An adjustable boring tool for stepped hole machining

Abstract

The present invention relates to the technical field of boring tools, and specifically relates to an adjustable boring tool for stepped hole machining, which includes a tool body. A tool holder is arranged at the lower end of the tool body, and a tool head is fixedly connected to the lower end of the tool holder. The tool body is composed of an upper tool rod, a second tool rod, and a tool rod sleeve; the beneficial effects are as follows: This tool integrates radial and axial adjustment mechanisms, enabling the tool to perform precise radial and axial adjustments according to the diameters and depths of different stepped hole sizes during the machining process. With the introduced variable-diameter support mechanism, it can protect the upper part of the tool head, ensure the assembly fastening between the tool holder and the tool head, dynamically adjust the effective support for stepped holes of different sizes according to the processing requirements, enhance the rigidity of the tooling, and avoid the phenomena of tool deflection or vibration of the boring tool, and avoid the appearance of cutting marks on the inner wall of the boring. It not only improves the flexibility of the tool but also ensures the accuracy and stability of the machining.

Description

Technical Field

[0001] The present invention relates to the technical field of boring tools, and specifically to an adjustable boring tool for stepped hole machining. Background Art

[0002] A stepped hole is a common hole type in machining, with multiple hole segments of different diameters. When traditional fixed boring tools are used to machine stepped holes, the tools need to be frequently replaced, which not only reduces the machining efficiency but also increases the machining cost. With the development of the manufacturing industry, the requirements for machining efficiency and machining accuracy are constantly increasing, and adjustable boring tools have emerged. They can adapt to the machining requirements of different hole diameters and depths by adjusting the structure or parameters of the tools.

[0003] In the prior art, for example, a three-layer stepped large-diameter boring tool for machining the front housing of a transmission box with the publication number CN210817498U can machine three stepped inner holes of different diameters simultaneously. Each layer of the tool body adopts a sleeve-type hollow tool body, which is light in weight and simple in structure. Moreover, each layer of the tool body adopts boring tool sliders and boring tool seats of the same size, with a unified module standard, having modularity and adjustability. Also, the machining depth of each hole can be adjusted, so as to achieve the purpose of machining three large-diameter inner holes with one tool.

[0004] During the actual use process, it is necessary to manually adjust a plurality of groups of diameter adjustment bolts in sequence to adjust the axial distance between each layer of the tool body, and then fix the connecting bolts and washers firmly. Although this method realizes the machining of multi-layer stepped inner holes, the operation steps are cumbersome, and it is easy to have adjustment errors resulting in boring failure. Moreover, when the feed and rotation speed of traditional tools do not match, there is rigid vibration and tool wear, the cutting resistance is large, and it is easy to have tool chatter and tool deflection phenomena, and fish-scale or thread-shaped cutting marks appear on the machined surface, affecting the dimensional stability and machining quality.

[0005] Therefore, the present invention proposes an adjustable boring tool for stepped hole machining to solve the problem of cumbersome adjustment steps when existing tools machine stepped holes. It can adjust the axial and radial directions of the boring tool, maintain a relatively stable boring diameter during the machining process, and can adapt to the machining requirements of different hole depths, reducing the machining process and ensuring the coaxiality requirements for machining stepped holes. Summary of the Invention

[0006] The purpose of the present invention is to provide an adjustable boring tool for stepped hole machining to solve the problems raised in the above background art.

[0007] To achieve the above object, the present invention provides the following technical solution: An adjustable boring tool for stepped hole machining, comprising a tool body, a tool holder is provided at the lower end of the tool body, a tool head is fixedly connected to the lower end of the tool holder, the tool body is composed of an upper tool rod, a tool rod two and a tool rod sleeve, the outer surfaces of the lower ends of the tool rod two and the tool rod sleeve are fixedly welded to the tool holder, the inner surface of the tool head is respectively provided with a movable groove one and a movable groove two, a square notch is centrally penetrated through the movable groove one and the movable groove two, a radial adjustment mechanism is arranged inside the square notch, a variable diameter support mechanism is arranged above the tool head, and the variable diameter support mechanism includes a tool head socket and an expansion assembly.

