A hole rolling strengthening device and a hole rolling strengthening method

Abstract

The application provides an inner hole roll strengthening device and method, aiming at solving the problems of traditional technology hole wall tensile injury, strengthening layer shallow and the like. The device comprises a shell, a stroke mechanism, a rotating mechanism, a roll pressing tool and a fixing mechanism, the roll pressing tool comprises a mandrel, a cage with a needle and a thrust bearing, and the lower end of the mandrel is provided with a polished rod cylindrical section and a small inclination taper section. The cage with the needle is arranged in the hole in advance, then the polished rod cylindrical section at the lower end of the mandrel is extruded into the cage and rotated, the needle is driven to rotate in the hole through the cooperation of the mandrel and the cage, so that the high level and large depth of the strengthening effect is obtained on the surface of the connecting hole with a large tool interference, the fatigue resistance of the connecting hole is significantly improved, the operation is simple, and the device is suitable for the strengthening of connecting holes of various metal components.

Description

Technical Field

[0001] This invention relates to the strengthening treatment of the inner hole of a workpiece, specifically to an inner hole rolling strengthening device and an inner hole rolling strengthening method. Background Technology

[0002] Currently, many mechanical structures still primarily use rivets or bolts as fasteners, resulting in a large number, variety, and wide distribution of fastener connection holes. Due to stress concentration at the hole edges, fastener connection holes are often weak points in mechanical structures. Taking aircraft as an example, statistics show that over 80% of aircraft structural fractures are caused by fatigue failure around fastener connection holes. Therefore, enhancing the fatigue resistance of fastener connection holes is crucial for improving the service life and safety of mechanical structures.

[0003] Currently, surface deformation strengthening technology is widely used in the machinery manufacturing industry to improve the fatigue resistance of fastener connection holes. The most mature and widely applied surface deformation strengthening technologies for connection holes mainly fall into three categories: cold extrusion, shot peening, and rolling. However, all three of these traditional surface deformation strengthening technologies for connection holes have significant limitations:

[0004] (1) The mandrel and connecting hole used in cold extrusion technology are in conformal contact, with huge sliding friction, which can easily cause hole wall scratches. Moreover, the better the strengthening effect (the greater the tool interference), the more likely the hole wall will be scratched. Although the above problems have been alleviated to some extent with the use of slotted bushing technology, new problems such as bushing consumption, secondary reaming of hole wall, and radial cracking at the hole exit end have emerged one after another.

[0005] (2) The shot peening technology for connecting holes not only inherited the "old problems" of low surface finish and easy contamination of the strengthened surface by shot peening of the outer surface, but also produced new problems such as poor accessibility inside the hole;

[0006] (3) Existing hole rolling technology mainly uses small tool interference to perform surface finishing on the hole wall, resulting in a shallow reinforcement layer and very limited improvement in fatigue resistance. Therefore, it is urgent to explore and develop new technologies for surface deformation strengthening of fastener connecting holes that are highly smooth, deep, crack-free, and highly fatigue-resistant, in order to avoid secondary reaming, suppress cracking on the hole edge and inner surface, improve the hole wall strengthening effect, and enhance the fatigue resistance of the components. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide an internal hole rolling strengthening device and an internal hole rolling strengthening method. By pre-arranging a cage with roller needles in the hole, and then squeezing a mandrel with a small-angle taper section into the cage and rotating it, the mandrel and the cage cooperate to drive the roller needles to rotate in the hole, thereby obtaining a high-level and deep strengthening effect on the surface of the connecting hole with a large amount of tool interference, significantly improving the fatigue resistance of the connecting hole.

[0008] An internal hole rolling strengthening device is used to roll strengthen the inner surface of a through-hole of a workpiece. The strengthening device includes a housing, a stroke mechanism, a rotation mechanism, a rolling tool, and a fixing mechanism.

[0009] The housing includes a base plate and an adjustable limit switch located at the end of the base plate;

[0010] The stroke mechanism is fixed above the housing and is used to provide axial feed power to the rotary mechanism. The rotary mechanism stops feeding when it contacts the adjustable limit switch.

