JP2003322109A - Air cylinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the generation of a adhesion force between a piston and a bottom plate due to the surface tension of a lubricant and to remove the cause of an error in an initial operation of a cylinder by preventing the lubricant applied on a cylinder tube inner wall from sticking on the contact surface of the bottom plate, in a vertically placed air cylinder. <P>SOLUTION: In this air cylinder in which a piston 1 is reciprocated up and down within a cylinder tube 3, a lower portion not abutting on the piston 1 is formed on the circumference of a piston contact surface 14a of a bottom plate 4a with which the piston 1 reaching the lowest point is in contact, a lower portion working as a lubricant pool 12 storing the lubricant flowing down from the inner wall surface of the cylinder tube 3. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air cylinder, and more particularly to an air cylinder capable of preventing abnormal initial operation of a piston when a cylinder tube is used in a vertical type.

[0002]

2. Description of the Related Art As an example of a conventional air cylinder, as shown in the cross-sectional view of FIG. 4A and the perspective view of FIG. A piston 1 and a piston rod 2 fixed to the piston 1 are provided, and a cylinder tube 3 is closed at its upper and lower ends by a top plate 5 and a bottom plate 4, respectively. The
The bottom plate 4 is provided with a port 8 for introducing high-pressure air for raising the piston 1 in the central portion, and a port 9 for introducing high-pressure air for lowering the piston 1 is provided on the upper portion of the cylinder tube 3. There is. A seal packing 10 is fitted on the sliding surface of the piston 1 with the cylinder tube 3, and a seal packing 11 is fitted on the sliding surface of the upper plate 5 with the piston rod 2. Further, as disclosed in Japanese Patent Laid-Open No. 9-42219, the contact surfaces of the piston 1 and the bottom plate 4 are flat surfaces having the same area.

When a conventional air cylinder having such a structure is installed vertically and operated, high pressure air is first supplied from a port 9 to a hollow chamber 7 formed by a cylinder tube 3 and a piston 1. Send in. At this time, since the port 8 of the bottom plate 4 is switched to the exhaust hole, the hollow chamber 6 which is also formed by the cylinder tube 3 and the piston 1 is contracted and the piston 1 is pushed downward, so that the upper surface of the bottom plate 4 is depressed. It stops when it comes into contact with a certain piston contact surface 14. Subsequently, the port 9 is switched to the exhaust hole, high-pressure air is fed from the port 8, the hollow chamber 6 is expanded and the hollow chamber 7 is contracted, and the piston 1 is raised. in this way,
The piston is reciprocated up and down by alternately switching the port to the high pressure air introduction hole and the exhaust hole.

[0004]

In the conventional air cylinder as described above, the following problems occur especially when the cylinder tube is used in a vertical type. First, the lubricant applied to the inner wall of the cylinder tube leaks from the gap of the seal packing due to the vertical movement of the piston and flows down along the inner wall of the cylinder tube, and the lubricant that has flowed down begins to collect on the upper surface of the cylinder bottom plate. When the stroke of the piston reaches the lowest point, the piston and the bottom plate come into surface contact, but here the bottom plate only has a port hole in the center and the entire top surface of the bottom plate is flat, so the entire surface is the same. Contact with the flat piston surface of the same area without any gap.

As described above, since the conventional air cylinder originally has a structure in which the contact area between the piston and the bottom plate is large, the lubricant further enters the structure.
The surface tension of the lubricant makes it difficult for the cylinder bottom plate and the piston to come into close contact with each other and separate. Moreover, since the bottom plate and the piston are in intimate contact with each other over the entire surface, there is no hollow chamber at all, and the piston does not immediately start rising even when high-pressure air is fed from the port of the bottom plate. The generation of this adhesion force delayed the piston rising timing and caused an abnormal initial operation. In particular, when operating a manufacturing facility having a structure in which two cylinders are operated at the same time, a positional deviation after operation occurs due to the two cylinders being out of synchronization due to abnormal initial operation of the cylinders, which is a problem.

