JP2001328032A - Method of making piston for swash plate type compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of turning a piston material without deteriorating work accuracy. SOLUTION: A material 160 for manufacture of a single-head piston is a tandem material with two head part forming parts 210 positioned in axially both end parts and two engaging part forming parts 166 in the central part. The engaging part forming part 166 is eccentrically placed relating to the head part forming part 210. Before roughing work and finishing work are applied to an external peripheral surface of the head part forming part 210, a center hole 216 is formed in a pair of protrusion parts 202 provided in the center of both end faces of the material 160. In a process of the roughing work, the external peripheral surface of the head part forming part 210 is machined by a cutter 230 with the material 160 rotated in a condition that the material 160 is supported from both sides by engaging centers 220, 222 with the center hole 216. Successively in a process of the finishing work, the external peripheral surface is finished by a depth of cut at a feed speed of the cutter 230 smaller than at roughing work time in a condition that the material 160 is supported by clamp force smaller than clamp force of the centers 220, 222 at roughing work time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a piston for a swash plate type compressor, and more particularly to an improvement in a process for turning a piston blank while supporting the piston blank at both centers.

[0002]

2. Description of the Related Art Swash plate compressors are widely used as refrigerant gas compressors for air conditioners for vehicles.
The piston is engaged with the swash plate, and the piston is reciprocated in the cylinder bore with the rotation of the swash plate to suck and compress the refrigerant gas. For this purpose, the piston is configured to include a head that is fitted substantially airtightly and slidably into the cylinder bore, and an engaging portion that engages with the outer peripheral portion of the swash plate via a shoe device. The engaging portion includes a pair of arms extending substantially parallel to each other and a connecting portion for connecting the arms, the connecting portion extends beyond the outer peripheral surface of the swash plate, and the pair of arms each includes a shoe. It engages both sliding surfaces of the swash plate via the device. The shoe device is composed of a ball and a shoe having a concave spherical surface that receives the ball, and a hemisphere that forms a substantially hemisphere and slides on the sliding surface of the swash plate on a substantially planar sliding surface. In some cases, it is composed of shoes. A double-headed piston having a head on both sides of the engaging portion and a single-headed piston having a head only on one side of the engaging portion are used, and the latter mainly discharges by changing the inclination angle of the swash plate. It is used in variable displacement swash plate compressors that change capacity.

[0003] The piston is generally manufactured by machining a piston material formed by forging or casting. In order to reduce the weight of the piston, the head may be hollow, in which case, for example, by closing the opening of a main body member having a cast or forged bottomed cylindrical portion with a closing member. Then, a piston material having a portion to be a hollow head is manufactured. The piston material may be a multiple material in which a plurality of piston materials are connected in series.

[0004] In any case, it is necessary to cut the outer peripheral surface of at least the portion to be the head of the piston blank, and this cutting is often performed by forming center holes at both ends of the piston blank. And turning using the center holes. Insert a pair of centers into both center holes,
By applying a clamping force to the pair of centers so as to approach each other, the piston material is supported by the pair of centers, and the piston material is rotated in that state, so that the outer peripheral surface is cut. is there.

[0005]

When turning the piston blank, if at least one of the cutting depth and the feed rate of the cutting tool is increased (hereinafter, turning conditions will be referred to as strict). ), The machining efficiency can be improved, but in that case, the cutting resistance acting on the piston material increases. In order to counter the large cutting force, it is necessary to increase the axial clamping force of the piston material by the pair of centers, but if the clamping force is increased, the bending due to the elastic deformation of the piston material increases, This causes a decrease in accuracy. As described above, the piston material is provided with the engaging portion, and since the engaging portion is generally eccentric with respect to the head due to its function, the clamping force in the axial direction is reduced by the piston material. And the piston material is elastically bent. In this state, the outer peripheral surface is cut into a cylindrical shape by the cutting tool, but when turning is completed and the clamping force in the axial direction is released, the piston material returns to almost the state before elastic deformation, and the head Is inclined with respect to the axis defined by both center holes. In particular, when the piston material is a multiple material, the outer peripheral surfaces of the plurality of heads are not located on one cylinder.

