Method for setting processing conditions for shaft enlargement, shaft enlargement method, and shaft enlargement apparatus.

Abstract

The present invention provides a method for setting processing conditions for a shaft enlargement process, a shaft enlargement process, and a shaft enlargement process apparatus that can reduce the time and cost required for inspection for the presence or absence of cracks. [Solution] The control unit 13 of the shaft enlargement processing device 1 controls the pressurizing unit 4, the bending unit 5, and the rotating unit 6, and rotates the shaft material W around its axis while applying axial compressive force and a bending angle to the intermediate part Wa of the shaft material W held by a pair of holding units 2 and 3, thereby enlarging the intermediate part Wa of the shaft material W to a predetermined outer diameter. The pass / fail status of the shaft material W is determined based on the number of rotations of the shaft material W required for the intermediate part Wa of the shaft material W to enlarge to a predetermined outer diameter, which is detected by the rotation count detection unit 7.

Description

Technical Field

[0005] , , ,

[0001] The present invention relates to a method for setting processing conditions of an axial enlargement processing method, an axial enlargement processing method, and an axial enlargement processing apparatus.

Background Art

[0002] As one of the processing methods for forming a large-diameter portion in a part of a shaft material, axial enlargement processing is known. As an example of the axial enlargement processing method, a method of enlarging the middle portion of a shaft material by applying a compressive force and a bending angle to the middle portion of the shaft material and rotating the shaft material is known.

[0003] The axial enlargement processing machine for performing the above axial enlargement processing generally holds a shaft material by a pair of holding portions arranged at a distance in the axial direction of the shaft material, reduces the distance between the pair of holding portions to apply a compressive force to the middle portion of the shaft material, tilts one holding portion with respect to the other holding portion to apply a bending angle to the middle portion of the shaft material, and rotates the pair of holding portions in that state to rotate the shaft material, thereby enlarging the middle portion of the shaft material. And the process of enlarging the middle portion of the shaft material ends when the distance between the pair of holding portions is reduced to a predetermined distance (see, for example, Patent Document 1), or ends when the outer diameter of the middle portion reaches a predetermined outer diameter (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] During shaft enlargement machining, cracks may occur at the connection point between the enlarged intermediate section and the remaining shaft section, and cracks may also occur on the outer circumference of the enlarged intermediate section. While these cracks can be detected by methods such as visual inspection, magnetic particle testing, and eddy current testing, 100% inspection of mass-produced shaft materials is time-consuming and costly.

[0006] This invention has been made in view of the above circumstances, and aims to provide a method for setting processing conditions for a shaft enlargement process, a shaft enlargement process, and a shaft enlargement process apparatus that can reduce the time and cost required for inspection for the presence or absence of cracks. [Means for solving the problem]

[0007] A method for setting processing conditions for shaft enlargement according to one aspect of the present invention is a method for setting processing conditions for shaft enlargement, in which the intermediate portion of a shaft material is enlarged radially by rotating the shaft material around its axis while applying an axial compressive force and a bending angle to the intermediate portion of the shaft material, and based on test data obtained by performing shaft enlargement on a test shaft material of the same material and shape as the shaft material, the method sets an allowable number of rotations such that the probability of crack occurrence at the connection portion is below a threshold, and the number of rotations of the shaft material when enlarging the intermediate portion of the shaft material to the predetermined outer diameter in shaft enlargement processing of the shaft material is below the allowable number of rotations.

[0008] Furthermore, a method for setting processing conditions for shaft enlargement processing according to one aspect of the present invention is a method for setting processing conditions for shaft enlargement processing, in which the intermediate part of a shaft material is enlarged radially by rotating the shaft material around its axis while applying an axial compressive force and a bending angle to the intermediate part of the shaft material, and based on test data obtained by performing shaft enlargement processing on a test shaft material of the same material and shape as the shaft material, the method sets an allowable enlargement rate such that the probability of crack occurrence on the outer circumference of the intermediate part of the test shaft material is less than or equal to a threshold, and the enlargement rate of the intermediate part of the shaft material when enlarging the intermediate part of the shaft material to a predetermined outer diameter in shaft enlargement processing is set to be less than or equal to the allowable enlargement rate.

[0009] Furthermore, one embodiment of the present invention is a shaft enlargement method in which the intermediate portion of a shaft material is enlarged radially by rotating the shaft material around its axis while applying an axial compressive force and a bending angle to the intermediate portion of the shaft material, and the pass / fail status of the shaft material is determined based on the number of rotations of the shaft material required to enlarge the intermediate portion of the shaft material to a predetermined outer diameter.

[0010] Furthermore, one embodiment of the present invention is a shaft enlargement method in which the intermediate portion of a shaft material is enlarged radially by rotating the shaft material around its axis while applying an axial compressive force and a bending angle to the intermediate portion of the shaft material, and the pass or fail of the shaft material is determined based on the enlargement rate, which is the ratio of the outer diameter after processing to the outer diameter before processing of the intermediate portion of the shaft material.

