Joined body, shock absorber, and method for manufacturing shock absorber

A joined body includes a first member having a female portion, and a second member having a male portion inserted in the female portion at one end, and an annular groove along an outer circumference of the male portion. The first member and the second member are fitted to each other. A plurality of joint portions is formed on a side wall of the female portion. The joint portions are joined to the male portion by being pushed in the annular groove. A pressing portion is formed at the female portion so as to face a position of the male portion axially different from the annular groove of the male portion. The pressing portion pressed against the male portion.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a joined body, a shock absorber, and a method for manufacturing a shock absorber.

2. Description of the Related Art

For example, Japanese Patent Public Disclosure No. 2008-55483 discloses a technique for fitting a female portion to a male portion with a plurality of annular grooves formed thereon, and mechanically clinching the female portion in a staggered manner, thereby joining the male portion and the female portion.

SUMMARY OF THE INVENTION

However, mechanically clinching the female portion in a staggered manner, like the technique disclosed in Japanese Patent Public Disclosure No. 2008-55483, has a problem with its workability.

Therefore, an object of the present invention is to provide a joined body, a shock absorber, and a method for manufacturing a shock absorber with improved workability.

To achieve the foregoing and other objects, the present invention is configured in such a manner that a plurality of joint portions, which is pushed in and joined to an annular groove of a male portion, is formed at a side wall of a female portion, and a pressing portion, which is pressed against the male portion, is formed at the female portion so as to face an axially different position from the annular groove of the male portion.

Further, the present invention is configured in such a manner that a plurality of joint portions, which is pushed in and joined to an annular groove of a rod, is formed at a side wall of a connection cylinder portion, and a pressing portion, which is pressed against the rod, is formed so as to face a position axially different from the annular groove.

Further, the present invention includes performing a joining process for joining a mounting eye and a rod by inserting the rod in a connection cylinder of the mounting eye, and pushing a side wall of the connection cylinder portion in an annular groove of the rod, after coating of a mounting eye, coating of a cylinder, and plating of a rod.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1illustrates a shock absorber11as the first embodiment. This shock absorber11is used for a suspension apparatus for an automobile. The shock absorber11includes a cylinder12sealing containing hydraulic fluid such as oil, a piston13slidably inserted in the cylinder12, a rod (a second member)14having one end coupled to the piston13and the other end extending to the outside of the cylinder12, a mounting eye15attached to the other end of the rod14, a dust cover16supported by the mounting eye15and covering a portion of the rod14that extends from the cylinder12, and a mounting eye17attached to an opposite end of the cylinder12from the rod14. The mounting eye15includes an outer eye main body (a first member)21attached to the rod14, and an inner rubber bush22. Similarly, the mounting eye17also includes an outer eye main body23attached to the cylinder12and an inner rubber bush24.

For example, one of the mounting eyes15and17of the shock absorber11is supported by a vehicle body, and the other is coupled to a wheel side. More specifically, the shock absorber11is coupled to the vehicle body side via the mounting eye15attached to the rod14, and is coupled to the wheel side via the mounting eye17attached to the cylinder12. Conversely, the shock absorber11may be coupled to the vehicle body side via the mounting eye17attached to the cylinder12, and may be coupled to the wheel side via the mounting eye15attached to the rod14.

As described above, the eye main body21is attached to the one end of the rod14, and this one end of the rod14constitutes a male portion27, which is a solid rod-like body circular in cross section, and is configured to be fitted in the eye main body21. Hereinafter, the one end of the rod14at the side attached to the eye main body21will be referred to as the “insertion-side end”. As illustrated inFIGS. 2 and 3, the male portion27includes an annular groove28along an outer circumference at an intermediate predetermined position in an axial direction. A portion of an outer circumference of the male portion27except for the annular groove28constitutes a fitted cylindrical surface portion (a fitted portion)30, which extends continuously from an outer circumferential surface of an intermediate shaft portion29connected to the male portion27of the rod14, keeping a same diameter from the intermediate shaft portion29and a constant diameter through the entire fitted cylindrical surface portion30. The fitted cylindrical surface portion30has a larger diameter than a groove bottom surface portion32of the annular groove28, which is the smallest in diameter. The groove bottom surface portion32of the annular groove28is formed so as to have a constant diameter at a portion of the groove bottom surface portion32except for both ends in the axial direction of the rod14, and is formed so as to extend along a same position in the axial direction of the rod14, keeping a constant width. Groove wall surface portions33and33at the both ends of the annular groove28in the axial direction of the rod14extend perpendicularly to a central axis of the rod14and connect end edges of the groove bottom surface portion32and the fitted cylindrical surface portion30. In other words, the annular groove28is formed annularly with a constant width at a predetermined position in the axial direction of the rod14. An abutment tip surface portion34of the male portion27at the tip thereof extends perpendicularly to the central axis of the rod14.

The eye main body21attached to the rod14includes an annular member40having an annular shape, a female member (a female portion)41fixed along a radial direction of the annular member40at an outer circumferential portion of the annular member40, and a holding member42disposed between the annular member40and the female member41. The annular member40, the female member41, and the holding member42are integrally assembled to constitute the eye main body21.

The annular member40includes a single attachment recess portion45, which is radially internally recessed, at the outer circumferential portion of the annular member40. The attachment recess portion45includes a flat circular attachment bottom surface portion46perpendicular to the radial direction of the annular member40, and an attachment tapering surface portion47extending from an outer circumference of the attachment bottom surface portion46to the outer circumferential surface of the annular member40in a flaring manner. The attachment tapering surface portion47shares a same axis with the attachment bottom surface portion46, and the diameter thereof increases toward the radially outer side of the annular member40.

The female member41includes a cylindrical connection cylinder portion (a first member)51, a closing bottom portion52, which closes an axial one side of the connection cylinder portion51, and an attachment shaft portion53, which protrudes to an opposite side of the closing bottom portion52from the connection cylinder portion51. The female member41further includes an opening portion54at an opposite side of the connection cylinder portion51from the closing bottom portion52. The inside of the connection cylinder portion51is hollow by being surrounded by an inner-side wall (a side wall)85, and opens at the opening portion54. The male portion27of the rod14(the second member) is inserted from the opening portion54into the connection cylinder portion51.

An outer surface of the attachment shaft portion53includes a holding cylindrical surface portion57cylindrically protruding from the closing bottom portion52, an attachment tapering surface portion58extending from an opposite side of the holding cylindrical surface portion57from the closing bottom surface52in a reducing tapering manner, and a flat attachment tip surface portion59positioned at an opposite side of the attachment tapering surface portion58from the holding cylindrical surface portion57. The holding cylindrical surface portion57, the attachment tapering surface portion58, and the attachment tip surface portion59share a same central axis, which matches the central axis of the attachment shaft portion53. The attachment tip surface portion59is perpendicular to this central axis.

