A stepped drill and a method of drilling a workpiece using the same

Abstract

The invention relates to a stepped drill, characterized in that the stepped drill has a bore machining portion and at least two grooves extending on the bore machining portion, the bore machining portion comprising step sections, each of which forms at least two cutting edges distributed in the circumferential direction of the step section with the at least two grooves, the at least two cutting edges on at least one step section comprising at least a first cutting edge and a second cutting edge, the first cutting edge and the second cutting edge each being configured in at least two sections and thus each comprising at least two cutting edge sections, wherein the first cutting edge and the second cutting edge differ at least partially from one another in the configuration of their cutting edge sections, or one of the first cutting edge and the second cutting edge is configured in one section and the other cutting edge is configured in at least two sections and thus comprises at least two cutting edge sections. The invention also relates to a method for drilling a workpiece using a stepped drill.

Description

Technical Field

[0001] This invention relates to a step drill and a method for drilling and cutting workpieces using a step drill. Background Technology

[0002] A step drill is a pagoda-shaped drill bit, consisting of a drill tip, an adjacent reaming section with a stepped profile, and a shank, hence its name "step drill." The stepped profile is formed by multiple stepped segments that increase in size against the feed direction, and each stepped segment includes a frustoconical segment and an adjacent cylindrical segment. The step drill has at least one groove, or chip removal groove, or cutting groove on its drill tip and reaming section, and the groove intersects with the surface of the frustoconical segment to form the main reaming cutting edge. Multiple grooves on the same frustoconical surface thus form multiple main reaming cutting edges.

[0003] The working process of a step drill is as follows: after starting, an initial small hole is drilled with the drill tip, and then the hole is gradually enlarged to obtain the desired diameter. Using a single step drill, multiple diameter holes can be drilled (or enlarged) in a single setup.

[0004] Step drills are ideal for sheet metal drilling, suitable for cutting non-ferrous metals up to 1.5mm thick, plastics and wood up to 4.0mm thick, and steel plates up to 4.0mm thick.

[0005] See Figure 1 Existing step drills typically have two symmetrical oblique grooves or helical grooves 105 and 105'. Figure 1 (as shown) or straight groove (not shown), and each reaming main cutting edge A'n on each step section T'n of the stepped drill 100 is a single-segment line segment, that is, a single-segment straight line segment (when the groove is a straight groove) or a single-segment curved segment (when the groove is an oblique groove or a spiral groove 105, 105'). Figure 1 The figure shows a segment of a curve in the case of oblique groove or spiral groove 105, 105'.

[0006] like Figure 1 and Figure 2 As shown, the main cutting edges on the first helical groove 105 are A'1, A'2…A'i…A'n. The normal cutting angles of each segment of the cutting edge on the first helical groove 105 are: rake angle γn, clearance angle αn, cutting edge inclination angle (helix angle) β, and main and secondary cutting edge angles λ, which are distributed according to certain design rules and requirements.

[0007] The main cutting edges on the second helical groove 105' (which is symmetrically distributed 180° relative to the first helical groove 105 on the circumference) are A'1', A'2'…A'i'…A'n', which are structurally identical to the corresponding main cutting edges on the first helical groove 105, i.e., A'1'=A'1, A'2'=A'2, …A'i'=A'i, A'n'=A'n. Furthermore, the normal cutting angles of each segment of the cutting edge on the second helical groove 105' are: rake angle γn', clearance angle αn', inclination angle (helix angle) β', and primary and secondary cutting angles λ', distributed according to the same design rules and requirements as the first helical groove 105, i.e., γn'=γn, αn'=αn, β'=β, λ'=λ.

[0008] In other words, the main cutting edges that are symmetrically arranged 180° in the circumferential direction on each step segment T'n are identical, and therefore their cutting functions are also identical. See [link to relevant documentation] for details. Figure 10 The shaded area shown represents the area cut by each primary cutting edge on the same step segment T'n, with a depth of cut of f / 2 and a cutting length A'n corresponding to the entire length of the primary cutting edge A'n. The area cut by each primary cutting edge is exactly the same and all cutting occurs over the entire cutting length A'n.

[0009] However, in practice, it has been found that traditional stepped drills with the above design have problems such as large cutting force, insufficient cutting sharpness, difficulty in chip breaking, large cutting heat, and low machining efficiency. Summary of the Invention

[0010] Therefore, the present invention aims to provide a step drill and a method for drilling and cutting workpieces using a step drill, by means of which at least one of the above-mentioned technical problems existing in the prior art can be solved.

[0011] According to one aspect of the invention, the task is accomplished using a step drill, wherein the step drill has a hole-machining portion and at least two grooves extending on the hole-machining portion, the hole-machining portion comprising one or more stepped segments, each stepped segment forming at least two circumferentially distributed cutting edges with respect to the at least two grooves.

[0012] Wherein, at least one of the at least two cutting edges on the stepped segment includes at least a first cutting edge and a second cutting edge, wherein...