[0006] Since the multiple material is later separated into individual piston portions, it seems that there is no problem even if the outer peripheral surfaces of the plurality of heads are not located on one cylinder, but it is easy to do so. Absent. The large relative position error between the engaging portion and the head means that the position of the head, for example, the top dead center position is shifted from the design position when the piston is incorporated in the swash plate compressor. Not desirable. In addition, after turning of the outer peripheral surface, a layer of a low friction material is formed on the outer peripheral surface, and when the final finishing of the low friction material layer is performed by centerless grinding, the outer periphery of the low friction material layer at a plurality of heads is formed. While the surface is located on one cylinder, the turning surface of the head is inclined with respect to the one cylinder, and the thickness of the low friction material layer differs depending on the location. If the thin part is worn, the piston can no longer be used and the life of the piston is shortened.

The present invention has been made in view of the above circumstances as an object to improve the efficiency of turning a piston material without lowering the processing accuracy. A method of manufacturing a piston for a plate compressor is 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 method for manufacturing a piston for a swash plate compressor, which engages with an outer peripheral portion of a swash plate via a shoe device and reciprocates in a cylinder bore as the swash plate rotates. Forming a center hole at both ends of the manufactured piston material, and engaging the pair of centers with the center holes by applying a first clamping force in a direction approaching each other to the pair of centers; A first turning step of turning the outer peripheral surface of the piston material in a state where the piston material is supported at the center of the piston material, and applying the second clamping force smaller than the first clamping force to the pair of centers. And a second turning step of turning the outer peripheral surface of the piston. In the second turning step, the axial clamping force of both centers is made smaller than that in the first turning step, so that the elastic bending of the piston material is reduced. If turning is performed on the outer peripheral surface in this state, a decrease in machining accuracy generated in the first turning step is reduced, and a piston with high machining accuracy can be obtained. Moreover, in the first turning step, since the clamping force in the axial direction is large, the turning can be performed efficiently by strictly setting the processing conditions, and a decrease in the processing efficiency can be avoided. (2) The method for manufacturing a piston for a swash plate compressor according to the above mode (1), wherein at least one of the cutting depth and the feed rate of the cutting tool in the second turning step is smaller than those in the first turning step. Claim 2). If the cutting amount or the feed rate of the cutting tool is reduced in the second turning step, the cutting resistance is reduced, so that the clamping force can be made smaller than in the first turning step, and the processing accuracy can be improved. (3) The piston material has a portion to be an engaging portion which is a portion to be engaged with the swash plate, and a portion to be a head to be fitted to the cylinder bore, and should be an engaging portion. The method of manufacturing a piston for a swash plate compressor according to the above mode (1) or (2), wherein the portion is eccentric with respect to a portion to be a head. (4) The swash plate type compressor piston is a single-headed piston having the head only on one side of the engagement portion, and the piston material is a plurality of single-headed piston materials connected in series. The method for producing a piston for a swash plate compressor according to item (3), wherein the piston is a multiple material. Because multiple materials become longer,
The amount of elastic deformation due to the axial clamping force is likely to increase. Therefore, when the present invention is applied to a multiple material, a great effect can be obtained as compared with the case where the present invention is applied to a non-multiple piston material. (5) The multiple material is a multiple material connected such that two portions to be the head are located at both ends and two portions to be the engaging portions are located at the center. A method for producing a piston for a swash plate type compressor according to item (4). (6) The portion where the multiple material is to be the engaging portion is 2
The swash plate type compressor according to the item (4), which is a multiple material that is located at both ends in the individual axial direction and is connected in such a manner that the part to be the head is located in the central part in the two axial directions. Manufacturing method of piston. (7) In the multiple material, the two heads are connected by a connecting shaft having a smaller diameter than the heads. (6)
13. The method for producing a piston for a swash plate type compressor according to item 13. (8) The portion to be the engaging portion includes a pair of arms extending parallel to each other, and a connecting portion connecting the base ends of the arms. (3) to (7). A method for manufacturing a piston for a swash plate type compressor according to any one of the above. (9) The method for manufacturing a piston for a swash plate compressor according to (8), wherein the portion to be the engaging portion includes a reinforcing rib that connects inner surfaces of the pair of arm portions and the connecting portion to each other. . Reinforcing ribs function to suppress large curvature when an axial clamping force is applied to the piston material,
It is unnecessary for a piston as a product. According to the present invention, it is possible to reduce the size of the reinforcing rib. (10) The method for manufacturing a piston for a swash plate compressor according to (8), wherein the portion to be the engagement portion includes a bridge portion that connects inner surfaces of the pair of arm portions. If the reinforcing rib is read as a bridge portion, the description relating to the item (9) also applies to this item as it is. (11) The piston material has at least a hollow head formed by integrally fixing a main body member having a bottomed cylindrical shape with one end opened and a closing member for closing the opening of the main body member. (1) or
(10) The method for producing a piston for a swash plate compressor according to any one of the above (10). (12) The piston material includes a pair of projecting portions projecting from both end surfaces in the axial direction, and the center hole is formed in the pair of projecting portions. The method for producing a piston for a swash plate type compressor according to any one of the first to third aspects. If a center hole is provided in the protruding portion, the center hole can be eliminated by removing the protruding portion later by cutting or the like. (13) The piston material is provided with a lug extending radially from the outer peripheral surface of the protrusion, and the piston material is rotated by engaging a rotational torque transmitting member with the lug. 12. The method for producing a swash plate compressor piston according to any one of the above 12). (14) The swash plate compressor piston according to any one of (1) to (13), wherein the first turning step is a roughing step and the second turning step is a finishing step. Production method. In the finishing step, the feed rate is set lower than in the roughing step in order to satisfy the requirement for the surface roughness, but the cut depth is also usually made smaller. Therefore, the cutting resistance is reduced, the clamping force in the finishing step can be made smaller than in the roughing step, and the processing accuracy can be improved. (15) The piston material is made of an aluminum alloy
The method for producing a piston for a swash plate compressor according to any one of (1) to (14).

