EP1907168A1

EP1907168A1 - Machine tool with two clamp points on separate carriages

Info

Publication number: EP1907168A1
Application number: EP06721959A
Authority: EP
Inventors: Lukas Betschon; Christian Glaus
Original assignee: STARRAGHECKERT AG
Current assignee: STARRAGHECKERT AG
Priority date: 2005-05-16
Filing date: 2006-05-15
Publication date: 2008-04-09
Also published as: CN101193727A; WO2006122440A1; JP2008540145A; DE202006020904U1; US20080213057A1; KR20080018166A

Abstract

The invention relates to a machine tool for milling workpieces, provided with at least two linear displacement axes and at least one pivot axis for carrying out relative movements between a tool and the corresponding workpiece with a workpiece mounting in which a workpiece may be clamped between two clamping points, whereby one of the linear displacement axes is provided as workpiece axis of the workpiece mounting, by means of which the workpiece may be linearly driven, which is furthermore provided with a tool holder for mounting a cutting machining tool, driven in rotation about a tool axis by means of a tool drive. The same conditions are achieved for workpieces of greatly different length for a highly accurate production, whereby two physically separate carriages (27, 28) for the workpiece mounting are provided, on each of which one of the clamping points (16, 17) is arranged and which both may be linearly driven along the same workpiece axis independently of each other.

Description

TOOLING MACHINE WITH TWO CHANNELS ON SEPARATE SLICES

machine tool

The invention relates to a machine tool for milling workpieces, which is provided with a tool carrier for receiving a chip-removing and rotationally driven machining tool having a workpiece holder in which a workpiece is clamped between two clamping points, wherein the machine tool has a plurality of driven axes of movement Movement axes are provided to produce individually or in combination with each other Bearbeitungsvorschubbewegungen as Reiativbewegung the machining tool with respect to the workpiece during machining of the tool on the workpiece, wherein the tool carrier with at least one linear axis of movement of the driven axes of movement and the workpiece holder with at least two physically separated Carriage is provided on each of which one of the clamping points is arranged, the two carriages of the workpiece holder together along at least one driven linear movement axis are movable.

For milling workpieces, such machine tools are used, in which the workpiece and the milling tool perform relative pivoting movements about at least one axis, as well as relative linear movements along at least two axes. These are movement axes with which feed movements are generated and are to be distinguished from those axes with which pure cutting movements are generated, as is the case, for example, for the rotational movement of the workpiece during a turning operation or for the rotational movement of the tool during a milling operation. In particular, movement axes are to be distinguished therefrom, with which simple advancing movements of the tool or workpiece can be carried out, for example, to pick up the workpiece or to transfer it to a specific position. Movement axes for purely infeed movements are not actuated during the machining of a workpiece. Depending on the complexity of the required machining operations, a larger number of feed motion axes may also be present. Thus, for the production of workpieces with complex geometric shape, such as blades or Blisks of turbines and compressors, in at least one clamping at least three linear and two rotary feed axes advantageous.

Especially with elongated workpieces, such as turbine blades or - blades, these are often clamped between two clamping points to avoid bends and the resulting large manufacturing inaccuracies. In a conventional solution for such workpieces a clamping point on a longitudinally movable carriage is arranged stationary, while a second clamping point is longitudinally movable only for the clamping operation. The length of this longitudinal movement and the size of the entire carriage must be designed on the basis of the longest machinable workpiece on the corresponding machine tool. However, this has the disadvantage that, especially for shorter workpieces on the carriage a strong one-sided load of the bearing of the carriage is present, which can lead to manufacturing inaccuracies.

From WO 03/064089 A1, a milling machine is already known, in which three linear feed motion axes and a pivot axis are placed in the tool. The workpiece holder designed as a round station with two separate slides is provided with a linear feed movement axis. The two carriages, between which a workpiece is to be clamped, can be moved independently of one another along their movement axis. It is also provided in the machine tool, a second workpiece holder to which the workpiece is to be transferred automatically. In order to record the workpiece, the second workpiece holder should be movable in different directions. As a feed movement, the carriages of the second workpiece holder carry out movements parallel to the feed axis of the first workpiece holder. This conceptual design of the machine tool makes it difficult to achieve good machine rigidity. In addition, the accessibility of the workpiece is despite The mobility of the two slides each workpiece holder limited in the X direction. In particular, the fact that a second workpiece holder is present can be detrimental to the accessibility to the workpiece during its processing.