[0011] The rotating mechanism is installed inside the housing and connected to the stroke mechanism to provide the rotational driving force for the rolling tool;

[0012] The rolling tool includes a mandrel, a cage with multiple needle rollers, and a thrust bearing. The cage passes through and is installed in the inner hole of the thrust bearing with an interference fit. The cage has several axial through slots along its circumference. Cylindrical needle rollers that axially pass through the inner hole are installed in the axial through slots. The upper end of the mandrel is connected to a rotating mechanism. The lower end of the mandrel has a slender rod that axially slides through the cage and is axially in contact with all the needle rollers. The upper section of the slender rod is a smooth cylindrical section, and the lower section is a small-angle taper section with a decreasing diameter from top to bottom. When the small-angle taper section contacts the needle rollers, there is a gap between the needle rollers and the inner wall of the workpiece's inner hole. When the smooth cylindrical section contacts the needle rollers, there is an interference fit between the needle rollers and the inner wall of the inner hole.

[0013] The fixing mechanism is fixedly connected to the base plate, and the fixing mechanism is equipped with a perforated workpiece support plate for supporting the workpiece.

[0014] Furthermore, the stroke mechanism is a hydraulically driven mechanism, including a cylinder and a stroke driver, the end of which is connected to the rotary mechanism.

[0015] Furthermore, the rotating mechanism includes: a rotating driver mounting bracket, a rotating driver upper cover plate, a rotating driver base plate, a guide rail, a rotating driver, a connector housing, and a connector end cap;

[0016] The rotary actuator mounting bracket is encapsulated by the rotary actuator upper cover plate and the rotary actuator bottom plate to form a rotary actuator accommodating space. The rotary actuator mounting bracket is provided with a guide rail for sliding axially with the housing. The rotary actuator upper cover plate is fixedly connected to the stroke mechanism.

[0017] The rotary actuator is fixedly installed inside the rotary actuator accommodating space;

[0018] One end of the connector housing is connected to the output shaft of the rotary driver, and the other end is provided with a connector end cap. The connector end cap has an inner hole in the center for receiving the mandrel so as to transmit torque to the rolling tool.

[0019] Furthermore, the fixing mechanism also includes a fixing bracket, a connecting plate, and a lower support structure;

[0020] The upper end face of the cylindrical fixed bracket is fixedly connected to the base plate, and the lower end face of the fixed bracket is fixedly connected to the lower support structure through an annular connecting plate.

[0021] The workpiece support plate is fixedly installed on the lower surface of the connecting plate by tightening bolts, and the upper surface of the workpiece is attached to the lower surface of the connecting plate.

[0022] Furthermore, a shallow groove for placing the workpiece is provided at the center of the upper surface of the workpiece pallet. The size of the shallow groove is larger than the size of the workpiece, and the depth of the shallow groove is less than the thickness of the workpiece by 3 mm.

[0023] Furthermore, the mandrel is composed of an upper connector, a tapered connector, a smooth cylindrical section, and a small-angle tapered section, all integrally formed from top to bottom.

[0024] The upper connector is used for fixed connection with the connector end cap. The upper connector is provided with an annular groove and a radial through hole located below the annular groove.

[0025] The upper connector is fixedly connected to the cylindrical section of the smooth rod via a tapered connector.

[0026] Furthermore, the axial length of the smooth cylindrical section is greater than or equal to 1.2 times the axial length of the needle roller.

[0027] Furthermore, the diameter of the needle roller is 1 / 4 of the inner bore diameter.

[0028] The upper end diameter of the small-angle taper section is equal to the diameter of the smooth cylindrical section, both being 1 / 2 of the inner hole diameter plus the tool interference δ. The lower end diameter of the small-angle taper section is less than 1 / 2 of the inner hole diameter.

[0029] A method for strengthening a connecting hole using the aforementioned connecting hole rolling strengthening device includes the following steps:

[0030] S1. Preparatory steps: Select the appropriate rolling tool according to the inner diameter to be strengthened and the required tool interference amount δ, and fix the mandrel to the rotating mechanism and adjust the height of the limit switch.

[0031] S2. Workpiece and cage clamping: Lower the workpiece support plate of the fixing mechanism, place the workpiece in the shallow groove on the workpiece support plate, and insert the cage and its needle rollers into the inner hole from top to bottom in advance so that the thrust bearing base fits against the upper surface of the workpiece.

