WOOD DRILL

Abstract

In a wood drill (100) having a clamping portion (110) for connecting, for conjoint rotation, to a tool fitting of a portable power tool, and a head portion (200) which is provided with a centring geometry (250), wherein the clamping portion (130) is formed at a first end (202), remote from a workpiece, and the head portion (200) is formed at a second end (204), close to a workpiece, of the wood drill (100), wherein the clamping portion (110) is connected to the head portion (200) via a shank portion (130), and wherein a maximum outside radius (RK) of the head portion (200) is greater than a maximum outside radius (RS) of the shank portion (130), the head portion (200) has at least one main lip (214, 216) with at least two stages (230, 232, 234) for introducing a bore (152) with a predefined inside radius (RB) into a workpiece (150), and an outside radius (RH) of a main lip base (260) is less than 60%, preferably less than 50%, of an outside radius (RK) of the head portion.

Description

[0001] Description

[0002] title

[0003] wood drill

[0004] State of the art

[0005] The present invention relates to a wood drill bit with a clamping section for rotationally fixed connection with a tool holder of a hand-held power tool, and a head section which is provided with a centering geometry, wherein the clamping section is formed at a first end facing away from the workpiece and the head section at a second end of the wood drill bit facing the workpiece, wherein the clamping section is connected to the head section via a shank section, and wherein a maximum outer radius of the head section is greater than a maximum outer radius of the shank section.

[0006] Wood drill bits are known in a wide variety of designs. They allow for drilling holes with high dimensional accuracy in wood or wood-like materials. However, such workpieces often contain metallic objects, such as fasteners and / or fixings in the form of nails, screws, or staples. If the wood drill bit comes into contact with these metallic objects during drilling, this leads to significant wear on the cutting edges and a correspondingly considerable reduction in tool life.

[0007] From EP 2217417 B1, an auger drill with a reamer is known. This previously known drill can cut through a large number of metal nails, at least when drilling in wood at slow speed and high torque, without a significant decrease in drilling performance due to dulling of the main cutting edges.

[0008] Disclosure of the Invention: The present invention relates to a wood drill bit with a clamping section for a rotationally fixed connection to a tool holder of a power tool, and with a head section provided with a centering geometry. The clamping section is formed at a first end facing away from the workpiece, and the head section at a second end of the wood drill bit facing the workpiece. The clamping section is connected to the head section via a shank section, and the maximum outer radius of the head section is greater than the maximum outer radius of the shank section. The head section has at least one main cutting edge with at least two steps. According to one embodiment, the head section serves to bore a hole with a predetermined inner radius into a workpiece, wherein the outer radius of a main cutting edge base is less than 60%, preferably less than 50%, of the outer radius of the head section.

[0009] Due to the preferably multi-stage, axially retracted design of the at least one main cutting edge of the wood drill bit, metal bodies located within the workpiece are cut through in sections, resulting in considerably less wear on the main cutting edge. The wood drill bit can easily cut through metal bodies even at high speeds, and not only in the torque mode of a hand-held power tool at reduced speed and high torque. The dimensioning of the main stage also limits the required drive torque of the wood drill bit when cutting through metallic objects. The wood drill bit is preferably intended for drilling in wood and other comparably soft materials, such as plastic. The overall axial length of the wood drill bit can preferably be up to 600 mm with a diameter preferably between 6 mm and 35 mm.

[0010] Preferably, the head section has a spirally wound surface geometry with at least one chip groove and at least one secondary cutting edge.

[0011] The spirally wound surface geometry ensures the trouble-free removal of chips produced during drilling. The secondary cutting edges guarantee a virtually smooth inner wall for holes drilled into the workpiece with a wood drill bit.

[0012] Preferably, the at least two steps of the at least one main cutting edge are each set back axially by one step height in relation to the radially inner main cutting edge base towards the second end of the wood drill.

[0013] As a result, the main cutting edge separates a metal object piece by piece into metal fragments and therefore does not have to completely remove the metal object across its transverse extent in relation to the longitudinal center axis.

[0014] In a technically advantageous further development, each of the at least two stages of the main cutting edge has a radial step width.

[0015] Due to the at least one radially outermost step of a main cutting edge, improved cutting results are achieved in wood that is interspersed with metal bodies such as nails, screws, staples, etc.

[0016] According to a favorable embodiment, the radial step width is between 1 mm and 10 mm, preferably between 2 mm and 5 mm.

[0017] This exemplary design results in improved work outcomes.

[0018] Preferably, each step base of the at least two steps is inclined by a step angle perpendicular to the longitudinal center axis in the direction of the first end of the wood drill.

