Extrusion device for hole strengthening and hole extrusion strengthening process

Abstract

The invention discloses an extrusion device for hole strengthening and a hole extrusion strengthening process, and relates to the technical field of hole machining, the device comprises a first extrusion core rod and a second extrusion core rod, and at least part of the outer side wall of the first extrusion core rod can extrude the inner side wall of a first hole body of a bottom hole; and at least part of the outer side wall of the second extrusion core rod can extrude the inner side wall of the first hole edge chamfer of the bottom hole. The method comprises the steps that the outer side wall of a first extrusion core rod makes contact with the inner side wall of a first hole body of a bottom hole, the inner side wall of the first hole body is extruded, and the inner side wall of the first hole body generates elasticoplastic deformation; and the outer side wall of the second extrusion core rod makes contact with the inner side wall of the first hole edge chamfer of the bottom hole and extrudes the inner side wall of the first hole edge chamfer, so that the inner side wall of the first hole edge chamfer generates elasticoplastic deformation. The fatigue strength, the stress resistance, the corrosion resistance and the fatigue resistance of the pore structure can be improved on the basis of not changing materials and structural design and not increasing the weight of parts, and the cost is low.

Description

Technical Field

[0001] The invention relates to the technical field of hole processing, in particular to an extrusion device for hole strengthening and a hole extrusion strengthening process. Background Art

[0002] Hole structures such as bolt holes, pin holes, and pressure-equalizing holes are prone to stress concentration when used. For example, when the turbine disk, compressor disk, and other structures of the engine are working, the bolt holes, pin holes, and pressure-equalizing holes on the disk often become high-stress parts of the turbine disk due to stress concentration. Among them, bolt holes are used for bolt connections, and are often used to connect the turbine disk and the shaft of an aircraft engine; the pressure-equalizing holes of the turbine disk of the engine are common structures on the engine, which undertake functions such as ventilation and balancing the air pressure in the front and rear cavities of the disk. The weakening of the bearing capacity of the turbine disk by the pressure-equalizing holes and bolt holes will reduce the overall strength and service life of the structure. Stress concentration at the edge of the hole often leads to radial crack failures, which has a significant impact on the life of the turbine disk.

[0003] For the stress concentration problem of hole structures such as pressure equalizing holes and bolt holes, special non-circular holes can be designed to optimize the stress distribution at the hole edge, and the hole edge chamfering, hole polishing and other process methods can be used for optimization. Sometimes, the pressure equalizing holes are directly eliminated. However, the effects of processing methods such as processing hole edge chamfering and hole polishing on relieving hole stress concentration are very limited, and eliminating the pressure equalizing holes will affect the balancing effect of the air pressure in the front and rear cavities of the turbine disk. Summary of the invention

[0004] The purpose of the present invention is to provide an extrusion device and a hole extrusion strengthening process for hole strengthening, so as to solve the problems existing in the above-mentioned prior art, greatly improve the fatigue strength, stress resistance, corrosion resistance and fatigue resistance of the hole structure, and have the advantages of not changing the material, not changing the structural design, not increasing the weight of parts, low cost, and obvious strengthening effect.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides an extrusion device for hole strengthening, comprising a first extrusion core rod and a second extrusion core rod, wherein at least a portion of the outer side wall of the first extrusion core rod can contact the inner side wall of the first hole body of the bottom hole and extrude the inner side wall of the first hole body; at least a portion of the outer side wall of the second extrusion core rod can contact the inner side wall of the first hole edge chamfer of the bottom hole and extrude the inner side wall of the first hole edge chamfer.

[0007] Preferably, the first extrusion core rod includes an extrusion strengthening section, a strengthening holding section and an anti-rebound section which are connected in sequence, the shape of the outer wall of the strengthening holding section is the same as the shape of the inner wall of the second hole body of the target hole, and the size of the outer wall of the strengthening holding section is the same as the size of the inner wall of the second hole body; the outer edge of the end face of the extrusion strengthening section close to one end of the strengthening holding section is connected to the outer edge of the end face of the strengthening holding section close to one end of the extrusion strengthening section, the contour size of the extrusion strengthening section gradually decreases in the direction away from the strengthening holding section, and the contour size of the end of the extrusion strengthening section away from the strengthening holding section is smaller than the size of the first hole body; the outer edge of the end face of the anti-rebound section close to one end of the strengthening holding section is connected to the outer edge of the end face of the strengthening holding section close to one end of the anti-rebound section.

[0008] Preferably, the outline dimension of the anti-rebound segment gradually decreases in a direction away from the reinforced retaining segment.

[0009] Preferably, the extrusion reinforcement section and the anti-rebound section are symmetrical about a middle cross section of the reinforcement retaining section.

[0010] Preferably, the second extrusion core rod includes a chamfered reinforcement section, and the angle between the two side edges of the longitudinal section of the chamfered reinforcement section and the center line of the chamfered reinforcement section is the same as the angle of the second hole edge chamfer of the target hole; the outer contour dimension of the end face of the small end of the chamfered reinforcement section is smaller than the inner contour dimension of the small end of the second hole edge chamfer, and the outer contour dimension of the end face of the large end of the chamfered reinforcement section is larger than the inner contour dimension of the large end of the second hole edge chamfer; the length of the chamfered reinforcement section is larger than the length of the hole section where the second hole edge chamfer is located.

