JP2942839B2 - Two-layer sintered seal ring and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a material for a two-layer sintered seal ring obtained by integrally sintering two types of sintered materials having different components, each satisfying different required characteristics. The present invention relates to a component and a method for producing a two-layer sintered seal ring formed into a required shape during sintering.

(Prior Art) FIG. 1 is a front sectional view of a two-layer seal ring in which an O-ring is assembled. The outer periphery of the seal ring 1 comprising the wear-resistant sintered layer 2 having the seal surface 4 and the seal base 3 has a tapered portion 5 and an elastic O-ring 7 is loosely fitted.
An inverted tapered portion 6 is formed at the end of the tapered portion 5 to prevent the O-ring 7 from falling off.

 Conventionally, there are the following manufacturing methods for seal rings.

(1) A method in which a wear-resistant sintering material constituting a sealing surface is formed into a thin ring shape on a steel seal base by a smelting method and bonded and sintered.

(2) A method in which a sintered wear-resistant ring is brazed to a seal base of a sintered body or a steel seal base by a melting method.

(3) In order to prevent leaching of oil, water, etc., after forming a two-layer structure of a seal base material of a normal sintered body that does not sinter at a high density and a wear resistant material sintering at a high density beforehand, and sintering it. A method in which many small holes in the seal base are subjected to a sealing treatment such as resin impregnation.

(Problems to be Solved by the Invention) However, the above manufacturing method has the following problems. The method (1) is expensive because the seal base is manufactured in a separate process. In addition, a gas pool is easily formed at the joint interface between the seal base and the sintered layer, and the wear-resistant thin-walled ring may bulge or the liquid to be sealed may ooze through the gas pool. Alternatively, when the densification shrinkage of the wear-resistant material starts during sintering, the joint with the steel seal base that starts before that becomes a resistance to shrinkage, hindering the densification of the sintered body, and thus abrasion resistance Cannot be fully satisfied. (2)
In the method (1), it is expensive to braze the wear-resistant ring and the seal base manufactured in a separate process. In the method (3), since the shrinkage rate during sintering is different between the wear-resistant material and the seal base material, the joint between the wear-resistant material and the seal base material is a hindrance to the densification of the wear-resistant sintered material, and the wear resistance is reduced. May not be fully satisfied. In addition, when the seal ring is press-formed using a mold, the reverse tapered portion 6 cannot be formed. Therefore, after forming and sintering without the reverse tapered portion 6 shown in FIG. 6, which is expensive. Further, there is a problem that the sealing process is expensive.

(Means for solving the problem) Density of the seal base is increased to prevent bleeding of the liquid, and gas accumulation at the joint interface and resistance to contraction of the wear-resistant material generated when the wear-resistant material and the seal base material are integrally sintered. The formation of the reverse tapered portion 6 at the same time is an essential factor for improving the productivity. The inventor of the present application has conducted intensive studies to improve these, and as a result, when a mixed powder of iron, carbon, phosphorus, boron, nickel, and molybdenum is used for the seal base, densification proceeds from a low temperature, and abrasion resistant material and It was found that there was no gas accumulation at the bonding interface, no hindrance to shrinkage of the wear-resistant material, no bleeding of liquid exceeding 95% relative density, and by using an inner diameter restraining jig during sintering. The present invention has found a very unique material component and a manufacturing method which can form an inverted tapered portion and which has not been seen before.

That is, the method for producing a two-layer sintered seal ring according to the first invention of the present application is a method of forming a green compact by pressing a sintered material into a cylindrical shape, and sintering the green compact. In the method for manufacturing a sintered seal ring, the green compact is formed into a cylindrical shape having an inner diameter surface having substantially the same inner diameter in the axial direction in a diameter cross section, and an outer surface tapered in the axial direction. A compact compact made of a sintering material to be a wear-resistant sintering layer is placed on the thick end face of the compact, and an inner diameter restraining jig for restraining shrinkage due to sintering is arranged on the inner face of the thin end portion. An inverse taper portion with respect to the tapered outer surface is formed at the end of the thin outer surface by sintering the green compact.

