Ultrasonic drilling device

Abstract

Ultrasonic drilling device (300) with a sonotrode (310) and with an ultrasonic drilling tool (320), characterized in that a mechanical interface (350) is provided at which the ultrasonic drilling tool (320) can be connected to the sonotrode (310) in a vibration-resistant and detachable manner, wherein the sonotrode (310) has a substantially cylindrical end mass (312) with an integrally formed sonotrode rod (314) which is formed concentrically to a longitudinal central axis (150) of the end mass (312) and is directed axially away from it, wherein a diameter (D E ) the final mass (312) greater than a diameter (D S ) of the sonotrode rod (314), wherein the mechanical interface (350) is arranged in the area of ​​a free end (352) of the sonotrode rod (314) formed receiving section (354) for low-loss transmission of the ultrasonic vibration (120) from the sonotrode (310) to the ultrasonic drilling tool (320).

Description

State of the art

[0001] The invention relates to an ultrasonic drilling device with a sonotrode and with an ultrasonic drilling tool.

[0002] Ultrasonic drilling machines are known in a wide variety of designs. The impact frequency of an ultrasonic drilling machine typically ranges between 20 kHz and 200 kHz. The oscillation system of such an ultrasonic drilling machine generally comprises a vibration actuator, e.g., a piezoelectric vibration actuator, which is connected to a drilling sonotrode via a thread. The actuator and the drilling sonotrode are operated, for example, in their individual, first longitudinal natural modes at the same frequency. This is possible because the natural frequencies of both components are the same. However, higher vibration modes are also possible with the drilling sonotrode.

[0003] To achieve the largest possible deflection amplitudes in the drill head area of ​​an ultrasonic drill, large transformations within the oscillating system are necessary. These transformations can be achieved, for example, with a drilling sonotrode featuring a solid cylindrical end mass and a smaller-diameter, essentially cylindrical ultrasonic drill bit with a phase length of at least approximately π / 2, which is integrally connected axially to it. To further optimize drilling performance, ultrasonic drill bits are often equipped, at least in sections, with a helix and, in the drill head area, with a carbide plate or a carbide head. Disclosure of the invention

[0004] The present invention relates to an ultrasonic drilling device comprising a sonotrode and an ultrasonic drilling tool. A mechanical interface is provided at which the ultrasonic drilling tool can be connected to the sonotrode in a vibration-resistant and detachable manner, wherein the mechanical interface is designed to enable low-loss transmission of the ultrasonic vibration from the sonotrode to the ultrasonic drilling tool.

[0005] The invention thus enables the ultrasonic drilling tool to be easily and quickly replaced with a new, unused ultrasonic drilling tool when needed, for example, in case of wear. Furthermore, the non-integral design of the sonotrode and ultrasonic drilling tool significantly simplifies the manufacturing process of the ultrasonic drilling tool, as the ultrasonic drilling tool can be manufactured from a cylindrical, metallic semi-finished product with a significantly smaller diameter compared to the diameter of the sonotrode.

[0006] Preferably, the ultrasonic drilling tool has a substantially cylindrical shaft section with a helix formed at least partially on it and a free head section with a cutting element and / or a crushing element.

[0007] As a result, the ultrasonic drilling tool achieves a comparatively good drilling progress when drilling a hole in a workpiece, while at the same time the resulting workpiece material is effectively removed from the hole.

[0008] Preferably, the sonotrode has a substantially cylindrical end mass with an integrally formed sonotrode rod, which is formed concentrically to a longitudinal central axis of the end mass and directed axially away from it, wherein a diameter of the end mass is larger than a diameter of the sonotrode rod.

[0009] Due to the sonotrode's final mass, comparatively high deflection amplitudes can be achieved at the head section of the ultrasonic drilling tool. The diameter of the sonotrode rod preferably corresponds approximately to the diameter of the ultrasonic drilling tool.

[0010] According to a technically advantageous design, the length of the sonotrode rod and the length of the ultrasonic drilling tool are dimensioned such that the mechanical interface lies axially in the area of ​​a minimum ultrasonic load.

