JP3139692B2 - Gas cock - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for preventing a sliding portion between a gas cock main body and a plug body from galling, thereby improving durability and operability.

[0002]

2. Description of the Related Art Generally, a gas cock accommodates a plug in a plug housing chamber formed in a gas flow path of a main body, and opens and closes the gas flow path by rotating the plug with an operation shaft. Grease is applied to the sliding surface between the plug housing chamber and the plug, and the airtightness of the sliding surface is secured by a thin film of grease. However, the grease thin film may be broken due to the number of rotations of the plug, temperature change, deterioration of the grease, and the like with the passage of time, and the plug may be stuck and the rotation torque may increase, making the rotation impossible. Was. Therefore, in many cases, the cock body is generally made of iron and the plug body is made of a copper alloy.

In Japanese Patent Application Laid-Open No. 57-40170, a sliding face of a gas cock which has been precisely turned is finished to an appropriate roughness by bead blasting, liquid honing, or the like, and then Ni is removed by electroless plating. -Forming a P plating film to obtain a porous plating film, lapping the sliding surface, washing and drying, and applying grease mixed with low friction fine particles such as tetrafluoride resin to the sliding surface. A coating is disclosed.

[0004] Ni-P plating is sufficiently harder than the hardness of cast iron or copper alloy casting forming the cock body. In the case where the Ni-P plating film is formed on only one of the main body and the plug, since the sliding portion has a difference in hardness, the phenomenon of galling is reduced. In addition, the grease contains fine particles with low friction, so that the sliding portion has good slip and the plug can be rotated with low torque.

[0005]

However, in the above prior art, Ni-P plating is sometimes formed on both the main body and the plug, and the phenomenon of galling has not been solved. In addition, the grease film becomes thinner gradually due to repetition of a rotating operation or a temperature change due to direct sunlight at a piping location, and the film is destroyed if the grease is accelerated in deterioration.
Particularly, when the material of the main body and that of the plug are different, the thermal expansion coefficients thereof are also different, so that there is no gap between the sliding portions, and the destruction of the grease film is remarkably promoted. The grease is mixed with low friction fine particles, and these fine particles are present in the pores of the Ni-P plating film (actually, in the pores formed because the base is finished by bead blasting or the like). Even if retained, the fine particles cannot secure the sealability of the sliding portion and cannot maintain the sealability for a long period of time. SUMMARY OF THE INVENTION The present invention provides a gas cock that retains rotational operability and sealability for a long period of time even under severe use conditions.

[0007]

SUMMARY OF THE INVENTION The gist of the present invention is to provide a gas cock in which a stopper rotatable by an operation shaft is accommodated in a stopper housing chamber of the gas cock body, wherein the gas cock body and the stopper are made of the same material. Forming an Ni-P plating film on one of the outer surface of the stopper and the inner surface of the stopper housing chamber, and forming a Sn plating film on the surface of the Ni-P plating film. It is a gas cock.

[0008]

Since the present invention has the above construction, the materials of the main body and the plug are always made of, for example, cast iron or copper alloy.
The coefficient of thermal expansion is the same, so that even if there is a temperature change, there is no change due to thermal expansion, and there is no change due to thermal expansion in the gap between the sliding parts. And the hardness of each material is about Sn plating Hv
10 <copper alloy Hv80 <cast iron Hv145 <Ni-P plating Hv500. In this case, a Ni-P plating film is formed on one of the main body and the plug, so that a large difference in hardness is always provided in the sliding portion. No galling problem.
Furthermore, a very soft Sn on Ni-P plating film
Since the plating film is formed, the Sn plating film serves as a lubricant, so that the turning operation of the plug can be performed with low torque. Also, even if the grease film is broken, the Sn plating film is not sealed.
Maintain the quality. Therefore, the rotation operability and the sealability are favorably maintained over a long period of time.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. The structure shown in FIG. 1 is substantially the same as that of a conventional gas cock.
Are both made of cast iron, and Ni-P
A plating film 3 and further a Sn plating film 4 are formed.

The Ni-P plating film 3 is formed by electroless plating using hypophosphite as a reducing agent on the outer peripheral surface of the plug 2 precisely finished by turning and lapping. According to this method, P is contained in an amount of 7 to 11 wt%, and the hardness is Hv4.
A hard film of about 00 to 550 is formed. The film thickness was about 10 μm, and the entire film was formed to have a substantially uniform thickness. Next, an Sn plating film 4 is quickly formed on the surface of the film 3 thus formed by electroplating. The Ni-P plating film 3 is preferably formed continuously since an insulating film is easily formed. If it cannot be performed in a continuous process, the coating 3 is once activated using electrolytic acid before performing Sn plating.

