A fixed shank drill bit with a rotating internal cooling channel and a production process thereof

Abstract

The present application belongs to the technical field of metal cutting, and specifically relates to a fixed-shank drill bit with a spiral internal cooling channel and a production process thereof, which comprises an internal cooling channel extending spirally along an axis, a tangential velocity component is generated by utilizing the guiding effect of the spiral channel wall surface, the cooling liquid forms a liquid flow inclined in the rotation direction, and self-adaptive following injection to the rotary cutting area is realized; a four-axis or more numerical control machining center is adopted to form the drill bit body and the spiral internal cooling channel; the drill bit comprises a hard alloy drill bit body, a spiral internal cooling channel, a drill tip cooling outlet, a neck transition section and a steel fixed shank; the present application realizes accurate tracking cooling by superimposing the pre-swirl velocity and the rotation velocity vector generated by the spiral channel, disperses stress concentration by the neck variable-diameter conical surface structure and stress release grooves, eliminates flow field distortion and flashing by the gradually changing cross-sectional area design, significantly improves the cooling efficiency and the tool life, and guarantees the drilling quality and the reliability of the fixed-shank connection.

Description

Technical Field

[0001] This invention belongs to the field of metal cutting technology, specifically a fixed shank drill bit with a rotating internal cooling channel and its manufacturing process. Background Technology

[0002] Internally cooled fixed-shank drills rely on an internal coolant circulation structure to achieve efficient heat dissipation in the cutting zone. With their advantages of high clamping accuracy and good structural rigidity, they are widely used in precision drilling of various difficult-to-machine materials. Their cooling performance, structural strength, and connection reliability directly determine the drilling quality and tool life.

[0003] Existing internally cooled fixed-shank drill bits are designed with internal cooling channel structures based solely on static fluid requirements, passively balancing the matching relationship between the cross-sectional area of ​​the cooling channel and the strength of the drill bit structure. Furthermore, they only assess the connection strength of the fixed shank under static conditions, which is sufficient to complete basic drilling operations under normal working conditions.

[0004] Existing drill bit designs do not consider the coupling effects of fluid-solid-thermal multi-physics fields during the drilling process, which can easily lead to problems such as coolant deviation, heat accumulation in the cutting zone, and cavitation damage in the channel. They cannot balance cooling efficiency and structural strength. At the same time, they ignore the cumulative damage caused by thermal-mechanical coupling under high-temperature conditions, which can easily lead to fretting wear and fatigue failure, affecting and reducing drilling accuracy and tool reliability.

[0005] Therefore, the present invention provides a fixed shank drill bit with a rotating internal cooling channel and its manufacturing process. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0007] The technical solution adopted by this invention to solve its technical problem is: the manufacturing process of a fixed shank drill bit with a rotating internal cooling channel, as described in this invention, includes the following steps: S1. Design a drill bit body with a spiral internal cooling channel structure. The internal cooling channel is arranged along the axis of the drill bit body and extends in a spiral twisted shape. The tangential velocity component is generated by the guiding effect of the spiral channel wall on the coolant. The coolant forms a liquid flow inclined along the rotation direction of the drill bit at the injection outlet, so as to achieve the adaptive following spray effect of the coolant on the rotating cutting area. S2. Perform CNC machining of the drill bit body. Use a four-axis or higher CNC machining center to grind the drill tip, machine the spiral groove, machine the spiral internal cooling channel, and finish the fixed shank connection section of the cemented carbide drill bit blank to ensure that the spiral angle, pitch and channel cross-sectional dimensions of the spiral internal cooling channel meet the design accuracy requirements. S3. Perform an interference fit assembly between the fixed shank and the drill body. The steel fixed shank and the carbide drill body are connected by an interference fit using a hot fitting method. The interference amount is controlled to be three to five per thousand of the drill body diameter to ensure the stability of the preload at the connection interface under high temperature conditions. S4. Perform overall fine grinding and coating treatment on the drill bit. Use a centerless grinder to fine grind the drill bit neck and working part, and then perform physical vapor deposition coating treatment. The coating thickness is controlled in the range of two to four micrometers. S5. Conduct drill bit performance testing and quality inspection. Test the internal cooling channel flow rate, channel pressure bearing capacity and jet atomization effect of the drill bit through a high-pressure coolant circulation test bench, and screen qualified products that meet the design specifications.

[0008] In step S1, the drill bit body with a spiral internal cooling channel includes a cemented carbide drill bit body, a spiral internal cooling channel, a drill tip cooling outlet, and a neck transition section. The cemented carbide drill bit body is made of YG8 grade tungsten carbide. The drill bit body is composed of a drill tip section, a spiral groove section, a neck transition section, and a fixed shank connection section connected in sequence. The spiral internal cooling channel is arranged along the axis of the drill bit body and extends from the tail of the drill bit body to the drill tip section in a spiral twisted shape. The spiral angle of the channel is set to 15 to 30 degrees, and the pitch is set to 0.5 to 1.2 times the drill bit diameter. The channel cross-section adopts an Archimedean spiral profile. The cross-sectional area of ​​the channel gradually decreases from the tail to the drill tip along the axis of the drill bit body. The cross-sectional area of ​​the channel at the tail is 15% to 25% of the cross-sectional area of ​​the drill bit body, and the cross-sectional area of ​​the channel at the drill tip section is 8% to 12% of the cross-sectional area of ​​the drill bit body.

[0009] In step S1, the structural design of the spiral internal cooling channel utilizes the guiding effect of the spiral channel wall on the coolant to generate a tangential velocity component. When the coolant flows in the channel, the normal reaction force applied to the coolant by the spiral channel wall is decomposed into an axial component and a tangential component. The tangential component drives the coolant to generate a pre-rotation velocity along the direction of drill bit rotation. The vector superposition of the pre-rotation velocity and the drill bit rotation velocity causes the coolant to form an inclined liquid flow along the direction of drill bit rotation at the injection outlet. This inclined liquid flow has a backward pointing injection angle relative to the drill bit surface. The injection angle is positively correlated with the spiral angle and the drill bit rotation speed. When the drill bit rotates at the rated speed, the injection angle reaches the range of 30 to 60 degrees, realizing the adaptive following injection effect of the coolant on the rotating cutting area.

[0010] Preferably, in step S1, the spiral internal cooling channel has a main channel inlet at the tail of the drill bit body. The main channel inlet is connected to the external coolant supply pipeline by a conical sealing connection. An O-ring groove is provided at the connection point. The groove depth is set to 2.5 to 3 mm, the groove width is set to 2 to 2.5 mm, and the inner diameter of the main channel inlet is set to 6 to 10 mm.

