EP2934799A1

EP2934799A1 - Drill bit with an exchangeable cutting portion

Info

Publication number: EP2934799A1
Application number: EP13821105.7A
Authority: EP
Inventors: Matthaeus Hoop
Original assignee: Hilti AG
Current assignee: Hilti AG
Priority date: 2012-12-21
Filing date: 2013-12-20
Publication date: 2015-10-28
Also published as: JP6175513B2; BR112015013811B1; CN104955598B; KR20150095913A; CN104955598A; US10201858B2; BR112015013811A2; RU2015129594A; KR101726529B1; US20150328694A1; WO2014096360A1; RU2631566C2; JP2016502937A; WO2014096360A8; EP2745965A1

Abstract

Drill bit (10), which is rotatable in a direction of rotation (21) about an axis of rotation (22), having: a cutting portion (11) with an annular portion (13), which is connected at a first end to one or more cutting elements (14) and has at a second end a first insertion element (15), and a drill shaft portion (12) with a cylindrical drill shaft (16), which has at an end, towards the cutting portion (11), a second insertion element (17). In a direction of insertion parallel to the axis of rotation (22), the insertion elements (15, 17) form a plug-in connection and can be additionally connected by way of at least one pin element (25), which is movable in at least one slit-shaped clearance (26).

Description

Hilti Aktiengesellschaft in Schaan Principality of Liechtenstein

Drill bit with a replaceable cutting section Technical area

The present invention relates to a drill bit with a replaceable cutting section according to the preamble of claim 1.

The term "drill bit" summarizes all drilling tools that have a hollow, cylindrical drill shaft and a cutting section with one or more cutting elements, such as core bits and can countersink. Depending on the application, the drill bits may have additional elements, such as a depth stop that limits the drilling depth.

State of the art

Drill bits consist of a cutting section with one or more cutting elements, a drill shank section and a receiving section with insertion end. The drill bit is attached via the insertion end in the tool holder of a core drilling machine and driven in drilling operation by the core drill in a rotational direction about an axis of rotation. Known drill bits are subdivided into interchangeable cutting section drill bits and drill bits with no interchangeable cutting section, with removable interchangeable section drill bits providing separable and non-detachable connections. A connection is said to be detachable if the connection can be released non-destructively by the user, such as a plug connection, a screw connection or a magnetic connection. A connection is said to be non-releasable if the user can release the connection only by destroying the connection means, such as a solder connection, a welded connection, a riveted connection or an adhesive connection.

In the drill bit disclosed in US 3,888,320 A, the cutting portion and the drill stem portion are connected to each other via a detachable plug-and-turn connection. The cutting portion includes a ring portion connected at a first end to a plurality of cutting elements and having at a second end an outer plug element and an annular stop shoulder. The drill shank section comprises a cylindrical shaped drill shank, which has an inner plug-in element with an end face at a, the cutting section facing the end. The plug-in elements form a plug-in connection in a plug-in direction parallel to the axis of rotation. The outer plug-in element has on the inside a plurality of pin elements which are directed radially inwardly in a plane perpendicular to the axis of rotation. The inner male member has a plurality of slit-like recesses in L-shape into which the male members are inserted. The L-shaped recesses consist of a transverse slot which is perpendicular to the axis of rotation, and a connecting slot which is parallel to the axis of rotation and connects the transverse slot with a lower edge of the inner plug-in element. In the known drill bit with exchangeable cutting section is in the closed plug-and-turn connection between the cutting portion and the Bohrschaftabschnitt in a direction parallel to the axis of rotation an axial clearance. A gap is formed between the end face of the inner plug-in element and the stop shoulder of the outer plug-in element, so that the power transmission from the drill shaft section to the cutting section takes place exclusively via the pin elements. The gap also causes a cooling and rinsing medium is not completely transported to the processing site, but can be misdirected into the gap on the inside of the drill bit.

Another disadvantage of the known drill bit with exchangeable cutting section shows when the drill bit has jammed in the ground. During core drilling, the drill bit usually jams in the ground during drilling and has to be loosened by the operator. To release the jammed drill bit, the drill bit is driven counter to the direction of rotation in stator-guided core drilling and exerted on the drill bit by the drill stand, a tensile force, which is directed counter to the drilling direction. The operator tries to clear the drill bit from the ground by turning it manually with the aid of a tool wrench and simultaneously pulling it with the help of the drill stand. The L-shaped recesses are liable to cause the operator to rotate the drill shaft portion about the axis of rotation until the pin member abuts the connection slot and at the same time actuate the hand wheel of the drill stand so that the pin member is moved out of the connection slot. Once the plug-in rotary connection between cutting section and Bohrschaftabschnitt is solved, the cutting section must otherwise be released from the ground, for example by removing the substrate.

Presentation of the invention

The object of the present invention is to develop a drill bit with exchangeable cutting section, in which the risk is reduced that when removing a jammed drill bit from the ground unintentionally opens the plug-in rotary connection of the plug-in elements and the Bohrschaftabschnitt is removed without the cutting section of the substrate. In addition, the stability of the drill bit during drilling and the stability against a tensile load by a drill stand to be increased.

