Inspection method, inspection device, and manufacturing method for planetary gear support shaft

Abstract

To inspect the presence or absence of cracks with high accuracy.SOLUTION: An inspection method for a planetary gear support shaft that has a center hole that is open only on an end face on one side in an axial direction and that is formed by a deep end portion that is closed on the other side in the axial direction, includes: injecting an ultrasonic wave from a probe into an outer peripheral surface of the planetary gear support shaft, in a direction inclined with respect to a central axis of the planetary gear support shaft, from one side in the axial direction toward a radially outside of the deep end portion on the other side in the axial direction; receiving the ultrasonic wave reflected inside the planetary gear support shaft by the probe; and determining whether there is a crack inside the planetary gear support shaft based on the received waveform.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for inspecting a planetary gear support shaft that supports a planetary gear incorporated in a planetary gear unit constituting, for example, an automatic transmission for an automobile so as to be rotatable relative to a carrier. [Background technology]

[0002] A structure including a torque converter and a planetary gear set is widely used as an automatic transmission for automobiles. The planetary gear set includes a sun gear, a ring gear arranged around the sun gear, and a plurality of planetary gears meshed with the sun gear and the ring gear. Each planetary gear is rotatably supported by a carrier via a support shaft. Specifically, each planetary gear is rotatably supported by a plurality of needles around a support shaft supported and fixed to the carrier. That is, each needle is in rolling contact with the outer peripheral surface of an axial middle portion of each support shaft. In other words, the outer peripheral surface of an axial middle portion of each support shaft forms an orbital surface.

[0003] JP 2013-228032 A (Patent Document 1) describes a support shaft for planetary gears that is provided with an oil supply passage consisting of a bottomed central hole that opens only to one end face in the axial direction and branch holes that communicate with the outer circumferential surface and the inner circumferential surface of the central hole. In the support shaft described in JP 2013-228032 A, lubricating oil can be supplied through the oil supply passage to the rolling contact portion between the outer circumferential surface of the support shaft and the needle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-228032 A Summary of the Invention [Problem to be solved by the invention]

[0005] The support shaft described in JP 2013-228032 A is manufactured by forming an oil supply passage by cutting (boring) using a drill, and then performing a quenching process to form a quench-hardened layer at the rolling contact portion with the needle. The quenching process is performed, for example, by heating the support shaft with a high-frequency induction coil, and then spraying cooling water onto the surface of the support shaft to rapidly cool it. Therefore, transformation stress is generated in the support shaft in the temperature range where martensitic transformation begins on the surface of the support shaft (for example, 200°C to 300°C in the case of SUJ2). In addition, internal stress is generated due to the difference in thermal expansion based on the temperature difference between the surface and the core of the support shaft.

[0006] Such transformation stress and internal stress may be applied to a part of the support shaft as a large tensile stress that may lead to cracks. In particular, the corner of the central hole that connects the conical portion at the inner end and the cylindrical portion at the opening side is prone to stress concentration and cracks. If cracks occur at the corner, the strength and durability of the support shaft will be impaired. Therefore, a method is needed that can non-destructively inspect the presence or absence of cracks inside the support shaft without cutting the support shaft.

[0007] A method of using an ultrasonic probe can be considered as a method of non-destructively inspecting the presence or absence of cracks inside a metal support shaft. Specifically, as shown in FIG. 6, the probe 100 is vertically abutted against the outer circumferential surface of a support shaft 102 having an oil supply passage 101 inside, and ultrasonic waves U are emitted from the probe 100. i While transmitting the ultrasonic wave toward the inside of the support shaft 102, the ultrasonic wave (reflected wave) U reflected inside the support shaft 102 r The reflected wave U from the inside of the support shaft 102 is received by the probe 100. This operation is performed while rotating the support shaft 102 and displacing the probe 100 in the axial direction of the support shaft 102. r By observing the waveform, it is judged whether or not a crack C has occurred in the corner portion 103c of the central hole 103 of the support shaft 102, the corner portion 103c connecting the conical portion 103a and the cylindrical portion 103b.

