Anti-tear drill bit

Abstract

The utility model provides a kind of anti-tearing drilling bit, belong to drilling bit technical field, the anti-tearing drilling bit is used to carry out drilling operation on plate, including drill rod body and drill head, the drill head is connected in the terminal of the drill rod body, the drill head includes central cone tip portion and the helical blade portion being arranged around the central cone tip portion, the helical blade portion is distributed along the axial direction of the drill rod body with helical rising, it is characterized in that, the outer edge of the helical blade portion is provided with multiple buffer teeth, the buffer teeth are spaced distribution along the helical direction of the helical blade portion, the top of the buffer teeth and the cutting edge surface of the helical blade portion form transition camber surface between, the curvature radius of the transition camber surface is the 2~5 times of the buffer tooth height, the buffer tooth is gradually contacted with plate edge in drilling process, for reducing the impact force of plate edge in drilling initial stage.

Description

Technical Field

[0001] This utility model belongs to the field of drilling bit technology, and more specifically, relates to a tear-resistant drilling bit. Background Technology

[0002] In industries such as furniture manufacturing, building decoration, and precision sheet metal processing, drilling various metal sheets is a fundamental and important processing step, used for installing fasteners such as rivets, bolts, hinges, and screws, or for drilling through wiring. Traditional drilling bits typically use a direct cutting method, where the cutting edge of the drill bit makes rigid contact with the edge of the metal sheet, generating instantaneous concentrated pressure and impact force on the sheet surface at the initial stage of drilling. This drilling method is acceptable for non-ferrous metal sheets with good toughness, such as aluminum alloys and copper alloys. However, for hard metal sheets such as stainless steel, titanium alloys, and high-strength steel, due to their dense internal crystal structure and high hardness, the metal grains at the sheet edge are prone to dislocation and microcrack propagation when subjected to the sudden impact of the drill bit, resulting in obvious burrs, flanging, and irregular plastic deformation at the drilled edge. Utility Model Content

[0003] In view of this, the present invention provides a tear-resistant drilling bit, which can solve the problem that when drilling a board, the cutting edge of the drill bit makes direct rigid contact with the edge of the board. In the early stage of drilling, a momentary concentrated impact force is generated on the edge of the board, causing the fiber or granular structure of the board edge to break and tear due to the sudden strong impact. This results in burrs, cracks or irregular damage on the drilled edge, which seriously affects the drilling quality and the subsequent processing and use of the board. The tearing phenomenon is particularly obvious when processing engineered wood products such as MDF and plywood.

[0004] This utility model is implemented as follows:

[0005] This utility model provides a tear-resistant drilling bit for drilling operations on sheet metal. It includes a drill rod body and a drill bit, the drill bit being connected to the end of the drill rod body. The drill bit includes a central cone tip and a spiral cutting edge surrounding the central cone tip. The spiral cutting edge is spirally distributed upwards along the axial direction of the drill rod body. Multiple buffer teeth are provided on the outer edge of the spiral cutting edge, spaced apart along the spiral direction of the spiral cutting edge. A transition arc surface is formed between the tip of each buffer tooth and the cutting edge of the spiral cutting edge. The radius of curvature of the transition arc surface is 2 to 5 times the height of the buffer tooth. During drilling, the buffer teeth make progressive contact with the edge of the sheet metal to reduce the impact force on the edge of the sheet metal during the initial drilling stage.

[0006] The technical effects of the anti-tear drilling bit provided by this utility model are as follows: By setting multiple buffer teeth distributed at intervals along the spiral direction on the outer edge of the spiral cutting edge, and forming a transition arc surface with a specific radius of curvature between the tip of the buffer teeth and the cutting edge of the spiral cutting edge, the buffer teeth make progressive contact with the edge of the plate during the drilling process rather than instantaneous impact contact. This effectively reduces the concentrated impact force of the drill bit on the edge of the plate in the early stage of drilling, avoids tearing of the edge of the plate due to sudden force, ensures the integrity and smoothness of the drilled edge, and improves the drilling quality.