The present invention has been made to solve the above problems, and in a vertical air cylinder, the lubricant applied to the inner wall of the cylinder tube is prevented from adhering to the contact surface between the piston and the bottom plate. The purpose is to prevent the generation of the adhesion force between the piston and the bottom plate due to the surface tension of the lubricant, and to eliminate the cause of the abnormal initial operation of the cylinder.

[0007]

SUMMARY OF THE INVENTION The present invention is an air cylinder in which a piston reciprocates up and down in a cylinder tube, and a piston is provided in the periphery of the piston contact surface of the bottom plate of the cylinder tube with which the piston reaches the lowest point. A low portion that does not come into contact is provided, and this low portion is used as a lubricant reservoir for storing the lubricant that flows down from the inner wall surface of the cylinder tube.

Further, according to the present invention, a step portion is provided between the piston contact surface of the bottom plate and the lower portion, and the step portion serves as a barrier for preventing the lubricant from flowing into the piston contact surface of the bottom plate. It was done like this.

Further, according to the present invention, the bottom plate is provided with a two-step structure in which a circular convex portion serving as a piston contact surface is formed in the central portion thereof, and the circular convex portion is provided with a lubricant reservoir around the bottom plate. A ring-shaped groove formed by the stepped portion of the two-stage structure and the inner wall of the cylinder tube serves as a lubricant reservoir.

Further, according to the present invention, a ring-shaped convex portion serving as a piston contact surface is formed in the central portion of the bottom plate, and the outer wall step of the ring-shaped convex portion prevents the lubricant from flowing into the piston contact surface. A lubricant is provided around the ring-shaped protrusion as a barrier, and a ring-shaped groove formed by the outer wall of the ring-shaped protrusion and the inner wall of the cylinder tube is used as the lubricant reservoir.

Further, according to the present invention, in an air cylinder for vertically reciprocating a piston in a cylinder tube, the inner diameter of the cylinder tube which is substantially flush with the piston contact surface of the bottom plate with which the piston reaching the lowest point contacts To form a ring-shaped groove surrounding the piston contact surface of the bottom plate, and this ring-shaped groove serves as a lubricant reservoir for collecting the lubricant that flows down from the inner wall surface of the cylinder tube, and the groove bottom of this ring-shaped groove is the bottom plate. The position is lower than the piston contact surface of.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. 1A and 1B are views showing a first embodiment of the present invention, FIG. 1A is a sectional view of an air cylinder, and FIG. 1B is a perspective view of a bottom plate. The same parts as those of the conventional technique will be described using the same reference numerals.

As shown in FIGS. 1A and 1B, a vertical air cylinder used in the present invention includes a cylinder tube 3, a piston 1 which reciprocates up and down in the cylinder tube 3, and a piston 1. The cylinder tube 3 is closed at its upper and lower ends by an upper plate 5 and a bottom plate 4a, respectively, and a through hole through which the piston rod 2 penetrates is formed in the upper plate 5 and a bottom plate 4a is formed in the bottom plate 4a. A port 8 for introducing high-pressure air for raising the piston 1 is provided in the central portion, and a port 9 for introducing high-pressure air for lowering the piston 1 is provided at the upper part of the cylinder tube 3. A seal packing 10 is fitted on the sliding surface of the piston 1 with the cylinder tube 3, and a seal packing 11 is fitted on the sliding surface of the upper plate 5 with the piston rod 2.

When operating the air cylinder having such a structure, first, high pressure air is fed from the port 9 into the hollow chamber 7 formed by the cylinder tube 3 and the piston 1. At this time, since the port 8 of the bottom plate 4a is switched to the exhaust hole, the cylinder tube 3
The hollow chamber 6 formed by the piston 1 and the piston 1 is contracted, the piston 1 is pushed downward, and stops when it comes into contact with the piston contact surface 14a which is the upper surface of the bottom plate 4a. Subsequently, the port 9 is switched to the exhaust hole, high-pressure air is fed from the port 8, the hollow chamber 6 is expanded and the hollow chamber 7 is contracted, and the piston 1 is raised. In this way, the piston is reciprocally moved up and down by alternately switching the port to the high pressure air introduction hole and the exhaust hole.

