Boring head with mechanism for clamping a displaceable tool carrier

Abstract

A boring head is provided, which includes a tool body (1) having a main rotation axis (R), and the tool body (1) rotates about the main rotation axis during a boring operation. The boring head further includes: a tool carrier (6) arranged in or on the tool body (1); a first motor (9) for displacing the tool carrier (6) relative to the tool body (1); and a clamping mechanism (26) having clamping elements (27, 55, 68, 81) for applying a clamping force to the tool carrier (6) to prevent the tool carrier (6) from displacing relative to the tool body (1) during the boring operation. The clamping mechanism (26) is an active clamping mechanism, and the active clamping mechanism applies a clamping force that can be actively adjusted.

Description

Technical Field

[0001] The present invention relates to a boring head having a clamping mechanism for clamping a displaceable tool carrier to prevent displacement of the tool carrier relative to the tool body during a boring operation. Background Art

[0002] For example, boring heads for metal cutting to form chips typically include a tool carrier that is radially displaceable relative to the tool body to allow radial adjustment of a cutting tool attached to the tool carrier. Such boring heads are used, for example, to enlarge an existing hole by rotating the boring head with the tool attached thereto. The radial displacement of the tool carrier enables not only a variable cutting diameter but also compensation for wear of the cutting tool during the boring operation.

[0003] For adjusting the boring diameter, the radial displacement of the tool carrier is typically performed manually by the user. For this purpose, the user rotates an adjusting screw that engages a threaded hole of the tool carrier to radially displace the tool carrier relative to the tool body. However, manual adjustment is time-consuming and often inaccurate. Therefore, there is a need for a boring head having a motor-driven tool carrier, i.e., a tool carrier that can be radially displaced relative to the tool body by means of a motor.

[0004] A motor-driven electric actuator for radially displacing a cutting tool of a boring head is disclosed in US2017 / 165760 A1. However, the electric actuator represents an external device, which still requires manual operation and interruption of the boring operation.

[0005] For example, boring heads having a motor for displacing a tool carrier are disclosed in DE 197 17 172A1, WO 88 / 03672A1, JP 3 252996B2, and EP 3 222 375A1.

[0006] Some prior art documents, such as WO 00 / 62962A1 and US2014 / 0133930 A1, propose the motorized radial or axial displacement of a tool carried in a boring head by means of a piezoelectric mechanism.

[0007] The challenge faced by tool carriers that can be displaced by means of a motor lies, in particular, in their fixation within the tool body during the boring operation. During the boring operation, large forces and in particular large radial forces typically act on the cutting tool and the tool carrier. Due to these forces, the tool carrier tends to displace in the radial direction, and every effort needs to be made to prevent this from happening in order to achieve a good boring result. The force of the displacement motor itself when at rest is typically far from sufficient to prevent this unwanted displacement during the boring operation.

[0008] In US 6,394,710 B1 and EP 2 095 897 A1, a prestressed spring element is used to apply a clamping force to the tool carrier to prevent the tool carrier from experiencing unwanted radial or axial displacement during the boring operation. However, setting such a passive clamping mechanism results in a greater force being required for the intended displacement of the tool carrier. If a motor is used for the displacement, a correspondingly stronger and larger-sized motor is required in this case. However, such a larger-sized motor is not only more expensive but also difficult to arrange within the limited space of the boring head.

[0009] Furthermore, it is pointed out that different embodiments of piezoelectric actuators are disclosed in DE 10 2004 002 249 A1 and DE 19643180 A1. SUMMARY OF THE INVENTION

[0010] It is an object of the present invention to provide a boring head having a tool carrier that can be easily displaced on the one hand and fixed relative to the tool body during the boring operation on the other hand.

[0011] This object is achieved by a boring head according to the present invention.

[0012] Accordingly, the present invention provides a boring head comprising:

[0013] A tool body having a main rotation axis about which the tool body rotates during the boring operation;

[0014] A tool carrier arranged in or on the tool body;

[0015] A first motor for displacing the tool carrier relative to the tool body; and

[0016] A clamping mechanism having a clamping element that applies a clamping force to the tool carrier to prevent displacement of the tool carrier relative to the tool body during the boring operation.

[0017] The clamping mechanism is an active clamping mechanism that applies a clamping force that can be actively adjusted.

[0018] Compared with a passive clamping mechanism, an active clamping mechanism does not require a preload to exist. Therefore, the force used to displace the tool carrier can be significantly reduced, which means lower requirements for the first motor. On the other hand, by means of the active clamping mechanism, a high clamping force can be applied to the tool carrier during the boring operation to prevent the tool carrier from undesirably displacing relative to the tool body. However, if it is necessary to displace the tool carrier relative to the tool body by means of the first motor, the tool carrier can be released by the clamping mechanism to enable easy displacement.

[0019] Therefore, the boring head includes an active clamping mechanism that applies a clamping force that can be actively adjusted. In contrast, in a passive clamping mechanism, such as a clamping mechanism formed only by a spring, the clamping force cannot be actively adjusted. The active clamping mechanism typically includes at least one element that can be activated and / or deactivated. In the case of the active clamping mechanism, when the clamping mechanism is activated and / or in the activated state of the clamping mechanism, an energy flow from an energy source to the clamping mechanism usually occurs. Therefore, in order to activate the active clamping mechanism, an energy storage device, particularly an electrical energy storage device such as one or more batteries, is preferably provided to supply the required energy. The boring head is preferably adapted to actively adjust the clamping force based on an input instruction of an operator and / or an input instruction of a control logic implemented, for example, in a printed circuit board (PCB) of the boring head.

[0020] The clamping mechanism is preferably adapted to be activated and / or in the activated state of the clamping mechanism so that the tool carrier can be displaced relative to the tool body. In addition, the clamping mechanism is preferably adapted to be deactivated and / or in the deactivated state of the clamping mechanism so that the tool carrier cannot be displaced relative to the tool body.

[0021] The main rotation axis of the tool body represents the axis about which the boring head rotates as expected during normal boring operation. The tool body is preferably integrally formed as a whole.

[0022] The tool carrier is used to carry the tool. The tool is usually a cutting tool, such as a cutting insert, that can be directly or indirectly attached to the tool carrier, for example, via a cutting tool holder.

[0023] In certain preferred embodiments, the tool carrier is displaceable laterally relative to the tool body, which means that the tool carrier is displaceable in a lateral direction relative to the main rotational axis. The lateral direction, relative to the displacement of the tool carrier, may but need not be the same as the perpendicular direction relative to the main rotational axis. In the present case, displacement along the lateral direction means that a radial displacement of the cutting tool relative to the main rotational axis is achieved such that, during a boring operation, a hole with a wider or smaller diameter is produced as a direct result of the displacement. Thus, although preferred in most cases, it is not absolutely necessary that the displacement of the tool carrier along the lateral direction is the same as and has the same effect as the displacement along the direction perpendicular to the main rotational axis. The direction along which the tool carrier is adapted to be displaced relative to the tool body by means of the first motor is referred to herein as the displacement direction.

[0024] The tool carrier is generally arranged within an opening of the tool body. The opening or hole can in particular be a through-opening. However, in certain embodiments, it is also conceivable that the tool carrier is attached to the outer part of the tool body in a displaceable manner. The tool carrier is preferably attached to the tool body such that the tool carrier cannot be removed from the tool body without the use of a special tool. The tool carrier is preferably integrally formed as a unit.