[0008] Preferably, a cavity is provided on the inner surface of the upper tool rod, an axial adjustment mechanism is arranged inside the cavity, the axial adjustment mechanism includes a telescopic push rod, the telescopic push rod is fixedly installed on the top surface of the inner cavity of the cavity, the output end of the telescopic push rod is fixedly connected to the outer surface of the upper end of the tool rod two, the outer surface of the tool rod two is fixedly connected to the inner surface of the tool rod sleeve, and the outer surface of the tool rod sleeve is slidably connected to the inner wall of the cavity.

[0009] Preferably, the radial adjustment mechanism includes a screwing handle, a moving cylinder one and a moving cylinder two, a toothed rod is fixedly installed on the outer surface of the center of the screwing handle, both ends of the screwing handle are respectively rotatably connected to the inner wall of the tool head, the moving cylinder one is slidably installed inside the movable groove one, the moving cylinder two is slidably installed inside the movable groove two, tooth grooves that are meshed and matched with the outer surface of the toothed rod are respectively arranged on the lower surface of the moving cylinder one and the upper surface of the moving cylinder two, a fixed block fixedly connected to the inner wall of the movable groove two is arranged at one end of the moving cylinder two, a limiting rod is fixedly connected to the inner side surface of the fixed block, and the outer surface of the limiting rod is movably connected to the inner wall of the moving cylinder two.

[0010] Preferably, a connecting rod is fixedly installed at one end of the limiting rod away from the fixed block, the outer surface of the connecting rod is fixedly connected to the inner wall of the moving cylinder two, a tool mounting seat is fixedly connected to the outside of the connecting rod by a bolt, and a tool is detachably installed at the lower end of the tool mounting seat.

[0011] Preferably, fastening bolts are respectively arranged on the inner side walls of both sides of the tool head socket, the tool head socket and the outer surface of the tool head are fixedly connected by the fastening bolts, and an inner convex plate is fixedly added to the inner ring side wall of the tool head socket.

[0012] Preferably, a receiving inclined groove is provided on the inner wall of the tool head socket, the receiving inclined groove is provided with a 75° inclined plane, an avoidance groove is centrally penetrated through the upper cavity of the receiving inclined groove, and six groups of the receiving inclined grooves and the avoidance grooves are respectively arranged in a circular array about the central axis of the tool head socket.

[0013] Preferably, the extension component includes a protective convex ring and a screwing disk, the protective convex ring is fixedly mounted on the upper surface of the cutter head sleeve, the screwing disk is rotatably mounted on the upper side of the protective convex ring, the central inner surface of the screwing disk is fixedly connected to a connecting shaft, the lower end outer surface of the connecting shaft is fixedly connected to a gear, the outer surface of the gear is meshed and rotatably engaged with a gear ring, the inner ring surface of the gear ring is fixedly connected to a rotating disk, and the cross-section of the rotating disk presents a "convex" plate-like structure.

[0014] Preferably, the upper outer surface of the rotating disk is fixedly connected to a limiting ring, and a rotating groove is provided on the side wall of the upper inner ring of the tool head sleeve, and the inner surface of the rotating groove is rotatably connected to the outer surface of the limiting ring.

[0015] Preferably, arc grooves are evenly opened on the inner wall of the rotating disk, and a limiting column is movably installed on the inner surface of the arc groove. The lower end of the limiting column is fixedly connected to an extended support block, and the outer surface of the extended support block is movably connected to the inner wall of the receiving inclined groove and the avoidance groove.

[0016] Preferably, a buffer groove is opened on the outer inner wall of the limiting column, and carbon steel and alloy steel blocks are fixedly installed on the inner wall of the buffer groove. The outer surfaces of the carbon steel and alloy steel blocks are fixedly connected to support plates, and the outer surface of the support plate is movably connected to the inner wall of the buffer groove.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention proposes an adjustable boring tool for step hole processing. The tool integrates radial and axial adjustment mechanisms, so that the tool can be accurately adjusted radially and axially according to the diameter and hole depth of different step hole sizes during the processing process. In conjunction with the introduced variable diameter support mechanism, the upper part of the tool head is protected and the assembly and tightening between the tool holder and the tool head are met. It can also dynamically adjust the effective support for step holes of different sizes according to processing requirements, enhance the rigidity of the tooling, avoid the boring tool from letting go or vibrating, and avoid the appearance of cut lines on the inner wall of the boring tool. Not only does it improve the flexibility of the tool, but it also ensures the processing accuracy and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0020] Figure 2 It is a schematic diagram of a half-section structure of the present invention;

