Metal drill bit and method using the same

Abstract

The present invention relates to a drill 10 for drilling a blind hole having a blind hole diameter and a blind hole depth, which is guided by hand to a workpiece made of metal, and includes a shaft 20 defining a drilling direction 30 and having a rotation axis oriented in the drilling direction. The shaft has a cutting edge 50 at its end facing the drilling direction and an abutting shoulder 55 at a certain distance from the cutting edge, which is measured in the direction opposite to the drilling direction and defines the blind hole depth. The cutting edge defines the blind hole diameter by rotation about the rotation axis. The shaft has an envelope circle diameter that varies along the rotation axis and is larger than the blind hole diameter at the abutting shoulder. The shaft has a first shaft portion 40 adjacent to the abutting shoulder in the direction opposite to the drilling direction. The first shaft portion extends up to the abutting shoulder, and its envelope circle diameter increases starting from the abutting shoulder in the direction opposite to the drilling direction.

Description

【Technical Field】 【0001】 The present invention relates to a drill bit for drilling a blind hole with a manual guide into a metal workpiece. 【Background Art】 【0002】 There are known drill bits having a shank with a cutting edge and a stop shoulder that define a drilling direction, and the distance between the cutting edge and the stop shoulder defines the depth of the blind hole. The stop shoulder usually has an edge and creates a hole with a sharp boundary in the covering layer of the workpiece to be targeted. A sealing ring that later covers the hole can be damaged by its edge. 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0003】 An object of the present invention is to provide a drill bit that reduces the risk of damage to a seal element. 【Means for Solving the Problems】 【0004】 This objective is achieved by a drill bit for manually drilling a blind hole having a blind hole diameter and a blind hole depth in a metal workpiece, the drill bit comprising a shank having a rotation axis that defines the drilling direction and is oriented in the drilling direction, the shank having a cutting edge at its end facing the drilling direction and a stopper at a distance from the cutting edge that defines the blind hole depth and is measured in the opposite direction to the drilling direction, the cutting edge defining the blind hole diameter by rotation about the rotation axis, the shank varying along the rotation axis and having an envelope diameter at the stopper that is larger than the blind hole diameter, the shank varying along the rotation axis and having an envelope diameter at the stopper that is larger than the blind hole diameter, the shank having a first shank section adjacent to and reaching the stopper that is opposite to the drilling direction, the envelope diameter starting from the stopper and preferably increasing continuously in the opposite direction to the drilling direction. The shank preferably has two or more cutting edges at its end facing the drilling direction, which together define the diameter of the blind hole by rotation around a rotation axis, and is particularly preferably arranged symmetrically around the rotation axis. 【0005】 In this invention, the envelope diameter is the diameter of the smallest possible circle whose center lies on the axis of rotation and which still completely encloses the shank. In other words, with respect to any point along the axis of rotation, the envelope region is the region covered by the shank when rotated around the axis of rotation. For a circular circumference, the envelope diameter is equal to the diameter of the circumference, i.e., the shank diameter. Deviation inward from the circular shape of the circumference does not affect the envelope diameter, while deviation outward increases the envelope diameter. 【0006】 In a preferred embodiment, the shank has a centering point at its end facing the drilling direction, through which the axis of rotation extends. 【0007】 In a preferred embodiment, the stopper shoulder has a stopping surface oriented perpendicular to the axis of rotation and point in the drilling direction. 【0008】 In a preferred embodiment, the shank has a fixing section at its end facing away from the drilling direction for temporary attachment to a handheld drilling machine. The fixing section is particularly preferably configured as an insertion end. 【0009】 In a preferred embodiment, the first section has a conical shape. The opening angle of the conical shape is preferably at least 60°, and particularly preferably at least 90° or at least 120°. 【0010】 In a preferred embodiment, the first section extends along the axis of rotation for at least 0.5 mm, preferably at least 1.0 mm, and particularly preferably at least 1.5 mm or at least 2.0 mm. 【0011】 This objective can also be achieved by a method of fastening a fastening element to a workpiece, wherein a workpiece having a cover layer and a drill bit are provided as described above, a blind hole is drilled in the workpiece through the cover layer by the drill bit, the first shank section of the drill bit creating a hole in the cover layer whose size increases in the opposite direction to the drilling direction, and further, a fastening element having a sealing element is provided and is pressed into the blind hole, the sealing element pressing against the hole in the cover layer. The fastening element is preferably screwed into the blind hole. 【0012】 The present invention will be described in more detail below with reference to the drawings. [Brief explanation of the drawing] 【0013】 [Figure 1] This is a diagram showing a drill bit. [Figure 2] This is a diagram showing the workpiece. [Figure 3] This is a diagram showing a drilling machine with fastening elements. [Figure 4] This figure shows a workpiece having a sealing element. [Modes for carrying out the invention] 【0014】 Figure 1 shows a side view of a drill bit 10 suitable for manually drilling a blind hole in a metal workpiece (not shown). The drill bit 10 includes a shank 20 that defines a drilling direction 30 and has a rotation axis oriented toward the drilling direction 30. The shank 20 has a cutting edge 50 and a further cutting edge (not shown) at its end facing the drilling direction 30, which are arranged opposite each other and symmetrically with respect to the rotation axis, and together define the diameter of the blind hole drilled by rotation around the rotation axis. Furthermore, the shank 20 has a stopper shoulder 55 that is oriented perpendicular to the rotation axis and faces the drilling direction 30, and has a stop surface 60. During drilling of the blind hole, the stopper shoulder 55 strikes the surface of the workpiece, and therefore the distance between the stop surface 60 and the cutting edge 50, measured opposite to the drilling direction 30, defines the depth of the blind hole drilled. The shank 20 has an insertion end (not shown) at its end facing away from the drilling direction 30 for temporary fixation to a handheld drilling machine. 【0015】 The shank 20 has an envelope diameter that varies along the axis of rotation. At the stop shoulder 55, the envelope diameter is larger than the diameter of the blind hole. Furthermore, the shank 20 has a centering point 70 at its end facing the drilling direction 30, through which the axis of rotation extends. The entire shank 20, including the cutting edge 50 and the centering point 70, is integrally formed, and therefore the stop shoulder 55 and the cutting edge 50 are made of the same material, preferably metal or alloy, and particularly preferably steel. 【0016】 To remove metal chips generated during drilling by the cutting edge 50 and further cutting edges, the shank 20 has two helical grooves 90 that extend through the retaining shoulder 55 and are bounded by the cutting edge 50 and further cutting edges. 【0017】 The shank 20 has a first shank section 40 adjacent to the stopper shoulder 55 opposite to the drilling direction 30 and extending to the stopper shoulder 55, in which the envelope diameter increases continuously opposite to the drilling direction 30, starting from the stopper shoulder 55. The first shank section has a conical shape with an opening angle of 140° and extends for 2.5 mm along the axis of rotation. 【0018】 Figure 2 shows a workpiece 100 having a cover layer 110. The workpiece has blind holes 120, which are created, for example, by a drill bit 10 in Figure 1. The first shank section of the drill bit creates a hole 130 in the cover layer, the size of which increases in the opposite direction to the drilling direction. 【0019】 Figure 3 shows a drilling machine 150 having a bit holder 160 and a fastening element 170, the fastening element 170 having a sealing element 180 configured as a sealing ring, which is pressed into, for example, the blind hole 120 in Figure 2. 【0020】 Figure 4 shows the workpiece 100 having a cover layer 110 after the fastening element, with only the sealing element 190 shown, has been pressed into the blind hole 120. The sealing element 190 is pressed against a hole 130 in the cover layer, which increases in size in the opposite direction to the drilling direction. Due to the conical shape of the hole 130, the sealing element 190 is protected from excessive load. 【0021】 The present invention has been described using the example of a metal drill bit. However, the drill bit according to the present invention is also suitable for other purposes.

