Drilling portion for a hole machining tool and hole machining tool

Abstract

The present application relates to a drill bit for a hole machining tool, characterized in that the drill bit comprises: at least two flutes; a plurality of flanks, each flank comprising a plurality of step segment portions, all step segment portions of the same step segment number of all flanks forming one step segment, each flank further comprising a transition segment portion; a plurality of main cutting edges; a plurality of minor cutting edges; and a plurality of tip points, wherein at least one step segment is configured as an asymmetric step segment, the same asymmetric step segment having at least two asymmetric step segment portions separated by a flute in a circumferential direction, the at least two asymmetric step segment portions corresponding to the at least two flutes forming at least two asymmetric tip points, the at least two asymmetric tip points having different radial distances from a working rotational axis and being arranged axially offset in a direction of the working rotational axis with respect to each other. The present application also relates to a hole machining tool.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of machining, in particular to a drill point for a hole machining tool and a hole machining tool. BACKGROUND

[0002] A multi-point drill point is a drill point for drilling machining, which forms part of a hole machining tool and has multiple points on each flute in the direction of the working rotational axis. For example, a multi-point drill point can be used as the drill point at the front end of a twist drill to undertake the drilling task.

[0003] In this regard, the applicant discloses a high-efficiency twist drill in its prior patent document (WO2017136966A1). See Figure 1a and Figure 1b The twist drill includes a shank 1 and a working portion 2, and the working portion 2 has the above-mentioned multi-point drill point 4 at the front end. The drill point 4 is formed by multiple stepped segments Tn (n = 1, 2, 3, …, i, …) with diameters increasing in the direction opposite to the feed direction, and each stepped segment Tn includes a frustoconical segment 5 and a cylindrical segment 6 directly adjacent to the rear thereof. Two helical flutes 3 extend on the drill point 4. Each flute 3 intersects the surface of the frustoconical segment 5 of each stepped segment Tn to form a primary cutting edge 7, and intersects the surface of the cylindrical segment 6 of each stepped segment Tn to form a secondary cutting edge 8. The primary cutting edge 7 and the secondary cutting edge 8 formed by the same stepped segment Tn and the same flute 3 intersect to form a point 9. Therefore, multiple stepped segments Tn form multiple points 9. The multiple points 9 formed by the same flute 3 and different stepped segments Tn are distributed on a helix with a taper around the working rotational axis 10 or center axis 10 of the drill point 4. Therefore, the above-mentioned drill point 4 is referred to as a multi-point drill point 4.

[0004] See Figure 1a and Figure 1b The two primary / secondary cutting edges 7 / 8 or points 9 formed by the same stepped segment Ti of the drill point 4 and the two flutes 3 are symmetrical or rotationally symmetrical about the working rotational axis 10 of the drill point 4. Therefore, on the one hand, see the K view of the twist drill in Figure 1b , the two radii ri, ri (i = 1, 2, 3, …) measured at the two points 9 of the same stepped segment Ti of the drill point 4 are equal, and are half of the diameter di of the stepped segment Ti, i.e. ri = ri = di / 2. Here, the radii ri, ri of the points 9 can be understood as the distance of the points 9 from the working rotational axis 10 of the drill point 4. On the other hand, see Figure 1a , the axial lengths Li, Li of the two points 9 on the same stepped segment Ti from the drill tip vertex 13 are also equal, i.e. Li = Li (i = 1, 2, 3, …).

[0005] Therefore, in the prior art, two main cutting edges 7 distributed 180° symmetrically in the circumferential direction on all step sections Tn participate in cutting at the same time, the cutting amount and cutting force of the two main cutting edges 7 are equal, which is easy to produce resonance of the same frequency and period. In addition, the problem caused is that the cutting resistance is large, especially at small step sections, the chip flute 3 is narrow and small, and it is not easy to discharge chips. SUMMARY

[0006] Therefore, the present application proposes a drilling portion for a hole machining tool and a hole machining tool, by means of which at least one of the above-mentioned technical problems existing in the prior art can be solved.

[0007] According to one aspect of the present application, a drilling portion for a hole machining tool is proposed, characterized in that the drilling portion comprises:

[0008] at least two chip flutes arranged at intervals in the circumferential direction of the drilling portion,

[0009] a plurality of side portions, each side portion being circumferentially delimited by two adjacent chip flutes, wherein each side portion comprises a plurality of step section portions arranged in succession in the feed direction, and each step section portion comprises a first section and a second section directly adjacent to the first section, wherein, in the case that the step section portions of each side portion are sequentially numbered respectively in the direction opposite to the feed direction, all step section portions belonging to the same ordinal number on all side portions constitute the same step section, wherein each side portion further comprises a transition section portion after all step section portions,

[0010] a plurality of main cutting edges formed by the intersection of each chip flute and the first section of each step section portion and each transition section portion,

[0011] a plurality of secondary cutting edges formed by the intersection of each chip flute and the second section of each step section, and

[0012] a plurality of cutting edges, each cutting edge being formed by the intersection of the main cutting edge and the secondary cutting edge formed by the same chip flute and the same step section portion,

[0013] wherein at least one of the step sections is configured as an asymmetric step section, and the same asymmetric step section has at least two asymmetric step section portions separated by chip flutes in the circumferential direction, the at least two asymmetric step section portions correspondingly form at least two asymmetric cutting edges which are not rotationally symmetric about the working rotation axis, the at least two asymmetric cutting edges thus have different radial distances from the working rotation axis and are arranged axially offset in the direction of the working rotation axis relative to each other.

[0014] The technical effects that can be achieved by the drilling portion of the hole machining tool include, but are not limited to: the asymmetric step section of the drilling portion can achieve misaligned cutting, so that the cutting edges cut at different times and asymmetrically to form a composite cutting effect, thereby gradually decomposing the cutting of the metal amount, high drilling efficiency, labor saving. In addition, due to the fact that the cutting force is not strictly symmetrically distributed on the circumference, cutting resonance of the same frequency and period will not occur.

[0015] Advantageously, the drilling portion is configured as the drilling portion at the foremost end of the hole machining tool, wherein the foremost end first step section in the step section is configured as a drill tip section, and the point at the foremost end of the drill tip section in the feed direction is configured as a drill tip vertex. Each asymmetric edge point on the same asymmetric step section has different axial distances from the drill tip vertex.

[0016] Advantageously, each edge point of the drill tip section is rotationally symmetric about the working rotation axis, and thus has the same radial distance from the working rotation axis and the same axial distance from the drill tip vertex.

[0017] Advantageously, in each step section of the drilling portion after the drill tip section, at least one step section of the first half number of step sections is configured as an asymmetric step section. Here it can be understood that all step sections (including the foremost drill tip section) are numbered in sequence against the feed direction, and at least one step section of the first half of all step sections after the drill tip section is configured as an asymmetric step section. For example, for a drilling portion with 5 step sections (including the foremost drill tip section), the "first half number" is (5-1) ÷ 2 = 2, which means that at least one of the second and third step sections is configured as an asymmetric step section; for a drilling portion with 6 step sections (including the foremost drill tip section), the "first half number" is (6-1) ÷ 2 = 2.5 ≈ 3, which means that at least one of the second, third, and fourth step sections is configured as an asymmetric step section. And so on.

[0018] Advantageously, in each step section of the drilling portion after the drill tip section, at least two step sections of the first half number of step sections that are directly adjacent to each other are configured as asymmetric step sections.