The closing bottom portion52of the female member41includes a flange-like large-diameter portion63formed at an end of the closing bottom portion52closer to the connection cylinder portion51so as to have a larger diameter than a maximum outer diameter of the connection cylinder portion51. An outer circumferential surface of the large-diameter portion63constitutes a large-diameter cylindrical surface portion64. The closing bottom portion52includes a holding tapering surface portion65connecting the large-diameter cylindrical surface portion64and the holding cylindrical surface portion57of the attachment shaft portion53in a tapering manner. Further, the closing bottom portion52includes a flat abutment bottom surface portion66inside the connection cylinder portion51, and a flat stepped surface portion67outside the connection cylinder portion51. The large-diameter cylindrical surface portion64, the holding tapering surface portion65, the abutment bottom surface portion66, and the stepped surface portion67of the closing bottom portion52share a same central axis, which matches the central axis of the closing bottom portion52. The abutment bottom surface portion66is perpendicular to this central axis. This central axis matches the central axis of the attachment shaft portion53, and corresponds to the central axis of the female member41.

The holding member42includes a cylindrical portion70, a tapering portion71extending from an axial one end of the cylindrical portion70so as to have an increasing diameter from the cylindrical portion70toward axial another side, and a holding plate portion72flaring from an opposite side of the tapering portion71from the cylindrical portion70toward a radially outer side.

The above-described annular member40, female member41, and holding member42are integrally assembled to constitute the eye main body21. During this integrally assembling process, first, the cylindrical portion70of the holding member42is fitted to the holding cylindrical surface portion57of the attachment shaft portion53of the female member41, and the inner surface of the tapering portion71is placed into abutment with the holding tapering surface portion65of the closing bottom portion52of the female member41, whereby the holding member42is supported by the female member41. Next, the attachment tapering surface portion58of the attachment shaft portion53of the female member41is placed into abutment with the attachment tapering surface portion47of the annular member40, and the attachment tip surface portion59of the attachment shaft portion53of the female member41is placed into abutment with the attachment bottom surface portion46of the annular member40, whereby the holding member42is placed into abutment with the outer circumferential surface of the annular member40at an opposite side of the cylindrical portion70from the tapering portion71. While the respective components are maintained in this state, the cylindrical portion70of the holding member42and the attachment shaft portion53of the female member41are fixed to the annular member40by welding. As a result, the annular member40, the female member41, and the holding member42are integrally assembled to constitute the eye main body21. When they are integrally assembled in this way, the central axis of the female member41extends along the radial direction of the annular member40.

As illustrated inFIG. 1, the dust cover16is coupled to the outer circumferential portion of the holding plate portion72of the holding member42, whereby the dust cover16is held by the eye main body21.

As illustrated inFIGS. 2 to 4, a recess portion76, which is recessed radially inwardly, is formed at an outer wall75of the connection cylinder portion51of the female member41at the radially outer side by plastic working. Before plastic working is performed, the connection cylinder portion51has a cylindrical shape coaxial with the central axis of the attachment shaft portion53and the closing bottom portion52. Then, the male portion27at the other end (the insertion-side end) of the rod14(the second member), which extends to the outside of the cylinder12, is inserted into the opening portion54of the cylindrical connection cylinder portion (the first member)51in such a manner that the abutment tip surface portion34of the male portion27is in abutment with the abutment bottom surface portion66of the female member41. In other words, the female member41of the eye main body21and the male portion27of the rod14are fitted to each other. Therefore, the cylindrical connection cylinder portion51has an inner diameter slightly larger than the fitted cylindrical surface portion30of the male portion27of the rod14, and the connection cylinder portion51and the rod14are fitted as a clearance fit. The male portion27of the rod14corresponds to the portion of the rod14that is inserted in the connection cylinder portion51of the female member41. The annular groove28is formed at a middle position at an axially opposite side of the male portion27from the abutment tip surface portion34.

The groove-like recess portion76, which partially extends in the circumferential direction of the female member41, is formed on the outer wall75of the cylindrical connection cylinder portion51by plastic deformation, which is performed from the outer circumferential surface by swaging processing. The outer circumferential surface of the outer wall75of the connection cylinder portion51except for the recess portion76constitutes a cylindrical outer circumference cylindrical surface portion77. If the central axis of the outer circumferential surface portion77is designed to correspond to the central axis of the connection cylinder portion51, this central axis also matches the central axis of the female member41.

As illustrated inFIGS. 2 and 3, the recess portion76includes an opening-side recess portion81and a bottom-side recess portion82. The opening-side recess portion81is located axially closer to the opening portion54of the female member41, and is deep in the radial direction of the female member41and is wide in the circumferential direction of the female member41. The bottom-side recess portion82axially extends from the opening-side recess portion81toward the closing bottom portion52of the female member41, and is shallower in the radial direction of the female member41than the opening-side recess portion81, and narrower in the circumferential direction of the female member41than the opening-side recess portion81. In other words, as illustrated inFIG. 3, the recess portion76has a T shape as viewed from the radial direction of the female member41. The opening-side recess portion81has a longer length thereof in the circumferential direction than the length thereof in the axial direction of the female member41. On the other hand, the bottom-side recess portion82has a longer length thereof in the axial direction than the length thereof in the circumferential direction of the female member41.

As illustrated inFIGS. 2 to 4, the opening-side recess portion81is aligned with the annular groove28of the rod14in the axial direction of the female member41and the rod14in such a state that the abutment tip surface portion34of the rod14is in abutment with the abutment bottom surface portion66of the female member41. A joint portion86, which radially inwardly protrudes by formation of the opening-side recess portion81and is joined by being pushed in the annular groove28of the rod14, is formed on the inner-side wall (the side wall)85in the radially inner side at a position of the opening-side recess portion81in the axial direction of the female member41. Therefore, this joint portion86is also formed by plastic deformation based on the above-described swaging processing. The connection cylinder portion51remains cylindrical except for the joint portion86on the inner-side wall85at the radially inner side, and constitutes an inner circumferential cylindrical surface portion87. The central axis of the inner circumferential cylindrical surface portion87also matches the central axis of the female member41.

