Boring bar, and non-rotating boring tool and boring device including such a boring bar

Abstract

The boring bar (2) for a non-rotary boring tool includes an elongated main portion (10) configured for attachment to a support structure of a metal cutting machine, a front portion (12) arranged to support a tool portion (4) equipped with a cutting element (5), and at least one damping module (14) disposed between a front end (10a) of the main portion (10) and a rear end (12b) of the front portion (12) and equipped with an electrically controlled vibration actuator (16) configured to generate a vibratory force for active vibration damping of the boring bar. The front portion (12) is connected to the main portion (10) via the at least one damping module (14), and the main portion, front portion, and at least one damping module together form an elongated body (6), the at least one damping module (14) constituting a length section of the elongated body.

Description

[Technical Field]

[0001] The present invention relates to a boring bar according to the preamble of independent claim 1. The invention also relates to a non-rotating boring tool and a boring device comprising such a boring bar. [Background technology]

[0002] Cantilever boring bars with cutting elements at their free ends may be used to perform various types of machining operations, such as internal or external turning on a rotating workpiece of metallic material. During a machining operation, the cutting element extends perpendicular to the axis of rotation of the workpiece and is subjected to cutting forces from the rotating workpiece, including radial forces directed along a line intersecting the axis of rotation and the point of contact between the cutting element and the workpiece, and tangential forces directed perpendicular to the radial forces and tangential to the surface of the workpiece at the point of contact between the cutting element and the workpiece. These mutually perpendicular cutting forces can induce vibrations in the boring bar, which can then cause noise, imperfect surface finishes on the workpiece, tool failure, and other undesirable effects.

[0003] Various types of active damping systems have been developed to reduce vibrations of the boring bar caused by cutting forces on the cutting elements at the outer end of the boring bar during machining of a workpiece. Such active damping systems may include at least one vibration sensor for sensing vibrations of the boring bar and at least one electrically controlled vibration actuator for generating a vibratory force in the boring bar, the vibration actuator being controlled by an electronic control unit, depending on measurement signals from the vibration sensor(s), to induce counter-vibrations in the boring bar that interfere with and thereby cancel the vibrations induced in the boring bar by the cutting forces.

[0004] An active damping system of the above type is disclosed in US Pat. No. 5,170,103 A, in which a vibration actuator is housed in a cavity inside the boring bar.

[0005] An active damping system may include one or more vibration actuators mounted on the machine tool external to the ram for damping vibrations in the ram, such as those disclosed in EP 3511112 A1.

[0006] SUMMARY OF THE INVENTION It is an object of the present invention to provide a new, advantageously designed boring bar of the above type. Summary of the Invention

[0007] According to the invention, this object is achieved by means of a boring bar having the features defined in claim 1.

[0008] The boring bar according to the present invention is configured for use with a non-rotary boring tool, an elongated main portion configured for attachment to a support structure of a metal cutting machine, the main portion having a rear end and an opposite front end; a front portion having a rear end opposite the front end of the main portion and an opposite front end, the front end of the front portion being positioned to support a tool portion having a cutting element; at least one damping module disposed between the forward end of the main section and the aft end of the forward section; Including, At least one damping module has an aft end facing the main portion, an opposite forward end facing the forward portion, and a central axis extending between the aft and forward ends of the damping module.

[0009] At least one damping module is provided with an electrically controlled vibration actuator for active vibration damping of the boring bar, the actuator being configured to generate a vibratory force. The front portion of the boring bar is connected to a main portion of the boring bar via at least one damping module, the main portion, the front portion, and the single or multiple damping modules together forming an elongated body, the at least one damping module constituting a length section of the elongated body. Thus, the main portion, the at least one damping module, and the front portion constitute separate, continuously arranged length sections of the elongated body as viewed in the longitudinal direction of the boring bar. Thus, the vibration actuator may be integrated into the elongated body of the boring bar by first placing the actuator in a casing of the associated damping module and then fixing the damping module between the main portion and the front portion of the boring bar, which facilitates assembly of the boring bar. Furthermore, by housing one actuator in a separate damping module, the damping characteristics can be easily tailored to specific needs by changing the damping module without having to change other parts of the boring bar. The number of actuators in the boring bar can be easily changed, depending on specific needs, by changing the number of damping modules located between the main and front sections of the boring bar. The placement of one actuator in a separate damping module located between the main and front sections of the boring bar also facilitates placing the actuator near the front end of the boring bar, which is a preferred location for the actuator due to its proximity to the cutting elements where boring bar vibrations are generated. Furthermore, the use of a separate damping module makes it easy to tailor this portion of the boring bar to the actuator requirements for the purpose of maximizing the actuator's damping mass and stroke.

