Drilling tool and drill bit with multiple rake faces thereof

Abstract

The drill bit comprises a handle part and a cutting part connected to one end of the handle part, the cutting part comprises a spiral blade part, one end of the spiral blade part extends from one end of the handle part in the axial direction, an end blade part is formed at the other end of the spiral blade part, the spiral blade part is provided with two spiral grooves, and each spiral groove extends to the end blade part. When the cutting part is driven to cut, formed cuttings are discharged through the spiral groove; a front cutter groove is formed in the position, close to a notch of each spiral groove, of the spiral blade part, two symmetrical rear cutter faces are formed in the direction, far away from the handle part in the axial direction, of the end blade part, one front cutter groove and one rear cutter face intersect to form a set of main cutting edges, and the other front cutter groove and the other rear cutter face intersect to form the other set of main cutting edges; each group of main cutting edges comprises at least n sections of linear or arc sub-cutting edges, and in the n sections of sub-cutting edges, two adjacent sections of sub-cutting edges are not collinear, so that edge intersection points are formed between the two adjacent sections of sub-cutting edges.

Description

Technical Field

[0001] This application relates to the field of cutting components, and more particularly to a drilling tool and its drill bit. Background Technology

[0002] In the processing of metals, wood chips, plastics, etc., it is usually necessary to use tools or equipment, such as hand tools, power tools, or automated machine tools, to drill holes. And these tools or equipment all need to be equipped with drill bits.

[0003] Commonly used drill bits in the prior art, such as the Chinese patent with publication number CN110902259A, are twist drill bits. These twist drill bits typically include a shank and a working section. The outer surface of the working section has a helical chip-breaking groove for diverting and removing chips, which is commonly used for chip removal. The edges of the helical chip-breaking groove form cutting edges to maintain the smoothness and shape of the drill hole during drilling. The helix angle of the helical groove in prior art twist drill bits determines the rake angle and clearance angle of the cutting edge. The steeper the helical groove, the larger the rake angle, but the clearance angle may decrease, requiring adjustment through sharpening to balance cutting performance. Furthermore, the helical groove guides chips out along the groove, reducing friction between chips and the hole wall. However, the helical groove makes the drill core thinner, reducing rigidity and increasing the risk of hole axis misalignment.

[0004] In the prior art, there is also an improved drill bit that forms a helical groove in a single machining step on the rake face near the tip edge. The shape of the main cutting edge of this drill bit is affected by the helical groove and the size of the apex angle. To ensure the tip edge is straight, different apex angle values ​​correspond to different helical groove shapes. For example, with the same groove type, the main cutting edge is straight at one apex angle and concave or convex arcs at other apex angles. Furthermore, the rake angle of this drill bit varies considerably, specifically from a positive rake angle at the outer diameter to a large negative rake angle near the drill core.

[0005] The prior art CN221817428U discloses a double-edged drill bit with a first cutting edge and a second cutting edge. However, the first cutting edge and the second cutting edge are formed by the drill bit at two different tapers, and both use the end of the helical groove as the rake face, that is, the chip removal groove as the rake face.

[0006] In addition, the prior art CN220679467U also discloses a drill bit with a chip breaker groove. The cutting edge has a rake face, a flank face, and a cutting edge formed by the intersection of the rake face and the flank face. However, each main tangential cutting edge has only one rake face. As a result, the rake angle of the drill bit is often fixed. Summary of the Invention

[0007] To solve the above-mentioned technical problems, this application provides a drill bit, the drill bit comprising: Handle; A cutting portion connected to one end of the shank includes a helical cutting edge, wherein one end of the helical cutting edge extends axially from one end of the shank, and the other end of the helical cutting edge forms an end cutting edge. The helical cutting edge has two helical grooves extending axially and centrally symmetrically in the circumferential direction, wherein each helical groove extends to the end cutting edge so that when the cutting portion is driven to cut, the generated chips are discharged through the helical grooves. A sharp cutting edge is formed at the edge of the helical groove to form a secondary cutting edge, and each of the secondary cutting edges has a corresponding independent rake face. The spiral cutting edge forms a front groove near the opening of each spiral groove, and the end cutting edge forms two symmetrical flank faces in the direction away from the shank along the axial direction. One of the front grooves and one of the flank faces intersect to form a set of main cutting edges, and the other front groove and the other flank face intersect to form another set of main cutting edges. Each group of main cutting edges includes at least n straight or curved sub-cutting edges to form a chip breaking groove at the position corresponding to each sub-cutting edge in the rake groove, where n is greater than or equal to 2, and in the n sub-cutting edges, adjacent sub-cutting edges are not collinear but intersect to form a cutting edge intersection point between adjacent sub-cutting edges, wherein the nth sub-cutting edge near the outer edge intersects with the secondary cutting edge.