[0032] S3. Initial centering and positioning: Raise the workpiece support plate so that the small-angle taper section of the mandrel is initially inserted into the cage, making uniform initial contact with all the needle rollers on the cage, and forcing the workpiece to move freely in a small range in the shallow groove on the workpiece support plate, so as to achieve coaxiality alignment between the rolling tool and the inner hole on the workpiece. Then lock the workpiece support plate.

[0033] S4. Mandrel Extrusion Reinforcement: The start-up stroke mechanism drives the mandrel to feed downwards at a constant speed. The small-angle taper section pushes all the needle rollers radially away and gradually presses them into the inner wall of the bore.

[0034] After the limit switch sensing cage moves to the designated position, the feed stops. At this point, the cylindrical section of the smooth rod is in complete contact with all the side walls of the needle rollers.

[0035] S5. Start the rotating mechanism to drive the mandrel to rotate a preset number of times or a preset time, and then automatically stop the machine. During this process, the rotational friction of the mandrel drives each needle roller to rotate, and at the same time drives the cage to rotate so that the needle rollers can revolve around the mandrel, thereby achieving rolling and strengthening of the inner hole wall.

[0036] S6. Start the stroke mechanism to drive the spindle to withdraw axially at a uniform speed, so that the spindle slowly and evenly disengages from all the needle rollers and is gradually pulled upward from the cage.

[0037] S7. Remove the workpiece.

[0038] The technical advantages of this invention are as follows:

[0039] 1. By adopting the "first-laying needle rollers + mandrel extrusion and rotation" mode, the hole wall is plastically deformed to a greater depth with a large tool interference, resulting in a deeper reinforcement layer and significantly improving the fatigue resistance of the inner hole, far exceeding the traditional rolling technology.

[0040] 2. The needle rollers and the hole wall use non-conformal rolling friction, which replaces the sliding friction of traditional cold extrusion, greatly reducing the risk of hole wall scratches. After strengthening, the hole wall is smooth and flat with low surface roughness, and no secondary finishing treatment is required.

[0041] 3. No bushing assistance is required, avoiding problems such as bushing consumption, radial cracking at the hole exit, and secondary reaming; the workpiece can be self-centered through the shallow groove of the pallet, ensuring machining accuracy, and the operation process is simple and efficient.

[0042] 4. It can meet the through-hole reinforcement requirements of various metal components with plate thickness of 6~100mm and hole diameter of 6~50mm, and is suitable for fatigue-resistant manufacturing scenarios in multiple industries such as aviation, aerospace, and transportation.

[0043] 5. The segmented structure of the mandrel (tapered section + smooth rod section) reduces the squeezing resistance, the rotation and stroke mechanisms work together, the power transmission is stable, the equipment operates reliably, and the maintenance cost is low. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art 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.

[0045] Figure 1 This is an external view of an internal hole rolling strengthening device according to the present invention;

[0046] Figure 2 This is a cross-sectional view of the internal structure of an internal hole rolling strengthening device according to the present invention;

[0047] Figure 3 This is a drawing of the outline of the rolling tool;

[0048] Figure 4 This is a cross-sectional view of the internal structure of the rolling tool;

[0049] Figure 5 This is a flowchart illustrating the process of strengthening the inner hole according to the present invention;

[0050] Figure 6 A schematic diagram showing the mandrel being pushed in and all the needle rollers being pushed outwards radially;

[0051] Figure 7 This is a schematic diagram showing how the spindle rotates after being inserted, causing all the needle rollers to rotate on their own axis and revolve around the spindle.

[0052] Figure 8 The unique advantages of this technology compared to traditional technologies are that it can produce higher residual compressive stress peaks and deeper residual compressive stress layers.

[0053] Figure 9 The unique advantages of this technology compared to traditional technologies are: it can produce high fatigue resistance and lower surface roughness. Detailed Implementation

[0054] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention.

[0055] To fully understand this invention, detailed steps and structures will be presented in the following description to illustrate the technical solution of this invention. Preferred embodiments of the invention are described in detail below; however, in addition to these detailed descriptions, the invention may have other embodiments.

[0056] like Figure 1-4 As shown, the present invention provides a connecting hole rolling strengthening device 1000 for rolling strengthening the inner surface of the through-hole 501 of the workpiece 500.

