Step drill bit

Abstract

A drill bit (10) that includes: a shaft (12) extending along a drill axis (14); a transition section (16) which is connected to the shaft (12); a body section (18) having a front end (21) and comprising a plurality of axially superimposed, progressively increasing steps (20A-20M) including a first step (20A) at the front end and a last step (20M) connected to the transition section (16), wherein the first stage (20A) has two tip clamping grooves (42) which are each arranged at an angle of the tip clamping groove (44, 50) to the drill axis (14), the body section (18) further having two body clamping grooves (46) which each extend from the first stage (20A) to the transition section (16) and are arranged at an angle of the body clamping groove (48) which differs from the angle of the tip clamping groove (50); and a drill tip (21) located at the front end (21) of the body section (18) and having a cutting edge (28) that crosses the drill axis (14), wherein a first cutting surface (24) is located on one side of the cutting edge (28) and a second cutting surface (26) is located on an opposite side of the cutting edge (28), wherein the first cutting surface (24) has a first clearance angle (36) and the second cutting surface (26) has a second clearance angle (38) which differs from the first clearance angle (36); wherein each tip-chipping groove (42) extends to the first cutting surface (24) or the second cutting surface (26) to define at least part of an edge (32) of the first cutting surface (25) or the second cutting surface (26); wherein the angle of the body clamping groove (48) of each body clamping groove (46) is formed as a compound angle defined by a first angle of the body clamping groove (48) and a second angle of the body clamping groove (72), wherein the first angle of the body clamping groove (48) is measured between a center line (72) of each body clamping groove (46) and the drill axis (14) in a first plane, and the second angle of the body clamping groove (72) is measured between the center line (71) of each body clamping groove (46) and the drill axis (14) in a second plane which is orthogonal to the first plane; wherein the first angle of the body span groove (48) is between about 4.5 degrees and about 5.5 degrees, and wherein the second angle of the body span groove (72) is between about 1 degree and about 3 degrees.

Description

background

[0001] The present invention relates to accessories for power tools. The present invention relates in particular to step drills.

[0002] Further relevant prior art is disclosed in the following documents: DE 299 04 042 U1 and DE 203 04 580 U1.

[0003] Step drills are used in numerous applications and industries where a user needs to drill holes through a thin-walled workpiece. A step drill allows a user to drill holes of increasing size with a single drill bit. Summary

[0004] A drill bit with the features of claim 1 is specified. A drill bit with the features of claim 8 is also specified. Furthermore, a drill bit with the features of claim 14 is specified. Further advantageous embodiments are defined in the dependent claims. In one embodiment, the invention provides a drill bit comprising a shank extending along a drill axis, a transition section connected to the shank, and a body section having a front end and a plurality of axially superimposed steps of increasing size. The plurality of steps includes a first step at the front end and a final step connected to the transition section. The first step has two tip flutes, each arranged at an angle of the tip flute to the drill axis.The body section further features two body flutes, each extending from the first stage to the transition section and arranged at a body flute angle that differs from the tip flute angle. The drill also includes a drill tip located at the front end of the body section, which has a cutting edge intersecting the drill axis, a first cutting face on one side of the cutting edge, and a second cutting face on the opposite side. The first cutting face forms a first clearance angle. The second cutting face forms a second clearance angle, which differs from the first.

[0005] In a further embodiment, the invention provides a drill bit comprising a shank extending along a drill axis, a transition section connected to the shank, and a body section having a front end and a plurality of axially stacked steps of increasing size. The plurality of steps includes a first step at the front end and a final step connected to the transition section. The body section further comprises a body flute extending from the first step to the transition section. The drill bit also includes an indicator strip formed on an outer surface of one of the plurality of steps.

[0006] In a further embodiment, the invention provides a drill bit comprising a shank extending along a drill axis, a transition section connected to the shank, and a body section having a front end and a plurality of axially stacked steps of increasing size. The plurality of steps includes a first step at the front end and a final step connected to the transition section. The body section further comprises a body flute with a flute surface extending from the first step to the transition section. The drill bit also includes markings on the flute surface. These markings correspond to the axial depths of the plurality of steps. Less than half of the markings include indicators that distinguish the corresponding markings from the other markings.

[0007] In one embodiment, the invention provides a drill bit comprising a shank extending along a drill axis, a transition section connected to the shank, and a body section having a front end and a plurality of axially stacked steps of increasing size. The plurality of steps includes a first step at the front end and a final step connected to the transition section. Each step includes an axial back tap formed on an edge of the step closest to the front end. The body section further comprises a body flute extending from the first step to the transition section. The difference between the hole diameters formed by each pair of adjacent steps of the plurality of steps is less than 0.1 inch.

[0008] Further aspects of the invention will become apparent upon consideration of the detailed description and the accompanying drawings. Brief description of the drawings Fig. Figure 1 is a side view of a step drill according to an embodiment of the invention. Fig. Figure 2 is another side view of the step drill, rotated by 90°. Fig. 1. Fig. Figure 3 is an enlarged top view of the step drill in Fig. 1. Fig. Figure 4 is an enlarged perspective partial view of a section of the step drill in Fig. 1. Fig. 5A is a sectional view of the step drill in Fig. 2 along the intersection line 5A-5A. Fig. 5B is a sectional view of the step drill in Fig. 1 along the intersection line 5B-5B. Fig. Figure 6 is an enlarged side view of a section of the step drill bit in Fig. 1. Fig. Figure 7 is an enlarged side view of a section of the step drill bit in Fig. 2. Fig. Figure 8 is a side view of a step drill according to a further embodiment of the invention. Fig. Figure 9 is another side view of the step drill, rotated by 90°. Fig. 8. Fig. Figure 10 is an enlarged top view of the step drill in Fig. 8. Fig. Figure 11 is an enlarged perspective partial view of a section of the step drill in Fig. 8. Fig. Figure 12 is an enlarged side partial view of a section of the step drill bit in Fig. 9. Fig. Figure 13 is an enlarged side partial view of a section of the step drill in Fig. 9. Fig. Figure 14 is a side view of a step drill according to a further embodiment of the invention. Fig. Figure 15 is a side view of the step drill rotated by 90° in Fig. 14. Fig. Figure 16 is an enlarged top view of the step drill in Fig. 14. Fig. Figure 17 is an enlarged side partial view of a section of the step drill in Fig. 15. Fig. Figure 18 is a partial side view of a step drill according to a further embodiment of the invention. Fig. Figure 19 is another side view of the step drill, rotated by 90°. Fig. 18. Fig. Figure 20 is an enlarged top view of the step drill in Fig. 18. Fig. Figure 21 is an enlarged side partial view of a section of the step drill in Fig. 19. Fig. Figure 22 is a side view of a step drill according to a further embodiment of the invention. Fig. Figure 23 is another side view of the step drill, rotated by 90°. Fig. 22. Fig. 24 is a bottom view of the step drill in Fig. 22. Fig. Figure 25 is a sectional view of the step drill bit in Fig. 22 along the intersection line 25-25. Fig. Figure 26 is an enlarged top view of the step drill in Fig. 22. Fig. Figure 27 is an enlarged side partial view of a section of the step drill in Fig. 23. Fig. Figure 28 is a side view of a step drill according to a further embodiment of the invention. Fig. Figure 29 is another side view of the step drill, rotated by 90°. Fig. 28. Fig. Figure 30 is an enlarged top view of the step drill in Fig. 28. Fig. Figure 31 is an enlarged side partial view of a section of the step drill in Fig. 29. Fig. Figure 32 is a side view of a step drill according to a further embodiment of the invention. Fig. Figure 33 is another side view of the step drill, rotated by 90°. Fig. 32. Fig. Figure 34 is an enlarged top view of the step drill in Fig. 32. Fig. Figure 35 is an enlarged side partial view of a section of the step drill in Fig. 33. Fig. Figure 36 is a side view of a step drill according to a further embodiment of the invention. Fig. Figure 37 is another side view of the step drill, rotated by 90°. Fig. 36. Fig. Figure 38 is an enlarged top view of the step drill in Fig. 36. Fig. Figure 39 is an enlarged side partial view of a section of the step drill in Fig. 36. Fig. Figure 40 is a side view of a step drill according to a further embodiment of the invention. Fig. Figure 41 is another side view of the step drill, rotated by 90°. Fig. 40. Fig. Figure 42 is an enlarged top view of the step drill in Fig. 40. Fig. Figure 43 is an enlarged side partial view of a section of the step drill in Fig. 41. Fig. Figure 44 is a side view of a step drill according to a further embodiment of the invention. Fig. Figure 45 is another side view of the step drill, rotated by 90°. Fig. 44. Fig. Figure 46 is an enlarged top view of the step drill in Fig. 44. Fig. Figure 47 is an enlarged side partial view of a section of the step drill in Fig. 45. Fig. Figure 48 is a side view of a step drill according to a further embodiment of the invention. Fig. Figure 49 is another side view of the step drill, rotated by 90°. Fig. 48. Fig. 50 is an enlarged top view of the step drill in Fig. 48. Fig. Figure 51 is an enlarged side partial view of a section of the step drill in Fig. 49. Fig. Figure 52 is a perspective view of the step drill according to a further embodiment of the invention. Fig. 53 shows performance data for comparing the step drill bit in Fig. 1 with other step drills in tabular form. Fig. Figure 54 is a schematic sectional view of a step drill, which represents a design criterion for avoiding jamming.

