Manufacturing method for cylindrical elastic coupling device for axial beams

Abstract

This invention provides a novel method for manufacturing a cylindrical elastic coupling device for shaft beams, which improves the mounting accuracy of the stopper member by protecting the screw hole of the inner shaft member during pre-treatment. [Solution] A method for manufacturing a cylindrical elastic coupling device 10 for a shaft beam, comprising: a screw hole protection step of protecting a screw hole 24 opening on the outer circumferential surface of an inner shaft member 12 by blocking it with a screw hole protection member 90; an inner shaft member pre-treatment step of pre-treating the inner shaft member 12, which has been protected by the screw hole protection member 90 in the screw hole protection step; a screw hole protection release step of removing the screw hole protection member 90 from the screw hole 24 of the inner shaft member 12 after the completion of the inner shaft member pre-treatment step; and a stopper mounting step of attaching a stopper member 30 to the inner shaft member 12 by screwing a mounting bolt 50 into the screw hole 24 opened in the screw hole protection release step, thereby limiting the relative displacement between the inner shaft member 12 and a pair of outer split bodies 14a, 14b.

Description

Technical Field

[0001] The present invention relates to a manufacturing method of a cylindrical elastic coupling device for an axle stay that elastically couples one end of an axle stay to a bogie frame of a railway vehicle.

Background Art

[0002] Conventionally, in railway vehicles, a structure in which an axle stay extending from an axle box portion supporting an axle extends in the vehicle longitudinal direction and an end portion of the axle stay is elastically coupled to a bogie frame by a cylindrical elastic coupling device has been generally adopted. As disclosed in Japanese Patent No. 7189809 (Patent Document 1) and the like, this cylindrical elastic coupling device for an axle stay has a structure in which a pair of outer split members (outer portions) extending in the circumferential direction are disposed on the outer peripheral side of an inner shaft member (central shaft), and the inner shaft member and the pair of outer split members are elastically coupled to each other by a main body rubber elastic body (elastic portion). Then, both axial ends of the inner shaft member are attached to the bogie frame, and the outer split member is attached to a cylindrical housing portion provided at one end of the axle stay, so that the axle stay is elastically supported by the bogie frame via the cylindrical elastic coupling device for the axle stay.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, in cylindrical elastic coupling devices for shafts and beams, a stopper member is sometimes provided to limit the relative displacement between the inner shaft member and a pair of outer segments in a specific radial direction where a large load input is expected. That is, in cylindrical elastic coupling devices for shafts and beams, a large load during deceleration is input in the radial direction corresponding to the front and rear of the vehicle, so in Patent Document 1, a stopper member (elastic stopper) is provided that protrudes from the inner shaft member toward the outer circumference in that radial direction. Then, the inner shaft member and the housing portion come into contact with each other via the stopper member, thereby limiting the relative displacement between the inner shaft member and the outer segments in a specific radial direction, improving the durability of the main rubber elastic body and achieving the desired braking performance of the railway vehicle.

[0005] Furthermore, the stopper member described in Patent Document 1 has a through-mounting hole, and is fixed to the inner shaft member by a bolt inserted through the mounting hole being screwed into a threaded hole opening on the outer circumferential surface of the inner shaft member.

[0006] However, in a structure where the stopper member is attached by bolt fixing, during pre-treatment such as cleaning, roughening, and formation of a chemical conversion film performed before vulcanizing and bonding the main rubber elastic body to the inner shaft member, there was a risk of unintended coating or damage to the threads, residual cleaning fluid, or intrusion of foreign matter in the screw holes opening on the outer surface of the inner shaft member. As a result, for example, the mounting strength and stability of the mounting state of the stopper member attached to the inner shaft member, as well as the mounting accuracy such as the direction of protrusion from the inner shaft member and the mounting position, may be insufficient, and the desired stopper performance may not be obtained.

[0007] The problem to be solved by the present invention is to provide a novel method for manufacturing a cylindrical elastic coupling device for shafts and beams, which can improve the mounting accuracy of the stopper member by protecting the screw hole of the inner shaft member to which the stopper member is attached during the pre-treatment of the inner shaft member. [Means for solving the problem]

[0008] The following describes preferred embodiments for understanding the present invention. However, each embodiment described below is illustrative and can be combined with others as appropriate. Furthermore, the multiple components described in each embodiment can be recognized and adopted as independently as possible, and can be combined with any component described in another embodiment as appropriate. Thus, the present invention is not limited to the embodiments described below, and various other embodiments can be realized.

[0009] The first aspect is, A pair of outer segments are arranged on the outer circumference of the inner shaft member, facing each other in a direction perpendicular to the axis, and these inner shaft member and the pair of outer segments are elastically connected to each other by the main rubber elastic body. A method for manufacturing a cylindrical elastic coupling device for an axle beam, wherein the inner axle member is attached to the bogie frame of a railway vehicle, and the pair of outer parts are attached to a cylindrical housing portion provided at one end of the axle beam, thereby elastically connecting the bogie frame and the axle beam, A screw hole protection step is performed in which a screw hole opening on the outer surface of the inner shaft member is covered and protected with a screw hole protection member. The screw hole protection process includes an inner shaft member pretreatment process for fixing the main body rubber elastic body to the inner shaft member, which has its screw hole protected by the screw hole protection member, After the completion of the pre-treatment step for the inner shaft member, a screw hole protection release step is performed, in which the screw hole protection member is removed from the screw hole of the inner shaft member. A stopper mounting step involves attaching a stopper member to the outer circumferential surface of the inner shaft member by screwing a mounting bolt into the screw hole that was opened in the screw hole protection release step, thereby limiting the relative displacement between the inner shaft member and the set of outer parts. including It is.

[0010] According to the manufacturing method of a cylindrical elastic coupling device for shafts and beams according to this embodiment, pre-treatment of the inner shaft member is performed while the screw hole of the inner shaft member is covered and protected with a screw hole protection member, thereby preventing damage to the screw hole due to pre-treatment and the intrusion of foreign matter into the screw hole. Therefore, after the completion of pre-treatment, the stopper member can be stably attached to the inner shaft member by a mounting bolt that is screwed into the screw hole from which the screw hole protection member has been removed. Furthermore, it is also possible to prevent corrosion of the screw hole due to residual cleaning fluid or other substances that have entered the screw hole.

[0011] A second aspect is a method for manufacturing a cylindrical elastic coupling device for an axial beam as described in the first aspect, The opening of the screw hole is provided with a tapered surface that widens toward the outer circumferential surface of the inner shaft member. The screw hole protection member protrudes from the screw hole toward the tapered surface side toward the outer circumference of the inner shaft member. It is.

[0012] According to the manufacturing method of a cylindrical elastic coupling device for shafts and beams according to this embodiment, for example, when a chemical conversion coating or adhesive layer is formed on the surface of the inner shaft member in the inner shaft member pretreatment step, the chemical conversion coating or the like layer is likely to break on the tapered surface when the screw hole protection member is removed after pretreatment. Therefore, it is possible to prevent the chemical conversion coating or the like covering the surface of the inner shaft member from peeling off when the screw hole protection member is removed.

[0013] The tapered surface is positioned further inward than the outer surface of the inner shaft member to which the stopper member is attached, and since the mounting bolt is not screwed into it, even if a fracture in the chemical coating or the like is located on the tapered surface, it will not cause the main rubber elastic body to stick or adversely affect the attachment of the stopper member.

[0014] A third aspect is a method for manufacturing a cylindrical elastic coupling device for an axial beam as described in the second aspect, The projection of the screw hole protection member in the axial direction of the screw hole overlaps with the tapered surface in at least a portion of it. It is.

[0015] According to the manufacturing method of the cylindrical elastic coupling device for shaft bushings according to this aspect, in the inner shaft member pretreatment step, the adhesion of a chemical conversion film or the like to the inner peripheral portion of the tapered surface is prevented by the thread hole protection member, so that it is possible to more reliably prevent the formation of a chemical conversion film or the like in the thread hole, and when removing the thread hole protection member from the thread hole, the chemical conversion film or the like can be more stably broken on the tapered surface.

[0016] The fourth aspect is in the manufacturing method of the cylindrical elastic coupling device for shaft bushings described in the third aspect, the thread hole protection member includes a shaft portion inserted into the thread hole and a head portion having a larger diameter than the shaft portion, and the outer diameter dimension of the head portion of the thread hole protection member is made larger than the maximum diameter dimension of the tapered surface is what is claimed.