The opening-side recess portion81includes a cylindrical bottom surface portion90, the center of which matches the central axis of the female member41, at a deepest position. The opening-side recess portion81includes a wall surface portion91radially outwardly extending from an end edge of the bottom surface portion90closer to the opening portion54in the axial direction of the female member41, a wall surface portion92radially outwardly extending from an end edge of the bottom surface portion90at an opposite side from the opening portion54in the axial direction of the female member41, and a pair of wall surface portions93(only one of them is illustrated inFIGS. 2 and 4, since they illustrate cross sections) radially outwardly extending from both end edges of the bottom surface portion90in the circumferential direction of the female member41. The bottom surface portion90is formed at a predetermined position in the axial direction of the female member41so as to have a constant width in the circumferential direction.

The wall surface portion91closer to the opening portion54is slightly inclined in such a manner that an outer side of the wall surface portion91in the radial direction of the female member41is positioned closer to the opening portion54in the axial direction. The wall surface portion92at an opposite side from the opening portion54is slightly inclined in such a manner that an outer side of the wall surface portion91in the radial direction of the female member41is positioned closer to the opposite side from the opening portion54in the axial direction of the female member41. The pair of wall surface portions93is also slightly inclined in such a manner that outer sides of the wall surface portions93in the radial direction of the female member41are spaced apart from each other by an increasing distance. In other words, the opening-side recess portion81has such a gradually narrowing shape that the width thereof in the axial direction of the female member41tapers toward the bottom surface portion90, and the width thereof in the circumferential direction of the female member41also tapers toward the bottom surface portion90.

The bottom surface portion90of the opening-side recess portion81as a whole is formed within a range of the annular groove28of the rod14, i.e., between the groove wall surface portions33and33at the both sides in the axial direction of the female member41.

The joint portion86is inserted in the annular groove28of the rod14, and the abutment surface portion94at the tip of joint portion86abuts against the groove bottom surface portion32in plane contact with the groove bottom surface portion32. Further, as illustrated inFIG. 2, the joint portion86is in abutment with the groove wall surface portions33and33at both sides of the annular groove28at least the opposite end of each groove wall surface portion33from the groove bottom surface portion32, i.e., the joint portion86is in abutment with each of the groove wall surface portions33and33at least at the opening side of the annular groove28. The joint portion86also has a shape short in the axial direction and long in the circumferential direction of the female member41in a similar manner to the opening-side recess portion81.

The bottom-side recess portion82is axially out of alignment with the annular groove28of the rod14in such a state that the abutment tip surface portion34of the rod14is in abutment with the abutment bottom surface portion66of the female member41. A pressing portion99is formed on the inner-side wall85at a position of the bottom-side recess portion82in the axial direction of the female member41. The pressing portion99slightly radially inwardly protrudes beyond the inner circumference cylindrical surface portion87by formation of the bottom-side recess portion82so as to be pressed against the fitted cylindrical surface portion30between the annular groove28and the abutment tip surface portion34of the rod14. Therefore, this pressing portion99is also formed by plastic deformation based on the above-described swaging processing. In other words, the pressing portion99, which is pressed against the male portion27, is formed at the female member41so as to face the fitted cylindrical surface portion30at a position axially different from the annular groove28of the male portion27of the rod14. In further other words, the joint portion86, which is joined by being pushed in the annular groove28, and the pressing portion99, which is pressed against the rod14facing a position axially different from the annular groove28, are formed on the inner-side wall85of the female member41at the radially inner side.

The pressing portion99abuts against the fitted cylindrical surface portion30at an abutment surface portion100as the protruding tip of the pressing portion99in plane contact with the fitted cylindrical surface portion30. This pressing portion99does not have a portion recessed in the radial direction of the female member41from the abutment surface portion100between the pressing portion99and one of portions of the joint portion86in abutment with both the groove wall surface portions33, which are positioned at the opposite side from the opening portion54, as a result of which the pressing portion99is connected to the joint portion86at the abutment surface portion100. In other words, the pressing portion99is formed continuously with the joint portion86in the axial direction of the female member41, i.e., the axial direction of the rod14. In other words, the pressing portion99is constantly in contact with the end of the fitted cylindrical surface portion30closer to the annular groove28at least at the side closer to the abutment tip surface portion34relative to the annular groove28of the rod14while applying a pressing force. The pressing portion99is formed so as to extend from the joint portion86in the direction of the axial one end of the rod14with the male portion27formed thereon, i.e., the direction of the abutment tip surface portion34, i.e., the direction of the closing bottom portion52of the female member41.

As illustrated inFIGS. 2 and 3, the bottom-side recess portion82is open at a middle position of the wall surface portion92of the opening-side recess portion81in the circumferential direction of the female member41at the end closer to the closing bottom portion52. The bottom-side recess portion82includes a bottom surface portion101, which extends along the circumferential direction of the female member41, and a pair of wall surface portions102(only one of them is illustrated inFIGS. 2 and 4, since they illustrate cross sections), which radially outwardly extend from both end edges of the bottom surface portion101in the circumferential direction of the female member41. The bottom surface portion101has a shape that defines a circular arc concaved inwardly in the radial direction of the female member41from the portion of the outer circumferential cylindrical surface portion77closer to the closing bottom portion52toward the opening-side recess81, and then substantially complies with the axial direction of the female member41. Further, the bottom surface portion101of the bottom-side recess portion82is radially inwardly inclined at the side closer to the opening-side recess portion81and is connected to the groove bottom surface portion32of the opening-side recess portion81.

The pair of wall surface portions102extends substantially in parallel. In other words, an angle defined by the pair of wall surface portions102is smaller than an angle defined by the pair of wall surface portions93of the opening-side recess portion81. The pressing portion99also has a shape short in the circumferential direction and long in the axial direction of the female member41in a similar manner to the bottom-side recess portion82, and is shorter than the joint portion86in the circumferential direction. However, the pressing portion99and the bottom-side recess portion82may be shaped so as to be long in the circumferential direction and short in the axial direction of the female member41.

The average depth of the opening-side recess portion81is deeper than the average depth of the bottom-side recess portion82. Therefore, the bottom-side recess portion82is deformed in the radial direction of the female member41by plastic deformation by a smaller deformation amount than the opening-side recess portion81, and the pressing portion99is pushed in by a smaller amount than the joint portion86.

The recess portion76, which includes the above-described opening-side recess portion81and bottom-side recess portion82, is formed at a plurality of positions equiangular in the circumferential direction of the female member41. Therefore, the joint portion86and the pressing portion99are respectively formed at a plurality of positions equiangular in the circumferential direction of the female member41. The opening-end recess portion81is formed at a plurality of positions equiangular in the circumferential direction of the female member41, thereby forming a radially outwardly extending flange portion108at the end of the female member41closer to the opening portion54, i.e., the opening end of the female member41. Each of the recess portions76is formed so as to correspond to another recess portion76at a symmetrical position around the central axis of the female member41, i.e., a position circumferentially different by 180 degrees.

