Drilling part of hole machining tool and hole machining tool

Abstract

A drilling part of a hole machining tool and a hole machining tool. The drilling part (4) comprises: at least two flutes (3); a plurality of side parts, each side part comprising a plurality of step section (Tn) portions, step section portions on all side parts belonging to a same serial number forming a same step section, and each side part further comprising a transition section portion (12); a plurality of major cutting edges (7); a plurality of minor cutting edges (8); and a plurality of cutting tips (9). At least one step section is configured as an asymmetrical step section, a same asymmetrical step section has in the circumferential direction at least two asymmetrical step section portions which are separated by the flutes, the at least two asymmetrical step section portions and at least two flutes correspondingly form at least two asymmetrical cutting tips, the at least two asymmetrical cutting tips have different radial distances (ri,ri ') from the working rotation axis and are axially staggered relative to each other in the direction of the working rotation axis. The drilling part and the hole machining tool avoid the offset of the working rotation axis, ensure the size precision of the final hole diameter, and avoid the generation of cutting resonance of the same frequency and period.

Description

Drilling unit for hole machining tool and hole machining tool Technical Field

[0001] The present invention relates to the field of mechanical processing, in particular to a drilling part for a hole processing tool and a hole processing tool. Background Art

[0002] A multi-tip drilling section is a drilling section used for drilling. It forms part of a hole-making tool and has multiple cutting edges along the working axis of rotation on each flute. For example, a multi-tip drilling section can be used as the front end of a twist drill to perform drilling tasks.

[0003] In this regard, the applicant disclosed a high-efficiency twist drill in its prior patent document (WO2017136966A1). Referring to Figures 1a and 1b, the twist drill comprises a shank 1 and a working portion 2, the working portion 2 having the aforementioned multi-edge drilling portion 4 at its front end. The drilling portion 4 is formed by a plurality of stepped sections Tn (n = 1, 2, 3, ..., i, ...) with increasing diameters opposite to the feed direction, and each stepped section Tn includes a truncated cone section 5 and a cylindrical section 6 directly adjacent thereto. Two spiral chip flutes 3 extend through the drilling portion 4. Each chip flute 3 intersects with the surface of the truncated cone section 5 of each stepped section Tn to form a primary cutting edge 7, and intersects with 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 secondary cutting edge 8 formed by the intersection of the same chip flute 3 of the same stepped section Tn further intersect to form a cutting edge 9. Therefore, the multiple step sections Tn form multiple cutting edges 9. The multiple cutting edges 9 formed by the same chip flute 3 and different step sections Tn are distributed on a tapered spiral line around the working rotation axis 10 or the central axis 10 of the drilling part 4. Therefore, the above-mentioned drilling part 4 is called a multi-edge drilling part 4.

[0004] Referring to Figures 1a and 1b , the two primary and secondary cutting edges 7 / 8, or cutting tips 9, formed by the same step section Ti of the drilling portion 4 and the two chip flutes 3 are symmetrical or rotationally symmetrical about the working rotation axis 10 of the drilling portion 4. Therefore, as shown in the twist drill view in the direction K in Figure 1b , the two radii ri, ri (i = 1, 2, 3, ...) measured at the two cutting tips 9 of the same step section Ti of the drilling portion 4 are equal and are half the diameter di of the step section Ti, i.e., ri = ri = di / 2. Here, the radii ri, ri of the cutting tips 9 can be understood as the distance between the cutting tips 9 and the working rotation axis 10 of the drilling portion 4. Furthermore, as shown in Figure 1a , the axial lengths Li, Li from the two cutting tips 9 on the same step section Ti to the drill tip apex 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° in the circumferential direction, on all step sections Tn simultaneously participate in cutting. The two main cutting edges 7 produce equal cutting amounts and forces, which easily leads to resonance with the same frequency and period. This also results in high cutting resistance, especially in small step sections where the chip flutes 3 are narrow, making chip removal difficult.

[0006] Summary of the Invention

[0007] Therefore, the present invention provides 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.

[0008] According to one aspect of the present invention, a drilling portion for a hole machining tool is provided, characterized in that the drilling portion for a hole machining tool comprises:

[0009] at least two chip flutes, which are arranged spaced apart in the circumferential direction of the drilling portion,

[0010] A plurality of side portions, each side portion being delimited by two adjacent chip flutes in a circumferential direction, wherein each side portion comprises a plurality of step section portions arranged successively in a feed direction, and each step section portion comprises a first section and a second section directly adjacent to the first section, wherein, when the step section portions of each side portion are numbered sequentially relative to the feed direction, the step section portions belonging to the same sequence number on all the side portions constitute the same step section, wherein each side portion further comprises a transition section portion following all the step section portions,

[0011] A plurality of main cutting edges are formed by the intersection of each chip flute with the first section of each step section and each transition section.

[0012] a plurality of secondary cutting edges formed by the intersection of each chip flute and the second section of each step section, and

[0013] A plurality of cutting edges, each formed by the intersection of a main cutting edge and a secondary cutting edge formed by the same chip flute and the same step section.

[0014] In which, at least one of the step sections is constructed as an asymmetric step section, and the same asymmetric step section has at least two asymmetric step section parts separated by a chip groove in the circumferential direction, and the at least two asymmetric step section parts and the at least two chip grooves respectively form at least two asymmetric cutting edges that are not rotationally symmetrical about the working rotation axis. Therefore, the at least two asymmetric cutting edges have different radial distances from the working rotation axis and are axially staggered relative to each other in the direction of the working rotation axis.

[0015] The drilling section of a hole-making tool can achieve technical benefits including, but not limited to: The asymmetric stepped section of the drilling section enables staggered cutting, resulting in a composite cutting effect where the cutting edges cut non-simultaneously and asymmetrically, gradually disaggregating the amount of metal removed. This improves drilling efficiency and reduces effort. Furthermore, because the cutting force is not strictly symmetrically distributed around the circumference, it prevents the generation of cutting resonances with the same frequency and period.

[0016] Advantageously, the drilling portion is configured as the drilling portion located at the front end of the hole processing tool, wherein the first step section located at the front end of the step sections is configured as a drill tip section, the point of the drill tip section located at the front end along the feed direction is configured as the drill tip apex, and the asymmetric cutting edges on the same asymmetric step section have different axial distances from the drill tip apex.

[0017] Advantageously, the individual cutting tips of the drill tip segments are designed rotationally symmetrically with respect to 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 tip apex.

[0018] Advantageously, among the step sections following the drill tip section of the drilling portion, at least one step section in the first half is configured as an asymmetric step section. This means that, if all step sections (including the frontmost drill tip section) are numbered sequentially against the feed direction, at least one step section in the first half of all step sections following the drill tip section is configured as an asymmetric step section. For example, for a drilling portion having five step sections (including the frontmost drill tip section), the "first half" is (5-1) ÷ 2 = 2, meaning at least one step section in the second and third step sections is configured as an asymmetric step section. For a drilling portion having six step sections (including the frontmost drill tip section), the "first half" is (6-1) ÷ 2 = 2.5 ≈ 3, meaning at least one step section in the second, third, and fourth step sections is configured as an asymmetric step section. And so on.