[0011] Preferably, in step S1, the spiral internal cooling channel is provided with a branch channel structure inside the drill bit body. The branch channel extends from the main channel along the spiral line to the outer periphery. At least two branch points are provided and evenly distributed along the spiral line. The end of the branch channel leads to the drill tip cooling outlet. The cross-sectional area of ​​each branch channel is 40% to 60% of the cross-sectional area of ​​the main channel. The connection between the branch channel and the main channel adopts an arc transition structure with an arc radius that is two to three times the channel width.

[0012] Preferably, in step S1, the drill tip cooling outlet is configured as two or more spray holes evenly distributed along the circumference of the drill tip. The diameter of each spray hole is set to 1 to 1.5 mm, the angle between the center line of the spray hole and the drill bit axis is set to 20 to 35 degrees, the spray direction of each spray hole is directed towards the back face area of ​​the main cutting edge of the drill tip, and a micro-shaped flared mouth structure is provided at the outlet of the spray hole, with the large end of the flared mouth facing the cutting area of ​​the drill tip.

[0013] Preferably, in step S1, the neck transition section adopts a variable diameter conical surface structure to connect the working part of the drill bit body and the fixed shank connection part. The angle between the generatrix of the conical surface and the drill bit axis is set to 10 to 15 degrees. A stress relief groove is set at the minimum diameter position of the neck transition section. The groove width is set to 0.5 to 1 mm, the groove depth is set to 0.3 to 0.6 mm, and the bottom fillet radius is set to 0.2 to 0.4 mm.

[0014] In step S2, a four-axis or higher CNC machining center is used to perform CNC machining of the drill body. The spindle speed of the CNC machining center is set to 3,000 to 15,000 revolutions per minute, and the tool feed rate is set to 50 to 500 millimeters per minute. During the CNC machining process, oil mist cooling is used to cool the contact area between the tool and the workpiece.

[0015] In step S2, the spiral internal cooling channel is machined by CNC milling using a spiral milling cutter. The diameter of the spiral milling cutter is selected according to the channel design dimensions. The milling depth is completed in two to four passes according to the channel cross-section requirements. The cutting depth of each pass decreases sequentially. The cutting depth of the last pass is controlled to be 0.1 to 0.2 mm to ensure the channel surface quality. After milling, the inner surface of the channel is finished by electrolytic polishing. The roughness of the inner surface of the channel is controlled to be 0.4 to 0.8 micrometers.

[0016] Preferably, in step S2, the drill tip grinding is performed using a five-axis CNC grinding machine. During the grinding process, the geometric parameters of the drill tip angle, the main cutting edge clearance angle, the secondary cutting edge clearance angle, and the chisel edge angle are monitored in real time by an online measurement system to ensure that the error of each parameter is controlled within ±0.5 degrees. After grinding, a diamond grinding wheel is used for finishing, and the grinding amount is controlled to be 0.05 to 0.1 millimeters.

[0017] Preferably, in step S2, the spiral groove is machined using a form milling cutter for CNC milling. The cutting edge profile of the form milling cutter is customized according to the spiral groove design profile. During the milling process, the cutting parameters are controlled to avoid the generation of burrs and vibration marks. The angle between the rake face of the spiral groove and the drill axis is set to eight to twelve degrees, and the depth of the spiral groove is set to ten percent to fifteen percent of the drill diameter.

[0018] Preferably, in step S2, the dimensional accuracy of the fixed shank connecting section is controlled to IT6 level, the surface roughness is controlled to 0.8 to 1.6 micrometers, and the coaxiality of the outer circle and inner hole of the fixed shank connecting section is controlled within the range of 0.02 to 0.03 millimeters.

[0019] In step S3, the interference fit between the fixed shank and the drill body is assembled using a heat fitting method. Before assembly, the fixed shank connection hole of the carbide drill body is ultrasonically cleaned and its actual size is measured. The actual interference is calculated based on the measured size and the outer diameter of the steel fixed shank. The interference is controlled to be three to five per thousand of the drill body diameter. During assembly, the steel fixed shank is heated to three to four hundred degrees Celsius and then quickly inserted into the fixed shank connection hole of the carbide drill body. After cooling, an interference fit connection is formed.

[0020] Preferably, in step S3, the steel fixed shank is rapidly heated by induction heating during the hot fitting assembly process. The power of the induction heating power supply is set to 15 to 25 kilowatts, the heating temperature is monitored in real time by an infrared thermometer, and the heating time is controlled to be 30 to 60 seconds. After heating is completed, the fixed shank and the drill bit body are fitted together within 5 seconds. During the fitting process, the coaxiality deviation between the fixed shank and the drill bit body axis is kept less than 0.02 millimeters.

[0021] Preferably, in step S3, the microscopic bonding quality of the interference fit interface is verified by an interface bonding strength test. The criterion for bonding strength is that the interface shear strength is not less than 300 MPa. During the test, ultrasonic non-destructive testing is used to screen for defects in the interface. When the screening results show no defects such as interface debonding, delamination, or cracks, it is considered qualified.

[0022] Preferably, in step S3, the fixed shank connection area is provided with a stress relief structure. The stress relief structure includes a transition fillet at the end of the fixed shank, a micro-threaded groove at the connection interface, and a conical weight-reducing structure in the inner cavity of the fixed shank. The radius of the transition fillet is set to 0.1 to 0.15 times the diameter of the drill bit body, the pitch of the micro-threaded groove is set to 0.5 to 1 mm, the groove depth is set to 0.1 to 0.2 mm, and the cone angle of the conical weight-reducing structure is set to 60 to 90 degrees.

[0023] In step S4, the overall fine grinding of the drill bit is carried out using a centerless grinder. During the grinding process, a CBN grinding wheel is used for external cylindrical grinding. The grinding wheel speed is set to 3,000 to 4,500 revolutions per minute, the workpiece feed speed is set to 0.5 to 2 meters per minute, and the grinding allowance is controlled to be 0.1 to 0.2 millimeters. After fine grinding, the outer roundness of the working part of the drill bit is controlled within the range of 0.001 to 0.003 millimeters.

[0024] In step S4, the physical vapor deposition coating treatment is carried out using a vacuum arc ion plating equipment. The coating material is selected as either nitrogen aluminum titanium coating or nitrogen chromium aluminum coating. The coating thickness is set to the range of two to four micrometers by precise control of the coating time. The coating hardness is controlled to be 1,800 to 2,500 Vickers hardness. The adhesion between the coating and the substrate is tested by a scratch test, and the critical load is not less than 60 Newtons.

[0025] Preferably, in step S4, the drill bit surface is subjected to plasma cleaning treatment before coating treatment. The plasma cleaning gas is a mixture of argon and hydrogen, with a mixing ratio of 70% to 80% argon and 20% to 30% hydrogen. The cleaning power is set to 500 to 800 watts, and the cleaning time is set to 10 to 20 minutes.