Next, a manufacturing method for manufacturing the thus-configured shock absorber11will be described.

The female member41before the above-described swaging processing is performed thereon, i.e., the female member41having the connection cylinder portion51in a cylindrical state, the annular member40, and the holding member42are integrally joined by welding to form the eye main body21. Then, a coating process is performed on the eye main body21to coat the eye main body21with cation. Further, a coating process is also performed on the cylinder12with the eye main body23welded thereto to coat the cylinder12with cation. Further, a plating process is performed on the rod14to form a plating layer on an outer surface of the rod14with the annular groove28formed thereon.

The coating process for coating the eye main body21of the mounting eye15, the coating process for coating the cylinder12, and the plating process for plating the rod14as described above are respectively separately performed. After that, as described above, a joining process and a pressing process are simultaneously performed. The joining process includes inserting the male portion27of the rod14in the connection cylinder portion51of the eye main body21of the mounting eye15, and pushing the joint portion86of the inner-side wall85into the annular groove28of the rod14by swaging the outer-side wall75of the connection cylinder portion51from the outside, thereby joining the rod14and the eye main body21. The pressing process includes pressing a position of the inner-side wall85of the connection cylinder51corresponding to the fitted cylindrical surface portion30, which is axially different from the annular groove28, toward the rod14. Further, the joining process and the pressing process are performed at a plurality of positions in the circumferential direction simultaneously.

In this way, the recess portion76, which is constituted by the opening-side recess portion81and the bottom-side recess portion82, is formed at a plurality of positions in the circumferential direction of the eye main body21. As a result, the joint portion86inserted in the annular groove28of the rod14, and the pressing portion99pressed against the fitted cylindrical surface portion30of the rod14are formed at a plurality of positions in the circumferential direction of the eye main body21, thereby fixing the eye main body21to the rod14. In other words, the joining process, in which the eye main body21and the rod14are joined to each other by pushing the joint portion86of the connection cylinder portion51into the annular groove28of the rod14, is performed, thereby prohibiting an axial relative movement between the eye main body21and the rod14. In addition, the pressing process, in which the pressing portion99is pressed against the fitted cylindrical portion30of the rod14at a position of the connection cylinder51axially different from the annular groove28, is performed, thereby eliminating a space formed by the clearance fit to prevent the rod14from being inclined relative to the eye main body21. Further, since the eye main body21is circumferentially partially pressed against the rod14, a relative rotation is also prohibited therebetween. The joining process and the pressing process may be separately performed. In this case, after the joining process is performed so that the eye main body21is coupled to the rod14so as to prohibit an axial relative movement therebetween, the pressing process is performed so as to prohibit the rod14from being inclined relative to the eye main body21.

The above-described joining process and pressing process are circumferentially simultaneously performed with use of a swaging processing apparatus120illustrated inFIGS. 5 and 6. This swaging processing apparatus120includes a disk-shaped circular table121as illustrated inFIG. 5, and a support table122disposed at a center of the table121for supporting the eye main body21at the annular member40thereof as illustrated inFIG. 6. This support table122includes a lower portion support portion123, which supports the lower portion of the annular member40from below, and a cylindrical side portion support portion124, which supports the both sides of the annular member40in the radial direction from the sides. The eye main body21is supported by the support table122in such a state that the annular member40faces downward while the female member41faces upward, whereby the central axis of the female member41can match the central axis of the table121.

As illustrated inFIG. 5, a plurality of swaging cylinders127, in particular, six swaging cylinders127are mounted at an outer circumferential side of the table121equiangularly in the circumferential direction of the table121around the central axis of the table121. The swaging cylinder127includes a cylinder main body128fixed to the table121, and a rod129that can enter or exit the cylinder main body128. The swaging cylinder127is disposed in such a manner that the central axis of the rod129extends along the radial direction of the table121, and the rod129can advance toward the center of the table121. Further, as illustrated inFIG. 6, a slide rail132is fixed to the table121along the radial direction of the table121so as to connect the central axis of the table121and each swaging cylinder127. A tool slider133is supported by the slide rail132so as to be movable by being guided by the slide rail132, and the rod129of the swaging cylinder127is coupled with each tool slider133.

As illustrated inFIG. 5, a slide rail136is fixed along the radial direction of the table121between the swaging cylinders127adjacent in the circumferential direction of the table121. A synchronization slider137is supported by the slide rail136so as to be guided by the slide rail136.

A link member140is disposed between the tool slider133coupled with the swaging cylinder127and the synchronization slider137adjacent thereto. The link member140has one end rotationally supported by a rotational shaft141of the tool slider133, and the other end rotationally supported by a rotational shaft142of the synchronization slider137. All of the tool sliders133are coupled to the synchronization sliders137adjacent thereto at the both sides thereof via the link members140, whereby all of the tool sliders133are configured to slide in synchronization with one another. Referring toFIG. 6, the swaging cylinder127at the left side indicates the rod129in a state retracted in the cylinder127, and the swaging cylinder127at the right side indicates the rod129in a state extended out of the cylinder127.

A tool attachment portion145is formed at the tip side of the tool slider133. A punch150illustrated inFIG. 7, which is a swaging tool, is fixed to the tool attachment portion145. The punch150has a tapering shape in a planar view. The punch150includes an upper surface portion151and a lower surface portion152in parallel with each other, a back surface portion153connecting the back end edges of the upper surface portion151and the lower surface portion152perpendicularly to the upper surface portion151and the lower surface portion152, a pair of parallel back portion side surface portions154forwardly extending from edges of both sides of the back surface portion153perpendicularly to the upper and lower surface portions151and152and the back surface portion153, and a pair of front portion side surface portions155extending from the respective front edges of the back portion side surface portions154perpendicularly to the upper and lower surface portions151and152and obtusely relative to the back portion side surface portions154continuous from the back side surface portions154. A distance between the pair of front portion side surface portions155reduces toward the opposite sides thereof from the pair of the back portion side surface portions154.

