JP2007085201A - Method of manufacturing piston for internal combustion engine, and piston for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a piston for an internal combustion engine capable of easily positioning a pipe member, reducing materials to be used, and providing a structure with high cooling effect. <P>SOLUTION: The pipe member 21 cast in a piston comprises a pipe body part 22 and a flange part 23 formed in a flange shape from the radial outer portion of the body part 22. These parts are formed of a same metal material. Next, the pipe member 21 is immersed in an aluminum molten metal with the same composition as the body of the piston 10 to form film on the surfaces of the pipe body part 22 and the flange part 23. The pipe member 21 is placed with the flange part 23 placed on a step part 31b formed on the inner peripheral surface 31a of an outer mold 31 and positioned in a casting mold 30. Then, aluminum molten metal is poured into the casting mold 30 to form a piston intermediate body in which the pipe member 21 is cast, and the outer surface of the piston intermediate body is machined and polished to form the outline of the piston 100. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a piston for an internal combustion engine configured by casting a pipe member together with a piston to form a cooling cavity, and a method for manufacturing the same.

  During the operation of the internal combustion engine, the piston receives a high-temperature combustion gas and thus becomes hot. For this reason, for example, there is a possibility that various problems (piston ring breakage, etc.) may occur due to piston cracks due to a decrease in material strength, and ring wear provided on the outer periphery of the piston.

  In order to prevent these problems, a cooling cavity is formed inside the piston head near the combustion chamber. The cooling cavity is opened on the inner surface side of the piston to which oil is sprayed for piston cooling, and the piston is cooled by the oil spraying, and the sprayed oil circulates in the cavity from the opening. The structure is cooled.

In order to form such a cooling cavity in a piston, for example, Patent Document 1 proposes a technique in which a pipe member is cast together with casting of a piston.
Specifically, in Patent Document 1, a guide pipe is brazed to one side of an annular pipe member to form a hollow member, the hollow member is set in a mold, and molten aluminum alloy is poured into the mold. As a result, a piston having a cooling cavity is manufactured.

  By the way, since the guide pipe of the hollow member serves as an inlet / outlet of oil, it is necessary to open it at the inner surface of the piston. In addition, since this guide pipe also plays a role of supporting the hollow member in the mold, it is necessary to support the guide pipe with a core mold for molding the inner surface of the piston.

  In Document 1, a support for supporting the guide pipe is provided in the core type, and the tip end portion of the guide pipe is heated and press-fitted into the support. Therefore, the positioning of the hollow member in the core mold is complicated.

  Therefore, in Patent Document 2, a metal porous body ring is disposed around an annular tube member serving as a cooling cavity, and the metal porous body ring is disposed at a step portion in the mold, and an aluminum alloy is disposed in the mold. A piston manufacturing method is described in which a piston molded body is obtained by pouring a molten metal, and then a piston ring groove is formed in the region of the annular reinforcing portion solidified by the molten aluminum entering the metal porous body ring. .

According to such a technique, positioning of the pipe member constituting the cooling cavity can be performed satisfactorily, and the piston ring groove can be strengthened by forming the piston ring groove in the annular reinforcing portion.
JP-A-10-184450 JP 2001-317628 A

  However, although the metal porous ring and the piston main body side are sufficiently coupled, the coupling between the annular tube member and the piston main body side is not sufficiently considered. Therefore, when the pipe member is made of a material different from that of the piston main body side, the pipe member and the piston main body side do not sufficiently adhere to each other, and an air layer serving as a heat insulating layer is formed between them. There is a problem that the effect cannot be obtained. Further, since the pipe member and the metal porous ring are made of different materials, there is a problem that the number of materials used for the piston increases.

  The present invention has been made to solve the above-described problems, and an object of the present invention is a method for manufacturing a piston for an internal combustion engine in which a cooling cavity is formed by casting a pipe member, and a piston for an internal combustion engine. An object of the present invention is to provide a method for manufacturing a piston for an internal combustion engine and a piston for an internal combustion engine that can easily position a pipe member during molding, reduce the material used, and have a structure with a high cooling effect.