[0026] Preferably, in step S4, after the coating treatment is completed, the drill bit is subjected to post-treatment heat treatment. The heat treatment temperature is controlled in the range of 150 to 180 degrees Celsius, the holding time is set to two to three hours, and the drill bit is cooled to room temperature with the furnace after heat treatment to eliminate the internal stress of the coating.

[0027] In step S5, the drill bit performance test is conducted using a high-pressure coolant circulation test bench. The maximum supply pressure of the test bench is set to 15 to 20 MPa, and the flow rate is adjusted from 0.5 to 5 liters per minute. During the test, the actual flow rate of the internal cooling channel is monitored in real time by a flow sensor, and the pressure-bearing capacity of the channel is monitored by a pressure sensor.

[0028] Preferably, in step S5, the coolant spray atomization effect is tested using a high-speed camera system. The frame rate of the high-speed camera system is set to 0.5 milliseconds per frame. The atomization cone angle, atomization uniformity, and droplet size distribution of the sprayed liquid flow are analyzed by image processing algorithms. The qualified standard for the atomization cone angle is 40 to 70 degrees, and the qualified standard for atomization uniformity is that the droplet density variation coefficient within the atomization area is less than or equal to 15%.

[0029] Preferably, in step S5, the service life test of the drill bit is carried out by a drilling test method. The test material is aerospace-grade titanium alloy TC4 plate. The drilling parameters are set as follows: rotation speed of 3,000 to 5,000 revolutions per minute, feed rate of 50 to 100 millimeters per minute, and cutting depth of one to three times the diameter of the drill bit. During the drilling test, coolant with a pressure of 10 MPa is continuously supplied. The criteria for judging the failure of the drill bit are that the wear of the drill tip reaches 0.3 millimeters or the drilling size accuracy exceeds the IT8 grade tolerance.

[0030] Preferably, in step S5, the quality inspection also includes the measurement and inspection of the drill bit's geometric parameters, including the measurement of the drill tip angle, the runout of the main cutting edge, the centering of the chisel edge, and the measurement of the total length of the drill bit and the length of the working part. The measurement of each parameter is performed using a coordinate measuring machine, and the measurement uncertainty is controlled to be 0.001 to 0.003 millimeters.

[0031] The present invention also provides a fixed shank drill bit with a spiral internal cooling channel, comprising a carbide drill bit body, a spiral internal cooling channel, a drill tip cooling outlet, a neck transition section, and a steel fixed shank.

[0032] The carbide drill bit body is composed of a drill tip, a spiral groove, a neck transition, and a fixed shank connection connected in sequence. The drill tip is provided with two or more main cutting edges. The spiral groove is evenly distributed along the circumference of the drill bit body. The neck transition adopts a variable diameter conical surface structure to connect the spiral groove and the fixed shank connection. The tail of the fixed shank connection is interference-fitted with the steel fixed shank.

[0033] The spiral internal cooling channel is arranged along the axis of the drill bit body and extends from the tail of the drill bit body to the drill tip in a spiral twisted shape. The spiral angle of the channel is set to 15 to 30 degrees, and the pitch is set to 0.5 to 1.2 times the drill bit diameter. The channel cross-section is formed by an Archimedean spiral profile, and the cross-sectional area of ​​the channel gradually decreases from the tail to the drill tip along the axis of the drill bit body.

[0034] The drill tip cooling outlet is located in the back face area of ​​the drill tip. The number and position of the spray holes correspond to the main cutting edge. The spray direction of each spray hole points to the back face area of ​​the main cutting edge of the drill tip. A micro-shaped flared mouth structure is provided at the outlet of the spray hole.

[0035] Preferably, the spiral internal cooling channel has a branch channel structure inside the drill bit body. The branch channel extends outward from the main channel along the spiral line, with at least two branch points evenly distributed along the spiral line. The end of the branch channel leads to the drill tip cooling outlet.

[0036] Preferably, the neck transition section adopts a variable diameter conical surface structure to connect the working part of the drill bit body and the fixed shank connection part. The angle between the generatrix of the conical surface and the drill bit axis is set to ten to fifteen degrees, and a stress relief groove is provided at the minimum diameter position of the neck transition section.

[0037] Preferably, the steel shank and the carbide drill body are connected by a hot-fitting interference fit, with the interference amount being three to five per thousand of the drill body diameter, and the connection interface is provided with a fine threaded groove to enhance the bonding force.

[0038] Preferably, the outer surface of the working part of the drill bit body is provided with a physical vapor deposition coating, the coating material being a nitrogen-aluminum-titanium coating or a nitrogen-chromium-aluminum coating, and the coating thickness being set to two to four micrometers.

[0039] The beneficial effects of this invention are as follows: Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention relates to a fixed-shank drill bit with a spiral internal cooling channel and its manufacturing process. By setting an internal cooling channel extending in a spiral twisted shape along the axial direction in the drill bit body, the tangential velocity component is generated by the guiding effect of the spiral channel wall on the coolant. This causes the coolant to form a liquid flow inclined along the rotation direction of the drill bit at the injection outlet, achieving an adaptive following spray effect of the coolant on the rotating cutting area. This solves the geometric mismatch problem of the existing straight channel coolant spray lagging behind the rotating cutting area, allowing the coolant to always act on the cutting area with the highest heat, significantly improving cooling efficiency and extending tool life.

[0040] 2. The present invention relates to a fixed-shank drill bit with a spiral internal cooling channel and its manufacturing process. The spiral internal cooling channel design enables the coolant to generate a pre-swirl velocity within the channel. The vector superposition of this pre-swirl velocity and the drill bit rotation velocity results in a backward-pointing spray angle of the jet fluid relative to the drill bit surface. This tilted spray angle effectively offsets the relative offset of the coolant caused by the drill bit rotation, enabling precise tracking of the coolant on the rotating cutting area. The coolant can directly act on the high-temperature areas of the main cutting edge and the flank face, achieving geometric matching between the coolant spray position and the heat peak position. This significantly reduces the temperature of the cutting area and improves the hole wall machining quality.

[0041] 3. The present invention relates to a fixed-shank drill bit with a spiral internal cooling channel and its manufacturing process. The present invention utilizes a gradual design where the cross-sectional area of ​​the spiral internal cooling channel gradually decreases from the tail to the drill tip along the axial direction. This design reduces the cross-sectional area, increases the flow velocity, and enhances the dynamic pressure of the coolant during flow. This effectively avoids flow field distortion and flash boiling caused by sudden changes in cross-sectional area at the outlet of a straight channel, maintains the single-phase flow state of the coolant, eliminates micro-corrosion damage to the channel wall and cutting zone caused by cavitation, significantly extends the service life of the drill bit, and ensures the stability of cooling efficiency.