[0017] According to the manufacturing method of the cylindrical elastic coupling device for shaft bushings according to this aspect, in the thread hole protection state where the shaft portion of the thread hole protection member is inserted into the thread hole, the head portion of the thread hole protection member and the entire tapered surface overlap each other in the axial projection. For example, when spraying a liquid adhesive or the like on the inner shaft member or applying it with a brush in the inner shaft member pretreatment step, the adhesion of the adhesive or the like to the tapered surface tends to be unstable. As a result, the thickness of the layer of the adhesive or the like covering the tapered surface becomes uneven, and the breakage of the adhesive layer or the like accompanying the removal of the thread hole protection member can be more stably caused on the tapered surface.

[0018] The fifth aspect is in the manufacturing method of the cylindrical elastic coupling device for shaft bushings described in any one of the second to fourth aspects, by performing roughening treatment by blasting as the pretreatment in the inner shaft member pretreatment step, the surface roughness of the portion of the outer peripheral surface of the inner shaft member where the main body rubber elastic body is fixed is made larger than the surface roughness of at least a part of the tapered surface is what is claimed.

[0019] According to the manufacturing method of the cylindrical elastic coupling device for shaft play according to this aspect, when performing roughening treatment by hitting small balls (shots) or the like, since the screw holes are protected by the screw hole protection members, it is possible to prevent small balls or the like from entering the screw holes and prevent the inner surfaces of the screw holes from being damaged by the impact of small balls or the like.

[0020] Since the outer peripheral surface of the inner shaft member to which the main body rubber elastic body is fixed has a larger surface roughness than at least a part of the tapered surface, for example, when forming a chemical conversion film or the like after the roughening treatment, the fixing strength of the chemical conversion film or the like can be obtained to be larger than at least a part of the tapered surface on the outer peripheral surface of the inner shaft member to which the main body rubber elastic body is fixed. Therefore, when removing the screw hole protection member, breakage due to peeling of the chemical conversion film or the like is likely to occur on the tapered surface, and peeling of the chemical conversion film or the like on the outer peripheral surface of the inner shaft member to which the stopper member is attached is more advantageously prevented.

[0021] The sixth aspect is in the manufacturing method of the cylindrical elastic coupling device for shaft play described in any one of the second to fifth aspects, the pre-treatment in the inner shaft member pre-treatment step includes at least one of a chemical conversion film treatment for forming a zinc phosphate film on the surface and an adhesive layer forming treatment for forming a layer of an adhesive on the surface, and at least one of the zinc phosphate film and the adhesive is fixed to at least a part of the tapered surface is the case.

[0022] According to the manufacturing method of the cylindrical elastic coupling device for shaft play according to this aspect, since the screw holes are blocked and protected by the screw hole protection members before performing the inner shaft member pre-treatment step, it is possible to prevent the forming material of the chemical conversion film and / or the adhesive from entering the screw holes in the inner shaft member pre-treatment step.

[0023] By performing a chemical conversion coating treatment and / or adhesive layer formation treatment such that the chemical conversion coating and / or adhesive adhere to at least a portion of the tapered surface (e.g., the outer circumference), it is possible to prevent the formation of areas around the screw holes on the outer circumference of the inner shaft member where the chemical conversion coating and / or adhesive layer is not formed, while also preventing the formation of the chemical conversion coating and / or adhesive layer on the inner surface of the screw holes.

[0024] The seventh aspect is a method for manufacturing a cylindrical elastic coupling device for an axial beam as described in any one of the second to sixth aspects, The inclination angle of the tapered surface with respect to a plane perpendicular to the central axis of the screw hole is within the range of 20 to 60 degrees. It is.

[0025] According to the manufacturing method of a cylindrical elastic coupling device for axial beams according to this embodiment, for example, when roughening treatment by blasting, the contact with the tapered surface of a small ball or the like is appropriately limited, so that the surface roughness of the tapered surface can be made relatively small. In addition, for example, when bonding with adhesive or cleaning with cleaning water, it is possible to prevent excessive accumulation of adhesive or cleaning water on the tapered surface.

[0026] The eighth aspect is a method for manufacturing a cylindrical elastic coupling device for an axial beam as described in any one of the first to seventh aspects, The mounting bolt is a separate component from the screw hole protection member. It is.

[0027] According to the manufacturing method of a cylindrical elastic coupling device for shafts and beams according to this embodiment, even if the screw hole protection member is damaged or soiled in the inner shaft member pretreatment process due to roughening by blasting or adhesion of adhesive, the mounting bolt for attaching the stopper member is a separate component from the screw hole protection member, so that the quality of the cylindrical elastic coupling device for shafts and beams to which the stopper member is attached is not affected.

[0028] The ninth aspect is a method for manufacturing a cylindrical elastic coupling device for an axial beam as described in any one of the first to seventh aspects, The mounting bolt is made of the same material as the screw hole protection member. It is.

[0029] According to the manufacturing method of a cylindrical elastic coupling device for an axial beam that conforms to this embodiment, the mounting bolt and the screw hole protection member are made of the same component, thereby reducing the number of components required to manufacture the cylindrical elastic coupling device for an axial beam.

[0030] The tenth aspect is a method for manufacturing a cylindrical elastic coupling device for an axial beam as described in any one of the first to ninth aspects, The screw hole protection member that closes the screw hole in the screw hole protection step comprises a screw shaft portion that is screwed into the screw hole. It is.

[0031] According to the manufacturing method of a cylindrical elastic coupling device for axial beams according to this embodiment, the screw hole can be easily sealed by screwing the screw hole protection member into the screw hole, The screw-type structure more reliably prevents foreign matter from entering the screw hole, thereby providing a significant advantage in protecting the screw hole.

[0032] The eleventh aspect is a method for manufacturing a cylindrical elastic coupling device for an axial beam as described in the tenth aspect, In the screw hole protection step, the screw shaft portion of the screw hole protection member is screwed into the screw hole for four or more threads. It is.

[0033] According to the manufacturing method of the cylindrical elastic coupling device for axial beams according to this embodiment, the screw-hole protection member is stably attached to the screw hole by screwing, preventing the screw hole protection member from unintentionally falling out of the screw hole. Furthermore, by screwing the screw hole protection member and the screw hole together to a sufficient length, the ingress of liquids such as cleaning fluid into the screw hole can be effectively prevented.

[0034] The twelfth aspect is a method for manufacturing a cylindrical elastic coupling device for an axial beam as described in the tenth or eleventh aspect, In the screw hole protection step, the screwed shaft portion of the screw hole protection member is screwed into the screw hole for a length of 10 times the nominal diameter or less. It is.

[0035] According to the manufacturing method of a cylindrical elastic coupling device for axial beams in accordance with this embodiment, the screw-hole protection member can be attached and detached by preventing the screw-hole protection member from becoming excessively long in the screw-hole area.

[0036] The thirteenth aspect is a method for manufacturing a cylindrical elastic coupling device for an axial beam as described in any one of the first to twelfth aspects, The screw hole protection member comprises a shaft portion that is inserted into the screw hole and a head portion that has a larger diameter than the shaft portion. In the screw hole protection step, the head is separated from the opening periphery of the screw hole. It is.

[0037] According to the manufacturing method of the cylindrical elastic coupling device for shafts and beams according to this embodiment, by using a head with a larger diameter than the shaft, it becomes easier to insert the small-diameter shaft into the screw hole. Furthermore, because the head is separated from the opening periphery of the screw hole when the screw hole protection member is attached to the screw hole, it is less likely that there will be a portion of the outer surface of the inner shaft member that is covered by the head and not subjected to pretreatment, and pretreatment can be performed on the opening periphery of the screw hole as well.

[0038] The fourteenth aspect is a method for manufacturing a cylindrical elastic coupling device for an axial beam as described in any one of the first to third or fifth to twelfth aspects, The screw hole protection member comprises a shaft portion which is inserted into the screw hole, at least a part of it. The outer diameter of the screw hole protection member is maximized at the shaft portion. It is.

[0039] According to the manufacturing method of a cylindrical elastic coupling device for axial beams according to this embodiment, when the shaft portion of the screw hole protection member is inserted into the screw hole, it is possible to prevent the opening periphery of the screw hole from being covered by the screw hole protection member, and to perform pretreatment on the opening periphery of the screw hole as well.

[0040] The fifteenth aspect is a method for manufacturing a cylindrical elastic coupling device for an axial beam as described in any one of the first to fourteenth aspects, The screw hole is formed in a part of the inner shaft member in the radial direction of the inner shaft member through which the screw hole extends. It is.

