It might be
The drill bit's innovative clearance angle design, transitioning from a linear to a curved progression, effectively reduces friction and thermal loads, improving drilling efficiency by minimizing resistance and maintaining low thermal stress.
Patent Information
- Application Number
- FR2025000202
- Authority / Receiving Office
- FR · FR
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-01-12
- Filing Date
- 2025-01-09
- Publication Date
- 2025-07-18
AI Technical Summary
Conventional drill bits experience high friction and thermal loads during drilling, particularly in the region of the flank surfaces adjacent to the main cutting surfaces, which affects chip evacuation and overall drilling efficiency.
The drill bit design features a varying clearance angle along its surface, transitioning from a near-center section with a linear progression to an outer section with a curved progression, increasing the clearance angle to reduce friction and thermal loads. This design includes a curved outer section with a higher clearance angle to minimize friction in regions of higher peripheral speed.
The varying clearance angle design reduces friction and thermal loads, enhancing drilling efficiency by minimizing frictional resistance and maintaining a low thermal load on the drill bit.
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Abstract
Description
Title of the invention: Drill Background to the invention
[0001] A drill bit extending along an axis of rotation and comprising a radius, and a plurality of main cutting surfaces each extending in the direction of the axis of rotation from a nose located on the radius, whereby a respective clearance surface adjoining the main cutting surfaces in the circumferential direction forms a clearance angle with respect to a horizontal plane oriented perpendicular to the axis of rotation, and transforms into a flute.
[0002] For an advantageous drilling result, the end face at the end of the drills in the region of the main cutting surface is usually suitably ground using a face grinder. The end face is in this case often designed to be tapered and is produced using a tapered jacket face grinder, or alternatively using a multi-surface grinder. A drill tip having a ground conical jacket surface can be taken from US 2014 / 0308086 AL A so-called "tip" is usually formed in the region of the center of the drill, i.e. in the region of the axis of rotation, in order to thin a drill in the foremost region of the drill tip.
[0003] The design of the drill bit end geometry including the main cutting surfaces as well as the clearance surfaces significantly affects the properties of the drill bit.
[0004] Depending on the application and the choice of material, as well as the machining parameters, e.g. rotational speed, high stresses also arise during the drilling process, in particular by friction. This also affects the chip evacuation via the flute, with a high friction load occurring, in particular in the sub-region of the flank surfaces adjacent to a respective main cutting surface. Subject of the invention
[0005] The aim of the invention is therefore to propose a drill bit which comprises a frontal geometry and which undergoes a lower friction load than conventional drill bits.
[0006] Realization of the object
[0007] The object according to the invention is achieved by a drill bit, which extends along an axis of rotation and has a radius as well as a plurality of main cutting surfaces, which each extend from a nose located on the radius in the direction of the axis of rotation, and thus to a center. The main cutting surfaces adjoin a clearance surface in a circumferential direction, which surface forms a clearance angle relative to a horizontal plane oriented perpendicular to the axis of rotation. Later along its progression, the clearance surface transforms into a flute in a circumferential direction. Viewed in vertical section parallel to the axis of rotation and perpendicular to a radial, an outer section of the clearance surface in the nose region exhibits a curved progression, while a section near the center in the region of the axis of rotation exhibits a linear progression.
[0008] In the present context, the term "radius" means the nominal radius extending from the axis of rotation in the radial direction to the nozzle.
[0009] When viewed in vertical section, the outer section extends along a particular arcuate line, or is determined by approximation by such an arcuate progression through distinct arcuate surface sections.
[0010] The progression of the clearance surface, seen in vertical section, therefore varies from the axis of rotation towards the beak. While the section close to the centre of the clearance surface extends linearly, it extends arcuately in the outer section.
[0011] In this case, the two sections directly adjoin the main cutting surface in a circumferential direction.
[0012] The arcuate progression has the particular advantage that the value of the clearance angle changes in a circumferential direction, in particular increases so that the friction load is reduced in this region. Due to the radial distance from the axis of rotation, the peripheral speed in the region of the nose, and thus in the region of the outer section, is greater than that in the section near the center. By means of the measure described above, an effective measure is created to reduce the friction load in the high speed range.