[0008] However, reflection of ultrasonic waves inside the support shaft 102 occurs not only from cracks C, but also from the contact area between the probe 100 and the outer circumferential surface of the support shaft 102, and from the boundary between the metal material constituting the support shaft 102 and the space existing within the central hole 103. Furthermore, when the reflected waves from cracks C, the contact areas, or the boundaries reach cracks C, contact areas, or boundaries located ahead in the propagation direction (traveling direction) of the respective reflected waves, they are reflected again (multiple reflection occurs). Therefore, the waves received by the probe 100 are a composite of many reflected waves, as shown in FIG. 7, and many peaks are detected. As a result, the reflected wave U from crack C r It may become difficult to determine whether or not cracks are present, and it may become difficult to inspect for the presence or absence of cracks C with high precision.

[0009] The present invention has been made to solve the above-mentioned problems, and has an object to provide a method for inspecting a planetary gear support shaft that can inspect for the presence or absence of cracks with high accuracy. [Means for solving the problem]

[0010] A method for inspecting a planetary gear support shaft according to one aspect of the present invention includes the steps of: The present invention relates to a planetary gear support shaft having a central hole that is open only on one end face in the axial direction and is formed by a rear end portion that is closed on the other axial side.

[0011] In one aspect of the present invention, a method for inspecting a planetary gear support shaft includes: Ultrasonic waves from a probe are incident on the outer surface of the planetary gear support shaft in a direction inclined with respect to the central axis of the planetary gear support shaft from one axial side toward the radially outward direction of the inner end portion on the other axial side, and the ultrasonic waves reflected inside the planetary gear support shaft are received by the probe. Based on the received waveform, the presence or absence of cracks inside the planetary gear support shaft is determined.

[0012] In one embodiment of the inspection method for a planetary gear support shaft of the present invention, the ultrasonic waves can be incident on the outer peripheral surface of the planetary gear support shaft in a direction such that the refraction angle of the ultrasonic waves is 45 degrees or more and 70 degrees or less, preferably 58.5 degrees or more and 61.5 degrees or less.

[0013] An inspection device for a planetary gear support shaft according to one aspect of the present invention comprises: The subject of this specification is a planetary gear support shaft having a center hole that opens only to one end face on one axial side.

[0014] An inspection device for a planetary gear support shaft according to one aspect of the present invention comprises: a support means for supporting the planetary gear support shaft; The planetary gear support shaft includes a probe that receives the ultrasonic waves that are incident on an outer peripheral surface of the planetary gear support shaft in a direction inclined with respect to a central axis of the planetary gear support shaft and are reflected inside the planetary gear support shaft.

[0015] In the planetary gear support shaft inspection device according to one aspect of the present invention, the incident angle of the ultrasonic waves with respect to the planetary gear support shaft can be set to be equal to or greater than 31.4 degrees and equal to or less than 56.4 degrees.

[0016] In one aspect of the present invention, in an inspection device for a planetary gear support shaft, the probe is supported so as to be able to move only toward and away from the outer peripheral surface of the planetary gear support shaft, and can have an abutment surface on the surface facing the outer peripheral surface of the planetary gear support shaft.

[0017] In one aspect of the inspection device for a planetary gear support shaft of the present invention, the support means can have a shaft portion that is inserted into a central hole of the planetary gear support shaft, and a step surface that bends radially outward from one axial end of the shaft portion and is abutted against an end face on one axial end of the planetary gear support shaft.

[0018] A method for manufacturing a planetary gear support shaft according to one aspect of the present invention includes the steps of: The subject of this specification is a planetary gear support shaft having a center hole that opens only to one end face on one axial side.

[0019] A method for manufacturing a planetary gear support shaft according to one aspect of the present invention includes the steps of: The method includes an inspection process in which ultrasonic waves are emitted from a probe to the outer peripheral surface of the planetary gear support shaft in a direction inclined with respect to the central axis of the planetary gear support shaft, the ultrasonic waves reflected inside the planetary gear support shaft are received by the probe, and the presence or absence of cracks inside the planetary gear support shaft is determined based on the received waveform.