[0041] According to the manufacturing method of a cylindrical elastic coupling device for shafts and beams in accordance with this embodiment, the screw hole with threads formed therein is partially provided radially with respect to the inner shaft member, thereby preventing the screw hole from becoming unnecessarily long, facilitating the formation of the screw hole, and preventing problems such as cleaning fluid being easily retained and left behind in the screw threads.

[0042] The sixteenth aspect is a method for manufacturing a cylindrical elastic coupling device for an axial beam as described in any one of the first to fifteenth aspects, The aforementioned screw hole penetrates the inner shaft member and is formed along the entire radial length of the inner shaft member. It is.

[0043] According to the manufacturing method of a cylindrical elastic coupling device for shafts and beams according to this embodiment, for example, the mounting strength of the stopper member can be increased by employing a mounting bolt with a long shaft portion, or multiple types of mounting bolts with different shaft lengths can be screwed in. When a screw hole is provided that penetrates the inner shaft member radially, the screw hole protection member may be attached to both ends of the screw hole, or it may be inserted along the entire length.

[0044] The seventeenth aspect is a method for manufacturing a cylindrical elastic coupling device for an axial beam as described in any one of the first to sixteenth aspects, The pretreatment step for the inner shaft member includes a vulcanization bonding step in which the main rubber elastic body is vulcanized and bonded to the pretreated inner shaft member. In the vulcanization bonding process, the screw hole of the inner shaft member is covered and protected by the screw hole protection member. It is.

[0045] According to the manufacturing method of the cylindrical elastic coupling device for axial beams according to this embodiment, the screw holes are sealed by the screw hole protection member even when the main body rubber elastic body is vulcanized and bonded, thereby preventing the forming material of the main body rubber elastic body from entering the screw holes and preventing rubber from adhering to the inner surface of the screw holes.

[0046] The eighteenth aspect is a method for manufacturing a cylindrical elastic coupling device for an axial beam as described in any one of the first to seventeenth aspects, The pretreatment applied to the inner shaft member in the aforementioned inner shaft member pretreatment step is at least one of the following: a cleaning treatment with a cleaning solution; a surface roughening treatment by blasting; a chemical conversion coating treatment that forms a zinc phosphate film on the surface; and an adhesive layer formation treatment that forms an adhesive layer on the surface. It is.

[0047] According to the manufacturing method of a cylindrical elastic coupling device for shafts and beams according to this embodiment, for example, if the pretreatment is a cleaning treatment, the inner surface of the screw hole can be prevented from rusting by preventing the cleaning liquid from entering the screw hole with a screw hole protection member. Also, for example, if the pretreatment is a surface roughening treatment, damage to the screw threads caused by small balls or the like striking the inner surface of the screw hole can be prevented, and stable screwing of the mounting bolt into the screw hole can be achieved. Also, for example, if the pretreatment is a chemical conversion coating treatment, screwing defects of the mounting bolt into the screw hole can be prevented by preventing the formation of a chemical conversion coating on the inner surface of the screw hole. Also, for example, if the pretreatment is an adhesive layer formation treatment, screwing defects of the mounting bolt into the screw hole can be prevented by preventing the formation of an adhesive layer on the inner surface of the screw hole. [Effects of the Invention]

[0048] According to the present invention, the mounting accuracy of the stopper member can be improved by protecting the screw hole of the inner shaft member to which the stopper member is attached during the pre-treatment of the inner shaft member. [Brief explanation of the drawing]

[0049] [Figure 1]Perspective view of a rubber bushing for a shaft beam according to the first embodiment of the present invention [Figure 2] Front view of the rubber bushing for the shaft shown in Figure 1. [Figure 3] Figure 1 shows a bottom view of the rubber bushing for the shaft. [Figure 4] Figure 2, section IV-IV [Figure 5] Figure 1 is a cross-sectional view of a rubber bushing for an axial beam, corresponding to the VV section in Figure 6. [Figure 6] Figure 2, section view between VI and VI [Figure 7] Front view of the inner shaft member constituting the rubber bushing for the shaft beam shown in Figure 1. [Figure 8] Bottom view of the inner shaft member shown in Figure 7 [Figure 9] Figure 7, section IX-IX [Figure 10] Cross-sectional view of XX in Figure 7 [Figure 11] Figure 9 shows a magnified cross-sectional view of the opening of the screw hole. [Figure 12] Figure 1 is a flowchart showing the manufacturing process of rubber bushings for shafts and beams. [Figure 13] Front view of the inner shaft member with protective bolts screwed into it, as shown in Figure 7. [Figure 14] Bottom view of the inner shaft member into which the protective bolt is screwed, as shown in Figure 13. [Figure 15] Figure 13: XV-XV cross-section [Figure 16] Figure 13 shows the cross-sectional view between XVI and XVI. [Figure 17] Figure 15 shows a magnified cross-sectional view of the opening of the screw hole. [Figure 18] The table shows the results of a watertightness test conducted on the inner shaft member into which the protective bolt shown in Figure 13 is screwed. [Figure 19] Cross-sectional view showing a rubber bushing for a shaft beam according to another embodiment of the present invention. [Figure 20] Enlarged cross-sectional view showing a portion of the inner shaft member constituting a rubber bushing for a shaft beam according to yet another embodiment of the present invention, with a protective bolt attached. [Modes for carrying out the invention]

[0050] Embodiments of the present invention will be described below with reference to the drawings.

[0051] Figures 1 to 6 show a rubber bushing 10 for a shaft beam as a cylindrical elastic coupling device for a shaft beam, representing a first embodiment of the present invention. The rubber bushing 10 for a shaft beam has a structure in which an inner shaft member 12 and front and rear outer splits 14a and 14b, which are arranged opposite each other on the outer circumference of the inner shaft member and the outer splits 14a and 14b, are elastically connected to each other by a main rubber elastic body 16. In the following description, as a general rule, the vertical direction refers to the vertical direction on the plane of Figure 2, the front and rear direction refers to the vertical direction on the plane of Figure 3, and the left and right direction refers to the left and right direction on the plane of Figure 2.

[0052] The inner shaft member 12 is rod-shaped and extends linearly in the left-right direction as a whole, and is a highly rigid member made of a metal such as iron or an aluminum alloy. As shown in Figures 7 to 10, the inner shaft member 12 has a structure in which a cylindrical central shaft body 18, a pair of flange-shaped inner flange portions 20, 20 that protrude outward at both axial ends of the central shaft body 18, and a pair of mounting portions 22, 22 that protrude further axially outward than the inner flange portions 20, 20 are integrally formed.

[0053] The central shaft body 18 has a substantially constant circular cross-section and extends linearly in the left-right direction. The central shaft body 18 of the inner shaft member 12 has a screw hole 24 that extends radially. The screw hole 24 has a substantially circular cross-section and extends linearly in the front-rear direction, and screw threads are formed on its inner circumferential surface. The screw hole 24 is a bottomed hole that opens to the front surface of the central shaft body 18 and is partially provided in the front-rear radial direction of the central shaft body 18. As shown in Figure 11, a tapered surface 26 is provided at the opening of the screw hole 24, with the diameter increasing toward the outer circumferential surface of the central shaft body 18. In this embodiment, the inclination angle of the tapered surface 26 with respect to the central axis of the screw hole 24 is substantially constant, and it has a shape that extends linearly in the radial cross-section of the screw hole 24 shown in Figure 11, but the inclination angle may vary. The inclination angle θ of the tapered surface 26 with respect to a plane perpendicular to the central axis of the screw hole 24 (see Figure 11) is preferably set within the range of 20° to 60°, and in this embodiment it is set to 30°.

[0054] The inner flange portions 20, 20 are annular plate-shaped, with the axial outer surface widening in a direction approximately perpendicular to the axis, and the inner circumference portion of the axial inner surface being an inclined surface, with the inner circumference portion gradually becoming thinner towards the outer circumference, and the outer circumference portion widening to a substantially constant thickness.

[0055] As shown in Figure 1, the mounting portion 22 has a roughly polygonal prism shape and has bolt holes 28 that pass through it linearly in the vertical direction. The mounting portion 22 is then fixed to the trolley, which will be described later, by fastening bolts (not shown) that are inserted through the bolt holes 28.

[0056] Furthermore, the shape of the inner shaft member 12 is not limited by the specific description of the embodiment, and the specific shapes of each part constituting the inner shaft member 12 (the central shaft body 18, inner flange portion 20, mounting portion 22, and bolt hole 28 in this embodiment) are not particularly limited.

