Tool clamping system

Abstract

Disclosed is a tool system including a drive for driving a tool holder including an electromagnetic generator for generating electrical energy from inertial energy of the tool holder. The tool holder may be driven in rotation, wherein the electromagnetic generator comprises a rotor part, which is rotatably mounted on the tool holder, and a stator part on the tool holder cooperating with each other for generating a voltage by electromagnetic induction. Alternatively, an axially movable inertial mass can be used for utilization of an oscillating linear movement.

Claims

1. A tool clamping system for clamping a tool, comprising: a tool holder for holding a tool; a drive for driving said tool holder oscillatingly; an electromagnetic generator configured for generating electrical energy from an inertial energy of said oscillating drive; and a sensor configured for monitoring an operating parameter of the tool clamping system; wherein said sensor is powered by the electrical energy generated by said electromagnetic generator.

2. The tool clamping system of claim 1, wherein said drive is configured for driving said tool holder back and forth in a longitudinal direction.

3. The tool clamping system of claim 2, further comprising an inertial mass being mounted axially movably on a shaft of said tool holder.

4. The tool clamping system of claim 3, wherein said tool holder is configured for receiving a honing tool.

5. The tool clamping system of claim 4, wherein said inertial mass is mounted axially movably between two stops.

6. The tool clamping system of claim 3, wherein, on said shaft and said inertial mass, there is provided at least one winding cooperating with a magnet for generating an induction voltage from said oscillating movement.

7. The tool camping system of claim 6, further comprising at least one permanent magnet arranged on said inertial mass cooperating with said at least one winding, wherein said at least one winding is arranged on said shaft.

8. The tool camping system of claim 7, wherein said at least one winding is part of a magnet array.

9. A tool clamping system for clamping a tool, comprising: a tool holder for holding a tool; a drive for driving said tool holder oscillatingly; an electromagnetic generator for generating electrical energy from an inertial energy of said tool clamping system; and an inertial mass being mounted movably on a shaft of said tool holder; wherein, on said shaft and said inertial mass, there is provided at least one winding cooperating with a magnet for generating an induction voltage from said inertial energy of said oscillating movement; wherein said drive is further configured for rotatingly driving said tool, and wherein said at least one winding cooperating with said magnet is further configured for generating an induction voltage from said rotating movement.

10. A tool clamping system for clamping a tool, comprising: a tool holder for holding a tool; a drive for driving said tool holder oscillatingly; an electromagnetic generator for generating electrical energy from an inertial energy of said tool clamping system; an inertial mass being mounted movably on a shaft of said tool holder; at least one winding arranged on said shaft and said inertial mass and cooperating with a magnet for generating an induction voltage from said oscillating movement; and at least one permanent magnet arranged on said inertial mass cooperating with said at least one winding; wherein said inertial mass is mounted movably in an axial direction between two stops, wherein a maximum amplitude defined in said axial direction between said two stops is greater than an axial length of said at least one permanent magnet.

11. The tool clamping system of claim 10, wherein said at least one winding comprises a magnet core having an axial length deviating from an axial length of said at least one permanent magnet.

12. A tool clamping system for clamping a tool, comprising: a tool holder for holding a tool; a drive for driving said tool holder oscillatingly; an electromagnetic generator configured for generating electrical energy from an inertial energy of said oscillating drive; a sensor configured for monitoring an operating parameter of the tool clamping system; and a transmitter configured for transmitting an output signal generated by said sensor to an evaluation circuit; wherein said sensor and said transmitter are powered by the electrical energy generated by said electromagnetic generator.

13. The tool clamping system of claim 12, further comprising an antenna fed by said transmitter for transmitting said output signal of said sensor wirelessly.