[0011] Preferably, the second extruded mandrel also includes a strength reinforcement section, which is fixedly connected to the large end of the chamfered reinforcement section, and the shape and outline dimensions of each cross section of the strength reinforcement section are respectively the same as the shape and outline dimensions of the large end face of the chamfered reinforcement section.

[0012] Preferably, the outer wall of the extrusion reinforcement section, the outer wall of the reinforcement retention section, the outer wall of the anti-rebound section, the outer wall of the chamfer reinforcement section and the outer wall of the strength reinforcement section are all provided with a lubricating coating.

[0013] The present invention also provides a hole extrusion strengthening process based on the extrusion device for hole strengthening, comprising the following steps:

[0014] Extrusion-strengthening the first hole body of the bottom hole: making the outer side wall of the first extrusion mandrel contact with the inner side wall of the first hole body of the bottom hole and extruding the inner side wall of the first hole body, so that the inner side wall of the first hole body generates elastic-plastic deformation;

[0015] Extrusion strengthens the first hole edge chamfer of the bottom hole: the outer side wall of the second extrusion mandrel is brought into contact with the inner side wall of the first hole edge chamfer of the bottom hole and extrudes the inner side wall of the first hole edge chamfer, so that the inner side wall of the first hole edge chamfer undergoes elastic-plastic deformation.

[0016] Preferably, the first extrusion mandrel comprises an extrusion reinforcement section, a reinforcement holding section and an anti-rebound section connected in sequence, the shape of the outer side wall of the reinforcement holding section is the same as the shape of the inner side wall of the second hole body of the target hole, and the size of the outer side wall of the reinforcement holding section is the same as the size of the inner side wall of the second hole body; the outer edge of the end face of the extrusion reinforcement section close to one end of the reinforcement holding section is connected to the outer edge of the end face of the reinforcement holding section close to one end of the extrusion reinforcement section, the contour size of the extrusion reinforcement section gradually decreases in the direction away from the reinforcement holding section, and the contour size of the end of the extrusion reinforcement section away from the reinforcement holding section is smaller than the size of the first hole body; the outer edge of the end face of the anti-rebound section close to one end of the reinforcement holding section is connected to the outer edge of the end face of the reinforcement holding section close to one end of the anti-rebound section;

[0017] The second extrusion mandrel comprises a chamfered reinforcement section, and the included angles between two side edges of the longitudinal section of the chamfered reinforcement section and the center line of the chamfered reinforcement section are the same as the angle of the second hole edge chamfer of the target hole;

[0018] The method for extruding and strengthening the first hole body of the bottom hole comprises: controlling the first extrusion mandrel to continuously feed along the center line direction of the first hole body, so that the extrusion strengthening section, the strengthening holding section and the anti-rebound section pass through the first hole body in sequence, and completing one hole body extrusion strengthening; performing at least one hole body extrusion strengthening on the bottom hole until the inner contour size of the first hole body of the bottom hole after extrusion strengthening is within the size range of the inner contour of the second hole body of the target hole;

[0019] The method for extrusion strengthening the first hole edge chamfer of the bottom hole comprises: controlling the second extrusion mandrel to continuously feed along the center line direction of the first hole body so that the outer side wall of the chamfer strengthening section extrude the first hole edge chamfer to complete one hole edge chamfer extrusion strengthening; performing at least one hole edge chamfer extrusion strengthening on the bottom hole.

[0020] Preferably, it also includes:

[0021] Before and during extrusion strengthening of the first hole body of the bottom hole, lubricating oil is added between the outer side wall of the first extrusion mandrel and the inner side wall of the first hole body;

[0022] Before and during the extrusion strengthening of the first hole edge chamfer of the bottom hole, lubricating oil is added between the outer side wall of the second extrusion mandrel and the inner side wall of the first hole edge chamfer;

[0023] After the extrusion strengthening of the bottom hole is completed, the inner side wall of the first hole body and / or the inner side wall of the first hole edge chamfer is polished.

[0024] Compared with the prior art, the present invention has achieved the following technical effects:

