JP2003193969A - Manufacturing method for piston for swash plate compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a piston with a sufficient strength in an inner surface of a depth in an engaging part at a lower cost. <P>SOLUTION: A piston material 160 for manufacturing the piston 14 for a swash plate compressor is produced via die cast step S10 and fixing step S12. In an intermediate product 230 after an outer peripheral surface processing step S14, an inner surface cutting step S16, and a plastic deformation applying step S18, at a fine shot peening step S20, an inner surface of the engaging part including the inner surface of the depth is smoothed by projecting fine shots with a average particle diameter of 500 μm or less at a rate of 50 m/sec or more to the inner surface of the depth in the engaging part to cause compression residual stress, thereby improving fatigue strength in the engaging part 70 of the piston 14 as an end product. Heat treatment such as T6 treatment for the piston material 16 can be omitted. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston for a swash plate compressor, and more particularly to a method for manufacturing a piston made of an aluminum alloy.

[0002]

2. Description of the Related Art One type of swash plate type compressor includes a rotary shaft, a housing, a swash plate, a plurality of pistons, and a shoe device. The housing holds the rotating shaft so as to be rotatable about the axis of the rotating shaft, and has a plurality of cylinder bores formed in parallel with the axis of the rotating shaft around the axis of the rotating shaft. . Also, the swash plate is
It is supposed to rotate with the rotation axis in a state of being inclined with respect to a plane perpendicular to the axis of the rotation axis (the angle between the plane and the swash plate is called the swash plate inclination angle), and the outer circumference of the swash plate. A shoe device is disposed between the portion and the plurality of pistons. The shoe device includes a pair of a spherical body and a plate-shaped shoe, respectively, between the outer peripheral portions of both side surfaces of the swash plate and the engaging portion of the piston, or a spherical crown that forms a part of a sphere. One spherical crown shoe having a shape may be provided. The plate-shaped shoe has a concave spherical surface portion that accommodates a part of the spherical body,
It is generally flat and has a flat portion that slides on a swash plate. The swash plate type compressor includes a variable displacement type in which the inclination angle of the swash plate is changed to change the discharge capacity, and a fixed displacement type in which the inclination angle does not change.

In any case, the piston includes a piston head slidably fitted in the cylinder bore and an engaging portion engaging with the swash plate via a shoe device.
The engaging portion includes a base portion extending substantially parallel to the axis of the piston head, and a pair of arm portions extending from both ends of the base portion in a direction substantially orthogonal to the axis, and accommodates the outer peripheral portion of the swash plate. The engaging recess is formed. In a variable displacement swash plate compressor, the head is usually provided only on one side of the engaging portion, and in a fixed displacement swash plate compressor, the head is provided on both sides of the engaging portion. It is often done. In any case, a concave spherical surface portion that slides on the convex spherical surface portion of the spherical crown shoe or the spherical body is formed on the inner side surfaces of the pair of arm portions of the engaging portion that face each other.

The base portion of the engaging portion connects the pair of arm portions through a gap between the outer peripheral surface of the swash plate and the inner peripheral surface of the housing. This gap is a small size of the entire compressor. In order to improve performance while improving performance, it is desirable that the size be made as small as possible. Therefore, it is desirable to make the radial dimension of the base portion as small as possible, and this is one of the locations where it is difficult to secure the strength among the piston portions. In particular, among the inner side surfaces of the engaging recesses of the engaging portion, tensile stress is likely to concentrate on the inner side surface of the inner part formed by the base and the boundary between the base and the pair of arms, and strength is ensured. Especially difficult.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to manufacture a piston having sufficient strength on the inner surface of the inner part at the lowest possible cost. According to the present invention, the method for manufacturing a piston for a swash plate compressor according to each of the following aspects can be obtained. Similar to the claims, each mode is divided into paragraphs, each paragraph is numbered, and the numbers of other paragraphs are referred to as necessary. This is merely for facilitating the understanding of the present invention, and the technical features and combinations thereof described in the present specification should not be construed as being limited to those described in the following respective sections. . Moreover, when a plurality of items are described in one section, it is not always necessary to adopt the plurality of items together. It is also possible to select and use only some of the items.

In the following items, (1) corresponds to claim 1, (2) to claim 2, and (3) to claim 3.
And the combination of (4) and (5) is in claim 4,
Claim (8) is in claim 5, claim (9) is in claim 6, and claim (10) to
A combination of (12) corresponds to claim 7.

