Non-rotating hole machining tool for internal diameter turning and hole machining mechanism equipped with such hole machining tool

Abstract

A non-rotating hole-machining tool for internal turning, comprising a boring bar (2) with an elongated body (6), a cutting element (5) with a rake face (30), a flank face (32), and a cutting edge (33), and an electrically controlled vibration actuator (8) for active vibration damping of the boring bar. When viewed in a cross-sectional plane perpendicular to the longitudinal axis (7) of the elongated body and intersecting the cutting edge at a radially outermost point (39), imaginary straight first and second reference lines L1, L2 intersect the cutting edge at the radially outermost point, the first reference line L1 extending outside the cutting element at an angle of 6° to the flank face (32), and the second reference line L2 extending between the rake face (30) and the flank face (32) at an angle of 10 to 40° to the first reference line L1. The actuator is disposed with its operating shaft (10) extending parallel to the second reference line L2.

Description

Technical Field

[0001] The present invention relates to a non-rotating hole machining tool for internal diameter turning as described in the preamble of claim 1. The present invention also relates to a hole machining mechanism comprising such a hole machining tool.

Background Art

[0002] In order to perform an internal diameter turning operation on a rotating metal workpiece, a hole machining tool comprising a cantilever boring bar having a cutting element at its free end may be used. The internal diameter turning operation is one that machines the inner surface of the workpiece located in some kind of hole in the workpiece, and the boring bar is gradually moved deeper and deeper into the hole in the workpiece during machining of the inner surface of the hole. The internal diameter turning operation can be performed, for example, to enlarge an existing hole in the workpiece or to smooth the inner surface of such a hole. During the internal diameter turning operation, the cutting element receives a cutting force from the rotating workpiece, which includes a radial force that is directed perpendicular to the axis of rotation of the workpiece and along a line that intersects the axis of rotation and the contact point between the cutting element and the workpiece, and a tangential force that is directed in the tangential direction of the workpiece surface perpendicular to the radial force at the contact point between the cutting element and the workpiece. These mutually perpendicular cutting forces will induce vibrations in the boring bar, and the boring bar may cause noise, damage to the surface finish of the workpiece, tool breakage, and other undesirable effects.

[0003] In order to reduce the vibrations of the boring bar caused by the cutting forces on the cutting element at the outer end of the boring bar during machining of the workpiece, various types of active damping systems have been developed. Such an active damping system can comprise at least one vibration sensor for sensing the vibrations of the boring bar and at least one electrically controlled vibration actuator for generating a vibration force in the boring bar, and the vibration actuator is controlled by an electronic control unit in response to measurement signals from one or more vibration sensors so as to introduce into the boring bar a reverse vibration that interferes with and cancels out the vibration induced in the boring bar by the cutting force.

[0004] An active damping system of the above type is described in U.S. Patent No. 5,170,103A, in which the vibration actuator is housed in a cavity inside the boring bar. SUMMARY OF THE INVENTION

[0005] Object of the Invention It is an object of the present invention to provide a non-rotating hole machining tool of the above type having a novel and preferred design.

[0006] According to the present invention, the above object is achieved by a non-rotating hole machining tool having the features defined in claim 1.

[0007] The non-rotating hole machining tool according to the present invention is for use in internal diameter turning, a boring bar having an elongated body configured to be attached to a support structure of a metal cutting machine, the elongated body having a rear end portion and an opposite front end portion, and a tool portion having a cutting element, the tool portion being removably attached to or integrally formed with the front end portion of the elongated body, the cutting element including a rake face, a flank face, and a cutting edge formed at a portion where the rake face and the flank face intersect.

[0008] In order to be able to define the hole machining tool of the present invention in an appropriate manner, the following virtual reference lines are defined in a plane in the cross-sectional direction that is perpendicular to the longitudinal axis of the above-described elongated body and intersects the cutting edge at the radially outermost point on the cutting edge: a first reference line L1, which is a virtual straight line that intersects the cutting edge at the radially outermost point and extends at an angle of 6° with respect to the flank face outside the cutting element, and A second reference line L2, which is a virtual straight line that intersects the cutting edge at the outermost point in the radial direction and extends at an angle of 10 to 40° with respect to the first reference line L1 between the rake face and the flank face. Preferably, the second reference line L2 extends at an angle of 10 to 30° with respect to the first reference line L1 between the rake face and the flank face.

[0009] The boring bar is provided with an electrically controlled vibration actuator for active vibration damping of the boring bar, which is configured to generate a vibration force parallel or substantially parallel to the operating axis of the actuator, hereinafter referred to as the first actuator. This actuator is a single-axis actuator having a single operating axis, and is arranged in an elongated main body in a state where its operating axis extends parallel or substantially parallel to the above-mentioned second reference line L2.

