Processing method of inlayed equal-rake-angle self-locking drill bit

Abstract

The application discloses a processing method of an inlaid equal-rake-angle self-locking drill bit, S1, integrated parameterized processing of a blade; S2, precise processing of the adaptability of a cutter body; S3, double-limiting parameter linkage hot mounting and press mounting; and S4, non-damage type laser welding reinforcement, beneficial effects of the application are that through integrated synchronous processing of the locking teeth, wedge angle self-locking structure and equal-rake-angle chip breaking grooves in the same clamping station, the reference deviation and shape tolerance accumulation caused by multiple clamping and processing in sequence are avoided, the consistency of the shape accuracy of the radial positioning structure, axial self-locking structure and cutting structure of the blade is ensured, meanwhile, through synchronous forming of the double-side bevels of the equal-rake-angle chip breaking grooves, integrated design of one groove and double functions is realized, the equal-rake-angle chip breaking grooves simultaneously have the dual functions of cutting and chip breaking and self-locking positioning, and the industry inherent cognition that the cutting rake face and the locking matching face are designed to be split and the cutting sharpness and the self-locking anti-loosening effect cannot be considered simultaneously in the prior art is broken.

Description

Technical Field

[0001] This invention relates to a method for machining an insert-type equal rake angle self-locking drill bit. Background Technology

[0002] In the field of modern mechanical manufacturing, hole machining is one of the most widely used key processes in metal cutting. As the requirements for machining accuracy, cutting efficiency and tool reliability in high-end equipment manufacturing continue to increase, traditional solid drill bits can no longer meet the diverse, high-efficiency and low-cost production needs. Insertable drill bits, with their advantages of replaceable inserts, low maintenance costs and wide adaptability to various working conditions, have gradually become the mainstream tool for precision hole machining.

[0003] However, existing machining processes still have significant limitations. The design and machining of the cutting structure and locking and positioning structure of the insert are disconnected, and the chip flute design lacks quantitative closed-loop control, which easily leads to uneven rake angles and a failure to simultaneously achieve cutting performance and self-locking anti-loosening performance. At the same time, the tolerance matching between the insert and the tool body is poor, and the hot fitting process is prone to tool body deformation and loss of fitting accuracy control. Subsequent reinforcement processes are prone to damaging the cutting edge accuracy, making it difficult to simultaneously ensure the cutting performance, assembly accuracy and structural reliability of the drill bit, and failing to meet the increasingly demanding requirements for high-end precision hole machining. In view of this, the present invention proposes a machining method for an insert-type equal rake angle self-locking drill bit to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide a method for processing an insert-type equal rake angle self-locking drill bit to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for machining an insert-type equal rake angle self-locking drill bit, characterized in that:

[0007] S1. Integrated parametric machining of cutting tools:

[0008] The parametric design of the cutting insert is completed based on the nominal specifications of the target drill bit, and the insert base is machined and formed.

[0009] Under the same clamping position, locking teeth for radial positioning are integrally machined in the circumferential direction of the insert base, and wedge angle self-locking structure for axial anti-loosening is integrally machined in the axial direction of the insert base. At the same time, multiple sets of equal rake angle chip grooves are integrally machined on the insert base along the center symmetrical distribution.

[0010] The equal rake angle chip-breaking groove has two inclined surfaces that are machined simultaneously. One inclined surface is a cutting rake face that is adapted to the drill bit helical groove, and the other inclined surface is a self-locking mating surface that mates with the tool body.

[0011] When machining the equal rake angle chip groove, a fixed-proportion closed-loop design formula is used to ensure that the rake angles of all circumferential cutting edges of the insert are completely equal. Simultaneously, the symmetry and parallelism of the two inclined surfaces of the equal rake angle chip groove meet the preset geometric tolerances. The fixed-proportion closed-loop design formula is as follows:

[0012] ,

[0013] In the formula: C is the nominal circumference of the target drill bit, ln is the radial cutting edge length corresponding to the nth cutting edge, h1 is the rake angle height of the equal rake angle chip flute, l(n-1) is the radial cutting edge length corresponding to the (n-1)th cutting edge, b is the width of the transition cutting edge at the equal rake angle chip flute and the cutting edge, n≥1, and l0 is the half length of the center clearance section of the cutting tool.

[0014] S2, Precision machining with tool body compatibility:

[0015] Based on the actual measured dimensions of the blade processed in step S1, a mounting groove that is perfectly adapted to the blade is machined on the cutting end face of the blade body. The inner wall of the mounting groove is simultaneously machined with a positioning tooth groove that is fully engaged with the locking teeth of the blade and a wedge-angle mating surface that is fully engaged with the wedge-angle self-locking structure of the blade.

[0016] The depth and width of the mounting groove are controlled by the size adaptation formula, so that the mounting groove and the blade form an interference fit with a preset interference amount.

[0017] S3, Dual-limit parameter linkage hot fitting:

[0018] Based on the preset interference in step S2, calculate the target thermal expansion of the tool body, heat the entire tool body to a forging temperature that matches the target thermal expansion, and make the mounting groove generate a thermal expansion that is precisely adapted to the tool pressing.

