EP0043000B1 - Drilling tool with expansible cutters - Google Patents

Drilling tool with expansible cutters Download PDF

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Publication number
EP0043000B1
EP0043000B1 EP81104350A EP81104350A EP0043000B1 EP 0043000 B1 EP0043000 B1 EP 0043000B1 EP 81104350 A EP81104350 A EP 81104350A EP 81104350 A EP81104350 A EP 81104350A EP 0043000 B1 EP0043000 B1 EP 0043000B1
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EP
European Patent Office
Prior art keywords
shaft
tool
bore
cutting tool
cutter feed
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP81104350A
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German (de)
French (fr)
Other versions
EP0043000A1 (en
Inventor
Heinrich Liebig
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Individual
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Individual
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Publication date
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Priority to AT81104350T priority Critical patent/ATE7325T1/en
Publication of EP0043000A1 publication Critical patent/EP0043000A1/en
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Publication of EP0043000B1 publication Critical patent/EP0043000B1/en
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Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B10/00—Drill bits
    • E21B10/26—Drill bits with leading portion, i.e. drill bits with a pilot cutter; Drill bits for enlarging the borehole, e.g. reamers
    • E21B10/32—Drill bits with leading portion, i.e. drill bits with a pilot cutter; Drill bits for enlarging the borehole, e.g. reamers with expansible cutting tools
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T408/00—Cutting by use of rotating axially moving tool
    • Y10T408/83—Tool-support with means to move Tool relative to tool-support
    • Y10T408/85—Tool-support with means to move Tool relative to tool-support to move radially
    • Y10T408/858—Moving means including wedge, screw or cam
    • Y10T408/8588—Axially slidable moving-means
    • Y10T408/85884—Tool pivotally mounted on support
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T82/00—Turning
    • Y10T82/12—Radially moving rotating tool inside bore
    • Y10T82/125—Tool simultaneously moving axially
    • Y10T82/128—Pivoted to tool-carrier

Definitions

  • the invention relates to a drilling tool for producing undercuts in pilot holes in masonry, concrete, stone and.
  • a rotatably drivable tool shaft that can be inserted into the pilot hole to be provided with the undercut, in the end region of which at least one cutting tool is arranged such that its cutting edge can gradually be displaced radially outward into the wall of the pilot hole after the shaft has been inserted into the pilot hole, wherein the cutting tool is arranged on a pivotable in a longitudinal slot-like recess in the bore-inner end portion of the tool shank, designed as a two-armed lever cutting tool carrier, which through the bore-inner end of a longitudinally displaceable but rotationally penetrating through the tool shaft, with its outer end from the outer end End of the tool shank led out feed shaft from a position pivoted back into the slot-like recess by inserting the feed shaft into the tool shaft into a position in which the cutting tool from the tool shank.
  • the machined drilling dust from the wall of the hole is placed in the recess in the cutting tool holder, it can happen in isolated cases that the swiveling of the cutting tool holder into the recess, which is necessary after the drilling process, is hindered, and the force of the spring is not sufficient to retract the cutting tool completely into the recess, so that additional manipulations are required to remove the undercut tool from the bore.
  • the cutting tool is swiveled back into the tool shaft after completion of the undercut after the cam has been withdrawn either only by pressure exerted on the cutting tools by the wall of the hole when the entire drilling tool is withdrawn from the bore (DE-B-1207907) or a link-like connection which additionally supports this pressure between the infeed shank and the cutting tool holder, in which a pin from the infeed shaft engages in a cam slot in the cutting tool holder (CH-A-495492).
  • the invention has for its object to increase the drilling performance of the drilling tool compared to the known drilling tool in that a comparatively higher radial feed force can be exerted on the cutting tool, both when pivoting the cutting tool during the undercut drilling process and when retracting of the cutting tool after the drilling process against any inhibitions caused by drilling dust which may have penetrated into the interior of the tool.
  • the cutting tool carrier has on its rear side opposite the cutting tool on its bore-inside lever arm a pressure surface which is inclined to the direction of displacement of the feed shaft which engages a delivery cam formed on the inside of the bore of the feed shank, which pivots the bore-inside lever arm of the cutting tool carrier when the feed shaft shifts relative to the tool shaft into the bore with an increasingly larger lever arm out of the recess of the tool shaft, and that the back of the bore-mouth lever arm of the cutting tool carrier is one Lever arm inside the bore has oppositely inclined pressure surface on which the feed cam engages out of the bore inside when the feed shank is displaced relative to the tool shank.
  • the feed shaft in the area led out of the tool shaft on the one hand and on the tool shaft Delivery shaft supports supported coil springs that are under pressure.
  • the helical spring is expediently supported on the bore-mouth end face of the tool shank on the one hand and the end face of a collar component provided on the feed shank on the other hand, whereby it may be expedient to design the collar component in selectable axial positions on the area of the feed shank protruding from the tool shank, since in this way the Bias of the coil spring is changeable.
  • the helical spring is expediently arranged within a sleeve attached to the end of the tool shank, in which the front end of the collar component facing the bore engages in a longitudinally displaceable manner.
  • the coil spring is therefore completely encapsulated within the sleeve.
  • the rotationally fixed and longitudinally displaceable coupling of the feed shank to the tool shank is brought about by a pin provided in a transverse bore in the tool shank and penetrating an elongated hole in the feed shank.
  • this coupling can also take place in that a section provided with a multi-wedge profile is provided on the feed shaft, which is arranged in a sleeve section of the tool shaft provided with a complementary multi-wedge profile in a rotationally fixed but longitudinally displaceable manner.
  • the feed shank in its area led out of the tool shank is designed as a multi-wedge shank section, which at its front end facing the tool shank is still partly in a sleeve-shaped section of the tool shank with an inner multi-wedge profile complementary to the multi-wedge profile of the multi-wedge shank section engages, the sleeve section provided with the multi-wedge profile being dimensioned such that the multi-wedge shaft section can be displaced into the sleeve section by the amount required for pivoting the cutting tool carrier.
  • a resilient return of the feed shank relative to the tool shank can be provided to simplify the handling of the tool, in that a compression spring supported on the front end face of the multi-spline shank section on the one hand and on the bottom of the sleeve section on the tool shank on the other hand is provided in the sleeve section is arranged.
  • a functional improvement of the tools designed in the manner according to the invention is achieved in that the slot-like recess for receiving the cutting tool carrier extends into the section of the tool shank lying in front of the cutting tool carrier in the insertion direction and to a receiving pocket for the material worked out by the cutting tool from the wall of the pilot hole (drilling dust ) is designed. Obstacles to the pivoting-out process of the cutting tool carrier due to drilling dust collecting in the recess are thus avoided.
  • the feed shank can be drilled in the middle over its entire length for this purpose, so that it On the cutting tool side, the bore opens into the recess in the tool shank that receives the cutting tool carrier.
  • a device for extracting the drilling dust from the machine-side mouth of the bore must then be provided in the drive machine receiving the drilling tool.
  • the drilling tool according to the invention shown in the drawing designated in its entirety by 10, for drilling an undercut in a cylindrical pilot hole previously produced in a customary manner in an underground of stone, concrete, masonry or the like has a tool shank 12, in which in the A front-end region to be introduced into the pre-bore is provided with a longitudinal slot-like recess 14 that is open on one side.
  • a cutting tool carrier 18 is mounted on a bolt 16 in the form of a flat, elongated, two-armed lever fitted in the width of the recess 14, on the lever arm 18a on the inside of the bore, which is located in the drawing below, on the front side facing the open side of the recess
  • the actual cutting tool 20 is arranged, which is formed, for example, by a hard metal plate which is hard-soldered into a suitable receptacle of the cutting tool carrier 18 and on which the cutting edges which are designed in accordance with the shape of the undercut to be produced are ground.
  • the tool shank 12 has a longitudinal center bore 22 extending from its outer bore end to the recess 14, in which a feed shank 24 is inserted so as to be longitudinally displaceable but non-rotatable, which still emerges from the tool shank 12 to a considerable extent.
  • the rotation is secured by a pin 30 penetrating a transverse bore 26 in the tool shank 12 and an elongated hole 28 in the additional shank 24.
  • the longitudinal center bore and the feed shank could also - at least in a partial area - be complementarily polygonal in cross section, e.g. B. be square or hexagonal, or the rotation of the shafts 12, 24 relative to each other can alternatively be prevented by a tongue and groove connection.
  • the free end of the end of the feed shaft 24 protruding from the tool shaft 12 is designed as a hexagon at 32.
  • the back of the lever arm 18a of the cutting tool carrier 18, which is opposite the cutting tool 20, is designed as a pressure surface 34 which extends obliquely to the direction of displacement of the infeed shaft 24, namely its inclination is selected such that it relates to the right in relation to the position of the drilling tool shown in the drawing opening recess 14 runs from top right to bottom left.
  • a feed cam 36 attached to the lower end of the feed shaft 24 and guided past the rear of the second lever arm 18b on the bore mouth side can be brought into contact with the pressure surface 34 by pushing the feed shaft into the tool shaft with its somewhat rounded front end.
  • the delivery cam 36 supported with its rear side on the closed side of the recess urges the pressure surface 34, i. H.
  • the rear of the lever arm 18b on the bore mouth side of the cutting tool carrier 18 is also designed as a pressure surface 38, which is inclined in the opposite direction to the pressure surface 34.
  • the complementarily inclined surface 40 of the feed cam 36 runs against the pressure surface 40 and inevitably pivots the cutting tool carrier 18 when the feed shank 24 is retracted in such a way that the cutting tool 20 is returned to the recess 14.
  • the drilling tool 10 is already functional to the extent described so far, but its handling is improved in practice in that a helical spring 42 surrounding it is arranged in the area of the delivery shaft 24 which is led out of the tool shaft 12, the lower end of which is on the bore mouth side End face of the tool shank 12 is supported, while its other end rests under pressure on the end face facing the bore of a collar component 44 pushed onto the feed shank 24 and fastened thereon.
  • a collar component can be fastened in selectable axial positions on the feed shaft 24 in a radial threaded bore 46 screwed into the collar component 44.
  • the bias of the coil spring 24 can therefore be changed to a certain extent.
  • the coil spring 42 is surrounded by a sleeve 50 which is attached to the end of the tool shank 12 and in the other end of which the collar component 44 fits d. H. engages longitudinally.
  • An enlarged receiving pocket 52 which continues the recess 14 in the insertion direction and continues the recess 14, serves to receive the drilling dust worked out by the cutting tool 20 from the wall of a pilot hole. Jamming of the cutting tool carrier 18 in the pivoted-out position by accumulated in the recess 14 behind the pivoted-out cutting tool carrier This avoids drilling dust. Even if drilling dust should have accumulated in this area, it is displaced into the receiving pocket 52 when the delivery shaft is pulled back.
  • the drilling tool 110 shown in FIGS. 2 and 3 differs from the drilling tool 10 described above essentially only in the manner of the rotationally fixed but longitudinally displaceable coupling of the feed and tool shafts, so that it is sufficient to describe only this coupling below, while referring to the general description of the drilling tool 110, the foregoing description.
  • the parts of the drilling tool 110 which correspond to the parts of the drilling tool 10 are identified by the same reference numerals, but with the preceding 1.
  • the feed shaft 124 of the drilling tool 110 carries a pressed-on or otherwise rigidly fastened multi-wedge body 160 which engages in a sleeve section 162 provided with a complementary multi-wedge profile at the rear end of the tool shaft 112, the length of the sleeve section 162 in relation to the multi-wedge body 160 is dimensioned such that the multi-wedge body 160 can be pushed into the sleeve section 162 against the action of the spring 142 by the feed path required for the pivoting of the cutting tool carrier 118.
  • the feed shank 124 is provided with a continuous longitudinal center bore 164, which makes it possible for the drilling dust which collects when working with the tool 110 in the recess 114 receiving the cutting tool carrier 118 to be continuously sucked off if the drive machine for the tool has a corresponding suction device is provided.
  • the rotationally fixed and longitudinally displaceable connection of the feed shank 224 to the tool shank 212 takes place by means of a multi-spline connection.
  • the area of the feed shank 224 which is led out of the tool shank 212 is designed overall as a multi-wedge shank section 260 which, at its front end facing the tool shank 212, engages somewhat in a sleeve-shaped section 262 at the rear end of the tool shank.
  • this sleeve-shaped section 262 is provided with a multi-wedge profile that is complementary to the multi-spline profile of the shaft section 260, as a result of which a positive connection between the shaft section 260 and the sleeve section 262 is provided in the direction of rotation of the tool.
  • the sleeve section 262 is in turn dimensioned such that the multi-wedge shaft section 260 can be pushed into the sleeve section 262 by the required feed path.
  • the compression spring 242 which supports the restoration, is supported between the front end face 261 of the multi-spline shank section 260 on the one hand and on the bottom 263 of the sleeve section 262 on the tool shank 212 on the other hand.
  • the feed shaft 224 can be provided with a longitudinal center bore 264 (FIG. 5) for suctioning off the drilling dust during the drilling process.

