A broaching tool structure with complementary profiled cutting edges

Abstract

The application provides a broaching tool structure with complementary special-shaped cutting edges, comprising a tool handle, a precision adjusting assembly, a tool seat and a broaching blade; the bottom of a guide rail seat is fixed on the tool handle, and the top of the guide rail seat is provided with a sliding groove matched with a sliding seat, and the tool seat is fixed on the sliding seat; the guide rail seat is provided with an adjusting groove below the sliding groove, a first wedge block and a second wedge block are arranged in the adjusting groove, and the inclined surfaces of the two wedge blocks are matched; the guide rail seat is provided with an adjusting hole, a circular tube-shaped boss is arranged on the outer side surface of the first wedge block, the boss is arranged in the adjusting hole, a coarse adjusting sleeve is arranged in the adjusting hole in an axial direction and is sleeved on the boss and is in threaded connection with the boss, a fine adjusting screw rod is arranged in the boss in an axial direction and is in threaded connection with the outer side surface of the first wedge block, the second wedge block is connected with the bottom of the sliding seat, and elastic return members are arranged between the first wedge block or the second wedge block and the adjusting groove. The application solves the problems that the position of the cutting edge of the existing broaching tool cannot be adjusted or the resolution of the adjustment is low.

Description

Technical Field

[0001] This invention belongs to the technical field of broaching equipment, and specifically relates to a broaching tool structure with complementary irregular cutting edges. Background Technology

[0002] In the field of pipe fitting processing technology, the internal square hole structure of pipe fittings is widely used in various mechanical connections and transmission components. Currently, CNC milling technology is relatively mature for machining conventionally shaped internal square holes and is widely used in various mechanical manufacturing scenarios. This technology controls the movement trajectory of the milling head through a CNC system, enabling high-precision hole machining to meet general industrial needs.

[0003] However, for irregularly shaped internal square hole structures with complex geometric features, such as the internal hole curvature curves, trumpet shapes, parabolic shapes, and other irregular contours found in batches of pipe fittings, existing CNC milling methods still face many technical bottlenecks. Specifically, due to the narrow and elongated internal space of the pipe fittings and the large overhang of the milling head, the system rigidity is relatively insufficient, making chatter prone to occur during machining, affecting cutting stability and surface quality. At the same time, milling cannot complete the forming of complex contours in one go, often requiring multiple clamping and multi-process combinations, which makes precision control difficult and machining efficiency low.

[0004] Broaching offers advantages such as high precision, high efficiency, and one-time forming, making it a potential alternative to address the aforementioned problems. However, existing broaching tools are typically integral structures with non-adjustable cutting edge positions. This leads to difficulties in adapting to dimensional deviations of different components and inability to eliminate clamping errors (the cumulative errors from multiple clamping operations between the tool and machine spindle, and between the workpiece and the worktable, cannot be compensated for by the tool itself, resulting in a high scrap rate for the first batch of machined parts). Furthermore, tool wear cannot be compensated online. Even when some tools are adjustable, most rely on single-stage threads or eccentric sleeve structures for adjustment, resulting in limited adjustment methods, low precision, low resolution, poor vibration resistance, and a tendency to shift and loosen under high cutting forces.

[0005] To address the aforementioned issues, there is an urgent need to develop a new broaching tool structure capable of achieving high-precision position adjustment and matching the cutting edge contour to complex irregular internal cavities. Summary of the Invention

[0006] The purpose of this invention is to provide a broaching tool structure with complementary irregular cutting edges, which solves the problems of existing broaching tools having unadjustable cutting edge positions or low adjustment resolution and poor vibration resistance.

[0007] To achieve the above objectives, the solution of the present invention is to provide a broaching tool structure with complementary irregular cutting edges, including a tool holder, a precision adjustment component, a tool holder, and broaching inserts; The precision adjustment assembly includes a slide, a guide rail, a first wedge, a second wedge, a fine adjustment screw, a coarse adjustment sleeve, and an elastic reset component. The bottom of the guide rail is fixed to the tool holder, and the top of the guide rail is provided with a sliding groove. The bottom of the slide is provided with a slider that cooperates with the sliding groove. The tool holder is fixed to the top of the slide, and the broaching blade is fixed to the tool holder. The guide rail seat has an adjustment groove communicating with the slide groove below it. The first wedge block, the second wedge block, and the elastic reset member are all set in the adjustment groove. The inclined surfaces of the first wedge block and the second wedge block are engaged with each other. The side wall of the guide rail seat has an adjustment hole communicating with the adjustment groove. The outer side of the first wedge block facing the adjustment hole has a cylindrical boss. The boss passes through the adjustment hole. The coarse adjustment sleeve is axially limited in the adjustment hole and is sleeved on the boss and threadedly connected to the boss. The boss is hollow. The outer side of the first wedge block has a threaded hole corresponding to the position inside the boss. The fine adjustment screw is axially limited in the boss and screwed to the threaded hole. The second wedge block is connected to the slider at the bottom of the slide. Rotating the coarse adjustment sleeve and the fine adjustment screw drives the first wedge block to move along the axial direction of the adjustment hole, thereby pushing the second wedge block to drive the slide to move along the radial direction of the adjustment hole, realizing the coarse and fine adjustment of the broaching tool position. An elastic reset member is provided between the first wedge block or the second wedge block and the wall of the adjusting groove, and the extension and retraction direction of the elastic reset member is the same as the movement direction of the second wedge block.