[0042] 4. The present invention relates to a fixed-shank drill bit with a spiral internal cooling channel and its manufacturing process. The present invention effectively disperses stress concentration by adopting a variable-diameter conical surface structure and setting a stress relief groove in the neck transition section, thereby reducing the weakening effect of the internal cooling channel on the neck strength. At the same time, the spiral angle design of the spiral channel converts part of the centrifugal load borne by the channel wall into an axial load, improving the stress distribution in the neck area. While ensuring the cross-sectional area of ​​the cooling channel, the structural strength of the drill bit neck is maintained, achieving a coordinated optimization of cooling effect and structural strength.

[0043] 5. The present invention relates to a fixed shank drill bit with a rotating internal cooling channel and its manufacturing process. The present invention uses a hot fitting method to perform an interference fit assembly between the fixed shank and the drill bit body, controlling the interference amount to be three to five per thousand of the drill bit body diameter. A stress relief structure is set in the connection area, which effectively alleviates the deformation mismatch problem caused by the difference in the coefficient of linear expansion between the carbide drill bit body and the steel fixed shank, reduces the reciprocating micro-stress at the connection interface under high temperature conditions, inhibits fretting wear and the initiation of fatigue cracks, and significantly improves the reliability and service life of the fixed shank connection area. Attached Figure Description

[0044] The invention will now be further described with reference to the accompanying drawings.

[0045] Figure 1 This is a structural block diagram of a fixed shank drill bit with a rotating internal cooling channel according to the present invention; Figure 2 This is a schematic diagram of the core principle framework of the adaptive following injection of coolant in the spiral internal cooling channel of this invention; Figure 3 This is a process flow diagram of the manufacturing process of a fixed shank drill bit with a rotating internal cooling channel according to the present invention. Detailed Implementation

[0046] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0047] Example 1: This embodiment applies to the manufacturing scenario of carbide drill bits in a precision drilling production line. The scenario includes a CNC machining workshop, a hot assembly section, a precision grinding and coating production line, and a performance testing laboratory. The product manufactured in this scenario is a fixed-shank drill bit with a rotating internal cooling channel. This drill bit is used for efficient drilling of difficult-to-machine materials such as aerospace titanium alloys, medical implants, and precision molds. The drill bit manufacturing system includes five core functional modules: a design and modeling unit, a CNC machining unit, a hot assembly unit, a precision grinding and coating unit, and a performance testing unit. These modules are sequentially connected to form a complete manufacturing process from product design to qualified delivery. The process layout of this manufacturing system fully considers the differences in machining characteristics between the carbide drill bit body and the steel fixed-shank, as well as the environmental control requirements of special processes such as interference fit, precision grinding, and physical vapor deposition coating, ensuring smooth logistics and close process connection between each process.

[0048] like Figure 1 and Figure 2 As shown, the fixed shank drill bit manufacturing system with a swivel internal cooling channel consists of five core functional units. Each unit integrates process equipment and control system, and the units are connected to each other through standardized material transfer devices and data communication networks to form a complete drill bit manufacturing process chain.

[0049] The design and modeling unit is responsible for the 3D modeling, process simulation, and machining program development of drill bit products. This unit is equipped with a professional CAD / CAM software platform. The software has a pre-built parametric design module for spiral internal cooling channels. Designers can automatically generate a 3D geometric model of the spiral internal cooling channel by inputting key parameters such as drill bit diameter, helix angle, and pitch. The flow field simulation module in the software can numerically simulate the flow state of coolant in the spiral channel, calculate the flow velocity distribution, pressure distribution, and outlet spray angle of the coolant in the channel. The simulation results are displayed intuitively in the form of cloud maps to show the adaptive following spray effect of the coolant. After the design is completed, the software automatically outputs CNC machining code to the CNC machining unit and generates process parameter cards to guide the production operations of subsequent processes.

[0050] The CNC machining unit is equipped with a four-axis or higher CNC machining center as its core process equipment. The spindle speed of the machining center is set to a range of 3,000 to 15,000 revolutions per minute, and the tool feed rate is set to a range of 50 to 500 millimeters per minute, which can meet the precision milling requirements of cemented carbide materials. The unit integrates three functional stations: a drill tip grinding workstation, a spiral groove machining workstation, and a spiral internal cooling channel machining workstation. Each station is equipped with a fixture and tool system. The drill tip grinding workstation is equipped with a five-axis CNC grinding machine tool. The machine tool is equipped with an online measurement system to monitor the drill tip geometric parameters in real time. The parameters include the drill tip angle, the main cutting edge clearance angle, the secondary cutting edge clearance angle, and the chisel edge angle. The measurement accuracy of the online measurement system is better than ±0.01 degrees, which can ensure the precise control of the grinding parameters. The spiral groove machining workstation is equipped with a form milling cutter and a high-speed milling spindle. The cutting edge profile of the form milling cutter is customized according to the spiral groove design profile to ensure the geometric accuracy and surface quality of the spiral groove. The spiral internal cooling channel machining workstation is equipped with a spiral milling cutter and a high-precision CNC rotary table. The diameter of the spiral milling cutter is selected according to the channel design dimensions. The indexing accuracy of the table is better than 0.005 degrees, which can realize precise milling positioning of the spiral channel.

[0051] The hot-fitting assembly unit is equipped with three functional modules: induction heating equipment, interference fit hydraulic press, and interface quality inspection system. The power supply of the induction heating equipment is set to 15 to 25 kilowatts, and the heating temperature is monitored in real time by an infrared thermometer with a temperature measurement accuracy of ±3 degrees Celsius, ensuring that the steel shank is heated to the target temperature range of 300 to 400 degrees Celsius. The maximum thrust of the interference fit hydraulic press is set to 50 kN, and the piston stroke accuracy is better than 0.05 mm, enabling precise fitting of the shank and drill bit body. The interface quality inspection system integrates ultrasonic non-destructive testing equipment and an interface bonding strength testing machine. The frequency of the ultrasonic probe is set to 10 to 25 MHz, which can detect debonding, delamination, and crack defects at the joint interface. The bonding strength testing machine is used to verify whether the interface bonding force meets the technical requirement of not less than 300 MPa.

[0052] The precision coating unit is equipped with a centerless grinder, a vacuum arc ion plating system, and supporting pre- and post-treatment equipment. The centerless grinder uses CBN grinding wheels for external cylindrical grinding, with the wheel speed set to 3,000 to 4,500 revolutions per minute and the workpiece feed rate set to 0.5 to 2 meters per minute. The grinding allowance is controlled to be 0.1 to 0.2 millimeters, and the external roundness after precision grinding is controlled within the range of 0.001 to 0.003 millimeters. The vacuum arc ion plating system is used to deposit physical vapor deposition coatings. The coating materials are selected as either aluminum-titanium nitrogen coatings or aluminum-chromium nitrogen coatings. The vacuum level is controlled to be 1 to 5 Pascals during the coating process. The coating thickness is set to a range of two to four micrometers through precise control of the coating time. The coating unit is also equipped with a plasma cleaner for surface pretreatment before coating. The gas used for plasma cleaning is a mixture of argon and hydrogen, with a mixing ratio of 70% to 80% argon and 20% to 30% hydrogen. The cleaning power is set to 500 to 800 watts, and the cleaning time is set to 10 to 20 minutes. The post-coating treatment equipment includes a vacuum annealing furnace and a cooling device. The annealing temperature is controlled in the range of 150 to 180 degrees Celsius, and the holding time is set to 2 to 3 hours.

