JP4368779B2 - Molding method of piston nut - Google Patents

Description

  The present invention relates to a method for forming a piston nut, and in particular, an improvement in a method for forming a piston nut in which a piston nut in which a circular leaf valve is provided adjacent to a piston body in a piston portion of a hydraulic shock absorber for a vehicle or the like is formed by pressing a punch. About.

  For example, in a piston portion of a hydraulic shock absorber for a vehicle or the like, there is a proposal disclosed in, for example, Patent Document 1 in which a cracking pressure is included in an annular leaf valve that is a damping valve.

  That is, this Patent Document 1 discloses that the piston body forming the piston portion is located on the end surface facing the pressure receiving surface of the annular leaf valve, and the height position of the top portion of the outer peripheral side seat portion is set on the inner peripheral side. It is supposed that it is formed at a so-called outer height that is made higher from the height position of the top portion of the boss portion toward the pressure receiving surface of the annular leaf valve.

Therefore, in the proposal disclosed in Patent Document 1, when finishing the end face of the piston body, the inner peripheral boss portion is precisely finished, and the outer peripheral side seat portion is raised, that is, the so-called outer height is finished. Thus, when fixing the inner peripheral side fixed portion of the annular leaf valve to the inner peripheral boss portion of the piston body by tightening the piston nut, the piston body is provided with cracking pressure in the outer peripheral side bending portion of the annular leaf valve. It becomes possible to be seated on the outer peripheral side seat portion.
Japanese Patent Application Laid-Open No. 2004-176775 (Claims 1, Detailed Explanation of the Invention, FIGS. 1, 2, Abstract)

  However, even in the proposal disclosed in Patent Document 1 described above, it is pointed out that when the annular leaf valve is composed of a large number of laminated bodies, it is difficult to provide the annular leaf valve with a predetermined cracking pressure. There is a possibility.

  That is, in the proposal disclosed in Patent Document 1 described above, the provision of the predetermined cracking pressure in the annular leaf valve largely depends on the elasticity of the annular leaf valve itself.

  Therefore, when the annular leaf valve is composed of a single body or a laminate of two or three sheets, it is easy to ensure elasticity. However, when the annular leaf valve is composed of a plurality of laminates, The rigidity of the valve is increased, so that it becomes difficult to provide the annular leaf valve with a predetermined cracking pressure.

  Therefore, when the piston portion as shown in FIG. 1 is formed, as shown in an exaggerated manner in FIGS. 2 and 3, it faces the back pressure surface of the annular leaf valve 4 made up of a large number of laminates via a shim 8. Proposed as a so-called external height on the end face of the piston nut 6 that increases the height position of the top portion 6a on the outer peripheral side toward the back pressure surface of the annular leaf valve 4 from the height position of the top portion 6b on the inner peripheral side. You will get none.

  In the case of this proposal, the annular leaf valve 4 is fixed by pressing the inner peripheral side fixing portion 4a of the annular leaf valve 4 against the inner peripheral side boss portion 3c of the piston body 3 by tightening the piston nut 6. 4, the outer peripheral side bending portion 4 b is pressed against the outer peripheral side seat portion 3 d of the piston body 3, and therefore the outer peripheral side bending portion 4 b of the annular leaf valve 4 can be provided with cracking pressure.

  At this time, the end surface of the piston nut 6 facing the back pressure surface of the annular leaf valve 4 needs to be finished to a so-called outer height and precisely so that the end surface of the piston nut 6 is formed after molding by pressing the punch against the piston nut 6. It is indispensable not to develop a so-called sagging turbulent surface on the inner peripheral top 6b.

  The present invention has been created in view of the above-described present situation, and the object of the present invention is to provide an end face that is in contact with the back pressure surface of the annular leaf valve when the piston nut is formed by pressing the punch. An object of the present invention is to provide a method for forming a piston nut which is optimal for providing a stable cracking pressure in an annular leaf valve provided adjacent to the end face of the piston body with this piston nut so as not to develop a turbulent surface.

