JP2003090432A - Wear resistant ring with cooling cavity and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wear resistant ring with a cooling cavity superior in manufacturability and capable of stably preventing separation of a wear resistant ring main body and a cooling cavity-forming member. SOLUTION: Graphite powder is mixed in alloy steel powder to make a mixture of powder. A pair of green compacts having a shape dividing a wear resistant ring of a near shape into two in a height direction and having a step part over the whole circumference of the end part to make a section of a roughly U-shape after sintering on an inner circumference surface is made of the mixture of powder. An annular cooling cavity forming ring member is put between inner circumferences of a pair of the green compacts. The green compacts are sintered to be sintered bodies and the wear resistant ring main body made of sintered body and a cooling cavity forming ring member are sintered and bonded at tip of the step part to form a unit. The alloy steel powder is preferably austenitic stainless steel powder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wear ring which is cast in a piston for an internal combustion engine and holds a piston ring, and more particularly to a wear ring having a ring material for forming a cooling cavity on the inner peripheral side.

[0002]

2. Description of the Related Art In recent years, for the purpose of weight reduction and improvement of heat dissipation of engines, aluminum alloy engines are becoming popular, and pistons are also made of aluminum alloy. On the other hand, along with the demand for higher engine output, the engine is exposed to a higher temperature combustion environment, and the piston ring is also required to have severe wear resistance.

In order to improve the wear resistance of the piston ring, a high hardness piston ring has been used. Therefore, the piston ring groove is hit by the end faces of these piston rings, and therefore, there is a possibility that the piston ring groove will be sagged or deformed in a normal aluminum alloy. In particular, since the combustion pressure acts directly on the top ring of a diesel engine, the top ring groove is repeatedly subject to impacts by the piston ring, and is easily worn. If wear occurs in the top ring groove,
Gas leakage and oil leakage will occur, resulting in a reduction in engine output.

In order to solve such a problem, there has been proposed a structure in which a wear ring made of a material having a higher strength than the piston material (aluminum alloy) is fixed to the piston ring groove, and the piston ring is supported by the wear ring. There is. For example, in a piston for a diesel engine, a Niresist cast iron insert (anti-wear ring) is cast in the top ring groove to prevent wear of the piston ring groove when the piston slides inside the cylinder. Things are the mainstream.

On the other hand, the piston of the internal combustion engine, especially the vicinity of the top ring groove, is exposed to a high temperature due to the thermal energy generated by the compression and explosion of the fuel, and therefore must be cooled at all times. Therefore, conventionally, an annular (doughnut-shaped) cooling cavity is created near the top ring groove of the thick wall of the piston.
A type that circulates lubricating oil to cool it is adopted. Further, from the viewpoint of preventing the wear of the piston ring groove and preventing the deterioration of the function of the piston ring, it has been required to arrange the wear ring and the cooling cavity as close as possible to prevent the temperature rise of the wear ring.

[0006] In response to such a demand, for example, Jikho Sho 58
As shown in FIG. 7, Japanese Patent Laid-Open No. 52346 proposes a piston in which a cooling cavity and a ring trailer (anti-wear ring) are integrally molded and cast into a piston body. However, in the technology described in Japanese Utility Model Publication No. 58-52346, since the cooling cavity and the wear ring are integrated by casting, the wall thickness between the ring groove bottom and the cooling cavity is (Fig. 7
There is a problem that it is difficult to thin the inner space: a), and therefore the cooling ability of the piston ring groove is not sufficient.

On the other hand, in Japanese Unexamined Patent Publication No. 5-240347, either one of the molded body having a substantially U-shaped cross section made of a metal plate and the joint end surface on the inner peripheral side of the wear-resistant ring main body is provided on the other side. And a wear-resistant ring having a body ring portion on the inner peripheral side through which the coolant flows back by joining the molded body and the wear-resistant ring body portion by inserting the other into the fit-inserted portion. The technology to do is proposed. According to the technique described in Japanese Patent Laid-Open No. 5-240347, it is preferable that the wear resistant ring main body is made of Niresist cast iron and the molded body is made of a metal plate such as a stainless steel plate.

However, in the wear resistant ring disclosed in Japanese Patent Laid-Open No. 5-240347, there is a problem that the joint between the molded body and the wear resistant ring body is uncertain. For example, when welding is used as the joining means, welding defects may remain at the joining portion. When the wear ring described in JP-A-5-240347 is cast in an aluminum piston, the wear resistance of the wear ring body made of Ni-resist cast iron and the molded body made of stainless steel plate is poor, and therefore In order to improve the castability, it is necessary to subject the wear-resistant ring surface to alfin treatment before casting. However, even such a treatment does not always provide sufficient adhesive strength, and there is a problem in that the process becomes complicated and the manufacturing cost rises.