[0010] The flank angle of the cutting element of a non-rotating hole machining tool to be used for internal diameter turning is usually 6° or around 6°, which suggests that the tangential cutting force on the cutting element is directed substantially along the first reference line L1 defined above. On the other hand, the radial cutting force on the above-mentioned cutting element will be directed substantially perpendicular to this first reference line L1.

[0011] The vibration induced in the boring bar of a non-rotating hole machining tool during internal diameter turning is mainly caused by the tangential and radial cutting forces on the above-mentioned cutting element, and these forces act on the cutting element at the contact point between the cutting element and the workpiece, that is, at the outermost point in the radial direction on the cutting edge of the cutting element. The tangential and radial cutting forces F t , F r are perpendicular to the longitudinal axis of the elongated main body and are directed in a plane that intersects the contact point between the cutting element and the workpiece, that is, in a plane corresponding to the cross-sectional direction defined above. The resultant force F of the radial and tangential cutting forces F t , F r on the cutting element res ​(See FIG. 7c) has its application point at the radially outermost point on the cutting edge and extends between the rake face and the flank face of the cutting element in a plane corresponding to the plane in the same plane as the tangential and radial cutting forces, i.e., the plane in the cross-sectional direction defined above. The resultant force F res and the angle between the tangential cutting force F t and thus the angle between the resultant force and the first reference line L1 are determined by the relationship between the magnitude of the tangential cutting force F t and the magnitude of the radial cutting force F r . And this relationship is determined by the depth of cut a p and the corner radius r of the cutting edge ε . Based on simple calculations based on principles well known to those skilled in the art, under normal operating conditions for internal turning, the relationship between the magnitude of the tangential cutting force F t and the magnitude of the radial cutting force F r is such that the angle between the resultant force F res and the tangential cutting force F t , and thus the angle between the resultant force and the first reference line L1, is in the range of 10 to 40°. For example, when the depth of cut a p is such that 0.5r ε ≤ a p ≤ r ε , the relationship between the tangential cutting force F t and the radial cutting force F r is approximately 2:1, which suggests that the angle between the resultant force F res and the tangential cutting force F t , and thus the angle between the resultant force and the first reference line L1, is approximately 27°. When the depth of cut a p is such that 2r ε ≤ a p ≤ 3r ε , the relationship between the tangential cutting force F t and the radial cutting force F r is approximately 4:1, which suggests that the angle between the resultant force F res and the tangential cutting force F tsuggests that the angle between them, and thus the angle between the resultant force and the first reference line L1, is approximately 14°.

[0012] The orientation of the second reference line L2 is intended to represent the assumed orientation of the resultant force with respect to the cutting element, which means that the first actuator is arranged within an elongated body with its axis of action extending substantially parallel to the assumed orientation of the resultant force with respect to the cutting element, and this suggests that this actuator can efficiently damp the vibrations caused by the combined effect of the tangential and radial cutting forces on the cutting element. Using this configuration of the actuator, it will be possible to achieve efficient vibration damping of the boring bar by using a single actuator.

[0013] According to an embodiment of the present invention, the first actuator is arranged within the elongated body such that the central axis of the first actuator is aligned or substantially aligned with the longitudinal axis of the elongated body. This centering of the first actuator within the elongated body is thereby achieved, which simplifies the calculations used in the control of the first actuator and thus enables the realization of a damping system having an excellent ability to respond and damp in an accurate and rapid manner to vibrations in the boring bar. However, the first actuator may alternatively be arranged without aligning its central axis with the longitudinal axis of the elongated body.

[0014] According to another embodiment of the present invention, the first actuator is adjustable in its rotational position within the elongated body and / or the tool part is adjustable in its rotational position with respect to the elongated body. This will enable adjustment of the angular position of the first actuator with respect to the cutting element in order to optimize the damping characteristics, for example, according to the depth of cut a p of the cutting.

[0015] According to another embodiment of the present invention, the boring bar comprises a second electrically controlled vibration actuator for active vibration damping of the boring bar, the second actuator being configured to generate a vibration force parallel or substantially parallel to the axis of action of the second actuator, the second actuator being a uniaxial actuator having a single axis of action, and the second actuator being arranged longitudinally in series with the first actuator within an elongated body. The second actuator will assist in damping the vibrations induced in the boring bar by the cutting forces exerted by the first actuator on the cutting element, thus enabling an improvement in the damping characteristics. The first and second actuators are preferably arranged within the elongated body such that the central axis of the first actuator and the central axis of the second actuator are aligned or substantially aligned with each other.

