Drilling part for hole machining tool and hole machining tool

Abstract

The present invention relates to a drilling part for a hole drilling tool, the drilling part having at least two chip flutes and a plurality of sides, wherein each side has a plurality of step segment portions, and step segment portions with the same serial number on all sides form a single step segment, and each side further has a transition segment portion, and has a plurality of major cutting edges, a plurality of minor cutting edges, and a plurality of cutting edge tips, wherein at least one step segment is formed as an asymmetric step segment, and the single asymmetric step segment has at least two asymmetric step segment portions separated in the circumferential direction by a chip flute, and the at least two asymmetric step segment portions and the at least two chip flutes correspondingly form at least two asymmetric cutting edge tips, the at least two asymmetric cutting edge tips having different radial distances from an operating rotation axis and being axially offset relative to each other in the direction of the operating rotation axis.

Description

[Technical Field]

[0001] The present invention relates to the field of machining, in particular to a drill part for a hole drilling tool and to a hole drilling tool. [Background technology]

[0002] A multi-tip drilling section is a type of drilling section used for drilling processes, which constitutes a part of the hole-making tool in which the drilling section is located and has multiple cutting edges on each chip flute along the working axis of rotation. For example, a multi-tip drilling section can be used as a drilling section at the front end of a twist drill to perform drilling operations.

[0003] In this regard, the applicant disclosed an efficient twist drill in his prior patent document (WO2017136966A1). Referring to Figures 1a and 1b, the twist drill comprises a shank portion 1 and a working portion 2, the working portion 2 having, at its front end, the multi-tip drilling portion 4 as described above. The drilling portion 4 is formed by a plurality of step segments Tn (n=1, 2, 3, ..., i, ...) whose diameter increases in the direction opposite to the feed direction, each step segment Tn comprising a frustoconical segment 5 followed by a directly adjacent cylindrical segment 6. Two spiral chip flutes 3 extend over the drilling portion 4. Each chip flute 3 intersects with the surface of the frustoconical segment 5 of each step segment Tn to form a major cutting edge 7 and with the surface of the cylindrical segment 6 of each step segment Tn to form a minor cutting edge 8. The major cutting edge 7 and the minor cutting edge 8 of the same step segment Tn, which are formed by intersecting with the same chip discharge flute 3, further intersect to form a cutting edge tip 9. Therefore, multiple step segments Tn form multiple cutting edge tips 9. The multiple cutting edge tips 9 formed by the same chip discharge flute 3 and different step segments Tn are distributed on a tapered spiral line around the operating rotation axis 10 or central axis 10 of the drilling unit 4. For this reason, the above-mentioned drilling unit 4 is called a multi-tip drilling unit 4.

[0004] 1a and 1b, the two main / minor cutting edges 7 / 8, or cutting edge tips 9, formed by the same step segment Ti of the drilling section 4, together with the two chip flutes 3, are symmetrical, or more precisely, rotationally symmetrical, with respect to the operating rotation axis 10 of the drilling section 4. Thus, on the one hand, with reference to the K-direction view of the twist drill as shown in FIG. 1b, the two radii ri, ri (i=1, 2, 3, ...) measured at the two cutting edge tips 9 of the same step segment Ti of the drilling section 4 are equal and are half the diameter di of the step segment Ti, i.e., ri = ri = di / 2. Here, the radii ri, ri of the cutting edge tips 9 can be understood as the distance between the cutting edge tips 9 and the operating rotation axis 10 of the drilling section 4. On the other hand, with reference to FIG. 1a, the axial lengths Li, Li of the two cutting edge tips 9 on the same step segment Ti from the drill point 13 are also equal, i.e., Li = Li (i=1, 2, 3, ...).

[0005] Therefore, in the prior art, two main cutting edges 7 symmetrically distributed 180 degrees in the circumferential direction on every step segment simultaneously participate in cutting, and the two main cutting edges 7 have equal cutting amounts and cutting forces, which tends to cause resonance at the same frequency and period. In addition, there is a problem of large cutting resistance. In particular, in small step segments, the chip discharge flutes 3 are narrow, making it difficult to discharge chips. Summary of the Invention

[0006] Therefore, the present invention provides a drilling part for a hole drilling tool and a hole drilling tool, which can solve at least one of the above-mentioned technical problems existing in the prior art.

[0007] According to one aspect of the present invention, there is provided a drilling part for a hole drilling tool, the drilling part comprising: At least two chip discharge grooves spaced apart in the circumferential direction of the drilling portion; a plurality of sides, each side being defined by two adjacent chip flutes in the circumferential direction, wherein each side comprises a plurality of step segments arranged successively in the feed direction, each step segment comprising a first segment and a second segment immediately adjacent to the first segment, the step segments on each side being numbered serially in the direction opposite to the feed direction, with the step segments with the same serial number on all sides forming a single step segment, and each side further comprising a transition segment after every step segment; a plurality of main cutting edges, wherein the main cutting edges are formed by chip flutes intersecting the first segment and the transition segment of the step segment; a plurality of minor cutting edges, wherein the minor cutting edges are formed by chip flutes that intersect with second segments of the step segment portion; a plurality of cutting edge tips each formed by a major cutting edge intersecting with a minor cutting edge formed by the same chip flute and the same step segment portion; Equipped with At least one of the step segments is configured as an asymmetric step segment, and a single asymmetric step segment has at least two asymmetric step segment portions separated in the circumferential direction by a chip discharge groove, and the at least two asymmetric step segment portions and the at least two chip discharge grooves correspondingly form at least two asymmetric cutting edge tips that are not rotationally symmetric about the operating rotation axis, and therefore the at least two asymmetric cutting edge tips have different radial distances from the operating rotation axis and are axially offset relative to each other in the direction of the operating rotation axis.

[0008] Technical effects that may be provided by the drilling section of the hole-machining tool include, but are not limited to, that the asymmetric step segments of the drilling section may achieve offset cutting, whereby the cutting edges cut asymmetrically rather than simultaneously to create a compound cutting effect, whereby the amount of metal removed is gradually broken down and cut off, thereby making drilling efficient and labor-saving. In addition, because the cutting forces are not distributed strictly symmetrically around the circumference, they do not cause cutting resonances with the same frequency and period.

[0009] Advantageously, the drilling portion is formed as a drilling portion at the most distal end of the hole-drilling tool, wherein a first of the step segments at the most distal end is formed as a drill point segment, a point of the drill point segment that is at the most distal end in the feed direction is formed as a drill point, and asymmetric cutting edge tips on the same asymmetric step segment have different axial distances from the drill point point.

[0010] Advantageously, the cutting edge tips of the drill point segments are configured to be rotationally symmetrical about the working axis of rotation and therefore have the same radial distance from the working axis of rotation and the same axial distance from the drill point.

[0011] Advantageously, at least one step segment of the first few step segments of the drilling section after the drill point segment is configured as an asymmetric step segment. Here, it can be understood that all step segments (including the most advanced drill point segment) are numbered consecutively in the feed direction, and that at least one of the first few step segments of all step segments after the drill point segment is configured as an asymmetric step segment. For example, in a drilling section having five step segments (including the most advanced drill point segment), the "first few number" is (5-1) / 2=2, which means that at least one step segment of the second and third step segments is configured as an asymmetric step segment. In a drilling section having six step segments (including the most advanced drill point segment), the "first few number" is (6-1) / 2=2.5≈3, which means that at least one step segment of the second, third, and fourth step segments is configured as an asymmetric step segment. And so on.