[0025] The first motor is preferably an electric motor, such as a DC motor. However, in certain embodiments, it is also conceivable to use a piezoelectric motor or a hydraulic motor as the first motor. The first motor is preferably at least partially, but advantageously completely, incorporated within the boring head, in particular within the tool body. In most cases, the first motor has a stator and a rotor with a drive shaft. The drive shaft is attached to the rotor in a torsion-resistant manner and is even integrally formed with the rotor in a preferred embodiment. By the rotation of the rotor during the operation of the motor, the main drive axis is defined.

[0026] In a preferred embodiment, the main drive axis of the first motor extends along a direction parallel to the direction along which the tool carrier is displaceable relative to the tool body and advantageously extends along a direction perpendicular to the main rotational axis. Then an optimal power transmission from the first motor to the tool carrier can be achieved. In these embodiments, the drive shaft preferably has an external thread and the tool carrier includes a hole with an internal thread or a nut with an internal thread attached to the tool carrier in a torsion-resistant manner. The external thread of the drive shaft engages with the internal thread of this internal thread or nut of the tool carrier such that the rotational movement of the rotor achieved by the first motor is converted into a displacement of the tool carrier relative to the tool body.

[0027] In other equally preferred embodiments, the main drive axis extends perpendicular to the direction along which the tool carrier can be displaced relative to the tool body and advantageously extends parallel to the direction of the main rotation axis. These embodiments have the advantage that the first motor can be better integrated into the boring head, especially in the case of using a relatively large first motor. To convert the rotational movement achieved by the first motor into a displacement of the tool carrier relative to the tool body, a worm gear drive is preferably provided in these embodiments. By having a transmission unit, especially a transmission unit with a worm gear drive, the applied force for displacing the tool carrier can be increased, or in other words, a first motor of a smaller size can be used to apply the same force to displace the tool carrier.

[0028] In some embodiments, when viewed along a direction perpendicular to the main rotation axis, the tool carrier has a first end and a second end, and the first end is adapted to attach a cutting tool. The first motor then preferably acts on the second end to displace the tool carrier.

[0029] In other embodiments, the tool carrier includes a hole extending along the main rotation axis of the tool body, and the hole is adapted to receive a cutting tool or a cutting tool holder. Thus, in this case, the cutting tool or the cutting tool holder can be attached to the boring head by being inserted into the hole of the tool carrier. For example, fixation within the hole of the tool carrier can be achieved by means of fixing screws.

[0030] The tool carrier does not necessarily need to be able to be displaced relative to the main rotation axis of the tool body in a transverse direction. It is also possible that the first motor is adapted to displace the tool carrier parallel to the main rotation axis in order to displace the cutting tool in the axial direction.

[0031] The clamping mechanism is preferably adapted to clamp the tool carrier against the tool body or against another element of the boring head. For this purpose, the clamping mechanism preferably includes a clamping element having a clamping surface, and the clamping surface is adapted to directly or indirectly abut against the outer surface of the tool carrier to prevent any undesired displacement of the tool carrier relative to the tool body during the boring operation. The clamping surface is preferably shaped to correspond to the corresponding part of the outer surface of the tool carrier so as to maximize the mutual contact surface between the clamping element and the tool carrier and thus maximize the resulting friction.

[0032] In a particularly preferred and advantageous embodiment, the clamping mechanism has an idle state and an activated state. In the idle state, the tool carrier is clamped, and in the activated state, the tool carrier can be displaced relative to the tool body. Therefore, it is preferably necessary to activate the clamping mechanism to release the tool carrier and enable the tool carrier to be displaced relative to the tool body. To activate the clamping mechanism and / or to maintain the clamping mechanism in the activated state of the clamping mechanism, it is preferably necessary to supply energy to the clamping mechanism, for example, from one or several batteries. However, in the idle state, the tool carrier is clamped by the clamping mechanism in such a way that the tool carrier cannot be displaced relative to the tool body. Preferably, no energy supply is required to maintain the clamping mechanism in the idle state of the clamping mechanism. The clamping mechanism is preferably designed such that: in the case where the clamping mechanism is in the activated state of the clamping mechanism and the energy supply is interrupted, the clamping mechanism automatically assumes the idle state of the clamping mechanism. During the machining of a workpiece, i.e., during a normal boring operation, the clamping mechanism is preferably adapted to be in the basic idle state of the clamping mechanism.

[0033] By providing an active clamping mechanism that clamps the tool carrier in the idle state and releases the tool carrier in the activated state - rather than vice versa - the safety of the boring head in terms of boring operations can be significantly improved. For example, if the energy supply to the clamping mechanism is inadvertently interrupted or becomes insufficient due to a low charge state of the battery, there is no risk that the tool carrier is released during the boring operation and thus damages the machined workpiece, or worse, poses a risk to the operator.

[0034] In other equally preferred embodiments, the clamping mechanism is adapted to increase or decrease the clamping force upon activation. Therefore, in the activated state of the clamping mechanism, the clamping force can be changed, for example, to clamp or release the tool carrier, while in the non-activated (or idle) state, the clamping force can remain unchanged. If the clamping force remains unchanged in the non-activated state, it can be particularly ensured that during the boring operation, if, for example, the energy supply to the clamping mechanism is inadvertently interrupted or becomes insufficient due to a low charge state of the battery, the clamping of the tool carrier is maintained.

[0035] According to an improvement of the present invention, the clamping mechanism is based on the piezoelectric effect and includes at least one piezoelectric element. The piezoelectric element - which can also be referred to as a piezoelectricity element - undergoes mechanical movement, particularly expansion, due to the action of a voltage on the element. By using a clamping mechanism based on the piezoelectric effect, an optimal and direct conversion of electrical energy into mechanical clamping force can be achieved. For example, in other embodiments, an electric DC motor can be used instead.

[0036] According to a further improvement of the invention, the boring head comprises a second motor, in particular in the form of a DC motor, for actively adjusting the clamping force. The second motor is preferably adapted to actively adjust the force exerted by the clamping element on the tool carrier.

[0037] In a preferred embodiment, the clamping element has the form of a clamping bracket that at least partially, preferably completely, surrounds the other clamping elements of the clamping mechanism, such that the expansion of the other clamping elements in a first direction is converted into a contraction of the clamping bracket in a perpendicular second direction. The other clamping elements can in particular be the at least one piezoelectric element as already mentioned. By means of the clamping element in the form of a clamping bracket, a clamping mechanism of relatively small dimensions can be achieved, which clamps the tool carrier in the idle state of the clamping mechanism and releases the tool carrier in the activated state of the clamping mechanism.

[0038] In another preferred embodiment, the clamping element has the form of a clamping beam that is adapted to move away from the tool carrier by means of the expansion of the other clamping elements of the clamping mechanism. The other clamping elements can in particular be the at least one piezoelectric element as already mentioned. By means of the clamping element in the form of a clamping beam, a particularly large clamping force can be achieved. The clamping beam preferably comprises a clamping surface and advantageously extends in a direction perpendicular to the direction in which the tool carrier can be displaced. The clamping beam preferably has at least one section with a relatively low stiffness and at least one section with a relatively high stiffness. The section with the lower stiffness preferably forms a hinge about which the clamping beam can pivot, and the section with the higher stiffness comprises the clamping surface. The clamping beam as a whole advantageously represents a lever arm that can be moved closer to the tool carrier and away from the tool carrier by means of the other clamping elements.

[0039] In yet another preferred embodiment, the clamping mechanism comprises one or more wedges for exerting a clamping force on the tool carrier.