[0010] The at least one damping module is preferably arranged with its central axis aligned or substantially aligned with the longitudinal axis of the main section. This allows for centering of the at least one damping module on the boring bar, which simplifies the calculations used in controlling the actuators of the at least one damping module, thereby providing a damping system that is accurate, fast, and well-responsive to and able to damp vibrations in the boring bar. However, the at least one damping module may alternatively be arranged with its central axis not aligned with the longitudinal axis of the main section.

[0011] The at least one damping module preferably has the same cross-sectional peripheral shape as that of the main part and / or the front part. Furthermore, the main part and / or the front part and / or the at least one damping module are suitably cylindrical, preferably cylindrical.

[0012] According to one embodiment of the invention, the outer periphery of the main part and the outer periphery of the at least one damping module are flush with each other or substantially flush with each other, whereby the elongated body of the boring bar may be designed with a smooth outer periphery surface.

[0013] According to another embodiment of the invention, at least one damping module is clamped between the main section and the front section, preferably using tie rods extending through passages in the at least one damping module. This allows single or multiple damping modules to be simply and securely fixed between the main section and the front section of the boring bar. Each one of the tie rods may have a first end fixed to the main section and an opposite second end fixed to the front section.

[0014] According to another embodiment of the invention, the actuator of at least one damping module is a single-axis actuator configured to generate a vibratory force parallel or at least substantially parallel to a single actuation axis of the actuator. In this case, the actuator may be arranged in the associated damping module such that the actuation axis of the actuator extends in a cross section perpendicular to the central axis of the damping module, which implies that the actuator is arranged with its actuation axis intersecting the longitudinal axis of the elongated body. In this case, the actuation direction of the actuator relative to the point of contact between the cutting element and the workpiece may be adjusted, if necessary, by adjusting the rotational position of the associated damping module relative to the front of the boring bar.

[0015] According to another embodiment of the invention, the boring bar comprises at least two damping modules of the above-described type arranged in series with one another between the front end of the main section and the rear end of the front section. This allows for simple integration of several vibration actuators into the elongated body of the boring bar. The at least two damping modules are preferably arranged adjacent to one another. However, some kind of intermediate element may alternatively be arranged between the at least two damping modules. The front section of the boring bar is preferably arranged with its rear end in abutment with the front end of the frontmost of the at least two damping modules. However, some kind of intermediate element may alternatively be arranged between the front section and the frontmost damping module. The rearmost of the at least two damping modules is preferably arranged with its rear end in abutment with the front end of the main section. However, some kind of intermediate element may alternatively be arranged between the main section and the rearmost damping module.

[0016] To facilitate manufacturing of the boring bar, the at least two damping modules are preferably identical in design and size.

[0017] According to another embodiment of the present invention, the actuators in each of the at least two damping modules are single-axis actuators configured to generate a vibratory force parallel or at least substantially parallel to a single actuation axis of the actuator, and the at least two damping modules are arranged with their actuation axes angularly offset from one another. This allows the actuators of different damping modules to be optimized for canceling vibrations in different angular directions relative to the longitudinal axis of the boring bar, which facilitates achieving efficient vibration damping. In this case, the actuator of a first damping module may be optimized, for example, for canceling vibrations caused by the radial forces on the cutting elements, and the actuator of a second damping module may be optimized for canceling vibrations caused by the tangential forces on the cutting elements. In the latter case, it is preferable to use two damping modules whose actuation axes extend perpendicularly to one another, due to the fact that the radial forces are perpendicular to the tangential forces.

[0018] Further advantageous features of the boring bar according to the invention will become apparent from the following description.

[0019] The present invention also relates to a non-rotating boring tool comprising a boring bar of the type described above and a tool part provided with cutting elements, the tool part being removably attached to the front part of the boring bar or being integrally formed therewith.

[0020] According to one embodiment of the invention, the front of the boring bar is adjustable in its rotational position relative to the at least one damping module and / or the tool part is adjustable in its rotational position relative to the front of the boring bar, thereby allowing the angular position of the cutting elements relative to the at least one damping module to be adjusted in order to optimize the damping characteristics.