  In order to solve the above-mentioned problems, the invention described in claim 1 is a manufacturing of a piston for an internal combustion engine which is made of an aluminum alloy and which is formed by casting a pipe member together with the casting of the piston so as to form a cooling cavity. A pipe main body portion that forms a hollow ring to form the cooling cavity, and a flange portion that is provided in a flange shape from a radially outer portion of the pipe main body portion, the pipe main body portion and the A step of producing the pipe member in which the flange portion is made of the same metal material; and the pipe member is immersed in a molten aluminum alloy having the same composition as that of the piston main body side, and is formed on the surfaces of the pipe main body portion and the flange portion. A step of forming a coating; and the flange portion of the pipe member is placed on a step portion provided on the inner peripheral surface of the mold, and the step portion and the inner peripheral surface are positioned. A step of supporting the pipe member in the mold, a step of forming a piston intermediate body in which the pipe member is cast by pouring molten aluminum alloy constituting the piston in the mold, and the mold And the step of cutting and polishing the outer surface of the piston intermediate formed to form the outer shape of the piston.

  According to a second aspect of the present invention, in the method for manufacturing a piston for an internal combustion engine according to the first aspect, the outer periphery of the piston has a ring groove for mounting a piston ring, and the flange portion constitutes the piston. The gist of the present invention is that the flange portion is exposed to the ring groove when the ring groove is formed by the cutting and polishing.

  The gist of the invention described in claim 3 is that, in the method for manufacturing a piston for an internal combustion engine according to claim 2, the flange portion is exposed on the lower inner wall surface of the ring groove.

  According to a fourth aspect of the present invention, in the method for manufacturing a piston for an internal combustion engine according to the second or third aspect, the position of the stepped portion is such that the flange portion of the pipe member is at a position corresponding to the ring groove. The gist is that is set.

  According to a fifth aspect of the present invention, in the method for manufacturing a piston for an internal combustion engine according to any one of the first to fourth aspects, a portion to be cut and polished of the flange portion is placed on the stepped portion. This is the gist.

  The invention according to claim 6 is an internal combustion engine piston which is made of an aluminum alloy and which is formed by casting a pipe member together with a piston to form a cooling cavity. A pipe body portion having a hollow annular shape to form a cooling cavity, and a flange portion extending in a flange shape from a radially outer portion of the pipe body portion to an outer periphery of the piston, the pipe body portion and the pipe The gist is that the flange portion is made of the same metal material, and a coating made of an aluminum alloy having the same composition as the piston main body is formed on the surfaces of the pipe main body portion and the flange portion.

  A seventh aspect of the present invention is the internal combustion engine piston according to the sixth aspect, wherein the piston has a ring groove for mounting a piston ring on the outer periphery of the piston, and the flange portion constitutes the piston. The gist of the present invention is that it is formed of a metal material having higher hardness and exposed to the ring groove.

The gist of the invention according to claim 8 is that, in the piston for the internal combustion engine according to claim 7, the flange portion is exposed on the lower inner wall surface of the ring groove.
(Function)
According to the first aspect of the present invention, the pipe member cast into the piston includes a pipe body portion having a hollow annular shape, and a flange portion provided in a flange shape from a radially outer portion of the pipe body portion. The pipe body and the flange are made of the same metal material. Next, the pipe member is immersed in a molten aluminum alloy having the same composition as that of the piston body, and a coating is formed on the surfaces of the pipe body and the flange. Next, the flange portion of the pipe member is placed on the step portion provided on the inner peripheral surface of the mold, positioned by the step portion and the inner peripheral surface, and supported in the mold. Next, molten aluminum alloy constituting the piston is poured into the mold to form a piston intermediate body in which a pipe member is cast, and the outer surface of the formed piston intermediate body is cut and polished to remove the piston. An outline is formed. Thus, a piston having a cooling cavity inside is manufactured. Thus, the pipe member can be easily positioned and supported in the mold simply by providing the pipe member with the flange portion and placing the flange portion on the stepped portion in the mold. In addition, since the pipe main body portion and the flange portion of the pipe member are formed of the same metal material, the number of materials used for the pipe member and hence the piston can be reduced. In this case, the pipe member can be integrally formed, and the number of parts of the pipe member, and hence the piston, can be reduced. Furthermore, since the pipe member is immersed in a molten aluminum alloy having the same composition as that of the piston main body and a coating is formed on the surfaces of the pipe main body and the flange, the pipe main body, the flange and the piston are formed at the time of piston molding. Adhesion with the main body side becomes high. As a result, the formation of an air layer serving as a heat insulating layer between the pipe member and the piston body can be reduced as much as possible, the thermal conductivity from the piston body side to the pipe member side, i.e., the cooling cavity side, is improved, and the cooling effect It becomes a high structure.

