EP3595844A1

EP3595844A1 - Clamping means assembly for a machine tool, and machine tool comprising the clamping means assembly

Info

Publication number: EP3595844A1
Application number: EP18714427.4A
Authority: EP
Inventors: Michael Haberzettl
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2017-03-13
Filing date: 2018-03-01
Publication date: 2020-01-22
Also published as: CN110382163A; DE102017105257A1; WO2018166557A1

Abstract

The invention relates to a clamping means assembly (4) for a machine tool (1). The machine tool (1) has a tool (2) for machining a workpiece (3). The clamping means assembly (4) comprises a clamping means (5) which has a machine interface (9) for coupling to the machine tool (1) and a workpiece interface (8) for receiving the workpiece (3), a sensor assembly (6) which is designed to pick up vibrations of the tool (2) in the form of sensor data, and a controller (7) for receiving sensor data of the sensor assembly (6), wherein the clamping means (5) has at least one actuator (10) which is arranged on the clamping means (5), and the controller (7) is designed to actuate the at least one actuator (10) on the basis of the sensor data in order to compensate for the vibrations of the tool (2).

Description

Clamping arrangement for a machine tool and machine tool with the clamping device arrangement

The invention relates to a clamping device arrangement for a machine tool having the features of the preamble of claim 1. The invention also relates to a machine tool with this clamping device arrangement.

In separating, in particular machining, machining of the workpieces can lead to vibrations of the workpiece or the tool. Such vibrations are amplified when a feed rate for a tool is set too high during machining. This can, for example, lead to a "chattering" during a turning operation, wherein a characteristic, regular chattering pattern or chatter marks are applied to the workpiece, so that the machining quality on the workpiece is reduced On the other hand, it is desirable to set the feed rate as high as possible in order to achieve the lowest possible processing times.

DE 10 2006 049 867 A1 discloses a machine tool with a workpiece clamping device for clamping a workpiece and with a tool table, which is movable by means of an electric motor. The Werkstückeinspannvorrichtung and thus the workpiece are movable relative to the tool table by means of a piezoelectric actuator. In this case, a piezoelectric table is permanently mounted on the tool table, the piezoelectric actuators being arranged between the workpiece clamping device and the piezoelectric table. The known machine tool is designed to greatly reduce vibrations such as chatter vibrations.

In manufacturing plants, however, are usually older machine tools in use, no devices for the production of such Have vibrations. The purchase of a new machine tool is associated with high costs.

It is therefore an object of the present invention to provide a clamping device assembly for use in any conventional machine tool, which leads to such a reduction of vibrations.

This object is achieved by a clamping device arrangement with the features of claim 1 and by a machine tool having the features of claim 8. Preferred or advantageous embodiments of the invention will become apparent from the dependent claims, the following description and the accompanying drawings.

The invention relates to a clamping device arrangement which is suitable and / or designed for use in any conventional machine tool. The machine tool has a tool for machining a workpiece. The tool is in particular a tool for separating, in particular for machining. In particular, the tool can be designed as a drilling, milling, turning or broaching tool. The workpiece is particularly preferably realized as a metallic workpiece.

The tensioning means arrangement has a tensioning means, which can also be referred to as a tensioning means device. The clamping device has a machine interface for coupling to the machine tool and a workpiece interface for receiving the workpiece. In particular, the clamping means is designed as a receiving device which is arranged between the workpiece and the machine tool. The clamping means can also be referred to as an adapter for the workpiece to the machine tool.

It is preferred that the clamping means rotates together with the workpiece during machining. Alternatively or additionally, it is preferred that the tool is arranged stationary or at least only delivered. The clamping device arrangement has a sensor arrangement, wherein the sensor arrangement is designed to receive vibrations of the tool as sensor data. The vibrations of the tool thus form a measured variable in the sensor arrangement. The measured variable and / or the vibrations can be removed directly on the tool. However, it is also possible to detect the vibrations of the tool indirectly, for example via the tool holder of the tool. The vibrations of the tool are transmitted directly to the tool holder, so that the vibrations of the tool on the tool holder are unadulterated or virtually unadulterated.