[0021] Another embodiment of the present invention is the actuator in each damping module is a single axis actuator configured to generate a vibratory force parallel or at least substantially parallel to a single actuation axis of the actuator; The cutting element includes a rake side, a flank face, and a cutting edge formed at an intersection between the rake side and the flank face, and when viewed in a cross section that is perpendicular to the longitudinal axis of the boring bar and intersects the cutting edge at its radially outermost point, a straight and imaginary reference line L intersects the cutting edge at its radially outermost point and extends in this cross section at an angle of 6° to the flank face outside the cutting element, and when viewed in this cross section, the actuation axis of the actuator in the damping module closest to the front of the boring bar is: or forming an angle of 90°±10°, preferably an angle of 90°±5°, more preferably an angle of 90°±1° with respect to the reference line L; or It is characterized in that it forms an angle of 0°±10° with respect to the reference line L, preferably an angle of 0°±5°, and more preferably an angle of 0°±1°.

[0022] The clearance angle of the cutting elements of a non-rotary boring tool is generally at or close to 6°, which implies that the tangential forces on the cutting elements are directed substantially along the reference line L defined above, while the radial forces on the cutting elements are directed substantially perpendicular to this reference line L. In order to achieve efficient vibration damping of the boring bar of a non-rotary boring tool, it is preferred to arrange the actuation axis of the actuator in the damping module closest to the front of the boring bar substantially parallel to the radial forces on the cutting elements so that the actuator can efficiently damp the vibrations caused by these radial forces, or to arrange the actuation axis substantially parallel to the tangential forces on the cutting elements so that the actuator can efficiently damp the vibrations caused by these tangential forces. If the actuation axis of the actuator in the damping module closest to the front of the boring bar is arranged to form an angle of 90°±10° with respect to the reference line L, the actuator will consequently focus on damping the vibrations in the boring bar caused by the radial forces on the cutting elements. If the actuation axis of the actuator in the damping module closest to the front of the boring bar were positioned to form an angle of 0°±10° with respect to the reference line L, then this actuator would instead focus on damping vibrations in the boring bar caused by tangential forces on the cutting elements.

[0023] According to another embodiment of the invention, the boring tool includes at least one vibration sensor mounted on the front of the boring bar or on the tool portion thereof, which allows vibration detection close to the cutting elements, thereby effectively canceling vibrations induced by cutting forces acting on the cutting elements.

[0024] Further advantageous features of the boring tool according to the invention will become apparent from the following description.

[0025] The present invention also relates to a boring machine including a boring bar of the type described above and an electronic control unit configured to control the current to the actuators in each damping module in order to control the generation of a vibratory force in each damping module. The boring machine also preferably includes at least one vibration sensor configured to generate measurement signals related to the vibrations of the boring bar and to transmit these measurement signals to the electronic control unit, the electronic control unit being configured to receive these measurement signals from the at least one vibration sensor and to control the current to the actuators in each damping module in dependence on the measurement signals from the at least one vibration sensor in order to control the generation of a vibratory force in the actuators in each damping module in dependence on the measurement signals.

[0026] Further advantageous features of the boring machine according to the invention will become apparent from the following description.

[0027] A specific description of embodiments of the present invention follows, by way of example, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a side view of a non-rotary boring tool according to one embodiment of the present invention. [Figure 2] FIG. 2 is a longitudinal cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is an exploded view of the boring tool of FIG. 1. [Figure 4] FIG. 2 is an exploded view of the boring tool of FIG. 1 from another direction. [Figure 5] FIG. 2 is a perspective view of the front end of the boring tool of FIG. 1. [Figure 6a-6b] FIG. 2 is a front view of the boring tool of FIG. 1. [Figure 7a] FIG. 2 is a top perspective view of a cutting element included in the boring tool of FIG. 1. [Figure 7b]7b is a bottom perspective view of the cutting element of FIG. 7a. FIG. [Figure 7c] FIG. 7b is a side view of the cutting element of FIG. 7a. [Figure 8a] FIG. 10 is a top perspective view of an alternative cutting element. [Figure 8b] 8b is a bottom perspective view of the cutting element of FIG. 8a. FIG. [Figure 8c] FIG. 8b is a side view of the cutting element of FIG. 8a. [Figure 9] 1 is a schematic diagram of a boring device according to one embodiment of the present invention. [Figure 10] 1 is a schematic diagram of a boring device according to an alternative embodiment of the present invention; [Figure 11] FIG. 10 is a schematic diagram of a boring device according to another alternative embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] A non-rotating boring tool 1 according to one embodiment of the present invention is shown in Figures 1 to 5. Boring tool 1 is used to perform various types of machining operations, such as internal or external turning on a rotating workpiece of metallic material. Boring tool 1 comprises a boring bar 2 which is fixed to a support structure 3 of a metal cutting machine (shown highly diagrammatically in Figures 9 to 11) so as to cantilever from said support structure 3. Boring tool 1 also comprises a tool part 4, on which a cutting element 5 is provided, and which is supported by boring bar 2 and rests at its front end 2a.