[0019] This results in a simple and improved cutting of any metal components present in the workpiece. The step walls of the steps run essentially parallel to the longitudinal center axis of the wood drill bit.

[0020] Preferably the step angle is between 0° and 65°, preferably at approximately 0°. As a result, easily and simply improved working results are achieved when using the wood drill.

[0021] According to a further embodiment, a profile angle of between 10° and 30° exists between the at least one main cutting edge and perpendicular to the longitudinal center axis. If the shank section deviates from a cylindrical shape and has a helical geometry, the profile angle should be greater than the pitch of this helical shank geometry. A profile angle of between 15° and 25° is particularly preferred.

[0022] This allows for safe and reliable improvement in cutting results.

[0023] Preferably, the wedge angle of at least one main cutting edge is approximately 60°.

[0024] This allows for the provision of a robust and durable cutting edge, which can preferably increase the service life of the wood drill bit.

[0025] Preferably, a rake angle exists between the at least one chip groove and the longitudinal center axis. The rake angle is preferably 15°.

[0026] This ensures improved, gradual cutting through any metallic foreign matter that may be present in a wooden workpiece. Furthermore, chips are safely and reliably removed from the borehole.

[0027] In another favorable embodiment, the centering geometry is screw-like with a spirally circumferential thread with a pitch.

[0028] This allows the wood drill bit to automatically pull itself into the workpiece after being positioned, preferably with simultaneous and precise centering. The thread pitch is preferably between 1 mm and 2.5 mm.

[0029] As a result, the wood drill bit is easily and quickly drawn into the workpiece to be drilled after being positioned, enabling precise centering and dimensionally accurate drilling.

[0030] Preferably, the wood drill bit is made of high-strength carbon steel. Alternatively, at least the cutting edge can be made of high-speed steel (HSS) and / or tungsten carbide. The main cutting edge is designed to allow manufacturing using conventional machining processes and / or known hot or cold forming processes such as forging, bending, or stamping.

[0031] As a result, the wood drill bit has a comparatively long service life. Brief description of the drawings

[0032] The invention is explained in more detail in the following description with reference to embodiments shown in the drawings. These show:

[0033] Fig. 1 shows a side view of a wood drill bit,

[0034] Fig. 2 shows a side view of the wood drill bit from Fig. 1, rotated by 90° about a longitudinal central axis.

[0035] Fig. 3 is a top view of the wood drill bit from Fig. 2,

[0036] Fig. 4 shows a partial top view of a head section of the wood drill bit from Fig. 2.

[0037] Fig. 5 is an enlarged partial top view of the head section of Fig. 4, and

[0038] Fig. 6 is a partial top view of the head section of Fig. 5, rotated by 90° about the longitudinal center axis.

[0039] Description of the exemplary embodiments: Fig. 1 shows a wood drill 100, which includes, among other things, a clamping section 110 for a rotationally fixed connection with a tool holder of a hand-held power tool (not shown), and a head section 200 with a centering geometry 250. A preferably cylindrical shank section 130 runs between the clamping section 110 and the head section 200. The wood drill 100 can be designed as a wood twist drill, auger drill, and / or serpentine drill.

[0040] The clamping section 110, which here merely exemplifies six tangential flats, is formed at a first end 202, and the head section 200 with the centering geometry 250 is formed at a second end 204 of the wood drill 100, which faces away from the first end. It should be noted that the clamping section 110 can also have more or fewer than six flats. Furthermore, the clamping section 110 can also be designed as a round shank. The head section 200, for illustrative purposes, has an approximately helical surface geometry 206 with two chip flutes 240, 242 spirally wound around a longitudinal central axis 210. The maximum radius Rs of the shank section 130 is, for example, significantly smaller than the maximum outer radius R. K The head section 200 of the wood drill bit 100 is designed. Furthermore, the overall axial length L of the wood drill bit 100 can be up to 600 mm.

[0041] The wood drill 100 is preferably designed to be rotationally symmetrical about the longitudinal center axis 210. The head section 200 of the wood drill 100 has, by way of example, two main cutting edges 214, 216 facing a workpiece 150, which are diametrically opposed to each other with respect to the longitudinal center axis 210.

[0042] In order to cut through any metal objects present in the workpiece 150, such as nails, screws, staples, clamps, or the like, more easily and with less wear, the first main cutting edge 214 of the wood drill 100 has, by way of example, three steps projecting axially from the second end 204 – not shown here for the sake of clarity. In addition, the first main cutting edge 214 of the head section 200 of the wood drill 100 preferably has a first radially internal main cutting edge base 260, and correspondingly the second main cutting edge 216 has a second radially internal main cutting edge base 262. There is preferably an angle of less than 90°, but preferably only slightly less, between both main cutting edge bases 260, 262 and the longitudinal center axis 210. Here, the two main cutting bases 260, 262 of the head section 200 are preferably inclined in the direction of the first end 202.