This object is achieved according to the invention in the drill bit mentioned above by the features of the independent claim 1. Advantageous embodiments emerge from the dependent claims.

According to the invention, the slot-shaped recess has a connecting slot and a transverse slot with a driving area and a securing area, the driving area being connected to the connecting slot on a side of the connecting slot facing the direction of rotation, and the securing area facing away from the direction of rotation , Side of the connection slot is connected to the connection slot. The torque transmission from the Bohrschaftabschnitt on the cutting section via the pin elements and the driving area. On the, opposite the driving area, side of the connection slot, the backup area is arranged. The securing area reduces the risk that when releasing a jammed drill bit from the ground, the plug-in rotary connection between the Bohrschaftabschnitt and the

Cutting section is opened unintentionally. The operator tries to free the jammed drill bit by turning the drill shaft section with the help of a tool key around the axis of rotation and simultaneous pulling with the help of the drill stand from the ground. Practice has shown that operators pull on the drill shaft section especially when the pin element abuts the transverse slot. If the pin element abuts the driving area or the securing area in the drill bit according to the invention, there is no danger of the plug-in rotary connection being opened. In the drill bit according to the invention, the plug-in rotary connection is opened only when the operator pulls the Bohrschaftabschnitt exactly at the moment when the pin member is above the connection slot. The risk of unintentionally opening the plug-in rotary connection is significantly reduced compared to slit-shaped recesses in L-shape.

Preferably, the height of the connecting slot parallel to the axis of rotation is at least 10 mm. At a height of at least 10 mm, a sufficient stability of the cutting section against a tensile load is ensured by a drill stand. The height of the connecting slot parallel to the axis of rotation is particularly preferably not greater than 13 mm. Up to a height of 13 mm, the stability of the cutting section is improved over a tensile load by a drill stand. Larger heights have no or only a small influence on the stability of the cutting section compared to a tensile load by a drill stand and only lead to increased material and processing costs.

Preferably, the transverse slot parallel to the axis of rotation at a lower distance to the ring portion of at least 3 mm. At a minimum distance of 3 mm sufficient stability of the cutting section against a tensile load when loosening a jammed drill bit with the help of a drill stand is ensured.

In this case, the lower distance of the transverse slot to the ring portion is particularly preferably not greater than 5 mm. Up to a distance of 5 mm, the stability of the

Cutting section improved against a tensile load. Larger distances have no or only a small influence on the stability of the cutting section against a tensile load and only lead to increased material and processing costs.

In a preferred embodiment of the drill bit, the pin elements have a pin height perpendicular to the axis of rotation, the pin height being between 68% and 89% of the shank width of the drill bit. The width of the inner plug-in element is preferably about 50% of the Bohrschaftbreite. As the height of the pin increases, the area for torque transmission increases. In addition, the resistance to tensile load is improved.

Particularly preferably, the pin elements are formed circular-cylindrical with a pin radius, wherein the pin radius is between 2.5 and 5 mm. The torque transmission from the Bohrschaftabschnitt on the cutting section via the pin elements and the outer plug-in element. The larger the pin radius of the pin elements, the fewer pin elements required for torque transmission.

Preferably, the width of the driving area is not smaller than the pin radius plus 1 .5 mm. In this minimum width for the driving range sufficient stability of the cutting section against a tensile load is ensured by a drill stand. The pin elements are located on the driving area and do not break out of the driving area.

The width of the driving area is particularly preferably not greater than the pin radius plus 3 mm. Up to a width of half the pin diameter plus 3 mm, the stability of the cutting section against a tensile load by a drilling Stands improved. Larger widths have no or only a small influence on the stability of the cutting section against a tensile load and reduce the stability of the cutting section unnecessarily.

In a first preferred variant, the width of the entrainment area and the width of the security area coincide. The driving area and the securing area have a minimum width of pin radius plus 1.5 mm. This version is particularly suitable for drill bits with large diameters, in which the proportion of transverse slots on the circumference is small.

In a second preferred variant, the width of the driving area is greater than the width of the securing area. The driving area and the securing area have a minimum width of pin radius plus 1.5 mm. This version is particularly suitable for drill bits with small diameters, in which the proportion of transverse slots on the circumference is large.

In a preferred embodiment, the first plug-in element are formed as an outer plug-in element with a stop shoulder and the second plug-in element as an inner plug-in element with an end face. In the connected state, the end face of the inner plug-in element bears against the stop shoulder of the outer plug-in element. The power transmission from the drill shank section to the cutting section takes place during drilling over the end face and the stop shoulder. The risk of deformation of the outer plug-in element is reduced if the power transmission does not take place via the pin elements, so that the drill bit according to the invention has a higher stability. The stop shoulder may be annular or ringabschnittsformig. By a flat support of the end face on an annular stop shoulder, the drill bit is formed on the inside tight, so that the misdirection of a cooling and flushing medium is prevented. The cooling and rinsing medium supplied, for example, via the insertion end of the drill bit, flows completely to the processing point and ensures cooling of the cutting elements and removal of drill cuttings.