[0030] The boring bar 2 includes an elongated main portion 10 configured for attachment to a support structure 3 of a metal cutting machine. The main portion 10 has a rear end 10b and an opposite front end 10a. A longitudinal axis 11 of the main portion extends between the rear end 10b and the front end 10a of the main portion. The main portion 10 is preferably tubular in shape and is attached to the support structure 3 at its rear end 10b. In the embodiment shown, the main portion 10 is cylindrical and has a circular cross-sectional shape. However, the main portion 10 may also have any other suitable cross-sectional shape, such as an elliptical or polygonal cross-sectional shape.

[0031] The boring bar 2 further includes a front portion 12. The front portion 12 has a rear end 12b facing the front end 10a of the main portion 10 and an opposite front end 12a. A central axis 13 of the front portion extends between the rear end 12b and the front end 12a of the front portion. The front end 12a of the front portion is arranged to support the tool portion 4 described above. This tool portion 4 is thus attached at its front end 12a to the front portion 12 of the boring bar. Alternatively, the tool portion 4 may be integrally formed with the front portion 12, which implies that the tool portion 4 and the front portion 12 are combined as one common component. In the embodiment shown, the front portion 12 is cylindrical and has a circular cross-sectional shape. However, the front portion 12 may also have any other suitable cross-sectional shape, for example, an elliptical or polygonal cross-sectional shape.

[0032] The boring bar 2 also includes at least one damping module 14 disposed between the forward end 10 a of the main section 10 and the aft end 12 b of the forward section 12, the damping module 14 having an aft end 14 b facing the main section 10, an opposite forward end 14 a facing the forward section 12, and a central axis 15 extending between the aft end 14 b of the damping module and the forward end 14 a. In the embodiment shown, the boring bar 2 includes two such damping modules 14 disposed in series with one another between the forward end 10 a of the main section 10 and the aft end 12 b of the forward section 12. The two damping modules 14 are therefore disposed in series with one another in the longitudinal direction of the boring bar 2. The boring bar 2 may alternatively include more than two damping modules 14 disposed in series with one another in the longitudinal direction of the boring bar 2, or a single damping module 14.

[0033] In the embodiment shown, the damping module 14 is cylindrical and has a circular cross-sectional shape, but the damping module 14 may also have any other suitable cross-sectional shape, for example, an elliptical or polygonal cross-sectional shape.

[0034] Each one of the damping modules 14 is provided with an electrically controlled vibration actuator 16 for active vibration damping of the boring bar 2, the actuator 16 being arranged in the housing 14c of the associated damping module and configured to generate a vibratory force to counteract vibrations induced in the boring bar 2 by cutting forces acting on the cutting elements 5 during machining of the rotating workpiece. The vibratory force generated by the actuator 16 of the damping module 14 may also be used to intermittently vibrate the cutting elements 5 to break down large metal chips cut from the workpiece by the cutting elements 5 into smaller pieces.

[0035] In the embodiment shown, each damping module 14 is provided with a single vibration actuator 16. However, each damping module 14 may alternatively be provided with two or more vibration actuators 16, preferably, but not necessarily, with the actuation axes 17 of the two or more actuators 16 angularly offset from one another.

[0036] Each actuator 16 includes a movably arranged damping mass 16a configured to generate a vibratory force parallel or at least substantially parallel to the actuator's actuation axis 17, the damping mass 16a being movable relative to the housing 14c of the associated damping module 14. In the embodiment shown, the damping mass 16a is movable relative to the housing 14c of the damping module 14 against the action of return springs 16b arranged on opposite sides of the damping mass 16a. The actuators 16 may be of an electromagnetic type, in which the vibratory force is generated electromagnetically. However, any other suitable type of vibration actuator may be used.

