A drill bit and a drilling method for drilling a thin-walled part of a high-ductility material

Abstract

The present application relates to the technical field of drilling processing, and discloses a drill bit and a drilling method for drilling thin-walled parts of high ductility materials. The first cutting edge of the drill bit is provided with a chip separation groove, the second cutting edge is provided with a second chip separation groove and a third chip separation groove, the three chip separation grooves are arranged in order from inside to outside, and the axial depth of each chip separation groove is greater than the feed per revolution. During drilling, each chip separation groove divides the drilling area into five chip segments, the cross-sectional area of each chip segment tends to be equal, the chip is curled and broken and then discharged, and the possibility of chip winding around the tool and blocking the chip removal channel is reduced. The method drives the drill bit to rotate and feed at a linear speed of 160 to 180 m / min and a feed of 0.25 to 0.5 mm / r. The drill bit and the method solve the problems of difficult chip breaking, easy tool sticking, thin-walled deformation, and difficult control of hole bottom flanging burr in the drilling of thin-walled parts of high ductility materials, realize continuous automatic processing, and improve the processing efficiency by more than two times.

Description

Technical Field

[0001] This application relates to the field of drilling technology, and in particular to a drill bit and drilling method for drilling thin-walled parts made of highly ductile materials. Background Technology

[0002] Chromium-zirconium copper (CZT) is widely used in aerospace engine parts due to its excellent electrical and thermal conductivity and mechanical properties. However, this material is soft, sticky, and ductile, causing chips to continuously wrap around the drill bit during drilling, making them difficult to break. Furthermore, the chips tend to adhere to the cutting edge, accelerating tool wear and deteriorating hole wall quality. In actual machining, manual chip breaking and removal are often required, resulting in low efficiency and inconsistent surface quality.

[0003] In existing drill bits, some designs incorporate chip-breaking grooves on the cutting edge to improve chip breaking performance. For example, one drill bit has two centrally symmetrically arranged inserts, each with chip-breaking grooves that are circumferentially offset to divide the chip into multiple segments. However, this type of design primarily focuses on the presence and circumferential offset of chip-breaking grooves, without addressing the distribution of the number of grooves on the two inserts or specifying the radial position of each groove. This makes it difficult to apply to drilling of highly ductile materials.

[0004] The above problems are even more pronounced for thin-walled, low-rigidity parts. Thin-walled parts have poor rigidity and are sensitive to cutting forces. Even a slightly large radial force or impact during drilling can easily cause deformation and tool deflection, and burrs on the bottom of the hole are also difficult to control. Existing drill bits cannot meet the dual requirements of chip breaking and chip removal and cutting force control in machining thin-walled parts made of high-ductility materials, resulting in large fluctuations in machining quality and making it difficult to meet the precision and efficiency requirements of aerospace. Summary of the Invention

[0005] The purpose of this application is to provide a drill bit and drilling method for drilling thin-walled parts made of high ductility materials, in order to solve the problems of difficulty in chip breaking, chip entanglement, tool sticking, easy deformation of thin walls, and difficulty in controlling burrs at the bottom of the hole when existing drill bits are used to process thin-walled parts made of high ductility materials.

[0006] The technical solution is as follows: Firstly, a drill bit for drilling thin-walled parts made of highly ductile materials, comprising: a drill bit body, the front end of which is provided with a first cutting edge and a second cutting edge, the first cutting edge and the second cutting edge being distributed circumferentially along the drill bit body; a first chip-breaking groove is provided on the cutting edge of the first cutting edge, and a second chip-breaking groove and a third chip-breaking groove are provided on the cutting edge of the second cutting edge; the second chip-breaking groove, the first chip-breaking groove, and the third chip-breaking groove are arranged sequentially from the center of the drill tip outwards; the axial depth of the first chip-breaking groove, the second chip-breaking groove, and the third chip-breaking groove is greater than the axial feed per revolution of the drill bit.

[0007] Optionally, the second chip-dividing groove and the third chip-dividing groove are located at different radii of the second cutting edge.

[0008] Optionally, after the first cutting edge rotates 180° around the rotation center of the drill bit body, the first chip groove, the second chip groove, and the third chip groove are all in different positions in the circumferential direction.

[0009] Optionally, the first chip divider, the second chip divider, and the third chip divider divide the drilling area into five cutting segments, and the cross-sectional area of ​​each cutting segment tends to be equal.