  According to invention of Claim 2, 7, the flange part of a pipe member is formed with a metal material whose hardness is higher than the metal material which comprises a piston, and is exposed in a ring groove. Thereby, the wear resistance of the portion where the flange portion in the ring groove is exposed is improved, and a piston in which the progress of wear is moderate can be manufactured.

  According to invention of Claim 3, 8, the flange part of a pipe member is exposed to the lower inner wall face of a ring groove, and comprises this lower inner wall face. That is, when a piston ring that directly receives the pressure of the combustion gas is attached to this ring groove, the lower inner wall surface of the ring groove receives a large pressing force from the piston ring. By constituting the lower inner wall surface with a flange portion made of a metal material having high hardness, it is possible to manufacture a piston in which the wear resistance of the lower inner wall surface is improved and the progress of wear is moderate.

  According to the invention described in claim 4, the position of the stepped portion is set so that the flange portion of the pipe member is located at a position corresponding to the ring groove. Thereby, the flange portion can be positioned in the ring groove while the flange portion has a simple flat plate shape.

  According to the invention described in claim 5, the portion of the flange portion to be cut and polished is placed on the step portion. Thereby, the freedom degree of the shape of the part and step part in which the flange part of a pipe member is mounted can be improved.

  According to the sixth aspect of the present invention, the pipe member cast into the piston extends in a flange shape from the radially outer portion of the pipe body portion to the outer periphery of the piston. And a flange portion. The pipe main body part and the flange part are made of the same metal material, and the pipe main body part and the flange part are formed with a coating made of an aluminum alloy having the same composition as the piston main body side. Since the piston into which such a pipe member is cast can be manufactured by the manufacturing method according to claim 1, the pipe member can be easily positioned and supported in the mold at the time of piston molding as described above, and the material used Thus, a structure with a reduced cooling effect is obtained.

  Therefore, according to the present invention, the pipe member cast into the piston can be easily positioned, the material used can be reduced, and the internal combustion engine piston manufacturing method and the internal combustion engine having a structure with a high cooling effect. An engine piston can be provided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
FIG. 1 shows a piston 10 used in an internal combustion engine. The piston 10 has a substantially cylindrical shape with a hollow below, and three ring grooves 11 to 13 are formed on the outer periphery of the upper portion of the piston 10. Each of the ring grooves 11 to 13 has a substantially rectangular cross section. Piston rings 14 to 16 are mounted in the ring grooves 11 to 13, respectively.

  Among the piston rings 14 to 16, the piston rings 14, 15 mounted in the upper two ring grooves 11, 12 are first and second compression rings that mainly play a role of maintaining the airtightness of the combustion chamber. . The piston rings 14 and 15 have an annular flat plate shape having a cut at one place in the circumferential direction. The piston ring 16 mounted in the lowermost ring groove 13 is an oil ring mainly responsible for scraping off excess oil on the cylinder inner wall surface of the internal combustion engine. The piston ring 16 has a substantially I-shaped cross section and has an annular shape having a cut in one circumferential direction, and a coil expander 17 that urges the ring 16 radially outward is provided inside the piston ring 16. Has been.

