JP4844885B2 - Cylinder device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a cylinder device such as a hydraulic shock absorber, a fluid pressure cylinder, and a gas spring, and more particularly to a cylinder device suitable for an automobile suspension and a manufacturing method thereof.

  For example, as shown in FIG. 6, a hydraulic shock absorber mounted on a suspension of an automobile includes a cylinder 1, a rod 2 that is extendable from the cylinder 1, and an extension of the rod 2 from the cylinder 1. And a cap body 3 fitted to the protruding portion. In such a hydraulic shock absorber, the bottom of the cylinder 1 is attached to a suspension arm (not shown), while the tip of the rod 2 is attached to the vehicle body via a bolt-shaped part 2a. A protective cover 4 for protecting the rod 2 is attached to the outer periphery of the body 3.

  By the way, as shown in FIG. 7, the rod 2 generally has a rod body 5 extended from the cylinder 1 and a rod-shaped mounting member 6 provided with the bolt-shaped portion 2a on the tip side. It was joined (usually projection welding). In this case, the cap body 3 is disposed by being fitted to a step portion 5a provided at the tip of the rod body 5, and in this state, the tip of the rod body 5 and the head of the rear end of the mounting member 6 are caps. The three members are joined together through the body 3 and are welded together. A similar joint structure is also described in Patent Document 1.

  However, according to the above-described joining structure, the inner peripheral surface of the cap body 3 receives torque in the oscillating rotation direction applied to the cap body, so that stress concentrates on the inner peripheral portion of the cap body 3 and the current RV In an automobile or the like that generates a lot of vibration in a car or the like, there is a possibility that a crack (fatigue crack) may occur in the cap body at an early stage. As a countermeasure, it is effective to increase the plate thickness of the cap body. However, in the embodiment in which the rod body, the mounting member, and the cap body are simultaneously welded as described above, the cap body plate is used. The increase in thickness makes welding unstable and makes it difficult to safely secure the desired joint strength.

On the other hand, in Patent Document 2, a cap part is integrally formed on the joining end side of the mounting member with respect to the rod body, and only the rod body and the mounting member are butted and joined together. A cylinder device has been proposed in which is omitted. However, in this case, for the convenience of integrally forming a large-diameter cap portion with a diameter difference greatly different from that of the mounting member, the mounting member must be manufactured by casting, and an increase in manufacturing cost can be avoided. It will not be.
Japanese Utility Model Publication No. 56-138246 Japanese Patent Application No. 2005-163824

  The present invention has been made in view of the above-described conventional problems, and the object of the present invention is to provide a cylinder device that increases the resistance of the cap body to vibration without causing a decrease in bonding strength or an increase in manufacturing cost. And a manufacturing method capable of obtaining the cylinder device efficiently and safely.

To solve the above problems, a cylinder device according to the present invention, the cylinder and a rod which extends telescopically from the cylinder, an annular cap body is fitted to the extending portion from the cylinder of the rod with the door, said rod, said has become joined by butt the rod-shaped mounting member in the extending out the rod body and the tip-side bolt-shaped part from the cylinder, for the previous SL rod body of the mounting member On the butt end side, a flange portion having a diameter larger than that of the mounting member is formed, and the surface of the flange portion on the opposite side to the joining side with the rod body is a surface orthogonal to the axis, The cap body is characterized in that an inner peripheral flat portion fitted to the mounting member is overlapped with the orthogonal surface of the collar portion and joined at the orthogonal surface .

In the cylinder device configured as described above, the flat portion of the annular cap body is joined to the surface orthogonal to the axis of the flange portion of the mounting member, so that the swing rotation applied to the cap body The torque in the direction is received by the wide flat surface of the cap body, and the stress generated in the cap body is dispersed accordingly, and the cap body is hardly cracked. Further, since only the two members of the attachment member and the cap are overlapped and joined, the joining strength can be ensured. In addition, the mounting member that constitutes the rod has a shape that has only a flange portion that does not have a large difference in diameter, so that it can be manufactured by cutting or forging, and manufactured in comparison with the case of manufacturing by casting. Cost is reduced.

  In the cylinder device, an annular groove may be provided in a connecting portion of the flange portion with respect to the mounting member. In this case, when the cap body is overlapped with the collar portion, the connection portion does not interfere with the inner peripheral edge of the cap body due to the presence of the annular groove, and the flat portion of the cap body and the collar portion of the mounting member Can be closely overlapped with each other, and the lap joint can be reliably performed.

In order to solve the above-mentioned problem, a manufacturing method of a cylinder device according to the present invention includes a cap body overlapped with a flange portion of an attachment member, welded on a surface orthogonal to the axis , and the attachment member and The rod body is butted and welded to complete the rod, and then the rod is assembled to the cylinder.