14. The tool clamping system of claim 12, wherein said evaluation circuit is configured as a stationary evaluation circuit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further features and advantages of the invention will emerge from the following description of preferred exemplary embodiments with reference to the drawing, in which:

(2) FIG. 1 shows a perspective view, exposed in part, of a tool clamping system according to the invention;

(3) FIG. 2 shows a simplified detail of a voltage generator according to the invention in an embodiment as disk rotor;

(4) FIG. 3 schematically shows a profile of the rotational speed of the tool clamping system depending on time, with delayed profile of the rotor indicated in a dashed manner;

(5) FIG. 4 shows a schematic illustration of the AC voltage generated by the voltage generator following rectification by a bridge rectifier;

(6) FIG. 5 shows a possible circuit for rectification and voltage stabilization of the AC voltage generated by the voltage generator;

(7) FIG. 6 shows a schematic illustration of a sensor that is supplied by the generated, rectified and voltage-stabilized supply voltage U.sub.g in order to operate, with the output signal thereof, an operational amplifier, which in turn operates a transmitter for the wireless transfer of the useful signal to a stationary evaluation circuit;

(8) FIG. 7 shows a simplified schematic illustration of an electric interface at the end of the tool shaft;

(9) FIG. 8 shows a perspective illustration of a conventional honing tool with drive shaft;

(10) FIG. 9 shows a perspective illustration of a tool clamping system according to the invention with a honing tool;

(11) FIG. 10 shows a partially sectional longitudinal view of the tool clamping system according to FIG. 9, from which the structure of the inertial mass with magnet array becomes clearer;

(12) FIG. 11 shows a schematic illustration of the magnet array according to FIG. 10, and

(13) FIG. 12 shows an enlarged partial view of the magnet array according to FIG. 10 with permanent magnet for mounting.

DESCRIPTION OF PREFERRED EMBODIMENTS

(14) A simplified embodiment of a tool clamping system according to the invention is illustrated prospectively in FIG. 1 and is designated on the whole by numeral 10.

(15) The tool clamping system 10 has a tool holder 12 in the form of an HSK, which can be driven in rotation by a tool spindle, for example of a lathe or miller. The tool holder 12 can be formed for example as a shrink chuck or also as a mechanically clampable chuck.

(16) A voltage generator designated on the whole by 17 is received above a changeover receptacle 13 on the side facing toward the tool 14. In the illustrated case the voltage generator 17 has an inner part or stator part 22 received on the tool holder 12, on which inner part or stator part induction windings 24 are provided. The stator part 22 cooperates with an outer part in the form of a rotor 18 mounted on said stator part by means of a rolling bearing 16, there being permanent magnets 20 provided on the rotor.

(17) The rotor 18 with the permanent magnets 20 is thus rotatably mounted on the stator part 22.

(18) If the tool clamping system 10 is accelerated by a tool spindle, a relative movement between the rotor 18 and the stator part 22 is thus produced as a result of the inertia of the rotor 18. By means of the movement of the permanent magnets 20 along the induction windings 24, a voltage is induced in the induction windings 24 on account of the electromagnetic induction.

(19) The induced AC voltage can be rectified and stored by means of a capacitor and stabilized by means of a stabilization element, such as a Zener diode.

(20) For example, this voltage can be supplied to a sensor, which is received in the tool 14, for which purpose a suitable electric interface 26 is arranged at the outer end of the tool holder 12 in order to ensure the electrical contact with the sensor for voltage supply thereof and for the transfer of an output signal.

(21) In FIG. 2 a detail of a voltage generator designated on the whole by 17a is illustrated and is designed as a disk rotor. Here, the permanent magnets 20 in question are arranged in a planar manner in a plane of the disc-shaped rotor 18 and cooperate with the induction windings 24, which are arranged in a planar manner in the direct vicinity of the permanent magnets 20, likewise in a plane of the stator part 22.

(22) The permanent magnets 20 are arranged alternately with reversed polarity. In the event of a rotation of the rotor 18 relative to the stator part 22, and approximately sinusoidal induction voltage is produced in the induction windings 24 of the stator part 22. The induction windings 24 may be connected for example in a mono-polar or multi-polar (in particular tri-polar) manner. A mono-polar connection is preferably used, which results in a reduced conditioning effort with the subsequent stabilization of the voltage.

(23) In FIG. 3 a rotational speed ramp is plotted over time by way of example and shows the start-up of the tool clamping system 10 to a determined operating rotational speed, followed by a temporary maintenance of the rotational speed and a subsequent braking of the rotational speed to 0. Offset in relation thereto, there is shown in a dashed manner the rotational speed set at the rotor 18 by the delay.