[0009] Before embodiments of the invention are explained in detail, it should be noted that the invention is not limited in its application to the details of the construction and the arrangement of components as described in the following description or illustrated in the following drawings. Other embodiments of the invention are possible, and it can be implemented or carried out in various ways. Detailed description

[0010] Fig. 1 and Fig. Figure 2 represents a step drill 10 comprising a shank 12, a transition section 16, and a body section 18. The shank 12 is designed to engage with a power tool for rotating the step drill 10 about a drill axis 14. The transition section 16 is formed between the shank 12 and the body section 18. The body section 18 has thirteen axially stacked, progressively larger steps 20A-20M between a drill tip 21 and the transition section 16. The steps 20A-20M are axially stacked such that they are coaxially aligned along the drill axis 14. Furthermore, the stages 20A-20M become progressively larger in that the size (for example, the diameter) of the stages 20A-20M gradually increases from the drill tip 21 or a front end of the body section 18 towards the transition section 16.

[0011] Each of the thirteen stages 20A-20M of body section 18 has, as in Fig. Figure 1 shows a step height 56A-56M. The step heights 56A-56M need not be the same for all steps. In some embodiments, for example, steps corresponding to common drill diameters (e.g., 0.5 inch, 0.75 inch) may have greater heights so that a user can more easily handle the step drill and stop at these corresponding steps. The illustrated steps include a first step 20A at the front end of the body section 18 and a final step 20M connected to the transition section 16. In the illustrated embodiment, the first step 20A has a diameter of approximately 0.125 inch, and the final step 20M has a diameter of approximately 0.505 inch. The intermediate steps 20B-20L, located between the first and final steps 20A-20M, have progressively increasing diameters in the range of 0.125 inch to 0.505 inch.In other embodiments, the body section 18, as further described below, may have fewer or more steps, and / or each step 20A-20M may have a different diameter.

[0012] A step-phase 58 is, as in Fig. Figure 2 shows a chamfer 58 formed between each pair of adjacent steps 20A-20M. The step chamfer 58 connects two adjacent steps at a flank angle 60 to create a smoother transition between the two adjacent steps. The flank angle 60 is measured between a surface of the corresponding step chamfer 58 and a plane 61 extending perpendicular to the drill axis 14. In the illustrated embodiment, the flank angle 60 for all step chamfers 58 is between approximately 40° and approximately 50°, and particularly approximately 45°. In other embodiments, the flank angle 60 may be comparatively larger or smaller, or the step chamfers 58 may be omitted.

[0013] The drill bit 21 has, as further referenced above Fig. Figure 1 shows a primary tip angle 22 measured across the drill axis 14, between approximately 130° and approximately 140°, and in particular of approximately 135°. The drill tip 21 is, as shown in Fig. Figure 3 shows a tip with a double back taper, having two first cutting surfaces 24 and two second cutting surfaces 26. Each first cutting surface 24 is located on a side opposite a corresponding second cutting surface 26 of a cutting edge 28 of the drill tip 21. The drill tip 21 has a cutting width 30, measured between the cutting edges 32 of the cutting surfaces 24 and 26, of approximately 0.022 inches and approximately 0.028 inches, and particularly approximately 0.025 inches. In other embodiments, the primary tip angle 22 and / or the cutting width 30 may be comparatively larger or smaller.

[0014] Each first cutting surface 24 has, as in Fig. Figure 6 shows a width 40 of the first cutting surface between approximately 0.012 inches and approximately 0.014 inches, and particularly approximately 0.013 inches. Each first cutting surface 24 further has a clearance angle 36 of the first cutting edge, which represents the inclination of the first cutting surface 24 with respect to a reference axis 37 that is perpendicular to the drill axis 14. The clearance angle 36 of the first cutting edge is between approximately 10° and approximately 20°, and particularly approximately 15°. Each second cutting surface 26 has a clearance angle 38 of the second cutting edge, which represents the inclination of the second cutting surface 26 with respect to the reference axis 37. The clearance angle 38 of the second cutting edge is between approximately 25° and approximately 35°, and particularly approximately 30°. In other embodiments, the cutting widths 40 and / or the clearance angles 36, 37 of the cutting edges may be comparatively larger or smaller.

[0015] The first stage 20A, as further referenced above, shows Fig. Figure 3 shows two tip clamping grooves 42 extending to the drill tip 21. Each of the tip clamping grooves 42 has a U-shaped cross-section with a radius 52 ( Fig. 4) the diameter of the tip clamping groove is between approximately 0.035 inches and approximately 0.045 inches, and in particular of approximately 0.045 inches. The tip clamping grooves 42 are approximately in the shape of a quarter circle, the ends of which extend at an angle 54 of between approximately 85° and approximately 95°, and in particular of approximately 90°. In other embodiments, the radii 52 and / or the angles 54 of the tip clamping grooves 42 may be comparatively larger or smaller.