[0008] Furthermore, the precision adjustment component also includes an L-shaped block, which is disposed between the first wedge block and the wall of the adjustment groove. The L-shaped block is in the shape of an L-shaped plate, and its two mutually perpendicular inner surfaces are respectively attached to the two mutually perpendicular outer surfaces of the first wedge block. The boss is disposed on the outer surface of the L-shaped block facing the adjustment hole. The fine adjustment screw passes through the L-shaped block and is screwed into the threaded hole. The height of the L-shaped block is the same as the depth of the adjustment groove.

[0009] Furthermore, the precision adjustment assembly also includes a first shim and a second shim. The fine-tuning screw has an annular first stop shoulder on its outer periphery. The outer end of the boss has a first stepped groove, and the first stop shoulder fits into the first stepped groove. The outer end of the boss has a screw mounting hole on the outside of the first stepped groove. The first shim is fixed to the outer end of the boss by a screw to axially limit the fine-tuning screw. The outer end of the coarse-tuning sleeve has an annular second stop shoulder. The guide rail seat has a second stepped groove on the outer end of the adjustment hole, and the second stop shoulder fits into the second stepped groove. The guide rail seat has a screw mounting hole on the outside of the second stepped groove. The second shim is fixed to the guide rail seat by a screw to axially limit the coarse-tuning sleeve. The head of the fine-tuning screw has a first drive groove, the tail of the fine-tuning screw is screwed into a threaded hole, and the outer end of the coarse-tuning sleeve has a second drive groove. The first drive groove and the second drive groove are used to cooperate with a wrench to drive the first fine-tuning screw and the coarse-tuning sleeve to rotate.

[0010] Furthermore, the precision adjustment assembly also includes a connecting rod, the two ends of which are respectively connected to the slider and the second wedge block. A guide groove is provided between the sliding groove and the adjustment groove. A cylindrical guide block is provided in the middle of the connecting rod to cooperate with the guide groove. The guide rail seat has an installation port communicating with the adjustment groove on the side wall outside the second wedge block. A baffle is provided at the installation port. The baffle is connected to the guide rail seat by screws. The elastic reset member is disposed between the second wedge block and the baffle.

[0011] Furthermore, several rollers abut between the inclined surfaces of the first and second wedge blocks.

[0012] Furthermore, the precision adjustment component is provided in two sets. The guide rail seat of the first set of precision adjustment components and the slide seat of the second set of precision adjustment components are connected and fixedly arranged vertically, and the two sets of precision adjustment components are distributed vertically and alternately.

[0013] Furthermore, two broaching blades are arranged side by side, and the edges of the broaching blades are evenly distributed with multiple serrated teeth. The teeth of the two broaching blades are staggered. Blade support plates are provided between the tool holder and the broaching blades, as well as between the two broaching blades.

[0014] Furthermore, during broaching, the tool holder is connected to the machine tool spindle, and the tube is fixed on the rotary table of the CNC machine tool. The profile of the broaching insert is designed according to the cross-sectional shape of the inner hole of the tube. The inner hole of the tube is rectangular, and the two right-angled sides of the broaching insert are evenly distributed with cutting teeth. The cross-section of the tube is divided into four symmetrical cutting areas along two mutually perpendicular center lines. The broaching insert completes the inner hole machining of the tube in four cuts. The effective length of the right-angled side of each cutting area is half the width of the tube plus a fixed increment.

[0015] Furthermore, the tool holder is equipped with two sets of traveling components. Each traveling component includes a U-shaped bracket, a roller shaft, a bearing shaft, a bearing, and wheels. The U-shaped bracket includes two support arms and a connecting arm connecting the two support arms. A bearing is embedded in the middle of the two support arms. The two ends of the bearing shaft pass through the inner ring of the bearing, and the middle of the bearing shaft is perpendicularly connected to the middle of the roller shaft. Wheels are rotatably mounted at both ends of the roller shaft. The connecting arm of the U-shaped bracket is connected to the tool holder. The U-shaped brackets of the two traveling components are perpendicularly distributed, so that the wheels of the two traveling components respectively fit on two vertical surfaces inside the pipe. The wheel hub is made of steel, and the outer layer of the wheel is made of wear-resistant engineering plastic.

[0016] Furthermore, the connecting arm of the U-shaped bracket is provided with a mounting through hole in the middle, and a snap ring shaft is installed in the mounting through hole. The top of the tool holder is provided with an L-shaped plate, which is composed of two mutually perpendicular fixing plates. The bottom of the two fixing plates is fixed to the tool holder. The snap ring shafts of the two U-shaped brackets are respectively fixed to the two fixing plates by screws. A compression spring is sleeved on the snap ring shaft, and the compression spring is located between the connecting arm and the fixing plate.

[0017] After adopting the above solution, the beneficial effects of the present invention are as follows: 1. This solution utilizes the helical transmission between the fine-tuning screw and the coarse-tuning sleeve and the first wedge block to make the broaching insert position adjustable. The different pitches of the fine-tuning screw and the coarse-tuning sleeve result in different adjustment accuracies, ensuring a wide adjustment range while achieving micron-level adjustment resolution. This is a multi-stage adjustment mechanism combining coarse and fine adjustments. During adjustment, the coarse-tuning sleeve is rotated first for coarse adjustment, bringing the position close to the target. Then, the fine-tuning screw is rotated for fine adjustment, achieving precise final position adjustment of the broaching insert. In this process, coarse adjustment is used to quickly approach the target position, while fine adjustment is used for micron-level positioning. The overall adjustment balances efficiency and accuracy, effectively compensating for clamping errors, machine tool motion errors, and tool wear, significantly improving the positional accuracy and consistency of broaching machining.