[0016] According to another embodiment of the present invention, the first and second actuators are arranged with their axes of action offset from each other, preferably perpendicular to each other, and the first actuator is preferably arranged between the tool portion and the second actuator. This causes different actuators to focus on canceling vibrations in different angular directions with respect to the longitudinal axis of the boring bar, thereby facilitating the achievement of efficient vibration damping.

[0017] In addition to the first and second actuators described above, the boring bar may also comprise one or more additional vibration actuators arranged within the elongated body in any suitable manner, if desired.

[0018] According to another embodiment of the present invention, the elongated body is an elongated main portion configured to be attached to a support structure, the elongated main portion having a rear end portion and an opposite front end portion, a front portion having a rear end portion facing the front end portion of the main portion and an opposite front end portion, the front end portion of the front portion being arranged to carry the tool portion, At least one damping module disposed between the front end of the main portion and the rear end of the front side portion, and accommodating at least one of the first and second actuators.

[0019] The front portion of the elongated body described above is connected to the main portion of the elongated body via at least one damping module, and the at least one damping module constitutes a certain length section of the elongated body. Therefore, the main portion, the at least one damping module, and the front portion constitute continuously arranged individual length sections of the elongated body as seen in the longitudinal direction of the elongated body. By mounting the actuator within the casing of the initially associated damping module and then fixing the damping module between the main portion and the front portion of the elongated body, the vibration actuator can be integrated into the elongated body of the boring bar, which facilitates the assembly of the boring bar. In this case, the acting direction of the actuator with respect to the contact point between the cutting element and the workpiece can be adjusted, if necessary, by adjusting the rotational position of the associated damping module with respect to the front portion of the elongated body. Furthermore, by accommodating the actuator within a separate damping module, the damping characteristics can be easily adapted to specific requirements by modifying the damping module, without the need to change other parts of the boring bar at this time. The number of actuators in the boring bar can be easily changed according to specific requirements by changing the number of damping modules arranged between the main portion and the front portion of the elongated body. By arranging the actuator within a separate and spaced damping module between the main portion and the front portion of the elongated body, it also becomes easier to position the actuator near the front end of the elongated body, which is a favorable position for the actuator as it is close to the cutting element where the vibration of the boring bar is generated. Furthermore, the use of separate damping modules makes it easier to adapt this portion of the boring bar to the requirements of the actuator for the purpose of maximizing the damping mass and the stroke of the actuator.

[0020] However, the elongated body of the boring bar may not have a separate damping module of the type described above as an alternative, in which case each actuator is housed within a cavity inside the elongated body.

[0021] The main part and / or the front part and / or at least one damping module are preferably cylindrical, preferably a perfect cylindrical shape.

[0022] According to an embodiment of the present invention, the outer periphery of the main part and the outer periphery of at least one damping module are flush with each other or substantially flush. The elongated body of the boring bar can thus be designed to have a smooth outer peripheral surface.

[0023] According to another embodiment of the present invention, at least one damping module is preferably sandwiched between the main part and the front part by a connecting rod extending through a passage of at least one damping module. This allows one or more damping modules to be fixed in a simple and reliable manner between the main part and the front part of the elongated body. Each of the connecting rods may have a first end fixed to the main part and an opposite second end fixed to the front part.

[0024] According to another embodiment of the present invention, the elongated body comprises at least two damping modules of the type described above, arranged in series with each other between the front end portion of the main part and the rear end portion of the front side portion, and the first and second actuators are arranged in different ones of those damping modules. By this, the first and second actuators can be integrated into the elongated body of the mandrel in a simple manner. Alternatively, the first and second actuators may be housed within one and the same damping module. The at least two damping modules are advantageously arranged so as to abut against each other. However, some kind of intermediate element may be arranged between the at least two damping modules as an alternative. The front side portion of the elongated body is preferably arranged such that its rear end portion abuts against the front end portion of the foremost one of the at least two damping modules. However, some kind of intermediate element may be arranged between the front side portion and the foremost damping module as an alternative. The rearmost one of the at least two damping modules is preferably arranged such that its rear end portion abuts against the front end portion of the main part of the elongated body. However, some kind of intermediate element may be arranged between the main part and the rearmost damping module as an alternative.

[0025] To facilitate the manufacture of the elongated body, it is advantageous for the at least two damping modules to be of the same design and size.

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

[0027] The present invention also relates to a drilling mechanism comprising a core drill of the type described above and an electronic control unit configured to control the current to the actuator so as to control the generation of the vibration force in the first actuator. The drilling mechanism preferably also comprises at least one vibration sensor configured to generate a measurement signal related to the vibration of the core drill and to transmit the measurement signal to the electronic control unit. The electronic control unit receives the measurement signal from the at least one vibration sensor and controls the current to the first actuator in response to the measurement signal from the at least one vibration sensor, thereby controlling the generation of the vibration force in the first actuator in response to these measurement signals. If the core drill comprises a second electrically controlled vibration actuator, the control unit may also be configured to control the current to the second actuator so as to control the generation of the vibration force in the second actuator in response to the measurement signal.