[0011] Furthermore, a shaft enlargement processing apparatus according to one aspect of the present invention comprises: a pair of holding parts that hold the shaft material at a distance from each other in the axial direction of the shaft material; a pressing part that reduces the distance between the pair of holding parts and applies an axial compressive force to the intermediate part of the shaft material positioned between the pair of holding parts; a bending part that tilts one of the pair of holding parts relative to the other holding part to apply a bending angle to the intermediate part of the shaft material; a rotating part that rotates the pair of holding parts and the shaft material around the axis of the shaft material; a rotation count detection part that detects the number of rotations of the shaft material; and a control unit that controls the pressing part, the bending part, and the rotating part to rotate the shaft material around its axis while applying an axial compressive force and a bending angle to the intermediate part of the shaft material, thereby enlarging the intermediate part of the shaft material to a predetermined outer diameter, wherein the control unit determines whether the shaft material is acceptable or unacceptable based on the number of rotations of the shaft material required until the intermediate part of the shaft material is enlarged to the predetermined outer diameter.

[0012] Furthermore, a shaft enlargement processing apparatus according to one aspect of the present invention includes: a pair of holding parts that hold the shaft material at a distance from each other in the axial direction of the shaft material; a pressing part that reduces the distance between the pair of holding parts and applies an axial compressive force to the intermediate part of the shaft material positioned between the pair of holding parts; a bending part that tilts one of the pair of holding parts relative to the other holding part to apply a bending angle to the intermediate part of the shaft material; a rotating part that rotates the pair of holding parts and the shaft material around the axis of the shaft material; an axial displacement detection part that detects the amount of change in the distance between the pair of holding parts; and the shaft material The device comprises a radial displacement detection unit that detects the amount of change in the outer diameter of the intermediate portion, and a control unit that controls the pressurizing unit, the bending unit, and the rotating unit to apply an axial compressive force and a bending angle to the intermediate portion of the shaft material, rotate the shaft material around its axis, and reduce the distance between the pair of holding units by a predetermined amount, thereby enlarging the intermediate portion of the shaft material. The control unit determines the enlargement rate, which is the ratio of the outer diameter after processing to the outer diameter before processing of the intermediate portion of the shaft material, based on the amount of change in the outer diameter of the intermediate portion of the shaft material, and determines whether the shaft material is acceptable or not based on the determined enlargement rate. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a method for setting processing conditions for shaft thickening processing, a shaft thickening processing method, and a shaft thickening processing apparatus that can reduce the time and cost required for inspecting the presence or absence of cracks.

Brief Description of the Drawings

[0014] [Figure 1] It is a block diagram of an example of a shaft thickening processing apparatus for explaining an embodiment of the present invention. [Figure 2] It is a block diagram of a modified example of the shaft thickening processing apparatus of FIG. 1. [Figure 3A] It is a schematic diagram of an example of a shaft thickening processing method using the shaft thickening processing apparatus of FIG. 1. [Figure 3B] It is a schematic diagram of an example of a shaft thickening processing method using the shaft thickening processing apparatus of FIG. 1. [Figure 3C] It is a schematic diagram of an example of a shaft thickening processing method using the shaft thickening processing apparatus of FIG. 1. [Figure 3D] It is a schematic diagram of an example of a shaft thickening processing method using the shaft thickening processing apparatus of FIG. 1. [Figure 4A] It is a graph of an example of test data showing the relationship between the compressive force and the number of rotations of a test shaft material. [Figure 4B] It is a graph of an example of test data showing the relationship between the number of rotations of a test shaft material and the probability of crack generation. [Figure 5A] It is a graph of an example of test data showing the relationship between the compression rate and the thickening rate of a test shaft material. [Figure 5B] It is a graph of an example of test data showing the relationship between the thickening rate of a test shaft material and the probability of crack generation. [Figure 6] It is a flowchart of an example of the processing performed by the control unit of the shaft thickening processing apparatus of FIG. 1. [Figure 7] It is a flowchart of another example of the processing performed by the control unit of the shaft thickening processing apparatus of FIG. 1.

Embodiments for Carrying Out the Invention

[0015] FIG. 1 shows an example of a shaft thickening processing apparatus for explaining an embodiment of the present invention.

[0016] The shaft enlargement machining apparatus 1 shown in Fig. 1 includes a pair of holding parts 2 and 3 for holding a shaft material W, a pressing part 4, a bending part 5, a rotating part 6, a rotational speed detection part 7, and a control panel 8.

[0017] The holding part 2 fits with one end of the shaft material W in the axial direction, and the holding part 3 fits with the other end of the shaft material W in the axial direction. Thus, the shaft material W is held by the pair of holding parts 2 and 3. The pair of holding parts 2 and 3 are arranged at a distance along the reference line A on the reference line A and are supported by a support base (not shown). The shaft material W held by the pair of holding parts 2 and 3 is also arranged on the reference line A. One holding part 2 is movable along the reference line A, that is, movable in the axial direction of the shaft material W, and the other holding part 3 is movable in a direction intersecting the reference line A.