  In order to achieve the above-described object, the structure of the piston nut molding method according to the present invention is basically as set forth in claim 1, wherein the proximal thread portion of the rod body that penetrates the shaft core portion of the piston body. Piston nut formed by pressing the punch nut with a piston nut that fixes the inner peripheral side fixed part of the annular leaf valve adjacent to the end face of the piston body to the inner peripheral boss part of the piston body when tightened In this molding method, the piston nut is located on the end surface facing the back pressure surface of the annular leaf valve, and the height position of the top portion on the outer peripheral side is higher than the height position of the top portion on the inner peripheral side toward the back pressure surface of the annular leaf valve. On the other hand, the punch presses the end surface of the piston nut facing the back pressure surface of the annular leaf valve, and the shaft core portion of the piston nut penetrates the base end of the rod body. That permeable outer peripheral surface is introduced into the hole with comprising a shaft portion which is opposed to the inner peripheral surface of the opening end of the through hole, and a flange portion and the shaft portion is formed by a continuous in punch.

  More specifically, in claim 2, it is assumed that the outer diameter of the flange portion of the punch is set larger than the outer diameter of the end surface of the piston nut that presses the flange portion.

  Therefore, according to the first aspect of the present invention, when the punch is pressed against the end face of the piston nut and molded, the piston nut is located on the end face facing the back pressure face of the annular leaf valve, and the height of the top portion on the outer peripheral side is increased. A flange portion that pushes the end face of the piston nut that faces the back pressure surface of the annular leaf valve while the height is set higher toward the back pressure surface of the annular leaf valve than the height position of the top portion on the inner peripheral side, and the piston A shaft portion facing the inner peripheral surface of the opening end portion of the through hole that is opened in the shaft core portion of the nut and penetrates the base end portion of the rod body, and the flange portion and the shaft portion are Since they are continuous, it is possible to prevent a turbulent surface from appearing on the end face of the piston nut that forms the open end of the through hole that is opened in the shaft core portion when the punch is pressed.

  And in invention of Claim 2, since the outer diameter of the flange part in a punch is set larger than the outer diameter of the end surface in the piston nut which presses this flange part, it is also on the outer peripheral side in the end surface of a piston nut. It becomes possible not to express a turbulent surface.

  As a result, according to the present invention, when the punch nut is pressed to form the piston nut, it becomes possible to prevent the end face contacting the back pressure surface of the annular leaf valve from appearing a turbulent surface. With this piston nut, it becomes possible to provide a stable cracking pressure to the annular leaf valve provided adjacent to the end face of the piston body.

  Hereinafter, the present invention will be described based on the illustrated embodiment. However, in the illustrated embodiment, the present invention is embodied in a piston nut that forms a piston portion in a hydraulic shock absorber.

  Accordingly, the piston portion in the hydraulic shock absorber will be described briefly with reference to FIG. 1 described above. The piston body 3 held by the base end portion 2a of the rod body 2 inserted in the cylinder body 1 so as to be able to appear and retract is a cylinder. While being slidably mounted on the body 1, an extension side oil chamber R1 that is a rod side oil chamber and a pressure side oil chamber R2 that is a piston side oil chamber are defined.

  Then, the piston body 3 is provided with an extension side damping valve 4 which is an annular leaf valve for releasably closing the downstream end of the opening extension side flow path 3a adjacent to the lower end face in the figure. Further, a back pressure valve 5 serving as an annular leaf valve for releasably closing the downstream end of the opening pressure side flow path 3b is provided adjacent to the upper end face in the drawing.

  At this time, the inner peripheral side fixing portion 4 a of the expansion side damping valve 4 is clamped between the inner peripheral side boss portion 3 c of the piston body 3 and the piston nut 6, and the inner periphery of the piston body 3 is tightened by tightening the piston nut 6. It is assumed that it is fixed to the side boss portion 3c, and the outer peripheral side bending portion 4b of the expansion side damping valve 4 is adjacent to the outer peripheral side seat portion 3d of the piston body 3 so as to be separable and separable.

  Then, the inner peripheral side fixing portion 5a of the back pressure valve 5 is clamped between the inner peripheral boss portion 3c of the piston body 3 and the valve stopper 7 and tightened with the piston nut 6 as described above, via the piston body 3. However, it is assumed that it is fixed to the inner peripheral side of the valve stopper 7, and the outer peripheral side bending portion 5 b of the back pressure valve 5 is adjacent to the outer peripheral side seat portion 3 d of the piston body 3 so as to be separable. It is going to be.

