JP2001263240A - Method of manufacturing hollow piston for compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid reduction in joining strength of a bottomed cylindrical member and a blocking-up member. SOLUTION: A metal mold device for molding a body member 162 has an opening-closing mold 270 and slide cores 280 and 282. The slide cores 280 and 282 are arranged so as to be capable of advancing and retreating in the opening- closing mold 270 in the direction parallel to the center line of the bottomed cylindrical part 170 and in the direction orthogonal to the opening-closing direction of the opening-closing mold 270. The opening-closing mold 270 is closed, and in a state of being moved to an advance end position where a shoulder surface 344 of the slide cores 280 and 282 abuts to a shoulder surface 368, a molten metal is injected into a cavity 286 to mold the body member 162. An inner peripheral surface 178 of the bottomed cylindrical part 170 is molded by an outer peripheral surface 346 of a tip part 342 of the slide cores 280 and 282, and an opening side end surface 176 is molded by the shoulder surface 344. A cap is fitted without applying machine work to the inner peripheral surface 178 of the bottomed cylindrical part 170 and the opening side end surface 176 to mutually join mutual close contact end surfaces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow piston for a compressor, and more particularly, to facilitating the manufacture thereof.

[0002]

2. Description of the Related Art Since a piston for a compressor is reciprocated in a cylinder bore, it is required to reduce the weight. For this reason, conventionally, a head that is slidably fitted to a cylinder bore is hollowed. JP-A-11-303747 and JP-A-11-2
The hollow piston for a swash plate type compressor described in Japanese Patent No. 94320 is an example thereof. In order to manufacture such a hollow piston, a piston material having a bottom wall and a cylindrical portion extending from the bottom wall, and having a bottomed cylindrical portion with one end opened, is required. This is because a hollow piston can be obtained by closing the opening of the bottomed cylindrical portion with a closing member. In the manufacturing method described in Japanese Patent Application Laid-Open No. H11-303747, an engaging portion that engages with a reciprocating drive device is formed integrally with a closing member. In the manufacturing method described in Japanese Patent Application Laid-Open No. H11-294320, The joint portion is formed integrally with the bottom wall of the bottomed cylindrical portion.

A die casting method has been proposed as a method for producing a piston material having the above-mentioned bottomed cylindrical portion. This method includes an opening / closing die that opens and closes in a direction perpendicular to the axis of the bottomed cylindrical portion of the piston material, and forms a cavity for molding the outer surface of the bottomed cylindrical portion in a closed state, and an axis of the bottomed cylindrical portion. And a slide core forming an inner surface of the bottomed cylindrical portion while moving in a direction parallel to the direction of the cavity and projecting into the cavity. In the conventional die casting method, the opening-side end surface of the hollow cylindrical portion is formed together with the outer peripheral surface by an opening / closing die. With this configuration, since the slide core only needs to form the inner surface of the hollow cylindrical portion, the slide core can have a simple shaft shape.

[0004]

However, as described above, if the opening-side end face of the bottomed cylindrical portion is formed by an opening / closing mold, the opening-side end face can be opened and closed. It is unavoidable that a large or small beam is generated at a position corresponding to the parting surface of the mold. This burr becomes an obstacle when the opening of the bottomed cylindrical portion is closed by the closing member. The closing member is often joined by welding, bonding, friction welding, or the like in a state where the contact surface of the closing member is in contact with the opening end surface of the bottomed cylindrical portion. This is because if it exists, the contact surface of the closing member cannot be brought into close contact with the opening-side end surface.

[0005] Therefore, conventionally, the closing member is joined after removing the burrs by machining the open end face of the bottomed cylindrical portion, which increases the machining process and increases the manufacturing cost. I was If the machining step of the opening side end face, at least the step of removing burrs, is omitted, an increase in manufacturing cost can be avoided, but a gap is formed between the closing member and the welding, adhesion, friction welding and the like are adversely affected. . Since welding is generally performed by beam welding, the material of the base metal is used to fill gaps, pits are formed on the outer surface of the weld, and in severe cases, holes are formed, which contributes to a decrease in welding strength. Become. In addition, the adhesive layer has a predetermined thickness, such as 0.2 mm, at which the maximum adhesive strength can be obtained. If the gap is larger than the appropriate thickness, this will cause a decrease in the adhesive strength. Friction welding is less susceptible to burrs than beam welding or bonding, but may be adversely affected depending on the size of the burrs.

In the case where the opening-side end surface of the bottomed cylindrical portion is formed by an opening / closing die, a crack is formed at a corner of the opening / closing die corresponding to the boundary between the outer peripheral surface of the bottomed cylindrical portion and the opening-side end surface. There is also a disadvantage that is easily generated. When casting a piston material having a cylindrical portion with a bottom with the mold device having the above configuration, it is usual that after the molten metal is solidified, the slide core is first pulled out, and then the opening and closing mold is opened. On the other hand, stress concentration occurs at the corners due to the force acting on the opening / closing die when the slide core is pulled out, which causes cracking. Because the cast piston material strongly tightens the slide core, when the slide core is pulled out,
The piston material tries to move with the slide core. Since the movement is blocked by the opening and closing mold, the slide core is detached from the piston material, so that a large force is applied to a portion forming the opening side end face of the opening and closing mold, and stress concentration occurs at the corners. You do it.

[0007] The piston material having the bottomed cylindrical portion can be manufactured by forging, but in such a case, the same problem as in the above casting occurs. When a piston material having a bottomed cylindrical portion is forged by a mold device having an opening / closing die and a side punch, a crack is easily generated at a corner of the opening / closing die. During forging, the deformation resistance of the material acts on the cavity surface of the opening and closing mold to cause stress concentration at the corner of the opening and closing mold, or at the corner of the opening and closing mold when pulling out the side punch for the same reason as during casting. Because.

If the corners of the opening and closing molds for casting and forging are relatively rounded, the stress concentration can be reduced and the occurrence of cracks can be avoided. A rounded portion is formed at the outer peripheral edge of the open end face of the piston material. When the closing member is welded, bonded, friction-welded, or the like to the opening-side end surface as described above, welding, adhesion, friction welding, or the like is not performed on the rounded portion, which causes a reduction in bonding strength. Becomes In order to avoid this, if the end face on the opening side is machined, the number of processing steps increases.

The present invention has been made in view of the above circumstances, and when a hollow piston is manufactured by a molding method such as casting or forging by closing an opening of a bottomed cylindrical portion by a closing member, the present invention provides a method of manufacturing the hollow piston. The object of the present invention is to omit the step of removing at least the burrs on the opening-side end face or to avoid a decrease in joining strength. A method for manufacturing a hollow piston material for a compressor and a mold apparatus for performing the manufacturing method are obtained. As in the case of the claims, each aspect is divided into sections, each section is numbered, and if necessary, the other sections are cited in a form in which the numbers are cited. This is for the purpose of facilitating the understanding of the present invention and should not be construed as limiting the technical features and combinations thereof described in the present specification to those described in the following sections. . Further, when a plurality of items are described in one section, the plurality of items need not always be adopted together. It is also possible to select and adopt only some of the items.

