Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B51/00—Tools for drilling machines
  • B23B51/009—Stepped drills
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B2251/00—Details of tools for drilling machines
  • B23B2251/60—Drills with pilots
  • B23B2251/603—Detachable pilots, e.g. in the form of a drill
  • B23B2251/606—Detachable pilots, e.g. in the form of a drill being a twist drill
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B2260/00—Details of constructional elements
  • B23B2260/138—Screw threads

Definitions

• the invention relates to a drilling tool, in particular a precision drilling tool for introducing primarily closely tolerated holes with preferably large L / D ratio in metallic materials, according to the preamble of claim 1.
• Drilling tools of the kind described in the opening paragraph which are often made of high-strength materials, e.g. HSSE or solid carbide (VHM) must, in order to be economically successful, characterized by an extremely long service life with high cutting performance and dimensional accuracy of the holes to be produced with it.
• the drill tip is designed so that the main cutting machined the workpiece to nominal diameter.
• the invention is therefore based on the object, a drilling tool of the type described above and thus a To provide allowed device that or at reasonable manufacturing cost is characterized in that it is able to produce holes of high quality with better dimensional stability, even with long service life of the tool.
• the cutting part is arranged in a smaller diameter Wendelnut training part with a running along at least one spiral lug assembly upstream on its side facing the drill bit either in a core drill part - for drilling in full - or in a core drilling guide section - Boring an existing core hole - passes, the Wendelnut- training part can be used to generate the feed force.
• the cutting part of the drilling tool is thus no longer subjected to compression, but pulled into the workpiece, whereby the tool not only shatterproof, but also dimensionally stable.
• the tendency of the drilling tool to vibrate is considerably reduced, which is especially true when drilling relatively deep holes, i. of holes with a high L / D ratio has a positive effect on the precision and surface finish of the hole.
• the Wendelnut training part can be executed and designed in a variety of ways. All that is decisive is that it can exert an axial feed force on the drilling tool during machining of the workpiece, ie, when the drilling tool engages in the workpiece while performing a rotational movement by the teeth of the helical lug arrangement extending with the workpiece. That part of the drilling tool which lies between the shank and the helical groove forming part is relieved of the feed force and thus no longer subjected to an upsetting force.
• the depth with which the lug arrangement of the helical groove forming part engages in the material of the workpiece is material-dependent and can be varied within wide limits.
• a particularly advantageous use of the drilling tool according to the invention is obtained with the device according to claim 19.
• the drilling tool can then be stabilized particularly well and secured against upsetting vibrations caused by compression force, when the control device is capable of acting on the tool holder on the drilling tool feed force in Depending on the speed of the drilling tool and the slope of the introduced from the lug assembly in the workpiece coil to be set so that it is below an adjustable limit, which can be lowered to zero.
• the tool can be used for drilling in full.
• a variant of the embodiment of the Wendelnut- training part is the subject of claims 2 to 4.
• the helical groove-forming part is equipped with a helical running lug arrangement which works by machining.
• This embodiment has the advantage that the drive power of the tool can be kept very small.
• the Wendelnut- training part this is formed by a Gewindeschneidteil.
• the cutting lug helix can be designed to be single or multi-threaded. Notwithstanding a conventional design of the threaded cutting lugs, an asymmetrical cross-sectional configuration of the cutting lugs, quasi in the manner of a sawtooth profile, can be provided. - A -
• the flute lying between the cutting lugs continues according to an advantageous development in the core drill part or in the core bore guide section and / or in the cutting part.
• the flute can be guided with substantially the same depth from the core drill part or core bore guide section to the cutting part.
• the helical groove-forming part may also be formed by a non-cutting working helical groove molding. In this case, then a helical extending lug arrangement on Bohr-. Tool formed.
• the material of the workpiece is made to flow, wherein the pressure studs dig preferably deeper with increasing axial retraction of the drilling tool into the workpiece in the workpiece.
• the pressing lugs which have penetrated the full depth into the workpiece, are supported on the workpiece in the axial direction and thus produce, under the action of the rotational movement on the drilling tool, the axial feed force with which the drilling tool is drawn into the workpiece in this variant as well.
• the shaft and the drill part which is located between the tool holder and the helical groove-forming part, only one guide function is transmitted, at the same time a discharge of the feed force occurs.
• the design of the spiral groove molding there is a great creative freedom. For example, if it is equipped with a polygonal cross-section, the drive power is reduced.