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  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Processing Of Stones Or Stones Resemblance Materials (AREA)
  • Earth Drilling (AREA)
  • Drilling And Boring (AREA)

Abstract

A bore undercutting tool which is composed of a barrel and a cutter feed driver which is inserted for longitudinal displacement but also for co-rotation into the barrel and projects from the rearward end thereof. In a slot provided in the forward end portion of the barrel there is fulcrumed a cutter in the form of a two-armed lever which can be rocked by a cutter feed cam provided on the forward end of the cutter feed driver, in proportion to the longitudinal displacement of the latter relative to the barrel, such that a cutting tool disposed on the one lever arm can either be retracted into the slot or rocked out of same. A spring biases the barrel and the cutter feed driver toward a position in which the cutting tool is withdrawn into the slot.

Description

Die Erfindung betrifft ein Bohrwerkzeug zur Erzeugung von Hinterschnitten in Vorbohrungen in Mauerwerk, Beton, Gestein u. dgl. mit einem in die mit dem Hinterschnitt zu versehende Vorbohrung einführbaren, drehantreibbaren Werkzeugschaft, in dessen Endbereich wenigstens ein Schneidwerkzeug so angeordnet ist, daß seine Schneidkante nach dem Einführen des Schafts in die Vorbohrung allmählich radial nach außen in die Wandung der Vorbohrung verschiebbar ist, wobei das Schneidwerkzeug an einem verschwenkbar in einer längsverlaufenden schlitzartigen Ausnehmung im bohrungsinneren Endabschnitt des Werkzeugschafts gelagerten, als zweiarmiger Hebel ausgebildeten Schneidwerkzeugträger angeordnet ist, der durch das bohrungsinnere Ende eines den Werkzeugschaft um ein vorgegebenes Maß längsverschieblich aber drehfest durchsetzenden, mit seinem äußeren Ende aus dem äußeren Ende des Werkzeugschafts herausgeführten Zustellschafts aus einer in die schlitzartige Ausnehmung zurückgeschwenkten Stellung durch Einschieben des Zustellschafts in den Werkzeugschaft hinein in eine Stellung verschwenkbar ist, in welcher das Schneidwerkzeug vom Werkzeugschaft vortritt.The invention relates to a drilling tool for producing undercuts in pilot holes in masonry, concrete, stone and. Like. With a rotatably drivable tool shaft that can be inserted into the pilot hole to be provided with the undercut, in the end region of which at least one cutting tool is arranged such that its cutting edge can gradually be displaced radially outward into the wall of the pilot hole after the shaft has been inserted into the pilot hole, wherein the cutting tool is arranged on a pivotable in a longitudinal slot-like recess in the bore-inner end portion of the tool shank, designed as a two-armed lever cutting tool carrier, which through the bore-inner end of a longitudinally displaceable but rotationally penetrating through the tool shaft, with its outer end from the outer end End of the tool shank led out feed shaft from a position pivoted back into the slot-like recess by inserting the feed shaft into the tool shaft into a position in which the cutting tool from the tool shank.