[0018] 2. The wedge-shaped inclined surface transmission of the two wedge blocks in the precision adjustment component has a self-locking characteristic. The pre-tightening of the elastic reset component can eliminate the gap. It will not displace or loosen under the large cutting impact force generated by broaching, which is significantly better than the traditional eccentric sleeve or fine thread structure.

[0019] 3. The precision adjustment component has a compact structure and is easy to operate. It is suitable for pipe fittings of different specifications or different parabolic parameters. Only the customized broaching blade needs to be replaced and readjusted. There is no need to replace the entire tool, which reduces production costs.

[0020] 4. This application installs two fine-tuning components vertically and alternately, which can calibrate the tool center and cutting radius in two mutually perpendicular directions to ensure the symmetry, perpendicularity and contour tolerances of the square tube inner cavity.

[0021] 5. This application features a staggered arrangement of the teeth on the two broaching inserts. This structure creates staggered cutting paths in the cross-section of the inserts, reducing the peak cutting force per pass and suppressing chatter and resonance. Furthermore, the serrated tooth shape optimizes chip breaking and removal capabilities, preventing chip accumulation or secondary scratches in the inner cavity of long tubes. The insert support plate shares the same contour as the broaching inserts and fits tightly together, forming a high-rigidity composite structure that enhances the cutting edge's resistance to deformation.

[0022] 6. The compression spring in the traveling mechanism maintains constant elastic contact between the U-shaped bracket and the wheels, which can absorb dynamic vibrations during broaching and improve machining stability; the multi-wheel rolling structure reduces frictional resistance and ensures that the tool moves smoothly along the predetermined trajectory. Attached Figure Description

[0023] Figure 1 This is a perspective view of the broaching tool of the present invention; Figure 2 This is an exploded view of the broaching tool of the present invention; Figure 3 This is a perspective view of the precision adjustment component of the present invention; Figure 4 This is a schematic diagram showing the fit between the slide and the guide rail of the present invention; Figure 5 This is an exploded view of the precision adjustment component of the present invention; Figure 6 This is a partial cross-sectional view of the precision adjustment component of the present invention; Figure 7 This is a schematic diagram of the internal structure of the guide rail base of the present invention; Figure 8 This is a schematic diagram of the fine-tuning screw of the present invention; Figure 9 This is a schematic diagram of the coarse adjustment sleeve of the present invention; Figure 10 This is a schematic diagram of the structure of the second wedge block of the present invention; Figure 11 This is a schematic diagram of the walking component of the present invention; Figure 12 This is a schematic diagram of the blade assembly of the present invention; Figure 13 This is a schematic diagram of the broaching tool of the present invention working on the worktable; Figure 14 This is a schematic diagram of the pipe structure after processing by the broaching tool of the present invention; Figure 15This is a cross-sectional view of the pipe after processing with the broaching tool of the present invention.

[0024] Label Explanation: 1. Tool holder; 2. Precision adjustment assembly; 21. Slide; 211. Slider; 212. Groove; 22. Guide rail seat; 221. Slide groove; 222. Adjustment groove; 223. Adjustment hole; 224. Second step groove; 225. Guide groove; 226. Mounting port; 227. Baffle; 2271. Mounting post; 228. Guide rail; 229. Protrusion; 23. First wedge block; 231. Threaded hole; 24. Second wedge block; 241. Roller; 242. Mounting groove; 243. Bolt; 244. Rectangular hole; 245. Annular mounting groove; 25. Fine adjustment screw; 251. First washer; 252. First stop shoulder; 253. First drive groove; 26. Coarse adjustment sleeve; 261. Second washer; 26 2. Second stop shoulder; 263. Second drive groove; 27. Elastic reset component; 28. L-shaped block; 281. Boss; 282. First step groove; 29. ​​Connecting rod; 291. Guide block; 3. Tool holder; 31. U-shaped groove; 4. Broaching insert; 41. Cutting tooth; 42. Insert support plate; 43. Mounting plate; 44. Notch; 45. Positioning hole; 5. Rotary worktable; 6. Square tube; 7. Outer shaft sleeve; 8. Traveling assembly; 81. U-shaped bracket; 811. Support arm; 812. Connecting arm; 813. Mounting through hole; 82. Roller shaft; 821. Rectangular keyway; 83. Bearing shaft; 84. Bearing; 85. Wheel; 9. L-shaped plate; 91. Snap ring shaft; 92. Compression spring; 93. Retaining ring. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] like Figures 1-14As shown, this application provides a broaching tool structure with complementary irregular cutting edges, including a tool holder 1, a precision adjustment component 2, a tool holder 3, and a broaching insert 4. The precision adjustment component 2 includes a slide 21, a guide rail 22, a first wedge block 23, a second wedge block 24, a fine-tuning screw 25, a coarse-tuning sleeve 26, and an elastic reset component 27. The bottom of the guide rail 22 is fixed to the tool holder 1, and the top of the guide rail 22 is provided with a groove 221. The bottom of the slide 21 is provided with a slider 211 that cooperates with the groove 221. The tool holder 3 is fixed to the top of the slide 21, and the broaching insert 4 is fixed to the tool holder 3. Thus, the position of the broaching insert 4 can be adjusted by sliding the slide 21 relative to the guide rail 22. Preferably, the groove 221 is a dovetail groove 221, and the slider 211 is a dovetail slider 211. The two cooperate to form a dovetail guide rail pair, which improves the contact stiffness.