[0011] This reduces the mechanical stress on the interface caused by the ultrasonic vibration, with the ultrasonic load corresponding to a maximum of the ultrasonic displacement amplitude. For this purpose, the sonotrode rod preferably has a phase length that is at least approximately half the length of a corresponding phase length of the ultrasonic drilling tool, the length of which preferably corresponds to half the wavelength of the ultrasonic vibration.

[0012] Preferably, the mechanical interface for the axial connection of the sonotrode and ultrasonic drilling tool along the longitudinal center axis is formed with a receiving section of the sonotrode rod and with a fastening section of the ultrasonic drilling tool.

[0013] This effectively protects the preferably internally designed receiving section of the sonotrode rod from external mechanical damage.

[0014] According to a technically advantageous embodiment, the receiving section has an internal thread and the fastening section has an external thread corresponding to the internal thread.

[0015] Due to the threaded connection, a comparatively vibration-resistant mechanical coupling is ensured, particularly in the axial direction. During operation of the ultrasonic drilling device, unintentional loosening is preferably prevented by continuously tightening the threaded connection based on a predetermined direction of rotation of the ultrasonic drilling device and the torque thereby transmitted to it. Additionally and optionally, the external thread can be provided with a polymeric and, if necessary, releasable threadlocker, such as Loctite®, etc. Alternatively, the interface can also be implemented with a plug connection, a clamp connection, a bayonet connection, or any other suitable connection, in which, in particular, there is no axial play.

[0016] According to a further development, the fastening section has a radially outwardly directed flange as a stop for a free end face of the sonotrod rod.

[0017] This ensures a reliable, form-fit and friction-fit mechanical coupling between the sonotrode and the ultrasonic drilling tool. The mounting section is located at the end of the ultrasonic drilling tool facing away from the head section.

[0018] Preferably, the ultrasonic drilling tool has at least one contact surface.

[0019] This allows the ultrasonic drilling tool to be rotated around the longitudinal center axis using a suitable tool with increased torque.

[0020] Preferably, the ultrasonic drilling tool is made of a steel alloy.

[0021] As a result, a significant extension of the service life or lifespan of the ultrasonic drilling tool is possible. For example, high-speed steel with the alloy composition 1.3343 S 6-5-2, preferably subjected to suitable heat treatment, can be used as the steel alloy.

[0022] Preferably, radial centering is provided between the ultrasonic drilling tool and the sonotrod rod.

[0023] This allows for an improvement in the concentricity of the ultrasonic drilling device. Brief description of the drawings

[0024] The invention is explained in more detail below with reference to exemplary embodiments illustrated in the drawings. The drawings show: Fig. 1 a schematic view of an ultrasonic drilling machine, Fig. 2 A perspective side view of the ultrasonic drilling tool with the sonotrode of the ultrasonic drilling machine from Fig. 1, and Fig. 3 a longitudinal section of the ultrasonic drilling tool with the sonotrode of Fig. 2. Description of the exemplary implementations

[0025] Fig. Figure 1 shows a hand-held ultrasonic drilling machine 100 with a tool housing 180, to which an ergonomically shaped handle 185 is assigned for preferably one-handed gripping by a user. For illustrative purposes, the handle 185 of the tool housing 180 of the ultrasonic drilling machine 100 contains an electric hand switch 170, which can be operated by the user's finger, for switching an electronic control unit 200 on and off.

[0026] The tool housing 180 also contains an electric or pneumatic drive motor 130, which is designed for the rotary drive of an optional gearbox 140. The gearbox 140 preferably rotaryally drives a piezoelectric vibration actuator 105, as indicated by a double arrow 250.

[0027] The piezoelectric vibration actuator 105, which rotates when the drive motor 130 is activated or switched on, preferably serves to generate a comparatively intense, longitudinal, i.e., axial, ultrasonic vibration 120, which preferably acts substantially along a longitudinal central axis 150 of the ultrasonic drilling device 300 and which can be superimposed on the rotational movement of the vibration actuator 105. The ultrasonic vibration 120 emitted by the vibration actuator 105 preferably has a vibration frequency in the range of 20 kHz to 200 kHz.