(1) A hollow for a compressor having a bottom wall and a cylindrical portion extending from the outer peripheral portion of the bottom wall, and having an opening at one end closed by a closing member. A method of manufacturing a piston, comprising: an open / close mold that opens and closes in a direction perpendicular to an axis of the bottomed cylindrical member, and forms a cavity that forms an outer surface of the bottomed cylindrical member in a closed state; A bottomed cylindrical member, which is moved in a direction parallel to the axis of the member and moves into the cavity, and which includes a movable member for forming an inner surface of the bottomed cylindrical member and an opening-side end surface; And a fixing step of fixing the bottomed cylindrical member and the closing member in a state where the contact surface of the closing member is in contact with the end surface of the formed bottomed cylindrical member on the opening side. The production of a hollow piston for a compressor characterized by including The method (Claim 1). When the forming process is a casting process, the movable member is a slide core. When the forming process is a forging process, the movable member is a side punch. The slide core is in a state of protruding into the closed opening / closing mold cavity, and the molten metal is injected into the cavity in that state, but the side punch is formed after the forged material is formed by the opening / closing mold, Or it is made to enter into the forging material in parallel with it, and finally enters into the closed openable cavity. In any case, if not only the inner surface of the bottomed cylindrical member but also the opening-side end surface is formed by the movable member, no burr is generated on the opening-side end surface, and the closing member and the closing member are not removed. Even if it abuts,
There is no gap between the two. Therefore, it is possible to omit the removal of burrs from the opening-side end surface. Alternatively, since it is not necessary to round the outer peripheral portion of the opening-side end surface, it is possible to avoid a decrease in bonding strength due to the presence of the round portion. (2) The fixing step is a step of fixing the bottomed cylindrical member and the closing member by bringing the contact surface of the closing member into contact without machining the end surface on the opening side of the bottomed cylindrical member. The method for producing a hollow piston for a compressor according to (1). (3) As the movable member, a member whose outer peripheral edge of a shoulder surface forming the opening side end surface of the bottomed cylindrical member has a larger diameter than an outer peripheral edge of the opening side end surface is used (1). Or the manufacturing method of the hollow piston for compressors of Claim (2) (Claim 2). If the diameter of the outer peripheral edge of the shoulder surface of the movable member is the same as the diameter of the outer peripheral edge of the opening side end surface, the movable member protrudes from the outer peripheral edge of the opening side end surface in a direction parallel to the axis of the bottomed cylindrical member. Burrs occur. This is because the molten metal or the forged material penetrates into the gap between the opening / closing die and the movable member and hardens. Even in this case, if the diameter of the outer peripheral edge of the contact surface of the closing member is slightly smaller than the diameter of the outer peripheral edge of the opening side end surface, the burrs formed along the outer peripheral edge of the opening side end surface are removed. Without closing, the closing member can be brought into close contact with the opening-side end face, and this aspect is also one of the embodiments of the present invention. On the other hand, according to the aspect of the present mode, since the burrs generated along the outer peripheral edge of the opening-side end surface project in a direction parallel to the opening-side end surface, the diameter of the outer peripheral edge of the contact surface of the closing member is reduced. Need not be smaller than the diameter of the outer peripheral edge of the opening-side end face. For example, both diameters can be equal. (4) As the movable member, a member having a rounded portion at a boundary between a shoulder surface forming the opening-side end surface of the bottomed cylindrical member and an outer peripheral surface forming the inner surface of the bottomed cylindrical member is used. The method for producing a hollow piston for a compressor according to the above mode (1) to (3). If a rounded portion is provided at the corner of the movable member, stress concentration can be reduced, and the durability of the movable member can be improved. If the rounded portion is provided, the corner of the inner peripheral edge of the opening-side end face of the bottomed cylindrical member will be rounded. Is small. (5) As the movable member, a member having a projection at the tip for forming a concave portion on the bottom wall is used.
(3) The method for producing a hollow piston for a compressor according to any one of the above (3). According to this aspect, there is an advantage that the degree of freedom of the shape of the inner surface of the bottom wall is increased. (6) The method for manufacturing a hollow piston for a compressor according to the above mode (4), wherein the movable member is provided with the protrusion at an eccentric position. According to this aspect, the degree of freedom of the shape of the inner surface of the bottom wall is further increased as compared with the aspect of the above (4). (7) The bottomed cylindrical member is formed as an integral part of the bottom wall integrally with the reciprocating drive.
The method for producing a hollow piston for a compressor according to any one of the above items (1) to (6). (8) As the closing member, a member having a fitting portion protruding from the contact surface and fitted into the opening of the bottomed cylindrical member is used. (1) Any one of the above items (1) to (7) 5. A method for manufacturing a hollow piston for a compressor according to any one of the above. This has the advantage that the relative positioning of the closing member and the bottomed cylindrical member at the time of joining is facilitated. However, the corner defined by the contact surface of the closing member and the outer peripheral surface of the fitting portion is rounded for the sake of manufacturing (for example, to improve the durability of a mold or a cutting tool). In many cases, the corners of the corners corresponding to the corners of the bottomed cylindrical member interfere with the rounded portions, so that the opening-side end surface of the bottomed cylindrical member and the abutting surface that abuts the same. There may be a gap in the space. Therefore, an annular relief groove is formed in a portion adjacent to one of the contact surface and the outer peripheral surface that defines the corner, or a corner removal portion such as chamfering or rounding is formed in the corner, Alternatively, it is desirable to carry out both. By doing so, even if a rounded portion exists at the boundary between the contact surface at the corner and the outer peripheral surface, the rounded portion does not interfere with the corner of the corner. (9) A method for producing a material for a hollow piston for a compressor having a bottom wall and a cylindrical portion extending from an outer peripheral portion of the bottom wall and having a bottomed cylindrical shape with one end opened. An open / close mold that opens and closes in a direction perpendicular to the axis of the bottomed cylindrical part, forms a cavity that forms the outer surface of the bottomed cylindrical part in a closed state, and moves in a direction parallel to the axis of the bottomed cylindrical part, The material for the hollow piston is molded by a mold device including a movable member for molding the inner surface of the bottomed cylindrical portion and the opening-side end surface in a state of protruding into the cavity. Manufacturing method of hollow piston material. The features described in any one of the above items (2) to (8) can be applied to the method for manufacturing a hollow piston material for a compressor according to this item. (10) A mold device for producing a material for a hollow piston for a compressor having a bottom wall and a cylindrical portion extending from the outer peripheral portion of the bottom wall and having a bottomed cylindrical shape with one end opened. An opening / closing mold that opens and closes in a direction perpendicular to the axis of the bottomed cylindrical portion and forms a cavity for molding the outer surface of the bottomed cylindrical portion in a closed state; and a direction parallel to the axis of the bottomed cylindrical portion. And a movable member for forming the inner surface of the bottomed cylindrical portion and the end surface on the opening side while moving into the cavity. The features described in any one of the above items (2) to (8) can be applied to the mold apparatus of this item.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a swash plate type hollow piston used in a vehicle air conditioner according to an embodiment of the present invention. FIG. 1 shows a swash plate type compressor according to the present embodiment. In FIG. 1, reference numeral 10 denotes a cylinder block, and a plurality of cylinder bores 12 extending in the axial direction are formed on one circumference of the cylinder block 10 around the central axis. Each of the cylinder bores 12 is provided with a single-headed piston 14 (hereinafter abbreviated as piston 14) so as to be able to reciprocate. A front housing 16 is mounted on one axial end surface of the cylinder block 10 (the left end surface in FIG. 1 and referred to as a front end surface), and the other end surface (the right end surface in FIG. 1 and a rear end surface). ), A rear housing 18 is mounted via a valve plate 20. The main body of the swash plate type compressor is constituted by the front housing 16, the rear housing 18, the cylinder block 10, and the like. An intake chamber 22 and a discharge chamber 24 are formed between the rear housing 18 and the valve plate 20, and are connected to a refrigeration circuit (not shown) via an intake port 26 and a supply port 28, respectively. The valve plate 20 is provided with a suction hole 32, a suction valve 34, a discharge hole 36, a discharge valve 38, and the like.

On the central axis of the cylinder block 10,
A rotation shaft 50 is provided rotatably. Rotation axis 50
Are supported by the front housing 16 and the cylinder block 10 via bearings at both ends. A center support hole 56 is formed in the center of the cylinder block 10, and is supported by the center support hole 56. The end of the rotary shaft 50 on the front housing 16 side is connected to a vehicle engine as an external drive source, which is a kind of a drive source (not shown), via a clutch mechanism such as an electromagnetic clutch. Therefore, when the rotating shaft 50 is connected to the vehicle engine by the clutch mechanism during operation of the vehicle engine, the rotating shaft 50 is rotated around its own axis.