(1) A piston head that is slidably fitted in the cylinder bore, and an engaging portion that engages with the swash plate via a shoe device, the engaging portion of the piston head A slant that includes a base portion that extends substantially parallel to the axis and a pair of arm portions that extend from both ends of the base portion in a direction substantially orthogonal to the axis and that forms an engagement recess that accommodates the outer peripheral portion of the swash plate. A method for manufacturing a piston for a plate compressor, at least a die casting step of casting a piston material made of an aluminum alloy by a die casting method, and an intermediate product between the piston material and a finished product, wherein A fine shot having an average particle size of 500 μm or less is 50 m on the inner surface of the inner part of the recessed portion formed at least by the base and the boundary between the base and the pair of arms. Method of manufacturing a piston for a swash plate type compressor which comprises a fine shot peening step of projecting at sec or faster. If a fine shot is made to collide with at least the inner surface of the inner part of the engaging recess of the intermediate product at a high speed, the inner surface of the inner part is hit and the surface is smoothed, and compressive residual stress occurs and the strength of the engaging part is increased. Increase.
During operation of the swash plate compressor, tensile stress is generated on the inner surface of the inner part of the engaging portion, and particularly stress concentration occurs at the boundary between the base and the pair of arms, and a large tensile stress acts. If the surface of that part is smooth, it is possible to avoid the growth of cracks from the minute notches, and because the tensile stress is reduced by the amount of compressive residual stress, the strength of the engaging part (particularly fatigue strength) It will increase. Further, if the projection speed of the fine shot is increased, the temperature of the inner surface of the inner part of the inner part rises, and the surface part is once melted and changed into a rapidly cooled structure, which is close to the effect of T6 treatment, T7 treatment, etc. , Called a heat treatment-like effect), which also increases the strength of the engaging portion. As the fine shot, it is desirable to use a hard shot having a hardness equal to or higher than that of the piston material. As the hard shot, a steel shot such as stainless steel, a ceramic shot such as carborundum, and glass beads are suitable. However, it has been confirmed by experiments that the effect of increasing the strength of the engaging portion can be obtained even if a lubricating shot made of at least one material such as molybdenum disulfide, PTFE, or graphite is used. It is also possible to use a mixture of the hard shot and the lubricity shot as a fine shot. The larger the projection speed of the fine shot, the greater the treatment effect, and the larger the average particle size, the treatment effect reaches the inside of the engaging portion, but the surface roughness of the surface increases, and
Processing uniformity is reduced. Further, if the particle size of the fine shot is made small, the gas is jetted at a high speed, and by mixing the fine shot in the gas flow, it becomes easy to increase the projection speed (spray speed), and The increase can be increased to obtain a heat treatment-like effect. Therefore, the average particle size of the fine shots should be determined in consideration of the above, but generally, the average particle size of the fine shots is preferably 200 μm or less and 120 μm or less, and 80 μm or less. Is more desirable. The projection speed of the fine shot is 80 m / sec.
It is desirable to set it as above, and it is more desirable to set it to 100 m / sec or more. (2) The method for manufacturing a piston for a swash plate compressor according to the item (1), wherein the die casting step is a step of casting the piston material by a pore-free method. If a piston material made of aluminum alloy is cast by the pore-free method, it is possible to obtain a material with excellent strength, with few fine bubbles and voids. In particular,
A better piston material can be obtained by squeezing the pressurizing member into the cavity of the mold at the final stage of solidification of the molten metal. Moreover, if fine shot peening is performed according to the present invention, the strength of the engaging portion is further increased, and a lightweight and high strength piston can be obtained. (3) Including an inner surface cutting step of cutting the inner surface including the inner surface of the inner portion of the piston material, the fine shot peening step is performed after the inner surface cutting step (1) or ( The method for manufacturing a piston for a swash plate compressor according to the item 2). Since the piston material cast by the die casting method has a chill layer with high strength and hardness formed on the surface, it is better not to cut the inner surface of the inner part of the engagement part of the piston material. In order to remove the portion and flash, or to secure the dimensional accuracy, it is usually necessary to perform a cutting process. Then, when the cutting process is performed, the chill layer is removed, and the cut lines function as a kind of notch, and the strength of the engaging portion is reduced. On the other hand, if shot peening is applied to the inner surface of the inner part according to the present invention, a cutting residue disappears and a compressive residual stress is generated, and, depending on the shot projection speed, an effect similar to that of heat-treating the inner surface of the inner part. Is obtained, and the strength of the engaging portion is increased. (4) A concave spherical surface portion forming step of forming a concave spherical surface portion that slides with the shoe device on a portion of the inner side surface of the engagement concave portion formed by the pair of arm portions is included. A method for manufacturing a piston for a swash plate compressor according to any one of (3). (5) The fine shot peening step is performed after the concave spherical surface forming step, and the fine shot containing at least one material of tin, molybdenum disulfide, PTFE, and graphite is used. Four)
A method for manufacturing a piston for a swash plate compressor according to item. A fine shot peening process is performed after forming the concave spherical surface, and as fine shots, tin, molybdenum disulfide, P
If a lubricous shot made of a material containing at least one of TFE and graphite is used, the fine shot collides not only with the inner surface of the back part but also with the concave spherical surface, and tin, molybdenum disulfide, PTFE ， At least one kind of graphite adheres. Since the concave spherical surface is a sliding surface that slides on a spherical crown shoe or a spherical body, it is tin-plated or solid containing a solid lubricant such as molybdenum disulfide, PTFE or graphite in order to improve sliding characteristics. Forming a lubricant layer is performed,
According to the invention of this section, these processes can be omitted. The fine shot may or may not be projected not only on the inner surface of the back portion but also on the concave spherical surface portion.
This is because if the fine shot bounces back toward the inner surface of the inner part of the back, it will inevitably collide with the concave spherical surface. (6) The fine shot peening step includes a step of projecting the fine shot onto the outer peripheral surface of the piston head as well, in the piston for a swash plate compressor according to any one of the paragraphs (1) to (5). Production method. This section should be implemented in parallel with the features described in section (5). That is, it is desirable to project a lubricating shot containing at least one material of tin, molybdenum disulfide, PTFE and graphite on the outer peripheral surface of the piston head. The outer peripheral surface of the piston head, which is slidably fitted in the cylinder bore, is coated with various coatings to prevent sliding and improve sliding characteristics. When the sexuality shot is projected, the material adheres to the outer peripheral surface of the piston head and a lubrication effect is produced, so that the coating process can be omitted. (7) As the fine shot, a mixture of a hard shot having a hardness equal to or higher than that of the piston material and a lubricating shot made of at least one of tin, molybdenum disulfide, PTFE and graphite is used.
A method of manufacturing a piston for a swash plate compressor according to item (5) or (6). Although the reinforcing effect of the engaging portion can be obtained even when only the lubricious shot is made to collide, it is unavoidable that the reinforcing effect is slightly smaller than that when the hard shot is made to collide. On the other hand, if a mixture of hard shots and lubricity shots is used, it is possible to sufficiently obtain both the effect of enhancing the engaging portion and the effect of improving the sliding characteristics of the concave spherical surface portion. For hard shots, steel shots such as stainless steel,
Ceramic shots such as carborundum and glass beads are suitable. (8) The fine shot peening step comprises a hard shot peening step in which a hard shot having a hardness equal to or higher than that of a piston material is collided, and lubrication made of at least one of tin, molybdenum disulfide, PTFE and graphite. A method for manufacturing a piston for a swash plate compressor according to item (5) or (6), further comprising: a lubricative shot peening step of causing a sexual shot to collide. After strengthening the engaging part by carrying out the hard shot peening process,
