JPH02253003A - Nonlubricated fluid pressure cylinder - Google Patents

Abstract

PURPOSE:To obtain a nonlubricated fluid pressure cylinder with a high response speed by forming a composite film made of lubricating resin and hard oxidized aluminum on each of sliding surfaces of a cylinder tube and a piston rod whose base material is aluminum or aluminum alloy. CONSTITUTION:A cylinder tube 2 and a piston rod 4 are made of aluminum or aluminum alloy base material 23. A hard oxidized film 24 is formed on the base material 23. The hard oxidized film 24 is a porous film made of hard oxidized aluminum formed by anodic oxidation. The numerous file holes thereof are impregnated and coated with lubricating resin 25, such as fluorine, acetal or acrylic resin, and the resin is fused to form a composite film. It is thus possible to perform non-oil lubrication, thereby to improve durability and increase the response speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an oil-free hydraulic cylinder that does not require the conventional grease lubrication.

(Prior Art) Recently, oil-free hydraulic cylinders, which do not require frequent replenishment of lubricant, have been widely used because they have advantages such as easy handling and no need for a lubrication device.

Conventionally, for oil-free fluid pressure cylinders, a hard aluminum oxide film is formed on the inner peripheral surface of an aluminum cylinder tube by anodizing, and a hard chromium film is applied by plating on the outer peripheral surface of a carbon steel piston rod. The formed one is commonly used.

In such an oil-free fluid pressure cylinder, a piston seal is fitted around the outer periphery of the piston in order to maintain sealing between the piston and the cylinder tube.

In addition, the gland part of the piston rod is equipped with a dust wiper to prevent dust from entering the cylinder chamber, a rond packing to seal the cylinder chamber and the outside, and a bushing to receive the lateral load of the piston rod. is installed.

Therefore, the lubrication between the piston seal and the cylinder tube during cylinder operation, and the
Grease lubrication was used to lubricate the piston rod and the piston rod. That is, even though conventional oil-free hydraulic cylinders are oil-free, they still use grease as a lubricant to lubricate the sliding parts.

[Problem to be solved by the invention]

However, in the conventional oil-free hydraulic cylinder described above,
Grease may leak, and in such a case, lubrication failure may occur, and in the worst case, it may lead to accidents such as damage to the cylinder.

Furthermore, the leaked grease leaked out of the cylinder and became a source of contamination in the surrounding area.

Such environmental pollution must never occur in the food industry, where a beautification and hygiene of the manufacturing environment is particularly expected, and in the medical industry, where hygiene is strictly required.

Furthermore, nitrile rubber, which is commonly used for piston seals, rod seals, etc., may swell and deteriorate due to grease, and in such cases, there is a problem in that the nitrile rubber cannot sufficiently perform its function as a sealing member.

Furthermore, conventional cylinders use heavy piston rods made of carbon steel base material, and the inertia of the piston is large, resulting in drawbacks such as slow response speed.

Another problem has been pointed out: moisture contained in compressed air enters the many pinholes in the hard chrome coating, corrodes the carbon steel that is the base material of the piston rod, and shortens the life of the fluid pressure cylinder. Ta.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an oil-free hydraulic cylinder that does not require the use of grease and has a fast response speed.

[Means to solve the problem]

In order to solve all of the above-mentioned problems, the present invention provides lubricating resin by disposing it on the sliding surface instead of grease lubrication, and hard oxidized resin as the material for the piston rod and cylinder tube. An oil-free fluid pressure cylinder is constructed using aluminum or aluminum alloy that has been subjected to film treatment.

That is, the invention according to claim 1 provides an oil-free fluid pressure cylinder in which each sliding surface of the cylinder tube and piston rod, which is made of aluminum or an aluminum alloy as a base material, is made of a lubricating resin and hard aluminum oxide. A composite film is formed.