[0019] Advantageously, the two step sections of the drilling portion that are directly adjacent to each other next to the drill tip section are configured as asymmetric step sections.

[0020] Advantageously, the step section of the drilling portion next to the drill tip section is configured as an asymmetric step section.

[0021] Advantageously, the plurality of side portions each has the same number of step segment portions, wherein in each step segment of the drill portion following the drill tip segment, at least one of the last half number of step segments is constituted as a symmetrical step segment, each of the cutting edges on the symmetrical step segment being constituted to have the same radial distance from the working rotational axis and the same axial distance from the drill tip vertex as each other. Here, it is to be understood that all step segments (including the foremost drill tip segment) are numbered in sequence against the feed direction, and at least one of the last half number of step segments in all step segments following the drill tip segment is constituted as a symmetrical step segment. For example, for a drill portion having 5 step segments (including the foremost drill tip segment), the "last half number" is (5-1) ÷ 2 = 2, meaning that at least one of the fourth and fifth step segments is constituted as a symmetrical step segment; for a drill portion having 6 step segments (including the foremost drill tip segment), the "last half number" is (6-1) ÷ 2 = 2.5 ≈ 3, meaning that at least one of the fourth, fifth and sixth step segments is constituted as a symmetrical step segment. The same applies analogously.

[0022] Advantageously, in each step segment of the drill portion following the drill tip segment, at least two of the last half number of step segments are constituted as symmetrical step segments which directly adjoin each other.

[0023] Advantageously, in each step segment of the drill portion following the drill tip segment, the last two of the last half number of step segments are constituted as symmetrical step segments which directly adjoin each other.

[0024] Advantageously, the last step segment of the drill portion is constituted as a symmetrical step segment.

[0025] Advantageously, at least two of the side portions have a different number of step segment portions, wherein the cutting edges on one step segment portion of one of the side portions and the cutting edges on a step segment portion of the other side portion which differs from the step segment portion of the one side portion in terms of its ordinal number are constituted to have the same radial distance from the working rotational axis and are arranged axially without offset in relation to each other in the direction of the working rotational axis.

[0026] Advantageously, the cutting edges on the last step segment portion of the at least two side portions have the same radial distance from the working rotational axis and are arranged axially without offset in relation to each other in the direction of the working rotational axis.

[0027] Advantageously, the transition segment portion of each side portion (or rather the main cutting edges thereon, for example the front end and / or the rear end of the main cutting edges) has the same radial distance from the working rotational axis and is arranged axially without offset in relation to each other in the direction of the working rotational axis.

[0028] Advantageously, the first section is configured as a truncated conical section and the second section is configured as a cylindrical section; or the first section and / or the second section is configured as a curved section.

[0029] Advantageously, the number of stepped sections of the drill portion is greater than or equal to 3.

[0030] Advantageously, the number of stepped sections of the drill portion is greater than or equal to 5.

[0031] Advantageously, the included angle between the main cutting edges of the tip section is greater than the cone angle of the conical drill portion.

[0032] Advantageously, the included angle between the main cutting edges of the tip section is obtuse and the cone angle of the drill portion is acute.

[0033] Advantageously, the flutes are straight or helical.

[0034] Advantageously, at least one main cutting edge is configured as a multi-sectioned edge, each section being straight or arcuate.

[0035] According to another aspect of the present application, a hole machining tool is proposed, characterized in that it has a shank for fixing the hole machining tool and a working portion in front of the shank for hole machining, the working portion having a drill portion according to the present application at its most forward end.

[0036] Advantageously, the hole machining tool is configured as a twist drill, the working portion having a pilot portion adjoining the shank and the drill portion adjoining the pilot portion in front of the pilot portion, wherein the flutes extend over at least a portion of the pilot portion.

[0037] Advantageously, the flutes extend over a majority of the pilot portion.

[0038] Advantageously, the hole machining tool is configured as a taper drill, the working portion comprising a plurality of stepped drill / counterbore portions arranged successively in the feed direction and increasing in diameter, wherein a first drill portion at the most forward end is provided with the drill portion.

[0039] Advantageously, the hole machining tool is configured as a chamfering and counterboring integrated drill bit, the working portion having the drill portion at the most forward end, a stepped hole drill portion for drilling a stepped hole axially spaced apart from and behind the drill portion, and a hole chamfering portion for chamfering the drilled stepped hole axially spaced apart from and behind the stepped hole drill portion.

[0040] Advantageously, the hole machining tool is configured as a complex tap drill, the working portion having the drilling portion at the foremost end, a tapping portion for tapping the hole axially spaced apart from and after the drilling portion, and a hole chamfering portion for chamfering the hole axially spaced apart from and after the tapping portion.

[0041] Advantageously, the hole machining tool is configured as a complex tap drill, the working portion having the drilling portion at the foremost end, a tapping portion for tapping the hole axially spaced apart from and after the drilling portion, and a hole chamfering portion for chamfering the hole axially spaced apart from and after the tapping portion.

[0042] Advantageously, the hole machining tool is configured as a complex tap drill, the working portion having the drilling portion at the foremost end, a tapping portion for tapping the hole axially spaced apart from and after the drilling portion, and a hole chamfering portion for chamfering the hole axially spaced apart from and after the tapping portion.

[0043] The above-mentioned technical features and the technical features to be mentioned below and the technical features shown in the drawings can be combined with each other arbitrarily, as long as the combined technical features are not contradictory to each other. All technically feasible combinations of features are included in the technical content described in the specification. BRIEF DESCRIPTION OF DRAWINGS

[0044] The application will be further explained below with reference to exemplary embodiments by means of the accompanying drawings. In which:

[0045] Figure 1a schematic side view of a twist drill with a symmetrical multi-point drilling portion in the prior art;

[0046] Figure 1b schematic side view of a twist drill with a symmetrical multi-point drilling portion in the prior art; Figure 1a Figure 1a

[0047] Figure 2a schematic side view of the application of an asymmetrical multi-point drilling portion on a twist drill according to one embodiment of the application;

[0048] Figure 2b schematic side view of a twist drill with a symmetrical multi-point drilling portion in the prior art; Figure 2a Figure 2a

[0049] Figure 3a schematic side view of the application of an asymmetrical multi-point drilling portion on a twist drill according to another embodiment of the application, here mainly showing the drilling portion;

[0050] Figure 3b schematic side view of a twist drill with a symmetrical multi-point drilling portion in the prior art; Figure 3a Figure 3a

[0051] Figure 4 Figure 3a ​​​​​​​schematic longitudinal section view of the asymmetric multi-point drill point in the

[0052] Figure 5 shows Figure 3a schematic longitudinal section view of the asymmetric multi-point drill point in the

[0053] Figure 6 shows Figure 3a schematic longitudinal section view of the asymmetric multi-point drill point in the

[0054] Figure 7a shows a schematic longitudinal section view of an asymmetric multi-point drill point according to a further embodiment of the application;

[0055] Figure 7b shows Figure 7a schematic longitudinal section view of the asymmetric multi-point drill point in the

[0056] Figure 8 shows a schematic side view of the application of an asymmetric multi-point drill point according to an embodiment of the application on a gun-drill;

[0057] Figure 9 shows a schematic side view of the application of an asymmetric multi-point drill point according to an embodiment of the application on a chamfer-drill integrated drill bit;

[0058] Figure 10 shows a schematic side view of the application of an asymmetric multi-point drill point according to an embodiment of the application on a composite tap drill bit;

[0059] Figure 11 shows a schematic side view of the application of an asymmetric multi-point drill point according to an embodiment of the application on a gun-drill;

