DE102020005946A1 - Flow-optimized deep drilling tool - Google Patents

Abstract

Flow-optimized deep drilling tools from the field of single-lip drilling will be presented, which allow the use of interchangeable parts such as cutting inserts or guide strips in the previously accustomed areas without restricting the coolant supply, with sometimes even larger coolant channels or bores than is usual even in the so-called solid drill heads. This enables the necessary coolant throughput to be provided at a significantly lower pressure specification, which is relevant above all in the smaller diameter ranges, in which the energy requirements of the coolant pumps often far exceed that of the drill drive. Furthermore, two different peripheral shapes can be set on one and the same drilling tool by means of a targeted positioning of the diameter-determining guide strip and by means of a supporting surface on one side, which can be used alternately for different drilling tasks.

Description

Technical part:

Deep drilling tools are preferably used in task-related machine tools for drilling holes whose drilling depth is mostly much larger than the hole diameter. They are generally designed in such a way that a permanent flow of coolant causes the drill chips to be discharged uninterruptedly, so that repeated attachment or chipping can be omitted. Deep drilling tools are mainly used in the metal sector, but sometimes also in the non-metal sector.

Relevant state of the art:

Deep drilling tools have been known for a long time and are primarily named after the drilling process for which they were designed. The so-called single-lip drilling process (ELB process) is particularly suitable for drilling in the rather small diameter range, for which the one-sided cutting edge geometry of the drill heads gave it its name. Another typical feature of these drilling tools is the coolant supply inside through the drill pipe with transfer to the cutting area via channels in the drill head. The classic drill head usually has two bores here - with very small drill diameters, however, a kidney-shaped passage is more effective.

The possibility of using interchangeable parts in order to avoid soldering and unsoldering entire drill heads is, of course, very quickly limited in terms of diameter, especially since their positioning is functionally relevant and thus largely predetermined. You also come into conflict with the position of the cooling channels in the drill head. In particular, the position of the fastening threads, which is also specified, disturbs the straight passage, and so up to now it has often been content to only designate one cooling channel. It is obvious that the necessary coolant throughput can only be achieved with a significantly higher energy input.

With the T3-Bohrer® (combination tool with ELB elements / DE 10 2017 006 188.2 ) the problem in terms of interchangeable parts is directly comparable and is therefore also taken into account in this elaboration.

Task:

The invention is therefore based on the object of creating drilling tools that allow the use of interchangeable parts in the previously accustomed areas without restricting the coolant supply, with the total cross-section of the supply paths being increased as much as possible in terms of energy.

Disclosure of Invention:

This task is essentially solved by the fact that the cutting plane is no longer congruent with a flank of the chip space, and the entire chip space after the axial insert support is pivoted around the drilling axis to such an extent that there is still enough space for a second cooling channel after the diameter-determining guide strip . Since the chips move in a relatively orderly manner directly above the cutting insert in the direction of the drill pipe and only then become more and more confusing, a free sector of approx. 90° is sufficient at the beginning, which is then expanded to the previously proven cross-sectional shape after the cutting insert seat.

Examples:

1 shows the state of the art in the form of a typical single-lip drill with interchangeable parts. A drill head base body (10), a single through hole (11) for the coolant transport from the inside of the connected drill pipe (12) into the cutting area, an exchangeable cutting plate (13), a guide strip (14) opposite this and thus determining the diameter, and one underneath the guide bar (15) positioned on the cutting plate, which absorbs the main cutting pressure.

It can be clearly seen that the fastening screws (16) stand in the way of a second through hole, as is standard, for example, with so-called solid drill heads. Coolant and chips are fed back through a sector (17, 18) adapted to the drill pipe, the cross-section of which is many times larger than that of the feed bore, which results in a high and energy-intensive coolant pressure specification.

• Beim EL-Bohrkopf (20b) mit Wechselteilen (13, 14, 15, und 16) und angeschlossenem gesickten Bohrrohr (21b) sind nun trotzdem zwei Zuführkanäle (22c) gegeben, ermöglicht dadurch, dass der im Bereich der Schneidplatte vorhandene Spanraum (25b) nach der axialen Schneidplattenabstützung um ca. 30° bis auf die schon gebräuchliche und der Bohrrohrsicke nachempfundenen Kontur erweitert wird (28b). Und mithilfe additiver Fertigungstechniken können die Kanalquerschnitte sogar noch über den Vollbohrkopf-Standard hinaus erweitert werden (22d).