A swash plate 60 is attached to the rotating shaft 50 so as to be relatively movable and tiltable in the axial direction. Swash plate 60
, A center hole 61 passing through a center line is formed, and the rotating shaft 50 passes through the center hole 61. The diameter of the center hole 61 is gradually increased toward both ends. On the rotating shaft 50,
In addition, a rotating plate 62 as a rotation transmitting member is fixed, and the front housing 16 is fixed via a thrust bearing 64.
Is engaged. The swash plate 60 is rotated integrally with the rotation shaft 50 by the hinge mechanism 66,
Tilt with axial movement is allowed. Hinge mechanism 66
Is a support arm 67 fixedly provided on the rotating plate 62.
And a guide pin 69 fixedly provided on the swash plate 60 and slidably fitted in a guide hole 68 of the support arm 67.
, The center hole 61 of the swash plate 60, and the outer peripheral surface of the rotating shaft 50. In the present embodiment, the swash plate 60 as a driving member, the rotating shaft 50, the hinge mechanism 66 constituting the rotation transmitting device, and the like constitute a reciprocating drive device for reciprocating the piston 14.

The piston 14 is a kind of a hollow piston, and has an engaging portion 70 to be engaged with the swash plate 60 and a hollow cylindrical member provided integrally with the engaging portion 70 and fitted to the cylinder bore 12. And a head 72 as a hollow head. The swash plate 60 is engaged with a groove 74 formed in the engaging portion 70 via a pair of shoes 76 having a spherical crown shape. The shoe 76 is slidably held by the engaging portion 70 at the spherical portion, abuts against both side surfaces of the swash plate 60 at the flat portion, and slidably sandwiches the outer peripheral portion of the swash plate 60 from both sides. A detailed description of the shape of the piston 14 will be given later.

The rotational movement of the swash plate 60 is converted into a reciprocating linear movement of the piston 14 via the shoe 76. In the suction stroke in which the piston 14 moves from the top dead center to the bottom dead center,
The refrigerant gas in the suction chamber 22 is supplied to the suction hole 32 and the suction valve 34.
Through the cylinder bore 12. Piston 14
In the compression stroke in which the refrigerant moves from the bottom dead center to the top dead center, the refrigerant gas in the cylinder bore 12 is compressed and discharged to the discharge chamber 24 through the discharge hole 36 and the discharge valve 38. An axial compression reaction force acts on the piston 14 as the refrigerant gas is compressed. The compression reaction force is received by the front housing 16 via the piston 14, the swash plate 60, the rotating plate 62, and the thrust bearing 64. Engaging part 7 of piston 14
A rotation restricting section (not shown) is integrally provided at 0. The rotation restricting portion is brought into contact with the inner peripheral surface of the front housing 16, restricts rotation of the piston 14 around the central axis, and avoids collision between the piston 14 and the swash plate 60.

An air supply passage 80 is provided through the cylinder block 10. The discharge chamber 24 and the swash plate chamber 86 formed between the front housing 16 and the cylinder block 10 are connected by the air supply passage 80. In the middle of the air supply passage 80, a capacity control valve 90 is provided. The capacity control valve 90 is an electromagnetic valve, and the solenoid 92 is energized and demagnetized by a control device (not shown) mainly composed of a computer, and the amount of supplied current is controlled in accordance with information such as a cooling load. Is adjusted.

A discharge passage 100 is provided inside the rotary shaft 50. The discharge passage 100 has one end opened to the center support hole 56 and the other end opened to the swash plate chamber 86. The center support hole 56 communicates with the intake chamber 22 via the discharge port 104.

The swash plate type compressor is of a variable displacement type, and the pressure in the swash plate chamber 86 is controlled by utilizing the pressure difference between the discharge chamber 24 as a high pressure source and the suction chamber 22 as a low pressure source. , Cylinder bore 1 acting before and after piston 14
The difference between the pressure of the swash plate chamber 86 and the pressure of the swash plate chamber 86 is adjusted.
The stroke of the piston 14 is changed by changing the inclination angle of 0, and the displacement of the compressor is adjusted. Specifically, the pressure in the swash plate chamber 86 is controlled by controlling the displacement control valve 90 so that the swash plate chamber 86 is communicated with the discharge chamber 24 or cut off. In the demagnetized state of the solenoid 92, the capacity control valve 90 is fully opened and the air supply passage 80 is communicated, and the high-pressure refrigerant gas in the discharge chamber 24 is supplied to the swash plate chamber 86, and the pressure in the swash plate chamber 86 is increased. And the inclination angle of the swash plate 60 is minimized. The piston 14 is reciprocated with the rotation of the swash plate 60. When the inclination angle of the swash plate 60 is minimized, the volume change rate of the piston 14 is reduced, and the discharge capacity of the compressor is minimized. In the excited state of the solenoid 92, the supply amount of the high-pressure refrigerant gas in the discharge chamber 24 to the swash plate chamber 86 increases as the supply current increases and the opening of the displacement control valve 90 decreases (including the opening 0). The refrigerant gas in the swash plate chamber 86 is discharged to the intake chamber 22 through the discharge passage 100 and the discharge port 104, so that the pressure in the swash plate chamber 86 decreases. Along with this, the inclination angle of the swash plate 60 increases, the volume change rate of the piston 14 increases, and the discharge capacity of the compressor increases. When the supply passage 80 is shut off by the excitation of the solenoid 92, the high-pressure refrigerant gas in the discharge chamber 24 is not supplied to the swash plate chamber 86, the inclination angle of the swash plate 60 becomes maximum, and the discharge capacity of the compressor is reduced. Is the largest. The maximum inclination angle of the swash plate 60 is defined by the contact of the stopper 106 provided on the swash plate 60 with the rotating plate 62, and the minimum inclination angle is
0 is defined by the abutment on the stopper 107 on the rotating shaft 50. Air supply passage 80, swash plate chamber 86, capacity control valve 9
0, the discharge passage 100, the discharge port 104, the control device and the like constitute a swash plate inclination angle control device or a discharge displacement control device.

Cylinder block 10 and piston 14
Is made of an aluminum alloy, which is a kind of metal, and the outer peripheral surface of the piston 14 is coated with a fluororesin. By coating with a fluororesin, the fitting gap with the cylinder bore 12 can be reduced as much as possible while avoiding direct contact with the same kind of metal and preventing seizure. It is desirable that the cylinder block 10 and the piston 14 be made of an aluminum-silicon alloy. However, the material of the cylinder block 10 and the piston 14, the material of the coating layer, and the like are not limited to the above-described materials, and may be other materials.

The piston 14 will be described in more detail. As shown in FIG. 2, the end of the engagement portion 70 of the piston 14 remote from the head 72 has a generally U-shape due to the formation of the groove 74, and has a base 108 having a U-shaped bottom and a base 108. And a pair of arm portions 110 and 112 extending from the shaft in a direction orthogonal to the axis of the piston 14. Recesses 114 are respectively formed on side surfaces of the arm portions 110 and 112 facing each other. The inner surfaces of these recesses 114 have a concave spherical shape, and the pair of shoes 76
The swash plate 60 is held in the concave portion 114 while being in contact with the front and back surfaces of the outer periphery of the swash plate 60.

The head 72 of the piston 14 has a bottomed cylindrical portion 1 which is open at one end and closed at the other end.
20 and a cap 12 fixed to the bottomed cylindrical portion 120 and closing the opening of the bottomed cylindrical portion 120 as a closing member.
2 is provided. The bottomed cylindrical portion 120 includes a bottom wall 124.
Is formed integrally with the arm portion 112 side of the engaging portion 70. The bottomed cylindrical portion 120 includes a hollow cylindrical portion 126 extending axially from an outer peripheral portion of the bottom wall 124.
The inner peripheral surface 128 of the bottomed cylindrical portion 120 is a simple cylindrical surface. A concave portion 130 is formed on the inner surface of the bottom wall 124 to reduce the weight.

