JP2018158346A - Auto-frettage processing device, and auto-frettage processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an auto-frettage processing device capable of processing a workpiece with high accuracy for a short time.SOLUTION: An auto-frettage processing device 1 includes: a cylinder part 20; and a piston part 30. The cylinder part 20 has a communication hole 23 which is provided in a top direction of a workpiece 10 and can communicate with the inside of the workpiece 10; and a communication space 222 which is formed so as to communicate with the inside of the workpiece 10 though the communication hole 23 and can store oil. In the piston part 30, when a holder 32 of the piston part 30 is moved to brought into contact with a contact surface 225 formed in the periphery of the communication hole 23, a pressurizing pin 31 of the piston part 30 pressure-feeds oil of the communication space 222 into the inside of the workpiece 10. When the holder 32 is brought into contact with the contact surface 225, a trap space 220 capable of recovering air having a smaller specific gravity than that of oil is formed between an inner wall surface 226 outside of a radial direction of the contact surface 225 of the cylinder part 22 and a second inclined plane 322 of the holder 32.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an auto-frettage processing apparatus and an auto-frettage processing method.

  2. Description of the Related Art Conventionally, an autofrettage processing apparatus that processes a workpiece using the pressure of a fluid introduced into a hollow workpiece is known. In the auto-frettage processing apparatus, by pressurizing the fluid in the workpiece, the pressure of the pressure is applied to the inner wall of the workpiece, and the inner wall of the workpiece is plastically deformed. For example, Patent Document 1 describes an autofrettage processing apparatus including a piston that can be inserted into a work and can pressurize a fluid introduced into the work in the work.

Special table 2010-510385 gazette

  However, in the autofrettage processing apparatus described in Patent Document 1, if air is mixed in the fluid in the workpiece, the air is compressed when the fluid in the workpiece is pressurized by the piston. Cannot pressurize to desired pressure. For this reason, there is a possibility that desired processing cannot be performed on the workpiece. In addition, when a step of extracting air from the fluid introduced into the workpiece is added, the time for processing the workpiece becomes relatively long.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an autofrettage processing apparatus capable of processing a workpiece in a short time with high accuracy.

The autofrettage processing apparatus of the present invention includes a communication space forming part (20), pistons (31, 32), and an acting force generating part (45), and is used for fluid introduced into a hollow work (10). The workpiece is machined using pressure.
The communication space forming portion is located in the top direction or the ground direction of the work, and is a communication hole (23) that can communicate with the work, and a communication that is formed so as to be able to communicate with the work through the communication hole and can store fluid. It has a space (222).
The piston is provided in the communication space so as to be movable relative to the communication space forming portion. When the piston moves so as to contact the contact surface (225) formed around the communication space side of the communication hole, the fluid in the communication space can be pumped into the workpiece.
The acting force generating portion generates an acting force capable of relatively moving the communication space forming portion and the piston.
In the autofrettage processing apparatus of the present invention, when the piston and the contact surface come into contact with each other, the space between the inner wall surface (226) radially outside the contact surface of the communication space forming portion and the outer wall surface (322) of the piston. In addition, a recovery space (220) capable of recovering a compressive fluid having a specific gravity different from that of the incompressible fluid contained in the fluid is formed.

  In the auto-frettage processing apparatus of the present invention, the communication space forming portion is located in the top direction or the ground direction of the workpiece. Compressive fluid is recovered between the inner wall surface of the communication space forming portion and the outer wall surface of the piston when the piston and the contact surface are in contact with each other while pressurizing the fluid by relative movement between the communication space forming portion and the piston. A collection space is formed. In the communication space and the fluid in the workpiece, an incompressible fluid that contributes to the machining of the workpiece and a compressive fluid that is compressed by pressurization are mixed. If the specific gravity of the incompressible fluid and the specific gravity of the compressible fluid are different, the incompressible fluid and the compressible fluid are separated due to the difference in specific gravity. Among these, the compressive fluid moves in the celestial direction or the ground direction and is recovered in the recovery space. Since the recovery space is blocked from the inside of the work by the contact of the piston and the contact surface, the compressive fluid recovered in the recovery space is not mixed with the incompressible fluid in the work again. As a result, it is possible to reliably pressurize the incompressible fluid in the workpiece to a desired pressure while separating the compressive fluid contained in the fluid from the fluid, so that the workpiece is processed in a relatively short time and with high accuracy. be able to.

