JP5229618B2 - Shock absorber and method of manufacturing the shock absorber - Google Patents

Description

  The present invention relates to a shock absorber that constitutes a suspension of a vehicle, in particular, a single cylinder shock absorber, and a method of manufacturing the single cylinder shock absorber.

  Conventionally, one of the shock absorbers constituting the suspension of a vehicle has a rod that holds a piston valve that allows oil to flow at one end, and a piston valve that holds the rod including the rod inside, and an input load. There is a single-cylinder shock absorber composed of a cylinder that accommodates oil and high-pressure air that are damped while being separated by a free piston. In the single-cylinder shock absorber, the cylinder body and the vehicle body mounting part are integrated with each other from the structural necessity such as disposing a free piston for separating and accommodating oil and high-pressure air in the cylinder. The cylinder cap is formed, and both are integrally formed by a joint portion formed by screwing the male screw portion of the cylinder cap and the female screw portion of the cylinder body.

Special table 2000-507666

However, when the cylinder of the single-cylinder shock absorber is configured integrally, if the joint is formed by screwing between the male threaded portion of the cylinder cap and the female threaded portion of the cylinder body, the oil contained in the cylinder or Since it is necessary to prevent leakage of high-pressure air, it is necessary to precisely screw a male screw portion and a female screw portion that are screwed together at the joint portion. As a result, the efficiency of the part manufacturing operation is reduced, and the manufacturing cost may be increased.
In addition, if foreign matter is bitten at a joint where the male threaded portion of the cylinder cap and the female threaded portion of the cylinder body are threaded together, the precise threaded engagement between the male threaded portion and the female threaded portion is impaired. There is a possibility that oil or high-pressure air stored while being separated in the cylinder may leak.

  For this reason, it has also been proposed to melt and bond a joint portion between a cylinder cap and a cylinder body that integrally constitute the cylinder of the single-cylinder shock absorber. However, it is difficult to completely join the joining surfaces of the cylinder cap and the cylinder body when performing melt joining from the outside of the joint. As a result, the airtightness at the joint is lowered and sufficient strength cannot be ensured. In addition, when melt-bonding, the joint is thermally deformed, and if a large input load is applied to the cylinder, the cylinder may be damaged such as buckling or breaking.

  Therefore, it has been proposed that the joint between the cylinder cap and the cylinder main body, which integrally constitute the cylinder constituting the single cylinder type shock absorber, is friction-welded.

  As a result, at the joint between the cylinder cap and the cylinder body, the joint surface of the cylinder cap and the cylinder body is joined over the entire surface, and in the friction welding, heat is generated only at the joint surface and plastic flow does not occur, so thermal deformation occurs. There are few, and a high intensity | strength junction part is obtained.

However, when the cylinder cap and the cylinder body are friction-welded at the joint with the cylinder, an outer burr or an inner burr is formed so as to protrude outward or inward on the outer wall surface or inner wall surface of the joint portion, respectively. It will be a thing.
At this time, the outer surface burr formed on the outer wall surface of the cylinder can be easily shaped, but it is difficult to completely shape the inner surface burr formed on the inner wall surface of the cylinder.
As a result, internal burrs that cannot be shaped are peeled off due to vibration, etc., and if the peeled internal burrs enter the free piston that can slide in the cylinder, the inner wall of the cylinder and the free piston will be damaged. The separation of oil and high-pressure air by the free piston is impaired, and the input load may be attenuated.

  Therefore, the present invention obtains a high-strength joint without deformation by joining the cylinder cap and the cylinder main body, which integrally constitutes the cylinder, by friction welding, and the inner surface formed by the friction welding. It prevents damage to the inner wall surface of the free piston or cylinder caused by burrs, and allows oil or high-pressure air to be separated by the free piston so that attenuation of the input load can be maintained over a long period of time.