[0012] Advantageously, of the step segments of the drill hole after the drill point segment, at least two directly adjacent step segments of the first few step segments are configured as asymmetric step segments.

[0013] Advantageously, two immediately adjacent step segments directly adjacent to the drill point segment of the drill hole are formed as asymmetric step segments.

[0014] Advantageously, one step segment directly adjacent to the drill point segment of the drill hole is configured as an asymmetric step segment.

[0015] Advantageously, the plurality of side sections each have the same number of step segment portions, wherein at least one step segment of the latter few step segments of the drilling section after the drill point segment is formed as a symmetrical step segment, and the cutting edge tips on the symmetrical step segment are formed to have the same radial distance from the working rotation axis and the same axial distance from the drill point point, where it can be understood that all step segments (including the most distal drill point segment) are numbered consecutively in the opposite direction to the feed direction, and at least one of the latter few step segments of all step segments after the drill point segment is formed as a symmetrical step segment. For example, in the case of a drilling section having five step segments (including the most advanced drill point segment), the "second half number" is (5-1) / 2=2, which means that at least one step segment among the fourth and fifth step segments is formed as a symmetric step segment, and in the case of a drilling section having six step segments (including the most advanced drill point segment), the "second half number" is (6-1) / 2=2.5≈3, which means that at least one step segment among the fourth, fifth and sixth step segments is formed as a symmetric step segment, and so on.

[0016] Advantageously, of the step segments of the drill hole after the drill point segment, at least two directly adjacent step segments of the latter number of step segments are configured as symmetrical step segments.

[0017] Advantageously, of the step segments of the drill hole after the drill point segment, the last two directly adjacent step segments of the latter number of step segments are configured as symmetrical step segments.

[0018] Advantageously, the last step segment of the perforation is configured as a symmetric step segment.

[0019] Advantageously, at least two sides have a different number of step segment portions, and in at least two sides, the cutting edge tip on one step segment portion on one side and the cutting edge tip on one step segment portion on the other side having a different serial number from the one step segment portion on the one side have the same radial distance from the operating rotation axis and are not axially offset relative to each other in the direction of the operating rotation axis.

[0020] Advantageously, the cutting edge tips of the at least two lateral last step segment portions have the same radial distance from the working axis of rotation and are not axially offset relative to one another in the direction of the working axis of rotation.

[0021] Advantageously, these lateral transition segment portions (or the main cutting edges on these transition segment portions, e.g. the front and / or rear ends of the main cutting edges) have the same radial distance from the working rotation axis and are not axially offset relative to each other in the direction of the working rotation axis.

[0022] Advantageously, the first segment is formed as a truncated cone segment and the second segment is formed as a cylindrical segment, or the first segment and / or the second segment are formed as curved segments.

[0023] Advantageously, the number of step segments of the perforation is greater than or equal to three.

[0024] Advantageously, the number of step segments of the perforation is greater than or equal to five.

[0025] Advantageously, the included angle between the main cutting edges of the drill point segments is greater than the cone angle of the conical drilling section.

[0026] Advantageously, the included angle between the main cutting edges of the drill point segments is obtuse and the cone angle of the drilling section is acute.

[0027] Advantageously, the chip flutes are linear or spiral.

[0028] Advantageously, at least one main cutting edge is configured as a multi-segment cutting edge, each segment cutting edge being linear or arc-shaped.

[0029] According to another aspect of the present invention, there is provided a drilling section for a hole drilling tool, the hole drilling tool comprising a shank portion for fixing the hole drilling tool and an operating portion for drilling holes in front of the shank portion, the operating portion having the drilling section according to the present invention at its most distal end.

[0030] Advantageously, the hole-drilling tool is formed as a twist drill, the working part having a guide part adjacent to the shank part and a drilling part adjacent to the guide part in front of the guide part, wherein the chip discharge groove extends over at least a part of the guide part.

[0031] Advantageously, the chip groove extends over the majority of the guide portion.

[0032] Advantageously, the hole-drilling tool is formed as a pagoda drill, the working part comprising a plurality of stepped drilling / reaming parts arranged successively in the feed direction and having increasing diameters, wherein a first drilling part at the most distal end is provided with a drilling section.

[0033] Advantageously, the hole processing tool is formed as an integrated chamfering and drilling drill bit, and the working part has a drilling section at the most distal end of the working part, a stepped hole drilling section behind the drilling section and spaced a certain axial distance from the drilling section for drilling a stepped hole, and a hole chamfering section behind the stepped hole drilling section and spaced a certain axial distance from the stepped hole drilling section for chamfering the drilled stepped hole.

[0034] Advantageously, the hole drilling tool is formed as a compound tap drill bit, the working part having a drilling portion at a most distal end of the working part, a tapping portion after the drilling portion and spaced an axial distance from the drilling portion for tapping the hole, and a hole chamfering portion after the tapping portion and spaced an axial distance from the tapping portion for chamfering the hole.

[0035] Advantageously, the hole-drilling tool is formed as an umbrella-shaped drill bit, the working part having a drilling section at the most distal end and a reaming section immediately adjacent to and behind the drilling section.

[0036] Advantageously, the hole-making tool is formed as a saw drill bit, the working part having a drilling portion at the most distal end and a saw-tooth working part behind the drilling portion and spaced apart from the drilling portion by an axial distance.

[0037] The technical features described above, the technical features described below, and the technical features shown in the drawings may be arbitrarily combined with each other as long as the combined technical features are not contradictory. All technically possible combinations of features are included in the technical content described in this specification.

[0038] The invention will be further explained by way of exemplary embodiments with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0039] [Figure 1a] FIG. 1a shows a schematic side view of a prior art twist drill with a symmetric multi-tip drilling section. [Figure 1b] FIG. 1b shows a schematic view of the twist drill of FIG. 1a viewed in the k direction of FIG. 1a. [Figure 2a] FIG. 2a shows a schematic side view of the use of an asymmetric multi-tip drilling section according to one embodiment of the present invention in a twist drill. [Figure 2b] FIG. 2b shows a schematic view of the twist drill of FIG. 2a viewed in the k direction of FIG. 2a. [Figure 3a]FIG. 3a shows a schematic side view of the use of an asymmetric multi-tip drilling section according to another embodiment of the present invention in a twist drill, with the drilling section being the main focus. [Figure 3b] FIG. 3b shows a schematic view of the twist drill of FIG. 3a viewed in the k direction of FIG. 3a. [Figure 4] FIG. 4 shows a schematic longitudinal cross section of the asymmetric multi-tip perforating section of FIG. 3a. [Figure 5] FIG. 5 shows a schematic longitudinal cross-section of the asymmetric multi-tip drilling section of FIG. 3a, illustrating the combined cutting effect of the asymmetric step segments. [Figure 6] FIG. 6 shows a schematic longitudinal cross section of the asymmetric multi-tip drilling section of FIG. 3a, similarly illustrating the combined cutting effect of the asymmetric step segments. [Figure 7a] Figure 7a shows a schematic longitudinal cross section of an asymmetric multi-tip perforating section according to a further embodiment of the invention. [Figure 7b] FIG. 7b shows a schematic longitudinal cross section of the asymmetric multi-tip drilling section of FIG. 7a, illustrating the combined cutting effect of the asymmetric step segments. [Figure 8] FIG. 8 shows a schematic side view of the use of an asymmetric multi-tip drilling section according to one embodiment of the present invention in a pagoda drill. [Figure 9] FIG. 9 shows a schematic side view of the use of an asymmetric multi-tip drilling section in an integrated chamfering and drilling drill bit according to one embodiment of the present invention. [Figure 10] FIG. 10 shows a schematic side view of the use of an asymmetric multi-tip drilling section in a compound tap drill bit according to one embodiment of the present invention. [Figure 11] FIG. 11 shows a schematic side view of the use of an asymmetric multi-tip drilling section in an umbrella drill bit according to one embodiment of the present invention. [Figure 12] FIG. 12 shows a schematic side view of the use of an asymmetric multi-tip drilling section according to one embodiment of the present invention in a saw drill bit. [Figure 13a] FIG. 13a shows a schematic side view of the use of an asymmetric multi-tip drilling section according to another embodiment of the present invention in a twist drill. [Figure 13b]FIG. 13b shows a detailed view of the asymmetric multi-tip drilling section of the twist drill of FIG. 13a. DETAILED DESCRIPTION OF THE INVENTION