Bei diesem bekannten Hinterschnitt-Bohrwerkzeug (DE-A-27 31 901 ; Fig. 2) greift eine den Schneidwerkzeugträger in die zurückgeschwenkte Stellung vorspannende Feder direkt am rückwärtigen, d. h. zur Bohrungsmündung weisenden Hebelarm des Schneidwerkzeugträgers an, wobei sie unter Druckvorspannung zwischen der Rückseite dieses Hebelarms und der gegenüberliegenden Wandung der den Schneidwerkzeugträger aufnehmenden Ausnehmung angeordnet ist. Da die Größe des für die Feder zur Verfügung stehenden Zwischenraums aber sehr beschränkt ist, ist auch die von der Feder ausgeübte Vorspannkraft begrenzt. Nachdem sich beim Arbeiten mit dem bekannten Werkzeug das aus der Bohrungswandung herausgearbeitete Bohrmehl in die Ausnehmung im Schneidwerkzeugträger setzt, kann es in vereinzelten Fällen dazu kommen, daß die nach dem Bohrvorgang erforderliche Verschwenkung des Schneidwerkzeugträgers in die Ausnehmung zurück behindert ist, und die Kraft der Feder nicht ausreicht, um das Schneidwerkzeug ganz in die Ausnehmung zurückzuziehen, so daß zusätzliche Manipulationen erforderlich sind, um das Hinterschnittwerkzeug aus der Bohrung zu entfernen. Außerdem hat sich gezeigt, daß die Bohrzeit für die Hinterschnittfläche bei Betonqualitäten hoher Festigkeit relativ groß werden, was darauf zurückzuführen ist, daß die mit dem Zustellschaft ausgeübte Vorschubkraft, die beim bekannten Werkzeug über eine Schrägfläche am Ende des Zustellschafts auf den bohrungsmündungsseitigen Hebelarm einwirkt, an einen Hebelarm angreift, der mit zunehmendem Vorschub des Schneidwerkzeugs kleiner wird, d. h. der in die Vorschubkraft des Schneidwerkzeugs umgesetzte Anteil der auf den Zustellschaft ausgeübten Vorschubkraft wird mit zunehmender Tiefe des Hinterschnitts geringer.In this known undercut drilling tool (DE-A-27 31 901; Fig. 2), a spring biasing the cutting tool carrier into the pivoted-back position engages directly on the rear, i. H. lever arm of the cutting tool carrier pointing towards the bore opening, wherein it is arranged under pressure prestress between the back of this lever arm and the opposite wall of the recess receiving the cutting tool carrier. However, since the size of the space available for the spring is very limited, the preload force exerted by the spring is also limited. After working with the known tool, the machined drilling dust from the wall of the hole is placed in the recess in the cutting tool holder, it can happen in isolated cases that the swiveling of the cutting tool holder into the recess, which is necessary after the drilling process, is hindered, and the force of the spring is not sufficient to retract the cutting tool completely into the recess, so that additional manipulations are required to remove the undercut tool from the bore. In addition, it has been found that the drilling time for the undercut surface for concrete qualities of high strength is relatively long, which is due to the fact that the feed force exerted with the feed shank, which acts on the bore-mouth lever arm in the known tool via an inclined surface at the end of the feed shank engages a lever arm that becomes smaller as the cutting tool advances, d. H. the proportion of the feed force exerted on the feed shaft converted into the feed force of the cutting tool becomes smaller with increasing depth of the undercut.

Bei Bohrwerkzeugen größerer Abmessungen, die zum Herstellen von Erdbohrungen gedacht sind, ist es bekannt (DE-B-1207907; CH-A-495492), die an einem verschwenkbar im Werkzeugschaft gelagerten Schneidwerkzeugträger angeordneten Schneidwerkzeuge dadurch aus der in den Werkzeugschaft zurückgezogenen Lage radial nach außen in Schneideingriff mit der Bohrungswandung zu verschieben, daß ein an einem Zustellschaft angeordneter Nocken an einer geneigt verlaufenden Drückfläche auf der Innenseite des Schneidwerkzeugträgers angreift und bei Längsverschiebung des Zustellschafts relativ zum Werkzeugschaft den Schneidwerkzeugträger zwangsläufig nach außen verschwenkt. Das Zurückschwenken des Schneidwerkzeugs in den Werkzeugschaft nach Fertigstellung des Hinterschnitts erfolgt nach Zurückziehen des Nockens entweder nur durch von der Bohrungswandung beim Zurückziehen des gesamten Bohrwerkzeugs aus der Bohrung auf die Schneidwerkzeuge ausgeübten Druck (DE-B-1207907) oder eine diesen Druck zusätzlich unterstützende kulissenartige Verbindung zwischen dem Zustellschaft und dem Schneidwerkzeugträger, bei welcher ein Zapfen vom Zustellschaft in einen Kurvenschlitz im Schneidwerkzeugträger eingreift (CH-A-495492). Problematisch wird diese Art der Zurückstellung eines Schneidwerkzeugs aber dann, wenn das Schneidwerkzeug zur Erzeugung eines Hinterschnitts mit einer rechtwinklig zur Bohrungslängsachse verlaufenden Hinterschnittfläche eine rechtwinklig aus dem Bohrungsschaft vortretenden Schneidkante aufweist, und das beim Hinterschneiden von harten Untergründen entstehende Bohrmehl den Zurückschwenkvorgang zusätzlich behindert.In the case of drilling tools of larger dimensions, which are intended for the production of earth bores, it is known (DE-B-1207907; CH-A-495492) that the cutting tools arranged on a cutting tool carrier pivotally mounted in the tool shaft are radially retracted from the position withdrawn into the tool shaft to move outside into cutting engagement with the bore wall, that a cam arranged on an infeed shaft engages on an inclined pressing surface on the inside of the cutting tool carrier and inevitably pivots the cutting tool carrier outwards when the infeed shaft is displaced longitudinally relative to the tool shaft. The cutting tool is swiveled back into the tool shaft after completion of the undercut after the cam has been withdrawn either only by pressure exerted on the cutting tools by the wall of the hole when the entire drilling tool is withdrawn from the bore (DE-B-1207907) or a link-like connection which additionally supports this pressure between the infeed shank and the cutting tool holder, in which a pin from the infeed shaft engages in a cam slot in the cutting tool holder (CH-A-495492). This type of provision of a cutting tool becomes problematic, however, if the cutting tool for producing an undercut with an undercut surface running at right angles to the longitudinal axis of the bore has a cutting edge protruding at right angles from the bore shaft, and the drilling dust which arises when undercut hard surfaces additionally hinders the pivoting-back process.

Demgegenüber liegt der Erfindung die Aufgabe zugrunde, die Bohrleistung des Bohrwerkzeugs im Vergleich zu dem bekannten Bohrwerkzeug dadurch zu erhöhen, daß eine vergleichsweise höhere radiale Vorschubkraft auf das Schneidwerkzeug ausgeübt werden kann, und zwar sowohl beim Ausschwenken des Schneidwerkzeugs beim Hinterschnitt-Bohrvorgang als auch beim Zurückziehen des Schneidwerkzeugs nach dem Bohrvorgang entgegen etwaigen Hemmungen durch gegebenenfalls ins Innere des Werkzeugs eingedrungenes Bohrmehl.In contrast, the invention has for its object to increase the drilling performance of the drilling tool compared to the known drilling tool in that a comparatively higher radial feed force can be exerted on the cutting tool, both when pivoting the cutting tool during the undercut drilling process and when retracting of the cutting tool after the drilling process against any inhibitions caused by drilling dust which may have penetrated into the interior of the tool.