[0021] Figure 3 It is a schematic diagram of the three-dimensional disassembled structure of the present invention;

[0022] Figure 4 For the present invention Figure 3 A schematic diagram of the enlarged structure at point A;

[0023] Figure 5 It is a schematic diagram of the partial cross-sectional structure of the radial adjustment mechanism of the present invention;

[0024] Figure 6 It is a schematic diagram of the partial cross-sectional structure of the tool head socket of the present invention;

[0025] Figure 7 For the present invention Figure 6 The enlarged structure diagram at position B;

[0026] Figure 8 It is a schematic diagram of the partial structure of the variable diameter support mechanism of the present invention;

[0027] Figure 9 It is a schematic diagram of the half-sectional structure of the gear ring of the present invention;

[0028] Figure 10 It is a schematic diagram of the partial cross-sectional structure of the expansion component of the present invention;

[0029] Figure 11 It is a schematic diagram of the machining state structure of the stepped hole of the boring tool of the present invention.

[0030] In the figure: 1. Tool body; 11. Upper tool rod; 10. Cavity; 12. Tool rod two; 121. Tool rod sleeve; 13. Telescopic push rod; 2. Tool seat; 3. Tool head; 30. Moving groove one; 300. Moving groove two; 301. Square notch; 31. Fastening bolt; 32. Screwing handle; 321. Rack; 33. Moving cylinder one; 34. Moving cylinder two; 35. Tool mounting seat; 351. Tool; 352. Connecting rod; 353. Limiting rod; 354. Fixed block; 4. Tool head socket; 41. Inner convex plate; 40. Receiving inclined groove; 401. Avoidance groove; 400. Rotating groove; 42. Protective convex ring; 421. Screwing disc; 422. Gear; 423. Gear ring; 4231. Limiting ring; 43. Rotating disc; 430. Arc groove; 44. Limiting column; 441. Expansion support block; 4410. Buffer groove; 442. Support plate; 443. Carbon steel and alloy steel block. Detailed implementation manners

[0031] In order to clearly and completely describe the purpose, technical solution of the present invention and make the advantages more clear, the following further details the embodiments of the present invention with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are part of the embodiments of the present invention, rather than all of the embodiments, and are only used to explain the embodiments of the present invention, not to limit the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0032] Embodiment 1, please refer to Figure 1 - Figure 11, the present invention provides a technical solution: an adjustable boring tool for stepped hole machining, including a tool body 1. A tool holder 2 is provided at the lower end of the tool body 1, and a tool head 3 is fixedly connected to the lower end of the tool holder 2. The tool body 1 is composed of an upper tool rod 11, a second tool rod 12, and a tool rod sleeve 121. The outer surfaces of the lower ends of the second tool rod 12 and the tool rod sleeve 121 are fixedly welded to the tool holder 2. Activity grooves one 30 and two 300 are respectively formed on the inner surface of the tool head 3. A square notch 301 is formed through the centers of the activity groove one 30 and the activity groove two 300. A radial adjustment mechanism is arranged inside the square notch 301. A variable diameter support mechanism is arranged above the tool head 3. The variable diameter support mechanism includes a tool head socket 4 and an expansion component; a cavity 10 is formed on the inner surface of the upper tool rod 11. An axial adjustment mechanism is arranged inside the cavity 10. The axial adjustment mechanism includes a telescopic push rod 13. The telescopic push rod 13 is fixedly installed on the top surface of the inner cavity of the cavity 10. The output end of the telescopic push rod 13 is fixedly connected to the outer surface of the upper end of the second tool rod 12. The outer surface of the second tool rod 12 is fixedly connected to the inner surface of the tool rod sleeve 121. The outer surface of the tool rod sleeve 121 is slidably connected to the inner wall of the cavity 10;

[0033] In this embodiment, the tool body 1 is divided into a two-section combination. Through the cavity 10 formed on the inner wall of the upper tool rod 11, the second tool rod 12 and the tool rod sleeve 121 are dominantly installed. The telescopic push rod 13 is controlled to push the top end of the second tool rod 12. According to the hole depth that the boring tool needs to machine, the telescopic push rod 13 precisely adjusts the lowering stroke of the second tool rod 12. The inner wall of the upper tool rod 11 fits well with the outer wall of the tool rod sleeve 121 to ensure the stability of the forward stroke section of the tool head 3. It should be mentioned that when the tool rod sleeve 121 is in the initial state, the tool rod sleeve 121 merges with the bottom end of the upper tool rod 11 to form a double-layer rod structure, enhancing the rigidity of the tool body 1. And when the tool head 3 extends, the upper tool rod 11 can not only protect the second tool rod 12 but also satisfy the stable longitudinal movement limit of the second tool rod 12.

