Machine tool for grinding or gear hobbing

Abstract

Machine tool for machining workpieces (1) comprising a machine frame (2) with a front wall (5), with a workpiece spindle (6), with a machining head (9) with a tool holder (7), with a rotatably driven tool (8), wherein the workpiece (1) and tool (8) are guided linearly relative to each other along two mutually orthogonal axes (X, Z) and can be brought into machining engagement with each other, wherein the machining head (9) is guided on a slide (10) on the front wall (5) of the machine frame (2) on guides (4) axially to the workpiece (1) in the direction of the Z-axis and wherein the machining head (9) is rotatably mounted about a pivot axis (11), wherein the workpiece spindle (6) is fixed in position on the machine frame (2) during the machining of the workpiece (1),wherein the machining head (9) is guided linearly movable relative to the slide (10) along the pivot axis (11) radially to the workpiece (1) in the direction of the X-axis and wherein the tool holder (7) is guided linearly movable on the machining head (9) along an axis orthogonal to the pivot axis (11), wherein a tailstock (22) is assigned to the workpiece spindle (6, 6') and that the tailstock (22) can be fixed to the front wall (5) of the machine frame (2), characterized in that two workpiece spindles (6, 6') are provided, that the two workpiece spindles (6, 6') are arranged on a rotary table (18) and can be moved alternately from a working position (19) to a loading position (20) and vice versa.

Description

[0001] The invention relates to a machine tool for grinding or gear hobbing. A gear hobbing machine is known from EP 0 614 406 B1. This machine has a cuboid machine bed with two traveling columns. The tool column is movable on the machine bed in the X-axis direction and carries guides for the vertical slide with the hobbing head. The hobbing head can be pivoted about the A-axis. In addition to the tool column, the traveling column with the workpiece carrier, consisting of the spindle and tailstock, is movable on the machine frame in the Y-direction. This arrangement allows a shift movement relative to the tool without having to move the hobbing head. However, a disadvantage is the large distance that the power transmission from the tailstock to the tool must overcome. DE 10 2011 082 831 B3 relates to a machine tool for the production of gears.A column and a workpiece with a swivel unit are arranged on the machine bed. A tool head is movable in the three main directions of the machine coordinate system (X, Y, Z) on the frame-shaped column and can also be swivelled about an A-axis. The swivel unit supports two workpiece spindles and their associated tailstocks. The tailstocks are connected via a bearing element, which forms a frame with the swivel unit. The column and workpiece are connected to each other via a crossbeam, also forming a frame. In this machine, too, the path for the power transmission is quite long because it extends over a total of three machine frames. A machine tool for machining workpieces is known from US 20101 0 202 847 A1.

[0002] The object of the present invention is to provide a machine tool according to the preamble of claim 1 with a compact design and improved machine rigidity. This object is achieved with a device having the features of claim 1. Advantageous embodiments are the subject of the dependent claims. According to an advantageous aspect of the invention, the tool performs all the necessary relative movements for machining. This allows the tailstock and workpiece spindle to be fixed in position on the machine frame during machining. This arrangement achieves optimal force flow and enables a space-saving design.

[0003] Fig. Figure 1 shows a schematic side view of a machine tool for grinding or gear hobbing. The machine frame 2 is designed as a column with a square cross-section and has vertical side walls 3, 3' and a similarly vertical front wall 5 with vertical guides 4 for the slide 10. The slide is moved numerically controlled in the Z-axis direction by the motor 23 and the ball screw 24. The machining head 9 is mounted on the slide 10 in a quill housing 13. It can be pivoted about a horizontal pivot axis 11 by a swivel drive 17 and moved linearly in the direction of the pivot axis 11 for feed purposes. A recess 25 is provided in the machine frame 2 into which the quill housing 13 projects. This allows the distance between the machining head 9 and the front wall 5 to remain particularly small and a short, symmetrical force path to be achieved.This is an important prerequisite for high static and dynamic machine rigidity. The machining head 9 carries the tool holder 7 with the tool 8. The workpiece 1 is clamped between a workpiece spindle 6 and a tailstock 22. To clamp workpieces of different lengths, the tailstock 22 is movable on the guides 4 and can be moved by the motor 23' via the ball screw 24'. According to... Fig. To reduce non-productive time, a second workpiece spindle 6' is provided alongside the workpiece spindle 6. The two workpiece spindles 6 and 6' are arranged on a rotary table 18. They are moved from a working position 19 to a loading position 20 and vice versa by pivoting the rotary table 18 about the axis of rotation 26. The partition 21 protects the spindle in the loading position 20 from contamination. The improved machine rigidity resulting from the arrangement of the axes of motion is independent of the machine load and is also achieved with a single-spindle machine.