  Further, as shown in FIG. 2, an annular cooling cavity 20 is formed along the ring groove 11 on the radially inner side of the uppermost ring groove 11. The cooling cavity 20 is configured inside the piston 10 by casting the pipe member 21 together with the casting of the piston 10. Incidentally, in this Embodiment, the piston 10 main body consists of aluminum alloys, and the pipe member 21 consists of stainless steel whose hardness is higher than the aluminum alloy of the piston 10 main body side.

  The pipe member 21 includes a pipe main body portion 22 that forms a hollow ring shape so as to form the cooling cavity 20, and a flange portion 23 that is provided in a flange shape from a radially outer portion of the pipe main body portion 22. The cooling cavity 20 in the pipe main body portion 22 communicates with a communication hole (not shown) in which an opening is formed on the inner surface side of the piston 10. Oil injected from the lower side (crankcase side) of the piston 10 is sprayed on the inner surface side of the piston 10, and the piston 10 is cooled by spraying the oil, and the sprayed oil is injected into the cavity 20 from the opening. It is structured to be cooled by circulating the air.

  The flange portion 23 of the pipe member 21 extends to the outer periphery of the piston 10 and is exposed at the lower inner wall surface 11a of the ring groove 11 to constitute the lower inner wall surface 11a. That is, the lower inner wall surface 11a of the ring groove 11 is a portion that is highly worn because it receives a large pressing force from the piston ring 14 that directly receives the pressure of the combustion gas. By comprising the stainless steel flange portion 23 having a hardness higher than that of the aluminum alloy on the main body side, the wear resistance of the lower inner wall surface 11a is improved, and the progress of wear is moderated.

  Moreover, since the flange part 23 is extended in radial direction, it is possible to absorb the heat from the upper part of the piston 10 with a combustion chamber effectively. In addition, the absorbed heat is transmitted through the flange portion 23 to the cooling cavity 20 side or from the piston ring 14 to the cylinder inner wall surface (not shown) side, so the cooling effect of the piston 10 is great. In particular, since the lower inner wall surface 11a where the flange portion 23 is located is cooled well, this also improves the wear resistance of the lower inner wall surface 11a.

Next, a manufacturing mode of the piston 10 in the present embodiment will be described.
As shown in FIG. 3, the mold 30 for molding the piston 10 includes an outer mold 31, a core mold 32, and an upper mold 33. The outer mold 31, the core mold 32, and the upper mold 33 are provided with piston intermediate bodies (not shown) that are slightly larger than the finished piston 10 (illustrated by the wavy line in FIG. 4) across the molds 31 to 33. A molding recess 34 is formed for formation. That is, the outer die 31 is formed with an inner circumferential surface 31a for molding the outer circumferential surface of the piston intermediate body. Further, the core mold 32 is formed with an outer peripheral surface 32a for molding the inner surface of the piston intermediate body, and the upper mold 33 is formed with a lower surface 33a for molding the upper surface of the piston intermediate body. ing. The outer mold 31 is formed with a pouring port (not shown) for pouring molten aluminum alloy (molten aluminum).

  Further, an annular step portion 31 b is formed on the inner peripheral surface 31 a of the outer mold 31. The step portion 31b is provided for placing the pipe member 21 inserted into the molding recess 34 from the upper mold 33 side. The mounting surface in the step portion 31b is a flat surface. The flange portion 23 of the pipe member 21 placed on the stepped portion 31b is formed larger outside in the radial direction than the finished piston 10 in the same manner as the piston intermediate body before cutting and polishing of the piston 10. The outer peripheral portion 23a that protrudes radially outward from the piston 10 of the finished product is placed on the step portion 31b. Further, the flange portion 23 placed on the step portion 31b is set at a position (height) corresponding to the uppermost ring groove 11 of the finished piston 10.