Even if the sliding characteristics of the concave spherical surface portion are improved by carrying out the lubricity shot peening step, the same effect as in the above item can be obtained. Moreover, since the hard shot adhered to the concave spherical surface portion in the hard shot peening step is removed by the collision of the lubricating shot in the lubricative shot peening step, it is possible to prevent the sliding characteristics of the concave spherical surface portion from being impaired by the hard shot. You can (9) No heat treatment is applied to the piston material or the intermediate product other than the fine shot peening step.
A method for manufacturing a piston for a swash plate compressor according to any one of items (1) to (8). The piston for a swash plate type compressor is usually subjected to heat treatment such as T6 treatment and T7 treatment for the purpose of increasing the strength. However, fine shot peening is applied to the inner surface of the inner portion of the engaging portion to remove the engaging portion. If it is increased, the heat treatment can be omitted. For example, if a piston material is cast by the pore-free die casting method and further squeezed, a good piston material having no apparent bubbles or porosity can be obtained. However, it is difficult to obtain a material having no trapped gas inside, and when heat treatment such as T6 or T7 treatment is performed, the material becomes soft and the trapped gas may expand to cause a blister. This blister not only impairs the appearance of the product, but also lowers the strength. However, if the heat treatment is omitted according to the present invention, the occurrence of blister can be avoided. (10) The method for manufacturing a piston for a swash plate compressor according to any one of the items (1) to (4), which includes a plating step of performing tin plating on the concave spherical surface portion. If the concave spherical surface portion is tin-plated, the slidability with the shoe device can be improved. Further, if the plating step is performed after the fine shot peening step, the hard shot attached to the concave spherical surface portion is removed, and the slidability is improved also from this point. Tin plating is
Since aluminum melts and tin adheres instead, the aluminum around the hard shot melts and the hard shot falls off, and both of this and the formation of the tin plating layer cause the sliding of the concave spherical surface. The dynamic characteristics are improved. Further, since a plurality of cleaning steps including alkali cleaning are performed in association with tin plating, it can be expected that hard shots will be removed during these cleaning steps. (11) In the die casting process, as a piston material,
It is a step of casting the one provided with a reinforcing portion that connects the pair of arm portions of the engaging portion to each other to reinforce the engaging portion,
Further, the manufacturing method is a method for manufacturing a piston for a swash plate compressor according to any one of items (1) to (10), which includes a step of removing a reinforcing portion for removing the reinforcing portion. The piston material is often provided with a reinforcing portion that connects the pair of arm portions to each other to reinforce the engaging portion. When the piston material is used to manufacture a single-headed piston, and two single-headed piston materials are cast in series, a large bending moment acts on the piston material during cutting. Since it is unavoidable to do so, a reinforcing portion is particularly required. The reinforcing portion may be provided not only for the purpose of reducing elastic deformation due to the force applied during machining of the piston material as described above, but also for the purpose of preventing distortion during heat treatment. (12) The method for manufacturing a piston for a swash plate compressor according to the item (11), which includes, after the step of removing the reinforcing portion, a step of imparting a plastic deformation to the engaging portion so as to generate tensile residual stress on the inner surface of the inner portion. The piston material is often deformed because it is cut by the time it is made into a finished product piston or is heated for performing a coating process or heat treatment described later. In order to remove this deformation or to give a deformation suitable for canceling the deformation in advance, plastic deformation that causes tensile residual stress may be applied to the inner surface of the inner part of the engagement portion. (13) The method for manufacturing a piston for a swash plate compressor according to item (12), wherein the fine shot peening step is performed after the plastic deformation imparting step. If the fine shot peening is performed after the engaging part is plastically deformed in the direction that causes the tensile residual stress on the inner surface of the inner part, the tensile residual stress once generated is reduced or eliminated, or further the compressive residual stress is generated. Is generated and the strength of the engaging portion is increased. (14) The die casting step is a step of casting, as the piston material, a piston material having a reinforcing portion that connects the pair of arm portions of the engaging portion to each other to reinforce the engaging portion, and The method is an outer peripheral surface processing step of cutting at least the outer peripheral surface of the head of the piston material, a reinforcing portion removing step of removing the reinforcing portion after the outer peripheral surface processing step, and at least after the outer peripheral surface processing step. A coating step of applying a thermosetting resin coating to the outer peripheral surface of the head portion, the fine shot peening step is after the die casting step, and any of the steps performed after the die casting step. The method for manufacturing a piston for a swash plate compressor according to any one of items (1) to (10), which is carried out before. When the reinforcing portion is formed in the form of a continuous reinforcing rib on the base portion, the fine shot peening step needs to be performed after the reinforcing portion removing step is performed. When it is formed as a bridge portion that connects the two to each other, it is possible to perform the fine shot peening step before the reinforcement portion removing step. As the thermosetting resin, polytetrafluoroethylene, polyamideimide, epoxy resin, polyetheretherketone (PEEK resin), phenol resin, furan resin, urea resin, unsaturated polyester and the like are preferable. (15) A piston head that is slidably fitted in the cylinder bore, and an engaging portion that engages with the swash plate via a pair of shoes, the engaging portion being aligned with the axis of the piston head. A base portion extending substantially in parallel, and a pair of arm portions extending from both ends of the base portion in a direction substantially orthogonal to the axis,
A piston for a swash plate compressor that forms an engagement recess that accommodates an outer peripheral portion of the swash plate, the piston being made of an aluminum alloy, and at least the base portion and the base portion of the inner side surface of the engagement recess. And an average grain size of 5 on the inner surface of the inner part formed by the boundary between the pair of arms.
A piston for a swash plate compressor, characterized by being subjected to fine shot peening by fine shots of 00 μm or less. (16) The piston for a swash plate compressor according to item (15), which is manufactured from a piston material cast by an aluminum alloy die casting method. (17) The piston for a swash plate compressor according to item (16), wherein the piston material is die-cast by a pore-free method. (18) The piston for a swash plate compressor according to the item (17), which is manufactured from a piston material that is squeezed during die casting of the pore-free method. (19) A concave spherical surface portion is formed on a portion of the inner surface of the engaging portion formed by the pair of arm portions, and a slidability improving substance is adhered to the concave spherical surface portion. (1
The piston for a swash plate compressor according to any one of items 8). (20) The piston for a swash plate compressor according to item (19), wherein the slidability improving substance adhered to the concave spherical surface portion is tin plating. (21) The piston material or the intermediate product from the piston material to the finished product piston is not subjected to heat treatment for the purpose of increasing strength. Piston for plate compressor.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for manufacturing a piston for a swash plate type compressor, which is an embodiment of the present invention, and a swash plate type compressor having a piston manufactured by the method will be described in detail with reference to the drawings. FIG. 1 shows a swash plate compressor according to this embodiment. In FIG. 1, reference numeral 10 denotes a cylinder block, and a plurality of cylinder bores 12 are formed in parallel with the center axis of the cylinder block 10 on a circumference thereof. A single-headed piston 14 (hereinafter abbreviated as piston 14) is provided in each of the cylinder bores 12 so as to reciprocate. The front housing 1 is attached to one end surface of the cylinder block 10 in the axial direction.
6 is attached to the other end surface of the rear housing 1
8 is attached via a valve plate 20.
The housing 21 of the swash plate type compressor including the front housing 16, the rear housing 18, the cylinder block 10 and the like.
Is configured. A suction 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 a suction port 26 and a supply port 28, respectively. The valve plate 20 includes a suction hole 32, a suction valve 34, a discharge hole 36,
A discharge valve 38 and the like are provided.