[0019] Advantageously, among the step sections of the drilling portion following the drill tip section, at least two step sections directly adjacent to each other among the first half of the step sections are formed as asymmetrical step sections.

[0020] Advantageously, two step sections of the drilling part that are directly adjacent to the drill tip section are designed as asymmetrical step sections.

[0021] Advantageously, the step section of the drilling portion adjoining the drill tip section is formed as an asymmetrical step section.

[0022] Advantageously, the plurality of side portions each have the same number of step sections, wherein, among the step sections of the drilling portion following the drill tip section, at least one step section in the last half of the step sections is configured as a symmetrical step section, and the cutting edges in the symmetrical step sections are configured to have the same radial distance from the working rotation axis and the same axial distance from the drill tip apex. This means that all step sections (including the frontmost drill tip section) are numbered sequentially against the feed direction, and at least one step section in the last half of all step sections following the drill tip section is configured as a symmetrical step section. For example, for a drilling portion having five step sections (including the frontmost drill tip section), the "second half" is (5-1) ÷ 2 = 2, meaning that at least one of the fourth and fifth step sections is a symmetrical step section. For a drilling portion having six step sections (including the frontmost drill tip section), the "second half" is (6-1) ÷ 2 = 2.5 ≈ 3, meaning that at least one of the fourth, fifth, and sixth step sections is a symmetrical step section. And so on.

[0023] Advantageously, among the step sections of the drilling portion following the drill tip section, at least two step sections directly adjacent to each other among the last half of the step sections are formed as symmetrical step sections.

[0024] Advantageously, among the step sections of the drilling portion following the drill tip section, the last two step sections directly adjacent to each other among the last half of the step sections are formed as symmetrical step sections.

[0025] Advantageously, the last step section of the drilling portion is designed as a symmetrical step section.

[0026] Advantageously, at least two sides have different numbers of step section parts, and among the at least two sides, the cutting edge on a step section part of one side and the cutting edge on a step section part of the other side with a different serial number from the one step section part 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.

[0027] Advantageously, the cutting edges on the last step section portions of the at least two side portions have the same radial distance from the working rotation axis and are arranged axially without offset relative to each other in the direction of the working rotation axis.

[0028] Advantageously, the transition section parts of each side (or the main cutting edges thereon, such as the front and / or rear ends of the main cutting edges) have the same radial distance from each other from the working rotation axis and are not axially offset relative to each other in the direction of the working rotation axis.

[0029] Advantageously, the first segment is configured as a truncated cone segment and the second segment is configured as a cylindrical segment; alternatively, the first segment and / or the second segment are configured as curved segments.

[0030] Advantageously, the number of the step sections of the drilling portion is greater than or equal to three.

[0031] Advantageously, the number of the step sections of the drilling portion is greater than or equal to 5.

[0032] Advantageously, the included angle between the main cutting edges of the drill tip segments is larger than the cone angle of the conical drilling portion.

[0033] Advantageously, the included angle between the main cutting edges of the drill tip segments is an obtuse angle, and the taper angle of the drilling portion is an acute angle.

[0034] Advantageously, the chip flutes are linear or spiral.

[0035] Advantageously, at least one main cutting edge is configured as a multi-segmented edge, each edge segment being straight or arcuate.

[0036] According to another aspect of the present invention, a hole processing tool is proposed, characterized in that the hole processing tool has a shank for fixing the hole processing tool and a working part for hole processing in front of the shank, and the working part has a drilling part according to the present invention located at its front end.

[0037] Advantageously, the hole-making tool is designed as a twist drill, the working part having a guide portion adjoining the shank and the drilling part adjoining the guide portion in front of the guide portion, wherein the chip flute extends over at least part of the guide portion.

[0038] Advantageously, the chip flutes extend over a large portion of the guide portion.

[0039] Advantageously, the hole processing tool is configured as a pagoda drill, and the working portion comprises a plurality of stepped drilling / reaming portions arranged successively along the feed direction and with increasing diameters, wherein the first drilling portion at the front is provided with the drilling portion.

[0040] Advantageously, the hole processing tool is configured as a chamfering and drilling integrated drill bit, the working portion having the drilling portion at the front end, a step hole drilling portion for drilling a step hole behind the drilling portion and separated from it by an axial distance, and a hole chamfering portion for chamfering the drilled step hole behind the step hole drilling portion and separated from it by an axial distance.

[0041] Advantageously, the hole processing tool is configured as a compound tap drill, the working part having the drilling part at the front end, a tapping part behind the drilling part and separated from the drilling part by an axial distance for tapping the hole, and a hole chamfering part behind the tapping part and separated from the drilling part by an axial distance for chamfering the hole.

[0042] Advantageously, the drilling tool is designed as an umbrella drill, the working part having the drilling part at the front end and a reaming part behind and directly adjacent to the drilling part.

[0043] Advantageously, the hole machining tool is configured as a saw drill bit, and the working portion comprises the drilling portion at the front end and a sawtooth working portion located behind the drilling portion and spaced apart from the drilling portion at an axial distance.

[0044] The technical features mentioned above and the technical features to be mentioned below, as well as the technical features shown in the drawings, may be combined with each other arbitrarily, as long as the combined technical features do not contradict each other. All technically feasible feature combinations are included in the technical content of the description. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The present invention will be further described below with reference to the accompanying drawings using exemplary embodiments, wherein:

[0046] FIG1a shows a schematic side view of a twist drill having a symmetrical multi-edge drilling portion in the prior art;

[0047] FIG1b is a schematic diagram showing the twist drill in FIG1a as viewed from the direction k in FIG1a;

[0048] FIG2 a shows a schematic side view of an asymmetric multi-edge drilling portion applied to a twist drill according to an embodiment of the present invention;

[0049] FIG2 b shows a schematic diagram of the twist drill in FIG2 a viewed from the direction k in FIG2 a ;

[0050] FIG3 a is a schematic side view showing the application of an asymmetric multi-edge drilling portion on a twist drill according to another embodiment of the present invention, mainly showing the drilling portion;

[0051] FIG3 b shows a schematic diagram of the twist drill in FIG3 a viewed from the direction k in FIG3 a ;

[0052] FIG4 shows a schematic longitudinal sectional view of the asymmetric multi-edge drilling portion in FIG3a;

[0053] FIG5 is a schematic longitudinal sectional view of the asymmetric multi-edge drilling portion in FIG3a, illustrating the compound cutting effect of the asymmetric step section;

[0054] FIG6 shows a schematic longitudinal sectional view of the asymmetric multi-edge drilling portion in FIG3a, which also illustrates the compound cutting effect of the asymmetric step section;

[0055] FIG7 a shows a schematic longitudinal sectional view of an asymmetric multi-edge drilling portion according to yet another embodiment of the present invention;

[0056] FIG7 b shows a schematic longitudinal sectional view of the asymmetric multi-edge drilling portion in FIG7 a , illustrating the compound cutting effect of the asymmetric step section;

[0057] FIG8 is a schematic side view showing the application of an asymmetric multi-edge drilling portion on a pagoda drill according to one embodiment of the present invention;

[0058] FIG9 is a schematic side view showing an application of an asymmetric multi-edge drilling portion on a chamfering and drilling integrated drill bit according to one embodiment of the present invention;