[0013] The first and second cutting edges are each configured as at least two segments, and therefore each includes at least two cutting edge segments, wherein the first and second cutting edges differ from each other at least partially in the structure of their cutting edge segments, or

[0014] One of the first and second cutting edges is configured as a single segment, while the other cutting edge is configured as at least two segments, and thus includes at least two cutting edge segments.

[0015] In this invention, the term "structure" should be interpreted broadly, and may include geometric structures or parameters such as the geometry (e.g., straight or curved cutting edge, primary / secondary cutting edge angle λ, etc.), size or quantity of each cutting edge segment.

[0016] The technical effects achievable with a stepped drill include, but are not limited to: transforming a single-segment cutting edge into a multi-segment cutting edge with at least two segments, increasing the total length of the cutting edge compared to the original cutting edge. This disperses the cutting force per unit cutting edge length, thus reducing heat generation. Multi-segment cutting edges can be combined with other multi-segment or single-segment cutting edges to create composite cutting actions, thereby cutting the material in multiple segments and thus decomposing the cutting process. Each cutting edge bears a smaller cutting area, therefore only a reduced cutting force is needed during cutting.

[0017] Advantageously, the first cutting edge participates in cutting only locally in its first extended section, the radial distance of which from the longitudinal axis of the stepped drill is greater than the radial distance from the longitudinal axis of the stepped drill to the section of the second cutting edge that is coaxial with the first extended section; and

[0018] The second cutting edge participates in cutting only locally in its second extended section, and the radial distance of the second extended section from the longitudinal axis of the stepped drill is greater than the radial distance of the section of the first cutting edge that is in the same axial position as the second extended section from the longitudinal axis of the stepped drill.

[0019] Advantageously, the first protruding section includes at least one first cutting edge cutting area, and the second protruding section includes at least one second cutting edge cutting area. In the hypothetical state where the first and second cutting edges are rotated and merged about the longitudinal axis of the step drill, the first cutting edge cutting area and the second cutting edge cutting area are adjacent to each other in the axial or radial direction of the step drill.

[0020] Advantageously, the first protruding section includes at least two first cutting edge cutting areas spaced apart from each other, and the second protruding section includes at least one second cutting edge cutting area, wherein, in the hypothetical state of the first and second cutting edges rotating and merging about the longitudinal axis of the step drill, the one second cutting edge cutting area is located between the two first cutting edge cutting areas in the axial or radial direction of the step drill.

[0021] Advantageously, the first and / or second cutting edges of at least two segments include first and second cutting edge sections arranged sequentially against the feed direction, wherein the first and second cutting edge sections of the at least two-segment first cutting edge are different from each other in terms of the major / minor cutting edge angles relative to the feed direction, and / or the first and second cutting edge sections of the at least two-segment second cutting edge are different from each other in terms of the major / minor cutting edge angles relative to the feed direction.

[0022] Advantageously, in the hypothetical state where the first and second cutting edges are rotated and merged about the longitudinal axis of the step drill, the first cutting edge segment and / or the second cutting edge segment of the first cutting edge with at least two segments intersect with the first cutting edge segment and / or the second cutting edge segment of the second cutting edge with at least two segments, or, one of the first and second cutting edges is a single-segment cutting edge that intersects with the first cutting edge segment and / or the second cutting edge segment of the other at least two-segment cutting edge.

[0023] Advantageously, the first cutting edge section of the at least two-segment first cutting edge and the first cutting edge section of the at least two-segment second cutting edge are identical to each other in terms of the major / minor cutting edge angles relative to the feed direction, and the second cutting edge section of the at least two-segment first cutting edge and the second cutting edge section of the at least two-segment second cutting edge are different from each other in terms of the major / minor cutting edge angles relative to the feed direction, or...

[0024] One of the first and second cutting edges is a single-segment cutting edge, and the first and / or second cutting edge segments of the other at least two-segment cutting edge are different from each other in terms of the primary / secondary cutting edge angles relative to the feed direction.

[0025] Advantageously, the length of the first cutting edge section of the first cutting edge with at least two segments is less than the length of the first cutting edge section of the second cutting edge with at least two segments, and the radial distance of the first cutting edge section of the first cutting edge with at least two segments from the longitudinal axis of the stepped drill at the same axial position is greater than the radial distance of the first cutting edge section of the second cutting edge from the longitudinal axis of the stepped drill.

[0026] Advantageously, at least one of the cutting edge segments of the first or second cutting edge, which is at least two-segmented, can be formed by locally reducing the material on the original one-segmented cutting edge.

[0027] Advantageously, each cutting edge segment of the first and second cutting edges, which are at least two-segmented, is composed of a straight line segment or a curved segment.

[0028] Advantageously, at least one of the horizontal cutting edge segments adjacent to the first cutting edge is radially offset from at least one of the horizontal cutting edge segments adjacent to the second cutting edge.

[0029] Advantageously, the cutting edges formed by the same groove on different step sections are constructed to be at least partially different or identical in terms of their structure.

[0030] Advantageously, the groove structure is a straight groove or a spiral groove.