[0027] Key references Figures 3-10 The guide rail seat 22 has an adjustment groove 222 communicating with the slide groove 221 below the slide groove 221. The first wedge block 23, the second wedge block 24, and the elastic reset member 27 are all disposed in the adjustment groove 222. The inclined surfaces of the first wedge block 23 and the second wedge block 24 are engaged with each other. The side wall of the guide rail seat 22 has an adjustment hole 223 communicating with the adjustment groove 222. The adjustment hole 223 is disposed through the side wall of the guide rail seat 22. The outer surface of the first wedge block 23 facing the adjustment hole 223 has a cylindrical boss 281. The boss 281 passes through the adjustment hole 223. The coarse adjustment sleeve 26 is sculpted. The first wedge block 23 is axially limited within the adjustment hole 223 and is threaded onto the boss 281. The boss 281 is hollow, and the outer side of the first wedge block 23 has a threaded hole 231 corresponding to the position inside the boss 281. The fine-tuning screw 25 is axially limited within the boss 281 and threaded into the threaded hole 231. The second wedge block 24 is connected to the slider 211 at the bottom of the slide block 21. An elastic reset member 27 is provided between the first wedge block 23 or the second wedge block 24 and the groove wall of the adjustment groove 222. The extension and retraction direction of the elastic reset member 27 is the same as the movement direction of the second wedge block 24. Since both the coarse adjustment sleeve 26 and the fine adjustment screw 25 are axially limited, they can only rotate circumferentially within the adjustment hole 223 and cannot move along the axis of the adjustment hole 223. The first wedge block 23 also cannot rotate within the adjustment groove 222. Therefore, rotating the coarse adjustment sleeve 26 and the fine adjustment screw 25 respectively drives the first wedge block 23 to move along the axial direction of the adjustment hole 223, which in turn pushes the second wedge block 24 to move the slide block 21 radially along the adjustment hole 223, thus adjusting the position of the broaching tool 4. The fine adjustment screw 25 has a different pitch than the coarse adjustment sleeve 26, resulting in different adjustment accuracies. This ensures a large adjustment range while achieving micron-level adjustment resolution, forming a graded adjustment mechanism of coarse adjustment + fine adjustment.

[0028] During adjustment, the coarse adjustment sleeve 26 can be rotated first for coarse adjustment, and after adjusting to near the target position, the fine adjustment screw 25 can be rotated for fine adjustment to achieve precise adjustment of the final position of the broaching insert 4. In this adjustment process, coarse adjustment is used to quickly approach the target position, and fine adjustment is used for micron-level positioning. The overall adjustment takes into account both adjustment efficiency and accuracy, effectively compensating for clamping errors, machine tool motion errors and tool wear, and significantly improving the positional accuracy and consistency of broaching. Furthermore, the wedge-shaped inclined surface transmission of the two wedge blocks in the precision adjustment component 2 has a self-locking characteristic. Combined with the pre-tightening of the elastic reset component 27, it can eliminate gaps and will not displace or loosen under the large cutting impact force generated by broaching, which is significantly better than the traditional eccentric sleeve or fine thread structure. In addition, the precision adjustment component 2 has a compact structure and is easy to operate. It is suitable for pipe fittings of different specifications or different parabolic parameters. Only the customized broaching insert 4 needs to be replaced and readjusted, without the need to replace the entire tool, thus reducing production costs.

[0029] Key references Figures 5-7 The precision adjustment component 2 further includes an L-shaped block 28, which is disposed between the first wedge block 23 and the groove wall of the adjustment groove 222. The L-shaped block 28 is L-shaped plate, and its two mutually perpendicular inner surfaces are respectively attached to the two mutually perpendicular outer surfaces of the first wedge block 23. The adjustment groove 222 can be a rectangular deep groove, and the two mutually perpendicular outer surfaces of the L-shaped block 28 are respectively attached to the two walls of the adjustment groove 222. The boss 281 is disposed on the outer surface of the L-shaped block 28 facing the adjustment hole 223. The L-shaped block 28 has a through hole inside the boss 281 for the fine adjustment screw 25 to pass through, so that the fine adjustment screw 25 passes through the L-shaped block 28 and is screwed into the threaded hole 231. During adjustment, rotating the coarse adjustment sleeve 26 moves the L-shaped block 28 along the axial direction of the adjustment hole 223, thereby pushing the first wedge block 23 to move. The height of the L-shaped block 28 is the same as the depth of the adjustment groove 222, which restricts the rotational movement of the L-shaped block 28. Furthermore, the contact between the L-shaped block 28 and the first wedge block 23 further restricts the rotational movement of the first wedge block 23, eliminating the need for other limiting structures. Additionally, the height of the first wedge block 23 and the second wedge block 24 is preferably the same as the depth of the adjustment groove 222 to prevent the first wedge block 23 and the second wedge block 24 from moving up and down, thus affecting the adjustment accuracy.

[0030] Since the inclined surface of the first wedge block 23 directly slides and abuts against the inclined surface of the second wedge block 24, under the pre-tightening force of the elastic reset member 27, a large frictional force will be generated between the two inclined surfaces, resulting in a sudden change in static friction. This can easily lead to discontinuous displacement during adjustment (for example, after rotating the fine adjustment screw 25, the second wedge block 24 may not move at first, and then suddenly move a large distance). The adjustment is laborious and unstable. Therefore, it is preferable to set several rollers 241 between the inclined surfaces of the first wedge block 23 and the second wedge block 24. This can convert the sliding friction between the inclined surfaces of the two wedge blocks into rolling friction, reduce the frictional force, make the adjustment operation more convenient and labor-saving, and also make the movement of the second wedge block 24 linearly related to the rotation angle of the fine adjustment screw 25 or the coarse adjustment sleeve 26, so that the adjustment is stable and controllable.