Further, in Japanese Unexamined Patent Publication No. 2001-32748, an annular wear-ring-resistant body made of a metal-based sintered material and an annular cavity-forming material made of a pipe material are sinter-fitted to the inner circumference of the wear-resistant ring body. Piston wear rings with cooling cavities have been proposed which are joined together, preferably during sintering, by brazing to the inner circumference of the wear ring body.

[0010]

SUMMARY OF THE INVENTION
In the piston wear ring with a cooling cavity described in 2001-32748, it is difficult to sufficiently diffuse the joint surface at the time of sintering, and there is a problem in adhesion of the joint surface, stability of the joint surface strength, and the like. was there. Therefore, when the molten aluminum alloy is cast and wrapped in the piston material, the cooling cavity and the wear-resistant ring main body may separate from each other and become a product, leaving a problem in the manufacturability of the piston. In addition, in order to prevent peeling at the joint surface during casting, it is necessary to process the cavity forming material and the ring carrier body with high dimensional accuracy so that stable and high joint surface strength can be obtained. There was also the problem of causing a steep rise in prices.

The present invention solves the above-mentioned problems of the prior art, and when a wear ring is cast on a piston, a high joint surface strength is stably obtained, and the wear ring body and the cooling cavity forming material are separated from each other. It is an object of the present invention to propose a wear-resistant ring with a cooling cavity, which can be prevented and is excellent in manufacturability, and a manufacturing method thereof.

[0012]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the inventor of the present invention diligently studied a method for joining a ring carrier body and a cooling cavity forming material. As a result, stepped portions are formed at both ends in the height direction of the inner surface of the wear resistant ring body, and the wear resistant ring body is divided into two parts in the height direction, and the cooling cavity forming material is sandwiched on the inner peripheral side of the wear resistant ring body. Alternatively, by arranging them so that they are held together and heating and sintering, peeling can be prevented at least at the joint surface between the wear ring body and the cooling cavity forming material and at the wear ring body joint surface at the time of casting and productivity is improved. I found out to do.

