Metal cutting machine and machining method

Abstract

In the machining of a stationary workpiece by means of a rotating tool head, the risk of damages to the workpiece by the chips can be minimized and the removal of the chips can be simplified if a chip collector and a stationary nozzle for fluid are respectively provided.

Claims

1. A metal cutting machine featuring a tool head that rotates in a machining area, a stationary workpiece, an externally accessible machine hood that encloses the machining area and features a hood opening for introducing the workpiece into the machining area, a screen for preventing fluid from escaping through the hood opening, and a chip collector that is arranged in the machining area behind the hood opening, wherein the chip collector comprises a collecting surface that is conically tapered decreasing in diameter toward the tool head and/or that is directed radially outwards.

2. The metal cutting machine according to claim 1, wherein a gap between the screen and the workpiece amounts to less than 20 mm.

3. The metal cutting machine according to claim 2, wherein said gap between said screen and said workpiece amounts to less than 15 mm.

4. The metal cutting machine according to claim 1, wherein the collecting surface is arranged rotationally symmetrical relative to a rotational axis of the tool head.

5. The metal cutting machine according to claim 1, wherein the chip collector is hardened.

6. The metal cutting machine according to claim 1, wherein the chip collector is arranged on the screen and/or on the machine hood.

7. The metal cutting machine according to claim 1, wherein the screen comprises a mechanical seal.

8. A metal cutting machine comprising a tool head that rotates in a machining area, a stationary workpiece, an externally accessible machine hood that encloses the machining area, the machine hood featuring a hood opening for introducing the workpiece into the machining area and featuring a front face disposed axially in front of the tool head, a screen for preventing fluid from escaping through the hood opening, the screen being attached to the front face of the machine hood, and a stationary nozzle for liquid or liquid-air-mixture, the stationary nozzle being directed at the workpiece and being arranged in the screen such that the stationary nozzle is axially in front of the tool head.

9. The metal cutting machine according to claim 8, wherein the stationary nozzle comprises a ring nozzle or comprises multiple nozzle outlets and/or wherein the stationary nozzle generates a closed fluid sheath around the workpiece.

10. The metal cutting machine according to claim 8, wherein the nozzle opens into a gap between the screen and the workpiece.

11. The metal cutting machine according to claim 8, wherein the nozzle is directed at the tool head.

12. The metal cutting machine according to claim 7, wherein the screen comprises an elastic seal.

13. A metal cutting machine featuring a tool head that rotates in a machining area, a stationary workpiece, an externally accessible machine hood that encloses the machining area and features a hood opening for introducing the workpiece into the machining area, a screen for preventing fluid from escaping through the hood opening, and a chip collector that is arranged in the machining area behind the hood opening, wherein the chip collector comprises a stripper.

14. The metal cutting machine according to claim 13, wherein said stripper comprises tongs, a gripper, a bow, or a ring able to strip over said chip collector.

15. The metal cutting machine according to claim 13, wherein said chip collector comprises a collecting surface that is conically tapered decreasing in diameter toward the tool head.

16. The metal cutting machine according to claim 15, wherein said stripper comprises tongs, a gripper, a bow, or a ring able to strip over said collecting surface.

17. The metal cutting machine according to claim 15, wherein the collecting surface is arranged rotationally symmetrical referred to a rotational axis of the tool head.

Description

(1) Other advantages, objectives and characteristics of the present invention are elucidated in the following description of exemplary embodiments that are illustrated in the attached drawings. In these drawings:

(2) FIG. 1 shows a schematic section through the rotational axis of a tool head of a metal cutting machine;

(3) FIG. 2 shows an enlarged detail of the arrangement according to FIG. 1;

(4) FIG. 3 shows the arrangement according to FIG. 2 with an axial displacement of the machine hood and the tool head;

(5) FIG. 4 shows the arrangement according to FIGS. 2 and 3 with removed workpiece and axially displaced screen;

(6) FIG. 5 shows the arrangement according to FIGS. 2-4 during the removal of the chips from the chip collector;

(7) FIG. 6 shows a second metal cutting machine in the form of an illustration similar to FIG. 2;

(8) FIG. 7 shows a third metal cutting machine in the form of an illustration similar to FIGS. 2 and 6;

(9) FIG. 3 shows a fourth metal cutting machine in the form of an illustration similar to FIGS. 2, 6 and 7;

(10) FIG. 9 shows a fifth metal cutting machine in the form of an illustration similar to FIGS. 2 and 6-3, however, without tool, head and workpiece; and

(11) FIG. 10 shows a sixth metal cutting machine in the form of an illustration similar to FIGS. 2 and 6-8.

(12) The metal cutting machine 10 illustrated in FIGS. 1-5 comprises a machine housing 54 with a drive for a tool head 14 that revolves about a rotational axis 58. The tool bead 14 carries a tool holder 56 that can be radially (x-axis) adjusted relative to the rotational axis 58 and on which tools 44 are provided.

