MACHINE TOOL WITH CONTROLLED CHIP REMOVAL

Description

[0001] The invention relates to a machine tool with a workpiece and a tool for machining the workpiece.

[0002] Machine tools allow workpieces to be finished automatically in multiple processing steps and with different tools. However, various factors, such as machining within a closed, usually narrow space within the machine tool or the manufacturing technology used, can lead to unfavorable chip flow. For example, chips can become jammed and / or stuck to the workpiece, they can wrap around the tool, especially long, thin chips, or uncontrolled chip evacuation.

[0003] This results in the chips damaging the surfaces already machined or the machining process having to be interrupted in order to remove the chips from the workpieces or tools before subsequent machining, which on the one hand entails increased personnel expenditure for manual removal and thus high costs and on the other hand entails a risk of injury to people and damage to the workpiece when removing the chips, with no guarantee that all chips have been removed or moved to a disturbance-free area.

[0004] The problem of uncontrolled chip evacuation is of great importance for workpieces that have stringent manufacturing tolerance requirements. In particular, if a workpiece must be finished in only one clamping position due to the required manufacturing tolerance, i.e., without re-clamping, further restrictions arise, for example, regarding the clamping surface to be used on the workpiece or the geometry of a clamping mechanism for the workpiece, which can further impair or even negatively influence chip evacuation.

[0005] DE 10 2018 126 437 A1 discloses a system with a machine tool and a cleaning station for cleaning components by means of rotating brushes.

[0006] DE 10 2006 022 588 A1 discloses a cleaning of spindles of a machine tool by means of counter-rotating brushes.

[0007] WO 2020 / 083440 A1 discloses a machine tool according to the preamble of claim 1.

[0008] It is therefore the object of the invention to provide a machine tool with which a high-precision machining of workpieces can be carried out and at the same time the chip removal can be controlled in each application, in particular without adverse effects on the machining accuracy, machining costs or machining time.

[0009] The object of the invention is achieved by a machine tool having the features of claim 1. Advantageous further developments are the subject of the subclaims.

[0010] In particular, the object of the invention is achieved according to a first aspect in that the machine tool has a chip removal device formed by two brushes with approximately parallel longitudinal brush axes. The brushes can be driven in a counter-rotating rotational movement about their longitudinal brush axes, which are arranged spaced apart by a gap. The longitudinal brush axes are the rotational axes. The counter-rotating movement of the two brushes allows a stripping mechanism to be implemented in a particularly simple manner, by which adhering chips can be removed automatically, efficiently, and without potential damage or hazard.

[0011] According to the invention, the machine tool comprises a workpiece clamping device for holding the workpiece to be machined and a tool clamping device for holding the tool. The workpiece clamping device and the tool clamping device are displaceable relative to the chip removal device within the machine tool such that the workpiece and the tool can be inserted into the gap of the chip removal device. This means that the workpiece and the tool can be immersed in a space between the brushes, so that the brushes slide / rotate along a surface of the workpiece or the tool, respectively, and thereby free the workpiece or the tool of chips.

[0012] In particular, chip removal takes place directly within the machine tool, so that after chip removal has been completed, the workpiece can be further processed directly within the machine tool.

[0013] According to a preferred embodiment, the size of the gap between the brush longitudinal axes can be adjustable. This means that the distance between the brush longitudinal axes can be increased or decreased depending on the dimensions of the workpiece and / or tool to ensure that the brushes can come into contact with the surface regardless of the dimensions of the workpiece and / or tool.

[0014] According to a preferred development, the brush longitudinal axes can be aligned horizontally of the machine tool and / or perpendicular to a longitudinal axis of the tool and / or the workpiece. This has the advantage that plunging the tool and / or the workpiece can be implemented particularly easily, since the longitudinal axis of the tool and / or the workpiece is usually aligned vertically.

[0015] According to a preferred development, the brushes can be arranged and driven in opposite directions to one another such that the gap between the brush longitudinal axes produces a direction of action in the direction of gravity of the machine tool, i.e., downwards. This means that the bristles of the brushes directed toward one another rotate downwards, and the bristles of the brushes directed away from one another rotate upwards. This ensures that the chips scraped off by the tool and / or workpiece entering the gap between the brushes can be transported downwards and thus into a disturbance-free area.