[0040] Exemplary embodiments of an asymmetric (more specifically, rotationally asymmetric) multi-tip drilling unit 4 according to the present invention are described below. In this description, for purposes of explanation only, various systems, structures, and devices are generally illustrated in the drawings, although not all features of actual systems, structures, and devices are described. For example, well-known functions or structures are not described in detail to avoid unnecessary detail that obscures the present invention. Of course, it should be understood that in any practical application, many specific implementation decisions must be made to achieve the specific goals of a developer or user and must comply with system-related and industry-related constraints. These specific goals may vary depending on the actual application. Additionally, it should be understood that, while making such specific implementation decisions can be complex and time-consuming, this is a routine task for those skilled in the art who would benefit from the present invention.

[0041] The terms and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those terms and phrases by those skilled in the art. Consistent use of a term or phrase herein is not intended to imply a particular definition of the term or phrase, i.e., a definition that is different from the ordinary and customary meaning as understood by those skilled in the art. For any term or phrase that is intended to have a special meaning, i.e., a meaning that is different from that understood by those skilled in the art, this special definition will be expressly set forth herein by definition, directly and unambiguously giving the term or phrase a special definition.

[0042] Unless the context otherwise requires, throughout the following description, the word "comprising" and its variations such as "including" are to be interpreted in their open and inclusive sense, i.e., "including but not limited to."

[0043] Exemplary embodiments of an asymmetric multi-tip perforating section 4 according to the present invention and its use will now be described with reference to the schematic Figures 2a to 6. The same reference numerals are used here for components that correspond to components of the embodiment shown in Figures 1a and 1b.

[0044] 2a and 2b show an embodiment of an asymmetric multi-tip drilling section 4 according to the present invention. Here, this drilling section 4 is exemplarily used as a front drilling section 4 of a twist drill for drilling with a twist drill. The twist drill comprises a shank portion 1 and an operating portion 2 connected to the shank portion 1. The operating portion 2 comprises a cylindrical guide portion 11 connected to the shank portion 1 and a conical drilling section 4 connected to the guide portion 11. A chip discharge flute 3 extends over the entire drilling section 4 and partially over the guide portion 11. Here, the chip discharge flute 3 is a spirally extending chip discharge flute 3. In another embodiment, a linear chip discharge flute 3 can also be envisaged. Here, the chip discharge flutes 3 are two in number. In other embodiments, more than two chip discharge flutes 3 (e.g., three, four, ...) can also be envisaged.

[0045] The perforation section 4 comprises a plurality of step segments Tn (n=1, 2, 3, ..., i, ...) whose diameter increases in the direction opposite to the feed direction. Each step segment Tn comprises a truncated cone segment 5 followed by an adjacent cylindrical segment 6. Here, nine step segments are provided, but in other embodiments, a different number of step segments Tn (e.g., two, three, four, five, six, seven, eight, ten, ...) can be envisaged. A step groove 20 having a substantially V-shaped cross section extending in the circumferential direction is formed between two adjacent step segments Tn-1 and Tn-2. Each step groove 20 is defined by the cylindrical segment 6 of the preceding step segment Tn-1 and the truncated cone segment 5 of the following step segment Tn. In another embodiment, the rear cylindrical segment 6 can also be replaced by a truncated cone segment having a smaller cone angle than the truncated cone segment 5. Each chip flute 3 intersects with the surface of the frustoconical segment 5 of each step segment Tn to form a major cutting edge 7, and intersects with the surface of the cylindrical segment 6 of each step segment Tn to form a minor cutting edge 8. Both the major cutting edge 7 and the minor cutting edge 8 of the same step segment Tn, formed by intersecting with the same chip flute 3, further intersect to form a cutting edge tip 9. Thus, multiple step segments Tn form multiple cutting edge tips 9. The multiple cutting edge tips 9 formed by the same chip flute 3 and different step segments Tn are distributed on a tapered spiral line extending around the operating rotation axis 10 of the drilling part 4. For this reason, the drilling part 4 (formed by multiple step segments Tn) is called a multi-tip drilling part 4. The two chip discharge grooves 3, together with the same step segment Tn, each form a pair of a major cutting edge 7 and a minor cutting edge 8, and each pair of a major cutting edge 7 and a minor cutting edge 8 forms a cutting edge tip 9, so that two cutting edge tips 9 distributed in the circumferential direction are formed on the same step segment Tn.

[0046] Regarding the main cutting edges 7, referring to the embodiment shown in Figures 2a and 2b, the main cutting edges 7 on each step segment Tn may be formed to be one-segmental, and this one-segment edge may be linear or arc-shaped. However, in some embodiments not shown, at least one of the main cutting edges 7 may also be formed to be multi-segmental, and each segment may be linear or arc-shaped. The multi-segment main cutting edge 7 may include at least two main cutting edge segments, and an angle (other than 0 degrees and 180 degrees) may be formed between two adjacent main cutting edge segments. Therefore, chips may be further broken down, reducing chip-cutting forces and cutting heat.

[0047] In this embodiment, the first step segment T1 at the tip of the drilling section 4 constitutes the drill point segment T1 with the smallest diameter of the twist drill, and the two main cutting edges 7 of the drill point segment are formed as two linear or straight main cutting edges 7, where the obtuse included angle formed between the two main cutting edges 7 corresponds to the included angle of the main cutting edges of a typical non-multi-step segment twist drill and can be larger than the cone angle α of the entire conical drilling section 4 (see FIG. 2a), where the cone angle α is preferably formed as an acute angle, but the cone angle α can also be formed as a substantially right angle or obtuse angle. In this structure, the small-diameter drill point segment functioning as the first step segment T1 has good centering, and the cylindrical segment 6 of the drill point segment becomes a centering shaft after cutting into the workpiece. In particular, when the asymmetric cutting edges of subsequent step segments Tn (where n>1), having an offset structure as described in more detail below, gradually cut into the workpiece, the cylindrical segment 6 of the drill tip step is sufficient to serve as a centering element, so that the working rotation axis 10 does not shift. As with conventional twist drills, two linear main cutting edges 7, two additional auxiliary edges, and a cross edge 25 on the drill tip segment form the top edges of the drill tip segment. The two linear main cutting edges 7 intersect at both ends of the cross edge 25 at the front end, so that the cross edge 25 is located at the very front end of the drill tip segment.

[0048] Here, the point at the very front end of the drill bit in the feed direction or the direction of the working rotation axis is defined as the drill point point 13, and the drill point point 13 is also the point at the very front or farthest end of the drill point segment of the first stage segment T1. At the start of drilling, the drill point point 13 is the part of the drill bit that first contacts the workpiece. It is considered that the drill point point 13 may be located on the cross edge 25 and may be the intersection of the working rotation axis 10 and the cross edge 25. If the cross edge 25 is a straight edge perpendicular to the working rotation axis 10, any point on the cross edge 25 may be referred to as the drill point point 13.