[0007] Based on the above technical solution, the tear-resistant drilling bit of this utility model can be further improved as follows:

[0008] Wherein, the spacing between the buffer teeth along the helical direction of the helical blade is less than the axial distance of the helical blade spiraling up one revolution.

[0009] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by making the spacing of the buffer teeth along the spiral direction of the spiral cutting edge smaller than the axial distance of the spiral cutting edge spiraling up one turn, the number of buffer teeth per unit axial length is increased, so that the edge of the plate can contact the buffer teeth more frequently during the drilling process, further dispersing and mitigating the drilling impact force, making the impact force more evenly distributed in time and space, more effectively preventing the plate edge from tearing due to local stress concentration, and improving the integrity of the drilled edge.

[0010] Furthermore, the cone angle of the central cone tip is 3 to 4 times the angle between the helical cutting edge and the axis of the drill pipe body.

[0011] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by setting the cone angle of the central cone tip to 3 to 4 times the angle between the spiral cutting edge and the axis of the drill rod body, the central cone tip has a larger cone angle, which allows it to contact the plate surface at a gentler angle in the early stage of drilling, reducing the piercing speed of the central cone tip on the plate. Combined with the cutting angle of the spiral cutting edge, a drilling process that gradually progresses from the center to the outer edge is formed, reducing sudden damage to the plate surface and effectively preventing tearing at the beginning of the drilling stage.

[0012] Furthermore, the buffer tooth is in the shape of a triangular truncated pyramid, and the bottom surface of the buffer tooth is smoothly connected to the outer edge surface of the spiral blade.

[0013] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by designing the buffer tooth into a triangular frustum shape and making the bottom surface of the buffer tooth smoothly transition and connect with the outer edge surface of the spiral cutting edge, the buffer tooth has a cross-section that gradually decreases from the bottom to the top. This frustum shape allows the buffer tooth to form a gradual change in contact area when it contacts the edge of the plate, gradually expanding from a small area contact to a larger area contact, further alleviating drilling impact. At the same time, the smooth transition connection avoids stress concentration and enhances the durability of the buffer tooth.

[0014] Furthermore, the helix angle of the spiral cutting edge is 15° to 25°, and the helical direction of the spiral cutting edge is consistent with the rotation direction of the drill rod body.

[0015] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by setting the helix angle of the spiral cutting edge to 15° to 25° and making the spiral direction of the spiral cutting edge consistent with the rotation direction of the drill rod body, within this range of helix angle, it can ensure that the spiral cutting edge has good chip removal capability, so that the chips generated by drilling can be smoothly discharged upward along the spiral cutting edge, avoiding secondary tearing caused by chip accumulation, and also make the spiral cutting edge form a stable cutting motion on the plate during rotation, reducing edge tearing caused by radial runout.

[0016] Furthermore, the transition arc surface is concave, and the transition arc surface forms a smooth curved surface connection with the cutting edge surface of the spiral blade.

[0017] The beneficial effects of adopting the above-mentioned improved scheme are as follows: by designing the transition arc surface as a concave arc and making the transition arc surface and the cutting edge surface of the spiral blade form a smooth curved surface connection, the buffer tooth tip to the cutting edge surface presents a continuous concave curved surface change. This concave arc shape can produce a gentle guiding effect on the edge of the plate during drilling, so that the plate fibers or particles are gradually separated and cut along the concave arc surface direction, avoiding tearing caused by sudden fiber breakage. At the same time, the smooth curved surface connection eliminates stress concentration caused by sharp transition.

[0018] Furthermore, the tip of the central cone is blunt and rounded, and the radius of curvature of the blunt and rounded tip of the central cone is less than 1 / 10 of the diameter of the drill pipe body.

[0019] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by designing the tip of the central cone to be blunt and round, and making the radius of curvature of the blunt round tip less than 1 / 10 of the diameter of the drill rod body, the central cone tip will not make sharp point contact with the plate in the early stage of drilling, but will make contact with the plate with a circular arc surface with a small radius of curvature. This blunt round tip can effectively disperse the concentrated pressure in the early stage of drilling, reduce the puncture impact on the plate, and with an appropriate radius of curvature, it can ensure positioning accuracy and reduce tearing damage to the surface of the plate.