[0019] Insert the blade into the limiting pressure head fixture that precisely matches the outer diameter of the blade body, and press the blade into the mounting groove of the blade body while it is still hot;

[0020] During the press-fitting process, the inner wall of the limiting pressure head tooling fits against the outer circle of the cutting end of the tool body to form a radial limit, which suppresses the radial expansion deformation of the tool body during the hot pressing process;

[0021] The inner bottom surface of the limiting pressure head tooling is fully fitted with the cutting end face of the tool body to form an axial limit, which precisely controls the axial pressing depth of the blade and ensures that the self-locking mating surface of the blade and the wedge angle mating surface of the mounting groove are fully fitted after pressing, and the locking teeth and the positioning tooth groove are fully engaged.

[0022] After pressing, the assembly is placed in a dust-free environment and allowed to cool naturally to room temperature.

[0023] S4. Non-destructive laser welding reinforcement:

[0024] For the assembly after slow cooling, the welding path is planned based on the boundary of the cutting face of the insert. Laser welding is used to fill the circumferential gap between the insert and the tool body mounting groove. Without damaging the cutting edge and the accuracy of the cutting face, the micro gap is filled and a secondary reinforcement structure is formed to complete the machining of the inlaid equal rake angle self-locking drill bit.

[0025] As an improvement to the above technical solution, in step S1, the number of slots on one side of the equal rake angle chip-breaking groove is determined by a precise slot number design formula, which is:

[0026] ,

[0027] In the formula, N is the number of flutes on one side, and D is the nominal diameter of the target drill bit, in mm;

[0028] The calculated N value is taken as a symmetrical even number to ensure that the chip breaking load and the pressure force are evenly distributed along the circumference of the drill bit center.

[0029] As an improvement to the above technical solution, in step S1, when machining the equal rake angle chip groove, a center clearance section is reserved in the central region of the insert base. The length of the center clearance section is controlled by a dimensional formula as follows: This avoids frictional losses in the zero-cutting-speed region at the center of the drill bit.

[0030] As an improvement to the above technical solution, in step S1, the width b of the transition blade is in the range of 0.1mm to 0.3mm, and the rake angle of the inclined surface of the equal rake angle chip groove is in the axial direction of 2° to 8°.

[0031] As an improvement to the above technical solution, in step S2, the depth of the mounting groove is controlled by a groove depth adaptation formula, which is:

[0032] ,

[0033] In the formula, H is the depth of the mounting groove, H0 is the measured height of the blade, and the value of ΔH ranges from 0.5mm to 1.5mm.

[0034] In step S2, the width of the mounting groove is controlled by a groove width interference design formula, which is:

[0035] ,

[0036] In the formula, B is the width of the mounting groove, B0 is the measured thickness of the blade, and ΔB is the preset interference, with a value range of 0.05mm to 0.20mm.

[0037] As an improvement to the above technical solution, in step S3, the forging temperature of the blade body is determined by calculation using an interference-temperature linkage formula, wherein the interference-temperature linkage formula is:

[0038] ,

[0039] In the formula, T is the forging temperature in °C; Ac3 is the austenitizing critical temperature of the tool body material in °C; ΔB is the preset interference in mm; and K is the temperature compensation coefficient, which is 30~50℃ / 0.1mm.

[0040] As an improvement to the above technical solution, in step S3, the cooling rate of the natural slow cooling in the air is controlled at 50℃ / min~100℃ / min to avoid stress concentration, tool body cracking or blade breakage caused by excessively fast cooling rate.

[0041] As an improvement to the above technical solution, in step S4, the penetration depth of the laser welding is controlled to be 0.5mm~1.2mm, the welding path is set as a continuous closed loop along the circumference of the mating seam, and after welding, the weld is ground to smoothly transition with the outer circle of the cutter body to avoid the weld affecting the chip removal effect of the drill bit.

[0042] As an improvement to the above technical solution, in step S2, a locking thread hole communicating with the mounting groove is machined on the tool body. After step S4 is completed, a locking screw that matches the locking thread hole is installed to form a drill bit with an equal rake angle and replaceable inserts.

[0043] Compared with the prior art, the beneficial effects of the present invention are:

[0044] By integrating and synchronously machining the locking teeth, wedge angle self-locking structure, and equal rake angle chip-breaking groove in the same clamping station, the accumulation of datum deviations and geometric tolerances caused by multiple clamping and sequential machining is avoided, ensuring the consistency of geometric accuracy between the radial positioning structure, axial self-locking structure, and cutting structure of the insert. At the same time, by synchronously forming the double-sided inclined surfaces of the equal rake angle chip-breaking groove, an integrated design with two functions in one groove is achieved, enabling the equal rake angle chip-breaking groove to have the dual functions of cutting chip breaking and self-locking positioning. This breaks the industry's inherent perception that the cutting rake face and locking mating surface are designed separately in the existing technology, making it impossible to take into account both cutting sharpness and self-locking anti-loosening effect.