[0049] The drilling part 4 also includes a transition segment 12 that transitions from the last step segment T9 (more precisely its cylindrical segment 6) to the adjacent part of the drilling tool, here the guide part 11. The transition segment 12 is formed as a truncated cone segment 5 that connects the cylindrical segment 6 of the last step segment T9 with the guide part 11. This transition segment 12 also forms the main cutting edge 7 together with the chip flute 3.

[0050] In the present invention, the substantially conical drilling section 4 is divided into a plurality of substantially arcuate sides by a plurality of chip discharge flutes 3 in the circumferential direction, whereby each side is defined by two adjacent chip discharge flutes 3 in the circumferential direction. Each side of the drilling section 4 comprises a plurality of step segmental parts whose diameter increases in the opposite direction to the feed direction, and each step segmental part correspondingly comprises a truncated cone segmental part 5 and a subsequently adjacent cylindrical segmental part 6. Each side of the drilling section 4 also includes a transition segmental part 12 located last in the feed direction, whereby each transition segmental part 12 is also defined by two adjacent chip discharge flutes 3 in the circumferential direction.

[0051] For ease of explanation and understanding of the present invention, it is defined here that all step segments with the same serial number on each side are still defined as forming a step segment Tn (n=1, 2, 3, ..., i, ..., 9), provided that the step segments on each side are numbered serially in the direction opposite to the feed direction. For example, taking the embodiment shown in Figures 2a and 2b as an example, the perforation 4 is divided into two approximately arc-shaped sides by two chip discharge grooves 3 in the circumferential direction, whereby each side is defined by two chip discharge grooves 3 in the circumferential direction. Each side of the perforation 4 comprises nine step segments whose diameter increases in the direction opposite to the feed direction, and each step segment comprises a truncated conical segment 5 followed by an adjacent cylindrical segment 6. The step segments on the two sides are numbered 1, 2, 3, ..., i, ..., 9 in the direction opposite to the feed direction, and two step segments on the two sides having the same number i are defined as forming one step segment Ti (i = 1, 2, 3, ..., 9), regardless of whether the two step segments having the same number i are rotationally symmetrical to each other about the operating rotation axis. Each side of the drilling section 4 also includes a transition segment 12 located at the end in the feed direction, whereby each transition segment 12 is defined by two adjacent chip flutes 3 in the circumferential direction.

[0052] Referring to Figures 2a and 2b, two step segment portions (which may also be referred to as step segmental halves) of the same step segment T1 (here shown schematically as the third step segment T3) of the drilling section 4, separated by two chip discharge grooves 3, are not symmetrical with respect to the operating rotation axis 10 of the drilling section 4.

[0053] In particular, the radius ri of the cylindrical segment 6 of the step segment portion on the first side (facing into the plane of the paper in FIG. 2a, left side in FIG. 2b) of the asymmetric step segment Ti is greater than the radius ri' of the cylindrical segment 6 of the step segment portion on the second side (facing out of the plane of the paper in FIG. 2a, right side in FIG. 2b) of the step segment Ti, i.e., ri > ri', and the axial length Li of the cylindrical segment 6 (or its front end) of the step segment portion on the first side of the step segment Ti from the drill point point 13 is greater than the axial length Li' of the cylindrical segment 6 (or its front end) of the step segment portion on the second side of the step segment Ti from the drill point point 13, i.e., Li > Li'. In other words, step segment portions with smaller radii within the same step segment are located axially closer to the drill point point 13.

[0054] In other words, the two cutting edge tips 9 formed by the same step segment Ti having two chip flutes 3 are not symmetrical with respect to the operating rotation axis 10 of the drilling part 4. In particular, the radius ri of the cutting edge tip 9 of the step segment portion on the first side of the step segment Ti is greater than the radius ri' of the cutting edge tip 9 of the step segment portion on the second side of the step segment Ti, i.e., ri > ri', and the axial length Li of the cutting edge tip 9 of the step segment portion on the first side of the step segment Ti from the drill point point 13 is greater than the axial length Li' of the cutting edge tip 9 of the step segment portion on the second side of the step segment Ti from the drill point point 13, i.e., Li > Li'.

[0055] 2b, the two radii ri, ri' (where i=3) measured at the two cutting edge tips 9 of the same step segment Ti of the drilling part 4 are therefore not equal and are not equated to half the diameter di' of the step segment Ti, i.e., ri ≠ ri' ≠ di' / 2, but ri + ri' = di'. Here, the radii ri, ri' of the cutting edge tips 9 can be understood as the distance between the cutting edge tips 9 and the working rotation axis 10 of the drilling part 4. On the other hand, referring to FIG. 2a, the axial lengths Li, Li' of the two cutting edge tips 9 on the same step segment Ti from the drill point 13 are also not equal, i.e., Li ≠ Li'.

[0056] This results in the two main cutting edges 7 of the asymmetric step segments Ti, distributed 180 degrees circumferentially on the two chip flutes 3, not simultaneously cutting the same workpiece section, i.e., the two main cutting edges 7 cut consecutively or offset in the axial direction. The main cutting edge 7 closer to the drill point 13 cuts first, followed by the other main cutting edge 7 distributed 180 degrees circumferentially (i.e., the main cutting edge 7 relatively farther away from the drill point 13). This gradually breaks down the remaining metal until a hole of the desired diameter is obtained. Therefore, when drilling a hole, the drill bit with this asymmetric multi-point drilling section 4 has a rational distribution of the remaining cutting metal according to the hole diameter, and the amount of removed metal is gradually broken down and removed, thus avoiding the disadvantages of the symmetric multi-point drilling section 4 shown in FIGS. 1a and 1b, thereby enabling a smoother machining process. At the same time, drilling is more efficient and labor-saving. In addition, due to the presence of the asymmetric step segments Ti, the cutting forces are not distributed strictly symmetrically at 180° on the circumference, and therefore do not cause cutting resonance with the same frequency and period.

[0057] 2a and 2b, only the asymmetrical arrangement of cutting edges on the third step segment T3 of the drilling section 4 is shown, but optionally such an asymmetrical arrangement of cutting edges can also be arranged on another or more step segments Tn, i.e. such an asymmetrical arrangement of cutting edges can be provided on at least one step segment Tn of the drilling section 4.

[0058] Here, for each step segment Tn (n>1) of the drilling section 4 after the drill point segment T1 in the feed direction, the length of the main cutting edge on the small diameter step segment may be shorter than the length of the main cutting edge on the large diameter step segment, but this is not necessary and, quite possibly, in practice the former may be longer than the latter, or the lengths of these main cutting edges may be equal.

[0059] A specific application of the design concept of the present invention will now be explained in more detail with reference to Figures 3a to 6, taking as an example a perforated section 4 having five step segments Tn.

[0060] 1a and 1b, in the prior art, the radii of the cylindrical segments 6 or cutting edges 9 of two step segment portions of the same step segment Ti of a symmetrical multi-tip drilling section 4 are the same and equal to half the corresponding measured / working diameter di, i.e., ri = ri = di / 2. However, with reference to Figures 3a, 3b and 4, the measured radii ri, ri' of the cylindrical segments 6 or cutting edges 9 of two step segment portions of the same step segment Ti (where i = 2, 3) of an asymmetrical multi-tip drilling section 4 according to the present invention are different, and the measured diameter dic of the step segment Ti is equal to the sum of the two radii ri, ri' of the cylindrical segments 6 or cutting edges 9 of the two step segment portions, i.e., dic = ri + ri', where, as can be seen in Figure 4, the measured diameter d2c of the second step segment T2 shown exemplarily is equal to the sum of the two measured radii r2 and r2'. However, the actual working diameter dig of step segment Ti (i.e., the maximum diameter that step segment Ti can cut) is equal to twice the maximum radius max{ri, ri'} of step segment Ti, i.e., dig=2*max{ri, ri'}.