The autofrettage processing method of the present invention includes a setting process, a fluid supply process, and a pressurized fluid pumping process.
In the setting step, a communication space forming portion (20) having a communication hole (23) that can communicate with the work (10) and a communication space (222) that is formed so as to be able to communicate with the work through the communication hole and can store fluid. ) And the inside of the work are set.
In the fluid supply step, a fluid containing an incompressible fluid is supplied to the communication space.
In the pressurized fluid pressure feeding step, the pistons (31, 32) provided so as to be able to reciprocate in the communication space are brought into contact with the contact surface (225) of the communication space forming portion formed around the communication space of the communication hole. Move and pump the fluid in the communication space into the workpiece.
In the autofrettage processing method of the present invention, in the pressurized fluid pumping step, the compressive fluid having a specific gravity different from that of the incompressible fluid is the radially inner wall surface (226) of the contact surface of the communication space forming portion and the piston. It is recovered in a recovery space (220) formed between the outer wall surface (322) of the main body.

  In the autofrettage processing method of the present invention, in the pressurized fluid pumping step, the compressive fluid separated from the incompressible fluid due to the difference in specific gravity is recovered in the recovery space. Since the recovery space is blocked from the inside of the work by the contact between the piston and the contact surface, the compressive fluid recovered in the recovery space is not mixed with the incompressible fluid in the work again. Thereby, a workpiece | work can be processed with high precision in a comparatively short time.

It is a mimetic diagram of an auto fretage processing device by one embodiment. It is the II-II sectional view taken on the line of FIG. It is a flowchart of the auto-frettage processing method by one Embodiment. It is a schematic diagram explaining the effect | action of the auto fretage processing apparatus by one Embodiment. It is a schematic diagram explaining the effect | action of the auto fretage processing apparatus by one Embodiment, Comprising: It is a schematic diagram explaining the effect | action different from FIG. It is a schematic diagram explaining the effect | action of the auto fretage processing apparatus by one Embodiment, Comprising: It is a schematic diagram explaining the effect | action different from FIG.

Hereinafter, an embodiment of an auto fretage processing apparatus will be described with reference to the drawings.
(One embodiment)
The auto-frettage processing apparatus 1 according to one embodiment is used for auto-frettage processing that plastically deforms the inner wall of the work 10 using the pressure of oil as an “incompressible fluid” introduced into the hollow work 10. It is done.

First, the shape of the workpiece 10 to be processed by the auto fretage processing apparatus 1 will be described.
As shown in FIG. 1, the workpiece 10 is a member made of metal formed in a cylindrical shape, and is, for example, a common rail capable of storing high-pressure fuel. The work 10 has an internal space 100 as “inside the work” that can store a fluid therein, and two openings 11 and 12 that communicate the internal space 100 with the outside.

  The auto-frettage processing apparatus 1 includes a cylinder part 20 as a “communication space forming part”, a piston part 30, a closing member 40, an acting force generation part 45, and a control part 50. 1 and 4 to 6, the direction in which the acting force generator 45 is positioned with respect to the workpiece 10 is a ground direction, and the direction in which the cylinder portion 20 is positioned with respect to the workpiece 10 is a top direction.

  The cylinder unit 20 includes a nozzle 21 and a cylinder 22. The cylinder part 20 is located in the top direction of the workpiece 10. The cylinder part 20 is provided so as to be movable in the vertical direction along the central axis C1 of the auto-frettage processing apparatus 1. The central axis C1 of the auto fretage processing apparatus 1 is substantially parallel to the moving direction of the pressure pin 31.

  The nozzle 21 is formed in a cylindrical shape and is provided between the workpiece 10 and the cylinder 22. The nozzle 21 has a nozzle communication path 210. The nozzle communication path 210 can communicate with the internal space 100 of the work 10 through the opening 11 as “one opening” of the work 10.