[0040] In a preferred embodiment, the clamping mechanism comprises two wedges that can be moved towards each other or away from each other to increase or decrease the clamping force. To move the two wedges, a threaded shaft is preferably provided that extends through the wedges and engages with corresponding internal threads of the wedges, the threads being oriented in opposite directions. The threaded shaft is advantageously driven by a motor, in particular a DC motor.

[0041] In other preferred embodiments, the clamping element includes a clamping surface extending parallel to the displacement direction of the tool carrier, and the clamping mechanism preferably further includes a spring element that applies a spring force to the clamping element in a direction perpendicular to the displacement direction. In this embodiment, the clamping surface is preferably inclined with respect to the direction of the spring force applied by the spring element. In this way, the force applied by the spring element is advantageously redirected relative to the tool carrier by the inclined surface to clamp the tool carrier against the tool body.

[0042] The clamping mechanism may include at least two rods that are hinged to each other and are used to displace the clamping element in a direction opposite to the direction of the force applied by the spring element on the clamping element. A motor, particularly a DC motor, is preferably provided to move the rods. Thus, the clamping force applied by the clamping mechanism can be actively adjusted by the motor via the rods.

[0043] The clamping surface provided by the clamping mechanism preferably conforms to the outer surface of the tool carrier to improve the holding force.

[0044] The boring head may include a rotation sensor for measuring the rotational position of the drive shaft or the rotational position of the drive spindle, which is used to convert the rotational motion achieved by the motor into the displacement of the tool carrier relative to the tool body. Alternatively or additionally, the boring head may include a position sensor for measuring the position of the tool carrier relative to the tool body. The unexpected rotation and / or displacement of the tool carrier during the boring operation can be detected by means of the rotation sensor and / or the position sensor.

[0045] According to a further improvement of the present invention, the clamping surface of the clamping mechanism - which directly acts on the outer surface of the tool carrier and / or the outer surface of the tool carrier, particularly the outer surface in contact with the clamped surface of the tool carrier - preferably includes a high-friction coating to improve the holding force of the clamping mechanism on the tool carrier. In this way, the clamping effect of the clamping mechanism can be improved.

[0046] According to another further improvement of the present invention, the tool carrier and / or the tool body include a low-friction coating to facilitate the displacement of the tool carrier relative to the tool body. Providing a low-friction coating allows a smaller-sized motor to be used to displace the tool carrier.

[0047] According to yet another further improvement of the present invention, the tool carrier and / or the tool body include a high-friction coating in the area where the tool carrier contacts the tool body to avoid the displacement of the tool carrier relative to the tool body, particularly during the boring operation. It is particularly advantageous to provide a high-friction coating in the area where the tool carrier contacts the tool body to avoid displacement caused by a certain play of the elements of the clamping mechanism.

[0048] It has been recognized that the application of a high-friction coating and / or a low-friction coating on the outer surface of the tool carrier and / or on the outer surface of the tool carrier and / or on the tool body can be provided independently of the type of clamping mechanism used and even of a boring head having a manually displaceable tool carrier. In particular, the above coatings can be used not only in combination with the above active clamping mechanisms, but also in combination with passive clamping mechanisms based, for example, solely on coil springs. In addition, the coatings can even be used in combination with the following boring heads: in which the tool carrier is manually clamped, for example, by means of one or more fixing screws and / or is manually displaced, for example, by means of adjusting screws.

[0049] Accordingly, the present invention also relates to a boring head, in particular to a boring head as described above, which comprises:

[0050] A tool body having a main axis of rotation about which the tool body rotates during a boring operation;

[0051] A tool carrier arranged in or on the tool body and displaceable relative to the tool body;

[0052] A clamping mechanism having a clamping element for applying a clamping force to the tool carrier to prevent displacement of the tool carrier relative to the tool body during a boring operation;

[0053] wherein the clamping mechanism includes a clamping surface acting directly on the outer surface of the tool carrier.

[0054] The clamping surface of the clamping mechanism and / or the outer surface of the tool carrier includes a high-friction coating to increase the holding force of the clamping mechanism, and / or the tool carrier and / or the tool body includes a low-friction coating to facilitate displacement of the tool carrier relative to the tool body, and / or the tool carrier and / or the tool body includes a high-friction coating to prevent unwanted displacement of the tool carrier relative to the tool body.

[0055] Particularly preferred is an embodiment in which the tool carrier includes both a high-friction coating and a low-friction coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings, which are intended to illustrate the preferred embodiments of the present invention and not to limit the preferred embodiments of the present invention. In the drawings,

[0057] Figure 1 A perspective view of a first embodiment of a boring head according to the present invention having an active clamping mechanism is shown;

[0058] Figure 2 ShowsFigure 1 The boring head along the central cross-sectional view of plane II-II as depicted in Figure 3 ;

[0059] Figure 3 Shows Figure 1 The boring head along the cross-sectional view of plane III-III as depicted in Figure 2 ;

[0060] Figure 4 Shows a perspective view of the second embodiment of the boring head of the present invention with an active clamping mechanism;

[0061] Figure 5 Shows the same view as the boring head of Figure 4 , but with the cover of the electronic unit removed;

[0062] Figure 6 Shows Figure 4 The boring head along the central cross-sectional view of plane VI-VI as depicted in Figure 7 ;

[0063] Figure 7 Shows Figure 4 The boring head along the cross-sectional view of plane VII-VII as depicted in Figure 6 ;

[0064] Figure 8 Shows Figure 4 The boring head along the cross-sectional view of plane VIII-VIII as depicted in Figure 6 ;

[0065] Figure 9 Shows a partial cross-sectional view and a partial side view of the third embodiment of the boring head of the present invention with an active clamping mechanism;

[0066] Figure 10 Shows Figure 9 The boring head along the partial cross-sectional view of plane X-X as depicted in Figure 9 ;

[0067] Figure 11 Shows a perspective view of the tool carrier and the active clamping mechanism of the fourth embodiment of the boring head of the present invention;

[0068] Figure 12 Shows the central cross-sectional view of the clamping mechanism as shown in Figure 11 ;

[0069] Figure 13 Shows a perspective view of the tool carrier and the active clamping mechanism of the fifth embodiment of the boring head of the present invention;

[0070] Figure 14shows a first side view of the clamping mechanism and the tool carrier as shown in Figure 13 ;

[0071] Figure 15 shows a second side view of the clamping mechanism and the tool carrier as shown in Figure 13 ; and

[0072] Figure 16 shows a cross-sectional view of a boring head having an integral Figure 13 clamping mechanism and tool carrier. DETAILED DESCRIPTION

[0073] Figures 1 to 3 shows a first embodiment of a boring head of the present invention having an active clamping mechanism and Figures 4 to 8 shows a second embodiment of a boring head of the present invention having an active clamping mechanism. Although the first embodiment allows for machining holes with particularly large diameters, a greater radial force can be exerted on the workpiece to be machined by means of the second embodiment. In Figures 9 to 10 a third inventive embodiment of a boring head having an active clamping mechanism is shown, in Figure 11 and Figure 12 a fourth inventive embodiment is shown and in Figures 13 to 16 a fifth inventive embodiment is shown. In Figures 1 to 16 elements having the same or similar functions are denoted by the same reference numerals in each case.

