JP2001263307A - Piston structure of fluid pressure cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce fabrication costs. SOLUTION: A cushion rubber 35b arranged on a head side end face of a piston 25 is attached on the piston 25 by a cushion holder 36 and a screw 31 constituting attaching means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston structure of a hydraulic cylinder.

[0002]

2. Description of the Related Art Some cylinders utilizing fluid pressure have a piston which is reciprocated based on supply and discharge of fluid. In such a fluid cylinder, it is necessary to appropriately absorb the inertial energy of the piston at the end of the stroke so as to absorb the impact of the piston on the cylinder. Therefore, some cylinders in which a cushion rubber is arranged on a piston have been proposed.

FIG. 3 shows an example of this type of hydraulic cylinder. In the fluid pressure cylinder 61 shown in the figure, a metal piston 64 having a piston rod 63 connected to one side is slidably accommodated in a cylinder tube 62.
Two annularly formed cushion rubbers 66a and 66b are provided on both end surfaces of the piston 64. The cushion rubber 66 b on the head side of the piston 64 is externally inserted into a protrusion 67 provided at the center of the piston 64. The inner peripheral edge of the cushion rubber 66b is
Is fitted in an annular groove 67a machined on the outer peripheral surface of the rim.

[0004] In addition to the hydraulic cylinder 61 shown in FIG. 3, a hydraulic cylinder 61 shown in FIG. 4 has been proposed. In FIG. 4, an annular cushion rubber 66 b on the head-side end surface of the piston 64 is disposed in a concave portion 68 formed on the head-side end surface of the piston 64. The outer peripheral edge of the cushion rubber 66b is fitted into a cut portion 68a formed by cutting the outer peripheral surface of the concave portion 68.

[0005]

However, in the conventional hydraulic cylinder 61 shown in FIGS. 3 and 4, the surface of the piston 64 must be cut in order to attach the cushion rubber 66b to the piston 64. . Therefore, not only is processing difficult, but also the cost increases.

Further, it is necessary to prepare a plurality of types of pistons 64 having different shapes depending on the use of the fluid pressure cylinder 61.
Therefore, parts cannot be shared, resulting in high cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a piston structure of a hydraulic cylinder which is easy to process and inexpensive.

[0008]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, a piston and a piston rod integrated in a cylinder tube are provided so as to be reciprocally movable. In a piston structure of a fluid pressure cylinder having a buffer member provided on an end surface on a head side, an essential point is that an attaching means for attaching the buffer member to an end surface on a head side of the piston is provided.

According to a second aspect of the present invention, in the piston structure of the hydraulic cylinder according to the first aspect, the attaching means is attached to a piston or a piston rod, and the attaching means and the piston are used for the attachment. The gist of the present invention is that the buffer member is sandwiched and supported.

According to a third aspect of the present invention, in the piston structure of the hydraulic cylinder according to the first or second aspect, the buffer member is formed in an annular shape, and the mounting means is disposed inside the buffer member. The gist is that an outer peripheral edge of the attachment means is formed with an engaging portion that engages with an inner peripheral edge of the cushioning member.

According to the invention described in claim 4, the gist is that the end face on the head side of the piston has a flat shape. Hereinafter, the “action” of the present invention will be described.

According to the first aspect of the present invention, since the cushioning member is attached to the head-side end face of the piston using the attaching means, it is not necessary to cut a groove or the like for attaching the cushioning member to the piston. As a result, the shape of the piston can be simplified, so that the piston can be easily processed.

According to the second aspect of the present invention, since the cushioning member is sandwiched and supported by the mounting means and the piston, it is possible to reliably prevent the cushioning member from coming off from the head side end surface of the piston.

According to the third aspect of the present invention, the mounting means is disposed inside the annular buffer member, and the engaging portion formed on the outer peripheral edge thereof is engaged with the inner peripheral edge of the buffer member. The member can be accurately positioned at a predetermined position.

According to the fourth aspect of the present invention, since the head-side end surface of the piston has a flat shape without unevenness, a common piston can be used for a plurality of types of fluid pressure cylinders having different uses. be able to.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. As shown in FIG. 1, a fluid pressure cylinder 11 is a cylindrical cylinder tube 1.
2 is provided. Of the openings of the cylinder tube 12, the opening on the right side in FIG. 1 is closed by the head cover 15, and the opening on the left side is closed by the rod cover 16.