The invention is therefore an object of the invention to provide a machine tool of the type mentioned above with a workpiece holder with more favorable properties, in particular a more variable workpiece holder, in which equally good conditions for a high manufacturing accuracy are available even for very different lengths of workpieces. Despite these properties, prerequisites for machine tools according to the invention should as far as possible also be present for the machine tool to have a high degree of rigidity against deformation.

This object is achieved in a machine tool of the aforementioned type according to the invention that is provided by the two carriages of the workpiece holder at least one with a second linear axis of movement for executing machining feed movements.

The preferably associated with the two slides linear motion guides for machining feed movements should preferably be aligned in pairs parallel to each other se i n. D i e movement axes of these linear motion guides can advantageously on the one hand parallel to a Längsbzw. Clamping axis of the workpiece and on the other hand be aligned transversely thereto to allow both clamping points or slide the workpiece holder driven machining feed movements in two mutually perpendicular directions. Since two linear axes of motion are thus placed in the workpiece in such embodiments, such machine tools can be made particularly compact and rigid despite the functionality according to the invention.

The ^" inventive solution can also be ensured that due to the clamping of the workpiece, the linear motion guides both Clamping points are exposed to substantially the same static loads. Also at the by the. Machining resulting dynamic loads can hereby achieve a more even distribution of the bearings. In addition, it is advantageous in the solution according to the invention that all workpiece lengths can be machined from extremely short workpieces to workpieces whose length corresponds to the length of the workpiece axis under always identical favorable conditions. Finally, the invention also enables a compensation of geometric inaccuracies of the base frame by means of the control, whereby the manufacturing accuracy can be further improved.

A particular rigid machine design, which has the advantages of the inventive machine concept, can be achieved if the tool carrier is not assigned more than two linear axes of movement. In preferred embodiments of the invention, the tool carrier is therefore movable in only two and the workpiece holder in likewise only two linear machining feed axes. In contrast to WO 03/064089 A1, for example, despite the at least four linear axes of movement, both the tool carrier and the workpiece holder have the smallest possible number of linear axes of movement, which leads to high manufacturing accuracy of machine tools according to the invention.

At least the movements of the two clamping points along a movement feed axis, preferably in both movement feed axes, should be synchronized with each other. Such a synchronization can preferably be carried out with a hardware-based software-based control as part of the control ^' . The mechanically separated traversability of the two clamping points or .. slide along the same axis can be achieved with very little design effort, if both carriages are arranged on the same rails of the purpose provided linear motion guides. In order to achieve a secure and stable arrangement of a workpiece between the two clamping points of the workpiece holder, for the synchronous movement of the two clamping points detectors for determining momentary Positions of both clamping points be present. Their signals should be fed to a controller. Due to the detection signals, the controller can make a comparison between the setpoint and actual positions of the two carriages or the speed of the two synchronously moving carriages. For this purpose, the controller may also contain one or more control loops.

Special significance of the invention in connection with machine tools whose tool carrier is pivotable about a pivot axis, wherein the pivot axis preferably includes an acute angle with the tool axis of the clamped tool. Furthermore, in suitable developments, the pivot axis and the tool axis should intersect, at least pass very close to one another, wherein the point of intersection or the point with the smallest distance should be in the region of the tool tip. With such a solution, even without complex compensation movements along one or more translatory axes pivoting movements of the tool carrier are possible, in which the tool tip maintains its position despite the pivoting movement. In addition, in this case the torque load of the rotation axis is minimized as a result of cutting forces. Such pivotal movements can therefore be used for alignment or tracking of the tool, with which a good surface quality and accuracy can be achieved, even if the workpiece to be produced has a complicated contour.