  The cylinder 22 is formed in a substantially bottomed cylindrical shape from metal. The cylinder 22 is located in the top direction of the nozzle 21 and is connected to the top end of the nozzle 21. The cylinder 22 includes a communication path 221, a communication space 222, an introduction path 223, and an air discharge path 224 as a “discharge path”.

  The communication path 221 is formed on the ground side of the cylinder 22 so as to extend in a direction along the central axis C1. The ground side opening of the communication path 221 is formed to be able to communicate with the nozzle communication path 210. A communication hole 23, which is an opening on the top side of the communication path 221, communicates with the communication space 222.

  The communication space 222 is formed in the approximate center of the cylinder 22. The communication space 222 is formed so that the inner diameter is larger than the inner diameter of the communication hole 23. The cylinder 22 has a contact surface 225 that can contact a holder 32 of a piston portion 30 described later around the communication hole 23. The contact surface 225 is formed to be inclined with respect to the central axis C1. An inner wall surface 226 is formed on the radially outer side of the contact surface 225. The inner wall surface 226 is formed so as to extend in the horizontal direction on the entire outer circumference in the radial direction of the contact surface 225.

The introduction path 223 is formed to communicate with the communication space 222 from a substantially horizontal direction. The opening 228 on the communication space 222 side of the introduction path 223 is formed at a position that can be closed by the holder 32 when the holder 32 and the contact surface 225 contact each other (see FIG. 6). The introduction path 223 is connected to the fluid supply unit 25 via the supply pipe 24. The introduction path 223 introduces oil supplied from the fluid supply unit 25 into the communication space 222.
The supply pipe 24 is provided with a flow rate control valve 241 that can control the flow rate of oil flowing through the introduction path 223. The flow control valve 241 is electrically connected to the control unit 50.

  The air discharge path 224 is formed to communicate with the communication space 222 from a substantially horizontal direction. As shown in FIG. 2, the air discharge path 224 is formed on the opposite side of the introduction path 223 across the communication space 222. When the oil in the communication space 222 is introduced, the air discharge path 224 discharges air as a “compressible fluid” in the communication space 222 to the outside.

  The piston part 30 is provided on the top side of the cylinder part 20. The piston portion 30 includes a pressure pin 31 as a “piston”, a holder 32 as a “piston”, a top plate 33, and a guide member 34. The piston portion 30 can pressure-feed oil in the communication space 222 to the internal space 100 of the workpiece 10.

  The pressure pin 31 is a columnar member provided in the communication space 222. When the cylinder part 20 moves in the vertical direction, the pressure pin 31 moves relative to the cylinder part 20 in the communication space 222.

  The holder 32 is a substantially cylindrical member provided in the radially outward direction of the pressure pin 31. The holder 32 has a through hole 320 through which the pressure pin 31 can be inserted on the central axis C1. The holder 32 is provided so as to be capable of reciprocating along the central axis C <b> 1 integrally with the pressure pin 31. The holder 32 is slidably formed on an inner wall 227 formed so as to extend in a direction along the central axis C <b> 1 of the cylinder 22. Thereby, the pressure pin 31 is guided by the holder 32 and the cylinder 22 in the direction along the central axis C1.

The holder 32 has a first inclined surface 321 and a second inclined surface 322 as an “outer wall surface” on the ground side.
The first inclined surface 321 is formed in an annular shape around the ground side opening of the through hole 320. The first inclined surface 321 is formed to be inclined with respect to the central axis C1. The inclination angle α321 of the first inclined surface 321 with respect to the central axis C1 is the same as the inclination angle α225 of the contact surface 225 with respect to the central axis C1.
The second inclined surface 322 is formed in an annular shape on the radially outer side of the first inclined surface 321. The second inclined surface 322 is formed such that the inclination angle α322 with respect to the central axis C1 is larger than the inclination angle α321. As a result, the distance between the second inclined surface 322 and the inner wall surface 226 of the cylinder 22 increases as the distance from the communication hole 23 increases.