[0060] Figure 12 shows a schematic side view of the application of an asymmetric multi-point drill point according to an embodiment of the application on a saw-drill drill bit;

[0061] Figure 13a shows a schematic side view of the application of an asymmetric multi-point drill point according to a further embodiment of the application on a twist drill; and

[0062] Figure 13b shows Figure 13a a detail view of the asymmetric multi-point drill point of the twist drill in the DETAILED DESCRIPTION

[0063] An illustrative embodiment of an asymmetric (or non-rotationally symmetric) multi-land drill point 4 according to the present application is described below. In this description, for the purpose of explanation, in the drawings, specific embodiments of systems, structures and devices are shown, but are presented merely for purposes of illustration and description, and are not intended to limit the scope of the application. Indeed, specific embodiments of the present application can be practiced without these specific details. In other instances, well-known structures and functions have not been described in detail in order to not obscure the application. It will be apparent, however, to one of ordinary skill in the art having the benefit of this description, that many

[0064] The terms and phrases used herein should be understood as having the meanings set forth in this section. The terms and phrases used herein have their normal and customary meanings in the field of the application, unless otherwise indicated. The use of "including," "comprising," "having," "containing," and variations thereof herein, is meant to encompass the items listed thereafter, and any subsequent items added to such events. Such events are open-ended, and unless otherwise stated, the use of "including," "comprising," "having," "containing" and variations thereof herein is not meant to exclude other items from the events.

[0065] Unless the content requires, throughout the description, the word "comprise" and variations of the word, such as "comprising" or "comprises," will be understood to encompass the items listed thereafter, and any subsequent items added to such events. Such events are open-ended, and unless otherwise stated, the use of "including," "comprising," "having," "containing," and variations thereof herein is not meant to exclude other items from the events.

[0066] The illustrative embodiments of the asymmetric multi-land drill point 4 according to the present application and its use are described next in connection with the illustrative Figures 2a to 6 The illustrative embodiments of the asymmetric multi-land drill point 4 according to the present application and its use are described next in connection with the illustrative Figure 1a and Figure 1b Corresponding parts are marked with the same reference numerals in the embodiments shown.

[0067] Figure 2a and Figure 2b An embodiment of an asymmetric multi-land drill point 4 according to the present application is shown. The drill point 4 is exemplarily used here as a front drill point 4 of a twist drill for drilling with the twist drill. The twist drill comprises a shank 1 and a working portion 2 connected to the shank 1. The working portion 2 comprises a cylindrical guide portion 11 connected to the shank 1 and a conical drill point 4 connected to the guide portion 11. A chip flute 3 extends over the entire drill point 4 and partially over the guide portion 11. Here, the chip flutes 3 are helically extending chip flutes 3. Linearly extending chip flutes 3 are also conceivable in other embodiments. The number of chip flutes 3 is two here. More than two chip flutes 3, for example three, four,..., are also conceivable in other embodiments.

[0068] The drill portion 4 comprises a plurality of stepped sections Tn (n = 1, 2, 3,..., i,..., 9) with diameters increasing in the direction opposite to the feed direction, and each stepped section Tn comprises a frustoconical section 5 and a cylindrical section 6 adjacent to the frustoconical section 5. There are nine stepped sections Tn in this embodiment, but different numbers of stepped sections Tn (e.g. 2, 3, 4, 5, 6, 7, 8, 10,...) are also conceivable in other embodiments. Each two adjacent stepped sections Tn-i, Tn form a stepped groove 20 extending in the circumferential direction and having a generally V-shaped cross section, and each stepped groove 20 is enclosed by the cylindrical section 6 of the former stepped section Tn-i and the frustoconical section 5 of the latter stepped section Tn. In other embodiments, the latter cylindrical section 6 can also be replaced by a frustoconical section with a smaller taper angle than the frustoconical section 5. Each flute 3 intersects the surface of the frustoconical section 5 of each stepped section Tn to form a primary cutting edge 7, and intersects the surface of the cylindrical section 6 of each stepped section Tn to form a secondary cutting edge 8. The primary cutting edge 7 and the secondary cutting edge 8 formed by the same stepped section Tn and intersecting the same flute 3 in turn intersect to form a tip 9. Thus, a plurality of stepped sections Tn form a plurality of tips 9. The plurality of tips 9 formed by the same flute 3 and different stepped sections Tn are distributed on a helical line with a taper extending around the working rotation axis 10 of the drill portion 4. Therefore, the drill portion 4 is referred to as a drill portion 4 with multiple tips (formed by multiple stepped sections Tn). Two flutes 3 form a pair of primary cutting edges 7 and secondary cutting edges 8 respectively with the same stepped section Tn, and each pair of primary cutting edges 7 and secondary cutting edges 8 forms a tip, so that two tips 9 are distributed in the circumferential direction on the same stepped section Tn.

[0069] For the primary cutting edges 7, see the embodiments shown in Figure 2a and Figure 2b The primary cutting edges 7 on each stepped section Tn can be configured as one-piece, which can be straight or arc-shaped. However, in some not shown embodiments, at least one of the primary cutting edges 7 can also be configured as multi-piece, each piece can be straight or arc-shaped. The multi-piece primary cutting edge 7 comprises at least two primary cutting edge sections, and an angle (not 0 degree and 180 degree) can be formed between adjacent two primary cutting edge sections. Thereby, the chip can be further broken down, and the chip force and the cutting heat can be reduced.

[0070] In this embodiment, the first stepped section T1 at the foremost end of the drill portion 4 constitutes the smallest diameter tip section T1 of the twist drill, and the two primary cutting edges 7 of the tip section are configured as two straight or linear primary cutting edges 7, and the obtuse included angle formed between the two primary cutting edges 7 can correspond to the primary cutting edge included angle of a common non-multi-stepped-section twist drill, and is greater than the taper angle a of the overall conical drill portion 4 here (see Figure 2a), the cone angle a is preferably configured as an acute angle, but it is also possible to configure it as a right angle or an obtuse angle. In such a configuration, the small-diameter drill tip section as the first step section T1 has a good centering property, and the cylindrical section 6 of the drill tip section becomes a centering shaft after cutting into the workpiece, and the drill tip step cylindrical section 6 is sufficient to play a centering role when the asymmetric cutting edges of the subsequent step sections Tn (where n > 1), especially the later-described step sections with a staggered structure, are gradually cut into the workpiece, so that the working rotational axis 10 does not deviate. As with a conventional twist drill, the two straight main cutting edges 7 and the other two auxiliary edges and one chisel edge 25 on the drill tip section constitute the top edges on the drill tip section. The two straight main cutting edges 7 respectively intersect the two ends of the chisel edge 25 at the front end, and therefore the chisel edge 25 is located at the frontmost end of the drill tip section.

[0071] Here, the point at which the drill bit is located at the frontmost end in the feed direction or in the direction of the working rotational axis is configured as the drill tip vertex 13, which is also the point at the frontmost end or the farthest end of the drill tip section as the first step section T1. At the beginning of drilling, the drill tip vertex 13 is the part of the drill bit that first contacts the workpiece. It is conceivable that the drill tip vertex 13 can be located on the chisel edge 25, and can be the intersection of the working rotational axis 10 and the chisel edge 25. If the chisel edge 25 is a straight edge perpendicular to the working rotational axis 10, then any point on the chisel edge 25 can be referred to as the drill tip vertex 13.