[0016] Each top span groove 42 is, as with reference to Fig. 1 and Fig. 4 can be seen, arranged at a compound angle with respect to the tip axis 14. The compound angle is formed by an angle 44 of the tip clamping groove ( Fig. 1) and a second angle 50 of the tip clamping groove ( Fig. 4) formed. The two angles 44, 50 of the tip clamping groove 42 are spatially located in one plane, but are determined and measured in such a way that the composite angle is considered in two right-angled planes. The first angle 44 of the tip clamping groove is, in a first direction (for example, from the viewing point in Fig. The second angle 50 of the tip clamping groove 42 is measured in a second direction (for example, from the viewing point in 1), between a center line of each tip clamping groove 42 and the drill axis 14. Fig. 4) seen, measured between the center line of each tip-chipping groove 42 and the drill axis 14. In the illustrated embodiment, each first angle 44 of the tip-chipping groove 42 with respect to the drill axis 14 is, in Fig. 1 seen, between approximately 36° and approximately 46°, and in particular approximately 41°. Furthermore, every second angle of 50° of the tip flute with respect to the drill axis 14 is, in Fig. 4 seen, between approximately 10° and approximately 20°, and in particular approximately 15°. In other embodiments, the first angles 44 of the tip clamping grooves and / or the second angles 50 of the tip clamping grooves may be comparatively larger or smaller.

[0017] Body section 18 shows, as with reference to Fig. As can be seen in Figures 1-2, two body clamping grooves 46 are arranged on diametrically opposite sides of the drill axis 14. Each body clamping groove 46 extends from the first stage 20A to the transition section 16. Like the tip clamping grooves 42, the body clamping grooves 46 are arranged at compound angles with respect to the drill axis 14. A first angle 48 of the body clamping grooves of each clamping groove 46 is, as shown in Fig. Figure 1 shows, viewed in a first direction, measured between a center line 71 of the body span groove 46. A second angle 72 of the body span grooves of each body span groove is, as shown in Fig. Figure 2 shows the angles of the body clamping grooves measured in a second direction, which differs from the first direction (for example, when the step drill 10 is rotated 90° about the drill axis 14), between the center line 71 of the body clamping groove 46. In the illustrated embodiment, each first angle 48 of the body clamping grooves is between approximately 4.5° and approximately 5.5° with respect to the drill axis 14, and in particular approximately 5°.

[0018] Furthermore, every second angle 72 of the body clamping grooves is between approximately 1° and approximately 3° with respect to the drill axis, and in particular approximately 2°. In other embodiments, the first angles 48 of the body clamping grooves and / or the second angles 72 of the body clamping grooves may be comparatively larger or smaller.

[0019] Each body span of 46 is, as with reference to Fig. 5A and Fig. As shown in Figure 5B, the body clamping groove has a radius 62 of approximately 0.06 inches to approximately 0.08 inches, and in particular approximately 0.07 inches. Each body clamping groove 46 further has a width or opening 64, which is measured between an edge 66 and a lip 68 of a corresponding step 20A-20M. In the illustrated embodiment, the opening 64 of the body clamping groove is between approximately 52.5° and approximately 62.5°, and in particular approximately 57.5°. Depending on the step, the lip 68 is arranged at an offset 70 to the drill axis 14. The offset 70 can be different for each of the steps 20A-20M. Fig. For example, 5a represents the offset of 70M for the last stage of 20M, which is approximately 0.14 inches in one direction. In contrast, Fig. 5B represents the offset 70C for the third stage 20C, which is approximately 0.01 inch in a second direction.

[0020] The thirteen steps 20A-20M of the step drill 10 each include three types of back tapers, that is, an axial back taper 74 ( Fig. 7), a diametrical undercut 76 ( Fig. 7) and a radial undercut 78 ( Fig. 3) The axial undercut 74 of each stage 20A-20M is, as in Fig. Figure 7 shows the distance by which an upper edge 80 of the step (that is, the edge of the step closest to the front end of the body section 18) is displaced along the drill axis 14 toward the front end as the upper edge 80 approaches a front edge 82 of the step (that is, the edge of the step at the body clamping groove 46). In the illustrated embodiment, the axial back taper 74 of each step 20A-20M measures between approximately 0.007 inches and approximately 0.013 inches, and in particular approximately 0.01 inch. In other embodiments, the axial back taper 74 may be comparatively larger or smaller.

[0021] The diametrical undercut 76 of each stage 20A-20M is, as further referenced in Fig. Figure 7 shows the degree by which an outer circumferential surface 84 of the step tapers radially inwards or outwards along the drill axis 14. In the illustrated embodiment, the diametral back taper 76 of each step 20A-20M measures between approximately -1° and approximately 0°. In some embodiments, the diametral back taper 76 can be omitted (i.e., it can be 0°). In other embodiments, the diametral back taper 76 can have a comparatively larger degree value or be positive.

[0022] The radial undercut 78 is, as with reference to Fig. Figure 3 shows the amount by which a radius 68 of steps 20A-20M decreases when the outer surface of step 20A-20M moves away from the front edge 82. That is, a circle 88 with a constant diameter is in Fig. Figure 3, with dashed lines, represents the nominal diameter of the third stage 20C. The radial back taper 78 increases continuously along an angle 34 from the front edge 82 of the stage to a point where it reaches its maximum value. The term "radial back taper" used here refers to the maximum distance by which the radius 86 of the stage 20C decreases radially inward from the nominal diameter 88. In the illustrated embodiment, the radial back taper 78 of each stage 20A-20M measures between approximately 0.002 inches and approximately 0.008 inches, and particularly approximately 0.005 inches. Furthermore, the angle 34 of the radial back taper of each stage 20A-20M from the front edge 82 is between approximately 40° and approximately 50°, and particularly approximately 45°.In other embodiments, the radial undercut 78 and / or the angle 34 of the radial undercut may be comparatively larger or smaller.

[0023] Fig. Figures 8-13 represent a step drill 110 according to a further embodiment of the invention. The step drill 110 contains structures similar to those of the step drill 10 in Fig. 1-7 are identical, and identical structures have been provided with the same reference numerals, increased by 100. The step drill 110 can include any combination of structures, dimensions, or a range of dimensions from the preceding or subsequent embodiment(s); however, only those structures of the step drill 110 that have not yet been described in relation to the preceding embodiments are described in detail below.

[0024] The 110 step drill bit contains six axially stacked, progressively larger steps, 120A-120F. The first step, 120A, has a diameter of approximately 0.118 inches, and the last step, 120F, has a diameter of approximately 0.505 inches. As referenced in Fig. As can be seen in figure 9, a second angle of 172 degrees is the body span, which, in Fig. 9, seen between a drill axis 114 and a center line of the radius 171 of the body flute, is formed between approximately 1.7° and approximately 1.9°, and in particular approximately 1.8°. The step drill 110 closes, as with reference to Fig. As can be seen in Figure 10, a cutting width of 130 is between approximately 0.029 inches and approximately 0.035 inches, and in particular of approximately 0.032 inches. A first cutting surface width of 140 is, as with reference to Fig. 12 can be seen, between approximately 0.011 inches and approximately 0.021 inches, and in particular approximately 0.016 inches. A radius of 152 of the tip span groove ( Fig. 11) of the step drill is between 0.055 inch and 0.075 inch, and in particular approximately 0.065 inch.

[0025] The step drill 110 closes, as in Fig. Figure 10 shows a radial back taper 178 measuring between approximately 0.002 inches and approximately 0.008 inches, and in particular approximately 0.005 inches. The drill 110 further includes, as shown in Fig. Figure 13 shows a diametrical back taper 176 measuring between approximately 0° and approximately 1°, and in particular approximately 1°. Furthermore, the step drill 110 includes an axial back taper 174 measuring between approximately 0.007 inch and approximately 0.013 inch, and in particular approximately 0.01 inch.