The invention according to claim 2 is the oil-free hydraulic cylinder according to claim 1, in which the lubricating resin is a synthetic resin selected from fluorine resin, acetal resin, and acrylic resin. It is composed of

[For production]

The lubricating resin in the composite film formed on the sliding surface of the aluminum cylinder tube acts as a lubricant for sliding friction of the cylinder tube, and the composite film formed on the sliding surface of the aluminum piston rod acts as a lubricant for sliding friction of the cylinder tube. The lubricating resin in the body film acts as a lubricant for sliding friction of the piston rod.

[Example] Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

FIG. 1 is a cross-sectional front view of an oil-free fluid pressure cylinder according to the present invention.

In FIG. 1, a pneumatic cylinder 1 includes a cylinder tube 2, a piston 3 that slides inside the cylinder tube 2, a piston rod 4 that is connected to the piston 3 and outputs the reciprocating motion of the piston 3, and both end surfaces of the cylinder tube 2. The seal 7 is made of a hard elastic member (for example, hard polyurethane) that is integrally formed with a head cover 5 and a rod cover 6 that close the head cover 5, a bushing, a rod packing, and a dust wiper.

Cushion posts 89 are provided on both sides of the piston 3, a sliding wear ring 31 made of synthetic resin is attached to the outer peripheral surface of the piston 3, and a piston gasket 33 for sealing is fitted on the outside.

A cushion hole 10 into which the cushion boss 8 should fit is formed in the head cover 5, and a cushion hole 10 is formed at the entrance of the cushion hole 10 so that the space between the cushion boss 8 and the cushion hole 10 is sealed during the cushioning process. Kunjong Patsukin 12 is installed.

Similarly, a cushion hole 11 into which the cushion boss 9 is inserted is formed in the rod cover 6, and at the entrance of the cushion hole, the space between the cushion boss 9 and the cushion hole 11 is sealed during the cushioning process. Cushion pan V-13 is attached so that it appears.

The head cover 5 and the rod cover 6 are provided with air inlets and outlets 14 and 1.5, respectively, which communicate the cushion holes 10.11 with external piping (not shown).

Further, the cushion chamber 21 formed between the piston 3 and the hendockher 5 is configured to communicate with the cushion hole 10 via the cushion flow path 16 during the cushioning process.

Similarly, the cushion chamber 22 formed by the piston 3 and the rod cover 6 is also configured to communicate with the cushion hole 11 via the cushion passage 17. Although not shown, check valves are provided in parallel with each cushion flow path 16, 17.

The cylinder tube 2 is made of an aluminum or aluminum alloy base material, and a composite film of a lubricating resin and hard aluminum oxide is formed on the inner peripheral surface using a conventionally known surface modification method. .

The piston rod 4 is also made of aluminum or an aluminum alloy base material, and a composite coating similar to that described above is also formed on its outer peripheral surface by the same method.

FIG. 2 is a schematic cross-sectional view of the sliding surfaces of the cylinder tube 2 and piston rod 4.

In FIG. 2, a hard oxide film 24 is formed on a base material 23 made of aluminum or an aluminum alloy. The hard oxide film 24 is a porous film formed by anodic oxidation, and its countless pores (pinholes) are impregnated and coated with a lubricating resin 25 and then fused. The entire membrane is constructed as one composite skin.

The thicker the composite film, the longer the life of the pneumatic cylinder. It may be formed to have an appropriate thickness depending on the desired durability. The required thickness of the composite film varies depending on the cylinder specifications and operating conditions, but - for boat fishing,
It is formed to have a thickness of 5 to 50 μm. Usually, it is about 20 μm in the case of a cylinder tube, and about 50 μm in the case of a piston rod.

As the above-mentioned resin having lubricating properties, conventionally known resins that can be melted by heat of compression and exhibiting lubricating properties can be used. Examples include various synthetic resins such as fluorocarbon resins, acetal resins, and acrylic resins.