[0020] In one embodiment of the manufacturing method for a planetary gear support shaft of the present invention, in the inspection process, the ultrasonic waves can be incident on the outer peripheral surface of the planetary gear support shaft in a direction such that the refraction angle of the ultrasonic waves is 45 degrees or more and 70 degrees or less, preferably 58.5 degrees or more and 61.5 degrees or less. Effect of the Invention

[0021] According to the method for inspecting a planetary gear support shaft of one aspect of the present invention, the presence or absence of cracks can be inspected with high accuracy. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a view showing an example of a planetary gear device incorporating a planetary gear support shaft according to the present invention, as viewed from the axial direction. [Diagram 2] FIG. 2 is a cross-sectional view taken along line XX in FIG. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing an example of a planetary gear support shaft according to the present invention. [Figure 4] FIG. 4 is a schematic cross-sectional view showing a method for inspecting a planetary gear support shaft according to one embodiment of the present invention. [Diagram 5] FIG. 5 is a diagram showing a schematic diagram of a waveform received by a probe in one embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view showing a conventional example of an inspection method for a planetary gear support shaft. [Figure 7] FIG. 7 is a diagram showing a schematic diagram of a waveform received by a probe in a conventional example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] An example of an embodiment of the present invention will be described with reference to Figures 1 to 5. A planetary gear support shaft 1 according to this example is incorporated into a planetary gear device 2 constituting, for example, an automatic transmission or a transaxle for an automobile. As shown in Figures 1 and 2, the planetary gear device 2 includes a sun gear 3, a ring gear 4, a carrier 5, and a plurality of planetary gears 6.

[0024] The sun gear 3 has teeth 3a on its outer circumferential surface and is connected to a drive shaft (not shown) so as to rotate integrally with the drive shaft, i.e., so as to rotate in the same direction and at the same speed as the drive shaft.

[0025] The ring gear 4 has teeth 4a on its inner peripheral surface, is supported and fixed coaxially around the sun gear 3, and does not rotate even during use.

[0026] Carrier 5 is supported coaxially with sun gear 3 and ring gear 4, and is connected to driven shaft 7 so as to rotate integrally with said driven shaft 7. Carrier 5 includes a base plate 8 having a substantially L-shaped cross section, and a connecting plate 9 in the shape of a hollow circular plate.

[0027] Board 8 is , medium It has a hollow circular plate-shaped side plate portion 10 and a cylindrical portion 11 bent from a radially inner end of the side plate portion 10 toward one axial side (the right side in Fig. 2). The side plate portion 10 has circular holes 12a penetrating in the axial direction at multiple locations in the circumferential direction. The cylindrical portion 11 is externally fitted and fixed to the driven shaft 7 by spline engagement or the like so as to be capable of transmitting torque.

[0028] The connecting plate 9 has circular holes 12b penetrating in the axial direction at multiple positions in the circumferential direction, and is disposed coaxially with the base plate 8 and spaced apart from the side plate portion 10 on the other axial side (the left side in FIG. 2).

[0029] The multiple planetary gears 6 are arranged at multiple locations in the circumferential direction between the sun gear 3 and the ring gear 4, and are supported by the carrier 5 so as to be able to freely rotate (spin) about their own central axis via the planetary gear support shaft 1 and the multiple needles 13. Each planetary gear 6 has, on its outer circumferential surface, teeth 6a that mesh with the teeth 3a of the sun gear 3 and the teeth 4a of the ring gear 4, and has, on its inner circumferential surface, an outer diameter side raceway surface 6b with which the multiple needles 13 roll and come into contact.

[0030] Each planetary gear 6 is supported to rotate freely around its own central axis around the planetary gear support shaft 1 by supporting a plurality of needles 13 for rolling between the outer diameter side raceway surface 6b and the outer peripheral surface of the axially middle portion of the planetary gear support shaft 1. Also, each planetary gear support shaft 1 has one axial end non-rotatably fitted into the circular hole 12a of the side plate portion 10, and has the other axial end non-rotatably fitted into the circular hole 12b of the connecting plate 9.

[0031] Each planetary gear support shaft 1 is made of high carbon chromium bearing steel (SUJ2 to SUJ4 (JIS G 4805)), 100CrMnSi6-4 (ISO 683-17), etc.), chrome molybdenum steel (SCM420 (JIS G 4105)), carbon tool steel (SK5 (JIS G 4401), etc. ) The planetary gear support shaft 1 is cylindrical and made of a metal material that can be subjected to induction hardening. The planetary gear support shaft 1 has an inner diameter side raceway surface 14, an oil supply passage 15, and a hardened layer 16.