  In the manufacturing method performed in this way, since the cap body is welded to the mounting member in advance, the welding work around the rod main body is performed only once as in the conventional case, and the chance of spatter adhesion to the rod main body increases. Absent. Further, since the two members of the attachment member and the cap body and between the attachment member and the rod body are welded, there is no special difficulty in welding.

In this manufacturing method, the method of welding the mounting member and the cap body is arbitrary, but since it can be efficiently and reliably welded , a projection welding projection is provided on a surface orthogonal to the axis of the collar, It is desirable to join by projection welding.

According to the cylinder device according to the present invention, since the flat surface of the annular cap body is overlapped and joined to the surface orthogonal to the axis of the collar portion of the mounting member, the stress generated in the cap body is dispersed, Even in environments where intense vibrations are applied, it is difficult for fatigue cracks to occur in the cap body, ensuring the bonding strength and significantly improving the reliability of the device. Further, since the mounting member constituting the rod can be manufactured by cutting or forging, the manufacturing cost is reduced as compared with the case of manufacturing by casting, and the effect of the present invention is generally large.

  Also, according to the method for manufacturing a cylinder device according to the present invention, the welding work around the rod body does not increase, so that contamination of the rod body can be suppressed and the cylinder device can be manufactured safely. Since the two members are welded together, the cylinder device can be efficiently manufactured without any particular difficulty in welding.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows a hydraulic shock absorber according to one embodiment of the present invention. This hydraulic shock absorber is mounted on the suspension of an automobile, and its basic configuration is the same as that shown in FIG. 6, and therefore, the same reference numerals are given to the same parts here. In the present embodiment, the rod 2 extended from the cylinder 1 so as to be extendable and contracted is obtained by abutting a rod main body 10 extended from the cylinder 1 and a mounting member 12 having a bolt-shaped portion 11 on the tip side as in the conventional case. It is joined. As shown in FIG. 2, a collar portion 13 is integrally formed on the mounting member 12 on the side of the butting end with the rod body 10, and the protective cover 4 is attached to the collar portion 13. For this purpose, a cap body 14 is overlapped and joined.

  In the present embodiment, the cap body 14 is lap welded to the collar portion 13 by projection welding. A through hole 15 into which the attachment member 12 can be inserted is formed at the center of the cap body 14, and a flat surface that can be overlapped with the collar portion 13 is formed at the bottom of the cap body 14 centering on the through hole 15. A portion 16 is formed. The cap body 14 is fitted to the mounting member 12 through the through hole 15 so that the flat portion 16 can be overlapped with the collar portion 13.

  On the other hand, a plurality of (three in this case) projections 17 for projection welding are formed on one surface (mating surface) of the collar portion 13 on which the cap body 14 is overlapped, as well shown in FIGS. It is formed with equal distribution in the circumferential direction. Further, the mating surface of the collar portion 13 is a surface orthogonal to the axis of the mounting member 12, and an annular groove 18 is formed in the connecting portion of the inner peripheral portion (FIG. 4). 5). The annular groove 18 serves to prevent the connecting portion from interfering with the inner peripheral edge of the cap body 14. Due to the presence of the annular groove 18, the cap body 14 is connected to the collar portion 13 via the protrusion 17. It will be possible to reliably overlap.

  The size of the collar portion 13 is set to an appropriate size in consideration of the bonding strength with the cap body 14, the manufacturability of the mounting member 12, and the like. As an example, the outer diameter of the collar portion 13 is set to about 1.5 to 2.0 times the diameter of the mounting member 12. Further, the height of the protrusion 17 provided on the collar portion 13 is sufficient if it is a size required for normal projection welding, and is set to about 1 mm. Further, it is desirable that the annular groove 18 provided in the collar portion 13 is formed as shallow as possible within a range in which the connecting portion with the mounting member 12 is removed. Further, it is desirable that the annular groove 18 has a curved shape as shown in FIG.

  In the present embodiment, the flange portion 13 of the mounting member 12 is formed at a site where a slight protrusion 19 is left on the end of the butt end with the rod body 10. The mounting member 12 has its protrusion 19 abutted against the rod body 10 and is abutted and joined to the rod body 10 (in this case, projection welding). Therefore, the collar 13 is an obstacle to butt welding. Never become.

  Here, the attachment member 12 having the collar portion 13 can be integrally manufactured by cutting from a round bar or by forging. However, for mass production, forging is advantageous in terms of cost. . Further, the screw-shaped portion 11 on the distal end side of the mounting member 12 may be formed by cutting or rolling, but when mass production is required, rolling processing is costly. It is advantageous.