  When the abutting surface 225 of the cylinder 22 and the first inclined surface 321 of the holder 32 abut, as shown in FIG. 1, a trap as a “recovery space” is formed by the second inclined surface 322 and the inner wall surface 226 of the cylinder 22. A space 220 is formed. In FIG. 1, the position of the second inclined surface 322 when the contact surface 225 of the cylinder 22 contacts the first inclined surface 321 is indicated by a one-dot chain line.

  The top plate 33 is provided on the top side of the holder 32. The top plate 33 is fixed to a fixing member (not shown) and cannot move. The top plate 33 supports the holder 32 and the guide member 34.

  The guide member 34 is formed to extend from the top plate 33 in the ground direction. The guide member 34 is fixed to the top plate 33. The guide member 34 is inserted into a guide hole 229 provided in the cylinder 22. The guide member 34 guides the movement of the cylinder portion 20 with respect to the top plate 33 in the vertical direction. In the present embodiment, two guide members 34 are provided.

  The closing member 40 is provided on the side opposite to the cylinder portion 20 with respect to the workpiece 10. The closing member 40 is formed so as to be able to close the opening 12 as the “other opening” of the workpiece 10.

The acting force generator 45 is provided on the ground side of the closing member 40. The acting force generation unit 45 includes a gantry 46 and an output unit 47.
The gantry 46 is a flat plate-like member provided so as to come into contact with the closing member 40. The gantry 46 supports the closing member 40 from the ground side, and transmits the acting force output from the output unit 47 to the closing member 40.
The output unit 47 is connected to the gantry 46. The output unit 47 outputs an acting force capable of moving the cylinder unit 20 in the upward direction via the gantry 46, the closing member 40, and the work 10. The output unit 47 is electrically connected to the control unit 50.

  The control unit 50 is a small computer having a CPU as computing means, ROM and RAM as storage means, input / output means, and the like. The control unit 50 controls the opening / closing of the flow control valve 241 and the magnitude of the acting force output by the output unit 47 based on a program input in advance.

  Next, an auto-frettage processing method for the workpiece 10 using the auto-frettage processing apparatus 1 will be described with reference to FIGS.

  First, in a step (hereinafter simply referred to as “S”) 101 as a “set process”, the workpiece 10 is attached to the auto-frettage processing apparatus 1. Specifically, the workpiece 10 is set between the nozzle 21 and the closing member 40 using a support member (not shown). At this time, as shown in FIG. 4, the output unit 47 moves the gantry 46 so that a gap 15 is formed between the closing member 40 and the workpiece 10 so that oil can leak out.

Next, in S <b> 102 as the “fluid supply process”, oil is supplied to the communication space 222. In S <b> 102, oil supplied by the fluid supply unit 25 is introduced into the communication space 222. At this time, the air introduced into the communication space 222 pushes the air in the communication space 222 out of the air discharge path 224 (see the solid line arrow F41 in FIG. 4). Further, the air pushed out from the communication space 222 causes the air in the internal space 100 of the work 10 to be discharged to the outside through the gap 15 (see the solid line arrow F42 in FIG. 4).
In the oil stored in the communication space 222, the air contained in the oil moves upward due to the difference in specific gravity from the oil. Thereby, the air contained in oil collects in the ground side of the 2nd inclined surface 322 of the holder 32 (area | region A220 shown in FIG. 4).

  Next, in S103 as the “pressurized fluid pumping step”, the oil in the communication space 222 is pressurized. In S103, the cylinder part 20 is moved to the top by the acting force generated by the output part 47. As a result, as shown in FIG. 5, the volume of the communication space 222 is reduced, so that the oil in the communication space 222 is pumped to the internal space 100 of the workpiece 10 through the communication path 221 and the nozzle communication path 210. The At this time, the air in the internal space 100 of the workpiece 10 is pushed out from the gap 15 by oil (see the solid line arrow F52 in FIG. 5).

When the cylinder portion 20 is further moved upward by the acting force output from the output portion 47, the oil is discharged from the gap 15. At this time, the output unit 47 closes the opening 12 by bringing the closing member 40 and the workpiece 10 into contact with each other.
Moreover, the air contained in oil moves to the top by the movement of the cylinder part 20 to the top. The air moving in the ceiling direction accumulates on the ground side of the second inclined surface 322 of the holder 32 (region A220 shown in FIG. 5).