[0057] As shown in Figures 4 and 6, a stopper member 30 is attached to the central shaft body 18 of the inner shaft member 12. The stopper member 30 is substantially rectangular in the front view shown in Figure 2. A bolt insertion hole 32 is formed in the stopper member 30, penetrating in the front-to-back direction. The front portion of the bolt insertion hole 32 is larger in diameter, thereby forming a stepped surface 34 around its entire circumference. No threads are formed on the inner circumferential surface of the bolt insertion hole 32. The stopper member 30 comprises a rigid base portion 36 fixed to the inner shaft member 12 and an elastic portion 38 provided on the tip side opposite to the inner shaft member 12 relative to the base portion 36.

[0058] The base portion 36 is roughly rectangular in shape and is a highly rigid member made of metal such as iron or aluminum alloy. The tip surface of the base portion 36 that overlaps with the elastic portion 38 is a curved surface that curves in the circumferential direction of the inner shaft member 12. Furthermore, the base end surface of the base portion 36 that overlaps with the central shaft body 18 of the inner shaft member 12 is an inner-side corresponding surface 40 which is a curved surface corresponding to the outer circumferential surface of the inner shaft member 12. The stepped surface 34 of the bolt insertion hole 32 is formed in the base portion 36.

[0059] The elastic section 38 has a laminated structure in which a rigid intermediate restraining member 46 is positioned between a tip elastic body 42 and an intermediate elastic body 44, both of which are made of elastic material. The entire elastic section 38 is made of a material that is harder than the main rubber elastic body 16. In particular, both the tip elastic body 42 and the intermediate elastic body 44 are made of an elastic material that is harder than the main rubber elastic body 16.

[0060] The tip elastic body 42 is a thin rubber layer that is superimposed on and fixed to the tip surface of the intermediate restraint member 46, and constitutes the tip surface of the stopper member 30. The tip elastic body 42 is made of a rubber material that is harder than the main rubber elastic body 16. The tip elastic body 42 may also be made of a resin elastomer that exhibits rubber-like elasticity.

[0061] The intermediate elastic body 44 is a thin rubber layer that is superimposed on and fixed to the tip surface of the base portion 36. The intermediate elastic body 44 is made of a rubber material that is harder than the main rubber elastic body 16. In this embodiment, the tip elastic body 42 and the intermediate elastic body 44 are made of the same elastic material, and manufacturing is facilitated by making it easier to mold the tip elastic body 42 and the intermediate elastic body 44 simultaneously. The intermediate elastic body 44 may be made of a resin elastomer that exhibits rubber-like elasticity.

[0062] The intermediate restraint member 46 is plate-shaped and curved in correspondence with the tip surface of the base 36, and is positioned at a distance from the tip side of the base 36. An intermediate elastic body 44 is positioned between the opposing surfaces of the base 36 and the intermediate restraint member 46, and the base 36 and the intermediate restraint member 46 are interconnected by the intermediate elastic body 44. The tip surface of the intermediate restraint member 46 is almost entirely covered by a tip elastic body 42.

[0063] The stopper member 30, having the structure described above, is fixed to the inner shaft member 12 by a mounting bolt 50. The mounting bolt 50 comprises a shaft portion 52 with threads formed on its outer circumference and a head portion 54 integrally formed on the front side of the shaft portion 52. The shaft portion 52 is designed to be screwable into the threaded hole 24 of the inner shaft member 12. The head portion 54 is cylindrical in shape with a larger diameter than the shaft portion 52, and its outer diameter is smaller than the inner diameter of the front portion of the bolt insertion hole 32, and larger than the inner dimension of the stepped surface 34. The mounting bolt 50 in this embodiment has a hexagonal cross-section recess formed so that the head portion 54 opens to the front, and is a socket head cap bolt that can be rotated by inserting a hexagonal wrench into the recess. Note that the mounting bolt 50 is not limited to a socket head cap bolt, and may be a hexagonal bolt with a hexagonal columnar head, etc.

[0064] The shaft portion 52 of the mounting bolt 50 is inserted from the front into the bolt insertion hole 32 of the stopper member 30 and screwed into the threaded hole 24 of the inner shaft member 12. The head 54 of the mounting bolt 50 is housed in the large diameter portion of the bolt insertion hole 32 of the stopper member 30 and is superimposed on the stepped surface 34 provided in the bolt insertion hole 32. As a result, the stopper member 30 is bolted to the inner shaft member 12 with its inner side corresponding surface 40 superimposed on the outer circumferential surface of the central shaft body 18 of the inner shaft member 12, and protrudes forward from the central shaft body 18 of the inner shaft member 12.

[0065] In this embodiment, the outer circumferential surface of the central shaft body 18 in the inner shaft member 12 is a cylindrical surface that curves in the circumferential direction, and the overlapping surface (base end surface) of the base portion 36 of the stopper member 30 with the central shaft body 18 is an inner-side corresponding surface 40 that curves in the circumferential direction with a shape corresponding to the outer circumferential surface of the central shaft body 18. The outer circumferential surface of the central shaft body 18 on the inner shaft member 12 side and the inner-side corresponding surface 40 on the stopper member 30 side are superimposed on each other, thereby forming a rotation limiting mechanism that limits the relative amount of rotation of the stopper member 30 around the mounting bolt 50 with respect to the inner shaft member 12. This rotation limiting mechanism fixes the stopper member 30 to the inner shaft member 12 in an appropriate orientation around the central axis of the mounting bolt 50.

[0066] It is desirable that the stopper member 30 be positioned so that the orientation of the mounting bolt 50 around the central axis is appropriate with respect to the inner shaft member 12 before the mounting bolt 50 is screwed in. For example, by pressing the inner corresponding surface 40 of the stopper member 30 against the central shaft body 18 of the inner shaft member 12 in the appropriate orientation while tightening the mounting bolt 50, the stopper member 30 is prevented from rotating integrally with the mounting bolt 50, and the mounting bolt 50 can be easily screwed into the screw hole 24.

[0067] Outer segments 14a and 14b are arranged on both the front and rear sides of the inner shaft member 12 to which the stopper member 30 is attached. Both outer segments 14a and 14b have a curved plate shape that extends in the circumferential direction for a length of less than half a circumference. Outer flanges 56, 56 that protrude outward are integrally formed at both axial ends of the outer segments 14a and 14b. The outer flanges 56 protrude outward while inclined axially outward and are positioned opposite the inner flange 20 at a predetermined distance axially inward. In this embodiment, one outer segment 14a has a larger circumferential length dimension than the other outer segment 14b.

[0068] One of the outer segments 14a has a window portion 58 formed therein. The window portion 58 penetrates the central part of the outer segment 14a in the circumferential and axial directions in the front-to-back direction and has a roughly square opening shape. In the axial beam rubber bush 10, the window portion 58 is larger than the front end surface of the stopper member 30 in the front-to-back projection, and is sized so that the entire front end surface of the stopper member 30 can be exposed through the window portion 58.

[0069] The outer segments 14a and 14b are positioned separately on the outer circumference of the central shaft body 18 of the inner shaft member 12, and the inner shaft member 12 and the outer segments 14a and 14b are elastically connected to each other by the main rubber elastic body 16. The outer segments 14a and 14b are positioned radially opposite each other with the central shaft body 18 in between, and the circumferential ends of the outer segments 14a and 14b are separated from each other.

[0070] The main rubber elastic body 16 has a generally thick, substantially cylindrical shape, and rubber flanges 60, 60 projecting outward are integrally formed at both axial ends. The inner circumferential surface of the cylindrical central axial portion of the main rubber elastic body 16 is vulcanized and bonded to the outer circumferential surface of the central shaft body 18 of the inner shaft member 12, while the outer circumferential surface is vulcanized and bonded to the inner circumferential surfaces of the outer segmented bodies 14a, 14b. Each rubber flange 60 is positioned between the opposing surfaces of the inner flange 20 of the inner shaft member 12 and the outer flanges 56, 56 of the outer segmented bodies 14a, 14b, and is vulcanized and bonded to the inner flange 20 and outer flanges 56, 56. In this embodiment, the main rubber elastic body 16 is formed as an integrally vulcanized molded product comprising the inner shaft member 12 and the outer segmented bodies 14a, 14b.

[0071] A pocket portion 62 is formed in the main rubber elastic body 16. The pocket portion 62 is concave, opening onto the outer circumferential surface of the main rubber elastic body 16, and is formed in the axial central portion of the main rubber elastic body 16. In this embodiment, the pocket portion 62 is provided in the portion where one of the outer segmented bodies 14a is located, and is open to the outer circumferential surface through the window portion 58 of the outer segmented body 14a.