[0018] The pressing part 4 is configured to include, for example, a fluid pressure cylinder or the like, moves the holding part 2 along the reference line A, and reduces the distance between the pair of holding parts 2 and 3. As the distance between the pair of holding parts 2 and 3 is reduced, an axial compressive force is applied to the intermediate part Wa in the axial direction of the shaft material W arranged between the pair of holding parts 2 and 3.

[0019] The bending part 5 is configured to include, for example, a fluid pressure cylinder or the like, moves the holding part 3 in a direction intersecting the reference line A, and tilts the holding part 3 with respect to the holding part 2 arranged on the reference line A. As the holding part 3 is tilted with respect to the holding part 2, a bending angle θ is applied to the intermediate part Wa of the shaft material W.

[0020] The rotating part 6 is configured to include, for example, an electric motor or the like, and rotates the holding part 3 around the central axis of the holding part 3. As the holding part 3 is rotated, the shaft material W whose one end is fitted to the holding part 3 also rotates around the axis, and the holding part 2 to which the other end of the shaft material W is fitted also rotates.

[0021] The rotation count detection unit 7 is configured to include, for example, a rotary encoder, and detects the number of rotations of the holding unit 3 as the number of rotations of the shaft material W. The rotation count detection unit 7 may also detect the number of rotations of the holding unit 2 instead of the holding unit 3, or it may detect the number of rotations of the shaft material W.

[0022] The control panel 8 includes an operation unit 11 having hardware keys such as switches and used for inputting processing conditions, a display unit 12 having a display device such as an LCD (liquid crystal display) and displaying an operation screen, and a control unit 13.

[0023] The control unit 13 is a computer such as a PLC (programmable logic controller), and has one or more processors, a memory device such as a ROM (Read Only Memory) or RAM (Random Access Memory) that stores the programs executed by the processors and the processing conditions input via the operation unit 11. The processor executes the program and controls the pressurizing unit 4, the bending unit 5, and the rotating unit 6 based on the input processing conditions.

[0024] Under the control of the control unit 13, the pressurizing unit 4 applies an axial compressive force to the intermediate portion Wa of the shaft material W, and the bending unit 5 applies a bending angle θ to the intermediate portion Wa of the shaft material W, while the rotating unit 6 rotates the shaft material W around its axis. As a result, the intermediate portion Wa of the shaft material W is compressed in the axial direction and expanded in the radial direction.

[0025] The number of rotations detected by the rotation count detection unit 7 is input to the control unit 13. The pressurizing unit 4 is equipped with a sensor to detect compressive force, the bending unit 5 is equipped with a sensor to detect the bending angle θ based on, for example, the displacement of the holding unit 3, and the rotating unit 6 is equipped with a sensor to detect the rotational speed of the holding unit 3. The compressive force, bending angle θ, and rotational speed detected by these sensors are also input to the control unit 13. The rotational speed may be calculated by the control unit 13 based on the number of rotations detected by the rotation count detection unit 7.

[0026] The shaft enlargement processing apparatus 1 further includes an axial displacement detection unit 9. The axial displacement detection unit 9 is configured to include, for example, a linear encoder, and detects the amount of displacement of the holding unit 2 which is moved by the pressurizing unit 4.

[0027] The amount of displacement of the holding part 2 detected by the axial displacement detection unit 9 is input to the control unit 13. Based on the amount of displacement of the holding part 2 since the compressive force began to increase, the control unit 13 detects the amount of compression of the intermediate part Wa of the shaft material W (the decrease in the axial length of the intermediate part Wa), and based on this amount of compression, detects that the intermediate part Wa has been enlarged to a predetermined outer diameter.

[0028] As shown in Figure 2, the shaft enlargement processing apparatus 1 may also include a radial displacement detection unit 10 for detecting the change in the outer diameter of the intermediate portion Wa of the shaft material W. The control unit 13 may detect that the intermediate portion Wa has been enlarged to a predetermined outer diameter based on the change in the outer diameter of the intermediate portion Wa from the outer diameter before processing, as detected by the radial displacement detection unit 10.

[0029] Next, an example of a shaft enlargement method using the shaft enlargement processing device 1 will be explained with reference to Figures 3A to 3E.

[0030] First, as shown in Figure 3A, the shaft material W is held by a pair of holding parts 2 and 3. The axial length L0 of the intermediate part Wa of the shaft material W before processing is given by D0, where D0 is the outer diameter of the intermediate part Wa before processing. In relation to 0, it is appropriately determined according to the axial length L and outer diameter D of the intermediate section Wa after machining. Hereafter, L / L0 will be referred to as the compression ratio, and D / D0 as the expansion ratio.