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The manufacture of a piston for a swash plate type compressor used in a vehicle air conditioner according to an embodiment of the present invention will be described below in detail with reference to the drawings. 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). Rear housing 1
8 is attached via a valve plate 20.
The housing of the swash plate type compressor is constituted by the front housing 16, the rear housing 18, and the cylinder block 10. Rear housing 18 and valve plate 20
A suction chamber 22 and a discharge chamber 24 are formed between the two, and are connected to a refrigeration circuit (not shown) via a suction port 26 and a supply port 28, respectively. In the valve plate 20,
A suction hole 32, a suction valve 34, a discharge hole 36, a discharge valve 38 and the like are provided.

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
Is formed with a through hole 61 passing through the center line, and the rotating shaft 50 passes through the through hole 61. The inner diameter of the through-hole 61 is gradually increased in the up-down direction toward the opening side of both ends, and the cross-sectional shape of each end portion is an elongated hole. Rotation axis 50
Further, a rotary plate 62 as a rotation transmitting member is fixed thereto, and is engaged with the front housing 16 via a thrust bearing 64. The swash plate 60 is rotated integrally with the rotation shaft 50 by the hinge mechanism 66, and is allowed to tilt with movement in the axial direction. The hinge mechanism 66 includes a support arm 6 fixedly provided on the rotating plate 62.
And a guide pin 6 fixedly provided on the swash plate 60 and slidably fitted in a guide hole 68 of the support arm 67.
9, the through 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,
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 head provided integrally with the engaging portion 70 and fitted to the cylinder bore 12. Head 72. Engaging part 7
0 is engaged with the outer peripheral portion of the swash plate 60 via a pair of hemispherical shoes 76. A detailed description of the shape of the piston 14 will be given later.

