JP2006052671A - Method for manufacturing piston and friction pressure welding structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a piston and a friction pressure welding structure securing joining strength between the piston and a reinforcement member. <P>SOLUTION: An annular groove part 7 is formed on an inner circumference surface 6 of a clamp bush 5 and flowing material between matrix materials is filled in a first filled part 17 formed with including the groove part 7 to regulate flow of flowing material between the matrix materials. Consequently, creation of bur is suppressed and propulsion force acting between the matrix materials is increased to enable to increase pressure welding pressure between the matrix materials. Structure of a joining part between matrix material becomes fine and joining strength between the matrix materials is secured. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a piston manufacturing method and a friction welding structure, and more particularly, a method for joining a reinforcing member to the top of a piston used in a diesel engine by friction welding, and a friction welding for joining the reinforcing member to a piston. Concerning structure.

  In an internal combustion engine, particularly a diesel engine, in order to meet the demand for higher output and higher efficiency of the engine, the shape of the combustion chamber is devised by a recess provided at the top of the piston, and combustion is controlled. Such a diesel engine employs a piston made of an aluminum alloy that is lightweight and excellent in mechanical properties at high temperatures. And in order to meet the said request | requirement, the periphery of the recessed part provided in the top part of a piston needs to be formed in a ridge angle. However, in the case of an aluminum alloy piston, when the peripheral edge formed in the concave portion is formed at a ridge angle, the thermal stress accompanying the operation of the engine concentrates and the peripheral ridge angle formed in the concave portion cracks. May occur. Therefore, Patent Document 1 discloses a piston made of an aluminum alloy in which a reinforcing member formed by rapidly solidifying and forming a rapidly solidified aluminum alloy powder in an annular shape is embedded in the periphery or the entire top of the recess to improve the heat resistance of the recess. A manufacturing method is disclosed.

In the piston manufacturing method of Patent Document 1, the reinforcing member is joined to the top of the aluminum alloy piston main body by friction welding. At the time of friction welding, the mother body softened by heat generation due to frictional resistance between the base materials. The material of the butt portion between the materials is extruded while being plastically flowed by the volume of the reinforcing member, and the extruded material becomes a burr. Therefore, in the above piston manufacturing method, even if the thrust between the base materials is increased, only burrs are increased, and the pressure between the base materials cannot be sufficiently increased. For this reason, the abutting portion between the base materials is not sufficiently stirred, the structure of the joint portion becomes rough, and the bonding strength between the base materials is not ensured. Further, since the abutting portion between the base materials is not sufficiently stirred, the fiber flow along the circumferential direction of the piston is not sufficiently formed in the tissue of the joint portion, and the longitudinal direction (piston sliding direction) in the joint portion. There is a risk of cracks extending to In addition, in the above piston manufacturing method, when the upset pressure is increased, even if the upset thrust is increased, the upset pressure cannot be sufficiently increased only by increasing the burr. It is difficult to ensure the bonding strength.
JP-A-63-256287 (page 2, right upper orchid 3rd line to page 2 left lower orchid 20th line, FIGS. 1 to 4)

Therefore, the present invention has been made in view of the above circumstances, and a first object is to provide a method for manufacturing a piston in which the bonding strength between the piston and the reinforcing member is ensured.
A second object is to provide a friction welding structure in which the bonding strength between the piston and the reinforcing member is ensured.

  In order to achieve the first object, the invention according to claim 1 of the present invention is a method of manufacturing a piston in which at least a peripheral edge of a recess provided in a top portion of a piston body is reinforced by a reinforcing member, The piston main body held by the piston holding means and the reinforcing member held by the reinforcing member holding means are brought into contact with each other, and a thrust is applied between the piston main body and the reinforcing member, and the piston main body and the reinforcing member are relatively rotated. In addition, frictional heat is generated at the abutting portion between the piston body and the reinforcing member, and the flow of the material of the abutting portion that is softened and plastically flowed by the frictional heat is restricted, so that the piston body and the reinforcing member are friction-welded. It is characterized by making it.