The present invention has been completed by further studies based on the above findings. That is, the gist of the present invention is as follows. (1) A wear resistant ring with a cooling cavity, comprising a wear resistant ring main body made of a porous metal sintered body and an annular cooling cavity forming ring member joined to the inner peripheral side of the wear resistant ring main body, The ring body is sintered and joined at a predetermined position in the height direction,
In addition, a stepped portion is formed over the entire circumference on both sides of the end so that the inner peripheral surface has a substantially U-shaped cross section, and the stepped portion is baked so as to sandwich the cooling cavity forming ring member. A wear-resistant ring with a cooling cavity, characterized by being integrally joined and bonded. (2) In (1), the ring material for forming cooling cavities has, on the outer peripheral surface thereof, a notch portion configured to be able to fit and join the tip of the stepped portion, and at least the above. A wear resistant ring with a cooling cavity, characterized in that the tip of the stepped portion and the bottom portion of the cutout portion are sintered and joined together. (3) In (1) or (2), the inner peripheral surface of the wear resistant ring main body and the outer peripheral surface of the cooling cavity forming ring material have a predetermined clearance other than the stepped portion. Wear ring with cooling cavity. (4) In any one of (1) to (3), the ring material for forming cooling cavities has a size up to a position corresponding to a second ring in the height direction, the wear resistant ring with cooling cavities. (5) In (1), instead of being sintered and bonded so that the cooling cavity forming ring member is sandwiched by the stepped portion, the cooling cavity forming ring material is held by the stepped portion. A wear-resistant ring with a cooling cavity, characterized in that it is sintered and bonded to. (6) In any one of (1) to (5), the wear resistant ring main body has a size capable of forming two ring grooves and is sintered at two predetermined positions in the height direction. A wear-resistant ring with a cooling cavity, characterized by being joined. (7) In any one of (1) to (6), the porous metal sintered body contains C: 0.1 to 1.5% by mass% and Si:
1.0% or less, Mn: 2.0% or less, P: 0.1% or less, S: 0.
Abrasion resistance with cooling cavities characterized by being a porous austenitic stainless steel sintered body having a composition containing 03% or less, Ni: 5.0 to 15.0%, Cr: 15.0 to 25.0%, and the balance being substantially Fe. ring. (8) In any one of (1) to (7), the ring material for forming cooling cavities is made of steel pipe, and a wear resistant ring with cooling cavities is provided. (9) In any one of (1) to (8), the cooling cavity forming ring material is C: 0.1% or less by mass%.
Si: 1.5% or less, Mn: 2.0% or less, Ni: 2 to 20%, Cr:
Characterized in that it is made of austenitic stainless steel with a composition of 16-26%, or additionally Mo: 1.2-4.0% and / or Cu: 1-2.5% with the balance being essentially Fe. Wear ring with cooling cavity. (10) After the graphite powder is mixed with the alloy powder to form a mixed powder, the mixed powder is formed into a ring to form a green compact, and then an annular cooling cavity is formed on the inner peripheral side of the green compact. In a method for manufacturing a wear ring with a cooling cavity, in which a ring material for cooling is incorporated to sinter and bond the green compact and the ring material for forming the cooling cavity, the green compact is provided with a piston ring groove on an outer periphery of a substantially predetermined shape. A pair of ring-shaped wear-resistant rings divided in the height direction and having a stepped portion on the inner peripheral surface over the entire circumference of the end portion so that the cross section after sintering is substantially U-shaped. Forming a cooling cavity by setting a predetermined gap on the inner peripheral side of the green compact so that the pair of green compacts can be joined by sandwiching the cooling cavity forming ring material. A method for manufacturing a wear-resistant ring with a cooling cavity, comprising incorporating a ring material for sintering and sintering the ring material. (11) In (10), the ring material for forming cooling cavities is a ring material for forming cooling cavities, which has a notch formed on the outer peripheral surface so as to be capable of contacting with the tip of the stepped portion.
The cooling cavity forming ring material, so that at least the tip of the stepped portion and the bottom of the notch portion can be sintered and joined,
A method for manufacturing a wear-resistant ring with a cooling cavity, characterized by incorporating the same. (12) In (10) or (11), the inner peripheral surface of the wear resistant ring main body and the outer peripheral surface of the cooling cavity forming ring material have a clearance of a predetermined value or more except for the stepped portion. A method for producing a wear-resistant ring with a cooling cavity, comprising adjusting a length of a stepped portion and / or a depth of the cutout portion. (13) In any one of (10) to (12),
The alloy powder is, by mass%, Ni: 5.0 to 15.0%, Cr: 1
A method for producing a wear resistant ring with a cooling cavity, which is an austenitic stainless steel powder containing 5.0 to 25.0%. (14) In (13), the austenitic stainless steel powder contains Ni: 5.0 to 15.0% or less and Cr: 15.0 to 25.0.
%, C: 0.3% or less, Si: 1.0% or less,
A method for producing a wear-resistant ring with a cooling cavity, comprising: Mn: 2.0% or less, P: 0.1% or less, S: 0.03% or less, and the balance being substantially Fe. (15) In any one of (10) to (14),
A method for producing a wear-resistant ring with a cooling cavity, wherein the sintering temperature is 1150 to 1250 ° C. (16) In (15), the sintering time is 40 to 70
A method for producing an anti-wear ring with a cooling cavity, characterized in that the value is min. (17) In any one of (10) to (16),
The method for producing a wear resistant ring with a cooling cavity, wherein the ring material for forming the cooling cavity is made of a steel pipe. (18) In any of (10) to (17),
The ring material for forming cooling cavities, in mass%, C: 0.1%
Below, Si: 1.5% or less, Mn: 2.0% or less, Ni: 2-20
%, Cr: 16-26%, or even Mo: 1.2-
A method for producing a wear resistant ring with a cooling cavity, which is made of an austenitic stainless steel having a composition containing 4.0% and / or Cu: 1 to 2.5%, and the balance being substantially Fe.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION As shown schematically in FIG. 1, a wear-resistant ring 1 of the present invention comprises an annular wear-resistant ring body 2 made of a porous metal sintered body, and an inner circumferential side of the wear-resistant ring body. And an annular cooling cavity forming ring member 3 joined to the. Although FIG. 1 shows an example in which the ring groove 22 is formed on the outer peripheral side of the wear resistant ring main body 2, the ring groove 22 may be formed in advance before the wear resistant ring is cast into the piston, or may be cast. Needless to say, either may be formed by finishing.

The ring carrier body 2 has a stepped portion 21a over the entire circumference of both end portions of the inner peripheral surface so that the inner peripheral surface has a substantially U-shaped cross section.
, 21b. Although the ring carrier body is made of a porous metal sintered body, in the present invention, the ring carrier body 2 is provided at a predetermined position in the height direction, for example, as shown in FIG. After placing the pressed powder bodies (members 2a, 2b) in a shape that divides the ring carrier body at the center position in the vertical direction via the contact part 2A, heat sinter and sinter and bond the contact part 2A for integration. The ring-shaped main body is formed into a ring shape. The lengths and thicknesses of the stepped portions 21a and 21b formed at both ends of the inner peripheral surface of the wear resistant ring body are determined by the bonding strength with the desired cooling cavity forming ring material,
It is preferable to make appropriate adjustments depending on the method of integration with the cooling cavity forming ring material.

On the other hand, the cooling cavity forming ring member 3 has an outer peripheral surface having an annular shape which substantially matches the inner peripheral surface shape of the wear-resistant ring main body. The ring material 3 for forming cooling cavities is preferably a metal tube, preferably a steel tube, processed by, for example, a press or the like so that the outer peripheral surface has the above-described annular shape, but the present invention is not limited to this. . In the present invention, the outer peripheral surface of the ring material 3 for forming cooling cavities has a shape that substantially matches the shape of the inner peripheral surface of the ring-resistant body, and the outer peripheral surface of the ring material 3 for forming cooling cavities further has Notches 31a, 31b are formed so that the tips of the stepped portions 21a, 21b formed at both ends of the inner peripheral surface can be fitted and joined. (In FIG. 3 (a),
The state where the notch parts 31a and 31b are formed is shown. It is preferable that the cooling cavity forming ring member 3 has a size (length) up to a position corresponding to the top ring, mainly for the purpose of preventing the function of the top ring from being reduced. As shown in FIG. 3B, the size may be up to a position corresponding to the second ring in the height direction. By enlarging the cooling cavity, it is possible to improve the cooling capacity and reduce the wear of the piston ring up to the second ring.

