DRILL

Abstract

Drill for drilling in hard materials, including a drill head having a rotational axis, wherein the drill head includes an apex aligned with the rotational axis and centre point cutting edges radially extending and receding from the apex. A first one of the centre point cutting edges and a second one of the centre point cutting edges have a different radius and/or are receding at least for a part at a different rate. A drill for drilling in hard materials, including a drill head having a rotational axis. The drill head includes a centre point aligned with the rotational axis and main cutting edges radially extending from the centre point, wherein each of the main cutting edges deviates from a radial.

Claims

1-33. (canceled)

34. A drill (100) for drilling in hard materials, comprising a drill head (150) having a rotational axis (R), wherein the drill head comprises a centre point (180) comprising: an apex (182) aligned with the rotational axis; centre point cutting edges (181, 181′) radially extending and receding from the apex, main cutting edges (160, 160′) radially extending from the centre point (180), wherein a first one of the centre point cutting edges and a second one of the centre point cutting edges have a different radius (r1, r2) and/or are receding at least for a part at a different rate; wherein the centre point comprises an asymmetric cutting edge (183) arranged between a proximal end (172′) of one of the main cutting edges (160, 160′) and a distal end of one of the centre point cutting edges (181′); and wherein a proximal end (172) of another one of the main cutting edges (160, 160′) ends at a distal end of another one of the centre point cutting edges (181).

35. The drill according to claim 34, wherein the centre point cutting edges are angularly evenly distributed around the apex.

36. The drill according to claim 34, wherein the centre point cutting edges deviate and/or curve away from a radial.

37. The drill according to claim 36, wherein the centre point cutting edges are convex centre point cutting edges.

38. The drill according to claim 34, wherein the centre point cutting edges recede from the apex at the same rate.

39. The drill according to claim 34, wherein the part of the first one of the centre point cutting edges and the part of the second one of the centre point cutting edges having a different rate of receding are arranged distal from the apex.

40. The drill according to claim 34, wherein the drill head comprises main cutting edges (160, 160′) radially extending from the centre point.

41. The drill according to claim 40, wherein a proximal end (172, 172′) of each of the main cutting edges ends at a distal end of the centre point cutting edges.

42. The drill according to claim 41, wherein the asymmetric cutting edge is extending in a direction different from the direction of the distal end of the one of the centre point cutting edges.

43. The drill according to claim 34, wherein the drill is a high-speed steel (HSS) drill.

44. The drill according to claim 34, wherein the number of centre point cutting edges is two, three or four.

45. The drill according to claim 34, wherein the number of centre point cutting edges is two and the two centre point cutting edges form an S-shape with the apex as rotational symmetric point.

46. The drill according to claim 34, wherein the drill is combined with any of the features of the embodiments specified in EMBODIMENTS.

47. The drill (100) according to claim 34, wherein each of the main cutting edges (160, 160′) deviates from a radial (Rad).

48. The drill (100) according to claim 47, wherein the deviation of one of the main cutting edges (160, 160′) is defined as that there exists a tangent line tangent to a point of the main cutting edge (160, 160′), wherein the tangent line has a non-zero angle with the radial through that point.

49. The drill (100) according to claim 34, wherein each of the main cutting edges (160, 160′) comprise at least one section that deviates and/or curves away from the radial.

50. The drill (100) according to claim 34, wherein each of the main cutting edges (160, 160′) comprises a convex edge section (165, 165′).

51. The drill (100) according to claim 50, wherein the drill head has a drill head (150) circumference (C) and wherein a distal end (166, 166′) of each of the convex edge sections ends at the drill head circumference.

52. The drill (100) according to claim 34, wherein the drill (100) has a drill circumference (C), and comprises at least two guiding lands (190, 190′, 191, 191′) arranged to the drill circumference and spiraling away from the drill head.

53. The drill (100) according to claim 52, wherein the at least two guiding lands start at the drill head circumference.

54. The drill (100) according to claim 53, wherein an end of the respective at least two guiding lands (190, 190′) is adjacent to a respective distal end (166, 166′) of one of the convex edge sections.

55. The drill (100) according to claim 34, wherein each of the main cutting edges (160, 160′) comprises a concave edge section (165, 165′).

56. The drill (100) according to claim 55, wherein the concave edge section is arranged proximal relative to the convex edge section (165, 165′).