• the retraction movement of the drill tool into the workpiece can be further reduced when the helical groove forming member is provided with a gate.
• a gate In such a gate, the radial extent of which increases the production of the helical groove serving tool lugs in the axial direction towards the drill shank towards gradually. In this way, the tool lugs penetrate only gradually into the wall of the predrilled core hole.
• the gate is advantageously adapted in terms of its geometry to the radial extent of the tool studs, depending on the material of the workpiece and / or the tool or its coating.
• the inventively designed drilling tool can have a variety of applications. It can be used, for example, as a single lip drilling tool, i. be designed as pronounced deep hole drilling tool with and without internal cooling. It may just be grooved or equipped with helical flutes. The tool can also be used to drill pre-drilled holes. In this case, a core bore guide section adjoining the helical groove forming part, which may have a small axial extent, is sufficient.
• a particularly advantageous field of application of the tool according to the invention is precision deep hole drilling, in which holes of the smallest diameter are introduced into a workpiece over a depth of, for example, up to 100 times the nominal bore diameter with a narrow bore tolerance of H ⁇ to H7.
• the cutting part can also consist of several parts.
• the cutting part is composed of several parts, advantageously the separation of the cutting part takes place at a short axial distance behind the main cutting edge for producing the nominal drilling diameter.
• the drill bit facing the cutting part can then be formed of a high strength material such as solid carbide or a cermet material, while the rest of the cutting part is formed with shaft of a different material, preferably a material with high dimensional stability.
• This component of the cutting part has invented In accordance with only the function of guiding the drill bit facing cutting part with preferably integrally formed Wendelnut- training part and core drill part and to transmit the drive torque on this.
• leaner cutting part relieved of feed force 'conditional compression forces and set by the heat generated by the helical groove forming part feed force under train, whereby the tendency is greatly reduced to vibrate even at very long cutting part. This gives the designer of the tool more freedom for the design of the flutes, which ultimately benefits the increase in dimensional stability and chip removal.
• the drilling tool can also be designed as a multi-bladed tool, such as a three-knife trimmer, which has the advantage that it can be drilled with the tool into the solid, without risking a running of the tool.
• the axial length of the helical groove forming part can be varied and depends on various factors such as pitch of the helix, height of the lug assembly, material of the workpiece and tool, cutting speed and / or feed of the tool. Good results can be achieved, for example, with a geometry according to claim 11.
• the axial length of the core drill part can vary within wide limits. It may be limited to a level required to form the drill bit, plus a small axial dimension for the formation of a cutting corner and a short knife edge. Over the axial length of the core drill part, the guidance accuracy of the tool can be controlled well. To drill in full has an axial length as proved to be greater than 1.5 times the amount of the core diameter.
• the at least one flute of the drilling tool can be rectilinear but also helical, in each of the three functional sections of the core drill part or core bore guide part, helical groove forming part or cutting part or a cutting part carrier carrying this cutting part.
• the individual components of the drilling tool can - depending on the specific requirement - i.
• Material of the workpiece and required cutting performance - different materials can be used.
• the highly stressed components consist of a hard material, such as, for example, solid carbide or a cermet material, wherein these sections can additionally be provided with a suitable coating, in the embodiment as a hard material layer and / or soft material layer.
• the material and / or the coating is selected according to the specific stresses of the respective drill bit section according to known criteria, so that this aspect need not be discussed separately here.
• the above-outlined drilling tool according to the invention is advantageously operated with a device which is able to absorb the tool shank tensile and pressure resistant and having a control device with which the force acting from the tool holder on the drilling tool feed force as a function of the speed and the slope of the introduced from the lug arrangement in the workpiece coil is adjustable.
• the adjustability is preferably such that the force acting from the tool holder on the drilling tool feed force is below an adjustable limit. This limit can reach zero or even negative value.
• FIG. 1 shows a perspective view of a first embodiment of the drilling tool according to the invention
• FIG. 2 shows a side view of the tool according to FIG. 1;
• FIG. 3 shows, on an enlarged scale, a plan view as seen along the arrow "III" of the tool
• Fig. 4 is a schematic side view of a second embodiment of the drilling tool according to the invention.
• reference numeral 10 designates a drilling tool, which can be used as a precision drilling tool for the introduction of primarily closely tolerated holes with a large L / D ratio in metallic materials.
• the drilling tool has, for example, a nominal diameter D of 12 mm, which is produced, for example, with the tolerance h7.