[0026] Fig. Figures 14-17 represent a step drill 210 according to a further embodiment of the invention. The step drill 210 contains structures similar to those of the step drill 10 in Fig. 1-7 are identical, and identical structures have been provided with the same reference numerals, increased by 200. The step drill 210 can include any combination of features, dimensions, or a range of dimensions from the preceding or subsequent embodiments; however, only those structures of the step drill 210 that have not yet been described in detail with respect to the preceding embodiments are described below.

[0027] The step drill 210 contains nine axially stacked, progressively larger steps 220A-220I. A first step 220A has a diameter of approximately 0.255 inches, and a last step 220I has a diameter of approximately 0.755 inches. The angle 244° of the tip flute is, as with reference to Fig. As can be seen in Figure 14, the angle is between approximately 54° and approximately 64°, and in particular approximately 59°. Furthermore, a first angle 248 of the body span is between approximately 9.2° and approximately 11.2°, and in particular approximately 10.2°. A second angle 272 of the body span is, as shown with reference to Fig. As can be seen in Figure 15, the angle is between approximately 2.4° and approximately 4.4°, and in particular approximately 3.4°. The step drill 210 concludes, as with reference to Fig. As can be seen in Figure 16, a cutting width of 230 is between approximately 0.028 inch and approximately 0.034 inch, and in particular of approximately 0.031 inch.

[0028] The step drill 210 closes, as in Fig. Figure 16 shows a radial back taper 278 measuring between approximately 0.002 inches and approximately 0.008 inches, and in particular approximately 0.005 inches. The step drill 210, as shown in Fig. Figure 17 shows a diametrical back taper 276 measuring between approximately 0° and approximately 1°, and in particular approximately 0.5°. Furthermore, the step drill 210 includes an axial back taper 274 measuring between approximately 0.007 in and approximately 0.013 in, and in particular approximately 0.01 in.

[0029] Fig. Figures 18-21 represent a step drill 310 according to a further embodiment of the invention. The step drill 310 contains structures similar to those of the step drill 10 in Fig. 1-7 are identical, and identical structures have been provided with the same reference numerals, increased by 300. The step drill 310 can include any combination of structures, dimensions, or a range of dimensions from the preceding or subsequent embodiments; however, only those structures of the step drill 310 that have not yet been described in relation to the preceding embodiments are described in detail below.

[0030] The 310 step drill contains twelve axially stacked, progressively larger steps, 320A-320L. A first step, 320A, has a diameter of approximately 0.188 inches, and a last step, 320L, has a diameter of approximately 0.88 inches. The 310 step drill, as described in [reference to] Fig. As can be seen in Figure 18, the body clamping groove has a first angle 348, which is between approximately 6.8° and approximately 8.8°, and in particular approximately 7.8°. The step drill 310 contains, as with reference to Fig. As can be seen in Figure 19, a second angle 372 of the body span groove is between approximately 4.6° and approximately 6.6°, and in particular approximately 5.6°.

[0031] The step drill 310 closes, as in Fig. Figure 20 shows a radial back taper 378 measuring between approximately 0.002 inches and approximately 0.008 inches, and in particular approximately 0.005 inches. The step drill 310, as shown in Fig. Figure 21 shows a diametrical back taper 376 measuring between approximately -1° and approximately 0°, and in particular approximately 0°. Furthermore, the step drill 310 includes an axial back taper 374 measuring between approximately 0.007 inch and approximately 0.013 inch, and in particular approximately 0.01 inch.

[0032] Fig. Figures 22-27 represent a step drill 410 according to a further embodiment of the invention. The step drill 410 contains structures similar to those of the step drill 10 in Fig. 1-7 are identical, and identical structures have been provided with the same reference numerals, increased by 400. The step drill 410 can include any combination of structures, dimensions, or a range of dimensions from the preceding or subsequent embodiments; however, only those structures of the step drill 410 that have not yet been described in relation to the preceding embodiments are described in detail below.

[0033] The 410 step drill contains ten axially stacked, progressively larger steps, 420A-420J. The first step, 420A, has a diameter of approximately 0.25 inches, and the last step, 420J, has a diameter of approximately 1.38 inches. The 410 step drill, as described in the following, Fig. As can be seen in Figure 22, the body clamping groove forms a first angle 448, which is between approximately 16.4° and approximately 18.4°, and in particular approximately 17.4°. The step drill 410, as shown with reference to Fig. As can be seen in Figure 23, a second angle 472 of the body clamping groove is formed, which is between approximately 3.6° and approximately 5.6°, and in particular approximately 4.6°. The step drill 410, as referred to in Figure 23, includes a second angle 472 of the body clamping groove, which is between approximately 3.6° and approximately 5.6°, and in particular approximately 4.6°. The step drill 410 includes, as referred to in Figure 23, a second angle 472 of the body clamping groove, which is between approximately 3.6° and approximately 5.6°, and in particular approximately 4.6°. Fig. 24 and Fig. Figure 25 shows a body flute radius 462, which is between approximately 0.084 inches and approximately 0.104 inches, and in particular approximately 0.094 inches. Furthermore, the step drill 410 includes a body flute 464, which measures between approximately 61° and approximately 71°, and in particular approximately 66°.

[0034] The step drill 410 closes, as in Fig. Figure 26 shows a radial back taper 478 measuring between approximately 0.002 inches and approximately 0.008 inches, and in particular approximately 0.005 inches. The step drill 410, as shown in Fig. Figure 27 shows a diametrical back taper 476 measuring between approximately 0° and approximately 1°, and in particular approximately 0.5°. Furthermore, the step drill 410 includes an axial back taper 474 measuring between approximately 0.007 in and approximately 0.013 in, and in particular approximately 0.01 in.

[0035] Fig. Figures 28-31 represent a step drill 510 according to a further embodiment of the invention. The step drill 510 contains structures similar to those of the step drill 10 in Fig. 1-7 are identical, and identical structures have been provided with the same reference numerals, increased by 500. The step drill 510 can include any combination of structures, dimensions, or a range of dimensions from the preceding or subsequent embodiments; however, only those structures of the step drill 510 that have not yet been described in relation to the preceding embodiments are described in detail below.

[0036] The 510 step drill bit contains six axially stacked, progressively larger steps, 520A-520F. A first step, 520A, has a diameter of approximately 0.188 inches, and a last step, 520F, has a diameter of approximately 0.505 inches. The 510 step drill bit, as described in reference to Fig. As can be seen in Figure 28, the body clamping groove forms a first angle 548, which is between approximately 8.8° and approximately 10.8°, and in particular approximately 9.8°. The step drill 510, as described in Figure 28, Fig. 29 shows a second angle 572 of the body span groove, which is between approximately 4.3° and approximately 6.3°, and in particular approximately 5.3°.

[0037] The step drill 510 closes, as in Fig. Figure 30 shows a radial back taper 578 measuring between approximately 0.002 inches and approximately 0.008 inches, and in particular approximately 0.005 inches. The step drill 510 further includes, as shown in Fig. Figure 31 shows a diametrical back taper 576 measuring between approximately -1.5° and approximately -0.5°, and in particular approximately -1°. Furthermore, the step drill 510 includes an axial back taper 574 measuring between approximately 0.015 inch and approximately 0.021 inch, and in particular approximately 0.018 inch.

[0038] Fig. Figures 32-35 represent a step drill 610 according to a further embodiment of the invention. The step drill 610 contains structures similar to those of the step drill 10 in Fig. 1-7 are identical, and identical structures have been provided with the same reference numerals, increased by 600. The step drill 610 can include any combination of structures, dimensions, or a range of dimensions from the preceding or subsequent embodiments; however, only those structures of the step drill 610 that have not yet been described in relation to the preceding embodiments are described in detail below.