[0028] For the sake of clarity, the oscillating elements of the oscillating actuator 105, which are not shown in the diagram, are preferably formed, at least partially, with a suitable piezoelectric material and can, for example, be ring-shaped. The oscillating actuator 105 will therefore be referred to below simply as the "piezo actuator." Such a piezo actuator with exemplary ring-shaped, piezoelectrically operating oscillating elements is described in detail, among other places, in WO 2010 / 076230 A1, the disclosure of which is hereby explicitly incorporated into the present application, so that a more detailed explanation of the construction of the piezo actuator 105 and its function can be omitted here.

[0029] An ultrasonic drilling device 300 associated with the ultrasonic drilling machine 100 preferably comprises a preferably solid sonotrode 310 and an ultrasonic drilling tool 320 for machining a metallic and / or mineral workpiece 160, illustrated by the creation of a borehole 162. The sonotrode 310 is preferably mechanically coupled to the piezo actuator 105 in a suitable manner, but can also be integrally formed with it. Furthermore, a mechanical interface 350 is provided by means of which the ultrasonic drilling tool 320 can be connected to the sonotrode 310 in a vibration-resistant manner and preferably, if necessary, in a way that is at least comparatively easy for the user to detach. The mechanical interface 350 is preferably designed to provide a connection with minimal loss or...to ensure low-damping transmission of the ultrasonic vibration 120 from the sonotrode 310 to the ultrasonic drilling tool 320, including the rotational movement of the piezo actuator 105 indicated by the double arrow 250.

[0030] By way of example only, the ultrasonic drilling machine 100 can be electrically connected to an AC power supply network via a mains cable 190. However, it should be noted that the present invention is not limited to mains-powered ultrasonic drilling machines, but can be applied to a wide variety of handheld power tools in which a piezo actuator is used for the oscillating drive of an associated ultrasonic drilling tool, regardless of whether the power tool can be operated via mains power and / or battery packs. According to a preferred embodiment not shown in the drawings, the ultrasonic drilling machine 100 can be operated via a battery pack.

[0031] In an exemplary operation of the ultrasonic drilling machine 100, the electronic control unit 200 is supplied with alternating current via the mains supply line 190 by the user when the electric hand switch 170 is pressed down, thereby activating or switching it on. As a result, the control unit 200 generates an electrical excitation signal 210, suitable, for example, for pulsed or continuous control of the piezo actuator 105, so that the ultrasonic vibration 120 is generated.

[0032] The frequency of the ultrasonic vibration 120 can preferably be continuously adjustable by means of the electronic control unit 200, for example, depending on the workpiece 160 to be machined, wherein the frequency of the ultrasonic vibration 120 is preferably kept substantially constant during a machining operation. Preferably simultaneously with the activation of the piezo actuator 105, the drive motor 130 for the rotary drive of the ultrasonic drilling device 300 is switched on by the electronic control unit 200, monitored by an electronic control signal 220. The drive motor 130 and the piezo actuator 105 can preferably be switched on and off independently of each other by means of the electronic excitation signal 210 and the control signal 220.

[0033] Fig. Figure 2 shows the ultrasonic drilling device 300 from Fig. 1 with the sonotrode 310 and the ultrasonic drilling tool 320. The ultrasonic drilling tool 320 preferably has a cylindrical shaft section 322 with a helix 324 formed at least partially thereon and a free head section 326 with a cutting element 328. The helix 324 ensures reliable removal of material from the borehole 162. Fig. 1. Friction and wear of the ultrasonic drilling tool 320 are minimized. To ensure the longest possible service life, the ultrasonic drilling tool 320 is preferably made of a high-strength steel alloy, such as a high-speed steel with the alloy composition 1.3343 S 6-5-2. The at least one cutting element 328, or a corresponding crushing element, is preferably formed with a carbide insert to further improve the service life of the ultrasonic drilling tool 320 when machining workpieces, especially mineral ones.

[0034] It should be noted that a crushing element can also be provided instead of the cutting element 328. This is useful, for example, in the case of ultrasonic drilling tools for drilling into rock to crush the respective subsurface.