The ring carrier body and the ring material for forming cooling cavities are stepped portions 21a, 21 formed on the inner peripheral surface of the ring carrier body.
The tip of b and the bottom of the notches 31a and 31b formed on the outer peripheral surface of the cooling cavity forming ring member 3 are placed facing each other so as to be joined, and heat-sintered. The ring carrier body contracts during sintering to come into contact with the cooling cavity forming ring material and also to perform sinter bonding. As a result, as shown in FIG. 1, the cooling cavity forming ring member can be sintered and joined so as to be sandwiched by the stepped portion of the wear resistant ring main body to be integrated.

Further, instead of the above case, without forming a notch on the outer peripheral surface of the cooling cavity forming ring member,
As shown in FIG. 4, the stepped portions 2a and 2b of the wear resistant ring main body may be formed long so that the cooling cavity forming ring member can be held therein. As a result, the cooling cavity forming ring member can be placed so as to be held by the stepped portion. By mounting and sintering in this manner, the ring material for forming the cooling cavity can be joined and integrated so as to be held in the stepped portion of the wear resistant ring main body.

A ring carrier body and a ring material for forming a cooling cavity.
Is a sinter joint at least in the above-mentioned stepped part and notch part.
All you have to do is do it. Other than this, it is not always sinter-bonded
It is not necessary to have a ring wear body and a cooling cavity shape.
B between the production ring material ₁= 0 to 0.5 mm, b₂= 0
It is better to have a clearance of ~ 0.05mm.
It is preferable from the viewpoint of preventing the occurrence of cracks when casting in tons.
Especially clearance b ₂Is over 0.05 mm, when casting
The ring material 3 for forming the cooling cavity may come off.

It should be noted that the wear-resistant ring main body may have a size such that two ring grooves can be formed so that a second ring groove can be formed in addition to the top ring groove. In this case, it is preferable to sinter and bond the ring carrier body to two predetermined positions in the height direction, as shown in FIG. 2 (b). Further, in the present invention, in order to prevent the occurrence of cracks at the boundary surface between the piston and the wear ring, as the wear ring body, use a material whose difference in coefficient of thermal expansion from the aluminum alloy that is the piston material is as small as possible. It is important to minimize the thermal stress generated between the piston and the piston material. For this reason,
As a material for the ring carrier body, it is preferable to use an austenitic stainless steel sintered body. The coefficient of thermal expansion of austenitic stainless steel is about 16 × 10-6 to 18 × 10-6 / ° C, and the coefficient of thermal expansion of aluminum alloy (20 × 10-6 /
℃) close.

In the present invention, the porous metal sintered body constituting the wear resistant ring main body is, in mass%, C: 0.1 to 1.5%, Si: 1.0.
% Or less, Mn: 2.0% or less, P: 0.1% or less, S: 0.03%
Hereinafter, it is preferable to use a porous austenitic stainless steel sintered body having a composition containing Ni: 5.0 to 15.0% and Cr: 15.0 to 25.0% and the balance substantially Fe. Next,
The reasons for limiting the composition of the porous austenitic stainless steel sintered body will be described. In the following, mass% in the composition will be simply referred to as%.

C: 0.1 to 1.5% C is an element that increases the strength of the sintered body. In the present invention, the content of 0.1% or more is required to secure the strength and improve the wear resistance. If the content exceeds 1.5%, the carbides become coarse and the machinability deteriorates. Therefore, C is 0.1-1.5%
It is preferable to limit to

Si: 1.0% or less Si is an element which increases the strength of the sintered body, and it is preferable to contain Si in an amount of 0.3% or more. However, if it exceeds 1.0%, the sintered body tends to become brittle. Become. Therefore, Si is 1.0
% Or less is preferable. Mn: 2.0% or less Mn is an element that increases the strength of the sintered body. In the present invention, it is preferable to contain 0.05% or more, but if it exceeds 2.0%, the sintered body becomes brittle. It becomes a tendency. Therefore, Mn is preferably set to 2.0% or less.

P: 0.1% or less, and when P is contained in excess of 0.1%, the amount of steadite carbide increases and the machinability deteriorates. Therefore, it is preferable to limit P to 0.1% or less. In addition, more preferably 0.05%
It is the following. S: 0.03% or less It is preferable that S forms a sulfide and reduces the ductility and toughness of the material as much as possible. Therefore, in the present invention, S is preferably limited to 0.03% or less.