Ausgehend von einem Bohrwerkzeug der eingangs erwähnten Art wird diese Aufgabe erfindungsgemäß dadurch gelöst, daß der Schneidwerkzeugträger auf seiner dem Schneidwerkzeug gegenüberliegenden Rückseite an seinem bohrungsinneren Hebelarm eine zur Verschiebungsrichtung des Zustellschafts schräg geneigt verlaufende Druckfläche aufweist, an welcher ein am bohrungsinneren Ende des Zustellschafts ausgebildeter Zustellnocken angreift, der den bohrungsinneren Hebelarm des Schneidwerkzeugträgers bei einer Verschiebung des Zustellschafts relativ zum Werkzeugschaft ins Bohrungsinnere mit zunehmend größer werdendem Hebelarm aus der Ausnehmung des Werkzeugschafts herausschwenkt, und daß die Rückseite des bohrungsmündungsseitigen Hebelarms des Schneidwerkzeugträgers eine zum bohrungsinneren Hebelarm gegensinnig schräg verlaufende Druckfläche aufweist, an welcher der Zustellnocken bei einer Verschiebung des Zustellschafts relativ zum Werkzeugschaft aus dem Bohrungsinnern heraus angreift. Sowohl beim Ausschwenken des Schneidwerkzeugs in die Arbeitsstellung als auch beim Zurückziehen des Schneidwerkzeugträgers in die Ausnehmung im Werkzeugschaft wird also in Abhängigkeit von der Neigung der Druckfläche relativ zur Verschiebungsrichtung des Zustellschafts eine jeweils hinreichend hohe Vorschub- bzw. Rückstellkraft für das Schneidwerkzeug erzeugt, um auch in den harten Untergründen, für welche das erfindungsgemäße Werkzeug vorgesehen ist, den erforderlichen Vorschub des Schneidwerkzeugs zu ermöglichen bzw. das Werkzeug nach dem Bohrvorgang mit Sicherheit in den Werkzeugschaft zurückzuziehen.Starting from a drilling tool of the type mentioned at the outset, this object is achieved in that the cutting tool carrier has on its rear side opposite the cutting tool on its bore-inside lever arm a pressure surface which is inclined to the direction of displacement of the feed shaft which engages a delivery cam formed on the inside of the bore of the feed shank, which pivots the bore-inside lever arm of the cutting tool carrier when the feed shaft shifts relative to the tool shaft into the bore with an increasingly larger lever arm out of the recess of the tool shaft, and that the back of the bore-mouth lever arm of the cutting tool carrier is one Lever arm inside the bore has oppositely inclined pressure surface on which the feed cam engages out of the bore inside when the feed shank is displaced relative to the tool shank. Both when the cutting tool is swung out into the working position and when the cutting tool carrier is pulled back into the recess in the tool shank, a sufficiently high feed or restoring force for the cutting tool is generated depending on the inclination of the pressure surface relative to the direction of displacement of the feed shank, in order also in the hard surfaces for which the tool according to the invention is intended to enable the necessary advance of the cutting tool or to withdraw the tool with certainty into the tool shank after the drilling process.

Infolge der zwangsläufigen Zurückschwenkung des Schneidwerkzeugs beim Zurückziehen des Zustellschafts nach dem Fertigbohren der Hinterschnittfläche ist die Anordnung einer den Werkzeugträger zurückschwenkenden Feder an sich nicht erforderlich. Da die Handhabung des Bohrwerkzeugs jedoch vereinfacht wird, wenn das Schneidwerkzeug nach Beendigung des Hinterschnitt-Bohrvorgangs selbsttätig in die Ausnehmung zurückgestellt wird, wird in erfindungsgemäßer Weiterbildung eine solche Feder vorgesehen, wobei der Zustellschaft in dem aus dem Werkzeugschaft herausgeführten Bereich die am Werkzeugschaft einerseits und am Zustellschaft andererseits abgestützte, unter Druckvorspannung stehende Schraubenfeder trägt. Gegenüber der bei dem bekannten Hinterschnitt-Bohrwerkzeug gemäß der Ausgangsdruckschrift vorgesehene, am Schneidwerkzeugträger einerseits und einer benachbarten Wandung im Werkzeugschaft abgestützten Feder steht bei dieser Ausgestaltung erheblich mehr Platz für die Anordnung der Feder in einem Bereich zur Verfügung, in welchem eine Beeinträchtigung der Federfunktion durch eindringendes Bohrmehl nicht zu befürchten ist.As a result of the inevitable pivoting back of the cutting tool when the feed shank is pulled back after the undercut surface has been drilled, the arrangement of a spring pivoting back the tool carrier is not necessary per se. However, since the handling of the drilling tool is simplified if the cutting tool is automatically put back into the recess after completion of the undercut drilling process, such a spring is provided in a further development according to the invention, the feed shaft in the area led out of the tool shaft on the one hand and on the tool shaft Delivery shaft, on the other hand, supports supported coil springs that are under pressure. Compared to the spring provided in the known undercut drilling tool according to the original publication, supported on the cutting tool carrier on the one hand and an adjacent wall in the tool shaft, there is considerably more space available for the arrangement of the spring in an area in this area in which the spring function is impaired by penetrating Drilling powder is not to be feared.

Die Schraubenfeder ist dabei zweckmäßig an der bohrungsmündungsseitigen Stirnfläche des Werkzeugschafts einerseits und der Stirnfläche eines auf dem Zustellschaft vorgesehenen Bundbauteils andererseits abgestützt, wobei es zweckmäßig sein kann, den Bundbauteil in wählbaren Axialstellungen auf dem aus dem Werkzeugschaft vortretenden Bereich des Zustellschafts befestigbar auszubilden, da so die Vorspannung der Schraubenfeder veränderbar ist.The helical spring is expediently supported on the bore-mouth end face of the tool shank on the one hand and the end face of a collar component provided on the feed shank on the other hand, whereby it may be expedient to design the collar component in selectable axial positions on the area of the feed shank protruding from the tool shank, since in this way the Bias of the coil spring is changeable.

Die Schraubenfeder wird dabei zweckmäßig innerhalb einer am Ende des Werkzeugschafts angesetzten Hülse angeordnet, in welche das zur Bohrung weisende Vorderende des Bundbauteils längsverschieblich eingreift. Die Schraubenfeder ist also vollständig gekapselt innerhalb der Hülse angeordnet.The helical spring is expediently arranged within a sleeve attached to the end of the tool shank, in which the front end of the collar component facing the bore engages in a longitudinally displaceable manner. The coil spring is therefore completely encapsulated within the sleeve.

Die drehfeste und längsverschiebliche Koppelung des Zustellschafts mit dem Werkzeugschaft wird im einfachsten Fall durch einen in einer Querbohrung des Werkzeugschafts vorgesehenen und ein Langloch im Zustellschaft durchsetzenden Stift bewirkt.In the simplest case, the rotationally fixed and longitudinally displaceable coupling of the feed shank to the tool shank is brought about by a pin provided in a transverse bore in the tool shank and penetrating an elongated hole in the feed shank.

Alternativ kann diese Koppelung auch dadurch erfolgen, daß am Zustellschaft ein mit einem Vielkeilprofil versehener Abschnitt vorgesehen wird, der in einem mit einem komplementären Vielkeilprofil versehenen Hülsenabschnitt des Werkzeugschafts drehfest aber längsverschieblich angeordnet ist.Alternatively, this coupling can also take place in that a section provided with a multi-wedge profile is provided on the feed shaft, which is arranged in a sleeve section of the tool shaft provided with a complementary multi-wedge profile in a rotationally fixed but longitudinally displaceable manner.