[0028] The at least one vibration sensor is preferably mounted on the front end of the elongated body or on the tool part. This will detect the vibration at a position close to the cutting element, which will make it possible to effectively cancel out the vibration induced by the cutting force acting on the cutting element.

[0029] Further advantageous features of the drilling mechanism according to the present invention will become apparent from the following description.

[0030] A specific description of an embodiment of the present invention, mentioned by way of example, will be described below with reference to the accompanying drawings.

Brief Description of the Drawings

[0031]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7a

Figure 7b

Figure 7c

Figure 8a

Figure 8b

Figure 8c

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Mode for Carrying Out the Invention

[0032] The non-rotating hole machining tool 1 according to an embodiment of the present invention is illustrated in FIGS. 1 to 5. The hole machining tool 1 is used for performing a machining operation in the form of internal diameter turning on a rotating metal material workpiece. The hole machining tool 1 includes a boring bar 2, which is to be fixed to a support structure 3 of a metal cutting machine (very schematically illustrated in FIGS. 9 to 11) so as to protrude from this support structure 3 in the form of a cantilever beam. The boring bar 2 includes an elongated body 6 configured to be attached to the support structure 3 of the metal cutting machine. The elongated body 6 has a front end portion 6a on the side opposite to the rear end portion 6b. The longitudinal axis 7 of the elongated body extends between the rear end portion 6b and the front end portion 6a of the elongated body.

[0033] The hole machining tool 1 also includes a tool portion 4 having a cutting element 5, and this tool portion 4 is carried by the elongated body 6 and attached to the elongated body at its front end portion 6a. Alternatively, the tool portion 4 may be integrally formed with the front end portion 6a of the elongated body, which implies that the tool portion 4 and the elongated body 6 are combined to form a common component.

[0034] The boring bar 2 includes an electrically controlled vibration actuator 8 for active vibration damping of the boring bar 2. This actuator 8 includes a damping mass 9 arranged to be movable, and the movement of this damping mass is configured to generate a vibration force parallel or at least substantially parallel to the action axis 10 of the actuator. The actuator 8 is a single-axis actuator having one single action axis 10.

[0035] The actuator 8 is configured to generate a vibration force to cancel out the vibration induced in the boring bar 2 by the cutting force acting on the cutting element 5 during the machining of the rotating workpiece. The vibration force generated by the actuator 8 may also be used to intermittently vibrate the cutting element 5 in order to break up larger metal chips cut from the workpiece by the cutting element 5 into small pieces.

[0036] The actuator 8 may be of the electromagnetic type, in which case the vibration force is generated electromagnetically. However, any other suitable type of vibrating actuator may also be used.

[0037] The cutting element 5 fixed to the tool part 4 may be a positive cutting element as shown in FIGS. 7a to 7c, or a negative cutting element as shown in FIGS. 8a to 8c. The cutting element 5 includes an upper rake face 30, a bottom face 31 extending parallel or substantially parallel to the rake face 30, and a peripheral relief face 32 extending between the rake face 30 and the bottom face 31. The cutting edge 33 is formed at the portion where the rake face 30 and the relief face 32 intersect. In the illustrated example, the cutting edge 33 extends along the entire circumference of the rake face 30 along its periphery. In the case of the positive cutting element 5, as shown in FIG. 7c, the relief face 32 extends at an acute angle φ with respect to the rake face 30. In the case of the negative cutting element 5, as shown in FIG. 8c, the relief face 32 extends perpendicular to the rake face 30.

[0038] A hole 34 extends across the cutting element 5 between the rake face 30 and the bottom face 31. The cutting element 5 is configured to be removably attached to the tool part 4, and at this time, the bottom face 31 of the cutting element 5 is abutted and held on a support surface 35 (see FIG. 6) on a seat provided for the cutting element on the tool part 4. The cutting element 5 is fixed to the seat of the tool part 4 by a fixing element 36 in the form of a screw (see FIG. 5), and this screw extends through the hole 34 of the cutting element 5 and engages into a threaded hole of the support surface 35 on the seat.

[0039] In the illustrated example, the cutting element 5 comprises two cutting corners 37 positioned opposite each other on both sides of the cutting element. The cutting element 5 is to be fixed to the tool part 4 with one of the cutting corners 37 facing outward away from the longitudinal axis 7 of the elongated body 6, and the cutting element 5 is intended to contact the rotating workpiece via this outward-facing cutting corner 37. During the internal diameter turning of the rotating workpiece, the hole machining tool 1 is usually positioned relative to the workpiece such that the tangential force F on the cutting element 5 as described above is directed at an angle θ of approximately 6° with respect to the flank face 32 t will be oriented.