Ni: 5.0 to 15.0% Ni is an austenitizing element, and in the present invention, it is preferable to contain 5% or more. On the other hand, if the content exceeds 15.0%, the hardness decreases. Therefore, Ni is 5.0-15.0%
It is preferable to limit the range. Cr: 15.0 to 25.0% Cr is a solid solution strengthening element, and is preferably contained in an amount of 15.0% or more in order to secure desired strength. On the other hand, if the content exceeds 25.0%, the precipitation of Cr carbide on the grain boundaries becomes remarkable and the wear resistance decreases. Therefore, Cr is 15.0 to 25.0%
It is preferable to limit the range.

In addition to the above components, there is no problem even if one or more of Mo, Ti and Nb are contained in a total amount of 1% or less. The balance other than the above components is substantially Fe. As inevitable impurities, N: 0.1% or less,
Se: 0.15% or less is acceptable. The porous metal sintered body (porous austenitic stainless steel sintered body) of the present invention preferably has pores having an area ratio of 20 to 50%. When the porosity is less than 20%, the molten aluminum alloy does not impregnate the pores of the wear ring when cast in an aluminum alloy piston, and the boundary strength decreases. On the other hand, the porosity is 50%
When it exceeds, the strength is reduced due to too many holes and the piston ring is deformed when sliding.

The ring material for forming the cooling cavity is preferably made of a metal tube, preferably a steel tube. As a steel pipe, in mass%, C: 0.1% or less, Si: 1.5% or less, M
n: 2.0% or less, Ni: 2 to 20%, Cr: 16 to 26%,
Alternatively or additionally, Mo: 1.2-4.0% and / or Cu:
It is more preferable to use an austenitic stainless steel pipe having a composition containing 1 to 1.5% and the balance being substantially Fe. By making the cooling cavity forming ring material an austenitic stainless steel pipe of the above composition, the shrinkage during sintering is less than that of the wear resistant ring main body, and at least the wear resistant ring main body is caused by the stress due to the difference in shrinkage at the time of sintering. The tip of the stepped portion presses the bottom of the cutout portion of the cooling cavity forming ring material, whereby the wear ring main body and the cooling cavity forming ring material are sintered and integrated with each other.

Next, the method for producing the wear resistant ring of the present invention will be described. The ring carrier body is made of a porous metal sintered body. Porous metal sintered body, after the alloy powder as a raw material, and graphite powder to be mixed powder, after charging the mixed powder into a mold and pressure molding into a ring-shaped green compact,
The green compact is sintered to form a ring carrier body.

The alloy powder used as the raw material powder is preferably austenitic stainless steel powder. As austenitic stainless steel powder, SUS 302, SUS 30
3, SUS 304, SUS 304L, SUS 316, SUS 317, SUS 310S are preferable. Above all, as the material of the wear ring, SUS 303, which has a high coefficient of thermal expansion from the viewpoint of preventing the occurrence of cracks on the boundary surface,
SUS 304 is preferable. If SUS 304 is used, improvement in oxidation resistance and wear resistance can be expected.

The austenitic stainless steel powder as described above is mixed with graphite powder or with copper powder to obtain a mixed powder so that the composition of the porous austenitic stainless steel sintered body described above is obtained. Graphite powder is added as an alloying element that increases the strength of the porous sintered body, but if the content in the mixed powder exceeds 1.5 mass%, carbides increase and the characteristics of the austenitic stainless steel are impaired, Machinability is deteriorated, a liquid phase is generated during sintering, a large number of independent pores are generated, and the boundary strength is reduced. Therefore, it is preferable to limit the graphite powder to 1.5% by mass or less. The particle size of the graphite powder is preferably 0.1-10 μm. If it is less than 0.1 μm, handling becomes difficult, and if it exceeds 10 μm, uniform dispersion becomes difficult.

In the present invention, in addition to the above composition of the mixed powder, the mixed powder may further contain fine particle powder for improving the machinability in order to improve the machinability. The fine particle powder for improving the machinability is preferably one or more selected from MnS 2, CaF 2, BN and enstatite. When the mixed powder contains the fine particle powder for improving the machinability, the content of the fine particle powder for improving the machinability is 0.1 to 5
It is preferably set to mass%. If it is less than 0.1% by mass, the machinability improving effect is small, while if it exceeds 5% by mass, the boundary strength is lowered.

In the present invention, the mold is a mold capable of molding a ring-shaped green compact having a stepped portion on the inner peripheral side, and the mixed powder is charged into the mold and pressure-molded, for example, , FIG. 5 (a)
A pair of ring-shaped green compacts 2a (2b) each having a stepped portion 21a (21b) having a cross-sectional shape shown in FIG. A ring-shaped green compact 2 having stepped portions 21a (21b) shown in FIG. 5 (a).
Reference numeral a (2b) has the same shape as one side 2a or the other side 2b which is symmetrical with respect to the dividing surface 2A and which is obtained by dividing the wear resistant ring main body 2 having a substantially predetermined shape into two in the height direction. In FIG. 5 (a), the portion corresponding to the piston ring groove 22 is formed on the outer circumference, but it goes without saying that the piston ring groove may be formed by finishing.