2 now shows the measures according to the invention for optimizing the flow cross sections:

• With the EL drill head (20b) with interchangeable parts (13, 14, 15 and 16) and connected beaded drill pipe (21b), there are still two feed channels (22c), which makes it possible for the chip space (25b) in the area of the cutting insert to after the axial insert support is expanded by approx. 30° to the contour that is already in use and is based on the bead of the drill pipe (28b). And with the help of additive manufacturing techniques, the channel cross-sections can even exceed the solid drill head standard (22d).

With the T3-Drill® (20a) with a connected round drill pipe (21a), a higher chipping performance can be assumed due to the greater torsional rigidity, which is why the free discharge sector is already expanded slightly beyond the center in the area of the cutting plate (13). (26). In this tool, too, the chip space (25a) is widened by a sector (27) after the axial cutting plate support and then reaches a size (28a) overall that is matched to the inside of the pipe in terms of cross-section. The inflow is further improved by partial flattening down to the tube outer diameter and transitions (23) to the cooling channels (22a, 22b) and flattening on both sides of the guide strips (24). Even taking into account a partially premature outflow through the backflushing channels into the interior of the drill pipe (22b), there is still around twice as much coolant available for the cutting area as compared to previous standard tools. Conversely, the necessary flushing can also be achieved with an even lower and thus further energy-saving pressure specification.

3 points to a positive side effect, in that a circumferential shape smaller (31) or larger than 180° (32) can be produced with the diameter-defining bar, which is now slightly below the cutting plane and ground asymmetrically (30), depending on the installation. The former usually has a positive effect on the diameter accuracy, the latter is preferably used in unfavorable spotting, overboring and boring situations. The reduction in the circumferential area of the bar is negligible, since the main load is taken up by the bar under the insert.

Advantages of the invention:

The most serious advantage is probably that, in comparison with solid drilling heads, despite the installation of exchangeable installation elements, the necessary flushing can be maintained without increasing the pressure specification and with the sometimes even larger flow cross sections, with even greater energy savings. After all, especially in the smaller drilling diameter range, the energy expenditure for the coolant side is usually even greater than for the machining itself.

It should also be mentioned that the modifications only affect the base body of the drill head, so that all wear and change parts are unchanged and can be used as before.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102017006188 [0004]

Claims (8)

Deep drilling tool, consisting of: a drill head base body (20a) with a round drill pipe (21a) connected at the end and front recesses with threaded holes for interchangeable parts such as cutting insert (13), guide strips (14, 15) and the associated screws (16), with at least two cooling channels to the cutting area (22a ) and facing the inside of the tube (22b), with two peripheral flattened areas reaching to the outer diameter of the drill tube and openings to the cooling channels (23), with flattened areas on both sides of the guide strips (24) and an approximately right-angled chip space (25a) in the area of the cutting insert. Deep drilling tool, consisting of: a drill head base body (20b) with a beaded drill pipe (21b) connected at the end and front recesses with threaded holes for interchangeable parts such as cutting insert (13), guide strips (14, 15) and the associated screws (16), with at least two cooling channels to the cutting area (22c ) and an approximately right-angled chip space (25b) in the area of the insert. deep drilling tool claim 1 , characterized in that the chip space (25a) in the area of the cutting plate (13) is pronounced beyond the central center (26). deep drilling tool claim 1 , characterized in that immediately after the axial support of the cutting plate (13), the chip space is expanded by a sector (27) up to an opening (28a) which corresponds in cross-section to that of the inside of the tube. deep drilling tool claim 1 , characterized in that the contours of all flow-through zones and transitions are fluidically designed with the help of additive manufacturing techniques. deep drilling tool claim 2 , characterized in that on the drill head base body (20b) the chip space (25b) after the axial support of the cutting plate (13) is adapted to the contour of the tube (28b). deep drilling tool claim 2 , characterized in that the cooling channels (22c) in the drill head base body (20b) are expanded beyond the circular shape to a permissible distance from the boundary contours of the recesses or threaded bores in cross section (22d) using additive manufacturing techniques. deep drilling tool claim 1 and 2 , characterized in that the guide strip (14) opposite the cutting plate (13) is positioned between the cooling channels in such a way that, with an asymmetrical bevel (30), either a so-called peripheral shape of 180° - x (31) or, with rotated installation, a peripheral shape of 180° + x (32) results.

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