DE2354123A1 - Small diameter boring tool - incorporates spiral swarf channel in cutting plate and collet - Google Patents

Abstract

Boring tool for working holes with a small diameter, with a circular cross sections shaft, comprising a fixture and a collet part of the front free end of which a cutting plate made of hard metal is fitted, the cutting point of which protrudes sideways over the collet. The cutting plate with the exception of its sideways protruding outer cutting point is completely contained within the circular cross section of the collet, and both collet and cutting plate have a semi-circular shaped cross-sectional swarf channel winding in the rotary and advance directions. The top surface of the swarf channel is ground, and its pitch angle is preferabl 75 deg. The swarf channel radius is between 0.4 and 0.6 of the collet radius.

Description

PATENTANWÄLTE 89 Augsburg-GSggingen 22, October 29 * 1973

yon-Eichendorff-Strasse 10

dr., ng. ELIEBAU _Un , _Br2 " _I ", e.ffi / w κ 9010, κ 9055

DIPL. ING. G. LIEBAU (please specify when replying)

for characters

Steel holder and tool factory

Sobert Breuning GmbH

7122 Besigheim / ^{; l} . . .

Boring tool for machining Small diameter holes

The invention relates to a boring tool for machining of bores with a small diameter, with a shank of circular cross-section, consisting of a clamping end, a neck part at the front end of which a cutting plate made of hard metal or the like is arranged, the cutting tip of which protrudes laterally over the neck part.

With known boring tools of this type (see brochure of the applicant "KOMET boring steel holders and internal machining steels" IB 0/69/5 W) is at the front end of the neck part with a head enlarged in diameter compared to this neck part. a laterally protruding bevel; intended. on this rabbit is soldered to a hard metal plate. This training was chosen so that there is sufficient space between the neck part, which is tapered in diameter, and the inner wall of the bore large space remains through which the spooks escape can. Due to the tapering of the neck part opposite the head part or the clamping part is the boring tool considerably weakened «This weakening makes itself particularly noticeable in bores with a very small diameter, because even with small bores, the exit space may a certain minimum of

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Telegr.-Adr .: ElPATENT - Augsburg Posischedtkonio Munich 86510-809 Deutsche Bank AG Augsburg Kto.'Nr. 08/34

"- - - Bank code 720 700 01

Do not fall below approx. 2 mm so that the chips can still emerge without interference. One can therefore use the diameter ratio Do not make it proportionally between the hole and the neck part, but it must be in the area of the small Bores the proportion of the exit gap can be considerably larger than with large bores. If the exit is too low The gap between the holes results from chips scratched bore walls with unusable surfaces, wedges from Chips between the neck part and the bore, which lead to a bending of the neck part with the result of scoring and lead to changes in diameter. In addition, there is also chip jamming with clump formation, which often breaks the cutting edge have as a consequence.

The invention is based on the object of a boring tool to create small diameter bores of the type mentioned, which is particularly stable and a perfect chip evacuation is guaranteed.

This is achieved according to the invention in that the cutting plate, with the exception of its laterally protruding outermost cutting tip completely within the ice cross-section of the neck part is arranged, and that the neck part adjoins the cutting plate with a and feed direction has a coiled chip channel with a semicircular cross-section.

This training allows the diameter !? of the neck part as big as possible. The diameter can be made practically just as large as the diameter the hole to be machined, since the chip channel is used for chip evacuation and between the neck part and the inner wall of the hole only so much space has to remain that the neck part does not scrape the inner wall. The cutting edge needs this only very slightly cross-cut across the circle of the neck part

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to protrude * by; the semicircular cross-section of the Chip canal "promotes the formation of helically curved chips. The twisting of the chip canal in Dreh-'und ¥ o.rs.Ghubsriehtunghat, .indifferent whether that Workpiece, rotates and., The turning tool stands still or ■ vice versa, to. Consequence, -.that the inevitable touch of the Chips on the wall of the bore ■ triggers a friction, the force of which acts the chips, always along the coiled chip channel towards-. Helping to get the exit out of the meeting far away. ·;

The turning tool according to the invention is advantageously designed in such a way that the helix of the chip channel extends over a maximum pitch of one third. This will make the greatest possible. Stability at, b _; ester chip evacuation achieved that. especially when the boring machine is arranged horizontally: A horizontal arrangement of the boring tool with a horizontal feed direction is common on lathes and boring machines. In the machining of small holes, the workpiece ¹ and the Wei'k- rotates .in the, usually, _s. stuff stands / still ;. (Lathes, turret lathes, automatic machines). It usually finds the. Chip separation in a horizontal plane going through the hole axis, instead of .. In such a case, the chip channel begins with a horizontal course_and then turns downwards with more and more gradient, whereby the end of the chip channel is arranged outside the hole pointing downwards. so that the chips are thrown through with support. Gravity can fall out of the chip canal. In the case of series work with always the same bore dimensions, there is the possibility of. the slope of the. Design the chip channel in such a way that the chip channel is directed downwards precisely where it emerges from the workpiece when the volume = hole depth has been reached. .-; ..-

Further. Design options are identified in the d, en sub-languages. .

The invention will be described in the following, with reference to in the drawing illustrated embodiments explained in more detail.

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Show it:

Fig. 1 is a side view of the new boring tool,

Fig. 2 is an end view of the same,

FIG. 3 is a plan view in direction III of FIG. 1

Fig. 4 is a section along the line IY-IV of Fig. 1,

Fig. 5 shows a second embodiment, in the form of a so-called Ausdreheckstahles,

Fig. 6 is a side view of a third embodiment "example, FIG. 7 is a plan view of the same, FIG. 8 is an end view.