A machine tool according to the invention may further comprise a round station, from the two clamping points of the workpiece can be added and offset during the processing of the workpiece latter in rotational movements, which is provided as a machining feed movement or as a component of the feed movement of the workpiece relative to the milling tool. Preferably, the round station can perform endless rotational movements. In connection with such machine tools, as already described in EP 0 659 520 B1, a large number of additional advantages arise in connection with the separate and multiaxial movability of the preferably two clamping points according to the invention. These exist for example, in the possible reduction of the moving masses, especially because the round station can turn out slimmer. The short processing times, which are anyway possible with this machine concept, can be further reduced despite the high machining accuracy due to the low masses to be moved. The chip flow as well as the accessibility for a workpiece exchange or an end machining of the workpiece is improved by the use of the invention in such a machine tool concept. The content of EP 0 659 520 B1 is therefore fully incorporated by reference in particular with regard to the basic construction and the mode of operation of such machine tools.

Further preferred embodiments of the invention will become apparent from the claims, the description and the drawings. Although individual features of the invention are shown here only in combination with other features, they also have independent significance.

The invention will be explained in more detail with reference to embodiments shown purely schematically in the figures, in which:

1 shows a perspective view of a machine tool according to the invention;

2 is a side view of the machine tool of FIG. 1.

The machine tool shown in highly schematic form in FIG. 1 is provided with a machine frame 1, on the upper side of which a first slide 2 is arranged. The carriage 2 is movable in the X direction of a Cartesian coordinate system. The mobility of the carriage 2 is achieved by two mutually parallel linear motion guides, in which a plurality of carriages 3, 4 are arranged on linear motion rails 5. In the figures, only one of the rails 5 can be seen from this. Such linear motion guides, in which circulate in the carriage 3, 4 rolling elements in circulation channels are many previously known. In the present case, the carriages 3, 4 are fixedly mounted on the machine frame 1, while the rails 5 are mounted on the movable carriage 2.

The carriage 2 is provided with an inclined surface 6, on which a tool slide 7 is arranged. By means of two not shown further linear motion guides the tool carriage 7 is movable on this surface 6 in the X and Z directions.

On the tool carriage 7, a tool carrier 8 is mounted, in which a milling tool 9 is received and a machining axis 10 by a

Tool drive 1 1 can be set in rotation. By the

Rotational movement may be that required for machining

Cutting speed are generated. The tool holder 8 is here on

Tool carriage 7 pivotally mounted about a driven pivot axis 14. The pivot axis 14 in this case intersects the axis of rotation (machining axis 10) of the tool 9 in the tool tip. The pivoting movements can be performed during the machining of a workpiece, in particular during an existing engagement of the respective tool 9 in a (not shown in the figures) workpiece.

On a front side of the machine frame 1 is a round station as a workpiece holder

15, which is provided with two clamping points 16, 17, between which a workpiece can be clamped. The round station 15 is provided with a rotary drive 16a, 17a, with which the respective workpiece is rotatable about a clamping axis 18.

The rotary drive 16a, 17a of the round station 15 can, for example, the clamping point

Be assigned 16 to enable their workpiece holder in rotational movements. Preferably, both clamping points 16, 17 each have their own rotary drive 16a, 17a. Each of the clamping parts 16, 17 is arranged on a clamping point carrier 19, 20, which is movable parallel to the Z-axis via two parallel linear movement guides. The two clamping plate supports 19, 20 are each provided with a separate drive (not shown), with which mutually independent translational movements of the clamping plate carriers can be performed. This may be important especially if a workpiece is held only by one of the clamping point 16, 17. If both clamping points 16, 17 simultaneously used for receiving a workpiece, the movements of the two clamping plate support 19, 20 should be synchronized with each other, for example by means of suitable sensors, with the positions of the two clamping points 16, 17 along the Z-axis constantly determined , compared and, if necessary, aligned with each other.