[0072] The drilling portion 4 further includes a transition section 12 that transitions from the last step section T9 (or the cylindrical section 6 thereof) to the adjacent portion of the hole machining tool, here the guide portion 11, and the transition section 12 is configured as a truncated cone section 5 and connects the cylindrical section 6 of the last step section T9 and the guide portion 11 to each other. The transition section 12 also forms a main cutting edge 7 with the flutes 3.

[0073] In the present application, the substantially conical drilling portion 4 is divided into a plurality of substantially arc-shaped side portions in the circumferential direction by a plurality of flutes 3, so that each side portion is bounded in the circumferential direction by two adjacent flutes 3. Each side portion of the drilling portion 4 includes a plurality of step section portions (or step section sections) that increase in diameter in the direction opposite the feed direction, and each step section portion respectively includes a truncated cone section portion 5 and a cylindrical section portion 6 adjacent thereto. In addition, each side portion of the drilling portion 4 also includes a last transition section portion 12 in the feed direction, so that each transition section portion 12 is also bounded in the circumferential direction by two adjacent flutes 3.

[0074] For the convenience of describing and understanding the present application, it is defined here that, in the case of sequentially numbering the step section portions of each side portion in the direction opposite the feed direction, all the step section portions belonging to the same number on each side portion are still defined as constituting a step section Tn (n = 1, 2, 3, …, i, …, 9). For example, in the case of the first side portion 1, the step section portions of the first side portion 1 are sequentially numbered as T1.1, T1.2, T1.3, …, T1.i, …, T1.9, and the step section portions of the first side portion 1 belonging to the same number are defined as constituting a step section Tn (n = 1, 2, 3, …, i, …, 9).Figure 2a and Figure 2b The embodiment shown by way of example further illustrates that the drilling portion 4 is divided into two substantially arc-shaped side portions in the circumferential direction by the two flutes 3, so that each side portion is bounded in the circumferential direction by the two flutes 3. Each side portion of the drilling portion 4 comprises nine step segment portions of increasing diameter in the direction of feed, and each step segment portion accordingly comprises one frustoconical segment portion 5 and one cylindrical segment portion 6 adjoining it. The step segment portions of the two side portions are respectively sequentially numbered 1, 2, 3,..., i,..., 9 in the direction of feed, and the two step segment portions belonging to the same number i on the two side portions are defined as constituting one step segment Ti (i = 1, 2, 3,..., 9). This is independent of whether the two step segment portions belonging to the same number i are rotationally symmetrical about the working rotational axis or not. In addition, the two side portions of the drilling portion 4 also respectively comprise one last transition segment portion 12 in the direction of feed, so that each transition segment portion 12 is bounded in the circumferential direction by the two adjacent flutes 3.

[0075] Referring to Figure 2a and Figure 2b , the two step segment portions (which can also be referred to as step segment halves) of the same step segment Ti (here the third step segment T3 is designated by way of example) of the drilling portion 4, which are separated by the two flutes 3, are not symmetrical about the working rotational axis 10 of the drilling portion 4.

[0076] In particular, the radius ri of the cylindrical segment 6 of the step segment portion of the non-symmetrical step segment Ti which is located on the first side portion (in Figure 2a towards the inside of the sheet and on the left in Figure 2b ) is greater than the radius ri' of the cylindrical segment 6 of the step segment portion of the step segment Ti which is located on the second side portion (in Figure 2a towards the outside of the sheet and on the right in Figure 2b ), i.e. ri > ri', and the axial length Li of the cylindrical segment 6 (or rather the front end thereof) of the step segment portion of the first side portion of the step segment Ti from the apex 13 of the drill point is greater than the axial length Li' of the cylindrical segment 6 (or rather the front end thereof) of the step segment portion of the second side portion of the step segment Ti from the apex 13 of the drill point, i.e. Li > Li'. That is to say, the step segment portion with the smaller radius is arranged axially closer to the apex 13 of the drill point in the same step segment.

[0077] In other words, the two cutting edges 9 of the same step segment Ti formed by two flutes 3 are not symmetrical about the working rotation axis 10 of the drill cutting portion 4. Specifically, the radius ri of the cutting edge 9 of the step segment portion of the step segment Ti located at the first side is greater than the radius ri' of the cutting edge 9 of the step segment portion of the step segment Ti located at the second side, i.e. ri > ri', and the axial length Li of the cutting edge 9 of the step segment portion of the step segment Ti located at the first side from the drill tip vertex 13 is greater than the axial length Li' of the cutting edge 9 of the step segment portion of the step segment Ti located at the second side from the drill tip vertex 13, i.e. Li > Li'.

[0078] Therefore, on the one hand, referring to Figure 2b , the two radii ri, ri' (here i = 3) of the same step segment Ti of the drill cutting portion 4 measured at its two cutting edges 9 are not equal, and neither is equal to half of the measured diameter di' of the step segment Ti, i.e. ri ≠ ri' ≠ di' / 2, but ri + ri' = di'. Here, the radius ri, ri' of the cutting edge 9 can be understood as the distance of the cutting edge 9 from the working rotation axis 10 of the drill cutting portion 4. On the other hand, referring to Figure 2a , the axial lengths Li, Li' of the two cutting edges 9 on the same step segment Ti from the drill tip vertex 13 are also not equal, i.e. Li ≠ Li'.

[0079] This makes the two major cutting edges 7 of the asymmetric step segment Ti on the two flutes 3 distributed 180° in the circumferential direction not simultaneously involved in cutting when cutting the same workpiece cross section, i.e. axially successive cutting or staggered cutting. The major cutting edge 7 closer to the drill tip vertex 13 cuts first, and then the other major cutting edge 7 distributed 180° in the circumferential direction (i.e. the major cutting edge 7 relatively far from the drill tip vertex 13) cuts again, whereby the metal allowance is gradually decomposed until the desired diameter hole is obtained. Therefore, the drill bit with this asymmetric multi-edge drill cutting portion 4 avoids the disadvantages of the symmetrical multi-edge drill cutting portion 4 shown in Figure 1a and Figure 1b , makes the machining more smooth, and at the same time, the drilling efficiency is higher and more labor-saving. In addition, due to the existence of the asymmetric step segment Ti, the cutting force is not strictly 180° symmetrical distributed in the circumference, and then the cutting resonance of the same frequency and co-periodicity will not be produced.

[0080] In Figure 2a and Figure 2bIn the shown embodiment of the present application, the asymmetric structure of the cutting edges on the third step section T3 of the drill portion 4 is only schematically marked, but it is also possible to provide such an asymmetric structure of the cutting edges on other or more step sections Tn. That is, it is possible to provide such an asymmetric structure of the cutting edges on at least one step section Tn of the drill portion 4.

[0081] Herein, in each step section Tn (n > 1) of the drill portion 4 following the tip section T1 in the feed direction, the main cutting edge length on the step section with the smaller diameter can be shorter than the main cutting edge length on the step section with the larger diameter, but this is not mandatory and in practice it is also possible to consider it longer or equal.

[0082] Next, referring to Figures 3a to 6 , a specific application of the design concept of the present application is further described in detail by way of example of a drill portion 4 having five step sections Tn.