[0037] The front portion 12 is connected to the main portion 10 via a damping module 14. The main portion 10, the front portion 12, and the damping module 14 together form the elongated body 6, with the main portion 10, each individual damping module 14, and the front portion 12 forming separate length sections, or segments, of the elongated body 6. Thus, the main portion 10, the damping module 14, and the front portion 12 form a continuous section of the boring bar's elongated body 6 as viewed in its longitudinal direction.

[0038] In the illustrated embodiment, the damping modules 14 abut one another directly, with the rear end 14b of the forward-most one of the damping modules abutting the forward end 14a of the other, i.e., the rearmost, damping module. As shown in Figures 1 to 5, the front section 12 may be positioned with its rear end 12b directly abutting the forward end 14a of the forward-most damping module, and the rearmost damping module may be positioned with its rear end 14b directly abutting the forward end 10a of the main section 10.

[0039] The periphery 18 of the main section 10 and the periphery 19 of each damping module 14 are preferably coplanar or substantially coplanar with one another, as shown in Figures 1, 2, and 5. Additionally, the periphery 20 of the front section 12 is preferably coplanar or substantially coplanar with the periphery 19 of the forward-most damping module 14.

[0040] In the embodiment shown, each one of the damping modules 14 is positioned with its central axis 15 aligned or substantially aligned with the longitudinal axis 11 of the main portion 10 .

[0041] To facilitate maintenance and repair of the boring bar 2, the main section 10, the damping module 14, and the front section 12 are preferably removably mounted to one another. In the embodiment shown, the damping module 14 is clamped between the main section 10 and the front section 12 using tie rods 22. Each tie rod 22 has a first end 22a fixed to the main section 10 and an opposite second end 22b fixed to the front section 12. Furthermore, each tie rod 22 extends through passages 23 that are aligned with one another in the damping module 14. The separate sections 10, 12, 14 of the elongated body 6 may alternatively be mounted to one another in any other suitable manner.

[0042] In the embodiment shown, the actuators 16 in each one of the damping modules 14 are accessible through two openings on opposite sides of that damping module, each opening being covered by a removably mounted cover 24 which forms part of the periphery 19 of the damping module and which is fixed in the associated opening by means of fixing elements 25 in the form of screws. Passages 23 for some of the tie rods 22 mentioned above may be provided in the cover 24.

[0043] In the illustrated embodiment, coolant is supplied to the tool portion 4 through a first feed pipe 26 extending axially through the main section 10 of the boring bar 2 and at least one second feed pipe 27 extending parallel to the tie rod 22 between the main section 10 and the front section 12 of the boring bar. In the illustrated example, the boring bar 2 is provided with two such second feed pipes 27. The first feed pipe 26 is fixed to the main section 10 of the boring bar by means of a first end piece 28a fixed to the main section 10 at its front end 10a and a second end piece 28b fixed to the main section 10 at its rear end 10b. Each of the second feed pipes 27 is connected to the first feed pipe 26 via an internal channel in the first end piece 28a. Furthermore, each of the second feed pipes 27 may be arranged to extend through aligned passages 29 in the damping module 14.

[0044] The actuator 16 in each one of the damping modules 14 is preferably a single-axis actuator configured to generate a vibratory force parallel or at least substantially parallel to a single actuation axis 17 of the actuator. In the illustrated embodiment, the actuation axis 17 of each one of the actuators 16 extends in a cross section perpendicular to the central axis 15 of the associated damping module 14, and the damping modules 14 are arranged with the actuation axes 17 of their actuators 16 angularly offset from one another. Thus, the actuators 16 of the damping modules 14 are arranged at different rotational positions relative to one another on the elongated body 6. If there are two damping modules 14, they are preferably arranged with the actuation axes 17 of their actuators 16 extending perpendicular to one another, as shown in FIGS. 1 and 2 .

