JP3780040B2 - Fluid pressure cylinder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fluid pressure cylinder in which a piston is attached to a rod in a floating state.
[0002]
[Prior art]
When the rod is eccentric with respect to the cylinder hole due to an eccentric load or the like, the known fluid pressure cylinder with the piston fixed to the tip of the rod may bite the cylinder hole. May cause malfunction.
In order to solve this problem, Japanese Utility Model Laid-Open No. 5-40602 has proposed a hydraulic cylinder in which a piston is attached to the tip of a rod in a floating state.
[0003]
As shown in FIG. 5, the fluid pressure cylinder 1 includes a nut 3 that is provided with a piston 3 with a radial clearance t1 provided at a reduced diameter portion 2a at the tip of a rod 2 and screwed to a male screw at the tip of the reduced diameter portion 2a. An axial clearance t2 is provided between the piston 4 and the piston 3, and the radial clearance t1 between the rod 2 and the piston 3 is sealed by an O-ring 5 provided on the inner peripheral surface of the piston 3. 3 and the cylinder tube 6 are sealed by a piston packing 7 fitted to the outer peripheral surface of the piston 3.
Reference numeral 8 in FIG. 5 is a damper attached to both sides of the piston 2, and 9 is a head cover.
[0004]
In this fluid pressure cylinder, since the piston 3 is attached to the rod 2 in a floating state by the radial clearance t1 and the axial clearance t2, even if the rod 2 is eccentric due to an eccentric load or the like, the cylinder tube by the piston 3 is used. 6 galling can be prevented.
However, in this fluid pressure cylinder, there is a lack of consideration for the mounting of the piston. Since the piston 3 is mounted by the nut 4 screwed to the male screw at the tip of the rod 2, the mounting of the piston is troublesome. Further, since the axial clearance t2 is set by the nut 4 screwed to the rod 2, the setting is troublesome, and the nut 4 may be loosened to change the clearance t2.
[0005]
In order to solve these problems, it is conceivable to attach the piston 3 to the reduced diameter portion 2a of the rod by a retaining ring. However, since the diameter of the reduced diameter portion 2a to which the piston 3 is attached is small, the strength of the retaining ring and the groove into which the retaining ring is fitted is reduced, so that the piston is omitted from illustration at the end of the left moving stroke in the drawing. When it collides with the cover, the retaining ring and the groove may be damaged by this impact, and even if the damper 3 is provided on the piston 3, it is difficult to eliminate the damage to the retaining ring and the groove.
[0006]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to provide a fluid pressure cylinder that can be easily attached to a piston rod in a floating state and set in an axial clearance.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, a fluid pressure cylinder according to the present invention is a fluid pressure cylinder comprising a cylinder body, a piston that airtightly slides in a cylinder hole of the cylinder body, and a rod thereof. A mounting rod having a radial flange and an axial piston mounting portion is attached to the piston mounting portion, and a piston is mounted with a radial clearance between the piston mounting portion and the piston mounting portion. The piston is attached to the piston mounting portion by a retaining ring fitted in the groove on the tip outer peripheral surface of the piston mounting portion with an axial clearance, and the radial clearance between the cylinder hole and the piston is attached to the piston. In addition to sealing with packing, the radial clearance between the piston and mounting rod is sealed with packing. It is characterized in that the Le.
[0008]
In order to solve the same problem, a flange and a piston mounting portion are integrally formed at the tip of the rod in place of the mounting rod in the fluid pressure cylinder.
[0009]
Furthermore, in order to solve the same problem, the cylinder bodies of these fluid pressure cylinders have a plurality of cylinder holes formed in parallel, and a plurality of piston rods that slide in these cylinder holes are disposed outside the cylinder body. It is characterized by being connected by a connecting plate so that it can move integrally.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 show a first embodiment of the present invention. A cylinder body 12 of the fluid pressure cylinder 11 is provided with two cylinder holes 13 and 13 formed in parallel to the axial direction. The head cover 14 and the rod cover 15 that close both ends in the axial direction are attached to the cylinder holes by retaining rings 16. A ball bush 17 for guiding the movement of the rod, which will be described later, is provided inside the rod cover 15.