[0020] Furthermore, the height of the buffer tooth gradually decreases along the helical cutting edge from the central cone tip towards the drill pipe body.

[0021] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by making the height of the buffer teeth gradually decrease from the central cone tip to the drill rod body along the spiral cutting edge, a gradient buffer structure is formed. During the drilling process, the higher buffer teeth near the central cone tip first contact the edge of the plate and provide the main buffering effect. Subsequently, the gradually decreasing buffer teeth participate in the buffering in turn, realizing a multi-level buffering effect. This allows the impact force on the edge of the plate to be more fully dispersed in space and time, further improving the tear resistance.

[0022] Furthermore, the drill bit is connected to the drill rod body by a thread, and a tapered transition section is provided at the threaded connection. The tapered angle of the tapered transition section is the same as the tapered angle of the central cone tip.

[0023] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by using a threaded connection between the drill bit and the drill rod body, and setting a tapered transition section at the threaded connection with the same cone angle as the tip of the central cone, a detachable connection structure is formed between the drill bit and the drill rod body, which facilitates the replacement of worn drill bits. At the same time, the setting of the tapered transition section makes the stress distribution at the connection more uniform, avoids the connection from becoming a stress concentration point, enhances the strength and stability of the overall structure, and ensures that the drill bit will not fail due to the breakage of the connection during the drilling process.

[0024] Furthermore, both the drill rod body and the drill head are made of high-speed steel, and the surface of the spiral cutting edge is nitrided.

[0025] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: by using high-speed steel to make the drill rod body and drill bit, and nitriding the surface of the spiral cutting edge, the drill bit has good hardness and wear resistance. The high-speed steel material can withstand the high temperature and stress generated by high-speed rotation and continuous drilling, maintaining the geometric stability of the drill bit. The nitriding treatment forms a hardened layer on the surface of the spiral cutting edge, which significantly improves the wear resistance and service life of the cutting edge, ensuring that the drill bit can still maintain good tear resistance during long-term use.

[0026] Compared with existing technologies, the beneficial effects of this anti-tear drilling bit are as follows: This invention, by setting multiple buffer teeth spaced along the spiral direction on the outer edge of the spiral cutting edge, and forming a transition arc surface with a specific curvature between the buffer teeth and the cutting edge, transforms the drilling process from traditional rigid direct cutting to progressive flexible cutting, effectively reducing the impact force on the edge of the board during the initial drilling stage. By optimizing the spacing, shape, and height gradient distribution of the buffer teeth, a multi-level buffering effect is achieved, fully dispersing the impact force on the edge of the board in both time and space. Simultaneously, by rationally setting the cone angle of the central cone tip, the spiral helix angle of the spiral cutting edge, and adopting a blunt rounded tip design, a smooth progressive cutting motion is formed from the center to the outer edge during the drilling process, avoiding sudden breakage of the board's fiber or granular structure. The overall structural design is scientifically sound, with coordinated cooperation between components, significantly improving the integrity and smoothness of the drilled edge, eliminating burrs and cracks. It is particularly suitable for drilling easily torn engineered wood products such as MDF, plywood, and particleboard, improving product quality and processing efficiency, and reducing board waste and subsequent finishing costs. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of a tear-resistant drilling bit;

[0029] Figure 2 A cross-sectional view of a tear-resistant drilling bit;

[0030] Figure 3 This is a schematic diagram of the bottom of a tear-resistant drilling bit;

[0031] The attached diagram lists the components represented by each number as follows:

[0032] 1. Drill rod body; 2. Drill head; 21. Central cone tip; 22. Spiral cutting edge. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0034] like Figures 1-3The image shows a first embodiment of a tear-resistant drilling bit provided by this utility model. In this embodiment, it is used for drilling operations on a plate. It includes a drill rod body 1 and a drill bit 2. The drill bit is connected to the end of the drill rod body. The drill bit includes a central cone tip 21 and a spiral cutting edge 22 arranged around the central cone tip. The spiral cutting edge is spirally distributed along the axial direction of the drill rod body. The outer edge of the spiral cutting edge is provided with multiple buffer teeth. The buffer teeth are spaced apart along the spiral direction of the spiral cutting edge. A transition arc surface is formed between the top of the buffer teeth and the cutting edge of the spiral cutting edge. The radius of curvature of the transition arc surface is 2 to 5 times the height of the buffer teeth. The buffer teeth make progressive contact with the edge of the plate during the drilling process to reduce the impact force on the edge of the plate in the early stage of drilling.