[0045] In order to be able to adjust the angular position of the working axis 17 of the actuator 16 relative to the cutting elements 5, the front part 12 of the boring bar 2 may be adjustable in its rotational position relative to the damping modules 14, which implies that the front part 12 can be attached to the foremost damping module 14 in different selectable rotational positions relative to this damping module. As an alternative or in combination with such rotational adjustability of the front part 12 relative to the damping modules 14, the tool part 4, on which the cutting elements 5 are provided, may be adjustable in its rotational position relative to the front part 12 of the boring bar, which implies that the tool part 4 can be attached to the front part 12 in different selectable rotational positions relative to this front part. The damping modules 14 may also be arranged so that their actuators 16 can be adjustable in their rotational position relative to the damping module casing. If the number of damping modules 14 is two or more, they may be arranged so that their respective rotational positions can be adjustable relative to each other.

[0046] The cutting elements 5 secured to the tool portion 4 may be positive cutting elements, as shown in Figures 7a-7c, or negative cutting elements, as shown in Figures 8a-8c. The cutting elements 5 include an upper rake side 30, a bottom side 31 extending parallel or substantially parallel to the rake side 30, and a peripheral flank 32 extending between the rake side 30 and the bottom side 31. A cutting edge 33 is formed at the intersection between the rake side 30 and the flank 32. In the example shown, the cutting edge 33 extends all around and along the periphery of the rake side 30. In the case of a positive cutting element 5, the flank 32 extends at an acute angle α to the rake side 30, as shown in Figure 7c. In the case of a negative cutting element 5, the flank 32 extends perpendicular to the rake side 30, as shown in Figure 8c.

[0047] A bore 34 extends across the cutting element 5 between the rake side 30 and the bottom side 31. The cutting element 5 is configured to be releasably mounted on the tool part 4 so that the bottom side 31 of the cutting element 5 rests on a support surface 35 (see FIG. 6a) on a seat provided for the cutting element in the tool part 4. The cutting element 5 is secured to the seat in the tool part 4 using a securing element 36 in the form of a screw (see FIG. 5) that extends through the bore 34 in the cutting element 5 and engages with a threaded hole in the support surface 35 on the seat.

[0048] In the example shown, the cutting element 5 comprises two cutting corners 37 located opposite each other on opposite sides of the cutting element. The cutting element 5 is fixed to the tool part 4 so that one of the cutting corners 37 faces outward from the longitudinal axis 7 of the boring bar 2, and the cutting element 5 is intended to come into contact with the rotating workpiece via this outward-facing cutting corner 37. During machining of the rotating workpiece, the boring tool 1 generally exerts the above-mentioned tangential force F on the cutting element 5. t is placed against the workpiece so that it is oriented at an angle θ of about 6° relative to the clearance face 32, as shown in Figures 7c and 8c.

[0049] A straight and imaginary reference line L (see Figures 6a and 6b) is defined in a cross section that is perpendicular to the longitudinal axis 7 of the boring bar 2 and intersects the cutting edge 33 at a radially outermost point 39, this reference line L intersecting the cutting edge 33 at the radially outermost point 39 and extending in this cross section, on the outside of the cutting element 5, at an angle β of 6° relative to the flank face 32, i.e., this angle β measured on the outside of the cutting element 5. Thus, if a positive cutting element 5 of the type shown in Figures 7a to 7c is fixed to the tool part 4 with a clearance angle of 6°, the reference line L may extend perpendicular to the rake side 30 of the cutting element, as shown in Figures 6a and 6b.

[0050] The actuator 16 in the damping module 14 closest to the front 12 of the boring bar 2 is preferably arranged in a rotational position on the boring bar 2 such that its working axis 17, when viewed in the cross section, forms an angle of 90°±10°, preferably an angle of 90°±5°, more preferably an angle of 90°±1° with respect to the reference line L (as shown in FIG. 6a). In this case, the working axis 17 of this actuator is arranged to actuate the radial force F on the cutting element 5. r With such an arrangement of the actuator 16 in the damping module 14 closest to the front 12 of the boring bar, this actuator acts to generate a radial force F on the cutting element 5. r The vibrations caused by the

[0051] According to a preferred alternative, the actuator 16 of the damping module 14 closest to the front part 12 of the boring bar 2 is arranged in a rotational position on the boring bar 2 such that its working axis 17, when viewed in said cross section, forms an angle of 0°±10°, preferably an angle of 0°±5°, more preferably an angle of 0°±1° with respect to said reference line L (as shown in FIG. 6b). In this case, the working axis 17 of this actuator is such that it is possible to apply a tangential force F on the cutting element 5 to the damping module 14. t With such an arrangement of the actuator 16 in the damping module 14 closest to the front 12 of the boring bar, this actuator acts to generate a tangential force F on the cutting element 5. t The vibrations caused by the

