MACHINING TOOL FOR DEBURRING BOREHOLES

Abstract

A machining tool for deburring boreholes, which lead laterally into a recess, comprising: a shaft; a cutting head with at least one circumferential cutting blade associated with a chip groove and having a cutting edge extending, at least in sections, in an axial direction, and which can perform a cutting process by virtue of relative movement between the tool and a workpiece, and which lies on a virtual cylindrical rotation surface; and at least one cutting-blade-free and chip-groove-free surface area; at least one fluid channel closed on the cutting head side, extending through the shaft into the cutting head; and at least one branch channel with an outlet opening. The outlet opening is in a dynamic pressure active surface radially set back relative to the virtual rotation surface, and is larger than a flow cross-sectional area of the at least one branch channel at the outlet opening.

Claims

1. A machining/cutting tool, for deburring boreholes that lead laterally into a recess, comprising: a shaft, a cutting head with at least one circumferential cutting blade which is associated with a chip groove and which has a cutting edge, which extends, at least in sections, in an axial direction, and which is configured to perform a cutting process by virtue of a relative movement between the tool and a work piece, and lies on a virtual cylindrical rotation surface a diameter of which corresponds with a nominal diameter of the machining tool, and at least one cutting-blade-free and chip-groove-free surface area, at least one fluid channel closed on a cutting head side, which extends through the shaft into the cutting head, and at least one branch channel emanating from the fluid channel with an outlet opening in the cutting-blade-free and chip-groove-free surface area, the outlet opening located in the cutting-blade-free and chip-groove-free surface area in a dynamic pressure active surface which is radially set back in relation to the virtual rotation surface of the cutting head and which is larger than a flow cross-sectional area of the at least one branch channel at the outlet opening.

2. The machining/cutting tool according to claim 1, wherein the dynamic pressure active surface is provided such that the total of the dynamic pressure forces produced in the area of the dynamic pressure active surface between the machining tool or the cutting head and the inner wall of the recess, can deflect the shaft in a radial direction.

3. The machining/cutting tool according to claim 1, wherein the dynamic pressure active surface is in the form of a flat surface.

4. The machining/cutting tool according to claim 1, wherein the dynamic pressure active surface is in the form of a trough-like hollow.

5. The machining/cutting tool according to claim 1, wherein the dynamic pressure active surface is formed as concave or convex in a direction of the at least one branch channel.

6. The machining/cutting tool according to claim 1, wherein the dynamic pressure active surface runs axially parallel to a longitudinal centre line of the tool.

7. The machining/cutting tool according to claim 1, wherein the dynamic pressure active surface has a smaller axial length than the cutting head.

8. The machining/cutting tool according to claim 7, wherein the dynamic pressure active surface, viewed in a feed direction of the tool, ends at a defined distance from front and rear ends of the cutting head.

9. The machining/cutting tool according to claim 1, wherein the machining tool has two linear branch channels extending out from the at least one fluid channel.

10. The machining/cutting tool according to claim 1, wherein the at least one fluid channel runs along a longitudinal centre axis of the machining tool.

11. The machining/cutting tool according to claim 1, wherein a diameter of the cutting head is larger than a diameter of the shaft.

12. The machining/cutting tool according to claim 1, wherein the cutting head has a multiplicity of cutting blades with straight grooves.

13. The machining/cutting tool according to claim 1, wherein a number of internal fluid channels are provided.

14. The machining/cutting tool according to claim 1, wherein the cutting head has a tap point at least on a side facing away from the shaft.

15. The machining/cutting tool according to claim 1, wherein the machining tool is in the form of a milling or a drilling tool or a reamer.

16. The machining/cutting tool according to claim 1, wherein the cutting head is divided, in a circumferential direction, into a cutting blade section and a cutting-blade-free and chip-groove-free section, which forms the cutting-blade-free and chip-groove-free surface area.

17. The machining/cutting tool according to claim 1, wherein the machining/cutting tool is rotationally driven.

18. The machining/cutting tool according to claim 1, wherein the recess is cylindrical.

19. The machining/cutting tool according to claim 1, wherein the cutting head has three cutting blades with straight grooves.

Description

[0031] Various embodiments of a machining tool according to the invention are explained below using the attached drawings.

[0032] FIG. 1 shows a perspective view of a first embodiment of a machining tool;

[0033] FIG. 2 shows a schematic side view of the machining tool in FIG. 1.

[0034] FIG. 3 shows a second schematic side view of the machining tool in FIG. 1.

[0035] FIG. 4 shows a cross-section view of the cutting head of the machining tool in FIG. 1.

[0036] FIG. 5 shows an enlarged detail A from FIG. 2.

[0037] FIG. 6 shows a perspective view of a cutting head of the first embodiment of a machining tool.