Particularly preferably, the at least one pin element is attached to the outside of the inner plug-in element and the outer plug-in element has the at least one slot-shaped recess. The arrangement of the slot-shaped recesses on the exchangeable cutting section has the advantage that the more unstable of the two drill bit sections is replaced regularly. The plug-in rotary connection of the plug-in elements according to the invention improves the stability and stability of the drill bit against tensile load. The drill bit section having the slot-shaped recesses is more susceptible to deformation by tensile load than the drill bit section the pin elements are attached. The risk of deformation due to tensile load increases with increasing proportion of slot-shaped recesses on the circumference of the plug-in element. Since the diameter of the outer plug-in element is greater than the diameter of the inner plug-in element, more circumference for the slot-shaped cutouts is available on the outer plug-in element or the proportion of the cutouts on the circumference is smaller. The drill bit is more stable when the slot-shaped recesses are provided on the outer plug-in element.

The arrangement of the pin elements on the inner plug-in element and the arrangement of the slot-shaped recesses on the outer plug-in element, the drill bit can be formed on the inside tight and the misdirection of a cooling and flushing medium can be prevented. The cooling and rinsing medium supplied, for example, via the insertion end of the drill bit, flows completely into the machining location in the case of a dense drill bit and ensures cooling of the cutting elements and removal of drill cuttings. The drill bit of the present invention also allows the operator to monitor the opening and closing of the plug-in pivot connection. This monitoring is not possible or only possible to a limited extent if the slot-shaped recesses are provided on the inner plug-in element.

Particularly preferably, the length of the inner plug-in element is greater than the length of the outer plug-in element. Due to the difference in length between the inner and outer plug-in element ensures that the end face of the inner plug-in element bears against the stop shoulder of the outer plug-in element and during drilling a defined power transmission from the Bohrschaftabschnitt to the cutting section.

Particularly preferably, the length of the outer plug-in element is at least 18 mm. With a minimum length of 18 mm for the outer plug element sufficient stability of the cutting section is ensured. The slot-shaped recesses can be positioned on the outer plug element at a height that the cutting section is stable to the tensile stresses occurring when loosening a jammed drill bit with the help of a drill stand.

The length of the outer plug-in element is particularly preferably not greater than 28 mm. Up to a length of 28 mm for the outer plug-in element, the stability of the cutting section is improved compared to a tensile load. Larger lengths for the outer plug element have no or only a small effect on the stability of the cutting section against a tensile load and only lead to increased material and processing costs. In a preferred embodiment, the outer and inner plug-in element are annular, wherein the difference between an inner diameter of the outer plug-in element and an outer diameter of the inner plug-in element is greater than 0.1 1 mm. Through the gap which forms between the outer and inner plug-in element, it is ensured that the end face of the inner plug-in element bears against the stop shoulder of the outer plug-in element. The drill bit is tightly formed on the inside, so that the supply of a liquid or gaseous cooling and purging medium is ensured to the cutting elements. In addition, a defined power transmission from the core drill on the end face of the Bohrschaftabschnittes on the stop shoulder of the cutting section.

In a preferred embodiment of the drill bit three or more pin elements are attached to the outside of the inner plug element and the outer plug element has three or more slot-shaped recesses, wherein the number of recesses is greater than or equal to the number of pin elements. In the drill bit according to the invention, the power transmission from the end face of the inner plug element takes place on the stop shoulder of the outer plug element and the torque transmission takes place via the pin elements on the outer plug element. The pin elements are particularly preferably evenly distributed around the axis of rotation of the drill bit. Due to the uniform distribution of the pin elements, there is no association between the pin elements and the recesses and a pin element can be inserted into each recess.

The number of slot-shaped recesses must be greater than or equal to the number of pin elements. To close the plug-in rotary connection, a slot-shaped recess must be provided for each pin element. The execution of a drill bit in which the number of recesses is greater than the number of pin elements, has the disadvantage that the stability of the cutting section is unnecessarily reduced. This embodiment is suitable, if at all, for very large diameter drill bits, since in these drill bits the proportion of recesses at the periphery of the outer plug element is smaller than in smaller diameter drill bits.

Particularly preferably, six pin elements are fastened on the outside of the inner plug-in element and the outer plug-in element has six or more slot-shaped cutouts. A swivel joint with six male elements with a pin diameter of 6 mm is suitable for torque transmission for drill bits of different diameters, for example from 50 mm to 250 mm.

In a further development of the drill bit, the ring portion has a guide portion, wherein the guide portion parallel to the longitudinal axis flush with an outer edge, a Inside edge or adjoining an outer and inner edge of the cutting elements. By the flush connection of the guide portion to the cutting elements of the guide portion forms a guide for the cutting elements during drilling and stabilizes the cutting elements. In this case, the guide on the outside of the drill bit on the surrounding the borehole underground or on the inside of the drill bit on the core can be done.

