Ring-shaped tool for processing a workpiece

Abstract

The invention relates to a ring-shaped tool for processing a workpiece, wherein the tool has a fastening region which is centred with its ring shape for fastening to a rotatable drive shaft, wherein the tool has cutting teeth and the teeth extend on both sides of the tool in each case from the head region of the tool in the direction of the fastening region, the teeth on one side having a right-hand twist and providing right-hand cutting, and the teeth on the other side having a right-hand twist and providing left-hand cutting.

Claims

1. A ring-shaped tool for processing a workpiece, wherein the tool has a fastening region which is centered with its ring shape for fastening to a rotatable drive shaft, wherein the tool has cutting teeth and the teeth extend on both sides of the tool in each case from a head region of the tool in a direction of the fastening region, the teeth on one side, as viewed along a rotation axis on the one side, having a right-hand twist and providing right-hand cutting, and the teeth on the other side, as viewed along the rotation axis on the other side, having a right-hand twist and providing left-hand cutting.

2. The tool according to claim 1, wherein a working region of the tool is given by the head region and the sides having the teeth.

3. The tool according to claim 1, wherein a cutting edge of a tooth on one side and the cutting edge of a tooth on the other side transition into one another at an angle of 170-180 degrees in the head region at a point of intersection, measured in a tangential plane of the ring shape passing through the point of intersection.

4. The tool according to claim 1, wherein the teeth in an axial direction of the tool have an arch shape with an apex in the head region, wherein the arch shape is provided on one of the sides by two circles that transition tangentially into one another smoothly with a first circle radius and a second circle radius, a circle center for the first circle radius lying beneath the apex, and the circle center for the second circle radius lying beneath the circle center for the first circle radius as viewed in a radial direction, the first circle radius being smaller than the second circle radius.

5. The tool according to claim 4, wherein, as viewed in the radial direction of the tool, a distance between the circle centers of the first circle radius and the second circle radius is between 0.5 and 0.7 times a difference between the first circle radius and the second circle radius.

6. The tool according to claim 4, wherein a ratio of the second circle radius to the first circle radius is between 10 and 20.

7. The tool according to claim 6, wherein the ratio of the second circle radius to the first circle radius is between 14 and 17.

8. The tool according to claim 1, wherein the twist is constant over the sides of the tool.

9. The tool according to claim 1, wherein for each of the sides a cutting depth of the teeth decreases continuously starting from the head region in the direction of the fastening region.

10. The tool according to claim 9, wherein the cutting depth of parts of the teeth adjacent to the fastening region is 4-6 times smaller than the cutting depth of the parts of the teeth in the head region.

11. Use of a tool according to claim 1 for use in hand tools or in cutting machines, wherein, during use, the tool is applied optionally on a head side or by one of the sides to a workpiece that is to be processed.

Description

(1) Preferred embodiments of the invention will be explained in greater detail hereinafter with reference to the drawings, in which:

(2) FIG. 1 shows a perspective view of a first side of a tool with drive means,

(3) FIG. 2 shows a perspective view of a second side of a tool,

(4) FIG. 3 shows a perspective view of a head region of a tool,

(5) FIG. 4 shows a schematic cross-sectional view of a tool with drive means,

(6) FIGS. 5a and 5b show schematic views of method steps for processing a workpiece, and

(7) FIGS. 6a and 6b show schematic views of method steps for processing a workpiece.

(8) Hereinafter, similar elements are denoted by like reference signs.

(9) FIG. 1 shows a perspective view of a tool 100, installed in a machine having a drive means 102, for example a manually operable angle grinder. The drive means 102 drives the tool 100 in rotation via a shaft 104. The tool may remove material from a workpiece via teeth 106 of the tool. The tool 100 has a ring shape, with the teeth 106 being arranged over the circumference of the tool.

(10) In FIG. 1 it can be seen in the perspective side view of the tool 100 that the teeth 106 are formed with a curved right-hand twist starting from the head side of the tool. The curvature 108 extends from the head side over the end region. This is used to provide an efficient material discharge (chip discharge) during use of the tool. The smooth running of the tool thus increases. This could be further increased if the teeth are interrupted regularly or irregularly along the curvature 108. In one example, the curvature is designed such that the twist angle of a tooth in the head region relative to a radial extent is 30 degrees and decreases as far as the fastening region to 20 degrees, i.e. the curvature corresponds to a twist difference of −10 degrees.

(11) In the shown perspective, the teeth are structured relative to one another such that they provide a right-hand-cutting tool, i.e. a milling effect is created as the ring rotates in a clockwise direction. The teeth have an angle of attack relative to the running direction of the tool that lies typically in the range of 65-85 degrees (corresponds to a rake angle between 5 and 25 degrees). In this range there is typically an optimal compromise between a maximisation of the cutting effect, mechanical stability of the teeth, manual handling of the tool, smoothness of running, and material removal efficiency. In one example, for the processing of aluminium, the rake angle of the teeth could be −20 degrees, the clearance angle +10 degrees, and the twist angle in the head region 30 degrees to the right. The material of the teeth is preferably tungsten carbide.

(12) The rake angle of the tooth face (cutting face) may be adapted homogeneously (for example ground) in accordance with the depth of the teeth as a function of the radial position. An improved control of the chip formation could thus be achieved for example by a continuous transition from machining (large rake angle in the vicinity of the fastening region) to transportation away (small rake angle in the vicinity of the head region).

(13) In one example, the teeth of the tool are formed with a transition of the tooth depth of 4.5 mm at the head region to 0.9 mm at the fastening region via a ring width of 27.5 mm. With this geometry, the risk of a clogging of the chip space could be prevented.

