Extrusion device and hole extrusion strengthening process for hole strengthening

Abstract

The application discloses an extruding device and a hole extruding strengthening process for hole strengthening, relates to the technical field of hole processing, and the device comprises a first extruding mandrel and a second extruding mandrel. At least part of the outer side wall of the first extruding mandrel can extrude the inner side wall of the first hole body of the bottom hole. At least part of the outer side wall of the second extruding mandrel can extrude the inner side wall of the first hole edge chamfer of the bottom hole. The method comprises the following steps: the outer side wall of the first extruding mandrel is brought into contact with the inner side wall of the first hole body of the bottom hole, and the inner side wall of the first hole body is extruded to cause the inner side wall of the first hole body to produce elastic-plastic deformation; the outer side wall of the second extruding mandrel is brought into contact with the inner side wall of the first hole edge chamfer of the bottom hole, and the inner side wall of the first hole edge chamfer is extruded to cause the inner side wall of the first hole edge chamfer to produce elastic-plastic deformation. The application can improve the fatigue strength, stress resistance, corrosion resistance and fatigue resistance of a hole structure without changing the material and structural design and increasing the weight of parts, and the cost is low.

Description

TECHNICAL FIELD

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

[0002] Hole structures such as bolt holes, pin holes, and pressure equalizing holes are prone to stress concentration in application. For example, when the turbine disc and the compressor disc of an engine are working, the bolt holes, pin holes, and pressure equalizing holes on the disc are often high stress positions of the turbine disc due to stress concentration. Among them, the bolt holes are used for bolt connection and are often used for the connection between the turbine disc and the shaft of an aero-engine; the pressure equalizing holes of the turbine disc of an engine are common structures on the engine, which bear the functions of air passage and balancing the air pressure in the cavity before and after the disc. The weakening of the pressure equalizing holes and the bolt holes to the bearing capacity of the turbine disc will reduce the overall strength and service life of the structure. Stress concentration at the hole edge often leads to radial crack failure, which has a significant impact on the service life of the turbine disc.

[0003] For the stress concentration problem of hole structures such as pressure equalizing holes and bolt holes, special-shaped non-circular holes can be designed to optimize the stress distribution at the hole edge, and processes such as machining hole edge chamfering and polishing the hole can be used for optimization, and sometimes the pressure equalizing holes are directly cancelled. However, the treatment methods such as machining hole edge chamfering and polishing the hole have very limited effect on relieving the stress concentration of the hole, and cancelling the pressure equalizing holes will affect the balancing effect of the air pressure in the cavity before and after the turbine disc. SUMMARY

[0004] The purpose of the present application is to provide an extrusion device for hole strengthening and a hole extrusion strengthening process to solve the problems existing in the 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 structure design, not increasing the weight of the parts, low cost, obvious strengthening effect, etc.

[0005] To achieve the above purpose, the present application provides the following solutions:

[0006] The present application provides an extrusion device for hole strengthening, which comprises a first extrusion mandrel and a second extrusion mandrel. At least part of the outer side wall of the first extrusion mandrel can be in 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. At least part of the outer side wall of the second extrusion mandrel can be in 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.

[0007] Preferably, the first extrusion mandrel 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 near the strengthening holding section is connected to the outer edge of the end face of the strengthening holding section near the extrusion strengthening section. The outline size of the extrusion strengthening section gradually decreases along the direction away from the strengthening holding section, and the outline 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 near the strengthening holding section is connected to the outer edge of the end face of the strengthening holding section near the anti-rebound section.

[0008] Preferably, the anti-rebound section gradually decreases in size along the direction away from the reinforced retaining section.

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

[0010] Preferably, the second extrusion mandrel includes a chamfered strengthening section, wherein the angle between the two sides of the longitudinal section of the chamfered strengthening section and the center line of the chamfered strengthening section is the same as the angle of the second hole edge chamfer of the target hole; the outer contour dimension of the small end face of the chamfered strengthening 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 large end face of the chamfered strengthening section is larger than the inner contour dimension of the large end of the second hole edge chamfer; the length of the chamfered strengthening section is greater than the length of the hole segment where the second hole edge chamfer is located.

[0011] Preferably, the second extruded mandrel further includes a strength reinforcing section, which is fixedly connected to the large end of the chamfering strengthening section, and the shape and contour dimensions of each cross section of the strength reinforcing section are the same as the shape and contour dimensions of the large end face of the chamfering strengthening section.