[0059] FIG10 is a schematic side view showing an application of an asymmetric multi-edge drilling portion on a composite tap drill bit according to an embodiment of the present invention;

[0060] FIG11 is a schematic side view showing an application of an asymmetric multi-edge drilling portion on an umbrella drill bit according to an embodiment of the present invention;

[0061] FIG12 is a schematic side view showing an application of an asymmetric multi-edge drilling portion on a saw drill bit according to one embodiment of the present invention;

[0062] FIG13 a is a schematic side view showing an application of an asymmetric multi-edge drilling portion on a twist drill according to another embodiment of the present invention; and

[0063] FIG. 13 b shows a detailed view of the asymmetrical multi-edge drilling portion of the twist drill in FIG. 13 a . DETAILED DESCRIPTION

[0064] An illustrative embodiment of an asymmetric (or non-rotationally symmetric) multi-edge drilling section 4 according to the present invention is described below. In this description, various systems, structures, and devices are schematically depicted in the accompanying drawings for purposes of explanation only. 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 obscuring the present invention with unnecessary detail. It should be understood that in any actual application, many specific implementation decisions need to be made to achieve the specific goals of the developer or user, and to comply with system-related and industry-related constraints, which may vary from application to application. Furthermore, it should be understood that such specific implementation decisions, while complex and time-consuming, are routine tasks for those of ordinary skill in the art who benefit from the present disclosure.

[0065] The terms and phrases used herein should be understood and interpreted as having a meaning consistent with the understanding of those terms and phrases by those skilled in the relevant art. No special definition of a term or phrase, i.e., a definition that is different from the ordinary and customary meaning as understood by those skilled in the art, is intended to be implied by consistent usage of a term or phrase herein. For terms or phrases that are intended to have a special meaning, i.e., a meaning that is different from that understood by those skilled in the art, such special definition will be explicitly set forth in the specification as a definition, directly and unambiguously giving the special definition of the term or phrase.

[0066] Unless the content requires otherwise, throughout the following description, the word "include" and variations such as "comprising" and "having" are to be interpreted in an open and inclusive sense, that is, as in "including but not limited to".

[0067] Next, an illustrative embodiment of the asymmetrical multi-edge drilling part 4 and its application according to the present invention will be described with reference to the schematic figures 2a to 6. For components corresponding to those in the embodiment shown in figures 1a and 1b, the same reference numerals are used.

[0068] Figures 2a and 2b show an embodiment of an asymmetric multi-edge drilling portion 4 according to the present invention. The drilling portion 4 is used as a front drilling portion 4 of a twist drill for drilling holes with the twist drill. The twist drill includes a shank 1 and a working portion 2 connected to the shank 1. The working portion 2 includes a cylindrical guide portion 11 connected to the shank 1 and a conical drilling portion 4 connected to the guide portion 11. The chip flute 3 extends over the entire drilling portion 4 and partially extends over the guide portion 11. Here, the chip flute 3 is a spirally extending chip flute 3. In other embodiments, linear chip flutes 3 are also conceivable. The number of chip flutes 3 here is two. In other embodiments, more than two chip flutes 3 (for example, 3, 4, ...) are also conceivable.

[0069] The drilling portion 4 includes a plurality of stepped sections Tn (n = 1, 2, 3, ..., i, ..., 9) with increasing diameters counter to the feed direction. Each stepped section Tn comprises a truncated cone section 5 and a subsequent cylindrical section 6. Nine stepped sections are provided herein, but other embodiments may include a different number of stepped sections Tn (e.g., 2, 3, 4, 5, 6, 7, 8, 10, ...). A circumferentially extending stepped groove 20 with a generally V-shaped cross section is formed between each pair of adjacent stepped sections Tn-1 and Tn. Each stepped groove 20 is bounded by the cylindrical section 6 of the preceding step section Tn-1 and the truncated cone section 5 of the following step section Tn. In other embodiments, the following cylindrical section 6 may be replaced with a truncated cone section having a smaller taper angle than the truncated cone section 5. Each chip flute 3 intersects with the surface of the truncated cone section 5 of each step segment Tn to form a major cutting edge 7, and intersects with the surface of the cylindrical section 6 of each step segment Tn to form a minor cutting edge 8. The major cutting edge 7 and minor cutting edge 8 formed by the intersection of the same chip flute 3 of the same step segment Tn intersect to form a cutting edge 9. Thus, multiple step segments Tn form multiple cutting edges 9. The multiple cutting edges 9 formed by the same chip flute 3 and different step segments Tn are distributed along a tapered spiral extending around the working rotation axis 10 of the drilling portion 4. Therefore, the drilling portion 4 is referred to as a multi-cutting-edge drilling portion 4 (formed by multiple step segments Tn). Two chip flutes 3 form a pair of major cutting edges 7 and minor cutting edges 8 with the same step segment Tn, respectively. Each pair of major cutting edges 7 and minor cutting edges 8 forms a cutting edge, thus forming two cutting edges 9 distributed circumferentially on the same step segment Tn.

[0070] As for the main cutting edge 7, referring to the embodiment shown in Figures 2a and 2b, the main cutting edge 7 on each step section Tn can be configured as a single-stage type, and the single-stage edge can be straight or curved. However, in some embodiments not shown, at least one of the main cutting edges 7 can also be configured as a multi-stage type, and each segment can be straight or curved. The multi-stage main cutting edge 7 includes at least two main cutting edge segments, and an angle (not 0 degrees or 180 degrees) can be formed between two adjacent main cutting edge segments. This can further decompose the chips, reducing chip force and cutting heat.

[0071] In this embodiment, the first stepped section T1 at the front end of the drilling portion 4 constitutes the smallest diameter drill tip section T1 of the twist drill. The two main cutting edges 7 of the drill tip section are configured as straight or linear main cutting edges 7. The obtuse angle formed between these two main cutting edges 7 corresponds to the main cutting edge angle of a conventional twist drill without multiple stepped sections and is greater than the taper angle α (see FIG. 2 a ) of the overall conical drilling portion 4. The taper angle α is preferably an acute angle, but a right angle or an obtuse angle is also conceivable. With this configuration, the small-diameter drill tip section serving as the first stepped section T1 has excellent centering properties, and the cylindrical section 6 of the drill tip section serves as the centering axis after engaging the workpiece. As the asymmetrical cutting edges of subsequent stepped sections Tn (where n>1), particularly those with offset structures (described in more detail below), gradually engage the workpiece, the stepped cylindrical section 6 of the drill tip provides sufficient centering, preventing the working rotation axis 10 from shifting. As with conventional twist drills, the top edge of the drill tip section is composed of two straight main cutting edges 7, two auxiliary cutting edges, and a chisel edge 25. The two straight main cutting edges 7 intersect at the ends of the chisel edge 25 at the front end, so the chisel edge 25 is located at the front end of the drill tip section.

[0072] Here, the drill tip apex 13 is the point at the front end of the drill tip in the feed direction or in the direction of the working rotational axis. This point is also the front-most or distal-most point of the drill tip section that serves as the first step section T1. At the start of drilling, the drill tip apex 13 is the portion of the drill tip that first contacts the workpiece. It is conceivable that the drill tip apex 13 could be located on the chisel edge 25, or at 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, any point on the chisel edge 25 could be considered the drill tip apex 13.