[0072] The stopper member 30 attached to the inner shaft member 12 protrudes into the pocket portion 62. The stopper member 30 is positioned in the central part of the pocket portion 62, and at least the elastic portion 38 is separated from the inner wall surface of the pocket portion 62. The protruding tip surface of the stopper member 30 located inside the pocket portion 62 is exposed to the outside through the opening and window portion 58 of the pocket portion 62.

[0073] As shown in Figures 3, 5, and 6, the main rubber elastic body 16 is exposed between the outer segments 14a and 14b in the circumferential direction, and a free surface not constrained by fittings or the like is provided in the exposed portion. An annular groove 64 is opened on the outer circumferential surface of the main rubber elastic body 16 that is exposed between the outer segments 14a and 14b in the circumferential direction. The annular groove 64 is composed of a transverse groove extending axially along the circumferential ends of the outer segments 14a and 14b, and a circumferential groove extending circumferentially along the base end of the rubber flange portion 60 of the main rubber elastic body 16, and extends continuously in a substantially rectangular annular shape in the exposed portion of the main rubber elastic body 16. As shown in Figure 6, the region of the main rubber elastic body 16 enclosed by the annular groove 64 is a protruding portion 66 that projects outward.

[0074] The axle beam rubber bush 10, with this structure, is attached to the bogie of a railway vehicle, as shown in, for example, Japanese Patent No. 7189809, and elastically connects the bogie frame to which the inner axle member 12 is attached, and the axle beam, which has a housing portion to which the outer split parts 14a and 14b are attached. In this embodiment, the bogie of the railway vehicle has a single-brake structure in which the rotation of the wheel is braked by pressing a brake shoe against the outer circumferential surface of the wheel from either the front or rear using hydraulic pressure or the like. Therefore, when the railway vehicle is braked, a load in the front-rear direction is applied to the axle beam rubber bush 10, and the relative displacement amount in the front-rear direction between the inner axle member 12 and the outer split parts 14a and 14b is limited by the contact between the stopper member 30 and the housing on the bogie side.

[0075] Incidentally, such a rubber bushing 10 for a shaft beam is manufactured, for example, by a manufacturing method that includes the steps shown in Figure 12. The manufacturing method for the rubber bushing 10 for a shaft beam will be described below.

[0076] First, in step (hereinafter referred to as S) 1, an inner shaft member preparation step is performed to prepare the inner shaft member 12. The inner shaft member 12 prepared in this step is provided with a screw hole 24 that opens on the outer circumferential surface of the central shaft body 18.

[0077] Next, in S2, a screw hole protection step is performed to protect the screw hole 24 by inserting a protective bolt 90, which serves as a screw hole protection member, into the screw hole 24. As shown in Figures 13 to 17, the protective bolt 90 comprises a shaft portion 92 that is inserted into the screw hole 24 and a head portion 94 that has a larger diameter than the shaft portion 92. In this embodiment, the protective bolt 90 is a separate component from the mounting bolt 50. The shaft portion 92 in this embodiment is a male screw-shaped threaded shaft portion with threads formed on its outer circumference, and is designed to be screwed into the screw hole 24. The head portion 94 in this embodiment is disc-shaped and has a screw-driver structure such as a hexagonal socket, similar to that of the mounting bolt 50. Then, in S2, the shaft portion 92 of the protective bolt 90 is screwed into the screw hole 24 of the inner shaft member 12 prepared in S1, thereby closing the screw hole 24 with the shaft portion 92 of the protective bolt 90.

[0078] As shown in Figures 15 to 17, the protective bolt 90 is attached to the screw hole 24 with its head 94 separated from the outer circumferential surface of the central shaft body 18 of the inner shaft member 12. In other words, the protective bolt 90 protrudes from the screw hole 24 toward the tapered surface 26 towards the outer circumference of the inner shaft member 12 (central shaft body 18). In this embodiment, the length of the shaft portion 92 of the protective bolt 90 is longer than the length of the shaft portion 52 of the mounting bolt 50, so that even when the shaft portion 52 is screwed all the way into the screw hole 24, the head 94 of the protective bolt 90 remains separated from the outer circumferential surface of the central shaft body 18. However, for example, the shaft portion 92 of the protective bolt 90 may be screwed only partway into the screw hole 24 so that the head 94 remains separated from the outer circumferential surface of the central shaft body 18. It is desirable that the shaft portion 92 of the protective bolt 90 has four or more threads screwed into the screw hole 24. Furthermore, it is desirable that the shaft portion 92 of the protective bolt 90 be screwed into the threaded hole 24 over a length of no more than 10 times the nominal diameter of the protective bolt 90.

[0079] In the projection along the central axis of the screw hole 24, it is desirable that the head 94 overlaps with the tapered surface 26 in at least a portion of it. In this embodiment, as shown in Figure 17, the outer diameter of the head 94 of the protective bolt 90 is larger than the maximum diameter of the tapered surface 26 provided at the opening of the screw hole 24, so that in the projection along the central axis of the screw hole 24, the entire tapered surface 26 overlaps with the head 94 of the protective bolt 90.

[0080] Next, in S3, an inner shaft member pretreatment process is performed on the inner shaft member 12 to pre-treat it for vulcanization bonding of the main rubber elastic body 16. Examples of pretreatment applied to the inner shaft member 12 in S3 include cleaning with a cleaning solution, roughening by blasting, chemical conversion coating treatment to form a chemical conversion film (zinc phosphate film) on the surface, and adhesive layer formation treatment to form an adhesive layer on the surface by applying adhesive. Specifically, in S3, after cleaning the inner shaft member 12 with a cleaning solution, the surface roughness of the inner shaft member 12 is increased by blasting, a chemical conversion film is formed on the roughened surface of the inner shaft member 12, and then a liquid adhesive for bonding the main rubber elastic body 16 is sprayed onto a part of the surface of the inner shaft member 12 covered with the chemical conversion film using a spray gun or the like to form an adhesive layer. However, it is not necessary to perform all of the example pretreatments in S3; at least one is sufficient.

[0081] In this embodiment, upon completion of the inner shaft member pretreatment process, a coating layer 96 consisting of a chemical conversion coating and adhesive is fixed to the outer circumferential surface of the central shaft body 18, which is the fixing surface of the main rubber elastic body 16 of the inner shaft member 12, the axial inner surface of the inner flange portions 20, 20, the tapered surface 26, and the portion of the protective bolt 90 protruding from the screw hole 24. Since the adhesive is sprayed only in the axial middle portion of the inner shaft member 12 to which the main rubber elastic body 16 is fixed, the coating layer 96 including the adhesive layer is provided only in the axial middle portion of the inner shaft member 12. However, the chemical conversion coating for rust prevention is formed on the entire surface of the inner shaft member 12, excluding the inner surface of the screw hole 24, by, for example, immersing the inner shaft member 12 in a treatment solution (zinc phosphate) in a water tank. Note that the thickness of the coating layer 96 is emphasized in the figure for ease of understanding.

[0082] During the pretreatment in S3, the screw hole 24 is sealed and protected by the protective bolt 90 that was screwed in in S2. This makes it difficult for liquids such as the cleaning solution used in the cleaning process, the chemical conversion coating material used in the chemical conversion coating process, and the adhesive used in the adhesive layer formation process to penetrate the screw hole 24. This prevents rust formation due to residual cleaning solution and improper screwing of the mounting bolt 50 due to the hardening of chemical conversion coating material or adhesive adhering to the inner surface of the screw hole 24, by installing the protective bolt 90 in the screw hole 24. In addition, because the protective bolt 90 is installed in the screw hole 24, shots such as small balls used in the blasting process of the roughening treatment do not strike the inner surface of the screw hole 24, thus preventing damage to the inner surface of the screw hole 24 from impact by the shots.

[0083] In this embodiment, since the protective bolt 90 protrudes from the screw hole 24, during the roughening treatment, the blast shots are less likely to hit the tapered surface 26 provided at the opening of the screw hole 24, making it difficult for the roughening treatment to reach it. As a result, the surface roughness of the central shaft body 18, which is the fixing surface of the main rubber elastic body 16, is greater than that of the tapered surface 26. Consequently, the rate of increase in surface area per unit area due to the roughening treatment is smaller on the tapered surface 26 than on the outer circumferential surface of the central shaft body 18, and during the chemical conversion coating treatment after the roughening treatment, the adhesion strength of the chemical conversion coating to the tapered surface 26 is smaller than the adhesion strength to the central shaft body 18. In short, the chemical conversion coating is relatively easy to peel off on the tapered surface 26.