[0052] Different embodiments of a boring machine 40 including a boring bar 2 of the above type are shown highly diagrammatically in Figures 9 to 11. The boring machine 40 further includes an electronic control unit 41 configured to control the supply of electric current to the actuators 16 in the damping modules 14 of the boring bar 2 in order to control the generation of vibratory forces in those damping modules. This electric current is supplied to the actuators 16 from a power source, which may be an external power source 42, as shown in Figure 9, or a power supply unit 42' mounted on the boring bar 2, as shown in Figure 11, or on the support structure 3 or any other part of the metal-cutting machine, as shown in Figure 10. The power supply unit 42' includes at least one energy storage element, for example in the form of a battery, for storing electrical energy. The electronic control unit 41 may be mounted on the front part 12 of the boring bar 2, as shown in Figures 10 and 11, or on any other part of the boring bar. As a further alternative, the electronic control unit 41 may be mounted on the support structure 3 or any other part of the metal cutting machine, as shown in FIG.

[0053] The boring machine 40 further comprises at least one vibration sensor 43, for example in the form of an accelerometer, which is configured to generate measurement signals related to the vibrations of the boring bar 2 and to transmit these measurement signals via a wireless or cable connection to the electronic control unit 41. The at least one vibration sensor 43 is preferably mounted on the front part 12 of the boring bar or on the tool part 4, although it may alternatively be mounted on any other suitable part of the boring bar 2.

[0054] The electronic control unit 41 is configured to receive the measurement signals from the at least one vibration sensor 43 and to control the supply of current to the actuators 16 in the damping modules 14 in dependence on the measurement signals, in order to control the generation of the vibratory force in each damping module 14 in dependence on the measurement signals, thereby controlling the cutting force F acting on the cutting element 5 during machining of the workpiece. r , Ft This cancels out the vibrations induced in the boring bar 2.

[0055] The present invention is, of course, not limited in any way to the above-described embodiments. On the contrary, many possibilities for modification thereof will be apparent to those skilled in the art without departing from the basic concept of the present invention, as defined in the appended claims. For example, the actuator in the associated damping module can be arranged so that its actuation axis is parallel to or coincides with the central axis of the damping module, which implies that the actuator is arranged with its actuation axis parallel to or aligned with the longitudinal axis of the elongated body. It is also possible to integrate a two-axis actuator into one damping module in order to obtain both radial and tangential damping of the boring bar using only one damping module.

Claims

1. A boring bar (2) for a non-rotating boring tool, comprising: an elongated main portion (10) configured for attachment to a support structure of a metal cutting machine, the main portion (10) having a rear end (10b) and an opposite front end (10a); a front portion (12) having a rear end (12b) facing the front end (10a) of the main portion (10) and an opposite front end (12a), the front end (12a) of the front portion (12) being arranged to support a tool portion (4) provided with a cutting element (5); A boring bar (2) comprising: the boring bar (2) includes at least one damping module (14) disposed between the front end (10a) of the main section (10) and the rear end (12b) of the front section (12), the at least one damping module (14) having a rear end (14b) facing the main section (10), an opposite front end (14a) facing the front section (12), and a central axis (15) extending between the rear end (14b) and the front end (14a) of the damping module; the at least one damping module (14) is provided with an electrically controlled vibration actuator (16) for active vibration damping of the boring bar (2), the vibration actuator (16) being configured to generate a vibratory force; the front portion (12) is connected to the main portion (10) via the at least one damping module (14), the main portion (10), the front portion (12) and the at least one damping module (14) together form an elongated body (6), the at least one damping module (14) constituting a length section of the elongated body (6); the at least one damping module (14) is clamped between the main section (10) and the front section (12) by means of a tie rod (22) extending through a passage (23) in the at least one damping module (14). Boring bar (2).

2. 2. The boring bar according to claim 1, wherein the at least one damping module (14) has the same cross-sectional peripheral shape as the cross-sectional peripheral shape of the main section (10) and / or the front section (12).

3. 3. Boring bar according to claim 1 or 2, characterized in that the main part (10) and / or the front part (12) and / or the at least one damping module (14) are cylindrical.