[0053] The performance testing unit is equipped with a high-pressure coolant circulation test bench and supporting testing instruments. The maximum supply pressure of the high-pressure coolant circulation test bench is set to 15 to 20 MPa, and the flow rate adjustment range is 0.5 to 5 liters per minute. The test bench is equipped with a high-pressure pump, flow regulating valve, pressure sensor and temperature sensor, which can simulate the coolant supply conditions during actual drill bit operation. A high-speed camera system is used to capture the coolant spray atomization effect, with a frame rate set to 0.5 milliseconds per frame, which can capture the transient shape of the sprayed liquid flow. The atomization effect analysis software calculates the atomization cone angle, atomization uniformity and droplet size distribution through image processing algorithms. The qualified standard for the atomization cone angle is 40 to 70 degrees, and the qualified standard for atomization uniformity is that the droplet density variation coefficient in the atomization area is less than or equal to 15%. A coordinate measuring machine is used for the precise measurement of drill bit geometric parameters, with the measurement uncertainty controlled to 0.001 to 0.003 millimeters.

[0054] like Figure 3 As shown, the manufacturing process of this fixed-shank drill bit with a rotating internal cooling channel includes the following steps: Step 1: Design of the drill bit body with a spiral internal cooling channel structure. This step is performed by the design modeling unit. By arranging the internal cooling channel along the axis of the drill bit body and extending in a spiral twisted shape, the tangential velocity component is generated by the guiding effect of the spiral channel wall on the coolant. This causes the coolant to form a liquid flow inclined along the rotation direction of the drill bit at the injection outlet, thereby achieving the adaptive following spray effect of the coolant on the rotating cutting area. For example, the designer determines the basic structural parameters of the drill bit body based on the workpiece material, drilling diameter, and cutting parameters. The drill bit body uses YG8 tungsten carbide cemented carbide as the base material, which has comprehensive properties of high hardness, high wear resistance, and good thermal stability. The drill bit body is composed of a drill tip, a spiral groove, a neck transition section, and a shank connection section connected in sequence. Smooth transitions are used between each part to avoid stress concentration. The drill tip is equipped with two main cutting edges symmetrically distributed, and the geometric angle of the cutting edges is optimized according to the cutting performance of the workpiece material.

[0055] The spiral internal cooling channel is arranged along the axis of the drill bit body and extends from the tail of the drill bit body to the drill tip in a spiral twisted shape. The spiral angle of the channel is set to 15 to 30 degrees, and the pitch is set to 0.5 to 1.2 times the drill bit diameter. The channel cross-section adopts the Archimedean spiral profile. This profile design enables the channel wall to provide a continuous and stable guiding effect on the coolant. The cross-sectional area of ​​the channel gradually decreases from the tail to the drill tip along the axis of the drill bit body. The cross-sectional area of ​​the channel at the tail is 15% to 25% of the cross-sectional area of ​​the drill bit body, and the cross-sectional area of ​​the channel at the drill tip is 8% to 12% of the cross-sectional area of ​​the drill bit body. The tapering design reduces the cross-sectional area, increases the flow velocity, and enhances the dynamic pressure of the coolant during flow, effectively avoiding flow field distortion and flash boiling caused by sudden changes in cross-sectional area.

[0056] The cooling of the spiral internal cooling channel utilizes the guiding effect of the spiral channel wall on the coolant to generate a tangential velocity component. When the coolant flows in the channel, the normal reaction force exerted on the coolant by the spiral channel wall is decomposed into an axial component and a tangential component. The tangential component drives the coolant to generate a pre-rotation velocity along the direction of drill bit rotation. The vector superposition of this pre-rotation velocity and the drill bit rotation velocity causes the coolant to form an inclined liquid flow at the injection outlet along the direction of drill bit rotation. The inclined liquid flow has a backward pointing injection angle relative to the drill bit surface. When the drill bit rotates at its rated speed, the spray angle reaches the range of 30 to 60 degrees, achieving an adaptive following spray effect of coolant on the rotating cutting area. After the designers construct the geometric model of the spiral internal cooling channel in the 3D modeling software, they verify the spray behavior and temperature distribution of the coolant through the flow field simulation module, confirming that the coolant can accurately act on the high-temperature areas of the main cutting edge and the flank face.

[0057] The branch channels of the branch channel structure extend outward from the main channel along a spiral line. At least two branch points are set and evenly distributed along the spiral line. The end of the branch channel leads to the drill tip cooling outlet. The cross-sectional area of ​​each branch channel is 40% to 60% of the cross-sectional area of ​​the main channel. The connection between the branch channel and the main channel adopts a circular arc transition structure with a radius of two to three times the channel width. This transition structure effectively reduces the flow resistance and pressure loss of the fluid in the branching area.

[0058] The drill tip cooling outlet ensures that the coolant can be accurately sprayed to the target area. The number and position of the spray holes are set to two or more, evenly distributed along the circumference of the drill tip, corresponding to the main cutting edge. The diameter of each spray hole is set to 1 to 1.5 mm, and the angle between the center line of the spray hole and the drill axis is set to 20 to 35 degrees. The spray direction of the spray hole is directed towards the back face area of ​​the main cutting edge of the drill tip, which is the main area where cutting heat is generated. The outlet of the spray hole is equipped with a micro-shaped flared mouth structure, with the large end of the flared mouth facing the cutting area of ​​the drill tip. This structure enables the sprayed liquid to form a good atomization effect at the outlet.

[0059] The neck transition section uses a variable diameter conical surface structure to connect the working part of the drill bit body and the fixed shank connection part. The angle between the generatrix of the conical surface and the drill bit axis is set to 10 to 15 degrees. A stress relief groove is set at the minimum diameter position of the neck transition section. The groove width is set to 0.5 to 1 mm, the groove depth is set to 0.3 to 0.6 mm, and the bottom fillet radius is set to 0.2 to 0.4 mm. The stress relief groove can effectively disperse stress concentration and reduce the weakening effect of the internal cooling channel on the neck strength.

[0060] The main channel inlet is located at the tail of the drill bit body. The main channel inlet is connected to the external coolant supply pipeline by a conical seal. The connection part is equipped with an O-ring seal groove. The groove depth is set to 2.5 to 3 mm, the groove width is set to 2 to 2.5 mm, and the inner diameter of the main channel inlet is set to 6 to 10 mm. The size design of the O-ring seal groove ensures that the seal can generate sufficient compression after installation to achieve a reliable sealing effect.

