WO2018114321A1

WO2018114321A1 - Ultrasonic drilling device

Info

Publication number: WO2018114321A1
Application number: PCT/EP2017/081499
Authority: WO
Inventors: Thomas Winkler; Heiner Storck; Georg Stellmann; Michael Guenther; Joachim Platzer
Original assignee: Robert Bosch Gmbh
Priority date: 2016-12-19
Filing date: 2017-12-05
Publication date: 2018-06-28
Also published as: DE102016225455A1

Abstract

The invention relates to an ultrasonic drilling device (300), having a sonotrode (310) and having a ultrasonic drilling tool (320), wherein a mechanical interface (350) is provided, at which the ultrasonic drilling tool (320) can be detachably connected to the sonotrode (310) for conjoint vibration, wherein the mechanical interface (350) is designed to enable the low-loss transmission of the ultrasonic vibration from the sonotrode (310) to the ultrasonic drilling tool (320).

Description

description

title

Ultrasonic drilling device prior art

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

Ultrasonic drills in a wide range of variations are known from the prior art. The beat frequency of an ultrasonic drill usually moves in a frequency range between 20kHz and 200kHz. The vibration system of such an ultrasonic drilling machine generally comprises a vibration actuator, e.g. a piezoelectric vibration actuator threaded by a s.g. Bohrsonotrode is connected. The actuator and the boring sonotrode are e.g. operated in their individual, first longitudinal vibration mode at the same frequency. This is possible because the natural frequencies of both components are the same. However, the Bohrsonotrode also higher vibration modes are possible.

In order to achieve the greatest possible deflection amplitudes in the area of the drill head of an ultrasonic drill, large transformations within the oscillation system are required. These transformations can be achieved, for example, with a Bohrsonotrode with a solid cylindrical final mass and an axially integrally adjacent thereto, smaller diameter and substantially cylindrical ultrasonic drill with a phase length of at least approximately TT / 2. To further optimize the drilling performance ultrasonic drills are often at least partially provided with a helix and in the region of the drill head with a hard metal plate or a hard metal head. Disclosure of the invention

The present invention relates to an ultrasonic drilling device with a sonotrode and with an ultrasonic drilling tool. A mechanical interface is provided on which the ultrasonic drilling tool can be connected to the sonotrode in a vibration-proof and detachable manner, the mechanical interface being designed to enable a low-loss transmission of the ultrasonic vibration from the sonotrode to the ultrasonic drilling tool.

The invention thus makes it possible that the ultrasonic drilling tool can be easily and quickly replaced, if necessary, for example, in a wear case, against an unused, new ultrasonic drilling. Moreover, due to the non-integral design of sonotrode and ultrasonic boring tool, the manufacturing process of the ultrasonic boring tool can be considerably simplified, since the ultrasonic boring tool can be made of a cylindrical, metallic semi-finished product with a significantly smaller diameter compared to a diameter of the sonotrode.

The ultrasonic drilling tool preferably has a substantially cylindrical shaft section with a helix formed at least in sections thereon and a free head section with a cutting element and / or a fragmentation element.

As a result, there is a comparatively good drilling progress of the ultrasonic drilling when inserting a hole in a workpiece, at the same time resulting workpiece removal is effectively transported out of the bore.

Preferably, the sonotrode has a substantially cylindrical final mass with an integrally formed sonotrode rod, which is concentric with a longitudinal center axis of the final mass and axially directed away therefrom, wherein a diameter of the final mass is greater than a diameter of the Sonotrodenstabs. Due to the final mass of the sonotrode comparatively high deflection amplitudes at the head portion of the ultrasonic drilling tool can be realized. Of the Diameter of the sonotrode rod preferably corresponds approximately to a diameter of the ultrasonic drilling tool.

According to a technically favorable embodiment, a length of the sonotrodesstabs and a length of the ultrasonic drilling tool are dimensioned such that the mechanical interface is axially in the range of a minimum of the ultrasonic load.