[0073] The drilling portion 4 further includes a transition section 12 that transitions from the last step section T9 (or its cylindrical section 6) to the adjacent portion of the hole machining tool, here, the guide section 11. This 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 section 11. This transition section 12 also forms the main cutting edge 7 with the chip flute 3.

[0074] In the present invention, the generally conical drilling portion 4 is divided circumferentially into a plurality of generally arcuate side portions by a plurality of chip flutes 3, each of which is circumferentially bounded by two adjacent chip flutes 3. Each side portion of the drilling portion 4 includes a plurality of stepped sections (or stepped section portions) whose diameters increase progressively against the feed direction, and each stepped section comprises a truncated cone section 5 and an adjacent cylindrical section 6. Furthermore, each side portion of the drilling portion 4 includes a transition section 12 located last in the feed direction, each of which is also circumferentially bounded by two adjacent chip flutes 3.

[0075] To facilitate the description and understanding of the present invention, it is defined herein that, even if the step sections of each side are sequentially numbered against the feed direction, all step sections on each side with the same sequence number are still defined as constituting a step section Tn (n = 1, 2, 3, ..., i, ..., 9). For further explanation, using the embodiment shown in Figures 2a and 2b, the drilling portion 4 is circumferentially divided into two generally arcuate side sections by two chip flutes 3. Therefore, each side section is circumferentially bounded by the two chip flutes 3. Each side of the drilling portion 4 includes nine step sections with increasing diameter against the feed direction, and each step section comprises a truncated cone section 5 and an adjacent cylindrical section 6. The step sections of the two sides are sequentially numbered 1, 2, 3, ..., i, ..., 9 against the feed direction, and two step sections on the two sides with the same sequence number i are defined as constituting a step section Ti (i = 1, 2, 3, ..., 9). This is irrelevant to whether the two step sections with the same number i are rotationally symmetrical with respect to the working rotation axis. In addition, the two side portions of the drilling portion 4 each include a transition section 12 located at the end in the feed direction, so each transition section 12 is circumferentially delimited by the two adjacent chip flutes 3.

[0076] 2a and 2b , the two step section parts (also referred to as step section halves herein) of the same step section Ti (the third step section T3 is schematically indicated herein) of the drilling portion 4 separated by two chip grooves 3 are not symmetrical about the working rotation axis 10 of the drilling portion 4.

[0077] Specifically, the radius ri of the cylindrical section 6 of the step section portion located on the first side of the asymmetric step section Ti (facing the inside of the paper in FIG. 2a and on the left side in FIG. 2b ) is greater than the radius ri' of the cylindrical section 6 of the step section portion located on the second side of the step section Ti (facing the outside of the paper in FIG. 2a and on the right side in FIG. 2b ), that is, ri>ri', and the axial length Li of the cylindrical section 6 of the step section portion located on the first side of the step section Ti (or its front end) from the drill tip apex 13 is greater than the axial length Li' of the cylindrical section 6 of the step section portion located on the second side of the step section Ti (or its front end) from the drill tip apex 13, that is, Li>Li'. In other words, the step section portion with a smaller radius in the same step section is located axially closer to the drill tip apex 13.

[0078] In other words, the two cutting edges 9 formed by the same step section Ti and the two chip flutes 3 are not symmetrical about the working rotation axis 10 of the drilling portion 4. Specifically, the radius ri of the cutting edge 9 of the step section portion located on the first side of the step section Ti is greater than the radius ri' of the cutting edge 9 of the step section portion located on the second side of the step section Ti, that is, ri>ri', and the axial length Li of the cutting edge 9 of the step section portion located on the first side from the drill tip apex 13 of the step section Ti is greater than the axial length Li' of the cutting edge 9 of the step section portion located on the second side from the drill tip apex 13 of the step section Ti, that is, Li>Li'.

[0079] Therefore, on the one hand, referring to FIG2b , the two radii ri and ri' (here i = 3) measured at the two cutting edges 9 of the same step section Ti of the drilling portion 4 are unequal and neither equals half the measured diameter di' of the step section Ti, i.e., ri ≠ ri' ≠ di' / 2, but ri + ri' = di'. Here, the radii ri and ri' of the cutting edge 9 can be understood as the distance between the cutting edge 9 and the working axis of rotation 10 of the drilling portion 4. On the other hand, referring to FIG2a , the axial lengths Li and Li' from the two cutting edges 9 on the same step section Ti to the drill tip apex 13 are also unequal, i.e., Li ≠ Li'.

[0080] This means that the two main cutting edges 7 on the two chip flutes 3 of the asymmetric step section Ti, which are distributed 180° in the circumferential direction, do not participate in cutting simultaneously when cutting the same workpiece cross-section. That is, they are cut sequentially or staggered in the axial direction. The main cutting edge 7 closer to the drill tip apex 13 cuts first, followed by the other main cutting edge 7 distributed 180° in the circumferential direction (that is, the main cutting edge 7 relatively far from the drill tip apex 13). As a result, the metal residue is gradually decomposed until a hole of the desired diameter is obtained. Therefore, when drilling a hole with this asymmetric multi-edge drilling portion 4, the amount of metal removed is gradually decomposed and cut because its cutting metal residue is reasonably distributed according to the size of the drill hole diameter, thereby avoiding the shortcomings of the symmetrical multi-edge drilling portion 4 shown in Figures 1a and 1b and making processing smoother. At the same time, drilling efficiency is higher and more labor-saving. In addition, due to the existence of the asymmetric step section Ti, the cutting force is not strictly 180° symmetrically distributed on the circumference, and thus no cutting resonance with the same frequency and period will be generated.

[0081] In the embodiment of the present invention shown in Figures 2a and 2b, only the asymmetric cutting edge structure on the third step section T3 of the drilling portion 4 is schematically indicated. However, this asymmetric cutting edge structure may also be provided on other or more step sections Tn. In other words, this asymmetric cutting edge structure may be provided on at least one step section Tn of the drilling portion 4.

[0082] Here, in each step section Tn (n>1) of the drilling portion 4 following the drill tip section T1 along the feed direction, the main cutting edge length on the step section with a smaller diameter can be shorter than the main cutting edge length on the step section with a larger diameter, but this is not mandatory and can also be considered longer than or equal to in practice.

[0083] 3 a to 6 , a specific application of the design concept of the present invention will be described in further detail by taking the drilling portion 4 having five step sections Tn as an example.

[0084] In the prior art, referring to Figures 1a and 1b, the radii of the cylindrical sections 6 or cutting tips 9 of the two step section portions of the same step section Ti of a symmetrical multi-edge drilling part 4 are the same and equal to half of the corresponding measuring / working diameter di, ri = ri = di / 2. However, referring to Figures 3a, 3b, and 4, the measuring radii ri, ri' of the cylindrical sections 6 or cutting tips 9 of the two step section portions of the same step section Ti (here i = 2, 3) of the asymmetrical multi-edge drilling part 4 of the present invention are different, and the measuring diameter dic of the step section Ti is equal to the sum of the two radii ri, ri' of the cylindrical sections 6 or cutting tips 9 of the two step section portions, i.e., dic = ri + ri'. In Figure 4, the measuring diameter d2c of the second step section T2, which is exemplarily marked, is shown, which is equal to the sum of the two measuring radii r2 and r2'. The actual working diameter dig of the step section Ti (ie, the maximum hole diameter that can be cut by the step section Ti) is equal to twice its maximum radius max{ri,ri'}, that is: dig = 2*max{ri,ri'}.

