JPH01162534A - Cold forging method for shoe for swash plate type compressor - Google Patents

Abstract

PURPOSE:To compress without sliding a blank and to cold-forging the shoe of excellent accuracy and surface roughness by compressing the spherical blank of less than the radius of curvature of the shoe by pressurizing it by the lower side die of the semi-spherical recessed part corresponding to the shoe spherical face and the upper side die forming the swash plate and sliding face of the shoe. CONSTITUTION:When an upper side die 20 is descended by the descent of a ram, the lower side die 13 having been floated by an elastic body 14 is descended to specified position by pushing a spherical blank 23 by the upper side die 20 to attain the state of strongly interposing the blank 23 between the tip of a knockout punch 16, the lower side die 13 and upper side die 20. The deformation of the blank 23 is progressed toward the upper part from the lower face of the semispherical inner wall 15 of the lower side die 13 in order from the knockout punch tip 17 and the deformation is progressed in the direction spreading in the radial direction from the center part of the sliding face 26 with the swash plate of the upper die 20. The forged shoe 29 is drawn out of the lower side die 13 by the knockout punch 16. The reason why the spherical blank 23 is made less than the radius of curvature of the shoe is because of forging without causing sliding between the blank 23 and lower die 13.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for cold forging a shoe for a swash plate compressor.

(Prior Art and Problems) As shown in FIG. 5, a swash plate compressor generally consists of a shoe 4 disposed within a shilling block l, and a piston 5 that straddles the swash plate 3 and is moored by the shoe 4. .

The rotational motion of the swash plate, which rotates with the rotating shaft, is converted into reciprocating motion of the piston by the shoe. With this structure, the medium to be compressed, such as refrigerant gas, which has been circulating through the refrigeration circuit, is compressed to high pressure within the cylinder bore 6 by the piston 5, and sent out to the refrigeration cycle circuit again.

The shoe in such a swash plate compressor is enlarged to form the sixth shoe.
As shown in the figure. In the figure, 48 is a hemispherical portion that comes into sliding contact with the piston, and 4b is a sliding surface that comes into contact with the swash plate. As a manufacturing method for such a shoe having a hemispherical portion, manufacturing by cold forging is known, and is disclosed in Japanese Patent Application Laid-Open No. 56-136.
No. 249 and Japanese Unexamined Patent Publication No. 139248/1983.

In the former case, as shown in the manufacturing process order in FIG.
A conical portion 4d of a predetermined size is provided around c, and then an upper mold 9 having an inner wall surface lO of a predetermined hemispherical shape and a lower mold 1 of a predetermined shape are formed.
This is a forging method using 1. In the latter case, as shown in the forging process order in FIG. 8, a hole 12 is formed in the end surface 4c of the cylindrical forging material 4' on the side that is to be the hemispherical part of the shoe, and then the inner part of the hemispherical part is formed into a predetermined hemispherical part. Upper mold 9 having wall surface lO
and a lower die 11 of a predetermined shape to form the opening side 4 of the hole 12.
This is a forging method in which a hemispherical portion 4a is formed by reducing the diameter of the outer peripheral portion of a cylindrical forging material 4'.

The former method involves closed forging, which requires a large forging load and has a short mold life, so it is not a practical method.

The latter method does not allow forging to be completely hermetically sealed due to the holes 12 formed in the end face, and has the advantage that the forging load can be lower than the former method.

However, in both the former and latter methods, when forming a hemispherical portion, the deformation progresses in the direction in which the upper end of the forging material is reduced in diameter, which causes slippage between the forging material and the inner wall of the hemispherical portion of the die.

Therefore, in terms of forging, it has the following drawbacks.

■ Seizing is likely to occur between the goo and the forging material.

■Large forging load is required.

■The life of the die is short due to the reasons mentioned above (■) and 9.

In order to prevent seizure between the forging material and the die and to reduce the forging load, it is necessary to lubricate the forging material. However, the lubrication process introduces the following new problems.

■Due to the presence of a lubricating film, it is difficult for the forging material to follow the shape of the inner wall of the die, resulting in variations in dimensional accuracy.

■As it gradually accumulates on the inner wall surface of the die, the dimensional accuracy and surface roughness of the mold deteriorate. Also, it is necessary to clean the die at regular intervals.