According to a second aspect of the present invention, in the method for manufacturing a piston according to the first aspect, the plastically flowable material of the abutting portion is formed including an annular groove provided in the piston holding means or the reinforcing member holding means. The first filling portion is filled to restrict the flow of the material of the butted portion.
The invention according to claim 3 is the method of manufacturing a piston according to claim 1 or 2, wherein the material to be plastically flowed in the abutting portion is a recess provided at the top of the piston body and a reinforcing member holding means or a reinforcing member. The second filling portion formed in the gap is filled to restrict the flow of the material of the butt portion.

  In order to achieve the second object, according to a fourth aspect of the present invention, in the invention, the reinforcing member that reinforces at least the peripheral edge of the concave portion provided on the top of the piston body is friction-welded to the piston body. The friction welding structure used is a piston holding means for holding a piston body, a reinforcing member holding means for holding a reinforcing member, a top restraining means for restraining the top of the piston body in the radial direction, and a piston body And a flow restricting means for restricting the flow of the material of the abutting portion by being filled with a softened and plastically flowable material of the abutting portion between the reinforcing member and the reinforcing member.

According to a fifth aspect of the present invention, in the friction welding structure according to the fourth aspect, the flow restricting means is provided in the piston holding means or the reinforcing member holding means, and is formed in an annular shape so as to face the top peripheral edge of the piston body. A groove portion is provided, and the first filling portion formed including the groove portion is filled with a material that is softened and plastically flowed at the abutting portion between the piston main body and the reinforcing member.
According to a sixth aspect of the present invention, in the friction welding structure according to the fifth aspect of the present invention, the groove portion is formed in an annular shape and has a flat surface facing the top peripheral edge of the piston body, and the axial cross section has a substantially arcuate shape. And a concave surface formed with one end connected to the flat portion and the other end connected to the constraining surface of the top constraining means.
According to a seventh aspect of the present invention, in the friction welding structure according to any one of the fourth to sixth aspects, the flow restricting means is provided in a gap between the recess provided at the top of the piston body and the reinforcing member or the reinforcing member holding means. A second filled portion is formed, and the second filled portion is filled with a material that is softened and plastically flowed at a butt portion between the piston main body and the reinforcing member.

Therefore, in the first aspect of the invention, since the flow of the material at the abutting portion between the piston body and the reinforcing member is restricted, the generation of burrs is suppressed and the thrust (pressure contact pressure) between the base materials is increased.
According to the second aspect of the present invention, the fluid material between the base materials is filled in the filling portion, and the flow of the fluid material is restricted, so that the generation of burrs is suppressed.
In the invention according to claim 3, the fluid material between the base materials is filled in the gap between the concave portion provided at the top of the piston body and the reinforcing member holding member or the reinforcing member, and the flow of the fluid material is restricted. .

In the invention according to claim 4, the absolute amount of the fluid material is restricted by the flow restricting means while the fluid restraining material between the base materials is restrained from flowing in the radial direction of the piston body by the top restraining means. .
In the invention according to claim 5, the fluidized material between the base materials is filled in the filled portion formed including the groove portion.
In the invention according to claim 6, the filled portion includes a groove portion in which a flat surface and a concave surface are formed.
According to the seventh aspect of the present invention, the fluid material between the base materials is filled in the gap between the concave portion provided at the top of the piston body and the reinforcing member or the holding member to which the reinforcing member is attached.

  It is possible to provide a piston manufacturing method and a friction welding structure in which the bonding strength between the piston and the reinforcing member is ensured.

  An embodiment of the present invention will be described with reference to FIGS. This friction welding structure is used when the annular reinforcing member 3 is friction welded to the top 2 of a piston body 1 for an aluminum alloy casting diesel engine, and holds the piston body 1. A groove portion 7 is provided on the inner peripheral surface 6 of the clamp bush 5 (piston holding means and top portion restraining means), and a first filled portion 17 (flow restricting means) formed including the groove portion 17; The butt portion 8 between the piston body 1 and the reinforcing member 3 is softened and plasticized to the second filled portion 18 (flow restricting means) formed including the recess 4 provided in the top portion 2 of the piston body 1. A material to be fluidized (hereinafter referred to as a fluid material between the base materials) is filled. Thereby, in this friction welding structure, since the flow of the fluid material between the base materials at the time of the friction welding process is limited, it becomes possible to increase the pressure of the butt portion 8 and suppress the generation of burrs. By sufficiently agitating the material of the butt 8, the bonding strength between the piston body 1 and the reinforcing member 3 is ensured.