[0012] Preferably, a lubricating coating is provided on the outer wall of the extrusion strengthening section, the outer wall of the strengthening and retaining section, the outer wall of the anti-rebound section, the outer wall of the chamfering strengthening section, and the outer wall of the strength reinforcing section.

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

[0014] The first hole body of the bottom hole is reinforced by extrusion: the outer wall of the first extrusion mandrel contacts the inner wall of the first hole body of the bottom hole and extrudes the inner wall of the first hole body, causing the inner wall of the first hole body to undergo elastoplastic deformation.

[0015] Extrusion reinforcement of the first hole edge chamfer of the bottom hole: the outer wall of the second extrusion mandrel contacts the inner wall of the first hole edge chamfer of the bottom hole and extrudes the inner wall of the first hole edge chamfer, causing the inner wall of the first hole edge chamfer to undergo elastoplastic deformation.

[0016] Preferably, the first extrusion mandrel 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 near the strengthening holding section is connected to the outer edge of the end face of the strengthening holding section near the extrusion strengthening section. The outline size of the extrusion strengthening section gradually decreases along the direction away from the strengthening holding section, and the outline 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 near the strengthening holding section is connected to the outer edge of the end face of the strengthening holding section near the anti-rebound section.

[0017] The second extrusion mandrel includes a chamfered strengthening section, wherein the angle between the two sides of the longitudinal section of the chamfered strengthening section and the center line of the chamfered strengthening section is the same as the angle of the chamfer on the second edge of the target hole;

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

[0019] The method for extruding and strengthening the first hole edge chamfer of the bottom hole includes: controlling the second extrusion mandrel to continuously feed along the center line direction of the first hole body, so that the outer wall of the chamfer strengthening section extrudes the first hole edge chamfer, completing one hole edge chamfering and strengthening; and performing at least one hole edge chamfering and strengthening on the bottom hole.

[0020] Preferred options also include:

[0021] Before and during the 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 bottom hole is extruded and strengthened, the inner wall of the first hole body and / or the inner wall of the chamfered edge of the first hole are polished.

[0024] The present invention achieves the following technical effects compared to the prior art:

[0025] This invention provides an extrusion apparatus and a hole extrusion strengthening process for hole strengthening, comprising a first extrusion mandrel and a second extrusion mandrel. At least a portion of the outer wall of the first extrusion mandrel can contact and compress the inner wall of the first hole body of the bottom hole; at least a portion of the outer wall of the second extrusion mandrel can contact and compress the inner wall of the chamfered edge of the first hole. By compressing the inner wall of the first hole body with the first extrusion mandrel, elastoplastic deformation can be generated at the inner wall of the first hole body. By compressing the inner wall of the chamfered edge of the first hole with the second extrusion mandrel, elastoplastic deformation can be generated at the inner wall of the chamfered edge of the first hole. The generation of elastoplastic deformation can introduce a deep, high-amplitude, and controllable residual compressive stress layer into the hole wall, improving the distribution of local stress at the hole edge under external load, and significantly improving the fatigue strength, stress resistance, corrosion resistance, and fatigue resistance of the hole structure. It has advantages such as not changing the material, not changing the structural design, not increasing the weight of the part, low cost, and significant strengthening effect. This invention not only strengthens the first hole body of the bottom hole, but also strengthens the chamfer of the first hole edge, making up for the weakness of the first hole edge chamfer and further improving the strengthening effect of the hole. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the structure of the first extrusion mandrel provided in Example 1;

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

[0029] Figure 3 for Figure 2 The left view;

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

[0031] Figure 5 This is a schematic diagram of the structure of the second extrusion mandrel provided in Example 1;

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

[0033] Figure 7 for Figure 6 The left view;

[0034] Figure 8 for Figure 6 Sectional view of BB;

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

[0036] Figure 10 for Figure 9 Sectional view of CC;

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

[0038] Figure 12 for Figure 11 Sectional view of DD;

[0039] Figure 13 A schematic diagram of the structure of a perforated extrusion strengthening machine body;

[0040] Figure 14 A comparison chart of the lifetimes of reinforced and unreinforced samples;

[0041] Figure 15 This is 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 mandrel; 201, extrusion strengthening section; 202, strengthening and holding section; 203, anti-springback section; 204, first side; 205, first clamping section; 3, second extrusion mandrel; 301, chamfering strengthening section; 302, strength reinforcing section; 303, second side; 304, second clamping section; 4, bottom hole; 401, first hole body; 402, first hole edge chamfer; 5, target hole; 501, second hole body; 502, second hole edge chamfer. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] The purpose of this invention is to provide an extrusion device and a pore extrusion strengthening process for pore strengthening, so as to solve the problems existing in the prior art, and significantly improve the fatigue strength, stress resistance, corrosion resistance and fatigue resistance of pore structures. It 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.