• the total length LG of the cutting part of the drilling tool 10 is a multiple of the nominal diameter D and is set for example to about 100 mm.
• the reference numeral 12 denotes the main cutting edges, with which the bore to be produced is machined to finished size.
• the actual cutting part of the drilling tool is denoted by 14 and passes into a shaft 16 ', which is rotatably and axially fixed in a tool holder, not shown.
• the cutting part 14 are preceded by two other functional sections. Initially, the cutting part 14 turns into a helical groove forming part 18 kept smaller in diameter.
• the diameter D18 of the helical groove forming part 18 is smaller than the nominal diameter D by a small amount, and it has a lug arrangement 20 formed on at least one helical line 22 runs with a helical pitch SW.
• the helical groove forming part has, for example, a diameter D18 in the range between 8 and 11 mm.
• the helical pitch SW is selected as a function of the respective processing parameters, which will be explained in more detail later.
• the Wendelnut- training part is designed similar to the cutting part in a tapping tool, ie along the spiral line 22 extending lugs 20 are separated by two flutes 24 and the lugs 20 are less pronounced towards the top of the drilling tool, ie the Wendelnut- training part 18 has on the side facing the drill bit a gate 26, which merges either continuously or via a small step in a core bit 28 with a diameter D28 and a length L28.
• the diameter D28 may correspond, for example, to the core diameter of the helical groove forming part 18, ie, the thread cutting part 18.
• the axial length L28, as well as the axial length L18 of the helical groove forming part 18, are determined according to the respective conditions of use, ie according to the required cutting speed and / or the material of the tool and / or the material of the material to be machined.
• the core drill part 28 has a drill tip 30 with a bevel, which is preferably designed so that the drilling tool is suitable for drilling in full. Such connections are well known, so that is not discussed here in detail.
• the core drill part is equipped with two main cutting edges, measures are preferably taken to keep the length of the cross cutting edge as small as possible. If three main sheaths are provided, the transverse cutting edges resulting from the grinding can be used as the centering point.
• the tool shown in FIGS. 1 to 3 has such a bevel that the main cutting edge 32 merges into a cross cutting edge 34 with a positive rake angle, which is achieved by the attachment of a special recess 36. With 38 openings openings of internal coolant / lubricant channels are designated, which open into main open spaces 40.
• the drilling tool 10 may be formed in one piece or several pieces.
• a material is preferably either tool steel, such as HSS or HSSE or a hard material such.
• solid carbide, or a cermet material or a ceramic material use.
• the parts 14 and / or 18 and / or 28 are soldered via preferably interlocking surfaces.
• the cutting part 14 may be divided into several sections, preferably at a predetermined axial distance A from the main cutting edge 12th
• the mode of operation of the drilling tool 10 according to the invention will be explained in more detail below.
• the drilling tool 10 is clamped with its shaft 16 in a tool holder, not shown.
• the clamping takes place in such a way that not only a rotationally fixed entrainment of the drilling tool 10 is ensured, but also a safeguard against axial tensile load.
• a quick-change threaded chuck with internal cooling according to article no. 4342 from Guhring OHG can be used.
• the tool is retracted into the material to be machined at a predetermined stepping speed and given feed rate, the core bit part 28 first being activated as soon as the core bit part 28 has penetrated the material by the dimension L28, the gate 26 starts with the lugs 20 of the helical groove.
• Training part 18 to work.
• the machine tool in the tool holder, the drilling tool 10 is clamped, exerts at this moment nor a feed force on the drilling tool 10.
• the feeding force of the drilling tool 10 is increasingly taken over by the helical groove forming part 18 in which the lugs 20 screw into the formed helical groove.
• the lug assembly braces against the helix and completely absorbs the feed force.
• the cutting part 14 since the cutting part 14 is subject to a tensile force, the tendency of the drilling tool 10 to vibrate is effectively suppressed, with the result that the bore can be manufactured with high precision and high surface finish.
• About the shape of the lug assembly 20, ie on the geometry of the studs and / or the pitch SW of the helical line 22 can be generated by the helical groove-forming part 18 Feed force in cooperation with the speed of the drilling tool 10 control.
• the speed is adjusted so that the feed force acting on the drilling tool from the tool holder is below an adjustable limit value when the helical groove forming part 18 is operating. This limit can be zero or even less than zero.
• the Wencielnut-training part 18 as non-cutting converter for example, after the manner of a thread rolling with and without lubrication, be formed.
• the helical groove molding may have a polygonal cross section.
• the drilling tool can be equipped in the region of the helical groove-forming part with outlet openings for the coolant / lubricant.
• the flutes 24 are formed in the embodiment shown in FIGS. 1 to 3 helically. However, they can equally be straightforward. Also, the number of flutes vary.
• the drilling tool of Figs. 1 to 3 is suitable for drilling both through holes and blind holes.