[0013] The term "near center section" preferably refers to the fact that this section is designed to be in a radial range greater than 0.1 times or greater than 0.2 times the radius. Furthermore, the near center section preferably extends over, for example, at least 0.5 times the radius. Therefore, the immediate region on the axis of rotation itself, thus in the region of a foremost drill tip, and in particular also in the region where the tip is formed, is not part of the near center section, in particular because this immediate region on the axis of rotation typically cannot be defined precisely.
[0014] Rather, at least one radially outer region of the outer section having the curved progression is designed to be at a distance of 0.9 times the radius from the axis of rotation.
[0015] In the preferred embodiment, the value of the clearance angle in the outer section is greater than the value of the clearance angle in the near section from the center. The clearance angle is preferably determined directly adjacent to the main cutting surface. This measurement also takes into account the fact that the peripheral speed in the outer section is higher. Because the clearance angle is greater in this outer section, friction in the outer section is minimized.
[0016] Preferably, the clearance angle in the near-center section having the linear progression has a value in the range of 8° to 10°.
[0017] In the outer section of the preferred embodiment, the value of the clearance angle increases in a circumferential direction, namely from a first value to a second value, due to the curved progression.
[0018] The first value is preferably in the range of 10° to 20°.
[0019] Further, the second value is preferably in the range of 20° to 40°.
[0020] The first value is preferably measured in a circumferential direction at a first angular distance of 5° from the main cutting surface and the second value is measured in a circumferential direction at an angular distance of 15° from the main cutting surface.
[0021] Overall, a particularly suitable design is achieved by the clearance surface created by the varying clearance angle values, which results in a low frictional load, and therefore a low thermal load, on the drill.
[0022] According to a preferred embodiment, the outer section having the curved progression extends continuously into the flute. In other words, the outer section of the clearance surface follows only a curved progression into the flute.
[0023] Alternatively, and particularly additionally, the near-center section in the preferred embodiment having the linear progression extends to the flute, which adjoins in a circumferential direction. In other words, the clearance surface in the near-center section extends only along a straight line into the flute.
[0024] The end of the clearance surface and the beginning of the flute, which adjoins the clearance surface in a circumferential direction, are usually formed by a transition which is, for example, formed by an edge. For example, a flute is normally oriented below a flute angle which is at least 1.5 times or 2 times greater than the clearance angle of the section of the clearance surface located directly in front of the flute. The flute angle is defined by the angle at which a flute wall adjacent to the clearance surface in a circumferential direction is oriented relative to the horizontal plane. This flute angle also depends, among other things, on the angle at which the flute is, for example, oriented at an oblique inclination relative to the axis of rotation. The flute angle is typically in a range greater than 60°.
[0025] According to a particularly preferred embodiment, the clearance surface is divided in a circumferential direction by an imaginary, and in particular linear, dividing line into a first portion facing the main cutting surface and a second portion facing the flute. The dividing line extends from the inside to the outside and intersects the main cutting surface, at least at an external intersection. This external intersection is, for example, greater than 0.7 times, greater than 0.8 times, and in particular greater than 0.9 times the radius. Viewed in vertical section, the first portion of the clearance surface extends linearly, and the second portion extends curvedly.In this embodiment, the region extending to the outer intersection of the clearance surface section that adjoins the main cutting surface, which section forms the first portion, thus defines the near-center section having the linear design. In contrast, the section radially outward from the intersection defines the outer region having the curved progression.
[0026] In the preferred embodiment, the parting line also intersects the main cutting surface at an internal intersection. The latter is in particular in a range less than 0.2 times and in particular less than 0.1 times the radius.
[0027] In this embodiment comprising the two portions of the clearance surface separated by the parting line, the outer region having the curved progression extends continuously from the main edge into the flute. Preferably, the near-center section in this embodiment having the linear progression adjoins additionally, in a circumferential direction, a clearance surface section having a curved progression.
[0028] The dividing line, which divides the first portion which extends linearly and the second portion which extends curvedly, preferably extends in a linear direction.
[0029] In the preferred embodiment, the dividing line is further oriented parallel to a radial passing through the axis of rotation and through the nozzle. Description of the drawings
[0030] An exemplary embodiment of the invention is explained in more detail below with reference to the drawings. The drawings represent the following partially simplified illustrations:
[0031] [Fig.l] is a sectional side view of a drill bit,
[0032] [Fig.2] is a top view of a front face at the end of the drill bit,
[0033] [Fig.3] is a cross-sectional view along line AA of [Fig.2],
[0034] [Fig.4] is a cross-sectional view along line BB of [Fig.2], and
[0035] [Fig.5] is a cross-sectional top view of the end face at the drill bit end with a parting line therethrough, a clearance surface being broken into a first portion and a second portion.