[0057] It comprises six main components: housing 100, stroke mechanism 200, rotation mechanism 300, rolling tool 400, workpiece 500, and fixing mechanism 600.

[0058] 100 shell

[0059] The housing 100 includes an upper cover plate 101, a middle frame 102, a base plate 103, and an adjustable limit switch 104. The upper cover plate 101 is fixed to the middle frame 102 by bolts, and the middle frame 102 is fixed to the base plate 103 by bolts. The adjustable limit switch 104 is fixed to the cylindrical boss end face at the end of the base plate 103 and its height is adjustable.

[0060] The adjustable limit switch 104 senses the position of the cage 402 through physical contact or non-contact means, including but not limited to pressure sensors, laser sensors, displacement sensors, etc.

[0061] 200 travel agencies

[0062] The stroke mechanism 200 includes a cylinder 201 and a stroke driver 202, wherein the cylinder 201 is fixed to the center of the upper housing 100 by external threads. Preferably, the stroke mechanism 200 of the present invention is driven by hydraulic oil, the cylinder 201 is connected to a hydraulic pump station through hydraulic pipelines, and the stroke driver 202 is installed in the core of the cylinder 201, and can perform stroke operation along the axial direction of the cylinder 201 under the action of hydraulic oil.

[0063] Rotating mechanism 300

[0064] The rotating mechanism 300 includes a rotating driver mounting bracket 301, a rotating driver upper cover plate 302, a rotating driver base plate 303, a guide rail 304, a rotating driver 305, a connector housing 306, and a connector end cap 307. The rotating driver upper cover plate 302 is bolted to the rotating driver mounting bracket 301, and the rotating driver mounting bracket 301 is bolted to the rotating driver base plate 303. The rotating driver 305 is bolted to the core of the rotating driver mounting bracket 301. The end of the stroke driver 202 of the stroke mechanism 200 is threaded to the rotating driver upper cover plate 302. The central part drives the rotary driver 305 to perform stroke operation; the rotary driver upper cover plate 302, the rotary driver fixing bracket 301, and the rotary driver base plate 303 are fixed to the guide rail 304 by a slider to guide the stroke operation of the rotary driver 305; the connector housing 306 is fixed to the rotor end of the rotary driver 305 by bolts; the connector end cover 307 is fixed to the bottom of the connector housing 306 by bolts, and the push-roll composite bearing sleeved on the outside of the connector housing 306 is fixed in the annular boss at the bottom of the rotary driver base plate 303; the connector end cover 307 has a square connection hole at the center of the bottom.

[0065] Roller tool 400

[0066] like Figure 3-4 As shown, the rolling tool 400 includes a spindle 401, a cage 402 with multiple needle rollers 404, and a thrust bearing 403. The cage 402 passes through and is installed in the inner hole of the thrust bearing 403 with an interference fit. The cage 402 is provided with several axial through grooves along the circumference. Cylindrical needle rollers 404 that axially pass through the inner hole are installed in the axial through grooves. The upper end of the spindle 401 is connected to the rotating mechanism 300.

[0067] The lower end of the mandrel 401 has a slender rod that slides axially through the retainer 402 and axially engages with all the needle rollers 404. The upper section of the slender rod is a smooth cylindrical section 4013, and the lower section is a tapered section 4014 with a decreasing diameter from top to bottom. When the tapered section 4014 contacts the needle rollers 404, there is a gap between the needle rollers 404 and the inner wall of the bore. When the smooth cylindrical section 4013 contacts the needle rollers 404, there is an interference fit between the needle rollers 404 and the inner wall of the bore. The axial length of the smooth cylindrical section 4013 is 1.2 times the length of the needle rollers 404 to ensure good engagement between the two.

[0068] Furthermore, the mandrel 401 is composed of an upper connector 4011, a tapered connector 4012, a smooth cylindrical section 4013, and a small-angle tapered section 4014, all integrally formed from top to bottom.

[0069] The upper connector 4011 is a square adapter section. The upper connector 4011 is provided with an annular groove and a radial through hole located below the annular groove, so as to fix it in the square connection hole at the bottom center of the connector end cover 307, and fix the spindle 401 to the rotating mechanism 300.