■Dimension accuracy varies due to variations in lubrication process.

■During heat treatment in the post-process, the surface becomes rough due to metallurgical reaction between the lubricating film and the base. To prevent this, it is necessary to remove the lubricating film after forging.

Shoes obtained by such a method have poor dimensional accuracy and surface roughness of the hemispherical portion, and therefore tend to cause problems when incorporated into a compressor.

■If the dimensional accuracy of the hemispherical part is poor, the reshu will not be able to smoothly move due to poor contact with the sliding piston pocket and locally high surface pressure, resulting in loss of compressor power. It also wears out the piston pockets, increases the clearance between the shoes and the swash plate, and increases compressor noise.

■If the surface roughness of the hemispherical part is poor, the pocket part of the aluminum alloy piston in sliding contact will wear out and the noise of the compressor will increase.

In order to alleviate such problems, an example is used in which a chemical conversion coating is applied to the hemispherical part, and a resin coating containing a solid lubricant dispersed thereon is used (for example, in
7-146070@I), but it is not a complete countermeasure, and on the contrary, it increases the number of steps and increases the cost.

For this reason, there has been a need for a method of manufacturing the hemispherical portion of the shoe with high precision and good surface roughness.

(Object of the Invention) The present invention has been made for the purpose of overcoming the problems of the shoe produced by the conventional forging method described above.

More specifically, it is an object of the present invention to provide a method for cold forging shoes for a swash plate compressor, in which a shoe with excellent dimensional accuracy and surface roughness can be obtained in one forging process even though the shoe is manufactured by cold forging. It is.

(Means for solving problems) The present invention consists of the following configuration.

The first step is to prepare a spherical forging material having a radius less than or equal to the radius of curvature of the shoe, and a lower die having a substantially hemispherical recess corresponding to the spherical surface of the shoe and a knockout punch at the center of the bottom. a second step of loading the forging material into the recess, the forging being loaded into the recess by an upper die that is provided opposite to the lower die and forms a sliding surface side with the swash plate of the shoe; It consists of a third step of pressurizing and compressing the raw material and plastically deforming it into a molded body, and a fourth step of extruding the molded body using the knockout punch. Then, the forging material is loaded with the tip of the knockout punch at the center of the bottom of the recess of the lower die recessed from the bottom of the recess, and in the process of pressurizing and compressing the forging material, the knockout punch It is preferable that the forging is performed so that the tip slightly protrudes from the bottom surface of the recess, and the mold surfaces of the portions close to the end surfaces of the upper die and the lower die are formed in the final process of pressure compression. Preferably, the forging process is completed without contacting the forging material, leaving a small gap between them.

This will be explained in more detail below.

In the first forging step, the forging material is made into a ball having a smaller diameter than the diameter of the hemispherical portion of the die. The balls must be annealed to improve forgeability.

In the second forging process, a die set having the following characteristics is used.

The structure of the die set is that the lower die with a hole for the knockout punch in the center is floated elastically, and the upper surface of the knockout punch is located lower than the bottom surface of the lower die, and the upper die of the lower die is A relief portion is provided on the die inner wall above a position that passes through the center point of the shoe ball portion and is parallel to the upper surface of the lower die. The upper die is provided with a surface in sliding contact with the swash plate of the shoe and an inclined surface starting from the surface in sliding contact with the swash plate,
Furthermore, a relief portion is provided to prevent the forging shoe from coming into contact with the upper die even during the final compression process.

With the configuration of the die set as described above, the forging process is as follows. A die with a hole for a knockout punch in the center is floated elastically, and the ball of the forging material is transferred into the lower die with the top surface of the knockout punch positioned lower than the bottom of the lower die. Then, the ball is centripetally positioned at the center of the bottom of the lower die.

In the third forging process, the ball is sandwiched between the knockout punch and the upper die while being lowered to a predetermined position through the forging material by lowering of either the lower die or the upper die which are elastically floated.

If the ball is inside the die, the ball is pressed sequentially from the knockout punch to the bottom of the hemispherical inner wall of the lower die, and then to the top to progress the deformation, and if it is outside the die, the ball is pressed to the center of the upper die. The deformation progresses while being pressed in a direction that spreads radially from the part.