[0034] Embodiment 2. On the basis of Embodiment 1, in order to enable the cutter head 3 to adapt to different boring diameters and meet the axial adjustment of the tool 351, this embodiment further proposes that: The radial adjustment mechanism includes a screwing handle 32, a moving cylinder 33 and a moving cylinder 34. A toothed rod 321 is fixedly installed on the outer surface of the center of the screwing handle 32. The two ends of the screwing handle 32 are respectively rotatably connected to the inner wall of the cutter head 3. The moving cylinder 33 is slidably installed inside the first movable groove 30, and the moving cylinder 34 is slidably installed inside the second movable groove 300. Tooth grooves that are meshed and matched with the outer surface of the toothed rod 321 are respectively arranged on the lower surface of the moving cylinder 33 and the upper surface of the moving cylinder 34. One end of the moving cylinder 34 is provided with a fixed block 354 fixedly connected to the inner wall of the second movable groove 300. A limiting rod 353 is fixedly connected to the inner side surface of the fixed block 354. The outer surface of the limiting rod 353 is movably connected to the inner wall of the moving cylinder 34; One end of the limiting rod 353 away from the fixed block 354 is fixedly installed with a connecting rod 352. The outer surface of the connecting rod 352 is fixedly connected to the inner wall of the moving cylinder 34. The outside of the connecting rod 352 is fixedly connected with a tool mounting seat 35 through bolts. A tool 351 is detachably installed at the lower end of the tool mounting seat 35;

[0035] In this embodiment, according to the processing requirements, the screwing handle 32 is rotated so that the toothed rod 321 rotates synchronously and is meshed and matched with the tooth grooves inside the moving cylinder 33 and the moving cylinder 34. When the toothed rod 321 rotates counterclockwise, the moving cylinder 33 and the moving cylinder 34 move towards opposite sides. During the relative movement of the moving cylinder 34, it slides on the surface of the limiting rod 353 and drives the tool mounting seat 35 and the tool 351 on one side to move. In this way, by precisely controlling the rotation angle of the screwing handle 32, the distance that the tool 351 extends is realized to adapt to the boring of stepped holes with different diameters; When the toothed rod 321 rotates back, the moving cylinder 33 and the moving cylinder 34 on both sides move inward relatively, so as to accommodate the tool 351. Through the cooperation between this series of structures, the accuracy of boring processing is enhanced, the operation is simple and convenient, and there is no need to repeat the steps of screwing multiple bolts, reducing the operation time and processing procedures.

[0036] Embodiment 3. On the basis of Embodiment 2, in order to realize the radial movement of the tool 351 and the stability of boring processing, this embodiment further proposes that: A circular receiving groove is opened on the inner surface of the moving cylinder 33, and a counterweight block is arranged on the inner surface of the circular receiving groove; Tightening bolts 31 are respectively arranged on the inner side walls of both sides of the cutter head socket 4. The cutter head socket 4 and the outer surface of the cutter head 3 are fixedly connected through the tightening bolts 31. An inner convex plate 41 is fixedly added to the inner ring side wall of the cutter head socket 4;

[0037] In this embodiment, by arranging a counterweight block in the circular receiving groove opened on the inner surface of the moving cylinder 1 33, the dynamic imbalance of the radial adjustment mechanism during operation can be effectively balanced, especially when the moving cylinder 1 33 and the moving cylinder 2 34 perform relative movement according to the rotation of the gear rod 321, the existence of the counterweight block can reduce the vibration caused by the movement, so that the radial movement of the tool 351 is more stable, and the precision and stability of the boring processing are improved. The counterweight block helps to maintain the self-balance of the entire processing system by reducing the vibration of the moving parts, thereby ensuring that the tool 351 can move accurately according to the predetermined trajectory during the processing, reducing the processing error caused by vibration, and at the same time can extend the service life of the radial adjustment mechanism and its related components, reducing the maintenance cost and replacement frequency;