For this purpose, at least one linear motion guide of each of the two clamping points 16, 17 a glass scale with optical read head (both not shown) may be provided which determines an absolute position of the respective clamping point 16, 17 with respect to a reference point. For this purpose, suitable glass scales are, for example, offered by the company. Heidenhein (for example, the product

LC181). The signals of the read heads are supplied to an electronic control of the machine tools, not shown in detail, compared with it and optionally by switching on one or both drives of the two

Clamping points 16, 17 matched. For this purpose, a control loop may be provided which performs a readjustment until, taking into account a predetermined tolerance, both clamping points either have a predetermined distance and speed or are predetermined at the clamping point for each clamping point

Z position.

The rails 23, 24, 25, 26 of the linear motion guide for the Z-axis of each of the two clamping plate supports 19, 20 are in turn respectively on top of a respective clamping plate carrier 19, 20 associated carriage 27, 28 are arranged. In both carriages 27, 28 are located on the underside of other linear motion guides, with which the carriage 27, 28 synchronously or independently translatable in the Y direction. For this purpose, the Y-axis of the machine tool has two rails 29, 30, which are connected to the machine frame, of motion guides. Carriage 31, 32; 33, 34, 35, 36 of this Ünearbewegungsführungen are attached to the carriage, with carriage 31, 32; 33, 34, 35, 36 of both carriages 27, 28 are arranged on the same rails 29, 30. Because of this structural design and the resulting mobility of the clamping plate carrier 19, 20 in the Y and in the Z direction, the clamping plate carriers are each a cross slide.

All of the carriages shown here may be provided with commercially available servomotors, not shown in more detail (for example, the type 1 FT6084-1AF71 offered by Siemens), the rotational movement of each of which is converted into a translational movement via a belt drive and a ball screw. Alternatively, linear direct drives can also be used, for example similar to the type 1 FN3600-4WC00-0AA0 also offered by Siemens.

Also, the movements of the carriage 27, 28 along the Y-axis may preferably be synchronized with each other. As with the 2-axis suitable detectors (for example, optical, magnetic or inductive detectors) for determining the position of both slides 27, 28 may be present for this purpose. The signals of the detectors are supplied to the control of the machine tool, with which a regulation of the movements or positions of the carriage is executable.

The inventive machine tool is predestined for the machining of elongated workpieces with complicated geometric shapes, such as

Blades of turbines or compressors. In particular, such

Clamp the workpiece are the two clamping points 16, 17 first on the Y-

Axis moved by means of the carriage with a Y-distance apart, which is greater than the length of the workpiece. Thereafter, the workpiece can be clamped in a collet, which is located in one of the rotatably driven clamping points 16, 17. Subsequently, the two clamping points in the Y direction to each other to be moved until, for example, a centering tip of the other clamping point 16, 17 is located in a center hole of the workpiece.

The thus clamped along the clamping axis 18 workpiece can be delivered to the tool via the driven workpiece side Y and Z axes. During machining, feed motions can be generated with these axes. The same applies to the possible rotation of the workpiece in the round station around the parallel to the Y-axis clamping axis. The tool can be moved for feed and / or for feed movements with the carriage in the X-axis and with the axis of the tool carriage 7 simultaneously in the X and Z directions. In addition, the tool is pivotable by means of its tool carrier 8 about the pivot axis 14 of the tool carriage 7 for pivotal movements. Due to the described alignment of the pivot axis 14 and the pivoting of the tool 9 about this axis, the tool 9 describes in these pivotal movements a path corresponding to a portion of a lateral surface of a cone, wherein the cone tip is located in the tool tip. Despite the pivoting movement thus the cone tip remains in its spatial position with respect to the coordinate system.

It has been found that, as a result, the tool 9 can always be aligned optimally on the workpiece surface, which is known to be of crucial importance for achieving good surfaces on the workpiece. Unlike other machine tools, the tool holder 8 sets with increasing size of the pivoting movement together with the tool 9 next to the workpiece. This allows for very large tilt angle, which always allows at least a good alignment of the tool on the workpiece for the milling process. Since a balanced load on both clamping points 16, 17 can also be achieved by the invention, overall high-quality work results are possible with such machine tools.