[0084] After the pre-treatment process for the inner shaft member in S3 is completed, in S4, a screw hole protection release process is performed to remove the protective bolt 90 from the screw hole 24. The protective bolt 90, which has been pre-treated together with the inner shaft member 12 while installed in the screw hole 24, is covered together with the inner shaft member 12 by a coating layer 96 of chemical conversion film and adhesive. Therefore, when removing the protective bolt 90 from the screw hole 24, peeling of the coating layer 96 occurs near the boundary between the protective bolt 90 and the inner shaft member 12, resulting in the rupture of the coating layer 96.

[0085] In this embodiment, peeling of the coating layer 96 is less likely to occur on the outer circumferential surface of the central shaft body 18, which is the fixing surface of the main rubber elastic body 16. Specifically, a tapered surface 26 is provided at the opening of the screw hole 24, and the surface of the inner shaft member 12 adjacent to the shaft portion 92 of the protective bolt 90 is the tapered surface 26, rather than the outer circumferential surface of the central shaft body 18. As a result, when the protective bolt 90 is rotated and removed from the screw hole 24, the rupture of the coating layer 96 is more likely to occur on the tapered surface 26, and because the coating layer 96 ruptures on the tapered surface 26, peeling of the coating layer 96 is less likely to occur on the outer circumferential surface of the central shaft body 18. In this way, damage to the coating layer 96 covering the outer circumferential surface of the central shaft body 18 is prevented, and stable fixing of the main rubber elastic body 16 is achieved in S5, which will be described later.

[0086] In this embodiment, as described above, the protective bolt 90 protruding from the screw hole 24 inhibits the roughening of the tapered surface 26, resulting in the adhesion strength of the coating layer 96 to the tapered surface 26 being lower than the adhesion strength of the coating layer 96 to the central shaft body 18, making the tapered surface 26 more prone to breakage due to peeling of the coating layer 96. Moreover, the protective bolt 90 protruding from the screw hole 24 inhibits the adhesion of the adhesive to the tapered surface 26, making the coating layer 96 covering the tapered surface 26 more uneven than the portion covering the outer circumferential surface of the central shaft body 18, thus making the coating layer 96 more prone to breakage on the tapered surface 26.

[0087] In addition, in the projection of the screw hole 24 in the direction of the central axis, the head 94 of the protective bolt 90 overlaps with the tapered surface 26, making it difficult for pre-treatments such as roughening and the formation of the coating layer 96 to reach the tapered surface 26, thus making fracture of the coating layer 96 on the tapered surface 26 more likely.

[0088] The inclination angle θ of the tapered surface 26 with respect to the plane extending perpendicular to the central axis direction of the screw hole 24 is set to a range of 20° to 60°. This makes it difficult for cleaning fluid to remain on the tapered surface 26 after cleaning, for example. Also, for example, during the roughening process, the impact of the shots on the tapered surface 26 is moderately suppressed by the protective bolts 90, reducing the adhesion strength of the coating layer 96 to the tapered surface 26, which makes it easier for the coating layer 96 to break on the tapered surface 26. However, the tapered surface 26 is a part that does not contribute to the adhesion of the main rubber elastic body 16, so the location on the tapered surface 26 where the coating layer 96 breaks is not a performance issue.

[0089] In S4, the pre-treated inner shaft member 12, from which the protective bolts 90 have been removed, is set in the cavity of the vulcanization mold for the main rubber elastic body 16 in S5. The separately prepared outer segments 14a and 14b are also set in the cavity of the vulcanization mold for the main rubber elastic body 16. Then, in S5, the main rubber elastic body 16 is vulcanized and molded as an integrally formed product comprising the inner shaft member 12 and the outer segments 14a and 14b. This completes the vulcanization bonding process in S5, in which the main rubber elastic body 16 is vulcanized and bonded to the inner shaft member 12 and the outer segments 14a and 14b. It is desirable that the outer segments 14a and 14b used in S5 undergo the same pre-treatment as the inner shaft member 12 in S3 (cleaning, roughening, formation of a chemical conversion film, formation of an adhesive layer, etc.).

[0090] The vulcanization bonding process in S5 can also be performed before the screw hole protection release process in S4. In short, the inner shaft member 12 may be set in the molding die for the main rubber elastic body 16 with the protective bolt 90 attached to the screw hole 24, and after the main rubber elastic body 16 has been vulcanized, the protective bolt 90 may be removed from the screw hole 24. This also prevents the forming material of the main rubber elastic body 16 from entering the screw hole 24 with the protective bolt 90.

[0091] Next, in S6, a stopper mounting process is performed in which the stopper member 30 is attached to the inner shaft member 12. Specifically, the pre-prepared stopper member 30 is inserted into the pocket portion 62 of the main rubber elastic body 16 through the window portion 58 of the outer split body 14a, and the stopper member 30 is superimposed on the outer circumferential surface of the central shaft body 18 of the inner shaft member 12. Then, the mounting bolt 50 is inserted through the bolt insertion hole 32 of the stopper member 30 and screwed into the screw hole 24 from which the protective bolt 90 has been removed. In this way, the stopper member 30 is fixed to the central shaft body 18 of the inner shaft member 12 with the mounting bolt 50. Upon completion of S6, a shaft beam rubber bush 10 with a structure according to this embodiment can be obtained.

[0092] According to the manufacturing method of the shaft beam rubber bush 10 according to this embodiment, the manufacturing method includes a screw hole protection step, which is performed before the inner shaft member pretreatment step, which is a pretreatment step for vulcanizing and bonding the main rubber elastic body 16 to the inner shaft member 12, by attaching a protective bolt 90 to the screw hole 24 of the inner shaft member 12 to protect the screw hole 24. This prevents the residue of cleaning solution on the screw hole 24, the adhesion of chemical conversion films, and damage to the screw threads during roughening treatment.

[0093] Furthermore, when removing the protective bolt 90 from the screw hole 24, the coating layer 96 is more likely to break on the tapered surface 26 provided on the periphery of the opening of the screw hole 24, making it difficult for the peeling of the coating layer 96 to extend to the surface of the central shaft body 18 of the inner shaft member 12. Therefore, stable fixation of the main body rubber elastic body 16 to the central shaft body 18 is achieved.

[0094] Furthermore, the fact that liquid ingress into the screw hole 24 of the inner shaft member 12 is prevented by attaching a protective bolt 90 to the screw hole 24 has also been confirmed by a water-stopping experiment, the results of which are shown in Figure 18. In the water-stopping experiment, water was applied to the screw hole 24 of the inner shaft member 12 while the protective bolt 90 was screwed into the screw hole 24, and then the protective bolt 90 was removed to check the state of water ingress into the screw hole 24. More specifically, first, the protective bolt 90 was screwed into the screw hole 24 to a predetermined number of threads, and the inner shaft member 12 was held so that the opening direction of the screw hole 24 (forward in Figure 15) was facing vertically upward. Then, a state in which approximately 4 liters of water per minute was applied to the formed portion of the screw hole 24 from vertically upward (forward in Figure 15) for 1 minute was maintained. Afterward, the water adhering to the inner shaft member 12 and the protective bolt 90 was wiped off to reduce it to a level that would not enter the screw hole 24. Then, with the opening direction of the screw hole 24 (forward in Figure 15) facing vertically downward, the protective bolt 90 was removed from the screw hole 24 to check for water ingress. The purpose of wiping off the water is to prevent water adhering to the surface of the inner shaft member 12 and the protective bolt 90 from entering the screw hole 24 or from accidentally adhering to the judgment area of ​​the protective bolt 90 when removing the protective bolt 90 from the screw hole 24 or after removal. It is not necessary to completely wipe off the water adhering to the surface of the inner shaft member 12 and the protective bolt 90.

[0095] In the above water-stopping experiment, the presence or absence of water ingress was confirmed for each case where the protective bolt 90 screwed into the screw hole 24 had 2 to 6 threads and 12 threads. When counting the number of threads on the protective bolt 90, they were numbered 1st, 2nd, 3rd, etc., starting from the tip of the shaft opposite the head. The screw hole 24 of the inner shaft member 12 used in the above water-stopping experiment is a bottomed hole as shown in the first embodiment. The protective bolt 90 used in the above water-stopping experiment is an M6 bolt with a nominal diameter of 6 mm.