[0010] Optionally, the first cutting edge and the second cutting edge have a rake angle γ that facilitates chip curling and breaking, and a clearance angle that facilitates reducing friction between the clearance face and the workpiece; the rake angle γ is ≥30°, and the clearance angle includes a primary clearance angle α1 and a secondary clearance angle α2, wherein the primary clearance angle α1 is ≥15° and the secondary clearance angle α2 is ≥25°.

[0011] Optionally, the cutting edges of the first cutting edge and the second cutting edge have an eccentricity L4 and an over-centering amount L5 respectively relative to the rotation center of the drill body. The cutting edges of each cutting edge do not pass through the rotation center, and the rake faces of the two cutting edges intersect in the central region of the drill tip, forming a recessed chip-receiving space.

[0012] Optionally, the high ductility material includes chromium zirconium copper, pure copper, oxygen-free copper, or aluminum alloy; the width-to-thickness ratio d / h of the thin-walled part is ≥30, where h is the wall thickness of the thin-walled part and d is the shape dimension of the thin-walled part perpendicular to the thickness direction.

[0013] Secondly, this application also provides a drilling method for thin-walled parts made of highly ductile materials, using the above-mentioned drill bit, driving the drill bit to rotate and feed axially at a cutting linear speed of 160m / min to 180m / min and a feed per revolution of 0.25mm / r to 0.5mm / r to perform drilling on the workpiece;

[0014] During drilling, the uncut residual material at the chip groove of one cutting edge is removed by the complete cutting edge of another cutting edge, and the chips are separated into multiple segments and discharged.

[0015] Optionally, the workpiece is a thin-walled part made of chromium zirconium copper material, and the width-to-thickness ratio d / h of the thin-walled part is ≥30, where h is the wall thickness of the thin-walled part and d is the shape dimension of the thin-walled part perpendicular to the thickness direction.

[0016] Optionally, the drill bit divides the chips into five chip segments within one rotation, and the five chip segments break sequentially along the circumferential direction, with the fracture surfaces staggered sequentially in the circumferential direction.

[0017] The beneficial effects of the technical solutions provided in this application include at least the following:

[0018] The present invention provides a drill bit for drilling thin-walled parts made of highly ductile materials. A chip-breaking groove is provided on the first cutting edge, and a second and third chip-breaking groove are provided on the second cutting edge. The three chip-breaking grooves are arranged radially in the order of inner, middle, and outer, dividing the drilling area into five chip segments. When the radial positions of the three chip-breaking grooves satisfy the condition of equal area division, the cross-sectional areas of the five chip segments tend to be equal, the bending stiffness of each segment is consistent, and the chip breaking rhythm is uniform, reducing the possibility of chips entangled in the tool and clogging the chip removal channel. The axial depth of each chip-breaking groove is greater than the feed per revolution. Any residual ribs left by one cutting edge chip-breaking groove are completely removed by the complete cutting edge of another cutting edge in the next rotation cycle, leaving no burrs at the bottom of the hole. The second and third chip-breaking grooves are located at different radii on the second cutting edge, distributing the outer edge cutting area across the three cutting edge segments and avoiding concentrated impact loads. The first chip-breaking groove differs from the second and third chip-breaking grooves in circumferential angle, resulting in an angular difference in the circumferential direction at the moment of chip removal for each chip segment, thus preventing the instantaneous impact from superimposing. This drill bit is suitable for high-ductility materials such as chromium-zirconium copper, pure copper, oxygen-free copper, and aluminum alloys with high elongation.

[0019] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a perspective view of a drill bit for drilling thin-walled parts made of highly ductile materials, as provided in an embodiment of this application.

[0022] Figure 2 This is a front view of a drill bit for drilling thin-walled parts made of highly ductile materials, as provided in an embodiment of this application.

[0023] Figure 3 This is a left view of a drill bit for drilling thin-walled parts made of highly ductile materials, as provided in an embodiment of this application.

[0024] Figure 4 yes Figure 3 Cross-sectional view at point AA.