A rotary shaft 50 is provided in the housing 21.
Is rotatably provided with the center axis of the cylinder block 10 as the rotation axis. One end of the rotary shaft 50 is connected to a drive source (not shown). A swash plate 60 is attached to the rotating shaft 50 so as to be relatively movable and tiltable in the axial direction. A through hole 61 passing through the center line is formed in the swash plate 60, and the rotary shaft 50 penetrates the through hole 61. The through hole 61 has a gradually increasing inner dimension in the up-down direction in FIG. 1 on the opening side of both ends, and the cross-sectional shape of these both ends is a long hole. A rotary plate 62 is fixed to the rotary shaft 50 and is received by the front housing 16 via a thrust bearing 64. The swash plate 60 is rotated integrally with the rotary shaft 50 by the hinge mechanism 66, and is allowed to tilt with axial movement. The hinge mechanism 66 includes a support arm 67 fixedly provided on the rotary plate 62, 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 through hole 61 of the swash plate 60 and the outer peripheral surface of the rotary shaft 50 are included.

The piston 14 is, as shown in FIG.
An engaging portion 70 that is engaged with the swash plate 60 while straddling its outer peripheral portion, and a head portion 7 that is integrally provided with the engaging portion 70 and that is slidably fitted into the cylinder bore 12 as a piston head portion.
2 and. The head 72 in the present embodiment is a hollow head to reduce the weight. The head 72, the cylinder bore 12, and the valve plate 20 cooperate to form a compression chamber. Further, the engagement portion 70 is engaged with the outer peripheral portion of the swash plate 60 via a pair of spherical crown shoes 76. The piston 14 in this embodiment is referred to as a single-headed piston because it has the head 72 only on one side of the engaging portion 70.

The piston 14 is reciprocated by the rotation of the swash plate 60. Specifically, the rotational movement of the swash plate 60 is converted into the reciprocating linear movement of the piston 14 via the shoes 76. During 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 sucked into the suction holes 32,
It is sucked into the compression chamber in the cylinder bore 12 through the suction valve 34. In the compression stroke in which the piston 14 moves from the bottom dead center to the top dead center, the refrigerant gas in the compression chamber inside the cylinder bore 12 is compressed and discharged into the discharge chamber 24 through the discharge hole 36 and the discharge valve 38. With the compression of the refrigerant gas, an axial compression reaction force acts on the piston 14. The compression reaction force is received by the front housing 16 via the piston 14, the swash plate 60, the rotary plate 62, and the thrust bearing 64.

An air supply passage 80 is provided through the cylinder block 10. The air supply passage 80 connects the discharge chamber 24 and the swash plate chamber 86 formed between the front housing 16 and the cylinder block 10. An electromagnetic control valve 90 is provided in the middle of the air supply passage 80. The current supply to the solenoid 92 of the electromagnetic control valve 90 is controlled by a control device (not shown) mainly composed of a computer according to information such as a cooling load.

A discharge passage 100 is provided inside the rotary shaft 50. The discharge passage 100 is opened at one end into a support hole 56 provided in the center of the cylinder block 10 and at the other end is opened into a swash plate chamber 86. The support hole 56 is communicated with the suction chamber 22 via the discharge port 104.

The swash plate type compressor is 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 on the high pressure side and the suction chamber 22 on the low pressure side. , The difference between the pressure of the compression chamber in the cylinder bore 12 acting before and after the piston 14 and the pressure of the swash plate chamber 86 is adjusted,
The tilt angle of the swash plate 60 (the angle formed by the swash plate 60 and the plane perpendicular to the rotation axis of the rotation shaft 50) is changed to allow the piston 14 to move.
The stroke is changed and the discharge capacity of the compressor is adjusted. Specifically, the pressure in the swash plate chamber 86 is controlled by controlling the excitation and demagnetization of the electromagnetic control valve 90 so that the swash plate chamber 86 is communicated with or cut off from the discharge chamber 24. In the swash plate compressor of the present embodiment, the swash plate tilt angle changing device that changes the tilt angle of the swash plate includes the hinge mechanism 66, the cylinder bore 12, the piston 14, the suction chamber 22, the discharge chamber 24, Support hole 56, air supply passage 80, swash plate chamber 86, electromagnetic control valve 90, discharge passage 100,
The exhaust port 104 and a control device (not shown) are included.

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, direct contact with the same kind of metal can be avoided, seizure can be prevented, and the fitting gap with the cylinder bore 12 can be made as small as possible. 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 materials, and other materials may be used.

In the present embodiment, the head 72 of the piston 14 has a bottomed cylindrical portion 110 which constitutes a main part of the head 72.
The opening is closed by the closing member 112. The bottomed cylindrical portion 110 is formed integrally with the engaging portion 70. However, in addition to this, the head 7 of the piston 14
It is also possible that the opening of the bottomed cylindrical member forming the main part of No. 2 is closed by the closing portion formed integrally with the engaging portion 70.

As shown in FIG. 2, the engagement portion 70 of the piston 14 has a base portion 118 extending parallel to the central axis of the head portion 72.
And a pair of arm portions 120, 122 extending in parallel to each other in the direction orthogonal to the central axis of the head portion 72 from both end portions of the base portion 118 that are separated from each other in the axial direction, and accommodate the outer peripheral portion of the swash plate 60. The engaging recess is formed. Base 118
Connects the base ends of the arm portions 120 and 122 to each other. A concave spherical surface portion 130 serving as a shoe holding surface is formed on each of inner surface 126, 128 of the arm portion 120, 122 facing each other. These two concave spherical surfaces 1
30 is located on the same spherical surface.

The pair of shoes 76 has a spherical crown shape having a spherical surface portion 132 whose one outer surface is a generally convex spherical surface and a flat surface portion 138 whose other outer surface is a generally flat surface. The pair of shoes 76 are slidably held on the concave spherical surface portion 130 of the piston 14 on the spherical surface portion 132, and on the flat surface portion 138, both sliding surfaces 140, 1 which are both side surfaces of the outer peripheral portion of the swash plate 60.
42, and the outer peripheral portion of the swash plate 60 is clamped from both sides.
The pair of shoes 76 is designed so that the convex spherical surface of the spherical surface portion 132 is located on the same spherical surface in this state. That is,
The shoe 76 in this embodiment has a spherical crown shape that is smaller than the hemisphere by about half the thickness of the swash plate 60. In the present embodiment, tin plating is applied to the pair of concave spherical surface portions 130, and sliding characteristics such as reduction of sliding resistance with the shoe 76 and prevention of seizure are improved. The shape of the shoe is not limited to the above shape. For example, in a fixed displacement compressor, it is desirable that the surface area of the sliding surface be slightly larger than that of the hemisphere even if the flat surface of the shoe is worn.