[0039] The 610 step drill contains twelve axially stacked, progressively larger steps, 620A-620L. A first step, 620A, has a diameter of approximately 0.188 inches, and a last step, 620L, has a diameter of approximately 0.88 inches. The 610 step drill, as described in [reference to] Fig. As can be seen in Figure 32, the body clamping groove forms a first angle 648 between approximately 13.3° and approximately 15.3°, and in particular of approximately 14.3°. The step drill 610, as with reference to Fig. 33 can be seen, a second angle 672 of the body span groove between approximately 5.3° and approximately 7.3°, and in particular of approximately 6.3°.

[0040] The step drill 610 closes, as in Fig. Figure 34 shows a radial back taper 678 measuring between approximately 0.002 inches and approximately 0.008 inches, and in particular approximately 0.005 inches. The step drill 610, as shown in Fig. Figure 35 shows a diametrical back taper 676 measuring between approximately 0° and approximately 1°, and in particular approximately 0.5°. Furthermore, the step drill 610 includes an axial back taper 674 measuring between approximately 0.007 in and approximately 0.013 in, and in particular approximately 0.01 in.

[0041] Fig. Figures 36-39 represent a step drill 710 according to a further embodiment of the invention. The step drill 710 contains structures similar to those of the step drill 10 in Fig. 1-7 are identical, and identical structures have been provided with the same reference numerals, increased by 700. The step drill 710 can include any combination of structures, dimensions, or a range of dimensions from the preceding or subsequent embodiments; however, only those structures of the step drill 710 that have not yet been described in relation to the preceding embodiments are described in detail below.

[0042] The 710 step drill contains fourteen axially stacked, progressively larger steps, 720A-720N. A first step, 720A, has a diameter of approximately 0.188 inches, and a last step, 720L, has a diameter of approximately 1 inch. The 710 step drill, as described in [reference to] Fig. 37 shows a second angle 772 of the body span groove, which is between approximately 3° and approximately 5°, and in particular approximately 4°.

[0043] The step drill 710 closes, as in Fig. Figure 38 shows a radial back taper 778 measuring between approximately 0.002 inches and approximately 0.008 inches, and in particular approximately 0.005 inches. The step drill 710 further includes, as shown in Fig. Figure 39 shows a diametrical back taper 776 measuring between approximately 0.5° and approximately 1.5°, and in particular approximately 1°. Furthermore, the step drill 710 includes an axial back taper 774 measuring between approximately 0.012 inch and approximately 0.018 inch, and in particular approximately 0.015 inch.

[0044] Fig. Figures 40-43 represent a step drill 810 according to a further embodiment of the invention. The step drill 810 contains structures similar to those of the step drill 10 in Fig. 1-7 are identical, and identical structures have been provided with the same reference numerals, increased by 800. The step drill 810 can include any combination of structures, dimensions, or a range of dimensions from the preceding or subsequent embodiments; however, only those structures of the step drill 810 that have not yet been described in relation to the preceding embodiments are described in detail below.

[0045] The 810 step drill contains seventeen axially stacked, progressively larger steps, 820A-820Q. A first step, 820A, has a diameter of approximately 0.188 inches, and a last step, 820Q, has a diameter of approximately 1.13 inches. The 810 step drill, as described in [reference to] Fig. As can be seen in Figure 40, the body clamping groove forms a first angle 848, which is between approximately 12° and approximately 14°, and in particular approximately 13°. The step drill 810, as with reference to Fig. 41 can be seen, a second angle 872 of the body span groove between approximately 4.2° and approximately 6.2°, and in particular of approximately 5.2°.

[0046] The step drill 810 closes, as in Fig. Figure 42 shows a radial back taper 878 measuring between approximately 0.002 inches and approximately 0.008 inches, and in particular approximately 0.005 inches. The step drill 810, as shown in Fig. Figure 43 shows a diametrical back taper 876 measuring between approximately 1° and approximately 2°, and in particular approximately 1°. Furthermore, the step drill 810 includes an axial back taper 874 measuring between approximately 0.012 inch and approximately 0.018 inch, and in particular approximately 0.015 inch.

[0047] Fig. Figures 44-47 represent a step drill 910 according to a further embodiment of the invention. The step drill 910 contains structures similar to those of the step drill 10 in Fig. 1-7 are identical, and identical structures have been provided with the same reference numerals, increased by 900. The step drill 910 can include any combination of structures, dimensions, or a range of dimensions from the preceding or subsequent embodiments; however, only those structures of the step drill 910 that have not yet been described in relation to the preceding embodiments are described in detail below.

[0048] The 910 step drill contains seventeen axially stacked, progressively larger steps, 920A-920Q. A first step, 920A, has a diameter of approximately 0.25 inches, and a last step, 920Q, has a diameter of approximately 1.224 inches. The 910 step drill, as described in the following, Fig. As can be seen in Figure 44, the body clamping groove forms a first angle 948, which is between approximately 13.4° and approximately 15.4°, and in particular approximately 14.4°. The step drill 910, as referred to in Figure 44, Fig. 45 can be seen, a second angle 972 of the body span groove, which is between approximately 3.7° and approximately 5.7°, and in particular approximately 4.7°.

[0049] The step drill 910 closes, as in Fig. Figure 46 shows a radial back taper 978 measuring between approximately 0.002 inches and approximately 0.008 inches, and in particular approximately 0.005 inches. The step drill 910, as shown in Fig. Figure 47 shows a diametrical back taper 976 measuring between approximately 0.5° and approximately 1.5°, and in particular approximately 1°. Furthermore, the step drill 910 includes an axial back taper 974 measuring between approximately 0.012 inch and approximately 0.018 inch, and in particular approximately 0.015 inch.

[0050] Fig. Figures 48-51 represent a step drill 1010 according to a further embodiment of the invention. The step drill 1010 contains structures similar to those of the step drill 10 in Fig. 1-7 are identical, and identical structures have been provided with the same reference numerals, increased by 1000. The step drill 1010 can include any combination of structures, dimensions, or a range of dimensions from the preceding or subsequent embodiments; however, only those structures of the step drill 1010 that have not yet been described in relation to the preceding embodiments are described in detail below.

[0051] The step drill 1010 comprises fifteen axially stacked, progressively larger steps 1020A-1020O. A first step 1020A has a diameter of approximately 0.25 inches, and a last step 10200 has a diameter of approximately 0.138 inches. The step drill 1010, as described in the following, Fig. As can be seen in Figure 48, the body span groove forms a first angle 1048, which is between approximately 15.7° and approximately 17.7°, and in particular approximately 16.7°. The step drill 1010, as with reference to Fig. As can be seen in Figure 49, a second angle 1072 of the body span is set, which is between approximately 4.1° and approximately 6.1°, and in particular approximately 5.1°.

[0052] The step drill 1010 closes, as in Fig. Figure 50 shows a radial back taper 1078 measuring between approximately 0.002 inches and approximately 0.008 inches, and in particular approximately 0.005 inches. The step drill 1010, as shown in Fig. Figure 51 shows a diametrical back taper 1076 measuring between approximately 0.5° and approximately 1.5°, and in particular approximately 1°. Furthermore, the step drill 1010 includes an axial back taper 1074 measuring between approximately 0.012 inch and approximately 0.018 inch, and in particular approximately 0.015 inch.