[0032] The outer diameter and axial length of the planetary gear support shaft 1 are appropriately determined depending on the application of the planetary gear device 2 in which the planetary gear support shaft 1 is incorporated. For example, in the case of the planetary gear support shaft 1 that is used by being incorporated into the planetary gear device 2 constituting an automatic transmission for an automobile, the outer diameter D can be 5 mm or more and 40 mm or less.

[0033] The inner diameter side raceway surface 14 is provided on the outer circumferential surface of the planetary gear support shaft 1 at an axially intermediate portion thereof, and is in rolling contact with the plurality of needles 13 when in use.

[0034] The oil supply passage 15 has a function of supplying lubricating oil to the rolling contact portions between the inner diameter side raceway surface 14 and the outer diameter side raceway surface 6b and each of the needles 13. The oil supply passage 15 has a central hole 17 and branch holes 18.

[0035] The center hole 17 is formed so as to extend in the axial direction in the center of the planetary gear support shaft 1, and is configured as a bottomed hole (blind hole) that opens only to one axial end face of the planetary gear support shaft 1. The center hole 17 has a conical portion 17a at the inner end (hole bottom), which is the end on the other axial side, with the inner diameter decreasing toward the other axial side, and a cylindrical portion 17b, whose inner diameter does not change in the axial direction, located on one axial side of the conical portion 17a.

[0036] Inner diameter of center hole 17 (inner diameter of cylindrical portion 17b) d 17 can be set to 5% or more and 85% or less of the outer diameter D of the planetary gear support shaft 1.

[0037] The apex angle α of the cone portion 17a is equal to the point angle of the drill used to form the center hole 17, and can be, for example, 110 degrees or more and 150 degrees or less, preferably 115 degrees or more and 140 degrees or less.

[0038] The branch hole 18 is formed by a through hole that communicates between the outer circumferential surface of the planetary gear support shaft 1 and the inner circumferential surface of the center hole 17 .

[0039] The planetary gear support shaft 1 of this example has one branch hole 18, and the one branch hole 18 is formed in the radial direction at the axial center position of the planetary gear support shaft 1. In other words, the branch hole 18 communicates between the axial center position of the outer circumferential surface of the planetary gear support shaft 1 and the inner circumferential surface of a portion of the cylindrical portion 17b of the center hole 17 that is slightly shifted to one axial side from the other axial end (corner portion 17c that is the connection portion with the conical portion 17a).

[0040] The quench-hardened layer 16 is formed on the surface layer of the planetary gear support shaft 1 by performing induction hardening on at least an axially intermediate portion of the planetary gear support shaft 1 including the inner diameter side raceway surface 14, and does not reach the inner peripheral surface of the center hole 17 (cylindrical portion 17b). In other words, the planetary gear support shaft 1 has a non-hardened portion 19 around the entire circumference of the center hole 17 and in the center of the portion deviated from the center hole 17 to the other axial direction side.

[0041] The quench-hardened layer 16 is a portion hardened by induction hardening and has a Vickers hardness (Hv) of 550 or more, while the non-hardened portion 19 is a portion having a Vickers hardness (Hv) of less than 550.

[0042] The planetary gear support shaft 1 is produced by forming a central hole 17 and branch holes 18 in a cylindrical material by cutting (drilling) using a drill, and then performing high-frequency hardening on the axial middle portion including the inner diameter side raceway surface 14 to form a hardened layer 16 on the surface layer portion of the planetary gear support shaft 1.

[0043] During the hardening process, when the planetary gear support shaft 1 is heated by a high-frequency induction coil and then rapidly cooled by cooling water or the like, transformation stress and internal stress are generated in the planetary gear support shaft 1. Then, based on such transformation stress and internal stress, a large tensile stress is applied to the corner portion 17c connecting the conical portion 17a and the cylindrical portion 17b of the center hole 17, and cracks C may occur in the corner portion 17c. If cracks C occur in the corner portion 17c, the strength and durability of the planetary gear support shaft 1 may be impaired. Therefore, the manufacturing method of the planetary gear support shaft of this example includes an inspection process for non-destructively inspecting the presence or absence of cracks C. The inspection method of the planetary gear support shaft in the inspection process will be described next.