The cap 122 has a disk-shaped bottom wall 134.
A large-diameter hollow cylindrical portion 136 extending in the axial direction from the outer peripheral portion of the bottom wall 134; and a small-diameter hollow cylindrical portion 140 extending in the axial direction from the inner peripheral portion of the end surface 138 of the large-diameter portion 136. It has a cylindrical shape with a step and a bottom. A concave portion 146 opening to the end surface 144 of the small-diameter portion 140 is formed in the cap 122 by the inner peripheral surface of the small-diameter portion 140 and the large-diameter portion 136 and the inner surface of the bottom wall 134, so that the weight is reduced. As shown in FIG. 2, the corner where the inner peripheral surface of the concave portion 146 intersects with the inner surface of the bottom wall 134 is rounded to have a large-diameter portion 136.
The rigidity at the boundary between the bottom wall and the bottom wall 134 is increased. An annular relief groove 150 is formed in a portion of the small diameter portion 140 adjacent to the end surface 138 of the outer peripheral surface 148. In FIG. 2, for easy understanding, the hollow cylindrical portion 1 is shown.
26, the thickness of the peripheral wall of the large diameter portion 136, the thickness of the bottom wall 134, and the like are exaggerated.

Outer peripheral surface 1 of small diameter portion 140 of cap 122
48 is provided on the inner peripheral surface 128 of the bottomed cylindrical portion 120,
8 is fitted to a depth at which it contacts the opening-side end surface 152 of the bottomed cylindrical portion 120, and the opening-side end surface 152 and the end surface 138 are fitted.
Are welded as welding surfaces, so that the cap 12
2 and the bottomed cylindrical part 120 are joined. The compression reaction force of the refrigerant gas acting on the top surface 154 of the head 72 during the compression stroke of the piston 14 is increased by the end face 138 and the opening end face 15.
2 and received by the weld.

The piston 14 configured as described above is
In the present embodiment, two pieces are manufactured from one piston material. For this reason, as shown in FIG.
The material 160 is abbreviated to the piston body member 162.
(Hereinafter, abbreviated as a main body member 162) and a cap 164 as a closing member. The main body member 162
An engagement portion 166 and a bottomed cylindrical portion 170 having a bottomed cylindrical shape opened in a direction opposite to the engagement portion 166 are provided.
The two main body members 162 are integrally formed adjacent to each other on the engagement portion 166 side so that the bottomed cylindrical portions 170 are concentric with each other.

The bottomed cylindrical portion 170 has a bottom wall 172 and a hollow cylindrical portion 17 extending axially from an outer peripheral portion of the bottom wall 172.
4 and is formed integrally with the engaging portion 166 on the bottom wall 172. An opening-side end surface 176 is formed on the side of the hollow cylindrical portion 174 opposite to the bottom wall 172, and becomes the opening-side end surface 152 when the piston 14 is a product. The inner peripheral surface 178 of the hollow cylindrical portion 174 becomes the inner peripheral surface 128 when the piston 14 is a product, and the concave portion 180 formed on the inner surface of the bottom wall 172 is
Becomes Bridge part 182 provided in each engagement part 166
The base 108 and the arm 11 as shown in FIG.
0, 112 (each of the base 1
84, referred to as arm portions 186, 188) to reinforce the engaging portion 166 against the clamping action during processing, thereby increasing the rigidity of the main body member 162 or distorting due to heat. Is provided as a reinforcing portion for suppressing the pressure. In the present embodiment, the main body member 162 is made of an aluminum alloy, which is a kind of metal, and is manufactured by casting. The casting includes various die castings such as a vacuum method and a PF (pore free die casting) method. The step of casting the main body member 162 will be described later in detail.

The two caps 164 are similarly configured, one of which will be representatively described. As shown in FIG. 3, the cap 164 includes a disc-shaped bottom wall 192, and a hollow cylindrical large-diameter portion 194 that extends in an axial direction from an outer peripheral portion of the bottom wall 192.
And a hollow cylindrical small-diameter portion 198 extending in the axial direction from the inner peripheral portion of the end surface 196 of the large-diameter portion 194 to form a stepped cylindrical shape with a bottom. A concave portion 202 that opens to the end face 200 of the small-diameter portion 198 is formed inside the cap 164 by the inner peripheral surface of the small-diameter portion 198 and the large-diameter portion 194 and the inner surface of the bottom wall 192, so that the weight is reduced. The recess 202 becomes a recess 146 when the piston 14 is a product. The diameter of the outer peripheral surface 204 of the small-diameter portion 198 is smaller than the outer diameter of the large-diameter portion 194 and can be fitted to the inner peripheral surface 178 of the bottomed cylindrical portion 170. End surface 2 on the small diameter portion 198 side of cap 164
At the center of the end face 210 on the opposite side to 00, a holding section 212 having a circular cross section in the example shown in the figure is protruded. In the present embodiment, the cap 164 thus configured is
It is made of an aluminum alloy, which is a kind of metal, and is manufactured by casting, like the main body member 162.

As shown in an enlarged manner in FIG.
An annular relief groove 220 is formed in a portion of the outer peripheral surface 204 adjacent to the end surface 196 of the outer peripheral surface 204. The escape groove 220 is
When the piston 14 is a product, the relief groove 150 is formed. After the cap 164 is manufactured by casting, the clearance groove 220 is formed by cutting with a processing tool (not shown). 7, the thickness of the peripheral wall of the hollow cylindrical portion 174, the thickness of the peripheral wall of the large-diameter portion 194, and the bottom wall 19
2, etc. are exaggerated for ease of understanding.

The main body member 162 is manufactured by a pore-free die casting method in this embodiment. FIG. 4 schematically shows a casting apparatus used in the die casting method. On the base 252 of the casting apparatus 250, a pair of fixed plates 254 and 256 are provided so as to face each other, and four guide rods 25 are provided at four corners of the fixed plates 254 and 256.
8 are fixed at both ends. A movable plate 260 is slidably fitted to the guide rod 258. The fixed platen 254 is provided with a mold opening / closing cylinder 264 that constitutes a mold opening / closing device. The tip of a guide bar 266 connected to the tip of a piston rod of the cylinder 264 is connected to the movable platen 260. The movable plate 260 is moved by the cylinder 264 in a direction approaching to and away from the fixed plate 256 while being guided by the guide rod 258.

On the surfaces of the fixed platen 256 and the movable platen 260 facing each other, a fixed die 268 and a movable die 26
9 are attached, and the pair of molds 268, 2
69 constitutes the opening and closing mold 270. As shown schematically and enlarged in FIG. 5, the fixed mold 268 includes a fixed mold plate 272 and a fixed attachment plate 273,
At 73, it is detachably attached to the fixed board 256. The movable mold 269 also includes a movable mold plate 274 and a movable mounting plate 275, and is detachably attached to the movable plate 260 at the movable mounting plate 275. Movable board 26
A pushing cylinder 276 is attached to the surface opposite to the surface to which the zero movable mold 269 is attached. The piston rod of the pushing cylinder 276 has a pushing member 27.
8 are connected, and the tip of the pushing member 278 is provided through the movable mold 269.

A pair of slide cores 280 and 282 are provided near the opening and closing mold 270 so as to be movable in the axial direction. The slide cores 280 and 282 will be described later. A cavity 286 is formed in the opening / closing mold 270, and a molten metal (in this embodiment, an aluminum alloy) is poured into the cavity 286 to manufacture the main body member 162. The opening and closing mold 270 can be opened and closed at parting surfaces 290 and 292 (shown by two-dot chain lines), which are surfaces of the fixed mold plate 272 and the movable mold plate 274 facing each other. Mold opening / closing cylinder 26
The opening and closing mold 270 is opened and closed by moving the stationary mold 268 toward and away from the stationary mold 268 by driving of the mold 4. Parting surfaces 290 and 292 are set on a plane that includes the center line of bottomed cylindrical portion 170 of main body member 162 and that is parallel to the direction in which the pair of arms 186 and 188 of engaging portion 166 extends. You. Cavity surfaces 294, 296 are provided at positions corresponding to each other on each of the parting surfaces 290, 292.
Are respectively formed, and these cavity surfaces 294, 29
6 defines a cavity 286. In FIG. 5, illustration of the detailed shapes of the cavity surfaces 294 and 296 is omitted.