[0025] The present invention provides an extrusion device for hole strengthening and a hole extrusion strengthening process, comprising a first extrusion mandrel and a second extrusion mandrel, wherein at least a portion of the outer wall of the first extrusion mandrel can contact with the inner wall of the first hole body of the bottom hole and extrude the inner wall of the first hole body; and at least a portion of the outer wall of the second extrusion mandrel can contact with the inner wall of the first hole edge chamfer of the bottom hole and extrude the inner wall of the first hole edge chamfer. By extruding the inner wall of the first hole body by the first extrusion mandrel, elastic-plastic deformation can be generated at the inner wall of the first hole body, and by extruding the inner wall of the first hole edge chamfer by the second extrusion mandrel, elastic-plastic deformation can be generated at the inner wall of the first hole edge chamfer. The generation of elastic-plastic deformation can introduce a large depth, high amplitude, and controllable residual compressive stress layer into the hole wall, improve the distribution state of the local stress of the hole edge of the hole structure under the action of external load, and greatly improve the fatigue strength, stress resistance, corrosion resistance, and fatigue resistance of the hole structure, and has the advantages of not changing the material, not changing the structural design, not increasing the weight of the parts, low cost, and obvious strengthening effect. The present invention not only strengthens the first hole body of the bottom hole, but also strengthens the first hole edge chamfer of the bottom hole, thereby compensating for the weakness of the first hole edge chamfer and further improving the strengthening effect of the hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic structural diagram of a first extrusion mandrel provided in Example 1;

[0028] Figure 2 A front view of a first extrusion mandrel provided in Example 1;

[0029] Figure 3 for Figure 2 Left view of

[0030] Figure 4 for Figure 1 Sectional view of AA in the middle;

[0031] Figure 5 A schematic structural diagram of a second extrusion mandrel provided in Example 1;

[0032] Figure 6 A front view of a second extrusion mandrel provided in Example 1;

[0033] Figure 7 for Figure 6 Left view of

[0034] Figure 8 for Figure 6 Cross-sectional view of the middle BB;

[0035] Fig. 9 A front view of the bottom hole provided in Example 1;

[0036] Fig.10 for Fig. 9 Cross-sectional view of CC;

[0037] Fig.11 A front view of the target hole provided in Example 1;

[0038] Fig.12 for Fig.11 Cross-sectional view of the middle DD;

[0039] Fig.13 It is a schematic diagram of the structure of the hole extrusion strengthening machine body;

[0040] Fig.14 This is a comparison chart of the life span of the reinforced sample and the unreinforced sample;

[0041] Fig.15 A system block diagram of the hole extrusion strengthening process provided in Example 2;

[0042] In the figure: 100, extrusion device for hole strengthening; 2, first extrusion core rod; 201, extrusion strengthening section; 202, strengthening holding section; 203, anti-rebound section; 204, first side; 205, first clamping section; 3, second extrusion core rod; 301, chamfer strengthening section; 302, strength reinforcement section; 303, second side; 304, second clamping section; 4, bottom hole; 401, first hole body; 402, first hole side chamfer; 5, target hole; 501, second hole body; 502, second hole side chamfer. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] The purpose of the present invention is to provide an extrusion device and a hole extrusion strengthening process for hole strengthening, so as to solve the problems existing in the above-mentioned prior art, greatly improve the fatigue strength, stress resistance, corrosion resistance and fatigue resistance of the hole structure, and have the advantages of not changing the material, not changing the structural design, not increasing the weight of parts, low cost, and obvious strengthening effect.

[0045] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] Example 1

[0047] like Figures 1 to 13 As shown, this embodiment provides an extrusion device 100 for hole strengthening, including a first extrusion mandrel 2 and a second extrusion mandrel 3, at least a portion of the outer wall of the first extrusion mandrel 2 can contact the inner wall of the first hole body 401 of the bottom hole 4 and extrude the inner wall of the first hole body 401; the bottom hole 4 refers to a hole pre-processed during the machining process for subsequent processing (such as tapping, reaming, etc.); at least a portion of the outer wall of the second extrusion mandrel 3 can contact the inner wall of the first hole edge chamfer 402 of the bottom hole 4 and extrude the inner wall of the first hole edge chamfer 402. By squeezing the inner wall of the first hole body 401 by the first extrusion mandrel 2, elastic-plastic deformation can be generated at the inner wall of the first hole body 401, and by squeezing the inner wall of the first hole edge chamfer 402 by the second extrusion mandrel 3, elastic-plastic deformation can be generated at the inner wall of the first hole edge chamfer 402. The generation of elastic-plastic deformation can introduce a large depth, high amplitude, and controllable residual compressive stress layer into the hole wall, improve the distribution state of the local stress of the hole edge of the hole structure under the action of external load, and greatly improve the fatigue strength, stress resistance, corrosion resistance, and fatigue resistance of the hole structure. It has the advantages of not changing the material, not changing the structural design, not increasing the weight of the parts, low cost (the device can be reused, and the process is convenient to implement), and obvious strengthening effect. This embodiment not only strengthens the first hole body 401 of the bottom hole 4, but also strengthens the first hole edge chamfer 402 of the bottom hole 4, making up for the disadvantage of the weakness of the first hole edge chamfer 402.