  Here, the pipe member 21 of the present embodiment is configured as shown in FIG. As shown in FIG. 5 (a), a hollow stainless steel pipe material is bent into an annular shape and ends thereof are joined together to form a pipe body portion 22. In addition, as shown in FIG.5 (d), you may comprise the annular pipe main-body part 22 using the connection pipe 24 and inserting and crimping each edge part of a pipe material. On the radially outer part of the pipe body 22 configured in an annular shape, a stainless steel ring material having a flat plate shape as shown in FIG. Is done. As a result, as shown in FIG. 5C, the pipe member 21 having the flange portion 23 on the radially outer portion of the pipe main body portion 22 is configured. In this case, the outer diameter of the flange portion 23 is set larger than the outer diameter of the finished piston 10.

  Further, the surface of the pipe member 21 configured as described above is in close contact with the aluminum alloy on the piston 10 main body side so that an air layer serving as a heat insulating layer is not formed between the piston 10 main body and the piston 10 main body as much as possible. Aluminizing (coating treatment) is performed to increase the properties. More specifically, the pipe member 21 is first preheated, and the preheated pipe member 21 is crushed in an aluminum melt having the same composition as the aluminum alloy constituting the main body of the piston 10. In this case, the same type of molten aluminum having a slightly different composition may be used instead of the completely same composition. Then, after a predetermined time has elapsed, the pipe member 21 is taken out from the molten aluminum, and a 10 to 20 μm film (not shown) is formed on the surface of the pipe member 21. This coating improves the adhesion between the pipe member 21 and the piston 10 main body.

  In manufacturing the piston 10, first, as shown in FIGS. 3 and 4, the flange portion 23 (outer peripheral portion 23 a) of the pipe member 21 is placed on the step portion 31 b of the outer mold 31. The upper mold 33 is closed by positioning with the inner peripheral surface 31a. Next, molten aluminum is poured into the molding recess 34 from the pouring port, and after cooling, the upper mold 33 is opened, and the piston intermediate body into which the pipe member 21 is cast is taken out from the molding recess 34. When the molten aluminum is poured, if the wraparound to the lower surface side of the flange portion 23 is not good, measures such as air bleeding are taken for the outer mold 31.

  Next, the outer surface of the piston 10 is cut and polished to form the outer shape of the finished product including the ring grooves 11 to 13 on the extracted piston intermediate. At this time, simultaneously with the cutting and polishing of the outer surface of the piston 10, the outer peripheral portion 23 a of the flange portion 23 of the pipe member 21 is also processed. As the ring groove 11 is formed, the flange portion 23 is exposed at the lower inner wall surface 11 a of the ring groove 11. Although not shown, a communication hole communicating with the cooling cavity 20 of the pipe member 21 is formed on the inner surface of the piston 10, and oil can be circulated into the cooling cavity 20. Thus, the piston 10 of the present embodiment as shown in FIGS. 1 and 2 is manufactured through these steps.

Next, characteristic actions and effects of the present embodiment will be described.
(1) The pipe member 21 to be cast into the piston 10 includes a pipe main body portion 22 having a hollow annular shape, and a flange portion 23 provided in a flange shape from a radially outer portion of the pipe main body portion 22. The pipe body 22 and the flange 23 are made of the same metal material. Next, the pipe member 21 is immersed in a molten aluminum having the same composition as that of the main body of the piston 10, and coatings are formed on the surfaces of the pipe main body portion 22 and the flange portion 23. Next, the pipe member 21 is placed on the step portion 31b provided on the inner peripheral surface 31a of the outer mold 31 in which the flange portion 23 constitutes the mold 30, and is positioned by the step portion 31b and the inner peripheral surface 31a. Supported in the mold 30. Next, molten aluminum is poured into the mold 30 to form a piston intermediate body (not shown) having the pipe member 21 therein, and the outer surface of the formed piston intermediate body is cut and polished to produce the piston 10. Is formed. Thus, the piston 10 having the cooling cavity inside is manufactured. Thus, the pipe member 21 can be easily positioned and supported in the mold 30 simply by providing the pipe member 21 with the flange portion 23 and placing the flange portion 23 on the stepped portion 31 b in the mold 30.