[0045] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be 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 sidewall of the first extrusion mandrel 2 can contact and extrude the inner sidewall of the first hole body 401 of the bottom hole 4. The bottom hole 4 refers to a hole pre-machined during the machining process for subsequent processing (such as tapping, reaming, etc.). At least a portion of the outer sidewall of the second extrusion mandrel 3 can contact and extrude the inner sidewall of the first hole edge chamfer 402 of the bottom hole 4. By pressing the inner wall of the first hole body 401 with the first extrusion mandrel 2, elastoplastic deformation can be generated at the inner wall of the first hole body 401. By pressing the inner wall of the first hole edge chamfer 402 with the second extrusion mandrel 3, elastoplastic deformation can be generated at the inner wall of the first hole edge chamfer 402. The generation of elastoplastic deformation can introduce a deep, high-amplitude, and controllable residual compressive stress layer into the hole wall, improve the distribution of local stress at the hole edge under external load, and significantly 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. In this embodiment, not only the first hole body 401 of the bottom hole 4 is strengthened, but also the first hole edge chamfer 402 of the bottom hole 4 is strengthened, making up for 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 near the strengthening holding section 202 is connected to the outer edge of the end face of the strengthening holding section 202 near the extrusion strengthening section 201. That is, the outer contour size and shape of the end face of the extrusion strengthening section 201 near the strengthening holding section 202 are respectively close to the outer edge of the strengthening holding section 202. The outer contour dimensions and shape of the end face of the extrusion-strengthened section 201 are the same. The contour dimensions of the extrusion-strengthened section 201 gradually decrease along the direction away from the strengthening and holding section 202. The contour dimension of the end face of the extrusion-strengthened section 201 away from the strengthening and 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 near the strengthening and holding section 202 is connected to the outer edge of the end face of the strengthening and holding section 202 near the anti-rebound section 203. That is, the outer contour dimensions and shape of the end face of the anti-rebound section 203 near the strengthening and holding section 202 are the same as the outer contour dimensions and shape of the end face of the strengthening and holding section 202 near the extrusion-strengthened section 201.

[0049] In this embodiment, the dimensions of the first extrusion mandrel 2 and the second extrusion mandrel 3 can be designed according to the outline dimensions and extrusion amount of the bottom hole 4 to be strengthened. After removing the extrusion amount, the outline dimensions of the bottom hole 4 can be used to obtain the target hole 5. The design principle is that the outline dimension of the end face of the extrusion strengthening section 201 away from the strengthening holding section 202 is smaller than the dimension of the first hole body 401. That is, the outer outline of the end face of the extrusion strengthening section 201 away from the strengthening holding section 202 can be completely placed inside the first hole body 401, ensuring that the small end of the extrusion strengthening section 201 can extend into the first hole body 401. The outline dimensions of the large end face of the extrusion strengthening section 201 are the same as the outline dimensions of any cross-section of the strengthening and holding section 202, and also the outline dimensions of any cross-section of the target hole 5, so that the extrusion strengthening section 201 and the strengthening and holding section 202 can transition well and gradually compress and expand the first hole body 401. After one extrusion by the strengthening and holding section 202, the target hole 501 will not be obtained directly, but a certain amount of springback will occur. At this time, the anti-springback section 203 can play a certain role in hindering the springback of the first hole body 401. After multiple extrusion strengthenings, the outline dimensions of the first hole body 401 can meet the design requirements of the outline dimensions of the target hole 5.

[0050] In this embodiment, the anti-rebound section 203 gradually decreases in size along the direction away from the reinforced retaining section 202, and the portion of the anti-rebound section 203 near the reinforced retaining section 202 has a certain hindering effect on the rebound of the first hole body 401.