As a result, the mechanical load on the interface is at least reduced by the ultrasonic vibration, the ultrasonic load corresponding to a maximum of the ultrasonic deflection amplitude. For this purpose, the sonotrode rod preferably has a phase length which is at least approximately half the size of a corresponding phase length of the ultrasonic drilling tool whose length preferably corresponds to half the wavelength of the ultrasonic vibration.

The mechanical interface for the axial connection of the sonotrode and the ultrasonic drilling tool along the longitudinal central axis is preferably formed with a receiving section of the sonotrode rod and with a fastening section of the ultrasonic drilling tool.

As a result, the preferably internally formed receiving portion of the sonotrode bar is effectively protected from mechanical external damage.

According to a technically advantageous embodiment, the receiving portion has an internal thread and the attachment portion a corresponding to the internal thread formed external thread. Due to the threaded connection, a comparatively vibration-resistant mechanical coupling is ensured, especially in the axial direction. A safeguard against unintentional loosening takes place during operation of the ultrasonic drilling device, preferably by a continuous tightening of the threaded connection on the basis of a predetermined direction of rotation of the ultrasonic drilling device and thereby a torque transmitted thereto. Additionally and optionally, in particular the external thread with a polymeric and optionally again releasable threadlocker, such as Loctite® etc., be provided. Alternatively, the interface can also be realized with a plug connection, a clamping connection, a bayonet connection or any other suitable connection, in which, in particular, there is no axial play.

According to a development, the attachment section has a radially outwardly directed flange as a stop for a free end face of the sonotrode rod.

As a result, a reliable positive and frictional mechanical coupling between the sonotrode and the ultrasonic drilling tool is given. The fastening section is in this case formed on an end remote from the head section of the ultrasonic drilling tool.

The ultrasonic drilling tool preferably has at least one contact surface.

In this way, the ultrasonic drilling tool can be rotated by means of a suitable tool with increased torque about the longitudinal center axis.

Preferably, the ultrasonic drilling tool is formed with a steel alloy.

As a result, a significant extension of the service life or the life of the ultrasonic drilling tool is possible. As the steel alloy, for example, the high-speed steel having the alloy composition of 1.3343 S 6-5-2, which is preferably subjected to a suitable heat treatment, can be used.

Preferably, a radial centering is provided between the ultrasonic drilling tool and the sonotrode rod.

Thus, a corresponding concentricity of the ultrasonic drilling apparatus can be improved.

Brief description of the drawings

The invention is based on exemplary embodiments shown in the drawings. play explained in more detail in the following description. Show it:

1 is a schematic view of an ultrasonic drilling machine, FIG. 2 is a perspective side view of the ultrasonic drilling tool with the sonotrode of the ultrasonic drilling machine of Fig. 1, and

3 shows a longitudinal section of the ultrasonic drilling tool with the sonotrode of FIG. 2.

Description of the embodiments

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. In the handle 185 of the tool housing 180 of the ultrasonic drill 100 is illustratively an actuatable by a user's finger of the electric hand switch 170 for electrically switching on and off an electronic control device 200th

In the tool housing 180, an electric or a pneumatic drive motor 130 is further housed, which is designed for the rotational drive of an optional gear 140. By the gear 140, a piezoelectric vibration actuator 105 - as indicated by a double arrow 250 - preferably rotationally driven.

The piezoelectric oscillation actuator 105 which rotates when the drive motor 130 is activated or switched on serves preferably to generate a comparatively intensive, longitudinal, d. H. axial ultrasonic vibration 120, preferably substantially along a longitudinal central axis 150 of the

Ultrasonic drilling device 300 acts and the rotational movement of the

Vibration actuator 105 is superimposed. In this case, the ultrasound vibration 120 emitted by the vibration actuator 105 preferably has an oscillation frequency in the order of 20 kHz up to 200 kHz.