[0085] Furthermore, in the prior art, referring to Figures 1a and 1b , the cylindrical sections 6 or cutting edges 9 of the two stepped sections of the same stepped section Ti of the symmetrical multi-edge drilling portion 4 have equal axial lengths from the drill tip apex 13, i.e., Li = Li'. However, in this embodiment of the present invention, referring to Figure 3a , the cylindrical sections 6 or cutting edges 9 of the two stepped sections of the same stepped section Ti (here, i = 2, 3) of the asymmetric multi-edge drilling portion 4 of the present invention have unequal axial lengths from the drill tip apex 13, i.e., Li ≠ Li'. Instead, there is a certain axial offset ΔLi, where ΔLi = Li - Li'. Figure 4 exemplifies ΔL1 = l1' - l1.

[0086] In this embodiment, only the second and third step sections T2 and T3 are axially and radially offset, i.e., asymmetrically arranged, about the working axis of rotation 10. The first step section T1, the subsequent fourth step section T4, and the fifth step section T5, serving as the drill tip sections, are still symmetrically arranged about the working axis of rotation 10. Therefore, the measured diameters d1, d4, and d5 of the first, fourth, and fifth step sections T1, T4, and T5 are equal to their working diameters, while the measured diameters d2 and d3 of the second and third step sections T2 and T3 are not equal to their working diameters but are smaller than their working diameters dig (dig = 2*max{ri,ri'}, where i = 2 and 3). The radii of the cylindrical sections 6 or cutting tips 9 on different step section portions of each of the two step sections T2 and T3 are unequal, and the cylindrical sections 6 or cutting tips 9 are axially offset from one another. During operation, the two asymmetrical step sections T2, T3 can advantageously be combined (ie combined after multiple-edge cutting) to form four working steps T2.1, T2.2, T3.1, T3.2, which will be explained in more detail below, for example with reference to FIG. 5.

[0087] In addition, Figure 4 also shows the axial lengths l1, l2, l3, l4, l5 of the step section parts of each step section Tn of the drilling portion 4 located on the first side; the axial lengths l1', l2', l3', l4', l5' of the step section parts of each step section Tn of the drilling portion 4 located on the second side; the measured diameter d1<d2<d3<d4<d5 of each step section Tn; the radius differences δ2, δ3, δ4, δ5, δ2', δ3', δ4', δ5' of the cylindrical section 6 or the cutting edge 9 of the step section parts on the same side of adjacent step sections Tn, where δ2<δ2', δ5=δ5'; and the radius differences δ, δ' between the cylindrical section 6 of each step section part of the fifth step section T5 and the guide portion 11, where δ=δ'.

[0088] Next, reference is made to Figures 5 and 6, which schematically illustrate cross-sections of an asymmetrical multi-edge drilling section 4 taken along a plane parallel to the working axis of rotation 10. This illustrates the composite cutting effect of the asymmetrical second and third step sections T2 and T3 of the drilling section 4 according to the present invention, which combine to form four working step sections T2.1, T2.2, T3.1, and T3.2 during operation. The terms "upper" and "lower" below refer to the orientation of the structural features in Figures 5 and 6.

[0089] Specifically, for the asymmetrically arranged second step section T2, the radius r2 of the cylindrical section 6 or the cutting edge 9 below the second step section T2 is smaller than the radius r2' of the cylindrical section 6 or the cutting edge 9 above the second step section T2, and the axial distance between the front end of the cylindrical section 6 or the cutting edge 9 below the second step section T2 and the drill tip apex 13 is smaller than the axial distance between the front end of the cylindrical section 6 or the cutting edge 9 above the second step section T2 and the drill tip apex 13. Therefore, when the cutting edges 7 and 8 below the second step section T2 are hypothetically rotated 180 degrees upward about the central axis 10 and the cutting edges 7 and 8 above the second step section T2 are hypothetically rotated 180 degrees downward about the central axis 10, it can be seen (particularly referring to the first two dark black thick lines in the axial direction) that the main cutting edge 7 below the second step section T2 fully participates in cutting, while the main cutting edge 7 above the second step section T2 only partially participates in cutting. Thus, one second step section T2 itself produces the combined cutting effect of two working step sections T2.1, T2.2.

[0090] Similarly, for the asymmetrically arranged third step section T3, the radius of the cylindrical section 6 or the cutting edge 9 below the third step section T3 is smaller than the radius of the cylindrical section 6 or the cutting edge 9 above the second step section T3, and the axial distance between the front end of the cylindrical section 6 or the cutting edge 9 below the third step section T3 and the drill tip apex 13 is smaller than the axial distance between the front end of the cylindrical section 6 or the cutting edge 9 above the third step section T3 and the drill tip apex 13. Therefore, after imagining that the cutting edges 7 and 8 below the third step section T3 are rotated 180 degrees upward about the central axis 10 and the cutting edges 7 and 8 above the third step section T3 are rotated 180 degrees downward about the central axis 10 (particularly see the last two broken lines in the axial direction, dark black thick lines), it can be seen that the main cutting edge 7 below the third step section T3 only partially participates in cutting, and the main cutting edge 7 above the third step section T3 also only partially participates in cutting. Thus, one third step section T3 itself produces the combined cutting effect of two working step sections T3.1, T3.2.

[0091] Therefore, as can be seen from Figures 5 and 6, this drilling section 4 with five step sections Tn can be broken down or combined into seven step sections Tn during actual operation. This results in two additional working step sections Tn compared to a symmetrical drilling section 4 with five step sections Tn. The four working step sections T2.1, T2.2, T3.1, and T3.2, formed by combining the asymmetric second step section T2 and the asymmetric third step section T3, are also asymmetric in terms of measured dimensions. Their working diameters d2.1, d2.2, d3.1, and d3.2 differ from their measured diameters. Their working diameters d2.1, d2.2, d3.1, and d3.2 are twice the maximum of the two radii (ri or ri') at the working step sections T2.1, T2.2, T3.1, and T3.2, respectively, i.e., 2×max{ri,ri'}. For example, see the marking of the third working step section T2.2 in Figures 5 and 6, whose measured diameter is the sum of r2 and r2', but is smaller than its working diameter d2.2=2×r2'.

[0092] In this embodiment, the measured diameter d1 of the symmetrical first step section T1 , the measured diameter d4 of the symmetrical fourth step section T4 , and the measured diameter d5 of the symmetrical fifth step section T5 are their actual working diameters.