  In addition, since the pipe main body portion 22 and the flange portion 23 of the pipe member 21 are formed of the same metal material (stainless steel), the number of materials used for the pipe member 21 and thus the piston 10 can be reduced. In this case, the pipe member 21 can be integrally formed as shown in FIG. 6, and the number of parts of the pipe member 21 and thus the piston 10 can be reduced. Furthermore, since the pipe member 21 is crushed in the same molten aluminum as the piston 10 main body side and a film is formed on the surfaces of the pipe main body portion 22 and the flange portion 23, the pipe main body portion 22 and the flange are formed when the piston 10 is formed. Adhesion between the portion 23 and the piston 10 main body side is increased. Thereby, formation of the air layer used as the heat insulation layer between the pipe member 21 and the piston 10 main body can be reduced as much as possible, and the heat conductivity from the piston 10 main body side to the pipe member 21 side, that is, the cooling cavity side becomes good. Thus, the structure has a high cooling effect. And since formation of an air layer is reduced as much as possible, it becomes a highly rigid structure in which the crack in this part does not occur easily.

  (2) The flange portion 23 of the pipe member 21 is formed of a metal material (stainless steel) having a higher hardness than the metal material (aluminum alloy) constituting the piston 10, and is formed on the lower inner wall surface 11 a of the uppermost ring groove 11. And the lower inner wall surface 11a is formed. That is, the lower inner wall surface 11a of the ring groove 11 is a portion that is highly worn because it receives a large pressing force from the piston ring 14 that directly receives the pressure of the combustion gas. By using the flange portion 23 made of a high metal material, the wear resistance of the lower inner wall surface 11a can be improved, and the progress of wear becomes moderate.

  (3) The position (height) of the step portion 31b is set so that the flange portion 23 of the pipe member 21 is at a position corresponding to the uppermost ring groove 11. Accordingly, the flange portion 23 can be positioned in the uppermost ring groove 11 (lower inner wall surface 11a) while the flange portion 23 has a simple flat plate shape.

  (4) The outer peripheral portion 23a to be cut and polished of the flange portion 23 is placed on the step portion 31b. Thereby, the freedom degree of the shape of the outer peripheral part 23a of the flange part 23 of the pipe member 21, or the level | step-difference part 31b can be improved.

The embodiment of the present invention may be modified as follows.
In the above embodiment, the pipe member 21 is composed of two parts, that is, a pipe material corresponding to the pipe main body portion 22 and a ring material corresponding to the flange portion 23. In FIG. Although configured, the present invention is not limited to this.

  For example, as shown in FIG. 6, you may comprise the pipe member 21 by one part. That is, as shown in FIG. 6 (a), a flat plate 25 made of stainless steel is used to form an intermediate member 25a having a recessed intermediate portion as shown in FIG. 6 (b). The pipe body 22 is formed by the recessed portions such as the members 25b and 25c, and both side portions are bonded to each other. Then, the pipe member 21 may be formed by bending the intermediate member 25c as shown in FIG. 6D into an annular shape as shown in FIG. If it does in this way, the number of parts and the number of materials to be used can be reduced, and the number of joints can be reduced.

  In the above embodiment, the material constituting the pipe member 21 is stainless steel, but other materials such as aluminum alloy, iron, copper, and the like similar to the piston 10 may be used. In this case, it is preferable to use a metal material having a hardness higher than that of the aluminum alloy constituting the piston 10 for at least the flange portion 23 of the pipe member 21.

  In the said embodiment, although the flange part 23 of the pipe member 21 was exposed in the lower side inner wall face 11a of the uppermost ring groove 11, an exposed location is not limited to this. For example, the other ring grooves 12 and 13 may be exposed. Moreover, you may expose in the predetermined location of the outer periphery of the piston 10 unrelated to the ring grooves 11-13.

  In the above-described embodiment, the position (height) of the step portion 31b is set so that the flange portion 23 of the pipe member 21 corresponds to the uppermost ring groove 11, but the position of the step portion 31b is For example, the flange portion 23 may be appropriately changed depending on the location where the flange portion 23 is exposed.