Claims

[Claim 1] A drill bit for drilling a blind hole having a blind hole diameter and a blind hole depth, which is guided by hand into a metal workpiece, comprising a shank having a rotation axis that defines the drilling direction and is directed in the drilling direction, the shank having a cutting edge at its end facing the drilling direction, and having a stop shoulder at a distance from the cutting edge that defines the blind hole depth and is measured in the opposite direction to the drilling direction, the cutting edge defining the blind hole diameter by rotation about the rotation axis, and A drill bit comprising a shank that changes along the axis of rotation and has an envelope diameter larger than the diameter of the blind hole at the stop shoulder, the shank having a first shank section adjacent to the stop shoulder opposite to the drilling direction and extending to the stop shoulder, in which case the envelope diameter increases opposite to the drilling direction, starting from the stop shoulder, and the first shank section extending along the axis of rotation for at least 0.5 mm. [Claim 2] The drill bit according to claim 1, wherein the first shank section extends along the axis of rotation for at least 1.0 mm instead of 0.5 mm. [Claim 3] The drill bit according to claim 1, wherein the first shank section extends along the axis of rotation for at least 1.5 mm instead of the 0.5 mm. [Claim 4] The drill bit according to claim 1, wherein the first shank section extends along the axis of rotation for at least 2.0 mm instead of 0.5 mm. [Claim 5] The drill bit according to any one of claims 1 to 4, wherein the diameter of the envelope of the first shank section increases continuously in the opposite direction to the drilling direction. [Claim 6] The first section is a drill bit according to any one of claims 1 to 4, having a conical shape. [Claim 7] The drill bit according to claim 6, wherein the opening angle of the conical shape is at least 60°. [Claim 8] The drill bit according to claim 6, wherein the opening angle of the conical shape is at least 90° instead of 60°. [Claim 9] The drill bit according to claim 6, wherein the opening angle of the conical shape is at least 120° instead of 60°. [Claim 10] The drill bit according to any one of claims 1 to 4, wherein the shank has a centering point at its end facing the drilling direction, through which the axis of rotation extends. [Claim 11] The drill bit according to any one of claims 1 to 4, wherein the stopper shoulder portion has a stopping surface oriented perpendicular to the rotation axis and point in the drilling direction. [Claim 12] The drill bit according to any one of claims 1 to 4, wherein the shank has a fixing section, particularly an insertion end, for temporarily securing to a handheld drilling machine at its end facing away from the drilling direction. [Claim 13] A method for fastening fastening elements to a workpiece, - A process for providing a workpiece having a cover layer, - A step of providing a drill bit according to any one of claims 1 to 4, - A step of drilling a blind hole in the workpiece through the cover layer with the drill bit, wherein the first shank section of the drill bit generates a hole in the cover layer whose size increases in the opposite direction to the drilling direction. - A process for providing a fastening element having a sealing element, and - A step of pressing the fastening element into the blind hole, wherein the sealing element is pressed against the hole in the cover layer. A method that includes this. [Claim 14] The method according to claim 13, wherein pushing the fastening element into the blind hole includes screwing the fastening element into the blind hole.

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