[0044] The feature of the inspection method for the planetary gear support shaft of this example is that ultrasonic waves from the probe 21 are incident on the outer surface of the planetary gear support shaft 1 in a direction inclined with respect to the central axis O of the planetary gear support shaft 1, the ultrasonic waves reflected inside the planetary gear support shaft 1 are received by the probe 21, and the presence or absence of a crack C inside the planetary gear support shaft 1 is determined based on the received waveform.

[0045] The inspection device used in the method for inspecting the planetary gear support shaft includes a jig 27 and a probe 21.

[0046] Jig 27 regulates the axial orientation of planetary gear support shaft 1 and positions planetary gear support shaft 1 in the axial and radial directions. That is, in this example, jig 27 constitutes a support means. Jig 27 has a head 28 and a shaft portion 29 that protrudes from the center of the other axial side surface of head 28 toward the other axial side. Head 28 has an outer diameter larger than the inner diameter of center hole 17 (cylindrical portion 17b) of planetary gear support shaft 1, and shaft portion 29 has an outer diameter smaller than the inner diameter of center hole 17.

[0047] The probe 21 includes a wedge member 22 and a measuring portion 23 .

[0048] The wedge member 22 has a shape like a rectangular parallelepiped with one side cut off. That is, as shown in Fig. 4, the wedge member 22 has an abutment surface 24 on a lower side facing the outer circumferential surface of the planetary gear support shaft 1, and an inclined surface portion 25 on one axial side of the upper side, which is inclined downward as it approaches that side in the axial direction.

[0049] In this example, the abutment surface 24 is configured as a flat surface parallel to the central axis O of the planetary gear support shaft 1 in a state in which the planetary gear support shaft 1 is supported by a jig 27. However, when implementing the present invention, the abutment surface can also be configured as a cylindrical concave curved surface with a larger radius of curvature than the outer circumferential surface of the planetary gear support shaft.

[0050] The wedge member 22 is supported by a housing of an inspection device (not shown) so as to be movable only toward and away from the planetary gear support shaft 1 (displacement in the vertical direction in FIG. 4).

[0051] The wedge member 22 is made of a material that can reduce the attenuation of ultrasonic waves emitted from the transducer 26. Specifically, the wedge member 22 can be made of a synthetic resin such as an acrylic resin, polyetherimide, polystyrene, or polyimide.

[0052] The measuring unit 23 has a cylindrical shape and has a transducer 26 at its tip, which has both a transmitting function for transmitting ultrasonic waves and a receiving function for receiving reflected waves. That is, in this example, the probe 21 is configured as a single-transducer probe. However, when implementing the present invention, the ultrasonic probe can also be configured as a dual-transducer probe having a transmitting transducer and a receiving transducer. In any case, in this example, the probe 21 has a receiving section for receiving reflected waves at the same position or approximately the same position as the transmitting section for transmitting ultrasonic waves.

[0053] Measuring unit 23 is supported and fixed to inclined surface portion 25 of wedge member 22 with its own central axis perpendicular to inclined surface portion 25. Specifically, the tip of measuring unit 23 is embedded in wedge member 22. This allows ultrasonic waves to be emitted from transducer 26 in a direction inclined to central axis O of planetary gear support shaft 1. In short, in this example, probe 21 is configured as a so-called bevel probe.

[0054] When inspecting the presence or absence of cracks C inside the planetary gear support shaft 1, first, the shaft portion 29 of the jig 27 is inserted into the central hole 17 of the planetary gear support shaft 1, and the other axial side surface of the head 28 is abutted against one axial end surface of the planetary gear support shaft 1. This restricts the axial orientation of the planetary gear support shaft 1 and positions the planetary gear support shaft 1 in both the axial and radial directions. That is, in this example, a step surface is formed by the other axial side surface of the head 28.

[0055] In carrying out the present invention, the axial and radial positioning of the planetary gear support shaft 1 can be performed by any method, not limited to the method using the jig 27 as described above. In any case, the axial position of the planetary gear support shaft 1 is determined by ultrasonic waves U transmitted from the vibrator 26 and incident on the planetary gear support shaft 1, as described later. i is restricted in relation to the axial position of the probe 21 so as to pass radially outside the corner 17c of the center hole 17.