Bei einem weiteren Ausführungsbeispiel der Erfindung ist der Zustellschaft in seinem aus dem Werkzeugschaft herausgeführten Bereich als Vielkeil-Schaftabschnitt ausgebildet, der an seinem, dem Werkzeugschaft zugewandten Vorderende noch zum Teil in einem hülsenförmigen Abschnitt des Werkzeugschafts mit einem zum Vielkeilprofil des Vielkeil-Schaftabschnitts komplementären inneren Vielkeilprofil eingreift, wobei der mit dem Vielkeilprofil versehene Hülsen- Abschnitt-solang bemessen ist, daß der Vielkeil-Schaftabschnitt um das zum Verschwenken des Schneidwerkzeugträgers erforderliche Maß in den Hülsen-Abschnitt hinein verschiebbar ist.In a further exemplary embodiment of the invention, the feed shank in its area led out of the tool shank is designed as a multi-wedge shank section, which at its front end facing the tool shank is still partly in a sleeve-shaped section of the tool shank with an inner multi-wedge profile complementary to the multi-wedge profile of the multi-wedge shank section engages, the sleeve section provided with the multi-wedge profile being dimensioned such that the multi-wedge shaft section can be displaced into the sleeve section by the amount required for pivoting the cutting tool carrier.

Auch bei diesem Ausführungsbeispiel kann zur Vereinfachung der Handhabung des Werkzeugs eine federnde Rückstellung des Zustellschafts relativ zum Werkzeugschaft vorgesehen sein, indem in dem Hülsen-Abschnitt eine an der vorderen Stirnfläche des Vielkeil-Schaftabschnitts einerseits und am Boden des Hülsen-Abschnitts am Werkzeugschaft andererseits abgestützte Druckfeder angeordnet ist.In this embodiment too, a resilient return of the feed shank relative to the tool shank can be provided to simplify the handling of the tool, in that a compression spring supported on the front end face of the multi-spline shank section on the one hand and on the bottom of the sleeve section on the tool shank on the other hand is provided in the sleeve section is arranged.

Eine Funktionsverbesserung der in der erfindungsgemäßen Weise ausgebildeten Werkzeuge wird dadurch erreicht, daß die schlitzartige Ausnehmung zur Aufnahme des Schneidwerkzeugträgers in den in Einschubrichtung vor dem Schneidwerkzeugträger liegenden Abschnitt des Werkzeugschafts verlängert und zu einer Aufnahmetasche für das vom Schneidwerkzeug aus der Wandung der Vorbohrung herausgearbeitete Material (Bohrmehl) ausgestaltet ist. Behinderungen des Ausschwenkvorgangs des Schneidwerkzeugträgers durch sich in der Ausnehmung sammelndes Bohrmehl werden so vermieden.A functional improvement of the tools designed in the manner according to the invention is achieved in that the slot-like recess for receiving the cutting tool carrier extends into the section of the tool shank lying in front of the cutting tool carrier in the insertion direction and to a receiving pocket for the material worked out by the cutting tool from the wall of the pilot hole (drilling dust ) is designed. Obstacles to the pivoting-out process of the cutting tool carrier due to drilling dust collecting in the recess are thus avoided.

Dies kann auch dadurch erreicht werden, daß das beim Bohrvorgang entstehende Bohrmehl aus der Vorbohrung abgesaugt wird. Bei den Ausführungsbeispielen, bei denen die Verbindung von Werkzeug- und Zustellschaft durch eine Vielkeilverbindung erfolgt, kann zu diesem Zweck der Zustellschaft über seine gesamte Länge mittig durchbohrt sein, so daß diese Bohrung schneidwerkzeugseitig in der den Schneidwerkzeugträger aufnehmenden Ausnehmung des Werkzeugschafts mündet. In der das Bohrwerkzeug aufnehmenden Antriebsmaschine muß dann eine Einrichtung zur Absaugung des Bohrmehls aus der maschinenseitigen Mündung der Bohrung vorgesehen sein.This can also be achieved in that the drilling dust produced during the drilling process is sucked out of the pilot hole. In the exemplary embodiments in which the tool and feed shank are connected by a multi-spline connection, the feed shank can be drilled in the middle over its entire length for this purpose, so that it On the cutting tool side, the bore opens into the recess in the tool shank that receives the cutting tool carrier. A device for extracting the drilling dust from the machine-side mouth of the bore must then be provided in the drive machine receiving the drilling tool.

Die Erfindung ist in der folgenden Beschreibung mehrerer Ausführungsbeispiele in Verbindung mit der Zeichnung näher erläutert, und zwar zeigt :

  • Figur 1 einen Längsmittelschnitt durch ein erstes Ausführungsbeispiel eines in der erfindungsgemäßen Weise ausgebildeten Hinterschnitt-Bohrwerkzeugs ;
  • Figur 2 einen Längsmittelschnitt durch ein weiteres Ausführungsbeispiel eines erfindungsgemäßen Hinterschnitt-Bohrwerkzeugs ;
  • Figur 3 eine Schnittansicht entlang der Linie 3-3 in Fig. 2 ;
  • Figur 4 einen Längsmittelschnitt durch ein drittes Ausführungsbeispiel des erfindungsgemäßen Bohrwerkzeugs ; und
  • Figur 5 eine Schnittansicht, gesehen in Richtung der Pfeile 5-5 in Fig. 4.
The invention is explained in more detail in the following description of several exemplary embodiments in conjunction with the drawing, which shows:
  • 1 shows a longitudinal central section through a first embodiment of an undercut drilling tool designed in the manner according to the invention;
  • Figure 2 shows a longitudinal central section through a further embodiment of an undercut drilling tool according to the invention;
  • Figure 3 is a sectional view taken along line 3-3 in Fig. 2;
  • Figure 4 shows a longitudinal central section through a third embodiment of the drilling tool according to the invention; and
  • FIG. 5 is a sectional view, seen in the direction of arrows 5-5 in FIG. 4.

Das in der Zeichnung dargestellte, in seiner Gesamtheit mit 10 bezeichnete erfindungsgemäße Bohrwerkzeug zum Aufbohren eines Hinterschnitts in einer zuvor auf übliche Weise erzeugten zylindrischen Vorbohrung in einem Untergrund aus Stein, Beton, Mauerwerk od. dgl. weist einen Werkzeugschaft 12 auf, in dessen in die Vorbohrung einzuführendem vorderen Endbereich eine an einer Seite offene längsverlaufende schlitzartige Ausnehmung 14 vorgesehen ist. In dieser Ausnehmung ist auf einem Bolzen 16 ein Schneidwerkzeugträger 18 in Form eines flachen langgestreckten, in der Breite in die Ausnehmung 14 eingepaßten doppelarmigen Hebels gelagert, an dessen bohrungsinnerem, in der Zeichnung unten liegendem Hebelarm 18a auf der zur offenen Seite der Ausnehmung weisenden Vorderseite das eigentliche Schneidwerkzeug 20 angeordnet ist, das beispielsweise von einer in einer passenden Aufnahme des Schneidwerkzeugträgers 18 hart eingelöteten Hartmetallplatte gebildet wird, an welcher die der Form des zu erzeugenden Hinterschnitts entsprechend ausgebildeten Schneidkanten angeschliffen sind.The drilling tool according to the invention shown in the drawing, designated in its entirety by 10, for drilling an undercut in a cylindrical pilot hole previously produced in a customary manner in an underground of stone, concrete, masonry or the like has a tool shank 12, in which in the A front-end region to be introduced into the pre-bore is provided with a longitudinal slot-like recess 14 that is open on one side. In this recess, a cutting tool carrier 18 is mounted on a bolt 16 in the form of a flat, elongated, two-armed lever fitted in the width of the recess 14, on the lever arm 18a on the inside of the bore, which is located in the drawing below, on the front side facing the open side of the recess The actual cutting tool 20 is arranged, which is formed, for example, by a hard metal plate which is hard-soldered into a suitable receptacle of the cutting tool carrier 18 and on which the cutting edges which are designed in accordance with the shape of the undercut to be produced are ground.