[0061] 1a and 1b, in the prior art, the axial lengths of the cylindrical segments 6 or cutting edge tips 9 of two step segment portions of the same step segment Ti of a symmetrical multi-tip drilling section 4 from the drill point point 13 are the same, i.e., Li = Li'. In this embodiment according to the invention, referring to Fig. 3a, the axial lengths of the cylindrical segments or cutting edge tips 9 of two step segment portions of the same step segment Ti (where i = 2, 3) of the asymmetrical multi-tip drilling section 4 of the invention from the drill point point 13 are not equal, i.e., Li ≠ Li', but there is an axial offset ΔLi, ΔLi = Li - Li'. As exemplarily shown in Fig. 4, ΔL1 = L1' - L1.

[0062] In this embodiment, only the second stage segment T2 and the third stage segment T3 are offset axially and radially, that is, they are arranged asymmetrically with respect to the operating rotation axis 10. On the other hand, the first stage segment T1 functioning as a drill tip segment, the subsequent fourth stage segment T4 and the fifth stage segment T5 are still arranged symmetrically with respect to the operating rotation axis 10. Therefore, the measured diameters d1, d4, and d5 of the first, fourth, and fifth stage segments T1, T4, and T5 are equal to their working diameters, while the measured diameters d2 and d3 of the second and third stage segments T2 and T3 are not equal to their working diameters and are smaller than their working diameters dig (dig = 2 * max{ri, ri'}, where i = 2, 3). The radii of the cylindrical segment 6 or the cutting edge tip 9 on different segment portions of each of the two stage segments T2, T3 are not equal, and the cylindrical segment 6 or the cutting edge tip 9 is axially offset from each other. During operation, these two asymmetric stage segments T2, T3 can preferably be combined to form four working stages T2.1, T2.2, T3.1, T3.2 (that is, combined after multi-edge cutting), which will be described in detail below, for example, with reference to FIG. 5.

[0063] Also, FIG. 4 also shows the respective axial lengths l1, l2, l3, l4, l5 of the segment portions on the first side of each stage segment Tn of the drilling part 4, the respective axial lengths l1', l2', l3', l4', l5' of the segment portions on the second side of each stage segment Tn of the drilling part 4, the measured diameters d1 < d2 < d3 < d4 < d5 of each stage segment Tn, the radius differences δ2, δ3, δ4, δ5, δ2', δ3', δ4', δ5' between the cylindrical segment 6 or the cutting edge tip 9 of the segment portions on the same side of adjacent stage segments Tn, where δ2 < δ2', δ5 = δ5', and the radius differences δ, δ' between the cylindrical segment 6 and the guide portion 11 of each segment portion of the fifth stage segment T5, where δ = δ'.

[0064] 5 and 6, there are shown schematic cross-sectional views of the asymmetric multi-tip drilling section 4 cut in a plane parallel to the working rotation axis 10. Here, it can be seen that the asymmetric second and third stage segments T2, T3 of the drilling section 4 according to the invention are combined in actual operation into a combined cutting effect of four working stage segments T2.1, T2.2, T3.1, T3.2. The terms "upper" and "lower" used below refer to the orientation of the structural features in FIGS. 5 and 6.

[0065] In particular, in the case of the asymmetrically arranged second stage segment T2, the radius r2 of the lower cylindrical segment 6 or cutting edge tip 9 of the second stage segment T2 is smaller than the radius r2' of the upper cylindrical segment 6 or cutting edge tip 9 of the second stage segment T2, and the axial distance from the front end or lower cutting edge tip 9 of the lower cylindrical segment 6 of the second stage segment T2 to the drill point 13 is smaller than the axial distance from the front end or upper cutting edge tip 9 of the upper cylindrical segment 6 of the second stage segment T2 to the drill point 13. Thus, if we assume that the lower cutting edges 7, 8 of the second stage segment T2 are rotated 180° upward about the central axis 10 and the upper cutting edges 7, 8 of the second stage segment T2 are rotated 180° downward about the central axis 10, it can be seen that the lower main cutting edge 7 of the second stage segment T2 is fully involved in cutting, while the upper main cutting edge 7 of the second stage segment T2 is only partially involved in cutting (see in particular the thick dark black lines of the two front folds in the axial direction). Thus, the single second stage segment T2 itself provides the combined cutting effect of the two working stage segments T2.1 and T2.2.

[0066] Similarly, in the case of an asymmetrically positioned third step segment T3, the radius of the lower cylindrical segment 6 or cutting edge tip 9 of the third step segment T3 is smaller than the radius of the upper cylindrical segment 6 or cutting edge tip 9 of the third step segment T3, and the axial distance from the front end or lower cutting edge tip 9 of the lower cylindrical segment 6 below the third step segment T3 to the drill point 13 is smaller than the axial distance from the front end or upper cutting edge tip 9 of the upper cylindrical segment 6 of the third step segment T3 to the drill point 13. Thus, if we assume that the lower cutting edges 7, 8 of the third stage segment T3 are rotated 180° upward about the central axis 10 and the upper cutting edges 7, 8 of the third stage segment T3 are rotated 180° downward about the central axis 10, it can be seen that the lower main cutting edge 7 of the third stage segment T3 is fully involved in cutting, while the upper main cutting edge 7 of the third stage segment T3 is only partially involved in cutting (see in particular the thick dark black lines in the two front axial recesses). Thus, the single third stage segment T3 itself provides the combined cutting effect of the two working stage segments T3.1 and T3.2.

[0067] 5 and 6, this drilling section 4 with five step segments Tn can be decomposed or combined into seven step segments Tn to participate in cutting in actual operation, resulting in two additional working step segments Tn compared to the symmetric drilling section 4 with five step segments Tn. The four working step segments T2.1, T2.2, T3.1, and T3.2 formed by combining the asymmetric second step segment T2 and the asymmetric third step segment T3 are also asymmetric in measured dimensions, and their working diameters d2.1, d2.2, d3.1, and d3.2 are different from the measured diameters. These working diameters d2.1, d2.2, d3.1, and d3.2 are twice the maximum of the two radii (ri or ri') of the working step segments T2.1, T2.2, T3.1, and T3.2, respectively, i.e., 2 × max{ri, ri'}. In this regard, reference can be made to the annotation of the third working stage segment T2.2 in Figures 5 and 6. Its measured diameter is the sum of r2 and r2' but is smaller than its working diameter d2.2 = 2 x r2'.

[0068] In this embodiment, the measured diameter d1 of the symmetric first step segment T1, the measured diameter d4 of the symmetric fourth step segment T4, and the measured diameter d5 of the symmetric fifth step segment T5 are the actual working diameters of those step segments.

[0069] As can be seen from Figures 5 and 6, the working diameters d1, d2.1, d2.2, d3.1, d3.2, d4, d5 of the seven working stage segments Tn are increased and are smaller than the diameter d of the adjacent part of the hole-drilling tool, here the guide part 11. The axial distances lg1, lg2.1, lg2.2, lg3.1, lg3.2, lg4, and lg5 from the rear end of the cylindrical segment 6 of the seven working stage segments Tn to the drill tip point 13 are increased.