[0083] In the prior art, referring to Figure 1a and Figure 1b , the radii of the cylindrical segments 6 or the nose 9 of the two step section portions of the same step section Ti of a symmetrical multi-nose drill portion 4 are identical and equal to half of the corresponding measured / work diameter di, i.e. ri = ri = di / 2. Whereas, referring to Figure 3a , Figure 3b and Figure 4 , the measured radii ri, ri' of the cylindrical segments 6 or the nose 9 of the two step section portions of the same step section Ti (here i = 2, 3) of an asymmetric multi-nose drill portion 4 of the present application are not identical and the measured diameter dic of the step section Ti is equal to the sum of the two radii ri, ri' of the cylindrical segments 6 or the nose 9 of the two step section portions, i.e. dic = ri + ri', wherein, in Figure 4 , the measured diameter d2c of the second step section T2 is exemplarily marked and is equal to the sum of the two measured radii r2 and r2'. Whereas, the actual work diameter dig of the step section Ti (i.e. the maximum hole diameter that can be cut by the step section Ti) is equal to twice the maximum radius max{ri, ri'} of the step section Ti, i.e. dig = 2*max{ri, ri'}.

[0084] Further, in the prior art, referring to Figure 1a and Figure 1b , the axial lengths of the cylindrical segments 6 or the nose 9 of the two step section portions of the same step section Ti of a symmetrical multi-nose drill portion 4 from the axial tip vertex 13 are equal, i.e. Li = Li'. Whereas, in the present embodiment, referring to Figure 3aThe axial length of the cylindrical segment 6 or the land 9 of the two step segment portions of the same step segment Ti (here i = 2, 3) of the asymmetric multi-land drill point of the drill cutting portion 4 from the drill point vertex 13 is not equal, i.e. Li≠ Li', but has a certain axial offset ΔLi, ΔLi = Li - Li', in the axial direction. Figure 4 In the example shown in

[0085] In this embodiment, only the second step segment T2 and the third step segment T3 are arranged axially and radially offset, i.e. asymmetrically, with respect to the working rotation axis 10, while the first step segment T1, the subsequent fourth step segment T4 and the fifth step segment T5 as drill point segments are still arranged symmetrically with respect to the working rotation axis 10. Thus, the measured diameters d1, d4, d5 of the first, fourth and fifth step segments T1, T4, T5 are equal to their working diameters, while the measured diameters d2, d3 of the second and third step segments T2, T3 are not equal to their working diameters, but are smaller than their working diameters dig (dig = 2*max{ri, ri'}, where i = 2, 3). The radii of the cylindrical segments 6 or lands 9 of each of these two step segments T2, T3 on the different step segment portions are not equal and the cylindrical segments 6 or lands 9 are axially offset from each other. In operation, these two asymmetric step segments T2, T3 can advantageously be combined, i.e. after multi-land cutting, to form four working steps T2.1, T2.2, T3.1, T3.2, which are described in more detail, for example, with reference to Figure 5 and

[0086] Furthermore, in Figure 4 It is also marked that the axial length of the step segment portion on the first side of each step segment Tn of the drill cutting portion 4 is li, l2, l3, l4, l5; the axial length of the step segment portion on the second side of each step segment Tn of the drill cutting portion 4 is li', l2', l3', l4', l5'; the measured diameters of each step segment Tn are dl < d2 < d3 < d4 < d5; the radius difference of the cylindrical segments 6 or lands 9 of the same side step segment portions of adjacent step segments Tn is δ2, δ3, δ4, δ5, δ2', δ3', δ4', δ5', where δ2 < δ2' and δ5 = δ5'; and the radius difference of the cylindrical segments 6 of each step segment portion of the fifth step segment T5 and the guide portion 11 is δ, δ', where δ = δ'.

[0087] Next, reference is made to Figure 5 and Figure 6Fig. 2, they schematically show cross-sectional views of the asymmetric multi-fluted drill point 4 in a plane parallel to the working rotational axis 10. Therein, the asymmetric second and third step sections T2, T3 of the drill point 4 according to the present application are seen in their composite cutting effect of four working step sections T2.1, T2.2, T3.1, T3.2 in actual working. The following terms "above" and "below" refer to the orientation of the structural features in Figure 5 and Figure 6 .

[0088] In particular, for the asymmetrically arranged second step section T2, the radius r2 of the lower cylindrical section 6 or the nose 9 of the second step section T2 is smaller than the radius r2' of the upper cylindrical section 6 or the nose 9 of the second step section T2, and the axial distance of the lower cylindrical section 6 or the nose 9 of the second step section T2 from the drill tip vertex 13 is smaller than the axial distance of the upper cylindrical section 6 or the nose 9 of the second step section T2 from the drill tip vertex 13. Thereby, it is seen (see in particular the two dark bold broken lines in axial direction) that, after an imaginary rotation of the lower cutting edges 7, 8 of the second step section T2 by 180 degrees around the central axis 10 and of the upper cutting edges 7, 8 of the second step section T2 by 180 degrees around the central axis 10, the lower main cutting edges 7 of the second step section T2 are fully involved in cutting, whereas the upper main cutting edges 7 of the second step section T2 are only partially involved in cutting. Thereby, one second step section T2 itself generates the composite cutting effect of two working step sections T2.1, T2.2.

[0089] Likewise, for the asymmetrically arranged third step section T3, the radius of the lower cylindrical section 6 or the nose 9 of the third step section T3 is smaller than the radius of the upper cylindrical section 6 or the nose 9 of the third step section T3, and the axial distance of the lower cylindrical section 6 or the nose 9 of the third step section T3 from the drill tip vertex 13 is smaller than the axial distance of the upper cylindrical section 6 or the nose 9 of the third step section T3 from the drill tip vertex 13. Thereby, it is seen (see in particular the two dark bold broken lines in axial direction) that, after an imaginary rotation of the lower cutting edges 7, 8 of the third step section T3 by 180 degrees around the central axis 10 and of the upper cutting edges 7, 8 of the third step section T3 by 180 degrees around the central axis 10, the lower main cutting edges 7 of the third step section T3 are only partially involved in cutting, and the upper main cutting edges 7 of the third step section T3 are also only partially involved in cutting. Thereby, one third step section T3 itself generates the composite cutting effect of two working step sections T3.1, T3.2.

[0090] Thus, by Figure 5 andFigure 6 It can be seen that the drilling portion 4 with 5 stepped sections Tn can be decomposed or rather composed of 7 stepped sections Tn participating in the cutting in actual work, thus 2 working stepped sections Tn are additionally provided compared to the symmetrical drilling portion 4 with 5 stepped sections Tn. The four working stepped sections T2.1, T2.2, T3.1, T3.2 composed of the asymmetrical second stepped section T2 and the asymmetrical third stepped section T3 are also asymmetrical in the measured dimension, their working diameters d2.1, d2.2, d3.1, d3.2 are different from the measured diameters. Their working diameters d2.1, d2.2, d3.1, d3.2 are twice the maximum value (ri or ri') of the two radii at the working stepped section T2.1, T2.2, T3.1, T3.2, i.e. 2 x max{ri, ri'}. This can be seen exemplarily for the third working stepped section T2.2 in Figure 5 and Figure 6 The measured diameter of the third working stepped section T2.2 is the sum of r2 and r2', but is smaller than its working diameter d2.2 = 2 x r2'.

[0091] In the present embodiment, the measured diameter dl of the symmetrical first stepped section T1, the measured diameter d4 of the symmetrical fourth stepped section T4 and the measured diameter d5 of the symmetrical fifth stepped section T5 are the actual working diameters thereof.