In order to solve the above-mentioned problem, as a first feature, a rod that is slidable and that holds a disc-like piston valve that allows oil to flow at one end thereof, and the rod including the rod at one end thereof It is composed of a cylindrical cylinder that accommodates oil and high-pressure air while being separated by a piston-like free piston that is slidable together with a piston valve that is fixed,
The cylinder is composed of a cylinder main body integrated with each other by friction welding and a cylinder cap integrally forming a vehicle body mounting portion.
Forming a hollow inverted frustoconical rib having an opening on the inner bottom surface of the cylinder cap;
An inner surface burr formed so as to protrude from the inner wall surface of the joint portion of the cylinder by friction welding the cylinder body and the cylinder cap is the inner wall surface of the cylinder body, the inner wall surface and the inner bottom surface of the cylinder cap, and the cylinder what der made located in a space formed by the ribs of the inverted truncated cone shape formed on the inner bottom surface of the cap,
X, the distance from the inner bottom surface of the cylinder cap to the virtual equal division position between the inner surface burr on the cylinder body side and the inner surface burr on the cylinder cap side,
The maximum thickness of the internal burr on the cylinder body side is y,
The maximum amount of protrusion from the inner wall of the cylinder body of the inner surface burr on the cylinder body side is z,
The distance from the inner bottom surface of the cylinder cap to the closest approach position of the hollow inverted frustoconical rib having an opening with respect to the inner wall surface of the cylinder body is a,
The distance between the inner wall surface of the cylinder body and the hollow inverted frustoconical rib having an opening is b,
And when the maximum distance to the hollow rib having the inner wall surface of the cylinder cap and the opening on the inner bottom surface of the cylinder cap is c,
0 <a ≦ 50 (mm)
0 ≦ b ≦ 10 (mm)
0.5 <c ≦ 50 (mm)
And (x + y) / (c−z) ≧ a / (c−b)
It satisfies the relationship.

  As described above, the inner surface burrs formed on the inner wall surface of the cylinder by friction welding the cylinder cap and the cylinder body at the joint portion of the cylinder are the inner wall surface of the cylinder body, the inner wall surface and the inner bottom surface of the cylinder cap. And a space formed by a hollow inverted frustoconical rib having an opening formed on the inner bottom surface of the cylinder cap, the inner surface burr is peeled off from the inner wall surface of the cylinder due to vibration or the like. However, it does not stay in the space and advance to the free piston side. As a result, the inner surface burr does not damage the free piston or the inner wall surface of the cylinder, the airtightness of the free piston is sufficiently maintained, and the oil and the high-pressure air are separated.

  In addition, in particular, the inner burr formed at the joint between the cylinder cap and the cylinder body that integrally form the cylinder and the inverted frustoconical rib formed on the inner bottom surface of the cylinder cap satisfy the above predetermined relationship. The inner surface burr is reliably positioned in the space formed by the inner wall surface of the cylinder body, the inner wall surface and inner bottom surface of the cylinder cap, and the inverted frustoconical rib formed on the inner bottom surface of the cylinder cap. It can be made to be.

  Here, when the distance b between the inner wall surface of the cylinder body and the inverted frustoconical rib formed on the inner bottom surface of the cylinder cap is 0 (mm), the rib comes into full contact with the inner wall surface of the cylinder. . As a result, even if the inner surface burr is peeled off due to vibration or the like and finely pulverized, it is possible to sufficiently prevent the advancing to the free piston side. On the other hand, if b = 10 mm or less at the maximum, even if the inner surface burr tries to advance toward the free piston side, the inner surface burr of a fatal size that damages the inner wall surface of the free piston or cylinder will advance. Can be sufficiently prevented.