[0011]
A mounting rod 22 is screwed to the tip of the rod 21 of the piston 20 that slides in the cylinder hole 13. As shown in detail in FIG. 2, the mounting rod 22 includes a screwing portion 22 a to be screwed into the screw hole of the rod 21, a piston mounting portion 22 b having the same diameter as the screwing portion 22 a, and a smaller diameter than the piston 20 therebetween. The piston 20 is mounted on the piston mounting portion 22b with a radial clearance t1. In addition, the piston 20 having one side abutted against the flange 22c has an axial clearance t2 between the other side and a retaining ring 23 fitted in a groove on the outer peripheral surface of the piston mounting portion 22b. Yes. Therefore, the piston 20 is attached to the attachment rod 22 so as to be slightly swingable, that is, in a floating state, by these clearances t1 and t2.
The radial clearance t1 is sealed by U-shaped packings 24, 24 that are inserted into grooves on the outer peripheral surface of the piston mounting portion 22b and whose openings face each other. A radial clearance t3 between the piston 20 and the cylinder hole 13 is sealed by a piston packing 25 fitted in a groove on the outer peripheral surface of the piston 20.
[0012]
The movement of the rod 21 is guided by the ball bush 17, and the outer peripheral surface is sealed by the rod packing 27 provided on the rod cover 15. The two rods 21 and 21 are connected to the connecting plate 28 outside the cylinder body 12. Are moved together.
In the figure, the cylinder chamber 29a on the head side and the cylinder chamber 29b on the rod side defined by the upper piston 20 communicate with ports 30a and 30b formed in the cylinder body 12, respectively, and are defined by the lower piston 20. 29a and 29b (both not shown) communicate with the corresponding cylinder chambers through communication holes 31a and 31b provided in the partition wall 12a of the cylinder body 12, respectively.
[0013]
A damper 32a is attached to the surface of the cylinder body 12 facing the connecting plate 28 so that the protruding length can be adjusted, and a damper 32b is provided on the surface of the ball bush 17 facing the piston 20.
2 is a magnet for detecting the position of the piston 20, and reference numerals 35,... In FIG. 1 are mounting holes for a fluid pressure cylinder provided in the cylinder body 12 and the connecting plate 28.
[0014]
In the first embodiment, when compressed air is supplied and discharged from the ports 30a and 30b to the upper cylinder chambers 29a and 29b, the compressed air is supplied and discharged to the lower cylinder chambers 29a and 29b through the communication holes 31a and 31b. Therefore, the pistons 20 and 20 and the rods 21 and 21 reciprocate together. In this case, the lip of the U-shaped packings 24 and 24 is tightly sealed to the piston 20 and the piston mounting portion 22a by the air pressure supplied to the cylinder chambers 29a and 29b, so that the compressed air leaks from the radial clearance t1. Never do.
When the piston 20 moves to the right in the figure, it is buffered by the damper 32a, and when it moves to the left in the figure, it is buffered by the damper 32b.
The impact at the end of the rightward movement stroke of the piston 20 acts on the piston mounting portion 22b of the mounting rod 22, and the impact at the end of the leftward movement stroke of the piston 20 acts on the flange 22c of the mounting rod 22, in either case the piston 20 Since it does not act on the retaining ring 23 to which is attached, even if the retaining ring 23 has a small diameter and a low strength, it will not be damaged.
In this case, since the retaining ring 16 to which the rod cover 15 is attached has a larger diameter than the retaining ring 23 to which the piston 20 is attached, the retaining ring 16 may have a strength that can withstand an impact at the end of the left moving stroke of the piston 20. it can.
[0015]
Since the piston 20 is attached to the rod 21 by the retaining ring 23, the piston 20 can be easily attached to the rod 21, and the axial clearance t2 is set differently from the axial clearance set by the nut. It is reliable and easy, and since there is no loosening of the nut, the axial clearance does not change even when used for a long time.
Even if the cylinder hole 13 and the piston 20 are slightly decentered, the piston 20 does not bite the cylinder hole 13 because the piston 20 is attached to the rod 21 in a floating state, and the rod 21 is decentered with respect to the rod packing 27. Therefore, the amount of dust generated due to wear of the rod packing 27 can be reduced.