[0025] Explanation of reference numerals in the attached figures

[0026] 1-Drill body; 2-First cutting edge; 3-Second cutting edge; 4-First chip flute; 5-Second chip flute; 6-Third chip flute; L1-Distance from the first chip flute to the drill tip; L2-Distance from the second chip flute to the drill tip; L3-Distance from the third chip flute to the drill tip; L4-Eccentricity; L5-Overcenter; γ-Rake angle; α1-Major clearance angle; α2-Secondary clearance angle. Detailed Implementation

[0027] The specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0028] In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the relative positions of the corresponding components in the direction of gravity when they are in use, while "inner" and "outer" refer to their relative positions to the contours of the corresponding components themselves. Furthermore, the terms "first," "second," etc., used in this application are for distinguishing one element from another and do not imply sequentiality or importance. In the following description, when referring to the accompanying drawings, unless otherwise explained, the same reference numerals in different drawings denote the same or similar elements.

[0029] The present application will now be described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the application.

[0030] First aspect: According to the embodiments of this application, reference is made to Figures 1 to 4 A drill bit is provided for drilling thin-walled parts made of highly ductile materials. The drill bit has a drill body 1, with a first cutting edge 2 and a second cutting edge 3 distributed circumferentially at the front end of the drill body 1. The two cutting edges are arranged 180° apart circumferentially. A first chip-breaking groove 4 is formed on the cutting edge of the first cutting edge 2, and a second chip-breaking groove 5 and a third chip-breaking groove 6 are formed on the cutting edge of the second cutting edge 3. The first chip-breaking groove 4 is located in the radially central region of the first cutting edge 2, the second chip-breaking groove 5 is located in the radially inner region of the second cutting edge 3, and the third chip-breaking groove 6 is located in the radially outer region of the second cutting edge 3. Viewed from the drill tip along the outer edge of the cutting edge, the three chip-breaking grooves are arranged sequentially in the order of second chip-breaking groove 5, first chip-breaking groove 4, and third chip-breaking groove 6.

[0031] The axial depth of each chip flute is greater than the axial feed per revolution of the drill bit. This constraint ensures that during the cutting process, any residual ridges formed on the workpiece by the chip flute of one cutting edge can be completely removed by the full cutting edge of another cutting edge in subsequent drill cycles, without leaving uncut material protrusions at the bottom of the hole.

[0032] During one revolution of the drill bit, the material in the drilling area is divided into five chip segments by three chip flutes. Each of the five chip segments forms independently and does not connect to form a continuous band. The width of each chip segment is controlled within a small range, resulting in reduced bending stiffness. The chips curl and break immediately after formation, reducing the possibility of chips entangled in the tool and clogging the chip removal channel. The chip removal channel remains unobstructed, requiring no manual cleaning. Deformation of thin-walled parts caused by cutting force fluctuations during drilling is suppressed, and no burrs remain at the bottom of the hole.

[0033] According to the embodiments of this application, refer to Figures 1 to 3 The first chip-breaking groove 4 is located on the cutting edge of the first cutting edge 2, and the second chip-breaking groove 5 and the third chip-breaking groove 6 are located on the cutting edge of the second cutting edge 3. The second chip-breaking groove 5 and the third chip-breaking groove 6 are located at different radii of the second cutting edge 3, that is, the second chip-breaking groove 5 is closer to the drill tip, and the third chip-breaking groove 6 is farther from the drill tip.

[0034] The second chip-breaking groove 5 and the third chip-breaking groove 6 are located in the radially inner and radially outer regions of the second cutting edge 3, respectively. The second cutting edge 3 is divided into three cutting edge segments by these two chip-breaking grooves: the inner segment handles the cutting of the central region, the middle segment handles the cutting of the middle region, and the outer segment handles the cutting of the outer edge region. During the rotation of the drill bit, the three cutting edge segments of the second cutting edge 3 independently form chips, and adjacent cutting edge segments are separated by the chip-breaking grooves, preventing mutual interference. The cutting area of ​​the outer edge region handled by the second cutting edge 3 is distributed among the three cutting edge segments by the two chip-breaking grooves, resulting in a relatively uniform cutting area for each cutting edge segment. This controls the single impact load and avoids vibration and tool deflection in the outer edge region due to excessively large chip cross-sections.

[0035] According to the embodiments of this application, refer to Figure 3 After the first cutting edge 2 rotates 180° around the rotation center of the drill bit body 1, the first chip groove 4, the second chip groove 5, and the third chip groove 6 are all at different angular positions in the circumferential direction.