[0070] As can be seen from Figures 5 and 6, the cutting edge tips 9 of the first step segment T1 and the fourth and fifth step segments T4 and T5 are distributed symmetrically with respect to the working rotation axis 10, i.e. the cutting edge tips 9 on the same step segment T4, T5 not only have the same radius but also have the same axial distance to the drill point 13 or are not axially offset.

[0071] In this overall structure, the small-diameter drill point segment serving as the first step segment T1 has good centering properties, and the drill point segment becomes a centering shaft after cutting into the workpiece. Furthermore, the radial distance (cutting radius) between the cutting edges of the second and third step segments T2 and T3 and the rotary shaft 10 is small, i.e., the cantilever amount is small, so the force to be borne is small. Therefore, the asymmetric structure of the second and third step segments T2 and T3 does not generate a large eccentric force in the drilling section 4. Therefore, when the asymmetric cutting edges with offset structures of the subsequent second and third step segments T2 and T3 gradually cut into the workpiece, the first step segment T1 is sufficient to play a centering role, so that the working rotary shaft 10 does not shift. On the other hand, the radial distance (cutting radius) between the cutting edges of the fourth and fifth step segments T4 and T5 and the shaft is large, i.e., the cantilever amount is large, so the force to be borne is large. Therefore, the cutting edges (or cutting edge tips 9) are designed to be symmetrically distributed, so that the main cutting edges 7 bearing large cutting forces can be balanced during radial cutting, thereby balanced cutting of the entire drilling section 4, stabilizing the working rotation axis 10 during drilling, preventing deviation of the working rotation axis 10, and ensuring the diameter accuracy of the final hole. In addition, after the entire drilling section 4 has completely cut into the workpiece to be machined, the cutting edges of all step segments Tn act simultaneously, and the overall cutting force is not strictly distributed symmetrically around 180° on the circumference, so cutting resonance does not occur at the same frequency and period.

[0072] Also, because the cutting edges of the asymmetric step segments T2, T3 of the asymmetric multi-tip drilling section 4 are axially offset, the remaining metal to be cut is again broken down and refined in the actual cutting operation. In this embodiment, each of the five step segments Tn has two step segment parts, and when both step segment parts enter the work (rotation), the effect of a machined (cut) seven-step hole is achieved, so that the actual number of cutting edges of the tool during machining (cutting) (7 steps) is greater than the number of cutting edges of the tool itself (5 steps).

[0073] Referring to Figure 6, due to the axial offset structure of the asymmetric stage segments T2 and T3, the axial distances between adjacent pairs of main and minor cutting edges on the same chip flute 3 and the drill point 13 have a distance difference Δl2 = lg3.1 - lg2.1 (i.e., the distance difference between pairs of main and minor cutting edges on the second working stage segment T2.1 and the fourth working stage segment T3.1), and Δl3 = lg3.2 - lg2.2 (i.e., the distance difference between pairs of main and minor cutting edges on the third working stage segment T2.2 and the fifth working stage segment T3.2). This difference is much larger than the distance differences Δl2'=lg2.2-lg2.1 and Δl3'=lg3.1-lg2.2 between adjacent major and minor cutting edges on the same chip flute 3 and the drill point 13 in the symmetrically distributed step structure of the symmetric multi-tip drilling section 4, i.e., ΔL2=lg3.1-lg2.1 is much larger than ΔL2'=lg2.2-lg2.1, and Δl3=lg3.2-lg2.2 is much larger than ΔL3'=lg3.1-lg2.2. This increases the chip evacuation space between adjacent pairs of cutting edges on the chip flutes 3 on the same side, thereby making chip evacuation smoother. In particular, in the case of the cutting edges of the small diameter step segment Tn, the cutting linear speed is low, the chip discharge speed is also low, and the width of the chip discharge flute 3 is narrow due to the small diameter, so it is relatively difficult for the cutting edges of the small diameter step segment Tn to discharge chips. However, the axial offset structure of the asymmetric multi-tip drilling section 4 according to the present invention increases the chip discharge space between adjacent pairs of cutting edges on the same chip discharge flute 3, thereby improving the chip discharge performance of the cutting edges of the small diameter step.

[0074] Referring to Figures 7a and 7b, there are shown schematic longitudinal cross-sectional views of an asymmetric multi-tip perforating section 4 according to a further embodiment of the present invention.

[0075] In this embodiment, the drilling section 4 is divided into two lateral parts in the circumferential direction by two chip flutes 3. Unlike the above-mentioned embodiment, in this embodiment the upper side of the drilling section 4 comprises three step segment parts T1, T2, T3 with diameters increasing against the feed direction and a transition segment 12, while the lower side of the drilling section 4 comprises four step segment parts T1, T2, T3, T4 with diameters increasing against the feed direction and a transition segment 12.

[0076] All step segment portions with the same serial number are still defined as forming a step segment Tn (n=1, 2, 3, 4), the step segment portions on each side being numbered in the opposite direction to the feed direction. In particular, the first, second and third step segment portions T1, T2 and T3 in the upper feed direction and the first, second and third step segment portions T1, T2 and T3 in the lower feed direction form the first, second and third step segments T1, T2 and T3, respectively, while the fourth step segment portion T4 in the lower feed direction forms itself the fourth step segment T4.

[0077] 7a and 7b, the two step segment portions of the second step segment T2 and the two step segment portions of the third step segment T3 of the perforation section 4 are not symmetrical with respect to the working axis of rotation 10.

[0078] In particular, the radii (or radial distances from the working rotation axis 10) of the cylindrical segments 6 of the upper step segment portions of the second and third step segments T2 and T3 are greater than the radii (or radial distances from the working rotation axis 10) of the cylindrical segments 6 of the lower step segment portions of the second and third step segments T2 and T3, respectively, and the axial lengths of the cutting edge tips 9 of the upper step segment portions of the second and third step segments T2 and T3 from the drill point point 13 are greater than the axial lengths of the cutting edge tips 9 of the lower step segment portions of the second and third step segments T2 and T3 from the drill point point 13. That is, step segment portions with smaller radii within the same step segment are located axially closer to the drill point 13.

[0079] Figure 7b shows the combined cutting effect of the asymmetric second and third stage segments T2 and T3, respectively, where in actual operation one can see the combined cutting effect of the asymmetric second and third stage segments T2, T3 compounding into four working stage segments T2.1, T2.2, T3.1, T3.2.

[0080] Here, the cutting edge tip 9 of the working stage segment T3.2 is symmetrical to the cutting edge tip 9 of the lower fourth stage segment T4 or fourth stage segment part T4. Therefore, the cooperation between the symmetrically arranged working stage segment T3.2 and the fourth stage segment T4 or fourth stage segment part T4 can maintain the centering function of the drilling part 4 after it has entered the workpiece.

[0081] FIG. 8 shows a schematic side view of the use of an asymmetric multi-tip drilling section 4 according to one embodiment of the present invention in a pagoda drill. The pagoda drill has a shank portion 1 for fixing the pagoda drill and a working portion 2 for drilling holes adjacent to the shank portion 1. The working portion 2 includes multiple stepped drilling / reaming sections 30 arranged successively in the feed direction and having increasing diameters. Each drilling / reaming section 30 can drill / reamer a hole having the same diameter as its cylindrical segment in a thin metal plate, such as a steel plate. Generally, the first step at the front of the working portion 2 can be referred to as the drilling section, and the next step can be referred to as the reaming section 30. The tip of the working portion 2, i.e., the front end of the first drilling section, located far from the shank portion 1, is formed as an asymmetric multi-tip drilling section 4 according to the present invention. That is, the first drilling section 30 at the forefront of the working portion 2 includes a drilling section 4 according to the present invention and a cylindrical segment 40 adjacent to the drilling section 4. The cylindrical segment 40 defines a hole with the smallest diameter that can be drilled, for example, by a pagoda drill. Furthermore, it can be seen that a spiral chip flute 3 extends longitudinally over the entire working part 2.