By superposing one green compact 2a on the other green compact 2b as shown in FIG. 5 (b), a ring-shaped groove can be formed on the outer periphery to have a predetermined ring shape. It becomes the same shape. A ring material for forming cooling cavities is prepared separately from the pair of green compacts that form the ring carrier body. A metal tube, preferably a steel tube, is processed by, for example, a press or the like to form an outer peripheral surface into an annular shape that substantially matches the inner peripheral surface shape of the wear-resistant ring main body. The metal pipe (steel pipe) to be used is not particularly limited as long as it can secure at least a width (length in the wear ring shaft (height) direction) capable of cooling the top ring groove. The ring material for forming the cooling cavity may have a size capable of cooling up to a position where the second ring can be cooled (a position corresponding to the second ring). The cooling cavity forming ring material is preferably a metal tube, preferably a steel tube. As a steel pipe, in mass%, C: 0.1% or less, Si: 1.5% or less, Mn: 2.0%
Below, Ni: 2 to 20%, Cr: 16 to 26%, or further, Mo: 1.2 to 4.0% and / or Cu: 1 to 1.5%
It is more preferable to use an austenitic stainless steel pipe having a composition containing the above and the balance being substantially Fe.

In the present invention, the outer peripheral surface of the cooling cavity forming ring member 3 is shaped to substantially match the inner peripheral surface shape of the wear ring main body, and as shown in FIG. Notches 31a, 31b are formed on the outer peripheral surface of No. 3 so that the tips of stepped portions 21a, 21b formed at both ends of the inner peripheral surface of the ring carrier body can be fitted and joined. The ring material 3 for forming a cooling cavity having notches 31a and 31b formed on the outer peripheral surface thereof,
As shown in FIG. 6, gaps t ₁ and t ₂ between 21a (21b) and 31a (31b) are formed on the inner peripheral side of the pair of green compacts 2a and 2b, which become the wear-resistant ring body after sintering, as shown in FIG. It is preferable to set it so as to form a predetermined gap and to incorporate it.

It is preferable to set the predetermined void upon assembling in accordance with the composition of the powder compact that constitutes the wear-resistant ring main body and the composition of the metal tube (steel tube) of the ring material for the cooling cavity. In the case of the combination of the sintered body and the metal tube (steel tube) of the ring material for the cooling cavity, t ₁ = 0 to
0.4 mm, t ₂ = 0.05 to 0.1 mm / diameter of about 100 mm is preferable. If the distance t ₂ is smaller than 0.05 mm, the ring-resistant main bodies will be easily separated from each other due to shrinkage during sintering. Further, if the interval t ₂ exceeds 0.1 mm, the clearance after sintering exceeds 0.05 mm, and the link for forming the cooling cavity is likely to come off.

After the sintering, the stepped portion length and the stepped portion length are set so that the inner circumferential surface of the wear resistant ring main body and the outer circumferential surface of the cooling cavity forming ring material have a clearance of a predetermined value or more except the stepped portion. The depth of the notch and / or the void may be adjusted. In this way, the separately prepared cooling cavity forming ring material is added to the pair of green compacts forming the wear resistant ring body, and the stepped portion 21 is formed on the inner peripheral surface of the wear resistant body.
The cooling cavity forming ring material is assembled so that the tips of a and 21b and the notches 31a and 31b formed on the outer peripheral surface of the cooling cavity forming ring member 3 face each other so as to be joined, and are heated. 3 is sintered and joined so as to be sandwiched between a pair of green compacts 2a and 2b. As shown in FIG. 1, the green compact, which becomes the wear-resistant ring body, shrinks during heating and sintering, contacts the ring material for forming the cooling cavity, and at least the tip of the stepped portion and the bottom of the notch portion are sintered. To join. By this sintering treatment, a pair of green compacts are also sintered and joined at the same time, and integrated so that the cooling cavity forming ring member is sandwiched between the stepped portions of the wear resistant ring main body to form a cooling cavity-equipped wear ring.

It is preferable to appropriately select the sintering conditions depending on the materials to be used, but when the green compact having the above composition and the ring material for the cooling cavity are combined, the sintering conditions are
It is preferable to set the temperature at 1150 to 1250 ° C for 40 to 70 minutes. If the heating temperature for sintering is less than 1150 ° C, the amount of shrinkage of the green compact during sintering is small and the required bonding strength cannot be obtained. On the other hand, 1250 ℃
If the temperature exceeds the above range, the porosity of the obtained sintered body varies greatly and it is difficult to obtain a sintered body having stable characteristics, and the maintenance work load of the sintering furnace becomes large, and the cost of the sintering process rises. On the other hand, if the sintering treatment time is less than 40 min, the sintering treatment will be insufficient and it will be difficult to obtain the required strength of the sintered body. On the other hand, if it exceeds 70 min, the sintering treatment time will be long and the productivity will be reduced.