[0036] The first cutting edge 2 and the second cutting edge 3 are arranged 180° apart on the circumference, but the circumferential angular position of the first chip-breaking groove 4 is offset from the circumferential angular positions of the second chip-breaking groove 5 and the third chip-breaking groove 6. The three chip-breaking grooves are evenly distributed throughout the entire circumference of the drill bit, and there is no situation where two chip-breaking grooves are at the same circumferential angular position. During the rotation of the drill bit, the three chip-breaking grooves independently and sequentially cut into and detach from the workpiece, and the cutting forces generated by each chip-breaking groove appear sequentially in time rather than being superimposed simultaneously. The removal times of the five chip segments have a phase difference in the circumferential direction, preventing the superposition of multiple chip-breaking impacts at the same time, and keeping the instantaneous impact load at a low level.

[0037] According to the embodiments of this application, refer to Figure 3 The first chip-breaking groove 4, the second chip-breaking groove 5, and the third chip-breaking groove 6 divide the entire drilling area into five cutting segments, and the cross-sectional area of ​​each cutting segment tends to be equal.

[0038] The radial positions of the three chip-breaking grooves are determined based on the principle of equal area division of the drill cross-section. For example, assuming the drill radius is R, to ensure that the cross-sectional areas of the five cutting sections are approximately uniform, the second chip-breaking groove 5, the first chip-breaking groove 4, and the third chip-breaking groove 6 are located radially at 0.577R, 0.707R, and 0.816R, respectively. Specifically, the second chip-breaking groove 5 is located at a distance L2 from the drill tip (L2 = 0.577R), the first chip-breaking groove 4 is located at a distance L1 from the drill tip (L1 = 0.707R), and the third chip-breaking groove 6 is located at a distance L3 from the drill tip (L3 = 0.816R). L2, L1, and L3 are arranged radially in sequence, with L2 < L1 < L3. The maximum deviation between the cross-sectional areas of the five cutting sections does not exceed 10% of the average cross-sectional area. This 10% deviation range is derived from the allowable deviation between the theoretically calculated value of equal area division and the actual grinding tolerance, and can be controlled within the range of 5% to 8% in actual machining measurements. This value can be adjusted appropriately according to the actual machining accuracy.

[0039] The uniform cross-sectional area of ​​each cutting segment brings two benefits. First, the bending stiffness of each chip segment is similar, resulting in similar curl radii and fracture rhythms during cutting. This prevents situations where one chip segment is too large to break while another fragments too small. Second, the impact load generated during chip fracture is similar across all segments, leading to a more rhythmic chip breaking process. This reduces torque fluctuations on the drill bit's main bearing, which is particularly beneficial for thin-walled parts with poor rigidity, suppressing tool deflection during machining.

[0040] According to the embodiments of this application, refer to Figure 3 and Figure 4 The first cutting edge 2 and the second cutting edge 3 have a rake angle γ and a clearance angle, respectively. The rake angle γ is greater than or equal to 30°, and the clearance angle is divided into a major clearance angle α1 and a minor clearance angle α2. The major clearance angle α1 is greater than or equal to 15°, and the minor clearance angle α2 is greater than or equal to 25°.

[0041] When the rake angle γ is greater than or equal to 30°, the sharpness of the cutting edge is high, the deformation coefficient of the cutting layer metal is reduced, and the cutting force is correspondingly reduced. For highly ductile materials such as chromium, zirconium, and copper, a large rake angle γ allows the chip to bend with a small curl radius in the early stage of chip formation, reducing the contact length between the chip and the rake face, and reducing the tendency of the chip to rub against and adhere to the rake face. A clearance angle configuration with a major clearance angle α1 greater than or equal to 15° and a minor clearance angle α2 greater than or equal to 25° reduces the contact area between the clearance face and the machined surface, reduces frictional heat, reduces the elastic recovery of the machined surface, and correspondingly improves the hole wall quality. At the same time, a large clearance angle weakens the squeezing effect of the cutting edge on the bottom edge of the hole when penetrating the workpiece exit, and correspondingly reduces the height of the flanging burr.

[0042] There is a synergistic relationship between the angle parameters and the chip-breaking grooves. The second chip-breaking groove 5, the first chip-breaking groove 4, and the third chip-breaking groove 6 reduce the chip width, significantly decreasing the chip's bending stiffness and making it more prone to bending deformation. The large rake angle γ further ensures that the chip bends with a small curl radius, causing it to break within a very short length immediately after formation. The combined effect of these two factors means that the chip-breaking effect does not depend on a single parameter, but is achieved through the combined effect of the reduced width of the chip-breaking grooves and the bending promotion of the large rake angle γ. Simultaneously, the large clearance angle reduces friction between the flank face and the workpiece, preventing additional pulling on the chip as it leaves the workpiece surface, further solidifying the chip-breaking effect.