• the drilling device can be operated in two ways. In one case, the tool spindle can be stopped upon reaching the desired drilling depth and then rotated backwards. However, it is equally possible to let the drilling tool continue to rotate upon reaching the desired drilling depth, but to lock the feed device.
• the helical groove forming part 18 cuts the material in the region of the length L18 at this moment, whereupon the drilling tool 10 can be moved out of the bore.
• the drilling tool 10 is provided with a cutting part 14 whose axial length is greater than three times the nominal diameter D. An exemplary embodiment of the drilling tool will be described below with reference to FIG. 4, in which this axial length is substantially greater, even greater than ten times. D is.
• the drilling tool 110 is designed as a pronounced deep hole drilling tool.
• a cutting part 114 is rotationally and axially fixedly received in a clamping sleeve 113.
• the cutting part 114 is different from those of the drilling tool 10 of Figs. 1 to 3 in that it has a single flute 124 and that it is composed of two elements 114-1 and 114-2.
• the interface between the parts 114-1 and 114-2 is indicated by the dotted line 117.
• the bit-facing portion 114-2 of the cutting portion 114 carries the major cutting edge 112. This may be a single major cutting edge used in single-lip drilling dies with downhole applications. Such single-lip drilling tools can produce bores with a nominal diameter of less than 1.2 mm for drilling depths of up to 160 mm. Correspondingly small is the diameter of the cutting part section 114-1. However, the ' cutting segment 114-2 can also be equipped with a cutting insert, which is advantageous for larger nominal diameters, for example of more than 15 mm. Cutting member segment 114-2 is - as in the drilling tool 10 of Figure '1 to 3 -. In a helical groove forming part 118 via, to which a core drill part connects 128th The illustration according to FIG.
• the statements on the embodiment according to FIGS. 1 to 3 apply, so that a more detailed description can be omitted here. It can be seen from the illustration that the parts 128, 118 and 114-2 are in one piece.
• a material for this component is preferably a high-strength material, such as.
• HSSE or solid carbide used.
• cermet or ceramic materials can also be used.
• a material having a low tendency to vibration is preferably used for the cutting part segment 114-1. Also in this area can be worked with tool steel, but also with hard metal, but which differs in terms of its structure from the carbide of the cutting section segment 114-2.
• the tool according to FIG. 4 operates in the same way as that of FIGS. 1 to 3. It can be seen that, as a result of the design according to the invention, when the helical groove forming part 118 generates the feed force of the tool, the cutting part segment 114- 1 no longer has to transfer significant pressure force, but only still assumes a leadership function for the cutting segment 114-2. The tool thus works less fibrations and accordingly more accurate. Of course, further deviations from the previously described embodiments are possible without departing from the spirit of the invention.
• the tool also does not necessarily require a core bit 28, 128 in the embodiment of Figures 1 to 4. Rather, this core bit 28, 128 can be extremely shortened axially and next to a drill bit with bevel only the cutting edge of the main cutting edge and also axially on a Minimum measure shortened secondary cutting edge.
• the core drill part can also be completely eliminated if the tool is used for boring a core hole that has already been completed.
• a core drilling guide section via which the tool is centered when entering the core bore occurs.
• This core-drilling guide section can also be taken over by a section of the helical-groove-forming part that gradually tapers in the axial direction of the tool tip.
• the drilling tool 10, 110 can be operated with and without internal coolant / lubricant supply. Coatings are possible for the various sections of the drilling tool 10, 110, wherein these coatings can be selected from the following group either separately or in combination: TiAlN layer, TiCN layer, TiN layer, a soft layer (MoS '2). Layer) or a TiAlN / TiN multilayer coating. These layers can be constructed, for example, as described in the applicant's leaflet "Layers" with the printing note 114988 / 0704-11-22. Instead of the single-turn helical line 22, 122 shown in the figures, multi-turn helical lines can also be provided. The spiral line can also be interrupted several times.
• the invention thus provides a drilling tool, in particular a precision drilling tool for introducing primarily closely tolerated holes with preferably large L / D ratio in metallic materials.
• the drilling tool has a shaft rotatably and axially fixed in a tool holder and a cutting part with which the bore can be machined to final dimensions.
• the cutting part is preceded by a smaller diameter held Wendelnut training part having a lug assembly which extends along at least one coil.
• the helical groove forming part passes on its side facing the drill bit into a core drill part or a core bore guide section.

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• Mechanical Engineering (AREA)
• Drilling Tools (AREA)

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Cited By (2)

Citations (4)

• 2007
  • 2007-06-28 DE DE102007029826A patent/DE102007029826A1/de not_active Withdrawn
• 2008
  • 2008-03-13 WO PCT/DE2008/000431 patent/WO2008119320A1/de active Application Filing

Patent Citations (4)

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