[0074] As shown in Figure 1 , a first embodiment of a preferred boring head includes a tool body 1 in a substantially cylindrical form. A fastening stud 3 is attached to and integrally formed with the tool body 1. The fastening stud 3 is also in a cylindrical form but has a smaller diameter than the tool body 1. The fastening stud 3 has a central longitudinal hole 4 and a transverse hole 5 intersecting the longitudinal hole 4. The boring head is adapted to be fastened to a boring machine by means of the fastening stud in a manner known to those skilled in the art. During a boring operation, a rotational movement is transmitted from the boring machine to the boring head, and the boring head thus rotates about a main rotational axis R. The main rotational axis R also forms the central longitudinal axis of the tool body 1 in a cylindrical form.

[0075] In a region near the end face of the tool body 1 that is oriented away from the fastening stud 1, the tool body 1 includes a transverse opening 2 (see Figure 2 ). The transverse opening 2 is a through-hole extending perpendicular to the main rotational axis R. Within the transverse opening 2, a tool carrier 6 is arranged in a displaceable but non-rotatable manner relative to the tool body 1. The tool carrier 6 generally has a cylindrical outer shape with a first end face and a second end face. The cylindrical outer shape of the tool carrier 6 is designed to be complementary to the transverse opening 2 of the tool body 1.

[0076] The cutting tool 16 is attached to the first end face of the tool carrier 6. As can be seen in Figure 2 , the cutting tool 16 is in the form of an indexable cutting insert. In order to attach the cutting tool 16 to the tool carrier 6, a tool attachment member 17 is used, and the tool attachment member 17 itself is attached to the first end face of the tool carrier 6 by means of a fastening screw 18. For this purpose, the fastening screw 18 is screwed into the internal thread provided in the central hole 7 of the tool carrier 6. The central hole 7 extends centrally from the first end face through the entire tool carrier 6 to the second end face.

[0077] In order to displace the tool carrier 6 relative to the tool body 1 in the transverse direction, a motor 9 is arranged within the tool body 1 in the region of the second end face of the tool carrier 6. The motor 9 fixed in place relative to the tool body 1 is a DC electric motor having an outer stator 10 and an inner rotor 11. The rotor 11 has a drive shaft 12 extending into the central hole 7 of the tool carrier 6. The drive shaft 12 has an external thread that engages with the internal thread provided in the nut 8. The nut 8 is fixed torsionally within the central hole 7 of the tool carrier 6. In different embodiments, the nut 8 can also be integrally formed with the tool carrier 6. Thus, by rotating the drive shaft 12, due to the engagement of the threads of the drive shaft 12 and the nut 8, the tool carrier 6 can be displaced in the transverse direction within the transverse opening 2.

[0078] By displacing the tool carrier 6 in the transverse direction, the boring head can be adjusted to different boring diameters and the wear of the cutting tool 16 during the boring operation can be compensated for.

[0079] In order to supply electrical energy to the motor 9, one or more batteries 22 are arranged in the battery compartment 21. The battery compartment 21 is arranged between the fastening pin 3 and the transverse opening 2 and the battery compartment 21 can be accessed through a lateral opening provided in the tool body 1. The opening of the battery compartment 21 can be closed by means of a cover 23.

[0080] In order to detect the rotational position of the rotor 11, a rotational sensor 13 is provided. For this purpose, the rotor 11 includes a decoder magnet that is arranged directly adjacent to a decoder printed circuit board (PCB) fixed relative to the tool body 1. Alternatively or additionally, a position sensor can be provided to measure the displacement position of the tool carrier 6 relative to the tool body 1.

[0081] The motor 9 can be accessed from the other lateral opening in the tool body 1. This opening can be closed by means of a cover 15. The rotational sensor 13 is arranged between the motor 9 and the cover 15.

[0082] In order to prevent the tool carrier 6 from being displaced during the boring operation, a clamping mechanism 26 is provided within the clamping compartment 24 of the tool body 1. As Figure 2 andFigure 3 The clamping mechanism 26 shown in the figure is arranged in the region between the tool carrier 6 and the fastening nail 3. The clamping compartment 24 can be accessed via a lateral opening provided in the tool body 1. This lateral opening can be closed by means of a cover 25.

[0083] The clamping mechanism 26 includes active elements in the form of stacked piezoelectric elements 28. If a voltage is applied to the stacked piezoelectric elements 28, the stacked piezoelectric elements 28 expand longitudinally. The direction along which the stacked piezoelectric elements 28 can expand lies in a plane that extends parallel to the displacement direction of the tool carrier 6. In the present embodiment, the expansion direction of the stacked piezoelectric elements 28 extends along a direction perpendicular rather than radial to the displacement direction of the tool carrier 6.

[0084] As Figure 3 shown in the figure, the stacked piezoelectric elements 28 are arranged within a clamping bracket 27 that completely surrounds the stacked piezoelectric elements 28. The arrangement of the stacked piezoelectric elements 28 within the clamping bracket 27 is such that if the stacked piezoelectric elements 28 expand along their longitudinal direction, the clamping bracket 27 extends along the same direction. The extension of the clamping bracket 27 along the longitudinal direction of the stacked piezoelectric elements 28 causes the clamping bracket 27 to contract along a perpendicular direction, i.e., a radial direction with respect to the displacement direction of the tool carrier 6. This radial direction along which the clamping bracket 27 contracts represents the clamping direction. Both the stacked piezoelectric elements 28 and the clamping bracket 27 represent the clamping elements of the clamping mechanism 26. Thus, in the non-activated state of the clamping mechanism 26, i.e., when no voltage is applied to the stacked piezoelectric elements 28, the clamping bracket 27 applies a clamping force on the outer surface of the tool carrier 6. Therefore, the clamping bracket 27 is prestressed. Due to this clamping force, the tool carrier 6 is clamped between the clamping bracket 27 and the inner surface that delimits the lateral opening 2 of the tool body 1, thus preventing the displacement of the tool carrier 6 relative to the tool body 1. The clamping mechanism 26 is brought into the activated state of the clamping mechanism 26 by applying a voltage to the stacked piezoelectric elements 28. Due to the application of this voltage, the clamping bracket 27 contracts along the radial direction of the tool carrier 6 and the tool carrier 6 is released by the clamping mechanism 26, thereby enabling displacement relative to the tool body 1.

[0085] Between the clamping bracket 27 and the outer surface of the tool carrier 6, a clamping pad 30 is provided, and the clamping pad 30 is attached to the clamping bracket 27 by means of an attachment screw 39. The clamping pad 30 includes a clamping surface 31 that is in direct contact with the cylindrical outer surface of the tool carrier 6.

[0086] As can be seen from Figure 3As can be seen, the clamping surface 31 has a rounded shape complementary to the outer surface of the tool carrier 6. In this way, the friction between the clamping pad 30 and the tool carrier 6 can be improved.

[0087] To adjust the clamping force of the clamping mechanism 26, an adjusting mechanism 32 is provided. The adjusting mechanism 32 includes an adjusting wedge 34. The clamping bracket 27 is arranged between the adjusting wedge 34 and the tool carrier 6. The adjusting wedge 34 can be radially displaced within the tool body 1, and depending on the position of the adjusting wedge 34, the clamping force exerted by the clamping bracket 27 is greater or smaller. The position of the adjusting wedge relative to the clamping bracket 27 can be adjusted by an adjusting screw 33 and a counter screw 35. An adjusting barrel 36 is provided between the adjusting wedge 34 and the clamping bracket 27, and the adjusting barrel 36 is attached to the clamping bracket 27 by means of an attachment screw 38. The adjusting barrel 36 is arranged within an adjusting bracket 37. A lateral screw 40 is screwed laterally through the adjusting bracket 37 to fasten the adjusting barrel 36 ( Figure 2 ). If the cover 25 is removed, the lateral screw 40 can be accessed from the outside.