The swash plate 6 in the arms 120 and 122
The inner side surface 126, which faces both sliding surfaces 140 and 142 of 0.
As shown in FIG. 3, the swash plate 60 is provided at both ends of the swash plate 60 in the circumferential direction, which are the intersections of the inner surface 150 of the base 118 and the outer surface of the swash plate 60 facing the outer surface of the base 118. Relief portion 15 for avoiding interference with the outer peripheral edge of the
2 is formed.

In this embodiment, two pistons 14 having the above-mentioned structure are manufactured from one piston material. Therefore, as shown in FIG. 4, the piston material 160 for manufacturing the piston 14 includes a main body member 162 and a closing member 164. The main body member 162 includes the engaging portion 16
6 and a bottomed cylindrical portion 170 that opens in the direction opposite to the engaging portion 166. The main body member 162 includes the engaging portion 1 so that the two bottomed cylindrical portions 170 are concentric with each other.
It is a double material in which the 66 side is adjacent to each other and integrally formed. The engagement portion 166 is a portion that is to be the engagement portion 70 in the piston 14 that is a finished product.

The engaging portion 166 is formed by a base portion 172 extending parallel to the central axis of the bottomed cylindrical portion 170, and from both end portions of the base portion 172 axially separated from each other, the engagement portion 166 is orthogonal to the central axis line of the bottomed cylindrical portion 170. And a pair of arm portions 174 and 176 extending in parallel with each other in the direction of forming the engaging concave portion. Reinforcing ribs 188 as reinforcing portions that connect the inner side surfaces 180, 182, 184 of the base portion 172 and the pair of arm portions 174, 176 are integrally formed. The reinforcing rib 188 is provided to increase the rigidity of the engaging portion 166 and to suppress distortion due to heat.

The body member 162 is made of aluminum alloy, which is a kind of metal, and is manufactured by casting. This step is the die casting step S10 shown in FIG. In addition,
FIG. 5 is a flowchart showing each manufacturing process of the piston manufacturing method in the present embodiment, and a schematic diagram of each process is also shown correspondingly. In this embodiment, the body member 162 is manufactured by the pore-free die casting method. A part of the mold 200 used in the die casting step S10 of the present embodiment is schematically shown in FIG. Mold 20
0 is openable and closable. The pore-free die casting method is a method in which a cavity 206 of a mold 200 is filled with an active gas such as oxygen and a molten metal such as an aluminum alloy is injected into the cavity 206, and a reaction between the molten metal and the active gas causes the cavity to flow. This is a casting method in which gas is prevented from being entrained inside the cast product by setting the interior of 206 to a high vacuum state, and it is possible to obtain a cast product that is thin and has high strength. Further, a pair of slide cores 208 (only one of them is shown in FIG. 6) capable of relatively moving in the axial direction are provided inside the mold 200.
The bottomed cylindrical portion 170 is formed by the cooperation of the outer peripheral surface 08 and the cavity 206. In the slide core 208, the pressure member 210 is provided in the slide core 2
It is provided separately from 08 in such a manner that it can be moved in the axial direction, and the molten metal becomes semi-fluid after the set time has elapsed after the molten metal has been injected into the cavity 206, as shown in FIG. 210 is projected from the slide core 208 and pushed into the molten metal to perform squeeze. Therefore, the porosity of the molten metal can be effectively eliminated. The pressure member 210 is advanced to a state where it cannot move any further, and after a lapse of a set time, the pressure member 210 is retracted. Further, the slide core 208 is detached from the bottomed cylindrical portion 170, and the mold 200 is opened, whereby the main body member 162.
Is obtained. The squeeze mark formed by the pressing member 210 remains on the main body member 162. This may be removed by machining, but since it is formed on the bottom surface of the bottomed cylindrical portion 170 and is in the space to be closed later by the closing member 164, there is no problem if left as it is.

In the fixing step S12, the main body member 162 manufactured through the die casting step S10 and the closing member 164 manufactured separately by casting or the like are subjected to beam welding,
The piston material 160 is manufactured by being fixed by an appropriate fixing means such as adhesion or press fitting. In FIG. 4, the body member 162 is shown.
The opening of the bottomed cylindrical portion 170 is closed and fixed by the closing member 164. A holding portion 220 is provided at the center of one end surface of the closing member 164, and a center hole 222 (see FIG. 3) is formed in the holding portion 220.
(Indicated by a chain double-dashed line). In the outer peripheral surface processing step described later, the holding portion 220 and the center hole 2
22 is used to center and hold the piston material 160.

After the closing member 164 is fixed to the main body member 162, the portion that will form the head 72, that is, the outer peripheral surface of the bottomed cylindrical portion 170 of the main body member 162 and the outer peripheral surface of the closing member 164. First, a plurality of parts are cut. After the outer peripheral surface of the portion that will form the head 72 is cut, the holding portion 220 is removed and the end surface of the closing member 164 is cut. The above is the outer peripheral surface processing step S14.

In the intermediate product 230 that has undergone the outer peripheral surface processing step S14, the inner surface 180, 182, 184 of the engaging portion 166 is machined in the next inner surface cutting step S16, and at the same time, the flash and the reinforcing rib 188 are formed. Are removed. That is, the inner surface cutting step S16 also includes a reinforcing portion removing step. In this step S16, the engaging portion 166
The dimensional accuracy of is improved. Further, the inner side surface 180 of the base 172 and the inner side surfaces 182 of the arm portions 174, 176 are
At both ends of the intersection with 184, the above-mentioned relief portion 152
Are formed by cutting.