As a second feature, the shock absorber according to the present invention is slidable, and includes a rod that holds a disc-like piston valve that allows oil to flow at one end thereof, and includes the rod in the inside thereof. It is composed of a cylinder that accommodates oil and high-pressure air while being separated by a disc-shaped free piston that is slidable, together with a piston valve that is firmly held at one end,
A cylindrical cylinder body and a body mounting part are integrally formed at one end, and a cylinder cap that forms a cylindrical rib on the inner bottom is integrally friction welded to form the cylinder,
Inside the cylinder, a hollow having an opening by inserting and pressing a cone having a reverse taper surface that is reduced in diameter toward the tip of a cylindrical rib formed on the inner bottom surface of the cylinder cap. Transformed into a frustoconical rib,
An inner surface burr formed so as to protrude from the inner wall surface of the joint portion of the cylinder by friction welding the cylinder body and the cylinder cap, the inner wall surface of the cylinder body, the inner bottom surface of the cylinder cap, and the cylinder cap It is located in a space formed by an inverted frustoconical rib formed on the inner bottom surface.

As a third feature, based on the second feature, the inner wall surface of the cylinder body, the inner wall surface and the inner bottom surface of the cylinder cap, and the inverted frustoconical rib formed on the inner bottom surface of the cylinder cap In the space to be formed, when the inner surface burr formed so as to protrude on the inner wall surface of the joint portion of the cylinder by friction welding the cylinder body and the cylinder cap,
X, the distance from the inner bottom surface of the cylinder cap to the virtual equal division position between the inner surface burr on the cylinder body side and the inner surface burr on the cylinder cap side,
The maximum thickness of the internal burr on the cylinder body side is y,
The maximum amount of protrusion from the inner wall of the cylinder body of the inner surface burr on the cylinder body side is z,
The distance from the inner bottom surface of the cylinder cap to the closest approach position of the hollow inverted frustoconical rib having an opening with respect to the inner wall surface of the cylinder body is a,
The distance between the inner wall surface of the cylinder body and the hollow inverted frustoconical rib having an opening is b,
And when the maximum distance to the hollow rib having the inner wall surface of the cylinder cap and the opening on the inner bottom surface of the cylinder cap is c,
0 <a ≦ 50 (mm)
0 ≦ b ≦ 10 (mm)
0.5 <c ≦ 50 (mm)
And (x + y) / (c−z) ≧ a / (c−b)
It satisfies the relationship.

As described above, by deforming the cylindrical rib formed on the inner bottom portion of the cylinder cap into an inverted frustoconical shape by the cone in the cylinders that are integrally formed by friction welding, the cylinder has the inside of the cylinder body. The wall surface, the inner wall surface and the inner bottom surface of the cylinder cap, and the space formed by the rib can be easily and reliably formed.
In addition, it is assumed that the inner surface burr formed at the joint between the cylinder cap and the cylinder body that integrally form the cylinder and the rib formed on the inner bottom surface of the cylinder cap satisfy the above predetermined relationship. The burr can be reliably positioned in the space.
As a result, internal burrs peeled off from the inner wall surface of the cylinder due to vibration or the like reliably stay in the space and prevent the free piston from advancing, so that the free piston or the inner wall surface of the cylinder may be damaged. Therefore, the airtightness of the free piston can be reliably maintained.

  The present invention relates to an inner surface burr formed on the inner wall surface of a cylinder when integrally forming a cylinder of a single cylinder shock absorber, an inner wall surface of a cylinder body, an inner wall surface and an inner bottom surface of a cylinder cap, and an inner surface of the cylinder cap. Since it is located in the space formed by the inverted frustoconical rib formed on the bottom surface, the inner surface burr peeled off from the inner wall surface of the cylinder is reliably retained in the space. As a result, damage to the free piston or the inner wall of the cylinder can be prevented and the airtightness of the free piston can be reliably maintained, so that the oil or high pressure air can be separated by the free piston and the input load from the shock absorber can be reduced. It has the outstanding effect which can maintain attenuation over a long period of time.

Examples of the present invention will be described below.
In addition, this Example is for demonstrating one preferable embodiment of this invention, Comprising: This invention is not restrict | limited by this.

