Metal drill and method
Patent Information
- Application Number
- EP2023732523
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-06-28
- Filing Date
- 2023-06-13
- Publication Date
- 2025-05-07
AI Technical Summary
Existing metal drills often damage sealing rings when creating blind holes in metal workpieces due to the sharp edge formed by the stop shoulder, which can lead to premature wear or failure of the sealing element.
A drill design featuring a shaft with a changing enveloping circle diameter that increases beyond the blind hole diameter at the stop shoulder, incorporating a conical first section that enlarges the hole in the opposite direction, reducing stress on the sealing element and incorporating two cutting edges for symmetrical drilling, along with a centering tip and spiral grooves for chip removal.
The design minimizes the risk of damaging sealing elements by creating a conically enlarged hole that reduces stress on the sealing ring, ensuring its integrity and extending its lifespan during the drilling process.
Smart Images
Figure 1.1
Abstract
Description
[0001] Metal drills and processes
[0002] The present invention relates to a drill for hand-guided drilling of a blind hole in a metal workpiece.
[0003] Drills are known that have a shank defining a drilling direction, a cutting edge, and a stop shoulder, the distance between which defines the blind hole depth. Typically, the stop shoulder has an edge that creates a hole with a sharp edge in a surface layer of a workpiece. A sealing ring, which may later be intended to cover the hole, can be damaged by this edge.
[0004] The invention is based on the object of providing a drill with which the risk of damage to a sealing element is reduced.
[0005] The object is achieved by a drill for hand-guided drilling of a blind hole with a blind hole diameter and a blind hole depth in a metal workpiece, comprising a shank which defines a drilling direction and has a rotation axis oriented in the drilling direction, wherein the shank has a cutting edge at its end pointing in the drilling direction and a stop shoulder at a distance from the cutting edge that defines the blind hole depth and is measured counter to the drilling direction, wherein the cutting edge defines the blind hole diameter by rotation about the rotation axis, wherein the shank has an enveloping circle diameter that changes along the rotation axis and is larger than the blind hole diameter at the stop shoulder, wherein the shank has an enveloping circle diameter that changes along the rotation axis and is larger than the blind hole diameter at the stop shoulder,The shank has a first shank section adjoining the stop shoulder in the opposite direction to the drilling direction, extending as far as the stop shoulder, and in which the enveloping circle diameter, starting from the stop shoulder, increases, preferably continuously, in the opposite direction to the drilling direction. Preferably, the shank has two or more cutting edges at its end facing in the drilling direction, which jointly define the blind hole diameter by rotation about the rotation axis and are particularly preferably arranged symmetrically about the rotation axis.
[0006] An enveloping circle diameter, as defined by the invention, is the diameter of the smallest possible circle that, with its center on the rotation axis, still completely encloses the shaft. In other words, for any point along the rotation axis, the circular area of the enveloping circle is the area covered by the shaft when rotating around the rotation axis. For a circular circumference, the enveloping circle diameter is equal to the diameter of the circumference, i.e., the shaft diameter. Inward deviations of the circumference from the circular shape do not affect the enveloping circle diameter; however, outward deviations increase the enveloping circle diameter.
[0007] In a preferred embodiment, the shaft has a centering point at its end pointing in the drilling direction, through which the axis of rotation runs.
[0008] In a preferred embodiment, the stop shoulder has a stop surface aligned perpendicular to the axis of rotation and pointing in the drilling direction.
[0009] In a preferred embodiment, the shaft has a fastening section at its end facing opposite the drilling direction for temporary attachment to a hand-held drill. Particularly preferably, the fastening section is designed as a shank end.
[0010] In a preferred embodiment, the first section has a conical shape. The opening angle of the conical shape is preferably at least 60°, particularly preferably at least 90° or at least 120°.
[0011] In a preferred embodiment, the first section extends along the axis of rotation over at least 0.5 mm, preferably at least 1.0 mm, particularly preferably at least 1.5 mm or at least 2.0 mm.
[0012] The object is also achieved in a method for fastening a fastening element to a workpiece, in which a workpiece having a covering layer and a drill bit as described above are provided, a blind hole is drilled through the covering layer into the workpiece using the drill bit, wherein the first shaft section of the drill bit creates a hole in the covering layer that enlarges counter to the drilling direction, wherein a fastening element having a sealing element is further provided and driven into the blind hole, wherein the sealing element is pressed against the hole in the covering layer. Preferably, the fastening element is screwed into the blind hole. The invention is explained in more detail below with reference to the drawings. In the drawings:
[0013] Fig. 1 a drill,
[0014] Fig. 2 a workpiece,
[0015] Fig. 3 a drilling machine with a fastening element and
[0016] Fig. 4 a workpiece with a sealing element.