[0038] In addition, a cutter head sleeve 4 is installed at the connection between the cutter seat 2 and the cutter head 3, and is fastened with a fastening bolt 31. This design can not only provide structural support for the variable diameter support mechanism, but also meet the protection of the connection between the cutter seat 2 and the cutter head 3. It can prevent external boring debris from damaging the internal structure, and can also weaken the swing stress of the cutter head 3 during the overall boring operation.

[0039] Embodiment 4, on the basis of embodiment 3, in order to achieve the stability of the cutter head 3 during deep hole step hole processing, this embodiment further proposes: a receiving inclined groove 40 is provided on the inner wall of the cutter head sleeve 4, the receiving inclined groove 40 is provided at an inclined surface inclined at an angle of 75°, and an avoidance groove 401 is provided through the upper cavity of the receiving inclined groove 40, and the receiving inclined groove 40 and the avoidance groove 401 are respectively provided with six groups and are distributed in a circular array about the central axis of the cutter head sleeve 4; the extension component includes a protective convex ring 42 and a screw disk 421, the protective convex ring 42 is fixedly mounted on the upper surface of the cutter head sleeve 4, and the screw disk 421 The rotating disk 421 is rotatably mounted on the upper side of the protective convex ring 42. The central inner surface of the screwing disk 421 is fixedly connected to a connecting shaft. The outer surface of the lower end of the connecting shaft is fixedly connected to a gear 422. The outer surface of the gear 422 is meshed and rotatably engaged with a gear ring 423. The inner ring surface of the gear ring 423 is fixedly connected to a rotating disk 43. The cross-section of the rotating disk 43 is a "convex" plate-like structure. The upper outer surface of the rotating disk 43 is fixedly connected to a limiting ring 4231. A rotating groove 400 is provided on the side wall of the upper inner ring of the tool head sleeve 4. The inner surface of the rotating groove 400 is rotatably connected to the outer surface of the limiting ring 4231.

[0040] In this embodiment, after the cutter head 3 finishes machining the first stepped hole in the upper layer, the radial depth of the cutter head 3 is adjusted to machine the second stepped hole. At this time, the cutter head 3 extends into the second stepped hole, and the upper section of the cutter head 3 is located within the boring hole of the first stepped hole. According to the diameter of the boring hole of the first stepped hole, the expansion assembly is adjusted to adapt to stepped holes of different diameters. Specifically, the screwing disc 421 is manually rotated, causing the connecting shaft rod to drive the gear 422 to rotate together. Under the matching action of the meshing teeth, the toothed ring 423 rotates. In this way, the rotating disc 43 is finely adjusted. According to the arc-shaped groove 430 opened on the rotating disc 43, the inner limiting column 44 will be driven to move. The expansion support block 441 is limited by the rotating groove 400. Then, at this time, multiple groups of expansion support blocks 441 achieve variable diameter adjustment. According to the diameter of the boring hole of the first stepped hole, the support plate 442 contacts its machined wall surface to support the outer hole, enhancing the rigidity of the tooling and avoiding the phenomenon of tool deflection or vibration of the boring tool. It should be noted that the receiving inclined groove 40 is set as an inclined groove body. While serving as the receiving of the expansion assembly, it can effectively prevent the adhesion of debris during the polishing of the inner side of the stepped hole.

[0041] Embodiment 5, on the basis of Embodiment 4, in order to avoid the phenomenon of tool vibration during the boring operation of the cutter head 3, this embodiment also proposes that arc-shaped grooves 430 are uniformly opened on the inner wall of the rotating disc 43. The inner surface of the arc-shaped groove 430 is movably installed with a limiting column 44. The lower end of the limiting column 44 is fixedly connected with an expansion support block 441. The outer surface of the expansion support block 441 is movably connected with the inner walls of the receiving inclined groove 40 and the avoidance groove 401. A buffer groove 4410 is opened on the outer inner wall of the limiting column 44. Carbon steel and alloy steel blocks 443 are fixedly installed on the inner wall of the buffer groove 4410. The outer surface of the carbon steel and alloy steel blocks 443 is fixedly connected with a support plate 442. The outer surface of the support plate 442 is movably connected with the inner wall of the buffer groove 4410.