[0035] In the above technical solution, the spacing between the buffer teeth along the helical direction of the helical blade is less than the axial distance of the helical blade spiraling up one revolution.

[0036] Furthermore, in the above technical solution, the cone angle of the central cone tip is 3 to 4 times the angle between the spiral cutting edge and the axis of the drill pipe body.

[0037] Furthermore, in the above technical solution, the buffer tooth is in the shape of a triangular truncated pyramid, and the bottom surface of the buffer tooth is smoothly connected to the outer edge surface of the spiral blade.

[0038] Furthermore, in the above technical solution, the helix angle of the spiral cutting edge is 15° to 25°, and the spiral direction of the spiral cutting edge is consistent with the rotation direction of the drill pipe body.

[0039] Furthermore, in the above technical solution, the transition arc surface is concave, and the transition arc surface forms a smooth curved surface connection with the cutting edge surface of the helical blade.

[0040] Furthermore, in the above technical solution, the tip of the central cone is blunt and rounded, and the radius of curvature of the blunt and rounded tip of the central cone is less than 1 / 10 of the diameter of the drill pipe body.

[0041] Furthermore, in the above technical solution, the height of the buffer tooth gradually decreases along the helical cutting edge from the central cone tip towards the drill pipe body.

[0042] Furthermore, in the above technical solution, the drill bit and the drill rod body are connected by threads, and a tapered transition section is provided at the threaded connection. The cone angle of the tapered transition section is the same as the cone angle of the central cone tip.

[0043] Furthermore, in the above technical solution, both the drill rod body and the drill bit are made of high-speed steel, and the surface of the spiral cutting edge is nitrided.

[0044] The following is a specific embodiment 1 of this utility model. In this embodiment, the anti-tear drilling bit adopts an integral structural design. The drill rod body is a cylindrical rod with a diameter of 8mm and a length of 120mm, made of high-speed steel that has undergone quenching and tempering, achieving a hardness of HRC62 to HRC65. The drilling bit is connected to the end of the drill rod body via an M8 right-hand thread. A 5mm long tapered transition section with a cone angle of 118° is provided at the threaded connection to ensure uniform stress distribution at the connection. The central cone tip of the drilling bit is conical with a cone angle of 118° and a blunt rounded tip with a radius of curvature of 0.6mm, approximately 1 / 13 of the drill rod body diameter. A helical cutting edge surrounds the central cone tip, spiraling upwards along the axial direction of the drill rod body. The helix angle is 20°, and the helical direction is right-handed, consistent with the rotation direction of the drill rod body. The length of the helical cutting edge is 35mm. Eight buffer teeth are evenly distributed along the spiral direction on the outer edge of the spiral cutting edge. The spiral spacing between two adjacent buffer teeth is 12 mm, which is less than the axial distance of approximately 43 mm for one spiral rotation of the spiral cutting edge. Each buffer tooth is shaped like a triangular truncated pyramid, with a base dimension of 3 mm long and 2 mm wide, a top dimension of 1.5 mm long and 1 mm wide, and a height of 1.2 mm. The height of the buffer teeth near the central cone tip is 1.5 mm, gradually decreasing to 0.9 mm towards the drill pipe body, forming a gradient distribution. The bottom surface of the buffer tooth is connected to the outer edge surface of the spiral cutting edge by a circular arc with a radius of 0.8 mm. A concave arc-shaped transition surface is formed between the tip of the buffer tooth and the cutting edge of the spiral cutting edge, with a radius of curvature of 3 mm, approximately 2.5 times the average height of the buffer tooth (1.2 mm). The surface of the spiral cutting edge undergoes gas nitriding treatment, with a nitriding layer depth of 0.15mm to 0.25mm and a surface hardness of HV900 to HV1100, significantly improving wear resistance. During use, the drill bit is mounted on a bench drill press, with the rotation speed set to 1000 r / min. Drilling is performed on 18mm thick medium-density fiberboard, maintaining a feed rate of 150mm / min. The drilling process is smooth, producing smooth and complete drilled edges without obvious burrs or tears, significantly extending the drill bit's service life.