  After the opening 12 is closed by the closing member 40, the oil in the internal space 100 of the workpiece 10 is pressurized when the cylinder portion 20 further moves in the upward direction. The inner wall 101 of the workpiece 10 forming the internal space 100 is plastically deformed using the pressure of the oil.

  When the first inclined surface 321 of the holder 32 and the contact surface 225 of the cylinder 22 come into contact with each other by the movement of the cylinder portion 20 in the top direction, a trap space 220 is formed as shown in FIG. In the trap space 220, the air that has moved to the area indicated by the area A220 shown in FIGS. The trap space 220 is blocked from the communication path 221 by the contact between the first inclined surface 321 and the contact surface 225. Further, the opening 228 on the communication space 222 side of the introduction path 223 is closed by the holder 32 due to the movement of the cylinder portion 20 in the top direction.

  Next, oil is discharged from the workpiece 10 in S104. In S <b> 104, for example, the closing member 40 is separated from the workpiece 10 by weakening the acting force output by the output unit 47. As a result, the oil in the internal space 100 is discharged from the opening 12 to the outside.

Finally, in S105, the workpiece 10 is removed from the auto-frettage processing apparatus 1. In S <b> 105, after confirming that the oil pressure in the internal space 100 has decreased, the workpiece 10 is removed from the auto-frettage processing apparatus 1.
Thereafter, the next workpiece 10 is attached to the auto-frettage processing apparatus 1 and the next auto-frettage processing is performed.
In the auto-frettage processing method according to the present embodiment, the workpiece 10 is processed in this way.

The fluid used for auto-frettage processing is a mixture of an incompressible fluid that contributes to workpiece processing and a compressible fluid that is compressed by pressurization. If the fluid contains a large amount of compressible fluid that is compressed by pressurization, the incompressible fluid cannot be pressurized to a desired pressure, and the workpiece may not be processed at the desired pressure.
In the auto-frettage processing apparatus 1, when the holder 32 and the contact surface 225 come into contact with each other while the oil is pressurized by the movement of the cylinder 22, a trap space 220 capable of collecting air is formed between the cylinder 22 and the holder 32. It is formed. The air separated from the oil due to the difference in specific gravity between the oil and the air moves to a region A220 (see FIGS. 4 and 5) located in the top direction of the workpiece 10 and is collected in the trap space 220. The trap space 220 is blocked from the communication path 221 communicating with the internal space 100 by the contact between the holder 32 and the contact surface 225, so that the air collected in the trap space 220 is oil in the work 10. Never mix again. Thereby, in this embodiment, since the oil in the workpiece | work 10 can be reliably pressurized to desired pressure, isolate | separating the air mixed with oil from oil, the workpiece | work 10 is comparatively short and highly accurate. Desired processing can be performed.

  The inner wall surface 226 of the cylinder 22 that forms the trap space 220 is formed to extend in the horizontal direction on the entire outer periphery of the contact surface 225 in the radial direction. The second inclined surface 322 of the holder 32 is formed in an annular shape outside the first inclined surface 321 in the radial direction. Thereby, since the trap space 220 is formed over the entire circumference in the radially outward direction of the contact surface 225, the air moving in the sky direction in the auto-frettage processing apparatus 1 can be reliably guided to the trap space 220. .

  In the auto-frettage processing apparatus 1, the distance between the inner wall surface 226 formed so as to extend in the horizontal direction and the second inclined surface 322 increases as the distance from the communication hole 23 increases. That is, the region A220 and the trap space 220 are formed so as to expand in the celestial direction as the distance from the communication hole 23 increases. As a result, the air moving in the top direction in the auto-frettage processing apparatus 1 can be reliably moved in the direction away from the communication hole 23. Therefore, when the holder 32 and the contact surface 225 contact each other, it is possible to reliably prevent air from being mixed in the oil on the workpiece 10 side.