[0045] By using a fixed-proportion closed-loop design formula, the rake angle of each circumferential cutting edge of the equal rake angle chip flute is precisely controlled proportionally, ensuring that the rake angle of all circumferential cutting edges of the insert is completely consistent. This completely solves the problems of uneven rake angle, poor chip breaking effect, and uneven cutting load distribution caused by the experience-based design of equal rake angle chip flutes in existing technologies. At the same time, the formulaic design precisely ensures the symmetry and parallelism of the double-sided inclined surfaces of the equal rake angle chip flute, which not only ensures the cutting sharpness of the cutting rake face and effectively reduces cutting resistance and cutting heat, but also ensures the full circumferential fitting accuracy of the self-locking mating surface, improves the axial self-locking anti-loosening effect, and achieves a simultaneous improvement in drill bit cutting life and cutting stability.

[0046] By using adaptive machining based on the actual measured dimensions of the blade, the industry pain points of mismatched fit tolerances and uncontrolled interference caused by machining the blade and blade body separately according to theoretical dimensions in the existing technology are overcome. This ensures the precise fit between the blade body mounting groove and the blade, so that the positioning teeth of the mounting groove and the locking teeth of the blade are fully engaged, and the wedge angle mating surface and the self-locking structure of the blade wedge angle are fully fitted. Through the quantitative formula design of groove depth and groove width, the interference range is precisely controlled, which not only ensures the feasibility of interference press fitting, but also avoids the problems of press fitting difficulties and blade body cracking caused by excessive interference, or insufficient bonding strength caused by insufficient interference. This lays a solid foundation for assembly accuracy and structural reliability from the source of processing.

[0047] By using a formula linking interference and temperature, the forging temperature of the tool body is precisely matched with the preset interference, ensuring that the thermal expansion of the mounting groove is fully adapted to the pressing requirements of the tool. This avoids problems such as insufficient thermal expansion and pressing difficulties caused by heating based on experience, or coarse grains and decreased mechanical properties of the tool body caused by excessive heating temperature. At the same time, through the radial and axial dual-limiting design of the limiting pressure head tooling, the radial expansion deformation of the tool body is suppressed throughout the pressing process, and the axial pressing depth of the tool is precisely controlled. This ensures that the self-locking structure of the tool and the mating surface of the tool body are completely fitted after pressing. This completely solves the technical defects of easy deformation of the tool body, loss of pressing accuracy, and failure of the self-locking structure in the existing hot fitting process, and greatly improves the pass rate and assembly consistency of the pressed finished product. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the structure of the present invention;

[0049] Figure 2 This is a schematic diagram of the blade body of the present invention;

[0050] Figure 3 This is a side view of the blade body of the present invention;

[0051] Figure 4 This is a schematic diagram of the mounting groove of the present invention;

[0052] Figure 5 This is a schematic diagram of the blade of the present invention;

[0053] Figure 6 This is a side view of the blade of the present invention;

[0054] Figure 7 This is a schematic diagram showing the connection between the blade body and the blade of the present invention;

[0055] Figure 8 This is a schematic diagram of the limiting pressure head tooling of the present invention.

[0056] In the diagram: 10. Tool body; 11. Mounting groove; 12. Positioning tooth groove; 13. Wedge angle mating surface; 20. Insert; 21. Equal rake angle chip divider; 22. Self-locking mating surface; 23. Cutting edge; 24. Cutting rake face; 25. Wedge angle self-locking structure; 26. Locking tooth; 30. Limiting pressure head fixture. Detailed Implementation

[0057] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] Example:

[0059] like Figure 1-8 As shown in the figure, this embodiment proposes a method for machining an insert-type equal rake angle self-locking drill bit, including the following steps:

[0060] S1. Integrated parametric machining of cutting tools:

[0061] The parametric design of the cutting insert 20 is completed according to the nominal specifications of the target drill bit, and the substrate of the insert 20 is formed by machining.

[0062] In the same clamping position, locking teeth 26 for radial positioning are integrally machined in the circumferential direction of the base of the insert 20, and wedge angle self-locking structure 25 for axial anti-loosening is integrally machined in the axial direction of the base of the insert 20. At the same time, multiple sets of equal rake angle chip grooves 21 are integrally machined on the base of the insert 20 along the center symmetrical distribution.

[0063] The equal rake angle chip groove 21 is formed by simultaneous machining of the two inclined surfaces. One inclined surface is the cutting rake face 24 adapted to the drill bit helical groove, and the other inclined surface is the self-locking mating surface 22 that mates with the tool body 10.

[0064] When machining the equal rake angle chip groove 21, the rake angles of all circumferential cutting edges 23 of the insert 20 are made completely equal by a fixed-proportion closed-loop design formula. Simultaneously, the symmetry and parallelism of the two inclined surfaces of the equal rake angle chip groove 21 are ensured to meet preset geometric tolerances. The fixed-proportion closed-loop design formula is as follows:

[0065] ,

[0066] In the formula: C is the nominal circumference of the target drill bit, ln is the radial cutting edge length corresponding to the nth cutting edge 23, h1 is the rake angle height of the equal rake angle chip flute 21, l(n-1) is the radial cutting edge length corresponding to the (n-1)th cutting edge 23, b is the width of the transition cutting edge at the equal rake angle chip flute 21 and the cutting edge 23, n≥1, and l0 is half the length of the center clearance section of the insert 20.