[0008] According to one embodiment of this application, the main cutting edge is implemented as a series of straight lines, i.e., in a segmented form of broken lines.

[0009] According to one embodiment of this application, each chip breaker groove has a non-groove surface adjacent to the sub-cutting edge and a recessed groove surface between the helical groove and the non-groove surface, wherein the angle between the boundary line between the non-groove surface and the recessed groove surface and the axial direction is between 30° and 60°.

[0010] According to one embodiment of this application, the included angle between two adjacent cutting edges ranges from 140° to 170°.

[0011] According to one embodiment of this application, the position of the intersection point formed by two adjacent sub-cutting edges on each main cutting edge is between the intersection point of the 1 / 4 bisector and the 3 / 4 bisector of the line that intersects the main cutting edge between the two ends of the main cutting edge.

[0012] According to one embodiment of this application, the cutting portion forms two helical grooves from the end of the end blade portion to the helical blade portion, in the helical direction of the helical groove. A cutting band is formed between each helical groove and the corresponding helical groove. The chip breaker groove furthest from the axial direction passes through the cutting band, and after the chip breaker groove furthest from the axial direction passes through the cutting band, the thickness of the cutting band is cut to account for 1 / 3 to 2 / 3 of the entire width of the cutting band.

[0013] According to one embodiment of this application, each of the n-1 chip breaker grooves and the front tool groove has a concave hook groove surface.

[0014] According to one embodiment of this application, the front groove near the axis is implemented as a non-concave groove, and the arc at the junction of the front groove and the spiral groove is tangent to the spiral groove.

[0015] According to one embodiment of this application, a transition groove is also formed between the front groove and the helical groove near the axis, wherein the front groove, the transition groove and the helical groove transition smoothly in sequence.

[0016] According to another aspect of this application, this application provides a drilling tool comprising: Installation structure; As described in any of the above-described drill bits, wherein the shank of the drill bit is mounted on the mounting structure. Attached Figure Description

[0017] Figure 1 A schematic diagram of a drill string according to one embodiment of this application is shown; Figure 2 A perspective view of the drill bit described in this application at one angle is shown; Figure 3 A perspective view of the drill bit described in this application from another angle is shown; Figure 4 A bottom view of the broken cutting edge of the drill bit described in this application is shown; Figure 5 An enlarged view of drill bit A as described in this application is shown; Figure 6 An enlarged view of drill bit B as described in this application is shown; Figure 7 A perspective view of the drill bit described in this application is shown from another angle; Figure 8 This application shows Figure 7 A magnified schematic diagram of a portion of the image. Detailed Implementation

[0018] The following description is intended to disclose this application and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. The basic principles of this application defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of this application.

[0019] Those skilled in the art should understand that, in the disclosure of this application, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on this application.

[0020] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0021] refer to Figure 1-8 A preferred embodiment of the present application of a drilling tool will be described in detail below, wherein the drilling tool includes a drill bit 100 and a mounting body 200 for mounting the drill bit 100.

[0022] In one embodiment, the mounting body 200 is implemented as a main component of a power tool. For example, in one embodiment, the mounting body 200 is implemented as an electrical component with a motor, wherein the drill bit 100 is mounted on the electrical component and is synchronously rotatably connected to the motor.

[0023] In another embodiment, the mounting body 200 is implemented as a part of a machine tool for mounting and securing the drill bit 100.

[0024] Specifically, the drill bit 100 includes a shank 10 and a cutting portion 20 connected to one end of the shank 10. Preferably, one end of the cutting portion 20 extends integrally from one end of the shank 10.