[0017] Figure 1 shows a side view of a drill 10 which is suitable for hand-guided drilling of a blind hole in a metal workpiece (not shown). The drill 10 comprises a shaft 20 which defines a drilling direction 30 and has an axis of rotation oriented in the drilling direction 30. At its end pointing in the drilling direction 30, the shaft 20 has a cutting edge 50 and a further cutting edge (not shown), which are arranged opposite one another and symmetrically with respect to the axis of rotation and, by rotation about the axis of rotation, together define a blind hole diameter of the drilled blind hole. Furthermore, the shaft 20 has a stop shoulder 55 with a stop surface 60 oriented perpendicular to the axis of rotation and pointing in the drilling direction 30.During drilling of the blind hole, the stop shoulder 55 abuts a surface of the workpiece, so that the distance of the stop surface 60 from the cutting edge 50, measured opposite to the drilling direction 30, defines a blind hole depth of the drilled blind hole. At its end facing opposite to the drilling direction 30, the shank 20 has a shank end (not shown) for temporary attachment to a hand-held drill.
[0018] The shaft 20 has an enveloping circle diameter that varies along the rotation axis. At the stop shoulder 55, the enveloping circle diameter is larger than the blind hole diameter. Furthermore, the shaft 20 has a centering point 70 at its end facing in the drilling direction 30, through which the rotation axis passes. The entire shaft 20, including the cutting edge 50 and the centering point 70, is formed from a single piece, so that the stop shoulder 55 and the cutting edge 50 are made of the same material, preferably a metal or an alloy, particularly preferably steel.
[0019] For the removal of metal chips generated by the cutting edge 50 and the further cutting edge during drilling, the shaft 20 has two spiral grooves 90 which extend through the stop shoulder 55 and are delimited by the cutting edge 50 and the further cutting edge, respectively.
[0020] The shaft 20 has a first shaft section 40 adjoining the stop shoulder 55 in the opposite direction to the drilling direction 30, which extends as far as the stop shoulder 55, and in which the enveloping circle diameter, starting from the stop shoulder 55, steadily increases in the opposite direction to the drilling direction 30. The first shaft section has a conical shape with an opening angle of 140° and extends along the rotational axis over 2.5 mm.
[0021] Fig. 2 shows a workpiece 100 with a cover layer 110. The workpiece has a blind hole 120, which was created, for example, using the drill 10 from Fig. 1. The first shaft section of the drill has created a hole 130 in the cover layer that enlarges counter to the drilling direction.
[0022] Fig. 3 shows a drilling machine 150 with a bit holder 160 and a fastening element 170, which has a sealing element 180 designed as a sealing ring and is driven, for example, into the blind hole 120 from Fig. 2.
[0023] Fig. 4 shows the workpiece 100 with the cover layer 110 after a fastener, of which only a sealing element 190 is shown, has been driven into the blind hole 120. The sealing element 190 is pressed against the hole 130 in the cover layer, which expands counter to the drilling direction. Due to the conical shape of the hole 130, the sealing element 190 is protected from excessive stress.
[0024] The invention has been described using the example of a metal drill. However, it should be noted that the drill according to the invention is also suitable for other purposes.
Claims
PATENT CLAIMS Drill for hand-guided drilling of a blind hole with a blind hole diameter and a blind hole depth in a metal workpiece, comprising a shaft which defines a drilling direction and has a rotation axis oriented in the drilling direction, wherein the shaft has a cutting edge at its end pointing in the drilling direction and a stop shoulder at a distance from the cutting edge which defines the blind hole depth and is measured counter to the drilling direction, wherein the cutting edge defines the blind hole diameter by rotation about the rotation axis, wherein the shaft has an enveloping circle diameter which changes along the rotation axis and is larger at the stop shoulder than the blind hole diameter, wherein the shaft has a first shaft section which adjoins the stop shoulder counter to the drilling direction, which first shaft section reaches up to the stop shoulder and in which the enveloping circle diameter,starting from the stop shoulder, increases counter to the drilling direction. Drill according to claim 1, wherein the enveloping circle diameter in the first shaft section increases continuously counter to the drilling direction. Drill according to one of the preceding claims, wherein the first section has a conical shape. Drill according to claim 3, wherein an opening angle of the conical shape is at least 60°, in particular at least 90°, in particular at least 120°. Drill according to one of the preceding claims, wherein the first section extends along the axis of rotation over at least 0.5 mm, in particular at least 1.0 mm, in particular at least 1.5 mm, in particular at least 2.0 mm. Drill according to one of the preceding claims, wherein the shaft has a centering tip at its end pointing in the drilling direction, through which the axis of rotation runs. Drill according to one of the preceding claims,wherein the stop shoulder has a stop surface aligned perpendicular to the axis of rotation and pointing in the drilling direction.
8. A drill according to any one of the preceding claims, wherein the shaft has a fastening portion, in particular a shank, at its end facing the drilling direction for temporary attachment to a hand-held drill.
9. A method for attaching a fastening element to a workpiece, comprising the following steps: - Providing a workpiece having a covering layer; - Providing a drill according to one of the preceding claims; Drilling a blind hole through the cover layer into the workpiece by means of the drill, wherein the first shank section of the drill creates a hole in the cover layer that enlarges in the opposite direction to the drilling direction; - Providing a fastening element having a sealing element; Driving the fastening element into the blind hole, wherein the sealing element is pressed against the hole in the cover layer.
10. The method according to claim 9, wherein the driving of the fastening element into the Blind hole involves screwing the fastener into the blind hole.