[0051] In a preferred embodiment, the two sides (first side 204) of any longitudinal section of the extrusion-strengthened section 201 and the anti-rebound section 203 are inclined straight lines. For example, the extrusion-strengthened section 201 and the anti-rebound section 203 can be conical.

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

[0053] In this embodiment, the second extrusion mandrel 3 includes a chamfered strengthening section 301. The angle between the two sides (second side 303) of the longitudinal section of the chamfered strengthening section 301 and the center line of the chamfered strengthening 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 small end face of the chamfered strengthening 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 large end face of the chamfered strengthening 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 strengthening section 301 is greater than the length of the hole segment where the second hole edge chamfer 502 is located. This ensures that the outer side wall of the chamfered strengthening section 301 can fully contact the inner side wall of the hole segment where the second hole edge chamfer 502 is located, so as to achieve extrusion strengthening of the second hole edge chamfer 502.

[0054] In this embodiment, the second extrusion mandrel 3 further includes a strength reinforcing section 302, which is fixedly connected to the large end of the chamfering reinforcement section 301. The shape and contour dimensions of each cross section of the strength reinforcing section 302 are the same as the shape and contour dimensions of the large end face of the chamfering reinforcement section 301. The strength reinforcing section 302 is positioned between the chamfering reinforcement section 301 and the second clamping section 304 to serve as a transition, dispersing the axial force during the extrusion process and improving the strength of the second extrusion mandrel 3.

[0055] In a preferred embodiment, the length of the strength-reinforcing section 302 is greater than the length of the chamfering reinforcement section 301, which can improve the stress distribution inside the chamfering reinforcement section 301 and the strength-reinforcing section 302 and improve the overall strength of the second extrusion mandrel 3.

[0056] In this embodiment, a lubricating coating is provided on the outer walls of the extrusion strengthening section 201, the strengthening and retaining section 202, the anti-rebound section 203, the chamfering strengthening section 301, and the strength reinforcing section 302. The lubricating coating is preferably a diamond-like carbon 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 extrusion mandrel 2 further includes a first clamping section 205, which is fixedly connected to the end of the anti-rebound section 203 away from the reinforcing retaining section 202; the second extrusion mandrel 3 further includes a second clamping section 304, which is fixedly connected to the end of the strength reinforcing section 302 away from the chamfering reinforcing section 301. The external 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 reinforcing retaining section 202 is half the length of the extrusion reinforcing section 201.

[0059] This embodiment also includes a hole extrusion strengthening machine body, which includes a drive device and a spindle. One end of the spindle is connected to the drive device, and the other end of the spindle can be detachably and fixedly connected to the first clamping section 205 or the second clamping section 304. The drive device can drive the first clamping section 205 or the second clamping section 304 to move bidirectionally along the spindle axis by driving the spindle to feed bidirectionally along the spindle axis. As a preferred embodiment, the feed straightness error of the spindle is less than 0.01 mm, and the axial feed tensile and compressive forces are not less than 10 kN. The drive device is preferably a motor.

[0060] The extrusion apparatus 100 for hole strengthening in this embodiment can be used for extrusion strengthening of holes of various shapes and sizes, and in particular provides a feasible strengthening method for processing irregular deep holes. It can especially realize extrusion strengthening of materials at high temperatures, for example, it can be used for processing irregular holes on high-temperature nickel-based alloy parts.

[0061] Example 2

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

[0063] The first hole body 401 of the extrusion-strengthened bottom hole 4 is made to contact the outer side wall of the first extrusion mandrel 2 with the inner side wall of the first hole body 401 of the bottom hole 4 and extrude the inner side wall of the first hole body 401, so that the inner side wall of the first hole body 401 undergoes elastic-plastic deformation.

[0064] The first hole edge chamfer 402 of the extrusion-strengthened bottom hole 4 is made to contact the inner side wall of the first hole edge chamfer 402 of the bottom hole 4 and extrude the inner side wall of the first hole edge chamfer 402, so that the inner side wall of the first hole edge chamfer 402 undergoes elastic-plastic deformation.