[0025] Preferably, the other end of the shank 10 is provided with a mounting structure that can be mounted to the mounting body 200. In the example shown, the outer wall of the other end of the shank 10 extends at intervals along the circumferential direction of the shank 10 to form a plurality of external slots 101 for mounting to the mounting body 200. Those skilled in the art will understand that the plurality of external slots 101 disrupt the roundness of the cross-section of the shank 10, thereby effectively preventing the drill bit 100 from rotating relative to the mounting body 200 during subsequent operation.

[0026] Those skilled in the art will understand that, since the cutting part 20 is provided with a cutting edge, when it is driven to rotate, the cutting part 20 can cut the target object, such as a wooden object or a metal object, to form a hole of a predetermined shape.

[0027] Specifically, the cutting part 20 includes a helical blade part 21, wherein one end of the helical blade part 21 extends axially from one end of the shank part 10, and the other end of the helical blade part 21 forms an end blade part 22.

[0028] Preferably, one end of the spiral blade 21 extends integrally from one end of the handle 10; in other words, the handle 10 and the cutting part 20 are connected by integral molding.

[0029] The helical cutting edge 21 has two centrally symmetrical helical grooves 2101 extending axially, namely a first helical groove 2101A and a second helical groove 2101B. The first helical groove 2101A and the second helical groove 2101B extend to the end cutting edge 22 so that when the cutting part 20 is driven to perform cutting, the generated chips can be discharged through the first helical groove 2101A and the second helical groove 2101B. In other words, the first helical groove 2101A and the second helical groove 2101B have a chip removal function.

[0030] Preferably, the helical blade 21 forms a sharp cutting edge 2102 at the edges of the first helical groove 2101A and the second helical groove 2101B. Since the cutting edge 2102 is set to be relatively sharp, it can have the same cutting function as a cutting blade. The cutting edge 2102 will form a secondary cutting edge.

[0031] Furthermore, the first spiral groove 2101A and the second spiral groove 2101B respectively form a groove at the end of the end blade portion 22, namely a first groove 2103A and a second groove 2103B.

[0032] More preferably, a front groove 2104 is formed on the spiral cutting edge 21 at the first groove opening 2103A near the first spiral groove 2101A and the second groove opening 2103B near the second spiral groove 2101B, namely the first front groove 2104A and the second front groove 2104B. At the same time, two symmetrical flank surfaces 2201 are formed on the end cutting edge 22 in the direction away from the shank along the axial direction, namely the first flank surface 2201A and the second flank surface 2201B.

[0033] The end-cutting portion 22 also forms a main cutting edge 221 at the intersection of the first rake groove 2104A and the first flank face 2201A, and at the intersection of the second rake groove 2104B and the second flank face 2201B, respectively. The two main cutting edges 221 are centrally symmetrical. Each group of main cutting edges 221 includes at least n straight or curved sub-cutting edges, where the intersection of two adjacent sub-cutting edges forms a cutting edge intersection point. A chip-breaking groove 2105 is also formed at the position corresponding to each sub-cutting edge in the rake groove, where n is greater than or equal to 2. Particularly noteworthy is that when the main cutting edge 221 includes at least n straight or curved sub-cutting edges, a chip-breaking groove 2105 is formed in each rake groove corresponding to each sub-cutting edge, resulting in n-1 chip-breaking grooves 2105. Each chip-breaking groove 2105 forms the rake face of the corresponding sub-cutting edge; in other words, each sub-cutting edge corresponds to one rake face. In this way, by adjusting the angle between the sub-cutting edge near the outermost circle of the center and the axial direction, the rake angle of the outermost circle of the main cutting edge 221 can be adjusted, thereby ensuring the cutting capability of the outermost circle of the main cutting edge 221 while effectively preventing tool breakage.

[0034] Preferably, in one embodiment, all n-1 chip breaker grooves 2105 and the front tool groove have a concave hook groove surface, thereby enabling the n-1 chip breaker grooves 2105 and the front tool groove to have chip breaker function.

[0035] In another embodiment, the front groove near the axis is implemented as a non-concave groove, and the arc at the junction of the front groove and the spiral groove is tangent to the spiral groove. This allows the generated chips to flow smoothly from the first chip-breaking groove 2105 near the axis into the spiral groove, thus improving chip removal. The other n-1 chip-breaking grooves, being recessed, all have chip-breaking functions, effectively breaking the chips and reducing their length.