[0093] As can be seen from Figures 5 and 6, the working diameters d1, d2.1, d2.2, d3.1, d3.2, d4, and d5 of the seven working step sections Tn are progressively larger and smaller than the diameter d of the adjacent portion of the hole machining tool, here, the guide portion 11. The axial distances lg1, lg2.1, lg2.2, lg3.1, lg3.2, lg4, and lg5 between the rear ends of the cylindrical sections 6 of the seven working step sections Tn and the drill tip apex 13 are progressively larger.

[0094] As can be seen from Figures 5 and 6, the cutting edges 9 of the first step section T1 and the fourth and fifth step sections T4 and T5 are symmetrically distributed about the working rotation axis 10, that is, the cutting edges 9 on the same step sections T4 and T5 not only have the same radius, but also have the same axial distance from the drill tip apex 13, or there is no axial offset.

[0095] In this overall structure, the small-diameter drill tip section, which serves as the first stepped section T1, provides excellent centering performance and serves as the centering axis after engaging the workpiece. Furthermore, the radial distance (cutting radius) between the cutting edges of the second and third stepped sections T2 and T3 and the rotation axis 10 is small, resulting in a smaller cantilever and, consequently, a smaller force. Consequently, their asymmetric structure prevents significant eccentric forces from being applied to the drilling portion 4. Consequently, as the asymmetric cutting edges of the second and third stepped sections T2 and T3, with their offset structures, gradually engage the workpiece, the first stepped section T1 provides sufficient centering, preventing the working rotation axis 10 from shifting. The radial distance (cutting radius) between the cutting edges of the fourth and fifth step sections T4 and T5 and the axis is large, meaning the cantilever is large, resulting in greater force. Therefore, the cutting edges (or cutting tips 9) are designed to be symmetrically distributed. This allows the main cutting edge 7, which bears the greater cutting force, to achieve balance during radial cutting. This balances the cutting of the entire drilling section 4, stabilizes the working rotation axis 10 during drilling, avoids deviation of the working rotation axis 10, and ensures the dimensional accuracy of the final aperture. Furthermore, after the entire drilling section 4 has fully engaged the object being processed, the cutting edges of all step sections Tn operate simultaneously. Since the overall cutting force is not strictly 180° symmetrically distributed around the circumference, no cutting resonance with the same frequency and period is generated.

[0096] Furthermore, because the cutting edges of the asymmetric stepped sections T2 and T3 of the asymmetric multi-edge drilling portion 4 are axially misaligned on different stepped sections, the amount of metal to be removed is further broken down and refined during actual cutting. In this embodiment, each of the five stepped sections Tn has two stepped sections. When all are in operation (rotating), they effectively produce (cut) seven stepped holes, resulting in the tool's actual number of cutting edges (seven steps) exceeding the tool's actual number of cutting edges (five steps).

[0097] 6, due to the axial misalignment structure of the asymmetric step sections T2 and T3, the axial distances between the adjacent primary and secondary cutting edge pairs on the same chip flute 3 and the drill tip apex 13 have a distance difference of △l2=lg3.1-lg2.1 (i.e., the distance difference between the primary and secondary cutting edge pairs on the second working step section T2.1 and the fourth working step section T3.1), △l3=lg3.2-lg2.2 (i.e., the distance difference between the primary and secondary cutting edge pairs on the third working step section T2.2 and the fifth working step section T3.2). The difference in distance between the adjacent pairs of cutting edges on the same chip flute 3 is much larger than the distance difference △l2'=lg2.2-lg2.1 and △l3'=lg3.1-lg2.2 between the adjacent pairs of primary and secondary cutting edges on the same chip flute 3 and the drill tip apex 13 in the symmetrically distributed step structure of the symmetrical multi-edge drilling portion 4, that is, △l2=lg3.1-lg2.1 is much larger than △l2'=lg2.2-lg2.1, and △l3=lg3.2-lg2.2 is much larger than △l3'=lg3.1-lg2.2. This increases the chip removal space between adjacent pairs of cutting edges on the same side of the chip flute 3, making chip removal smoother. In particular, for the cutting edge at the small-diameter step section Tn, its cutting linear velocity is relatively low, and the chip outflow speed is also low. At the same time, its chip flute 3 is also relatively narrow due to its small diameter, so the chip removal of the cutting edge in the small-diameter step section Tn is relatively unsmooth. Due to the axially dislocated structure of the asymmetric multi-edge drilling portion 4 according to the present invention, the chip removal space between adjacent cutting edge pairs on the same chip flute 3 is increased, thereby improving the chip removal performance of the cutting edge of the small diameter step.

[0098] 7a and 7b, schematic longitudinal sectional views of an asymmetrical multi-edge drilling part 4 according to yet another embodiment of the present invention are shown.

[0099] In this embodiment, the drilling portion 4 is divided into two side portions in the circumferential direction by two chip flutes 3. Unlike the above embodiment, in this embodiment, the upper side portion of the drilling portion 4 includes three stepped sections T1, T2, and T3 with diameters increasing in the direction opposite to the feed direction and a transition section 12, while the lower side portion of the drilling portion 4 includes four stepped sections T1, T2, T3, and T4 with diameters increasing in the direction opposite to the feed direction and a transition section 12.

[0100] Here, all step sections with the same sequence number along the feed direction of each side are still defined as constituting a step section Tn (n = 1, 2, 3, 4). Specifically, the first, second, and third step section sections T1, T2, and T3 along the feed direction of the upper side and the first, second, and third step section sections T1, T2, and T3 along the feed direction of the lower side respectively form the first, second, and third step sections T1, T2, and T3; and the fourth step section section T4 along the feed direction of the lower side itself forms the fourth step section T4.

[0101] 7 a and 7 b , both step section portions of the second step section T2 and both step section portions of the third step section T3 of the drilling portion 4 are not symmetrical with respect to the working rotation axis 10 .

[0102] Specifically, the radius of the cylindrical section 6 (or the radial distance from the working rotation axis 10) of the upper step section portions of the second step section T2 and the third step section T3 is respectively greater than the radius of the cylindrical section 6 (or the radial distance from the working rotation axis 10) of the lower step section portions of the second step section T2 and the third step section T3, and the axial length from the cutting edge 9 of the upper step section portions of the second step section T2 and the third step section T3 to the drill tip apex 13 is respectively greater than the axial length from the cutting edge 9 of the lower step section portions of the second step section T2 and the third step section T3 to the drill tip apex 13. In other words, the step section portion with a smaller radius in the same step section is located closer to the drill tip apex 13 on the axis.

[0103] Figure 7b illustrates the composite cutting effect of the asymmetric second step section T2 and third step section T3. It can be seen that the asymmetric second and third step sections T2 and T3 are combined into four working step sections T2.1, T2.2, T3.1, and T3.2 during actual operation.

[0104] Here, the cutting edge 9 of the working step section T3.2 is symmetrical to the cutting edge 9 of the lower fourth step section T4 or fourth step section portion T4. Therefore, the symmetrical arrangement of the working step section T3.2 and the fourth step section T4 or fourth step section portion T4 cooperates to maintain the centering effect of the drilling portion 4 after it enters the workpiece.