The rotational motion of the swash plate 60 is converted into a reciprocating linear motion 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
The rotation restricting portion 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 rotating 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 in the swash plate chamber 86 and the pressure in the swash plate chamber 86 is adjusted, the inclination angle of the swash plate 60 is changed, the stroke of the piston 14 is changed, and the displacement of the compressor is adjusted. Specifically, the pressure of the swash plate chamber 86 is controlled by controlling the excitation and demagnetization of the capacity control valve 90 so that the swash plate chamber 86 is connected to or disconnected from the discharge chamber 24.

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. The engagement portion 70 of the piston 14 is generally U-shaped, and connects a pair of arms 108 and 110 extending in a direction perpendicular to the central axis of the head 72 to the base ends of the arms 108 and 110. And a connecting portion 112 to be connected. The extending ends of the arm portions 108 and 110 are located inside a cylindrical surface with the outer peripheral surface of the head 72 extended.
A concave portion 114 is formed on each of the side surfaces of the arm portions 108 and 110 facing each other. These recesses 114
Has a concave spherical surface, and two concave spherical surfaces are located on one spherical surface. The pair of shoes 76 are slidably held in the concave portion 114 at the spherical portion, contact the front and back surfaces of the outer peripheral portion of the swash plate 60 at the flat portion, and sandwich the outer peripheral portion of the swash plate 60 from both sides. These shoes 76 constitute a shoe device.

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 part 120 is formed integrally with the arm part 110 side of the engaging part 70 on the bottom wall opposite to the opening side.

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 provided with a main body member 162 and a cap 164 as a closing member. Body member 16
2 is an engaging portion forming portion 1 which is a portion to be the engaging portion 70.
66 and a bottomed cylindrical portion 170 opened in the opposite direction to the engagement portion forming portion 166. The main body member 162
The two bottomed cylindrical portions 170 are formed concentrically at both ends in the axial direction, and are integrally formed with the two engaging portion forming portions 166 located at the center. The piston material in the present embodiment is a double material which is one form of a multiple material. Rib 1 provided on engaging portion forming portion 166
76 connects the inner side surfaces of portions (hereinafter referred to as arm portions 178, 180, and connecting portion 182) that will later constitute the arm portions 108, 110 and the connecting portion 112, to prevent the pinching action during processing. This is to reinforce the engaging portion forming portion 166. It is a reinforcing rib that increases the rigidity of the main body member 162, and also has the purpose of minimizing distortion during heat treatment of the piston material 160. The arm 17
The extension ends of 8,180 are located inside the cylindrical surface where the outer peripheral surface of the bottomed cylindrical portion 170 is extended,
The engaging portion forming portion 166 is eccentric with respect to the center line of the bottomed cylindrical portion 170. The main body member 162 is made of an aluminum alloy, which is a kind of metal, and is manufactured by casting or forging.

The cap 164 has a stepped bottomed cylindrical shape, and can be fitted to the inner peripheral surface 192 of the main body member 162 at a fitting portion 190 having a smaller diameter than other portions. Cap 16
At the center of the end face 200 on the side opposite to the fitting part 190 side of No. 4, a projecting part 202 is provided so as to protrude. The protrusion 202
As shown in FIG. 4, the two ear portions 204 have a generally circular cross-sectional shape and extend in opposite directions from the outer peripheral surface thereof.
Are provided integrally. In the present embodiment, the cap 164 is made of an aluminum alloy, which is a kind of metal, and is manufactured by casting or forging, similarly to the main body member 162.

The fitting portion 190 side of the cap 164 serves as a tip, and is inserted into the opening of the bottomed cylindrical portion 170 in a coaxially positioned state, and the fitting portion 190 is fitted to the inner peripheral surface 192. . Opening end surface 206 of bottomed cylindrical portion 170
The bottomed cylindrical portion 170 and the cap 164 are welded or the like in a state where the fitting depth is defined by abutting the shoulder surface 208 extending outward in the radial direction from the fitting portion 190 of the cap 164. It is fixed by appropriate fixing means.