[0031] According to another aspect of the invention, the task is solved by a method of drilling a workpiece using a step drill, wherein the step drill has a hole-machining portion and at least two grooves extending on the hole-machining portion, the hole-machining portion comprising one or more stepped segments, each stepped segment forming at least two circumferentially distributed cutting edges with the at least two grooves, wherein at least two cutting edges on at least one of the stepped segments include at least a first cutting edge and a second cutting edge.

[0032] The method includes at least the following steps:

[0033] The first material portion on the workpiece is cut using the first cutting edge, wherein the first material portion extends only a portion of the length of the first cutting edge;

[0034] The second material portion on the workpiece is cut using the second cutting edge, wherein the second material portion extends only a portion of the length of the second cutting edge.

[0035] Advantageously, the first material section includes at least one first sub-material section, and the second material section includes at least one second sub-material section adjacent to the first sub-material section.

[0036] Advantageously, the first material section includes at least two first sub-material sections spaced apart from each other, and the second material section includes at least one second sub-material section located between the two first sub-material sections.

[0037] Advantageously, the step drill is a step drill according to the invention.

[0038] Those skilled in the art will understand the advantages of the respective embodiments and various other embodiments by referring to the following detailed description of the corresponding embodiments with reference to the accompanying drawings. Attached Figure Description

[0039] Embodiments of the invention are described below with reference to the accompanying drawings. The drawings are not necessarily to scale; rather, they are used for illustration in a schematic and / or slightly modified manner. For supplementary aspects of the teachings directly identifiable from the drawings, see the relevant prior art. It should be noted that various modifications and variations in the form and detail of the embodiments can be made without departing from the overall concept of the invention. The features of the invention disclosed in the specification and drawings are important for improvements to the invention, both individually and in any combination. Furthermore, the scope of the invention includes all combinations consisting of at least two of the features disclosed in the specification and / or drawings. The overall concept of the invention is not limited to the exact form or detail of the preferred embodiments shown and described below.

[0040] The attached image is as follows:

[0041] Figure 1 This is a schematic side view of a stepped drill in the prior art;

[0042] Figure 2 yes Figure 1 A schematic enlarged partial cross-sectional view of the stepped drill through the section line NN;

[0043] Figure 3 This is a schematic side view of the combined-blade stepped drill according to the present invention;

[0044] Figure 4 yes Figure 3 A schematic partial cross-sectional enlarged view of the combined-edge stepped drill through the Ni-Ni section line;

[0045] Figure 5 yes Figure 3 A schematic enlarged view of part I of the combined-edge step drill in the diagram;

[0046] Figure 6 yes Figure 3 A schematic enlarged view of part II of the combined-edge step drill, wherein, Figure 5 The first cutting edge in the drill merges with the second cutting edge after rotating 180° around the longitudinal axis of the stepped drill.

[0047] Figure 7 As shown in the diagram Figure 3 The second cutting edge at local II of the combined-edge step drill is compared with the first cutting edge at local I after rotating 180° around the longitudinal axis of the step drill.

[0048] Figure 8 yes Figure 7 The schematic diagram shows that the two first protruding sections of the first cutting edge are indicated by shaded lines.

[0049] Figure 9 yes Figure 7 The schematic diagram shows that a second extended section of the second cutting edge is indicated by a shaded line.

[0050] Figure 10 The diagram schematically illustrates the cutting action of two cutting edges, or teeth, of a conventional step drill, wherein the cutting area of ​​each cutting edge is indicated by a shaded line.

[0051] Figure 11 This schematically illustrates an embodiment of combined cutting with a single-stage cutting edge and a multi-stage cutting edge on a stepped section, wherein each cutting area of ​​each cutting edge is indicated by a shaded line; and

[0052] Figure 12 This schematically illustrates another embodiment of combined cutting with a single-segment cutting edge and a multi-segment cutting edge on a stepped section, wherein the respective cutting areas of one and two cutting edges of each cutting edge are indicated by shaded lines. Detailed Implementation

[0053] The following describes an illustrative embodiment of the combined-edge step drill 1 according to the present invention. In this specification, various systems, structures, and devices are schematically depicted in the accompanying drawings for illustrative purposes only, but not all features of actual systems, structures, and devices are described. For example, well-known functions or structures are not described in detail to avoid unnecessary detail that could obscure the invention. It should be understood that in any practical 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 limitations, which may vary depending on the specific application. Furthermore, it should be understood that while such implementation decisions are complex and time-consuming, they are routine tasks for those skilled in the art who will benefit from the present invention.

[0054] The terms and phrases used herein should be understood and interpreted in accordance with the understanding of those skilled in the art. The consistent use of terms or phrases herein is not intended to imply a specific definition, i.e., a definition different from the common and conventional meaning understood by those skilled in the art. For terms or phrases intended to have a specific meaning, i.e., a meaning different from that understood by those skilled in the art, such specific definition will be explicitly listed in the specification, giving the specific definition of the term or phrase directly and unambiguously.

[0055] Unless otherwise required by the content, throughout the following description, the word “including” and its variations, such as “comprising” and “having”, will be interpreted in an open-ended, inclusive sense, that is, as “including but not limited to”.