The ring-shaped wear ring having a cooling cavity thus obtained is composed of a porous metal sintered body and is a product as a sintered body, and is provided at a portion corresponding to the ring groove of the mold forming the piston. After mounting, the molten aluminum alloy melt is poured into the mold, and high pressure die casting is performed or the melt is forged. As a result, the molten metal penetrates into the pores of the sintered body, the joining with the piston material is completed, and the piston is made of an aluminum alloy in which the wear ring is cast. After being cast in the piston, the wear resistant ring is finished in the piston ring groove and mounted with the piston ring for use.

[0039]

[Example] Austenitic stainless steel powder shown in Table 1
Graphite powder or further machinability improving powder (MnS) was added to (alloy steel powder: SUS 304) and mixed, and kneaded to obtain a mixed powder. The blending amount of each powder was determined so as to have the composition of the sintered body shown in Table 1.

[0040]

[Table 1]

Next, after filling these mixed powders in a mold and press-molding with a molding press, a wear-resistant ring main body of a predetermined size is bisected in the height direction, as shown in FIG. 5 (a). A pair of ring-shaped green compacts (outer diameter: 100 mmφ) were produced. The green compact has a ring groove equivalent portion on the outer peripheral side and a stepped portion on the inner peripheral surface. For comparison, a green compact having no stepped portion on its inner peripheral surface was also manufactured.

Further, a stainless steel pipe (10 mmφ) was used to obtain an outer peripheral shape that matches the inner peripheral shape of the wear resistant ring main body by pressing, and further wear resistant to the outer peripheral surface by cutting the shape shown in FIG. A ring material for forming a cooling cavity, in which a stepped portion of the main body can be fitted and a notch portion which can be joined is formed, is manufactured. The cooling cavity forming ring material was sized so that the top ring could be cooled.

Next, the above-mentioned pair of ring-shaped green compacts are stacked in the height direction as shown in FIG. 5 (b), and a ring material for forming a cooling cavity is formed on the inner peripheral side of the pair of green compacts. , The gap between 21a (21b) and 31a (31b), so that the tip of the stepped portion of the inner peripheral surface of the pair of powder compacts and the bottom of the cutout portion of the cooling cavity forming ring material are joined. , 0.15m at t ₁
A space of 0.05 mm was set at m and t ₂ and the _two were assembled facing each other and subjected to a sintering treatment (atmosphere: vacuum) at 1200 ° C. for 60 min. By this sintering process, the green compact becomes a sintered body, and further, a pair of green compacts are sintered and bonded together to form a ring carrier body, and the ring carrier body sandwiches the cooling cavity forming ring material. Then, the wear-resistant ring body and the ring material for forming the cooling cavity are sinter-bonded to form the wear-resistant ring with the cooling cavity.

These wear resistant rings with cooling cavities were attached to the ring groove portions of the piston mold. Then, after pouring the molten aluminum alloy (JIS AC8A) into the mold,
Molten metal forging was applied to finish the piston shape to the specified dimensions.
In the example of the present invention, no accident occurred in which the wear resistant ring main body and the ring material for forming the cooling cavity were separated during casting into the piston (out of 20 pieces). On the other hand, if the wear-resistant ring body having a flat inner peripheral side is used, the wear-resistant ring body and the ring material for forming the cooling cavity are separated when the product is cast into the piston (13 pieces /
There were 20 pieces).

Further, as a conventional example, a wear resistant ring in which a salt core is arranged close to the inner circumference side of the wear resistant ring is mounted in a portion corresponding to the ring groove of the piston mold, and molten aluminum alloy (JIS AC8A) is placed in the mold. After pouring, it was subjected to molten metal forging and finished into a piston shape with predetermined dimensions. However, in the conventional example manufactured in this way, the gap between the wear resistant ring and the cooling cavity was larger than that in the example of the present invention, and there was a concern that the cooling capacity would decrease.

[0046]

According to the present invention, when the wear-resistant ring is cast into the piston, the wear-resistant ring body and the cooling cavity forming material can be stably prevented from being separated from each other, and the productivity of the wear-resistant ring can be improved. It produces a marked effect.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing an example of a wear resistant ring with a cooling cavity according to the present invention.

FIG. 2 is a cross-sectional view schematically showing an example of the shape of the wear resistant ring body.

FIG. 3 is a sectional view schematically showing an example of the shape of a cooling cavity forming ring material.

FIG. 4 is a sectional view schematically showing an example of a wear resistant ring with a cooling cavity according to the present invention.

FIG. 5 is a cross-sectional view that schematically shows an example of the shapes of a pair of green compacts that form the ring carrier body.

FIG. 6 is a cross-sectional view schematically showing an example of a state in which a ring material for forming a cooling cavity is incorporated into a pair of green compacts forming an anti-wear ring body.