[0048] In this embodiment, the first extrusion mandrel 2 includes an extrusion strengthening section 201, a strengthening holding section 202 and an anti-rebound section 203 connected in sequence. The shape of the outer wall of the strengthening holding section 202 is the same as the shape of the inner wall of the second hole body 501 of the target hole 5, and the size of the outer wall of the strengthening holding section 202 is the same as the size of the inner wall of the second hole body 501; the outer edge of the end face of the extrusion strengthening section 201 close to the strengthening holding section 202 is connected to the outer edge of the end face of the strengthening holding section 202 close to the extrusion strengthening section 201, that is, the outer contour size and shape of the end face of the extrusion strengthening section 201 close to the strengthening holding section 202 are respectively the same as the outer contour size and shape of the end face of the strengthening holding section 202 close to the strengthening holding section 202. The outer contour size and shape of the end face at one end of the extruded strengthening section 201 are the same, and the contour size of the extruded strengthening section 201 gradually decreases in the direction away from the strengthening holding section 202. The contour size of the end face of the extruded strengthening section 201 away from the strengthening holding section 202 is smaller than the size of the first hole body 401; the outer edge of the end face of the anti-rebound section 203 close to the strengthening holding section 202 is connected to the outer edge of the end face of the strengthening holding section 202 close to the anti-rebound section 203, that is, the outer contour size and shape of the end face of the anti-rebound section 203 close to the strengthening holding section 202 are respectively the same as the outer contour size and shape of the end face of the strengthening holding section 202 close to the extruded strengthening section 201.

[0049] The sizes of the first extrusion core rod 2 and the second extrusion core rod 3 in this embodiment can be designed according to the contour size and extrusion amount of the bottom hole 4 to be strengthened. After removing the extrusion amount, the contour size of the bottom hole 4 can obtain the target hole 5; the design principle is: the contour size of the end face of the extruded strengthening section 201 away from the strengthening holding section 202 is smaller than the size of the first hole body 401, that is, the outer contour of the end face of the extruded strengthening section 201 away from the strengthening holding section 202 can be completely placed in the first hole body 401, ensuring that the small end of the extruded strengthening section 201 can extend into the first hole body 401. The contour size of the large end face of the extrusion strengthening section 201 is the same as the contour size of any cross section of the strengthening holding section 202, and is the same as the contour size of any cross section of the target hole 5, so that the extrusion strengthening section 201 and the strengthening holding section 202 can have a good transition and can gradually extrude and expand the first hole body 401; after one extrusion of the strengthening holding section 202, the target hole 501 is not obtained directly, but a certain rebound will be generated. At this time, the anti-rebound section 203 can have a certain hindering effect on the rebound of the first hole body 401; after multiple extrusion strengthenings, the contour size of the first hole body 401 can meet the design requirements of the contour size of the target hole 5.

[0050] In this embodiment, the outline size of the anti-rebound segment 203 gradually decreases in the direction away from the reinforced holding segment 202 , and the portion of the anti-rebound segment 203 close to the reinforced holding segment 202 has a certain blocking effect on the rebound of the first hole body 401 .

[0051] As a preferred embodiment, two side edges (first side edges 204 ) of any longitudinal section of the extrusion reinforcement section 201 and the anti-rebound section 203 are inclined straight lines. For example, the extrusion reinforcement section 201 and the anti-rebound section 203 may be tapered.

[0052] In this embodiment, the extrusion reinforcement section 201 and the anti-rebound section 203 are symmetrical about the middle cross section of the reinforcement holding section 202 , that is, the extrusion reinforcement section 201 and the anti-rebound section 203 are completely the same in shape and size.

[0053] In this embodiment, the second extrusion core rod 3 includes a chamfered reinforcement section 301, and the angle between the two side edges (second side edges 303) of the longitudinal section of the chamfered reinforcement section 301 and the center line of the chamfered reinforcement section 301 is the same as the angle of the second hole edge chamfer 502 of the target hole 5; the outer contour dimension of the end face of the small end of the chamfered reinforcement section 301 is smaller than the inner contour dimension of the small end of the second hole edge chamfer 502, and the outer contour dimension of the end face of the large end of the chamfered reinforcement section 301 is larger than the inner contour dimension of the large end of the second hole edge chamfer 502; the length of the chamfered reinforcement section 301 is larger than the length of the hole section where the second hole edge chamfer 502 is located; it is ensured that the outer wall of the chamfered reinforcement section 301 can fully contact the inner wall of the hole section where the second hole edge chamfer 502 is located, so as to achieve extrusion reinforcement of the second hole edge chamfer 502.

[0054] In this embodiment, the second extrusion mandrel 3 further includes a strength reinforcement section 302, which is fixedly connected to the large end of the chamfer reinforcement section 301, and the shape and outline size of each cross section of the strength reinforcement section 302 are respectively the same as the shape and outline size of the large end face of the chamfer reinforcement section 301. The strength reinforcement section 302 is arranged between the chamfer reinforcement section 301 and the second clamping section 304 to play a transition role, and is used to disperse the axial force during the extrusion process and improve the strength of the second extrusion mandrel 3.

[0055] As a preferred embodiment, the length of the strength reinforcement section 302 is greater than that of the chamfer reinforcement section 301 , which can improve the stress distribution inside the chamfer reinforcement section 301 and the strength reinforcement section 302 and enhance the overall strength of the second extruded mandrel 3 .