[0082] 9 shows a schematic side view of an asymmetric multi-tip drilling section according to one embodiment of the present invention in an integrated chamfering and drilling drill bit. The integrated chamfering and drilling drill bit has a shank portion 1 for fixing the integrated chamfering and drilling drill bit and a working portion 2 for drilling holes adjacent to the shank portion 1. The working portion 2 has an asymmetric multi-tip drilling section 4 according to the present invention at its most distal end, a stepped hole drilling section 50 for drilling a stepped hole, which is located after the drilling section and spaced a certain axial distance from the drilling section, and a hole chamfering section 60 for chamfering the drilled stepped hole, which is located after the stepped hole drilling section 50 and spaced a certain axial distance from the stepped hole drilling section 50. Here, the chip discharge flute 3 extends continuously through the multi-tip drilling section 4, the stepped hole drilling section 50, and the hole chamfering section 60.

[0083] 10 shows a schematic side view of the use of an asymmetric multi-tip drilling section 4 according to one embodiment of the present invention in a compound tap drill bit. The compound tap drill bit comprises a shank portion 1 for fixing the compound tap drill bit and a working portion 2 for drilling a hole adjacent to the shank portion 1. The working portion 2 comprises an asymmetric multi-tip drilling section 4 according to the present invention at its most distal end, a tapping portion 70 for tapping a hole, which is located after the drilling portion 4 and spaced a certain axial distance from the drilling portion 4, and a hole chamfering portion 80, which is located after the tapping portion 70 and spaced a certain axial distance from the tapping portion 70, for chamfering the hole. Here, the chip flute 3 extends continuously through the multi-tip drilling section 4, the tapping portion 70, and the hole chamfering portion 80.

[0084] FIG. 11 shows a schematic side view of an umbrella-shaped drill bit using an asymmetric multi-tip drilling section 4 according to one embodiment of the present invention. The umbrella-shaped drill bit includes a shank portion 1 for securing the umbrella-shaped drill bit and a working portion 2 for drilling holes adjacent to the shank portion 1. The working portion 2 includes an asymmetric multi-tip drilling section 4 according to the present invention at its most distal end, and a reaming section 90 behind the drilling section 4 and immediately adjacent to the drilling section 4. The reaming section 90, configured to ream a hole to a required diameter, is used for drilling thin plates. Based on the asymmetric multi-tip drilling section 4 of the present invention, the umbrella-shaped drill bit can efficiently penetrate the workpiece and ultimately complete the drilling of the hole. Here, the chip discharge flutes 3 extend continuously through the multi-tip drilling section 4 and the reaming section 90.

[0085] 12 shows a schematic side view of the use of an asymmetric multi-tip drilling section 4 according to one embodiment of the present invention in a saw drill bit. The saw drill bit comprises a shank portion 1 for securing the saw drill bit and a working portion 2 for drilling holes adjacent to the shank portion 1. The working portion 2 comprises an asymmetric multi-tip drilling section 4 according to the present invention at its most distal end and a serrated working portion 100 behind the drilling section 4 and spaced a certain axial distance from the drilling section 4. The serrated working portion 100 is configured to cut transversely to cut a desired shape into a thin plate.

[0086] 13a shows a schematic side view of the use of an asymmetric multi-tip drilling section according to another embodiment of the present invention in a twist drill. The twist drill comprises a shank portion 1 for securing the twist drill and a working portion 2 for drilling holes adjacent to the shank portion 1. The working portion 2 comprises a guide portion adjacent to the shank portion 1 and an asymmetric multi-tip drilling section 4 according to an embodiment of the present invention in front of and adjacent to the guide portion. Here, a chip flute 3 extends over at least a portion of the working portion 2.

[0087] Figure 13b shows a detailed view of the asymmetric multi-tip drilling section of the twist drill of Figure 13a. Unlike the previous embodiment, each step segment portion has two curved segments, so that each cutting edge (major cutting edge 5 and minor cutting edge 6) is configured in an arc shape. Also visible is the asymmetric cutting edge tip 9, major cutting edge 5, and minor cutting edge 6 located on the second step segment. However, the cutting edge tip 9 of the drill point segment at the very tip and the final transition segment 12 are symmetrical.

[0088] It is also conceivable to apply this asymmetric multi-tip drilling section 4 to other hole-making drill bits for other hole-making combinations.

[0089] Referring to the above description of the embodiments of the present invention, the features or advantageous technical effects of the asymmetric multi-tip perforating section 4 of the present invention include, but are not limited to, the following: 1) The simultaneous and symmetrical cutting of the symmetrical cutting edges of the symmetrical multi-tip drilling section 4 is changed to staggered cutting, so that the cutting edges cut asynchronously and asymmetrically to form a compound cutting effect. 2) The resonance problem at the same frequency caused by the symmetrically distributed cutting force of the symmetric multi-tip drilling section 4 is improved, thereby stabilizing the cutting of the tool and extending the service life of the tool. 3) Compared with a symmetrical multi-tip drilling section 4 having the same number of step segments Tn, the number of step segments Tn involved in the actual cutting is increased, the metal cutting residue is refined and dispersed, and the power of the power tool, especially the physical strength and efficiency during hand-held processing, is reduced. 4) The axial offset structure allows adjacent cutting edges on the same side to have a longer space in the axial direction, which increases the chip acceptance rate and makes chip evacuation smoother. Particularly in small diameter stages, the chip evacuation groove 3 is narrow and is unfavorable for chip evacuation, but the offset arrangement of the cutting edges increases the distance between adjacent cutting edges on the same side, thus obtaining a larger chip acceptance space and being more favorable for chip evacuation. 5) The cutting edges in the larger diameter stages are arranged symmetrically, so that the main cutting edge 7, which bears the larger cutting force, is balanced in radial cutting, stabilizing the working rotary axis 10 during drilling, preventing the hole from misaligning, and ensuring the diameter accuracy of the hole.

[0090] The distinctive feature of the asymmetric multi-tip drilling section 4 according to the present invention is that at least one symmetric cutting edge in the prior art is changed to an offset structure cutting edge, thereby bringing about beneficial effects which further include: 1) Throughout the cutting process, the cutting force is small, uniform and appropriate, and chips are discharged smoothly. 2) The manual handheld power tool having the asymmetric multi-tip drilling portion 4 is stable, consumes less power, and can be operated for a long time. 4) The cutting edges of the individual step segments Tn of the tool wear uniformly, thereby extending the service life of the tool. 5) Unnecessary damage to tools during use and rejected work pieces are reduced. 6) The difficulty and cost of processing are reduced, and processing efficiency is improved. 7) Stable and smooth cutting.

[0091] The present invention may include any feature or combination of features, or the general concept thereof, implicitly or explicitly disclosed herein, and is not limited to any defined scope as recited above. Any of the elements, features, and / or structural arrangements described herein may be combined in any suitable manner.

[0092] It will be apparent to those skilled in the art having the benefit of the teachings herein that the particular embodiments disclosed above are illustrative only, and that the invention may be modified and practiced in different but equivalent manners. It is therefore evident that changes and modifications may be made to the particular embodiments disclosed above and all such variations are considered to be within the scope and spirit of the invention.