[0031] Key references Figures 5-9 The precision adjustment assembly 2 further includes a first shim 251 and a second shim 261. The fine-tuning screw 25 has an annular first stop shoulder 252 on its outer periphery. The first stop shoulder 252 can be an annular flange structure. The outer end of the boss 281 has a first stepped groove 282. The first stop shoulder 252 fits into the first stepped groove 282. The outer end of the boss 281 has a screw mounting hole on the outside of the first stepped groove 282. The first shim 251 is attached to the boss by a screw. The outer end of 281 is fixed. The first washer 251 has a through hole aligned with the screw mounting hole for the screw to pass through. The inner diameter of the first washer 251 is smaller than the outer diameter of the first stepped groove 282, and the inner diameter is greater than or equal to the diameter of the head of the fine adjustment screw 25 (the head is located at the outer end), so that the head of the fine adjustment screw 25 is exposed, which facilitates adjustment. At the same time, it can axially limit the fine adjustment screw 25 between the first stepped groove 282 and the first washer 251. The fine adjustment screw 25 cannot move axially and can only rotate.

[0032] The limiting structure of the coarse adjustment sleeve 26 is similar to that of the fine adjustment screw 25 and operates on the same principle. Specifically, the outer end of the coarse adjustment sleeve 26 is provided with an annular second stop shoulder 262. The guide rail seat 22 is provided with a second stepped groove 224 at the outer end of the adjustment hole 223. The second stop shoulder 262 fits into the second stepped groove 224. The guide rail seat 22 is provided with a screw mounting hole on the outer side of the second stepped groove 224. The second washer 261 is fixed to the guide rail seat 22 by a screw to axially limit the coarse adjustment sleeve 26. The second washer 261 is provided with a through hole for the screw to pass through. The inner diameter of the second washer 261 is smaller than the outer diameter of the second stepped groove 224, and the inner diameter is greater than or equal to the outer end diameter of the coarse adjustment sleeve 26, so that the outer end of the coarse adjustment sleeve 26 is exposed.

[0033] Preferably, the head of the fine-tuning screw 25 is provided with a first drive groove 253, the tail of the fine-tuning screw 25 is screwed into the threaded hole 231, and the outer end of the coarse-tuning sleeve 26 is provided with a second drive groove 263. The first drive groove 253 and the second drive groove 263 are used to cooperate with a wrench. The wrench is inserted into the first drive groove 253 and the second drive groove 263 to drive the fine-tuning screw 25 and the coarse-tuning sleeve 26 to rotate. Specifically, the first drive groove 253 and the second drive groove 263 can be internal hexagon countersunk grooves for cooperation with an internal hexagon wrench. The head of the fine-tuning screw 25 is provided with an arc surface, and the arc surface is provided with graduations for easy fine adjustment.

[0034] Key references Figure 5 and Figure 10 The second wedge block 24 has a mounting groove 242 on its inclined surface. The top wall of the mounting groove 242 has through holes for mates with bolts 243. Rollers 241 are mounted in the mounting groove 242 using bolts 243; specifically, two rollers 241 can be installed. The precision adjustment assembly 2 also includes a connecting rod 29. Both ends of the connecting rod 29 are connected to the slider 211 and the second wedge block 24, respectively, to connect the slider 211 and the second wedge block 24. Specifically, the top end of the connecting rod 29 is cylindrical and threaded, threaded to the center of the slider 211. The bottom end of the connecting rod 29 is rectangular, and a rectangular hole 244 is provided at the top of the second wedge block 24 to engage with the bottom of the connecting rod 29.

[0035] Preferably, a guide groove 225 is provided between the sliding groove 221 and the adjusting groove 222. A cylindrical guide block 291 is provided in the middle of the connecting rod 29 to cooperate with the guide groove 225. The guide groove 225 can restrict the linear sliding of the guide block 291 and prevent the second wedge block 24 from deviating, thus affecting the adjustment accuracy. The guide rail seat 22 has an installation port 226 communicating with the adjusting groove 222 on the side wall outside the second wedge block 24. A baffle 227 is provided at the installation port 226, and the baffle 227 is connected to the guide rail seat 22 by screws. A pair of guide rails 228 are provided between the sliding groove 221 and the adjusting groove 222, and a guide groove 225 is formed between the guide rails 228. Screw mounting holes are provided on the end face of the guide rails 228 corresponding to the installation port 226 to connect with the baffle 227. The elastic reset element 27 is disposed between the second wedge block 24 and the baffle 227. The elastic reset element 27 is preferably a spring. The inner side of the baffle 227 is provided with a mounting post 2271. The side of the second wedge block 24 facing the baffle 227 is provided with an annular mounting groove 242. One end of the spring is sleeved on the mounting post 2271, and the other end is embedded in the annular mounting groove 242. The mounting port 226 facilitates the installation of the first wedge block 23, the second wedge block 24, and the elastic reset element 27 into the adjusting groove 222.

[0036] Key references Figures 1-2 The precision adjustment component 2 has two sets. The guide rail seat 22 of the first set of precision adjustment components is vertically connected and fixedly set with the slide seat 21 of the second set of precision adjustment components. The two sets of precision adjustment components 2 are vertically staggered and can independently adjust the position of the broaching blade 4 in the X and Y axis directions, realizing fine adjustment in two mutually perpendicular directions to meet the adjustment requirements of the broaching blade 4. The guide rail seat 22 of the first set of precision adjustment components has a downward protrusion 229 at the bottom, and the slide seat 21 of the second set of precision adjustment components has a groove 212 at the top that mates with the protrusion 229. The groove 212 and the protrusion 229 are locked together with multiple screws. The protrusion 229 and the groove 212 can be cylindrical.