[0031] Next, as shown in Figure 3B, the holding part 2 is moved along the reference line A by the pressurizing part 4 (see Figure 1), and an axial compressive force is applied to the intermediate part Wa of the shaft W. Also, the holding part 3 is tilted relative to the holding part 2 by the bending part 5 (see Figure 1), and a bending angle θ is applied to the intermediate part Wa. The bending angle θ is set to an angle at which the bending of the shaft W falls within the deformation limit of the shaft W, and varies depending on the elastic limit of the material of the shaft W, but is typically around 2° to 4°. Then, with the compressive force and bending angle θ applied to the intermediate part Wa of the shaft W, the holding part 3 is rotated by the rotating part 6 (see Figure 1), and the shaft W is rotated around its axis.

[0032] As shown in Figure 3C, as the intermediate portion Wa of the shaft W is compressed, bent, and rotated, alternating radial loads act on each part of the intermediate portion Wa in the circumferential direction, and as these alternating loads are repeatedly applied, the intermediate portion Wa gradually expands in the radial direction. Specifically, compression and bending of the intermediate portion Wa cause the material on the inside of the bend to undergo plastic flow and bulge. Then, as the shaft W rotates, the bulge due to plastic flow of the material on the inside of the bend of the intermediate portion Wa grows along the entire circumference, and the intermediate portion Wa gradually expands in the radial direction.

[0033] As shown in Figure 3D, when the control unit 13 (see Figure 1) detects that the intermediate portion Wa of the shaft material W has been enlarged to a predetermined outer diameter, based on the amount of compression of the intermediate portion Wa or the amount of change in the outer diameter of the intermediate portion Wa, the compression of the intermediate portion Wa is stopped. Then, the holding portion 3 is positioned again along the reference line A, and the intermediate portion Wa of the shaft material W is bent back, and the thickness of the enlarged intermediate portion Wa is smoothed out around the entire circumference. After this process, the shaft enlargement process for the shaft material W is completed, and the rotation of the shaft material W is stopped.

[0034] The occurrence of cracks in the connection portion Wc between the intermediate portion Wa of the shaft material W, which has undergone shaft enlargement processing, and the shaft portion Wb excluding the intermediate portion Wa (the portion fitted to the holding portions 2 and 3) is due to material fatigue caused by repeated application of alternating loads and is related to the number of rotations of the shaft material W required for the intermediate portion Wa to enlarge to a predetermined outer diameter. Therefore, as a processing condition, an allowable number of rotations is set for the number of rotations of the shaft material W required for the intermediate portion Wa to enlarge to a predetermined outer diameter.

[0035] Furthermore, the occurrence of cracks in the outer peripheral portion Wd of the intermediate portion Wa of the shaft material W that has undergone shaft enlargement processing is due to the enlargement of the intermediate portion Wa exceeding the malleability limit of the material, and is related to the enlargement ratio D / D0 of the intermediate portion Wa. Therefore, as a processing condition, the allowable enlargement ratio D / D0 of the intermediate portion Wa is set. A large percentage is set.

[0036] Figures 4A and 4B show an example of test data used to set the allowable rotational speed.

[0037] The test data shown in Figures 4A and 4B are obtained by performing shaft enlargement processing on test shafts made of the same material and shape as shaft material W. The test data shown in Figure 4A shows the relationship between compressive force and number of rotations when the number of rotations required to enlarge the middle section of the test shaft to a predetermined outer diameter is changed by changing the compressive force applied to the middle section of the test shaft. The test data shown in Figure 4B shows the probability of crack occurrence at the connection point of the test shafts when shaft enlargement processing is performed on multiple test shafts for each set compressive force, in relation to the number of rotations corresponding to the compressive force.

[0038] In the interpolated curve of the test data shown in Figure 4B, the probability of crack occurrence at the connection point is 0% when the number of rotations is 40 or less. As the number of rotations increases beyond 40, the probability of crack occurrence also increases, and at 70 rotations or more, the probability of crack occurrence reaches 100%. This suggests that as the number of rotations increases, the number of repeated applications of the alternating load increases, and as the number of repeated applications of the alternating load increases, the material fatigues, and the probability of crack occurrence increases.

[0039] The allowable number of rotations can be set to the number of rotations at which the probability of crack occurrence is below a threshold, and the threshold for the probability of crack occurrence can be set considering the yield, etc., and can be set to 0%, for example.Therefore, according to the test data shown in Figure 4B, the allowable number of rotations can be set to 40, which is the upper limit of the number of rotations at which the probability of crack occurrence is 0%, and preferably, the number of rotations can be set with a margin considering the variation in the material properties of the shaft material, etc., relative to the upper limit of the number of rotations 40 at which the probability of crack occurrence is 0%, for example, the allowable number of rotations can be set to 32 (margin of 20%).