  The reinforcing member 3 is formed by solidification molding of rapidly solidified aluminum alloy powder, and as shown in FIG. 1, one side surface (the right side surface in FIG. 1 as viewed in FIG. 1) is inclined with respect to the axis perpendicular to the axis ( * If necessary, please tell us the degree of inclination.) In the friction welding structure, the other side of the reinforcing member 3 (the left side portion in the drawing in FIG. 1) is attached and fixed to a reinforcing member holder 9 (reinforcing member holding means) mounted on the main shaft of the friction welding apparatus. In this state, one side surface of the reinforcing member 3 is opposed to the top portion 2 of the piston main body 1 held by the clamp bush 5. The clamp bush 5 is formed in a substantially cylindrical shape, and is divided into two by an axial plane as shown in FIG. And in this friction welding structure, the outer peripheral surface 10 of the piston main body 1 is clamped by each inner cylindrical surface of the clamp bush 5 divided into two, and the piston main body 1 is clamped by the clamp bush 5. As shown in FIG. 2, the clamp bush 5 has a gap as a clamping allowance (in this embodiment, 0. About 5 mm). Further, the clamp bush 5 may be divided into three or more as required.

  As shown in FIG. 1, the clamp bush 5 has a top restraint portion 11 (top restraint means) for restraining the top portion 2 of the piston body 1 in the radial direction in the axial direction (left direction in the drawing in FIG. 1). An extension 12 is formed by extension, and an annular groove 7 centering on the axis of the clamp bush 5 is provided on the inner peripheral surface 13 of the extension 12. As shown in FIG. 3, the groove portion 7 has a flat surface that is formed in an annular shape and faces the peripheral edge of the top portion 2 of the piston body 1 in a state where the piston body 1 is clamped by the clamp bush 5. 14 and a concave surface 16 having a substantially arcuate cross section and having one end connected to the flat surface 14 and the other end connected to the constraining surface 15 of the top constraining portion 11. As shown in FIG. 1, at the time of the friction welding process, the reinforcing member holder 9 holding the reinforcing member 3 is inserted into the inner peripheral surface 6 of the clamp bush 5 with a predetermined clearance.

  As shown in FIGS. 1 and 3, in the friction welding structure, the reinforcing member 3 held by the reinforcing member holder 9 is in contact with the piston body 1 held by the clamp bush 5, and The first filled portion 17 is formed in a gap surrounded by the groove portion 7, the reinforcing member 3, and the top portion 2 of the piston body 1, and the concave portion 4 and the reinforcing member 3 provided in the top portion 2 of the piston body 1. The second filled portion 18 is formed in a gap surrounded by the reinforcing member holder 9. In the friction welding structure, each volume of the first filled portion 17 and the second filled portion 18 is such that the flow material between the base materials of the butted portion 8 between the piston body 1 and the reinforcing member 3 is the same. It is set as appropriate according to the flow rate.

  Next, the operation when the piston body 1 and the reinforcing member 3 are joined by friction welding using the friction welding structure will be described. First, the piston body 1 is clamped by the clamp bush 5 and the reinforcing member 3 is attached and fixed to the reinforcing member holder 9 mounted on the main shaft of the friction welding apparatus. Next, while the main shaft is rotated and the reinforcing member 3 is rotated, the reinforcing member 3 is abutted against the top of the piston body 1 with a predetermined thrust. Thereby, the material of the abutting portion 8 between the piston main body 1 and the reinforcing member 3 is softened by the frictional heat generated on the contact surface of the abutting portion 8 and plastically flows. Then, the fluid material between the base materials is filled in the first filled portion 17 and the second filled portion 18, and the plastic flow of the material between the base materials is limited. Thereby, generation | occurrence | production of Paris is suppressed, pressure contact pressure (thrust) is raised, and the fluid material between base materials is fully stirred.