Further, the punch150includes a tip surface portion160located at the opposite side from the back surface portion153, extending perpendicularly to the upper and lower surface portions151and152, and constituted by a cylindrical surface recessed backward. The tip surface portion160is disposed at a middle position between the upper and lower surface portions151and152. The tip surface portion160is formed at a predetermined position in the direction connecting the upper and lower surface portions151and152, keeping a constant width. The punch150includes an extending upper surface portion161backwardly and upwardly extending from the upper edge of the tip surface portion160toward the back surface portion153, an upper front surface portion162extending from the back end edge of the extending upper surface portion161to the upper surface portion151perpendicularly to the upper surface portion151, a pair of extending lower surface portions163backwardly and downwardly extending from both sides of the lower edge of the tip surface portion160, a pair of lower front surface portions164extending from back end edges of the respective extending lower surface portions163to the lower surface portion152perpendicularly to the lower surface portion152, a central front surface portion165extending from the center of the lower edge of the tip surface portion160to the lower surface portion152, and a pair of front end side surface portions166extending from edges of both sides of the central front surface portion165to edges of inner sides of the pair of lower front surface portions164in parallel with the pair of back portion side surface portions154. The central front surface portion165is offset from the tip surface portion160toward the back surface portion153as a whole.

As illustrated inFIG. 6, the above-described punch150is disposed in such a manner that the upper surface portion151and the lower surface portion152are horizontally at the upper side and the lower side, respectively. The punch150is fixed to the tool attachment portion145of the tool slider133in such a posture that the tip surface portion160is disposed at the central side of the table121. Then, the above-described recess portion76is formed at the eye main body21illustrated inFIGS. 2 to 4by a tip swaging portion175including the tip surface portion160illustrated inFIG. 7. More specifically, the punch150functions in the following manner. The tip surface portion160forms the bottom surface portion90of the opening-side recess portion81of the recess portion76. The extending upper surface portion161forms the wall surface portion91of the opening-side recess portion81. The extending lower surface portion163forms the wall surface portion92of the opening-side recess portion81. The front portions of the pair of front portion side surface portions155form the pair of wall surface portions93of the opening-side recess portion81. The pair of front end side surface portions166forms the pair of wall surface portions102of the bottom-side recess portion82. The central front surface portion165forms the bottom surface portion101of the bottom-side recess portion82.

The tip swaging portion175of the punch150includes the tip surface portion160, the extending upper surface portion161, the pair of extending lower surface portion163, the front portions of the pair of front portion side surface portions155, the pair of front end side surface portions166, and the central front surface portion165. The tip swaging portion175has a T shape as viewed from the front thereof. In other words, the tip of the punch150has a T shape. A plurality of attachment screw holes177is formed at the punch150perpendicularly to the upper and lower surface portions151and152. The punch150is fixed to the tool attachment portion145of the swaging processing apparatus120illustrated inFIG. 5at the attachment screw holes177.

The above-described punches150are respectively fixed to the tool attachment portions145of the tool sliders133with the tip swaging portions175thereof facing the support table122. As a result, the plurality of punches150is disposed at six positions equiangularly in the circumferential direction of the table121, and therefore they become slidable in the radial direction of the table121, respectively.

The rod14is inserted from above into the opening portion54of the female member41which opens in the upward direction of the eye main body21supported by the support table122, and is fitted therein at the male portion27. The swaging processing apparatus120includes a rod support mechanism180that vertically supports the rod14fitted in the eye main body21in this way. The rod support mechanism180supports an upper end of the rod14by a vertically movable rod support portion181.

Then, the eye main body21is supported by the support table122of the above-described swaging processing apparatus120. After the male portion27of the rod14is fitted in the female member41of the eye main body21, the upper end of the rod14is supported by the rod support portion181of the rod support mechanism180. As a result, the eye main body21and the rod14are set in such a state that they vertically extend, sharing a common central axis. In this state, a so-called shrinking process is performed in the following manner. When all of the swaging cylinders127are driven in this state, the swaging cylinders127are accurately synchronized with one another by the link members140and the synchronization sliders137. The plurality of tool sliders133advances toward the eye main body21. The plurality of punches150fixed to the tool sliders133move to abut at the tip swaging portions175against the female member41of the eye main body21from the radially outer side simultaneously, thereby radially inwardly pushing in the female member41at the attachment positions. At this time, the punch150illustrated inFIG. 7is configured in such a manner that the central front surface portion165, which forms the bottom surface portion101of the bottom-side recess portion82illustrated inFIGS. 2 to 4, is overall backwardly offset relative t to the tip surface portion160, which forms the bottom surface portion90of the opening-side recess portion81. Therefore, the inner portion of the female member41corresponding to the bottom-side recess portion82is deformed in the radial direction by a smaller amount than the inner portion of the female member41corresponding to the opening-side recess portion81, as a result of which, the pressing portion99is pressed by a smaller amount than the joint portion86.

In this way, the recess portion76, which is constituted by the opening-side recess portion81and the bottom-side recess portion82illustrated inFIGS. 2 to 4, is formed at six positions equiangular in the circumferential direction of the eye main body21. As a result, the joint portions86inserted in the annular groove28of the rod14, and the pressing portions99pressed against the fitted cylindrical surface portion30of the rod14are formed at the six positions equiangular in the circumferential direction of the eye main body21, thereby fixing the eye main body21to the rod14. In this way, a jointed body182, which is formed by fixing the eye main body21to the rod14, is acquired.

After the above-described joining process and pressing process are simultaneously performed, the joined body182acquired from these processes is assembled to the cylinder12illustrated inFIG. 1. At this time, for example, as illustrated inFIG. 8, the joined body182is placed with the eye main body21down and the annular member40fixed to a support jig183. Then, an oil seal185, a rod guide186, and a buffer member187are mounted to the rod14of the joined body182from the opposite end from the eye main body21, and a retainer188is fixed to the rod14. After that, a piston13is fixed to the opposite end from the eye main body21of the rod14by a nut189. The joined body182with the oil seal185, the rod guide186, the buffer member187, the retainer188, the piston13, and the nut189attached thereto in this way is inserted in and attached to the cylinder12illustrated inFIG. 1.

Alternatively, as illustrated inFIG. 9, the rod14before the above described joining process and pressing process, i.e., the rod14before the eye main body21is attached thereto may be assembled to the cylinder12, and after that, the above-described joining and pressing processes may be performed to join the eye main body21to the rod14to acquire the joined body182.

The invention disclosed in Japanese Patent Public Disclosure No. 2008-55483 discussed in Related Art is configured in such a manner that a plurality of annular grooves is formed at a male portion, and clinch portions are respectively pushed in the annular grooves to join the male portion to a female portion, thereby deteriorating the stiffness of the female portion. Therefore, a further improvement is demanded in terms of the product quality. Further, this invention requires formation of a plurality of annular grooves, and formation of clinch portions in a staggered arrangement, resulting in an increase in a time required for processing. Further, the necessity of formation of the plurality of annular grooves leads to a problem of an increase in the axial length of a connection portion.