  In the above embodiment, the outer peripheral portion 23a to be cut and polished of the flange portion 23 has an annular shape, but may have a shape other than the annular shape. Further, the stepped portion 31b may have a shape other than the annular shape.

It is a fragmentary sectional view of the piston in this Embodiment. It is a principal part expanded sectional view of the piston in this Embodiment. It is sectional drawing which shows the casting_mold | template for shaping | molding of the piston in this Embodiment. It is a principal part expanded sectional view of the casting_mold | template in this Embodiment. (A)-(d) is a perspective view for demonstrating the pipe member in this Embodiment. (A)-(e) is a perspective view for demonstrating the pipe member in another example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Piston, 11-13 ... Ring groove, 11a ... Lower inner wall surface, 14-16 ... Piston ring, 20 ... Cooling cavity, 21 ... Pipe member, 22 ... Pipe main-body part, 23 ... Flange part, 23a ... Cutting and Peripheral part to be polished, 30 ... mold, 31 ... outer mold, 31a ... inner peripheral surface, 31b ... step part.

Claims (8)

A method for manufacturing a piston for an internal combustion engine, which is composed of an aluminum alloy and is formed by casting a pipe member together with a piston to form a cooling cavity,
A pipe body portion having a hollow ring shape to form the cooling cavity, and a flange portion provided in a flange shape from a radially outer portion of the pipe body portion, and the pipe body portion and the flange portion are the same A step of producing the pipe member made of the metal material of
Immersing the pipe member in a molten aluminum alloy having the same composition as the piston body, and forming a coating on the surfaces of the pipe body and the flange; and
Placing the flange portion of the pipe member on a stepped portion provided on the inner peripheral surface of the mold, positioning the stepped portion and the inner peripheral surface, and supporting the pipe member in the mold;
Pouring an aluminum alloy molten metal constituting the piston into the mold to form a piston intermediate in which the pipe member is cast; and
Cutting and polishing an outer surface of the piston intermediate formed by the mold to form an outer shape of the piston;
A method of manufacturing a piston for an internal combustion engine, comprising: In the manufacturing method of the piston for internal-combustion engines according to claim 1,
The outer periphery of the piston has a ring groove for mounting a piston ring,
The flange portion is formed of a metal material having a hardness higher than that of the metal material constituting the piston, and the flange portion is exposed to the ring groove when the ring groove is formed by the cutting and polishing. A method of manufacturing a piston for an internal combustion engine. In the manufacturing method of the piston for internal-combustion engines according to claim 2,
A method for manufacturing a piston for an internal combustion engine, wherein the flange portion is exposed on a lower inner wall surface of the ring groove. In the manufacturing method of the piston for internal-combustion engines according to claim 2 or 3,
The method of manufacturing a piston for an internal combustion engine, wherein the position of the stepped portion is set so that the flange portion of the pipe member is located at a position corresponding to the ring groove. In the manufacturing method of the piston for internal-combustion engines given in any 1 paragraph of Claims 1-4,
A method for manufacturing a piston for an internal combustion engine, wherein a portion of the flange portion to be cut and polished is placed on the step portion. A piston for an internal combustion engine configured by an aluminum alloy and configured by casting a pipe member together with a piston to form a cooling cavity,
The pipe member has a pipe main body portion that forms a hollow ring to form the cooling cavity, and a flange portion that extends in a flange shape from the radially outer portion of the pipe main body portion to the outer periphery of the piston, The pipe body part and the flange part are made of the same metal material, and a coating made of an aluminum alloy having the same composition as the piston body side is formed on the surfaces of the pipe body part and the flange part. A piston for an internal combustion engine. The piston for an internal combustion engine according to claim 6,
The outer periphery of the piston has a ring groove for mounting a piston ring,
The piston for an internal combustion engine, wherein the flange portion is formed of a metal material having a hardness higher than that of a metal material constituting the piston, and is exposed to the ring groove. The piston for an internal combustion engine according to claim 7,
The piston for an internal combustion engine, wherein the flange portion is exposed on a lower inner wall surface of the ring groove.

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