[0056] In this embodiment, a lubricating coating is provided on the outer wall of the extrusion strengthening section 201, the outer wall of the strengthening holding section 202, the outer wall of the anti-rebound section 203, the outer wall of the chamfer strengthening section 301, and the outer wall of the strength reinforcement section 302. The lubricating coating is preferably a diamond-like film or a nano-composite ceramic film. The lubricating coating can improve the lubrication effect during the extrusion process and ensure the extrusion strengthening effect.

[0057] In this embodiment, the first extruded mandrel 2 further includes a first clamping section 205, which is fixedly connected to one end of the anti-rebound section 203 away from the reinforcement holding section 202; the second extruded mandrel 3 further includes a second clamping section 304, which is fixedly connected to one end of the strength reinforcement section 302 away from the chamfer reinforcement section 301. The outer dimensions of the first clamping section 205 and the second clamping section 304 are smaller than the inner contour dimensions of the first hole body 401.

[0058] In this embodiment, the length of the strengthening and maintaining section 202 is half the length of the extrusion strengthening section 201 .

[0059] In this embodiment, a hole extrusion strengthening machine body is also included, and the hole extrusion strengthening machine body includes a driving device and a main shaft, one end of the main shaft is connected to the driving device, and the other end of the main shaft can be detachably fixedly connected to the first clamping section 205 or the second clamping section 304. The driving device can drive the main shaft to feed bidirectionally along the main shaft axis direction to drive the first clamping section 205 or the second clamping section 304 to move bidirectionally along the main shaft axis direction. As a preferred embodiment, the feed straightness error of the main shaft is less than 0.01mm, and the axial feed tensile force is not less than 10kN. The driving device is preferably a motor.

[0060] The extrusion device 100 for hole strengthening of this embodiment can be used for extrusion strengthening of holes of various shapes and sizes, and in particular, provides a feasible strengthening method for the processing of special-shaped deep holes, and can particularly achieve extrusion strengthening of materials at high temperatures, for example, it can be used for the processing of special-shaped holes on high-temperature nickel-based alloy parts.

[0061] Example 2

[0062] This embodiment provides a hole extrusion strengthening process based on the extrusion device 100 for hole strengthening in Embodiment 1, comprising the following steps:

[0063] Extrusion strengthens the first hole body 401 of the bottom hole 4: the outer wall of the first extrusion mandrel 2 is brought into contact with the inner wall of the first hole body 401 of the bottom hole 4 and extrudes the inner wall of the first hole body 401, so that the inner wall of the first hole body 401 undergoes elastic-plastic deformation;

[0064] Extrusion strengthens the first hole edge chamfer 402 of the bottom hole 4: the outer wall of the second extrusion mandrel 3 is brought into contact with the inner wall of the first hole edge chamfer 402 of the bottom hole 4 and extrudes the inner wall of the first hole edge chamfer 402, causing elastic-plastic deformation of the inner wall of the first hole edge chamfer 402.

[0065] In this embodiment, the first extrusion mandrel 2 includes an extrusion strengthening section 201, a strengthening holding section 202 and an anti-rebound section 203 connected in sequence. The shape of the outer wall of the strengthening holding section 202 is the same as the shape of the inner wall of the second hole body 501 of the target hole 5, and the size of the outer wall of the strengthening holding section 202 is the same as the size of the inner wall of the second hole body 501; the outer edge of the end face of the extrusion strengthening section 201 close to the strengthening holding section 202 is connected to the outer edge of the end face of the strengthening holding section 202 close to the extrusion strengthening section 201, that is, the extrusion strengthening section 201 close to the strengthening holding section 202 is connected to the outer edge of the end face of the strengthening holding section 202 close to the extrusion strengthening section 201. The outer contour size and shape of the end face of one end of the strengthening holding section 202 are respectively the same as the outer contour size and shape of the end face of the strengthening holding section 202 close to the extrusion strengthening section 201. The contour size of the extrusion strengthening section 201 gradually decreases in the direction away from the strengthening holding section 202. The contour size of the end face of the extrusion strengthening section 201 away from the strengthening holding section 202 is smaller than the size of the first hole body 401. The outer edge of the end face of the anti-rebound section 203 close to the strengthening holding section 202 is connected to the outer edge of the end face of the strengthening holding section 202 close to the anti-rebound section 203.

[0066] The second extrusion mandrel 3 includes a chamfered reinforcement section 301, and the included angle between the two side edges of the longitudinal section of the chamfered reinforcement section 301 and the center line of the chamfered reinforcement section 301 is the same as the angle of the second hole edge chamfer 502 of the target hole 5;

[0067] The method for extruding and strengthening the first hole body 401 of the bottom hole 4 comprises: controlling the first extrusion mandrel 2 to continuously feed along the center line direction of the first hole body 401, so that the extrusion strengthening section 201, the strengthening holding section 202 and the anti-rebound section 203 pass through the first hole body 401 in sequence, and completing one hole body extrusion strengthening; performing at least one hole body extrusion strengthening on the bottom hole 4, until the inner contour size of the first hole body 401 of the bottom hole 4 after extrusion strengthening is within the size range of the inner contour size of the second hole body 501 of the target hole 5;

[0068] The method for extruding and strengthening the first hole edge chamfer 402 of the bottom hole 4 comprises: controlling the second extrusion mandrel 3 to continuously feed along the center line direction of the first hole body 401, so that the outer wall of the chamfer strengthening section 301 extrude the first hole edge chamfer 402, and complete one hole edge chamfer extrusion strengthening; performing at least one hole edge chamfer extrusion strengthening on the bottom hole 4 until the inner contour size of the first hole edge chamfer 402 of the bottom hole 4 after extrusion strengthening is within the size range of the inner contour of the second hole edge chamfer 502 of the target hole 5.