On the other hand, according to the above-described first exemplary embodiment, the male portion27of the rod14(the second member), which has the single annular groove28formed around the outer circumference thereof, is fitted in the connection cylinder portion51(the first member) of the female member41of the eye main body21. Then, during the joining process, the plurality of joint portions86, which is joined by being pushed in the annular groove28, is circumferentially formed on the inner-side wall85of the connection cylinder portion51of the female member41. Further, during the pressing process, the pressing portion99, which is pressed against the fitted cylindrical surface portion30of the male portion27, is formed on the inner-side wall85of the connection cylinder portion51of the female member41so as to face the position axially different from the annular groove28. Therefore, the female member41of the eye main body21can be joined to the rod14by the joint portions86while ensuring the stiffness against an input in the axial direction from the rod14. In addition, the female member41of the eye main body21can be pressed against the rod14at the axially different positions of the joint portion86and the pressing portion99, whereby it is possible to prevent the rod14from being inclined relative to the eye main body21. Therefore, it is possible to maintain an appropriate joined state of the rod14to the eye main body21, therefore possible to improve the quality of the joined body182, i.e., the quality of the shock absorber11. More specifically, it is possible to ensure the stiffness against a moment input, a vibration, and a repeated input from the rod14. In addition, due to the formation of the pressing portion99, which is pressed against the fitted cylindrical surface portion30of the male portion27of the rod14, on the inner-side wall85of the connection cylinder portion51of the female member41at the position axially different from the annular groove28, it is possible to prevent a reduction in the stiffness of the female member41, i.e., the eye main body21, leading to improvement of the quality in this term.

Further, the pressing portion99is formed continuously with the joint portion86, so it is possible to press the connection cylinder portion51of the female member41of the eye main body21against a wider range of the rod14with the pressing portion99, whereby it is possible to further securely prevent the rod14from being inclined relative to the eye main body21. Therefore, it is possible to further securely maintain an appropriate joined state of the rod14to the eye main body21. Further, since the pressing portion99and the joint portion86are continuously formed, this makes simultaneous formation of these portions easier. Therefore, it is possible to reduce a time required to join the eye main body21and the rod14. Alternatively, the pressing portion99does not have to be formed continuously with the joint portion86. In other words, the pressing portion99may be spaced apart from the joint portion86. In this case, quality management becomes easier if the pressing portion99and the joint portion86are separately formed.

Further, the joint portion86has a shape short in the axial direction and long in the circumferential direction of the female member41, it is possible to improve the stiffness by the joint portion86and enhance the durability.

Further, the pressing portion99has a shape short in the circumferential direction and long in the axial direction of the female member41, so it is possible to effectively prevent an inclination of the rod14. However, the pressing portion99may be shaped so as to be long in the circumferential direction and short in the axial direction of the female member41.

Further, the pressing portion99is formed from the joint portion86in the direction toward one end closer to the male member27in the axial direction of the rod14(the direction toward the abutment tip surface portion34, the end closer to the insertion-side end of the rod14). Therefore, the joint portion86, which is pushed in the annular groove28, is joined at a position away from the tip of the rod14. Accordingly, it is possible to further securely prevent an inclination of the rod14relative to the eye main body21. Therefore, it is possible to further securely maintain an appropriate joined state of the rod14to the eye main body21. Alternatively, as illustrated inFIG. 10, the pressing portion99and the recess portion82for forming the pressing portion99may be formed from the joint portion86and the recess portion81for forming the joint portion86in the direction toward the other end corresponding to the opposite end from the male portion27in the axial direction of the rod14(the opposite direction from the abutment tip surface portion34, the opposite end from the insertion-side end of the rod14). In this case, it is possible to prevent a reduction in the stiffness of the connection cylinder portion51of the female member41against a force applied in the direction for inclining the rod14. Further alternatively, the pressing portion99and the recess portion82for forming the pressing portion99may be formed from the joint portion86and the recess portion81for forming the joint portion86in both the direction toward the one end and the direction toward the other end in the axial direction of the rod14. Also in this case, the pressing portion99may have a shape short in the circumferential direction and long in the axial direction of the female member41, or a shape long in the circumferential direction and short in the axial direction of the female member41. Further, the recessed portion81and the recessed portion82may be spaced apart, although the workability is reduced.

Further, since pressing portion99is pushed in by a smaller amount than the joint portion86, it is possible to prevent a reduction in the stiffness of the connection cylinder portion51of the female member41.

Further, since the flange portion108is formed at the opening end of the female member41, it is possible to improve the strength of the opening end of the female member41, which may receive a moment due to an inclination of the rod14.

Further, the coating process for coating the eye main body21of the mounting eye15, the coating process for coating the cylinder12, and the plating process for plating the rod14are respectively performed. After that, the rod14is inserted in the connection cylinder portion51of the eye main body21, and the rod14and the eye main body21are joined to each other by pushing the inner-side wall85of the connection cylinder portion51into the annular groove28, thereby performing the joining process. Therefore, the plated layer of the rod14is not affected by the coating process (especially, not affected by heat), whereby it is possible to ensure an excellent quality of the plating. Therefore, it is possible to improve the quality. More specifically, in a case where the rod14is welded to the eye main body21, the coating process should be performed after the welding. Therefore, during a drying process after the coating, the rod14, together with the eye main body21, is placed in a drying oven. At this time, an entry of heat from the drying oven deteriorates the quality of the plating, thereby reducing the corrosion resistance. On the other hand, according to the embodiment of the present invention, the rod14can be joined to the eye main body21without being welded thereto, whereby the eye main body21alone can be coated before the rod14is joined to the eye main body21, and the rod14is not placed in a drying oven, so it is possible to ensure an excellent quality of the plating of the rod14, i.e., improve the anticorrosive characteristic of the plating of the rod14. Further, welding can be omitted, whereby it is possible to prevent occurrence of, for example, a sputter and a burr from welding that adversely affect the sliding portion of the rod14, thereby improving the quality in this term. Further, the necessity of welding is eliminated, which makes it possible to use a high-carbon steel such as S45C as a material of the rod14, enabling improvement of the surface hardness, the strength under the neck, and the tensile strength of the rod14. Improving the surface hardness of the rod14is effective in preventing the sliding surface from being damaged.

Further, the rod14is assembled to the cylinder12after the joining process. This means that there is no cylinder12during the joining process, so the cylinder12does not become an obstacle, thereby facilitating the joining process. Alternatively, in a case where the rod14is assembled with the cylinder12before the joining process, assembling of the rod14to the cylinder12can be freed from a limitation from the eye main body21, and this assembling work can become easier. In this way, the number of choices about the order of the assembling processes increases, enhancing flexibility in the manufacturing processes.