57. The drill (100) according to claim 34, wherein the concave edge section (165) and the convex edge section (165′) are adjoining.

58. The drill (100) according to claim 55, wherein a proximal end (172, 172′) of each of the concave edge sections (165, 165′) ends at the centre point (180).

59. The drill (100) according to claim 34, wherein the centre point (180) protrudes from the drill head for centring the drill head (150) in use.

60. The drill (100) according to claim 34, wherein the hard material is a metal.

61. The drill (100) according to claim 60, wherein the metal is a hard metal, such as steel.

62. The drill (100) according to claim 61, wherein the drill is a highspeed steel (HSS) drill.

63. The drill (100) according to claim 34, wherein the number of main cutting edges (160, 160′) is two, three or four.

64. The drill (100) according to claim 34, wherein the main cutting edges (160, 160′) define a cutting plane substantially perpendicular to the rotational axis (R).

65. The drill (100) according to claim 34, wherein the main cutting edges (160, 160′) are angularly evenly distributed around the centre point (180).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The invention will be apparent from and elucidated further with reference to the embodiments described by way of example in the following description and with reference to the accompanying drawings, in which:

[0055] FIG. 1 schematically shows a top view of a drill head;

[0056] FIG. 2 schematically shows a side view of a drill head;

[0057] FIG. 3 schematically shows a perspective side view of a drill; and

[0058] FIG. 4 schematically shows a top view of a second drill head.

[0059] The figures are purely diagrammatic and not drawn to scale. In the figures, elements which correspond to elements already described may have the same reference numerals.

LIST OF REFERENCE NUMERALS

[0060]

TABLE-US-00001 100 drill 110 shank 150 drill head 160, 160′ main cutting edge 165, 165′ convex edge section 166, 166′ distal end convex edge section 167, 167′ proximal end convex edge section 170, 170′ concave edge section 171, 171′ distal end concave edge section 172, 172′ proximal end concave edge section 180 centre point 181, 181′ centre point cutting edge 182 apex 183 asymmetric cutting edge 184 ridge 190, 190′ guiding land 191, 191′ guiding land 192, 192′ flute r1 first radius centre point cutting edge r2 second radius centre point cutting edge C drill head circumference D direction of rotation R rotational axis Rad radial

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0061] FIG. 1 schematically shows a top view of a drill head 150 of a drill 100. The drill rotates around a rotational axis R. The drill rotates around this rotational axis in the direction D. The viewpoint of this figure is on the rotational axis, which causes the rotational axis, being a line, to be depicted as a dot in the centre of the drill. To introduce stability to the drill head and also the drill as a whole, the centre of rotation or rotational axis is aligned or at least substantially aligned with the centre line or elongated axis of the drill. The rotational axis further more may define a radial Rad. The radial Rad may be a line starting at the rotational axis and extending perpendicular from the rotational axis. The radial may be defined as radially extending from the rotational axis. Typically, the radial is the shortest way of reaching the circumference of the drill head starting from the rotational axis. The rotational axis further more may define a radial plane. The radial plane may be defined as a plane perpendicular to the rotational axis.

[0062] The drill head comprises main cutting edges 160, 160′. The main cutting edges have as a function to cut away the main part of the material from the object wherein a hole is to be drilled. The drill head has a circumference C, which is typically or substantially circular. The main cutting edges typically extend to the circumference of the drill head. The main cutting edges are typically substantially arranged in a radial plane thereby defining the cutting plane or main cutting plane which is a radial plane intersecting the rotational axis at a particular point. This particular point may be found by virtually extending the main cutting edges toward the rotational axis.

[0063] The drill head comprises a centre point 180. The centre point is typically protruding from the drill head. Thus, the centre point is protruding towards the viewpoint of FIG. 1. The centre point functionally cuts a centre hole into the object or material wherein a hole is to be drilled. The centre point has as function that it should counter any forces having an orientation substantially in a radial plane. These forces are typically introduced by the main cutting edges when cutting, slicing and/or removing away the larger part of the material from the drill hole. These forces may be introduced by imperfections, granules, veins in the material to be removed. These forces are countered by the centre point pushing sideways onto the centre hole and thereby holding the drill head and thus the drill stable in a radial plane. The technical effect of this is that the centre point provides for a smooth entry of the main cutting edges into the material to be cut away by the main cutting edges. Further, the technical effect of this is that the centre point promotes a straighter drill hole having less deviations or sideway imperfections and may prevent a tortuous drill hole. It may be deduced from the previous that the centre point is typically protruding from the drill head to fulfil its function.