First, a shock absorber 1 according to the present invention includes a rod 2 that holds a disc-shaped piston valve 3 that allows oil 4 to flow at one end thereof, and a piston valve that holds the rod 2 inside thereof, including the rod 2. 3 and a cylindrical cylinder 7 that accommodates oil 4 and high-pressure air 5 separated by a disc-shaped free piston 6 that is slidable.
First, the cylinder 7 comprises a cylinder body 8 that is friction-welded to each other and a cylinder cap 9 that integrally forms a vehicle body mounting portion 10.
Further, a hollow inverted frustoconical rib 12 having an opening is formed on the inner bottom surface 11 of the cylinder cap 9.
The cylinder body 8 and the cylinder cap 9 are friction-welded and joined to the inner wall 7a of the cylinder 7, in particular, the inner wall burr 13 formed so as to protrude from the inner wall 7b 'of the joint 7b. The inner wall surface 8a of the cylinder cap 9, the inner wall surface 9a and the inner bottom surface 11 of the cylinder cap 9, and the space 14 formed by the inverted frustoconical rib 12 formed on the inner bottom surface 11 of the cylinder cap 9. Become.

Here, the shock absorber 1 of the present invention is manufactured as follows.
First, the cylinder 7 has a cylindrical cylinder body 8 and a cylinder cap 9 that integrally forms a vehicle body mounting portion 10 at one end and a cylindrical rib 15 at an inner bottom portion 11 thereof. 8b and 9b are brought into contact with each other and then integrally formed by friction welding. At this time, the outer surface burr 18 and the inner surface burr 13 are formed on the outer wall surface and the inner wall surface 7b ′ of the joint 7b of the cylinder 7, respectively. The outer burr 18 formed on the outer wall surface of the cylinder 7 is removed and shaped by this stage or the final stage.
In the cylinder 7, a cone 16 having a reverse taper surface 17 that decreases in diameter toward the tip is inserted into and pressed against a cylindrical rib 15 formed on the inner bottom surface 11 of the cylinder cap 9. Thus, the cylindrical rib 15 is deformed so as to gradually expand, and is formed into a hollow inverted frustoconical rib 12 having an opening.
As a result, the inner surface burr 13 formed so as to protrude from the inner wall surface 7b ′ of the joint portion 7b of the cylinder 7 by friction welding the cylinder body 8 and the cylinder cap 9 is formed on the inner wall surface 8a of the cylinder body 8. The cylinder cap 9 is positioned in the space 14 formed by the inner wall surface 9a and the inner bottom surface 11 of the cylinder cap 9 and the inverted frustoconical rib 12 formed on the inner bottom surface 11 of the cylinder cap 9 (see FIG. 3). ).

At this time, it is formed by the inner wall surface 8 a of the cylinder body 8 where the inner surface burr 13 is located, the inner bottom surface 11 of the cylinder cap 9, and the inverted frustoconical rib 12 formed on the inner bottom surface 11 of the cylinder cap 9. The space 14 satisfies the relationship shown in FIG. That is,
The distance from the inner bottom surface 11 of the cylinder cap 9 to the virtual equal division position between the inner surface burr 13 on the cylinder body 8 side and the inner surface burr 13 on the cylinder cap 9 side is x,
The maximum thickness of the internal burr 13 on the cylinder body 8 side is y,
The maximum protruding amount of the inner surface burr 13 on the cylinder body 8 side from the inner wall surface 8a of the cylinder body 8 is z,
The distance from the inner bottom surface 11 of the cylinder cap 9 to the closest approach position of the hollow inverted frustoconical rib 12 having an opening to the inner wall surface 8a of the cylinder body 8 is represented by a,
The distance between the inner wall surface 8a of the cylinder body 8 and the hollow inverted frustoconical rib 12 having an opening is b,
And when the maximum distance from the inner wall surface 9a of the cylinder cap 9 to the hollow rib 12 having an opening on the inner bottom surface 11 of the cylinder cap 9 is c,
0 <a ≦ 50 (mm)
0 ≦ b ≦ 10 (mm)
0.5 <c ≦ 50 (mm)
And (x + y) / (c−z) ≧ a / (c−b)
It is what.