[0040] Furthermore, when the bending angle θ applied to the intermediate portion Wa of the shaft material W is relatively small, the material fatigue per alternating load cycle is relatively small, and when the bending angle θ applied to the intermediate portion Wa of the shaft material W is relatively large, the material fatigue per alternating load cycle is relatively large. In other words, the bending angle θ applied to the intermediate portion Wa is also related to the occurrence of cracks in the connection portion Wc of the shaft material W. Therefore, preferably, the test data used to set the allowable number of rotations is test data obtained by performing shaft enlargement processing on a test shaft material of the same material and shape as the shaft material W, at the same bending angle as the shaft material W.

[0041] Figures 5A and 5B show an example of test data used to determine the acceptable rate of hypertrophy.

[0042] The test data shown in Figures 5A and 5B are obtained by performing shaft enlargement processing on a test shaft material that is the same material and shape as shaft material W. The test data shown in Figure 5A shows the enlargement rate of the middle part of the test shaft material by changing the compression ratio L / L0 of the middle part of the test shaft material. This shows the relationship between the compression ratio L / L0 and the bloat ratio D / D0 when D / D0 is changed. The test data shown in Figure 5B indicates the probability of crack occurrence on the outer circumference of the middle section of the test shaft material when the shaft is enlarged for multiple test shaft materials at each set enlargement rate, in relation to the enlargement rate.

[0043] In the interpolated curve of the test data shown in Figure 5B, the probability of crack occurrence at the outer edge is 0% when the expansion rate is 1.8 or less. As the expansion rate increases above 1.8, the probability of crack occurrence also increases, and when the expansion rate is 3.0 or higher, the probability of crack occurrence is 100%. This indicates that as the expansion rate increases, the probability of exceeding the malleability limit of the material increases, and the probability of crack occurrence also increases.

[0044] The allowable expansion rate can be the expansion rate at which the probability of crack occurrence is below a threshold, and the threshold for the probability of crack occurrence can be set considering the yield, etc., and can be set to 0%, for example. Thus, according to the test data shown in Figure 5B, the allowable expansion rate can be set to 1.8, which is the upper limit of the expansion rate at which the probability of crack occurrence is 0%, and preferably, it can be set to an expansion rate with a margin that takes into account the variation in the material properties of the shaft material, etc., relative to the upper limit of the expansion rate of 1.8 at which the probability of crack occurrence is 0%, for example, the allowable expansion rate can be 1.6 (margin of error of 10%).

[0045] Figure 6 shows an example of the processing performed by the control unit 13 during shaft enlargement machining of the shaft material W.

[0046] First, the processing conditions are input to the operation unit 11, and the control unit 13 stores the input processing conditions (step S1). The input processing conditions are the compression force, rotational speed, bending angle θ, processing completion conditions, and allowable number of rotations N. The compression force and rotational speed can be set as appropriate, and for example, from the viewpoint of shortening the cycle time, they can be set to the maximum values ​​that the pressurizing unit 4 and the rotating unit 6 can output.

[0047] The processing completion condition is a condition for detecting that the intermediate portion Wa of the shaft material W has been enlarged to a predetermined outer diameter. If the shaft enlargement processing device 1 is equipped with an axial displacement detection unit 9 that detects the amount of displacement of the holding portion 2, the amount of displacement of the holding portion 2 (compression amount of the intermediate portion Wa) since the compressive force began to increase is set. If the shaft enlargement processing device 1 is equipped with a radial displacement detection unit 10 that detects the amount of change in the outer diameter of the intermediate portion Wa, the amount of change in the outer diameter of the intermediate portion Wa from the outer diameter before processing is set.

[0048] Here, the amount of displacement of the holding part 2 or the amount of change in the outer diameter of the intermediate part Wa is set in relation to the allowable enlargement rate. First, the enlargement rate is determined from the outer diameter D0 of the intermediate part Wa before processing and the required outer diameter D after processing. The shaft material W whose ratio D / D0 is less than or equal to the allowable enlargement rate is obtained from multiple shaft materials with different outer diameters D0 before processing. The required outer diameter D after processing is selected from among them. The change in the outer diameter of the intermediate section Wa is the difference between the outer diameter D0 of the intermediate section Wa of the selected shaft material W before processing and the required outer diameter D after processing. Furthermore, the volume of the intermediate section Wa does not change before and after processing, and the axial length L0 of the intermediate section Wa before processing is the same as Based on the enlargement rate D / D0, which is below the allowable enlargement rate, the axial length L of the intermediate section Wa after processing is determined. The displacement of the holding part 2 is determined by the axial length L0 of the intermediate part Wa before processing and the axial length after processing. It is the difference from length L.

[0049] The allowable number of rotations N is the allowable number of rotations for the selected shaft material W. The bending angle θ can be the same bending angle as the shaft enlargement process performed on a test shaft material of the same material and shape as the selected shaft material W to obtain the test data used to set the allowable number of rotations N.