As shown in FIG. 4, the lower end of the cavity 286 communicates with a sleeve 302 having a pouring port and an oxygen supply port (not shown) through a runner (not shown) extending parallel to the parting surfaces 290 and 292. Have been allowed.
It is desirable that a gate (not shown) having a smaller diameter than other portions is formed near the opening of the runner on the cavity 286 side. The other opening of the runner communicates with the sleeve 302. The sleeve 302 has a cylindrical shape and a fixed mold 268.
From the outside. A plunger tip 312 having a larger diameter than the plunger 310 provided at the tip of the plunger 310 is provided in a portion of the sleeve 302 extending outside.
Are slidably fitted. The plunger 310 is integrally and movably attached to a piston rod of a plunger driving cylinder 316 as an example of a plunger driving device.

The slide cores 280 and 282 are of the open / close type 2
The holding member 320 attached to the fixed-side attachment plate 273 so as to be able to advance and retreat in the direction parallel to the center line of the bottomed cylindrical portion 170 and orthogonal to the opening / closing direction of the molds 268 and 269. Is held. The holding member 320 is provided with a slide core driving cylinder 322 which is an example of a slide core driving device, and a front end portion of a piston rod 324 of the slide core driving cylinder 322 and a rear end portion 340 of the slide cores 280 and 282 are provided. Are linked. By driving the cylinder 322, the slide cores 280, 28
2 is a forward end position (FIG. 5) that projects into the cavity 286.
Are moved to a retracted end position (shown by a solid line in FIG. 5) retracted from the cavity 286. The tip 342 of the slide cores 280, 282
The diameter is smaller than the rear end 340. A shoulder 344 is formed between the rear end 340 and the front end 342. At the boundary between the shoulder surface 344 and the outer peripheral surface 346 of the tip portion 342,
A rounded portion 350 (see FIG. 6) is formed to reduce the concentration of stress on this boundary. In FIG. 6, the roundness of the rounded portion 350 is exaggerated for easy understanding. The tip portion 342 has a shape corresponding to the shape of the internal space of the bottomed cylindrical portion 170, and the outer peripheral surface 346 has a diameter corresponding to the inner peripheral surface 178. Also,
The diameter of the outer peripheral edge of the shoulder surface 344 is larger than the diameter of the outer peripheral edge of the opening-side end surface 176 of the bottomed cylindrical portion 170. A projection 352 having an outer diameter smaller than the diameter of the outer peripheral surface 346 and projecting in the axial direction is formed at the tip of the tip 342. The slide cores 280, 28 at the forward end position
The outer peripheral surface 346 and the shoulder surface 344 of the
A cavity 286 for forming the main body member 162 is formed in cooperation with 94 and 296.

Inside the opening / closing mold 270, one end communicates with the cavity 286 and the other end opens on both side surfaces orthogonal to the parting surfaces 290, 292 of the molds 268, 269 with the opening / closing mold 270 closed. A pair of fitting holes 360, 362
Are formed, and the slide core 280,
282 are movably fitted. Fitting holes 360, 3
The reference numeral 62 is formed by fitting concave portions having a semicircular cross section formed on the fixed-side and movable-side mold plates 272 and 274, respectively. A shoulder surface 368 is formed between the inner peripheral surfaces of the fitting holes 360 and 362 and the cavity surfaces 294 and 296. Shoulder surface 368 and slide cores 280, 28
2 by contact with the shoulder surface 344, the slide core 280,
The forward end position at 282 is defined.

The slide cores 280 and 282 constitute a movable member.
The mold apparatus is constituted by the reference numerals 0, 282, the holding member 320 and the slide core driving cylinder 322. This mold device and the mold opening / closing cylinder 26 of the casting device 250 are used.
4, the plunger driving cylinder 316 and the like are controlled by a control device (not shown).

The pore-free die-casting method using the casting apparatus 250 having the above configuration will be described. With the plunger tip 312 at a position slightly advanced from the pouring port of the sleeve 302, as shown in FIG. 5, the opening and closing mold 270 is closed by the operation of the mold opening and closing cylinder 264, and the mold is closed. Next, as shown in FIG. 6A, the slide cores 280 and 282 are moved to the forward end position where the shoulder surfaces 344 and 368 come into contact with each other, and stand by in preparation for the injection of the molten metal. . Thereafter, oxygen as an active gas is blown from an oxygen supply port formed at a position slightly in front of the plunger tip 312 of the sleeve 302 to fill the cavity 286 with oxygen. Cavity 2
The air in 86 is replaced by oxygen. Next, the plunger tip 312 is retracted to the retracted end position while the supply of oxygen is continued, and the molten metal is supplied into the sleeve 302 from the pouring port. Thereafter, the plunger tip 312 is advanced toward the opening / closing die 270, and the level of the molten metal in the sleeve 302 is raised. Eventually, the molten metal will enter the runner,
From this point, the forward speed of the plunger tip 312 is increased, and the molten metal is ejected at a stretch into the cavity 286 through the narrow gate. Thereby, the cavity 286
Aluminum and oxygen are satisfactorily reacted in the inside, and the oxygen in the cavity 286 disappears to be in a vacuum state, so that entrainment of air (mainly nitrogen) into the molten metal is well avoided. In addition, the molten metal is favorably supplied to the gap between the cavity surfaces 294 and 296 and the slide cores 280 and 282, and the main body member 1 including the thin bottomed cylindrical portion 170 is provided.
62 is molded. The inner peripheral surface 178 of the bottomed cylindrical portion 170 is formed by the outer peripheral surface 346 of the distal end portion 342 of the slide cores 280 and 282, and a portion of the shoulder surface 344 on the inner peripheral side from the contact portion with the shoulder surface 368. Open end face 1
76 is molded. In addition, the projection 352 forms a concave portion 180 that forms the bottom surface of the bottomed cylindrical portion 170. The corner of the inner peripheral edge of the opening-side end surface 176 of the bottomed cylindrical portion 170 is slightly rounded by the rounded portion 350 provided at the boundary between the shoulder surface 344 of the slide cores 280 and 282 and the outer peripheral surface 346.

The molten metal is sprayed into the cavity 286 in a mist through a narrow gate, so that the molten metal is rapidly cooled after reacting with oxygen. Therefore, a relatively thick chill layer is formed on the solidified main body member 162. According to the pore-free method, the thickness of the chill layer formed by the conventional casting method is about 20 μm,
A chill layer having a thickness of 0 μm is formed. The chill layer is primary α
This is a layer in which the change in the crystallization ratio of (α phase) and eutectic silicon is discontinuous, and has high hardness and strength. Therefore, the peripheral wall of the bottomed cylindrical portion 170 can be manufactured to be thin while satisfying the required strength.

After the molten metal is supplied to the cavity 286,
If the set time elapses and the main body member 162 is formed, after the slide cores 280 and 282 are detached from the bottomed cylindrical portion 170, the opening / closing die 270 is opened and the extrusion cylinder 276 is operated. The main body member 162 held by the movable mold 269 is extruded by the pushing member 278.

