JP3196282B2 - Pipe end closure molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a pipe end block used for forming a bottom portion of an outer cylinder (reservoir tube) in a hydraulic shock absorber for an automobile, for example.

[0002]

2. Description of the Related Art In general, in a vehicle suspension hydraulic shock absorber, as shown in FIG.
The bottom of 3 is closed by a substantially hemispherical closing surface 13a. An inner cylinder 14 is disposed inside the outer cylinder 13, and a bottom body 15 attached to the lower end of the inner cylinder 14 is provided on a projection 11 formed on a closed surface 13 a at the bottom of the outer cylinder. While being seated, the lower end of the outer cylinder 13 and the lower end of the inner cylinder 14 are held concentrically, and the upper end of the outer cylinder 13 and the upper end of the inner cylinder 14 are mounted on them. Are concentrically connected via a rod guide 16.

A reservoir chamber 17 is formed between the outer cylinder 13 and the inner cylinder 14, and an upper cylinder chamber 18 is formed inside the inner cylinder 14.
A and a piston 19 partitioned into a lower cylinder chamber 18B are slidably fitted. And the piston rod 20
Is attached to a vehicle body (not shown) via a screw portion 20a formed at the upper end thereof, and is slidably held by the rod guide 16 and extends vertically. The piston 19 is fixed.

A spring (not shown) is contracted between a lower retainer 21 mounted on the outside of the outer cylinder 13 and an upper retainer (not shown) provided on the piston rod 20. Further, the piston 19 is provided with a valve 22 for regulating the flow of the buffer oil from the lower cylinder chamber 18B to the upper cylinder chamber 18A, and the bottom body 15 is provided with a reservoir chamber 17 and an inner cylinder 14
A bottom valve 23 for regulating the flow of the buffer solution between the inside and the inside is provided. Further, between the rod guide 16 and a cover 24 covering the rod guide 16 and closing the upper end of the outer cylinder 13, a buffer solution from the upper cylinder chamber 18 </ b> A of the inner cylinder 14 to the reservoir chamber 17. A one-way valve 25 is provided that permits the recirculation of compressed gas but does not permit the flow of compressed gas in the reverse direction.

Conventionally, a hydraulic shock absorber for a suspension of a motorcycle or the like is disclosed in Japanese Patent Application Laid-Open No. 59-125221 as a pipe end block forming method for integrally forming a block surface at the bottom of an outer cylinder with an outer cylinder. The disclosed technology is disclosed.

Therefore, as shown in FIG. 5, the hydraulic shock absorber for suspension of a four-wheeled vehicle also has its axial line and the end 13b of the outer cylinder 13 fixed in the same manner as in the above-mentioned pipe end block forming method. The friction roller 6 and the forced drive roller 5 are pressed at a right angle, and the end roller 13b of the outer cylinder 13 is rotated about the axis by the rotation of the forced drive roller 5, and the friction roller 6 is moved to the arc-shaped guide rail 7. A pipe end closing forming method of forming the end portion 13b of the outer cylinder 13 into a hemispherical closing surface portion 13a by spinning and moving the outer cylinder cylinder 13 while rotating the cylinder cylinder 13 along the direction is considered.

[0007] In addition, in these automobile suspension hydraulic shock absorbers, due to the structure described above, the closing surface portion 1 is not provided.
It is necessary to form the projection 11 for seating the bottom body on the inner surface of the projection 3a. In this case, as shown in FIG. 6, the closing surface 13a of the outer cylinder 13 is set on the projection molding die 9 and the projection molding die 9 is formed. There is a method of forming the projection 11 by the punch 10 of FIG.

[0008]

However, in the above-described method, when the projections 11 are formed, there is a possibility that a minute gap may be formed at the tip contact portion of the closing surface portion 13a. In this case, complete airtightness of the closing surface portion 13a is required. Repair by welding etc. is necessary to secure. In particular, the plate thickness of the outer cylinder 13 is thicker in terms of strength, and the plate thickness of the closed surface portion 13a is usually about three times the plate thickness of the outer cylinder 13 by molding by spinning. large.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a projection even in the case of a thick tube, such as an outer cylinder of an automobile suspension hydraulic shock absorber. It is an object of the present invention to provide a tube end block forming method capable of forming a closed block portion in which the closed block portion is completely airtightly maintained integrally with the pipe.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a method of forming a closed surface by spinning an end of a tubular body, and then pressing a contact portion of the closed end with a pressure punch. A protrusion is formed on the inner surface of the closed surface by a forming punch while pressing in the axial direction of the tubular body.