[0050] Next, when a processing start instruction is input to the operation unit 11, the control unit 13 controls the pressurizing unit 4, the bending unit 5, and the rotating unit 6 according to the processing conditions input in step S1, and performs the shaft enlargement processing on the shaft material W as shown in Figures 3A to 3D (step S2). The control unit 13 completes the shaft enlargement processing on the shaft material W when the amount of displacement of the holding unit 2 detected by the axial displacement detection unit 9, or the amount of change in the outer diameter of the intermediate unit Wa detected by the radial displacement detection unit 10, reaches the processing completion condition (step S3).

[0051] Next, the control unit 13 obtains the number of rotations n of the shaft material W detected by the rotation count detection unit 7, which is the number of rotations required for the intermediate part Wa to enlarge to a predetermined outer diameter D, and determines whether the shaft material W is acceptable or unacceptable based on the obtained number of rotations n (step S4). In determining whether it is acceptable or unacceptable, the control unit 13 uses the allowable number of rotations N input in step S1, and determines that it is acceptable if n ≤ N (step S5), and unacceptable if n > N (step S6).

[0052] An example of a case where the number of rotations n exceeds the allowable number of rotations N is when the shaft material W being processed is unusually hard due to variations in the material properties of the shaft material. When n > N, the occurrence of a crack in the connection part Wc of the shaft material W is expected to occur with a probability corresponding to the number of rotations n on the interpolation curve of the test data shown in Figure 4B. Therefore, the control unit 13 determines that the product is unsuccessful when n > N. The result of the determination is communicated to the operator, for example, by being displayed on the display unit 12 under the control of the control unit 13.

[0053] In this way, the pass / fail status of crack occurrence in the connection portion Wc of the shaft material W is determined based on the number of rotations n required for the intermediate portion Wa of the shaft material W to enlarge to a predetermined outer diameter D. This allows for determination immediately after the completion of processing, thereby saving time and costs required for inspection for the presence or absence of cracks.

[0054] Furthermore, in this example, the displacement of the holding portion 2 or the change in the outer diameter of the intermediate portion Wa, which is the processing completion condition, is set in relation to the allowable enlargement rate, and the occurrence of cracks in the outer circumference Wd of the shaft material W is also suppressed. As a result, the time and cost required for inspection for the presence or absence of cracks can be further reduced.

[0055] Figure 7 shows another example of the processing performed by the control unit 13 during shaft enlargement machining of the shaft material W.

[0056] In the example shown in Figure 7, the processing conditions are input as compressive force, rotational speed, bending angle θ, processing completion conditions, and allowable expansion ratio D / D0, and the control unit 13 uses the input allowable expansion ratio D / D0 to process the data. This determines whether the condition is positive or negative. In this example, the shaft enlargement processing apparatus 1 includes an axial displacement detection unit 9 that detects the amount of displacement of the holding unit 2, and a radial displacement detection unit 10 that detects the amount of change in the outer diameter of the intermediate part Wa of the shaft material W. The processing completion condition is set by the amount of displacement of the holding unit 2, and the radial displacement detection unit 10 detects the amount of change in the outer diameter of the intermediate part Wa when processing is complete.

[0057] First, the processing conditions are input to the operation unit 11, and the control unit 13 stores the input processing conditions (step S11). Next, when a processing start instruction is input to the operation unit 11, the control unit 13 controls the pressurizing unit 4, the bending unit 5, and the rotating unit 6 according to the processing conditions input in step S1, and performs the shaft enlargement processing on the shaft material W as shown in Figures 3A to 3D (step S12). The control unit 13 completes the shaft enlargement processing on the shaft material W when the amount of displacement of the holding unit 2 detected by the axial displacement detection unit 9 reaches the processing completion condition (step S13).

[0058] Next, the control unit 13 acquires the change in the outer diameter of the intermediate part Wa detected by the radial displacement detection unit 10 and determines the enlargement rate of the intermediate part Wa after processing is complete (step S14). The enlargement rate of the intermediate part Wa is determined by the outer diameter D0 of the intermediate part Wa before processing and the change detected by the radial displacement detection unit 10. Using the change in the outer diameter ΔD of the intermediate part Wa, the result can be calculated by (D0 + ΔD) / D0. It is possible.

[0059] Then, the control unit 13 uses the enlargement rate (D0+ΔD) / D0 obtained in step S14 to determine The pass / fail status of the shaft material W is determined (step S15). In this pass / fail determination, the control unit 13 uses the allowable enlargement rate D / D0 input in step S11, and (D0+ΔD) / D0≦D / If D0, it is judged as a pass (step S16), and (D0+ΔD) / D0 > D / D0 If so, the result is a failure (Step S17).

[0060] Cases where the enlargement rate (D0 + ΔD) / D0 exceeds the allowable enlargement rate D / D0 include the dimensions of the shaft material. Due to the error, the axial length L0 of the intermediate part Wa of the shaft material W to be machined is unusually large before machining. For example, a case in which the change in outer diameter ΔD after machining is particularly large can be cited. With respect to a constant displacement of the holding part 2, the larger the axial length L0 before machining, the larger the change in the outer diameter of the intermediate part Wa. The quantity ΔD becomes large. And when (D0+ΔD) / D0 > D / D0, then in Figure 5B... The probability corresponding to the enlargement rate (D0+ΔD) / D0 on the interpolation curve of the shown test data is for the shaft material W Cracks are expected to occur in the outer circumference Wd. Therefore, the control unit 13 (D0 + ΔD) If / D0 > D / D0, it is judged as a failure. The judgment result is, for example, controlled by the control unit 13. The information is displayed on the display unit 12 under the supervision of the supervisor, and the worker is notified.