  The inner peripheral side fixing portion 4a of the extension side damping valve 4 is fixed to the inner peripheral side boss portion 3c of the piston body 3, and the inner peripheral side fixing portion 5a of the back pressure valve 5 is fixed to the valve stopper 7. The piston nut 6 is screwed into the proximal thread portion 2 b of the rod body 2.

  By the way, when the piston nut 6 is tightened in a state where the piston nut 6 is screwed to the proximal end thread portion 2 b of the rod body 2, the inner peripheral side of the piston body 3 interposed in the proximal end portion 2 a of the rod body 2. The boss portion 3c functions to fix the inner peripheral side fixing portion 4a of the expansion side damping valve 4, but at this time, the present invention also has the following effects.

  That is, first, the above-described piston nut 6 shown in FIG. 1 is integrally formed with a valve stopper facing the back pressure surface of the expansion-side damping valve 4. This can be said to be embodied in the valve stopper portion described above.

  However, after all, it can be said that it is embodied in the piston nut 6, so in the following description, only the piston nut 6 is deliberately expressed.

As described above, the piston nut 6 having the valve stopper integrally is formed in a form adjacent to the shim 8 adjacent to the back pressure surface of the extension side damping valve 4 which is a laminated body. 8 to face the back pressure surface of the laminate.

  Then, when observed more closely, as shown exaggeratedly in FIG. 2 and FIG. 3, the piston nut 6 is compared with the height position of the top portion 6a on the outer peripheral side compared with the height position of the top portion 6b on the inner peripheral side. It is assumed that the nut 6 is formed higher toward the back pressure surface of the extension side damping valve 4 facing the nut 6.

  At this time, as shown in FIG. 2 and FIG. 3, the outer peripheral side apex portion 6 a and the inner peripheral side apex portion 6 b are assumed to be continuous with a so-called inwardly inclined surface (not shown). It is sufficient that the outer peripheral side top 6a is formed to be higher than the inner peripheral side top 6b, that is, so-called outer height.

  The height difference between the top portions 6b and 6a in the case of the so-called outer height is not limited to the millimeter unit, but is in the micron unit region. May be selected, but in many cases will be due to pressing of the punch.

  From this point of view, instead of the inner and outer apexes 6b and 6a being continuous with an inclined surface, the outer peripheral apex 6a is formed with a flat surface, but the inclined surface is continuous with this. Also, although not shown in the figure, it may be possible to have a step on the outer peripheral top 6a made of a flat surface and continue to the inner peripheral top 6b on the flat surface. Any shape may be selected as long as it is formed as a so-called outer height.

  As described above, the surface of the piston nut 6 that faces the back pressure surface of the expansion-side damping valve 4 is formed at a so-called outer height, so that the piston nut 6 is screwed into the proximal thread portion 2b of the rod body 2. When tightened in a closed state, the outer peripheral side bending portion 4b of the extension side damping valve 4 is forcibly fixed while fixing the inner peripheral side fixing portion 4a of the extension side damping valve 4 to the inner peripheral side boss portion 3c of the piston body 3. That is, it is possible to make the outer peripheral side bending portion 4b of the extension side damping valve 4 have a cracking pressure.

  Accordingly, in the piston nut 6, as shown in FIG. 4, when the end surface adjacent to the back pressure surface of the annular leaf valve 4 is formed by pressing the punch P, the end surface is disturbed. It is important not to express.

  Therefore, in the present invention, as shown in the drawing, the punch P is opened to the rod body by being pierced by the flange portion P1 that is in contact with and pressing the end surface of the piston nut 6 and the shaft core portion of the piston nut 6. 2 has a shaft portion P2 which is introduced into the through hole 6c penetrating through the base end portion 2a and faces the inner peripheral surface of the opening end portion of the through hole 6c, and the flange portion P1. The shaft portion P2 is assumed to be continuous in the punch P.

  At this time, no gap is formed between the flange portion P1 of the punch P and the end surface of the piston nut 6, but the shaft portion P2 is projected and retracted with respect to the through hole 6c. It is assumed that there is a gap as indicated by a symbol d in the figure between the inner peripheral surface of the hole 6c.