[0038] FIG. 7 shows a cross-section view of the cutting head in FIG. 6.

[0039] FIG. 8 shows a perspective view of a cutting head of a second embodiment of a machining tool.

[0040] FIG. 9 shows a cross-section view of the cutting head in FIG. 8.

[0041] FIG. 10 shows a perspective view of a cutting head of a third embodiment of a machining tool.

[0042] FIG. 11 shows a cross-section view of a borehole leading into a cylindrical recess.

[0043] FIGS. 1 to 7 show a preferred first embodiment of a rotationally driven machining tool 10 according to the invention which is formed, by way of example, as a reamer.

[0044] The work tool 10 has a shaft 20, a cutting head 30, a fluid channel 21 and two branch channels 50.

[0045] The shaft 20 serves to fix the work tool in a chuck. FIGS. 1, 2 and 3 show that the diameter of shaft 20 tapers in the direction of the cutting head 30. The tapered longitudinal section 22 of the shaft 20 is smaller in diameter than the nominal diameter of the cutting head 30. The diametrically tapered longitudinal section 22 of the shaft 20 ensures that the work tool 10 is flexible, which facilitates a radial deflection of the cutting head 30.

[0046] The cutting head 30 sits axially on the tapered longitudinal section 22 of the shaft 20. The straight-grooved cutting head 30 shown in the embodiment has three cutting blades with three cutting edges 31, which extend in a linear manner in an axial direction, perform a cutting process by virtue of a relative movement between the work tool 10 and the work piece to be processed and which are located on a virtual cylindrical rotation surface 40 (see FIG. 4). The diameter of the virtual cylindrical rotation surface 40 corresponds to the nominal diameter of the cutting head 30 of the work tool 10. Further, the cutting head 30 has a cutting-blade-free and chip-groove-free surface area 32, in which there are no cutting blades and no chip grooves and which therefore does not perform a cutting process.

[0047] Furthermore, the work tool 10 has an inner fluid channel 21 closed on the cutting head side, which extends along the longitudinal axis 11 through the shaft 20 into the cutting head 30 and from which two radial branch channels 50 extend out in the cutting head 30 area. The branch channels 50 are arranged so that they lead with an outlet opening 51 into a dynamic pressure active surface 60, which is located within the cutting-blade-free and chip-groove-free surface area 32, as shown in FIG. 4.

[0048] In the embodiment shown according to FIGS. 1, 3, 4, 6 and 7, the dynamic pressure active surface 60 is a flat rectangular surface which runs parallel to the longitudinal axis 11 and which is radially set back in relation to the rotation surface 40 of the cutting head 30. The dynamic pressure active surface 60 therefore lies radially inside the virtual rotation surface 40. The radial distance r of the dynamic pressure active surface 60 from the longitudinal axis 11 is smaller than the radius R of the virtual cylindrical rotation surface 40, the diameter of which corresponds to the nominal diameter of the work tool 10. FIGS. 1 and 3 show that the dynamic pressure active surface 60 extends in an axial direction over the whole length of the cutting head 30, and so has the same axial length as the cutting head 30. FIGS. 1 and 3 further show that the dynamic pressure active surface 60 is larger than the sum of the flow cross-sectional surfaces of the branch channels 50 at the outlet openings 51.

[0049] FIG. 4 shows that the dynamic pressure active surface 60 is located, at least largely, opposite the middle of the cross-sectionally segment-shaped cutting blade section 33 in which the cutting blades with cutting edges 31 are arranged. The dynamic pressure active surface 60 is advantageously arranged largely vertically in relation to the angle bisector of the cutting blade section 33 or the segment of the cutting-blade-free and chip-groove-free surface area 32.

[0050] In addition, FIG. 4 shows that the outer surface of the cutting-blade-free and chip-groove-free surface area 32 in the embodiment shown features two cylindrical rotation surface sections 32a, 32b, and the dynamic pressure active surface 60.

[0051] The cutting-blade-free and chip-groove-free surface area 32 facilitates a spreading over the dynamic pressure active surface 60 of the fluid leaving the outlet openings of the branch channels 50 in the area or volume between the work tool 10 and the opposite inner wall of the recess 2 of a work piece which is to be machined. Assuming there is a sufficient fluid supply into the fluid channel 21, the dynamic pressure of the fluid leaving the branch channels 50 via the outlet openings 51, which is building up in this area or volume, acts on the dynamic pressure active surface 60, producing a radial force which effects a deflection of the cutting head 30 in the direction of the cutting blades with cutting edges 31.

[0052] As a result of the radial deflection, the cutting edges 31 of the cutting blades move largely on a circular path around the longitudinal axis 11. It has been shown that it is possible in this way to carefully as well as reproducibly and reliably remove a burr, or if necessary existing chip residue in a borehole 1 which leads laterally into a cylindrical recess 2 without running the risk that further chip residue will occur elsewhere.