The two-layer sintered seal ring according to the second invention of the present application is a two-layer sintered seal obtained by placing a compact formed as a wear-resistant sintered layer on a compact formed as a seal base sintered body and sintering. In the ring, the material component of the green compact to be the seal base sintered body is based on iron, carbon is 0.6 to 1.5% by weight, phosphorus is 0.3 to
It is essential to contain 1.2% by weight and 0.2% by weight or less of boron, which must be 4.0% by weight or less of nickel and
It is a composition to which at least one of molybdenum of 1.0% by weight or less is added, and is sintered at a temperature of 1100 ° C. or more, and thus has a relative density exceeding 95%.

Of the material components of the seal base sintered body of the present invention, the lower limit of 0.6% by weight of carbon is baked at 1100 ° C. or more when the upper limit of phosphorus is 1.2% by weight and the upper limit of boron is 0.2% by weight. When sintering, it is an addition amount necessary for the relative density to exceed 95%, and when the amount is too large, precipitation of cementite mainly in crystal grain boundaries is severe after sintering, and it becomes brittle, so the upper limit value is 1.5.
% By weight. The upper limit of 1.2% by weight of phosphorus is set from the upper limit of remarkable precipitation of adelite crystals, and the lower limit is 0.3% by weight.
Is the amount required for the relative density to exceed 95% when sintered at 1100 ° C. or more when the upper limit of the amount of carbon added is 1.5% by weight and the upper limit of the amount of boron added is 0.2% by weight. The upper limit of the added amount of boron of 0.2% by weight is set because the iron boride phase becomes excessively brittle and the strength is lowered when the iron boride phase is excessively precipitated. Even if the lower limit is 0% by weight, the relative density exceeds 95%. However, preferably, when added in an amount of about 0.05% by weight, there is no significant effect on strength and brittleness, and the material is densified well. When nickel and molybdenum are added together with boron, densification in particular progresses from low temperatures, resulting in a stable, high-density product, and wear-resistant sintering placed on the sealing surface even during quenching after sintering. The layer is added to adjust the quenched layer of the seal base material to prevent the separation and cracking of the joint interface generated by the martensitic transformation of the layer, and the range is 0 to 4% by weight of nickel and 0 to 4% by weight of molybdenum. The function is satisfied at about 1% by weight. The material components of the present invention include those to which commonly used elements such as manganese, silicon, and chromium are added for adjusting hardenability, and those to which copper is added for improving corrosion resistance and weather resistance.

(Function) According to the first invention, the compact formed into a cylindrical shape having an inner diameter surface having substantially the same inner diameter in the axial direction and a tapered outer surface in the axial direction in the diameter cross section, An inner diameter restraining jig for restraining shrinkage due to sintering is disposed on the inner diameter surface on the thin end portion side of the body, and the compacted body is sintered to form the thinner outer surface with respect to the tapered outer surface at the end portion. An inverse tapered projection is formed.

According to the second invention, (1) in the seal base sintered body, since at least one of nickel and molybdenum is coexistently added to boron, the densification progresses particularly from a low temperature, and the relative density exceeds 95%. Product with high density.

(2) Similar to the wear-resistant sintered layer, the seal base sintered body has a relative density of more than 95% and is increased in density, so that the shrinkage ratio during sintering is substantially the same as that of the wear-resistant sintered layer. For this reason, the wear-resistant sintered layer can obtain sufficiently satisfactory wear resistance without densification being hindered at the joint with the seal base sintered body.

(3) When the two-layer sintered seal ring after sintering is quenched, the abrasion-resistant sintered layer disposed on the seal surface becomes martensitic and expands, thereby causing peeling and cracking at the joint interface. Although it is easy, at least one of the added nickel and molybdenum adjusts the hardenability of the seal base sintered body to prevent peeling and cracking at the joint interface.

(Example) The two-layer sintered seal ring of the present invention is manufactured as follows. As shown in FIG. 2, the respective sintered materials of the wear-resistant sintered layer 2 on the sealing surface and the seal base sintered body 3 are pressure-formed, and as shown in FIG. When the anticipated disk-shaped inner diameter restraining jig 11 is attached and sintered at 1100 ° C. or more, an inverted tapered portion 6 is formed as shown in FIG. After sintering, remove the inner diameter restraining jig 11, quench,
Perform tempering. After the sintering, the inner diameter restraining jig 11 was easily detached from the two-layer sintered seal ring 1 and the inverted tapered portion 6 was also formed, and the roundness of the outer diameter portion of the sealing surface was suppressed to about ± 0.07 mm. Next, an example of a method for manufacturing a wear-resistant sintered layer and a seal base sintered body will be described.