  As described above, in the shock absorber 1 of the present invention, the inner surface burr 13 is formed so as to protrude from the inner wall surface 7b ′ of the joint 7b of the cylinder 7 by friction welding the cylinder body 8 and the cylinder cap 9. In the space 14 formed by the inner wall surface 8a of the cylinder body 8, the inner wall surface 9a and the inner bottom surface 11 of the cylinder cap 9, and the inverted frustoconical rib 12 formed on the inner bottom surface 11 of the cylinder cap 9. Positioned securely. As a result, even if the inner surface burr 13 is peeled off from the inner wall surface 7a of the joint portion 7b of the cylinder 7 due to vibration or the like, the peeled inner burr 13 is prevented from advancing toward the free piston 6 side. Alternatively, since the inner wall surface 7a of the cylinder 7 is not damaged, the airtightness of the free piston 6 can be reliably maintained.

Therefore, the shock absorber 1 of the present invention was actually manufactured as follows and the effect was confirmed.
First, in a cylinder 7 comprising a cylinder body 8 and a cylinder cap 9 of a shock absorber 1 which is an embodiment of the present invention, the cylinder body 8 is made of an aluminum alloy (JIS A6061-T8, diameter φ is 45 mm, and thickness t is 2). .5 mm) drawing tube. The cylinder cap 9 is made of an extruded material of an aluminum alloy (JIS A6061-T6, diameter φ is 45 mm), and is formed by integrally forming the annular vehicle body mounting portion 10 by cutting.
Then, the joining surface 8b of the cylinder body 8 and the joining surface 9b of the cylinder cap 9 are rotated at 1800 rpm, and friction welding is performed at a pressure of 100 MPa to form the joint 7b, and the cylinder 7 is configured integrally. .
Then, in the cylinder 7, a cone 16 having a reverse taper surface 17 that decreases in diameter toward the tip is inserted into a cylindrical rib 15 formed on the inner bottom surface 11 of the cylinder cap 9. The ribs 12 were deformed by pressing so as to satisfy the conditions of a = 30 mm, b = 0.5 mm, and c = 30 mm, and formed into a hollow inverted frustoconical rib 12 having an opening.
As a result, the inner surface burr 13 formed so as to protrude from the inner wall surface 7 a of the cylinder 7 by friction welding the cylinder body 8 and the cylinder cap 9 is formed on the inner wall surface 8 a of the cylinder body 8 and the cylinder cap 9. The inner wall surface 9 a, the inner bottom surface 11, and the inverted frustoconical rib 12 formed on the inner bottom surface 11 of the cylinder cap 9 are positioned in the space 14.

On the other hand, the following was manufactured as a comparative example for the shock absorber 1 which is an embodiment of the present invention.
First, as Comparative Example 1, in a cylinder 7 comprising a cylinder body 8 and a cylinder cap 9 of the shock absorber 1, the cylinder body 8 is made of an aluminum alloy (JIS A6061-T8, diameter φ is 45 mm, and thickness t is 2.5 mm). ). The cylinder cap 9 is made of an extruded material of an aluminum alloy (JIS A6061-T6, diameter φ is 45 mm), and is formed by integrally forming the annular vehicle body mounting portion 10 by cutting.
Then, the joining surface 8b of the cylinder body 8 and the joining surface 9b of the cylinder cap 9 are rotated at 1800 rpm, and friction welding is performed at a pressure of 100 MPa to form the joint 7b, and the cylinder 7 is configured integrally. .
However, the inverted frustoconical rib 12 was not formed, and the inner surface burr 13 formed so as to protrude from the inner wall surface 7b ′ of the joint 7b of the cylinder 7 was left as it was.