(24) Of course, the rotor 18 is delayed compared with the tool holder 12, which results on the one hand by the inertia of the rotor 18, but on the other hand also by the induced voltage, which under load leads to an electromotive force, which is directed opposite the cause, as is known.

(25) With a mono-phase connection of the induction windings 24, an approximately sinusoidal induction voltage is produced, which naturally becomes increasingly smaller over time with equalization of the rotational speeds between the rotor 18 and the tool holder 12.

(26) FIG. 4 shows the induced voltage following rectification by a bridge rectifier, again in the starting phase (i.e. without considerable reduction of the voltage).

(27) FIG. 5 shows an exemplary circuit 30, which can be used for storage and voltage stabilization. The output voltage 32 of the voltage generator 17 or 17a is fed to the input of a bridge rectifier 34. A capacitor C and parallel thereto a Zener diode Z are disposed between the two outputs 36, 38 of the bridge rectifier 34, wherein the Zener diode may additionally also be disposed in series with a resistor (not illustrated).

(28) The capacitor C is preferably embodied as a gold-cap capacitor, which ensures a particularly high capacitance with particularly low losses and thus enables a long-term storage. Depending on the output voltage peaks of the windings, it may be necessary to adapt this voltage under the breakdown voltage of the storage capacitor. The Zener diode limits the output voltage U.sub.g to a value defined by the Zener diode. The output voltage U.sub.g is available as useful voltage, with the aid of which any electronic components can be supplied, wherein these may preferably be constituted by a sensor, a circuit for signal processing, or for example a transmitter.

(29) It goes without saying that the components illustrated here are merely purely exemplary in nature and that, instead of the analogue circuit components presented here, digital circuit components are of course also conceivable, as long as the provided energy is sufficient for voltage supply.

(30) In FIG. 6 a sensor 40 is illustrated by way of example, which sensor is fed by the generated supply voltage U.sub.g and provides at its output 42 an output signal.

(31) The sensor may be, for example, a temperature sensor, an acceleration sensor or a force sensor (for example DMS measuring bridge). The sensor 40 may be used to monitor any operating parameters of the tool clamping system, i.e. for example for temperature monitoring, for force monitoring, for monitoring the acceleration.

(32) According to FIG. 6 the output signal of the sensor 40 is fed to the input 46 of a downstream operational amplifier 44, which is likewise supplied by the supply voltage U.sub.g. The amplified signal is available at the output 48 of the operational amplifier 44 and can then be fed, where necessary after further processing, to a transmitter 50, which transfers the signal via an antenna 52 wirelessly to a stationary evaluation circuit 54, which in turn has a suitable antenna 56.

(33) It goes without saying that any known methods can be used for signal processing. Such methods are known and can of course be used within the scope of the present invention.

(34) FIG. 7 shows by way of example the arrangement of an electric interface 60 in the region between the shaft end of the tool 14 and a receiving bore of the tool holder, which is formed here for example as a shrink holder.

(35) At the end of the tool shaft of the tool 14, a contact face 61 is provided on the end face and is electrically insulated from the rest of the tool 14, for example by means of suitable ceramic layers, and is coupled via a line 58 for example to an associated sensor 40 in the tool 14. The contact face 61 is assigned a resiliently mounted contact pin 62 on the tool holder 12, which contact pin is pre-loaded toward the tool 14 via a spring 64. This contact pin 62 is also electrically insulated in a suitable manner with respect to the rest of the material of the tool holder 12 and is connected for example via a line 66 to an associated evaluation and transmitting unit within the tool holder 12.

(36) Here, merely one arrangement for transfer is shown by way of example for merely one pole. It goes without saying that of course further contacts can be provided for the other poles (for example for the voltage supply of the sensor 40), possibly in a concentric arrangement. A concentric arrangement has the advantage that a voltage transfer is enabled independently of the position of installation of the tool 14 on the tool receptacle 12.

(37) Depending on the application in question for which the present voltage generator is to be used, the inertial moment of the rotor, the windings and the consumer in question and also the associated circuit for storage and voltage stabilization are advantageously coordinated with one another in a suitable manner in order to attain an optimal voltage yield for the application in question, the voltage yield being sufficient over a long period of time for sufficiently supplying energy to the desired monitoring circuit(s) in a suitable manner.