[0016] According to a preferred embodiment, the machine tool can have a chip collection container arranged below the chip removal device in the direction of gravity, so that the stripped chips can be collected directly and are not distributed uncontrollably throughout the machine tool. This also facilitates chip removal.

[0017] In other words, according to a first aspect, the invention relates to a machine tool having fully adjustable and adaptable, counter-rotating brushes, between which a gap is formed. The workpieces and tools can be automatically guided / pulled through the resulting gap between the brushes, thereby sweeping away any adhered or jammed chips. Depending on their intended use, the brushes are compactly constructed, fully automatable, and can also be integrated into existing processes because they are fully adjustable and adaptable. By providing the brushes, the manual, cost-intensive removal of adhered and jammed chips can be eliminated, while simultaneously ensuring 100% part and tool cleanliness.

[0018] Furthermore, the object of the invention is achieved according to a second aspect, which can be present in combination with the features of the first aspect, in that the machine tool has a workpiece clamping device designed as a collet, in which the workpiece can be clamped such that a section of the workpiece to be machined lies radially within the collet, wherein the workpiece and the tool for machining the section of the workpiece to be machined can be driven in rotation simultaneously about their respective longitudinal axes. The section of the workpiece to be machined or the required machining of the section of the workpiece to be machined is, in particular, rotationally symmetrical.This means that, particularly in a machining process where the section of the workpiece to be machined is difficult to access due to external circumstances, such as the inability to change the clamping position due to manufacturing tolerances or the required tool geometry, the problem of chip removal is exacerbated, as the chips can become trapped in the collet or tool and cannot be removed. Because both the tool and the workpiece rotate simultaneously during machining, a milling process is combined with a turning process, resulting in a particularly short flowing chip that can be flushed through the collet and removed to a disturbance-free zone despite the limited space available for the section of the workpiece to be machined.

[0019] According to a preferred development, the tool can be designed as a milling tool whose longitudinal axis is parallel to the longitudinal axis of the workpiece, wherein the machine tool is designed such that the milling tool rotates about its longitudinal axis within the collet to machine the section of the workpiece to be machined and revolves about the longitudinal axis of the workpiece or only rotates about its longitudinal axis. Because the workpiece already rotates about its longitudinal axis, the milling tool can only be rotated about its longitudinal axis to machine the section of the workpiece to be machined. Alternatively, it can be advantageous if the milling tool also rotates about the longitudinal axis of the workpiece, so that the speed of the workpiece is not the sole determining factor for manufacturing accuracy.

[0020] According to a preferred development, the milling tool can have several axially spaced cutting edges of different outer diameters on its outer circumference, which are simultaneously in machining engagement with the workpiece for machining. This means that the milling tool has a corncob-like outer shape, which allows grooves of varying depths to be created in the workpiece. The axial spacing of the cutting edges further supports chip removal, as short chips are produced.

[0021] In other words, according to a second aspect, the invention relates to a machine tool in which both the tool geometry and the workpiece are rotatably driven, creating a short flowing chip that can be flushed through the collet chuck and removed into a disturbance-free zone. This has the advantage of enabling precise pre- and finish machining, advantageously designing chip flow, reducing tool costs, increasing machine productivity, and reducing scrap costs. Furthermore, unit costs can be reduced.

[0022] Furthermore, the object of the invention is achieved according to a third aspect, which can be present in combination with the features of the first and / or the second aspect, in that the machine tool has a tool holder and two grooving tools, wherein the grooving tools are received in the tool holder in such a way that they are arranged on opposite sides of the workpiece in the circumferential direction, and the machine tool is designed such that the workpiece is machined simultaneously by the two grooving tools for rotationally symmetrical machining, in particular for creating a rotationally symmetrical groove. This means that instead of turning, which usually produces long and thin chips, the workpiece is machined simultaneously by two grooving tools, which ensure that the chip generated by the other grooving tool is separated.In addition, mechanical stability can be improved due to reduced vibrations. According to a preferred embodiment, the longitudinal axes of the grooving tools can lie in a radial plane of the workpiece, in particular in a substantially common radial plane.

