprising: The relationship is obtained using an analytical model of a plurality of cylindrical members having different dimensions, and is associated with information regarding the dimensions of the cylindrical member,
In step (a), further obtaining information about the dimensions of the cylindrical member;
In the step (b), the inner surface of the cylindrical member after the self-stressing treatment is determined based on the information on the dimensions and the measured values of each residual stress obtained in the step (a), and on the basis of the relationship. 6. The residual stress estimation method according to claim 5, wherein the residual stress of is estimated. 7. The residual stress estimating method according to claim 6, wherein said information on dimensions is information on an outer diameter and an inner diameter of said cylindrical member. (c) determining whether or not the residual stress on the inner surface estimated in step (b) satisfies preset residual stress conditions; The described residual stress estimation method. In order to estimate the residual stress of the cylindrical member after self-heating treatment, the computer
(a) Measured value of residual stress on the outer surface of the cylindrical member after self-strengthening treatment, measured value of residual stress on the outer surface of the cylindrical member after self-straightening treatment and after halving, and after self-straightening treatment and half obtaining a measured value of the residual stress on the inner surface of the cylindrical member after splitting;
(b) the residual stress on the outer surface of the cylindrical member after the self-sealing treatment, the residual stress on the inner surface of the cylindrical member after the self-sealing treatment, and the self-sealing treatment obtained in advance using the analytical model of the cylindrical member; The relationship between the residual stress on the outer surface of the cylindrical member after halving and the residual stress on the inner surface of the cylindrical member after self-strengthening treatment and after halving, and each residual obtained in step (a) estimating the residual stress on the inner surface of the cylindrical member after the self-stressing treatment, based on the measured value of the stress;
The program that causes the to run. The relationship is obtained using an analytical model of a plurality of cylindrical members having different dimensions, and is associated with information regarding the dimensions of the cylindrical member,
In step (a), further obtaining information about the dimensions of the cylindrical member;
In the step (b), the inner surface of the cylindrical member after the self-stressing treatment is determined based on the information on the dimensions and the measured values of each residual stress obtained in the step (a), and on the basis of the relationship. 10. The program according to claim 9, which estimates the residual stress of . 11. The program according to claim 10, wherein said information on dimensions is information on an outer diameter and an inner diameter of said cylindrical member. to the computer;
(c) determining whether or not the residual stress on the inner surface estimated in step (b) satisfies preset residual stress conditions; program described in . (A) a step of subjecting the cylindrical member to a self-stressing process;
(B) a step of actually measuring the residual stress on the outer surface of the cylindrical member that has been subjected to self-stress treatment in step (A);
(C) After halving the cylindrical member that has undergone the self-stressing treatment in step (A), measuring the residual stress on the outer and inner surfaces of the halved cylindrical member;
(D) Using the residual stress estimating apparatus according to any one of claims 1 to 4, the residual stress on the inner surface of the cylindrical member that has been subjected to the self-straining treatment in step (A) is estimated by using the residual stress estimator according to (B) and A step of estimating from each residual stress actually measured in step (C);
(E) a step of adjusting conditions for self-stressing treatment of other cylindrical members based on the residual stress estimated in step (D);
A method for quality control of a cylindrical member, comprising:

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