After the cap 164 is fixed to the main body member 162, a portion to be the head 72 (referred to as a head forming portion 210), that is, the bottomed cylindrical portion 17 of the main body member 162
Roughing and finishing are performed on the outer peripheral surface of 0 and the cap 164. The roughing is a step of cutting the material 160 (mainly the head forming part 210) into a shape close to the piston 14 as a product, and the finishing is a roughing processing of the material 160 (mainly the head forming part 210). ) Is a process of cutting to the nominal size in design, and the machining allowance is larger than in finish machining. Although machining is performed on portions other than the head forming portion 210, the description is omitted because it is not directly related to the present invention.

First, as shown in FIG. 2, a center hole 216 is formed at the center of the projection 202 provided on each of the two caps 164. Next, rough processing is performed on the outer peripheral surface of the head forming section 210. As shown in FIG. 3, a pair of centers 220 and 222 are brought close to each other and engaged with both center holes 216, and the material 160 is
It is supported from both sides while being centered by 222.
The pair of centers 220 and 222 may be movable in the axial direction together by a moving device (not shown). In the present embodiment, one center 220 is moved and the other center 222 is fixed. . In this roughing step, the centers 220 and 222 engage with the center hole 216,
The force for clamping the material 160 in the axial direction is referred to as a first clamping force. In the state where the centering is performed in this manner, the rotation torque transmitting member 226 of the rotation driving device (not shown) is brought close to one side surface of the ear portion 204 of the cap 164 as shown in FIG. Become. And
When the rotation driving device is activated, its rotation (indicated by an arrow in FIG. 4) is performed by the rotation torque transmitting member 226 and the ear 2.
Cap 164, main body member 1
62. And cutting tool 2 as cutting tool
By means of 30, roughing of the outer peripheral surface of the head forming section 210 is performed at a cutting amount and a feed speed suitable for the margin of the outer peripheral surface during roughing.

Subsequent to the roughing process, a finishing process is performed. In the finishing process, as described above, the machining allowance is smaller than in rough machining, the feed speed of the cutting tool is set smaller than in rough machining, and the cutting depth is set to be smaller. Therefore, since the cutting resistance at the time of finishing is reduced, the second clamping force as the axial clamping force of the material 160 by the centers 220 and 222 can be made smaller than the first clamping force at the time of roughing. As described above, the centers 220, 2
An eccentric compressive load is applied to the engaging portion forming portion 166 eccentric to the head forming portion 210 by the axial clamping force of 22, and the material 160 is bent to the connecting portion 182 side by elastic deformation. However, the curvature is smaller during finish machining than during rough machining. Therefore, roughing,
The amount of deformation in the radial direction of the head forming part 210 in the state where the first and second clamping forces after the finishing processing are released (the head forming part 2
As shown in FIG. 5, the inclination of the outer peripheral surface of the outer peripheral surface 10 with respect to the center axis defined by the two center holes 216 is smaller in the finish machining than in the rough machining, and the variation in the deformation amount is also small in the rough machining. The finish processing is smaller than the time, and the finish processing can be performed with high accuracy.

After the roughing and finishing processes, at least the outer peripheral surface of the head forming portion 210 is coated, and a coating layer mainly composed of, for example, polytetrafluoroethylene is formed. Then, the protruding portion 202 of the cap 164
Is removed and the end face 200 is cut,
Centerless grinding is performed on the outer peripheral surface of the head forming portion 210 on which the coating layer is formed, and the head 72 is completed. Subsequently, machining is applied to the engagement portion forming portions 166, respectively.
Recess 1 that holds shoe 76 when it becomes piston 14
14 (shown by a two-dot chain line in FIG. 2)
Is completed. Finally, in the separation step, the material 160 is cut into two, and two pistons 14 are obtained.