[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 near the strengthening holding section 202 is connected to the outer edge of the end face of the strengthening holding section 202 near the extrusion strengthening section 201, that is, the extrusion strengthening section 201 near the strengthening holding section 202 is connected to the outer edge of the end face of the strengthening holding section 202 near the extrusion strengthening section 201. The outer contour dimensions and shape of the end face of one end of the reinforced retaining section 202 are the same as the outer contour dimensions and shape of the end face of the reinforced retaining section 202 near the end of the extrusion reinforced section 201. The contour dimension of the extrusion reinforced section 201 gradually decreases along the direction away from the reinforced retaining section 202. The contour dimension of the end face of the extrusion reinforced section 201 away from the reinforced retaining 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 near the end of the reinforced retaining section 202 is connected to the outer edge of the end face of the reinforced retaining section 202 near the end of the anti-rebound section 203.

[0066] The second extrusion mandrel 3 includes a chamfered strengthening section 301. The angle between the two sides of the longitudinal section of the chamfered strengthening section 301 and the center line of the chamfered strengthening 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 includes: controlling the first extrusion mandrel 2 to continuously feed along the centerline direction of the first hole body 401, so that the extrusion strengthening section 201, the strengthening holding section 202 and the anti-springback section 203 pass through the first hole body 401 in sequence to complete one hole body extrusion strengthening; performing at least one hole body extrusion strengthening on the bottom hole 4 until the inner contour dimension of the first hole body 401 of the bottom hole 4 after extrusion strengthening is within the inner contour dimension range of the second hole body 501 of the target hole 5;

[0068] The method for extrusion strengthening of the first hole edge chamfer 402 of the bottom hole 4 includes: 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 extrudes the first hole edge chamfer 402, completing one hole edge chamfering extrusion strengthening; performing at least one hole edge chamfering extrusion strengthening on the bottom hole 4 until the inner contour dimension of the first hole edge chamfer 402 of the bottom hole 4 after extrusion strengthening is within the inner contour dimension range of the second hole edge chamfer 502 of the target hole 5.

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

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

[0071] 1. Preparation of an extrusion apparatus 100 for pore strengthening

[0072] The extrusion amount is determined based on the inner contour dimensions (such as the hole diameter) and extrusion ratio of the target hole 5. The corresponding first extrusion mandrel 2 and second extrusion mandrel 3 are designed and processed according to the extrusion amount. The following conditions must be met: the contour dimension of the end face of the extrusion strengthening section 201 away from the strengthening holding section 202 is smaller than the dimension of the first hole body 401; the contour dimension of the large end face of the extrusion strengthening section 201 is the same as the contour dimension of any cross-section of the strengthening holding section 202, and is the same as the contour dimension of any cross-section of the target hole 5; the extrusion strengthening section 201 and the anti-rebound section 203 are symmetrical about the middle cross-section of the strengthening holding section 202.

[0073] 2. Machining of the outer shape and bottom hole 4 of the workpiece

[0074] 3. Bottom hole 4 extrusion strengthening

[0075] 3.1 The first hole body 401 is strengthened by extrusion using the first extrusion mandrel 2.

[0076] 3.2 The first hole edge chamfer 402 is reinforced by extrusion using the second extrusion mandrel 3.

[0077] 3.3 Polish the inner wall of the reinforced first hole body 401 and / or the inner wall of the first hole edge chamfer 402.

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

[0079] (1) Install the workpiece to be processed on the special bottom hole fixture of the machine tool worktable, and install the first extrusion mandrel 2 and the second extrusion mandrel 3 into the machine tool magazine;

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

[0081] (3) Extrusion strengthening of the first hole body 401: After fixing the first extrusion mandrel 2 to the main shaft, control the main shaft to slowly feed along the Z-axis through the bottom hole 4 until the extrusion strengthening section 201, the strengthening holding section 202, and the anti-springback section 203 completely pass through the first hole body 401, thus completing the extrusion strengthening of the first hole body 401. It is crucial to avoid stopping during the extrusion process, otherwise, it may cause the mandrel to jam. After extrusion is completed, the hole diameter should be measured promptly to determine if it is within a reasonable range; if it does not meet the requirements, extrusion should be performed again.

[0082] (4) Extrusion strengthening of the first hole edge chamfer 402: Remove the first extrusion mandrel 2 from the main shaft and replace it with the second extrusion mandrel 3. After fixing the second extrusion mandrel 3 to the main shaft, first make the outer wall of the chamfer strengthening section 301 fit against the inner wall of the first hole edge chamfer 402 but not under force. Then, control the main shaft to descend by 0.02mm through the motor to achieve extrusion of the first hole edge chamfer 402. Repeat the above steps multiple times to ensure the strengthening effect;

[0083] (5) Polish the inner wall of the reinforced first hole body 401 and / or the inner wall of the first hole edge chamfer 402.