[0045] The following is another specific embodiment 2 of this utility model. Embodiment 2 is based on Embodiment 1, but the number of buffer teeth on the outer edge of the spiral cutting edge is increased to 12, and the helical spacing between adjacent buffer teeth is reduced to 8mm, making the buffer teeth more densely distributed. Each buffer tooth is changed to a semi-cylindrical shape with a diameter of 2mm and an axial length of 2.5mm. The axis of the semi-cylindrical shape is parallel to the helical direction of the spiral cutting edge. The height of the buffer teeth still adopts a gradient distribution, with the height of the buffer teeth near the central cone tip being 1.8mm, gradually decreasing to 1.0mm towards the drill rod body. The radius of curvature of the transition arc surface is adjusted to 4mm, making the transition smoother. This improvement allows the drill bit to make more frequent progressive contact with the edge of the board during drilling, further reducing the impact force of a single contact. It is particularly suitable for drilling particleboard and plywood with low density or weak interlayer bonding, resulting in a more significant tear-resistant effect and further improving the smoothness and integrity of the drilled hole edge.

[0046] The following is another specific embodiment 3 of this utility model. Embodiment 3 is based on Embodiment 1, but adds a ring-shaped reinforcing rib to the connection area between the central cone tip and the spiral cutting edge. The ring-shaped reinforcing rib is 1.5mm wide and 0.8mm thick, encircling the bottom of the central cone tip to enhance the structural strength of the connection between the central cone tip and the spiral cutting edge. Simultaneously, the connection method between the drill bit and the drill rod body is changed to a double connection structure with a conical surface fit and threaded locking. The taper of the conical surface is 1:10, and the length of the conical surface is 8mm. Axial locking is then achieved through an M8 thread on top of the conical surface connection. This double connection method makes the connection more robust and reliable, capable of withstanding greater drilling torque and axial force. The material of the drill bit and drill rod body is changed to cobalt-containing high-speed steel with a cobalt content of 5%–8%, further improving the material's red hardness and wear resistance. This improvement allows the drill bit to adapt to drilling operations on plates with higher strength and greater thickness, maintaining good tear resistance and service life even under high-efficiency drilling conditions of 1500r / min and feed rate of 200mm / min.

[0047] Specifically, the principle of this invention is as follows: By setting multiple buffer teeth spaced apart along the spiral direction on the outer edge of the spiral cutting edge, the buffer teeth can contact the edge of the plate before the main cutting edge during the rotary drilling process, pre-contacting and pre-pressing the edge of the plate, generating a gradual mechanical effect. The transition arc surface formed between the tip of the buffer tooth and the cutting edge surface makes the contact process present a continuous curved surface change, avoiding sudden rigid collisions. When the buffer tooth contacts the edge of the plate, a small local pressure is initially generated at the contact point. As the drill continues to rotate and feed, the contact area gradually increases, and the pressure distribution gradually diffuses, making the stress field at the edge of the plate gradually distributed rather than concentrated. This gradual contact method gives the internal structure of the plate an adaptation and adjustment process, allowing the adhesive layer and fiber particles to gradually withstand external forces rather than break instantly. At the same time, the buffer teeth are spaced apart along the spiral direction, and multiple buffer teeth contact the edge of the plate in sequence during the drilling process, forming multiple gradual impacts rather than a one-time strong impact, further dispersing and reducing the peak impact force of a single contact. The large cone angle and blunt rounded tip design of the central cone tip allow the material to enter the plate at a gentler angle and with a larger contact area during the initial drilling stage, reducing the puncture speed. Combined with the reasonable helix angle of the spiral blade, a smooth chip removal channel is formed, avoiding secondary tearing caused by chip accumulation. This effectively solves the problem of tearing at the edge of the plate from a mechanical perspective.