[0023] According to a preferred embodiment, the two grooving tools can have a cutting edge with identical or different geometries. Different tools allow different areas of the workpiece to be machined simultaneously, which has a beneficial effect on the overall machining time. With identical tools, one area can be machined simultaneously with both tools, thus shortening the machining time for one area and reducing tool wear. Thus, although twice as many tools are required overall, they can be used for a correspondingly longer period, so that no disadvantages arise.

[0024] In other words, according to a third aspect, the invention relates to a machine tool in which a special tool and a tool holder, adapted to the machine conditions, provide optimal chip flow so that the chips do not wrap around the components and cause machine malfunctions. In particular, in the so-called horn-head application, a short, solid, and wide chip is created that is discharged into a malfunction-neutral zone by using the grooving application in combination with the newly developed tool holder and optimized flushing, taking the machine conditions into account. This has the advantage of generating advantageous chips, reducing tool costs, increasing machine output, and reducing scrap costs. Furthermore, unit costs can be reduced.

[0025] Furthermore, the object of the invention is achieved according to a fourth aspect, which can be present in combination with the features of the first, the second and / or the third aspect, in that an inner diameter of the workpiece to be machined is constructed in sections from different materials and the machine tool has a reamer whose outer diameter is matched to a target diameter of the inner diameter to be machined, wherein the machine tool is designed such that the inner diameter to be machined is finish-machined by the reamer in a single machining step, preferably with a constant machining feed and a constant machining speed.This means that the inner diameter is not created by turning, as otherwise waves and bulges would form due to the different hardness of the materials, but a reamer is used whose outer diameter is already matched to the target diameter of the inner diameter to be machined.

[0026] In other words, according to a fourth aspect, the invention relates to a machine tool in which a functionally relevant inner diameter of an assembly to be manufactured, in particular from three materials with different hardnesses, has to be produced in one clamping and one machining direction due to the required manufacturing tolerances, for which purpose a reaming process with a specially designed reamer was developed in order to, on the one hand, maintain the cylindricity and diameter tolerance and, on the other hand, to influence the chips in a targeted manner during formation and removal.In contrast to turning, where part quality cannot be guaranteed due to inaccurate machining, particularly fluctuating diameters and lack of cylindricity, resulting in high scrap rates and requiring automated 100% inspection in the subsequent process, and where chips are generated in the area of ​​the inner diameter due to manufacturing processes, the specially designed reamer can increase the accuracy of the component contour and reliably ensure chip removal during machining by using the reaming application in combination with the newly developed reamer with optimized chip flow. This has the advantage of generating advantageous chips, enabling precise pre- and finish-machining, implementing process-capable production, increasing machine output, reducing scrap costs, and eliminating the need for 100% inspection. Furthermore, unit costs can be reduced.

[0027] The invention is explained below with the aid of drawings. They show: Figs. 1 to 3 various representations of a chip removal device of a machine tool, Figs. 4 to 7 various representations of the machine tool in which a workpiece is held in a collet, Figs. 8 and 9 various representations of the machine tool with a tool holder and two grooving tools, and Figs. 10 and 11 various representations of a machining process by the machine tool, in which an inner diameter of the workpiece to be machined is constructed in sections from different materials.

[0028] The drawings are merely schematic in nature and serve to clarify the invention. Identical elements are designated by the same reference numerals. Features of different embodiments can be combined in any way.

[0029] The invention relates to a machine tool which has at least one workpiece 1 and at least one tool 2 for machining the workpiece 1.

[0030] Figs. 1 to 3 show a chip removal device 3 of the machine tool according to the invention. The chip removal device 3 has two axially parallel brushes 4, which can be driven in a counter-rotating rotational movement about their longitudinal brush axes, which are arranged spaced apart by a gap.

[0031] Furthermore, the machine tool can have a workpiece clamping device (not explicitly shown) for holding the workpiece 1 to be machined. The workpiece clamping device can be displaced relative to the chip removal device 3 within the machine tool such that the workpiece 1 can be inserted into the gap of the chip removal device 3. This means that the workpiece 1 can be immersed, in particular from above, between the brushes 4 in order to be able to strip off chips adhering to the workpiece 1 as the brushes 4 rotate.