Preferably, the length of the guide portion parallel to the axis of rotation is less than 4 mm. A guide section smaller than 4 mm does not obstruct the supply of a cooling and purging medium, or at least does not substantially hinder it. In a preferred embodiment of the drill bit, a nose is arranged on the outer side of the inner plug element and the outer plug element has a groove, wherein the nose and groove form a positive connection in the connected state in the axial direction. The additional positive connection between the Bohrschaftabschnitt and the cutting portion, the risk can be further reduced that the detachable connection between the Bohrschaftabschnitt and the cutting section unintentionally opens when removing a jammed Bohrkrone from the ground. The formation of the positive connection means as nose and groove allows a simple and reliable connection, which makes it difficult to remove the Bohrschaftabschnittes from the cutting section. The holding force of the connection can be adapted via the geometry of the nose and groove to the application of the drill bit.

Preferably, the nose is arranged in the axial direction between the pin elements and the drill shaft and the groove is arranged in the axial direction at the level of the slot-shaped recesses. Between the slot-shaped recesses of the outer plug-in element arise sections which show a resilient effect. On the number and axial height of the slot-shaped recesses and the length of the outer plug element, the resilient effect can be adjusted. In order to separate the Bohrschaftabschnitt from the cutting section, a force is exerted on the end face of the outer plug element with the aid of a tool in the axial direction. By the force of the resilient portion of the outer plug element is deflected and the positive connection between the nose and groove can be solved. The greater the distance of the groove to the stop shoulder of the outer plug-in element, the greater the deflection of the resilient portion.

Particularly preferably, the groove is annular and arranged in a plane perpendicular to the axis of rotation. An annular groove, which is arranged at the level of the slot-shaped recesses, supports the resilient action of the portions of the outer plug element between the slot-shaped recesses. As the axial direction, a direction is defined parallel to the axis of rotation of the drill bit. In the connected state of Bohrkronenabschnitte the axis of rotation of the drill bit coincides with the longitudinal axes of the Bohrkronenabschnitte, cutting section and Bohrschaftabschnitt together. As the radial plane, a plane perpendicular to the rotation axis is defined, and a radial direction is a direction that extends in the radial plane and intersects the rotation axis of the drill bit and the longitudinal axis of the drill bit sections, respectively.

embodiments

Embodiments of the invention are described below with reference to the drawing. This is not necessarily to scale the embodiments, but the drawing, where appropriate for explanation, executed in a schematic and / or slightly distorted form. With regard to additions to the teachings directly recognizable from the drawing reference is made to the relevant prior art. It should be noted that various modifications and changes may be made in the form and detail of an embodiment without departing from the general idea of the invention. The disclosed in the description, the drawings and the claims features of the invention may be essential both individually and in any combination for the development of the invention. In addition, all combinations of at least two of the features disclosed in the description, the drawings and / or the claims fall within the scope of the invention. The general idea of the invention is not limited to the exact form or detail of the preferred embodiment shown and described below or limited to an article that would be limited in comparison with the subject matter claimed in the claims. For given design ranges, values lying within the specified limits should also be disclosed as limit values and be arbitrarily usable and claimable. For simplicity, the same reference numerals are used below for identical or similar parts or parts with identical or similar function.

Show it:

FIGS. 1A, B a drill bit according to the invention with a cutting section and a

Drill shank portion in the non-connected state (FIG 1A) and in the connected state (FIG 1 B);

FIGS. 2A, B, the drill shank portion of the in FIG. 1 shown in a longitudinal section along the sectional plane AA in FIG. 1A (FIG 2A) and the plug-in element of the Bohrschaftabschnittes in an enlarged view (Figure 2B). FIGS. 3A, B show the cutting portion of FIG. 1 in a longitudinal section (FIG 3A) and the plug element of the cutting section in an enlarged view (FIG 3B);

FIGS. 4A, B, the cutting section in a longitudinal section along the sectional plane B-B in

FIG. 1 A (FIG. 4A) and along the sectional plane C-C in FIG. 1B (FIG.4B); and

FIG. 5 shows another embodiment of a drill bit according to the invention with a

Cutting section and a Bohrschaftabschnitt, which are connected in the axial direction via an additional positive connection as Abziehsicherung. FIGS. 1A, B show a drill bit 10 according to the invention with a cutting section 11, which is connected to a drill shaft section 12 via a detachable plug-and-turn connection. In this case, FIG. 1A, the cutting portion 1 1 and the Bohrschaftabschnitt 12 in the non-connected state with open plug-and-turn connection and FIG. 1 B, the cutting section 1 1 and the Bohrschaftabschnitt 12 in the connected state with closed plug-and-turn connection.

The cutting portion 1 1 comprises a ring portion 13 which is connected at a first end with a plurality of cutting elements 14 and at a second end has a first plug-in element 15. In this case, the first plug-in element is designed as an outer plug-in element 15. The cutting elements 14 are welded to the ring section 13, soldered, screwed or fastened to the ring section 13 in another suitable manner of fastening. The cutting section 1 1 may instead of a plurality of cutting elements 14 also have a single formed as a cutting sleeve cutting element, which is connected to the ring portion 13.