The clamping device arrangement further has a control device for receiving the sensor data of the sensor arrangement. The control device is designed, for example, as a digital data processing device. In particular, this can be realized as a microcontroller, a computer, etc. Alternatively, this may be designed as an analog data processing device or as a combination of digital and analog data processing device.

In the context of the invention, it is proposed that the tensioning means comprise at least one actuator arranged on the tensioning device, which actuator is particularly preferably operated with external energy. Characterized in that the at least one actuator is arranged on the clamping means itself, an installation of a clamping device according to the invention is independent of the type of machine tool feasible. Thus older machine types can be easily converted and the quality of the machined workpieces can be increased.

In particular, the at least one actuator is designed as an active actuator. The controller is programmatically and / or circuitry designed to evaluate the sensor data and based on the sensor data and / or their evaluation to control the actuator. The activation of the actuator is done so that the vibrations of the tool are compensated. In particular, the actuator is controlled so that the negative consequences for the machining of the workpiece are reduced or eliminated. The activation of the actuator takes place in particular in real time, in particular with a control frequency equal to or higher than the main frequencies of the vibrations.

It is an advantage of the invention that the clamping means is designed as an active clamping means which compensates or compensates for vibrations caused by the machining on the tool by manipulation of the workpiece by means of the actuator. In this way, the clamping device arrangement makes it possible to improve the machining result of the machine tool or, alternatively, to allow higher feed speeds, thereby making the production process more cost-effective.

Preferably, the clamping means is formed as an encapsulated system, which can be adapted to any machine tool or at least on many machine tools.

In a preferred embodiment of the invention, the control device is designed to control the actuator in such a way that the workpiece is counter-oscillated in order to generate an extinction of the oscillations of the tool.

Particularly preferably, a feedforward control is implemented by the control device and / or the clamping device arrangement. The basic principle of feedforward control is to compensate for a disturbance on a primary track - here on the tool - by imposing a counter-swing on the system via a secondary track - here on the workpiece - at the exit of the primary track - Here on the machining zone between the tool and workpiece - to achieve vibration cancellation. The countervibration is calculated directly from the reference signal acting on the input of the primary link - here the sensor data. Therefore, the term feedforward control for the feedforward control, in particular feedforward control, control or control, is also common.

In a preferred structural realization of the invention, the workpiece interface is formed as a chuck, which, for example can be opened and closed to clamp the workpiece. In particular, the chuck is realized as a lathe chuck. Thus, the workpiece can be clamped directly into the clamping device. The transmission of the countervibrations of the at least one actuator to the workpiece are particularly easy to implement.

Alternatively or additionally, the machine interface is designed for coupling to a machine flange. The machine interface can be a standardized connection according to DIN ISO 702-1 to 702-4 (issued April 2010). In particular, in a preferred embodiment, it may be a clip exchange closure, such as a bayonet closure act. This allows a short-term use of a single clamping device arrangement in alternation with several different machine tools of an operation.

Particularly preferred decoupling modules are provided between the clamping means and the machine flange, which prevent vibrations transmitted from the clamping means to the machine tool. The decoupling modules can be integrated in particular in the clamping device and / or in the machine flange. Such a decoupling module is essentially a passive bearing, which is arranged in particular adjacent to the machine flange contact surfaces. As decoupling modules, for example, inserts made of granite, reactive resin concrete or the like can be used.

In a preferred embodiment of the invention, the sensor arrangement has at least one piezoelectric sensor. Such piezoelectric sensors can record vibrations with very high frequencies with low errors. Particularly preferably, the sensor arrangement has two such piezoelectric sensors in order to carry out a redundancy measurement.

It is preferred that the actuator allows movement of the workpiece interface and / or of the workpiece in the direction of a rotation axis (ie in the Z direction) and perpendicular to the rotation axis in the direction of the workpiece (ie in the X direction). In this way, any vibration on the workpiece interface or the workpiece can be applied to the rotating workpiece.

In a structural realization of the actuator may be formed, for example, as a ring actuator or as a disk actuator. It is particularly preferred that this is also designed as a piezoelectric actuator to allow a fast response and / or frequency in the control by the control device.