[0061] Step 2: CNC machining of the drill bit body. This step is performed by a CNC machining unit. A CNC machining center is used to grind the drill tip, machine the spiral grooves, machine the spiral internal cooling channel, and finish the shank connection section of the carbide drill bit blank. This ensures that the spiral angle, pitch, and cross-sectional dimensions of the spiral internal cooling channel meet the design accuracy requirements. The specific machining process is as follows: The carbide drill bit blank is first machined to form its basic outline, and then enters the CNC machining unit for precision machining.

[0062] The drill tip is sharpened using a five-axis CNC grinding machine. During the sharpening process, the geometric parameters of the drill tip angle, the main cutting edge clearance angle, the secondary cutting edge clearance angle, and the chisel edge angle are monitored in real time by an online measurement system. The online measurement system adopts a dual detection method combining a contact probe and a machine vision system to ensure that the error of each parameter is controlled within ±0.5 degrees. After sharpening, a diamond grinding wheel is used for finishing, with the grinding amount controlled to be 0.05 to 0.1 millimeters. The surface roughness of the drill tip after sharpening is better than 0.2 micrometers.

[0063] The spiral groove is machined using a form milling cutter for CNC milling. The cutting edge profile of the form milling cutter is customized according to the design profile of the spiral groove to ensure the geometric accuracy and surface quality of the spiral groove. During the milling process, the cutting parameters are controlled to avoid the generation of burrs and vibration marks. The angle between the rake face of the spiral groove and the drill axis is set to eight to twelve degrees, and the depth of the spiral groove is set to ten percent to fifteen percent of the drill diameter. The spindle speed of the CNC machining center is set to three thousand to fifteen thousand revolutions per minute, and the tool feed rate is set to fifty to five hundred millimeters per minute. During the machining process, oil mist cooling is used to cool the contact area between the tool and the workpiece.

[0064] Machining the spiral internal cooling channel is the most technically challenging process in the entire drill body machining process. The diameter of the spiral milling cutter is selected according to the channel design dimensions. The milling depth is completed in two to four passes according to the channel cross-section requirements. The cutting depth of each pass decreases sequentially. The cutting depth of the last pass is controlled to be 0.1 to 0.2 mm to ensure the channel surface quality. The high-precision rotary table of the CNC machining center precisely controls the helix angle and pitch parameters during the milling process to ensure that the spiral geometry of the channel meets the design requirements. After milling, the inner surface of the channel is finished by electrolytic polishing. The electrolyte for electrolytic polishing is sodium nitrate aqueous solution, and the polishing voltage is set to 15 to 25 volts. The roughness of the inner surface of the channel is controlled to be 0.4 to 0.8 micrometers.

[0065] The dimensional accuracy of the fixed shank connecting section is controlled at IT6 level, the surface roughness is controlled at 0.8 to 1.6 micrometers, the coaxiality of the outer circle and inner hole of the fixed shank connecting section is controlled within the range of 0.02 to 0.03 millimeters, the finishing is carried out by a centerless grinder, and the grinding allowance is controlled at 0.1 to 0.2 millimeters.

[0066] Step 3: Assemble the interference fit between the shank and the drill body. This step is performed by the hot-fit assembly unit. The steel shank and the carbide drill body are connected by an interference fit using a hot-fit method. The interference fit is controlled to be 0.3% to 0.5% of the drill body diameter to ensure the stability of the preload at the connection interface under high-temperature conditions. The specific assembly process is as follows: Before assembly, the fixed shank connection hole of the carbide drill bit body is ultrasonically cleaned to remove machining residues and contaminants. After cleaning, dry nitrogen is used to purge the residual liquid in the hole and the actual inner diameter of the fixed shank connection hole is measured. The steel fixed shank is also cleaned and measured before assembly. The actual interference is calculated based on the measured dimensions. The interference is controlled to be three to five per thousand of the drill bit body diameter. Too little interference will result in insufficient connection strength, while too much interference will result in assembly difficulties and increase interface stress.

[0067] The hot fitting method uses induction heating to rapidly heat the steel fixed handle. The power of the induction heating power supply is set to 15 to 25 kilowatts, the heating temperature is monitored in real time by an infrared thermometer, and the heating time is controlled to be 30 to 60 seconds. When the steel shank is heated to 300 to 400 degrees Celsius, the outer diameter of the shank material increases due to thermal expansion. At this time, the fit clearance between the inner diameter of the shank and the outer diameter of the shank connection hole in the drill bit body increases to a level sufficient for free insertion. After heating, the insertion operation between the shank and the drill bit body is completed within five seconds. During the insertion process, the coaxiality deviation between the shank and the drill bit body axis is kept less than 0.02 mm by the clamp. As the temperature of the steel shank gradually decreases and returns to room temperature, the shank material shrinks and forms an interference fit connection with the drill bit body. The connection interface generates a uniformly distributed preload to ensure connection reliability.

[0068] The microscopic bonding quality of the interference fit interface is verified by the interface bond strength test. The bond strength is judged by the interface shear strength of not less than 300 MPa. During the test, ultrasonic non-destructive testing method is used to screen for defects in the interface. When the screening results show no interface debonding, delamination and cracks, it is judged as qualified. The frequency of the ultrasonic probe is selected from 10 to 25 MHz to obtain sufficient detection resolution.

[0069] The stress-relief structure in the shank connection area effectively enhances connection reliability and service life. The stress-relief structure includes a transition fillet at the end of the shank, a micro-threaded groove at the connection interface, and a tapered weight-reducing structure in the inner cavity of the shank. The radius of the transition fillet is set to 0.1 to 0.15 times the drill bit body diameter. This fillet design reduces stress concentration. The pitch of the micro-threaded groove at the connection interface is set to 0.5 to 1 mm, and the groove depth is set to 0.1 to 0.2 mm. The micro-threaded groove increases the interface contact area and provides a mechanical locking effect. The cone angle of the tapered weight-reducing structure in the inner cavity of the shank is set to 60 to 90 degrees. This structure reduces the weight of the shank while maintaining sufficient structural strength.

[0070] Step four involves overall precision grinding and coating of the drill bit. This step is performed by the precision grinding and coating unit, which uses a centerless grinder to precision grind the drill bit neck and working part, followed by physical vapor deposition coating treatment. The specific process is as follows: After the hot-fitting assembly is completed, the drill bit blank is first inspected for dimensions and geometric tolerances. After confirming that the dimensions of each part meet the process requirements, it enters the fine grinding process.