[0069] In this embodiment, it also includes: before extruding and strengthening the first hole body 401 of the bottom hole 4 and during the extrusion of the first hole body 401 of the bottom hole 4, lubricating oil is added between the outer wall of the first extrusion core rod 2 and the inner wall of the first hole body 401; before extruding and strengthening the first hole edge chamfer 402 of the bottom hole 4 and during the extrusion of the first hole edge chamfer 402 of the bottom hole 4, lubricating oil is added between the outer wall of the second extrusion core rod 3 and the inner wall of the first hole edge chamfer 402 to ensure good lubrication during the extrusion process and to ensure the extrusion effect; after completing the extrusion strengthening of the bottom hole 4, polishing the inner wall of the first hole body 401 and / or the inner wall of the first hole edge chamfer 402 can significantly improve the surface quality of the hole and further extend the service life of the hole.

[0070] As a preferred implementation, the hole extrusion strengthening process provided in this embodiment specifically includes the following steps:

[0071] 1. Preparation of extrusion device 100 for hole strengthening

[0072] The extrusion amount is determined according to the inner contour size (such as the aperture) and the extrusion rate of the target hole 5, and the corresponding first extrusion core rod 2 and second extrusion core rod 3 are designed and processed according to the extrusion amount, which must meet the following requirements: the contour size of the end face of the extruded strengthening section 201 away from the strengthening holding section 202 is smaller than the size of the first hole body 401, the contour size of the large end face of the extruded strengthening section 201 is the same as the contour size of any cross section of the strengthening holding section 202, and is the same as the contour size of any cross section of the target hole 5, and the extruded strengthening section 201 and the anti-rebound section 203 are symmetrical about the middle cross section of the strengthening holding section 202.

[0073] 2. Processing of the shape and bottom hole 4 of the workpiece to be processed

[0074] 3. Bottom hole 4 extrusion strengthening

[0075] 3.1. Extrusion-strengthening the first hole body 401 by the first extrusion core rod 2.

[0076] 3.2. The first hole edge chamfer 402 is extruded and strengthened by the second extrusion mandrel 3.

[0077] 3.3. Polishing the strengthened inner side wall of the first hole body 401 and / or the inner side wall of the first hole edge chamfer 402.

[0078] Specifically, the flow chart of the bottom hole 4 extrusion strengthening process is as follows: Fig.15 As shown, the specific implementation is as follows:

[0079] (1) The workpiece to be processed is mounted on a special bottom hole fixture for a machine tool workbench, and the first extrusion mandrel 2 and the second extrusion mandrel 3 are mounted on the machine tool magazine;

[0080] (2) Positioning the bottom hole 4 on the X-axis and Y-axis: Use an edge finder to position the bottom hole 4 on the X-axis and Y-axis in sequence;

[0081] (3) Extrusion strengthening of the first hole body 401: After fixing the first extrusion core rod 2 to the main shaft, control the main shaft to slowly feed along the Z-axis direction through the bottom hole 4 until the extrusion strengthening section 201, the strengthening holding section 202 and the anti-rebound section 203 completely pass through the first hole body 401, completing the extrusion strengthening of the first hole body 401. Do not pause during the extrusion process, otherwise it is easy to cause the rod to get stuck. After the extrusion is completed, the aperture should be measured in time to determine whether it is within a reasonable range; if it does not meet the requirements, perform another extrusion;

[0082] (4) Extrusion strengthening the first hole edge chamfer 402: Remove the first extrusion mandrel 2 on the spindle and replace it with the second extrusion mandrel 3. After fixing the second extrusion mandrel 3 to the spindle, first make the outer wall of the chamfer strengthening section 301 fit with the inner wall of the first hole edge chamfer 402 but without force, and then control the spindle to drop 0.02mm through the motor to achieve the extrusion of the first hole edge chamfer 402. Repeat the above steps several times to ensure the strengthening effect;

[0083] (5) polishing the inner side wall of the strengthened first hole body 401 and / or the inner side wall of the first hole edge chamfer 402;

[0084] (6) Hole size measurement after polishing: Use an internal micrometer to measure the hole diameter to ensure that the hole diameter is within the actual size tolerance range.