[0042] In this embodiment, when the cutter head 3 rotates integrally for boring operation through the startup of the equipment, the cutter head socket 4 rotates synchronously with the expansion assembly. At this time, the support plate 442 can not only achieve the limiting support during the machining of the second stepped hole by the cutting tool 351, maintain the centering boring of multiple-layer stepped holes, enhance the machining accuracy, but also continuously rub against the wall surface of the first stepped hole, which can assist in polishing the initially bored inner wall, enhancing the smoothness of the boring hole. And through the setting of adding carbon steel and alloy steel blocks 443 inside the buffer groove 4410, while providing support rigidity for the back end of the support plate 442, the vibration during boring is weakened, further improving the stability during the machining of the stepped hole.

[0043] In actual use, first, one end of the tool body 1 is installed on the machine tool. According to the processing requirements, the screwing handle 32 is rotated so that the toothed rod 321 rotates synchronously and is adaptively engaged with the tooth grooves inside the first moving cylinder 33 and the second moving cylinder 34. When the toothed rod 321 rotates counterclockwise, the first moving cylinder 33 and the second moving cylinder 34 move toward both sides relative to each other. During the relative movement of the second moving cylinder 34, it slides on the surface of the limiting rod 353 and drives the tool mounting seat 35 and the tool 351 on one side to move. In this way, by precisely adjusting the rotation angle of the screwing handle 32, the distance that the tool 351 extends out can be realized to adapt to the boring of stepped holes with different diameters. Furthermore, when the tool head 3 finishes processing the upper first stepped hole, the radial depth and the axial diameter of the tool head 3 are adjusted, and then the second stepped hole is processed. At this time, the tool head 3 extends into the second stepped hole. By manually rotating the screwing disc 421, the connecting shaft rod drives the gear 422 to rotate together. Under the matching action of the meshing teeth, the toothed ring 423 rotates. In this way, the rotating disc 43 is finely adjusted. According to the arc-shaped groove 430 opened on the rotating disc 43, the inner limiting column 44 will be driven to move. The extended support block 441 is limited by the rotating groove 400. Then, at this time, multiple groups of extended support blocks 441 realize variable diameter adjustment. After the equipment is started, when the tool head 3 performs the overall rotary boring operation, the tool head sleeve seat 4 rotates synchronously with the extended assembly. At this time, the support plate 442 can not only achieve the limiting support for the tool 351 during the processing of the second collective hole, keep the concentric boring of the multi-layer stepped holes, and enhance the processing accuracy, but also the support plate 442 continuously rubs against the wall surface of the first stepped hole, which can assist in polishing the inner wall of the preliminary boring and enhance the smoothness of the boring hole. And through the setting of adding carbon steel and alloy steel blocks 443 inside the buffer groove 4410, while providing support rigidity for the back end of the support plate 442, the vibration during boring is weakened, and the stability during the processing of the stepped hole is further improved.