[0071] The overall fine grinding is carried out using a centerless grinder. During the grinding process, CBN grinding wheels are used for external cylindrical grinding. CBN grinding wheels have high hardness and good wear resistance, which can effectively grind cemented carbide materials with minimal wheel wear. The grinding wheel speed is set to 3,000 to 4,500 revolutions per minute, the workpiece feed speed is set to 0.5 to 2 meters per minute, and the grinding allowance is controlled to 0.1 to 0.2 millimeters. During the fine grinding process, the outer roundness and dimensional accuracy of the drill bit are monitored by an online measurement system. After fine grinding, the outer roundness of the working part of the drill bit is controlled within the range of 0.001 to 0.003 millimeters. After fine grinding, the geometry of the stress relief groove of the neck transition section is precisely guaranteed, and the groove width, groove depth, and groove bottom fillet radius are all controlled within the design tolerance range.

[0072] Before coating treatment, the drill bit surface is subjected to plasma cleaning to remove surface contaminants and activate the surface crystal structure. The plasma cleaning gas is a mixture of argon and hydrogen, with a mixing ratio of 70% to 80% argon and 20% to 30% hydrogen. The cleaning power is set to 500 to 800 watts, and the cleaning time is set to 10 to 20 minutes. Plasma cleaning can effectively remove organic contaminants and oxide layers from the drill bit surface, giving the substrate surface a higher surface energy, which is beneficial for forming a strong metallurgical bond between the coating and the substrate.

[0073] Physical vapor deposition coating is performed using vacuum arc ion plating equipment. The coating material is either nitrogen-aluminum-titanium coating or nitrogen-chromium-aluminum coating. The working principle of vacuum arc ion plating is to use the coating material as a target and evaporate it through arc discharge. The evaporated material atoms react with the reactive gas in a vacuum environment to generate a compound coating that is deposited on the surface of the drill bit. The coating thickness is set to the range of two to four micrometers by precise control of the coating time. The coating hardness is controlled to be 1,800 to 2,500 Vickers hardness. The adhesion between the coating and the substrate is tested by scratch test. The critical load is not less than 60 Newtons. The scratch test is performed by continuously scratching the coating surface with a diamond stylus and gradually increasing the load until the coating peels off.

[0074] After the coating is completed, the drill bit is subjected to post-treatment heat treatment to eliminate the internal stress of the coating. The temperature of the post-treatment heat treatment is controlled in the range of 150 to 180 degrees Celsius, and the holding time is set to two to three hours. After heat treatment, the drill bit is cooled to room temperature in the furnace to avoid the generation of thermal stress. Heat treatment can effectively reduce the residual tensile stress inside the coating, improve the coating's resistance to crack propagation, and extend the service life of the coating under intermittent cutting conditions.

[0075] Step 5 involves drill bit performance testing and quality inspection. This step is performed by the performance testing unit. The internal cooling channel flow rate, channel pressure bearing capacity, and jet atomization effect of the drill bit are tested using a high-pressure coolant circulation test bench. Qualified products that meet the design specifications are selected. The specific testing process is as follows: The drill bit is mounted on the fixture of the test bench. The fixture simulates the connection method of the actual machine tool spindle to ensure the consistency between the test conditions and the actual use conditions. The maximum supply pressure of the high-pressure coolant circulation test bench is set to 15 to 20 MPa, and the flow rate adjustment range is 0.5 to 5 liters per minute. During the test, the actual flow rate of the internal cooling channel is monitored in real time by the flow sensor, and the pressure bearing capacity of the channel is monitored by the pressure sensor. When the supply pressure is gradually increased to the rated working pressure, the channel should not leak or deform. The pressure holding time for the pressure test is set to thirty seconds.

[0076] The coolant spray atomization effect was tested using a high-speed camera system. The frame rate of the high-speed camera system was set to 0.5 milliseconds per frame to capture the transient shape of the sprayed fluid. During the test, the coolant supply pressure was set to 10 MPa to simulate the cooling conditions under actual drilling conditions. The atomization cone angle, atomization uniformity, and droplet size distribution of the sprayed fluid were analyzed using image processing algorithms. The acceptable standard for the atomization cone angle is 40 to 70 degrees. An excessively large atomization cone angle indicates insufficient spray kinetic energy, resulting in the coolant not being able to effectively reach the cutting zone. An excessively small atomization cone angle indicates that the spray is too concentrated, resulting in insufficient cooling coverage. The acceptable standard for atomization uniformity is that the droplet density variation coefficient within the atomized area is less than or equal to 15%. Insufficient atomization uniformity will lead to uneven cooling in the cutting zone.

[0077] The service life test of the drill bit was conducted using a drilling test method to verify the actual machining performance of the drill bit. The test material was aerospace-grade titanium alloy TC4 plate. This material is recognized as one of the most difficult materials to machine due to its high strength, low thermal conductivity and high chemical activity, which can fully test the comprehensive performance of the drill bit. The drilling parameters were set as follows: rotation speed of 3,000 to 5,000 revolutions per minute, feed rate of 50 to 100 millimeters per minute, and depth of cut of one to three times the drill bit diameter. During the drilling test, coolant with a pressure of 10 MPa was continuously supplied. The criteria for judging the failure of the drill bit were that the wear of the drill tip reached 0.3 millimeters or the drilling size accuracy exceeded the IT8 grade tolerance. During the drilling test, the drilling force, drilling torque and vibration signal were continuously monitored. These parameters can reflect the working status of the drill bit during the cutting process.

[0078] Quality inspection also includes the measurement and inspection of drill bit geometric parameters. The drill tip angle is measured using a projector with a measurement accuracy better than 0.1 degrees. The runout of the main cutting edge is measured using a runout meter, and the runout should be controlled within 0.02 millimeters. The chisel edge alignment is measured using a tool microscope, and the chisel edge alignment deviation should be controlled within 0.1 millimeters. The total length of the drill bit and the length of the working part are measured using a coordinate measuring machine, and the measurement uncertainty is controlled to be between 0.001 and 0.003 millimeters. The probe of the coordinate measuring machine is a contact ruby ​​probe, and the measuring force is controlled within one Newton to avoid indentation on the cemented carbide surface.

[0079] Example 2: This embodiment is applied to the manufacturing of ultra-long spiral internal cooling channel drill bits for deep hole drilling. Compared with Embodiment 1, this embodiment has made targeted adjustments to the structural design and processing technology of the spiral internal cooling channel to adapt to the special needs of deep hole drilling.