The Sn plating film 4 has a thickness of about 5 μ and a hardness of about Hv5 to Hv15. It is very soft as compared with the film 3 and has good adaptability to the plug housing chamber of the main body 1. Sn
After the plating film is formed, the roundness, the degree of fitting to the main body, and the like are increased by lapping. Grease is applied to the surface of the thus-formed plug 2 and assembled with the main body 1. The grease is provided for improving the turning operability and the sealing property of the stopper, but the experimental results showed that the sealing property could be maintained without applying the grease. This is considered to be due to the fact that the sealing effect is exhibited by the soft Sn plating film 4 as the underlayer.

Next, a durability test was performed on the gas cock of the above embodiment, and the results are shown in Table 1 below. For comparison, a conventional cock having a main body made of cast iron and a plug made of a copper alloy and having no surface treatment was similarly tested. The test conditions are as follows. Nominal gas cock: 3/4 One open / close: Closed → 90 ° rotation → Right open → 180 ° rotation →
Open left → 90 ° rotation → close Open / close speed: 10 times / minute Torque measurement: Maximum torque at each of the above rotation operations (Kg
-Cm)

[0013]

[Table 1]

Next, a heat resistance test was performed to examine how the opening / closing operation torque is affected by the temperature. The results are shown in Table 2 below. The test conditions are as follows. Low and high temperature holding test: After holding at -10 ° C and 60 ° C for 30 minutes, measure the opening / closing torque at that temperature. Heat cycle test: -10 ° C holding to 60 ° C holding, 4 cycles per day The cycle was repeated for 10 cycles, and the final opening / closing torque at 60 ° C. and the opening / closing torque (Kg-cm) when the temperature was cooled to 20 ° C. were measured. Other: Same conditions as above

[0015]

[Table 2]

In the durability test shown in Table 1, all of the rotation torque increases as the number of rotation operations increases. However, the product of the present embodiment can be rotated with a small torque of about 1/2 over the entirety from before the test until the number of rotations increases, as compared with the conventional product. This is presumably because the effect of providing the soft Sn plating film 4 on the hard Ni-P plating film 3 is exhibited. In the heat resistance test of Table 2, the conventional product was greatly affected by heat, and greatly increased compared to the rotational torque before the test. In view of the nominal size of the cock, if the torque exceeds 10, the steering wheel cannot be operated. At 60 ° C. after 10 heat cycles, rotation was impossible. On the other hand, in the product of this embodiment, the influence of heat was small, and the torque value was low enough to operate the steering wheel sufficiently. This is presumably because the effect that the main body 1 and the plug 2 are made of the same kind of metal is exhibited. In addition, since the soft Sn plating film 4 is provided on the hard Ni-P plating film 3 as described above, it is considered to be useful for preventing galling and improving slippage and improving operability. .

[0017]

As described above, the gas cock of the present invention is particularly excellent in operability, and maintains stable performance for a long period of time even under severe use conditions.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a gas cock of the present invention.

FIG. 2 is a partial cross-sectional view illustrating a state in which a plating film is provided on the plug according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body 2 Plug 3 Ni-P plating film 4 Sn plating film

Continuing on the front page (72) Inventor Kenji Taniguchi 2nd Daifuku, Kuwana-shi, Mie, Hitachi Metals Co., Ltd. Kuwana Plant (72) Inventor Chiaki Tsutsumi 2nd Daifuku, Kuwana-shi, Mie, Hitachi Metals Co., Ltd. Kuwana Plant (72 ) Inventor Isao Yoshikawa 3-14-10 Ayase, Adachi-ku, Tokyo (72) Inventor Hitoshi Denda 4-20-14 Toyocho, Shinagawa-ku, Tokyo Inside Gwangyang Sangyo Co., Ltd. (72) Michio Hasegawa Joetsu, Niigata city Oaza Kamigen'nyu 428 address No. 7 (72) inventor Sakumi Niigata Prefecture medium kubiki County Seiichiro kubiki village Ueyanagi-cho, 382 examiner Kazumi Kawamukai (58) investigated the field (Int.Cl. ^7, DB name) F16K 5 / 22 F16K 5/02

Claims (1)

(57) [Claims] 1. A gas cock comprising a plug body rotatable by an operation shaft housed in a plug body chamber of a gas cock main body, wherein the gas cock main body and the plug body are formed of the same material, and the outer surface of the plug body or the plug is provided. A gas cock characterized in that a Ni-P plating film is formed on one of inner surfaces of a body accommodating chamber, and a Sn plating film is formed on a surface of the Ni-P plating film.