Der Werkzeugschaft 12 weist eine von seinem bohrungsäußeren Ende zur Ausnehmung 14 durchlaufende Längsmittelbohrung 22 auf, in welcher ein Zustellschaft 24 längsverschieblich aber drehfest eingesetzt ist, der noch um ein erhebliches Maß aus dem Werkzeugschaft 12 vortritt. Im dargestellten Fall erfolgt die Drehsicherung durch einen eine Querbohrung 26 im Werkzeugschaft 12 und ein Langloch 28 im Zusteltschaft 24 durchsetzenden Stift 30. Statt dessen könnten die Längsmittelbohrung und der Zustellschaft auch - zumindest in einem Teilbereich - im Querschnitt komplementär polygonal, z. B. quadratisch oder sechseckig ausgebildet sein, oder die Drehung der Schäfte 12, 24 relativ zueinander kann alternativ durch eine Nut-Feder-Verbindung verhindert werden. Zum Einspannen des Bohrwerkzeugs 10 in eine motorisch antreibbare Bohrmaschine ist das freie Ende des aus dem Werkzeugschaft 12 vortretenden Ende des Zustellschafts 24 bei 32 als Sechskant ausgebildet.The tool shank 12 has a longitudinal center bore 22 extending from its outer bore end to the recess 14, in which a feed shank 24 is inserted so as to be longitudinally displaceable but non-rotatable, which still emerges from the tool shank 12 to a considerable extent. In the case shown, the rotation is secured by a pin 30 penetrating a transverse bore 26 in the tool shank 12 and an elongated hole 28 in the additional shank 24. Instead, the longitudinal center bore and the feed shank could also - at least in a partial area - be complementarily polygonal in cross section, e.g. B. be square or hexagonal, or the rotation of the shafts 12, 24 relative to each other can alternatively be prevented by a tongue and groove connection. To clamp the drilling tool 10 in a motor-driven drilling machine, the free end of the end of the feed shaft 24 protruding from the tool shaft 12 is designed as a hexagon at 32.

Die beim Schneidwerkzeug 20 gegenüberliegende Rückseite des bohrungsinneren Hebelarms 18a des Schneidwerkzeugträgers 18 ist als zur Verschiebungsrichtung des Zustellschafts 24 schräg verlaufende Druckfläche 34 ausgebildet, und zwar ist ihre Neigung so gewählt, daß sie bezogen auf die in der Zeichnung dargestellte Lage des Bohrwerkzeugs mit sich nach rechts öffnender Ausnehmung 14 von oben rechts nach unten links verläuft. Ein am unteren Ende des Zustellschafts 24 angesetzter und an der Rückseite des bohrungsmündungsseitigen zweiten Hebelarms 18b vorbeigeführter Zustellnocken 36 ist durch Einschieben des Zustellschafts in den Werkzeugschaft mit seinem etwas abgerundeten Vorderende an der Drückfläche 34 zur Anlage bringbar. Bei weiterem Einschieben drängt der mit seiner Rückseite an der geschlossenen Seite der Ausnehmung abgestützte Zustellnocken 36 die Druckfläche 34, d. h. den bohrungsinneren Hebelarm 18a in Richtung zur offenen Seite der Ausnehmung 14, wodurch das Schneidwerkzeug 20 mit zunehmendem Einschub des Zustellschafts 24 aus der Ausnehmung 14 vortritt, bis es die in der Zeichnung in strichpunktierten Linien angedeutete, über den Umfang des Werkzeugschafts 12 vorstehende Lage einnimmt. Bezogen auf die von der Längsmittelachse des Bolzens 16 gebildete Schwenkachse des Schneidwerkzeugträgers 18 wird der Hebelarm der vom Zustellnocken 36 auf die Druckfläche 34 beim Einschieben des Zustellschafts 24 ausgeübten Vorschubkraft also mit zunehmender Einschubtiefe größer.The back of the lever arm 18a of the cutting tool carrier 18, which is opposite the cutting tool 20, is designed as a pressure surface 34 which extends obliquely to the direction of displacement of the infeed shaft 24, namely its inclination is selected such that it relates to the right in relation to the position of the drilling tool shown in the drawing opening recess 14 runs from top right to bottom left. A feed cam 36 attached to the lower end of the feed shaft 24 and guided past the rear of the second lever arm 18b on the bore mouth side can be brought into contact with the pressure surface 34 by pushing the feed shaft into the tool shaft with its somewhat rounded front end. Upon further insertion, the delivery cam 36 supported with its rear side on the closed side of the recess urges the pressure surface 34, i. H. the bore-inner lever arm 18a in the direction of the open side of the recess 14, as a result of which the cutting tool 20 emerges from the recess 14 with increasing insertion of the feed shank 24 until it assumes the position protruding beyond the circumference of the tool shank 12, indicated in broken lines in the drawing. Relative to the swivel axis of the cutting tool carrier 18 formed by the longitudinal central axis of the bolt 16, the lever arm of the feed force exerted by the feed cam 36 on the pressure surface 34 when the feed shaft 24 is pushed in is therefore greater with increasing insertion depth.

Auch die Rückseite des bohrungsmündungsseitigen Hebelarms 18b des Schneidwerkzeugträgers 18 ist als Druckfläche 38 ausgebildet, die gegensinnig zur Druckfläche 34 geneigt verläuft. Beim Zurückziehen des Zustellschafts 24 läuft daher die komplementär geneigt ausgebildete Fläche 40 des Zustellnockens 36 an der Druckfläche 40 an und verschwenkt den Schneidwerkzeugträger 18 bei weiterem Zurückziehen des Zustellschafts 24 zwangsläufig so, daß das Schneidwerkzeug 20 wieder in die Ausnehmung 14 zurückgestellt wird.The rear of the lever arm 18b on the bore mouth side of the cutting tool carrier 18 is also designed as a pressure surface 38, which is inclined in the opposite direction to the pressure surface 34. When the feed shank 24 is withdrawn, the complementarily inclined surface 40 of the feed cam 36 runs against the pressure surface 40 and inevitably pivots the cutting tool carrier 18 when the feed shank 24 is retracted in such a way that the cutting tool 20 is returned to the recess 14.

An sich ist das Bohrwerkzeug 10 im bisher beschriebenen Umfang bereits funktionsfähig, jedoch ist seine Handhabung für die Praxis noch dadurch verbessert, daß in dem aus dem Werkzeugschaft 12 herausgeführten Bereich des Zustellschafts 24 eine diesen umgebende Schraubenfeder 42 angeordnet ist, deren unteres Ende auf der bohrungsmündungsseitigen Stirnfläche des Werkzeugschafts 12 abgestützt ist, während ihr anderes Ende unter Druckvorspannung an der zur Bohrung weisenden Stirnfläche eines auf den Zustellschaft 24 augeschobenen und auf ihm befestigten Bundbauteils 44 anliegt. Durch einen in einer radialen Gewindebohrung 46 im Bundbauteil 44 eingeschraubten Gewindestift 48 ist der Bundbauteil in wählbaren Axialstellungen auf dem Zustellschaft 24 befestigbar. Die Vorspannung der Schraubenfeder 24 ist daher in bestimmten Maße veränderbar.As such, the drilling tool 10 is already functional to the extent described so far, but its handling is improved in practice in that a helical spring 42 surrounding it is arranged in the area of the delivery shaft 24 which is led out of the tool shaft 12, the lower end of which is on the bore mouth side End face of the tool shank 12 is supported, while its other end rests under pressure on the end face facing the bore of a collar component 44 pushed onto the feed shank 24 and fastened thereon. Through a The collar component can be fastened in selectable axial positions on the feed shaft 24 in a radial threaded bore 46 screwed into the collar component 44. The bias of the coil spring 24 can therefore be changed to a certain extent.