Further, the coating process employs cation coating, which is especially high in the drying temperature when the coating is dried. Therefore, it is possible to further increase the effect of preventing a reduction in the quality of the plating, i.e., improving the anticorrosive characteristic of the plating by omitting putting the rod14in the drying oven. For improving the anticorrosive characteristic, it is necessary to increase the drying temperature. Therefore, this effect can be acquired by not only the cation coating but also any coating that increases the temperature at the time of drying.

Further, the joining process and the pressing process are simultaneously performed, so it is possible to reduce the time required for these processes.

Further, the punch150, which simultaneously performs the joining process and the pressing process, has a T shape as the tip shape thereof. Therefore, the joint portion86can be formed into a wide shape and the pressing portion99can be formed into a narrow shape. Therefore, it is possible to effectively form the joint portion86and the pressing portion99while preventing a reduction in the stiffness of the eye main body21. Further, it is possible to reduce the number of annular groove28, so it is possible to reduce the processing time, and possible to reduce the axial dimension. The present embodiment includes only one annular groove, but may include two annular grooves.

Next, a second embodiment will be described mainly with reference toFIG. 11, focusing on a difference from the first embodiment. Similar members and portions to the first embodiment will be indicated by the same names and reference numerals.

According to the second embodiment, as illustrated inFIG. 11, a counter boring200is formed at the groove bottom surface portion32of the annular groove28of the rod14so as to be recessed beyond the groove bottom surface portion32by cutting processing. The counter boring200is formed along the radial direction of the rod14, and is formed at one or more positions, in particular, two positions different by 180 degrees. As a result, unevenness, which is constituted by recesses defined by the counter borings200and protrusions defined between the counter borings200, is formed inside the annular groove28.

Thus-configured rod14is attached to the eye main body21by the above-described swaging processing apparatus120. At this time, the male portion27of the rod14is inserted in the eye main body21while arranging the phases in such a manner that the above-described two counter borings200are situated on a line connecting any two punches150disposed at positions different by 180 degrees, among the six punches150of the swaging processing apparatus120.

Then, during the joining process, six joint portions86are formed at the female member41of the eye main body21by the six punches150. As a result, as illustrated inFIG. 11A, protrusion portions201, which enter the counter borings200, are formed at the two joint portions86formed by swaging processing with use of the above-described two punches150so as to protrude beyond the abutment surface portion94in contact with the groove bottom surface portion32of the annular groove28of the rod14.

According to the above-described second embodiment, since the unevenness is formed inside the annular groove28, the protrusion portion201of the joint portion86can enter the recessed counter boring200as described above. Therefore, it is possible to increase the strength against a torque of a relative rotation and therefore improve a rotation-prevention effect for prohibiting a relative rotation, compared to the first embodiment, which prohibits a relative rotation between the rod14and the eye main body21only by a contact pressure. As a result, for example, as illustrated inFIG. 8, when the nut189is fastened in a state prohibiting a rotation of the eye main body21after the eye main body21is fixed to the rod14, it is possible to fasten the nut by a higher torque. Unevenness may be formed on at least one of the pair of groove wall surface portions33in the annular groove28, and the unevenness at the groove bottom surface portion32may be added thereto.

Next, a third embodiment will be described mainly with reference toFIGS. 12 to 14, focusing a difference from the second embodiment. Similar members and portions to the second embodiment will be indicated by the same names and reference numerals.

According to the third embodiment, as illustrated inFIG. 12, the counter boring200in the second embodiment is replaced with a serration groove210. The serration groove210is formed at the groove bottom surface portion32of the annular groove28of the rod14by rolling. A large number of serration grooves210are formed equiangularly in the circumferential direction of the rod14. As a result, unevenness, which is consisted by recesses defined by the serration grooves210and protrusions defined between adjacent serration grooves210, is formed inside the annular groove28.

The thus-configured rod14is attached to the eye main body21by the above-described swaging processing apparatus120. At this time, the phase adjustment is unnecessary unlike the second embodiment, and the male portion27of the rod14is inserted in the eye main body21at an arbitrary angle.

Then, during the joining process, the six joint portions86are formed at the female member41of the eye main body21by the six punches150. Then, as illustrated inFIG. 12A, protrusion portions211, which enter the serration grooves210, are formed at the joint portions86formed by the swaging processing with use of the punches150. Although the rod14may be in any phase relative to the eye main body21, the arrangement and interval of the serration grooves210are set in such a manner that at least one protrusion portion211is necessarily formed at every joint portion86.

According to the above described third embodiment, since the unevenness is formed inside the annular groove28, the protrusion portions211of the joint portions86can be inserted in the recessed serration grooves210as described above. Therefore, the third embodiment can provide a similar effect to the second embodiment. In addition, since the grooves210are serration grooves, it is possible to improve manufacturing efficiency. Further, it is possible to form a large number of recesses at narrow arrangement intervals, thereby eliminating the necessity of considering the phase of the rod14relative to the eye main body21as described above. Therefore, it is possible to improve work efficiency at the time of manufacturing. Also in this case, unevenness may be formed on at least one of the pair of groove wail surface portions33in the annular groove28. The unevenness of the groove bottom surface portions32may be added thereto.

Alternatively, as illustrated inFIG. 13, serration grooves215may be formed at the portion of the fitted cylindrical surface portion30except for the annular groove28of the male portion27of the rod14at the side closer to the abutment tip surface portion34relative to the annular groove28. In this case, during the pressing process, protrusion portions are formed at the pressing portion99of the eye main body21so as to protrude beyond the abutment surface portion100and enter the serration grooves215. According to this configuration, it is possible to prevent a reduction in the strength of the rod14. In this case, instead of the serration grooves215, counter borings, like the second embodiment, may be formed at the portion of the fitted cylindrical surface portion30closer to the abutment tip surface portion34relative to the annular groove28.

Further, as illustrated inFIG. 14, serration grooves220may be formed at the portion of the fitted cylindrical surface portion30except for the annular groove28of the male portion27of the rod14at the opposite side of the annular groove28from the abutment tip surface portion34. In this case, during the pressing process, as illustrated inFIG. 10, the pressing portion99(the recessed portion82) is formed at the opposite side of the joint portion86from the abutment tip surface portion34in the axial direction of the rod14. As a result, protrusion portions are formed at the pressing portion99of the eye main body21so as to protrude beyond the abutment surface portion100and enter the serration grooves22. Also in this case, instead of the serration grooves215, counter borings, like the second embodiment, may be formed at the opposite portion of the fitted cylindrical surface portion30from the abutment tip surface portion34relative to the annular groove28.

