JP2000120871A - Carbon made piston ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a good sliding characteristic in which there is no sticking phenomenon of an aluminum made cylinder by forming a carbon made piston ring of a carbon material formed by impregnating resin on a carbon base material setting an open porosity to a specified value. SOLUTION: In a place having a high humidity, there is such a trend that corrosion caused by galvanic action is generated by water drops which is in dew condensation in inner surfaces of a carbon made piston and an aluminum made cylinder. When the corrosion is developed, the piston ring and the cylinder are sticked to each other. The piston ring is formed of a carbon material formed by impregnating resin on a carbon base material whose open porosity is not more than 15%, and thereby, the carbon made piston ring is prevented from sticking to the aluminum made cylinder. In an air type braking device for a sliding door closer, the piston ring is interposed between an aluminum pipe 5 arranged on an outside as a cylinder and an aluminum pipe 4 arranged on an inside as a piston rod, and is suitably used as a piston ring 1 fixed to the aluminum pipe 4 arranged on an inside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon piston ring, and more particularly to a carbon piston ring suitable for a pneumatic braking device for a sliding door closer having an aluminum cylinder pipe and a carbon piston ring.

[0002]

2. Description of the Related Art In the case of a sliding door closer which automatically closes a suspended sliding door by a force of a spring or the like, a pneumatic braking device is provided to close the door softly. In general, in this pneumatic braking device, a pipe provided with a carbon piston ring slides in an aluminum cylinder pipe and compresses air in the aluminum cylinder pipe to generate a braking force. However, if left unused for a long time, there is a problem that some carbon piston rings and aluminum cylinders are stuck and do not operate.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a carbon piston ring having excellent sliding characteristics without sticking phenomenon.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above-mentioned situation, and as a result, in a humid place, the battery action was caused by water droplets condensed on the inner surface of a carbon piston ring and an aluminum cylinder. Corrosion may occur, and if this corrosion progresses, it is found that the carbon piston ring and the aluminum cylinder are stuck and do not operate. Further, the carbon base material having an open porosity of 15% or less is impregnated with a resin. It has been found that using a carbon piston ring made of carbon material makes it impossible for the aluminum cylinder to stick. The present invention has been completed based on these findings.

That is, the present invention relates to a carbon piston ring made of a carbon material obtained by impregnating a carbon base material having an open porosity of 15% or less with a resin.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As the carbon base material used in the present invention, those used as bearings and seals as general carbon sliding materials are preferable. That is, a carbon base material obtained by adding a binder such as coal tar and tar pitch to an aggregate such as coke powder, graphite powder, and carbon black, and kneading, pulverizing, molding, and baking can be used.
There is no particular limitation on the usage ratio of the aggregate and the binder, but the binder is preferably used in an amount of 60 to 120 parts by weight based on 100 parts by weight of the aggregate.

However, the open porosity of the carbon substrate used in the present invention needs to be 15% or less, and preferably 13% or less. With a carbon base material having an open porosity of more than 15%, it is difficult to close the pores by a single resin impregnation. Further, when the open porosity is larger than 15%, the pore diameter increases, and when the resin shrinks during curing after resin impregnation, pores remain. As a result, moisture penetrates into the pores, forming corrosive substances and causing cylinder sticking.

In the production of the carbon substrate used in the present invention, the heat kneading is generally carried out by using a double-armed kneader or the like, and the respective materials such as aggregates and binders are preferably used in an amount of 180 to 3 times.
It can be performed by heating and kneading at 00 ° C.

The pulverization is performed by pulverizing the material obtained by heating and kneading using various types of pulverizers, preferably so as to have an average particle size of 10 to 30 μm. The compacting is performed by packing the powder obtained by the pulverization in a mold or the like, and forming it into a block by a hydraulic press or the like, preferably at a pressure of 800 to 1200 kg / cm ² . The firing is performed by raising the temperature to preferably 800 to 1200 ° C. in a reducing atmosphere. Here, the heating time is 300 to 5
00 hours is preferred. As a method of raising the temperature in a reducing atmosphere, there is a method of packing carbon powder around a molded body.

The open porosity of the carbon substrate is adjusted to 15% or less by appropriately adjusting the amount of the binder.

The carbon substrate thus obtained is impregnated with a resin. The amount of the resin impregnated is preferably at least 3% by weight, more preferably at least 5% by weight, based on the carbon substrate. Although there is no particular upper limit, it is generally 20% by weight or less due to the structure of the carbon substrate.

The type of the resin is not particularly limited, and may be a thermosetting resin or a thermoplastic resin. As thermosetting resin,
Phenol resin, epoxy resin, unsaturated polyester resin, furan resin, melamine resin, alkyd resin, xylene resin, polycarbodiimide resin and the like can be mentioned, and as the thermoplastic resin, acrylic resin and the like can be mentioned. Also, a mixture of these resins can be used. Preferred resins include phenolic resins, furan resins, epoxy resins and the like.

A curing agent is used according to the type of the thermosetting resin. Examples of the curing agent include inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid; organic sulfonic acids such as p-toluenesulfonic acid and methanesulfonic acid; and carboxylic acids such as acetic acid, trichloroacetic acid, and trifluoroacetic acid. When using a curing agent, it is preferable to use 0.001 to 20% by weight depending on the thermosetting resin.