[0088] To control the motor 9 and the clamping mechanism 26, an electronic unit 19 is provided within the tool body 1 (see Figure 1 ). The electronic unit 19 is in the form of a printed circuit board (PCB) and includes, for example, at least a processor and a data storage module. The electronic unit 19 can be accessed via a lateral opening of the tool body 1. This lateral opening can be closed by means of a cover 20 ( Figure 3 ). The electronic unit 19 can include a wireless unit to transmit data to and / or receive data from an external device and / or to control signals to and / or from an external device, the external device being, for example, a desktop computer or a tablet or a smartphone or a smartwatch. For example, this transmission can be carried out via the Bluetooth standard.

[0089] In Figures 4 to 8 a second embodiment of the boring head according to the present invention is shown, and this second embodiment will be described below.

[0090] Compared with the Figures 1 to 3 embodiment, Figures 4 to 8 the embodiment is suitable for machining holes with a smaller diameter.

[0091] As can be seen from Figures 4 to 8 , the boring head according to this embodiment also includes a tool body 1 having fastening pins 3 and a lateral opening 2, and a radially displaceable cylindrical tool carrier 6 is arranged in the lateral opening 2. Compared with Figures 1 to 3In contrast to the embodiment, the cutting tool here is not attached to the end face of the tool carrier 6, but is attached to the tool attachment hole 41 via a tool holder. The tool attachment hole 41 extends through the tool carrier 6 along the main rotation axis R (see Figure 6 ). Note that the tool holder and the cutting tool are not shown in Figures 4 to 8 . For this purpose, the tool holder includes a cylindrical rod-shaped member that is introduced into the tool attachment hole 41 through a central opening provided on the side of the tool body 1 opposite to the fastening screw 3. To fix the tool holder to the tool carrier 6, a fastening screw 42 is provided that is screwed into one end of the tool carrier 6. The corresponding end of the tool carrier 6 can be closed by means of a cover 43.

[0092] As Figures 4 to 8 shown, the boring head is particularly suitable for applying high radial cutting forces to the machining part. To cool the cutting tool and the machining part during the boring operation, the coolant can be brought to the cutting tool through the boring head. For this purpose, a longitudinal hole 4 extends through both the fastening screw 3 and the tool body 1. A plurality of corresponding seals are provided in the boring head to prevent the coolant from escaping during the boring operation.

[0093] In another embodiment, the tool body 1 can also have an additional through-channel that extends from the fastening screw 3 to the outside of the tool carrier 6 and extends to the end face of the tool body 1 to guide the coolant to the cutting tool. The advantage of providing a separate through-channel in the tool body 1 is that fewer seals are required between the movable parts. In addition, other advantages of guiding the coolant through the (dispersedly arranged) through-channels rather than through the centrally arranged longitudinal hole 4 are that the stacked piezoelectric elements 28 can be arranged centrally, i.e., intersecting the main rotation axis R, to minimize the centrifugal force acting on the stacked piezoelectric elements 28 during the boring head operation.

[0094] To achieve higher power for radially displacing the tool carrier 6 within the lateral opening 2, in this embodiment, the motor 9 is arranged such that the rotation axis of the motor 9 extends perpendicular to the displacement direction of the tool carrier 6. Therefore, the motor 9 can have a relatively large size because the motor 9 is arranged in the region of the tool body 1 between the fastening screw 3 and the lateral opening 2. In addition, a higher displacement force is achieved by providing a transmission device - in this case a worm gear transmission. The worm gear transmission includes a worm 44 and a worm wheel 49.

[0095] As Figure 7As shown, the first drive spindle 45 is torsionally attached to the drive shaft 12 of the motor 9. The first drive spindle 45 extends parallel to the main rotation axis R of the tool body 1. The screw 44 is torsionally attached to the first drive spindle 45. Of course, the first drive spindle 45 and the worm 44 can also be integrally formed together. The first drive spindle 45 and the worm 44 are arranged in the support tube 47. A plurality of supports 51 are provided in the support tube 47 to hold the first drive spindle 45.

[0096] The worm 44 engages with the worm wheel 49, and the worm wheel 49 is torsionally attached to the second drive spindle 46. Of course, it is also possible to produce the second drive spindle 46 and the worm wheel 49 together as an integral part. The second drive spindle 46 is held by a plurality of supports 48 arranged in the transmission housing 50 and is held by the spindle fastening plate 53. The spindle fastening screw 54 passes through the spindle fastening plate 53 and reaches the end of the second drive spindle 46. The transmission housing 50 is inserted into the lateral opening 2 of the tool body 1.

[0097] The nut 8 is torsionally attached to the second drive spindle 46. The nut 8 can also be integrally formed with the second drive spindle 46. The nut 8 includes an external thread that engages with an internal thread provided in the central hole of the tool carrier 6. Thus, the rotation achieved by the motor 9 is transmitted to the first drive spindle 45, via the worm gear transmission 44, 49 to the second drive spindle 46 and from the second drive spindle 46 to the nut 8. Due to the threaded engagement of the nut 8 with the tool carrier 6, the rotation of the nut 8 causes the displacement of the tool carrier 6 within the lateral opening 2.

[0098] Through a common lateral opening provided in the tool body 1, it is possible to access the compartment of the tool body 1 in which the motor 9 is arranged and the lateral area of the lateral opening 2 in which the transmission housing 50 and the worm gear transmission 44, 49 are arranged. This opening can be closed by a cover 52. The cover 52 is also used to hold the spindle fastening plate 53.

[0099] In Figures 4 to 8 the clamping mechanism 26 used in the embodiment of Figure 8 can be seen particularly well in Figures 1 to 3The clamping mechanism 26 of the embodiment is similar. This clamping mechanism also includes stacked piezoelectric elements 28 which expand when a voltage is applied. However, here a clamping beam 55 is provided instead of the clamping bracket 27 to apply a clamping force to the tool carrier 6. The clamping beam 55 has end sections with a relatively low stiffness, which is achieved by a thinner design of the clamping beam 55 in the corresponding sections. This end section of the clamping beam 55 is attached to the tool body 1 by means of attachment screws 56. The clamping beam 55 as a whole forms a rod that can pivot relative to the tool carrier 6 about the end section of the clamping beam. The clamping beam 55 extends along the circumference of the tool carrier 6, or in other words, along a direction perpendicular to both the displacement direction and the radial direction of the tool carrier 6.

[0100] The clamping beam 55 has a rounded clamping surface 31 which, in the non-activated state of the clamping mechanism 26, bears directly against the cylindrical outer surface of the tool carrier 6. Thus, the tool carrier 6 is clamped between the clamping beam 55 and the inner surface of the lateral opening 2 of the tool body to prevent displacement of the tool carrier 6 relative to the tool body 1 during the boring operation.

[0101] Similar to the foregoing embodiment, the radius of the clamping surface 31 is adapted to the outer surface of the tool carrier 6.

[0102] To activate the clamping mechanism 26, a voltage is applied to the stacked piezoelectric elements 28 by the electronic unit 19. Thus, the stacked piezoelectric elements 28 expand and push the clamping beam 55 away from the tool carrier 6. The stacked piezoelectric elements 28 push the clamping beam 55 in an end region opposite to the end region where the clamping beam 55 is attached to the tool body 1 by means of the attachment screws 56.