[0043] An example bore 152, drilled into the workpiece 150 using a wood drill 100, with an approximately cylindrical inner wall 154, has an inner radius of R B preferably the inner radius R corresponds B essentially with the outer radius R K of the head section 200 of the wooden drill bit 100. An outer radius R H The radius of both main cutting edge bases 260, 262 is preferably less than 60%, more preferably less than 50%, of the outer radius of the head section 200. Furthermore, the head section 200 preferably has two secondary cutting edges, of which only one secondary cutting edge 220 is shown and labelled in the drawing.

[0044] Preferably, the wood drill bit 100 comprises at least some sections made of high-strength carbon steel, high-speed steel (HSS), and / or carbide. According to one embodiment, the wood drill bit 100 is made of carbon steel, in particular high-strength carbon steel. Alternatively, at least the main cutting edges 214, 216, or their cutting edges, can be made of high-speed steel (HSS) and / or tungsten carbide. The main cutting edges 214, 216 are preferably designed such that they can be manufactured using conventional machining processes and / or by known hot or cold forming processes such as forging, bending, or punching.

[0045] Fig. 2 shows the wood drill 100 from Fig. 1 with the clamping section 110, the shank section 130, and the head section 200. The head section 200 preferably has a centering geometry 250 and is rotationally symmetrical about the longitudinal center axis 210. The clamping section 110 is formed at the first end 202, and the head section 200, including the centering section 250, is formed at the second end 204. The exemplary maggot-shaped centering section 250 preferably has a thread 252 with a helically circumferential thread 254 and a centering tip 256. The wood drill 100 has, for illustrative purposes, a total axial length L of up to 600 mm, i.e., including the clamping, shank, and head sections 110, 130, 200. Fig. 3 shows the wood drill 100 from Fig. 2, wherein the head section 200 of the wood drill 100 has a substantially circular circumferential contour 208. The circumferential contour 208 preferably has a bore or...The cutting operation involves a direction of rotation 199. The multi-stepped cutting edge 214 with the main cutting base 260 and the multi-stepped cutting edge 216 with the main cutting base 262 are, by way of example, rotationally symmetrical about the centering geometry 250 and the longitudinal center axis 210. A secondary cutting edge 220, running approximately parallel to the longitudinal center axis 210 in the area relative to the plane of the drawing, adjoins the first main cutting edge 214. Similarly, a secondary cutting edge 222 preferably adjoins the second main cutting edge 216. Finally, the two helical chip flutes 240, 242 run around the inner side between the stepped main cutting edges 214, 216.

[0046] Fig. 4 shows the head section 200 of the wood drill 100 from Fig. 2 and illustrates the centering geometry 250. Preferably, the head section 200 has the centering geometry 250 with the thread 252 formed coaxially with the longitudinal center axis 210 at the second end 204 of the wood drill 100. The thread 252 preferably has the helical thread 254. The head section 200 of the wood drill 100 has the outer radius R K The head section 200 also features the chip groove 240 and the secondary cutting edge 220. The main cutting edge 214 has the main cutting edge base 260 and at least two, preferably three, axially recessed steps 230, 232, 234, each with respect to the second end 204, for cutting through a metal object 156 located in the workpiece as required, in particular in the form of a connecting element 158 ​​and / or fastening element during the drilling process. The main cutting edge base 260 has the outer radius R Hon.

[0047] The metal object 156, located in the workpiece (not shown here), which is represented here only as an example of a connecting element 158 ​​in the form of a nail 162, is, according to the invention, successively divided or dismantled into small metal fragments 166 by the action of the multi-stage main cutting edge 214 during the drilling process. As a result, the service life of the wood drill 100 can be considerably increased compared to previously known solutions. Fig. 5 shows the head section 200 of the wood drill 100 from Fig. 4, which has the chip groove 240 and the centering geometry 250 with the thread 252, the thread pitch 254, and the exemplary mandrel-type centering tip 256 at the second end 204 of the wood drill 100. The pitch S of the thread 254 of the thread 252 is preferably between 1 mm and 2.5 mm. The longitudinal center axis 210 of the wood drill 100 runs coaxially to the centering geometry 250.