[0040] First and second reference lines L1, L2 (see FIG. 6), which are virtual straight lines, are defined in a plane in the cross-sectional direction that is perpendicular to the longitudinal axis 7 of the elongated body 6 and intersect the cutting edge 33 at the radially outermost point 39. The first reference line L1 intersects the cutting edge 33 at the radially outermost point 39 and extends in this plane in the cross-sectional direction at an angle β of 6° with respect to the flank face 32 outside the cutting element 5, i.e., this angle β is measured outside the cutting element 5. Thus, when a positive cutting element 5 of the type shown in FIGS. 7a - 7c with a 6° flank angle is fixed to the tool part 4, the first reference line L1 can extend perpendicular to the rake face 30 of the cutting element, as shown in FIG. 6.

[0041] The second reference line L2 intersects the cutting edge 33 at the radially outermost point 39 and extends between the rake face 30 and the flank face 32 at an angle α in the range of 10 - 40° with respect to the first reference line L1.

[0042] The actuator 8 is arranged within the elongated body 6 in a position such that its axis of action 10 extends parallel or at least substantially parallel to the second reference line L2. Thus, when viewed in the above-described plane in the cross-sectional direction, the axis of action 10 of the actuator 8 forms an angle of 10 - 40° with respect to the first reference line L1.

[0043] Actuator 8 is preferably arranged within the elongated body 6 such that the central axis 11 of the actuator is aligned or substantially aligned with the longitudinal axis 7 of the elongated body.

[0044] The working axis 10 of actuator 8 extends perpendicular to its central axis 11. Further, the working axis 10 of actuator 8 extends within a plane in the cross-sectional direction perpendicular to the longitudinal axis 7 of the elongated body 6.

[0045] In the embodiment illustrated in FIGS. 1 to 5, the elongated body 6 of the reamer bar 2 is composed of individual parts 12, 13, 14, which are connected to each other and together form the elongated body 6, and these parts 12, 13, 14 constitute individual length sections, i.e., individual segments, of the elongated body 6. Thus, these parts 12, 13, 14 constitute continuous sections of the elongated body 6 of the reamer bar when viewed in its longitudinal direction. In this case, the elongated body 6 comprises an elongated main part 12 configured to be attached to the support structure 3 of the metal cutting machine. This main part 12 has a front end 12a opposite to the rear end 12b. The main part 12 is preferably tubular and will be attached to the support structure 3 at its rear end 12b. In the illustrated embodiment, the main part 12 is cylindrical and has a circular cross-sectional shape. However, the main part 12 may also have any other suitable cross-sectional shape, such as an elliptical or polygonal cross-sectional shape.

[0046] The elongated body 6 shown in FIGS. 1 to 5 further includes a front portion 13. This front portion 13 has a rear end portion 13b facing the front end portion 12a of the main portion 12 and a front end portion 13a on the opposite side. The front end portion 13a of the front portion is arranged to carry the above-described tool portion 4. Accordingly, this tool portion 4 is attached to the front portion 13 of the elongated body at its front end portion 13a. Alternatively, the tool portion 4 may be integrally formed with the front portion 13, which implies that the tool portion 4 and the front portion 13 are combined to form a common component. In the illustrated embodiment, the front portion 13 is cylindrical and has a circular cross-sectional shape. However, the front portion 13 may also have any other suitable cross-sectional shape, such as an elliptical or polygonal cross-sectional shape.

[0047] The elongated body 6 shown in FIGS. 1 to 5 also includes a damping module 14 disposed between the front end portion 12a of the main portion 12 and the rear end portion 13b of the front portion 13. This damping module 14 has a rear end portion 14b facing the main portion 12 and a front end portion 14a on the opposite side facing the front portion 13. The front portion 13 is connected to the main portion 12 via the damping module 14. In the illustrated embodiment, the damping module 14 is cylindrical and has a circular cross-sectional shape. However, the damping module 14 may also have any other suitable cross-sectional shape, such as an elliptical or polygonal cross-sectional shape.

[0048] The damping module 14 houses an actuator 8. The actuator 8 is disposed within the housing 15 of the damping module, and the damping mass 9 of the actuator 8 is movable relative to this housing 15. In the illustrated embodiment, the damping mass 9 is movable relative to the housing 15 of the damping module 14 against the action of the return springs 16 disposed on both sides of the damping mass 9.

[0049] As shown in FIGS. 1, 2, and 5, the outer periphery 18 of the main portion 12 and the outer periphery 19 of the damping module 14 are preferably flush or substantially flush with each other. Further, the outer periphery 20 of the front portion 13 is preferably flush or substantially flush with the outer periphery 19 of the damping module 14.