For the sake of better graphical clarity, not shown oscillating elements te of the Schwingungsaktors 105 are preferably at least partially formed with a suitable piezoelectric material and may for example be designed annular. The vibration actuator 105 is therefore also referred to below with the term "piezoelectric actuator". Such a piezoelectric actuator with exemplary ring-shaped, piezoelectrically operating vibrating elements is described in detail in WO 2010/076230 A1, whose disclosure is hereby explicitly incorporated into the present application, so that a more detailed explanation of the structural design of the piezoelectric actuator 105 and its function is omitted here can be.

An ultrasonic drilling apparatus 300 assigned to the ultrasonic drilling machine 100 preferably comprises a preferably massive sonotrode 310 and an ultrasonic boring tool 320 for machining a metallic and / or mineral workpiece 160, illustratively by the introduction of a borehole 162. The sonotrode 310 is preferably mechanically suitable in the first instance coupled to the piezoelectric actuator 105, but may also be designed in one piece with this. In addition, a mechanical interface 350 is provided, by means of which the ultrasonic boring tool 320 can be connected to the sonotrode 310 in a vibration-resistant manner and, if required, preferably at least comparatively easily detachably on the user side. The mechanical interface 350 is preferably designed to ensure transmission of the ultrasonic vibration 120 from the sonotrode 310 to the ultrasonic boring tool 320 with as little or no loss as possible, including the rotational movement of the piezoactuator 105 indicated by the double arrow 250.

For example only, the ultrasonic drilling machine 100 for network-dependent power supply can be electrically connected by means of a power supply line 190 with an AC power supply network. It should be noted at this point, however, that the present invention is not limited to mains-powered ultrasonic drilling machines, but rather can be used in a variety of hand-held power tools, in which a piezoelectric actuator for oscillating drive of an associated ultrasonic drilling tool is used, regardless of whether Power tool is network-dependent and / or network-independent operated by means of a battery pack. According to a preferred embodiment not shown in the drawings, the ultrasonic drilling machine 100 is operable by means of a battery pack. In an exemplary operation of the ultrasonic drilling machine 100, the electronic control device 200 is supplied with alternating current via the mains supply line 190 by depressing the electrical manual switch 170 on the part of the user and thereby activated or switched on. As a result, the control device 200 generates an electrical excitation signal 210 suitable, for example, for a pulsed or permanent actuation of the piezoactuator 105, so that the ultrasound oscillation 120 is generated. In this case, a frequency of the ultrasound oscillation 120 may preferably be infinitely variable by means of the electronic control device 200 and, for example, depending on the workpiece 160 to be machined, the frequency of the ultrasound oscillation 120 preferably being kept substantially constant during a machining operation. Preferably, at the same time as the activation of the piezoelectric actuator 105, the drive motor 130 for the rotational drive of the ultrasonic drilling device 300 is switched on by the electronic control device 200 by means of an electronic control signal 220. The drive motor 130 and the piezoelectric actuator 105 are preferably switched on and off independently of each other with the aid of the electronic excitation signal 210 and the control signal 220.

FIG. 2 shows the ultrasonic drilling device 300 of FIG. 1 with the sonotrode 310 and the ultrasonic boring tool 320. The ultrasonic boring tool 320 preferably has a cylindrical shaft section 322 with a helix 324 formed at least in sections thereon and a free head section

326 with a cutting element 328 on. The helix 324 ensures a reliable removal of material removal from the borehole 162 of FIG. 1 for friction and wear minimization of the ultrasonic boring tool 320. The ultrasonic boring tool 320 is preferably formed with a high-strength steel alloy, such as a high-speed steel having the alloy composition 1 .3343 S 6-5-2, to ensure the longest possible service life. The at least one cutting element 328, or a corresponding fragmentation element, is preferably formed with a hard metal plate to further improve the service life of the ultrasonic drilling tool 320 when machining, in particular, mineral workpieces. It should be noted that instead of the cutting element 328, a fragmentation element may also be provided. This is useful, for example in the case of ultrasonic drilling tools for drilling holes in rock to smash a particular substrate.