[0092] It can be seen from Figure 5 and Figure 6 that the working diameters dl, d2.1, d2.2, d3.1, d3.2, d4, d5 of the 7 working stepped sections Tn are increasing and are smaller than the diameter d of the hole machining tool abutment portion, here the guide portion 11. The axial distances lg1, lg2.1, lg2.2, lg3.1, lg3.2, lg4, lg5 of the rear ends of the cylindrical sections 6 of the 7 working stepped sections Tn from the drill tip apex 13 are increasing.

[0093] It can be seen from Figure 5 and Figure 6 that the blade tips 9 of the first stepped section T1 and the fourth and fifth stepped sections T4, T5 are symmetrically distributed about the working rotation axis 10, i.e. the blade tips 9 on the same stepped section T4, T5 not only have the same radius, but also the same axial distance from the drill tip apex 13 or rather no axial misalignment.

[0094] In such an overall structure, firstly, the small-diameter drill tip section as the first step section T1 has good centering, and the drill tip section becomes a centering shaft after cutting into the workpiece. In addition, the cutting edges of the second and third step sections T2 and T3 have a small radial distance (cutting radius) from the rotation axis 10, i.e., a small cantilever amount, so that the force is also small, and thus the asymmetric structure thereof does not generate a large eccentric force on the drilling section 4. Therefore, when the asymmetric cutting edges of the subsequent second and third step sections T2 and T3 with the staggered structure gradually cut into the workpiece, respectively, the first step section T1 is sufficient to play a centering role, so that the working rotation axis 10 does not deviate. The cutting edges of the fourth and fifth step sections T4 and T5 have a large radial distance (cutting radius) from the axis, i.e., a large cantilever amount, so that the force is also large, and thus the cutting edges (or the blade tips 9) are designed to be symmetrically distributed, so that the main cutting edges 7 bearing the large cutting force are balanced in radial cutting, so that the overall drilling section 4 is balanced, the working rotation axis 10 during drilling is stable, the working rotation axis 10 is prevented from deviating, and the dimensional accuracy of the final hole diameter is ensured. In addition, after the entire drilling section 4 is completely cut into the workpiece, the cutting edges of all step sections Tn work at the same time, and since the overall cutting force is not strictly 180° symmetrically distributed in the circumference, cutting resonance of the same frequency and period does not occur.

[0095] In addition, since the asymmetric step sections T2 and T3 of the asymmetric multi-blade-tip drilling section 4 have cutting edges staggered in the axial direction on different step section portions, the metal remaining to be cut during actual cutting work is again decomposed and refined. In the present embodiment, the five step sections Tn each have two step section portions, and when all enter the work (rotation), the effect of actually machining (cutting) seven stepped holes is achieved, so that the actual cutting edge number (7 steps) of the tool work (cutting) is greater than the cutting edge number (5 steps) of the tool itself.

[0096] Referring to Figure 6Due to the axial misalignment structure of the asymmetric step sections T2, T3, the axial distance from the adjacent main and minor cutting edge pairs on the same chip flute 3 to the drill tip vertex 13 has a distance difference Δl2 = lg3.1-lg2.1 (i.e. the distance difference of the main and minor cutting edge pairs on the second working step section T2.1 and the fourth working step section T3.1), Δl3 = lg3.2-lg2.2 (i.e. the distance difference of the main and minor cutting edge pairs on the third working step section T2.2 and the fifth working step section T3.2), which is much larger than the distance difference Δl2' = lg2.2-lg2.1, Δl3' = lg3.1-lg2.2 of the symmetrically distributed step structure of the symmetric multi-fluted drill point 4, i.e. Δl2 = lg3.1-lg2.1 is much larger than Δl2' = lg2.2-lg2.1, Δl3 = lg3.2-lg2.2 is much larger than Δl3' = lg3.1-lg2.2. This makes the chip space between the adjacent cutting edge pairs of the same side chip flute 3 increase, and the chip removal is smoother. Especially for the cutting edges at the small diameter step section Tn, the cutting line speed is small, the chip flow speed is also small, and the chip flute 3 is also relatively narrow due to the small diameter, so the chip removal of the cutting edges at the small diameter step section Tn is relatively not smooth. Due to the axial misalignment structure of the asymmetric multi-fluted drill point 4 according to the present application, the chip space between the adjacent cutting edge pairs on the same chip flute 3 is increased, thereby improving the chip removal performance of the cutting edges at the small diameter step.

[0097] Referring to Figure 7a and Figure 7b , a schematic longitudinal sectional view of an asymmetric multi-fluted drill point 4 according to a further embodiment of the present application is shown.

[0098] In this embodiment, the drill point 4 is divided into two sides by two chip flutes 3 in the circumferential direction. Unlike the above-mentioned embodiments, in the present embodiment, the upper side of the drill point 4 includes 3 step section portions T1, T2, T3 and 1 transition section portion 12 in diameter increasing against the feed direction, and the lower side of the drill point 4 includes 4 step section portions T1, T2, T3, T4 and 1 transition section portion 12 in diameter increasing against the feed direction.

[0099] Here, all the step section portions belonging to the same serial number on each side in the feed direction are defined as constituting one step section Tn (n = 1, 2, 3, 4). Specifically, the first, second, and third step section portions T1, T2, T3 on the upper side in the feed direction and the first, second, and third step section portions T1, T2, T3 on the lower side in the feed direction form the first, second, and third step sections T1, T2, T3, respectively. The fourth step section portion T4 on the lower side in the feed direction forms the fourth step section T4 by itself.

[0100] Referring to Figure 7a and Figure 7b , the two step section portions of the second step section T2 and the two step section portions of the third step section T3 of the drill portion 4 are not symmetrical about the working rotational axis 10.

[0101] Specifically, the radius (or the radial distance from the working rotational axis 10) of the cylindrical segment 6 of the upper step section portion of the second step section T2 and the third step section T3 is greater than the radius (or the radial distance from the working rotational axis 10) of the cylindrical segment 6 of the lower step section portion of the second step section T2 and the third step section T3, respectively, and the axial length from the blade tip 9 of the upper step section portion of the second step section T2 and the third step section T3 to the drill tip vertex 13 is greater than the axial length from the blade tip 9 of the lower step section portion of the second step section T2 and the third step section T3 to the drill tip vertex 13, respectively. That is, the step section portion with a smaller radius in the same step section is disposed closer to the drill tip vertex 13 on the axis.

[0102] Figure 7b The complex cutting effects of the asymmetrical second step section T2 and the third step section T3 are shown. Here, it can be seen that the asymmetrical second and third step sections T2, T3 are combined into the complex cutting effects of the four working step sections T2.1, T2.2, T3.1, T3.2 in actual work.

[0103] Here, the blade tip 9 of the working step section T3.2 is symmetrical with the blade tip 9 of the lower fourth step section T4 or the fourth step section portion T4. Therefore, the symmetrical working step section T3.2 and the fourth step section T4 or the fourth step section portion T4 arranged in cooperation can maintain the centering function after the drill portion 4 enters the workpiece.

[0104] Figure 8A schematic side view showing the application of the asymmetric multi-edge point drill bit 4 according to one embodiment of the present application to a gun drill. The gun drill has a shank portion 1 for fixing the gun drill and a working portion 2 for hole machining adjacent to the shank portion 1. The working portion 2 comprises a plurality of stepped drill / ream portions 30 arranged successively in the feed direction and increasing in diameter. Each drill / ream portion 30 can drill / ream a hole with the same diameter as its cylindrical segment on, for example, a thin metal plate such as a steel plate. Generally, the first step in front of the working portion 2 can be referred to as a drill portion, and the following steps can be referred to as ream portions 30. The tip portion or first drill portion in front of the working portion 2 is configured as the asymmetric multi-edge point drill bit 4 according to the present application. That is, the first drill portion 30 at the most front end of the working portion 2 has the drill bit 4 according to the present application and a cylindrical segment 40 adjacent thereto. The cylindrical segment 40 defines, for example, the smallest diameter hole that the gun drill can drill. Further, it can be seen that the helical chip flute 3 extends longitudinally through the entire working portion 2.