[0050] To facilitate the maintenance and repair of the boring bar 2, the main portion 12, the damping module 14, and the front portion 13 are preferably detachably attached to each other. In the illustrated embodiment, the damping module 14 is sandwiched between the main portion 12 and the front portion 13 by the connecting rods 22. Each connecting rod 22 has a first end 22a fixed to the main portion 12 and an opposite second end 22b fixed to the front portion 13. Further, each connecting rod 22 extends through the passage 23 of the damping module 14. The different portions 12, 13, 14 of the elongated body 6 may alternatively be attached to each other in any other suitable manner.

[0051] In the illustrated embodiment, the actuator 8 within the damping module 14 is accessible through two openings on both sides of the damping module, each opening being covered by a removably attached cover 24, which cover 24 forms part of the outer periphery 19 of the damping module and is secured within the associated opening by a securing element 25 in the form of a screw. Passages 23 for some of the above-described connecting rods 22 may be provided in the cover 24.

[0052] In the illustrated embodiment, cooling fluid is supplied to the tool portion 4 through a first feed pipe 26 extending axially through a main portion 12 of the elongated body 6 and at least one second feed pipe 27 extending parallel to the connecting rod 22 between the main portion 12 and the front portion 13 of the elongated body. In the example shown, the drill rod 2 comprises two such second feed pipes 27. The first feed pipe 26 is fixed to the main portion 12 of the elongated body by a first end piece 28a fixed to the main portion 12 at its front end 12a and a second end piece 28b fixed to the main portion 12 at its rear end 12b. Each one of the second feed pipes 27 is connected to the first feed pipe 26 via an internal channel of the first end piece 28a. Still further, each one of the second feed pipes 27 can be arranged to extend through mutually aligned passages 29 of the damping module 14.

[0053] To enable adjustment of the angular position of the axis of action 10 of the actuator 8 relative to the cutting element 5, the front portion 13 of the elongate body 6 may be adjustable in its rotational position relative to the damping module 14, which suggests that the front portion 13 can be attached to the damping module 14 in various selectable rotational positions relative to the damping module. As an alternative to, or in combination with, the rotational adjustment of the front portion 13 relative to the damping module 14 being thus possible, the tool portion 4 equipped with the cutting element 5 may be adjustable in its rotational position relative to the front portion 13 of the elongate body, which suggests that the tool portion 4 can be attached to the front portion 13 in various selectable rotational positions relative to the front portion. The damping module 14 may also be arranged such that its actuator 8 can have its rotational position adjusted relative to the casing of the damping module. The rotational position of the actuator 8, i.e., its angular position relative to the cutting element 5, can be adjusted steplessly or stepwise. The optimal rotational position of the actuator may be calculated in advance, i.e., before the machining process of the workpiece is started, based on the cutting data and / or the properties of the workpiece material and / or the cutting conditions. The optimal rotational position of the actuator means the rotational position in which the axis of action of the actuator is oriented parallel to the resultant force F res and. However, during the machining process, the rotational position of the actuator may also be controlled, preferably by an electronic control unit arranged in / included in a suitable type of motor, which is configured to control the current to the motor so as to control and adjust the angular position of the motor and thereby adjust the rotational position of the actuator to its optimal rotational position. The electronic control unit configured to control the current to the motor may be the same electronic control unit 41 or a separate one.

[0054] Different embodiments of the drilling mechanism 40 with the above-described type of core drill 2 are very schematically illustrated in FIGS. 9 to 11. The drilling mechanism 40 further comprises an electronic control unit 41 configured to control the supply of current to the actuator 8 in order to control the generation of the vibration force in the actuator 8 within the elongated body 6. The current is supplied from a power source to the actuator 8, which power source may be an external power source 42 as illustrated in FIG. 9, or a power supply unit 42' mounted on the elongated body 6 as illustrated in FIG. 11, or on the support structure 3 or any other part of the metal cutting machine as illustrated in FIG. 10. The power supply unit 42' comprises at least one energy storage member, for example in the form of a battery for storing electrical energy. The electronic control unit 41 may be mounted on the front portion 13 of the elongated body 6 as illustrated in FIGS. 10 and 11, or on any other part of the elongated body. 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 illustrated in FIG. 9.

[0055] The drilling mechanism 40 further comprises at least one vibration sensor 43, for example in the form of an accelerometer, configured to generate a measurement signal related to the vibration of the core drill 2 and to transmit the measurement signal to the electronic control unit 41 via a wireless connection or a cable connection. The at least one vibration sensor 43 is preferably mounted on the front portion 13 of the elongated body 6 or on the tool portion 4, but alternatively may be mounted on any other suitable part of the elongated body 6.