In the present embodiment, the roughing step and the finishing step constitute a first turning step and a second turning step, respectively. According to the present embodiment, in the roughing process, the clamping force is increased to make the processing conditions relatively strict (increase the depth of cut and the feed rate), and to perform the roughing with a larger allowance than the finishing. Also, in the finishing process in which the machining allowance is smaller than the rough machining, the head forming portion 210 is held with a smaller clamping force than in the rough machining, and the machining is performed by reducing the cut amount and the feed speed. Both the magnitude and the variation in the amount of deformation of the outer peripheral surface of the later head forming part 210 can be reduced, and a finishing process with high dimensional accuracy can be performed.

Further, since the outer peripheral surface of the head forming portion 210 is finished with a high precision, the thickness of the head can be properly adjusted without unevenness in local thickness in the coating process after the roughing and finishing processes. Is formed, the piston 14 is smoothly reciprocated during use, and the wear resistance of the piston 14 and the durability of the compressor are improved.

In this embodiment, the arm 178,
Although a reinforcing rib for connecting the inner surfaces of the arm 180 and the connecting portion 182 to each other is provided, instead of this, as shown in FIG. 6, a bridge 240 for connecting the inner surfaces of the arms 178 and 180 may also be provided. Good.

The material 160 for manufacturing a single-headed piston in the embodiment shown in FIGS. 1 to 4 is a double material in which parts to be engaged are connected to each other. It is also possible to use a piston material in which parts to be connected are connected. One embodiment is shown in FIG. The material 300 for manufacturing a single-headed piston shown in FIG.
And a cap 304 as two closing members for closing the openings of the main body member 302. The two caps 304 are connected to each other by a connecting shaft 308 smaller in diameter than the other portions so as to be concentric with each other, and are integrally formed. Two caps 304 are fixed in a state where the opening of the bottomed cylindrical portion 310 of the main body member 302 is closed, and the bottomed cylindrical portion 310 and the cap 304 form a head that is to be a hollow head. A part 314 is formed. The engaging portion forming portion 318, which is to be the engaging portion of the main body member 302, has a generally trapezoidal cross-sectional shape, is eccentric with respect to the central axis of the head forming portion 314, and has a trapezoidal bottom portion. It is provided so as to be on the outer peripheral side. Therefore, also in this case, when the material 300 is clamped in the roughing process and the finishing process, the material 300 is bent by elastic deformation. The engaging part forming part 318 includes the head forming part 3
At the end surface 320 opposite to the 14 side, the head forming portion 3
14 at positions corresponding to the central axis of
Protruding portion 322 and ear portion 3 having the same configuration as ear portion 204
24 are provided. Similarly to the above embodiment, after a center hole (not shown) is formed at the center of the protruding portion 322, the axial clamping force is changed to large and small on the outer peripheral surface of the head forming portion 314 and the like, respectively. Roughing and finishing are performed. Then, as shown by a two-dot chain line in FIG. 7, a groove 330 is formed by a cutting tool leaving a bottom wall substantially at the center in the axial direction of the engaging portion forming portion 318, so that a pair of arm portions 332 and An engagement portion including a connection portion 334 that connects the base ends of the arm portions 332 and 334 to each other is formed.

In addition to the above embodiments, a double material in which a portion to be a head and a portion to be an engagement portion may be connected, or three or more single-headed piston manufacturing materials may be connected in series. It is also possible to use linked multiple materials. The present invention is suitable for a multiple material including a double material that is long in the axial direction as in each of the above-described embodiments. It is also applicable to a piston material for one piston provided one by one. In the case of a single piston material, the length in the axial direction is generally shorter than that of the double material. However, in many cases, the engaging portion does not include a reinforcing rib or a bridge portion. Further, the present invention is effective because the material is easily bent by elastic deformation during clamping.
FIG. 8 shows an embodiment thereof. In the present embodiment,
An end surface 404 on the head forming portion 402 side which is a portion to be a hollow head of the single-head piston manufacturing material 400 and an end surface 408 on an engaging portion forming portion 406 side which is a portion to be an engaging portion.
Are integrally provided with a pair of protrusions 414 each having an ear 412. The engaging portion forming portion 406 includes a pair of arms 420 and 422 extending in a direction orthogonal to the axial direction of the head forming portion 402, and a connecting portion 424 connecting the base ends of the arms 420 and 422. , Are provided eccentrically with respect to the axis of the head forming portion 402. The protruding portions 414 are provided at positions corresponding to the central axis of the head forming portion 402, respectively. These protrusions 414
A center hole (not shown) is formed in the head forming portion 406 in the same manner as in each of the above-described embodiments in a state where the center having the same configuration as the centers 220 and 222 is fitted into the center holes. Roughing and finishing are performed on the outer peripheral surface by changing the axial clamping force to large and small, respectively.