[0056] Next, the wedge member 22 of the probe 21 is displaced in a direction approaching the planetary gear support shaft 1 , that is, downward, until the abutment surface 24 comes into contact with the outer circumferential surface of the planetary gear support shaft 1 .

[0057] In addition, a couplant (coupling medium) is applied in advance to the abutment surface 24 and / or the outer circumferential surface of the planetary gear support shaft 1. As a result, a couplant is interposed at the abutment portion between the abutment surface 24 and the planetary gear support shaft 1. The reason for interposing a couplant at the abutment portion between the abutment surface 24 and the planetary gear support shaft 1 is to stabilize the input and output of ultrasonic waves to the planetary gear support shaft 1. In this example, as the couplant, oils with relatively low viscosity are used, such as hydraulic oil used when machining the center hole 17, lubricating oil used to lubricate the needle 13 and the inner diameter side raceway surface 14, and rust-preventing oil. Specifically, oils with a viscosity of about ISO VG 20 to 80 (about 0.02 Pa·s to 0.08 Pa·s) are used as the couplant.

[0058] With the abutment surface 24 in contact with the outer circumferential surface of the planetary gear support shaft 1, the transducer 26 of the probe 21 is energized to transmit ultrasonic waves, so that the ultrasonic waves are incident on the outer circumferential surface of the planetary gear support shaft 1 from one axial side toward the radially outer side of the conical portion 17a (rear end portion) of the central hole 17 on the other axial side in a direction inclined with respect to the central axis O of the planetary gear support shaft 1. Specifically, the incident angle θ of the ultrasonic waves with respect to the planetary gear support shaft 1 is i is set to 31.4 degrees or more and 56.4 degrees or less, preferably 44.9 degrees or more and 47.9 degrees or less, and the refraction angle θ of the ultrasonic wave penetrating (transmitting) into the planetary gear support shaft 1 is set to ris set to be 45 degrees or more and 70 degrees or less, and preferably 58.5 degrees or more and 61.5 degrees or less.

[0059] The ultrasonic wave is emitted from the oscillator 26 as a pulse signal having a predetermined pulse length (pulse width) once or intermittently at predetermined intervals. The frequency, pulse length and amplitude of the ultrasonic pulse signal are appropriately determined depending on the metal material constituting the planetary gear support shaft 1 and the outer diameter of the planetary gear support shaft 1. Specifically, for example, the frequency of the ultrasonic pulse signal can be set to 2 MHz or more and 5 MHz or less, and preferably 3.5 MHz or more and 5 MHz or less.

[0060] In this example, the ultrasound is Planetary gear support shaft 1 The ultrasonic wave U (the wave that penetrated into the planetary gear support shaft 1) is incident on the outer peripheral surface of the planetary gear support shaft 1 from one axial side toward the radially outer side of the conical portion 17a (the inner end portion) of the center hole 17 on the other axial side in a direction inclined with respect to the central axis O of the planetary gear support shaft 1. i The penetration wave U passes through the radially outer portion of the corner 17c of the central hole 17 where a crack C may occur. i The central axis of the center hole 17 passes through a portion located radially outwardly of the corner 17c of the center hole 17 by −1 mm or more and 2 mm or less, preferably 0 mm or more and 1 mm or less. In this way, when a crack C occurs, the reflected wave U from the crack C is r While enabling the oscillator 26 to receive the reflected waves from the boundary between the metal material constituting the planetary gear support shaft 1 and the space existing within the central hole 17, the oscillator 26 is prevented from receiving the reflected waves from the boundary between the metal material constituting the planetary gear support shaft 1 and the space existing within the central hole 17.

[0061] Intrusion Wave U i When it reaches the crack C, a part of it is reflected and becomes the reflected wave U r The remaining part is transmitted and becomes the transmitted wave U t That is, when a crack C occurs, after an ultrasonic pulse is emitted from the transducer 26, a reflected wave U having a certain amplitude or more is generated within a predetermined time. rIf no crack C has occurred, no reflected wave is received. Therefore, by observing the waveform of the wave received by the transducer 26, it is possible to determine whether or not a crack C has occurred in the corner 17c. Specifically, for example, after an ultrasonic pulse is transmitted from the transducer 26, a reflected wave U having a certain amplitude or more (S / N ratio of a predetermined value or more) is received within a predetermined time. r If this signal is received, it can be determined that a crack C has occurred in the corner 17c.