[0053] Fig. Figure 52 represents a step drill 1110 according to a further embodiment of the invention. The step drill 1110 contains structures similar to those of the step drill 10 in Fig. 1-7 are identical, and identical structures have been provided with the same reference numerals, increased by 1100. The step drill 1110 can include any combination of structures, dimensions, or a range of dimensions from the preceding or subsequent embodiments; however, only those structures of the step drill 1110 that have not yet been described in relation to the preceding embodiments are described in detail below.

[0054] The step drill 1110 comprises twelve axially arranged, progressively larger steps 1120A-1120L and at least one body flute 1146 extending through the steps 1120A-1120L. The step drill 1110 further comprises markings 1190C-1190L, which are applied to each step 1120A, 1120L. In some embodiments, the markings 1190C-1190L are laser etched into an outer surface 1202 of the step drill 1110. The markings 1190C-1190L contrast with a surface finish of the step drill 1110, so that the markings 1190C-1190L are clearly visible. The step drill bit 1110, for example, may have a black oxide surface, and the markings 1190C-1190L may be colored accordingly (for example, white) to stand out sufficiently from the black oxide surface.

[0055] The markings shown, 1190C-1190L, contain the numbers 1194 and marking strips 1198. The numbers 1194 indicate the diameter of the corresponding stages 1120A-1120L.

[0056] In the illustrated embodiment, the numbers 1190 are formed on a chip groove surface 1206, which partially forms the body chip groove 1146. When the numbers 1194 are positioned on the chip groove surface 1206 and within the body chip groove 1146, they are less susceptible to wear during operation of the step drill 1110.

[0057] The identification strips 1198 form markings that help to distinguish some of the markings (for example, markings 1190D, 1190F, 1190J, 1190L) from other markings. The illustrated identification strips 1198 are positioned on non-adjacent steps such that, in the arrangement of steps, not both of two directly adjacent steps have identification strips. In the illustrated embodiment, the identification strips 1198 are positioned, for example, on steps 1120D, 1120F, 1120J, 1120L, which correspond to commonly used hole diameters (for example, 3 / 8 inch, 1 / 2 inch, 3 / 4 inch, and 7 / 8 inch). When the drill 110 is rotated around the drill axis 1114 at operating speed (for example 200, 2000 rpm), the marking stripes 1198 form easily recognizable, visible stripes for these special stages.In other embodiments, the marking strips 1198 can be positioned on steps that have different diameters.

[0058] In the illustrated embodiment, the marking strips 1198 are present both on the slot surface 1206 and on the outer surfaces 1210 of the corresponding stages (for example, stages 1120D, 1120F, 1120J, 1120L). The illustrated marking strips 1198 are interrupted at the transition from the slot surface 1206 to the outer surfaces 1210, but can alternatively be formed as continuous strips. Furthermore, the illustrated marking strips 1198 do not extend completely around the outer surface 1210 of each corresponding stage. Instead, the marking strips 1198 extend only around a section of each outer surface 1210. In some embodiments, the marking strips 1198 extend around less than half of the outer surface 1210 of each stage. In the illustrated embodiment, the marking stripes 1198 extend around less than a quarter of the outer surface 1210 of each step.In other embodiments, the marking strips 1198 may only be present on the groove surface 1206 or only on the outer surfaces 1210 of the corresponding steps.

[0059] Fig. Figure 53 shows tabular data for a step drill according to the present invention. As shown in the tables, the step drill of the present invention performs better than competing products of comparable size. The test results for the step drill 10 are marked “Double Back Grind”. A step drill with a similar design but a drill point with only one back grind is marked “Single Back Grind”, and competing designs are marked “Manufacturer AE”. The step drill 10 was tested under various test conditions, including a sliding test (i.e., a test at lower speed) and a so-called Clausing test (i.e., a test at higher speed). Table 1 and Table 2 in Fig. Table 53 represents the number of holes drilled during the lifetime test. Tables 3 and 4 show the time (in seconds) required to cut the holes specified in Tables 1 and 2. Furthermore, Table 5 shows the time a drill bit takes to penetrate a workpiece during the Clausing test. As can be seen from the tables, drill bit 10 performs better than the single-back-ground drill bit design and the other brands under both test conditions, with a larger number of holes drilled and shorter cutting times.

[0060] The in Fig. The improved performance shown in section 53 can be partly attributed to the fact that step drills of the embodiments described above have a jam-resistant design. In particular, when the step drill is used with a cordless drill, jamming of the step drill can be significantly reduced by limiting the difference in diameter between adjacent steps. Each step drill has, as referenced in section 53, a jam-resistant design. Fig. 54 can be seen, a diameter D1 of the first stage, a diameter D N the last stage as well as a total number of N stages. The diameters of the stages increase progressively from the first stage to the last stage, until finally the final hole size with diameter D is reached. N has been reached. The final diameter D is reached. NThe required number of steps N should be reduced to a minimum to keep the drill compact (i.e., shorter in the direction of the drill's axis of rotation) while maintaining sufficient axial length to accommodate the appropriate workpiece thickness. However, to achieve a jam-proof design, the area of ​​material M removed with each successive step should remain below a predetermined threshold. The area of ​​material M removed between adjacent steps corresponds to the difference in the hole cross-sectional areas determined by adjacent steps n and n-1, that is, M = ¼ π (D n 2 - D n-1 2In some embodiments, the difference between the hole diameters formed by each pair of adjacent steps (which is the same as the difference between the diameters of each pair of adjacent steps) is less than 0.1 inch. That is, the difference between the hole diameters is approximately 0.0625 inch (or 1 / 16 inch).

[0061] The in Fig. The performance improvement shown in section 53 is partly due to the presence of the axial, diametrical, and radial back tapers described above. In particular, the axial back taper helps to increase the feed rate of the drill through a workpiece. A larger axial back taper generally increases the feed rate, thus reducing the cutting time for the step drill to bore the in Fig. The number of holes listed in tabular form is reduced to 53.

[0062] The invention thus provides an improved step drill. Although the invention has been described with reference to certain exemplary embodiments, the scope of protection and the spirit of one or more independent aspects of the invention, as described, include modifications and variations. Various features and advantages of the invention are set forth in the following claims.