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

[0085] The extrusion apparatus 100 for hole strengthening in this embodiment can be used for extrusion strengthening of holes of various shapes and sizes, such as... Figures 11 to 12 Taking the irregularly shaped hole shown as an example, this hole consists of six pairs of symmetrical circular arcs, with adjacent arcs being tangent to each other. The key dimensions of this irregularly shaped hole are R1, R2, R3, L0, and B0. R1, R2, and R3 determine the shape of the non-circular hole, while L0 and B0 determine the size and extrusion amount. The size of the bottom hole 4 required for extrusion strengthening is determined by equidistantly reducing L0 and B0 according to the extrusion amount, i.e.:

[0086] δ=2*(L0-L0')=2*(B0-B0'),

[0087] Where δ is the extrusion amount, L0 and B0 are the minor axis and major axis dimensions of the target hole 5, and L0' and B0' are the minor axis and major axis dimensions of the bottom hole 4.

[0088] The shape of the workpiece to be processed is the same as that of the irregular hole, and the reinforced retaining section 202 also has key dimensions R1, R2, R3, L0, and B0. For this workpiece, the processing methods for its shape and the bottom hole 4 include:

[0089] 2.1. Blanking: Perform the first rough machining on the short shaft dimension, long shaft dimension, and thickness of the blank, with a single-sided cutting amount of 0.5mm, to obtain the first rough blank;

[0090] 2.2. Perform a second roughing process on the first rough blank, cutting six circular arcs of the outer contour of the workpiece, with a single-sided cutting amount of 0.5 mm, to obtain the second rough blank;

[0091] 2.3. The short shaft dimensions and thickness of the second rough blank are precision machined by grinding to ensure that the short shaft dimensions and thickness of the second rough blank are within the dimensional tolerances of the drawing, thus obtaining the first precision blank;

[0092] 2.4. Perform finishing on the length of the first blank and the six arc segments of the outer contour of the workpiece to meet the dimensional tolerance requirements of the drawing; obtain the second blank.

[0093] 2.5. Rough mill the irregular hole on the second blank, with a removal amount of 0.25mm on one side;

[0094] 2.6. Perform precision milling on the irregular hole from step 2.6, with a removal amount of 0.05mm on one side;

[0095] 2.7. Perform fine milling on the irregular holes from step 2.7 again to meet the dimensional tolerance requirements of the drawing;

[0096] 2.8. Chamfer the first hole edge with 402 at both ends of the irregular hole.

[0097] As one feasible implementation, 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 were conducted on the workpieces before and after strengthening:

[0099] The material of the workpiece to be processed is nickel-based superalloy FGH96. Before strengthening, the dimensions of the bottom hole 4 of the workpiece are L0' = 3.64 mm and B0' = 4.72 mm. After strengthening, the dimensions of the irregular hole of the workpiece are L0 = 3.67 mm, B0 = 4.75 mm, and the depth is 5 mm. Six specimens were selected from both the workpiece before and after strengthening, and tests were conducted under the same conditions. Specifically, fatigue tests were performed on each specimen on a fatigue testing machine. The fatigue test parameters were set as follows: maximum nominal stress at the hole edge: 835 MPa, stress ratio: 0.1, loading frequency: 10 Hz, test waveform: sine wave, test temperature: 680℃. Under the above test conditions, the fatigue life of the workpiece before and after strengthening is as follows: Figure 14As shown, the average fatigue life of the workpiece before strengthening was 108,262 cycles, while the average fatigue life of the workpiece after strengthening was 574,708 cycles, which is 5.31 times that of the workpiece before strengthening, indicating that the strength of the hole structure was significantly improved.