[0062] In addition, the larger the crack C, the greater the reflectivity at the crack C, so the reflected wave U received by the transducer 26 r The amplitude of the reflected wave U r By measuring the amplitude of the crack, the size of the crack C can be estimated.

[0063] The above-mentioned work is performed on the entire circumference of the planetary gear support shaft 1 while rotating it, and the corners 17c are inspected for cracks C. Then, the planetary gear support shaft 1 in which cracks C have occurred (cracks C of a predetermined size or more) is excluded from being shipped as a defective product.

[0064] In the inspection method for the planetary gear support shaft of this embodiment, ultrasonic waves transmitted from the transducer 26 of the probe 21 are incident on the planetary gear support shaft 1 in a direction inclined with respect to the central axis of the planetary gear support shaft 1. i By passing through the radially outer portion of the corner portion 17c of the central hole 17, if a crack C occurs, the reflected wave U from the crack C is r While the transducer 26 can receive the reflected waves from the boundary between the metal material constituting the planetary gear support shaft 1 and the space existing in the center hole 17, the transducer 26 is prevented from receiving the reflected waves from the boundary. In other words, the reflected waves from the boundary can be prevented from being superimposed on the waveform received by the probe 21, and if a crack C occurs, the reflected waves U from the crack C can be prevented from being superimposed on the waveform received by the probe 21. r Therefore, the presence or absence of cracks C can be inspected with high accuracy.

[0065] Strictly speaking, the ultrasonic waves emitted from the transducer of the probe 21 are also reflected at the contact portion between the abutment surface 24 of the wedge member 22 constituting the probe 21 and the outer circumferential surface of the planetary gear support shaft 1. Therefore, the reflected wave from the contact portion between the probe 21 and the outer circumferential surface of the planetary gear support shaft 1 is superimposed on the waveform received by the probe 21. That is, as shown in FIG. 5, the reflected wave U from the crack C is r The peak of the reflected wave from the contact portion occurs before the peak of the reflected wave from the contact portion.

[0066] In this example, ultrasonic waves are incident on the planetary gear support shaft 1 in a direction inclined with respect to the central axis O of the planetary gear support shaft 1. As a result, the distance in the propagation direction of the ultrasonic waves between the contact portion between the abutment surface 24 of the wedge member 22 and the outer circumferential surface of the planetary gear support shaft 1 and the crack C can be made longer compared to the case where ultrasonic waves are incident in a direction perpendicular to the central axis of the support shaft 102, as shown in FIG. 6. This allows the time of reception of the reflected wave from the contact portion and the time of the reflected wave U from the crack C to be longer. r The difference between the reception time of the reflected wave U from the crack C can be made larger than that of the method shown in FIG. r This makes it easier to observe, and the presence or absence of cracks C can be inspected with high accuracy.

[0067] Furthermore, in this example, with the planetary gear support shaft 1 positioned in the axial and radial directions by the jig 27, ultrasonic waves are applied from the probe 21 to the planetary gear support shaft 1 to inspect for the presence or absence of cracks C. This makes it possible to precisely regulate the incidence position of the ultrasonic waves applied from the probe 21 to the planetary gear support shaft 1. From this perspective as well, it is possible to inspect for the presence or absence of cracks C with high precision.

[0068] In this embodiment, the wedge member 22 of the probe 21 is supported on the housing of the inspection device so that it can only move toward and away from the planetary gear support shaft 1. When inspecting the planetary gear support shaft 1, the wedge member 22 is displaced in a direction approaching the planetary gear support shaft 1, and the abutting surface 24 is brought into contact with the outer circumferential surface of the planetary gear support shaft 1. This ensures good adhesion between the probe 21 and the outer circumferential surface of the planetary gear support shaft 1. For this reason, as a couplant to be interposed at the abutting portion between the abutting surface 24 and the outer circumferential surface of the planetary gear support shaft 1, a relatively low-viscosity oil, specifically, for example, a hydraulic oil used when machining the center hole 17, a lubricating oil used to lubricate the needle 13 and the inner diameter side raceway surface 14, a rust-preventing oil, or the like, can be used. For this reason, a low-cost oil can be used as the couplant. In addition, since there is no need to clean the couplant after the inspection process, costs can be reduced.