The drill shank section 12 comprises a cylindrical drill shank 16, which has a second plug-in element 17 at an end facing the cutting section 11 and is connected to a receiving section 18 at an end facing away from the cutting section 11. In this case, the second plug-in element is designed as an inner plug-in element 17. The receiving portion 18 comprises a lid 19 and a spigot end 20. The drill bit 10 is fastened via the spigot end 20 in the tool holder of a core drill. In drilling operation, the drill bit 10 is driven by the core drilling machine in a direction of rotation 21 about an axis of rotation 22 and moved in a drilling direction 23 parallel to the axis of rotation 22 in the substrate to be processed. The axis of rotation 22 extends coaxially to a longitudinal axis of the drill shaft 16 and a longitudinal axis of the annular portion 13. The drill bit 10 has a circular cross-section perpendicular to the axis of rotation 22, alternatively, inventions can The drill bits according to the invention have other suitable cross-sections, such as a polygonal cross-section.

The cutting section 11 is connected to the drill shaft section 12 via a plug-in rotary connection 24 (FIG.1B). As a "plug-in rotary connection" connections of two connecting elements are referred to, which form a plug connection in at least one direction, wherein the plugged connection elements are additionally connected via a rotary connection. The plug connection and the rotary connection can be closed successively or simultaneously. The plug-in rotary connection 24 must connect the cutting section 11 and the drill shaft section 12 in all directions of translation and rotation. The cutting section 1 1 must be secured against translations in the drilling direction 23, counter to the drilling direction 23 and radially to the drilling direction 23 and against rotations about the axis of rotation 22.

The cutting section 11 is inserted with the outer plug-in element 15 onto the inner plug-in element 17 of the drill shaft section 12, the plug-in direction of the plug connection running parallel to the axis of rotation 22. The plug connection of the plug-in elements 15, 17 secures the cutting section 1 1 against translations against the drilling direction 23 and radially to the rotation axis 22. About the rotational connection of the plug elements 15, 17 of the cutting section 1 1 against rotation about the axis of rotation 22 and against translation in the drilling direction 23 be secured. The rotary joint comprises six pin elements 25 which are inserted into six slot-shaped recesses 26. The six pin members 25 are attached to the outer side 27 of the inner plug-in element 17 and the six slot-shaped recesses 26 are provided in the outer plug-in element 15. The pin elements 25 and the recesses 26 are distributed uniformly about the axis of rotation 22. Due to the uniform distribution, there is no association between the pin elements 25 and the recesses 26 and a pin element 25 can be inserted into each recess 26.

The cutting section 1 1 can be easily and quickly connected to the Bohrschaftabschnitt 12 by the operator. For this purpose, the cutting section 11 is inserted with the outer plug element 15 onto the inner plug element 17 of the drill shaft section 12 in such a way that the pin elements 25 are arranged in the slot-shaped cutouts 26. The cutting section 1 1 is moved in the insertion direction and then secured by rotation about the axis of rotation 22.

FIGS. 2A, B show the drill shaft section 12 of the drill bit 10 according to the invention in a longitudinal section along the sectional plane AA in FIG. 1 A. FIG. 2A the drilling shaft section 12 and FIG. 2B designed as an inner plug element second plug-in element 17 in an enlarged view.

The drill shaft section 12 comprises the cylindrical drill shaft 16 and the inner plug element 17, which are monolithic. As an alternative to the monolithic design, the inner plug-in element 17 may be formed as a separate part and subsequently connected to the drill shaft 16. On the outer side 27 of the inner plug-in element 17, the pin elements 25 are attached. The pin members 25 and the inner plug member 17 may be made of different materials and bonded or made of the same material, and the pin members 25 are formed by forming methods such as embossing or punching.

The drill shaft 16 has, perpendicular to the axis of rotation 22, an outer diameter d _a , an inner diameter d, and a Bohrschaftbreite b, b = (d _A - di) / 2, on. The inner plug-in element 17 has, perpendicular to the axis of rotation 22, an outer diameter d ₂ , _a and an inner diameter d ₂ , i. In this case, the inner diameter d _2, i of the inner plug element 17 corresponds to the inner diameter d, of the drill shaft 16 and the outer diameter d _{2, a of} the inner plug element 17 is smaller than the outer diameter d _{a of} the drill shaft 16, so that on the outside of the Bohrschaftabschnittes 12 forms an annular step.

FIG. 2B shows the inner plug-in element 17 in an enlarged view. The inner plug-in element 17 comprises an outer lateral surface 31, an inner lateral surface 32 and an end surface 33. At the transition from the drill shaft 16 to the inner plug-in element 17 there is an annular stop shoulder 34.

The inner plug-in element 17 has a length l ₂ parallel to the axis of rotation 22 and a width b ₂ perpendicular to the axis of rotation 22. The pin element 25 is formed circular cylindrical with a pin radius R _z parallel to the axis of rotation 22 and a pin height H _z perpendicular to the axis of rotation 22. The lower edge of the pin element 25 is parallel to the axis of rotation 22 at a distance Az to the end face 33 of the inner plug-in element 17th

FIGS. 3A, B show the cutting portion 1 1 of FIG. 1 shown drill bit 10 in a longitudinal section parallel to the plane of FIG. 1 A. FIG. 3A shows the entire cutting section 11 and FIG. 3B shows a slot-shaped recess 26 in the outer plug element 15 in an enlarged view.