Further, even if the rod 21 is inclined due to an eccentric load or the like, the piston 20 swings with respect to the rod 21, so that the piston 20 does not bite the cylinder hole 13, and the radial clearance even if the piston 20 swings. t 1 is sealed by U-shaped packings 24, 24.
Therefore, the cylinder hole 13 is not easily squeezed and the rod packing 27 is less worn, so that the life of the fluid pressure cylinder is long and the amount of dust generated is small, so that it can be used in a clean room.
[0016]
FIG. 3 shows a second embodiment of the present invention. In the rod 38 in the second embodiment, a flange 38a is formed near the tip, and a piston mounting portion 38b is integrally formed at the tip by forging or the like.
In the second embodiment, since it is not necessary to thread the rod 38, the rod can be formed more easily.
Since the other configurations and operational effects of the second embodiment are the same as those of the first embodiment, the same reference numerals are assigned to the same main portions in the drawing, and detailed description thereof is omitted.
[0017]
FIG. 4 is a diagram showing the relationship between the number of operations and the dust generation concentration of a conventional fluid pressure cylinder in which a piston is fixed to a rod and a fluid pressure cylinder of the present invention in which the piston is attached to a rod in a floating state. As is apparent from FIG. 4, the fluid pressure cylinder of the present invention can significantly reduce the dust generation concentration.
Note that each of the illustrated embodiments is a twin rod cylinder in which two cylinder holes and two rods are provided in parallel, but the fluid pressure cylinder of the present invention is not limited to this. The fluid pressure having a cylinder hole and one rod can be obtained.
[0018]
【The invention's effect】
In the fluid pressure cylinder of the present invention, since the piston is attached to the rod in a floating state by a retaining ring, it is easy to attach the piston to the rod in a floating state and set the axial clearance, and it is used for a long time. However, the axial clearance is constant and does not change.
Further, by providing a separate or integral flange on the rod, the impact at the end of the stroke toward the rod is received by the flange and is not transmitted to the piston, so that the retaining ring to which the piston is attached can be prevented from being damaged.
Further, since the amount of dust generated is small due to less wear of the rod packing due to the eccentricity of the rod, it can be used in a clean room.
[Brief description of the drawings]
FIG. 1 is a half longitudinal sectional plan view of a first embodiment.
FIG. 2 is a cross-sectional view of the main part of the same.
FIG. 3 is a cross-sectional view of a main part of a second embodiment.
FIG. 4 is a comparison diagram of dust generation amount.
FIG. 5 is a cross-sectional view showing a main part of a known fluid pressure cylinder.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Fluid pressure cylinder 12 Cylinder body 13 Cylinder hole 20 Piston 21,38 Rod 22 Mounting rod 22b, 38b Piston mounting part 22c, 38a Flange 23 Retaining ring 24 U-shaped packing 25 Piston packing

Claims (3)

In a fluid pressure cylinder comprising a cylinder body, a piston that slides airtightly in a cylinder hole of the cylinder body, and a rod thereof,
Attach a mounting rod having a radial flange and an axial piston mounting portion to the tip of the rod,
The piston mounting portion is provided with a radial clearance between the piston mounting portion and the piston, and the piston is fitted in a groove on the outer peripheral surface of the piston mounting portion with an axial clearance. attached to the piston mounting portion by wearing the snap ring,
The radial clearance between the cylinder hole and the piston is sealed by the piston packing attached to the piston, and the radial clearance between the piston and the mounting rod is sealed by the packing,
A fluid pressure cylinder characterized by that. Instead of the mounting rod, a flange and a piston mounting part were integrally formed at the tip of the rod.
The fluid pressure cylinder according to claim 1. The cylinder body is provided with a plurality of cylinder holes formed in parallel, and a plurality of piston rods that slide through the cylinder holes are connected so as to be integrally movable outside the cylinder body,
The fluid pressure cylinder according to claim 1 or 2, wherein the fluid pressure cylinder is provided.

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