JP4919070B2 - Manufacturing method of double cylinder type hydraulic shock absorber - Google Patents

Description

The present invention relates to a hydraulic shock absorber used in a suspension of an automobile, in particular piston about the method for manufacturing a twin-tube type hydraulic shock absorber of matches and cylinder into the barrel inner slide.

  As shown in FIGS. 5 and 6, the double cylinder type hydraulic shock absorber generally has a bottomed outer cylinder 3 together with a base valve device 2 mounted at one end of an inner cylinder 1 on which a piston (not shown) slides. The base valve device 2 is brought into contact with the inner surface of the bottom plate portion 4 of the outer cylinder 3 to position and fix the inner cylinder 1 with respect to the outer cylinder 3, and the oil liquid sealed in the inner cylinder 1 is A valve provided on the piston and the base valve device 2 are circulated to generate a damping force in the extension stroke and the contraction stroke, and the oil liquid of the entry and exit of the piston rod 5 integral with the piston is supplied to the inner cylinder 1 and the outer cylinder. 3 is compensated by a reservoir 6 between the two. In the figure, 7 is a knuckle bracket connected to the knuckle of the vehicle body, and 8 is a spring seat that receives a spring interposed between the knuckle and the vehicle body.

  In the above-described multi-cylinder hydraulic shock absorber, the bottom plate portion 4 of the outer cylinder 3 has been conventionally formed by welding a separate base cap, but recently, adverse effects such as contamination due to welding have been caused. In order to avoid this, the tube end portion is formed by closing. The closing process is described in, for example, Patent Document 1, in which a tube end is heated at a high frequency, and then a female tool that rotates is pressed against the tube end to perform squeezing and sealing, and then the bottom plate The part 4 is formed without a seam.

By the way, in the double cylinder type hydraulic shock absorber, if the inner cylinder 1 is not accurately positioned with respect to the outer cylinder 3, abnormal noise is generated during operation as a product, or the sliding property of the piston is deteriorated. A malfunction occurs. Therefore, in the one described in Patent Document 1, the inner surface of the bottom plate portion 4 is cooperated with the female tool and the mandrel at the final stage where the mandrel is inserted into the tube in advance and the mouth-drawing and sealing are finished. As shown in FIG. 7, a seat 4a for receiving the base valve device 2 is formed on the inner surface.
Japanese Patent Laid-Open No. 2003-200241

  However, in the outer cylinder obtained by the closing process described in Patent Document 1, the seat 4a for receiving the base valve device 2 has a linear shape at the intersection of two surfaces with different inclination angles. Since it is only molded, the seat of the base valve device 2 with respect to the seat portion 4a is poor, and there is a problem that it is difficult to accurately position the inner cylinder 1 on the outer cylinder 3. Further, if the shape of the inner surface of the bottom plate portion 4 is simultaneously formed by closing, the number of steps may be reduced, but the shape accuracy of the inner surface may not be sufficient.

The present invention has been made in view of the above-described conventional problems. The object of the present invention is to enable accurate positioning of the inner cylinder with respect to the outer cylinder by changing the inner surface shape of the bottom plate portion of the outer cylinder. Accordingly, it is an object of the present invention to provide a manufacturing method capable of manufacturing a multi-cylinder hydraulic shock absorber with no abnormal noise and stable operation with high accuracy and efficiency.

In order to solve the above-mentioned problems, a method of manufacturing a double cylinder type hydraulic shock absorber according to the present invention includes a step of accommodating an inner cylinder in which a piston slides in a bottomed outer cylinder together with a base valve device attached to one end thereof. And a method of manufacturing a multi-cylinder hydraulic shock absorber comprising: a step of bringing the base valve device into contact with an inner surface of a bottom plate portion of the outer cylinder and positioning and fixing the inner cylinder with respect to the outer cylinder. Before the step, the step of forming the bottom plate portion by closing processing, and after the temperature becomes high by the step, set a punch having a step forming portion, the temperature of the bottom plate portion is made using the residual heat of the step A step of forming an annular step of a predetermined depth on the inner surface of the bottom plate portion by press working before the temperature becomes lower than a predetermined temperature; and fitting the base valve device to the step to disengage the inner cylinder Positioning and fixing to the cylinder Characterized in that the extent is performed.

  In the manufacturing method of the double cylinder type hydraulic shock absorber performed in this way, after finishing the closing process, a step is formed in the bottom plate part by pressing, so that the inner surface of the bottom plate part can be shaped with high accuracy. . In addition, since the press working is performed using the residual heat of the closing process, it is possible to minimize the cost increase due to the increased number of processes.