[0096] In the above water-stopping experiment, the presence or absence of water ingress into the screw hole 24 was determined by whether or not water was adhering to the valley of the thread of the protective bolt 90 into which the top of the thread of the second screw hole 24 from the opening of the screw hole 24 fits. In short, when the protective bolt 90 is screwed into the screw hole 24 by n threads (where n is a natural number of 3 or more), in other words, when the thread of the protective bolt 90 screwed into the thread closest to the opening of the screw hole 24 is the nth thread (see Figure 17), the presence or absence of water ingress into the screw hole 24 was determined by whether or not water was adhering to the valley between the n-1th and n-2nd threads of the protective bolt 90 (the water-stopping determination area in Figure 17). By adopting such a determination method, it is possible to confirm the presence or absence of water ingress in the water-stopping determination area where the threads of the protective bolt 90 and the threads of the screw hole 24 are screwed together around the entire circumference, and thus more accurate experimental results can be expected. On the other hand, when the protective bolt 90 is screwed into the screw hole 24 by only two threads, the presence or absence of water ingress into the screw hole 24 was determined based on whether or not water was adhering to the portion from the tip of the protective bolt 90 to the first thread (the thread located at the very tip of the protective bolt 90). Note that although a coating layer 96 is shown in Figure 17, the inner shaft member 12 and protective bolt 90 used in the water-stopping experiment were not covered with the coating layer 96.

[0097] Water ingress into the screw hole 24 is prevented by the engagement of the threads of the protective bolt 90 with the threads of the screw hole 24. However, it is difficult to visually confirm water ingress into the screw hole 24. Therefore, the water ingress into the screw hole 24 is indirectly determined based on the presence or absence of water on the easily visible threaded portion of the protective bolt 90, thereby simplifying the water-stopping determination. Furthermore, if there is no water ingress into the opening of the screw hole 24, water cannot ingress into the bottom of the bottomed screw hole 24. Therefore, the confirmation work for water-stopping determination is simplified by focusing on the presence or absence of water on the threaded portion of the protective bolt 90 that is close to the opening of the screw hole 24.

[0098] According to the experimental results (water-stopping judgment results) in Figure 18, it was confirmed that when the protective bolt 90 is screwed into the screw hole 24 with four or more threads, water ingress can be reliably prevented. On the other hand, it was confirmed that when the protective bolt 90 is screwed into the screw hole 24 with two or three threads, water ingress may occur. This is because if the number of threads on the protective bolt 90 screwed into the screw hole 24 is too small, tilting (looseness) of the protective bolt 90 relative to the screw hole 24 is likely to occur, and this looseness creates a gap between the screw hole 24 and the protective bolt 90, into which water can ingress. In the "Water-Stopping" column of the test results in Figure 18, ○ indicates that there was no water adhesion to the water-stopping judgment part of the protective bolt 90, △ indicates that there was sometimes water adhesion to the water-stopping judgment part of the protective bolt 90 and sometimes not, and × indicates that there was water adhesion to the water-stopping judgment part of the protective bolt 90.

[0099] Although embodiments of the present invention have been described in detail above, the present invention is not limited by its specific description. For example, the screw holes are not necessarily limited to one, but may be multiple. In this case, it is desirable that a screw hole protection member be attached to each of the multiple screw holes during the screw hole protection process.

[0100] As shown in Figure 19, the shaft beam rubber bush 100, which is a cylindrical elastic coupling device for shaft beams, may have a screw hole 102 that penetrates the central shaft body 18 of the inner shaft member 12 and is formed along the entire radial length of the central shaft body 18. In this case, during the screw hole protection process, a screw hole protection member may be inserted along the entire length of the screw hole, or screw hole protection members may be attached to the openings on both sides of the screw hole, or a screw hole protection member may be provided only at the opening on the stopper member side to protect the threaded portion of the mounting bolt in the screw hole.

[0101] Furthermore, for example, the screw hole may be formed partway through the central shaft body of the inner shaft member, and a pilot hole without threads may be formed extending from the bottom of the screw hole toward the opposite side of the opening. The pilot hole may be formed partway through the central shaft body of the inner shaft member, or it may penetrate the central shaft body so as to open on the opposite side of the opening of the screw hole.

[0102] The screw hole protection member can also be made of a protective bolt 110 consisting only of a shaft portion 92 without a head, as shown in Figure 20. In such a protective bolt 110, the outer diameter is maximized at the shaft portion 92 that is screwed into the screw hole 24, and since there is no portion that covers the surface of the inner shaft member 12 (central shaft body 18) like the head portion 94 in the first embodiment, it becomes easier to uniformly apply pre-treatment such as roughening treatment to the surface of the inner shaft member 12. Furthermore, the screw hole protection member is not limited to a male screw structure that screws into the screw hole, but may also be a structure that has a shaft portion formed of an elastic body or a hard synthetic resin that is fitted into the screw hole. When a protective bolt 90 with a head portion 94 as in the first embodiment is used, it is desirable that the head portion 94 is separated from the surface of the inner shaft member 12 (central shaft body 18), but it may also be superimposed on the surface of the inner shaft member 12 (central shaft body 18) in a contact state.

[0103] The screw hole protection member can also be made of a mounting bolt. In short, the screw hole protection member for protecting the screw hole and the mounting bolt for fixing the stopper member to the inner shaft member may be the same member. In this case, the inner shaft member pre-treatment step (S3 in Figure 12) is performed with the mounting bolt screwed into the screw hole of the inner shaft member in the screw hole protection step (S2 in Figure 12), then the mounting bolt is removed in the screw hole protection release step (S4 in Figure 12), and the removed mounting bolt is inserted into the bolt insertion hole of the stopper member and screwed into the screw hole again in the stopper mounting step (S6 in Figure 12), thereby obtaining a cylindrical elastic coupling device for shafts equipped with a stopper member.

[0104] The means of adhering the adhesive to the surface of the inner shaft member are not necessarily limited to the spraying method exemplified in the above embodiment. The adhesive may also be applied to the surface of the inner shaft member by brushing or the like, or by immersing the inner shaft member in liquid adhesive in a water tank.

[0105] The stopper member is not limited to the laminated structure shown in the first embodiment; for example, a simple structure in which the surface of a metal material is covered with a cushioning rubber layer can also be adopted. Furthermore, the stopper member may be a single-layer structure formed entirely of an elastic material or a hard resin. [Explanation of symbols]

[0106] 10. Rubber bushing for axial beam (First embodiment: Cylindrical elastic coupling device for axial beam) 12 Inner shaft member 14a Outer division 14b Outer division 16 Main body rubber elastic body 18. Main shaft body 20 Inner flange 22 Mounting part 24 screw holes 26 Tapered surface 28 bolt holes 30 Stopper component 32 bolt insertion holes 34 Step surface 36 Base 38 Elastic part 40 Inner side corresponding surface 42. Tip elastic body 44 Intermediate elastic body 46 Intermediate restraint member 50 Mounting bolts 52 Shaft section 54 Head 56 Outer rim 58 Window section 60 Rubber flange 62 Pocket section 64 Annular groove 66 Protrusion 90 Protective bolt (screw hole protection component) 92 Shaft (threaded shaft) 94 Head 96 Covering layer 100 Rubber bushing for axial beam (another embodiment: cylindrical elastic coupling device for axial beam) 102 screw holes 110 Protective bolt (or another embodiment: screw hole protective member)

Claims

1. A pair of outer segments are arranged on the outer circumference of the inner shaft member, facing each other in a direction perpendicular to the axis, and these inner shaft member and the pair of outer segments are elastically connected to each other by the main rubber elastic body. A method for manufacturing a cylindrical elastic coupling device for an axle beam, wherein the inner axle member is attached to the bogie frame of a railway vehicle, and the pair of outer parts are attached to a cylindrical housing portion provided at one end of the axle beam, thereby elastically connecting the bogie frame and the axle beam, A screw hole protection step is performed in which a screw hole opening on the outer surface of the inner shaft member is covered and protected with a screw hole protection member. The screw hole protection process includes an inner shaft member pretreatment process for fixing the main body rubber elastic body to the inner shaft member, which has its screw hole protected by the screw hole protection member, After the completion of the pre-treatment step for the inner shaft member, a screw hole protection release step is performed, in which the screw hole protection member is removed from the screw hole of the inner shaft member. A stopper mounting step involves attaching a stopper member to the outer circumferential surface of the inner shaft member by screwing a mounting bolt into the screw hole that was opened in the screw hole protection release step, thereby limiting the relative displacement between the inner shaft member and the set of outer parts. including, The opening of the screw hole is provided with a tapered surface that widens toward the outer circumferential surface of the inner shaft member. In the screw hole protection step, a screw hole protection member is used, which comprises a shaft portion inserted into the screw hole and a head portion with a larger diameter than the shaft portion, and the head portion is mounted away from the opening periphery of the screw hole and facing the tapered surface. The pretreatment step in the inner shaft member pretreatment step includes a step of forming a coating layer that continuously covers the outer circumferential surface of the inner shaft member, the tapered surface, and the surface of the screw hole protection member, In the screw hole protection release step, the removal of the screw hole protection member causes the coating layer to break on the tapered surface. A method for manufacturing a cylindrical elastic coupling device for axial beams.

