JP4256202B2 - Piston molding method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for forming a piston used in a hydraulic cylinder or a hydraulic shock absorber.
[0002]
[Prior art]
In general, a hydraulic cylinder or a hydraulic shock absorber has a piston rod movably inserted into the cylinder via a piston, and the piston includes a piston body and a synthetic resin ring fitted to the outer periphery of the piston body. The piston is in sliding contact with the inner periphery of the cylinder via the ring.
[0003]
And as a piston used for this kind of hydraulic cylinder and a hydraulic shock absorber, there is a proposal indicated by patent documents 1, for example.
[0004]
As shown in FIG. 7, the piston P disclosed in this document includes a piston main body 1 coupled to the piston rod 3 and a synthetic resin ring 6 fitted to the outer periphery of the piston main body 1. A plurality of annular grooves 1a and a plurality of lands 1b are formed on the outer periphery along the axial direction, and the ring 6 is formed on the ring body 6a along the outer periphery of the piston body 1 and on the inner periphery side of the ring body 6a. A plurality of inner circumferential annular projections 6c fitted in the respective annular grooves 1a, bent portions 6b and 6f formed at both ends of the ring body 6a, and formed on the outer periphery of the bent portions 6b and 6f. The protrusions 6d and 6g are configured such that when the piston is inserted into the cylinder, the protrusions 6d and 6g come into contact with the inner periphery of the cylinder.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-276808 (FIG. 3)
[0006]
[Problems to be solved by the invention]
In the conventional piston P, since the ring 6 includes the convex portions 6d and 6g, when the piston P slides, the convex portions 6d and 6g prevent fluid such as oil from leaking between the piston and the cylinder. Although it has an advantageous point to prevent, the step of forming the bent portions 6b and 6f and the convex portions 6d and 6g after the ring main body 6a is thermocompression bonded to the piston main body 1 through a die when the ring is formed. As a result, the molding process of the entire ring 6 is complicated and the cost increases.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide a piston molding method in which the piston molding process is simple and the processing cost can be reduced.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, one means of a piston molding method according to the present invention is a ring mother formed in a disc shape on the outer periphery of a piston body having a plurality of lands intermittently formed along the axial direction on the outer periphery. Suppose that the ring body is placed along the outer periphery of the piston body by pressing and pressing the material, and the lip is formed by turning one end portion of the outer periphery of the ring base material outward. One means, while making the outer peripheral surface of the land in the piston body along the other end portion of the ring base material the inner peripheral side portion is a conical inclined surface or concave surface that raises a gradient toward the end direction, Pressing and pressing the ring base material onto the outer periphery of the piston body with a die, and forming the ring body along the outer periphery of the land by heating and softening the ring base material during the pressing and pressing step When, and comprising a step of forming a lip of the ring body in crimping roller return sled outward the other end while caulking pressurized to the inclined surface or concave.
[0009]
Then, the other means pressurizes and presses the ring base material formed in a disk shape on the outer periphery of the piston main body having a plurality of lands and annular grooves intermittently formed along the axial direction on the outer periphery, and softens it by heating. In the piston molding method in which the ring main body is placed along the outer periphery of the piston main body and one end formed of the outer peripheral side portion of the ring base material is turned outward to form a lip, the inner peripheral side of the ring base material Forming the top peak width of the land in the piston body along the other end of the portion smaller than the peak width of the other intermediate land while pressing the ring base material against the outer periphery of the piston main body with a die When caulking with a step of forming a ring body along the ring substrate during the pressing pushing step is heated and softened on the outer periphery of the land, an annular protrusion on the inner peripheral side b The ring body La and and a step of forming a lip return sled outward the other end while caulking pressurized in the annular groove adjacent to the land and land to reduce the top Yamahaba.
[0010]
And in each of the above methods, one or a plurality of annular chevron projections are formed on the inner periphery of the caulking roller, and the outer surface of the other end portion consisting of the inner peripheral side portion of the ring base material is pressed when the caulking roller is pressed. It may be provided with a step of forming one or a plurality of annular protrusions on the outer periphery of the lip by pressing with the chevron.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 to FIG. 6 show embodiments of a piston and a molding method thereof according to the present invention.