According to the manufacturing method of the double cylinder type hydraulic shock absorber according to the present invention , it is possible to accurately shape the inner surface of the bottom plate portion by pressing, and minimize the increase in cost by utilizing the residual heat of the closing process. To the limit.

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

  FIG. 1 shows the main structure of a double cylinder type hydraulic shock absorber according to the present invention. Since the overall structure of the hydraulic shock absorber is the same as that shown in FIG. 5, the same reference numerals are assigned to the same components, and duplicate descriptions are omitted. In the present embodiment, the bottom plate portion 4 of the outer cylinder 3 is formed seamlessly by squeezing and sealing the tube end portion by hot closing described in Patent Document 1.

  As shown in FIG. 2, a step 10 having a predetermined depth d is formed in an annular shape on the inner surface of the bottom plate portion 4 of the outer cylinder 3, and a base attached to one end of the inner cylinder 1. The valve device 2 is fitted to the step 10. The step 10 is formed so as to be concentric with the outer cylinder 3, whereby one end (lower end) of the inner cylinder 1 is supported concentrically with the outer cylinder 3. On the other hand, the upper end portion of the inner cylinder 1 is concentrically supported by the outer cylinder 3 via a rod guide (not shown) for guiding the piston rod 5 (FIG. 5). Further, the upper end of the inner cylinder 1 is pressed in the axial direction by a bent piece (not shown) obtained by bending the opening end of the outer cylinder 3 inward, and the base valve device 2 is in a state of bottoming in the step 10. The position is fixed. Therefore, the inner cylinder 1 is accurately positioned and fixed with respect to the outer cylinder 3 in the radial direction and the axial direction. A mortar-shaped slope 11 is formed on the inner surface of the bottom plate portion 4 around the step 10, which will be described later. The depth d of the step 10 is preferably at least 1 mm in order to ensure the fitting of the base valve device 2.

  Here, the base valve device 2 includes a valve body 14 having a first flow path 12 and a second flow path 13 penetrating in the axial direction, and a disk-shaped damping valve 15 for opening and closing the first flow path 12. A disc-shaped check valve 16 that opens and closes the second flow path 13 is provided, and both the valves 15 and 16 are fixed to the valve body 14 using a rivet 17 and a washer 18. The valve body 14 is made of a sintered body, and its upper end side outer peripheral portion is press-fitted and fixed to the inner cylinder 1, while its lower end side outer peripheral portion is fitted to the step 10. A notch 19 that opens into the reservoir 6 is formed at the lower end of the valve body 14. The inside of the inner cylinder 1 and the reservoir 6 communicate with each other through the notch 19 and the two flow paths 12 and 13. It has been made. In this base valve device 2, during the compression stroke of the hydraulic shock absorber, the damping valve 15 is opened, and the oil in the inner cylinder 1 flows to the reservoir 6 through the first flow path 12 and the notch 19, whereas During the stroke, the check valve 16 opens and the oil in the reservoir 6 flows into the inner cylinder 1 through the notch 19 and the second flow path 13.

  In the present embodiment, the step 10 and the slope 11 provided on the inner surface of the bottom plate portion 4 of the outer cylinder 3 may be formed by cutting, but are preferably formed by pressing. FIG. 3 shows one embodiment in the case where the step 10 and the slope 11 are formed by press working, and the punch 20 disposed in a fixed position on the lower side and the punch 20 approaching and separating from the upper side. Processing is performed by the die 21. A step forming part 22 for forming the step 10 and a slope forming part 23 for forming the slope 11 are connected to the upper end of the punch 20, while the die 21 has A central pressing portion 24 that presses the top of the outer surface of the curved bottom plate portion 4 and an annular peripheral pressing portion 25 that presses an intermediate portion of the bottom plate portion 4 are provided.

  At the time of pressing, the outer cylinder 3 is externally fitted and set on the punch 20 with the die 21 raised, and the bottom plate portion 4 is supported on the upper end portion of the punch 20. At this time, the outer cylinder 3 is positioned so as to be concentric with the punch 20, and the die 21 is lowered upon completion of the setting. Then, the bottom plate portion 4 of the outer cylinder 3 is pressed against the punch 20 by the center pressing portion 24 and the peripheral pressing portion 25 of the die 21, whereby the step forming portion 22 of the punch 20 bites into the inner surface of the bottom plate portion 4. 10 is molded. At the same time, the periphery of the step 10 is pressed by the slope forming part 23 of the punch 20, and the mortar-like slope 11 is formed on the inner surface. In this way, when the step 10 and the slope 11 are formed by pressing, the processing is completed in a short time, so that mass production is possible as compared with machining, and in addition, cutting waste is generated from the inside of the outer cylinder 3. Since the step of washing and removing is unnecessary, it is advantageous in terms of cost.