[0011]

According to this method, the deformation of the protrusion by the forming punch at the time of forming the protrusion is suppressed by the pressing of the pressing punch.
A fine defect does not occur at the tip contact portion of the closed surface formed by the spinning process. Therefore, complete airtightness of the closed surface can be ensured.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing a spinning step of a closed surface portion, and FIGS. 2 and 3 are illustrations showing a step of forming a projection.

First, as shown in FIG.
a, the forced drive roller 5 is pressed at right angles to the axis thereof, and the rotation of the forced drive roller 5 causes the end 1a of the tubular body 1 to rotate at high speed about the axis while the friction roller 6 is rotated.
Is pressed against the end 1a of the tubular body 1 at right angles to the axis thereof, and the end 1a is moved along the arc-shaped guide rail 7.
Move gradually toward the tip of.

By this spinning, the end 1a of the tube 1 is deformed, and at the same time, heat is generated by the friction between the end 1a of the tube 1 rotating at high speed and the friction roller 6. Then, the friction roller 6 is moved along the arcuate guide rail 7 to the end 1.
As it moves toward the tip of the end portion a, the thickness of the end portion 1a gradually increases from the tube side to the tip side, and at the tip contact portion 2a, the thickness is approximately three times the thickness of the tube 1 and is crimped. The closed surface portion 2 is formed in a shape.

Next, as shown in FIG. 2, the closed surface 2 of the tubular body 1 is set on a die 9 for forming a projection, and the pressure-contact punch 8 is used to connect the tip contact portion 2a of the closed surface 2 to the axis of the tubular body 1. While maintaining the pressurized state, the forming punch 10 is pressurized to form a projection 11 on the inner surface of the closed surface portion 2 as shown in FIG. Thereafter, the pressing force of the forming punch 10 is removed while the pressing punch 8 is kept in a pressing state, and the pressing force of the pressing punch 8 is removed slightly later than this.

[0016] According to the pipe end closing molding method as described above,
The closed surface 2 is formed integrally with the tube 1 at the end 1a of the tube 1 by spinning, and then the projections 11 are formed on the inner surface of the closed surface 2 by the pressing of the die 9, the press punch 8 and the forming punch 10. It is formed. At this time, the minute deformation of the tip contact portion 2a of the closing surface portion 2 caused by the forming punch 10
Since the pressure is suppressed by the pressing of the pressure punch 8, fine defects due to molding do not occur in the tip contact portion 2a of the closing surface portion 2, and complete airtightness of the closing surface portion 2 can be secured. Therefore, repair by welding or the like is unnecessary, and no extra man-hour is required.

[0017]

As described above, according to the present invention, after a closed surface is formed by spinning at the end of a tubular body, the contact portion at the tip of the closed surface is pressed in the axial direction of the tubular body by a pressure punch. Meanwhile, since the projections are formed on the inner surface of the closed surface portion by the forming punch, the deformation at the time of forming the protrusions by the forming punch is suppressed by the pressing of the pressure punch, so that the closed surface portion formed by the spinning process is formed. A fine defect is not generated in the contact portion at the tip end, and therefore, an excellent pipe end closing molding method capable of ensuring complete airtightness of the closed surface portion can be realized.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a step of spinning a closed surface portion according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a processing step before forming a projection of the closed surface portion.

FIG. 3 is an explanatory view showing a processing step after the projection of the closed surface is formed.

FIG. 4 is a partial cross-sectional view of a suspension hydraulic shock absorber of an automobile.

FIG. 5 is an explanatory view showing a conventional spinning process of a closed surface portion.

FIG. 6 is an explanatory view showing a processing step at the time of forming a projection of the closed surface portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tube 1a End part 2 Closed surface part 2a Tip contact part 5 Forced drive roller 6 Friction roller 8 Pressure punch 9 Die 10 Molding punch 11 Projection

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B21D 41/04 B21D 22/02 B21D 53/86-53/88 B60G 13/08 F16F 9/32

Claims (1)

(57) [Claims] After forming a closed surface portion by spinning at an end of a tubular body, the closed surface portion is formed by a forming punch while pressing a tip contact portion of the closed surface portion in an axial direction of the tubular body by a pressing punch. Forming a projection on the inner surface of the tube.