At the right end of the cylinder tube 12, a first
The fluid supply / discharge port 13 is formed. This port 13 communicates with the internal space of the cylinder tube 12 via a flow path 18. A second fluid supply / discharge port 14 is formed at the left end of the cylinder tube 12.
This port 14 communicates with the internal space of the cylinder tube 12 via the flow path 20.

A piston 25 is slidably accommodated in the inner space of the cylinder tube 12 along the longitudinal direction of the cylinder tube 12. The head-side end surface (the right end surface in FIG. 1) and the rod-side end surface (the left end surface in FIG. 1) of the piston 25 have flat shapes. Cylinder tube 1
The inner space 2 is divided into two pressure action chambers 27 and 28 by the presence of the piston 25. Air as a fluid is supplied to and discharged from the head-side pressure action chamber 27 through the first fluid supply / discharge port 13. On the other hand, air is supplied / discharged to / from the rod side pressure action chamber 28 via the second fluid supply / discharge port 14.

At the center of the piston 25, a small diameter portion formed at the inner end of the piston rod 26 is screwed. The outer end of the piston rod 26 passes through the rod insertion hole 21 formed in the rod cover 16 and
2 project outside. And the piston rod 26
Is slidably supported by the rod cover 16 via a bush 29 attached to the inner peripheral surface of the rod insertion hole 21. An annular rod packing 30 is mounted on the outer peripheral surface of the rod insertion hole 21. The rod packing 30 seals the peripheral surface of the piston rod 26 and the inner wall surface of the rod insertion hole 21.

An annular mounting groove 3 is formed on the outer peripheral surface of the piston 25.
3, a piston packing 24 having a cross-sectional shape of a bar is mounted inside. Also, piston 25
A wear ring 34 is mounted on the outer peripheral surface of the. The wear ring 34 is an incomplete annular member having a slit (not shown) in a part thereof. The slits are provided to facilitate the diameter expansion. In the wear ring 34, the outer peripheral surface functions as a sliding surface that is in sliding contact with the inner peripheral surface of the cylinder tube 12, and the inner peripheral surface functions as a non-sliding surface.

A cushion rubber 35 serving as an annular cushioning member is provided on the rod-side end surface and the head-side end surface of the piston 25.
a, 35b are provided. Each cushion rubber 35
The wall thickness in the vicinity of the central portion of each of a and 35b is smaller than the wall thickness of the outer peripheral portion. Then, the cushion rubbers 35a, 35
The boundary between the thin portion N1 and the thick portion N2 of b is tapered. The reason why the shape between the both meat portions N1 and N2 is tapered is to facilitate opening of the mold when the cushion rubbers 35a and 35b are injection-molded by the mold.

Cushion rubber 35a on rod-side end surface
The cushion rubber 35a is attached by press-fitting the piston rod 26 into the center portion of the cushion rubber 35a.
In this mounted state, the cushion rubber 35a is in contact with the rod-side end surface of the piston 25.

Cushion rubber 35b on the end face on the head side
Is provided with an annular cushion holder 36 made of urethane. A stepped engaging portion 36a is formed on the outer peripheral surface of the cushion holder 36, and the engaging portion 3a is formed.
6a is engaged with the inner peripheral portion of the cushion rubber 35b on the head side end surface, that is, the thin portion N1. The tip of a screw 37 that penetrates the center of the cushion holder 36 is screwed into the center of the small diameter portion of the piston rod 26, so that the cushion rubber 35b is sandwiched and supported between the piston 25 and the cushion holder 36. . Therefore, in the present embodiment, the cushion holder 36 and the screw 3
7, the cushion rubber 35 on the head side end surface
Mounting means for mounting b is configured.