[0037] The slide 21 and guide rail 22 can be cylindrical, and the tool holder 3 is cylindrical in shape, with a U-shaped groove 31 on its top for mounting the broaching blade 4. The tool holder 3 is vertically connected to the first set of precision adjustment components, and the connection structure is the same as the connection structure between the two sets of precision adjustment components 2. The second set of precision adjustment components is vertically connected to the tool holder 1, and the connection structure is also the same as the connection structure between the two sets of precision adjustment components 2.

[0038] The broaching insert 4 is a precision broaching insert 4 customized for machining the internal square hole of a pipe fitting, such as Figures 14-15 As shown, in one embodiment, the broaching blade 4 is used to process a slender hollow square tube 6. The inside of the square tube 6 is a rectangular hole with an approximately square cross-section. The four inner corners of the square hole are rounded, and the square hole changes with a precise parabolic arc along the length of the square tube 6. This square hole structure is the key to achieving efficient continuous casting heat transfer and molten steel flow in the parabolic square hole inside the tube wall, which directly affects the surface quality of the billet and the stability of production. Therefore, it places extremely high demands on the precision, stability and surface integrity of the broaching process.

[0039] To complete such a complex and precise internal cavity contour in a single broaching operation, during machining, such as Figure 13 As shown, the tool holder 1 is directly connected to the machine tool spindle, and the square tube 6 is fixed on the rotary table 5, which is dedicated to the CNC machine tool. The broaching insert 4 moves in a straight line, while the rotary table 5 rotates slowly. The combined motion trajectories of the two form a parabolic trajectory. The formula for the trajectory of the cutting point is derived as follows: The origin of the machine tool coordinate system is located at the center of the square tube 6. The broaching insert 4 moves in a straight line, and its position always satisfies the following:

[0040] In the formula, r is the cutting radius, V is the feed rate of the broaching insert 4, and t is the time; The tube 6 below the workpiece coordinate system rotates slowly around the origin by an angle of:

[0041] The coordinates of any point in the machine tool coordinate system can be converted to the workpiece coordinate system as follows:

[0042]

[0043] Substituting Xb=r, Yb=Vt, and θ=ωt, we obtain the formula for the arc trajectory of the final cutting point on the inner wall of square tube 6:

[0044]

[0045] This application features a broaching insert 4 specifically designed to match the cross-sectional profile of the inner surface of the square tube 6. Multiple serrated teeth 41 are evenly distributed along the edges of its two right-angled sides. Since the four corners of the inner hole of the square tube 6 are rounded, the broaching insert 4 can machine the two perpendicular inner surfaces of the tube through a rounded transition between its two right-angled sides. During machining, the entire cross-section of the square tube 6 is divided into four symmetrical cutting regions along two perpendicular centerlines. The broaching insert 4 can cut one region at a time, completing the inner hole machining of the tube in four cuts. Each cutting region consists of a parabolic arc edge and two right-angled sides. The effective length of the right-angled side in each cutting region is half the width of the tube plus a fixed increment. The fixed increment is the overlapping portion of multiple broaching cuts, and its length is less than half the width of the tube, ensuring a unique irregular profile structure that matches the parabolic inner shape and rounded corners of the square tube 6. This four-segment segmentation and complementary cutting edge design ensures that the broaching insert 4 can simultaneously achieve gradual cutting of the parabolic arc surface and precise rounding of the four inner corners as it passes through the slender tube. This avoids problems such as local overcutting, undercutting, vibration, or residual bumps and depressions that occur in the continuous curvature area of ​​traditional straight cutting edges or single arc-shaped tools.

[0046] Key references Figure 12 Two broaching inserts 4 are arranged side by side, with their teeth 41 staggered. This staggered tooth arrangement creates an interlaced cutting path on the same cross section, significantly reducing the peak cutting force in a single pass and suppressing chatter and resonance during broaching. The serrated tooth shape optimizes chip breaking and removal performance, effectively preventing chip accumulation, blockage, or secondary scratches in the inner cavity of the pipe. Insert support plates 42 are provided between the tool holder 3 and the broaching inserts 4, as well as between the two broaching inserts 4. The broaching inserts 4 and the insert support plates 42 combine to form an insert assembly. The shape and contour of the insert support plates 42 are consistent with the broaching inserts 4, but they do not have teeth 41. The two are precisely fitted together to form a high-rigidity composite structure, maximizing the broaching inserts 4's resistance to deformation and cutting stability under high loads.

[0047] The broaching blade 4 has a mounting plate 43 at the diagonal of its opposite rounded corner, which mates with the U-shaped groove 31 of the tool holder 3. The mounting plate 43 has notches 44 on both sides to allow space for the groove wall of the U-shaped groove 31, preventing interference with the tool holder 3. Specifically, the mounting plate 43 can be a hexagonal plate structure that mates with the structure of the U-shaped groove 31. The blade support plate 42 also has a mounting plate 43, and the mounting plate 43 has a positioning hole 45 in its center for fixed installation. An outer shaft sleeve 7 is provided above the tool holder 3. The bottom of the outer shaft sleeve 7 has a U-shaped boss that mates with the U-shaped groove 31. The outer shaft sleeve 7 is fixed to the tool holder 3 by multiple screws. The cutting tool assembly is fixed between the outer shaft sleeve 7 and the tool holder 3. A screw passes through the outer shaft sleeve 7 and is threaded into the positioning hole 45 to fix the outer shaft sleeve 7 and the cutting tool assembly. This ensures that the outer shaft sleeve 7 and the tool holder 3 provide sufficient support for the broaching cutting tool 4. The broaching cutting tool 4 has exposed sides of the cutting teeth 41 that are not between the outer shaft sleeve 7 and the tool holder 3.