[0103] The stacked piezoelectric elements 28 are fixedly attached to the clamping beam 55 by one end. The clamping mechanism 26 and in particular the clamping beam 55 can be accessed via a lateral opening provided in the tool body 1. The opening can be closed by means of a cover 25. A spring 57 and a first adjusting nut 58 can be provided between the inner surface of the cover 25 or the tool body 1 and the clamping beam 55. The spring 57 is arranged such that the spring 57 supports the clamping of the tool carrier 6 by the clamping beam 55 in the non-activated state of the clamping mechanism 26. A second adjusting nut 59 can be provided between the other end of the stacked piezoelectric elements 28 and the inner surface of the tool body 1 or another cover 60. By means of the adjusting nut 58 and the adjusting nut 59, the clamping force exerted by the clamping mechanism 26 on the tool carrier 6 can be adjusted.

[0104] To increase the holding force of the clamping beam 55 relative to the tool carrier 6, the clamping surface 31 and / or the corresponding portions of the outer surface of the tool carrier 6 preferably include a high-friction coating 61. The high-friction coating 61 is preferably applied to the clamping beam 55 and / or the tool carrier 6 by thermal spraying, particularly by atmospheric plasma spraying. Particularly preferred materials for the high-friction coating 61 are alumina (Al2O3), titanium oxide (TiO2), or a combination of these materials. The high-friction coating is also preferably provided on the clamping surface 31 of the clamping pad 30 of the boring head according to the embodiment as shown in Figures 1 to 3 and / or on the corresponding portions of the outer surface of the tool carrier 6.

[0105] To increase the displacement ability of the tool carrier 6 relative to the tool body 1, the corresponding contact surfaces of the tool carrier 6 and / or the tool body 1 preferably include a low-friction coating 62. Particularly preferred materials for the low-friction coating 62 are tungsten-containing materials, particularly materials having a matrix of carbon and hydrogen and inclusions containing tungsten, such as those of C. The low-friction coating 62 is preferably applied to the tool carrier 6 and / or the tool body 1 by a sputter deposition process, particularly by reactive (cathodic) sputtering, i.e., physical vapor deposition (PVD) sputtering. If the coating material contains tungsten, the reactive gas preferably contains carbon. The low-friction coating is also preferably provided on the outer surface of the tool carrier 6 of the boring head according to the embodiment as shown in Figures 1 to 3 and / or on the corresponding contact surfaces of the tool body 1.

[0106] Alternatively, the coating 62 can also be a high-friction coating. Applying a high-friction coating 62 on the tool carrier 6 and / or on the tool body 1 would be advantageous to avoid unwanted displacement of the tool carrier 6 relative to the tool body 1 during the operation of the boring head. Such unwanted displacement can be caused, for example, by a certain play of the elements of the clamping mechanism 26 within the tool body 1. Particularly preferred materials for the high-friction coating 62 are alumina (Al2O3), titanium oxide (TiO2), or a combination of these materials.

[0107] In Figure 9 and Figure 10 a third embodiment of the boring head according to the present invention is shown. Although the principle of displacing the tool carrier 6 relative to the tool body 1 is similar to that of the embodiment as shown in Figures 1 to 3 , the principle of the clamping mechanism 26 is similar to that of the embodiment as shown in Figures 4 to 8 .

[0108] As shown in Figure 9As can be seen, the tool carrier 6 includes a tool attachment hole 41 that extends along the main rotation axis R and is used to attach the rod-shaped tool holder to the cutting tool. To laterally displace the tool carrier 6, a motor 9 having a stator 10 and a rotor 11 is arranged in a lateral opening 2 of the tool body 1 near the end face of the tool carrier 6. A nut 8 with internal threads is fixed in a torsion-resistant manner in the central hole of the tool carrier 6. As in Figures 1 to 3 In the embodiment, the rotational movement of the motor 9 is converted into a radial displacement of the tool carrier 6 via a threaded drive shaft that engages with the internal threads of the nut 8.

[0109] In Figure 10 The clamping mechanism 26 of this embodiment is shown. Similar to the embodiment in Figure 8 , the clamping beam 55 serves as a clamping element that directly contacts the tool carrier 6 in the clamped state. The clamping beam 55 is attached to the tool body 1 by a first end in a region near the end face of the tool body 1 by means of an attachment screw 56. The second end of the clamping beam 55 is biased by a spring 57 such that the rounded clamping surface 31 of the clamping beam 55 presses against the tool carrier 6. To release the clamping force, stacked piezoelectric elements 28 extending in a vertical direction relative to the displacement direction of the tool carrier can be activated to press the clamping beam 55 away from the tool carrier 6.

[0110] In this embodiment, the stacked piezoelectric elements 28 are arranged between two leaf springs that extend laterally along the entire longitudinal extension of the stacked piezoelectric elements 28. The leaf springs can of course also be replaced by, for example, a single helical spring. The leaf springs are used to apply a pre-tightening force on the stacked piezoelectric elements 28. In this way, unwanted movement of the stacked piezoelectric elements 28, especially in the unactivated state of the piezoelectric elements, can be avoided.

[0111] Figures 11 to 12 The clamping mechanism 26 of a fourth embodiment of the boring head according to the present invention is shown.

[0112] The motor for radially displacing the tool carrier 6 relative to the tool body 1 is not shown in Figure 11 and Figure 12 . The principle of displacing the tool carrier 6 can be based on any of the principles indicated as in the embodiment regarding Figures 1 to 10 . The same is true for the embodiment shown in Figures 13 to 16 .

[0113] To clamp the tool holder 6 to prevent unwanted displacement during the operation of the boring head, the clamping mechanism 26 includes clamping jaws 67 and 68 (see Figure 11 ). The clamping jaws 67, 68 are arranged parallel to each other such that a gap is formed between the clamping jaws. The first clamping jaw 67 abuts against the inner surface of the tool body 1 (inFigure 11 and Figure 12 is not shown in Figure 12 ), and the second clamping jaw 68 abuts against the outer surface in the recess 75 of the tool carrier 6.

[0114] As can be seen in Figure 12 Figure 12 , the clamping jaws 67, 68 have inclined surfaces facing the gap. The inclined surfaces are formed such that the gap between the clamping jaws 67, 68 widens from the middle along an axis extending parallel to the main rotational axis R in two opposite directions. Thus, in the cross-sectional view as shown in Figure 12 Figure 12 , the gap formed between the clamping jaws 67, 68 has the shape of two wedges facing each other, wherein the narrow middle section widens in two opposite directions.

[0115] The threaded shaft 66, which is attached in a torsion-resistant manner via the connector 65 to the drive shaft 64 of the DC motor 63, extends in a direction parallel to the main rotational axis R and extends through the gap formed between the inclined surfaces of the clamping jaws 67, 68. Two wedges 69, 70 are arranged between the clamping jaw 67 and the clamping jaw 68, and the threaded shaft 66 extends through the two wedges 69, 70. The wedges 69, 70 are arranged above and below the narrow middle section of the gap between the clamping jaws 67, 68 such that the outer shape of the wedges 69, 70 widens in the same direction as the gap. Each of the wedges 69, 70 includes a threaded through-hole. The internal threads of the wedges 69, 70 are oriented in opposite directions. Corresponding external threads that mate with the threads of the wedges 69, 70 are provided on the threaded shaft 66.