[0044] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An adjustable boring tool for machining stepped holes, comprising a tool body (1), a tool holder (2) is arranged at the lower end of the tool body (1), and a tool bit (3) is fixedly connected to the lower end of the tool holder (2), characterized in that: The knife body (1) is composed of an upper knife bar (11), a second knife bar (12) and a knife bar sleeve (121); the lower end outer surfaces of the second knife bar (12) and the knife bar sleeve (121) are welded and fixed to the knife seat (2); the inner surface of the knife head (3) is respectively provided with a movable groove (30) and a movable groove (300); a square notch (301) is provided through the center of the movable groove (30) and the movable groove (300); a radial adjustment mechanism is provided on the inner side of the square notch (301); a variable diameter support mechanism is provided on the upper side of the knife head (3); the variable diameter support mechanism includes a knife head sleeve seat (4) and an expansion component; The inner walls on both sides of the tool head sleeve (4) are respectively provided with fastening bolts (31), the tool head sleeve (4) is fixedly connected to the outer surface of the tool head (3) by the fastening bolts (31), an inner convex plate (41) is fixedly provided on the inner ring side wall of the tool head sleeve (4), a receiving inclined groove (40) is provided on the inner wall of the tool head sleeve (4), the receiving inclined groove (40) is provided at an inclined surface inclined at an angle of 75°, an avoidance groove (401) is provided through the upper cavity of the receiving inclined groove (40), and the receiving inclined groove (40) and the avoidance groove (401) are respectively provided in six groups and are distributed in a circular array about the central axis of the tool head sleeve (4); The extension component comprises a protective convex ring (42) and a screwing disk (421); the protective convex ring (42) is fixedly mounted on the upper surface of the cutter head sleeve (4); the screwing disk (421) is rotatably mounted on the upper side of the protective convex ring (42); the central inner surface of the screwing disk (421) is fixedly connected to a connecting shaft; the lower end outer surface of the connecting shaft is fixedly connected to a gear (422); the outer surface of the gear (422) is meshed and rotatably engaged with a toothed ring (423); the inner ring surface of the toothed ring (423) is fixedly connected to a rotating disk (43); the cross-section of the rotating disk (43) presents a "convex" plate-like structure; The upper outer surface of the rotating disk (43) is fixedly connected to a limiting ring (4231); a rotating groove (400) is provided on the upper inner ring side wall of the tool head sleeve (4); and the inner surface of the rotating groove (400) is rotatably connected to the outer surface of the limiting ring (4231); The inner wall of the rotating disk (43) is evenly provided with arc grooves (430), the inner surface of the arc groove (430) is movably mounted with a limiting column (44), the lower end of the limiting column (44) is fixedly connected with an extended support block (441), and the outer surface of the extended support block (441) is movably connected to the inner wall of the receiving inclined groove (40) and the avoidance groove (401).

2. The adjustable boring tool for stepped hole machining according to claim 1, characterized in that: The inner surface of the upper tool rod (11) is provided with a cavity (10). An axial adjustment mechanism is arranged in the inner cavity of the cavity (10). The axial adjustment mechanism includes a telescopic push rod (13). The telescopic push rod (13) is fixedly installed on the top surface of the inner cavity of the cavity (10). The output end of the telescopic push rod (13) is fixedly connected to the outer surface of the upper end of the second tool rod (12). The outer surface of the second tool rod (12) is fixedly connected to the inner surface of the tool rod sleeve (121). The outer surface of the tool rod sleeve (121) is slidably connected to the inner wall of the cavity (10).

3. An adjustable boring tool for stepped hole machining according to claim 1, characterized in that: The radial adjustment mechanism includes a screwing handle (32), a first moving cylinder (33) and a second moving cylinder (34). A toothed rod (321) is fixedly installed on the outer surface of the center of the screwing handle (32). The two ends of the screwing handle (32) are respectively rotatably connected to the inner wall of the tool head (3). The first moving cylinder (33) is slidably installed inside the first movable groove (30). The second moving cylinder (34) is slidably installed inside the second movable groove (300). Tooth grooves which are meshed and matched with the outer surface of the toothed rod (321) are respectively arranged on the lower surface of the first moving cylinder (33) and the upper surface of the second moving cylinder (34). One end of the second moving cylinder (34) is provided with a fixed block (354) fixedly connected to the inner wall of the second movable groove (300). A limiting rod (353) is fixedly connected to the inner side surface of the fixed block (354). The outer surface of the limiting rod (353) is movably connected to the inner wall of the second moving cylinder (34).

4. An adjustable boring tool for stepped hole machining according to claim 3, characterized in that: One end of the limiting rod (353) far away from the fixed block (354) is fixedly installed with a connecting rod (352). The outer surface of the connecting rod (352) is fixedly connected to the inner wall of the second moving cylinder (34). A tool mounting seat (35) is fixedly connected to the outer side of the connecting rod (352) through a bolt. A tool (351) is detachably installed at the lower end of the tool mounting seat (35).

5. An adjustable boring tool for stepped hole machining according to claim 1, characterized in that: A buffer groove (4410) is formed in the inner wall on the outer side of the limiting column (44). A carbon steel and alloy steel block (443) is fixedly installed on the inner wall of the buffer groove (4410). A support plate (442) is fixedly connected to the outer surface of the carbon steel and alloy steel block (443). The outer surface of the support plate (442) is movably connected to the inner wall of the buffer groove (4410).

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