  When the pressure contact temperature of the butted portion 8 between the piston main body 1 and the reinforcing member 2 reaches a predetermined temperature (400 to 500 ° C. in the present embodiment), the relative rotational motion between the base materials (this embodiment) In the embodiment, the rotational movement of the reinforcing member 3 is stopped, and an upset thrust is applied between the base materials. If the upset thrust (* Please indicate the degree of upset thrust if necessary) is maintained between the base materials for a specified time (* If necessary, indicate the degree of retention time) ), The piston body 1 and the reinforcing member 2 are joined. Even during the upset pressurization, the flow of the fluid material is restricted by the first filled portion 17 and the second filled portion 18, so that the generation of burrs is suppressed and the upset thrust can be sufficiently increased. As a result, the bonding strength between the base materials is ensured. Then, the piston main body 1 to which the reinforcing member 3 is joined is removed from the clamp bushing 5 and the material filled in the first filled portion 17 and the second filled portion 18 as shown in FIG. The burrs are removed, and the finishing process is finally performed, so that the product piston shown in FIG. 5 is obtained.

This embodiment has the following effects.
In this friction welding structure, the top restraint portion 11 of the clamp bush 5 faces the inner peripheral surface 13 of the extension portion 12 formed by extending in the axial direction and the top periphery of the piston body 1 held by the clamp bush 5. An annular groove portion 7 is formed to form a first filled portion 17 surrounded by the groove portion 7, the reinforcing member 3, and the top peripheral edge of the piston body 1, and provided at the top portion 2 of the piston body 1. A second filled portion 18 is formed in a space surrounded by the recess 4, the reinforcing member 3, and the reinforcing member holder 9.
Therefore, with this friction welding structure, during the friction welding process, the fluidized material softened by the frictional heat between the base materials and plastically flowed is filled into the first filled portion 17 and the second filled portion 18. Thus, the flow of the fluid material between the base materials is restricted.

  Thereby, generation | occurrence | production of a burr | flash is suppressed and it becomes possible to raise the thrust made to act between base materials, and to increase the press-contact pressure of the said butt | matching part 8. FIG. For this reason, the fluidized material is sufficiently pressurized and agitated, the structure of the joint becomes dense, and the joining strength between the base materials is ensured. Further, a fiber flow along the circumferential direction of the piston is formed at the joint between the base materials, and it is possible to prevent a crack extending in the vertical direction (piston sliding direction) from occurring at the top of the piston. Further, by suppressing the generation of burrs, the upset thrust can be sufficiently increased, whereby the structure of the joint becomes dense and the joint strength between the base materials is ensured. Furthermore, by increasing the upset thrust (pressure contact pressure), it becomes possible to suppress the pressure contact temperature to 400 to 500 ° C., and it is not necessary to melt the reinforcing member 3 formed by solidifying and forming the rapidly solidified aluminum alloy powder. The strength of the reinforcing member 3 is ensured.

  Further, in this friction welding structure, the groove portion 7 constituting the first filled portion 17 is provided with the concave surface 16 whose axial cross section is formed in a substantially arcuate shape, so that the fluid material between the base materials is along the concave surface 16. Since the first filling portion 17 is smoothly flowed and quickly filled into the first filling portion 17, the fluid material between the base materials is sufficiently pressurized and stirred in a short time, The bonding strength between them is ensured.

In addition, embodiment is not limited above, For example, you may comprise as follows.
In the present embodiment, one side of the reinforcing member 3 (the portion that abuts against the piston body 1) is inclined with respect to the plane perpendicular to the axis of the reinforcing member 3, but as shown in FIG. You may comprise so that it may form in parallel with respect to an axis perpendicular surface, and the outer peripheral surface of the reinforcement member 3 may form the outer peripheral surface of a piston.
In the present embodiment, the reinforcing member 3 formed in an annular shape and held by the reinforcing member holder 9 is joined to the top portion 2 of the piston body 1 by friction welding. However, as shown in FIG. The member holder 9 is abolished, and one end of a round bar formed by solidifying and forming the rapidly solidified aluminum alloy powder is joined to the top of the piston body 1 by friction pressure welding. The reinforcing member 3 may be cut by cutting.
In the present embodiment, a top restraint portion 11 (top restraint means) for restraining the top portion 2 of the piston body 1 in the radial direction is provided on the clamp bush 5 to extend the top restraint portion 11 to form an extension portion 12. Although the annular groove portion 7 is provided on the inner peripheral surface 13 of the extension portion 12, as shown in FIG. 8, the top restraint portion 11 and the annular groove portion 7 are connected to the reinforcing member holder 9 (reinforcing member holding means). ) May be provided on the head portion 19 at one end (right end in FIG. 8) to constitute a friction welding structure.