After the inner surface cutting of the intermediate product 230 is completed, the intermediate product 230 is moved from the base 172 side to the arm parts 174, 176.
It is plastically deformed so as to be convex downward toward. This is the plastic deformation imparting step S18. In this step S18, as shown in FIG. 5, both ends of the intermediate product 230 are supported by a pair of support blocks 240 (illustrated by a chain double-dashed line) and attached to a ram of a strain relief press which is a kind of plastic deformation imparting device. The pressure member 242 thus pressed is pressed against the central portion of the intermediate product 230 to be plastically deformed. 2 of intermediate products 230
At the central position where the two engaging portions 166 are connected to each other, a load is applied downward from above in the direction in which the arms 174 and 176 extend from the base 172 side, so that the intermediate product 230 moves slightly downward. It is plastically deformed convexly. In FIG. 5, the deformation amount of the intermediate product 230 is exaggeratedly shown for easy understanding. In the piston material, particularly in the case of the double material that is long in the axial direction as in the present embodiment, the outer peripheral surface of the intermediate product 230 is coated as described later, and warpage occurs when firing. The direction and size of the warp of the piston material are substantially constant for each shape and size of the piston material. Therefore, the direction and size of the warp of the intermediate product 230 in the present embodiment are predicted and the plastic deformation imparting step is performed. The direction and magnitude of the plastic deformation in S18 are set so as to cancel the warpage. In this step S18, the inner side surfaces 180, 182 of the engaging portion 166 of the intermediate product 230 are
The inner surface 246 of the inner part of the inner part 246 formed by the boundary part between the base part 172 and the arm parts 174, 176 (see FIG. 7).
), A tensile residual stress is generated.

Next, the inner surface 2 at the back of the intermediate product 230
Fine shots are struck at 46 at high speed. This is the fine shot peening step S20. The fine shot peening is omitted from the illustration of the entire apparatus, but FIG.
As shown in (1), the jet nozzle 250 ejects a gas flow mixed with fine shots. In the fine shot peening step S20, the intermediate product 230
A fine shot having an average grain size of 200 μm or less is projected toward the inner surface 246 of the inner part of the slag at a speed of about 50 m / sec or more. As the fine shot, it is desirable to use a hard shot having a hardness equal to or higher than that of the intermediate product 230. As the hard shot, a steel shot such as stainless steel, a ceramic shot such as carborundum, and glass beads are suitable. The average particle size of the fine shots is preferably 120 μm or less, and 80 μm or less.
It is more desirable that the thickness be m or less. The projection speed of the fine shot is preferably 80 m / sec or more, and 1
It is more desirable to set the speed to 00 m / sec or more.

In this way, the engaging portion 1 of the intermediate product 230
When the hard shot collides with the inner side surfaces 180, 182, 184 of 66, particularly the inner side surface 246 of the inner part, the inner side surfaces 180, 182, 184 including the inner side surface 246 of the inner part are struck and fine cutouts are removed. , The surface is smoothed. In addition, compressive residual stress is generated on the inner surface 246 of the inner part,
The strength of the engaging portion 166 increases. This point will be described later in detail.

After the fine shot peening step S20,
Main body member 16 which is at least a portion forming the head 72
2, the outer peripheral surface of the bottomed cylindrical portion 170 and the closing member 164.
The outer peripheral surface of the is coated with a thermosetting resin to form a coating layer. This is the coating process S2
It is 2. As the thermosetting resin, polytetrafluoroethylene, polyamide imide, epoxy resin, polyether ether ketone (PEEK resin), phenol resin, furan resin, urea resin, unsaturated polyester, etc. are suitable, and in the present embodiment, A coating layer containing polytetrafluoroethylene as a main material is formed. After the coating layer is formed, a baking treatment is performed by heating to evaporate the solvent of the coating film of the coating layer and bring the coating film into close contact with the outer peripheral surface. This is a firing step, and this firing step is the coating step S2.
Included in 2. The intermediate product 230 after the firing step is in a state in which the warpage imparted in the plastic deformation imparting step S18 is eliminated.

After the coating step S22, centerless polishing is performed on the outer peripheral surface of the bottomed cylindrical portion 170 having the coating layer formed thereon, and the head 72 is completed. Subsequently, the engaging portions 166 are each machined so that the piston 14
The concave spherical surface portion 130 that holds the shoe 76 when it becomes is formed, and the engaging portion 70 is completed. This step is the concave spherical surface forming step S24. Subsequently, in the separation step S26, the intermediate product 230 is separated into two, and two pistons 14 are obtained. After the separation step S26, the piston 1
The pair of concave spherical surface portions 130 of No. 4 is tin-plated. This is the plating step S28. In this way, the piston 14 as a finished product is obtained.

When the piston 14 as a product is incorporated in the swash plate type compressor, the gap between the pair of arm portions 120 and 122 is set in the engaging portion 70 (the engaging portion 166 in the intermediate product 230) during the operation of the compressor. The expanding force is repeatedly applied to generate a tensile stress on the inner surface 246 of the inner part. In particular, stress is likely to be concentrated at the boundary between the base 118 and the arms 120 and 122, and a large tensile stress is generated on the inner surface 246 at the inner part of the piston, but the piston manufactured through the fine shot peening step S20 of the present embodiment. As described above, in No. 14, the inner surface 246 of the inner portion of the engaging portion 70 is made smooth and compressive residual stress is generated, so that the fatigue strength is increased. Therefore, the piston 1 with excellent durability
4. Consequently, a swash plate type compressor excellent in durability can be obtained.
As in the present embodiment, when the piston material is manufactured by the pore-free die casting method, a good quality piston can be obtained, but it is still not sufficient in strength, and conventionally, immediately after casting of the piston material. T6 for the purpose of improving strength
Heat treatment such as treatment or T7 treatment was performed. On the other hand, in the present embodiment, since the strength of the engaging portion 70 of the piston 14 is improved by performing the fine shot peening step S20, the piston material 160 and the intermediate product 230 are subjected to heat treatment such as T6 and T7. Not done. Since the heat treatment step can be omitted, the manufacturing cost of the piston 14 can be reduced, and a good quality piston 14 without blister that is likely to occur during heat treatment can be obtained.

The piston 14 manufactured as described above
The fatigue strength of the engaging portion 70 was tested. The result of the fatigue strength test is shown in FIG. In carrying out the present fatigue strength test, a piston manufactured by the manufacturing method of the present embodiment (hereinafter referred to as “invention product”) and a piston manufactured for comparison (hereinafter referred to as “comparative example”) , And each of them, and for each of them,
A load that does not damage the engaging portion 70 was examined even if the load for widening the distance between the pair of arm portions 120 and 122 was repeated 10 ⁷ times. As the product of the present invention, the piston 14 is manufactured by the manufacturing method described in the above embodiment, and particularly, in the fine shot peening step S20, the average particle diameter of the fine shot is variously changed (100 μm, 200 μm).
m, 500 μm), and a plurality of pistons 14 were obtained for each fine shot of each average particle size. As a fine shot,
Glass beads are used, and the projection speed is 100 m / sec, 80 m / sec, 50 m / s when the average particle size of the fine shot is 100 μm, 200 μm, and 500 μm, respectively.
ec. Further, as a comparative example, a plurality of pistons (shown as “no treatment” in FIG. 8) were manufactured without performing the fine shot peening process.