[0080] In terms of the spiral internal cooling channel structure design, the length of the spiral internal cooling channel in deep hole drilling bits has been significantly increased. The ratio of the total channel length to the working part length of the drill bit has been increased from 0.8 in standard drill bits to more than 1.5. The spiral angle of the channel has been adjusted to 10 to 20 degrees to increase the residence time of the coolant in the channel and enhance the pre-swirl effect. The pitch has been adjusted to 1.0 to 1.5 times the drill bit diameter to provide a larger channel volume. The tapering ratio of the channel cross-sectional area along the axis has been increased. The cross-sectional area of ​​the tail channel has been increased to 20% to 30% of the cross-sectional area of ​​the drill bit body, while the cross-sectional area of ​​the drill tip channel has been reduced to 6% to 8% of the cross-sectional area of ​​the drill bit body. This design increases the liquid storage volume of the channel while ensuring the dynamic pressure of the coolant jet, enabling a continuous supply of coolant when the drill bit enters the deep hole.

[0081] Regarding the branch channel structure, drill bits for deep hole drilling are equipped with more than three branch channels to meet the cooling requirements of deep hole machining. At least four branch points are evenly distributed along the spiral line. Increasing the number of branch channels makes the coolant distribution in the drill tip area more uniform. The cross-sectional area of ​​the branch channels is adjusted to 30% to 50% of the cross-sectional area of ​​the main channel. The radius of the arc transition at the connection between the branch channel and the main channel is increased to three to four times the channel width to reduce fluid resistance.

[0082] In terms of machining technology, the machining of the spiral internal cooling channel of the drill bit for deep hole drilling adopts a multi-step composite milling strategy. Due to the increase in channel length, the extension length of the spiral end mill increases accordingly, resulting in a decrease in tool rigidity. During the machining process, it is easier to generate vibration marks and dimensional errors. For this reason, a slender carbide spiral end mill is used in conjunction with a high-precision CNC machine tool for machining. The maximum length-to-diameter ratio of the tool is controlled within 15:1. The spindle speed is reduced to the range of 2,000 to 8,000 revolutions per minute to reduce the influence of centrifugal force on the slender tool. The tool feed rate is reduced accordingly to ensure cutting quality. The polishing time of the electrolytic polishing process is extended to 1.5 to 2 times that of the standard process to ensure the uniformity of the inner surface of the long channel.

[0083] In terms of coating process, the drill bit for deep hole drilling adopts a multi-layer composite coating structure to enhance wear resistance and anti-diffusion properties. The bottom layer is a titanium nitride coating with a thickness controlled at one to two micrometers. This layer has good adhesion to the cemented carbide substrate. The middle layer is a titanium nitride aluminum coating with a thickness controlled at two to three micrometers. This layer provides excellent wear resistance. The outer layer is a titanium nitride chromium aluminum coating with a thickness controlled at one to two micrometers. This layer provides good resistance to chemical diffusion. The total thickness of the multi-layer coating is controlled in the range of four to six micrometers to ensure coating toughness.

[0084] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A manufacturing process for a fixed-shank drill bit with a rotating internal cooling channel, characterized in that, Includes the following steps: S1. By using an internal cooling channel arranged along the axis of the drill bit body and extending in a spiral twisted shape, the tangential velocity component is generated by the guiding effect of the spiral channel wall on the coolant, so that the coolant forms a liquid flow inclined along the rotation direction of the drill bit at the injection outlet, thereby achieving the adaptive following injection effect of the coolant on the rotating cutting area. S2. The carbide drill bit blank is subjected to drill tip grinding, spiral groove machining, spiral internal cooling channel machining, and shank connection section precision machining by CNC machining center to ensure that the spiral angle, pitch and channel cross-sectional dimensions of the spiral internal cooling channel meet the design accuracy requirements. S3. The steel fixed shank and the carbide drill bit body are connected by interference fit using the hot fitting method. The interference is controlled within the preset range to ensure the stability of the preload force of the connection interface under high temperature conditions. S4. The drill neck and working part are precision ground using a centerless grinder, followed by physical vapor deposition coating treatment; S5. The internal cooling channel flow rate, channel pressure bearing capacity, and jet atomization effect of the drill bit are tested using a high-pressure coolant circulation test bench to screen qualified products that meet the design specifications.

2. The manufacturing process of a fixed-shank drill bit with a rotating internal cooling channel according to claim 1, characterized in that, In step S2, the spiral internal cooling channel is machined using a spiral milling cutter via CNC milling.

3. The manufacturing process of a fixed-shank drill bit with a rotating internal cooling channel according to claim 1, characterized in that, In step S3, the steel fixed shank is heated during the hot fitting assembly process, and after heating, the fixed shank is nested with the drill bit body.

4. The manufacturing process of a fixed-shank drill bit with a rotating internal cooling channel according to claim 1, characterized in that, In step S4, the physical vapor deposition coating treatment is performed using a vacuum arc ion plating device.

5. The manufacturing process of a fixed-shank drill bit with a rotating internal cooling channel according to claim 1, characterized in that, In step S5, the coolant spray atomization effect is tested by analyzing the atomization cone angle, atomization uniformity, and droplet size distribution of the sprayed liquid flow using an image processing algorithm.

6. A fixed-shank drill bit with a spiral internal cooling channel, applicable to the manufacturing process of a fixed-shank drill bit with a spiral internal cooling channel as described in any one of claims 1-5, characterized in that, It includes a carbide drill bit body, a spiral internal cooling channel, a drill tip cooling outlet, a neck transition section, and a steel fixed shank; The carbide drill bit body is composed of a drill tip, a spiral groove, a neck transition, and a shank connection connected in sequence. The spiral internal cooling channel is arranged along the axis of the drill bit body and extends from the tail of the drill bit body to the drill tip in a spiral twisted shape. The spiral angle and pitch of the channel are determined according to the coolant flow field. The cross-section of the channel is formed by an Archimedean spiral profile. The cross-sectional area of ​​the channel gradually decreases from the tail to the drill tip along the axis of the drill bit body. The drill tip cooling outlet is located in the back face area of ​​the drill tip. The number and position of the spray holes correspond to the main cutting edge, and the spray direction of each spray hole points to the back face area of ​​the main cutting edge of the drill tip.

7. A fixed-shank drill bit with a rotating internal cooling channel according to claim 6, characterized in that, The spiral internal cooling channel has a branch channel structure inside the drill bit body. The branch channel extends outward from the main channel along the spiral line. At least two branch points are set and evenly distributed along the spiral line. The end of the branch channel leads to the drill tip cooling outlet.

8. A fixed-shank drill bit with a rotating internal cooling channel according to claim 6, characterized in that, The neck transition section uses a variable diameter conical surface structure to connect the working part of the drill bit body and the fixed shank connection part, and a stress relief groove is set at the minimum diameter position of the neck transition section.

9. A fixed-shank drill bit with a rotating internal cooling channel according to claim 6, characterized in that, The steel shank and the carbide drill bit body are connected by a hot-fitting interference fit, and the connection interface is provided with a fine threaded groove to enhance the bonding force.

10. A fixed-shank drill bit with a rotating internal cooling channel according to claim 6, characterized in that, The outer surface of the working part of the cemented carbide drill bit body is provided with a physical vapor deposition coating.

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