At an end 330 of the cylindrical shaft section 322 of the ultrasonic drilling tool 320 directed away from the free head section 326, preferably four in each case planar contact surfaces are formed, of which only two contact surfaces 332, 334 are visible. The four circumferentially mutually perpendicular connecting surfaces form here for example an engagement geometry 336 with an approximately square cross-sectional geometry, which is intended to rotate the ultrasonic drilling tool 320 about the longitudinal central axis 150 by means of a turning tool not shown in the drawings. Deviating from this, a large number of alternative engagement geometries, such as, for example, an external hexagon, a multiple toothing or the like, are possible.

The preferably integrally formed sonotrode 310 preferably has an end mass 312, which is merely cylindrically configured as an example here, with a likewise approximately cylindrical sonotrode rod 314. The sonotrode rod 314 is preferably formed concentrically with the longitudinal center axis 150 of the end mass 312 and axially from This directed away. A diameter DE of the end mass 312 here is preferably larger-preferably significantly larger-than a diameter Ds of the sonotrode rod 314.

By means of the mechanical interface 350 is preferably the vibration-resistant and the user side in case of need simply again to be solved mechanical see connection between the sonotrode 310 and the ultrasonic drill

As a result, the ultrasonic boring tool 320 may, for example, be replaced in the event of wear or the need to use another type of tool, for example in the form of an ultrasonic boring tool having a different diameter, spiral geometry and / or divergent free head portion become. FIG. 3 shows the ultrasonic drilling device 300 of FIG. 2 with the sonotrode 310 and the ultrasonic drilling tool 320 of FIG. 2. The end mass 312 of the sonotrode 310 preferably continues in the axial direction into the cylindrical sonotrode rod 314. By means of the mechanical interface 350, the ultrasonic boring tool 320 with the sonotrode 310 is preferably connected with low damping and vibration resistance.

The ultrasonic drilling device 300 is preferably formed substantially rotationally symmetrical to the longitudinal central axis 150, which illustratively coincides with the x-axis of a coordinate system 400. On a U (x) axis of the coordinate system 400 oriented perpendicular to the x-axis, the profile of an axial deflection amplitude of the ultrasonic oscillation 120 symbolized by the double arrow 120 of FIG. 1 along the x-axis, i. over the longitudinal extent of the ultrasonic drilling device 300 away, removed.

The mechanical interface 350 of 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 boring tool 320. The receiving portion 354 is formed here merely by way of example with an internal thread 358, whereas the fastening portion 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.

In order to simplify the screwing and unscrewing of the ultrasonic drilling tool 320 into the sonotrode rod 314, the engagement geometry 336 for a rotary tool, not shown in the drawings, is provided on the ultrasonic boring tool 320. In order to provide a defined limit to the completion of this screwing process, a radially outwardly directed, annular flange 364 is provided between the attachment portion 356 and the engagement geometry 336 for the rotary tool, serving as an axial stop for a free end face 366 of the sonotrode rod 314 when screwing in the ultrasonic drilling tool 320 acts. At the same time arises due to the setting of the stop adjusting, axial tension between the components screwed together a reliable securing effect of mechanical interface 350, so that the ultrasonic drilling tool 320 can not easily solve again from the sonotrode rod 314 and unscrew. Alternatively, a fuse element, for example in the

Form of a polymeric screw lock, such as Loctite ^® or the like, be provided between the internal thread 358 and the external thread 360.

In order to further improve a radial centering of the ultrasonic boring tool 320 in the sonotrode rod 314 and, concomitantly, the concentricity of the ultrasonic boring tool 320, it is possible to move between the ultrasonic boring tool

320 and the sonotrode 314 a radial centering 370 - as the dotted lines diagonally only indicated - be provided.