  In order to manufacture the cylinder device, first, the cap body 14 separately formed is overlap-welded by projection welding to the flange portion 13 of the mounting member 12 manufactured as described above. At the time of this lap welding, as shown in FIG. 2, the cap body 14 is inserted from the screw-shaped portion 11 side of the mounting member 12 and overlapped with the collar portion 13 through the projections 17. The collar portion 13 is sandwiched between electrodes and pressurized and energized. Then, resistance heat is generated intensively around the protrusion 17 at the overlapping portion of both, and the cap body 14 and the collar portion 13 of the mounting member 12 are efficiently and firmly welded by this heat. Next, the projecting portion 19 of the mounting member 12 to which the cap body 14 is joined and the rod body 10 are butted together, and both are butt welded by projection welding. As a result, the rod 2 is completed, and thereafter, the rod 2 is assembled to the cylinder 1 according to a predetermined assembling procedure, and the cylinder device is completed thereto.

  In the cylinder device thus completed, the bottom portion of the cylinder 1 is attached to the suspension arm (not shown) as described above, while the tip end portion of the rod 2 is attached to the vehicle body via the bolt-shaped portion 11. In this state, a protective cover 4 for protecting the rod 2 is attached to the outer periphery of the cap body 14. Thus, in this cylinder device, the flat portion 16 of the cap body 14 is overlapped and joined to the collar portion 13 of the mounting member 12, and therefore the torque in the swinging rotation direction applied to the cap body 14 is the cap body 14. Can be received on a wide flat surface. Therefore, the stress generated in the cap body 14 is dispersed over a wide range, and as a result, cracks (fatigue cracks) are less likely to occur in the cap body 12 even under conditions in which severe vibration is applied to the cap body 14 with an RV vehicle or the like. Further, since only the two members of the attachment member 12 and the cap 14 are overlap welded, the plate thickness of the cap body 14 can be increased. In this case, as the plate thickness of the cap body 14 is increased, the rigidity of the cap body 14 is increased, and the overall deformation thereof is suppressed. As a result, the lower end of the protective cover 4 comes into contact with the cylinder 1 and the cylinder 1 There is no risk of scratching the painted surface.

  In manufacturing the cylinder device, the cap member 14 is overlapped and welded to the collar portion 13 of the mounting member 12 as described above, and then the mounting member 12 and the rod body 10 are butt welded. The welding work at is just one time as before. This means that the chance that spatter adheres to the piston rod 2 does not increase, and according to this manufacturing method, the cylinder device can be manufactured safely. Further, since the two members of the attachment member 12 and the cap body 14, and the attachment member 12 and the rod body 10 are welded together, the cylinder device can be efficiently manufactured without any special difficulty in welding.

  In the above embodiment, projection welding is used for the lap welding of the mounting member 12 and the cap body 14, but the method of the lap welding is arbitrary, and instead of projection welding, for example, spot welding or laser welding is used. Etc. can be used. Moreover, the method of butt welding of the rod main body 10 and the attachment member 12 is also arbitrary, and various fusion welding methods can be used including various resistance welding methods.

  Further, in the above-described embodiment, an example is shown in which the present invention is applied to a hydraulic shock absorber mounted on a suspension. However, the present invention is naturally applicable to various cylinder devices that require a cap body as a part of a rod. .

It is a side view which shows the principal part structure of the hydraulic shock absorber which is one embodiment of this invention as a partial cross section. It is an exploded view of the rod which comprises this hydraulic shock absorber. It is a side view which shows the shape of the attachment member which comprises this rod. It is a front view of the attachment member shown in FIG. It is sectional drawing which expands and shows the A section of FIG. It is a side view which shows the principal part structure of the conventional hydraulic shock absorber as a partial cross section. It is an exploded view of the rod which comprises the conventional hydraulic shock absorber.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Rod 4 Protective cover 10 Rod main body 11 Bolt shape part 12 Mounting member 13 Collar part 14 Cap body 15 Through hole of the cap body 16 Flat part of the cap body 17 Projection welding projection 18 Annular groove

Claims (4)

A cylinder,
A rod extended and retractable from the cylinder;
And an annular cap body is fitted to the extending portion from the cylinder of the rod,
The rod is formed by abutting and joining a rod body extending from the cylinder and a rod-shaped attachment member having a bolt-shaped portion on the tip side,
Wherein the butt end side for the previous SL rod body of the mounting member, the flange portion of a diameter larger than the attachment member is formed,
The surface of the flange portion opposite to the side joined to the rod body is a surface orthogonal to the axis,
The cap body has an inner peripheral flat portion fitted to the mounting member overlapped with the orthogonal surface of the collar portion , and is joined to the orthogonal surface. . The cylinder device according to claim 1, wherein an annular groove is provided in a connecting portion of the flange portion with respect to the mounting member. A method of manufacturing the cylinder device according to claim 1 or 2, wherein a cap body is overlaid on the collar portion and both are welded on a surface orthogonal to the axis , and then the mounting member and the rod body And then welding them to complete the rod, and then assembling the rod to the cylinder. 4. The method of manufacturing a cylinder device according to claim 3 , wherein the attachment member and the cap body are welded by providing projection welding projections on the orthogonal surfaces of the collar portion and joining them by projection welding.

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