[0012]
The basic structure of the piston P in each embodiment is composed of a piston main body 1 and a ring 6 fitted to the outer periphery of the piston main body 1 as in the prior art shown in FIG. The ring 6 includes a plurality of lands 1b and a plurality of annular grooves 1a formed alternately along the axial direction on the outer periphery, and the ring 6 presses the outer periphery of the piston body 1 with a ring base material formed in a synthetic resin disk shape. The ring main body 6a is formed along the outer periphery of the land 1b formed by heating and softening while being pushed in, and the inner peripheral side annular protrusion 6c that flows and fits in each of the annular grooves 1a.
[0013]
In the piston P shown in FIGS. 1 to 3 and 4, in the piston body 1, the outer periphery of the land 1 b in the piston body 1 along the other end 6 b on the right side in the drawing consisting of the inner periphery side portion of the ring base material. The surface is configured as a conical inclined surface that rises in the direction of the end portion, and the ring body 6a is pressed against the inclined surface and caulked to turn the other end portion 6b outward so that the lip B Formed.
[0014]
The molding of the piston P shown in FIG. 1 to FIG. 3 and FIG. 4 is configured as a conical inclined surface A in which the outer peripheral surface of one end land 1b, which is the right end in each drawing, rises toward the end. In this state, a ring base material formed into a disc shape made of a synthetic resin is pressed against the outer periphery of the piston main body 1 with a die in the same manner as in the prior art, and the ring base material is heated and softened during the pressurizing step to thereby each land. A ring body 6a is formed along the outer periphery of 1b and is caused to flow into the annular grooves 1a to form an inner annular protrusion 6c (see FIG. 1).
[0015]
Next, in the present invention, the ring body 6a, that is, the other end portion 6b consisting of the inner peripheral side end portion of the ring base material is outwardly pushed while the ring body 6a is pressed against the inclined surface A by the caulking roller 10. FIG. 2 shows a state in which the other end 6b before caulking with the caulking roller 10 is not bent, and FIG. 3 shows caulking with the caulking roller 10 to form the other end 6b. Indicates the state of turning over.
[0016]
In the embodiment shown in FIGS. 1 to 4, the inclined surface A is provided only at the right end in each figure, but instead, it may be provided at both ends, although not shown.
However, the lip B on the left side of the ring body 6a in each figure can be formed without providing the inclined surface A.
[0017]
That is, as described above, when the ring base material formed into a disk shape with a die is pressed as in the conventional case and the die is removed, one end on the left side of the ring main body 6a composed of the outer peripheral side portion of the ring base material is shown. Since the lip B is formed by automatically deflecting the portion outward by the restoring force, the left land portion 1b can be used without providing the inclined surface A.
[0018]
The caulking roller 10 has a main body 10a, a curved guide surface 10b, and an annular protrusion 10c. Accordingly, the ring main body 6a on the inclined surface A or in the vicinity of the inclined surface A can be pressed by the protrusion 10c. By crimping, the other end portion 6b of the ring body 6a is bent outwardly while being guided by the guide surface 10b along the inclined surface A, so that the lip B is formed.
[0019]
The piston shown in FIG. 4 has the basic structure described above and one or a plurality of annular convex portions 12 formed on the outer periphery of the lip B.
[0020]
In this case, another annular chevron protrusion 10d is formed on the inner periphery of the pressure roller 10, and when the pressure roller 10 is caulked, the annular protrusion 10d presses the outer periphery of the lip B, and the annular chevron protrusion 10 An annular recess 11 is formed at a portion corresponding to 10d, and protrusions 12 are formed on both sides of the recess 11.
[0021]
The convex portion 12 is in sliding contact with the inner periphery of the cylinder when the piston P is inserted into the cylinder, and prevents oil leakage more effectively.
[0022]
FIG. 5 shows another embodiment according to the present invention, in which the outer peripheral surface of the land 1b at one end or both ends is configured as an annular concave surface C, and the ring body 6a is pressurized and caulked to the concave surface C. As a result, the end of the ring body 6a is bent outward to form the lip B.
[0023]
In this embodiment, a concave surface C is formed instead of the inclined surface A of FIG. 1, and the molding method and other structures, functions, and effects are the same as those of the embodiment of FIG.
[0024]
FIG. 6 shows another embodiment according to the present invention, and this piston P is obtained by deforming an end land.
[0025]
That is, in this embodiment, the top width of the land 1B at one end or both ends is formed smaller than the top width of the other intermediate land 1b, and the ring body is placed in the annular groove 1a adjacent to the land 1B at one end or both ends. By pressing and crimping 6a, the end of the ring body 6a is turned outward to form the lip B, and the land 1B may be provided only on the right side as shown.