  When the oil is supplied to the communication space 222 in S101 and S102, the output unit 47 sets the gantry 46 so that a gap 15 is formed between the closing member 40 and the workpiece 10 so that the oil can leak. Moving. Thereby, the air in the internal space 100 of the workpiece 10 can be pushed out from the opening 12. Therefore, the air in the internal space 100 such as the air adhering to the inner wall 101 can be reliably discharged to the outside.

  As shown in FIG. 2, the cylinder 22 has an introduction path 223 and an air discharge path 224 with the communication space 222 interposed therebetween. Accordingly, when oil is supplied from the introduction path 223 to the communication space 222, the air in the communication space 222 is easily discharged from the air discharge path 224. Therefore, the air in the communication space 222 can be reliably discharged to the outside.

  When the trap space 220 is formed in S 103, the opening 228 on the communication space 222 side of the introduction path 223 is closed by the holder 32. Thereby, since it is possible to prevent the air in the trap space 220 from flowing into the introduction path 223, it is possible to prevent the air in the trap space 220 from being mixed with the oil supplied to the communication space 222 in the next auto-frettage processing.

  The contact surface 225 is formed to be inclined with respect to the central axis C1. Thereby, if it contacts with the holder 32 which moves along the central axis C1, the communication path 221 and the trap space 220 can be reliably interrupted | blocked. Therefore, it is possible to reliably prevent the air collected in the trap space 220 from being mixed with the oil in the workpiece 10 again.

(Other embodiments)
In the above-described embodiment, oil is used as the incompressible fluid, and air is used as the compressive fluid. However, neither an incompressible fluid nor a compressible fluid is limited to this. What is necessary is just the combination of the incompressible fluid and compressive fluid from which specific gravity differs.

  In the above-described embodiment, the trap space is located in the top direction of the workpiece and the top direction of the contact surface. However, the positional relationship between the trap space and the workpiece is not limited to this. When the specific gravity of the incompressible fluid is smaller than the specific gravity of the compressible fluid, the trap space is positioned in the ground direction of the workpiece, so that the compressive fluid can be reliably collected in the trap space.

  In the above-described embodiment, the trap space is located in the top direction of the contact surface. However, the positional relationship between the trap space and the contact surface is not limited to this. When the specific gravity of the incompressible fluid is smaller than the specific gravity of the compressive fluid, the trap space is positioned in the ground direction of the contact surface, so that the compressive fluid can be reliably collected in the trap space.

  In the above-described embodiment, the workpiece has two openings that communicate the internal space with the outside. However, the number of openings the workpiece has is not limited to this. There may be one, or three or more.

  In the above-described embodiment, when the fluid is pressurized, the acting force generation unit moves the cylinder unit with respect to the piston unit. However, the acting force generator may move the piston part relative to the cylinder part.

  In the above-described embodiment, the distance between the second inclined surface of the holder that forms the trap space and the inner wall surface of the cylinder increases as the distance from the communication hole increases. However, the distance may be constant or may be shortened.

  In the above-described embodiment, the cylinder has the introduction path and the air discharge path with the communication space interposed therebetween. However, the positional relationship between the introduction path and the air discharge path is not limited to this.

  In the above-described embodiment, the contact surface is formed so as to be inclined with respect to the central axis of the auto-frettage processing apparatus. However, the contact surface may not be inclined. Moreover, even if it is spherical, when the holder and the contact surface come into contact with each other, the communication path and the trap space can be reliably shut off.

  As mentioned above, this invention is not limited to such embodiment, In the range which does not deviate from the meaning of invention, it can implement with a various form.