[0100] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. An extrusion apparatus for pore strengthening, characterized in that: It includes a first extrusion mandrel and a second extrusion mandrel. At least a portion of the outer sidewall of the first extrusion mandrel can contact and extrude the inner sidewall of the first hole body of the bottom hole. At least a portion of the outer sidewall of the second extrusion mandrel can contact and extrude the inner sidewall of the chamfered edge of the first hole of the bottom hole. The first extrusion mandrel 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 near the strengthening holding section is connected to the outer edge of the end face of the strengthening holding section near the extrusion strengthening section. The outline size of the extrusion strengthening section gradually decreases along the direction away from the strengthening holding section, and the outline 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 near the strengthening holding section is connected to the outer edge of the end face of the strengthening holding section near the anti-rebound section. The second extrusion mandrel includes a chamfered strengthening section. The angle between the two sides of the longitudinal section of the chamfered strengthening section and the center line of the chamfered strengthening section is the same as the angle of the second hole edge chamfer of the target hole. The outer contour dimension of the small end face of the chamfered strengthening section is smaller than the inner contour dimension of the small end of the second hole edge chamfer. The outer contour dimension of the large end face of the chamfered strengthening section is larger than the inner contour dimension of the large end of the second hole edge chamfer. The length of the chamfered strengthening section is greater than the length of the hole segment where the second hole edge chamfer is located.

2. The extrusion apparatus for pore strengthening according to claim 1, characterized in that: The anti-rebound section gradually decreases in size along the direction away from the reinforced retaining section.

3. The extrusion apparatus for pore strengthening according to claim 1, characterized in that: The extrusion-strengthening section and the anti-rebound section are symmetrical about the middle cross section of the strengthening and retaining section.

4. The extrusion apparatus for pore strengthening according to claim 1, characterized in that: The second extruded mandrel also includes a strength reinforcing section, which is fixedly connected to the large end of the chamfering strengthening section. The shape and contour dimensions of each cross section of the strength reinforcing section are the same as the shape and contour dimensions of the large end face of the chamfering strengthening section.

5. The extrusion apparatus for pore strengthening according to claim 4, characterized in that: A lubricating coating is provided on the outer wall of the extrusion strengthening section, the outer wall of the strengthening and retaining section, the outer wall of the anti-rebound section, the outer wall of the chamfering strengthening section, and the outer wall of the strength reinforcing section.

6. A pore extrusion strengthening process based on the extrusion apparatus for pore strengthening according to any one of claims 1 to 5, characterized in that: Includes the following steps: The first hole body of the bottom hole is reinforced by extrusion: the outer wall of the first extrusion mandrel contacts the inner wall of the first hole body of the bottom hole and extrudes the inner wall of the first hole body, causing the inner wall of the first hole body to undergo elastoplastic deformation. Extrusion reinforcement of the first hole edge chamfer of the bottom hole: the outer wall of the second extrusion mandrel contacts the inner wall of the first hole edge chamfer of the bottom hole and extrudes the inner wall of the first hole edge chamfer, causing the inner wall of the first hole edge chamfer to undergo elastoplastic deformation.

7. The hole extrusion strengthening process according to claim 6, characterized in that: The first extrusion mandrel 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 near the strengthening holding section is connected to the outer edge of the end face of the strengthening holding section near the extrusion strengthening section. The outline size of the extrusion strengthening section gradually decreases along the direction away from the strengthening holding section, and the outline 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 near the strengthening holding section is connected to the outer edge of the end face of the strengthening holding section near the anti-rebound section. The second extrusion mandrel includes a chamfered strengthening section, wherein the angle between the two sides of the longitudinal section of the chamfered strengthening section and the center line of the chamfered strengthening section is the same as the angle of the chamfer on the second edge of the target hole; The method for extruding and strengthening the first hole body of the bottom hole includes: controlling the first extrusion mandrel to continuously feed along the centerline direction of the first hole body, so that the extrusion strengthening section, the strengthening holding section and the anti-springback section pass through the first hole body in sequence to complete one hole body extrusion strengthening; performing at least one hole body extrusion strengthening on the bottom hole until the inner contour dimension of the first hole body of the bottom hole after extrusion strengthening is within the inner contour dimension of the second hole body of the target hole; The method for extruding and strengthening the first hole edge chamfer of the bottom hole includes: controlling the second extrusion mandrel to continuously feed along the center line direction of the first hole body, so that the outer wall of the chamfer strengthening section extrudes the first hole edge chamfer, completing one hole edge chamfering and strengthening; and performing at least one hole edge chamfering and strengthening on the bottom hole.

8. The hole extrusion strengthening process according to claim 7, characterized in that: Also includes: Before and during the 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 bottom hole is extruded and strengthened, the inner wall of the first hole body and / or the inner wall of the chamfered edge of the first hole are polished.

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