[0056] Throughout this specification, references to terms such as "an embodiment," "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. Therefore, the phrases "in one embodiment" or "in one embodiment" appearing in different places throughout this specification do not necessarily refer to the same embodiment. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0057] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0058] Next, let's combine the illustrative examples. Figures 3 to 12 An illustrative embodiment of the combined-edge stepped drill 1 (hereinafter referred to as stepped drill 1) of the present invention is described.

[0059] See Figure 3 The step drill 1 may have a drill tip 2 for drilling, an adjacent reaming section 3 for enlarging, and a shank 4. The drill tip 2 and the reaming section 3 together form the machining section of the step drill 1 for drilling and enlarging. The reaming section 3 may include multiple adjacent stepped sections Tn (n = 1, 2, 3, ..., i, ...), and each stepped section Tn includes a truncated conical section and an adjacent cylindrical section. The stepped sections Tn can work in groups to achieve a step-by-step enlarging function. The diameter of each stepped section Tn increases progressively from the drill tip 2 against the feed direction F, step by step Tn. Figure 3 The example shows the diameter dn of the nth step segment Tn (specifically its cylindrical segment) following the feed direction F and the diameter di of the ith step segment Ti (specifically its cylindrical segment) preceding the feed direction F. It can be seen that dn > di.

[0060] The machining section can be provided with two grooves 5 and 5' that form chip removal channels, namely a first groove 5 that faces mostly outward from the drawing plane and a second groove 5' that faces mostly inward from the drawing plane. The first groove 5 and the second groove 5' can extend spirally from one end of the machining section to the other end, and can be radially or rotationally symmetrical about each other in the circumferential direction about the longitudinal axis 6 of the stepped drill 1. On each stepped section Tn, the first groove 5 can intersect with the truncated conical section of the stepped section Tn to form a first cutting edge An (in Figures 5 to 9 (Drawn with a thick solid line in the middle), and the second groove 5' can intersect with the truncated conical segment of the step section Tn to form a second cutting edge An' that is 180° apart from the first cutting edge An in the circumferential direction (in Figures 5 to 9 (Drawn with thick dashed lines). Therefore, two cutting edges An and An' can be formed on each step segment Tn. These two cutting edges An and An' can each have a depth of cut of f / 2.

[0061] In other embodiments, three or more grooves 5, 5' may be provided on the machining section, so that three or more cutting edges An, An' can be formed on each step segment Tn, and these grooves 5, 5' can be evenly distributed in the circumferential direction and rotate symmetrical about the longitudinal axis 6.

[0062] In other embodiments, each groove 5, 5' can be configured as a straight groove, that is, extending straight from one end of the machining section to the other end, and thus forming a cutting edge in the form of a straight segment.

[0063] Unlike existing technologies, the step drill 1 of the present invention has a multi-segment or broken line structure for each cutting edge An, An' (or cutting edge) on at least one step segment Tn. That is, each cutting edge An, An' may include at least two cutting edge segments An1, An2, An1', An2' that are adjacent to each other, and these cutting edge segments can together form the entire cutting edge An, An'.

[0064] Each cutting edge segment An1, An2, An1', An2' can be configured as a straight segment in the case of a straight groove. While each cutting edge segment An1, An2, An1', An2' can be configured as a curved segment in the case of a curved groove 5, it can also be implemented as a straight segment according to specific functional requirements using machining processes. In particular, in this invention, a relatively small cutting edge An, An' is designed to be composed of multiple smaller cutting edge segments An1, An2, An1', An2'. Both straight and curved cutting edge segments An1, An2, An1', An2' are within the scope of this invention, and the concept of this invention is applicable to cutting edges that are straight, curved, or of other shapes. For clarity, the following explanation uses only a simplified example of straight cutting edge segments An1, An2, An1', An2'.

[0065] As mentioned above, the adjacent cutting edge segments An1, An2, An1', and An2' of each cutting edge An and An' can form a broken line segment (i.e., a broken straight line or a broken curve) at an angle to each other, or in other words, they can form abrupt changes or inflection points at their adjacent points, or they can have different slopes.

[0066] This embodiment uses the cutting edge segments of straight lines as an example. That is, each cutting edge An and An' on each stepped segment Tn can include multiple cutting edge segments An1, An2, An1', and An2' of straight lines, which can collectively form a polygonal cutting edge An and An'. In this embodiment, the number of cutting edge segments An1, An2, An1', and An2' of each cutting edge An and An' on each stepped segment Tn can be two, namely, a first cutting edge segment An1 and An1' along the feed direction F and a second cutting edge segment An2 and An2' along the feed direction F.

[0067] See Figure 3 For the i-th step segment Ti, the first cutting edge Ai on it may include a first cutting edge segment Ai1 and a subsequent second cutting edge segment Ai2, which may differ in length and may be at an angle to each other. Figure 3 The blade inclination angle (helix angle) βi can be seen.

[0068] Figure 4 Show Figure 3 The image shows a magnified view of the first cutting edge on a stepped section, at a point on the cutting edge (specifically, the cutting edge of the first cutting edge section), divided by the section line Ni-Ni, where γni is the normal forward angle and αni is the normal backward angle. The cutting angles and forces at different points on the cutting edge are also different, which can be used for the analysis of the cutting principle of the tool.