DESCRIPTION OF SYMBOLS 1 ... Auto fretage processing apparatus 10 ... Work 20 ... Cylinder part (communication space formation part)
23 ... Communication hole 222 ... Communication space 225 ... Contact surface 226 ... Inner wall surface 31 ... Pressure pin (piston)
32 ... Holder (piston)
322 ... Second inclined surface (outer wall surface)
45 ... Acting force generator

Claims (11)

An auto-frettage processing apparatus for processing a workpiece using the pressure of a fluid introduced into a hollow workpiece (10),
A communicating hole (23) located in the top or ground direction of the workpiece and communicating with the inside of the workpiece (100), and being formed to be able to communicate with the workpiece through the communicating hole, can store the fluid. A communication space forming part (20) having a continuous communication space (222);
The communication space is provided in the communication space so as to be movable relative to the communication space forming portion, and moves so as to contact a contact surface (225) formed around the communication space on the communication space side. Pistons (31, 32) capable of pumping the fluid into the workpiece;
An action force generating part (45) for generating an action force capable of relatively moving the communication space forming part and the piston;
With
When the piston and the contact surface contact each other, the fluid flows between an inner wall surface (226) radially outside the contact surface of the communication space forming portion and an outer wall surface (322) of the piston. An auto-frettage processing apparatus in which a recovery space (220) capable of recovering a compressive fluid having a specific gravity different from that of the included incompressible fluid is formed.   The auto-frettage processing apparatus according to claim 1, wherein the collection space is formed over the entire circumference of the contact surface in a radially outward direction of the contact surface.   The auto-frettage processing apparatus according to claim 1 or 2, wherein a distance between the inner wall surface and the outer wall surface becomes longer as the distance from the communication hole increases.   When the specific gravity of the incompressible fluid is larger than the specific gravity of the compressible fluid, the recovery space is positioned in the top direction of the workpiece, and the specific gravity of the incompressible fluid is smaller than the specific gravity of the compressible fluid The auto-frettage processing apparatus according to any one of claims 1 to 3, which is located in a ground direction of the workpiece.   When the specific gravity of the incompressible fluid is larger than the specific gravity of the compressible fluid, the recovery space is positioned in the top direction of the contact surface, and the specific gravity of the incompressible fluid is compared with the specific gravity of the compressible fluid. The auto-frettage processing apparatus according to any one of claims 1 to 4, which is positioned in a ground direction of the contact surface when it is small.   The auto-frettage processing apparatus according to any one of claims 1 to 5, wherein the acting force generating portion generates an acting force that can move the communication space forming portion with respect to the piston. The workpiece has a plurality of openings (11, 12) communicating with the workpiece,
A closing member (40) capable of closing the other openings (12) of the plurality of openings when one opening (11) of the plurality of openings communicates with the communication hole;
The auto-frettage processing apparatus according to claim 6, wherein the acting force generator is capable of controlling a contact state between the periphery of the other opening and the closing member. The communication space forming portion has an introduction path (223) capable of introducing the fluid into the communication space, and a discharge path (224) capable of discharging the compressive fluid in the communication space,
The auto-frettage processing apparatus according to claim 1, wherein the introduction path and the discharge path are formed so as to sandwich the communication space. The communication space forming portion has an introduction path capable of introducing the fluid into the communication space;
The auto-frettage processing apparatus according to any one of claims 1 to 8, wherein when the piston moves so as to contact the contact surface, the communication space and the introduction path can be blocked.   The auto-frettage processing apparatus according to any one of claims 1 to 9, wherein the contact surface is formed so as to be inclined with respect to a moving direction of the piston or is formed in a spherical shape. An auto-frettage processing method for processing a workpiece using the pressure of a fluid introduced into a hollow workpiece (10),
A communication hole (23) located in the top or ground direction of the work and communicating with the work, and a communication space (222) formed so as to be able to communicate with the work via the communication hole and storing the fluid. A setting step of setting the work so that the communication space forming portion (20) having the inside and the inside of the work communicate with each other;
A fluid supply step of supplying the fluid containing an incompressible fluid to the communication space;
The pistons (31, 32) provided in the communication space so as to be reciprocally movable are moved so as to come into contact with the contact surface (225) of the communication space forming portion formed around the communication space of the communication hole, A pressurized fluid pumping step of pumping the fluid in the communication space into the workpiece;
Have
In the pressurized fluid pumping step, the compressive fluid having a specific gravity different from that of the incompressible fluid includes an inner wall surface (226) in a radially outward direction of the contact surface of the communication space forming portion and an outer wall surface (322 of the piston). The auto-frettage processing method is recovered in the recovery space (220) formed between the two.

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