[0032] In addition, the machine tool may have a tool clamping device (not explicitly shown) for receiving the tool 2. The tool clamping device is displaceable within the machine tool relative to the chip removal device 3 such that the tool 2 can be inserted into the gap of the chip removal device 3. This means that the tool 2 can be inserted, in particular from above, between the brushes 4 in order to be able to strip off chips adhering to the tool 2 as the brushes 4 rotate.

[0033] Preferably, the brush longitudinal axes can be aligned in a horizontal direction of the machine tool and / or perpendicular to a longitudinal axis of the tool 1 and / or the workpiece 2. Since the longitudinal axes of the tool 2 and / or the workpiece 1 are usually aligned in the vertical direction / direction of gravity, the tool 2 and / or the workpiece 1 can be particularly easily immersed between the brushes 4.

[0034] The tension-relieving device 3 can, in particular, be designed such that the size of the gap between the brush longitudinal axes is adjustable. In the illustrated figures, the tension-relieving device 3 has two rotary knobs 5, the rotation of which allows the brush longitudinal axes to be displaced to correspondingly increase or decrease the gap between the brushes 4. Preferably, the brush longitudinal axes can be spaced apart sufficiently so that the brushes 4 touch or slightly overlap.

[0035] Furthermore, the brushes 4 of the chip removal device 3 can preferably be arranged and driven in rotation in opposite directions to one another such that an effective direction in the direction of gravity of the machine tool results in the gap between the brush longitudinal axes. This means that the brushes 4 are preferably driven such that bristles of the brushes 4 move downward on their facing sides, i.e., downwards in the vertical direction, so that the chips are conveyed downwards during stripping. The chip removal device 1 can preferably have a chip collecting container 6, which is arranged below the brushes 4 in the direction of gravity, so that the stripped chips are collected directly in the chip collecting container 6.

[0036] Figs. 4 to 7show the machine tool in which the workpiece 1 is held in a workpiece clamping device designed as a collet 7. The workpiece 1 is clamped in the collet 7 such that a section 8 of the workpiece 1 to be machined lies radially within the collet 7. To prevent chips from becoming trapped in the collet 7, the workpiece 1 and the tool 2 for machining the section 8 of the workpiece 1 to be machined can be driven in rotation simultaneously about their respective longitudinal axes. This means that the machine tool is designed such that the workpiece 1 can be machined by turn-milling.

[0037] Fig. 5shows the tool 2, which is designed as a milling tool 9. A longitudinal axis of the milling tool 9 is aligned parallel to the longitudinal axis of the workpiece 1. The machine tool can be designed such that the milling tool 9 rotates about its longitudinal axis within the collet 7 for machining the section 8 of the workpiece 1 to be machined, as well as revolves about the longitudinal axis of the workpiece 1, or only rotates about its longitudinal axis. The milling tool 9 has on its outer circumference a plurality of axially spaced cutting edges 10 of different outer diameters, which are simultaneously in machining engagement with the workpiece 1 for machining. As a result, grooves 11 of varying depths can be introduced into the workpiece 1 using the milling tool 9, which has a corncob-like outer shape (cf. Fig. 6 ).

[0038] Figs. 8 and 9show a tool holder 12 and two grooving tools 13, 14 of the machine tool. The grooving tools 13, 14 are accommodated in the tool holder 12 such that they can be arranged on circumferentially opposite sides of the workpiece 1. Furthermore, the machine tool is designed such that the workpiece 1 can be machined simultaneously by the two grooving tools 13, 14 for rotationally symmetrical machining, in particular for creating a rotationally symmetrical groove. Simultaneous grooving allows for the production of particularly short chips, since a chip produced by the first grooving tool 13 is separated by the second grooving tool 14. Fig. 9Possible machining surfaces 15 of the workpiece 1 are shown, which can be machined with the two grooving tools 13, 14. The two grooving tools 13, 14 can have a cutting edge with identical geometry or with different geometries in order to machine the possible machining surfaces 15 as efficiently as possible.