[0043] According to the embodiments of this application, refer to Figure 1 and Figure 2 The first cutting edge 2 and the second cutting edge 3 have an eccentricity L4 and an over-center distance L5 relative to the rotation center of the drill body 1, respectively, and the cutting edges do not pass through the rotation center. The rake faces of the two cutting edges intersect in the central region of the drill tip, forming a concave chip-receiving space.

[0044] Eccentricity L4 refers to the offset of the starting point of the inner cutting edge relative to the center of rotation, and the over-center amount L5 refers to the amount by which the ending point of the inner cutting edge crosses the center of rotation. Neither cutting edge passes through the center of rotation, and the central area of ​​the drill tip is no longer occupied by the chisel edge. The two rake faces converge and connect in the central area, forming a recessed cavity structure. This cavity serves as a chip-collecting space during drilling. When chips are removed from the cutting edges, they first enter this recessed space for curling and buffering, and then are discharged outwards along the chip removal groove.

[0045] For highly ductile materials, chips expand significantly during formation. If there is no chip-holding space in the central area, the chips will be compressed and accumulated at the drill tip, leading to a sharp increase in axial force and causing deformation of thin-walled parts. This recessed space provides a buffer zone, allowing the chips to curl freely after formation, preventing blockage at the drill tip and ensuring smooth chip removal.

[0046] According to the embodiments of this application, refer to Figure 1 and Figure 2 High ductility materials include chromium zirconium copper, pure copper, oxygen-free copper, and aluminum alloys with an elongation of ≥15%. These materials have strong adhesion and are the most difficult to break.

[0047] For thin-walled parts, the width-to-thickness ratio d / h ≥ 30, where h is the wall thickness and d is the shape dimension perpendicular to the thickness direction. A larger width-to-thickness ratio weakens the rigidity of the thin-walled part, resulting in poor resistance to deformation under cutting forces during drilling. This leads to more prominent issues with tool deflection and burr formation on the hole wall, placing stricter requirements on the chip flute layout and process parameters. In this specific working condition, the drill bit's chip flute layout divides the chips into five segments with similar cross-sectional areas, consistent bending stiffness, and uniform chip breaking rhythm. The large rake angle γ configuration allows the cutting edge to complete the cut with lower cutting force, keeping the deformation of the thin-walled part within acceptable tolerances. Actual machining verification shows that using this drill bit and process parameters under these conditions achieves more than twice the machining efficiency of traditional methods, with a hole wall surface roughness Ra value not exceeding 3.2 micrometers and a hole bottom burr height not exceeding 0.1 millimeters. The above roughness and burr height data are derived from actual machining verification measurements using chromium-zirconium-copper thin-walled parts.

[0048] Secondly, this application also provides a drilling method in which the cutting speed is set to 160 m / min to 180 m / min and the feed per revolution is set to 0.25 mm / revolution to 0.5 mm / revolution, driving the drill bit to rotate and feed axially.

[0049] Within this parameter range, the drill bit's rotational speed and feed rate are matched to ensure that each chip-breaking groove can complete chip segmentation as designed. The feed per revolution is less than the axial depth of each chip-breaking groove, and the residual ridge height left on the workpiece by each chip-breaking groove is less than the groove depth, which is removed by the complete cutting edge of another cutting edge in subsequent rotational cycles. A cutting linear speed of 160 m / min to 180 m / min provides sufficient cutting temperature to induce chip curling, but not to the point of excessive temperature causing chips to adhere to the cutting edge. During drilling, each chip-breaking groove divides the chip into multiple segments, and each segment immediately detaches from the workpiece surface and is discharged along the chip removal groove without manual intervention, allowing the machining process to continue continuously.