(14) FIG. 2 shows a perspective side view of the tool from FIG. 1 from the second side, facing away from the viewer in FIG. 1. This second side provides left-hand cutting (mills when rotated in an anti-clockwise direction) and is also formed with a right-hand twist of the teeth. If the tool were installed as in FIG. 1, this would be the side of the tool facing away from the machine, by which material may be milled in planar fashion (surface milling). Due to the right-hand twist, chips produced during surface milling could be transported radially outwardly, which could prevent a clogging of the chip space of the milling machine.

(15) In one example, the tool 100 has the following dimensions: outer diameter (measured between the radially outer end points of the cutting edges of two opposite teeth 106): 181 mm; outer diameter (measured between the radially outer end points of the bases of two opposite grooves): 178 mm; inner diameter (measured between the radially inner end points of the cutting edges of two opposite teeth 106): 123 mm; outer diameter of the fastening region 200: 120 mm; inner diameter of the fastening region 200 (diameter of the ring opening): 105 mm; thickness of the tool 100 (measured between the radially inner end points of the cutting edges of two opposite teeth 106): 20 mm; thickness of the fastening region 200: 6 mm; first circle radius: 2.5 mm; second circle radius: 52.5 mm.

(16) In another example the tool 100 has the following dimensions: outer diameter (measured between the radially outer end points of the cutting edges of two opposite teeth 106): 231 mm; outer diameter (measured between the radially outer end points of the bases of two opposite grooves): 228 mm; inner diameter (measured between the radially inner end points of the cutting edges of two opposite teeth 106): 173 mm; outer diameter of the fastening region 200: 167 mm; inner diameter of the fastening region 200 (diameter of the ring opening): 152 mm; thickness of the tool 100 (measured between the radially inner end points of the cutting edges of two opposite teeth 106): 20 mm; thickness of the fastening region 200: 6 mm; first circle radius: 2.5 mm; second circle radius: 52.5 mm.

(17) FIG. 3 shows a perspective view of a tool 100, in which the head region of the tool 100 faces the viewer. The teeth 106 of the tool 100 are formed on both sides with a right-hand twist and at the apex contact one another in pairs via their cutting edges at an angle of 170-180 degrees. In the shown orientation of the tool, the left-hand side provides right-hand cutting and the right-hand side provides left-hand cutting, i.e. the milling effect of the tool 100 is created upon rotation in the rotation direction 300, in which the head region, which is facing the viewer, runs downwardly. With installation of the tool 100 in a milling machine with drive running in a clockwise direction (as viewed from the drive to the tool), the left-hand side would face the drive. With use of the tool 100 installed in this way as a surface milling ring for processing a workpiece by the right end face of the tool 100, the chips created could advantageously be discharged radially outwardly on account of the right-hand twist.

(18) FIG. 4 shows a schematic cross-sectional view of the tool 100 of FIG. 1, wherein it can now be seen that the shaft 104 acts on a fastening region 200 of the tool 100. The section through an individual tooth 106 is also visible in FIG. 4 in the cross-sectional view, the tooth extending at least in part from the head side 402 via an end region 404 of the tool. In the axial direction (that is to say from left to right in FIG. 4), the tooth 106 has an arch shape with an apex and is formed mirror-symmetrically to the ring face of the tool passing through the apex. The teeth are thus formed on both sides of the tool, and the teeth on the left-hand side have a right-hand twist and provide left-hand cutting, whereas the teeth on the right-hand side have a right-hand twist and provide right-hand cutting.

(19) The arch shape is describable in FIG. 4 by two circles, which transition tangentially into one another contourlessly. The arch shape describable by the two circles is definable by two circle radiuses, specifically a first radius 406 and a second radius 408. A particularly high smooth running of the tool when removing material could be provided by the ratio of the two radiuses of approximately a factor of 15.

(20) As is also shown in FIG. 4, the tooth 106 extends only approximately as far as the circle centre of the second radius 404 in the end region 404. As viewed in the radial direction of the tool 100, the distance 410 between the circle centres of the first and second circle radius is approximately 0.6 times the difference between the first and second circle radius.

(21) FIG. 5a shows a workpiece 504 with a weld seam 506. In order to open the weld seam, i.e. the weld root, the tool 100 is now used, which is set in rotation in the direction 500 by a drive (not shown here). The tool 100 is placed in the weld seam 506 in a direction 502 and now removes material continuously.

(22) The result is shown in FIG. 5b, wherein the resultant milling notch 508 has the tooth shape of the tool 100. The milling notch 508 may now be welded again or filled otherwise with material.

(23) FIG. 6a shows a workpiece 504 with a level vertical surface 602. The tool 100 is now used to mill the surface, for example in order to prepare a subsequent welding step. To this end, the tool is set in a rotational movement in the direction 500 by a drive (not shown here). The tool 100 is placed onto the surface 602 in the direction 600 and then removes material continuously.

(24) The result is shown in FIG. 6b, wherein the resultant milled surface 604 has the tooth shape of the tool 100. The milled surface 604 may now be welded, for example to a second workpiece (not shown), which has been milled similarly on an opposite surface by a milling face. As the two workpieces are joined together, the two opposite milling surfaces form a notch, which is then filled with material during the welding.

LIST OF REFERENCE SIGNS

(25) 100 tool

(26) 102 drive element

(27) 104 shaft

(28) 106 tooth

(29) 108 curvature

(30) 200 fastening region

(31) 300 direction

(32) 402 head region

(33) 404 end region

(34) 406 first radius

(35) 408 second radius

(36) 410 distance

(37) 500 rotation direction

(38) 502 direction

(39) 504 workpiece

(40) 506 weld root

(41) 508 milling notch

(42) 600 direction

(43) 602 surface

(44) 604 milled surface