[0039] Figs. 10 and 11show a machining operation by the machine tool in which an inner diameter of the workpiece 1 to be machined is constructed in sections from different materials, in particular materials of different hardness. In particular, the workpiece 1 has a first inner diameter section 16 which has a first material hardness, and a second inner diameter section 17 which has a second material hardness that is higher than the first material hardness. The two inner diameter sections 16, 17 are connected to one another via a weld seam 18 which has a third material hardness that is higher than the first material hardness and the second material hardness. Since the inner diameter of the workpiece 1 to be machined is functionally relevant, it is crucial for production reasons that the inner diameter is machined in a single machining step, in particular with the same tool feed and the same tool speed.The machine tool comprises the tool configured as a reamer 19, the outer diameter of which is matched to a target diameter of the inner diameter to be machined. Thus, the machine tool can be configured such that the inner diameter to be machined is finished by the reamer 19 in a single machining step, resulting in high machining accuracy despite the different material hardnesses.

Claims

1. Machine tool, having a workpiece (1) and a tool (2) for machining the workpiece (1), the machine tool having a chip removal device (3) which is formed by two brushes (4) having parallel longitudinal brush axes, the brushes (4) being counter-rotationally movable about their longitudinal axes, which are arranged at a distance from one another via a gap, the machine tool having a workpiece clamping device for holding the workpiece (1) to be machined and a tool clamping device for holding the tool (2), characterized in that the workpiece clamping device and the tool clamping device can be displaced relative to the chip removal device (3) within the machine tool in such a way that the workpiece (1) and the tool (2) can be introduced into the gap of the chip removal device (3).

2. Machine tool according to claim 1, characterized in that a size of the gap between the longitudinal axes of the brushes is adjustable.

3. Machine tool according to one of claims 1 to 2, characterized in that the longitudinal axes of the brushes are aligned in a horizontal direction of the machine tool and / or perpendicular to a longitudinal axis of the workpiece (1) and / or of the tool (2).

4. Machine tool according to one of the claims 1 to 3, characterized in that the brushes (4) are arranged and are rotationally movable in opposite directions to one another in such a way that, in the gap between the longitudinal axes of the brushes, the direction of action is in the direction of the force of gravity of the machine tool.

5. Machine tool according to one of claims 1 to 4, characterized in that the machine tool has a workpiece clamping device designed as a collet chuck (7), in which the workpiece (1) can be clamped in such a way that a section (8) of the workpiece (1) to be machined lies radially within the collet chuck (7), wherein the workpiece (1) and the tool (2) can be driven in rotation simultaneously about their respective longitudinal axes in order to machine the section (8) of the workpiece (1) to be machined.

6. Machine tool according to claim 5, characterized in that the tool (2) is configured as a milling tool (9), the longitudinal axis of which is axially parallel to the longitudinal axis of the workpiece (1), wherein the machine tool is configured in such a way that the milling tool (9) for machining the section (8) of the workpiece (1) to be machined rotates about its longitudinal axis within the collet chuck (7) and also revolves about the longitudinal axis of the workpiece (1) or only rotates about its longitudinal axis.

7. Machine tool according to one of the claims 1 to 6, characterized in that the machine tool has a tool holder (12) and two infeed tools (2, 13, 14), the infeed tools (13, 14) being accommodated in the tool holder (12) in such a way that they are arranged on sides of the workpiece (1) that are opposite in the peripheral direction, and the machine tool is designed in such a way that the workpiece (1) is machined simultaneously by the two infeed tools (13, 14) for rotationally symmetrical machining.

8. Machine tool according to claim 7, characterized in that the two infeed tools (13, 14) have a cutting edge with an identical geometry or with a different geometry.

9. Machine tool according to one of the claims 1 to 8, characterized in that an inside diameter of the workpiece (1) to be machined is constructed in sections from different materials and the machine tool is a reamer (2, 19) whose outside diameter is matched to a target diameter of the internal diameter to be machined, the machine tool being designed in such a way that the internal diameter to be machined is finishmachined by the reamer (2, 19) in a single machining step.