[0116] Therefore, since the first wedge 69, for example, has a left-hand thread and the second wedge 70 has a right-hand thread, rotation of the threaded shaft 66 in a first direction causes the wedges 69, 70 to move towards each other and rotation of the threaded shaft 66 in another second direction causes the wedges 69, 70 to move away from each other, i.e., away from the narrow middle section of the gap formed by the clamping jaws 67, 68. In the first case, i.e., when the wedges 69, 70 move away from each other, the clamping jaws 67, 68 can move towards each other and the clamping pressure on the tool carrier 6 is released. In the second case, when the wedges 69, 70 move towards each other, the clamping jaws 67, 68 are pressed away from each other such that the first clamping jaw 67 abuts against the inner surface of the tool body 1 and the second clamping jaw abuts against the tool carrier 6. Thus, by activating the DC motor 63 to rotate the threaded shaft 66, the clamping force on the tool carrier 6 can be increased or decreased. To rotate the threaded shaft 66, an energy flow from a power source, such as a battery (not shown in Figure 11 and Figure 12 Figure 12 ) to the DC motor 63 is required. The free end of the threaded shaft 66 is held in the ball bearing 72.

[0117] In order to minimize the friction between the wedges 69, 70 and the clamping jaws 67, 68 during rotation of the threaded shaft 66, needle bearings 71 are preferably provided between each inclined surface of the clamping jaws 67, 68 and the respective wedges 69, 70. The needle bearings 71 are held in the gap between the clamping jaws 67, 68 by means of stop elements 73.

[0118] In order to better guide the clamping jaws 67, 68 and to prevent the clamping jaws 67, 68 from getting stuck in the clamped state, a pull-back strip 74 can be provided, the pull-back strip 74 having a certain elasticity and surrounding the two clamping jaws 67, 68 in the region of the narrow middle section of the gap. In addition, guide pins can be provided to ensure proper alignment of the clamping jaws 67, 68. In the present embodiment, guide pins are arranged on each side of the threaded shaft 66 between the two pull-back strips 74. The guide pins are attached to the second clamping jaw 68 and extend through openings provided in the first clamping jaw 67.

[0119] Similar to Figures 4 to 8 the embodiment shown in, a high-friction coating 61 can be applied to the second clamping jaw 68 in the region where the outer surface of the second clamping jaw 68 contacts the tool carrier 6. In this way, the clamping effect can be improved. In the region where the outer surface of the tool carrier 6 contacts the tool body 1, particularly in the region opposite the second clamping jaw 68, a high-friction coating or a low-friction coating 62 can be provided on the tool carrier 6 and / or on the tool body 1.

[0120] The arrangement of the inclined surfaces of the wedges 69, 70 and the clamping jaws 67, 68 and the threaded engagement between the threaded shaft 66 and the wedges 69, 70 allow a relatively high clamping force to be applied to the tool carrier 6 by means of a relatively small DC motor 63. The clamping force is maintained as long as the DC motor 63 remains inactive.

[0121] In the fifth embodiment of the boring head of the present invention as shown in Figures 13 to 16 , other variants of an active clamping mechanism 26 with actively adjustable clamping force are shown.

[0122] The clamping mechanism 26 includes a clamping member 81 which forms a clamping element that comes into direct contact with the tool carrier 6 during the clamped state. The clamping member 81 includes a flat clamping surface 31 which extends parallel to the displacement direction of the tool carrier 6 and the clamping surface 31 is arranged in the region of a recess 75 formed in the cylindrical circumference of the tool carrier 6. As shown in Figure 15 and Figure 16As can be seen, the flat surfaces of the recess 75 and the clamping member 81 are both inclined with respect to the main rotation axis R of the tool body 1. Due to the inclined surface of the clamping member 81, the clamping member 81 forms a wedge as a whole. The helical spring 82 is attached to the end face of the clamping member 81, so that the clamping member 81 is pressed in the direction of the fastening nail 3 along the main rotation axis R. Due to the inclination of the clamping surface 31 with respect to the main rotation axis R, the clamping member 81 is pressed against the tool carrier 6 by the spring 82. In this way, the tool carrier 6 is clamped between the clamping member 81 and the inner surface of the tool body 1 on the opposite side of the tool carrier 6 with respect to the clamping member 81. In other words, the inclination of the flat contact surface of the recess 75 and the inclination of the flat contact surface of the clamping member 81 cause the redirection of the force of the spring 82 to clamp the tool carrier 6 between the clamping member 81 and the inner surface of the tool body 1 arranged on the opposite side of the tool carrier 6.

[0123] To prevent the tool carrier 6 from undesired rotation about its longitudinal axis during the clamping process due to the inclined clamping surface 31, an anti-rotation bolt 83 is provided. The anti-rotation bolt 83 abuts against the flat outer surface of the tool carrier 6 provided in the recess 75 (see Figure 13 and Figure 14 ) through a flat surface.

[0124] As in all the embodiments described before and after, a high-friction coating 61 can be applied to the contact surface of the clamping member 81 and / or the contact surface of the tool carrier 6 to further avoid the undesired displacement of the tool carrier 6 relative to the tool body 1. One or both of the contact surface of the tool carrier 6 and the contact surface of the tool body 1 on the opposite side of the clamping member 81 can include a high-friction coating or a low-friction coating 62 to similarly avoid the undesired displacement of the tool carrier 6 relative to the tool body 1 due to, for example, an inevitable certain play of the elements of the clamping mechanism 26, or to facilitate the displacement of the tool carrier 6, for example, when adjusting the boring diameter.

[0125] To release the clamping force, a DC motor 63 is provided, which has a drive shaft 64 attached to a threaded shaft 66 in a torsion-resistant manner. The threaded shaft 66 engages with the internal thread of the connecting member 76, such that rotation of the DC motor 63 causes a displacement of the connecting member 76 in a direction parallel to the displacement direction of the tool carrier 6. A first rod 78 is articulated to the connecting member 76 by a first end and to the clamping member 81 by a second end. An articulation portion 80 is provided approximately in the middle of the first rod 78, wherein a first end of a second rod 79 is pivotally attached to the first rod 78. A second end of the second rod 79 is pivotally attached to an attachment member 77 fixedly attached to the tool body 1. If the clamping member 81 is in the released state of the clamping member 81, both the first rod 78 and the second rod 79 extend in a direction perpendicular to the displacement direction of the tool carrier 6 and approximately parallel to the main rotation axis R of the tool body 1.

[0126] In use, if the connecting member 76 moves away from the DC motor 63 (to the Figure 14 right in the figure), the clamping member 81 is pulled along the main rotation axis R towards the fastening nail 3 by the rods 78, 79 and thus abuts against the tool carrier 6 by the inclined contact surface of the clamping member 81. Accordingly, the clamping force increases. If the connecting member 76 moves towards the DC motor 63 by the DC motor 63 (to the Figure 14 left in the figure), the clamping member 81 is pressed downwards towards the spring 82 by the rods 78, 79 and the clamping of the tool carrier 6 is released. Accordingly, the two rods 78, 79 together act as a "knee joint", such that the displacement of the connecting member 76 is converted into a displacement of the clamping member 81 along the main rotation axis R.

[0127] From the above description, it can be seen that in the case of the clamping mechanism 26 of the Figures 13 to 16 embodiment, the clamping force acting on the tool carrier 6 can be actively adjusted by means of the DC motor 63. If the DC motor 63 idles, the clamping force remains unchanged.

[0128] The arrangement of the rods 78, 79 and the threaded engagement between the threaded shaft 66 and the connecting member 76 allow a relatively high reaction force (against the force of the spring 82) to be exerted on the clamping member 81 by means of a relatively small DC motor 63.