[0048] Key references Figures 1-2 and Figure 11 The tool holder 3 is equipped with two sets of traveling components 8. Each traveling component 8 includes a U-shaped bracket 81, a roller shaft 82, a bearing shaft 83, a bearing 84, and wheels 85. The U-shaped bracket 81 has a U-shaped structure and includes two support arms 811 and a connecting arm 812 connecting the two support arms 811. The bearing 84 is embedded in the middle of the two support arms 811. The bearing 84 can be a deep groove ball bearing 84. The two ends of the bearing shaft 83 are respectively inserted into the inner ring of the bearing 84. The middle of the bearing shaft 83 is perpendicularly connected to the middle of the roller shaft 82. The bearing shaft 83 can be fixed by embedding it into the through hole in the middle of the roller shaft 82, or it can be connected and fixed by other methods. Wheels 85 are rotatably mounted at both ends of the roller shaft 82. Specifically, rectangular keyways 821 can be provided at both ends of the roller shaft 82, and through holes can be made in the rectangular keyways 821 to install the rotating shaft of the wheel 85. The wheels 85 at both ends are respectively installed on both sides of the roller shaft 82. The connecting arm 812 of the U-shaped bracket 81 is connected to the tool holder 3, specifically to the outer shaft sleeve 7 on the tool holder 3. The U-shaped brackets 81 of the two sets of walking components 8 are vertically distributed, so that the wheels 85 of the two sets of walking components 8 can travel smoothly on the two inner wall surfaces of the pipe respectively.

[0049] Specifically, the top of the outer shaft sleeve 7 is provided with an L-shaped plate 9. The L-shaped plate 9 can be integrally set with the outer shaft sleeve 7, or it can be connected and fixed by a connecting structure. The L-shaped plate 9 consists of two mutually perpendicular fixing plates, and the bottom of the two fixing plates is fixed to the tool holder 3. The connecting arm 812 of the U-shaped bracket 81 is provided with a mounting through hole 813 in the middle. A snap ring shaft 91 is installed in the mounting through hole 813. The snap ring shafts 91 of the two U-shaped brackets 81 are respectively fixed to the two fixing plates by screws. A retaining ring 93 is fixed to the outside of the connecting arm 812 to prevent the U-shaped bracket 81 from detaching from the snap ring shaft 91. A compression spring 92 is sleeved on the snap ring shaft 91. The compression spring 92 is located between the connecting arm 812 and the fixing plate. The compression spring 92 can absorb dynamic vibrations during broaching and improve machining stability.

[0050] Furthermore, the hub of the wheel 85 is made of steel, while the outer layer of the wheel 85 is made of wear-resistant engineering plastic. That is, the wheel 85 employs a composite structure of a steel hub and a wear-resistant engineering plastic outer layer. The steel hub provides extremely high strength and rigidity, withstanding the enormous radial loads and impacts during broaching without deformation. The outer wear-resistant engineering plastic layer is specifically designed for copper tubing, possessing an extremely low coefficient of friction, excellent self-lubrication, and chemical inertness, forming a perfect "hard-soft" match with the soft copper alloy inner wall. This composite structure eliminates the inherent metal-to-metal engagement, scratches, or embedding phenomena of traditional all-metal wheels, sliding rails, or bronze sliders, preventing any microscopic scratches or surface hardening on the high-precision inner surface, ensuring uniform adhesion and meeting roughness requirements for subsequent chromium plating; significantly extending the wheel's own lifespan and reducing potential damage to expensive copper tubing.

[0051] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0052] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A broaching tool structure with complementary irregular cutting edges, characterized in that: Includes tool holder, precision adjustment assembly, tool holder, and broaching insert; The precision adjustment assembly includes a slide, a guide rail, a first wedge, a second wedge, a fine adjustment screw, a coarse adjustment sleeve, and an elastic reset component. The bottom of the guide rail is fixed to the tool holder, and the top of the guide rail is provided with a sliding groove. The bottom of the slide is provided with a slider that cooperates with the sliding groove. The tool holder is fixed to the top of the slide, and the broaching blade is fixed to the tool holder. The guide rail seat has an adjustment groove communicating with the slide groove below it. The first wedge block, the second wedge block, and the elastic reset member are all set in the adjustment groove. The inclined surfaces of the first wedge block and the second wedge block are engaged with each other. The side wall of the guide rail seat has an adjustment hole communicating with the adjustment groove. The outer side of the first wedge block facing the adjustment hole has a cylindrical boss. The boss passes through the adjustment hole. The coarse adjustment sleeve is axially limited in the adjustment hole and is sleeved on the boss and threadedly connected to the boss. The boss is hollow. The outer side of the first wedge block has a threaded hole corresponding to the position inside the boss. The fine adjustment screw is axially limited in the boss and screwed to the threaded hole. The second wedge block is connected to the slider at the bottom of the slide. Rotating the coarse adjustment sleeve and the fine adjustment screw drives the first wedge block to move along the axial direction of the adjustment hole, thereby pushing the second wedge block to drive the slide to move along the radial direction of the adjustment hole, realizing the coarse and fine adjustment of the broaching tool position. The precision adjustment assembly further includes a first shim and a second shim. The first shim is fixed to the outer end of the boss by a screw to axially limit the fine adjustment screw, and the second shim is fixed to the guide rail seat by a screw to axially limit the coarse adjustment sleeve. An elastic reset member is provided between the second wedge block and the wall of the adjusting groove, and the extension and retraction direction of the elastic reset member is the same as the movement direction of the second wedge block.