[0050] Furthermore, the workpiece is specifically a thin-walled part made of chromium-zirconium copper material, with a width-to-thickness ratio d / h ≥ 30, where h is the wall thickness and d is the shape dimension perpendicular to the thickness direction of the thin-walled part. A larger width-to-thickness ratio results in weaker rigidity of the thin-walled part, poorer resistance to deformation under cutting forces during drilling, and more prominent issues with tool deflection and burr formation on the hole wall. This also places more stringent requirements on the chip flute layout and process parameters. Actual machining verification shows that under these conditions, using this drill bit and process parameters, the machining efficiency is more than twice that of traditional machining methods, the surface roughness Ra value of the hole wall is no greater than 3.2 micrometers, and the burr height at the bottom of the hole is no greater than 0.1 millimeters. The above roughness and burr height data are derived from actual measurement results during machining verification, using a chromium-zirconium copper thin-walled part as the test condition.

[0051] Furthermore, during one revolution of the drill bit, the three chip-breaking grooves divide the drilling area into five chip segments. The first chip-breaking groove 4, the second chip-breaking groove 5, and the third chip-breaking groove 6 are staggered in both the radial and circumferential directions, and the cutting positions of each chip segment are arranged sequentially in the circumferential direction without overlapping. The fracture surfaces of the five chip segments are staggered sequentially along the circumferential direction, and there is no residual material connection between adjacent fracture surfaces.

[0052] Each chip-breaking groove is positioned differently in both the radial and circumferential directions, and the circumferential angle of the fracture surface produced by each groove on the workpiece is also different. This results in a distribution pattern where the five fracture surfaces are staggered along the circumference and appear one after another. The chip segments are independent of each other, with no residual connections. During chip removal, the segments do not pull on each other, and the chip removal channel remains unobstructed.

[0053] The following combination Figures 1 to 4 The following is a general explanation using a complete drilling process as an example.

[0054] A thin-walled part made of chromium-zirconium-copper alloy is selected. The width-to-thickness ratio d / h of this part is greater than or equal to 30, and a through hole needs to be machined at a predetermined position. The aforementioned drill bit is selected, wherein the first cutting edge 2 has a chip-breaking groove 4, the second cutting edge 3 has a second chip-breaking groove 5 and a third chip-breaking groove 6, and the three chip-breaking grooves are arranged radially in the order of inner, middle and outer. The axial depth of each chip-breaking groove is greater than the feed per revolution. The rake angle γ of the cutting edge is greater than or equal to 30°, the major clearance angle α1 is greater than or equal to 15°, and the minor clearance angle α2 is greater than or equal to 25°. Both cutting edges have eccentricity and overcenter, and they enclose a recessed chip-receiving space at the center of the drill tip.

[0055] Mount the drill bit onto the spindle of the CNC machining center, perform tool setting, and start the spindle. Set the cutting speed to 160 m / min to 180 m / min and the feed per revolution to 0.25 mm / revolution to 0.5 mm / revolution. The drill bit rotates and feeds axially to begin drilling.

[0056] When the drill bit contacts the workpiece surface, the first cutting edge 2 and the second cutting edge 3 participate in cutting simultaneously. The first chip-breaking groove 4 is located at the middle radial position of the first cutting edge 2, which is divided into two cutting edge segments: an inner segment and an outer segment. The second chip-breaking groove 5 and the third chip-breaking groove 6 are located at the inner and outer radial positions of the second cutting edge 3, respectively, which is divided into three cutting edge segments: an inner segment, a middle segment, and an outer segment. Each of the five cutting edge segments independently removes its corresponding annular region.

[0057] During drill bit rotation, the chips generated by each cutting edge segment are separated by adjacent chip-breaking grooves and do not connect with each other. The cross-sectional area of ​​each chip segment tends to be equal, and the bending stiffness is basically the same. After formation, they curl and break immediately. The residual ribs generated by the first chip-breaking groove 4 are removed by the complete cutting edge of the second cutting edge 3 in the next rotation cycle. The residual ribs generated by the second chip-breaking groove 5 and the third chip-breaking groove 6 are removed by the complete cutting edge of the first cutting edge 2, respectively. There is no residual material connecting the segments. After the chips are formed, they enter the chip-receiving space recessed in the center of the drill tip for curling and buffering, and then are discharged along the chip removal grooves without the need for manual chip removal.

[0058] The drill bit continues to feed axially until it penetrates the workpiece. At the exit point of the drill bit's penetration, each chip segment has been pre-divided into independent short segments, with the cut edges of each segment staggered sequentially in the circumferential direction, preventing the formation of continuous burrs at the exit. The hole wall surface is free of scratches, and the dimensional accuracy meets design requirements.