[0069] The following is combined Figures 5 to 9 An exemplary description is provided of the structure of the first cutting edge An and the second cutting edge An' on the nth step segment Tn, and their combined cutting method.

[0070] See Figure 5 The first cutting edge An on the nth step segment Tn is drawn with a thick solid line. It can include a first cutting edge segment An1 that is in front in the feed direction F and a second cutting edge segment An2 that is behind in the feed direction F. The first cutting edge segment An1 and the second cutting edge segment An2 can be different in length from each other, specifically the former is shorter than the latter, and they can form an angle with each other, which is an obtuse angle in this case, so that they can together form a two-segment broken edge.

[0071] The second cutting edge section An2 can be formed by reducing the material, such as cutting off the material, on the upper part of the original one-piece cutting edge A’n, and the first cutting edge section An1 can then be formed by the cutting edge part remaining after cutting off part of the material. Thus, the main cutting edge angle λn1 of the first cutting edge An at the first cutting edge section An1 remains unchanged compared to the main cutting edge angle λn0 of the one-piece cutting edge A’n, while the secondary cutting edge angle λn2 of the first cutting edge An at the second cutting edge section An2 is smaller than λn0 or λn1, that is, λn2 < λn1 = λn0.

[0072] In addition, it can be seen from Figure 5 that the length An1 of the first cutting edge section An1 of the first cutting edge An and the length An2 of the second cutting edge section An2 are both smaller than the length A’n of the original one-piece first cutting edge A’n, but the sum of the two is obviously greater than the length A’n of the original one-piece first cutting edge A’n, that is, An1 < An2 < A’n, and An1 + An2 > A’n.

[0073] Refer to Figure 6 , after rotating the first cutting edge An drawn by the thick solid line in Figure 5 by 180° around the longitudinal axis 6 of the step drill, it is combined and compared with the second cutting edge An’ drawn by the thick dashed line. The second cutting edge An’ can include a first cutting edge section An1’ in front in the feed direction F and a second cutting edge section An2’ behind it in the feed direction F. The first cutting edge section An1’ and the second cutting edge section An2’ of the second cutting edge An’ can be different in length, specifically, the former is smaller than the latter, and the two can form an angle with each other, which is an obtuse angle here, so that the two can together form a two-piece broken line cutting edge An’. The length An1’ of the first cutting edge section An1’ of the second cutting edge An’ and the length An2’ of the second cutting edge section An2’ are both smaller than the length A’n of the original one-piece first cutting edge A’n, but the sum of the two is obviously greater than the length A’n of the original one-piece first cutting edge A’n, that is, An1’ < An2’ < A’n, and An1’ + An2’ > A’n.

[0074] Refer to Figure 7 , after rotating the second cutting edge An’ drawn by the thick dashed line in Figure 6 by 180° around the longitudinal axis 6 of the step drill, it is combined and compared with Figure 5 the first cutting edge An drawn by the thick solid line in

[0075] Refer to Figure 6 and Figure 7 , through the combined comparison of the two cutting edges An and An’, the different structures of the two and how they are combined and used to form a "combined cutting edge" for combined cutting can be seen more clearly.

[0076] See Figure 7 , the first horizontal edge section that is in front along the feed direction F and adjacent to the first cutting edge section An1 of the first cutting edge An can be parallel to the first horizontal edge section that is in front along the feed direction F and adjacent to the first cutting edge section An1' of the second cutting edge An', and the former can be farther from the longitudinal axis 6 by a distance δ compared to the latter. The first cutting edge section An1 of the first cutting edge An can be parallel to the first cutting edge section An1' of the second cutting edge An', and the former can be farther from the longitudinal axis 6 by a distance δ at the same axial position compared to the latter. The length An1 of the first cutting edge section An1 of the first cutting edge An can be less than the length An1' of the first cutting edge section An1' of the second cutting edge An', that is, An1 < An1'. Therefore, the first cutting edge section An1' of the second cutting edge An' can intersect with the second cutting edge section An2 of the first cutting edge An.

[0077] The main cutting edge angle λn1 of the first cutting edge section An1 of the first cutting edge An is equal to the main cutting edge angle λn1' of the first cutting edge section An1' of the second cutting edge An', and is equal to the main cutting edge angle λno of the original one-piece first cutting edge A'n, that is, λn1 = λn1' = λno.

[0078] In addition, the second horizontal edge section that is behind along the feed direction F and adjacent to the second cutting edge section An2 of the first cutting edge An can be parallel to the second horizontal edge section that is behind along the feed direction F and adjacent to the second cutting edge section An2' of the second cutting edge An', and the former can be farther from the longitudinal axis 6 by a distance δ compared to the latter. The second cutting edge section An2' of the second cutting edge An' can intersect with the second cutting edge section An2 of the first cutting edge An.

[0079] The main cutting edge angle λn2 of the second cutting edge section An2 of the first cutting edge An is greater than the main cutting edge angle λn2' of the second cutting edge section An2' of the second cutting edge An', and both are less than the main cutting edge angle λn1 of the first cutting edge section An1 of the first cutting edge An or the main cutting edge angle λn1' of the first cutting edge section An1' of the second cutting edge An or the main cutting edge angle λno of the original one-piece first cutting edge A'n, that is, λn2' < λn2 < λn1 = λn1' = λno.