[0067] S2, Precision machining with tool body compatibility:

[0068] Based on the actual measured dimensions of the blade 20 processed in step S1, a mounting groove 11 that is perfectly adapted to the blade 20 is machined on the cutting end face of the blade body 10. The inner wall of the mounting groove 11 is simultaneously machined with a positioning tooth groove 12 that is fully engaged with the locking tooth 26 of the blade 20 and a wedge angle mating surface 13 that is fully engaged with the wedge angle self-locking structure 25 of the blade 20.

[0069] The depth and width of the mounting groove 11 are controlled by the size adaptation formula, so that the mounting groove 11 and the blade 20 form an interference fit with a preset interference amount.

[0070] S3, Dual-limit parameter linkage hot fitting:

[0071] Based on the preset interference in step S2, calculate the target thermal expansion of the tool body 10, heat the tool body 10 as a whole to the forging temperature matching the target thermal expansion, so that the mounting groove 11 generates a thermal expansion that precisely matches the pressing of the blade 20.

[0072] Insert the blade 20 into the limiting pressure head fixture 30, which is precisely matched with the outer diameter of the blade body 10, and press the blade 20 into the mounting groove 11 of the blade body 10 while it is still hot.

[0073] During the pressing process, the inner wall of the limiting pressure head tooling 30 is fully circumferentially fitted with the outer circle of the cutting end of the tool body 10 to form a radial limit, thereby suppressing the radial expansion deformation of the tool body 10 during the hot pressing process.

[0074] The inner bottom surface of the limiting pressure head fixture 30 is fully fitted with the cutting end face of the cutter body 10 to form an axial limit, which precisely controls the axial pressing depth of the blade 20, ensuring that the self-locking mating surface 22 of the blade 20 and the wedge angle mating surface 13 of the mounting groove 11 are fully fitted after pressing, and the locking tooth 26 and the positioning tooth groove 12 are fully engaged.

[0075] After pressing, the assembly is placed in a dust-free environment and allowed to cool naturally to room temperature.

[0076] S4. Non-destructive laser welding reinforcement:

[0077] For the assembly after slow cooling, the welding path is planned based on the boundary of the cutting face 24 of the insert 20. Laser welding is used to fill the circumferential gap between the insert 20 and the mounting groove 11 of the tool body 10. Without damaging the cutting edge 23 and the accuracy of the cutting face of the insert 20, the micro gap is filled and a secondary reinforcement structure is formed, thus completing the machining of the inlaid equal rake angle self-locking drill bit.

[0078] In this embodiment, by simultaneously machining the locking teeth 26, the wedge angle self-locking structure 25, and the equal rake angle chip-breaking groove 21 at the same clamping station, the accumulation of reference deviations and form and position tolerances caused by multiple clamping and sequential machining is avoided, ensuring the consistency of form and position accuracy of the radial positioning structure, axial self-locking structure, and cutting structure of the insert 20. At the same time, by simultaneously forming the double-sided inclined surfaces of the equal rake angle chip-breaking groove 21, an integrated design with two functions in one groove is realized, so that the equal rake angle chip-breaking groove 21 has the dual functions of cutting chip breaking and self-locking positioning. This breaks the industry's inherent perception that the cutting rake face 24 and the locking mating surface are designed separately and cannot take into account both cutting sharpness and self-locking anti-loosening effect.

[0079] By using a fixed-proportion closed-loop design formula, the rake angle of each circumferential cutting edge 23 of the equal rake angle chip groove 21 is precisely controlled proportionally, ensuring that the rake angle of all circumferential cutting edges 23 of the insert 20 is completely consistent. This completely solves the problems of uneven rake angle of the cutting edge 23, poor chip breaking effect, and uneven distribution of cutting load caused by the experience-based design of the equal rake angle chip groove 21 in the existing technology. At the same time, the formulaic design precisely ensures the symmetry and parallelism of the double-sided inclined surfaces of the equal rake angle chip groove 21, which not only ensures the cutting sharpness of the cutting rake face 24 and effectively reduces cutting resistance and cutting heat, but also ensures the full circumferential fitting accuracy of the self-locking mating surface 22, improves the axial self-locking anti-loosening effect, and achieves a simultaneous improvement in drill bit cutting life and cutting stability.