It is explanatory drawing of this friction welding structure. It is explanatory drawing of this friction welding structure, and is a figure which shows that a clamp bush is the structure divided | segmented by the axial plane. It is the A section enlarged view in FIG. It is a figure which shows the piston of the state from which the burr | flash produced at the time of friction welding was removed after joining a piston main body and a reinforcement member. It is a figure which shows the piston (product) in which the finishing process was given from the state in FIG. It is explanatory drawing which shows the other form of a reinforcement member. It is explanatory drawing which shows the other form of a reinforcement member. It is explanatory drawing which shows another friction welding structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston main body, 2 Top part, 3 Reinforcement member, 4 Recessed part, 5 Clamp bush (Piston holding means), 7 Groove part, 8 Butting part, 9 Reinforcement member holder (Reinforcement member holding means), 11 Top part restraint part (Top part restraint means) ), 14 flat surface, 15 constraining surface, 16 concave surface, 17 first filled portion (flow restricting means), 18 second filled portion (flow restricting means)

Claims (7)

  A piston manufacturing method in which at least a peripheral edge of a concave portion provided on a top portion of a piston main body is reinforced by a reinforcing member, the piston main body held by a piston holding means, and the reinforcing member held by a reinforcing member holding means, The piston main body and the reinforcing member are relatively rotated while applying thrust between the piston main body and the reinforcing member, and friction heat is applied to the abutting portion between the piston main body and the reinforcing member. A manufacturing method of a piston, characterized in that the piston body and the reinforcing member are friction-welded with each other by restricting the flow of the material of the butted portion that is softened and plastically flowed by the frictional heat.   The material to be plastically flowed in the butt portion is filled in a first filled portion formed including an annular groove provided in the piston holding means or the reinforcing member holding means, and the material of the butt portion is The method for producing a piston according to claim 1, wherein flow is limited.   The material to be plastically flowed in the abutting portion is filled in a second filling portion formed in a gap between the concave portion provided on the top of the piston body and the reinforcing member holding means or the reinforcing member, and the abutting is performed. The method for manufacturing a piston according to claim 1, wherein the flow of the material of the portion is restricted.   The reinforcing member that reinforces at least the peripheral edge of the concave portion provided on the top of the piston body is a friction welding structure used when the piston body is friction-welded, the piston holding means for holding the piston body, and the reinforcing member A reinforcing member holding means for holding the piston body, a top restraining means for restraining the top portion of the piston body in the radial direction, and a softened and plastically flowable material of the butted portion of the piston body and the reinforcing member. And a flow restricting means for restricting the flow of the material of the abutting portion.   The flow restricting means includes a groove portion that is provided in the piston holding means or the reinforcing member holding means and is formed in an annular shape so as to face the periphery of the top portion of the piston body, and is formed by including the groove portion. 5. The friction welding structure according to claim 4, wherein the filling portion is filled with a material that is softened and plastically flowed at a butt portion between the piston body and the reinforcing member.   The groove is formed in an annular shape with a flat surface facing the top peripheral edge of the piston body, an axial cross section is formed in a substantially arcuate shape, one end is connected to the flat part, and the other end is the top. 6. The friction welding structure according to claim 5, wherein a concave surface connected to the restraining surface of the restraining means is formed. The flow restricting means includes a second filling portion formed in a gap between a concave portion provided on the top of the piston body and the reinforcing member or the reinforcing member holding means, and the second filling portion is provided with the second filling portion. The friction welding structure according to any one of claims 4 to 6, wherein a material that is softened and plastically flows at a butted portion between the piston main body and the reinforcing member is filled.

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