A cap 164 separately manufactured by casting is fixed to the main body member 162 formed through the above-described casting process. Hereinafter, a process of fixing the cap 164 to the main body member 162 will be described. As shown in FIG. 7, the small-diameter portion 198 side of the cap 164 is set to the distal end side and is positioned coaxially with the bottomed cylindrical portion 170, inserted into the opening of the bottomed cylindrical portion 170, and has an outer peripheral surface of the small-diameter portion 198. 204 is fitted with the inner peripheral surface 178. The fitting proceeds further in a state where the cap 164 is positioned in the radial direction in the bottomed cylindrical portion 170 by the fitting between the inner peripheral surface 178 and the outer peripheral surface 204, and the end surface 196 of the cap 164 and the hollow cylindrical portion 174 are formed. The cap 16 is brought into contact with the opening-side end face 176 by contact.
4 is defined. In this state, a welding beam such as an electron beam is irradiated, and the end faces 176 and 196 are respectively welded as welding surfaces. In the present embodiment, the main body member 162 and the cap 164 are die-cast, and have high dimensional accuracy. The opening-side end surface 176 of the bottomed cylindrical portion 170 is the shoulder surface 3 of the slide cores 280, 282.
Since it is formed by 44, burrs do not occur on the opening side end surface 176. Accordingly, the inner peripheral surface 178 and the opening-side end surface 176 of the bottomed cylindrical portion 170 and the cap 16
The small-diameter portion 198 is fitted to the inner peripheral surface 178 of the bottomed cylindrical portion 170 without performing machining such as cutting or grinding on the end surface 196 and the outer peripheral surface 204 of the small-diameter portion 198.
Can be brought into close contact with the opening-side end surface 176, and the manufacturing cost can be reduced.

After the two caps 164 are fixed to the main body member 162 in this manner, the portion that forms the head 72, that is, the bottomed cylindrical portion 1 of the main body member 162
A plurality of portions including the outer peripheral surface of the cap 70 and the cap 164 are cut. At this time, two caps 1
The center holes 38 are provided in the holding portions 212 provided in
0 (shown by a two-dot chain line in FIG. 3), the centers are fitted into the center holes 380, the centering is performed, and the rotation is performed while the two holding portions 212 are gripped by the chucks. The rotation of the driving device is transmitted to the cap 164 and the main body member 162, and the processing is performed favorably.

Next, the bottomed cylindrical portion 17 of the main body member 162
Coating is performed on the part including the outer peripheral surface of 0, for example,
A coating layer of polytetrafluoroethylene is formed. Then, after the holding portion 212 of the cap 164 is removed and the end surface 210 is cut, centerless grinding is performed on the outer peripheral surface of the bottomed cylindrical portion 170 on which the coating layer is formed, and the head 72 is completed. I do. continue,
Each of the engaging portions 166 is machined, the bridge portion 182 is removed, and the concave portion 114 (shown by a two-dot chain line in FIG. 3) that holds the shoe 76 when the piston 14 is formed is processed. The joint 70 is completed. Then, the material 160 is cut into two, and two pistons 14 are obtained.

As is apparent from the above description, the piston body member 162 integrally including the bottomed cylindrical portion 170 and the engaging portion 166 constitutes a bottomed cylindrical member, and the hollow cylindrical portion 1
74 constitutes a cylindrical part. The large-diameter portion 194 of the cap 164 as a closing member constitutes a hollow cylindrical portion, the small-diameter portion 198 constitutes a fitting portion, and the end surface 196 constitutes a contact surface.

According to the present embodiment, the bottomed cylindrical portion 170
Is formed by the shoulder surfaces 344 of the slide cores 280 and 282, so that burrs can be prevented from being generated on the open end surface 176. Even if burrs occur, the end surface 196 of the cap 164 can be extended from the outer peripheral edge of the opening-side end surface 176 of the bottomed cylindrical portion 170 in parallel with the opening-side end surface 176 without machining the opening-side end surface 176. Can be in close contact with
As described above, it is possible to prevent the formation of the dents and holes on the outer surface of the welded portion to prevent the joining strength from being insufficient, to secure the required strength of the welded portion, and to improve the durability of the piston 14. In addition, from the outer peripheral edge of the opening side end surface 176 to the opening side end surface 1
After the cap 164 is fixed, the burrs extending parallel to 76 can be removed when the outer peripheral surfaces of the cap 164 and the bottomed cylindrical portion 170 are machined.

Further, since the rounded portion 350 is provided at the boundary between the shoulder surface 344 and the outer peripheral surface 346 of the slide cores 280, 282, stress concentration occurring when the slide cores 280, 282 are detached is reduced, and the slide cores 280, 282 are alleviated. 2
82 has improved durability. The inner peripheral edge of the opening-side end surface 176 of the bottomed cylindrical portion 170 is slightly rounded. However, as compared with the case where the outer peripheral portion is rounded as described above, the adverse effect on the joining strength is small. As a result, the durability of the piston 14 is improved.

Further, the corner of the opening-side end of the bottomed cylindrical portion 170 and the end face 1 of the cap 164 are formed by the escape groove 220.
Interference with the boundary between the outer peripheral surface 204 and the outer peripheral surface 204 can be avoided, the end surfaces 176 and 196 can be completely adhered to each other, and welding can be performed using the end surfaces 176 and 196 as welding surfaces. This also makes piston 1
4 is improved in durability. However, the roundness of the inner peripheral side of the opening side end of the bottomed cylindrical portion 170 is made sufficiently large, and the opening side end, the end surface 196 of the cap 164 and the outer peripheral surface 20 are formed.
The escape groove 220 may be omitted when avoiding interference with the rounded portion of the boundary with the groove 4. In this case, the rounding of the opening side end is an example of the corner removing part, and the end face 176 and the end face 196 are joined in a state where they are completely adhered to each other, so that the required strength of the joint is satisfied. It is.

It is desirable that the inner surfaces of the end faces 176 and 196 be welded to the inner periphery. The corner of the cap 164 serves as a stress concentration generating part when the bottom wall 134 elastically deforms into a three-dimensional shape based on the pressure and inertia force of the refrigerant gas acting on the bottom wall 134 of the piston 14 during the compression stroke and the suction stroke. Although it is slightly away from the surface, it is not completely unaffected by the stress concentration. If the inner surface of the end faces 176 and 196 is not welded, the unwelded portion has an effect similar to a crack. None, the weld is likely to be damaged, but sufficient welding strength can be obtained if it is welded to the inner peripheral edges of the end faces 176 and 196. This is because not only the welding area is increased, but also an action similar to the crack is prevented.

Various shapes can be employed for the bottomed cylindrical member and the closing member, and one embodiment is shown in FIG. In FIG. 8, only portions different from the embodiment shown in FIGS. 1 to 7 are shown, and components that function in the same manner as in the above embodiment are given the same reference numerals, and description thereof will be omitted. FIG.
As shown in (b), the inner peripheral surface of the hollow cylindrical portion 402 of the bottomed cylindrical portion 400 constituting the bottomed cylindrical member in the present embodiment forms a stepped cylindrical surface having a large diameter on the opening side, Inner peripheral surface 412 of large diameter hole 410 and inner peripheral surface 4 of small diameter hole 414
16 and a shoulder surface 418 is formed.

The bottomed cylindrical portion 400 thus configured
As shown in FIG. 8A, a slide core 430 used for casting a piston manufacturing material having
2 and a front end 434 smaller in diameter than the rear end 432. A shoulder 436 is provided between the rear end 432 and the front end 434.
Are formed. The distal end portion 434 has a large-diameter portion 440 and a small-diameter portion 442, and the distal end side is a small-diameter portion 442, and a shoulder surface 444 is formed between the large-diameter portion 440 and the small-diameter portion 442. Shoulder surface 436 and outer peripheral surface 446 of large diameter portion 440
Is provided with a rounded portion 450 at the boundary with the shoulder surface 44.
A rounded portion 452 is formed at a corner where 4 and the outer peripheral surface 446 intersect.
A rounded portion 454 is provided at the boundary between the shoulder surface 444 and the outer peripheral surface 453 of the small-diameter portion 442 to reduce stress concentration.