4. 4. Boring bar according to any one of claims 1 to 3, characterized in that the outer periphery (18) of the main part (10) and the outer periphery (19) of the at least one damping module (14) are flush with each other.

5. 5. The boring bar according to claim 1, wherein the at least one damping module (14) is arranged with its central axis (15) aligned with the longitudinal axis (11) of the main portion (10).

6. 6. The boring bar according to claim 1, wherein the vibration actuator (16) is a single-axis actuator configured to generate a vibratory force parallel or at least substantially parallel to a single actuation axis (17) of the vibration actuator (16).

7. 7. Boring bar according to claim 6, characterized in that the actuation axis (17) extends in a cross section perpendicular to the central axis (15) of the at least one damping module (14).

8. 8. The boring bar according to claim 1, wherein the boring bar comprises at least two damping modules arranged in series with one another between the front end of the main section and the rear end of the front section.

9. 9. The boring bar according to claim 8, wherein adjacent damping modules (14) of the at least two damping modules (14) abut each other.

10. the vibration actuator (16) in each of the at least two damping modules (14) is a single-axis actuator configured to generate a vibratory force parallel or at least substantially parallel to a single actuation axis (17) of the vibration actuator (16); the at least two damping modules (14) are arranged such that the actuation axes (17) of the vibration actuators (16) are angularly offset from one another; 10. A boring bar according to claim 8 or 9.

11. 11. The boring bar according to claim 10, characterized in that the at least two damping modules (14) are arranged such that the actuation axes (17) of the vibration actuators (16) extend perpendicularly to one another.

12. A boring bar (2) according to any one of claims 1 to 11; a tool part (4) provided with cutting elements (5), the tool part (4) being removably attached to the front part (12) of the boring bar or being integrally formed with the front part (12) of the boring bar; 1. A non-rotating boring tool comprising:

13. 13. A non-rotary boring tool according to claim 12, characterized in that the front part (12) of the boring bar is adjustable in its rotational position relative to the at least one damping module (14) and / or the tool part (4) is adjustable in its rotational position relative to the front part (12) of the boring bar.

14. the vibration actuator (16) of the at least one damping module or in each damping module (14) of the at least two damping modules is a single-axis actuator configured to generate a vibratory force parallel or at least substantially parallel to a single actuation axis (17) of the vibration actuator (16); The cutting element (5) comprises a rake side (30), a flank face (32), and a cutting edge (33) formed at the intersection between the rake side and the flank face, wherein, when viewed in a cross section perpendicular to the longitudinal axis (7) of the boring bar (2) and intersecting the cutting edge (33) at a radially outermost point (39), a straight and imaginary reference line L intersects the cutting edge (33) at the radially outermost point (39) and extends in this cross section at an angle (β) of 6° to the flank face (32) outside the cutting element (5), and when viewed in this cross section, the actuation axis (17) of the vibration actuator (16) of the damping module (14) closest to the front part (12) of the boring bar is: Forming an angle of 90°±10° with respect to the reference line L, or The angle formed with respect to the reference line L is 0°±10°. A non-rotary boring tool according to claim 12 or 13 when dependent on any one of claims 8 to 11.

15. 15. A non-rotary boring tool according to any one of claims 12 to 14, characterized in that the non-rotary boring tool comprises at least one vibration sensor (43) mounted on the front part (12) of the boring bar or on the tool part (4).

16. A boring bar (2) according to any one of claims 8 to 11; an electronic control unit (41) configured to control a current to the vibration actuator (16) of the at least one damping module or of each damping module (14) of the at least two damping modules in order to control the generation of a vibratory force in the vibration actuator (16) of the at least one damping module or of each damping module (14) of the at least two damping modules; A boring device comprising:

17. the boring device (40) comprises at least one vibration sensor (43) configured to generate a measurement signal related to the vibration of the boring bar (2) and to transmit the measurement signal to the electronic control unit (41); the electronic control unit (41) is configured to receive the measurement signal from the at least one vibration sensor (43), and the electronic control unit (41) is configured to control the current to the vibration actuator (16) of the at least one damping module or of each damping module (14) of the at least two damping modules in dependence on the measurement signal from the at least one vibration sensor (43) in order to control the generation of a vibratory force in the vibration actuator (16) of the at least one damping module or of each damping module (14) of the at least two damping modules in dependence on the measurement signal.

17. The boring device of claim 16.

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