[0048] The main cutting edge 214 preferably has the main cutting edge base 260 as well as the three radially outwardly positioned and axially recessed steps 230, 232, 234, which are shown only as examples. The main cutting edge 214 is subdivided into at least three sections or steps 230, 232, 234, offset axially backwards or toward the first axial end 202. The first step 230 preferably has a step base 270 and a step wall 280. Similarly, the second step 232 preferably has a step base 272 and a step wall 282. The third step 234 has a step base 274 and a step wall 284. The at least two, illustratively three steps 230, 232, 234 of the main cutting edge 214 visible here each step back by an axial step height H in relation to the radially inner main cutting edge base 260 in the direction of the first end 202 of the wood drill 100.A radial step width B of steps 230, 232, 234 is between 1 mm and 10 mm, but preferably between 2 mm and 5 mm.

[0049] The step walls 280, 282, 284 are shown to run approximately parallel to the longitudinal center axis 210, while the step bases 270, 272, 274 are each inclined at a step angle α relative to the longitudinal center axis 210. The angle α is the angle between a perpendicular 290 to the longitudinal center axis 210 and the respective step base 270, 272, 274 of the steps 230.

[0050] 232, 234 defined. The step angle α can be in a range between 0° and 65°, with a step angle α of about 40° being preferred.

[0051] Fig. 6 shows the head section 200 of the wood drill bit 100 from Fig. 5 and illustrates the two main cutting edges 214, 216 and the centering geometry 250. A profile angle β exists between the at least one main cutting edge 214, 216 and the perpendicular 290 to the longitudinal center axis 210, preferably between 10° and 30°. To achieve improved results, the profile angle β preferably has a value between 15° and 25°. The wedge angle g of the at least one main cutting edge 214, 216 is shown here, by way of example, on the order of approximately 60°. Between the preferably two chip grooves 240, 242 of Fig. 2, of which only one chip groove 240 is visible here, and the longitudinal center axis 210 there is also a rake angle d, which here is only by way of example about 15°.

Claims

Claims 1. A wood drill bit (100) with a clamping section (110) for a rotationally fixed connection to a tool holder of a hand-held power tool, and a head section (200) which is provided with a centering geometry (250), wherein the clamping section (130) is formed at a first end (202) facing away from the workpiece and the head section (200) is formed at a second end (204) facing the workpiece of the wood drill bit (100), wherein the clamping section (110) is connected to the head section (200) via a shank section (130), and wherein a maximum outer radius (RK) of the head section (200) is greater than a maximum outer radius (Rs) of the shank section (130), characterized in that the head section (200) has at least one main cutting edge (214, 216) with at least two steps (230, 232, 234) for The drilling process involves creating a bore (152) with a predetermined inner radius (RB) in a workpiece (150), and an outer radius (RH) of a main cutting base (260) is less than 60%.preferably less than 50% of an outer radius (RK) of the head section (200).

2. Wood drill bit according to claim 1, characterized in that the head section (200) has a spirally wound surface geometry (206) with at least one chip groove (240, 242) and with at least one secondary cutting edge (220, 222).

3. Wood drill according to claim 1 or 2, characterized in that the at least two steps (230, 232, 234) of the at least one main cutting edge (214, 216) are set back axially by one step height (H) in the direction of the first end (202) of the wood drill (100) with respect to the radially inner main cutting edge base (260).

4. Wood drill according to claim 3, characterized in that each of the at least two steps (230, 232, 234) of the main cutting edge (214, 216) has a radial step width (B).

5. Wood drill bit according to claim 4, characterized in that the radial step width (B) is between 1 mm and 10 mm, preferably between 2 mm and 5 mm.

6. Wood drill according to one of the preceding claims, characterized in that each step base (270, 272, 274) of the at least two steps (230, 232, 234) is inclined by a step angle (a) perpendicular to the longitudinal center axis (210) in the direction of the first end (202) of the wood drill (100).

7. Wood drill according to claim 6, characterized in that the step angle (a) is between 0° and 65°, preferably at about 40°.

8. Wood drill according to one of the preceding claims, characterized in that a profile angle (β) exists between the at least one main cutting edge (214, 216) and perpendicular to the longitudinal central axis (210), which is between 10° and 30°, in particular between 15° and 25°.

9. Wood drill according to one of the preceding claims, characterized in that a wedge angle (g) of the at least one main cutting edge (214, 216) is approximately 60°.

10. Wood drill according to one of the preceding claims, characterized in that there is approximately a rake angle (d) between the at least one chip groove (240, 242) and the longitudinal center axis (210).

11. Wood drill according to one of the preceding claims, characterized in that the centering geometry (250) is designed in a screw-like manner with a spirally circumferential thread (252) with a pitch (S).

12. Wood drill bit according to claim 11, characterized in that the pitch (S) of the thread (252) is between 1 mm and 2.5 mm.

13. Wood drill bit according to one of the preceding claims, characterized in that the wood drill bit (100) is made of a high-strength carbon steel.