[0105] Figure 9 A schematic side view showing the application of the asymmetric multi-edge point drill bit 4 according to one embodiment of the present application to a chamfer-drill integrated drill bit. The chamfer-drill integrated drill bit has a shank portion 1 for fixing the same and a working portion 2 for hole machining adjacent to the shank portion 1. The working portion 2 has a most front end configured as the asymmetric multi-edge point drill bit 4 according to the present application, a step hole drill portion 50 for drilling a step hole axially spaced apart from and after the drill bit 4, and a hole chamfer portion 60 for chamfering the drilled step hole axially spaced apart from and after the step hole drill portion 50. Here, the chip flute 3 extends successively through the multi-edge point drill bit 4, the step hole drill portion 50, and the hole chamfer portion 60.

[0106] Figure 10 A schematic side view showing the application of the asymmetric multi-edge point drill bit 4 according to one embodiment of the present application to a composite tap drill bit. The composite tap drill bit has a shank portion 1 for fixing the same and a working portion 2 for hole machining adjacent to the shank portion 1. The working portion 2 has a most front end configured as the asymmetric multi-edge point drill bit 4 according to the present application, a tapping portion 70 for tapping a hole axially spaced apart from and after the drill bit 4, and a hole chamfer portion 80 for chamfering the hole axially spaced apart from and after the tapping portion 70. Here, the chip flute 3 extends successively through the multi-edge point drill bit 4, the tapping portion 70, and the hole chamfer portion 80.

[0107] Figure 11A schematic side view showing the application of the asymmetric multi-point drill bit 4 according to one embodiment of the present application to a saw drill bit. The saw drill bit has a shank 1 for fixing the saw drill bit and a working portion 2 for hole machining adjacent to the shank 1. The working portion 2 has a frontmost asymmetric multi-point drill bit 4 according to the present application and a reaming portion 90 behind the drill bit 4 and directly adjacent to it, which is capable of reaming to a desired hole diameter for machining a sheet. Based on the asymmetric multi-point drill bit 4 according to the present application, the saw drill bit can efficiently cut into a workpiece and finally complete drilling. Here, the chip flutes 3 extend successively through the multi-point drill bit 4 and the reaming portion 90.

[0108] Figure 12 A schematic side view showing the application of the asymmetric multi-point drill bit 4 according to one embodiment of the present application to a saw drill bit. The saw drill bit has a shank 1 for fixing the saw drill bit and a working portion 2 for hole machining adjacent to the shank 1. The working portion 2 has a frontmost asymmetric multi-point drill bit 4 according to the present application and a reaming portion 90 behind the drill bit 4 and directly adjacent to it, which is capable of reaming to a desired hole diameter for machining a sheet. Based on the asymmetric multi-point drill bit 4 according to the present application, the saw drill bit can efficiently cut into a workpiece and finally complete drilling. Here, the chip flutes 3 extend successively through the multi-point drill bit 4 and the reaming portion 90.

[0109] Figure 13a A schematic side view showing the application of the asymmetric multi-point drill bit 4 according to one embodiment of the present application to a saw drill bit. The saw drill bit has a shank 1 for fixing the saw drill bit and a working portion 2 for hole machining adjacent to the shank 1. The working portion 2 has a frontmost asymmetric multi-point drill bit 4 according to the present application and a reaming portion 90 behind the drill bit 4 and directly adjacent to it, which is capable of reaming to a desired hole diameter for machining a sheet. Based on the asymmetric multi-point drill bit 4 according to the present application, the saw drill bit can efficiently cut into a workpiece and finally complete drilling. Here, the chip flutes 3 extend successively through the multi-point drill bit 4 and the reaming portion 90.

[0110] Figure 13b A schematic side view showing the application of the asymmetric multi-point drill bit 4 according to one embodiment of the present application to a saw drill bit. The saw drill bit has a shank 1 for fixing the saw drill bit and a working portion 2 for hole machining adjacent to the shank 1. The working portion 2 has a frontmost asymmetric multi-point drill bit 4 according to the present application and a reaming portion 90 behind the drill bit 4 and directly adjacent to it, which is capable of reaming to a desired hole diameter for machining a sheet. Based on the asymmetric multi-point drill bit 4 according to the present application, the saw drill bit can efficiently cut into a workpiece and finally complete drilling. Here, the chip flutes 3 extend successively through the multi-point drill bit 4 and the reaming portion 90. Figure 13a A detailed view of the asymmetric multi-point drill bit of the twist drill in

[0111] In addition, it is also conceivable to apply such an asymmetric multi-point drill bit 4 to other hole machining drill bits for other hole machining combinations.

[0112] In combination with the above description of the embodiments of the present application, the features or beneficial technical effects of the asymmetric multi-point drill bit 4 of the present application include but are not limited to:

[0113] 1) The simultaneous and symmetrical cutting of the symmetrical cutting edge of the symmetrical multi-point drill part 4 is changed to staggered cutting, so that the cutting edge cuts non-simultaneously and asymmetrically to form a composite cutting effect.

[0114] 2) Improves the problem of resonance caused by the symmetrical distribution of cutting forces in the symmetrical multi-tip drill section 4, making the cutting of the tool smooth and extending and improving the tool life.

[0115] 3) Compared with the symmetrical multi-tip drill section 4 which has the same number of stepped sections Tn, the number of stepped sections Tn participating in actual cutting is increased during actual cutting, which refines and disperses the metal cutting allowance, reduces the power of power tools, and especially reduces physical strength and efficiency during hand-held processing.

[0116] 4) The axially misaligned structure allows for a longer axial spacing between adjacent cutting edges on the same side, increasing chip capacity and making chip removal smoother. Especially at small-diameter steps, where the chip groove 3 is narrow and chip removal is difficult, the misaligned cutting edges increase the spacing between adjacent cutting edges on the same side, thus providing a larger chip space and facilitating chip removal.

[0117] 5) The cutting edges at the larger diameter steps are symmetrically arranged, which makes the radial cutting of the main cutting edge 7, which bears a larger cutting force, balanced, stabilizes the working rotation axis 10 during drilling, avoids the axial deviation of the hole, and ensures the dimensional accuracy of the hole diameter.

[0118] A significant feature of the asymmetric multi-tip drill bit 4 according to the present invention is that at least one symmetrical cutting edge of the prior art is changed to a misaligned cutting edge, which brings the following beneficial effects:

[0119] 1) Throughout the cutting process, the cutting force is small, uniform, and reasonable, and chip removal is smooth.

[0120] 2) Manual handheld power tools with asymmetrical multi-point drill bit 4 are more stable, consume less power, and can be operated for a long time.

[0121] 4) The cutting edge wear of each step section Tn of the tool is uniform and consistent, which extends the tool's service life.

[0122] 5) It reduces unnecessary damage to cutting tools and scrap of workpieces during use.

[0123] 6) Reduced processing difficulty and cost, and improved processing efficiency.

[0124] 7) The knife strokes are smooth and steady.