[0036] Description of the exemplary embodiment
[0037] A drill 2, as shown in [Fig.l] and [Fig.2], respectively in side view and in sectional top view, is, for example, designed as a one-piece drill 2. However, the following statements apply equally to, for example, modular drills in which a drill tip is interchangeably attached to a drill shank.
[0038] The drill bit 2 generally extends along an axis of rotation 4, about which it rotates during operation. The front face at the end of the drill bit 2 has a plurality of main cutting surfaces 6 which each extend outwardly from a central tip located on the axis of rotation 4 to a beak 8. The main cutting surfaces 6 extend in a curved manner - seen from above according to [Fig.2].
[0039] Preferably, the main cutting surfaces 6 continue to extend continuously and regularly, therefore also in a non-stepped manner in particular, from the nose 8 to the axis of rotation 4. The drill 2 is therefore not, for example, designed in the form of a stepped drill comprising stepped main cutting surface sections.
[0040] A radial distance between the axis of rotation 4 and a respective beak 8 thus defines a radius r. The connecting line between the axis of rotation 4 and a respective beak 8 defines a radial R. In the exemplary embodiment, the drill 2 comprises a total of three main cutting surfaces 6. Alternatively, the drill comprises only two main cutting surfaces 6, for example.
[0041] A respective clearance surface 10 adjoins the respective main cutting surface 6 in a circumferential direction U. Along its further progression, this surface transforms into a respective flute 12 in a circumferential direction U. This transition is indicated in the drawings by a curved line and is, for example, designed as a rounded edge or transition. From the nose 8, a secondary cutting surface 14 extends along the flute 12.
[0042] A tip can further be formed in the region of the rotation axis 4. The end face of the drill bit comprising the clearance surfaces 4, the main cutting surfaces 6, and optionally the tip is designed as a suitable end face ground surface.
[0043] According to the invention, the respective clearance surface 10 has a particular profile, as will be explained in more detail below with reference to FIGS. 3 to 5.
[0044] In particular, the clearance surface 10 comprises a near-center section 16 in the region of the axis of rotation 4, as well as an outer section 18 in the region of the beak 8.
[0045] View in vertical section according to [Fig.3] and [Fig.4], that is to say in a section plane parallel to the axis of rotation and perpendicular to the radials, the clearance surface 10 extends linearly in the section close to the center 16 and in an arcuate manner in the outer section 18.
[0046] With respect to a horizontal plane H oriented perpendicular to the axis of rotation 4, the clearance surface 10 in the near-center section 16 is oriented below a constant near-center clearance angle a, the value of which is preferably in the range between 8° and 10°.
[0047] Conversely, the progression, in particular convexly curved, in the outer section 16 increases an outer clearance angle, in particular from a first outer clearance angle b 1 to a second outer clearance angle b 2. The first outer clearance angle b 1 is preferably in the range between 10° and 20°, and the second outer clearance angle b 2 is preferably in the range between 20° and 40°.
[0048] The first outer clearance angle b 1 is measured at a first angular distance g 1 from the main cutting surface 6, which is preferably 5°. The second outer clearance angle b2 is measured at a first angular distance g2 from the main cutting surface 6, which is preferably 15°.
[0049] By means of this measure of increasing the clearance angle in the radial direction on the one hand, i.e. from the near-center section 16, then up to the outer section 18, and on the other hand in a circumferential direction U on the outer section 18, the clearance angle is purposefully chosen to increase in size in the regions where a peripheral speed increases during the drilling operation due to the radial distance from the center.
[0050] According to a first embodiment, the near-center section 16 and the outer section 18 both extend in a circumferential direction U to the start of the flute 12.
[0051] According to a preferred embodiment, as shown by way of example in [Fig. 5], the respective clearance surface 10 is divided into a first portion 10A and a second portion 10B. In the first portion 10A, seen in vertical section, the clearance surface 10 extends linearly, as indicated in [Fig. 5] by the linear arrow. In the second portion 10B, on the other hand, the clearance surface 10 extends curvedly in vertical section, as indicated by the curved arrow. The first portion 10A thus forms the section near the center 16. The second portion 10B having the curvilinear progression then adjoins these respectively according to a circumferential direction U.