FIG. 7 is a cross-sectional view schematically showing an example of a conventional example of a piston which is cast-wrapped with a wear-proof ring integrally formed with a cooling cavity.

[Explanation of symbols]

1 Wear ring 2 Anti-wear ring body 2a, 2b green compact (member) 21a, 21b Stepped part 22,22a, 22b Piston ring groove 3 Ring material for forming cooling cavities 31a, 31b Notch

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02F 3/00 F02F 3/00 GN 302 302 302Z 3/22 3/22 A F16J 9/00 F16J 9/00 A

Claims (12)

[Claims] 1. A wear-resistant ring with cooling cavities comprising a wear-resistant ring main body made of a porous metal sintered body and an annular cooling cavity-forming ring member joined to the inner peripheral side of the wear-resistant ring main body, The wear resistant ring main body is sintered and joined at a predetermined position in the height direction, and a stepped portion is formed on the inner peripheral surface over the entire circumference on both sides of the end portion so that the cross section has a substantially U shape. A wear resistant ring with a cooling cavity, characterized in that the ring material for forming a cooling cavity is sintered and joined so as to sandwich the ring material for forming a cooling cavity in the stepped portion. 2. The cooling cavity forming ring member has, on the outer peripheral surface thereof, a cutout portion configured so that the tip of the stepped portion can be fitted and joined thereto, and at least the stepped portion. The wear resistant ring with a cooling cavity according to claim 1, wherein the tip and the bottom of the notch are sintered and joined together. 3. The inner peripheral surface of the wear resistant ring main body and the outer peripheral surface of the cooling cavity forming ring material have a clearance of a predetermined value or more except for the stepped portion. A wear-resistant ring with a cooling cavity according to 1. 4. The wear resistant ring with cooling cavities according to claim 1, wherein the cooling cavity forming ring material has a size up to a position corresponding to a second ring in the height direction. 5. A sinter-bonding method in which the cooling cavity forming ring member is sandwiched between the stepped portions,
The wear resistant ring with a cooling cavity according to claim 1, wherein the stepped portion is sintered and bonded so as to hold the cooling cavity forming ring material. 6. The wear resistant ring main body has a size capable of forming two ring grooves, and a predetermined position in the height direction is set to two.
The wear resistant ring with a cooling cavity according to any one of claims 1 to 5, wherein the points are sintered and joined. 7. The mass percentage of the porous metal sintered body is C: 0.1 to 1.5%, Si: 1.0% or less, Mn: 2.0% or less, P: 0.1% or less, S: 0.03% or less, Ni. : 5.0 to 15.0%, Cr: 15.0 to 25.0%, the balance being a porous austenitic stainless steel sintered body having a composition of substantially Fe. A wear ring with a cooling cavity as described. 8. A graphite powder is mixed with an alloy powder to form a mixed powder, and the mixed powder is formed into a ring shape to form a green compact, and then an annular cooling is provided on the inner peripheral side of the green compact. A method for producing a wear ring with cooling cavities, which comprises incorporating a cavity-forming ring material and sintering-bonding the green compact and the cooling cavity-forming ring material, wherein the green compact has a piston ring groove on its outer periphery. A wear-resistant ring of a substantially predetermined shape is divided into two parts in the height direction, and a stepped portion is formed on the inner peripheral surface over the entire circumference of the end portion so that the cross section after sintering is substantially U-shaped. A pair of green compacts, and a predetermined gap is set on the inner peripheral side of the green compact so that the pair of green compacts can be joined so as to sandwich the cooling cavity forming ring material. A method for manufacturing a wear-resistant ring with a cooling cavity, comprising incorporating a ring-forming ring material and sintering the ring material. 9. The cooling cavity forming ring member, wherein the cooling cavity forming ring member has a notch portion formed on an outer peripheral surface thereof so as to be capable of contacting with a tip of the stepped portion. The method for manufacturing a wear resistant ring with a cooling cavity according to claim 8, wherein a material is incorporated so that at least the tip of the stepped portion and the bottom portion of the notch portion can be sintered and joined. 10. The stepped portion length and / or the stepped portion length so that the inner peripheral surface of the wear resistant ring main body and the outer peripheral surface of the cooling cavity forming ring material have a clearance of a predetermined value or more except for the stepped portion. The method according to claim 8 or 9, wherein the depth of the notch is adjusted. 11. The alloy powder, in mass%, Ni: 5.0
The method for producing a wear resistant ring with a cooling cavity according to any one of claims 8 to 10, which is an austenitic stainless steel powder containing -15.0% and Cr: 15.0-25.0%. 12. The austenitic stainless steel powder contains Ni: 5.0 to 15.0% or less and Cr: 15.0 to 25.0%,
Furthermore, C: 0.3% or less, Si: 1.0% or less, Mn: 2.0%
12. The method for producing a wear resistant ring with a cooling cavity according to claim 11, wherein the composition has P: 0.1% or less, S: 0.03% or less, and the balance is substantially Fe.