  In the present embodiment, it is desirable that the press work be performed hot by heating the bottom plate portion 4 of the outer cylinder 3 to a predetermined temperature (for example, 700 ° C. or higher). In this case, the residual heat of the above-described closing process may be used. In this case, the outer cylinder 3 is quickly set on the punch 20 after the closing process is completed, and the temperature of the bottom plate portion 4 is a predetermined temperature. While keeping the above, the die 21 is lowered to complete the press work. In the case of performing hot pressing as described above, since a molding load is small, a small processing facility is sufficient, which is advantageous in terms of facility cost. Incidentally, the molding load when the step 10 having a depth of 1 mm is molded at a processing temperature of 700 ° C. is about 350 kN. In addition, as described above, when the residual heat of the hot closing process is used, reheating is not necessary, which is extremely advantageous in terms of energy cost. In addition, when press-processing by reheating the bottom plate part 4 of the outer cylinder 3, it is desirable to use high-frequency heating because it can be heated for a short time.

  In order to assemble the above-described multi-cylinder hydraulic shock absorber, as shown in FIG. 4, a sub-assembly body 30 in which the base valve device 2 is attached to one end of the inner cylinder 1 in advance is prepared. In addition, the outer cylinder 3 having finished the molding of the bottom plate portion 4 by the closing process and the molding of the step 10 and the slope 11 by the pressing process is prepared, and the sub-assembly body 30 is placed in the base valve device 2 first. Insert into the outer cylinder 3. Then, the base valve device 2 at the tip of the subassembly body 30 is centered by the inclined surface 11 on the inner surface of the bottom plate portion 4 of the outer cylinder 3 and is smoothly fitted into the step 10. After that, the piston is inserted into the inner cylinder 1 and the other end portion of the inner cylinder 1 is positioned and fixed to the outer cylinder 3 via the rod guide, and the oil liquid is stored in the inner cylinder 1 and the oil liquid is stored in the reservoir 6. And the gas are sealed, and the open end is sealed through an oil seal to complete the double cylinder type hydraulic shock absorber.

  The double cylinder type hydraulic shock absorber completed as described above generates a damping force by flowing the oil in the inner cylinder 1 through a valve provided on a piston (not shown) during the extension stroke. At this time, the base valve The check valve 16 of the device 2 is opened, and the oil liquid for the withdrawal of the piston rod 5 is replenished from the reservoir 6 into the inner cylinder 1. On the other hand, during the contraction stroke, the oil liquid in the inner cylinder 1 opens and circulates by opening the damping valve 15 of the base valve device 2, and at the same time, the oil liquid for the entry of the piston rod 5 is stored in the reservoir 6. Spill to Thus, since the inner cylinder 1 constituting the hydraulic shock absorber is accurately positioned with respect to the outer cylinder 3 using the step 10, the expansion and contraction operation described above is stable and different during operation. No sound is generated.

It is sectional drawing which shows the principal part structure of the double cylinder type hydraulic shock absorber which concerns on this invention. It is sectional drawing which shows the shape of the baseplate part of the outer cylinder which comprises this hydraulic shock absorber. It is sectional drawing which shows embodiment of the press work for shape | molding a level | step difference and a slope in an outer cylinder. It is sectional drawing which shows the implementation condition of the assembly of this hydraulic shock absorber. It is a side view which shows the whole structure of a double cylinder type hydraulic shock absorber as a partial cross section. It is sectional drawing which shows the bottom part structure of a double cylinder type hydraulic shock absorber. It is sectional drawing which shows the shape of the general bottom-plate part shape | molded by the closing process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner cylinder 2 Base valve apparatus 3 Outer cylinder 4 Bottom plate part 5 Piston rod 6 Reservoir 10 Level difference 11 Slope 20 Punch 21 Die

Claims (1)

A step of accommodating an inner cylinder in which a piston slides in a bottomed outer cylinder together with a base valve apparatus mounted on one end thereof; and the inner cylinder by bringing the base valve apparatus into contact with an inner surface of a bottom plate portion of the outer cylinder In the method of manufacturing a double cylinder type hydraulic shock absorber comprising the step of positioning and fixing the outer cylinder to the outer cylinder,
Before these steps, a step of forming the bottom plate portion by closing processing, and after reaching a high temperature by the step, set a punch having a step forming portion, and using the residual heat of the step, the bottom plate portion A step of forming an annular step having a predetermined depth on the inner surface of the bottom plate portion before the temperature reaches a predetermined temperature by pressing, and fitting the base valve device to the step to connect the inner cylinder And a step of positioning and fixing the outer cylinder with respect to the outer cylinder.

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