The end face of the cushion holder 36 not in contact with the piston 25 and the end face of the screw 37 are located at substantially the same position as the end face of the cushion rubber 35b on the end face on the head side. That is, the cushion holder 36 and the screw 37 are
It does not protrude from the end face of the cushion rubber 35b on the end face on the head side. More specifically, the thick portion of the cushion rubber 35b is thicker than the thickness of the cushion holder 36. This is the cushion rubber 3 on the end face on the head side.
This is because the function as a cushioning member is ensured by ensuring that the end face of 5b is brought into contact with the inner end face of the head cover 15.

In FIG. 1, the thickness of the thick portion N2 of the cushion rubber 35b and the thickness of the cushion holder 36 are substantially the same because the piston 25 is located at the stroke end on the head side. Have been. Piston 25
Is located at a position other than the stroke end on the head side (not shown), the thickness of the thick portion N2 of the cushion rubber 35b is clearly larger than the thickness of the cushion holder 36 as described above.

Next, the operation of the piston structure of the hydraulic cylinder configured as described above will be described. When air is supplied to the first fluid supply / discharge port 13 in a state where the piston 25 is at the stroke end on the head side, air is introduced into the head side pressure action chamber 27, and the pressure in the chamber 27 rises. Then, the piston 25 and the rod 26 move in the direction of the rod side (the left side in FIG. 1), and the air in the pressure action chamber 28 on the rod side flows through the second fluid supply / discharge port 14 and the flow path 20. It is discharged outside. Then, when the piston 25 reaches the vicinity of the rod-side stroke end, the cushion rubber 3 on the rod-side end surface is moved.
5a hits the inner end face of the rod cover 16,
The inertial energy of the piston 25 is absorbed. As a result, the impact given by the piston 25 is reduced.

The piston 2 is provided at the stroke end on the rod side.
When air is supplied to the second fluid supply / discharge port 14 in a state where 5 is present, air is introduced into the rod-side pressure action chamber 28, and the pressure in the chamber 28 increases. Then, piston 2
5 and the rod 26 move in the direction of the head side (the right side in FIG. 1), and the air in the head side pressure action chamber 27 is discharged outside through the first fluid supply / discharge port 13 and the flow path 18. You. When the piston 25 reaches the vicinity of the stroke end on the head side, the cushion rubber 35b on the head side end surface hits the inner end surface of the head cover 15, so that the inertia energy of the piston 25 is absorbed. As a result, the impact given by the piston 25 is reduced.

Therefore, according to the present embodiment, the following effects can be obtained. (1) The cushion rubber 35b on the head-side end surface of the piston 25 is used as a cushion holder
And attached to the piston 25 by screws 37. Therefore, the cushion rubber 35b can be attached without the need to cut a groove or the like on the surface of the piston 25 in order to attach the cushion rubber 35b, so that the manufacturing cost of the piston 25 can be reduced. In addition, since the shape of the piston 25 can be simplified, machining can be facilitated and the versatility of the piston 25 can be enhanced.

(2) The means for attaching the cushion rubber 35b on the end face on the head side includes the cushion holder 36. The cushion rubber 35b on the head-side end face is sandwiched between the piston 25 and the cushion holder 36. Then, by tightening the screw 37 in this state, the cushion rubber 35b
Is pressed against the piston 25. Therefore, it is possible to reliably prevent the cushion rubber 35b from coming off from the head-side end surface of the piston 25.

(3) The cushion rubber 35b on the end face on the head side is formed in an annular shape, and a cushion holder 36 is disposed inside the cushion rubber 35b. And cushion rubber 35
In the state where b is mounted, the engaging portion 36a formed on the outer peripheral edge of the cushion holder 36 is engaged with the inner peripheral edge of the thin portion N1 of the cushion rubber 35b. Therefore, the center of the cushion rubber 35b on the end surface on the head side can be adjusted to the center position of the piston rod 26 (piston 25). Therefore, the cushion rubber 35 on the head side end surface
The mounting accuracy of the cushion rubber 35b can be improved while the mounting accuracy of the cushion rubber 35b can be improved.

(4) Since the head-side end face of the piston 25 has a flat shape without any irregularities, the piston 25 can be shared. As a result, the mass productivity of the piston 25 can be improved, and a plurality of types of fluid pressure cylinders 11 having different applications can be handled by the common piston 25.