[0080] By adapting the machining based on the actual measured dimensions of the blade 20, the industry pain points of mismatched fit tolerances and uncontrolled interference caused by machining the blade 20 and the blade body 10 separately according to theoretical dimensions in the existing technology are overcome. This ensures the precise fit between the mounting groove 11 of the blade body 10 and the blade 20, so that the positioning tooth groove 12 of the mounting groove 11 and the locking tooth 26 of the blade 20 are fully engaged, and the wedge angle mating surface 13 and the wedge angle self-locking structure 25 of the blade 20 are fully fitted. Through the quantitative formula design of groove depth and groove width, the interference range is precisely controlled, which not only ensures the feasibility of interference press fitting, but also avoids the problems of press fitting difficulties and cracking of the blade body 10 caused by excessive interference, or insufficient bonding strength caused by insufficient interference. This lays a solid foundation for assembly accuracy and structural reliability from the source of machining.

[0081] By using an interference fit and temperature linkage formula, the forging temperature of the tool body 10 is precisely matched with the preset interference fit, ensuring that the thermal expansion of the mounting groove 11 is fully adapted to the pressing requirements of the blade 20. This avoids problems such as insufficient thermal expansion and pressing difficulties caused by heating based on experience, or coarse grains and decreased mechanical properties of the tool body 10 caused by excessive heating temperature. At the same time, through the radial and axial dual limiting design of the limiting pressure head tooling 30, the radial expansion deformation of the tool body 10 is suppressed throughout the pressing process, and the axial pressing depth of the blade 20 is precisely controlled. This ensures that the self-locking structure of the blade 20 and the mating surface of the tool body 10 are completely fitted after pressing. This completely solves the technical defects of the tool body 10 being prone to deformation, loss of pressing accuracy, and failure of the self-locking structure in the existing hot fitting process, and greatly improves the pass rate and assembly consistency of the pressed finished product.

[0082] The wedge-angle self-locking structure 25, the self-locking positioning mating surface 22, and the locking teeth 26, which are integrally formed by the same clamping station, have a high degree of consistency in shape and position. During the entire process of inserting the blade 20 into the mounting groove 11 of the blade body 10, the locking teeth 26 and the positioning tooth groove 12 first mesh to form circumferential and radial pre-positioning. Simultaneously, the inclined surface of the wedge-angle self-locking structure 25 and the wedge-angle mating surface 13 of the blade body 10 form a progressive fitting guide, forming a stable pre-locking effect during the pressing stroke. This completely avoids circumferential deflection, radial wobble, and axial tilting of the blade 20 during the inserting process, and fundamentally solves the industry pain points of easy misalignment of the blade 20 during the inserting process and the inability of the self-locking structure to fully fit after assembly.

[0083] Specifically, in step S1, the number of slots on one side of the equal rake angle chip-breaking groove 21 is determined by a precise slot number design formula, which is:

[0084] ,

[0085] In the formula, N is the number of flutes on one side, and D is the nominal diameter of the target drill bit, in mm;

[0086] The calculated N value is taken as a symmetrical even number to ensure that the chip breaking load and the pressure force are evenly distributed along the circumference of the drill bit center.

[0087] In this embodiment, by establishing a quantitative correspondence between the number of grooves N on one side of the equal rake angle chip-breaking groove 21 and the nominal diameter D of the target drill bit, the number of grooves of the equal rake angle chip-breaking groove 21 is precisely matched with the diameter of the drill bit. This eliminates the high dependence of the existing technology on manual experience in groove design and realizes the standardized and reproducible design of the number of grooves of the equal rake angle chip-breaking groove 21 for different specifications of drill bits. While ensuring that the equal rake angle chip-breaking groove 21 effectively breaks chips and reduces cutting resistance and chip removal load, it also reasonably controls the load-bearing cross-sectional size of a single cutting edge 23, ensuring the structural strength and impact resistance of the cutting edge 23. This avoids common industry problems such as the chipping of the cutting edge 23 due to too many grooves and the poor chip removal due to too few grooves from the design source.

[0088] Meanwhile, by using the design rule of taking a symmetrical even number of grooves obtained from the calculation, the equal rake angle chip-breaking grooves 21 are symmetrically and evenly distributed around the circumference of the drill bit's rotation center. This ensures that the chip-breaking cutting load during the drill bit's cutting process and the pressing force during the pressing process of the insert 20 are evenly distributed around the drill bit's center circumference. This effectively suppresses circumferential vibration during the cutting process, improves the drill bit's cutting stability and the shape and position accuracy of the machined hole, and ensures that the circumferential force of the insert 20 is balanced during the pressing process, avoiding the insert 20 from being misaligned during pressing. It also ensures that the insert 20's locking teeth 26 are fully engaged with the tool body 10's positioning tooth groove 12, and that the wedge angle self-locking structure 25 is fully circumferentially fitted with the tool body 10's mating surface. This further improves the pressing and assembly accuracy of the insert 20 and the reliability of its axial self-locking and anti-loosening mechanism.

[0089] Specifically, in step S1, when machining the equal rake angle chip groove 21, a center clearance section is reserved in the central region of the substrate of the insert 20. The length of the center clearance section is controlled by a dimensional formula as follows: This avoids frictional losses in the zero-cutting-speed region at the center of the drill bit.