[0129] The present invention is of course not limited to the foregoing embodiments and can be modified in various ways. For example, the stacked piezoelectric elements 28 can easily be replaced by, for example, a DC drive in all corresponding embodiments. The displaceability of the tool carrier 6 relative to the tool body 1 does not necessarily have to be transverse, but can also be parallel to the main rotational axis R. Furthermore, for example, in order to displace the tool carrier 6, the motor 6 does not necessarily have to be an electric motor, but can also be in the form of a piezoelectric motor or a hydraulic motor. For example, the main power grid can be used instead of the battery 22 to supply the required electrical energy to the clamping mechanism via, for example, sliding contacts or inductive energy transfer. Various other modifications can be made.

[0130] List of reference numerals

[0131] 1 Tool body 30 Clamping pad

[0132] 2 Transverse opening 31 Clamping surface

[0133] 3 Fastening nail

[0134] 4 Longitudinal hole 32 Adjusting mechanism

[0135] 5 Transverse hole 33 Adjusting screw

[0136] 34 Adjusting wedge

[0137] 6 Tool carrier 35 Reverse screw

[0138] 7 Central hole 36 Adjusting barrel

[0139] 8 Nut 37 Adjusting bracket

[0140] 38 Attachment screw

[0141] 9 Motor 39 Attachment screw

[0142] 10 Stator 40 Lateral screw

[0143] 11 Rotor

[0144] 12 Drive shaft 41 Tool attachment hole

[0145] 42 Fastening screw

[0146] 13 Rotation sensor 43 Cover

[0147] 15 Cover

[0148] 16 Cutting tool 44 Worm

[0149] 17 Tool attachment part 45 First drive spindle

[0150] 18 Fastening screw 46 Second drive spindle

[0151] 19 Electronic unit 47 Support pipe

[0152] 20 Cover 48 Support

[0153] 21 Battery compartment 49 Worm gear

[0154] 22 Battery 50 Transmission housing

[0155] 23 Cover 51 Support

[0156] 52 Cover

[0157] 24 Clamping compartment 53 Spindle fastening disc

[0158] 25 Cover 54 Spindle fastening screw

[0159] 26 Clamping mechanism

[0160] 27 Clamping bracket 55 Clamping beam

[0161] 28 Stacked piezoelectric elements 56 Attachment screw

[0162] 57 Spring 72 Ball bearing

[0163] 58 Adjusting nut 73 Stop element

[0164] 59 Adjusting nut 74 Pull-back bar

[0165] 60 Cover 75 Recess

[0166] 61 High-friction coating

[0167] 62 High-friction coating or low-friction coating 76 Connector

[0168] 77 Attachment part

[0169] 63 DC motor 78 First rod

[0170] 64 Drive shaft 79 Second rod

[0171] 65 Connector 80 Hinge part

[0172] 66 Threaded shaft 81 Clamping piece

[0173] 67 Clamping jaw 82 Spring

[0174] 68 Clamping jaw 83 Anti-rotation bolt

[0175] 69 Left-handed threaded wedge

[0176] 70 Right-handed threaded wedge R main axis of rotation

[0177] 71 Needle roller bearing

Claims

1. A boring head, comprising: A tool body (1) having a main rotation axis about which the tool body (1) rotates during a boring operation; A tool carrier (6) arranged in or on the tool body (1); A first motor (9) for displacing the tool carrier (6) relative to the tool body (1) in a displacement direction; and A clamping mechanism (26) having clamping elements (27, 55, 68, 81) for applying a clamping force to the tool carrier (6) to prevent displacement of the tool carrier (6) relative to the tool body (1) during a boring operation; Wherein the clamping mechanism (26) is an active clamping mechanism that applies an actively adjustable clamping force in a clamping direction such that when the clamping mechanism (26) is activated and / or in an activated state of the clamping mechanism, an energy flow occurs from an energy source to the clamping mechanism (26), And wherein the clamping mechanism (26) is based on the piezoelectric effect and includes at least one piezoelectric element (28), Characterized in that The first motor (9) is an electric motor having a stator (10) and a rotor (11), and the first motor (9) has a main drive axis defined by the rotation of the rotor (11) during operation of the first motor (9), and the main drive axis extends parallel to the displacement direction, Wherein the clamping element has the form of a clamping bracket that at least partially surrounds the at least one piezoelectric element (28) of the clamping mechanism (26) such that an expansion of the at least one piezoelectric element (28) along a first direction is converted into a contraction of the clamping bracket along a perpendicular second direction, and The clamping element is adapted to move away from the tool carrier (6) in the second direction by virtue of the expansion of the piezoelectric element (28) along the first direction caused by a voltage applied to the piezoelectric element (28).

2. The boring head according to claim 1, wherein, An energy storage device is provided to supply the energy required to activate the clamping mechanism (26).

3. The boring head according to claim 2, wherein, The energy storage device is an electrical energy storage device (22).

4. The boring head according to any one of claims 1 to 3, wherein, The clamping mechanism (26) has an idle state and an activated state, in the idle state, the tool carrier (6) is clamped, and in the activated state, the tool carrier (6) can be displaced relative to the tool body (1).

5. The boring head according to any one of claims 1 to 3, wherein, The clamping mechanism (26) has an idle state and an activated state, in the idle state, the clamping force acting on the tool carrier (6) remains unchanged, and in the activated state, the clamping force acting on the tool carrier (6) increases or decreases.

6. The boring head according to any one of claims 1 to 3, wherein, The clamping bracket completely surrounds the at least one piezoelectric element (28) of the clamping mechanism (26).

7. The boring head according to any one of claims 1 to 3, wherein, The clamping mechanism (26) includes a clamping surface (31) that acts directly on the outer surface of the tool carrier (6), and wherein the clamping surface (31) is adapted to the outer surface of the tool carrier (6).

8. The boring head according to any one of claims 1 to 3, wherein, The rotor (11) includes a drive shaft (12) with an external thread, wherein the tool carrier (6) includes a hole (7) with an internal thread, or a nut attached to the tool carrier (6) in a torsion-resistant manner has an internal thread, and wherein the external thread of the drive shaft (12) engages with the internal thread such that the rotational movement of the rotor (11) achieved by the first motor (9) is converted into a displacement of the tool carrier (6) relative to the tool body (1).

9. The boring head according to any one of claims 1 to 3, wherein, The clamping mechanism (26) includes a clamping surface (31) that acts directly on the outer surface of the tool carrier (6), and wherein the clamping surface (31) of the clamping mechanism (26) and / or the outer surface of the tool carrier (6) includes a high-friction coating (61) to increase the holding force of the clamping mechanism (26).

10. The boring head according to any one of claims 1 to 3, wherein, The tool carrier (6) and / or the tool body (1) includes a low-friction coating (62) to facilitate the displacement of the tool carrier (6) relative to the tool body (1).

11. The boring head according to any one of claims 1 to 3, wherein, The tool carrier (6) and / or the tool body (1) includes a high-friction coating (61) in the area where the tool carrier (6) contacts the tool body (1) to prevent the tool carrier (6) from displacing relative to the tool body (1).

12. The boring head according to any one of claims 1 to 3, wherein, The tool carrier (6) is displaceable relative to the main rotation axis of the tool body (1) in a transverse direction.

13. The boring head according to any one of claims 1 to 3, wherein, The boring head includes a rotation sensor (13) for measuring the rotational position of the drive shaft (12) or the rotational position of the drive spindle (45, 46), the drive shaft (12) or the drive spindle (45, 46) being for converting the rotational movement achieved by the first motor (9) into a displacement of the tool carrier (6) relative to the tool body (1), and / or wherein the boring head includes a position sensor for measuring the position of the tool carrier (6) relative to the tool body (1).

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