Between the forging shoe and the lower die, a gap is left in the relief section provided on the inner wall of the die above a position that passes through the center point of the ball of the shoe and is parallel to the upper surface of the lower die.

Furthermore, between the forging shoe and the upper die, the forging is completed with a gap left in the relief section provided between the sloped surface starting from the plane where the shoe of the upper die slides into contact with the swash plate and the end face of the upper die. .

In the fourth forging step, the forged shoe is pushed out using a knockout punch.

It should be noted that if the shape of the shoe is such that a bottomed recess is provided at the center of the sliding surface with the swash plate, the contact surface pressure at the center will be alleviated. The volume of the recess needs to be large in order to serve as an oil sump. For any purpose, an appropriate range is for the square of the diameter of the recess to be 10 to 40% of the square of the outer diameter of the surface that makes sliding contact with the swash plate. Further, this recess may be provided by machining after forging, or may be formed as a through hole by drilling.

(Function) In the first forging process, the reason why the forging material is made into a ball with a smaller diameter than the diameter of the hemispherical part of the die is that during forging, the ball-shaped forging material is pressed against the hemispherical inner wall sequentially from the bottom surface of the lower die. As deformation progresses, the forging material can be forged with almost no slippage between the inner wall of the hemispherical part of the lower die, making it unnecessary to apply a lubricating film to the forging material, which is different from the conventional forging method. This eliminates the negative effect on dimensional accuracy and surface roughness caused by the lubricating film, which was a problem in the previous model. That is.

Since it is not necessary to apply a lubricating film to the forging material, a shoe with high dimensional accuracy and good surface roughness can be easily obtained.

Furthermore, unlike the conventional method, the method is not a diameter-reducing rope forming method that involves slipping, so the load required for forging is small, and the press is also small, making it economical. Furthermore, the die life is extended due to low forging loads and non-slip deformation. In addition, since there is no lubricant attached to the die, it is easy to manage the die during forging.

Balls used as a material for forging can be easily obtained with uniform outer diameter and extremely good surface roughness through the manufacturing process of balls for ball bearings. In the case of ball bearings, for the purpose of use according to the quenching and quenching invention, the ball bearings may be used in a state before quenching and tempering, or balls that have been further finished after quenching and tempering may be annealed and used6. In order to obtain a good shoe surface roughness, the surface roughness of the ball as a forging material should be RmaxO04μ.
Rmax is good, and the most preferable is Rmax 0.
．． It is 15 μm or less.

In the second forging process, the lower die with a hole for the knockout punch in the center is floated elastically, and the top surface of the knockout punch is positioned lower than the bottom of the lower die. When the ball of the forging material is transferred into the lower die, the ball is centripetally positioned at the center of the bottom surface of the lower die.

For this reason, deformation can be performed uniformly.

The lower die or the upper die, which had been floated elastically, is lowered to a predetermined position via the forging material, creating a state in which the ball is sandwiched between the knockout punch and the upper die. Therefore, the position of the ball does not deviate from the center of the lower die.

When the ball-shaped forging material is in the lower die, the ball diameter is smaller than the diameter of the hemispherical part of the lower die, so the ball is sequentially directed from the bottom to the top of the hemispherical inner wall of the lower die from the knockout punch. deformation progresses as it is pressed.

Therefore, deformation can proceed without slipping between the inner wall of the hemispherical part of the lower die and the ball, so there is no need to lubricate the ball, and the ball-shaped forging material does not need to be placed outside the die. , which spreads in the radial direction from the center of the upper die.Since the deformation progresses as it is pressed with almost no burrs, no lubrication treatment is required on this surface as well.

At the upper part of the lower die, the forging material has a gap in the relief part provided on the die inner wall above a position that passes through the center point of the shoe bulb and is parallel to the upper surface of the die, and furthermore, the shoe of the upper die is connected to the swash plate. Forging is completed with a gap formed between the inclined surface starting from the plane in sliding contact with the upper die end surface and the relief section provided between the upper die end surface. Since this is the final compression step, a closed forging condition does not occur, and a shoe of a predetermined shape can be easily formed with a low forging load. Further, by providing a relief part, it is possible to provide a radius to the ends of both the lower die and the upper die, thereby making it possible to lengthen the life of each die.