[0061] In this way, by determining whether or not cracks have occurred in the outer peripheral portion Wd of the shaft material W based on the enlargement rate of the middle portion Wa of the shaft material W, the determination can be made immediately after the completion of processing, thereby saving the time and cost required for inspection for the presence or absence of cracks.

[0062] Furthermore, the pass / fail determination of crack occurrence in the outer peripheral portion Wd based on the enlargement rate and allowable enlargement rate of the intermediate portion Wa, as shown in Figure 7, can also be performed in combination with the pass / fail determination of crack occurrence in the connecting portion Wc based on the number of rotations of the shaft material W, as shown in Figure 6.

[0063] As described above, the method for setting processing conditions for shaft enlargement processing disclosed herein is a method for setting processing conditions for shaft enlargement processing, which involves applying an axial compressive force and a bending angle to the axial middle portion of a shaft material and rotating the shaft material around its axis to enlarge the middle portion of the shaft material radially. The method is based on test data obtained by performing shaft enlargement processing on a test shaft material of the same material and shape as the shaft material, which shows the relationship between the number of rotations of the test shaft material required to enlarge the middle portion of the test shaft material to a predetermined outer diameter and the probability of crack occurrence at the connection between the middle portion of the test shaft material and the shaft portion excluding the middle portion. Based on this test data, an allowable number of rotations is set such that the probability of crack occurrence at the connection is below a threshold, and the number of rotations of the shaft material when enlarging the middle portion of the shaft material to the predetermined outer diameter in the shaft enlargement processing is set to be below the allowable number of rotations.

[0064] Furthermore, the method for setting processing conditions for shaft enlargement processing disclosed herein is obtained by performing shaft enlargement processing on the test shaft material at the same bending angle as the shaft enlargement processing on the shaft material, as described above.

[0065] Furthermore, the method for setting processing conditions for shaft enlargement processing disclosed herein is a method for setting processing conditions for shaft enlargement processing, in which the intermediate part of a shaft material is enlarged radially by rotating the shaft material around its axis while applying an axial compressive force and a bending angle to the intermediate part of the shaft material, and based on test data obtained by performing shaft enlargement processing on a test shaft material of the same material and shape as the shaft material, the method sets an allowable enlargement rate such that the probability of crack occurrence on the outer circumference is below a threshold, and the enlargement rate of the intermediate part of the shaft material when enlarging the intermediate part of the shaft material to a predetermined outer diameter in shaft enlargement processing is set to be below the allowable enlargement rate.

[0066] Furthermore, the shaft enlargement method disclosed herein is a shaft enlargement method that enlarges the intermediate portion of a shaft material radially by rotating the shaft material around its axis while applying an axial compressive force and a bending angle to the intermediate portion of the shaft material, and determines whether the shaft material is acceptable or not based on the number of rotations of the shaft material required to enlarge the intermediate portion of the shaft material to a predetermined outer diameter.

[0067] Furthermore, the shaft enlargement processing method disclosed herein is based on test data obtained by performing shaft enlargement processing on a test shaft material of the same material and shape as the shaft material, which shows the relationship between the number of rotations of the test shaft material required to enlarge the intermediate portion of the test shaft material to the predetermined outer diameter and the probability of crack occurrence at the connection between the intermediate portion of the test shaft material and the shaft portion excluding the intermediate portion. An allowable number of rotations is set such that the probability of crack occurrence at the connection is below a threshold. The shaft material is judged to be acceptable if the number of rotations of the shaft material is below the allowable number of rotations, and the shaft material is judged to be unacceptable if the number of rotations of the shaft material exceeds the allowable number of rotations.

[0068] Furthermore, the shaft enlargement method disclosed herein is obtained by performing shaft enlargement on the test shaft material at the same bending angle as the shaft enlargement process performed on the shaft material, as described above.

[0069] Furthermore, the shaft enlargement processing method disclosed herein is based on test data obtained by performing shaft enlargement processing on the test shaft material, which shows the relationship between the enlargement rate, which is the ratio of the outer diameter after processing to the outer diameter before processing of the intermediate part of the test shaft material, and the probability of crack occurrence in the outer circumference of the intermediate part of the test shaft material. An allowable enlargement rate is set such that the probability of crack occurrence in the outer circumference is below a threshold, and the enlargement rate of the intermediate part of the shaft material when enlarging the intermediate part of the shaft material to the predetermined outer diameter is set to be less than or equal to the allowable enlargement rate.