[0053] Further, the cutting edge 30 of the work tool 10 has a conventional tap point 34 on the side facing away from the shaft 20.

[0054] The work tool 10 according to the invention is characterised in that the dynamic pressure active surface 60 is provided such that the sum of the dynamic pressure forces built up in the area of the dynamic pressure active surface 60 between the cutting head 30 and the inner wall of the recess 2, can radially deflect the shaft 20 in the direction of the cutting blades with cutting edges 31. As already mentioned, a precondition for this is that the amount of fluid fed into the fluid channel 21 is sufficiently large to enable a static flow condition to be established in the area or volume between the cutting head 30, in particular the dynamic pressure active surface 60 of the cutting-blade-free and chip-groove-free surface area 32, and the inner wall of the recess 2 located opposite. A sufficiently large fluid supply is easily achieved using machine-tool technology.

[0055] FIGS. 8 and 9 show a second embodiment of a machining tool according to the invention. The second embodiment is only differentiated from the first embodiment by the form of the dynamic pressure active surface 160. In the second embodiment, the dynamic pressure active surface 160 is formed cross-sectionally, in the direction of the branch channel, as a convex axial groove.

[0056] FIG. 10 shows a third embodiment of a machining tool according to the invention. The third embodiment is differentiated from the first embodiment by the length of the dynamic pressure active surface 260. The dynamic pressure active surface 260 has a flat surface as in the first embodiment, but the axial length of the dynamic pressure active surface 260 in the third embodiment is smaller than the axial length of the cutting head 30. The dynamic pressure active surface 260 ends at an axial distance in front of the face and shaft ends of the cutting head 30. In this way a type of pocket-shaped space is created between the cutting head 30 and the inner wall of the recess 2 which is to be machined. This obstructs the axial outflow of the fluid along the cutting-blade-free and chip-groove-free surface area or the dynamic pressure active surface 260 of the machining tool and raises the dynamic pressure.

[0057] In the embodiments shown in FIGS. 1 to 10, the dynamic pressure active surface 60 is arranged as axially parallel to the longitudinal axis 11 of the machining tool 10. It may however also be arranged at an angle to the longitudinal axis of the machining tool.

[0058] Furthermore, the dynamic pressure active surface may, in contrast to the embodiments shown, have a concave or convex surface.

[0059] It is also possible that a number of variously aligned dynamic pressure active surfaces may be arranged inside the cutting-blade-free and chip-groove-free surface area.

[0060] In contrast to the form of the cutting-blade-free and chip-groove-free surface area shown in FIG. 4, the dynamic pressure active surface may be radially further set back whereby the two cylindrical rotation surface sections decrease in size and the dynamic pressure active surface gets bigger. The dynamic pressure active surface may be set back to the extent that the outer surface of the cutting-blade-free and chip-groove-free surface area consists largely only of the dynamic pressure active surface.

[0061] Furthermore, there may be more or fewer than three cutting blades arranged in the cutting blade section.

[0062] Equally, the machining tool may have more or fewer than two branch channels. The course of the branch channels from the central fluid channel as far as the outlet openings in the cutting-blade-free and chip-groove-free surface area may take fundamentally any form.

[0063] Furthermore, the machining tool may have a number of, for example, parallel fluid channels running in the shaft, which each lead to an associated branch channel.

[0064] The machining tool may, in addition to the tap point facing away from the shaft, have another tap point on the side of the cutting head facing towards the shaft, so that the machining tool may also be used for deburring the inner outlet of a recess, into which the machining tool is inserted.

[0065] Moreover, the manner in which the dynamic pressure active surface is created on the cutting head is immaterial. For example, in the work tool disclosed in DE 103 21 670 A1, a cutting-blade-free and chip-groove-free surface area or a dynamic pressure active surface may simply be created by creating a surface area in an area of the cutting head in which at least one branch channel outlet opening is located, by a grinding or degrading process and in which, in an axial direction and/or a circumferential direction, a limited part of or a number of cutting blades are removed. The cutting-blade-free and chip-groove-free surface area obtained in this way thus has a dynamic pressure active surface in which the outlet opening of the at least one branch channel is located and which has a greater surface area than the flow cross-sectional surface of the at least one branch channel. In this case the outer surface of the cutting-blade-free and chip-groove-free surface area may, in contrast to the design shown in FIG. 4, consist only of a dynamic pressure active surface.

[0066] In the embodiments shown, the machining tool is realised by way of example as a reamer. It may also however be realised as a standing cutting tool, for example as a turning tool or as a cutting tool rotating around a longitudinal axis as a rotation axis, for example as a milling, drilling, in particular deep-hole drilling, straight-grooved drilling or spiral drilling work tool.