[0090] In this embodiment, by precisely limiting the length range of the central avoidance section, ineffective cutting in the zero-cutting-speed and low-cutting-speed region near the central axis during drill rotation is effectively avoided. This avoids the squeezing friction between the ineffective cutting edge and the workpiece in this region, significantly reducing the overall cutting resistance and cutting heat output of the drill bit, reducing the abrasive wear and thermal fatigue wear of the cutting edge 23, and greatly extending the effective service life of the drill bit. At the same time, it avoids the problems of chipping at the entrance of the machined hole and excessive inner wall roughness caused by squeezing friction in the central region, and improves the dimensional accuracy and surface forming quality of hole machining.

[0091] Specifically, in step S1, the width b of the transition cutting edge is in the range of 0.1mm to 0.3mm, and the rake angle of the inclined surface of the equal rake angle chip groove 21 is in the range of 2° to 8° in the axial direction.

[0092] In this embodiment, by precisely limiting the width b of the transition cutting edge to the range of 0.1mm to 0.3mm, while ensuring the cutting sharpness of the cutting edge 23, the structural strength and impact resistance of the circumferential cutting edges 23 of the equal rake angle chip groove 21 are effectively enhanced. This avoids common industry problems caused by the insufficient rigidity of the cutting edge 23 and the easy occurrence of chipping and breakage during high-load cutting due to the excessive width of the cutting edge 23. At the same time, it avoids the defects caused by the excessive width of the cutting edge 23, such as increased friction area between the cutting edge 23 and the workpiece machining surface, significant increase in cutting resistance and cutting heat, aggravated thermal wear of the cutting edge 23, and excessive roughness of the machined hole wall.

[0093] By precisely limiting the axial rake angle of the inclined surface of the equal rake angle chip groove 21 to the range of 2° to 8°, the "cutting chip separation function" and "self-locking positioning function" of the equal rake angle chip groove 21 are synergistically adapted. This breaks the inherent perception that the cutting rake angle design and the self-locking structure design are mutually exclusive in the prior art. This rake angle range provides a suitable cutting sharpness for the cutting rake face 24 on one side of the drill bit helical groove corresponding to the equal rake angle chip groove 21, effectively reducing the shear deformation resistance during the cutting process, realizing smooth chip separation and chip removal, and avoiding the technical problems of excessive cutting resistance and cutting vibration caused by an excessively small rake angle, as well as the technical problems of reduced strength and easy breakage of the cutting edge 23 caused by an excessively large rake angle.

[0094] Specifically, in step S2, the depth of the mounting groove 11 is controlled by a groove depth adaptation formula, which is:

[0095] ,

[0096] In the formula, H is the depth of the mounting groove 11, H0 is the measured height of the blade 20, and the value of ΔH ranges from 0.5mm to 1.5mm.

[0097] In step S2, the width of the mounting groove 11 is controlled by a groove width interference design formula, which is:

[0098] ,

[0099] In the formula, B is the width of the mounting groove 11, B0 is the measured thickness of the blade 20, and ΔB is the preset interference, with a value range of 0.05mm to 0.20mm.

[0100] In this embodiment, the groove depth of the mounting groove 11 is precisely quantitatively designed using a groove depth adaptation formula. The actual measured height of the cutting insert 20 after machining is used as the design benchmark. This overcomes the industry pain point of poor groove depth compatibility and severe tolerance accumulation caused by machining the mounting groove 11 with theoretical nominal dimensions. Combined with precise control of ΔH values ​​from 0.5mm to 1.5mm, this ensures that the cutting end of the cutting insert 20 has an effective protrusion to meet cutting requirements. It also ensures that the cutting face 24 of the cutting insert 20 can precisely adapt to the drill bit's helical groove to form a complete cutting edge structure, avoiding insufficient protrusion of the cutting insert 20 and damage to the cutting body 1 due to excessive groove depth. The design eliminates the defects of 0-end face interference cutting operations and inability to form effective cutting; on the other hand, it ensures that the mounting groove 11 of the tool body 10 can form a stable cover of the insert 20 with sufficient support height in the full circumference, avoiding the problems of insufficient support height of the insert 20 due to insufficient groove depth, and the insert 20 being subjected to force sway and stress concentration and cracking during press assembly and high-load cutting. At the same time, it ensures that the axial wedge angle self-locking structure 25 and the circumferential locking teeth 26 of the insert 20 can be fully embedded in the mounting groove 11, forming an effective fit and meshing of the full length with the corresponding matching structure of the tool body 10. From the root of the size design, it ensures the stable realization of the radial positioning accuracy and axial self-locking anti-loosening performance of the insert 20.