The cutting section 1 1 comprises the ring section 13, the cutting elements 14 and the outer plug-in element 15. The ring section 13 and the outer plug-in element 15 are monolithic in the illustrated embodiment. Alternative to monolithic training may be formed as a separate part of the outer plug-in element 15 and then connected to the ring portion 13.

The cutting elements 14 are arranged in a plane perpendicular to the rotational axis 22 annularly around the ring portion 13 and each have an outer edge 41 and an inner edge 42. The outer edges 41 of the cutting elements 14 form an outer circle with an outer diameter D _a and the inner edges of an inner circle with an inner diameter Dj. The cutting elements 14 create a borehole in the underground with a borehole diameter corresponding to the outer diameter D _a . Inside the drill bit 10, a drill core with a drill core diameter, which corresponds to the inner diameter D, is formed. The outer plug-in element 15 has an outer diameter di, _a and an inner diameter di _{; i} perpendicular to the axis of rotation 22. The outer diameter di _{, a of} the outer plug element 15 are smaller than the outer diameter D _a and the inner diameter du of the outer plug element 15 is greater than the inner diameter D ,.

FIG. 3B shows a slot-shaped recess 26 in the outer plug-in element 15 in an enlarged view. The slot-shaped recess 26 consists of a transverse slot 43, which is arranged perpendicular to the axis of rotation 22, and a connecting slot 44, which is arranged parallel to the axis of rotation 22. The connecting slot 44 connects the transverse slot 43 with an upper edge 45 of the outer plug-in element 15, which is open at the upper edge 45 in the region of the connecting slot 44. The pin elements 25 are inserted via the connecting slot 44 in the slot-shaped recess 26 and displaced by rotation about the axis of rotation 22 in the transverse slot 43. The torque transmission from the pin element 25 to the outer plug-in element 15 takes place in the transverse slot 43.

The outer plug-in element 15 has a length II parallel to the axis of rotation 22 and a width bi (FIG. 4A) perpendicular to the axis of rotation 22. The transverse slot 43 has a width B perpendicular to the axis of rotation 22 and a height H parallel to the axis of rotation 22. The connecting slot 44 has a width b perpendicular to the axis of rotation 22 and a height h parallel to the axis of rotation 22. The width b of the connecting slot 44 is greater than the pin diameter 2R _{Z of} the pin elements 25, so that the pin elements 25 can be easily inserted into the connecting slot 44. In this case, the insertion of the pin elements 25 can be facilitated by an insertion bevel 46 at the upper edge 45. The height h of the connecting slot 44 is selected so that the cutting section 1 1 has sufficient stability against tensile loads when releasing a jammed drill bit. If the height h chosen too low, there is a risk of deformation of the outer plug-in element 15th

The transverse slot 43 has, parallel to the axis of rotation 22, a lower distance A _{; U from} the annular section 13 and an upper distance from the upper edge 45, the upper distance of the Height h of the connecting slot 44 corresponds. The lower distance A _{1 u} to the ring section 13 is selected so that the cutting section 1 1 has sufficient stability against tensile loads by a drill stand. If the lower distance A _{1 u is} chosen too low, there is a risk of deformation of the outer plug-in element 15. The transverse slot 43 comprises a driving area 47, a securing area 48 and a transition area 49. The driving area 47 and the securing area 48 are related to the direction of rotation 21 the drill bit 10 arranged on different sides of the connecting slot 44, wherein the driving and securing portion 47, 48 are connected via the transition region 49 with the connecting slot 44. The driving area 47 is arranged on the side of the connecting slot 44 facing the direction of rotation 21, and the securing area 48 is arranged on the side facing away from the direction of rotation 21. The torque transmission from the drill shank portion 12 to the cutting portion 1 1 via the pin members 25 and the driving portion 47. The securing portion 48 reduces the risk that when loosening a jammed Bohrkrone from the ground, the plug-in rotary connection 24 between the Bohrschaftabschnitt 12 and the cutting section 1 1 unintentionally opened.

The entrainment region 47 has a width Bi perpendicular to the axis of rotation 22, the height of the entrainment region 47 corresponds to the height H of the transverse slot 43. The securing region 48 has a width B ₂ perpendicular to the axis of rotation 22, the height of the securing region 48 corresponds to the height H of FIG Transverse slot 43. The widths Bi, B _{2 of} the driving portion 47 and the securing portion 48 are selected so that the pin members 25 are held at a tensile load in the transverse slot 43 and do not break out.

FIGS. 4A, B show the cutting section 11 of the drill bit 10 according to the invention in a longitudinal section along the sectional plane B-B in FIG. 1 A (FIG. 4A) and along the section plane C-C in FIG. 1B (FIG.4B). The cutting section 1 1 comprises the ring section 13, the cutting elements 14 and the outer plug-in element 15.