As is clear from the graph of FIG. 8, the piston 14 manufactured through the fine shot peening step S20 (piston 14 of the present invention) is a piston not subjected to the fine shot peening step (the piston of the comparative example). ) Is superior in fatigue strength. In particular, in the product of the present invention using the fine shots having an average particle size of 200 μm or less, the fatigue strength was improved by about 20% on average as compared with the comparative example. Even when the average particle size was 500 μm, on average, the fatigue strength was superior to that of the comparative example. Further, the variation of the fatigue strength of the plurality of pistons 14 subjected to the fine shot peening step S20 for each average particle size is
The size is smaller than that of the comparative example, and it has been clarified that the manufacturing method of the present invention can stably manufacture the high-strength piston 14 that can sufficiently withstand use in a compressor.

The fine shot peening step S20
As described above, instead of after the plastic deformation imparting step S18 and before the coating step S22, may be performed after the coating step S22 and before the concave spherical surface forming step S24.

The pressing member 210 for pushing the molten metal is pushed into the side surface of the reinforcing rib 188, as shown in FIG.
It is also possible to be pushed into the outer surface of the engaging portion 166. However, in these cases, the squeeze marks after the squeeze must be removed by machining.

As described above, instead of performing the fine shot peening step S20 before the concave spherical surface forming step S24, it may be performed after the concave spherical surface forming step. One embodiment thereof is shown in FIG. However, in the present embodiment, the same steps as those in the above-described embodiment are designated by the same step numbers, and the description thereof will be omitted. Only parts different from the above-described embodiment will be described. Similar to the above embodiment, the die casting step S1
0, fixing step S12, outer peripheral surface processing step S14, inner side surface cutting step S16, plastic deformation imparting step S18, coating step S22, concave spherical surface forming step S24, intermediate product 2
At 30, a fine shot peening step S25 is performed. In the fine shot peening step S25, the intermediate product 230 is turned toward the inner surface 246 on the inner side of the intermediate product 230.
A mixture of a hard shot having a hardness equal to or higher than that and a lubricating shot made of at least one material of tin, molybdenum disulfide, PTFE and graphite is projected. The average particle size and the projection speed of the fine shot, the material of the hard shot, and the like may be the same as in the above embodiment. If the mixture of the hard shot and the lubricous shot is projected onto the engaging portion 166, the engaging portion 16 is similar to that described in the above embodiment.
A strength increasing effect of 6 is obtained. Further, the mixture collides with the inner surface 246 of the inner portion of the engaging portion 166 and the peripheral portion thereof and bounces back, and also collides with the concave spherical surface portion 130. This smoothes the surface of the concave spherical surface portion 130, and
Lubricating shots such as tin adhere to the surface of the concave spherical surface portion 130, and an effect similar to that when a lubricating layer is formed on the concave spherical surface portion 130 is obtained, and the sliding characteristics of the concave spherical surface portion 130 are improved.
Therefore, it is possible to omit the plating step S28 performed in the above embodiment.

Fine shot peening step S25
Can also include a hard shot peening step of projecting a hard shot and a lubricous shot peening step of projecting a lubricating shot. That is, instead of using the mixture of the hard shot and the lubricious shot as described above, the projection of the hard shot and the projection of the lubricous shot are performed as separate steps. The material, average particle diameter, projection speed, and the like of the hard shot and the lubricous shot may be the same as those in the above-described embodiment, but the hard shot is the engaging portion 1.
It is desirable to project toward the inner surface 246 at the inner portion of the inner portion 66 and to project the lubricating shot toward the concave spherical surface portion 130. Also in this embodiment, the same effect as in the above embodiment can be obtained, and in the hard shot peening step, the concave spherical surface portion 13 bounces from the inner surface 246 of the inner portion of the recess.
Since the hard shot adhered to 0 is removed by the collision of the lubricating shot, the concave surface portion 13 due to the hard shot is removed.
A unique effect is obtained in which the deterioration of the sliding property of 0 is favorably avoided.

In addition to the configuration shown in FIG. 4, the reinforcing portion of the piston material is, like the piston material 300 shown in FIG. 11, the inner side surfaces 182 of the pair of arm portions 174, 176.
It is also possible to adopt a form of the bridge portion 302 that connects the 184 to each other. In the piston material 300, the same components as those of the piston material 160 are designated by the same reference numerals and the description thereof will be omitted. The method for manufacturing a piston for a swash plate compressor using this piston material 300 can be the same as that described in each of the above-described embodiments, but another two embodiments will be described with reference to FIGS. 12 and 1.
Each will be described based on 3.

In the embodiment shown in FIG. 12, the piston material 300 manufactured by the die casting step S30 and the fixing step S32 is processed by the outer peripheral surface processing step S34, the coating step S36 and the inner surface cutting step S38 (the bridge portion 3).
The intermediate product 304 is subjected to a fine section peening process S40. After that, through the concave spherical surface forming step S42 and the separating step S44, the piston 14 as a finished product is obtained. Die casting step S30, fixing step S32, outer peripheral surface processing step S34, coating step S36, inner side surface cutting step S38, concave spherical surface forming step S4
2 and the separation step S44 are the die casting step S1.
0, fixing step S12, outer peripheral surface processing step S14, coating step S22, inner side surface cutting step S16, concave spherical surface forming step S24 and separation step S26, and the fine shot peening step S40 is the fine shot peening step. It is carried out similarly to S20.

The fine shot peening step S40 may be performed after the concave spherical surface forming step S42 and before or after the separating step S44. In this case, the fine shot peening step may be performed by using a mixture of a hard shot and a lubricating shot as the fine shot, like the fine shot peening step S25 described in the embodiment shown in FIG. The hard shot peening process and the lubricity shot peening process may be performed separately.