[0070] A tapered connector 4012 is used to connect the slender rod to the upper connector 4011, which effectively improves strength and prevents the slender rod at the lower section of the mandrel 401 from breaking.

[0071] In an optional embodiment, the diameter of the roller needle 404 is 1 / 4 of the diameter of the hole to be strengthened, the small end diameter of the small-angle taper section 4014 at the lower end of the mandrel 401 is less than 1 / 2 of the diameter of the hole to be strengthened, and the large end diameter of the small-angle taper section 4014 at the lower end of the mandrel 401, that is, the diameter of the middle smooth cylindrical section 4013, is greater than 1 / 2 of the diameter of the hole to be strengthened. The excess amount is the tool interference amount to be achieved by the rolling strengthening.

[0072] Workpiece 500

[0073] Workpiece 500 is a plate structure with connecting holes to be reinforced. The plate thickness is 6~100 mm, the holes are through holes, and the hole diameter ranges from 6~50 mm.

[0074] Fixed mechanism 600

[0075] The fixing mechanism 600 includes an upper fixing bracket 601, a connecting plate 602, a workpiece support plate 603, and a lower support structure 604. The bottom plate 103 of the housing 100 is fixed to the upper fixing bracket 601 by bolts. The outer cylindrical surface of the annular boss on the bottom plate 103 of the housing 100 is precisely fitted with the inner cylindrical surface of the circular tube structure at the center of the upper fixing bracket 601 to ensure the coaxiality of the entire device. The upper fixing bracket 601 is fixed to the connecting plate 602 by bolts. The connecting plate 602 is fixed to the lower support structure 604 by bolts.

[0076] The workpiece support plate 603 is fixed to the bottom of the connecting plate 602 by four long bolts. A shallow groove for supporting the workpiece 500 is provided at the center of the workpiece support plate 603. The depth of the shallow groove is 3 mm less than the thickness of the workpiece 500, and the size of the shallow groove is slightly larger than the workpiece 500, allowing the workpiece 500 to move within the shallow groove. When the smooth cylindrical section 4013 of the mandrel is fully in contact with all the needle rollers 404, if the center of the hole to be strengthened in the workpiece 500 is not coaxial with the mandrel, the needle rollers 404 can slightly move the workpiece 500 so that the center of the hole to be strengthened is coaxial with the mandrel, thereby achieving self-centering of the workpiece 500.

[0077] It should be noted that, in order to achieve a small-amplitude movement of workpiece 500 on workpiece support plate 603, the downward pressure applied to workpiece 500 by the connecting plate of the fixing mechanism should not be too large. Excessive pressure may prevent workpiece 500 from self-centering. Specifically, after the mandrel is inserted into the center of the needle rollers, the needle rollers drive the workpiece to overcome the end-face pressure and achieve lateral movement and centering. Furthermore, after workpiece 500 completes self-centering, it stops moving, and the inner wall of the hole to be strengthened is subjected to rolling strengthening treatment through the rotation and revolution of the needle rollers.

[0078] The material used in this embodiment is a 15 mm thick 7075-T651 aluminum alloy sheet with a single central hole, an initial hole diameter of Φ15.5, and a final hole diameter of Φ16.1.

[0079] Example 1

[0080] The material used in this embodiment is a 15 mm thick 7075-T651 aluminum alloy sheet with a single central hole. The initial hole diameter is Φ15.5, and the final hole diameter is Φ16.1. The implementation steps 1001 of the present invention for rolling strengthening the hole to be strengthened in workpiece 500 are as follows:

[0081] S1. Select the rolling tool: Based on the diameter of the connecting hole to be strengthened and the required rolling strengthening tool interference δ=(16.1-15.5) / 15.5=3.7%, select a suitable rolling tool 400.

[0082] S2. Install the rolling tool: Connect the square adapter section at the top of the rolling tool 400 (i.e., the upper connector 4011 of the spindle 401) to the square connection hole at the bottom center of the connector end cover 307 of the rotating mechanism 300.

[0083] S3. Adjust the limit switch: Adjust the height of the adjustable limit switch 104 according to the length of the mandrel 401 of the selected rolling tool 400.