There is no particular limitation on the method of impregnating the carbon base material with the resin. There are no particular restrictions on the method of putting the carbon base material and the resin in a pressure vessel and impregnating the carbon base material by applying pressure. A method of impregnation can be used.

Since the resin is impregnated in a solution state, when the resin is not liquid or has a high viscosity, it is dissolved in a solvent and used for impregnation. The solvent is not particularly limited, and alcohols such as methanol, aromatic hydrocarbon solvents such as toluene and xylene, and the like can be used. The amount of the solvent used is not particularly limited, and can be adjusted, for example, in the range of 5 to 95% by weight in terms of solid content.

The shape of the carbon substrate to be impregnated with the resin is not particularly limited, and the carbon black obtained by molding may be used as it is. However, in order to perform the impregnation sufficiently, a round having a necessary outer diameter as a piston ring is used. It is preferable to impregnate in a state of being machined into a rod shape, a ring shape, the shape of the piston ring itself, or the like.

When the resin is applied and impregnated,
It is preferable to apply it to the entire surface of the piston ring.

Although the shape of the piston ring in the present invention is not particularly limited, it generally has a circular ring shape, a cylindrical shape or the like.

The size is not particularly limited. For example, when used in an air-type braking device such as a sliding door closer, the outer diameter is 1 mm.
A cylindrical shape having a length of 0 to 50 mm, a length of 10 to 50 mm, and a thickness of 1 to 5 mm may be used.

FIG. 1 is a partial cross-sectional view of an example of a cylinder of a pneumatic braking device of a sliding door closer equipped with a carbon piston ring of the present invention. In FIG. 1, a piston ring 1 is fixed to an inner aluminum pipe 4 by an O-ring 2 and a stop washer 3, and slides between the outer aluminum pipe 5 and the outer ring. If the piston ring made of carbon of the present invention is used, it is possible to maintain a good sliding state without the piston ring 1 and the aluminum pipe 5 being fixed.

[0021]

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 Tar pitch was added to 60 parts by weight, 80 parts by weight, 100 parts by weight, and 140 parts by weight based on 40 parts by weight of pitch coke powder having an average particle size of 15 μm and 60 parts by weight of a homemade graphite powder having an average particle size of 12 μm. , And kneaded at 180-200 ° C with a double-arm kneader, and then allowed to cool. These four types of kneaded materials were each pulverized to obtain a 20 μm molded powder.

This molding powder is molded by a hydraulic press at a molding pressure of 1 ton / cm ² , and the molded product obtained is reduced to 10
The temperature was raised to 00 ° C. for 450 hours and calcination was performed to obtain a carbon substrate having the characteristics shown in Table 1.

The bending strength was 10 mm thick and 10 mm wide.
mm, length 50 mm rectangular parallelepiped test piece JCAS
(Carbon Institute Standard) measured in accordance with -10-1968,
Hardness was measured with a Shore hardness tester.

The open porosity is calculated from the apparent volume obtained from the weight in the atmosphere and water and the true volume obtained from the weight in water when the pores of the carbon substrate are replaced with water in a reduced-pressure atmosphere. It was determined as in the following equation.

[0026]

(Equation 1) Next, the carbon substrate was machined to obtain six round bars having an outer diameter of 30 mm. Five of these were placed in a pressure vessel equipped with a valve, the pressure in the vessel was reduced, the valve was opened, and the resin impregnation amount of the phenol resin (Sumilite Resin PR50273 manufactured by Sumitomo Durez Co., Ltd.) was targeted. The impregnating solution (methanol amount: 10% by weight) diluted with methanol was injected into the pressure vessel to impregnate the resin. Thereafter, the temperature is raised to 250 ° C. for 15 hours to cure,
A carbon material having a resin impregnation amount shown in Table 1 was obtained.

[0027]

[Table 1] A part of the sample shown in Table 1 was processed into an inner diameter of 24 mm and a length of 25 mm, and each was manufactured into three carbon piston rings, and set in an aluminum cylinder at 80% humidity and at temperatures of 40 ° C and 15 ° C. The repetition was repeated 100 times, and the state of adhesion was examined. As a result, Samples 2 to 4 exhibited good slidability without any sticking, and were extremely useful in practice. In addition, the sample 1 is a case where the carbon substrate has an open porosity exceeding 15%, and the sample 5 is a case where the sample 3 which is not impregnated with the resin is used.

[0028]

According to the present invention, it is possible to provide a carbon piston ring having excellent sliding characteristics without sticking to an aluminum cylinder.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of an example of a cylinder of a pneumatic braking device of a sliding door closer equipped with a carbon piston ring of the present invention.

[Explanation of symbols]

 Reference Signs List 1 piston ring 2 O-ring 3 stop washer 4 aluminum pipe (inside) 5 aluminum pipe (outside)

Claims (1)

[Claims] 1. A carbon piston ring made of a carbon material obtained by impregnating a resin into a carbon base material having an open porosity of 15% or less.