The cutting elements 14 are composed of a matrix zone 51 and a neutral zone 52, wherein the matrix zone 51 consists of a powder material mixed with cutting particles and the neutral zone 52 consists of a weldable powder material without cutting particles. The two-part construction of the cutting elements 14 is required in order to weld the cutting elements 14 to the ring portion 13. The ring portion 13 is flush with the inner edge 42 of the cutting element 14 and has over the outer edge 41 of the cutting element 14 has a recess 53. The ring portion 13 includes a guide portion 54 and a core removal portion 55 on the inner side. The core removal portion 55 has an inner diameter decreasing toward the cutting elements 14, the inclined surface of the core removal portion 55 aids in removing the drill core. The guide portion 54 is flush with the cutting element 14 and forms during drilling a guide for the cutting elements 14, parallel to the axis of rotation 22, the guide portion 54 has a length m. Alternatively to the guide on the inside of the drill bit 10, the guide section may be arranged on the outside or on the outside and inside. The length m of the guide portion 54 is less than 4 mm. A guide section smaller than 4 mm does not obstruct the supply of a cooling and purging medium, or at least does not substantially hinder it.

The outer plug-in element 15 comprises an outer lateral surface 56, an inner lateral surface 57 and an end surface 58. At the transition from the annular section 13 to the outer plug-in element 15 there is an annular stop shoulder 59. In the embodiment shown in FIG. 4A, the outer plug element 15 additionally has an oblique outer surface 60, the diameter of which increases in the direction of the cutting elements 14.

FIG. 4B shows the cutting section 11 and the drill shaft section 12, which are connected via the plug-in rotary connection 24, wherein the pin element 25 is arranged in the securing area 48 of the transverse slot 43. In the connected state of the Bohrschaftabschnitt 12 is located with the end face 33 against the stop shoulder 59 of the cutting section 1 1. Between the inner circumferential surface 57 of the outer pin member 15 and the outer surface 31 of the inner plug element 17 there is a radial gap 61. The difference is 8 _r a _d iai internal between the inner diameter du of the outer pin member 15 and the outer diameter d _{2, A} of the Plug element 17 for all diameters greater than 0.1 1 mm. The length l _{2 of} the inner plug-in element 17 is greater than the length of the outer plug-in element 15, so that an axial gap 62 of the gap width 5 _aX i _a i forms between the end face 58 of the outer plug-in element 15 and the stop shoulder 34 of the inner plug-in element 17. By the radial gap 61 and axial gap 62 it is ensured that the end face 33 of the inner plug element 17 rests against the stop shoulder 59 of the outer plug element 15 and when drilling a defined force transmission from the drill shaft section to the cutting section.

FIG. 5 shows a further embodiment of a drill bit 70 according to the invention with a cutting section 71 and a drill shaft section 72. The drill bit 70 differs from the drill bit 10 in that an additional molding in the axial direction is provided. is provided conclusive connection, which makes an unintentional release of the cutting portion 71 from the drill shaft portion 72 difficult.

The cutting section 71 has, in addition to the outer plug element 15 and the slot-shaped recesses 26, a first connection device 73, and the drill shaft section 72 has, in addition to the inner plug element 17 and the pin elements 25, a second connection device 74. The first connecting device 73 comprises a groove 75, which is arranged on the inner side 57 of the outer plug-in element 15. The second connecting device 74 comprises a nose 76, which is arranged on the outer side 28 of the inner plug-in element 17 and extends radially outward. In the connected state of the drill bits 70, the lug 76 and groove 75 form in the axial direction, i. in the boring direction 23, a positive connection between the cutting portion 71 and the Bohrschaftabschnitt 72. The cutting portion 71 is secured by means of the nose 76 and groove 75 against removal of the Bohrschaftabschnittes 72 from the cutting portion 71.

The nose 76 is disposed in the axial direction between the pin members 25 and the drill shank 16. In order to remove the Bohrschaftabschnitt 72 from the cutting portion 71, a force is exerted on the end face of the outer plug element 15 by means of a tool. By the force of the resilient portion of the outer plug element 15 is deflected and the positive connection between the nose 76 and groove 75 can be solved. The greater the distance of the nose 76 to the end face 33 of the inner plug-in element 17, the greater the deflection of the resilient portion. The groove 75 is annular and arranged in a plane perpendicular to the axis of rotation 22. An annular groove, which is arranged in the axial direction at the level of the slot-shaped recesses 26, supports the spring action of the portions of the outer plug element 15 between the slot-shaped recesses 26th

The holding force that can withstand the tab 76 and groove 75 can be adjusted via the geometry of the tab 76 and groove 75. The engagement of the nose 76 in the groove 75 should be as comfortable as possible for the operator, an inclined surface facilitates the snapping. As a geometry parameter for adjusting the holding force, for example, the radial height of the nose 76, i. the height in the radial direction, the contact surface between the nose 76 and the inner plug-in element 17 and the angle of inclination.