In the fourth step of the forging process, the compressed shoe is released from the die using a knockout punch, so the balls can be easily separated from the die and transported out of the die set using compressed air at high speed, resulting in high productivity. can do.

The forging method described above and the shoe obtained thereby can solve the problems in manufacturing a hemispherical shoe by conventional forging and the problems of the hemispherical part that occur during use.

Note that, after the shoe manufactured through such a process is quenched and tempered, the sliding surface with the swash plate is finished. Furthermore, a hard coating with a thickness of 2 to 10 μm containing chromium or titanium nitride or each nitride is provided on the sliding surface of the shoe with the swash plate using the ion-blating method, and ceramic particles are added to the nickel-based base. 2 to 1 dispersed
By providing a plating film with a thickness of 0 μm, a shoe with excellent seizure resistance and durability can be obtained.

Further, after these treatments are performed first, gas nitriding treatment or quenching and tempering treatment can be performed to obtain a shoe with improved adhesion between the respective coatings.

The material of the shoe is not limited to iron-based materials; if the swash plate to which it slides is made of iron-based material, it may not be made of aluminum alloy but may be coated with a thin plating layer on the hemispherical part of the shoe as described above. It is best to provide an ion blasting film.

(Example) Examples of the present invention will be described below.

FIG. 1 shows a die set structure used in the forging process of the present invention. The lower die 13 is suspended in a predetermined position by an elastic body (urethane rubber) 14, and an inner wall surface 1 having a hemispherical shape of a shoe is provided at the center of the lower die 13.
5 are provided.

At the center of the lower part is the tip 17 of the knockout punch 16.
is located below the bottom surface IB of the inner wall surface. Further, the lower die 13 is positioned by a guide pin 19. The upper die 20 is fixed to the die plate 22 by a guide post 21 and a die holder 21' so as to be coaxial with the lower die 13.

Figure 2 (a), (b), (c), (d), and (e) illustrate the forging process in the order of (a), (b), (c), (d), and (e). This is what I did. In the figure, 23 is a ball-shaped forged material having a diameter smaller than the average diameter of the hemispherical part of the lower die. The ball is made of high carbon bearing steel (SUJ-2) with a diameter of 14.
2875mm, surface roughness Rrnax 0.05~0
．． A 15 μm thick one was used.

First, FIG. 2(a) will be explained. The lower die 13 has a hemispherical inner wall surface 15 that has a predetermined hemispherical dimension in consideration of deformation due to heat treatment of the shoe after forging and elastic deformation of the die, and the upper portion thereof A relief portion 24 is provided for the purpose of preventing closed forging in the final compression process. In addition, a part A 25 for the knockout punch 16 is provided at the center of the bottom of the lower die 13, and the lower die is inserted so that the tip 17 of the knockout punch 16 is at a lower level than the lower surface 18 of the hemispherical inner wall surface 15. 13 is in a state of being floated by an elastic body 14. In this state, the ball 23 of the forging material is transferred into the lower die 13. The ball 23 is necessarily positioned at the center of the lower die by centripetal action. FIG. 2(b) shows the initial state of the compression process, in which the upper die 20 is lowered by the lowering of the upper ram of the forging press (not shown), but the lower die 13, which had been elastically floated at that time, is lowered. When the upper die 20 pushes the ball 23, it is lowered to a predetermined position, and the ball 23 is strongly sandwiched between the tip 17 of the knockout punch 16 and the upper die 20 of the lower die.
FIG. 2(c) shows that the ball 23 is deformed in the lower die 13 when it is pressed sequentially from the knockout punch tip 17 upward from the lower surface 18 of the hemispherical inner wall 15 of the lower die 13. When the ball 23 is advanced and outside the lower die 13, the deformation progresses while pressing the ball 23 in a direction expanding in the radial direction from the center of the sliding surface 26 with the swash plate of the upper die 2°0.

Figure 2(d) shows the state in the final compression process;
d') is an enlarged view of part A, and between the shoe 29 forged from a ball and the lower die 13, there is a part below the upper part that passes through the center point 30 of the ball of the shoe and is parallel to the upper surface 31 of the lower die. A gap 32 is left in the relief part 24 provided on the inner wall of the side die,
Further, between the forging shoe 29 and the upper die 20, a gap 3 is formed in a relief portion 28 provided between an inclined surface 27 starting from the plane 26 where the shoe slides on the swash plate and an upper die end surface 33.
Finish forging with 4 remaining. As shown in FIG. 3(a), the recess 35 of the shoe is formed by the knockout punch.
This is to reduce mutual wear between the piston pocket and the piston pocket.