[0084] S4. Clamping the workpiece: Loosen the four long bolts connecting the workpiece support plate 603 and the connecting plate 602 on the fixing mechanism 600, lower the workpiece support plate 603, place the workpiece 500 into the shallow groove in the center of the workpiece support plate 603, and insert the retainer 402 with the needle roller 404 into the inner hole 501 of the workpiece 500 from top to bottom, keeping the base of the thrust bearing 403 of the rolling tool 400 in good contact with the upper surface of the workpiece 500; then slowly raise the workpiece support plate 603 so that the mandrel 401 is slowly inserted into the retainer 402 with the needle roller 404; continue to raise the workpiece support plate 603 until the upper surface of the workpiece 500 is completely in contact with the lower surface of the connecting plate 602 of the fixing mechanism 600; then tighten the four long bolts with the same preload by diagonal locking.

[0085] S5. Mandrel Insertion: Hydraulic oil is introduced into the upper cavity of the cylinder 201 of the stroke mechanism 200, driving the stroke driver 202 to move downwards. This, in turn, drives the mandrel 401 of the rolling tool 400 to move downwards via the rotating mechanism 300. This causes the small-angle taper section 4014 at the lower end of the mandrel 401 to slowly and evenly contact all the needle rollers 404 within the cage 402, and causes all the needle rollers 404 to move radially along the inner hole 501, gradually pressing into the surface of the inner hole 501, i.e., the outer wall surface of all the needle rollers 404 to fit against the inner wall surface of the inner hole 501. The mandrel 401 is continuously and slowly pressed down until all the needle rollers 404 move axially along the inner hole 501 to the middle of the smooth cylindrical section 4013 at the middle end of the mandrel 401, triggering the adjustable limit switch 104 and stopping the hydraulic oil supply.

[0086] S6. Spindle rotation: Start the rotary driver 305 in the rotary mechanism 300 to drive the spindle 401 of the rolling tool 400 to rotate at the set speed; when the spindle 401 has rotated to the preset number of revolutions, the rotary driver 305 stops rotating.

[0087] S7. Mandrel Extraction: Hydraulic oil is introduced into the lower cavity of the cylinder 201 of the stroke mechanism 200 to drive the stroke driver 202 to move upward. The rotating mechanism 300 drives the mandrel 401 of the rolling tool 400 to move upward, so that the mandrel 401 slowly and evenly disengages from all the needle rollers 404 in the cage 402 and is gradually pulled upward from the cage 402 until the stroke driver 202 of the stroke mechanism 200 returns to the starting position.

[0088] S8. Remove the workpiece: Loosen the four long bolts connecting the workpiece support plate 603 and the connecting plate 602 on the fixing mechanism 600, lower the workpiece support plate 603, and remove the workpiece 500 together with the retainer 402.

[0089] S9. Strengthen the subsequent workpiece: Take the next workpiece 500 and repeat steps S4~S8 to complete the rolling strengthening treatment of the inner hole 501 of the subsequent workpiece 500.

[0090] S10. Remove the rolling tool and end the strengthening process: After all workpieces 500 have been processed, pull the square transition section at the top of the rolling tool 400 out of the square connecting hole at the bottom center of the connector end cover 307 of the rotating mechanism 300 to complete the rolling strengthening process of the inner hole 501.

[0091] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0092] 1) Compared with traditional cold extrusion technology, this technology uses a mandrel and cage to drive the needle rollers to achieve extrusion and rotational rolling strengthening within the hole. The lower end of the mandrel has a small-angle taper section 4014, which greatly reduces the extrusion resistance. Subsequently, the needle rollers rotate continuously within the hole, resulting in non-conformal rolling friction with the hole wall. The frictional resistance is much less than the conformal sliding friction resistance between the mandrel and the hole wall in traditional hole extrusion technology, which greatly reduces the risk of hole wall damage. This can significantly improve the structural integrity and surface integrity of the strengthened hole. Moreover, the process is simple and quick, and no bushing is required, thus effectively avoiding process problems such as radial cracking at the hole exit and secondary reaming.

[0093] 2) Compared with traditional shot peening technology, this technology uses a mandrel and cage to drive the needle rollers to achieve large interference amount of extrusion and rotational rolling strengthening treatment in the hole. The hole wall is smooth and flat, the roughness of the strengthened surface is greatly reduced, no additional surface finishing treatment is required, and the strengthening effect and fatigue resistance are greatly improved.