[0080] Thus, see Figure 8The first cutting edge An may extend axially outward beyond the second cutting edge An', with its first protruding sections S1 and S2, which can be two separate planar sections S1 and S2. The two first protruding sections S1 and S2 of the first cutting edge An are indicated by shaded lines, forming two spaced-apart first cutting edge cutting regions S1 and S2. The feed rate during drilling is f = mm / rpm. The depth of cut of the first protruding sections S1 and S2 is a maximum of f / 2. The first cutting edge cutting regions S1 and S2 may extend only along a portion of the length of the first cutting edge An. The first cutting edge cutting regions S1 and S2 may correspond to the cross-sectional area of ​​the material or chip cut by the first cutting edge An per revolution.

[0081] Here, the cutting of the first cutting edge An is based on the cutting of the second cutting edge An'. The two cutting areas S1 and S2 of the first cutting edge An form two cutting areas S1 and S2 with different shapes. Therefore, the total cutting area S of the first cutting edge An can be: S = S1 + S2. These two cutting areas S1 and S2 can be separated from each other, so they can play a strict chip-breaking role when the first cutting edge An is cutting. In addition, the residual burrs (not shown) remaining after the cutting of the second cutting edge An' can also be removed by the first cutting edge An. Then, the total cutting area S of the first cutting edge An can be: S = S1 + S2 + residual burr area.

[0082] See Figure 9 The second cutting edge An' may extend axially outward beyond the first cutting edge An by its second extension section S3 (compared to the first cutting edge at the same axial position). This second extension section can be a triangular planar section S3. The second extension section S3 of the second cutting edge An' is indicated by a shaded line, forming the second cutting edge cutting area S3. The feed rate during drilling is f = mm / rpm. The depth of cut of the second extension section S3 is a maximum of f / 2. The second cutting edge cutting area S3 may extend only along a portion of the length of the second cutting edge An'. The second cutting edge cutting area S3 may correspond to the cross-sectional area of ​​the material or chip cut by the second cutting edge An' per revolution.

[0083] Here, the cutting of the second cutting edge An' is based on the cutting of the first cutting edge An. The cutting area S3 of the second cutting edge An' forms a separate cutting area S3. Therefore, the total cutting area S' of the first cutting edge An can be: S' = S3. The second cutting edge An' cannot perform chip breaking during cutting. Here, S > S'.

[0084] The size and number of the cutting areas, or cutting surfaces S1, S2, and S3, of the first cutting edge An and the second cutting edge An' are not limited to this embodiment, but can vary with the structure or tool parameters of the two cutting edges An and An'. Generally, the first cutting edge An can have at least one cutting area, and the second cutting edge An' can have at least one cutting area. They can work together to cut different parts of the material on the workpiece, such as a sheet metal, and therefore can be combined to cut the workpiece material. Therefore, this invention refers to them as "combined cutting edges".

[0085] For the existing step drill 101, see [link / reference] Figure 10 Its two cutting edges, A'n and A'n', are both single-section and cut along the entire length of the cutting edge, A'n and A'n'. The cutting area S4 per revolution of each cutting edge is the same. Therefore, it can never play a chip-breaking role, and the cutting force is relatively large.

[0086] In summary, in this embodiment, each cutting edge An and An' can be decomposed into two cutting edge segments An1 and An2, and An1' and An2', respectively. That is, the original two single-segment cutting edges become two sets of two-segment cutting edges. The principal or secondary cutting edge angle λ of the cutting edge changes significantly. At the same time, the helix angle βi (i.e., the cutting edge inclination angle) of each segment also changes somewhat. In addition, the total length of the cutting edge after decomposition into multiple cutting edge segments An1, An2 or An1', An2' is greater than the length of the original cutting edge An and An', thereby dispersing the cutting force borne (loaded) per unit cutting edge length and playing a good chip-breaking role, thus dispersing the cutting heat.

[0087] The structure of the cutting edge on the nth step segment Tn of the stepped drill 1 in this embodiment has been described above. In this embodiment, both the first cutting edge An and the second cutting edge An' can be configured as multi-segment structures. Furthermore, for step segments other than the nth step segment Tn, such as those adjacent to it, the tooth shape or structure of their first cutting edge can be the same as that of the first cutting edge An on the nth step segment Tn, and the tooth shape or structure of their second cutting edge can be the same as that of the second cutting edge An' on the nth step segment Tn.

[0088] In other embodiments, see Figure 11 and Figure 12 For the nth step segment Tn, only one of the two cutting edges can be set as a multi-segment structure, while the other cutting edge A'n is still set as a single-segment structure. They can still be combined and cut in various possible specific structures, and can also form their own protruding segments S1, S2, S3 or cutting edge cutting areas S1, S2, S3, just like the combination of two multi-segment cutting edges.