(13) The metal cutting machine 10 furthermore comprises clamping jaws 52, by means of which a workpiece 16 can be stationarily held relative to the tool head 14, wherein the tool head 14 can be axially (z-axis) displaced relative to the clamping jaws 52, i.e. parallel to the rotational axis 58, in order to axially adjust, the tools 44 relative to the workpiece 16. A not-shown lateral transport is also provided in order to realize the supply and removal of the workpiece 16. If applicable, other units may be provided for the supply and removal in alternative embodiments. It would likewise be conceivable that an axial, adjustment of the tools 44 relative to the workpiece 16 required for the machining process is realised due to an axial motion of the machine housing 54, the tool head 14 and/or the tool holder 56.

(14) The metal cutting machine 10 furthermore features a machine hood 20 with a hood opening 18, wherein the workpiece 16 can protrude into a machining area 12 as far as the tool head 14 through the hood opening 18 in order to be machined, and wherein the machine hood 20 can be axially displaced, i.e. parallel to the rotational axis 58, in order to provide access for maintenance work or for the removal of potential chips 46 or to provide space for processing potential chips 46. It goes without saying that the machine hood 20 may in different embodiments uncover the machining area 12 in a different way, for example in that it is divided and its parts can be respectively pivoted away.

(15) In order to prevent the escape of fluid or other particles from the machining area 12, a screen 22 is provided on the hood opening 18, wherein the screen is composed of two parts in this exemplary embodiment, but this two-part design is merely related to the manufacture of the screen such that additional subassemblies or even a one-piece designs would also be conceivable in different embodiments.

(16) FIG. 2, in particular, shows that a relatively narrow gap 26 is formed between the screen 22 and the workpiece 16, wherein this gap is on the side of the hood opening sealed with a seal 30 that is realized in the form of an elastic ring seal in this exemplary embodiment.

(17) A chip collector 24 is arranged on the screen 22 and in this exemplary embodiment comprises a conical collecting surface 28 that is tapered in the direction of the rotating tool head 14 and arranged rotationally symmetrical referred to the rotational axis 58 of the tool head 14.

(18) A nozzle 32 is furthermore arranged in the screen 22, wherein said nozzle is in this exemplary embodiment realized in the form of a ring nozzle and can be supplied with fluid by means of a fluid channel 34.

(19) In this exemplary embodiment, the fluid pressure in the fluid channel 34 also acts upon the seal 30 in order to close this seal, wherein the seal 30, which is realized in the form of an elastic ring in this exemplary embodiment, basically springs back in the unpressurized state and releases the workpiece 16, but closes tightly under pressure.

(20) It goes without saying that the nozzle 32 may also be provided separately or in other subassemblies in different embodiments.

(21) In this exemplary embodiment, the nozzle 32 is directed at the workpiece, namely angled at the tool head 14, such that fluid can be supplied to she location being machined in the direction of the rotating tool head 14 in the form of a closed fluid sheath that propagates on the surface of the workpiece. At a sufficient fluid pressure, a vacuum is generated toward the seal 30 in the gap 26 and additionally improves the sealing effect.

(22) The chip collector 24, as well as the fluid delivered through the nozzle 32, act upon the chips 46 and keep these chips away from the workpiece 16 and, in particular, from the gap 26. The chips 46 accumulate on the chip collector 24.

(23) The nozzle 32 in the form of a stationary nozzle 32 also comprises stripping nozzles 38 that can be supplied with a fluid by means of a separate stripping fluid channel 40. A supply with another liquid would also be conceivable in different embodiments.

(24) The stripping nozzles 33 are also directed at the workpiece 16 and at the rotating tool head 14, as well as at the chips 46 accumulating on the chip collector 24. In this respect, it would be conceivable that the fluid from the stripping nozzles 38 is also used for influencing the chips 46, particularly for cooling or lubricating the collecting surface 28 of the screen 22.

(25) However, the stripping nozzles 38 are preferably used as strippers 36 in that the machine hood, as well as the machine housing 54 with the tool head 14, is displaced axially parallel to the rotational axis 58 of the cool head 14 as illustrated in FIG. 3 after the machining process is completed such that the workpiece exits the machining area 12 and the machine hood 20 through the hood opening 18.

(26) Subsequently, the machine hood 20 is axially displaced relative to the tool head as illustrated in FIG. 4 such that the machining area 12 is sufficiently accessible and, in particular, sufficient space for removing the chips 46 is provided, wherein the stripping nozzles 38 subsequently eject fluid, the pressure of which suffices for stripping the chips 46 off the chip collector 24 as illustrated in FIG. 5.

(27) The machine hood 20 can subsequently be moved toward the tool head 14 again and the next workpiece 16 can be supplied.

(28) A sufficient vacuum toward the outlet opening 18 can be generated, if applicable, by means of the nozzle 32 due to its entrance angle into the gap 26 between the screen 22 and the workpiece 16 such that the seal 30 can be eliminated and the Bernoulli effect of the nozzle 32 configured in the form of a Bernoulli nozzle 50 can be used as a Bernoulli seal 48 as schematically illustrated in FIG. 6. This represents a particularly simple constructive solution to the sealing problems and also reduces potential wear.