At least one of the main body 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 main body 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 closing member may be manufactured by machining a general-purpose material such as a commercially available bar, as long as it is a simple shape such as a disk.

The piston 14 may have a form in which a closing member and an engaging portion are integrally formed, and an opening of a bottomed cylindrical member constituting a main part of the head is closed by the closing member. May be divided at the axial center portion of the head and have a side provided with the engaging portion and a side not provided with the engaging portion.

The present invention can be applied to a single-headed piston for a fixed displacement type swash plate type compressor or a double-headed piston having heads on both sides of an engaging portion with a swash plate.

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 piston manufactured by a method for manufacturing a piston for a swash plate type compressor according to an embodiment of the present invention.

FIG. 2 is a front view (partial cross section) showing a piston material for manufacturing the piston.

FIG. 3 is a front view (partial cross section) illustrating a first turning step and a second turning step of the manufacturing method.

FIG. 4 is a side view showing the piston material together with a rotational torque transmitting member.

FIG. 5 is a graph showing experimental results for confirming the effectiveness of the present invention.

FIG. 6 is a front view (partial cross section) showing a piston material in a method for manufacturing a swash plate type compressor piston according to another embodiment of the present invention.

FIG. 7 is a front view showing a piston material in a method of manufacturing a piston for a swash plate type compressor according to still another embodiment of the present invention.

FIG. 8 is a front view showing a piston material in a method of manufacturing a piston for a swash plate type compressor according to still another embodiment of the present invention.

[Explanation of symbols]

12: Cylinder bore 14: Single head piston 60:
Swash plate 70: engaging part 72: head part 76: shoe 108, 110: arm part 112: connecting part 120: bottomed cylindrical part
122: Cap 160: Single head piston manufacturing material 162: Body member 164: Cap 16
6: engaging portion forming portion 170: bottomed cylindrical portion 176: rib 178, 1
80: arm part 182: connecting part 202: projecting part 204: ear
210: head forming part 216: center hole 220, 222: center 22
6: rotational torque transmitting member 230: cutting tool 24
0: Bridge portion 300, 400: Single head piston manufacturing material 302: Body member 304: Cap
308: connecting shaft 310: bottomed cylindrical portion 314, 402: head forming portion 318, 406: engaging portion forming portion 322, 41
4: Projecting parts 324, 412: Ear parts 332, 33
4,420,422: arm part 336,424: connecting part

Claims (2)

[Claims] 1. A method of manufacturing a piston for a swash plate type compressor, which engages with an outer peripheral portion of a swash plate via a shoe device and reciprocates in a cylinder bore as the swash plate rotates, wherein the piston is manufactured by forging or casting. Forming a center hole at both ends of the piston material, and engaging a pair of centers in the center holes by applying a first clamping force in a direction approaching the pair of centers to thereby form the pair of centers. A first turning step of turning the outer peripheral surface of the piston material in a state where the piston material is supported at the center, and applying a second clamping force smaller than the first clamping force to the pair of centers; A method for producing a piston for a swash plate type compressor, comprising: a second turning step of turning an outer peripheral surface. 2. The method of manufacturing a piston for a swash plate compressor according to claim 1, wherein at least one of a cutting amount and a feed rate of the cutting tool in the second turning step is smaller than those in the first turning step. .