Here, the shape of the bottom plate 4a in the present embodiment will be described. As shown in FIG. 1 (b), the bottom plate 4 a lowers the peripheral portion of the bottom plate 4 a, leaving a portion serving as the piston contact surface 14 a that comes into contact with the piston 1, and a circular convex portion serving as the piston contact surface 14 a around the port 8. It is formed in the center of the bottom plate. A step portion is provided between the piston contact surface 14a and a peripheral lower portion thereof, and the step portion serves as a barrier 13 which prevents the lubricant from flowing into the piston contact surface 14a of the bottom plate 4a. That is, since the bottom plate 4a has the two-step structure having the circular convex portion which becomes the piston contact surface 14a in the center thereof, the lubricant can be accumulated around the circular convex portion, and the bottom plate 4a is provided on the bottom plate 4a. A ring-shaped groove formed by the stepped portion of the two-stage structure and the inner wall of the cylinder tube 3 functions as the lubricant reservoir 12.

Next, a second embodiment of the present invention will be described. The present embodiment is the same as the first embodiment except for the shape of the bottom plate, and the description of the same parts will be omitted. As shown in the cross-sectional view of FIG. 2, the bottom plate 4b in the present embodiment has a piston contact surface 14 that contacts the piston 1.
A ring-shaped protrusion having b is formed. The ring-shaped protrusion is formed around the port 8 and the outer peripheral side wall thereof serves as a barrier 13, so that the lubricant flowing down the inner wall of the cylinder tube 3 flows into the piston contact surface 14b. It has a structure that prevents it from happening. That is, the bottom plate 4b has a ring-shaped groove formed by the outer peripheral side wall of the ring-shaped convex portion and the inner wall of the cylinder tube. By making this ring-shaped groove function as the lubricant reservoir 12, the piston contact surface 14 is formed.
It prevents the lubricant from flowing into b. According to the present embodiment, the area of the piston contact surface can be made smaller than that of the first embodiment, and the inside of the ring-shaped convex portion becomes a hollow chamber at the time of piston contact, so high pressure air is supplied from the port. When pushing, the piston can be pushed up with a larger force.

Next, a third embodiment of the present invention will be described. In the present embodiment, the shape of the bottom plate is the same as the conventional one in which the lowered piston is in contact with the entire upper surface of the bottom plate, and the lubricant reservoir is formed by processing a part of the cylinder tube. It is the one. Except for the cylinder tube, the structure is the same as the conventional one, and the description thereof is omitted.

That is, in the present embodiment, as shown in the cross-sectional view of FIG. 3, the inner diameter of the cylinder tube 3a is substantially flush with the piston contact surface 14 of the bottom plate 4 with which the piston that has reached the lowest point contacts. Is expanded to form a ring-shaped groove so as to surround the piston contact surface 14 of the bottom plate 4, and the expanded ring-shaped groove is used as the lubricant reservoir 12. The upper portion of the widened portion is tapered so that the lubricant can easily flow in. In addition, the bottom of the ring-shaped groove provided on the inner wall of the cylinder tube is formed so as to be located at a position lower than the piston contact surface 14 of the bottom plate 4 with which the piston contacts so that the lubricant does not flow into the piston contact surface 14. ing. In addition, the bottom plate 4 in the present embodiment
The shape is not limited to the conventional structure, and the 4a and 4b structures described in the first and second embodiments can also be used.