In the casting process of the piston material including the bottomed cylindrical portion 400, after the opening and closing mold 270 is closed, FIG.
As shown in (a), the slide core 430 is moved to the forward end position and protrudes into the cavity 286 of the opening and closing mold 270. Then, the molten metal is injected in the same manner as in the above embodiment to form the piston material. The inner peripheral surface 416 and the bottom surface of the bottomed cylindrical portion 400 are formed by the small diameter portion 442 of the slide core 430, and the inner peripheral surface 412 is formed by the outer peripheral surface 446 of the large diameter portion 440. Further, the opening side end surface 460 is a shoulder surface 368 of the shoulder surface 436.
The shoulder surface 418 is formed by the shoulder surface 444 by a portion on the inner peripheral side of the contact portion with the contact member. Bottomed cylindrical part 400
The rounded portion 450 of the slide core 430 rounds the inner corner of the opening-side end surface 460, and the rounded portion 454.
As a result, the corners on the inner peripheral side of the shoulder surface 418 are rounded, and the corners adjacent to the shoulder surface 418 and the inner peripheral surface 412 are rounded by the rounded portion 452.

As shown in FIG. 8B, a cap 470 as a closing member for closing the opening of the bottomed cylindrical portion 400 extends in the axial direction from the bottom wall 472 and the outer peripheral portion of the bottom wall 472. A hollow cylindrical portion 473 and a fitting portion 476 extending in an axial direction from an inner peripheral portion of an end surface 474 of the hollow cylindrical portion 473 are provided. The outer peripheral surface 480 of the fitting portion 476 has a large-diameter hole portion 410.
The end surface 474 abuts the opening side end surface 460 on the inner peripheral surface 412 and the tip end surface 482 of the fitting portion 476 has a shoulder surface 418.
Is fitted to the depth of contact with In order to avoid interference between the rounded portion of the shoulder surface 418 and the corner of the fitting portion 476, the fitting portion 47
6 is chamfered 490 at the corner where the tip surface 482 and the outer peripheral surface 480 intersect with each other, the inner peripheral corner of the opening-side end of the bottomed cylindrical portion 400, the end surface 474 of the cap 470, and the outer peripheral surface 480. In order to avoid interference with the corner defined by the above, it is desirable that an annular relief groove 492 is provided in a portion of the outer peripheral surface 480 adjacent to the end surface 474. By doing so, the distal end surface 482 and the shoulder surface 418 and the end surface 47
4,460 can be reliably brought into close contact with each other. In the present embodiment, the end surface 474, the opening-side end surface 460, and the outer peripheral surface 48
0 and the inner peripheral surface 412, and the end surface 482 and the shoulder surface 418 are adhered by an adhesive, and the bottomed cylindrical portion 400 and the cap 470 are joined. Note that, as described in the above-described embodiment, the roundness formed at the corner of the inner peripheral portion of the opening-side end surface 460 of the bottomed cylindrical portion 400 is sufficiently increased, and the opening-side end of the bottomed cylindrical portion 400 and The escape groove 492 may be omitted as long as interference with the round portion provided at the corner of the cap 470 is avoided.

The slide core can have any shape other than the above embodiments as long as the slide core can be separated from the molded cylindrical member with a bottom. Weight can be reduced. One embodiment is shown in FIG.
Shown in Note that FIG. 9 shows only parts different from the embodiment shown in FIGS. 1 to 7, and components that function in the same manner as in the above-described embodiment are given the same reference numerals and description thereof is omitted.
The distal end of the slide core 500 of the mold apparatus has a protrusion 50 at an asymmetric position with respect to its own axis, corresponding to the shape of the internal space of the bottomed cylindrical portion 502 constituting the bottomed cylindrical member.
Eight. The slide core 500 has a rear end 510.
And a front end 512 having a smaller diameter than the rear end 510, and a shoulder surface 514 is formed between the rear end 510 and the front end 512. The protruding portion 508 is provided so as to protrude in a direction parallel to the axis at a position eccentric to the base portion 184 side of the engaging portion 166 with respect to the axis on the front end surface 516 of the front end portion 512.

The slide core 500 configured as described above
According to the embodiment, the effects described in the above embodiment can be obtained, and the bottom surface 521 of the bottom wall 520 of the bottomed cylindrical portion 502 can be formed by forming the slide core 500 in a non-axisymmetric shape.
A concave portion 522 further concaved toward the arm portion 188 is formed, and a concave portion for reducing the weight can be provided in a portion that is difficult to process with a processing tool, and the weight of the piston can be easily reduced.

In the embodiment shown in FIGS. 1 to 7 and the embodiment shown in FIG. 8, the inner peripheral surfaces 178, 412 of the bottomed cylindrical portions 170, 400 and the outer peripheral surfaces 204, 480 of the caps 164, 470 Although the gap has been fitted, the fitting may be tight.

The method of fixing the bottomed cylindrical member and the closing member is not limited to the above-described beam welding or bonding, and various methods can be adopted. For example, friction welding or press fitting, the bottomed cylindrical member and the closing member can be used. Low melting point alloy with lower melting point, such as joining with solder, brazing material, etc., fixation by caulking,
It may be fixed by screws. Moreover, you may join by plastic flow. Alternatively, it may be fixed by any combination of these fixing methods.

It is desirable, but not indispensable, to form a concave portion inside the closing member as in each of the above embodiments from the viewpoint of weight reduction.

The bottomed cylindrical member may be formed by forging. One embodiment is shown in FIG. In the present embodiment, a bottomed cylindrical member having the same shape as the bottomed cylindrical member shown in FIG. 9 is formed by forging. Therefore, portions having the same shape as the embodiment shown in FIG. 9 are denoted by the same reference numerals, and description thereof is omitted. The die apparatus used for carrying out the forging method includes an opening / closing die 590 having a fixed die 586 and a movable die 588, and an axis of the bottomed cylindrical portion 500 orthogonal to the opening / closing direction of the opening / closing die 590. A pair of side punches 600 (FIG. 10)
(Only one of them is shown).

The side punch 600 has a cylindrical portion 602.
And a protrusion 610 having a non-circular cross section provided at a position eccentric in the axial direction of the distal end surface 604 of the columnar portion 602. The cylindrical portion 602 has a stepped cylindrical shape with a distal end 620 having a smaller diameter than the proximal end 622, and the distal end 620 and the proximal end 62.
2, a shoulder surface 628 extending radially outward from the outer peripheral surface 626 of the distal end portion 620 is formed. Shoulder surface 6
The diameter of the outer peripheral edge of 28 is larger than the diameter of the outer peripheral edge of the opening-side end surface 176 of the bottomed cylindrical portion 500. Shoulder surface 6
It is desirable that a rounded portion (not shown) is formed at a boundary between the outer peripheral surface 626 and the outer peripheral surface 626 of the distal end portion 620 so as to reduce stress concentration on the boundary. Both sides (FIG. 10) orthogonal to the parting surfaces (not shown) of the molds 586 and 588
, The advancing end position of the side punch 600 (the forming end position of the bottomed cylindrical portion 500) is defined by the abutment of one side surface 636, 638 (shown only) with the shoulder surface 628 of the side punch 600. The side punch 600 forms a movable member.

With the forging material positioned and supported on the mold surface of the fixed mold 586, the movable mold 588 is moved to the fixed mold 58.
6 and brought into contact with both parting surfaces, the engaging portions 166 are formed by the mold surfaces formed on the molds 588, 586. In a state where the intermediate product in which the engaging portion 166 is formed is restrained by the molds 586 and 588, the side punch 600 enters and the bottomed cylindrical portion 50 is inserted.
0 is molded. The outer peripheral surface 626 of the distal end portion 620 of the side punch 600 and the distal end surface 604 form the bottomed cylindrical portion 170.
The inner peripheral surface 176 and the bottom surface 521 are formed,
The concave portion 5 recessed from the bottom surface 521 of the bottom wall 520 of the bottomed cylindrical portion 170 toward the arm portion 188 by the protrusion 610.
22 is molded. Also, the shoulder surface 628 has side surfaces 636, 6
Excess material flows out of the gap between them before coming into contact with the outer surface 38, and then the opening-side end surface 176 is formed by a portion of the shoulder surface 628 on the inner peripheral side from the contact portion with the side surfaces 636 and 638. .