[0048] The specific operation or use method of this utility model is as follows: Before use, check whether the threaded connection between the drill bit and the drill rod body is tight, ensuring that the connection is firm and not loose. Then, install the other end of the drill rod body in the chuck of the drilling machine or electric drill and fix it securely. Fix the plate to be drilled on the worktable, ensuring that the plate surface is flat and firmly fixed without shaking. Start the drilling machine or electric drill to make the drill bit reach a suitable speed, generally set between 800 r / min and 1200 r / min, which can be adjusted appropriately according to the material and thickness of the plate. Slowly and vertically align the rotating drill bit with the predetermined drilling position on the plate, so that the blunt rounded tip of the central cone first contacts the plate surface. At this time, a steady feed speed should be maintained to avoid sudden downward pressure. As the drill bit continues to feed, the buffer teeth on the outer edge of the helical cutting edge contact the edge of the plate in sequence, producing a gradual pre-pressure effect, and then the main cutting edge begins to cut the plate. Throughout the drilling process, maintain a constant feed rate and avoid sudden changes in feed speed. When the drill bit is about to penetrate the plate, reduce the feed rate appropriately to prevent tearing of the back of the plate when the drill bit exits. After drilling is complete, slowly lift the drill bit out of the hole, turn off the drilling machine or electric drill, check the quality of the drilled edge, clean the chips from the drill bit and the worktable, and prepare for the next drilling operation.

Claims

1. A tear-resistant drilling bit for drilling holes in sheet metal, comprising a drill rod body and a drill bit, the drill bit being connected to the end of the drill rod body, the drill bit including a central conical tip and a helical cutting edge surrounding the central conical tip, the helical cutting edge being helically distributed upwards along the axial direction of the drill rod body, characterized in that... The outer edge of the spiral cutting edge is provided with multiple buffer teeth, which are distributed at intervals along the spiral direction of the spiral cutting edge. The tip of the buffer tooth forms a transition arc surface with the cutting edge surface of the spiral cutting edge. The radius of curvature of the transition arc surface is 2 to 5 times the height of the buffer tooth. The buffer tooth makes progressive contact with the edge of the plate during drilling, which is used to reduce the impact force on the edge of the plate in the early stage of drilling.

2. The tear-resistant drilling bit according to claim 1, characterized in that, The spacing between the buffer teeth along the helical direction of the helical blade is less than the axial distance of the helical blade spiraling up one revolution.

3. The tear-resistant drilling bit according to claim 2, characterized in that, The cone angle of the central cone tip is 3 to 4 times the angle between the spiral cutting edge and the axis of the drill pipe body.

4. The tear-resistant drilling bit according to claim 3, characterized in that, The buffer tooth is in the shape of a triangular truncated pyramid, and the bottom surface of the buffer tooth is smoothly connected to the outer edge surface of the spiral blade.

5. A tear-resistant drilling bit according to claim 4, characterized in that, The helix angle of the spiral cutting edge is 15° to 25°, and the helical direction of the spiral cutting edge is consistent with the rotation direction of the drill pipe body.

6. A tear-resistant drilling bit according to claim 5, characterized in that, The transition arc surface is concave, and the transition arc surface forms a smooth curved surface connection with the cutting edge surface of the spiral blade.

7. A tear-resistant drilling bit according to claim 6, characterized in that, The tip of the central cone is blunt and rounded, and the radius of curvature of the blunt and rounded tip of the central cone is less than 1 / 10 of the diameter of the drill pipe body.

8. A tear-resistant drilling bit according to claim 7, characterized in that, The height of the buffer tooth gradually decreases along the helical cutting edge from the central cone tip towards the drill pipe body.

9. A tear-resistant drilling bit according to claim 8, characterized in that, The drill bit is connected to the drill rod body by a thread, and a tapered transition section is provided at the threaded connection. The cone angle of the tapered transition section is the same as the cone angle of the central cone tip.

10. A tear-resistant drilling bit according to claim 9, characterized in that, Both the drill rod body and the drill bit are made of high-speed steel, and the surface of the spiral cutting edge is nitrided.

Images