[0089] exist Figure 11 In this process, the horizontal cutting edge sections on the same side adjacent to the two cutting edges can have the same radial dimension, and therefore coincide with each other after rotation. The two cutting edges respectively form a triangular protruding section S1, S2, or cutting edge cutting areas S1, S2, which are adjacent to each other radially or axially in the stepped drill (in the hypothetical state of the two cutting edges rotating and merging) and can be combined to cut each other.

[0090] exist Figure 12 In this process, the radial dimensions of the horizontal cutting edge sections adjacent to the two cutting edges on the same side can differ by a distance δ. One cutting edge forms two protruding sections S1 and S2, or cutting edge cutting areas S1 and S2, that are spaced apart from each other radially or axially in the stepped drill. The other cutting edge forms a protruding section S3, or cutting edge cutting area S3, located between these two protruding sections S1 and S2. This allows for precise chip separation during cutting.

[0091] In other embodiments, for step segments Tn other than the nth step segment Tn, such as those adjacent to it, the tooth shape or structure of its first cutting edge may be different from that of the first cutting edge An on the nth step segment Tn, and / or the tooth shape or structure of its second cutting edge may be different from that of the second cutting edge An' on the nth step segment Tn. For example, these differences may be reflected in the number, length, area, or arrangement of each cutting edge segment An1, An2, An1', An2', the size of the primary / secondary cutting edge angle λ, etc.

[0092] In other embodiments, the cutting edges on only a portion of the stepped sections Tn of the stepped drill 1 can be designed as the multi-segment combined cutting edges described above, while the cutting edges on other stepped sections Tn can be set as the original single-segment structure.

[0093] Based on the above description of the embodiments, the features of the combined cutting edge stepped drill 1 of the present invention include:

[0094] (1) The original single-segment (straight or curved) cutting edge or cutting edge is improved into a multi-segment (straight or curved) cutting edge with at least two segments. The total length of the cutting edge is greater than the original cutting edge length, thereby decomposing the cutting force borne (loaded) on a unit cutting edge length and dispersing the cutting heat.

[0095] (2) In particular, the primary and secondary cutting edge angles λn change significantly, thus altering the direction of the cutting force and achieving chip separation. At the same time, the inclination angle (helix angle) βn of each cutting edge section An1, An2, An1', and An2' also changes, thus altering the chip removal direction.

[0096] (3) At least two straight or curved main cutting edges on the same step section Tn are different in structure or tooth shape, for example, the length and / or inclination angle of each section of the broken edge are different, or even the number is different.

[0097] A significant feature of the combined-edge stepped drill 1 is that it alters the cutting edge length and angle values ​​of each cutting edge, thereby changing the original state during machining and bringing about the following beneficial effects:

[0098] 1. This reduces the cutting force, saves power, and allows for a wider machining range with the same cutting tools;

[0099] 2. Improved cutting sharpness leads to increased processing efficiency, thereby enhancing the value of the cutting tool.

[0100] 3. Easy chip breaking facilitates timely chip removal and heat dissipation, and frees up a larger cooling space;

[0101] 4. It increases the service life of the cutting tools, which is beneficial for long-term machining;

[0102] 5. Compared to conventional step drills, it increases the thickness of the sheet material that can be drilled in one go.

[0103] Furthermore, compared to the larger cutting area of ​​a conventional single-segment cutting edge, the multi-segment cutting edge of this invention can be combined with other multi-segment or single-segment cutting edges to produce a composite cutting action. Existing technology cuts the material completely along the entire length of the cutting edge in one go, while this invention cuts the material in multiple segments. Therefore, it can achieve decomposed cutting. Each cutting edge bears a smaller cutting area, thus requiring only a reduced cutting force during cutting. Furthermore, chip separation is easier to achieve. Additionally, by controlling the cutting angle of each segment, burrs and other defects can be effectively controlled.

[0104] This invention may include any feature or combination of features or generalization thereof implied or expressly disclosed herein, and is not limited to any of the defined scopes listed above. Any elements, features and / or structural arrangements described herein may be combined in any suitable manner.

[0105] The specific embodiments disclosed above are merely exemplary, and it will be apparent to those skilled in the art, upon which the teachings herein will be adapted and implemented in different but equivalent ways. Therefore, it is evident that changes and modifications can be made to the specific embodiments disclosed above, and all such variations are considered to fall within the scope and spirit of the invention.

Claims

1. A step drill, characterized in that, The stepped drill has a hole-machining section and at least two grooves extending on the hole-machining section. The hole-machining section includes one or more stepped segments, each stepped segment forming at least two circumferentially distributed cutting edges with the at least two grooves. Wherein, at least one of the at least two cutting edges on the stepped segment includes at least a first cutting edge and a second cutting edge, wherein... The first and second cutting edges are each configured as at least two segments, and therefore each includes at least two cutting edge segments. In this process, adjacent cutting edge segments of each of the first and second cutting edges are angled to each other and form inflection points at their points of contact. Furthermore, the first cutting edge and the second cutting edge are at least partially different from each other in terms of the structure of their cutting edge sections.