Die Schraubenfeder 42 wird von einer Hülse 50 umgeben, die am Ende des Werkzeugschafts 12 angesetzt ist und in deren anderes Ende der Bundbauteil 44 passend d. h. längsverschieblich eingreift.The coil spring 42 is surrounded by a sleeve 50 which is attached to the end of the tool shank 12 and in the other end of which the collar component 44 fits d. H. engages longitudinally.

Zur Aufnahme des vom Schneidwerkzeug 20 aus der Wandung einer Vorbohrung herausgearbeiteten Bohrmehls dient eine in Einschubrichtung vor dem Schneidwerkzeugträger 18 liegende, die Ausnehmung 14 fortsetzende, erweiterte Aufnahmetasche 52. Verklemmungen des Schneidwerkzeugträgers 18 in der ausgeschwenkten Stellung durch in der Ausnehmung 14 hinter dem ausgeschwenkten Schneidwerkzeugträger angesammeltes Bohrmehl werden dadurch vermieden. Selbst wenn sich in diesem Bereich Bohrmehl angesammelt haben sollte, wird es beim Zurückziehen des Zustellschafts in die Aufnahmetasche 52 verdrängt.An enlarged receiving pocket 52, which continues the recess 14 in the insertion direction and continues the recess 14, serves to receive the drilling dust worked out by the cutting tool 20 from the wall of a pilot hole. Jamming of the cutting tool carrier 18 in the pivoted-out position by accumulated in the recess 14 behind the pivoted-out cutting tool carrier This avoids drilling dust. Even if drilling dust should have accumulated in this area, it is displaced into the receiving pocket 52 when the delivery shaft is pulled back.

Das in den Figuren 2 und 3 gezeigte Bohrwerkzeug 110 unterscheidet sich von dem vorstehend beschriebenen Bohrwerkzeug 10 im wesentlichen nur durch die Art und Weise der drehfesten aber längsverschieblichen Koppelung des Zustell- und des Werkzeugschafts, so daß es genügt, nachstehend nur diese Koppelung zu beschreiben, während bezüglich des allgemeinen Aufbaus des Bohrwerkzeugs 110 auf die vorausgehende Beschreibung Bezug genommen wird. Die den Teilen des Bohrwerkzeugs 10 entsprechenden Teile des Bohrwerkzeugs 110 sind mit den gleichen Bezugszeichen, jedoch mit vorangestellter 1 bezeichnet.The drilling tool 110 shown in FIGS. 2 and 3 differs from the drilling tool 10 described above essentially only in the manner of the rotationally fixed but longitudinally displaceable coupling of the feed and tool shafts, so that it is sufficient to describe only this coupling below, while referring to the general description of the drilling tool 110, the foregoing description. The parts of the drilling tool 110 which correspond to the parts of the drilling tool 10 are identified by the same reference numerals, but with the preceding 1.

Der Zustellschaft 124 des Bohrwerkzeugs 110 trägt einen aufgepreßten oder in anderer Weise starr befestigten Vielkeilkörper 160, der in einen mit einem komplementären Vielkeilprofil versehenen Hülsen-Abschnitt 162 am rückwärtigen Ende des Werkzeugschafts 112 eingreift, wobei die Länge des Hülsen-Abschnitts 162 im Verhältnis zum Vielkeilkörper 160 so bemessen ist, daß der Vielkeilkörper 160 gegen die Wirkung der Feder 142 um den für die Verschwenkung des Schneidwerkzeugträgers 118 erforderlichen Zustellweg in den Hülsen-Abschnitt 162 einschiebbar ist.The feed shaft 124 of the drilling tool 110 carries a pressed-on or otherwise rigidly fastened multi-wedge body 160 which engages in a sleeve section 162 provided with a complementary multi-wedge profile at the rear end of the tool shaft 112, the length of the sleeve section 162 in relation to the multi-wedge body 160 is dimensioned such that the multi-wedge body 160 can be pushed into the sleeve section 162 against the action of the spring 142 by the feed path required for the pivoting of the cutting tool carrier 118.

Der Zustellschaft 124 ist in diesem Falle mit einer durchgehenden Längsmittelbohrung 164 versehen, die es ermöglicht, daß das sich beim Arbeiten mit dem Werkzeug 110 in der den Schneidwerkzeugträger 118 aufnehmenden Ausnehmung 114 sammelnde Bohrmehl ständig abgesaugt werden kann, wenn die Antriebsmaschine für das Werkzeug mit einer entsprechenden Absaugeinrichtung versehen ist.In this case, the feed shank 124 is provided with a continuous longitudinal center bore 164, which makes it possible for the drilling dust which collects when working with the tool 110 in the recess 114 receiving the cutting tool carrier 118 to be continuously sucked off if the drive machine for the tool has a corresponding suction device is provided.

Auch bei dem in den Fig. 4 und 5 gezeigten Hinterschnitt-Bohrwerkzeug 210 erfolgt die drehfeste und längsverschiebliche Verbindung des Zustellschafts 224 mit dem Werkzeugschaft 212 durch eine Vielkeilverbindung. Hierfür ist der aus dem Werkzeugschaft 212 herausgeführte Bereich des Zustellschafts 224 insgesamt als Vielkeil-Schaftabschnitt 260 ausgebildet, der an seinem dem Werkzeugschaft 212 zugewandten Vorderende noch etwas in einen hülsenförmigen Abschnitt 262 am rückwärtigen Ende des Werkzeugschafts eingreift. Das Innere dieses hülsenförmigen Abschnitts 262 ist mit einem zum Vielkeilprofil des Schaftabschnitts 260 komplementären Vielkeilprofil versehen, wodurch in Drehrichtung des Werkzeugs eine formschlüssige Verbindung zwischen dem Schaftabschnitt 260 und dem Hülsen-Abschnitt 262 gegeben ist. Der Hülsen-Abschnitt 262 ist wiederum solang bemessen, daß der Vielkeil-Schaftabschnitt 260 um den erforderlichen Zustellweg in den Hülsen- Abschnitt 262 hineingeschoben werden kann. Die die Rückstellung unterstützende Druckfeder 242 ist zwischen der vorderen Stirnfläche 261 des Vielkeil-Schaftabschnitts 260 einerseits und am Boden 263 des Hülsen-Abschnitts 262 am Werkzeugschafts 212 andererseits abgestützt. Auch bei diesem Ausführungsbeispiel kann der Zustellschaft 224 mit einer Längsmittebohrung 264 (Fig. 5) zur Absaugung des Bohrmehls während des Bohrvorgangs versehen sein.Also in the undercut drilling tool 210 shown in FIGS. 4 and 5, the rotationally fixed and longitudinally displaceable connection of the feed shank 224 to the tool shank 212 takes place by means of a multi-spline connection. For this purpose, the area of the feed shank 224 which is led out of the tool shank 212 is designed overall as a multi-wedge shank section 260 which, at its front end facing the tool shank 212, engages somewhat in a sleeve-shaped section 262 at the rear end of the tool shank. The interior of this sleeve-shaped section 262 is provided with a multi-wedge profile that is complementary to the multi-spline profile of the shaft section 260, as a result of which a positive connection between the shaft section 260 and the sleeve section 262 is provided in the direction of rotation of the tool. The sleeve section 262 is in turn dimensioned such that the multi-wedge shaft section 260 can be pushed into the sleeve section 262 by the required feed path. The compression spring 242, which supports the restoration, is supported between the front end face 261 of the multi-spline shank section 260 on the one hand and on the bottom 263 of the sleeve section 262 on the tool shank 212 on the other hand. In this exemplary embodiment too, the feed shaft 224 can be provided with a longitudinal center bore 264 (FIG. 5) for suctioning off the drilling dust during the drilling process.