2. A pair of outer segments are arranged on the outer circumference of the inner shaft member, facing each other in a direction perpendicular to the axis, and these inner shaft member and the pair of outer segments are elastically connected to each other by the main rubber elastic body. A method for manufacturing a cylindrical elastic coupling device for an axle beam, wherein the inner axle member is attached to the bogie frame of a railway vehicle, and the pair of outer parts are attached to a cylindrical housing portion provided at one end of the axle beam, thereby elastically connecting the bogie frame and the axle beam, A screw hole protection step is performed in which a screw hole opening on the outer surface of the inner shaft member is covered and protected with a screw hole protection member. The screw hole protection process includes an inner shaft member pretreatment process for fixing the main body rubber elastic body to the inner shaft member, which has its screw hole protected by the screw hole protection member, After the completion of the pre-treatment step for the inner shaft member, a screw hole protection release step is performed, in which the screw hole protection member is removed from the screw hole of the inner shaft member. A stopper mounting step involves attaching a stopper member to the outer circumferential surface of the inner shaft member by screwing a mounting bolt into the screw hole that was opened in the screw hole protection release step, thereby limiting the relative displacement between the inner shaft member and the set of outer parts. including, The opening of the screw hole is provided with a tapered surface that widens toward the outer circumferential surface of the inner shaft member. In the screw hole protection step, the screw hole protection member is used, in which the outer diameter is maximized at the shaft portion inserted into the screw hole. The pretreatment step in the inner shaft member pretreatment step includes a step of forming a coating layer that continuously covers the outer circumferential surface of the inner shaft member, the tapered surface, and the surface of the screw hole protection member, In the screw hole protection release step, the removal of the screw hole protection member causes the coating layer to break on the tapered surface. A method for manufacturing a cylindrical elastic coupling device for axial beams.

3. A pair of outer segments are arranged on the outer circumference of the inner shaft member, facing each other in a direction perpendicular to the axis, and these inner shaft member and the pair of outer segments are elastically connected to each other by the main rubber elastic body. A method for manufacturing a cylindrical elastic coupling device for an axle beam, wherein the inner axle member is attached to the bogie frame of a railway vehicle, and the pair of outer parts are attached to a cylindrical housing portion provided at one end of the axle beam, thereby elastically connecting the bogie frame and the axle beam, A screw hole protection step is performed in which a screw hole opening on the outer surface of the inner shaft member is covered and protected with a screw hole protection member. The screw hole protection process includes an inner shaft member pretreatment process for fixing the main body rubber elastic body to the inner shaft member, which has its screw hole protected by the screw hole protection member, After the completion of the pre-treatment step for the inner shaft member, a screw hole protection release step is performed, in which the screw hole protection member is removed from the screw hole of the inner shaft member. A stopper mounting step involves attaching a stopper member to the outer circumferential surface of the inner shaft member by screwing a mounting bolt into the screw hole that was opened in the screw hole protection release step, thereby limiting the relative displacement between the inner shaft member and the set of outer parts. including, The opening of the screw hole is provided with a tapered surface that widens toward the outer circumferential surface of the inner shaft member, and the surface roughness of the portion of the outer circumferential surface of the inner shaft member to which the main rubber elastic body is fixed is greater than the surface roughness of at least a portion of the tapered surface. The pretreatment step in the inner shaft member pretreatment step includes a step of forming a coating layer that continuously covers the outer circumferential surface of the inner shaft member, the tapered surface, and the surface of the screw hole protection member, In the screw hole protection release step, the removal of the screw hole protection member causes the coating layer to break on the tapered surface. A method for manufacturing a cylindrical elastic coupling device for axial beams.

4. The screw hole protection member protrudes from the screw hole toward the tapered surface side toward the outer circumference of the inner shaft member. A method for manufacturing a cylindrical elastic coupling device for an axial beam according to claim 2 or 3.

5. The projection of the screw hole protection member in the axial direction of the screw hole overlaps with the tapered surface in at least a portion of it. A method for manufacturing a cylindrical elastic coupling device for an axial beam according to claim 2 or 3.

6. The outer diameter of the head of the screw hole protection member is larger than the maximum diameter of the tapered surface. A method for manufacturing a cylindrical elastic coupling device for an axial beam according to claim 1.

7. As a pretreatment in the pretreatment step for the inner shaft member, a surface roughening treatment by blasting is performed, so that the surface roughness of the portion of the outer circumferential surface of the inner shaft member to which the main rubber elastic body is fixed is greater than the surface roughness of at least a portion of the tapered surface. A method for manufacturing a cylindrical elastic coupling device for an axial beam according to any one of claims 1 to 3.

8. The coating layer formed in the inner shaft member pretreatment step includes at least one of a zinc phosphate coating and an adhesive layer. A method for manufacturing a cylindrical elastic coupling device for an axial beam according to any one of claims 1 to 3.

9. The inclination angle of the tapered surface with respect to a plane perpendicular to the central axis of the screw hole is within the range of 20 to 60 degrees. A method for manufacturing a cylindrical elastic coupling device for an axial beam according to any one of claims 1 to 3.

10. The mounting bolt is a separate component from the screw hole protection member. A method for manufacturing a cylindrical elastic coupling device for an axial beam according to any one of claims 1 to 3.

11. The mounting bolt is made of the same material as the screw hole protection member. A method for manufacturing a cylindrical elastic coupling device for an axial beam according to any one of claims 1 to 3.

12. The screw hole protection member that closes the screw hole in the screw hole protection step comprises a screw shaft portion that is screwed into the screw hole. A method for manufacturing a cylindrical elastic coupling device for an axial beam according to any one of claims 1 to 3.

13. In the screw hole protection step, the screw shaft portion of the screw hole protection member is screwed into the screw hole for four or more threads. A method for manufacturing a cylindrical elastic coupling device for an axial beam according to claim 12.

14. In the screw hole protection step, the screwed shaft portion of the screw hole protection member is screwed into the screw hole for a length of 10 times the nominal diameter or less. A method for manufacturing a cylindrical elastic coupling device for an axial beam according to claim 12.

15. The screw hole protection member comprises a shaft portion that is inserted into the screw hole and a head portion that has a larger diameter than the shaft portion. In the screw hole protection step, the head is separated from the opening periphery of the screw hole. A method for manufacturing a cylindrical elastic coupling device for an axial beam according to claim 3.

16. The screw hole protection member comprises a shaft portion which is inserted into the screw hole, at least a part of it. The outer diameter of the screw hole protection member is maximized at the shaft portion. A method for manufacturing a cylindrical elastic coupling device for an axial beam according to claim 3.

17. The screw hole is formed in a part of the inner shaft member in the radial direction of the inner shaft member through which the screw hole extends. A method for manufacturing a cylindrical elastic coupling device for an axial beam according to any one of claims 1 to 3.

18. The aforementioned screw hole penetrates the inner shaft member and is formed along the entire radial length of the inner shaft member. A method for manufacturing a cylindrical elastic coupling device for an axial beam according to any one of claims 1 to 3.

19. The pretreatment step for the inner shaft member includes a vulcanization bonding step in which the main rubber elastic body is vulcanized and bonded to the pretreated inner shaft member. In the vulcanization bonding process, the screw hole of the inner shaft member is covered and protected by the screw hole protection member. A method for manufacturing a cylindrical elastic coupling device for an axial beam according to any one of claims 1 to 3.

20. The pretreatment applied to the inner shaft member in the aforementioned inner shaft member pretreatment step is at least one of the following: a cleaning treatment with a cleaning solution; a surface roughening treatment by blasting; a chemical conversion coating treatment that forms a zinc phosphate film on the surface; and an adhesive layer formation treatment that forms an adhesive layer on the surface. A method for manufacturing a cylindrical elastic coupling device for an axial beam according to any one of claims 1 to 3.

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