  As a result, after the punch P is removed, as shown in FIG. 5, a turbulent surface 6d called a sag is developed on the inner peripheral surface of the opening end of the through hole 6c. Since the turbulent surface 6d on the inner peripheral surface of the annular leaf valve 4 is not adjacent to the back pressure surface of the annular leaf valve 4, the presence of cracking pressure in the annular leaf valve 4 is not affected.

  On the other hand, the punch shown in FIG. 6 has a punch P having a flange portion P1, and a shaft-shaped guide G which is formed separately from the punch P and corresponds to the shaft portion P2 in the punch P shown in FIG. In other words, the conventional punch shape is used. In the case of this conventional punch, after removing the punch P and the shaft-shaped guide G, a gap d is formed between the punch P and the shaft-shaped guide G. Therefore, as shown in FIG. 7, in the piston nut 6, a turbulent surface 6 d called “sag” appears on the inner peripheral surface of the opening end portion of the through hole 6 c, and a turbulent surface called “sag” also on the end surface. 6e will be expressed.

  Since the turbulent surface 6e at the end face is adjacent to the back pressure surface of the annular leaf valve 4, the presence of the cracking pressure in the annular leaf valve 4 is affected, and a stable cracking pressure is obtained. It will impede nature.

  In view of the above, in the punch P shown in FIG. 4 used for realizing the present invention, the piston adjacent to the back pressure surface of the annular leaf valve 4 through the end face of the piston nut 6, that is, the shim 8. Since it is possible to avoid the occurrence of the turbulent surface 6e on the end surface of the nut 6, it becomes possible to provide the annular leaf valve 4 with a stable cracking pressure by tightening the piston nut 6, and there is a setting in the piston portion. The generation of damping force can be realized.

It is a longitudinal cross-sectional view which shows the piston part in the cylinder body which has the piston nut shape | molded with the shaping | molding method of the piston nut by this invention. FIG. 2 is an enlarged partial vertical sectional view showing a part of a piston nut in FIG. FIG. 2 is a partial vertical cross-sectional view showing a state in which the end face of the piston nut is formed at an outer height further enlarged from the state of FIG. 1. It is a figure which shows the place which actualizes the shaping | molding method of the piston nut by this invention, embodying the state shown in FIG. FIG. 4 is an enlarged view showing an end face of a piston nut formed by the piston nut forming method in FIG. 4. It is a figure which shows the state which embodied the shaping | molding method of the piston nut using the conventional punch similarly to FIG. FIG. 6 is a view showing an end face of a piston nut formed by the piston nut forming method in the same manner as FIG. 5.

Explanation of symbols

2 Rod body 2b Base end thread portion 3 Piston body 3c Inner peripheral side boss portion 4 Annular leaf valve 4a Inner peripheral side fixing portion 6 Piston nut 6a, 6b Top portion 6c Through hole P Punch P1 Flange portion P2 Shaft portion

Claims (2)

The inner peripheral boss of the piston body is fixed to the inner peripheral side fixing portion of the annular leaf valve that is adjacent to the end face of the piston body when tightened by screwing with the proximal end threaded portion of the rod body that penetrates the shaft core portion of the piston body. In a method for forming a piston nut, which is formed by pressing a piston nut to be fixed to a part by pressing a punch, the piston nut is located on the end surface facing the back pressure surface of the annular leaf valve, and the height of the top on the outer peripheral side is set to the inner peripheral side. The height of the top of the annular leaf valve is increased toward the back pressure surface of the annular leaf valve, while the punch presses the end face of the piston nut facing the back pressure surface of the annular leaf valve, and the shaft core portion of the piston nut. And a shaft portion that is introduced into a through hole that is opened and penetrates the proximal end portion of the rod body and has an outer peripheral surface facing the inner peripheral surface of the open end portion of the through hole. Molding process of the piston nut, characterized in that the di portion and the shaft portion is formed by continuously The method for molding a piston nut according to claim 1, wherein the outer diameter of the flange portion of the punch is set larger than the outer diameter of the end surface of the piston nut that presses the flange portion.

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