[0036] In this embodiment, preferably, a transition groove is also formed between the front cutting groove and the spiral groove near the axis, wherein the front cutting groove, the transition groove and the spiral groove transition smoothly in sequence, so that the generated chips can be smoothly discharged into the spiral groove.

[0037] More specifically, in the n-1 chip breaker grooves, each chip breaker groove 2105 has a non-groove surface 21051 adjacent to the sub-cutting edge and a concave groove surface 21052 between the helical groove and the non-groove surface, wherein the angle between the boundary line between the non-groove surface 21051 and the concave groove surface 21052 and the axial direction (e.g., Figure 5 The angles shown for b1 and b2 are between 30° and 60°. If the angle is too large, the area of ​​the non-groove surface 21051 of the chip breaker groove 2105 will be too small, resulting in poor chip removal. If the angle is too small, the secondary cutting edge will be easily cut through.

[0038] In one embodiment, each set of main cutting edges 221 includes a first sub-cutting edge 221A and a second sub-cutting edge 221B, wherein the first sub-cutting edge 221A and the second sub-cutting edge 221B are both formed at the intersection of the first rake groove 2104A and the first flank face 2201A, and the first sub-cutting edge 221A and the second sub-cutting edge 221B intersect to form a cutting edge intersection point.

[0039] It is worth mentioning that the first sub-cutting edge 221A and the second sub-cutting edge 221B can both be curved edges or both be straight edges. Compared with drill bits in the prior art where the main cutting edge is a straight edge, this increases the length of the main cutting edge, thereby reducing the cutting force per unit length of the main cutting edge under the same force.

[0040] More notably, the intersection of the first sub-cutting edge 221A and the second sub-cutting edge 221B to form a cutting edge intersection point can effectively cut the chip, thereby reducing the chip length.

[0041] Preferably, the included angle α between the two non-collinear straight blades is in the range of 140° to 170° (e.g., ...). Figure 4 (As shown). Preferably, by remachining the rake groove, n-1 chip breaker grooves 2105 can be formed within the rake groove. Sub-cutting edges can then be formed at the locations where the corresponding rake groove and chip breaker grooves 2105 intersect with the flank face 2201. By adjusting the shape of the chip breaker grooves 2105, the included angle between two adjacent sub-cutting edges can be adjusted, thereby adjusting the chip flow direction and the magnitude of radial and axial forces.

[0042] It is worth mentioning that the presence of the cutting edge intersection point can play a role in chip breaking. In particular, increasing the number of cutting edge intersection points can effectively improve the distribution of cutting force and extend the service life of the first sub-cutting edge 221A and the second sub-cutting edge 221B.

[0043] Preferably, the position of the intersection point formed by two adjacent sub-cutting edges on each main cutting edge 221 is between the two ends of the main cutting edge 221 (e.g., ...). Figure 4 Between the intersection of the H)4 bisector and the main cutting edge 221 at the 1 / 4 bisector and the 3 / 4 bisector.

[0044] In other words, the intersection point of the cutting edges should not be too close to the two ends of the main cutting edge 221. Otherwise, the chip-breaking ability of the segmented main cutting edge will be weakened.

[0045] It is worth mentioning that the segmented main cutting edge 221 changes the rake angle of the main cutting edge 221 near the center position, so that the rake angle of the main cutting edge 221 near the center position is adjusted to a positive rake angle, thereby improving the cutting performance of the drill bit.

[0046] More importantly, the chip space can be further increased due to the presence of the front tool groove 2104.

[0047] It is worth mentioning that the cutting part 20, from the end of the end blade 22 to the helical blade 21, forms two helical grooves 2106 in the helical direction of the helical groove, wherein a cutting edge 2107 is formed between each helical groove 2106 and the corresponding helical groove. In other words, the cutting part 20 forms two cutting edge edges 2107.

[0048] Preferably, the chip breaker groove 2105 furthest from the axial direction passes through the cutting edge 2107, and after the chip breaker groove 2105 furthest from the axial direction passes through the cutting edge 2107, the thickness (w) of the cutting edge 2107 is cut off to account for 1 / 3 to 2 / 3 of the entire cutting edge width (W). Figure 7 and Figure 8 As shown.