Claims

1. A drilling part for a hole drilling tool, the drilling part comprising: At least two chip discharge grooves spaced apart in the circumferential direction of the drilling portion; a plurality of sides, each side being defined by two adjacent chip flutes in the circumferential direction, and wherein each side comprises a plurality of step segment portions arranged successively in the feed direction, each step segment portion comprising a first segment and a second segment immediately adjacent to the first segment, with the step segment portions on each side being numbered serially in the opposite direction to the feed direction, and the step segment portions with the same serial number on all sides forming a single step segment, and each side further comprising a transition segment portion after all the step segment portions; a plurality of main cutting edges, wherein the main cutting edges are formed by chip flutes that intersect the first segment and the transition segment of the step segment; a plurality of minor cutting edges, wherein the minor cutting edges are formed by chip flutes that intersect with the second segments of the step segment portion; a plurality of cutting edge tips each formed by the major cutting edge intersecting the minor cutting edge, the major cutting edge being formed by the same chip flute and the same step segment portion; Equipped with wherein at least one of the step segments is formed as an asymmetric step segment, a single asymmetric step segment having at least two asymmetric step segment portions separated in the circumferential direction by the chip discharge grooves, the at least two asymmetric step segment portions and the at least two chip discharge grooves correspondingly forming at least two asymmetric cutting edge tips that are not rotationally symmetric about the working rotation axis, and thus the at least two asymmetric cutting edge tips have different radial distances from the working rotation axis and are axially offset relative to each other in the direction of the working rotation axis.

2. 2. The drilling section according to claim 1, wherein the drilling section is formed as a drilling section at a front end of the hole-drilling tool, wherein a first step segment among the step segments at the front end is formed as a drill point segment, a point of the drill point segment at the front end in the feed direction is formed as a drill point, and asymmetric cutting edge tips on the same asymmetric step segment have different axial distances from the drill point point.

3. 3. The drilling section according to claim 2, characterized in that the cutting edge tips of the drill point segments are formed to be rotationally symmetric about the working axis of rotation and therefore have the same radial distance from the working axis of rotation and the same axial distance from the drill point.

4. The drilling section according to claim 3, characterized in that at least one step segment of the first half of the step segments of the drilling section after the drill point segment is formed as an asymmetric step segment.

5. 5. The drilling section according to claim 4, characterized in that, of the step segments of the drilling section after the drill point segment, at least two immediately adjacent step segments of the first half number of step segments are formed as asymmetric step segments.

6. 6. The drilling section according to claim 5, wherein two immediately adjacent step segments immediately adjacent to the drill point segment of the drilling section are formed as asymmetric step segments.

7. The drilling section of claim 4, wherein the step segment immediately adjacent the drill point segment of the drilling section is formed as an asymmetric step segment.

8. 4. The drilling section according to claim 3, wherein the plurality of side sections each have the same number of step segment portions, and wherein at least one step segment in the latter few step segments of the drilling section after the drill point segment is formed as a symmetrical step segment, and the cutting edge tips on the symmetrical step segment are formed to have the same radial distance from the operating rotation axis and the same axial distance from the drill point point.

9. 9. The drilling section according to claim 8, characterized in that, of the step segments of the drilling section after the drill point segment, at least two directly adjacent step segments of the latter number of step segments are formed as symmetrical step segments.

10. 10. The drilling section according to claim 9, characterized in that of the step segments of the drilling section after the drill point segment, the last two directly adjacent step segments of the latter number of step segments are formed as symmetrical step segments.

11. 9. The perforation according to claim 8, wherein the last step segment of the perforation is formed as an asymmetric step segment.

12. 2. The drilling section according to claim 1, characterized in that at least two sides have a different number of step segment portions, and in the at least two sides, the cutting edge tip on one step segment portion on one side and the cutting edge tip on one step segment portion on another side having a different serial number from the one step segment portion on the one side have the same radial distance from the working rotation axis and are not axially offset relative to each other in the direction of the working rotation axis.

13. 13. The drilling section according to claim 12, characterized in that the cutting edge tips of the last step segment portions of the at least two sides have the same radial distance from the working rotation axis and are not axially offset relative to each other in the direction of the working rotation axis.

14. 2. The perforation section according to claim 1, characterized in that the transition segment portions of the sides have the same radial distance from the working axis of rotation and are not axially offset relative to one another in the direction of the working axis of rotation.

15. 2. The perforation section according to claim 1, characterized in that the first segment is formed as a truncated cone segment and the second segment is formed as a cylindrical segment, or the first segment and / or the second segment are formed as curved segments.

16. The perforation section according to claim 1 , wherein the number of step segments of the perforation section is three or more.

17. 17. The perforation of claim 16, wherein the number of step segments of the perforation is five or greater.

18. The drilling section of claim 2 , wherein the included angle between the main cutting edges of the drill point segments is greater than the cone angle of the conical drilling section.

19. 20. The drilling part of claim 18, wherein the included angle between the major cutting edges of the drill point segments is obtuse and the cone angle of the drilling part is acute.

20. The drilling section according to claim 1 , characterized in that the chip discharge grooves are linear or spiral.

21. 2. The drilling part according to claim 1, wherein at least one main cutting edge is formed as a multi-segment cutting edge, each segment cutting edge being linear or arc-shaped.

22. A hole drilling tool comprising a shank portion for fixing the hole drilling tool and an operating portion for hole drilling in front of the shank portion, the operating portion having the boring portion according to any one of claims 1 to 21 at the tip end of the operating portion.

23. 23. The hole drilling tool according to claim 22, wherein the hole drilling tool is formed as a twist drill, the working part having a guide part adjacent to the shank part and the drilling part adjacent to and in front of the guide part, and wherein the chip flute extends over at least a part of the guide part.

24. 24. A hole-drilling tool according to claim 23, characterized in that the chip flute extends over the majority of the guide portion.

25. 23. The hole drilling tool according to claim 22, characterized in that the hole drilling tool is formed as a pagoda drill, the working part comprising a plurality of stepped drilling / reaming parts arranged successively in the feed direction and having increasing diameters, wherein a first drilling part at the most distal end is provided with the drilling portion.

26. 23. The hole drilling tool according to claim 22, wherein the hole drilling tool is formed as an integrated chamfering and drilling drill bit, and the working part has: the drilling portion at the most forward end; a stepped hole drilling portion after the drilling portion and spaced a certain axial distance from the drilling portion for drilling a stepped hole; and a hole chamfering portion after the stepped hole drilling portion and spaced a certain axial distance from the stepped hole drilling portion for chamfering the drilled stepped hole.

27. 23. The hole drilling tool according to claim 22, wherein the hole drilling tool is formed as a compound tap drill bit, the working portion having: the drilling portion at the most distal end of the working portion; a tapping portion after the drilling portion and spaced an axial distance from the drilling portion for tapping the hole; and a hole chamfering portion after the tapping portion and spaced an axial distance from the tapping portion for chamfering the hole.

28. 23. The hole drilling tool according to claim 22, characterized in that the hole drilling tool is formed as an umbrella-shaped drill bit, the working part having the drilling portion at the most distal end and a reaming portion immediately adjacent to and behind the drilling portion.

29. 23. The hole drilling tool according to claim 22, characterized in that the hole drilling tool is formed as a saw drill bit, the working part having the perforating portion at the most distal end and a saw-tooth working part behind the perforating portion and spaced an axial distance from the perforating portion.

Images