FIG. 10 shows the shoulder surface 628 and the side surface 63.
6,638 are in direct contact with each other, but in practice, a thin flash is often sandwiched between the two. Also, side surfaces 636, 63 of the molds 586, 588
8 and the contact surface 628 of the side punch 600,
Instead of defining the forward end position of the side punch 600,
The advance of the side punch 600 is prevented by a special stopper, and the side surfaces 636 and 638 and the shoulder surface 6 of the side punch 600 are prevented.
It is also possible to make a small gap remain between the two, and in that case, a burr having a thickness corresponding to the gap is generated between the two. More specifically, in parallel with the formation of the engaging portion 166 by the molds 586 and 588,
The side punch 600 may be inserted into the forged material.

The closing member may be manufactured by forging, or if it has a simple shape such as a disk, it may be manufactured by machining a commercially available bar or other general-purpose material.

At least one of the bottomed cylindrical member and the closing member may be formed of a metal material other than an aluminum alloy, for example, a magnesium alloy. In the case where the bottomed cylindrical member and the closing member are joined by bonding and caulking, the closing member may be formed of a resin suitable for the joining method.

The single-headed piston manufacturing material 160 is a double material in which the engaging portions are connected to each other, but may be a double material in which the heads are connected to each other. . Further, the material for manufacturing the piston may be a material for one piston having one piston main body member and one closing member.

In each of the above embodiments, the case where the bottomed cylindrical member constituting the main part of the head and the engaging portion are integrally formed has been described. Are integrally formed, and can be applied to the case where the opening of the bottomed cylindrical member having the bottom wall and the hollow cylindrical portion is closed by the closing member. Further, the present invention can also be applied to a case where the hollow piston is divided at a central portion in the axial direction of the head and has a side provided with the engaging portion and a side not provided with the engaging portion.

The parting surfaces of the pair of molds of the mold apparatus are arranged on a plane that includes the center line of the bottomed cylindrical portion and is parallel to a direction perpendicular to the direction in which the pair of arms 186 and 188 extend. Can also be set to In this case, the parting surface of the engaging portion 166 has a width (the arm portion 186, 1).
(The direction orthogonal to the direction in which the extension 88 extends).

The structure of the swash plate type compressor is not limited to the above-described embodiment, but may be another structure. For example, the capacity control valve 90 is not indispensable, and an opening / closing valve that is mechanically opened / closed based on a pressure difference between the pressure of the discharge chamber 24 and the pressure of the swash plate chamber 86 may be provided. Further, instead of or together with the capacity control valve 90,
An electromagnetic control valve similar to the displacement control valve 90 may be provided in the middle of the discharge passage 100, or may be opened and closed mechanically based on the pressure difference between the pressure in the swash plate chamber 86 and the pressure in the intake chamber 22. A valve may be provided.

The present invention can be applied not only to a fixed displacement type swash plate type compressor but also to a hollow piston for a compressor other than a swash plate type compressor.

Although some embodiments of the present invention have been described in detail above, these are merely examples, and the present invention is not limited to the above-mentioned [Problems to be Solved by the Invention, Means for Solving Problems and Effects]. The present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art, including the described embodiment.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a swash plate type compressor including a hollow piston manufactured by a method for manufacturing a hollow piston for a compressor according to an embodiment of the present invention.

FIG. 2 is a front sectional view showing the hollow piston.

FIG. 3 is a front view (partial cross section) showing a piston body member and a closing member which constitute a piston manufacturing material for manufacturing the hollow piston.

FIG. 4 is a front view showing a casting device used for manufacturing the hollow piston.

FIG. 5 is an enlarged front sectional view showing a part of a mold device attached to the casting device.

FIG. 6 is a view for explaining a casting step of the method of manufacturing the hollow piston.

FIG. 7 is a view for explaining a fixing step of the method of manufacturing the hollow piston.

FIG. 8 is a view for explaining a method of manufacturing a hollow piston for a compressor according to another embodiment of the present invention.

FIG. 9 is a view for explaining a method of manufacturing a hollow piston for a compressor according to still another embodiment of the present invention.

FIG. 10 is a view for explaining a method of manufacturing a hollow piston for a compressor according to still another embodiment of the present invention.

[Explanation of symbols]

14: single-headed piston 70, 166: engagement part 7
2: Head 120, 170: Bottomed cylindrical part 12
2,164: cap 124,172: bottom wall 12
6,174: hollow cylindrical part 128,178: inner peripheral surface
130, 204: outer peripheral surface 134, 192: bottom wall
136, 194: Large diameter part 138, 196: End face
139, 198: small diameter portion 146, 180: concave portion
152, 176: Open end face 162: Piston main body member 250: Casting device 264: Cylinder for opening and closing mold 268: Fixed mold 269: Movable mold
270: Open / close type 280, 282: Slide core
286: cavity 320: holding member 322:
Slide core drive cylinder 344: shoulder surface 34
6: Outer peripheral surface 350: Round portion 352: Projection 4
00, 502: bottomed cylindrical part 402: hollow cylindrical part
412, 416: inner peripheral surface 418: shoulder surface 430, 500: slide core 436, 444, 5
14: shoulder surface 446: outer peripheral surface 450, 452, 4
54: rounded portion 460: open side end surface 470: cap 472: bottom wall 473: hollow cylindrical portion 47
4: end surface 476: fitting portion 480: outer peripheral surface 4
82: Tip surface 518: Projection 520: Bottom wall 5
22: recess 586: fixed mold 588: movable mold 590: open / close mold 600: side punch 61
0: protrusion

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Masato Takamatsu 2-1-1 Toyota-cho, Kariya-shi, Aichi Prefecture Inside Toyota Industries Corporation (72) Inventor Shigeo Fukushima 2-1-1 Toyota-cho, Kariya-shi, Aichi Prefecture Shares Inside Toyota Industries Corporation (72) Inventor Takahiro Hoshida 2-1-1 Toyota-cho, Kariya-shi, Aichi Prefecture Inside Toyota Industries Corporation (72) Inventor Fumio Enoshima 2-1-1 Toyota-machi, Kariya-shi, Aichi Prefecture F term in Toyota Industries Corporation (reference) 3H003 AA03 AC03 AD02 CB00 3H076 AA06 BB26 BB41 BB50 CC31

Claims (3)

[Claims] A hollow piston for a compressor having a bottom wall and a cylindrical portion extending from an outer peripheral portion of the bottom wall, and closing an opening of a bottomed cylindrical member having one end opened by a closing member. An open / close mold that opens and closes in a direction perpendicular to an axis of the bottomed cylindrical member, and forms a cavity for molding an outer surface of the bottomed cylindrical member in a closed state, and a bottomed cylindrical member. Moving in a direction parallel to the axis of, and in a state of protruding into the cavity, by using a mold device including a movable member that forms the inner surface of the bottomed cylindrical member and an end surface on the opening side, the bottomed cylindrical member is removed. A forming step of forming, and a fixing step of fixing the bottomed cylindrical member and the closing member in a state where the contact surface of the closing member is in contact with the opening-side end surface of the formed bottomed cylindrical member. Method for producing hollow piston for compressor characterized by containing . 2. The fixing step of fixing the bottomed cylindrical member and the closing member by bringing the contact surface of the closing member into contact without machining the open side end surface of the bottomed cylindrical member. The method of manufacturing a hollow piston for a compressor according to claim 1, wherein 3. A diameter of an outer peripheral edge of a shoulder surface forming the opening-side end surface of the bottomed cylindrical member as the movable member,
3. The method for manufacturing a hollow piston for a compressor according to claim 1, wherein a diameter larger than a diameter of an outer peripheral edge of the opening side end surface is used.