[0094] 3) Compared with traditional hole surface rolling technology, the strengthening method adopted in this technology, which is "arranging the rollers first, then squeezing in and rotating the mandrel", can effectively increase the effective interference of the tool, while controlling the cumulative plastic deformation in the hole surface strengthening layer, preventing damage to the hole surface material, thereby improving the strengthening quality and strengthening effect of the hole surface and significantly enhancing the fatigue resistance.

[0095] In summary, this invention discloses a device and method for strengthening connecting holes by rolling, which is simple, easy to implement, low in cost, and has a significant strengthening effect. It can be widely applied to the fatigue-resistant surface deformation strengthening of connecting holes in various metal structures, and has high practical value and important practical significance in the field of fatigue-resistant manufacturing in multiple industries such as aviation, aerospace, defense, and transportation.

[0096] The preferred embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and the devices and structures not described in detail should be understood as being implemented in a conventional manner in the art. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the present invention. This does not affect the essential content of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention's technical solutions still fall within the protection scope of the present invention.

Claims

1. An internal hole rolling strengthening device for rolling strengthening the inner surface of a through-hole of a workpiece (500), characterized in that, The strengthening device includes a housing (100), a stroke mechanism (200), a rotation mechanism (300), a rolling tool (400), and a fixing mechanism (600). The housing (100) includes a base plate (103) and an adjustable limit switch (104) disposed at the end of the base plate (103). The stroke mechanism (200) is fixed above the housing (100) and is used to provide axial feed power to the rotary mechanism (300). The rotary mechanism (300) stops feeding when it is axially fed to contact the adjustable limit switch (104). The rotating mechanism (300) is installed inside the housing (100) and connected to the stroke mechanism (200) to provide rotational driving force for the rolling tool (400); The rolling tool (400) includes a mandrel (401), a cage (402) with multiple needle rollers (404), and a thrust bearing (403). The cage (402) passes through and is interference-fitted into the inner hole of the thrust bearing (403). The cage (402) has several axial through grooves along its circumference, and cylindrical needle rollers (404) that axially pass through the inner hole are installed in the axial through grooves. The upper end of the mandrel (401) is connected to the rotating mechanism (300), and the lower end of the mandrel (401) is provided with an axial sliding surface. A slender rod passes through the cage (402) and is axially attached to all the needle rollers (404). The upper section of the slender rod is a smooth cylindrical section (4013), and the lower section is a small-angle taper section (4014) with a diameter decreasing from top to bottom. When the small-angle taper section (4014) contacts the needle roller (404), there is a gap between the needle roller (404) and the inner wall of the workpiece (500). When the smooth cylindrical section (4013) contacts the needle roller (404), there is an interference fit between the needle roller (404) and the inner wall of the inner hole. The fixing mechanism (600) is fixedly connected to the base plate (103), and the fixing mechanism (600) is provided with a perforated workpiece support plate (603) for carrying the workpiece (500).

2. The internal hole rolling strengthening device according to claim 1, characterized in that: The stroke mechanism (200) includes a cylinder (201) and a stroke driver (202), the end of which is connected to the rotary mechanism (300).

3. The internal hole rolling strengthening device according to claim 1, characterized in that: The rotating mechanism (300) includes: a rotating driver mounting bracket (301), a rotating driver upper cover plate (302), a rotating driver base plate (303), a guide rail (304), a rotating driver (305), a connector housing (306), and a connector end cap (307). The rotary driver mounting bracket (301) is encapsulated by the rotary driver upper cover plate (302) and the rotary driver bottom plate (303) to form a rotary driver accommodating space. The rotary driver mounting bracket (301) is provided with a guide rail (304) for sliding axially with the housing (100). The rotary driver upper cover plate (302) is fixedly connected to the stroke mechanism (200). The rotary actuator (305) is fixedly installed inside the rotary actuator accommodating space; One end of the connector housing (306) is connected to the output shaft of the rotary driver (305), and the other end is provided with a connector end cap (307). The connector end cap (307) has an inner hole in the center for connecting the spindle (401) to transmit torque to the rolling tool (400).