[0049] If the thickness of the cut edge 2107 is too large relative to the entire width of the cutting edge, the remaining width of the cutting edge 2107 will be too small, making the remaining portion of the cutting edge prone to breakage. Conversely, if the thickness of the cut edge 2107 is too small relative to the entire width of the cutting edge, the angle between two adjacent sub-cutting edges will be too large, thus failing to achieve the effect of breaking the chips.

[0050] Those skilled in the art should understand that the embodiments of this application described above and shown in the accompanying drawings are merely examples and do not limit the scope of this application. The advantages of this application have been fully and effectively implemented. The functional and structural principles of this application have been demonstrated and explained in the embodiments, and any variations or modifications can be made to the implementation of this application without departing from the stated principles.

Claims

1. A drill bit, characterized in that, The drill bit includes: Handle; A cutting portion connected to one end of the shank includes a helical cutting edge, wherein one end of the helical cutting edge extends axially from one end of the shank and the other end of the helical cutting edge forms an end cutting edge. The helical cutting edge has two helical grooves extending axially and centrally symmetrically around its circumference, wherein each helical groove extends to the end cutting edge so that when the cutting portion is driven to perform cutting, the generated chips are discharged through the helical grooves, and a sharp cutting edge is formed at the edge of the helical grooves to form a secondary cutting edge. The spiral cutting edge forms a front groove near the opening of each spiral groove, and the end cutting edge forms two symmetrical flank faces in the direction away from the shank along the axial direction. One of the front grooves and one of the flank faces intersect to form a set of main cutting edges, and the other front groove and the other flank face intersect to form another set of main cutting edges. Each group of main cutting edges includes at least n straight or curved sub-cutting edges. A chip breaking groove is formed at the position corresponding to each sub-cutting edge in the rake groove, where n is greater than or equal to 2. Among the n sub-cutting edges, adjacent sub-cutting edges are not collinear but intersect to form a cutting edge intersection point between adjacent sub-cutting edges. The nth sub-cutting edge near the outer edge intersects with the secondary cutting edge. Each sub-cutting edge has an independent rake face.

2. The drill bit according to claim 1, characterized in that, The main cutting edge is implemented as multiple consecutive straight lines, i.e., in a segmented, broken-line form.

3. The drill bit according to claim 1, characterized in that, Each of the chip-breaking grooves has a non-grooving surface adjacent to the sub-cutting edge and a concave groove surface between the helical groove and the non-grooving surface, wherein the angle between the boundary line between the non-grooving surface and the concave groove surface and the axial direction is between 30° and 60°.

4. The drill bit according to any one of claims 2, characterized in that, The included angle between two adjacent cutting edges ranges from 140° to 170°.

5. The drill bit according to claim 4, characterized in that, The position of the intersection point formed by two adjacent sub-cutting edges on each main cutting edge is between the intersection point of the 1 / 4 bisector and the 3 / 4 bisector of the main cutting edge between the two ends of the main cutting edge.

6. The drill bit according to claim 5, characterized in that, The cutting portion extends from the end of the end blade to the helical blade, forming two helical grooves in the helical direction of the helical groove. A cutting band is formed between each helical groove and the corresponding helical groove. The chip-breaking groove furthest from the axial direction passes through the cutting band, and after the chip-breaking groove furthest from the axial direction passes through the cutting band, the thickness of the cutting band is cut to account for 1 / 3 to 2 / 3 of the entire width of the cutting band.

7. The drill bit according to claim 1, characterized in that, Each of the n-1 chip-breaking grooves and the front tool groove has a concave hook groove surface.

8. The drill bit according to claim 1, characterized in that, The front groove near the axis is implemented as a non-concave groove, and the arc at the junction of the front groove and the spiral groove is tangent to the spiral groove.

9. The drill bit according to claim 1, characterized in that, A transition groove is also formed between the front groove and the helical groove near the axis, wherein the front groove, the transition groove and the helical groove transition smoothly in sequence.

10. A drilling tool, characterized in that, The drilling tool includes: Installation structure; The drill bit as described in any one of claims 1-9, wherein the shank of the drill bit is mounted on the mounting structure.

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