[0059] Actual processing verification showed that using this drill bit and process parameter combination, the single-hole processing time was reduced by more than half compared to traditional methods. During continuous processing, no machine stoppage for chip removal was required, and the processing efficiency was more than twice that of traditional methods. The surface roughness Ra value of the hole wall was no greater than 3.2 micrometers, and the burr height at the bottom of the hole was no greater than 0.1 millimeters. The above data comes from actual processing verification tests under the conditions of a chromium-zirconium copper thin-walled part with a wall thickness of 5mm, a width of 200mm, and a hole diameter of 16mm.

[0060] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this application will not describe the various possible combinations separately.

[0061] Furthermore, various different implementations of this application can be combined in any way, as long as they do not violate the spirit of this application, they should also be regarded as the content disclosed in this application.

Claims

1. A drill bit for drilling thin-walled parts made of highly ductile materials, characterized in that, include: The drill bit body (1) has a first cutting edge (2) and a second cutting edge (3) at its front end, and the first cutting edge (2) and the second cutting edge (3) are distributed along the circumference of the drill bit body (1); The first cutting edge (2) is provided with a first chip-breaking groove (4), and the second cutting edge (3) is provided with a second chip-breaking groove (5) and a third chip-breaking groove (6). From the center of the drill tip outwards, the second chip-breaking groove (5), the first chip-breaking groove (4), and the third chip-breaking groove (6) are arranged in sequence; The axial depth of the first chip groove (4), the second chip groove (5) and the third chip groove (6) is greater than the axial feed per revolution of the drill bit.

2. The drill bit according to claim 1, characterized in that, The second chip-breaking groove (5) and the third chip-breaking groove (6) are located at different radii of the second cutting edge (3).

3. The drill bit according to claim 1, characterized in that, After the first cutting edge (2) rotates 180° around the rotation center of the drill body (1), the first chip groove (4) is not in the same position as the second chip groove (5) and the third chip groove (6) in the circumferential direction.

4. The drill bit according to claim 1, characterized in that, The first chip-breaking groove (4), the second chip-breaking groove (5) and the third chip-breaking groove (6) divide the drilling area into five cutting segments, and the cross-sectional area of ​​each cutting segment tends to be equal.

5. The drill bit according to claim 1, characterized in that, The first cutting edge (2) and the second cutting edge (3) have a rake angle γ that is conducive to chip curling and breaking, and a clearance angle that is conducive to reducing friction between the clearance face and the workpiece; the rake angle γ is ≥30°, and the clearance angle includes a primary clearance angle α1 and a secondary clearance angle α2, wherein the primary clearance angle α1 is ≥15° and the secondary clearance angle α2 is ≥25°.

6. The drill bit according to claim 1, characterized in that, The cutting edges of the first cutting edge (2) and the second cutting edge (3) have an eccentricity L4 and an over-center amount L5 respectively relative to the rotation center of the drill body (1). The cutting edges of each cutting edge do not pass through the rotation center. The rake faces of the two cutting edges are connected in the central area of ​​the drill tip, forming a concave chip-containing space.

7. The drill bit according to claim 1, characterized in that, The high ductility material includes chromium zirconium copper, pure copper, oxygen-free copper, or aluminum alloy; the width-to-thickness ratio d / h of the thin-walled part is ≥30, where h is the wall thickness of the thin-walled part and d is the shape dimension of the thin-walled part perpendicular to the thickness direction.

8. A drilling method for thin-walled parts made of highly ductile materials, characterized in that, Using any one of claims 1 to 7, the drill bit is driven to rotate and feed axially at a cutting speed of 160 m / min to 180 m / min and a feed per revolution of 0.25 mm / r to 0.5 mm / r to perform drilling on the workpiece; During drilling, the uncut residual material at the chip groove of one cutting edge is removed by the complete cutting edge of another cutting edge, and the chips are separated into multiple segments and discharged.

9. The method according to claim 8, characterized in that, The workpiece is a thin-walled part made of chromium zirconium copper material, and the width-to-thickness ratio d / h of the thin-walled part is ≥30, where h is the wall thickness of the thin-walled part and d is the shape dimension of the thin-walled part perpendicular to the thickness direction.

10. The method according to claim 8, characterized in that, The drill bit divides the chips into five chip segments in one rotation. The five chip segments break off sequentially along the circumference, and the fracture surfaces are staggered in the circumferential direction.

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