(38) An alternative embodiment of the invention will now be explained with reference to the following FIGS. 8 to 12, in which the oscillation energy in the case of a honing tool is used for energy generation.

(39) FIG. 8 shows a conventional tool clamping system 10 for a honing tool 14. The honing tool 14 is received on a shaft 72, which is driven by a tool spindle 74. The honing tool 14 has a plurality of honing stones 70, which are received on the outer surface of the tool holder 12. The shaft 72 is driven in rotation, as is indicated by the arrow 76. In addition, the shaft 72 is driven with longitudinal oscillation in the axial direction, as is indicated by the arrow 75.

(40) By means of a wedge-shaped mounting of the honing stones 70 on the tool holder 12, only a slightly grinding movement without substantial workpiece removal is produced in a first direction of the honing tool 14, whereas, in the reverse direction, on account of the wedge effect, the honing stones 70 bear under pressure against the inner surface of the workpiece to be honed (for example a cylinder bore of an internal combustion engine) and cause a workpiece removal. The honing stones during the course of the honing process receive, in part, removed material of the workpiece, such that an axial adjustment of the tool holder 12 on the shaft is necessary in order to ensure a uniform machining (not illustrated). In the case of conventional honing machines this readjustment is made empirically on the basis of the number of performed strokes of the honing tool 14.

(41) FIG. 9 now shows a tool clamping system 10a for a honing machine that is constructed in accordance with the invention and has a device 78, 88, 90 for voltage generation from the inertial energy of an oscillating honing tool 14a. A sensor can be operated with this energy, which sensor either detects the position of the honing tool 14a or the force exerted onto the honing tool and transfers this wirelessly, for example via WIFI, to a controller of the honing machine.

(42) An inertial mass 78 having a magnet array 90 is mounted movably in the axial direction, as indicated by the arrow 84, on the shaft 72 of the tool clamping system 10a, which is driven by the spindle 10a (or a suitable interface). The inertial mass is movable back and forth between two stops 80, 82, wherein the movement energy is stored by springs 81, 83 located therebetween. If the honing tool 14a is moved back and forth in an oscillating manner in the direction of the arrow 75, the inertial mass 78 thus moves back and forth in the direction of the arrow 84 with a certain phase shift relative to the movement of the honing tool 14a.

(43) By means of a winding 88 on a magnet core 86 in the form of a laminated core according to FIG. 10, a voltage is induced hereby in cooperation with associated permanent magnets 89 on the inertial mass 78 in accordance with the principle of a linear generator. This voltage can be used to operate a sensor and for the wireless transfer of a signal in order to capture and to transfer the absolute position of the honing tool 14a or the force exerted onto the honing stones 70.

(44) The axial length L.sub.M of the permanent magnets 89 is much shorter than the axial length of the magnet core L.sub.K 86 of the winding 88. An effective voltage generation is thus ensured.

(45) In order to prevent the production of a large magnetic detent moment as a result of matching axial lengths (L.sub.M) of the permanent magnets 89 and of the magnet core (L.sub.K) of the winding 88, the axial length (L.sub.M) of the permanent magnets deviates slightly from the axial length of the magnet core 86 (L.sub.ML.sub.K).

(46) It goes without saying that, instead of one winding 88 with a magnet core 86, a plurality of windings 88 may also be provided on the shaft 72 distanced axially from one another.

(47) FIG. 11 shows, by way of example, a magnet array 90, which can be received on the shaft 72 alternatively to the winding 88 in order to ensure a particularly effective energy generation. The magnet array 90 is illustrated in a planar arrangement of the different windings extending in the radial direction. With a magnet array 90 of this type, an effective energy generation can be ensured both from the alternating linear movement of the honing tool 14a and from the rotation energy of the inertial mass 78.

(48) FIG. 12 shows, by way of example, how permanent magnets 92 provided in the outer periphery of the shaft 72 can be used for the low-loss magnetic mounting of the inertial mass 78 on the shaft 72.