[0019]

As described above, according to the present invention, by providing the lubricant reservoir on the bottom plate, the lubricant applied to the inner wall of the cylinder tube flows into and adheres to the piston contact surface of the bottom plate. Can be prevented.
As a result, when the piston is raised, the problem that the piston and the bottom plate are in close contact with each other due to the surface tension of the lubricant and becomes difficult to separate is eliminated, and the initial operation abnormality of the air cylinder can be eliminated. In particular, in a manufacturing device having a structure in which two air cylinders are operated simultaneously,
Since the two synchronous deviations due to the abnormal initial operation of the air cylinder are eliminated, the positional deviation after the operation does not occur, which can contribute to the improvement of the operation rate of the apparatus and the improvement of the manufacturing yield.

[Brief description of drawings]

1A and 1B are diagrams illustrating a first embodiment of the present invention, FIG. 1A is a cross-sectional view of an air cylinder, and FIG. 1B is a perspective view of a bottom plate.

FIG. 2 is a partial sectional view of an air cylinder illustrating a second embodiment of the present invention.

FIG. 3 is a partial cross-sectional view of an air cylinder illustrating a third embodiment of the present invention.

4A and 4B are views showing an example of a conventional air cylinder, FIG. 4A is a sectional view of the air cylinder, and FIG. 4B is a perspective view of a bottom plate.

[Explanation of symbols]

1 piston 2 piston rod 3,3a cylinder tube 4, 4a, 4b Bottom plate 5 Upper plate 6, 7 Hollow chamber 8 and 9 ports 10, 11 Seal packing 12 Lubricant reservoir 13 barriers 14, 14a, 14b Piston contact surface

Claims (9)

[Claims] 1. In an air cylinder for vertically reciprocating a piston in a cylinder tube, a lower portion which does not come into contact with the piston is provided in a peripheral portion of a piston contact surface of a cylinder tube bottom plate with which the piston reaching a lowest point comes into contact,
An air cylinder characterized in that this lower part is used as a lubricant reservoir that stores the lubricant that flows down from the inner wall surface of the cylinder tube. 2. A step portion is provided between the piston contact surface of the bottom plate and the lower portion, and the step portion serves as a barrier for preventing the lubricant from flowing into the piston contact surface of the bottom plate. The air cylinder according to claim 1. 3. The bottom plate has a two-step structure in which a circular protrusion serving as a piston contact surface is formed in the center of the bottom plate, and the circumference of the circular protrusion serves as a lubricant reservoir.
Air cylinder described. 4. The air cylinder according to claim 3, wherein a ring-shaped groove formed by the stepped portion of the two-stage structure provided on the bottom plate and the inner wall of the cylinder tube serves as a lubricant reservoir. 5. A ring-shaped convex portion serving as a piston contact surface is formed in a central portion of the bottom plate, and a step of an outer wall of the ring-shaped convex portion serves as a barrier for preventing a lubricant from flowing into the piston contact surface. The air cylinder according to claim 2, wherein: 6. The air cylinder according to claim 2, wherein a ring-shaped convex portion serving as a piston contact surface is formed in the central portion of the bottom plate, and the periphery of the ring-shaped convex portion serves as a lubricant reservoir. 7. The air cylinder according to claim 6, wherein a ring-shaped groove formed by the outer wall of the ring-shaped protrusion and the inner wall of the cylinder tube serves as a lubricant reservoir. 8. In an air cylinder in which a piston reciprocates up and down in a cylinder tube, the inner diameter of the cylinder tube which is substantially flush with the piston contact surface of the cylinder tube bottom plate with which the piston reaching the lowest point contacts is widened. The air cylinder is characterized in that a ring-shaped groove is formed so as to surround the piston contact surface of the bottom plate, and the ring-shaped groove serves as a lubricant reservoir for storing the lubricant flowing down from the inner wall surface of the cylinder tube. 9. The air cylinder according to claim 8, wherein the groove bottom of the ring-shaped groove provided on the inner wall of the cylinder tube is located at a position lower than the piston contact surface of the bottom plate.