[0125] The present application can include any feature or combination of features disclosed herein or any generalisation thereof, without limitation to the forgoing disclosed principles of the application. Any of the elements, features and / or structures described herein can be combined in any suitable manner.

[0126] The particular embodiments disclosed above are illustrative only, as the present application can be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Accordingly, departures in form and detail are considered to be within the scope and spirit of the present application.

Claims

1. A drilling section for a hole-machining tool, characterized in that, The drilling section includes: At least two chip removal grooves are arranged circumferentially spaced apart in the drilling section. Multiple sides, each defined circumferentially by two adjacent chip removal grooves, wherein each side includes multiple stepped segments arranged sequentially in the feed direction, and each stepped segment includes a first segment and a second segment directly adjacent to the first segment, wherein, when the stepped segments of each side are sequentially numbered against the feed direction, all stepped segments of the same number on all sides constitute the same stepped segment, and each side also includes a transition segment following all stepped segments. Multiple main cutting edges, each formed by the intersection of a chip removal groove, the first segment of a stepped section, and a transition section. Multiple secondary cutting edges, wherein each secondary cutting edge is formed by the intersection of a chip removal groove and the second segment of each stepped section, and Multiple cutting edges, each formed by the intersection of a main cutting edge and a secondary cutting edge formed by the same chip groove and the same stepped section. Wherein, at least one of the stepped sections is configured as an asymmetrical stepped section, and the same asymmetrical stepped section has at least two asymmetrical stepped section portions separated by chip removal grooves in the circumferential direction. The at least two asymmetrical stepped section portions and the at least two chip removal grooves respectively form at least two asymmetrical cutting tips that are not rotationally symmetric about the working rotation axis. The at least two asymmetrical cutting tips therefore have radial distances from each other from the working rotation axis and are axially offset from each other in the direction of the working rotation axis.

2. The drilling part according to claim 1, characterized in that, The drilling section is configured as the foremost drilling section of a hole machining tool, wherein the first step section at the foremost point of the step section is configured as the drill tip section, and the point at the foremost point of the drill tip section along the feed direction is configured as the drill tip apex. Each asymmetrical cutting tip on the same asymmetrical step section has an axial distance from the drill tip apex that is different from each other.

3. The drilling part according to claim 2, characterized in that, The individual cutting tips of the drill tip section are configured to be rotationally symmetric about the working rotation axis, and therefore have the same radial distance from the working rotation axis and the same axial distance from the drill tip apex.

4. The drilling part according to claim 3, characterized in that, In the drill section, among the step sections following the drill tip section, at least one of the first half of the step sections constitutes an asymmetrical step section.

5. The drilling part according to claim 4, characterized in that, In the drill section, among the step sections following the drill tip section, at least two directly adjacent step sections in the first half constitute an asymmetrical step section.

6. The drilling part according to claim 5, characterized in that, The two adjacent stepped sections of the drilling section, which are immediately following the drill tip section, constitute an asymmetrical stepped section.

7. The drilling part according to claim 4, characterized in that, The step section immediately following the drill tip section of the drilling section is an asymmetrical step section.

8. The drilling part according to claim 3, characterized in that, The plurality of side portions each have the same number of stepped sections, wherein, in each of the stepped sections after the drill tip section in the drilling portion, at least one of the stepped sections in the latter half of the stepped sections is configured as a symmetrical stepped section, wherein each cutting tip on the symmetrical stepped section is configured to have the same radial distance from each other from the working rotation axis and the same axial distance from each other from the drill tip apex.

9. The drilling part according to claim 8, characterized in that, In the drill section, in each step section after the drill tip section, at least two directly adjacent step sections in the latter half of the step sections constitute symmetrical step sections.

10. The drilling part according to claim 9, characterized in that, In the drill section, after the drill tip section, the last two directly adjacent step sections in the latter half of the step sections constitute symmetrical step sections.

11. The drilling part according to claim 8, characterized in that, The last step section of the drilling section is a symmetrical step section.

12. The drilling part according to claim 1, characterized in that, At least two sides have different numbers of stepped segments, wherein the cutting tip on a stepped segment of one side and the cutting tip on a stepped segment of another side with a different number have the same radial distance from the working axis of rotation and are not axially offset from each other in the direction of the working axis of rotation.

13. The drilling part according to claim 12, characterized in that, The cutting tips on the final stepped sections of the at least two sides have the same radial distance from each other from the working axis of rotation and are not axially offset from each other in the direction of the working axis of rotation.

14. The drilling part according to claim 1, characterized in that, The transition sections on each side have the same radial distance from each other from the working rotation axis and are not axially offset from each other in the direction of the working rotation axis.

15. The drilling part according to claim 1, characterized in that, The first segment is configured as a truncated cone segment and the second segment is configured as a cylindrical segment; or, the first segment and / or the second segment is configured as a curved surface segment.

16. The drilling part according to claim 1, characterized in that, The number of stepped sections in the drilled part is greater than or equal to 3.

17. The drilling part according to claim 16, characterized in that, The number of stepped sections in the drilled part is greater than or equal to 5.

18. The drilling part according to claim 2, characterized in that, The included angle between the main cutting edges of the drill tip section is greater than the cone angle of the conical drill section.

19. The drilling part according to claim 18, characterized in that, The included angle between the main cutting edges of the drill tip section is an obtuse angle, and the cone angle of the drilled section is an acute angle.

20. The drilling part according to claim 1, characterized in that, The chip removal groove is either straight or spiral.

21. The drilling part according to claim 1, characterized in that, At least one main cutting edge is configured as a multi-segment edge, each segment being either straight or curved.

22. A hole-machining tool, characterized in that, The hole-making tool has a shank for fixing the hole-making tool and a working part for hole-making in front of the shank, the working part having a drilling part located at its foremost end according to any one of claims 1 to 21.

23. The hole-making tool according to claim 22, characterized in that, The hole-making tool is configured as a twist drill, the working part having a guide portion adjacent to the shank and a drilling portion adjacent to the guide portion in front of the guide portion, wherein the chip removal groove extends over at least a portion of the guide portion.

24. The hole-making tool according to claim 23, characterized in that, The chip removal groove extends over most of the guide portion.

25. The hole-making tool according to claim 22, characterized in that, The hole-making tool is configured as a pagoda drill, and the working part includes a plurality of stepped drilling / reaming parts arranged sequentially along the feed direction with increasing diameter, wherein the foremost first drilling part is provided with the drilling part.

26. The hole-making tool according to claim 22, characterized in that, The hole machining tool is configured as an integrated chamfering and drilling drill bit. The working part has a drilling part at the foremost end, a step hole drilling part for drilling a step hole that is axially spaced after and separated from the drilling part, and a hole chamfering part for chamfering the drilled step hole that is axially spaced after and separated from the step hole drilling part.

27. The hole-making tool according to claim 22, characterized in that, The hole-making tool is configured as a compound tap drill bit, the working part having a drilling part at the foremost end, a tapping part for tapping the hole after the drilling part and spaced apart from it by an axial distance, and a hole chamfering part for chamfering the hole after the tapping part and spaced apart from it by an axial distance.

28. The hole-making tool according to claim 22, characterized in that, The hole-making tool is configured as an umbrella-shaped drill bit, and the working part has a drilling part at the foremost end and a reaming part that is located behind and directly adjacent to the drilling part.

29. The hole-making tool according to claim 22, characterized in that, The hole-making tool is configured as a saw drill bit, the working part having a frontmost drilling part and a sawtooth working part that is axially spaced behind and from the drilling part.

Images