[0004] Fig. Figure 2 shows the machine tool in a front view. The recess 25 is provided in the center of the machine frame 2, between the two guides 4, into which the quill housing 13, hidden in this view by the slide 10, projects. The symmetrical arrangement has a positive effect on the force flow and the machine rigidity. The tool holder 7 is movable on the machining head 9 and can move the tool 8 along its axis of rotation to perform shift movements.

[0005] Fig.Figure 3 shows a cross-section of the quill housing 13. The quill housing 13 is rigidly connected to the slide 10 and, together with the slide, is movably mounted in the guide shoes 27 on the guides 4. The machining head 9 is rotatably mounted about the pivot axis 11 in the quill housing 13 via the shaft 12. Since the machining head 9 is also guided linearly for infeed, a high-precision hydrostatic bearing 15 is installed in addition to the rolling bearings 14. A ball screw drive is provided for the infeed movement. Its nut 28 is set into rotation by the linear drive 16 and then causes the desired displacement. The rotary drive 17 is directly operatively connected to the shaft 12 without any mechanical intermediate elements. Drives 16 and 17 are designed as torque motors. Their stators are rigidly connected to the quill housing 13, while the rotors are formed by the shaft 12 and the nut 28, respectively. Reference symbol list 1 workpiece 2 machine frames 3 3' Side wall 4 guided tours 5 Front wall 6 6' workpiece spindle 7 tool holders 8 tools 9 Processing head 10 sleds 11 Swivel axis 12 wave 13 quill housings 14 rolling bearings 15 Hydrostatic bearing 16 Linear drive 17 Swivel drive 18 Turntable 19 work positions 20 loading positions 21 Partition wall 22 tailstock 23 23' Engine 24 24' Ball screw 25 Exclusion 26 axis of rotation 27 Guide shoe 28 Mother

Claims

[1] Machine tool for machining workpieces (1) comprising a machine frame (2) with a front wall (5), with a workpiece spindle (6), with a machining head (9) with a tool holder (7), with a rotatably driven tool (8), wherein the workpiece (1) and the tool (8) are guided linearly relative to each other along two mutually orthogonal axes (X, Z) and can be brought into machining engagement with each other, wherein the machining head (9) is guided on a slide (10) on the front wall (5) of the machine frame (2) on guides (4) axially to the workpiece (1) in the direction of the Z-axis and wherein the machining head (9) is rotatably mounted about a pivot axis (11), wherein the workpiece spindle (6) is fixed in position on the machine frame (2) during the machining of the workpiece (1),wherein the machining head (9) is guided linearly movable relative to the slide (10) along the pivot axis (11) radially to the workpiece (1) in the direction of the X-axis and wherein the tool holder (7) is guided linearly movable on the machining head (9) along an axis orthogonal to the pivot axis (11), wherein a tailstock (22) is assigned to the workpiece spindle (6, 6') and that the tailstock (22) can be fixed to the front wall (5) of the machine frame (2), , characterized by , that two workpiece spindles (6, 6') are provided, that the two workpiece spindles (6, 6') are arranged on a rotary table (18) and can be moved alternately from a working position (19) to a loading position (20) and vice versa. [2] Machine tool according to claim 1, characterized by, that the machining head (9) is torsionally rigidly connected to a shaft (12), wherein the shaft (12) is supported in a quill housing (13) arranged on the slide (10) in a combined axial and swivel bearing. [3] Machine tool according to claim 2, characterized by , that a recess (25) is provided on the front wall (5) between the guides (4), into which the quill housing (13) protrudes. [4] Machine tool according to claim 2 or 3, characterized by , that at least one rolling bearing (14) and one hydrostatic bearing (15) are provided for the support of the shaft (12). [5] Machine tool according to claim 2 or 3, characterized by , that the quill housing (13) accommodates both a linear drive (16) for movements along the X-axis and a swivel drive (17) for rotary movements about the swivel axis (11). [6] Machine tool according to any one of claims 1 to 5, characterized by, that the workpiece spindle (6, 6') in the working position (19) is shielded by a partition (21) so that the other workpiece spindle (6, 6') can be loaded in the loading position (20) in parallel with the main time. [7] Machine tool according to one of claims 1 to 6 with vertical workpiece spindle (6, 6'), characterized by , that the workpiece spindle (6, 6') is arranged vertically. [8] Machine tool according to any one of claims 1 to 7, characterized by , that the driven tool (8) is a grinding or gear hobbing tool.

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