(29) The stripping nozzles 38 are furthermore eliminated in the exemplary embodiment illustrated in FIG. 6, wherein the stripping process is in this exemplary embodiment realized by means of a not-shown manipulator in the form of a robot arm that removes the chips 46 after workpiece 16 has been retracted. The stripper 36 used may likewise consist, for example, of a mechanical stripper 42 of the type illustrated in FIG. 9 and described in greater detail below.

(30) In the exemplary embodiments illustrated in FIGS. 7 and 8, a chip collector was eliminated such that the screen 22 and the machine hood 20 can be moved very close to the tool 14. These embodiments have a particularly space-saving axial construction and therefore make it possible to realize a relatively short unclamping length of the workpiece 16. However, the exemplary embodiment according to FIG. 7 and the exemplary embodiment according to FIG. 8 respectively feature a nozzle 32 that is arranged m the screen 22 and acts upon the stationary workpiece 16 and the tools 14 with fluid.

(31) The nozzle 32 in the exemplary embodiment according to FIG. 7 is directed into the gap 26 between the workpiece 16 and the screen. 22, wherein, the seal 30 ensures that the fluid remains in the machining area 12 and propagates on the surface of the workpiece 16 in the direction of the tool head 14 in the form of a closed fluid sheath, and wherein the fluid is merely used for preventing the chips 46 from, coiling excessively tight on the workpiece 16 and does not have to reach as far as the location being machined because a conventional (not-shown) fluid supply is provided at this location on the tool head 14 by accepting a fluid supply by means of movable subassemblies.

(32) In the exemplary embodiment illustrated in FIG. 8, the nozzle is directed at the tool head 14, wherein the nozzle scatters the fluid so far that the workpiece 16 is also acted upon with fluid. In this case, the fluid sheath extends as far as the location being machined and thereby effectively prevents damages to the workpiece 16 by the chips and, in particular, the penetration, thereof into the gap 26, however, with a correspondingly reduced efficiency with respect to flushing the gap 26.

(33) The mechanical stripper 42 illustrated in FIG. 9 merely consists of a ring that surrounds the collecting surface 28 of the chip collector 24 and can be displaced relative to the chip collector 24 in the axial direction.

(34) In other respects, a stationary nozzle was eliminated in this exemplary embodiment because the chips expected in accordance with the present exemplary embodiment can be sufficiently kept away from the workpiece 16 and from the gap between the workpiece 16 and the screen 22 by the chip collector 24.

(35) In order to strip off the chips 46, the mechanical stripper 42 is moved in the direction of the tool head 14 (illustrated with broken lines) such that the chips 46 are correspondingly displaced and then drop down into the machining area 12.

(36) The arrangement according to FIG. 10, in which a very short collecting surface 28 and a very short chip collector are used, has a particularly space-saving axial construction and requires a correspondingly short unclamping length. In this case, the chips 46 work themselves very tightly into the space between the machine hood 20 and the tool 44, the tool holder 56 and the tool head 14, wherein this may potentially result in increased yet acceptable wear.

(37) In the arrangement according to FIG. 10, the chip collector 24 is furthermore realized on a plate that is not separately identified and forms a wall of the fluid channel 34 on its side facing the machining area 12, as well as a wall of the nozzle 32 on the side of the workpiece. The other wall of these subassemblies is formed by another plate that is not separately identified and also represents the screen 22. Both plates are to one another by means of screws and corresponding spacers (not numbered) such than they can be exchanged in a particularly space-saving and flexible fashion. The fluid supply is realized by means of another separate subassembly (not numbered) that is arranged radially outside of the two plates and to which the arrangement or the two plates is likewise connected by means of a screw connection that is not numbered, wherein this separate subassembly is in turn connected to the machine hood 20. This arrangement not only can be easily realised constructively, but also allows a modular use of the subassembly for supplying the fluid, as well as or the plates and, if applicable, supplementary adapter plates, such that an adaptation to different workpiece diameters or an exchange due to wear can be quickly carried out.

(38) The utilization of plates for realizing the nozzle walls also makes it possible to provide a relatively inexpensive ring nozzle, particularly with suitable working angles relative to the workpiece.

(39) A separate stripper is eliminated in the arrangement according to FIG. 10 because it is assumed that the chips 46 are acted upon by centrifugal forces due to the constant rotation of the tool head 14 and the tool holder 46 and, if applicable, additionally or alternatively acted upon by the fluid, wherein said centrifugal forces suffice for removing the chips from the chip collector 24 when the workpiece is removed and, if applicable, the machine hood 20 is slightly removed from the tool head 14. It goes without saying that such a removal of the chips 46 is also possible in other embodiments or process managements.

LIST OF REFERENCE SYMBOLS

(40) 10 Metal cutting machine 12 Machining area 14 head 16 Workpiece 18 Hood opening 20 Machine hood 22 Screen 24 Chip collector 26 Gap 28 Collecting surface 30 Seal 32 Nozzle 34 Fluid channel 36 Stripper 38 Stripping nozzle 40 Stripping fluid channel 42 Mechanical stripper 44 Tool 46 Chip 48 Bernoulli seal 50 Bernoulli nozzle 52 Clamping jaw 54 Machine housing 56 Tool holder 58 Rotational axis