[0085] The extrusion device 100 for hole strengthening of this embodiment can be used for extrusion strengthening of holes of various shapes and sizes, such as Figures 11-12 Take the special-shaped hole shown as an example. The special-shaped hole is composed of six symmetrical arcs, and the adjacent arcs are tangent to each other. The key dimensions of the special-shaped hole are R1, R2, R3, L0, and B0. Among them, R1, R2, and R3 determine the shape of the non-circular hole, and L0 and B0 determine the size and extrusion amount. The size of the bottom hole 4 required for extrusion strengthening is to reduce L0 and B0 equidistantly according to the extrusion amount, that is:

[0086] δ=2*(L0-L0')=2*(B0-B0'),

[0087] Among them, δ is the extrusion amount, L0 and B0 are the minor axis size and major axis size of the target hole 5 , and L0′ and B0′ are the minor axis size and major axis size of the bottom hole 4 .

[0088] The shape of the workpiece to be processed is the same as the shape of the special-shaped hole, and the strengthening holding section 202 also has key dimensions R1, R2, R3, L0, and B0. For the workpiece to be processed, the processing method of the shape of the workpiece to be processed and the bottom hole 4 includes:

[0089] 2.1. Cutting: Perform the first rough machining on the short axis size, long axis size and thickness of the blank, with a single-side cutting removal of 0.5 mm to obtain the first rough blank;

[0090] 2.2. Perform a second rough machining on the first rough blank, cutting six arcs of the outer contour of the workpiece to be machined, with a single-side cutting removal of 0.5 mm, to obtain a second rough blank;

[0091] 2.3. Finish the minor axis size and thickness of the second rough blank by grinding it so that the minor axis size and thickness of the second rough blank are within the size tolerance range of the drawing, thereby obtaining the first fine blank;

[0092] 2.4. Finish the length of the first fine blank and the six arcs of the outer contour of the workpiece to be processed to meet the requirements of the size tolerance range of the drawing; obtain the second fine blank;

[0093] 2.5. Rough milling of special-shaped holes on the second refined blank, with a single-side removal of 0.25 mm;

[0094] 2.6. Finish mill the special-shaped hole in step 2.6, with a single-side removal of 0.05 mm;

[0095] 2.7. Re-mill the special-shaped holes in step 2.7 to meet the size tolerance requirements of the drawing;

[0096] 2.8. Process the first hole edge chamfer 402 at both ends of the special-shaped hole.

[0097] As a feasible implementation manner, the first extrusion mandrel 2 and the second extrusion mandrel 3 are made of tungsten steel with a hardness of 68HRC.

[0098] The following fatigue tests are carried out on the workpieces before and after strengthening:

[0099] The material of the workpiece to be processed is nickel-based high-temperature alloy FGH96. The dimensions of the bottom hole 4 of the workpiece to be processed before strengthening are L0'=3.64mm, B0'=4.72mm. After strengthening, the dimensions of the special-shaped hole of the workpiece to be processed are L0=3.67mm, B0=4.75mm, and the depth is 5mm. Six specimens were selected from the workpiece to be processed before and after strengthening, and the tests were carried out under the same test conditions. Specifically, fatigue tests were carried out on each specimen on a fatigue testing machine, and the parameters of the fatigue test were set as: maximum nominal stress at the hole edge: 835Mpa, stress ratio: 0.1, loading frequency: 10Hz, test waveform: sine wave, test temperature: 680℃. Under the above test conditions, the fatigue life of the workpiece to be processed before and after strengthening is as follows Fig.14As shown in the figure, the average fatigue life of the workpiece before strengthening is 108262 cycles, and the average fatigue life of the workpiece after strengthening is 574708 cycles, which is 5.31 times the fatigue life of the workpiece before strengthening, that is, the strength of the hole structure has been significantly improved.

[0100] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An extrusion device for hole strengthening, characterized in that: It comprises a first extrusion mandrel and a second extrusion mandrel, wherein at least a portion of the outer side wall of the first extrusion mandrel can contact with the inner side wall of the first hole body of the bottom hole and extrude the inner side wall of the first hole body; and at least a portion of the outer side wall of the second extrusion mandrel can contact with the inner side wall of the first hole edge chamfer of the bottom hole and extrude the inner side wall of the first hole edge chamfer.

2. The extrusion device for hole strengthening according to claim 1, characterized in that: The first extrusion core rod includes an extrusion strengthening section, a strengthening holding section and an anti-rebound section connected in sequence, the shape of the outer wall of the strengthening holding section is the same as the shape of the inner wall of the second hole body of the target hole, and the size of the outer wall of the strengthening holding section is the same as the size of the inner wall of the second hole body; the outer edge of the end face of the extrusion strengthening section close to one end of the strengthening holding section is connected to the outer edge of the end face of the strengthening holding section close to one end of the extrusion strengthening section, the contour size of the extrusion strengthening section gradually decreases in the direction away from the strengthening holding section, and the contour size of the end of the extrusion strengthening section away from the strengthening holding section is smaller than the size of the first hole body; the outer edge of the end face of the anti-rebound section close to one end of the strengthening holding section is connected to the outer edge of the end face of the strengthening holding section close to one end of the anti-rebound section.