Further, as Comparative Example 2, in the cylinder 7 including the cylinder body 8 and the cylinder cap 9 of the shock absorber 1, the cylinder body 8 is made of an aluminum alloy (JIS A6061-T8, diameter φ is 45 mm, and thickness t is 2.5 mm). ). The cylinder cap 9 is made of an extruded material of an aluminum alloy (JIS A6061-T6, diameter φ is 45 mm), and is formed by integrally forming the annular vehicle body mounting portion 10 by cutting.
Then, the joining surface 8b of the cylinder body 8 and the joining surface 9b of the cylinder cap 9 are rotated at 1800 rpm, and friction welding is performed at a pressure of 100 MPa to form the joint 7b, and the cylinder 7 is configured integrally. .
Then, in the cylinder 7, a cone 16 having a reverse taper surface 17 whose diameter decreases toward the tip is inserted into a cylindrical rib 12 formed on the inner bottom surface 11 of the cylinder cap 9, and a = It was deformed by pressing so as to satisfy the conditions of 30 mm, b = 15 mm, and c = 30 mm, and formed into an inverted frustoconical rib 12 having an opening.
The inner surface burr 13 formed so as to protrude from the inner wall surface 7 a of the cylinder 7 by friction welding the cylinder body 8 and the cylinder cap 9 is formed on the inner wall surface 8 a of the cylinder body 8 and the inner wall of the cylinder cap 9. A wall surface 9 a and an inner bottom surface 11, and an inverted frustoconical rib 12 formed on the inner bottom surface 11 of the cylinder cap 9 are located in a space 14.

Therefore, when the sliding durability test was performed on the above-described Examples of the present invention and Comparative Examples 1 and 2 under the conditions of the excitation amplitude of 50 mm and the lateral load of 200 N, the present invention was found to be oil 4 or high-pressure air even 3 million times. No leakage of oil 5 or high-pressure air 5 was observed in Comparative Example 1 at 10,000 times and Comparative Example 2 at 100,000 times.
Therefore, in the present invention, even if the inner surface burr 13 is peeled off from the inner wall surface 7 b ′ of the joint 7 b of the cylinder 7, the inner surface burr 13 remains in the space 14 and remains on the free piston 6 or the inner wall surface 7 a of the cylinder 7. The effect of preventing the airtightness of the free piston 6 from being lowered and maintaining the attenuation of the input load over a long period without causing damage was sufficiently recognized.

  The present invention can be widely applied not only to a single cylinder type shock absorber but also to various structures that include a sliding member such as a piston that is slidable within a cylinder having a joint.

It is sectional drawing of the shock absorber which is an Example of this invention. It is the schematic diagram which showed the predetermined dimension in the shock absorber which is an Example of this invention. It is the schematic diagram which showed the manufacturing process of the shock absorber which is an Example of this invention.

DESCRIPTION OF SYMBOLS 1 Shock absorber 2 Rod 3 Piston valve 4 Oil 5 High pressure air 6 Free piston 7 Cylinder 7a (Cylinder) inner wall surface 7b Joining part 7b 'Inner wall surface 8 Cylinder body 8a Inner wall surface 8b Joining surface 9 Cylinder cap 9a Inner wall surface 9b Joining surface DESCRIPTION OF SYMBOLS 10 Car body attaching part 11 Inner bottom face (of cylinder cap) 12 (Inverted truncated cone shape) rib 13 Inner surface burr 14 Space 15 (Cylindrical) rib 16 Cone 17 Reverse taper surface 18 Outer surface burr

Claims (3)