According to the above-described embodiments, a joined body includes a first member (the eye main body21in the above-described embodiments) having a female portion, and a second member (the rod14in the above-described embodiments) having a male portion inserted in the female portion at one end and an annular groove along an outer circumference of the male portion, and fitted to the first member. In this joined body, a plurality of joint portions is formed on a side wall of the female portion. The joint portions are joined by being pushed in the annular groove. A pressing portion is formed at the female portion so as to face a position of the male portion axially different from the annular groove. The pressing portion is pressed against the male portion. Therefore, it is possible to join the male portion of the first member to the second member so as to ensure the stiffness against an input in an axial direction of the second member by the joint portions. Further, since it is possible to press the female portion against the second member at axially different positions of the joined portions and the pressing portion, it is possible to prevent the second member from being inclined relative to the first member. Therefore, it is possible to maintain an appropriate joined state of the second member to the first member, and therefore possible to improve the quality. Further, since the pressing portion, which is pressed against the male portion, is formed so as to face the position axially different from the annular groove of the female portion, it is possible to prevent a reduction in the stiffness of the female portion.

Further, the pressing portion is formed continuously with the joint portion. Therefore, it is possible to press the female portion of the first member against a wider range of the second member with the pressing portion in addition to the joint portion, whereby it is possible to further securely prevent the second member from being inclined relative to the first member. Therefore, it is possible to further securely maintain an appropriate joined state of the second member to the first member.

Further, in a case where the pressing portion is formed from the joint portion in a direction toward an insertion-side end of the second member, this means that the joint portion, which is pushed in the annular groove, is joined at a position away from a tip of the second member. Therefore, it is possible to further securely prevent the second member from being inclined relative to the first member. Therefore, it is possible to further securely maintain an appropriate joined state of the second member to the first member.

Further, in a case where the pressing portion is formed from the joint portion in a direction toward an opposite end from the insertion-side end of the second member, it is possible to prevent a reduction in the stiffness of the female member of the first member against a force applied in a direction for inclining the second member.

Further, in a case where the pressing portion is pushed in by a smaller amount than the joint portion, it is possible to prevent a reduction in the stiffness of the connection cylinder portion of the female member.

Further, in a case where unevenness is formed inside the annular groove, it is possible to prohibit a relative rotation between the first member and the second member by inserting the joint portion in a recessed portion of the unevenness.

Further, in a case where unevenness is formed at a portion of the male portion except for the annular groove of the male portion and where the first member and the second member are fitted, it is possible to further securely prevent a reduction in the strength of the second member.

Further, in a case where a flange portion is formed at an opening end of the female portion of the first member, it is possible to improve the strength of the opening end of the female portion, which may receive a moment due to an inclination of the second member.

Further, a shock absorber includes a cylinder sealingly containing hydraulic fluid, a piston inserted in the cylinder a rod having one end coupled to the piston and the other end extending to an outside of the cylinder, and a mounting eye attached to the other end of the rod. The mounting eye includes a connection cylinder portion in which the other end of the rod is inserted. An annular groove is formed at a portion of the other end of the rod that is inserted in the connection cylinder portion. A plurality of joint portions is formed on a side wall of the connection cylinder portion, and the joint portions are joined by being pushed in the annular groove. A pressing portion is formed at the side wall of the connection cylinder portion so as to face a position of the rod axially different from the annular groove, and the pressing portion is pressed against the rod. Therefore, it is possible to join the mounting eye to the rod with the joint portions so as to ensure the rigidity against an input in an axial direction of the rod by the joint portions of the mounting eye. In addition, the mounting eye can be pressed against the rod at the axially different positions of the joint portion and the pressing portion, whereby it is possible to prevent the rod from being inclined relative to the mounting eye. Therefore, it is possible to maintain an appropriate joined state of the rod to the mounting eye, therefore possible to improve the quality of the shock absorber. In addition, due to the formation of the pressing portion, which is pressed against the rod, on the connection cylinder portion of the mounting eye at the position axially different from the annular groove of the side wall of the rod, it is possible to prevent a reduction in the stiffness of the mounting eye, leading to improvement of the quality of the shock absorber in this term.

Further, the present invention is a method for manufacturing a shock absorber. The shock absorber includes a cylinder sealingly containing hydraulic fluid, a piston inserted in the cylinder, a rod having one end coupled to the piston and the other end extending to an outside of the cylinder, and a mounting eye attached to the other end of the rod. The mounting eye includes a connection cylinder portion in which the other end of the rod is inserted. An annular groove is formed at a portion of the other end of the rod that is inserted in the connection cylinder portion. The plurality of joint portions is formed on a side wall of the connection cylinder portion, and the joint portions are joined by being pushed in the annular groove. The method for manufacturing the shock absorber includes coating the mounting eye, coating the cylinder, plating the rod, and after performing each of them, joining the mounting eye and the rod by inserting the rod in the connection cylinder portion of the mounting eye and pushing the side wall of the connection cylinder portion in the annular groove. According to this method, the plated layer of the rod is not affected by the coating process, whereby it is possible to ensure a quality of the plated layer. Therefore, it is possible to improve the quality of the shock absorber.

Further, in the above-described manufacturing method, in a case where the rod is assembled with the cylinder after the joining, this means that there is no cylinder during the joining process, thereby facilitating the joining process.

Further, in the above-described manufacturing method, in a case where the rod is assembled with the cylinder before the joining, assembling of the rod to the cylinder can be freed from a limitation from the mounting eye, and therefore this assembling work can become easier.

Further, in the above-described manufacturing method, in a case where the coating includes cation coating in which a temperature is high at the time of drying, it is possible to enhance the effect in preventing a reduction in the quality of the plated layer, which might be otherwise caused by a high temperature at the time of drying.

Further, in a case where the above-described manufacturing method further includes pressing a position of the side wall of the connection cylinder portion axially different from the annular groove toward the rod, it is possible to prohibit the rod from being inclined relative to the mounting eye.

Further, in the above-described manufacturing, in a case where the joining and the pressing are simultaneously performed, it is possible to reduce a time required for joining and pressing.

Further, in the above-described manufacturing, in a case where the joining and pressing include disposing a plurality of punches in a circumferential direction and pushing the punches in a radial direction, and each of the punches has a T shape as a tip shape thereof to form a wider width portion and a narrower width portion, it is possible to effectively perform the joining and the pressing while preventing a reduction in the stiffness of the mounting eye.

Further, according to the embodiments of the present invention, it is possible to improve the workability of the joined body.

The present application claims priority to Japanese Patent Applications No. 2011-236639 filed on Dec. 27, 2011. The entire disclosure of No. 2011-286639 filed on Dec. 27, 2011 including specification, claims, drawings and summary is incorporated herein by reference in its entirety.