[0064] The centre point may comprise an apex 182. The apex is the most protruding part or point of the centre point. The apex typically protrudes towards the viewpoint in FIG. 1. The apex is typically substantially aligned with the rotational axis. The apex is typically also substantially aligned with the centre line of the drill. This alignment of the apex typically enhances the stability of the drill head and thus the drill as a whole. Stability of the drill head may be defined as the amount of movement of and/or forces acting upon the drill relative to the object or material wherein a hole is to be drilled and/or while drilling.

[0065] The main cutting edges are typically arranged radially outward from the centre point. The main cutting edges may be arranged adjoining to the centre point. The drill head may comprise several main cutting edges, such as three, four or two as shown in FIG. 1. The main cutting edges are typically radially distributed evenly for minimizing radial forces generated by the cutting main cutting edges.

[0066] Each of the main cutting edges 160, 160′ may comprise a convex edge section 165, 165′. The convex edge section deviates and/or curves away from the radial in a radial plane with increasing radius. The convex edge section curve deviates and/or curves away in a direction opposite to the direction of rotation D or away from the material to be cut.

[0067] The drill head while rotating provides a tangential velocity to the main cutting edge. The tangential velocity increases linearly with increasing radius. Thus, the outside or radially most extending part of the main cutting edge will experience the highest tangential velocity. Also, the outside or radially most extending part of the main cutting edge will cut away the most material as it travellers the longest distance when going around. These two reasons may cause increased wear of the outside or radially more extending parts of the main cutting edges compared to parts of the main cutting edges arranged inside or radially less extending parts of the main cutting edges. Parts of the main cutting edges experiencing more wear will become quicker blunt compared to parts experiencing less wear. A blunt cutting edge will cause increased friction when drilling. Furthermore, the increased friction will further increase wear of that part of the blunt cutting edge further worsening the friction of that part of the main cutting edges.

[0068] The main cutting edges 160, 160′ may comprise convex edge sections 165, 165′. The edge section having a convex shape arranges the edge section under a non-perpendicular angle with the tangential velocity. This advantageously allows the convex edge section to slice through the material to be removed instead of bluntly and frontally cutting into the material to be removed. The slicing motion of the convex edge section reduces the amount of wear on the convex edge section. A further effect of the convex edge section is that the edge section may be longer compared to extending along the radial while ending at the same radial distance from the rotational axis. The longer edge section means that more edge length is available to cut away material near the circumference of the drill head. Thus, the wear of the main cutting edge near the circumference of the drill head is spread out more, hence reducing the wear of the convex edge section. This effect may also be reached in an embodiment having a concave edge section arranged near the circumference of the drill head. Thus, the lifetime of the drill head may be extended by main cutting edges symmetrically radially extending from the centre point wherein each of the main cutting edges deviates and/or curves away from the radial.

[0069] The part of the main cutting edge close to the circumference of the drill head is preferably convex shaped. The material may comprise imperfections or other irregularities such as granules. The convex shape allows for forces experienced from these imperfections typically to advantageously translate into centripetal forces. Furthermore, the convex shape advantageously causes an outward or centrifugal force on the material just cut away. The centripetal and centrifugal forces or any other forces having a direction in a radial plane, such as the cutting plane, may be countered by the centre point snugly fitting in the centre hole. The centre point thus advantageously stabilizes or counters the instability caused by the main cutting edges curving away.

[0070] The drill may comprise guiding lands 190, 190′, 191, 191′. A drill may be seen as a cylinder. The drill head is arranged to one end of the cylinder. The shank is arranged to the other end of the cylinder. The drill head is the part of the drill contacting the object or material first wherein a hole is drilled. The shank typically has a fitting for fitting into a drilling machine. Guiding lands are arranged along the surface of the cylinder and spiral from the drill head to the shank. Flutes are arranged between the guiding lands for transporting cut material away from the drill head towards the shank and thus out of the drill hole. The upper edge of the wall on each side of the flutes may be formed by edges from the guiding lands. Guiding lands may stabilize the drill when the drill is far enough inside the drill hole for the guiding lands to be able to push onto the sides of the drill hole.