Figure 2(e) shows the forged shoe 2 after completing the final compression process.
9, the shoe 29 is pulled out from the lower die 13 by raising the knockout pin 115' using the knockout punch 16, and is transported out of the die set by compressed air.

Sample-A: 2000 balls were continuously forged using the die set described above, and then quenched and tempered, and treated with a vibrating barrel polisher for 5 minutes with smooth abrasive grains for finishing.
Furthermore, after the sliding surface with the swash plate was lapped with a grindstone, a plating layer containing silicon nitride dispersed in a nickel-phosphorus base was provided on the sliding surface with the swash plate. The thickness of the dispersed plating layer finished by puff polishing was 7 μm. The thus obtained shoe is shown in FIG. 3(a) and FIG. 3(b) which is an enlarged view of part B. In FIG. 35 is molded by the tip 17 of the knockout punch, and the part 36 connected thereto is the hemispherical inner wall 1 of the lower die 13 used for forging.
The radius r of the hemispherical part 37, which is molded by the lower surface 18 of 5 and comes into sliding contact with the piston pocket, is φD (10,6
The sphere radius is 7.93 between mm) and φd (6,2 mm).
1 in the range of 00 to 7.9325 mm. This was the size we aimed for in the design. Further, the surface roughness of the hemispherical portion 37 and the free curved surface 38 formed without contacting the lower die at the relief portion 24 provided on the die, and also at 36 portions was Rmax 0.3 μm or less. Further, in the figure, 41 is the sliding surface with the swash plate, and the plating layer 41' is also provided on the other sloped parts 40 of the sliding surface 41 with the swash plate, and the hardness of the coating is HmV8oO~900. Ta. The part 39 in the figure is the relief part 2B provided in the upper die 20.
It is a free surface formed without touching the surface.

Sample-B The sliding surface of the shoes obtained by forging 2000 of the same balls in the same way with the swash plate was lapped with a grindstone, then puff-polished, ultrasonically cleaned in a fluorocarbon solution, and the swash plate was polished using an arc ion brating device The sliding surface is made of chromium, Cr, and N and has a thickness of 4μ.
A shoe provided with a hard coating of 1.0 m was quenched and tempered, and then treated with a vibrating barrel polisher for 5 minutes with smooth abrasive grains for finishing, and the sliding surface was further puff-polished to produce a shoe. The cross-sectional state of the completed shoe is shown in FIG. 4 and FIG. 4(b), which is an enlarged view of part 0.

The sliding surface 42 of this shoe with the swash plate has a diameter of 12 mm, and the opening in the center has a diameter of 6 mm and a depth of 0.
A recess 43 of 2 mm is provided. This recess 43 is molded by making the center part of the upper die convex. 42' in Figure 0 indicates an ion blasting film, which is used as a base of 5UJ-2 and diffused to maintain heating before quenching. are combined. The hardness of the film is HmV1100-1200
Met. In the figure, φD (10,6 mm) and φd (6,
2mm) and a sphere radius of 7.9300 to 7.9325m.
It was in the range of m. In addition, the surface roughness of the hemispherical portion 37 and the free curved surface 38 formed without contacting the die at the relief portion 24 provided on the die and the 36 other portions is Rmax 0.
．． It was 2 μm or less.

For comparison, we used the same die set to forge a bonded ball, and as a result, lubricant adhered to the lower die.
The surface of the hemispherical part of the shoe had irregularities that were visible to the naked eye. In addition, the ball is vibrated in molybdenum disulfide powder to form an extremely thin coating layer (less than 1 μm) on the ball surface, and as a result of forging this, a shoe with extremely good dimensional accuracy and surface roughness is obtained at the initial stage. However, after continuous forging in large quantities, lubricant adhered to the re-die and the surface of the shoe tended to become rough. However, the results were very good compared to those subjected to bonding treatment. In addition, the surface of the hemispherical part after heat treatment after forging has a strong tendency to become rough compared to those manufactured without lubrication.This is due to the chemical reaction between molybdenum disulfide and the matrix. It can be significantly reduced by heat treatment during the post-barrel process.