[0069] However, when implementing the present invention, a highly viscous oil, gel, paste, or the like may be used as a couplant to be interposed between the contact portion between the probe and the outer circumferential surface of the planetary gear support shaft. Also, instead of using a couplant, the inspection may be performed by immersing the probe in water or oil. [Explanation of symbols]

[0070] 1 Planetary gear support shaft 2 Planetary gear unit 3. Sun Gear 3a Tooth 4 Ring Gear 4a Tooth 5. Career 6 Planetary Gears 6a Tooth 6b Outer diameter side raceway surface 7 Driven axis 8 Substrate 9 Connecting plate 10 Side plate part 11 Cylindrical part 12a, 12b circular hole 13 Needle 14 Inner diameter raceway surface 15 Fuel Line 16 Hardened layer 17 Center hole 17a Cone section 17b Cylindrical section 17c corner 18 Branch hole 19 Unhardened part 21 Probe 22 Wedge member 23 Measuring part 24 Abutment surface 25 Slope section 26 Transducer 27 Jig 28 head 29 Shaft 100 probe 101 Fuel Line 102 Support shaft 103 Center hole 103a Cone section 103b Cylindrical part 103c Corner

Claims

1. A method for inspecting a planetary gear support shaft, the planetary gear support shaft having a center hole that is open only on one end face in an axial direction and is closed on the other end face in an axial direction, comprising: an ultrasonic wave is applied from a probe to an outer peripheral surface of the planetary gear support shaft in a direction inclined with respect to a central axis of the planetary gear support shaft from one axial side toward the radially outward side of the inner end portion on the other axial side, the ultrasonic wave reflected inside the planetary gear support shaft is received by the probe, and the presence or absence of a crack inside the planetary gear support shaft is determined based on the received waveform. Inspection method for planetary gear support shafts.

2. The ultrasonic wave is incident on the outer circumferential surface of the planetary gear support shaft in a direction such that the refraction angle of the ultrasonic wave is 45 degrees or more and 70 degrees or less. The method for inspecting a planetary gear support shaft according to claim 1.

3. An inspection device for a planetary gear support shaft having a center hole that opens only to one end face on one side in the axial direction, a support means for supporting the planetary gear support shaft; a probe that applies ultrasonic waves to an outer circumferential surface of the planetary gear support shaft in a direction inclined with respect to a central axis of the planetary gear support shaft and receives the ultrasonic waves reflected inside the planetary gear support shaft. Inspection equipment for planetary gear support shafts.

4. an incident angle of the ultrasonic wave with respect to the planetary gear support shaft is 31.4 degrees or more and 56.4 degrees or less; 4. The planetary gear support shaft inspection device according to claim 3.

5. the probe is supported so as to be movable only toward and away from the outer circumferential surface of the planetary gear support shaft, and has an abutment surface on a surface facing the outer circumferential surface of the planetary gear support shaft; 5. The planetary gear support shaft inspection device according to claim 3 or 4.

6. the support means has a shaft portion inserted into a central hole of the planetary gear support shaft, and a step surface bent radially outward from one axial end of the shaft portion and abutted against one axial end face of the planetary gear support shaft. The planetary gear support shaft inspection device according to any one of claims 3 to 5.

7. A manufacturing method of a planetary gear support shaft having a center hole that opens only to one end face on one axial side, comprising the steps of: an inspection step of irradiating ultrasonic waves from a probe onto an outer circumferential surface of the planetary gear support shaft in a direction inclined with respect to a central axis of the planetary gear support shaft, receiving the ultrasonic waves reflected inside the planetary gear support shaft with the probe, and determining the presence or absence of a crack inside the planetary gear support shaft based on the received waveform; A manufacturing method of a planetary gear support shaft.

8. In the inspection step, the ultrasonic waves are incident on the outer circumferential surface of the planetary gear support shaft in a direction such that a refraction angle of the ultrasonic waves is 45 degrees or more and 70 degrees or less. The method for manufacturing the planetary gear support shaft according to claim 7.

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