4. The internal hole rolling strengthening device according to claim 1, characterized in that: The fixing mechanism (600) also includes a fixing bracket (601), a connecting plate (602), and a lower support structure (604). The upper end face of the cylindrical fixed bracket (601) is fixedly connected to the base plate (103), and the lower end face of the fixed bracket (601) is fixedly connected to the lower support structure (604) through the annular connecting plate (602); The workpiece support plate (603) is fixedly installed on the lower surface of the connecting plate (602) by fastening bolts, and the upper surface of the workpiece (500) is attached to the lower surface of the connecting plate (602).

5. The internal hole rolling strengthening device according to claim 4, characterized in that: The upper surface of the workpiece tray (603) is provided with a shallow groove for placing the workpiece (500) at the center. The size of the shallow groove is larger than the size of the workpiece (500), and the depth of the shallow groove is less than the thickness of the workpiece (500) by 3 mm.

6. The internal hole rolling strengthening device according to claim 3, characterized in that: The mandrel (401) is composed of an upper connector (4011) integrally formed from top to bottom, a tapered connector (4012), a smooth cylindrical section (4013), and a small-angle tapered section (4014); The upper connector (4011) is used to fix it to the connector end cap (307). The upper connector (4011) is provided with an annular groove and a radial through hole located below the annular groove. The upper connector (4011) is fixedly connected to the cylindrical section (4013) of the smooth rod via the tapered connector (4012).

7. The internal hole rolling strengthening device according to claim 6, characterized in that: The axial length of the smooth cylindrical section (4013) is greater than or equal to 1.2 times the axial length of the needle roller (404).

8. The internal hole rolling strengthening device according to claim 6, characterized in that: The diameter of the needle roller (404) is 1 / 4 of the inner bore diameter. The upper end diameter of the small-angle taper section (4014) is equal to the diameter of the smooth cylindrical section (4013), both being 1 / 2 of the inner hole diameter plus the tool interference δ. The lower end diameter of the small-angle taper section (4014) is less than 1 / 2 of the inner hole diameter.

9. A method for internal hole rolling strengthening using the internal hole rolling strengthening device according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Preparatory steps: Select the appropriate rolling tool (400) according to the inner hole diameter to be strengthened and the required tool interference amount δ, and fix the mandrel (401) to the rotating mechanism (300), and adjust the height of the limit switch (104); S2. Workpiece and cage clamping: Lower the workpiece support plate (603) of the fixing mechanism (600), place the workpiece (500) in the shallow groove on the workpiece support plate (603), and insert the cage (402) and its needle rollers (404) into the inner hole from top to bottom in advance, so that the base of the thrust bearing (403) fits against the upper surface of the workpiece. S3. Initial centering and positioning: Raise the workpiece support plate (603) so that the small-angle taper section (4014) of the mandrel (401) is initially inserted into the cage (402) and makes uniform initial contact with all the needle rollers (404) on the cage (402), and forces the workpiece (500) to move freely in the shallow groove on the workpiece support plate (603) to achieve coaxiality alignment between the rolling tool (400) and the inner hole on the workpiece (500), and then lock the workpiece support plate (603). S4, Mandrel Extrusion Reinforcement: The start-up stroke mechanism (200) drives the mandrel (401) to feed downwards at a constant speed. The small-angle taper section (4014) pushes all the needle rollers (404) radially and gradually presses them into the inner wall of the hole. After the limit switch (104) senses the holder (402) and moves to the designated position, the feed stops. At this time, the cylindrical section (4013) of the smooth rod is in complete contact with the side walls of all the needle rollers (404). S5. Start the rotating mechanism (300) to drive the spindle (401) to rotate a preset number of times or a preset time, and then stop automatically. During this process, the rotational friction of the spindle (401) drives each needle roller (404) to rotate, and at the same time drives the cage (402) to rotate so that the needle roller (404) revolves around the spindle (401) to achieve rolling and strengthening of the inner hole wall; S6. The start stroke mechanism (200) drives the spindle (401) to withdraw axially at a uniform speed, so that the spindle slowly and evenly disengages from all the needle rollers (404) and is gradually pulled upward from the cage (402); S7. Remove the workpiece.

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