A rod that is slidable and that holds a disc-shaped piston valve that allows oil to flow at one end thereof, and a disc that is slidable together with a piston valve that is held at one end including the rod inside the rod. It is composed of a cylindrical cylinder that contains oil and high-pressure air while being separated by a free piston,
The cylinder is composed of a cylinder main body integrated with each other by friction welding and a cylinder cap integrally forming a vehicle body mounting portion.
Forming a hollow inverted frustoconical rib having an opening on the inner bottom surface of the cylinder cap;
An inner surface burr formed so as to protrude from the inner wall surface of the joint portion of the cylinder by friction welding the cylinder body and the cylinder cap is the inner wall surface of the cylinder body, the inner wall surface and the inner bottom surface of the cylinder cap, and the cylinder It is located in a space formed by the inverted frustoconical rib formed on the inner bottom surface of the cap,
X, the distance from the inner bottom surface of the cylinder cap to the virtual equal division position between the inner surface burr on the cylinder body side and the inner surface burr on the cylinder cap side,
The maximum thickness of the internal burr on the cylinder body side is y,
The maximum amount of protrusion from the inner wall of the cylinder body of the inner surface burr on the cylinder body side is z,
The distance from the inner bottom surface of the cylinder cap to the closest approach position of the hollow inverted frustoconical rib having an opening with respect to the inner wall surface of the cylinder body is a,
The distance between the inner wall surface of the cylinder body and the hollow inverted frustoconical rib having an opening is b,
And when the maximum distance to the hollow rib having the inner wall surface of the cylinder cap and the opening on the inner bottom surface of the cylinder cap is c,
0 <a ≦ 50 (mm)
0 ≦ b ≦ 10 (mm)
0.5 <c ≦ 50 (mm)
And (x + y) / (c−z) ≧ a / (c−b)
A shock absorber characterized by satisfying the above relationship. A rod that is slidable and that holds a disc-shaped piston valve that allows oil to flow at one end thereof, and a disc that is slidable together with a piston valve that is held at one end including the rod inside the rod. Comprising a cylinder that contains oil and high-pressure air while being separated by a free piston,
A cylindrical cylinder body and a body mounting part are integrally formed at one end, and a cylinder cap that forms a cylindrical rib is integrally formed on the inner bottom part of the cylinder body to form a joint part by friction welding. ,
Inside the cylinder, a hollow having an opening by inserting and pressing a cone having a reverse taper surface that is reduced in diameter toward the tip of a cylindrical rib formed on the inner bottom surface of the cylinder cap. Transformed into a frustoconical rib,
An inner surface burr formed so as to protrude from the inner wall surface of the joint portion of the cylinder by friction welding the cylinder body and the cylinder cap, the inner wall surface of the cylinder body, the inner wall surface and the inner bottom surface of the cylinder cap, and the A shock absorber manufacturing method characterized by being positioned in a space formed by an inverted frustoconical rib formed on the inner bottom surface of a cylinder cap. Friction welding the cylinder body and the cylinder cap in the space formed by the inner wall surface of the cylinder body, the inner wall surface and inner bottom surface of the cylinder cap, and the inverted frustoconical rib formed on the inner bottom surface of the cylinder cap. When the inner surface burr formed so as to protrude from the inner wall surface of the joint portion of the cylinder by positioning is positioned,
X, the distance from the inner bottom surface of the cylinder cap to the virtual equal division position between the inner surface burr on the cylinder body side and the inner surface burr on the cylinder cap side,
The maximum thickness of the internal burr on the cylinder body side is y,
The maximum amount of protrusion from the inner wall of the cylinder body of the inner surface burr on the cylinder body side is z,
The distance from the inner bottom surface of the cylinder cap to the closest approach position of the hollow inverted frustoconical rib having an opening with respect to the inner wall surface of the cylinder body is a,
The distance between the inner wall surface of the cylinder body and the hollow inverted frustoconical rib having an opening is b,
And when the maximum distance to the hollow rib having the inner wall surface of the cylinder cap and the opening on the inner bottom surface of the cylinder cap is c,
0 <a ≦ 50 (mm)
0 ≦ b ≦ 10 (mm)
0.5 <c ≦ 50 (mm)
And (x + y) / (c−z) ≧ a / (c−b)
The method for manufacturing a shock absorber according to claim 2, wherein:

Images