In the embodiment shown in FIG. 13, the piston material 30 has undergone the die casting step S50 and the fixing step S52.
0 after the fine shot peening step S54 is performed, the outer peripheral surface processing step S56, the coating step S58,
The piston 14 is obtained through the inner surface cutting step S60 (including the reinforcing portion removing step of removing the bridge portion 302), the concave spherical surface forming step S62, and the separating step S64. Alternatively, the fine shot peening step S54 may be performed after the coating step S58 and before or after the inner surface cutting step S60.

Even if a double-headed piston having heads on both sides of the engaging portion with the swash plate is manufactured by the manufacturing method according to the present invention, the same effects as in the above-described respective embodiments can be obtained. An example of the double-headed piston is shown in FIG. The double-ended piston 400 is
An engaging portion 402 that engages with the swash plate via a shoe device, and heads 404 integrally formed with the engaging portion 402 on both sides of the engaging portion 402 are provided. The shoe device includes two pairs of spheres and a shoe, and the shoe has a generally disk shape, and has a flat portion that slides on the swash plate and a concave spherical portion that slidably accommodates the sphere. The piston material of the double-headed piston 400 is manufactured by die casting as in the above-described embodiments. The engaging portion 402 includes a base portion 406 extending substantially parallel to the axis of the head portion 404, and a pair of arm portions 410 extending from both ends of the base portion 406 in a direction substantially orthogonal to the axis line. An engaging recess is formed to accommodate the outer peripheral portion.
Fine shot peening is applied to the inner surface of the engaging recess. Two concave spherical surface portions 412 (only one of which is shown in FIG. 14) that slidably holds the spherical body are formed on the side surfaces of the pair of arm portions 410 that face each other.

Although some embodiments of the present invention have been described in detail above, these are merely examples, and the present invention is described in the above [Problems to be solved by the invention, means for solving problems and effects]. Various modifications and improvements can be performed based on the knowledge of those skilled in the art, including the described embodiments.

[Brief description of drawings]

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

FIG. 2 is a front view showing the piston together with a swash plate and a shoe.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a front view (partial cross section) showing a piston material for manufacturing the piston.

FIG. 5 is a diagram showing both a flowchart showing each step of the method for manufacturing the piston for a swash plate compressor and a schematic view of each step.

FIG. 6 is a front sectional view showing a die casting process of the above manufacturing method.

FIG. 7 is a diagram showing a fine shot peening step of the above manufacturing method.

FIG. 8 is a graph showing the results of each fatigue strength test of a piston manufactured by the above manufacturing method and a piston manufactured for comparison.

FIG. 9 is a front view showing another form of the pressing member used in the die casting process of the manufacturing method.

FIG. 10 is a flowchart showing each step of a method for manufacturing a piston for a swash plate compressor, which is another embodiment of the present invention.

FIG. 11 is a front view showing a piston material used in a method of manufacturing a piston for a swash plate compressor, which is still another embodiment of the present invention.

FIG. 12 is a flowchart showing each step of the manufacturing method.

FIG. 13 is a flowchart showing each step of a method for manufacturing a piston for a swash plate compressor, which is still another embodiment of the present invention.

FIG. 14 is a front view (partial cross section) showing a piston manufactured by a method for manufacturing a piston for a swash plate compressor which is still another embodiment of the present invention.

[Explanation of symbols]

14: Single-headed piston 60: Swash plate 70: Engagement part
72: Head 76: Shoe 118: Base 1
20, 122: Arms 126, 128: Inside surface
130: concave spherical surface part 150: inner surface 160:
Piston material 166: Engagement part 172: Base part 174, 176:
Arms 180, 182, 184: Inside surface 18
8: Reinforcing rib 230: Intermediate product 246: Inner side of inner part 300: Piston material 302: Bridge part 304: Intermediate product 400: Double-headed piston 4
02: Engagement portion 404: Head portion 406: Base portion 4
10: Arm part 412: Concave spherical surface part

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Osako Truth             2-1, Toyota-cho, Kariya City, Aichi Stock Association             Inside Toyota Toyota Industries F term (reference) 3H076 AA06 BB50 CC20 CC31 CC34                       CC99

Claims (7)

[Claims] 1. A piston head that is slidably fitted in a cylinder bore, and an engaging portion that engages with a swash plate via a shoe device, the engaging portion being an axis line of the piston head. A swash plate type that includes a base portion that extends substantially parallel to each other, and a pair of arm portions that extend from both ends of the base portion in a direction substantially orthogonal to the axis, and that forms an engagement concave portion that accommodates the outer peripheral portion of the swash plate. A method of manufacturing a piston for a compressor, which comprises at least a die casting process of casting a piston material made of an aluminum alloy by a die casting method, and an intermediate product between the piston material and a finished product, wherein the engagement An average particle size of 500 μm is provided on the inner surface of the inner part of the recess, which is formed at least by the base and the boundary between the base and the pair of arms.
A fine shot peening step of projecting the following fine shots at a speed of 50 m / sec or more, a method for manufacturing a piston for a swash plate compressor. 2. The die casting step is a step of casting the piston material by a pore-free method.
A method for manufacturing a piston for a swash plate compressor according to. 3. The inner surface cutting step of cutting the inner surface including the inner surface of the inner portion of the piston material, wherein the fine shot peening step is performed after the inner surface cutting step. 2. The method for manufacturing a piston for a swash plate compressor according to 2. 4. A concave spherical surface portion forming step of forming a concave spherical surface portion that slides with the shoe device on a portion of the inner surface of the engagement concave portion formed by the pair of arm portions,
The fine shot peening step is performed after the concave spherical surface forming step, and as the fine shot,
A material containing at least one material of tin, molybdenum disulfide, PTFE and graphite is used.
4. A method for manufacturing a piston for a swash plate compressor according to any one of 3 to 3. 5. The method for manufacturing a piston for a swash plate compressor according to claim 1, wherein neither heat treatment is performed on the piston material nor the intermediate product other than the fine shot peening step. 6. The method for manufacturing a piston for a swash plate compressor according to claim 1, further comprising a plating step of performing tin plating on the concave spherical surface portion. 7. The die casting step is a step of casting, as a piston material, a piston material including a reinforcing portion that connects the pair of arm portions of the engaging portion to each other to reinforce the engaging portion, and The manufacturing method includes a reinforcing portion removing step of removing the reinforcing portion, and after the reinforcing portion removing step, a plastic deformation imparting step of causing a tensile residual stress in the inner surface of the inner portion of the engaging portion, The shot peening step is performed after the plastic deformation imparting step.
7. A method for manufacturing a piston for a swash plate compressor according to any one of 6 to 6.