Another object of the invention is a machine tool as described above with a tool for machining a tool. The machine tool has the clamping device arrangement, as described above.

Another optional object of the invention is a method for compensating for vibrations on a tool with the clamping device assembly and / or the machine tool, as described above. When the vibrations are compensated, vibrations of the tool are recorded as sensor data and compensated by triggering the actuator with countervibrations, so that the vibrations at the machining zone between the workpiece and the tool are reduced and preferably extinguished.

Further features, advantages and effects of the invention will become apparent from the following description of a preferred embodiment of the invention and the accompanying drawings. These show:

Figure 1 is a schematic representation of a machine tool with a clamping device arrangement as an embodiment of the invention;

Figure 2 shows a basic structure of a feedforward control, as this can be used in the clamping device arrangement. 1 shows a highly schematic diagram of a machine tool 1 with a tool 2 for machining a workpiece 3 as an embodiment of the invention. Conceptually considered, the workpiece 3 is rotated during machining about a rotation axis R, which runs parallel to a Z-direction in a coordinate system KO of the machine tool 1. In the side view shown, in the coordinate system KO, an X direction is perpendicular to the Z direction. In particular, the XZ plane is shown.

The tool 2 may be formed, for example, as a drilling, milling, turning or broaching tool. In the present embodiment, the tool 2 is realized as a turning tool. The tool 2 has a tool holder 14, which has a shank and a head, wherein an indexable insert is arranged as a cutting body 17 on the head.

The machine tool 1 has a clamping means arrangement 4, which is constructed from a clamping means 5 of a sensor arrangement 6 and a control device 7. The clamping means 5 has as a workpiece interface 8 a chuck, in particular lathe chuck, wherein the workpiece 3 is received in the workpiece interface and is clamped in particular in the clamping or lathe chuck. At the other free end of the clamping means 5, a machine interface 9 is arranged, with which the clamping means 5 with the machine tool 1, in particular a rotation axis or spindle axis of the machine tool 1 can be connected. The machine interface 9 is designed as a standard interface. In particular, the machine interface 9 is designed as a quick-change closure in the form of a bayonet closure.

In the clamping means 5, an actuator 10 is integrated, which makes it possible to move the workpiece interface 8 and thus the workpiece 3 in the Z direction and additionally in the X direction or tilt. Taking into account that the workpiece 3 is offset during machining in rotation about the rotation axis R together with the clamping means 5, so can be deflected by the actuator 10, the workpiece 3 in any direction perpendicular to the rotation axis R. However, it is also possible that another actuator 10 is used. The actuator 10 is over a cable 1 1 signal-coupled with the control device 7. In view of the rotation of the clamping means 5, a rotary feedthrough 12 for the signal transmission and for the power supply between the control device 7 and the actuator 10 is provided.

The sensor arrangement 6 has two sensors 13 a, b, which are arranged on the tool holder 14 of the tool 2. One of the sensors 13 a is attached to the shaft of the tool holder 14, the other sensor 13 b is disposed on the head of the tool holder 14, immediately adjacent to the blade body 17. Both sensors 13a, b are designed as vibration sensors and in particular according to a piezoelectric operating principle. By way of further cables 15, the sensors 13a, b or, more generally, the sensor arrangement 6 are signal-connected to the control device 7.

The clamping means 5 has decoupling modules 16 which are provided for decoupling the machine tool 1 from the clamping means 5 and in particular from counter vibrations of the actuator 10. The clamping means 5 is designed as a fully encapsulated system that can be universally adapted to each machine tool 1.