[0101] By precisely quantifying and controlling the width of the mounting groove 11 using the groove width interference design formula, and setting the preset interference based on the actual measured thickness of the cutter 20 after machining, precise closed-loop control of the interference fit between the cutter 20 and the mounting groove 11 is achieved. This completely solves the problem of interference loss control caused by the lack of quantitative standards and reliance on experience in the existing technology for interference design. By precisely limiting the preset interference ΔB to the range of 0.05mm to 0.20mm, the lower limit of 0.05mm ensures that a stable and effective interference fit can be formed between the cutter 20 and the mounting groove 11. This avoids defects such as insufficient bonding strength between the cutter 20 and the tool body 10, radial movement of the cutter 20 during cutting, circumferential wobble, and fretting wear of the mating surface caused by insufficient interference. The upper limit of 0.20mm avoids common industry problems such as difficulties in hot fitting and pressing operations caused by excessive interference, irreversible radial expansion deformation of the tool body 10 during hot pressing, and even cracking of the tool body 10 and breakage of the cutter 20.

[0102] Specifically, in step S3, the forging temperature of the blade body 10 is determined by calculation using an interference fit and a temperature linkage formula. The interference fit-temperature linkage formula is as follows:

[0103] ,

[0104] In the formula, T is the forging temperature in °C; Ac3 is the austenitizing critical temperature of the tool body material 10 in °C; ΔB is the preset interference in mm; and K is the temperature compensation coefficient, which is 30~50℃ / 0.1mm.

[0105] Specifically, in step S3, the cooling rate of the natural slow cooling in the air is controlled at 50℃ / min~100℃ / min to avoid stress concentration, cracking of the tool body 10 or breakage of the blade 20 caused by excessively fast cooling rate.

[0106] In this embodiment, by precisely quantifying and controlling the cooling rate of the air-to-air natural slow cooling process of the assembly after hot fitting and pressing, the cooling rate is stably controlled within the optimal range of 50℃ / min to 100℃ / min. This addresses the core technical defects of existing hot-fitting and cooling processes for embedded drill bits, such as the lack of standardized quantitative control, unreasonable cooling rates leading to stress concentration within the assembly, cracking of the tool body 10, breakage of the carbide insert 20, loss of interference fit accuracy, and failure of the positioning and locking structure. It achieves significant technical effects through deep synergy with the entire closed-loop machining process.

[0107] Specifically, in step S4, the laser welding penetration depth is controlled to be 0.5mm~1.2mm, the welding path is set as a continuous closed loop along the circumference of the mating seam, and after welding, the weld is ground to smoothly transition with the outer circle of the tool body 10 to avoid the weld affecting the chip removal effect of the drill bit.

[0108] Specifically, in step S2, a locking thread hole communicating with the mounting groove 11 is machined on the tool body 10. After step S4 is completed, a locking screw that matches the locking thread hole is installed to form a type 20 drill bit with an equal rake angle replaceable insert.

[0109] In this embodiment, a locking threaded hole is provided on the surface of the blade body 10 and matches the position of the mounting groove 11. The locking threaded hole extends through the mounting groove 11, and then a locking screw is installed in the locking threaded hole. The locking screw contacts the blade 20 for reinforcement.

[0110] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for machining an insert-type equal rake angle self-locking drill bit, characterized in that: Includes the following steps: S1. Integrated parametric machining of cutting tools: The parametric design of the cutting insert (20) is completed according to the nominal specifications of the target drill bit, and the substrate of the insert (20) is formed by machining. Under the same clamping position, locking teeth (26) for radial positioning are integrally machined in the circumferential direction of the base of the insert (20), and wedge angle self-locking structure (25) for axial anti-loosening is integrally machined in the axial direction of the base of the insert (20). At the same time, multiple sets of equal rake angle chip grooves (21) distributed symmetrically along the center are integrally machined on the base of the insert (20). The equal rake angle chip groove (21) is formed by simultaneous machining of the two inclined surfaces. One inclined surface is the cutting rake face (24) adapted to the drill bit spiral groove, and the other inclined surface is the self-locking mating surface (22) that mates with the tool body (10). When machining the equal rake angle chip groove (21), the rake angles of all circumferential cutting edges (23) of the insert (20) are made completely equal by a fixed-proportion closed-loop design formula. At the same time, the symmetry and parallelism of the two inclined surfaces of the equal rake angle chip groove (21) are ensured to meet the preset form and position tolerances. The fixed-proportion closed-loop design formula is as follows: ， In the formula: C is the nominal circumference of the target drill bit, ln is the radial cutting edge length corresponding to the nth cutting edge (23), h1 is the rake angle height of the equal rake angle chip flute (21), l(n-1) is the radial cutting edge length corresponding to the n-1th cutting edge (23), b is the width of the transition cutting edge at the equal rake angle chip flute (21) and the cutting edge (23), n≥1, l0 is half the length of the center clearance section of the insert (20); S2, Precision machining with tool body compatibility: Based on the actual dimensions of the blade (20) processed in step S1, a mounting groove (11) that is fully adapted to the blade (20) is machined on the cutting end face of the blade body (10). The inner wall of the mounting groove (11) is simultaneously machined with a positioning tooth groove (12) that is fully engaged with the locking tooth (26) of the blade (20) and a wedge angle mating surface (13) that is fully engaged with the wedge angle self-locking structure (25) of the blade (20). The depth and width of the mounting groove (11) are controlled by the size adaptation formula so that the mounting groove (11) and the blade (20) form an interference fit with a preset interference amount; S3, Dual-limit parameter linkage hot fitting: According to the preset interference in step S2, calculate the target thermal expansion of the tool body (10), heat the tool body (10) as a whole to the forging temperature matching the target thermal expansion, so that the mounting groove (11) generates a thermal expansion that is precisely adapted to the pressing of the blade (20). Insert the blade (20) into the limiting pressure head fixture (30) that precisely matches the outer diameter of the blade body (10), and press the blade (20) into the mounting groove (11) of the blade body (10) while it is still hot; During the pressing process, the inner wall of the limiting pressure head fixture (30) is fully circumferentially fitted with the outer circle of the cutting end of the tool body (10) to form a radial limit, thereby suppressing the radial expansion deformation of the tool body (10) during the hot pressing process; The inner bottom surface of the limiting pressure head fixture (30) is fully fitted with the cutting end face of the cutter body (10) to form an axial limit, which precisely controls the axial pressing depth of the blade (20), ensuring that the self-locking mating surface (22) of the blade (20) and the wedge angle mating surface (13) of the mounting groove (11) are fully fitted after pressing, and the locking teeth (26) and the positioning tooth groove (12) are fully engaged. After pressing, the assembly is placed in a dust-free environment and allowed to cool naturally to room temperature. S4. Non-destructive laser welding reinforcement: For the assembly after slow cooling, the welding path is planned based on the boundary of the cutting face (24) of the insert (20). The laser welding process is used to fill the circumferential gap between the insert (20) and the mounting groove (11) of the tool body (10). Without damaging the cutting edge (23) of the insert (20) and the accuracy of the cutting face, the micro gap is filled and a secondary reinforcement structure is formed to complete the processing of the inlaid equal rake angle self-locking drill bit.