[0056] The electronic control unit 41 is configured to receive the measurement signal from the at least one vibration sensor 43 and, in response to these measurement signals, to control the supply of current to the actuator 8, thereby controlling the generation of the vibration force in the actuator 8 in response to these measurement signals, so as to counteract the vibration induced in the core drill 2 by the cutting force F r 、F t exerted on the cutting element 5 during the machining of the workpiece.

[0057] In the embodiments illustrated in FIGS. 1 to 5, the boring bar 2 includes only one vibration actuator 8. However, as an alternative, the boring bar 2 may include one or more additional electrically controlled vibration actuators for active vibration damping of the boring bar.

[0058] In the embodiments illustrated in FIGS. 12 and 13, the boring bar 2 includes first and second electrically controlled vibration actuators 8a, 8b for active vibration damping of the boring bar 2. The first vibration actuator 8a has the same design as the actuator 8 described above with reference to FIGS. 1 to 5 and is arranged in the elongated body 6 in the same manner as this actuator 8. Thus, the first actuator 8a is a single-axis actuator having one single-action axis 10a, and the action axis 10a thereof extends in a state parallel or at least substantially parallel to the second reference line L2 described above and is arranged in the elongated body 6. The second actuator 8b is likewise a single-axis actuator having one single-action axis 10b and may be an actuator of the same type as the first actuator 8a. The second actuator 8b is arranged longitudinally continuously with the first actuator 8a in the elongated body 6. Thus, the first and second actuators 8a, 8b are arranged continuously in the longitudinal direction of the elongated body 6, and preferably, the central axis 11a of the first actuator 8a and the central axis 11b of the second actuator 8b are aligned or substantially aligned with each other.

[0059] The first and second actuators 8a, 8b are arranged with the angles of their action axes 10a, 10b shifted from each other, preferably arranged perpendicular to each other. In the example illustrated in FIGS. 12 and 13, the second actuator 8b is arranged between the tool part 4 and the first actuator 8a. However, the first and second actuators 8a, 8b are preferably arranged in the opposite order, i.e., the first actuator 8a is arranged between the tool part 4 and the second actuator 8b.

[0060] In the embodiment illustrated in FIGS. 12 and 13, the elongated body 6 includes the main portion 12 and the front portion 13 of the type described above with reference to FIGS. 1 to 5. The elongated body 6 illustrated in FIGS. 12 and 13 further includes two damping modules 14 of the type described above with reference to FIGS. 1 to 5, and these damping modules 14 are arranged in series with each other between the front end portion 12a of the main portion 12 and the rear end portion 13b of the front portion 13. In this case, the first and second actuators 8a, 8b are arranged in different damping modules 14. However, the first and second actuators 8a, 8b may alternatively be arranged in one and the same damping module 14.

[0061] In the embodiment illustrated in FIGS. 12 and 13, the damping modules 14 are in direct contact with each other, and the rear end portion 14b of the foremost one of the damping modules abuts against the front end portion 14a of the other damping module, that is, the rearmost damping module. As illustrated in FIGS. 12 and 13, the front portion 13 may be arranged such that its rear end portion 13b abuts directly against the front end portion 14a of the foremost damping module, and the rearmost damping module may be arranged such that its rear end portion 14b abuts directly against the front end portion 12a of the main portion 12.

[0062] When the elongated body 6 includes three or more vibration actuators, the elongated body may include three or more damping modules 14. When the number of damping modules 14 is two or more, they may be arranged such that their respective rotational positions are adjustable relative to each other.

[0063] Naturally, the present invention is not limited in any sense to the above-described embodiments. On the contrary, it will be apparent to those skilled in the art that various modifications of these embodiments are possible without departing from the basic idea of the present invention as defined in the appended claims.