[0070] Furthermore, the shaft enlargement method disclosed herein is a method for enlarging a shaft material radially by rotating the shaft material around its axis while applying an axial compressive force and a bending angle to the shaft material's axial middle portion, and determining whether the shaft material is acceptable or not based on the enlargement rate, which is the ratio of the outer diameter after processing to the outer diameter before processing of the shaft material's middle portion.

[0071] Furthermore, the shaft enlargement processing method disclosed herein is based on test data obtained by performing shaft enlargement processing on a test shaft material of the same material and shape as the shaft material, which shows the relationship between the enlargement rate, which is the ratio of the outer diameter after processing to the outer diameter before processing of the intermediate part of the test shaft material, and the probability of crack occurrence at the outer circumference of the intermediate part of the test shaft material. An allowable enlargement rate is set such that the probability of crack occurrence at the outer circumference is below a threshold. The shaft material is judged to be acceptable if the enlargement rate of the shaft material is below the allowable enlargement rate, and the shaft material is judged to be unacceptable if the enlargement rate of the shaft material exceeds the allowable enlargement rate.

[0072] Furthermore, the shaft enlargement processing apparatus disclosed herein comprises: a pair of holding parts that hold the shaft material at a distance from each other in the axial direction of the shaft material; a pressurizing part that reduces the distance between the pair of holding parts and applies an axial compressive force to the intermediate part of the shaft material positioned between the pair of holding parts; a bending part that tilts one of the pair of holding parts relative to the other holding part to apply a bending angle to the intermediate part of the shaft material; a rotating part that rotates the pair of holding parts and the shaft material around the axis of the shaft material; a rotation count detection part that detects the number of rotations of the shaft material; and a control unit that controls the pressurizing part, the bending part, and the rotating part to rotate the shaft material around its axis while applying an axial compressive force and a bending angle to the intermediate part of the shaft material, thereby enlarging the intermediate part of the shaft material to a predetermined outer diameter. The control unit determines whether the shaft material is acceptable or unacceptable based on the number of rotations of the shaft material required until the intermediate part of the shaft material is enlarged to the predetermined outer diameter.

[0073] Furthermore, the shaft enlargement processing apparatus disclosed herein includes: a pair of holding parts that hold the shaft material at a distance from each other in the axial direction of the shaft material; a pressing part that reduces the distance between the pair of holding parts and applies an axial compressive force to the intermediate part of the shaft material positioned between the pair of holding parts; a bending part that tilts one of the pair of holding parts relative to the other holding part to apply a bending angle to the intermediate part of the shaft material; a rotating part that rotates the pair of holding parts and the shaft material around the axis of the shaft material; an axial displacement detection part that detects the amount of change in the distance between the pair of holding parts; and the shaft material The system includes a radial displacement detection unit that detects the amount of change in the outer diameter of the intermediate part of the shaft, and a control unit that controls the pressurizing unit, the bending unit, and the rotating unit to apply an axial compressive force and a bending angle to the intermediate part of the shaft, rotate the shaft around its axis, and reduce the distance between the pair of holding units by a predetermined amount, thereby enlarging the intermediate part of the shaft. The control unit determines an enlargement rate, which is the ratio of the outer diameter after processing to the outer diameter before processing of the intermediate part of the shaft, based on the amount of change in the outer diameter of the intermediate part of the shaft, and determines whether the shaft is acceptable or not based on the determined enlargement rate. [Explanation of symbols]

[0074] 1-axis enlargement processing equipment 2 Holding part 3 Holding part 4 Pressurized section 5. Bent section 6. Rotating parts 7. Rotation count detection unit 8 Control Panel 9. Axial displacement detection unit 10 Radial displacement detection unit 11 Control section 12 Display section 13 Control Unit A reference line W shaft material Wa (middle section) Wb shaft part Wc connection Wd outer perimeter

Claims

1. A shaft enlargement method is provided, wherein the shaft is rotated around its axis while an axial compressive force and a bending angle are applied to the shaft's axial middle portion, thereby enlarging the middle portion of the shaft radially. A shaft enlargement processing method for determining whether a shaft material is acceptable or unacceptable based on the enlargement rate, which is the ratio of the outer diameter after processing to the outer diameter before processing of the intermediate part of the shaft material.

2. A method for processing shaft enlargement according to claim 1, Based on test data obtained by performing shaft enlargement processing on a test shaft material of the same material and shape as the aforementioned shaft material, and which shows the relationship between the enlargement rate, which is the ratio of the outer diameter after processing to the outer diameter before processing of the intermediate part of the test shaft material, and the probability of crack occurrence at the outer circumference of the intermediate part of the test shaft material, an allowable enlargement rate is set such that the probability of crack occurrence at the outer circumference is below a threshold. A shaft enlargement processing method comprising determining that the shaft material is acceptable if its enlargement rate is less than or equal to the allowable enlargement rate, and determining that the shaft material is unacceptable if its enlargement rate exceeds the allowable enlargement rate.

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