Since in the inventive machine tool, the two clamping points in the Y direction with a comparatively large distance and also in the Z direction can be arranged with distance from each other, a one-sided clamping of a workpiece and its frontal processing is possible. A production clamping accuracy detrimental second clamping of the workpiece can be avoided, which is why with machine tools according to the invention even such machining with high manufacturing accuracy are possible.

Finally, it should be noted that all described axes are driven axles that are movable separately and simultaneously. The movements are usually generated and controlled by the electronic control, processed in the programs for the production of workpieces and, where appropriate, can be stored in suitable storage means.

LIST OF REFERENCE NUMBERS

Machine frame 24 rail

Slide 25 rail

Carriage 26 rail

Carriage 27 sleds

Linear motion rail 28 carriage inclined surface 29 rail

Tool carriage 30 rail

Tool carrier 31 car

Milling tool 32 cars

Machining axle 33 cars

Tool drive 34 Cart

Swivel axle 35 cars

Round station 36 cars

Clamp a drive

release axle

Clamp point support

rail

Claims

claims

1. A machine tool for milling of workpieces, which is provided with a tool carrier for receiving a chip-removing and rotationally driven machining tool having a workpiece holder, in which between two clamping points a workpiece is clamped, wherein the machine tool has a plurality of driven axes of motion

Movement axes are provided to produce individually or in combination with each other machining feed movements as relative movement of the machining tool with respect to the workpiece during machining of the tool on the workpiece, wherein the tool carrier with at least one linear axis of movement of the driven axes of movement and the workpiece holder with at least two physically separated Carriage (27, 28) is provided on each of which one of the clamping points is arranged, the two slides (27, 28) of the workpiece holder at least along at least one driven linear movement axis are movable, characterized in that of the two slides (27, 28 ) of the workpiece holder is provided at least one with a second linear movement axis for performing machining feed movements.

2. Machine tool according to claim 1, characterized in that the workpiece holder is designed as a round station, which is provided with a rotation axis for carrying out driven feed rotational movements of the workpiece about an axis of rotation extending through both clamping points.

3. Machine tool according to at least one of the two preceding claims, characterized in that both clamping points, each with a drive for generating a rotational movement of a workpiece is provided.

4. Machine tool according to at least one of the preceding claims, characterized in that the two carriages are movable on the same rails of linear motion guides one of the axes of movement.

5. Machine tool according to at least one of the preceding claims, characterized by means for synchronizing movements and / or positions of the two carriages.

6. Machine tool according to at least one of the preceding claims, characterized in that arranged on at least one, preferably on both, carriage in each case at least one linear motion guide of one of the linear axes of movement.

7. Machine tool according to claim 6, characterized in that the movements of the at least two arranged on the carriage

Linear motion guides are synchronized with each other.

8. Machine tool according to claim 7, characterized by a control for the synchronization of the at least two linear motion guides.

9. Machine tool according to at least one of the preceding claims, characterized by a tool carrier, which in a direction transverse to

Workpiece axis is movable.

10. Machine tool according to at least one of the preceding claims, characterized in that the two clamping points is arranged on a respective cross slide, wherein each of the cross slide is designed for the execution of driven machining feed movements along two mutually non-parallel axes of movement.

11. Machine tool according to at least one of the preceding claims, characterized by means with which the tool carrier is pivotable in driven machining feed movements.

12. Machine tool according to claim 11, characterized in that a pivot axis of the tool carrier at least approximately

Machining axis cuts.

13. Machine tool according to claim 12, characterized in that the pivot axis intersects the machining axis at least approximately in the region of a tool tip.

14. A method for milling of workpieces in a machine tool, wherein a tool is held in a tool holder and driven in rotation, a workpiece between two clamping points of a workpiece holder is held, each clamping point is located on a respective carriage and the two carriages at least parallel to each other are movable in machining feed movements, the tool carrier along at least one linear movement axis in a machining feed movement is movable, characterized in that the workpiece is moved with at least one of the two carriages in two non-parallel linear machining feed movements.