3. The extrusion device for hole strengthening according to claim 2, characterized in that: The outline size of the anti-rebound segment gradually decreases in a direction away from the reinforced retaining segment.

4. The extrusion device for hole strengthening according to claim 2, characterized in that: The extrusion reinforcement section and the anti-rebound section are symmetrical with respect to a middle cross section of the reinforcement holding section.

5. The extrusion device for hole strengthening according to claim 2, characterized in that: The second extrusion core rod includes a chamfered reinforcement section, and the angle between the two side edges of the longitudinal section of the chamfered reinforcement section and the center line of the chamfered reinforcement section is the same as the angle of the second hole edge chamfer of the target hole; the outer contour size of the end face of the small end of the chamfered reinforcement section is smaller than the inner contour size of the small end of the second hole edge chamfer, and the outer contour size of the end face of the large end of the chamfered reinforcement section is larger than the inner contour size of the large end of the second hole edge chamfer; the length of the chamfered reinforcement section is larger than the length of the hole section where the second hole edge chamfer is located.

6. The extrusion device for hole strengthening according to claim 5, characterized in that: The second extruded core rod also includes a strength reinforcement section, which is fixedly connected to the large end of the chamfered reinforcement section. The shape and outline dimensions of each cross section of the strength reinforcement section are respectively the same as the shape and outline dimensions of the large end face of the chamfered reinforcement section.

7. The extrusion device for hole strengthening according to claim 6, characterized in that: The outer side wall of the extrusion reinforcement section, the outer side wall of the reinforcement retention section, the outer side wall of the anti-rebound section, the outer side wall of the chamfer reinforcement section and the outer side wall of the strength reinforcement section are all provided with a lubricating coating.

8. A hole extrusion strengthening process based on the extrusion device for hole strengthening according to any one of claims 1 to 7, characterized in that: The steps include: Extrusion-strengthening the first hole body of the bottom hole: making the outer side wall of the first extrusion mandrel contact with the inner side wall of the first hole body of the bottom hole and extruding the inner side wall of the first hole body, so that the inner side wall of the first hole body generates elastic-plastic deformation; Extrusion strengthens the first hole edge chamfer of the bottom hole: the outer side wall of the second extrusion mandrel is brought into contact with the inner side wall of the first hole edge chamfer of the bottom hole and extrudes the inner side wall of the first hole edge chamfer, so that the inner side wall of the first hole edge chamfer undergoes elastic-plastic deformation.

9. The hole extrusion strengthening process according to claim 8, characterized in that: The first extrusion mandrel comprises an extrusion reinforcement section, a reinforcement holding section and an anti-rebound section connected in sequence, the shape of the outer side wall of the reinforcement holding section is the same as the shape of the inner side wall of the second hole body of the target hole, and the size of the outer side wall of the reinforcement holding section is the same as the size of the inner side wall of the second hole body; the outer edge of the end face of the extrusion reinforcement section close to one end of the reinforcement holding section is connected to the outer edge of the end face of the reinforcement holding section close to one end of the extrusion reinforcement section, the contour size of the extrusion reinforcement section gradually decreases in the direction away from the reinforcement holding section, and the contour size of the end of the extrusion reinforcement section away from the reinforcement holding section is smaller than the size of the first hole body; the outer edge of the end face of the anti-rebound section close to one end of the reinforcement holding section is connected to the outer edge of the end face of the reinforcement holding section close to one end of the anti-rebound section; The second extrusion mandrel comprises a chamfered reinforcement section, and the included angles between two side edges of the longitudinal section of the chamfered reinforcement section and the center line of the chamfered reinforcement section are the same as the angle of the second hole edge chamfer of the target hole; The method for extruding and strengthening the first hole body of the bottom hole comprises: controlling the first extrusion mandrel to continuously feed along the center line direction of the first hole body, so that the extrusion strengthening section, the strengthening holding section and the anti-rebound section pass through the first hole body in sequence, and completing one hole body extrusion strengthening; performing at least one hole body extrusion strengthening on the bottom hole until the inner contour size of the first hole body of the bottom hole after extrusion strengthening is within the size range of the inner contour of the second hole body of the target hole; The method for extrusion strengthening the first hole edge chamfer of the bottom hole comprises: controlling the second extrusion mandrel to continuously feed along the center line direction of the first hole body so that the outer side wall of the chamfer strengthening section extrude the first hole edge chamfer to complete one hole edge chamfer extrusion strengthening; performing at least one hole edge chamfer extrusion strengthening on the bottom hole.

10. The hole extrusion strengthening process according to claim 8, characterized in that: Also includes: Before and during extrusion strengthening of the first hole body of the bottom hole, lubricating oil is added between the outer side wall of the first extrusion mandrel and the inner side wall of the first hole body; Before and during the extrusion strengthening of the first hole edge chamfer of the bottom hole, lubricating oil is added between the outer side wall of the second extrusion mandrel and the inner side wall of the first hole edge chamfer; After the extrusion strengthening of the bottom hole is completed, the inner side wall of the first hole body and / or the inner side wall of the first hole edge chamfer is polished.

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