Examples of commercially available fluorocarbon resins include polytetrafluoroethylene (manufactured by Dekobon Co., Ltd., trade name "Teflon").

Moreover, Duracon (trade name) is mentioned as a commercially available acetal resin.

These lubricating resins may be used alone or in combination of two or more. The composite ratio of the resin to the hard aluminum oxide film may be set depending on the shape, structure, dimensions, etc. of the cylinder.

In addition, by anodizing aluminum or aluminum base material to form a hard aluminum oxide film, and sealing the countless pores generated in the film using a fluorine-based resin, resin-impregnated hard aluminum oxide film is produced. Materials in which an aluminum film is formed on the surface of an aluminum base material (or its treatment) are commercially available (manufactured by Nippon Shinku Gijutsu Co., Ltd., trade name "Tafram", etc.), so if this is molded, the present invention can be easily achieved. It is possible to obtain such a member for an oil-free fluid pressure cylinder. In addition, although the film formation method has not been published at present, there is a material on the market in which a composite film made of acrylic resin and hard aluminum oxide is formed on an aluminum base material (manufactured by Taiyo Soken Co., Ltd., product name: “Tafko I
・”) Therefore, it is also possible to use this material.

In the present invention, the materials of other members other than the cylinder tube and piston rod, such as the materials of the seal 7, the wear ring 31, etc., are not limited at all.

However, in consideration of compatibility with the resin blended into the hard aluminum oxide film, such as lubricity, synthetic resin is preferable as the material for sliding materials such as the sole 7 and the wear ring 31, and among them, synthetic resin has excellent abrasion resistance. Particularly preferred are urethane resins and polytetrafluoroethylene resins.

There is no difference in the operation of the pneumatic cylinder 1 having the above configuration from that of a conventional pneumatic cylinder. That is, in FIG. 1, when compressed air is flowed into the cylinder tube 2 from the air inlet/outlet 14 provided in the head cover 5 and pressure is applied to the piston 3, the piston 3 moves due to the force, and the piston rod 4 moves in the protruding direction. Moving. Next, the introduced compressed air is released from the air inlet/outlet 14, and the air inlet/outlet 1 provided in the rod cover 6 is opened.
When compressed air is poured into the cylinder tube 2 from 5,
The piston 3 moves in the opposite direction to the front, and the piston rod 4 retracts.

In the above-described embodiment, instead of the seal 7, a bush, a rod packing, and a dust wiper may be provided separately.

In the present invention, the structure, shape, material, etc. of the pneumatic cylinder may be various other than those described above, and the present invention may also be applied to fluid pressure cylinders other than pneumatic cylinders, such as hydraulic cylinders. Of course.

[Effects of the Invention] According to the oil-free hydraulic cylinder according to the present invention, the lubricating resin acts as a lubricant, so there is no need to use grease. Therefore, there is also no risk of contaminating the surrounding area due to grease leakage.

Also, since lightweight aluminum ram is used as the material for the piston rod, response speed is fast.

Furthermore, as a cylinder tube and piston rod,
Since the sliding surface is made of a passivated material, it is less likely to rust and has excellent durability.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional front view of an oil-free fluid pressure cylinder according to the present invention, and the second figure is a schematic cross-sectional view of a sliding surface portion of a cylinder tube and a piston rod. 1...Pneumatic cylinder (fluid pressure cylinder), 2...
Cylinder tube, 4... Piston rod, 23 Aluminum or aluminum alloy base material, 24... Hard oxide film (composite film), 25... Resin having lubricating properties.

Claims (2)

[Claims] (1) Each sliding surface of the cylinder tube and piston rod, whose base material is aluminum or aluminum alloy,
An oil-free fluid pressure cylinder characterized by having a composite film formed of a lubricating resin and hard aluminum oxide. (2) The oil-free fluid pressure cylinder according to claim 1, wherein the resin having lubricating properties is a synthetic resin selected from fluorine resin, acetal resin, and acrylic resin.