In short, the operation is as follows: By machining with various tools (drilling, milling, turning, broaching tools, etc.), exemplified as a cutting body 17, vibrations may occur during machining. These are picked up by the sensors 13a, b as vibration sensors according to the piezoelectric operating principle on the tool 2 or on the tool holder 14, wherein the two sensors 13a, b represent a redundant system. The detected vibrations are processed as sensor data in the control device 7 via the axial position of the machine tool 1 in real time and control signals via an interface, in this case the cable 1 1, the actuator 10, which is integrated in the clamping means 5, fed, which is converted into negative vibrations are to extinguish in this way in the machining zone between the tool 2 and the workpiece 3, the vibrations. This type of vibration compensation can be implemented, for example, by a feedforward control whose structure is shown in FIG. In the signal path, a primary interference PM is impressed on the tool 2 as the primary path by the machining, which can lead to vibrations in the processing zone B. The compensation takes place via a secondary path, which is formed by the active clamping means 5 and the workpiece 3, which generate a countervibration. Via the sensor arrangement 6, a reference signal RS is received and supplied to the control device 7, which is designed as a controller, in particular as an adaptive filter. The control device 7 calculates a control signal, which is supplied to the active clamping means 5, so that the counter-vibrations are generated on the workpiece 3. The oscillations in the primary track and the countervibrations in the secondary track are said to result in mutual cancellation at the machining zone B. It may be provided that, in addition, an error signal FS is recorded over the sensor arrangement 6 in order to adapt the control device 7, in particular the controller.

By the clamping means 4, a clamping means 5 is thus proposed, which is universally applicable to all machine tools and has an active, integrated vibration damping, so that the clamping means 5 absorb labile, slightly oscillating workpieces as usual and can counteract the vibrations occurring during processing. The advantage is the increase in component quality and / or the reduction of cycle times and the reduction of tool costs.

LIST OF REFERENCE NUMBERS

1 machine tool

Tool

workpiece

Clamping means assembly

clamping means

sensor arrangement

7 control device

8 workpiece interface

9 machine interface

10 actor

1 1 cable

12 rotary feedthrough

13a, b sensors

14 tool holder

15 more cables

16 decoupling modules

17 cutting body

R rotation axis

KO coordinate system

PM primary disorder

B processing zone

RS reference signal

FS error signal

Claims

claims

1 . Clamping arrangement (4) for a machine tool (1), wherein the machine tool (1) has a tool (2) for machining a workpiece (3),

with a clamping means (5), wherein the clamping means (5) has a machine interface (9) for coupling to the machine tool (1) and a workpiece interface (8) for receiving the workpiece (3),

characterized in that

the tensioning means arrangement (4) furthermore has a sensor arrangement (6), the sensor arrangement (6) being designed to receive vibrations of the tool (2) as sensor data, and furthermore comprising a control device (7) for receiving sensor data of the sensor arrangement (6), and wherein the tensioning means (5) has at least one actuator (10) arranged on the tensioning means (5), wherein the control means (7) is designed to control the at least one actuator (10) on the basis of the sensor data, in order to control the vibrations of the tool (2 ) to compensate.

2. clamping device arrangement (4) according to claim 1, characterized in that the control device (7) is adapted to control the actuator (10), so that the workpiece (2) is set in counter-vibrations to extinguish the vibrations of the tool (2 ) to create.

3. clamping device arrangement (4) according to claim 1 or 2, characterized in that the workpiece interface (8) is designed as a chuck.

4. clamping device arrangement (4) according to one of the preceding claims, characterized in that the machine interface (9) is designed for coupling to a machine flange as a quick-change lock.

5. clamping device arrangement (4) according to one of the preceding claims, characterized in that the sensor arrangement (6) has at least one piezoelectric sensor.

6. clamping device arrangement (4) according to one of the preceding claims, characterized in that the actuator (10) movement of the workpiece interface (8) and / or the workpiece (2) in the direction of an axis of rotation (R) of the clamping means (5) and in a vertical direction allows.

7. clamping device arrangement (4) according to claim 6, characterized in that the actuator (10) is designed as a ring actuator or disk actuator.

8. Machine tool (1) with a tool (2) for machining a workpiece (2), characterized by a clamping means arrangement (4) according to one of the preceding claims.

9. Machine tool (1) according to claim 8, characterized in that during machining, the tool (2) is arranged stationary and the clamping means (5) is rotated.

10. Machine tool (1) according to claim 8 or 9, characterized in that the tool (2) is designed as a drilling, milling, turning or broaching tool.