Claims

1. A boring bar (2) comprising an elongated body (6) configured to be attached to a support structure of a metal cutting machine, the elongated body (6) having a rear end portion (6b) and an opposite front end portion (6a), the boring bar (2); A tool portion (4) having a cutting element (5), the tool portion (4) being removably attached to or integrally formed with the front end portion (6a) of the elongated body (6), the cutting element (5) comprising a rake face (30), a flank face (32), and a cutting edge (33) formed at a portion where the rake face and the flank face intersect, and when viewed in a cross-sectional plane perpendicular to the longitudinal axis (7) of the elongated body (6) and intersecting the cutting edge (33) at the radially outermost point (39); A first reference line L1, which is a virtual straight line, intersects the cutting edge (33) at the radially outermost point (39) and extends at an angle (β) of 6° with respect to the flank face (32) outside the cutting element (5); A second reference line L2, which is a virtual straight line, intersects the cutting edge (33) at the radially outermost point (39) and extends at an angle (α) of 10 to 40° with respect to the first reference line L1 between the rake face (30) and the flank face (32), the tool portion (4); A non-rotating hole machining tool for internal turning, comprising; The boring bar (2) comprises a first electrically controlled vibration actuator (8, 8a) for active vibration damping of the boring bar (2), the first actuator (8, 8a) being configured to generate a vibration force parallel or substantially parallel to the action axis (10, 10a) of the first actuator, and the first actuator (8, 8a) being a single-axis actuator having one single action axis (10, 10a); The first actuator (8, 8a) is disposed within the elongated body (6) with its action axis (10, 10a) extending parallel or substantially parallel to the second reference line L2; The boring bar (2) includes a second electrically controlled vibration actuator (8b) for active vibration damping of the boring bar (2), and the second actuator (8b) is configured to generate a vibration force parallel or substantially parallel to the action axis (10b) of the second actuator. The second actuator (8b) is a uniaxial actuator having one single action axis (10b), and the second actuator (8b) is arranged longitudinally in series with the first actuator (8a) within the elongated body (6). The first and second actuators (8a, 8b) are arranged with the angles of their action axes (10a, 10b) offset from each other, and the first actuator (8a) is preferably arranged between the tool portion (4) and the second actuator (8b). A non-rotating hole machining tool for internal diameter turning, characterized by the above. **Claim 2** The non-rotating hole machining tool according to claim 1, wherein the first actuator (8, 8a) is arranged within the elongated body (6) such that the central axis (11, 11a) of the first actuator is aligned or substantially aligned with the longitudinal axis (7) of the elongated body. **Claim 3** The non-rotating hole machining tool according to claim 1 or 2, characterized in that the first actuator (8, 8a) is adjustable in its rotational position within the elongated body (6) and / or the tool portion (4) is adjustable in its rotational position relative to the elongated body (6). **Claim 4** The non-rotating hole machining tool according to claim 1, characterized in that the first and second actuators (8a, 8b) are arranged with their action axes (10a, 10b) perpendicular to each other. **Claim 5** The non-rotating hole machining tool according to any one of claims 1 to 4, characterized in that the first and second actuators (8a, 8b) are arranged within the elongated body (6) such that the central axis (11a) of the first actuator and the central axis (11b) of the second actuator are aligned or substantially aligned with each other. **Claim 6** The elongated body (6) is an elongated main portion (12) configured to be attached to the support structure, the elongated main portion (12) having a rear end portion (12b) and an opposite front end portion (12a). A front portion (13) having a rear end portion (13b) facing the front end portion (12a) of the main portion (12) and an opposite front end portion (13a), wherein the front end portion (13a) of the front portion (13) is arranged to carry the tool portion (4), and at least one damping module (14) disposed between the front end portion (12a) of the main portion (12) and the rear end portion (13b) of the front portion (13) and housing the first actuator (8, 8a) and / or the second actuator (8b). The front portion (13) of the elongated body (6) is connected to the main portion (12) via the at least one damping module (14), and the at least one damping module (14) constitutes a certain length section of the elongated body (6). A non-rotating hole machining tool according to any one of claims 1 to 5, characterized in that.

7. The non-rotating hole machining tool according to claim 6, characterized in that the main portion (12) and / or the front portion (13) and / or the at least one damping module (14) is cylindrical, preferably a true circular cylinder.

8. The non-rotating hole machining tool according to claim 6 or 7, characterized in that the outer periphery (18) of the main portion (12) and the outer periphery (19) of the at least one damping module (14) are flush with each other or substantially flush.

9. The non-rotating hole machining tool according to any one of claims 6 to 8, characterized in that the at least one damping module (14) is clamped between the main portion (12) and the front portion (13) by a connecting rod (22) preferably extending through a passage (23) of the at least one damping module (14).

10. The non-rotating hole machining tool according to any one of claims 6 to 9, characterized in that the first and second actuators (8a, 8b) are housed in the same damping module (14).

11. The elongated body (6) includes at least two of the damping modules (14) arranged in series with each other between the front end portion (12a) of the main portion (12) and the rear end portion (13b) of the front side portion (13), and the first and second actuators (8a, 8b) are arranged in different ones of the damping modules (14). The non-rotating hole machining tool according to any one of claims 6 to 9, characterized in that.

12. A non-rotating hole machining tool (1) according to any one of claims 1 to 11, An electronic control unit (41) configured to control the current to the first actuator (8, 8a) to control the generation of the vibration force in the first actuator. A hole machining mechanism for internal diameter turning, characterized in that it comprises.

13. The hole machining mechanism (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) controls the current to the first actuator (8, 8a) according to the measurement signal from the at least one vibration sensor (43), thereby controlling the generation of the vibration force in the first actuator (8, 8a) according to the measurement signal. The hole machining mechanism according to claim 12, characterized in that.

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