[0052] The two portions 10A, 10B are separated from each other by a separator line 20 (indicated by dotted lines). In the exemplary embodiment, this line extends linearly and parallel to the radials R. The separator line 20 intersects the main cutting surface 6 at an outer intersection S1 and preferably also at an inner intersection S2. The outer intersection S1 is preferably in a range between 0.7 times the radius r and 0.9 times the radius r. The region of the clearance surface 10 which adjoins the outer intersection S1 forms the outer section 18 described above. In this embodiment too, the latter therefore extends in a continuously curved manner in a circumferential direction U up to the flute 12.
[0053] On the other hand, the internal intersection S2 is preferably less than 0.2 times and, in particular, less than 0.1 times the radius r.
Claims
Claims
1. Drill (2), which extends along an axis of rotation (4) and has a radius (r) as well as a plurality of main cutting surfaces (6), which each extend in the direction of the axis of rotation (4) from a nose (8) located on the radius (r), in which a respective clearance surface (10) adjoins the main cutting surfaces (6) in a circumferential direction (U), forms a clearance angle (a, b1, b2) relative to a horizontal plane (H) oriented perpendicular to an axis of rotation (4), and transforms along its further progression into a flute (12), characterized in that - seen in a vertical section parallel to the axis of rotation (4) - an outer section (18) of the clearance surface (10) in the region of the nose (8) has a curved progression, and a near-center section (16) in the region of the axis of rotation has a linear progression.
2. Drill bit (2) according to the preceding claim, characterized in that the near-center cut (16) having the linear progression is designed to be at least in a range greater than 0.1 times, or greater than 0.2 times, and preferably up to 0.5 times the radius (r).
3. Drill bit (2) according to any one of the preceding claims, characterized in that the outer section (18) having the curved progression is adapted to be at least in a range greater than 0.9 times the radius (r).
4. Drill (2) according to any one of the preceding claims, characterized in that the value of the clearance angle (bl) on the main cutting surface (6) in the outer section (18) is greater than the value of the clearance angle (a) in the near-center section (16).
5. A drill bit (2) according to any preceding claim, characterized in that the clearance angle (a) in the near-center section (16) has a value in the range of 8° to 10°.
6. Drill (2) according to any one of the preceding claims, characterized in that the clearance angle (b 1.2b) in the outer section (18) increases from a first value to a second value, starting from the main cutting surface (6) in a peripheral direction (U).
7. Drill (2) according to the preceding claim, characterized in that the first value is in the range of 10° to 20°.
8. Drill (2) according to any one of the two preceding claims, characterized in that the second value lies in the range of 20° to 40°.
9. Drill bit (2) according to one of claims 6 to 8, characterized in that the first value in a circumferential direction (U) is measured at a first angular distance of 5° relative to the main cutting surface (6), and the second value in a circumferential direction (U) is measured at a second angular distance of 15° relative to the main cutting surface (6).
10. A drill bit (2) according to any preceding claim, characterized in that the outer section (18) having the curved progression extends into the flute (12).
11. A drill bit (2) according to any preceding claim, characterized in that the near-center cut (16) having the linear progression extends into the flute (12).
12. Drill bit (2) according to one of claims 1 to 10, characterized in that the clearance surface (10) is divided in a circumferential direction (U) by a dividing line (20) into a first portion (10A) facing the main cutting surface (6) and a second portion (10B) facing the flute (12), wherein the dividing line (20) extends from the inside to the outside, and the main cutting surface (6) intersects at least one outer intersection (SI), wherein, seen in vertical section, the first portion (10A) extends in a linear manner and the second portion (10B) extends in a curved manner, wherein the outer intersection (SI) is preferably located at more than 0.7 times, and in particular more than 0.9 times the radius (r).
13. Drill bit (2) according to the preceding claim, whereby the parting line (20) further intersects the main cutting surface (6) at an internal intersection (S2), which is preferably located less than 0.2 times and in particular less than 0.1 times the radius (r).
14. Drill (2) according to one of the two preceding claims, wherein the parting line (20) is oriented linearly, in particular parallel to a radial (R) which passes through the axis of rotation (4) and through the nose (8).