[0035] Preferably, four plane contact surfaces are formed at an end 330 of the cylindrical shaft section 322 of the ultrasonic drilling tool 320, directed away from the free head section 326. Only two contact surfaces 332 and 334 are visible here. The four contact surfaces, which meet at right angles around their circumference, form, by way of example, a engagement geometry 336 with an approximately square cross-sectional geometry, which is intended for rotating the ultrasonic drilling tool 320 about the longitudinal center axis 150 by means of a rotary tool not shown in the drawings. In contrast, a variety of alternative engagement geometries are possible, such as an external hexagon, multiple teeth, or the like.

[0036] The preferably one-piece sonotrode 310 preferably has an end mass 312, which is here only by way of example essentially cylindrical, with a preferably integrally formed, likewise approximately cylindrical, sonotrode rod 314. The sonotrode rod 314 is preferably concentric to the longitudinal central axis 150 of the end mass 312 and directed axially away from it. A diameter D E The final mass 312 is preferably larger – preferably significantly larger – than a diameter D. S of the sonotrode rod 314.

[0037] The mechanical interface 350 preferably provides a vibration-resistant mechanical connection between the sonotrode 310 and the ultrasonic drilling tool 320 of the ultrasonic drilling device 300, which can be easily released by the user if necessary. As a result, the ultrasonic drilling tool 320 can be replaced, for example, in case of wear or if it is necessary to use a different type of tool, such as an ultrasonic drilling tool with a different diameter, a different helix geometry and / or a differently designed free head section.

[0038] Fig. Figure 3 shows the ultrasonic drilling device 300 from Fig. 2 with the sonotrode 310 and the ultrasonic drilling tool 320 from Fig. 2. The end mass 312 of the sonotrode 310 preferably extends axially into the cylindrical sonotrode rod 314. The ultrasonic drilling tool 320 is preferably connected to the sonotrode 310 with low damping and vibration resistance via the mechanical interface 350.

[0039] The ultrasonic drilling device 300 is preferably designed to be substantially rotationally symmetrical about the longitudinal center axis 150, which, for illustrative purposes, coincides with the x-axis of a coordinate system 400. The course of an axial deflection amplitude of the device, indicated by the double arrow 120, is shown on a U(x)-axis of the coordinate system 400 oriented perpendicular to the x-axis. Fig. 1 symbolized ultrasonic vibration 120 along the x-axis, i.e. over the longitudinal extent of the ultrasonic drilling device 300.

[0040] The mechanical interface 350 from Fig.2 is preferably realized with a receiving section 354 formed in the region of a free end 352 of the sonotrode rod 314 and with a fastening section 356 formed in the region of the end 330 of the ultrasonic drilling tool 320. The receiving section 354 is shown here only as an example with an internal thread 358, whereas the fastening section 356 is realized with an external thread 360 formed corresponding to the internal thread 358, such that the ultrasonic drilling tool 320 can be screwed into the sonotrode rod 314.

[0041] To simplify the insertion and removal of the ultrasonic drilling tool 320 into the sonotrode rod 314, the ultrasonic drilling tool 320 is provided with an engagement geometry 336 for a rotary tool (not shown in the drawings). To create a defined limit for the completion of this insertion process, a radially outwardly directed, annular flange 364 is preferably provided between the fastening section 356 and the engagement geometry 336 for the rotary tool. This flange acts as an axial stop for a free end face 366 of the sonotrode rod 314 when the ultrasonic drilling tool 320 is inserted.At the same time, the axial tension that develops between the screwed components when the stop is reached provides a reliable locking effect for the mechanical interface 350, preventing the ultrasonic drilling tool 320 from easily unscrewing itself from the sonotrode rod 314. Alternatively, a locking element, for example in the form of a polymeric threadlocker such as Loctite, can be used. ® or the like, between the internal thread 358 and the external thread 360.

[0042] To further improve the radial centering of the ultrasonic drilling tool 320 in the sonotrode rod 314 and consequently the concentricity of the ultrasonic drilling tool 320, a radial centering element 370 – indicated in the drawing only by the dotted diagonal lines – can be provided between the ultrasonic drilling tool 320 and the sonotrode rod 314. This radial centering element 370 can be achieved, for example, with a conical chamfer 372 at the free end 352 of the sonotrode rod 314 and with a conical chamfer 374 on the flange 364 that is complementary to the chamfer 372.