This radial centering 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.

An axial length LS of the sonotrode rod 314 and an axial length LB of the ultrasonic drilling tool 320 are preferably dimensioned such that the free length of the individual components 310 and 320 is set at the same frequency. The first longitudinal eigenvibration shape of the free individual components is characterized in each case by a single vibration node (U (x) = 0) and the predominantly axial deflections. This results in a course of the axial deflection U (x), which has a local extreme point at 350. This is accompanied by a mechanical load which is proportional to the mechanical strain dU / dx and therefore minimal or zero. Illustratively, the axial length Ls of the sonotrode rod 314 is approximately 1/4 of a wavelength λ of the axial deflection amplitude U (x), and the axial length LB of the ultrasonic boring tool 320 corresponds to approximately 1/2 of a wavelength λ of the axial deflection amplitude U (x). 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, for example, in case of wear or in the case of labor-related exchanges user side easily and quickly replaced by another Ultraschallbohrwerk- tool. In addition, the manufacturing process of the sonotrode 310, which is known in previously known embodiments, is simplified. particular, due to the large diameter difference between the end mass 312 and the sonotrode rod 314, is generally more costly, relative to a one-piece design of sonotrode 310 and ultrasonic boring tool 320.

Claims

claims

1 . An ultrasonic drilling apparatus (300) having a sonotrode (310) and an ultrasonic boring tool (320), characterized in that a mechanical interface (350) is provided at which the

Ultrasonic Drilling Tool (320) vibration resistant and detachable with the

Sonotrode (310) is connectable, wherein the mechanical interface (350) is adapted to a low-loss transmission of

Ultrasonic vibration (120) from the sonotrode (310) to the

To allow ultrasonic drilling tool (320).

2. ultrasonic drilling apparatus according to claim 1, characterized in that the ultrasonic drilling tool (320) has a substantially cylindrical shaft portion (322) with an at least partially thereto

formed helix (324) and a free head portion (326) having a cutting element (328) and / or a fragmentation element.

3. ultrasonic drilling device according to claim 1 or 2, characterized

characterized in that the sonotrode (310) has a substantially cylindrical end mass (312) with an integrally formed sonotrode rod (314) concentric with and axially directed away from a longitudinal central axis (150) of the end mass (312)

Diameter (DE) of the end mass (312) is greater than a diameter (Ds) of the sonotrode rod (314).

4. Ultrasonic drilling apparatus according to one of the preceding claims, characterized in that a length (Ls) of the sonotrode rod (314) and a length (LB) of the ultrasonic boring tool (320) are dimensioned such that the mechanical interface (350) axially in the region of a minimum the ultrasonic load (dU (x) / dx) is.

Ultrasonic boring device according to one of the preceding claims, characterized in that the mechanical interface (350) for the axial connection of sonotrode (310) and ultrasonic drilling tool (320) along the longitudinal central axis (150) with a receiving portion (354) of the sonotrode rod (314) and with a mounting portion (356) of the ultrasonic drilling tool ( 320) is formed.

6. ultrasonic drilling apparatus according to claim 5, characterized in that the receiving portion (354) has an internal thread (358) and the

Attachment portion (356) has a corresponding to the internal thread (358) formed external thread (360).

7. Ultrasonic drilling apparatus according to claim 6, characterized in that the attachment portion (356) has a radially outwardly directed flange (364) as a stop for a free end face (366) of the sonotrodesstabs (314).

Ultrasonic drilling apparatus according to one of the preceding claims, characterized in that the ultrasonic drilling tool (320) has at least one attachment surface (332, 334).

Ultrasonic drilling device according to one of the preceding claims, characterized in that the ultrasonic drilling tool (320) is formed with a steel alloy.

Ultrasonic drilling device according to one of the preceding claims, characterized in that a radial centering (370) between the ultrasonic drilling tool (320) and the sonotrode rod (314) is provided.