[0071] The convex edge sections 165, 165′ may comprise distal ends 166, 166′. The convex edge section of a main cutting edge typically ends at the circumference of the drill. Preferably, the convex edge section ends at a guiding land. More preferably, the convex edge section ends at an edge of the guiding land 190, 190′. As the edge of the guiding land is typically also the upper wall of the flute, the material just cut away is advantageously directly inserted in the channel created by the flute and the side of the drilled hole for transport away from the drill head.

[0072] This improves transportation of material just cut away. The material cut away is thus less likely to come an additional time into contact with the main cutting edge reducing the wear of the main cutting edge. Furthermore, the pressure of the material just cut away is lessened further reducing the change of material cut away to come an additional time into contact with the main cutting edge. Thus, this has the technical effect of reducing wear, hence, improving lifetime of the main cutting edge, drill head and drill.

[0073] The main cutting edges may comprise concave edge sections 170, 170′. Typically, if also a convex edge section is present, the concave edge section is arranged radially closer to the axis of rotation and/or apex compare to the convex edge section. In other words, the concave edge section is arranged proximal relative to the convex edge section.

[0074] The convex edge section may have a proximal end 167, 167′ which is proximal relative to the rotational axis R. The concave edge section may have a distal end 171, 171′ which is distal relative to the rotational axis R. The proximal end of the convex edge section may be adjacent or adjoining to the distal end of the concave edge section for forming a continuous main cutting edge.

[0075] The centre point 180 may comprise centre point cutting edges 181, 181′. The centre point cutting edges typically extend from the apex 182. The centre point cutting edges typically start out to extend relatively inside a radial plane, which may be typed as a centre point cutting plane, from the apex. Thereafter the centre point cutting edges at a particular radius recede to form a sharp ridge 184 with the apex in the middle of the ridge, as shown in FIG. 2. This typically sharp receding at the ends of the ridge cause a centre hole while drilling, which centre hole has a relatively steep sidewall. This steep side wall allows the centre point arranged in the centre hole to counter any forces in a radial plane caused by the drilling and causing instability of the drill head by the centre point being pushed against the sidewall of the centre hole. Due to the steep side wall of the centre hole, these forces may even make a slight angle with the radial plane.

[0076] The apex is typically aligned with the rotational axis of the drill. From the apex the first centre point cutting edge 181 being part of the ridge 184 extends a first radius r1. Also, from the apex the second centre point cutting edge 181′ being part of the ridge 184 extends a second radius r2. The first and the second radius are different in FIG. 1. This difference in radius from the apex and/or the rotational axis causes a slight instability during drilling, which instability reduces the friction encountered by the centre point.

[0077] The concave edge section may comprise a proximal end 172, 172′. The proximal end of the concave edge section typically ends at the centre point 180. The centre point may comprise centre point cutting edges 181, 181′. The centre point cutting edges may be adjacent or adjoining to the proximal end of the concave edge section for forming a continuous cutting edge with the main cutting edge. Thus, a centre point cutting edge and a main cutting advantageously form a continuous cutting edge for allowing material to be cut away starting from the apex up to the circumference of the drill.

[0078] Due to the different radius of the centre point cutting edges in the embodiment of FIG. 1, one of the centre point cutting edges may be extended by an asymmetric cutting edge 183, as shown in FIGS. 2 and 4. The asymmetric cutting edge links the centre point cutting edge to the proximal end of a main cutting edge for advantageously forming a continuous cutting edge.

[0079] FIG. 2 schematically shows a side view of a drill head 150. The drill head comprises main cutting edges 160, 160′ and a centre point 180. The main cutting edges extend from the centre point and slightly recede with an increasing radius. The receding may be under an angle in the range of up to pi/4 radian, preferably less than pi/5 radian, more preferably less than pi/6 radian. The receding main cutting edge may still be considered to be substantially arranged in a radial plane, such as a main cutting plane.

[0080] The drill head may comprise guiding lands 190, 191, 191′ for providing a means for the drill to push against the side wall of the drill hole for creating stability. Furthermore, between the guiding lands the flutes 192, 192′ are formed for transporting removed material from the drill head towards the shank of the drill.

[0081] The slight receding of the main cutting edges has the technical effect of improving the transport of just cut material towards the circumference for enhancing the transportation of just cut material away from the centre point and/or centre of the drill head and towards the outside of the drill head and/or the flutes. The enhanced transportation reduces the friction of the drill head while drilling.