[0026]
The piston according to this embodiment is formed in such a manner that the top width of the land 1B at one end or both ends is made smaller than the top width of the other intermediate land 1b, and in this state, a disc made of synthetic resin is used as in the prior art. The ring base material formed in a shape is pressed against the outer periphery of the piston main body 1 by a die, and the ring base material is heated and softened during the pressurizing step to form the ring main body 6a along the outer periphery of the land, and the annular grooves 1a. An inner peripheral annular projection 6c that is allowed to flow in is formed.
[0027]
Next, in the present invention, the ring body 6a is pressed and caulked in the annular groove 1a adjacent to the land 1B at one end or both ends by the caulking roller 10 to turn the end of the ring body 6a outward and lip. B is formed, and other structures, functions, and effects are the same as those in the above embodiments.
[0028]
【The invention's effect】
The present invention has the following effects.
[0029]
1) According to the invention of each claim, in the piston, the piston main body is formed with the outer peripheral surface of the land at one end or both ends as an inclined surface or a concave surface, or formed smaller than the width of the other land. When the ring body is pressurized and caulked, the end of the ring body is deflected automatically by caulking and a lip is formed, making the entire ring and then the entire piston forming process easy. Reduce costs.
[0030]
2) The lip at the end of the ring body is in sliding contact with the inner periphery of the cylinder when the piston is inserted into the cylinder, and oil leakage in the cylinder can be effectively prevented.
[0031]
3) Since the lip is formed in the ring body corresponding to the shape of the land at one end or both ends of the piston body, the design freedom of the lip shape and angle is improved, the friction is increased and decreased, and the amount of oil leakage is large and small. It can respond to various requests.
[Brief description of the drawings]
FIG. 1 is a sectional view of an initial stage of a piston forming process according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a secondary process of the piston molding process.
FIG. 3 is a sectional view of the piston showing the final process.
FIG. 4 is a cross-sectional view of a piston according to another embodiment of the present invention.
FIG. 5 is a sectional view of a piston according to another embodiment of the piston molding method of the present invention.
FIG. 6 is a cross-sectional view of a piston according to another embodiment of the piston molding method of the present invention.
FIG. 7 is a sectional view of a conventional piston.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Piston main body 1a Annular groove 1b Land 10 Pressure roller A Inclined surface B Lip C Concave surface

Claims (3)

  A ring base material formed in the shape of a disk is pressed against the outer periphery of the piston body having a plurality of lands intermittently formed along the axial direction on the outer periphery, and is softened by heating and pushing the ring body along the outer periphery of the piston body. In the piston molding method in which one end portion formed from the outer peripheral side portion of the ring base material is bent outward to form a lip, in the piston main body along the other end portion formed from the inner peripheral side portion of the ring base material While the outer peripheral surface of the land is formed into a conical inclined surface or concave surface that rises in the direction of the edge, the ring base material is pressed against the outer periphery of the piston body with a die, and this pressurization is performed. During the process, the ring base material is heated and softened to form a ring main body along the outer periphery of the land, and the ring main body is pressed against the inclined surface or concave surface with a caulking roller. While the molding method of the piston, characterized in that it consists of a step of forming a lip return sled the other end outward. A ring base formed in a disk shape is pressed against the outer periphery of a piston body having a plurality of lands and annular grooves intermittently formed along the axial direction on the outer periphery, and the ring base is formed on the outer periphery of the piston body by pressing and pushing the disk base material. And forming the lip by turning one end portion formed on the outer peripheral side portion of the ring base material outward, and the other end portion formed on the inner peripheral side portion of the ring base material is A step of pressing the ring base material against the outer periphery of the piston main body with a die while pressing the top peak width of the land in the piston body smaller than that of the other intermediate land, and the pressure pressing step on a step by heating and softening a ring substrate forming a ring body along the outer periphery of the land, in the caulking roller ring body on the inner peripheral side with an annular protrusion in Piston molding method, characterized in that pressurized to an annular groove adjacent to the land and land to reduce the top Yamahaba in and a step of forming a lip return sled the other end outward while staking .   One or a plurality of annular chevron protrusions are formed on the inner periphery of the caulking roller, and the outer surface of the other end portion consisting of the inner peripheral side portion of the ring base material is pressed by the chevron protrusion when the caulking roller is pressed, The method for forming a piston according to claim 1, further comprising a step of forming one or more annular protrusions on the outer periphery.

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