JP-A-56-139248 and JP-A-56-136
With reference to Publication No. 249, we conducted a comparative test on various cylindrical forging materials with the same volume as the ball used in the present invention, and found that if the forging material was forged without lubrication, it would slip between it and the die and seize. occurred. In addition, by vibrating a cylindrical forged material in molybdenum disulfide powder to form an extremely thin coating layer (less than 1 μm) on the surface, the result of forging was better than that without lubrication, but seizure still occurred. .

The shoes of Sample-8 and Sample-B above have a bore diameter of 36 mm.
It was installed in a 6-cylinder swash plate compressor, and was subjected to repeated low-speed, high-load durability tests, high-speed, high-load durability tests, durability tests with too little refrigerant, and repeated start-up tests under liquid compression conditions.In all cases, the hemisphere of the shoe The wear between the piston and the pocket of the aluminum alloy piston was at a level that caused no problems.

Further, no seizure or wear occurred between the swash plate made of a hypereutectic Si aluminum alloy material and the sliding portion of the shoe.

(Effects of the Invention) As described above, according to the present invention, a ball that can be obtained or produced at low cost is used as a forging material, and deformation can proceed without the material ball slipping from the lower die or the upper die. Because of this structure, the balls do not require lubrication, and therefore shoes with high dimensional accuracy and excellent surface roughness can be produced cold with low forging loads, and the life of the lower die is also long. The manufacturing effect that can be achieved is obtained. In addition, when the shoe obtained by the present invention is incorporated into a compressor and used, the hemispherical part has high dimensional accuracy and good surface roughness, so it makes good contact with the pocket part of the mating piston, resulting in less power loss. Also, the piston pocket will not be worn out.

[Brief explanation of the drawing]

1 to 4 (a) and (b) are diagrams showing an embodiment of the present invention, and FIGS. 5 to 8 are diagrams showing a conventional example. Figure 1 is a sectional view showing the die set, Figure 2 (a),
Figure (b), Figure 2 (C), Figure 2 (d), Figure 2 (e)
is a sectional view of the main part showing the order of the forging process, and FIG. 2(d')
is an enlarged sectional view of section A in FIG. 2(d). Figure 3 (a
) is a sectional view showing a shoe provided with a plating layer;
FIG. 3(b) is an enlarged sectional view of section B in FIG. 3(a). FIG. 4(a) is a sectional view showing a shoe provided with an ion-blating film layer, and FIG. 4(b) is an enlarged sectional view of part 0 of FIG. 4(a). FIG. 5 is a sectional view of a swash plate compressor, and FIG. 6 is a sectional view of a conventional shoe. FIGS. 7 and 8 are sectional views of essential parts showing the order of the forging process for a conventional shoe. In the figure, 713... Lower die, 15... Hemispherical inner wall, 1
6... Knockout punch, 20... Upper die, 2
3... Forging material, 24... Relief part near the end face of the lower die, 26... Sliding surface with the swash plate, 28... Relief part near the end face of the upper die.

Claims (1)

[Claims] 1. A first step of preparing a spherical forging material having a radius less than or equal to the radius of curvature of the shoe, which has a substantially hemispherical recess corresponding to the spherical portion of the shoe, and has a knockout at the center of the bottom. A second step of loading the forging material into the recess of the lower die equipped with a punch, using an upper die that is provided opposite to the lower die and forms a sliding surface side with the swash plate of the shoe. A swash plate compression method comprising: a third step of pressurizing and compressing the forging material loaded into the recess to plastically deform it into a molded body; and a fourth step of extruding the molded body with the knockout punch. Cold forging method for machine shoes. 2. The forging material is loaded with the tip of the knockout punch at the center of the bottom of the recess of the lower die recessed from the bottom surface of the recess, and in the process of pressurizing and compressing the forging material, the knockout punch is 2. The method for cold forging a shoe for a swash plate compressor according to item 1, wherein the shoe is forged so that the tip slightly protrudes from the bottom surface of the recess. 3. The forging process is completed with the mold surfaces of the upper die and the lower die near the end faces not contacting the forging material during the final process of pressure compression, leaving a slight gap between them. A method for cold forging a shoe for a swash plate compressor according to item 1 or 2 above.