Claims

claims

1 . A drill bit (10; 70) rotatable in a rotational direction (21) about an axis of rotation (22), comprising:

A cutting section (1 1, 71) having a ring section (13) attached to a first section

End is connected to one or more cutting elements (14) and at a second end a first plug element (15), and

■ a drill shaft section (12; 72) with a cylindrical drill shaft (16) which has a second plug element (17) at an end facing the cutting section (1 1), the plug elements (15, 17) being parallel to the axis of rotation in a plug-in direction (22) form a plug connection and additionally connectable via at least one pin element (25) which is movable into at least one slot-shaped recess (26),

characterized in that the slot-shaped recess (26) has a connecting slot (44) and a transverse slot (43) with a driving area (47) and a securing area (48), wherein the driving area (47) in one, the direction of rotation (21 ), side of the connecting slot (44) and the securing area (48) on one, the direction of rotation (21) facing away, side of the connecting slot (44) with the connecting slot (44) is connected.

2. drill bit according to claim 1, characterized in that the height (h) of the connecting slot (44) parallel to the axis of rotation (22) is at least 10 mm.

3. drill bit according to claim 2, characterized in that the height (h) of the connecting slot (44) parallel to the axis of rotation (22) is not greater than 13 mm.

4. drill bit according to claim 1, characterized in that the transverse slot (43) parallel to the axis of rotation (22) has a lower distance (A _{1 u} ) to the ring portion (13) of at least

3 mm.

5. drill bit according to claim 4, characterized in that the lower distance (A _{1 u} ) of the transverse slot (43) to the ring portion (13) is not greater than 5 mm.

6. drill bit according to claim 1, characterized in that the pin elements (25) perpendicular to the rotation axis (22) have a pin height (H _z ), wherein the pin height (H _z ) between 68% and 89% of the shaft width (b) of the drill shank (16) is.

7. drill bit according to claim 6, characterized in that the pin elements (25) are formed in a circular cylindrical shape with a pin radius (R _z ), wherein the pin radius (R _z ) is between 2.5 and 5 mm.

8. Drill bit according to one of claims 6 to 7, characterized in that the width (Bi) of the driving area (47) is not smaller than the pin radius (R _z ) plus 1 .5 mm.

9. drill bit according to claim 8, characterized in that the width (bi) of the driving area (47) is not greater than the pin radius (R _z ) plus 3 mm.

10. Drill bit according to one of claims 7 to 9, characterized in that the width (Bi) of the driving area (47) is greater than the width (B ₂ ) of the securing area (48).

1 1. Drill bit according to one of claims 7 to 9, characterized in that the width (Bi) of the driving area (47) and the width (B ₂ ) of the securing area (48) coincide.

12. drill bit according to claim 1, characterized in that the first plug-in element as an outer plug element (15) with a stop shoulder (59) and the second plug element as an inner plug-in element (17) with an end face (33) is formed.

13. drill bit according to claim 12, characterized in that the at least one pin element (25) on the outer side (27) of the inner plug-in element (17) is fixed and the outer plug-in element (15) having at least one slot-shaped recess (26).

14. drill bit according to one of claims 12 to 13, characterized in that the length (l ₂ ) of the inner plug-in element (17) is greater than the length () of the outer plug-in element (15).

15. drill bit according to claim 14, characterized in that the length () of the outer plug element (15) is at least 18 mm.

16. drill bit according to claim 15, characterized in that the length () of the outer plug element (15) is not greater than 28 mm.

17. drill bit according to claim 1, characterized in that the outer and inner plug element (15, 17) are annular, wherein the difference (6 _rad iai) between an inner diameter (du) of the outer plug element (15) and an outer diameter (d _{2, a} ) of the inner plug-in element (17) is greater than 0.1 1 mm.

18. Drill bit according to claim 17, characterized in that on the outer side (27) of the inner plug element (17) three or more pin elements (25) are fixed and the outer plug element (15) has three or more slot-shaped recesses (26), wherein the number of recesses (26) is greater than or equal to the number of pin elements (25).

19. drill bit according to claim 1, characterized in that the annular portion (13) has a guide portion (54), wherein the guide portion (54) parallel to the longitudinal axis (22) flush with an outer edge (41), an inner edge (42) or at an outer and inner edge (41, 42) of the cutting elements (14) connects.

20. Drill bit according to claim 19, characterized in that the length (m) of the guide portion (54) parallel to the axis of rotation (22) is less than 4 mm.

21. Drill bit according to claim 1, characterized in that on the outer side (24) of the inner plug element (17) a nose (76) is arranged and the outer plug element (15) has a groove (75), wherein the nose (76) and groove (75) form a positive connection in the connected state in the axial direction.

22 drill bit according to claim 21, characterized in that the nose (76) in the axial direction between the pin elements (25) and the drill shank (16) is arranged and the groove (75) in the axial direction at the level of the slot-shaped recesses (26). is arranged.

23. Drill bit according to claim 22, characterized in that the groove (75) is annular and is arranged in a plane perpendicular to the axis of rotation (22).