2. The broaching tool structure with complementary irregular cutting edges as described in claim 1, characterized in that: The precision adjustment assembly also includes an L-shaped block, which is disposed between the first wedge block and the wall of the adjustment groove. The L-shaped block is in the shape of an L-shaped plate, and its two mutually perpendicular inner surfaces are respectively attached to the two mutually perpendicular outer surfaces of the first wedge block. The boss is disposed on the outer surface of the L-shaped block facing the adjustment hole. The fine adjustment screw passes through the L-shaped block and is screwed into the threaded hole. The height of the L-shaped block is the same as the depth of the adjustment groove.

3. The broaching tool structure with complementary irregular cutting edges as described in claim 2, characterized in that: The fine-tuning screw has an annular first stop shoulder on its outer periphery. The outer end of the boss has a first stepped groove, and the first stop shoulder fits into the first stepped groove. The outer end of the boss has a screw mounting hole on the outside of the first stepped groove. The outer end of the coarse-tuning sleeve has an annular second stop shoulder. The guide rail seat has a second stepped groove on the outer end of the adjustment hole, and the second stop shoulder fits into the second stepped groove. The guide rail seat has a screw mounting hole on the outside of the second stepped groove. The head of the fine-tuning screw has a first drive groove, the tail of the fine-tuning screw is screwed into a threaded hole, and the outer end of the coarse-tuning sleeve has a second drive groove. The first drive groove and the second drive groove are used to cooperate with a wrench to drive the fine-tuning screw and the coarse-tuning sleeve to rotate.

4. The broaching tool structure with complementary irregular cutting edges as described in claim 1, characterized in that: The precision adjustment assembly also includes a connecting rod, the two ends of which are connected to the slider and the second wedge block respectively. A guide groove is provided between the sliding groove and the adjustment groove. A cylindrical guide block is provided in the middle of the connecting rod to cooperate with the guide groove. The guide rail seat has an installation port communicating with the adjustment groove on the side wall outside the second wedge block. A baffle is provided at the installation port. The baffle is connected to the guide rail seat by screws. The elastic reset member is disposed between the second wedge block and the baffle.

5. The broaching tool structure with complementary irregular cutting edges as described in claim 1, characterized in that: Several rollers abut between the inclined surfaces of the first wedge block and the second wedge block.

6. A broaching tool structure with complementary irregular cutting edges as described in any one of claims 1-5, characterized in that: The precision adjustment components are provided in two sets. The guide rail seat of the first set of precision adjustment components is fixedly connected to the slide of the second set of precision adjustment components, and the two sets of precision adjustment components are vertically staggered.

7. The broaching tool structure with complementary irregular cutting edges as described in claim 1, characterized in that: Two broaching blades are arranged side by side. The edges of the broaching blades are evenly distributed with multiple serrated teeth, and the teeth of the two broaching blades are staggered. Blade support plates are provided between the tool holder and the broaching blades, as well as between the two broaching blades.

8. A broaching tool structure with complementary irregular cutting edges as described in claim 7, characterized in that: During broaching, the tool holder is connected to the machine tool spindle, and the tube is fixed on the rotary table of the CNC machine tool. The profile of the broaching insert is designed according to the cross-sectional shape of the inner hole of the tube. The inner hole of the tube is rectangular, and the two right-angled sides of the broaching insert are evenly distributed with cutting teeth. The cross-section of the tube is divided into four symmetrical cutting areas according to two mutually perpendicular center lines. The broaching insert completes the inner hole machining of the tube in four cuts. The effective length of the right-angled side of each cutting area is half the width of the tube plus a fixed increment.

9. A broaching tool structure with complementary irregular cutting edges as described in claim 8, characterized in that: The tool holder is equipped with two sets of traveling components. Each traveling component includes a U-shaped bracket, a roller shaft, a bearing shaft, a bearing, and wheels. The U-shaped bracket includes two support arms and a connecting arm connecting the two support arms. A bearing is embedded in the middle of the two support arms. The two ends of the bearing shaft are respectively inserted into the inner ring of the bearing. The middle of the bearing shaft is perpendicularly connected to the middle of the roller shaft. Wheels are rotatably mounted at both ends of the roller shaft. The connecting arm of the U-shaped bracket is connected to the tool holder. The U-shaped brackets of the two traveling components are perpendicularly distributed, so that the wheels of the two traveling components respectively fit on two vertical surfaces inside the pipe. The wheel hub is made of steel, and the outer layer of the wheel is made of wear-resistant engineering plastic.

10. A broaching tool structure with complementary irregular cutting edges as described in claim 9, characterized in that: The connecting arm of the U-shaped bracket has a mounting through hole in the middle, and a snap ring shaft is installed in the mounting through hole. The top of the tool holder has an L-shaped plate, which is composed of two mutually perpendicular fixing plates. The bottom of the two fixing plates is fixed to the tool holder. The snap ring shafts of the two U-shaped brackets are respectively fixed to the two fixing plates by screws. A compression spring is sleeved on the snap ring shaft, and the compression spring is located between the connecting arm and the fixing plate.

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