[0105] Figure 8 shows a schematic side view of an asymmetric multi-edge drilling section 4 used in a cone drill according to one embodiment of the present invention. The cone drill comprises a shank 1 for securing the cone drill and a working section 2 adjacent to the shank 1 for hole drilling. The working section 2 includes a plurality of stepped drilling / reaming sections 30 arranged sequentially along the feed direction and with increasing diameter. Each drilling / reaming section 30 can drill / reame a hole of the same diameter as its cylindrical section in, for example, a thin metal sheet such as steel. Generally, the first step at the front of the working section 2 can be referred to as the drilling section, and the subsequent steps can be referred to as the reaming section 30. The asymmetric multi-edge drilling section 4 according to the present invention is formed at the tip or front end of the first drilling section of the working section 2, distal from the shank 1. Specifically, the first drilling section 30 at the front end of the working section 2 comprises a drilling section 4 according to the present invention and an adjacent cylindrical section 40. This cylindrical section 40, for example, defines the minimum diameter hole that can be drilled by the cone drill. Furthermore, it can be seen that the helical chip flutes 3 extend longitudinally over the entire working part 2 .

[0106] FIG9 shows a schematic side view of an asymmetric multi-edge drilling section 4 according to one embodiment of the present invention, applied to a chamfering and drilling integrated drill bit. The chamfering and drilling integrated drill bit comprises a shank 1 for securing the same and a working section 2 for hole machining, adjacent to the shank 1. The working section 2 comprises an asymmetric multi-edge drilling section 4 according to the present invention at the front end, a stepped hole drilling section 50 for drilling a stepped hole, located behind the drilling section 4 and spaced axially therefrom, and a hole chamfering section 60 for chamfering the drilled stepped hole, located behind the stepped hole drilling section 50 and spaced axially therefrom. The chip flute 3 extends sequentially through the multi-edge drilling section 4, the stepped hole drilling section 50, and the hole chamfering section 60.

[0107] Figure 10 shows a schematic side view of an asymmetric multi-edge drilling section 4 according to one embodiment of the present invention, applied to a compound tap drill. The compound tap drill comprises a shank 1 for securing the drill and a working section 2 for hole machining, adjacent to the shank 1. The working section 2 comprises an asymmetric multi-edge drilling section 4 according to the present invention at the leading end, a tapping section 70 for tapping the hole, located axially behind and spaced apart from the drilling section 4, and a chamfering section 80 for chamfering the hole, located axially behind and spaced apart from the tapping section 70. The chip flutes 3 extend sequentially through the multi-edge drilling section 4, the tapping section 70, and the chamfering section 80.

[0108] FIG11 shows a schematic side view of the application of an asymmetric multi-edge drilling portion 4 on an umbrella drill according to an embodiment of the present invention. The umbrella drill has a shank 1 for fixing the umbrella drill and a working portion 2 for hole machining adjacent to the shank 1. The working portion 2 has an asymmetric multi-edge drilling portion 4 according to the present invention at the front end and a reaming portion 90 behind and directly adjacent to the drilling portion 4, which is capable of reaming to the desired hole diameter for machining thin plates. Based on the asymmetric multi-edge drilling portion 4 of the present invention, the umbrella drill can efficiently cut into the workpiece and ultimately complete the drilling. Here, the chip flute 3 extends successively through the multi-edge drilling portion 4 and the reaming portion 90.

[0109] FIG12 shows a schematic side view of an asymmetric multi-edge drilling portion 4 according to one embodiment of the present invention used in a saw drill bit. The saw drill bit comprises a shank 1 for securing the same and a working portion 2 for hole machining adjacent to the shank 1. The working portion 2 comprises an asymmetric multi-edge drilling portion 4 according to the present invention at the front end and a serrated working portion 100 spaced axially behind the drilling portion 4. The serrated working portion 100 is used to cut in the transverse direction, thereby cutting a desired shape into a thin plate.

[0110] Figure 13a shows a schematic side view of an asymmetric multi-edge drilling section according to another embodiment of the present invention, used in a twist drill. The saw drill comprises a shank 1 for securing the twist drill, and a working section 2 for drilling holes, adjacent to the shank 1. The working section 2 comprises a guide section adjacent to the shank 1, and an asymmetric multi-edge drilling section 4 according to an embodiment of the present invention, adjacent to the guide section in front of the guide section. A chip flute 3 extends over at least a portion of the working section 2.

[0111] Figure 13b shows a detailed view of the asymmetrical, multi-edge drilling section of the twist drill in Figure 13a. Unlike the previous embodiment, each stepped section comprises two curved segments, resulting in each cutting edge (primary cutting edge 5 and secondary cutting edge 6) being curved. Also visible are the asymmetrical cutting edge 9, primary cutting edge 5, and secondary cutting edge 6 located on the second stepped section. The cutting edge 9 of the leading drill tip section and the final transition section 12 remain symmetrical.

[0112] Furthermore, it is also conceivable to apply the asymmetric multi-edge drilling portion 4 to other hole-making drill bits to perform other hole-making combinations.

[0113] In combination with the above description of the embodiments of the present invention, the characteristics or beneficial technical effects of the asymmetric multi-edge drilling portion 4 of the present invention include but are not limited to:

[0114] 1) The simultaneous and symmetrical cutting of the symmetrical cutting edges of the symmetrical multi-edge drilling portion 4 is changed to staggered cutting, so that the cutting edges cut non-simultaneously and asymmetrically to form a composite cutting effect.

[0115] 2) The same-frequency resonance problem caused by the symmetrically distributed cutting force of the symmetrical multi-edge drilling portion 4 is improved, so that the tool cutting is stable and the tool life is extended and improved.

[0116] 3) Compared with the symmetrical multi-edge drilling part 4 with the same number of step sections Tn, the number of step sections Tn involved in actual cutting is increased, the metal cutting allowance is refined and dispersed, and the power of the power tool is reduced, especially the physical strength and efficiency during hand-held processing.

[0117] 4) The axially staggered structure creates a greater axial spacing between adjacent cutting edges on the same side, increasing chip capacity and facilitating smoother chip evacuation. This is especially true at small-diameter steps, where the chip flute 3 is narrow and unfavorable for chip evacuation. However, the staggered arrangement of cutting edges increases the spacing between adjacent cutting edges on the same side, creating a larger chip space and facilitating chip evacuation.

[0118] 5) The cutting edges at the larger diameter step are arranged symmetrically, so that the main cutting edge 7 that bears the larger cutting force has radial cutting balance, stabilizes the working rotation axis 10 during drilling, avoids the axis deviation of the hole, and ensures the dimensional accuracy of the hole diameter.

[0119] A notable feature of the asymmetric multi-edge drilling portion 4 according to the present invention is that at least one symmetrical cutting edge in the prior art is changed to a staggered cutting edge, thereby bringing the following beneficial effects:

[0120] 1) During the entire cutting process, the cutting force is small, uniform and reasonable, and the chip removal is smooth.

[0121] 2) The manual handheld power tool with the asymmetric multi-edge drilling portion 4 is more stable, consumes less power, and can be operated for a long time.

[0122] 4) The cutting edge wear of each step section Tn of the tool is uniform, which extends the service life of the tool.

[0123] 5) Reduce unnecessary damage to the tool during use and scrapping of the workpiece.

[0124] 6) Reduce processing difficulty and cost, and improve processing efficiency.

[0125] 7) The knife moves smoothly and steadily.