[0063] Other possible embodiments of the invention are: 1. Drill bit, which includes: a shaft extending along a drill axis; a transition section that is connected to the shaft; a body section having a front end and a plurality of axially superimposed, progressively larger stages, including a first stage at the front end and a final stage connected to the transition section, wherein the first stage has two tip-shaped clamping grooves, each arranged at an angle of the tip-shaped clamping groove to the drill axis, the body section further having two body-shaped clamping grooves, each extending from the first stage to the transition section and arranged at an angle of the body-shaped clamping groove that differs from the angle of the tip-shaped clamping groove; and a drill tip located at the front end of the body section and having a cutting edge that crosses the drill axis, wherein a first cutting surface is on one side of the cutting edge, and a second cutting surface is on the opposite side of the cutting edge, the first cutting surface having a first clearance angle, and the second cutting surface having a second clearance angle that differs from the first clearance angle. 2. Drill according to embodiment 1, wherein the second clearance angle is approximately twice as large as the first clearance angle. 3. Drill according to embodiment 1, wherein the first clearance angle with respect to a reference axis is between approximately 10° and approximately 20°, which is perpendicular to the drill axis, and the second clearance angle with respect to the reference axis is between approximately 25° and approximately 35°. 4. Drill according to embodiment 1, wherein each tip flute, viewed along the drill axis, has a U-shaped cross-section. 5. Drill according to embodiment 4, wherein each tip-chipping groove extends around approximately a quarter circle. 6. Drill according to embodiment 1, wherein the angle of the tip flute of each tip flute is formed as a compound angle, which has a first angle of the tip flute, which, viewed in a first direction, is measured between a center line of each tip flute and the drill axis, and a second angle of the tip flute, which, viewed in a second direction, is measured between the center line of each tip flute and the drill axis. 7. Drill according to embodiment 6, wherein the first angle of the tip flute is between approximately 36° and approximately 46° and the second angle of the tip flute is between approximately 10° and approximately 20°. 8. Drill according to embodiment 6, wherein the first angle of the tip flute is between approximately 54° and approximately 64° and the second angle of the tip flute is between approximately 10° and approximately 20°. 9. Drill according to embodiment 1, wherein the drill tip has a primary tip angle measured over the drill axis from the first cutting surface to the second cutting surface, which is between approximately 130° and approximately 140°. 10. Drill according to embodiment 1, wherein the angle of the body clamping groove of each body clamping groove is formed as a compound angle, which has a first angle of the body clamping groove, which, viewed in a first direction, is measured between a center line of each body clamping groove and the drill axis, and a second angle of the body clamping groove, which, viewed in a second direction, is measured between the center line of each body clamping groove and the drill axis. 11. Drill according to embodiment 10, wherein the first angle of the body clamping groove is between approximately 4.5° and approximately 5.5° and the second angle of the body clamping groove is between approximately 1° and approximately 3°. 12. Drill bit, which includes: a shaft extending along a drill axis; a transition section that is connected to the shaft; a body section having a front end and a plurality of axially superimposed, progressively larger stages, including a first stage at the front end and a final stage connected to the transition section, wherein the body section further has a body span groove that runs from the first stage to the transition section; and a marking strip formed on an outer surface of one of the multiple stages. 13. Drill according to embodiment 12, wherein the marking strip extends from the body clamping groove around at least one section of the outer surface of one of the plurality of steps. 14. Drill according to embodiment 13, wherein the marking stripe extends around less than half of the outer surface of one of the plurality of steps. 15. Drill according to embodiment 12, wherein the marking stripe contrasts with a surface texture of the body section. 16. Drill according to embodiment 12, wherein the marking stripe includes a laser etching in the outer surface of one of the plurality of steps. 17. Drill according to embodiment 12, wherein the marking strip is a first marking strip and further comprises a second marking strip which is formed on an outer surface of another of the plurality of steps. 18. Drill according to embodiment 17, wherein the other of the plurality of steps does not adjoin one of the plurality of steps. 19. Drill according to embodiment 12, wherein one of the plurality of steps has a diameter of 3 / 8 inch, 1 / 2 inch, 3 / 4 inch or 7 / 8 inch. 20. Drill bit, which includes: a shaft extending along a drill axis; a transition section that is connected to the shaft; a body section having a front end and a plurality of axially superimposed, progressively larger steps, including a first step at the front end and a final step connected to the transition section, the body section further comprising a body clamping groove having a clamping groove surface extending from the first step to the transition section; and Markings on the groove surface, wherein the markings correspond to axial depths of the plurality of steps, and less than half of the markings contain markings to distinguish the corresponding markings from the other markings. 21. Drill according to embodiment 20, wherein the markings include numbers indicating the diameter of the plurality of steps. 22. Drill according to embodiment 21, wherein each marking includes an identification strip formed around the corresponding number. 23. Drill according to embodiment 22, wherein the marking strip extends from the chip groove surface over at least a section of an outer surface of the corresponding step. 24. Drill according to embodiment 22, wherein each marking stripe contrasts with a surface finish of the chip groove surface. 25. Drill according to embodiment 20, wherein the markings include laser etchings in the chip groove surface. 26. Drill according to embodiment 20, wherein the markings are located on non-adjacent steps of the plurality of steps. 27. Drill bit according to embodiment 20, wherein the markings correspond to steps having diameters selected from a group consisting of 3 / 8 inch, 1 / 2 inch, 3 / 4 inch and 7 / 8 inch. 28. Drill bit, which includes: a shaft extending along a drill axis; a transition section that is connected to the shaft; a body section having a front end and a plurality of axially superimposed, progressively larger stages, including a first stage at the front end and a final stage connected to the transition section, wherein each step includes an axial undercut formed on an upper edge of the step, and the body section further comprises a body clamping groove extending from the first step to the transition section; a difference between the hole diameters formed by each pair of adjacent steps of the plurality of steps is less than 0.1 inch. 29. Drill according to embodiment 28, wherein the difference between hole diameters formed by each pair of adjacent steps of the plurality of steps is approximately 0.0625 inch. 30. Drill according to embodiment 28, wherein the axial back taper of each stage measures between approximately 0.007 inch and 0.021 inch. 31. Drill according to embodiment 28, wherein each stage further includes a diametrical back taper. 32. Drill according to embodiment 31, wherein the diametrical undercut of each step measures between approximately -1° and approximately 2°. 33. Drill according to embodiment 28, wherein each stage further includes a radial back taper. 34. Drill according to embodiment 33, wherein the radial back taper of each stage measures between approximately 0.002 inch and approximately 0.008 inch. 35. Drill according to embodiment 28, wherein the body section further includes a step chamfer formed between adjacent steps. 36. Drill according to embodiment 35, wherein each step chamfer has a flank angle which is measured between a surface of the step chamfer and a plane extending perpendicular to the drill axis, and each flank angle is between approximately 40° and approximately 50°. 37. Drill according to embodiment 28, wherein the body further comprises a second body clamping groove extending from the first stage to the transition section. 38. Drill according to embodiment 28, wherein the plurality of stages includes between six stages and seventeen stages.