2. The step drill according to claim 1, characterized in that, The first cutting edge participates in cutting only locally in its first extended section, and the radial distance of the first extended section from the longitudinal axis of the stepped drill is greater than the radial distance of the section of the second cutting edge that is at the same axial position as the first extended section from the longitudinal axis of the stepped drill; and The second cutting edge participates in cutting only locally in its second extended section, and the radial distance of the second extended section from the longitudinal axis of the stepped drill is greater than the radial distance of the section of the first cutting edge that is in the same axial position as the second extended section from the longitudinal axis of the stepped drill.

3. The step drill according to claim 2, characterized in that, The first protruding section includes at least one first cutting edge cutting area, and the second protruding section includes at least one second cutting edge cutting area. In the hypothetical state where the first and second cutting edges are rotated and merged around the longitudinal axis of the step drill, the first cutting edge cutting area and the second cutting edge cutting area are adjacent to each other in the axial or radial direction of the step drill.

4. The step drill according to claim 2, characterized in that, The first extended section includes at least two first cutting edge cutting areas spaced apart from each other, and the second extended section includes at least one second cutting edge cutting area. In the hypothetical state where the first and second cutting edges rotate and merge around the longitudinal axis of the step drill, the one second cutting edge cutting area is located between the two first cutting edge cutting areas in the axial or radial direction of the step drill.

5. The step drill according to claim 1, characterized in that, The first and / or second cutting edge, which are of at least two segments, include a first cutting edge segment and a second cutting edge segment arranged sequentially against the feed direction, wherein the first and second cutting edge segments of the first cutting edge are different from each other in terms of the major / minor cutting edge angle relative to the feed direction, and / or the first and second cutting edge segments of the second cutting edge are different from each other in terms of the major / minor cutting edge angle relative to the feed direction.

6. The step drill according to claim 5, characterized in that, In the hypothetical state where the first and second cutting edges rotate and merge around the longitudinal axis of the step drill, the first cutting edge segment and / or the second cutting edge segment of the first cutting edge with at least two segments intersect with the first cutting edge segment and / or the second cutting edge segment of the second cutting edge with at least two segments, or, one of the first and second cutting edges, is a single-segment cutting edge that intersects with the first cutting edge segment and / or the second cutting edge segment of the other at least two-segment cutting edge.

7. The step drill according to claim 5, characterized in that, The first cutting edge section of the at least two-segment first cutting edge and the first cutting edge section of the at least two-segment second cutting edge are identical to each other in terms of the major / minor cutting edge angles relative to the feed direction, and the second cutting edge section of the at least two-segment first cutting edge and the second cutting edge section of the at least two-segment second cutting edge are different from each other in terms of the major / minor cutting edge angles relative to the feed direction, or... One of the first and second cutting edges is a single-segment cutting edge, and the first and / or second cutting edge segments of the other at least two-segment cutting edge are different from each other in terms of the primary / secondary cutting edge angles relative to the feed direction.

8. The step drill according to claim 7, characterized in that, The length of the first cutting edge section of the first cutting edge with at least two segments is less than the length of the first cutting edge section of the second cutting edge with at least two segments, and the radial distance from the first cutting edge section of the first cutting edge with at least two segments to the longitudinal axis of the stepped drill at the same axial position is greater than the radial distance from the first cutting edge section of the second cutting edge to the longitudinal axis of the stepped drill.

9. The step drill according to claim 1, characterized in that, At least one of the cutting edge segments of the first or second cutting edge of the at least two-segment type can be formed by locally reducing the material on the original one-segment cutting edge.

10. The step drill according to claim 1, characterized in that, The cutting edge segments of the first and second cutting edges, which are at least two-segmented, are composed of straight or curved segments.

11. The step drill according to claim 1, characterized in that, At least one of the horizontal cutting edge segments adjacent to the first cutting edge is radially offset from at least one of the horizontal cutting edge segments adjacent to the second cutting edge.

12. The step drill according to claim 1, characterized in that, The cutting edges formed by the same groove on different step sections are constructed to be at least partially different or identical in terms of their structure.

13. The step drill according to claim 1, characterized in that, The groove structure is a straight groove or a spiral groove.

14. A method for drilling and cutting a workpiece using a step drill, characterized in that, The step drill is a step drill according to any one of claims 1 to 13, the step drill having a hole-machining portion and at least two grooves extending on the hole-machining portion, the hole-machining portion comprising one or more stepped segments, each stepped segment forming at least two circumferentially distributed cutting edges with the at least two grooves, wherein the at least two cutting edges on at least one of the stepped segments include at least a first cutting edge and a second cutting edge. The method includes at least the following steps: The first material portion on the workpiece is cut using the first cutting edge, wherein the first material portion extends only a portion of the length of the first cutting edge; The second material portion on the workpiece is cut using the second cutting edge, wherein the second material portion extends only a portion of the length of the second cutting edge.

15. The method according to claim 14, characterized in that, The first material section includes at least one first sub-material section, and the second material section includes at least one second sub-material section adjacent to the first sub-material section.

16. The method according to claim 14, characterized in that, The first material section includes at least two first sub-material sections spaced apart from each other, and the second material section includes at least one second sub-material section located between the two first sub-material sections.

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