The green compact to be used as the wear-resistant sintered layer has a basic composition of iron, and uses a sintered material of 3.0% by weight of carbon, 15% by weight of chromium, 1% by weight of molybdenum, and 0.8% by weight of silicon. The green compact is made of iron and has a basic composition of carbon.
A sintered material of 1.2% by weight, 1.0% by weight of phosphorus, 0.05% by weight of boron, 2% by weight of nickel and 0.5% by weight of molybdenum was used. Each of the green compacts serving as the wear-resistant sintered layers and the green compacts serving as the seal base sintered bodies was formed by molding the respective sintered materials into the respective shapes as shown in FIG. The green compact to be used as the wear-resistant sintered layer was molded at a molding pressure of 5 ton / cm ² so that the thickness was about 1 mm after the pressure molding. Next, after degreased at 750 ° C., the shrinkage ratio of the sintered compact is 7%, and the diameter of the compacted compact which is the seal base sintered body on which the compacted compact to be the wear-resistant sintered layer is placed is assumed. Attached to a 2 mm thick disk-shaped inner diameter restraining jig coated with BN (boron nitride) on an 18-8 stainless steel disk that has been determined to
After vacuum sintering at 01 Torr or less, forced quenching was performed with 650 Torr of N2 (nitrogen gas), and tempering was performed at 180 ° C for 2 hours. As a result, the relative density was 97% or more, and no leak was observed in the leak test using compressed air, and there was no crack during quenching.

(Effect of the Invention) A two-layer sintered seal ring in which a reverse taper portion can be easily formed by the manufacturing method using the inner diameter restraining jig of the present invention, the roundness of the outer diameter portion of the sealing surface is good, and the productivity is extremely high. Is obtained.

In addition, according to the material components of the present invention, the wear-resistant sintered layer and the seal base sintered body are both densified and shrunk beyond the relative density of 95% during sintering at 1100 ° C. or more.
In addition to preventing generation of gas pools at the joint interface, it does not hinder shrinkage and densification of the wear-resistant sintered layer, does not crack or peel during quenching, and does not exude liquids such as oil and water.

[Brief description of the drawings]

FIG. 1 is a front sectional view of a two-layer sintered seal ring with an O-ring assembled, FIG. 2 is a shape of the seal ring after pressure molding, FIG. 3 is an explanatory view of an inner diameter restraining jig, and FIG. FIG. 3 is an explanatory view of a shape of a two-layer sintered seal ring after sintering. DESCRIPTION OF SYMBOLS 1 ... Two-layer sintered seal ring 2 ... Wear-resistant sintered layer 3 ... Seal base sintered body 4, ... Seal surface 5, ... Peripheral taper part, 6 ... Reverse taper part, 7 ... O Ring, 11…
… Inner diameter restraining jig

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-53-8456 (JP, A) JP-A-49-125208 (JP, A) JP-A-54-20911 (JP, A)

Claims (2)

(57) [Claims] 1. A method for manufacturing a two-layer sintered seal ring, comprising forming a green compact by pressing a sintered material into a cylindrical shape, and sintering the green compact. Is formed in a cylindrical shape having an inner diameter surface having substantially the same inner diameter in the axial direction and a tapered outer surface in the axial direction in the diameter cross section, and a wear-resistant sintered layer is formed on the thick side end surface of the green compact. A compact formed from a sintered material is placed, and an inner diameter restraining jig for restraining shrinkage due to sintering is disposed on the inner surface of the thin end portion side, and the compact is compacted by sintering the compact. A method of manufacturing a two-layer sintered seal ring, comprising forming an inverse taper portion with respect to the tapered outer surface at an outer surface end. 2. A two-layer sintered seal ring obtained by placing a green compact as a wear-resistant sintered layer on a green compact as a seal base sintered body and sintering the same. The material component of the green compact is based on iron, and it is essential to contain 0.6 to 1.5% by weight of carbon, 0.3 to 1.2% by weight of phosphorus and 0.2% by weight or less of boron, and 4.0% by weight A two-layer sintering composition characterized by having at least one of the following nickel and 1.0% by weight molybdenum added thereto, sintered at a temperature of 1100 ° C. or more, and having a relative density exceeding 95%. Tied seal ring.