Claims

[1] A drill (10) comprising: a shaft (12) extending along a drill axis (14); a transition section (16) which is connected to the shaft (12); a body section (18) having a front end (21) and comprising a plurality of axially superimposed, progressively increasing steps (20A-20M) including a first step (20A) at the front end and a last step (20M) connected to the transition section (16), wherein the first stage (20A) has two tip clamping grooves (42) which are each arranged at an angle of the tip clamping groove (44, 50) to the drill axis (14), the body section (18) further having two body clamping grooves (46) which each extend from the first stage (20A) to the transition section (16) and are arranged at an angle of the body clamping groove (48) which differs from the angle of the tip clamping groove (50); and a drill tip (21) located at the front end (21) of the body section (18) and having a cutting edge (28) that crosses the drill axis (14), wherein a first cutting surface (24) is located on one side of the cutting edge (28) and a second cutting surface (26) is located on an opposite side of the cutting edge (28), wherein the first cutting surface (24) has a first clearance angle (36) and the second cutting surface (26) has a second clearance angle (38) which differs from the first clearance angle (36); wherein each tip-chipping groove (42) extends to the first cutting surface (24) or the second cutting surface (26) to define at least part of an edge (32) of the first cutting surface (25) or the second cutting surface (26); wherein the angle of the body clamping groove (48) of each body clamping groove (46) is formed as a compound angle defined by a first angle of the body clamping groove (48) and a second angle of the body clamping groove (72), wherein the first angle of the body clamping groove (48) is measured between a center line (72) of each body clamping groove (46) and the drill axis (14) in a first plane, and the second angle of the body clamping groove (72) is measured between the center line (71) of each body clamping groove (46) and the drill axis (14) in a second plane which is orthogonal to the first plane; wherein the first angle of the body span groove (48) is between about 4.5 degrees and about 5.5 degrees, and wherein the second angle of the body span groove (72) is between about 1 degree and about 3 degrees. [2] Drill (10) according to claim 1, wherein the second clearance angle (38) is approximately twice as large as the first clearance angle (36). [3] Drill (10) according to claim 1, wherein the first clearance angle (36) with respect to a reference axis (37) is between approximately 10° and approximately 20° which is perpendicular to the drill axis (14), and the second clearance angle (38) with respect to the reference axis (37) is between approximately 25° and approximately 35°. [4] Drill (10) according to claim 1, wherein each tip-chipping groove (42), viewed along the drill axis (14), has a U-shaped cross-section. [5] Drill (10) according to claim 4, wherein each tip-chipping groove (42) extends around approximately a quarter circle. [6] Drill (10) I according to claim 1, wherein the angle of the tip-chipping groove (44) of each tip-chipping groove (42) is formed as a compound angle defined by a first angle of the tip-chipping groove (44) and a second angle of the tip-chipping groove (50), wherein the first angle of the tip-chipping groove (44) is measured between a center line of each tip-chipping groove (42) and the drill axis (14) in a first plane and the second angle of the tip-chipping groove (50) is measured between the center line of each tip-chipping groove and the drill axis (14) in a second plane which is orthogonal to the first plane. [7] Drill (10) according to claim 1, wherein the drill tip (21) has a primary tip angle (22) measured over the drill axis (14) from the first cutting surface (24) to the second cutting surface (26), which is between approximately 130° and approximately 140°. [8] A drill (10) comprising: a shaft (12) extending along a drill axis (14); a transition section (16) which is connected to the shaft (12); a body section (18) having a front end (21) and comprising a plurality of axially superimposed, progressively increasing steps (20A-20M) including a first step (20A) at the front end (21) and a last step (20M) connected to the transition section (16), wherein the first stage (20A) has two tip clamping grooves (42) which are each arranged at an angle of the tip clamping groove (44, 50) to the drill axis (14), the body section (18) further having two body clamping grooves (46) which each extend from the first stage (20A) to the transition section (16) and are arranged at an angle of the body clamping groove (48, 72) which differs from the angle of the tip clamping groove (44, 50); and a drill tip (21) located at the front end (21) of the body section (18) and having a cutting edge (28) that crosses the drill axis (14), wherein a first cutting surface (24) is located on one side of the cutting edge (28) and a second cutting surface (26) is located on an opposite side of the cutting edge (28), wherein the first cutting surface (24) has a first clearance angle (36) and the second cutting surface (26) has a second clearance angle (38) which differs from the first clearance angle (36); wherein each tip-chipping groove (42) extends to the first cutting surface (24) or the second cutting surface (26) to define at least part of an edge (32) of the first cutting surface (24) or the second cutting surface (26); wherein the angle of the tip clamping groove (44, 50) of each tip groove (42) is formed as a compound angle formed by a first angle of the tip clamping groove (44) and a second angle of the tip-clamping groove (50) is defined, wherein the first angle of the tip-clamping groove (44) is measured between a center line of each tip-clamping groove (42) and the drill axis (14) in a first plane, and the second angle of the tip-clamping groove (50) is measured between the center line of each tip-clamping groove (44) and the drill axis (14) in a second plane which is orthogonal to the first plane; wherein the first angle of the tip clamping groove (44) is between about 54 degrees and about 64 degrees and wherein the second angle of the tip clamping groove (50) is between about 10 degrees and approximately 20 degrees. [9] Drill (10) according to claim 8, wherein the second clearance angle (38) is approximately twice as large as the first clearance angle (36). [10] Drill (10) according to claim 8, wherein the first clearance angle (36) with respect to a reference axis (37) is between approximately 10° and approximately 20° which is perpendicular to the drill axis (14), and the second clearance angle (38) with respect to the reference axis (37) is between approximately 25° and approximately 35°. [11] Drill (10) according to claim 8, wherein each tip-chipping groove (42), viewed along the drill axis (14), has a U-shaped cross-section. [12] Drill (10) according to claim 11, wherein each tip-chipping groove (42) extends around approximately a quarter circle. [13] Drill (10) according to claim 8, wherein the drill tip (21) has a primary tip angle (22) measured through the drill axis (14) from the first cutting surface (24) to the second cutting surface (26), which is between about 130 degrees and about 140 degrees. [14] A drill (10) comprising: a shaft (12) extending along a drill axis (14); a transition section (16) which is connected to the shaft (12); a body section (18) having a front end (21) and comprising a plurality of axially superimposed, progressively increasing steps (20A-20M) including a first step (20A) at the front end (21) and a last step (20M) connected to the transition section (16), wherein the first stage (20A) has two tip clamping grooves (42) which are each arranged at an angle of the tip clamping groove (44, 50) to the drill axis (14), the body section (18) further having two body clamping grooves (46) which each extend from the first stage (20A) to the transition section (16) and are arranged at an angle of the body clamping groove (48, 72) which differs from the angle of the tip clamping groove (44, 50); and a drill tip (21) located at the front end (21) of the body section (18) and having a cutting edge (28) that crosses the drill axis (14), wherein a first cutting surface (24) is located on one side of the cutting edge (28) and a second cutting surface (26) is located on an opposite side of the cutting edge (28), wherein the first cutting surface (24) has a first clearance angle (36) and the second cutting surface (26) has a second clearance angle (38) which differs from the first clearance angle (36); wherein each tip-chipping groove (42) extends to the first cutting surface (24) or the second cutting surface (26) to define at least part of an edge (32) of the first cutting surface (24) or the second cutting surface (26); wherein the angle of the tip-chipping groove (44, 50) of each tip-chipping groove (42) is formed as a compound angle defined by a first angle of the tip-chipping groove (44) and a second angle of the tip-chipping groove (50), wherein the first angle of the tip-chipping groove (44) is measured between a center line of each tip-chipping groove (42) and the drill axis (14) in a first plane, and the second angle of the tip-chipping groove (50) is measured between the center line of each tip-chipping groove (42) and the drill axis (14) in a second plane which is orthogonal to the first plane; wherein the first angle of the tip clamping groove (44) is between about 54 degrees and about 64 degrees and wherein the second angle of the tip clamping groove (50) is between about 10 degrees and The temperature is approximately 20 degrees. [15] Drill (10) according to claim 14, wherein the second clearance angle (38) is approximately twice as large as the first clearance angle (36). [16] Drill (10) according to claim 14, wherein the first clearance angle (36) with respect to a reference axis (37) is between approximately 10° and approximately 20° which is perpendicular to the drill axis (14), and the second clearance angle (38) with respect to the reference axis (37) is between approximately 25° and approximately 35°. [17] Drill (10) according to claim 14, wherein each tip-chipping groove (42), viewed along the drill axis, has a U-shaped cross-section. [18] Drill (10) according to claim 17, wherein each tip-chipping groove (42) extends around approximately a quarter circle. [19] Drill (10) according to claim 14, wherein the drill tip (21) has a primary tip angle (22) measured through the drill axis (14) from the first cutting surface (24) to the second cutting surface (26), which is between about 130 degrees and about 140 degrees.

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