Claims (11)

1. Drilling tool (10 ; 110 ; 210) for the production of undercuts in pilot bores in masonry, concrete, rock and the like, having a tool shaft (12 ; 112; 212) which can be inserted into the pilot bore that is to be provided with the undercut, and which can be driven in rotation, in whose end area at least one cutting tool (20 ; 120 ; 220) is so disposed that its cutting edge, after insertion of the shaft into the pilot bore, can be displaced gradually radially outwardly into the wall of the pilot bore ; the cutting tool (20 ; 120 ; 220) being disposed on a cutting tool holder (18 ; 118 ; 218) in the form of a two-armed lever pivotingly mounted in a longitudinally disposed, slot-like recess (14 ; 114; 214) in the bore-internal end section of the tool shaft (12 ; 112; 212); the cutting tool holder being pivotable from a position wherein it is retracted into the slot-like recess (14 ; 114 ; 214) to a position wherein the cutting tool (20; 120 ; 220) protrudes from the tool shaft (12; 112 ; 212), by the bore-internal end of . a cutter feed shaft (24 ; 124; 224) passing longitudinally displaceably by a certain amount, but co-rotationally, through the tool shaft (12 ; 112 ; 212), and with its outer end brought out of the outer end of the tool shaft, by the driving of the cutter feed shaft into the tool shaft, characterized in that the cutting tool holder (18 ; 118 ; 218) has on its back opposite the cutting tool (20 ; 120 ; 220), on its bore-internal lever arm (18a), a thrust surface (34 ; 134 ; 234) running at an angle to the direction of displacement of the cutter feed shaft (24 ; 124 ; 224), which thrust surface is engaged by a cutter feed cam (36 ; 136 ; 236) formed on the bore-internal end of the cutter feed shaft (24 ; 124 ; 224), which cam, upon a displacement of the cutter feed shaft (24 ; 124 ; 224) relative to the tool shaft (12 ; 112 ; 212) into the bore interior, rocks the bore-internal lever arm (18a) of the cutting tool holder (18 ; 118 ; 218) out of the recess (24 ; 114; 214) of the tool shaft (12; 112; 212) with an increasingly larger lever arm, and in that the back of the bore-orifice-side lever arm (18b) of the cutting tool holder (18 ; 118 ; 218) has a thrust surface (38 ; 138 ; 238) running at a slant opposite that of the bore-internal lever arm (18a), which is engaged by the cutter feed cam (36 ; 136 ; 236) upon a displacement of the cutter feed shaft (24 ; 124 ; 224) relative to the tool shaft (12 ; 112 ; 212) out of the bore interior.
2. Drilling tool according to Claim 1, with a cutting tool holder (18 ; 118; 218) biased by a spring into the retracted position, characterized in that the cutter feed shaft (24 ; 124 ; 224) bears in the portion led out of the tool shaft (12; 112; 212) a biased coil spring (42 ; 142) thrusting against the tool shaft on the one hand and against the cutter feed shaft on the other.
3. Drilling tool according to Claim 2, characterized in that the coil spring (42 ; 142) thrusts against the bore orifice-side end face of the tool shaft (12 ; 112) at the one end and at the other against the end face of a collar (44 ; 144) provided on the cutter feed shaft (24 ; 124).
4. Drilling tool according to Claim 3, characterized in that the collar (44 ; 144) can be fastened at selectable axial positions of the area of the cutter feed shaft (24 ; 124) protruding from the tool shaft (12 ; 112).
5. Drilling tool according to any one of Claims 2 to 4, characterized in that the coil spring (42 ; 142) is surrounded by a sleeve (50 ; 150) attached to one end of the tool shaft (12 ; 112), into which the front end of the collar (44 ; 144) pointing toward the bore engages in a longitudinally displaceable manner.
6. Drilling tool according to any one of Claims 1 to 5, characterized in that the cutter feed shaft (24) is coupled with the tool shaft (12) co-rotationally but longitudinally displaceably, by a pin (30) provided in a transverse bore (26) in the tool shaft (12) and passing through a longitudinal slot (28) in the cutter feed shaft (24).
7. Drilling tool according to any one of Claims 1 to 5, characterized in that a spline body (160) is provided on the cutter feed shaft (124) and is disposed, co-rotationally with but longitudinally displaceably, within a tool shaft section (162) of sleeve-like construction and having an internal spline profile complementary to the spline body (160).
8. Drilling tool according to Claim 1, characterized in that the cutter feed shaft (224) is constructed in its portion brought out of the tool shaft (212) as a spline shaft section (260) which, at its front end facing the tool shaft (212) still is partially engaged in a sleeve-like section (262) of the tool shaft (212), which is provided with an internal splined profile complementary to the splined profile of the splined shaft section (260), and that the sleeve section (262) provided with the internal splined profile is of such length that the splined shaft section (260) is displaceable into the sleeve section (262) to the extent necessary for the rocking of the cutting tool holder (218).
9. Drilling tool according to Claim 8, with a cutting tool holder (218) biased by a spring into the retracted position, characterized in that within the sleeve section (262) there is disposed a compression spring (242) thrusting against the front end (261) of the splined shaft section (260) at one end and against the bottom (263) of the sleeve section (262) of the tool shaft (212) at the other.
10. Drilling tool according to any one of Claims 1 to 9, characterized in that the slot-like recess (14 ; 114; 214) for the accommodation of the cutting tool holder (18 ; 118 ; 218) is prolonged into the section of the tool shaft (12 ; 112 ; 212) that lies in front of the cutting tool holder (18 ; 118 ; 218) in the driving direction, and formed into a receiving pocket (52 ; 152 ; 252) for the material cut from the wall of the pilot bore by the cutting tool (20 ; 120 ; 220).
11. Drilling tool according to any one of Claims 7 to 10, characterized in that the cutter feed shaft (124 ; 224) is pierced by a longitudinal bore (164 ; 264) which at the cutting tool end leads into the recess (114; 214) in the tool shaft (112; 212), which receives the cutting tool holder.
EP81104350A 1980-06-30 1981-06-05 Drilling tool with expansible cutters Expired EP0043000B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT81104350T ATE7325T1 (en) 1980-06-30 1981-06-05 UNDERCUT DRILLING TOOL.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3024656A DE3024656C2 (en) 1980-06-30 1980-06-30 Undercut drilling tool
DE3024656 1980-06-30

Publications (2)

Publication Number Publication Date
EP0043000A1 EP0043000A1 (en) 1982-01-06
EP0043000B1 true EP0043000B1 (en) 1984-05-02

Family

ID=6105980

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81104350A Expired EP0043000B1 (en) 1980-06-30 1981-06-05 Drilling tool with expansible cutters

Country Status (7)

Country Link
US (1) US4411324A (en)
EP (1) EP0043000B1 (en)
JP (1) JPS5739915A (en)
AT (1) ATE7325T1 (en)
CA (1) CA1157464A (en)
DE (1) DE3024656C2 (en)
ES (1) ES8204334A1 (en)

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Also Published As

Publication number Publication date
ES503444A0 (en) 1982-05-16
ES8204334A1 (en) 1982-05-16
US4411324A (en) 1983-10-25
DE3024656C2 (en) 1982-08-12
ATE7325T1 (en) 1984-05-15
JPS5739915A (en) 1982-03-05
DE3024656A1 (en) 1982-01-21
CA1157464A (en) 1983-11-22
EP0043000A1 (en) 1982-01-06

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