(5) Since the material for forming each of the cushion rubbers 35a and 35b is made of polyurethane, a piston structure having excellent wear resistance, elasticity and mechanical properties can be obtained. The embodiment of the present invention may be modified as follows.

As shown in FIG. 2, the cushion holder 36 and the screw 37 are integrated, and the screw portion is
5 and the center position of the piston rod 26. According to this configuration, the cushion rubber 35b on the head-side end surface can be positioned at the same time as the cushion holder 36 is tightened. Therefore, the cushion rubber 35b on the head side end surface can be more easily assembled.

Cushion rubber 3 on the end face on the head side
5b, the piston 25 is tightened with a screw 37.
It was attached to. Alternatively, the cushion rubber 35b may be attached by providing a protrusion on the cushion holder 36 and fitting the protrusion into a recess formed on the end surface of the piston 25.

In the above embodiment, the cushion holder 36 is tightened with the screw 37. In addition to this method, for example, the cushion holder 36 may be formed using an adhesive.
May be fixed to the piston 25.

A notch may be formed on the outer peripheral edge of the cushion rubber 35b. With this configuration, the piston 2
When air is supplied from the first fluid supply / discharge port 13 to the head-side pressure action chamber 27 in a state where the nozzle 5 is at the head-side stroke end, the air is supplied to the pressure action chamber 27 through the cutout portion. It can be supplied smoothly inside. Therefore, the movement of the piston 25 can be performed smoothly.

Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments will be listed below together with their effects. (1) The piston structure of a fluid pressure cylinder according to any one of claims 1 to 4, wherein the buffer member is made of an elastic synthetic resin (for example, urethane rubber). With this configuration, the buffer member can be manufactured at low cost, and the durability of the buffer member can be improved.

(2) In a piston structure of a fluid pressure cylinder, a piston is provided in a cylinder tube so as to be able to reciprocate, and a buffer member is provided on at least one of a head end surface and a rod end surface of the piston. A piston structure for a fluid pressure cylinder, wherein a head side end surface and a rod side end surface are made flat. With this configuration, it is not necessary to prepare a piston having a different shape for each of a plurality of types of cylinders, and it is possible to use common components.

[0039]

According to the first aspect of the present invention, the piston can be easily processed, so that the cost can be reduced.

According to the second aspect of the present invention, it is possible to reliably prevent the cushioning member from coming off from the head-side end surface of the piston. According to the third aspect of the present invention, it is possible to improve the assembling accuracy of the cushioning member on the head side end surface of the piston.

According to the fourth aspect of the present invention, it is possible to cope with a plurality of types of fluid pressure cylinders having different uses with a common piston.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a hydraulic cylinder according to an embodiment.

FIG. 2 is a cross-sectional view of a hydraulic cylinder according to another embodiment.

FIG. 3 is a sectional view of a fluid cylinder according to the related art.

FIG. 4 is a cross-sectional view of a conventional fluid cylinder of a type different from FIG.

[Explanation of symbols]

11 ... fluid pressure cylinder, 12 ... cylinder tube, 25
... Piston, 26 ... Piston rod, 35a, 35b ...
Cushion rubber (buffer member), 36: cushion holder, 36a: engaging portion, 36: cushion holder (attaching means), 37: screw (attaching means).

Claims (4)

[Claims] 1. A piston structure of a hydraulic cylinder in which a piston and a piston rod integrated in a cylinder tube are reciprocally provided, and a buffer member is provided on at least a head-side end surface of the piston. A piston structure for a fluid pressure cylinder, comprising: mounting means for mounting to a head-side end surface of a piston. 2. The hydraulic pressure according to claim 1, wherein the attachment means is attached to a piston or a piston rod, and the buffer member is sandwiched and supported by the attachment means and the piston. Piston structure of cylinder. 3. The shock-absorbing member is formed in an annular shape, and the mounting means is disposed inside the shock-absorbing member, and an outer peripheral edge of the mounting means has an engaging portion for engaging with an inner peripheral edge of the shock-absorbing member. The piston structure of a hydraulic cylinder according to claim 1, wherein the piston structure is formed. 4. The piston structure for a hydraulic cylinder according to claim 1, wherein the head-side end surface of the piston has a flat shape.