[0082] The centre point 180 may comprise centre point cutting edges 181, 181′. The middle of the centre point is formed by the apex 182. The centre point cutting edges extend from the apex and/or rotational axis for a specific radius relatively level and thereafter start to recede sharply thereby forming a ridge 184. As the ridge may extend radially different in different directions, and the preference to form a continuous edge with the main cutting edges, the centre point cutting edge 181′ providing the part of the ridge extending radially less may be extended by an asymmetric cutting edge 183 for filling the gap towards the end of the main cutting edge for advantageously forming the continuous cutting edge.

[0083] FIG. 3 schematically shows a perspective side view of a drill 100. The drill comprises a drill head 150 and may comprise a shank 110. The drill head and the shank are arranged on opposite ends of the drill. The shank may be shaped to be gripped by gripping means of a drilling machine. The shank is typically shaped such that the drill may be easily replaced in the drilling machine. The drill typically rotates around a rotational axis R. The drill may rotate around the rotational axis in a rotational direction D.

[0084] FIG. 4 schematically shows a top view of a second drill head 150. FIG. 4 shows the same features as in FIG. 1. This figure further shows a larger difference in the ending of the centre point cutting edge, hence the asymmetric cutting edge 183 is more clearly present in FIG. 4.

[0085] According to the invention, the diameter of the drill may be in the range of 2 mm to 100 mm, preferably 4 mm to 80 mm, more preferably 6 mm to 60 mm, even more preferably 8 mm to 40 mm, most preferably, 10 mm to 20 mm.

[0086] According to the invention, the diameter of the centre point may be a fraction of the diameter of the drill, the fraction may be in the range of 0.5 to 0.01, preferably 0.4 to 0.04, more preferably 0.3 to 0.06, even more preferably 0.2 to 0.08, most preferably around 0.1.

[0087] According to the invention, the centre point cutting edges may be asymmetric. The asymmetry may be by a different rate of receding especially at some radial distance from the apex and/or rotational axis. The difference in rate of receding may be expressed as a ridge extending from the apex and/or rotational axis with different radius. The asymmetry in the ridge may be expressed as a different radius from the apex and/or rotational axis for the ridge. The difference in radius may be in the range of 2 mm to 0.005 mm, preferably 1 mm to 0.01 mm, more preferably 1 mm to 0.05 mm. The asymmetry may also be by extending to a different radius from the apex and/or rotational axis. The difference in radius may be in the range of 2 mm to 0.005 mm, preferably 1 mm to 0.01 mm, more preferably 1 mm to 0.05 mm. The gap in the asymmetry may be filled up or bridged by an asymmetric cutting edge.

[0088] According to the invention, the asymmetry from the centre point causes a movement or an oscillation or movement during drilling. The amplitude of the oscillation, motion or movement is typically a fraction of the diameter of the centre point. The fraction may be in the range of 0.5 to 0.01, preferably 0.4 to 0.02, more preferably 0.3 to 0.03, even more preferably 0.2 to 0.04, most preferably around 0.05.

[0089] Examples of hard materials are metals, preferably certain metals, such as iron and copper, and alloys containing metals, such as steel, bronze and brass.

[0090] According to the invention, the centre point protrudes from the drill head. The length of the protrusion of the centre point, more specifically the apex, may be expressed as a ratio relative to the diameter of the centre point. The ratio may be in the range of 0.7 to 0.05, preferably 0.6 to 0.1, more preferably 0.5 to 0.15, even more preferably 0.4 to 0.2, most preferably around 0.3.

[0091] In the foregoing specification, the invention has been described with reference to specific examples of embodiments of the invention. It will, however, be evident that various modifications and changes may be made therein without departing from the scope of the invention as set forth in the appended claims. For example, the shapes may be any type of shape suitable to achieve the desired effect. Devices functionally forming separate devices may be integrated in a single physical device.

[0092] However, other modifications, variations and alternatives are also possible. The specifications and drawings are, accordingly, to be regarded in an illustrative rather than in a restrictive sense.

[0093] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word ‘comprising’ or ‘including’ does not exclude the presence of other elements or steps than those listed in a claim. Furthermore, the terms “a” or “an,” as used herein, are defined as one or as more than one. Also, the use of introductory phrases such as “at least one” and “one or more” in the claims should not be construed to imply that the introduction of another claim element by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim element to inventions containing only one such element, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an.” The same holds true for the use of definite articles. Unless stated otherwise, terms such as “first” and “second” are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.