2. The machining method of an insert-type equal rake angle self-locking drill bit according to claim 1, characterized in that: In step S1, the number of slots on one side of the equal rake angle chip-breaking groove (21) is determined by the precise design formula for the number of slots, which is: ， In the formula, N is the number of flutes on one side, and D is the nominal diameter of the target drill bit, in mm; The calculated N value is taken as a symmetrical even number to ensure that the chip breaking load and the pressure force are evenly distributed along the circumference of the drill bit center.

3. The machining method of an insert-type equal rake angle self-locking drill bit according to claim 1, characterized in that: In step S1, when machining the equal rake angle chip groove (21), a center clearance section is reserved in the central area of ​​the base of the insert (20). The length of the center clearance section is controlled by a dimensional formula as follows: This avoids frictional losses in the zero-cutting-speed region at the center of the drill bit.

4. The machining method of an insert-type equal rake angle self-locking drill bit according to claim 1, characterized in that: In step S1, the width b of the transition blade is in the range of 0.1mm to 0.3mm, and the rake angle of the inclined surface of the equal rake angle chip groove (21) is 2° to 8° in the axial direction.

5. The machining method of an insert-type equal rake angle self-locking drill bit according to claim 1, characterized in that: In step S2, the depth of the mounting groove (11) is controlled by a groove depth adaptation formula, which is: ， In the formula, H is the groove depth of the mounting groove (11), H0 is the measured height of the blade (20), and the value range of ΔH is 0.5mm~1.5mm; In step S2, the width of the mounting groove (11) is controlled by the groove width interference design formula, which is: ， In the formula, B is the width of the mounting groove (11), B0 is the actual thickness of the blade (20), and ΔB is the preset interference, with a value range of 0.05mm~0.20mm.

6. The machining method of an insert-type equal rake angle self-locking drill bit according to claim 1, characterized in that: In step S3, the forging temperature of the blade body (10) is determined by calculation using an interference-temperature linkage formula, wherein the interference-temperature linkage formula is: ， In the formula, T is the forging temperature, in °C; Ac3 is the austenitizing critical temperature of the material of the tool body (10), in °C; ΔB is the preset interference, in mm; K is the temperature compensation coefficient, with a value of 30~50℃ / 0.1mm.

7. The machining method of an insert-type equal rake angle self-locking drill bit according to claim 1, characterized in that: In step S3, the cooling rate of the natural slow cooling in the air is controlled at 50℃ / min~100℃ / min to avoid stress concentration in the assembly body, cracking of the blade (10) or breakage of the blade (20) caused by excessively fast cooling rate.

8. The machining method of an insert-type equal rake angle self-locking drill bit according to claim 1, characterized in that: In step S4, the laser welding penetration depth is controlled to be 0.5mm~1.2mm, the welding path is set in a continuous closed loop along the circumference of the mating gap, and after welding, the weld is ground to smoothly transition with the outer circle of the cutter body (10) to avoid the weld affecting the chip removal effect of the drill bit.

9. The method for machining an insert-type equal rake angle self-locking drill bit according to claim 1, characterized in that: In step S2, a locking thread hole communicating with the mounting groove (11) is machined on the cutter body (10). After step S4 is completed, a locking screw that matches the locking thread hole is installed to form a drill bit with an equal rake angle replaceable insert (20).

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