[0126] The present invention may include any feature or feature combination or generalization disclosed herein, whether implicit or explicit, and is not limited to the scope of any limitation listed above. Any elements, features and / or structural arrangements described herein may be combined in any suitable manner.

[0127] The particular embodiments disclosed above are exemplary only, and it will be apparent to those skilled in the art having the benefit of the teachings herein that the present invention may be modified and practiced in different but equivalent manners. It is therefore apparent that changes and modifications may be made to the particular embodiments disclosed above, and all such variations are considered to fall within the scope and spirit of the present invention.

Claims

1. A drilling part for a hole processing tool, characterized in that: The drilling part includes: at least two chip flutes, which are arranged spaced apart in the circumferential direction of the drilling portion, A plurality of side portions, each side portion being delimited by two adjacent chip flutes in a circumferential direction, wherein each side portion comprises a plurality of step section portions arranged successively in a feed direction, and each step section portion comprises a first section and a second section directly adjacent to the first section, wherein, when the step section portions of each side portion are numbered sequentially relative to the feed direction, the step section portions belonging to the same sequence number on all the side portions constitute the same step section, wherein each side portion further comprises a transition section portion following all the step section portions, A plurality of main cutting edges are formed by the intersection of each chip flute with the first section of each step section and each transition section. a plurality of secondary cutting edges formed by the intersection of each chip flute and the second section of each step section, and A plurality of cutting edges, each formed by the intersection of a main cutting edge and a secondary cutting edge formed by the same chip flute and the same step section. In which, at least one of the step sections is constructed as an asymmetric step section, and the same asymmetric step section has at least two asymmetric step section parts separated by a chip groove in the circumferential direction, and the at least two asymmetric step section parts and the at least two chip grooves respectively form at least two asymmetric cutting edges that are not rotationally symmetrical about the working rotation axis. Therefore, the at least two asymmetric cutting edges have different radial distances from the working rotation axis and are axially staggered relative to each other in the direction of the working rotation axis.

2. The drilling portion according to claim 1, wherein: The drilling portion is configured as the drilling portion located at the front end of the hole processing tool, wherein the first step section located at the front end of the step sections is configured as a drill tip section, the point of the drill tip section located at the front end along the feed direction is configured as a drill tip apex, and the asymmetric cutting edges on the same asymmetric step section have different axial distances from the drill tip apex.

3. The drilling portion according to claim 2, wherein: The individual cutting tips of the drill tip segments are designed rotationally symmetrically with respect to 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 tip apex.

4. The drilling portion according to claim 3, wherein: Among the step sections of the drilling portion following the drill tip section, at least one step section among the first half of the step sections is formed as an asymmetrical step section.

5. The drilling portion according to claim 4, wherein: Among the step sections of the drilling portion following the drill tip section, at least two step sections directly adjacent to each other among the first half of the step sections are formed as asymmetrical step sections.

6. The drilling portion according to claim 5, wherein: Two step sections of the drilling part that are directly adjacent to the drill tip section are designed as asymmetrical step sections.

7. The drilling portion according to claim 4, wherein: The step section of the drilling portion immediately following the drill tip section is formed as an asymmetrical step section.

8. The drilling portion according to claim 3, wherein: The plurality of side portions respectively have the same number of step section portions, wherein, among the step sections of the drilling portion following the drill tip section, at least one step section of the latter half of the step sections is configured as a symmetrical step section, and the cutting edges on the symmetrical step sections are configured to have the same radial distance from the working rotation axis and the same axial distance from the drill tip apex.

9. The drilling portion according to claim 8, wherein: Of the step sections of the drilling portion following the drill tip section, at least two step sections directly adjacent to each other among the last half of the step sections are formed as symmetrical step sections.

10. The drilling portion according to claim 9, wherein: Of the step sections of the drilling portion following the drill tip section, the last two step sections directly adjacent to each other among the second half of the number of step sections are formed as symmetrical step sections.

11. The drilling portion according to claim 8, wherein The last step section of the drilling portion is configured as a symmetrical step section.

12. The drilling portion according to claim 1, wherein At least two sides have different numbers of step section parts, and in the at least two sides, the cutting edge on a step section part of one side and the cutting edge on a step section part of another side with a different serial number from the one step section part 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. The drilling portion according to claim 12, wherein: The cutting edges on the last step section portions of the at least two side portions have the same radial distance from the working rotation axis and are arranged axially without being offset relative to each other in the direction of the working rotation axis.

14. The drilling portion according to claim 1, wherein The transition section parts of the respective sides have the same radial distance from the working axis of rotation and are arranged axially non-offset relative to one another in the direction of the working axis of rotation.

15. The drilling portion according to claim 1, wherein 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 are configured as curved segments.

16. The drilling portion according to claim 1, wherein The number of the step sections of the drilling portion is greater than or equal to 3.

17. The drilling portion according to claim 16, wherein: The number of the step sections of the drilling portion is greater than or equal to 5.

18. The drilling portion according to claim 2, wherein: The included angle between the main cutting edges of the drill tip sections is greater than the cone angle of the conical drilling portion.

19. The drilling portion according to claim 18, wherein The included angle between the main cutting edges of the drill tip sections is an obtuse angle, and the taper angle of the drilling portion is an acute angle.

20. The drilling portion according to claim 1, wherein The chip flutes are linear or spiral.

21. The drilling portion according to claim 1, wherein At least one main cutting edge is configured as a multi-segment edge, each edge segment being straight or arc-shaped.

22. A hole processing tool, characterized in that: The hole machining tool includes a shank for fixing the hole machining tool and a working portion for hole machining located in front of the shank. The working portion includes a drilling portion according to any one of claims 1 to 21 located at a front end thereof.

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

24. The hole machining tool according to claim 23, wherein: The chip flute extends over a majority of the guide portion.

25. The hole machining tool according to claim 22, wherein: The hole processing tool is configured as a pagoda drill, and the working portion includes a plurality of stepped drilling / reaming portions arranged successively along the feed direction and with increasing diameters, wherein the first drilling portion at the front is provided with the drilling portion.

26. The hole machining tool according to claim 22, wherein: The hole processing tool is configured as a chamfering and drilling integrated drill bit, the working portion having the drilling portion at the front end, a step hole drilling portion for drilling a step hole behind the drilling portion and spaced axially therefrom, and a hole chamfering portion for chamfering the drilled step hole behind the step hole drilling portion and spaced axially therefrom.

27. The hole machining tool according to claim 22, wherein: The hole processing tool is configured as a compound tap drill, the working part having the drilling part at the front end, a tapping part behind the drilling part and spaced axially therefrom for tapping the hole, and a hole chamfering part behind the tapping part and spaced axially therefrom for chamfering the hole.

28. The hole machining tool according to claim 22, wherein: The hole machining tool is configured as an umbrella drill, and the working portion includes the drilling portion at the front end and a reaming portion located behind and directly adjacent to the drilling portion.

29. The hole machining tool according to claim 22, wherein: The hole machining tool is configured as a saw drill bit, and the working portion includes the drilling portion at the front end and a sawtooth working portion located behind the drilling portion and spaced apart from the drilling portion at an axial distance.

Images