[0043] An axial length LS of the sonotrode rod 314 and an axial length L BThe components of the ultrasonic drilling tool 320 are preferably dimensioned such that the first longitudinal natural mode of vibration is established at the same frequency for the free individual components 310 and 320. The first longitudinal natural mode of vibration of the free individual components is characterized by a single node (U(x) = 0) and the predominantly axial displacements. This results in a distribution of the axial displacement U(x) that has a local extremum at 350. This is advantageously accompanied by a mechanical load that is proportional to the mechanical strain dU / dx and is therefore minimal or zero. For illustrative purposes, the axial length L corresponds to S of the sonotrode rod 314 approximately 1 / 4 of a wavelength λ of the axial displacement amplitude U(x) and the axial length L B The wavelength λ of the ultrasonic drilling tool 320 corresponds approximately to 1 / 2 of the axial deflection amplitude U(x).

[0044] Due to the inventive design of the ultrasonic drilling device 300 with the mechanical interface 350 between the ultrasonic drilling tool 320 and the sonotrode 310, the ultrasonic drilling tool 320 can be easily and quickly replaced by the user, for example, in case of wear or in case of a work-related replacement necessary. Furthermore, the manufacturing process of the sonotrode 310, which in previously known embodiments is generally more expensive, particularly due to the large diameter difference between the end mass 312 and the sonotrode rod 314, is significantly simplified compared to a one-piece design of the sonotrode 310 and ultrasonic drilling tool 320.

Claims

[1] Ultrasonic drilling device (300) with a sonotrode (310) and with an ultrasonic drilling tool (320), characterized by , that a mechanical interface (350) is provided at which the ultrasonic drilling tool (320) can be connected to the sonotrode (310) in a vibration-resistant and detachable manner, wherein the sonotrode (310) has a substantially cylindrical end mass (312) with an integrally formed sonotrode rod (314) which is formed concentrically to a longitudinal central axis (150) of the end mass (312) and is directed axially away from it, wherein a diameter (D E ) the final mass (312) greater than a diameter (D S ) of the sonotrode rod (314), wherein the mechanical interface (350) is arranged in the area of ​​a free end (352) of the sonotrode rod (314) formed receiving section (354) for low-loss transmission of the ultrasonic vibration (120) from the sonotrode (310) to the ultrasonic drilling tool (320). [2] Ultrasonic drilling device according to claim 1, characterized by , that the ultrasonic drilling tool (320) has a substantially cylindrical shaft section (322) with a helix (324) formed at least partially thereon and a free head section (326) with a cutting element (328) and / or a crushing element. [3] Ultrasonic drilling device according to one of the preceding claims, characterized by that a length (L S ) of the sonotrode rod (314) and a length (L B ) of the ultrasonic drilling tool (320) are dimensioned such that the mechanical interface (350) is axially located in the area of ​​a minimum ultrasonic load (dU(x) / dx). [4] Ultrasonic drilling device according to one of the preceding claims, characterized by, that the mechanical interface (350) for the axial connection of sonotrode (310) and ultrasonic drilling tool (320) along the longitudinal central axis (150) is formed with a receiving section (354) of the sonotrode rod (314) and with a fastening section (356) of the ultrasonic drilling tool (320). [5] Ultrasonic drilling device according to claim 4, characterized by , that the receiving section (354) has an internal thread (358) and the fastening section (356) has an external thread (360) corresponding to the internal thread (358). [6] Ultrasonic drilling device according to claim 5, characterized by , that the fastening section (356) has a radially outwardly directed flange (364) as a stop for a free end face (366) of the sonotrode rod (314). [7] Ultrasonic drilling device according to one of the preceding claims, characterized by , that the ultrasonic drilling tool (320) has at least one contact surface (332, 334). [8] Ultrasonic drilling device according to one of the preceding claims, characterized by , that the ultrasonic drilling tool (320) is made of a steel alloy. [9] Ultrasonic drilling device according to one of the preceding claims, characterized by , that a radial centering (370) is provided between the ultrasonic drilling tool (320) and the sonotrode rod (314).

Images