In the drawing, 1 denotes the entire boring tool, the shaft of which consists of a neck part 2 and a clamping part 3. The latter is used to clamp the boring tool. At the front end of the neck part 2 there is a triangular cutting plate 4 made of hard metal or the like. The cutting plate is provided with three cutting edges in a known manner and can be converted to ground after one cutting edge has been worn, so that a new cutting edge is brought into the operative position, which is possible by loosening and tightening the fastening screw 5. As can be seen in particular from FIG. 2, the cutting tip 4, with the exception of its laterally protruding outermost cutting tip 4a ', is arranged completely within the circular cross section of the neck part. The cutting tip takes this _o mm only half or less than the circular cross section vorzu- ^ω are. In the drawing this appears larger, but oo

- »the tool is shown there in about twice the size,

° Subsequently to the cutting plate 4, the neck part 2 - * a coiled chip channel 6 from the substantially semicircular one Cross-section, which can be seen in particular from FIG. The radius r of the chip channel cross-section should be about 0.4 to 0.6 of the radius R of the neck part 2.

If the first value is used, the greatest possible stability is achieved and if the second value is used, a "." largest possible Spanraxua. created. ■ '--.-'..-

As can be seen from Fig. 1, the helix extends of the chip channel a maximum of a third · slope, so that the chip channel 6 with a horizontal arrangement of the boring tool 1 is open at the bottom when the full drilling depth has been reached. This is in the 3 ig. 1 indicated by the dash-dotted line W. When the full drilling depth is reached, the Part of the boring tool lying to the left of this line in the hole, while the right-hand rope is outside.

With this arrangement it is also advantageous if the chip channel 6 at the rear end adjoining the clamping part 3 of the neck part 2 expires flat, as it is with the dashed line Line is shown. This ensures that the moment of resistance of the neck part is greatest at its rear end is where the greatest bending moment occurs. ' ./. -

To promote the removal of chips, "to the surface of the - 6 be smooth as possible \ Spankanaies" what is advantageously achieved by grinding.

A favorable chip evacuation is achieved if the angle of incline öC of the Spankanaies 6 about 70 ° to 80 ° preferably 75 ■ · amounts to.

The boring tool 1 'shown in FIG. 5 differs only because of the slightly different arrangement of the cutting insert 4. In such a known arrangement of the cutting plate, the tool is suitable for turning out blind holes and for facing.

Instead of the replaceable multi-edged cutting plate could possibly also the cutting insert in known Way to be soldered in. However, interchangeable ones are preferable Cutting inserts. / '. ■

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The boring tool according to the invention is particularly suitable for turning bores with; small diameter of about 8 "to 20 mm. Optionally, the inventive Training also for boring tools, which are intended for machining bores with larger diameters are suitable, but with such tools the stability problem is not so pronounced.

In the! Pig. 6 to 8 is another particularly advantageous; it Embodiment of the boring tool according to the invention shown. In this case, a chip breaker 8 is arranged on the upper side of the cutting insert 4. The one through the chip breaker 8 and the cutting plate 4 through fastening screw 5a holds both parts on the neck part 2. Then a chip channel 6 is provided on the chip breaker 8 and the cutting plate 4, the formation of which corresponds to that of the corresponds to previous embodiments.

The chip breaker extends to just above the cutting tip 4a and points at its point facing the cutting tip The longitudinal edge 8a running in the axial direction has an axially parallel edge to the cutting insert 4 and to the cutting tip 4a open chip breaker channel 9. As with the dashed Lines in FIGS. 6 and 7 can be seen, the cross section of the chip breaker channel 9 widens towards the chip channel 6. The chip breaker channel advantageously has an approximately semicircular one to the cutting plate 4 towards open cross-section. In order for the chips to pass through as unhindered as possible To ensure the chip breaker channel is between the longitudinal edge 8a and the cutting tip 4 over the entire length of the chip breaker channel extending slot is provided. The outer contour of the chip breaker δ is essentially semi-cylindrical with a radius which corresponds to the radius R of the neck part 2. The face 8b of the chip breaker is opposite the cutting tip 4 by about 0.3 to 0.5 hue back.

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The chip breaker liat the task of the cutting tip 4a Sheared chip from the rake face of the insert is distracted upwards, breaking. This is done by that the upwardly deflected chip on the rear wall and the The upper side of the chip channel 8 abuts and is broken by the sharp deflection. The broken chip is from the The following chips are pushed further into the chip breaker channel -9 and then enter the chip channel 6, through which it then slips backwards out of the hole in the workpiece. By dividing the separated chip into individual short pieces is prevented. that the otherwise helically shaped chips in the chip channel 6 rears up and then in some way at the hole x ^ and rubs or pulled between the bore and the turning tool will. The cross section of the chip breaker channel, in particular the distance between its top and the insert surface is depending on the feed rate or chip thickness for boring tools, which are intended for a bore diameter between 8 and 20 im., approx. 0.5 to 1.5 T & m «« Te larger than the Yorschub or the chip thickness, the greater it must be Be distance. ..

BQ 9.8.19 / 051 1

Claims (12)

Expectations {i. ! Turning tool for machining bores with -small diameter, with a circular cross-section shaft, consisting of a clamping and a neck part at the front free end of which a cutting plate made of hard metal or the like is arranged, the cutting tip of which protrudes laterally beyond the neck part, characterized in that the cutting insert (4) with the exception of its laterally protruding outermost cutting tip (4a) completely within the circular section of the neck part (2) is arranged, and that the neck part (2) adjoining the cutting plate (.4) one in the direction of rotation and Yorschubrichtung coiled chip channel (6). rait has a semicircular cross-section. 2. Tool according to claim 1, characterized in that that the spiral of the chip channel (6) extends a maximum of a third pitch. 3- Tool according to claim 1, characterized in that it is marked ei c h n e t that the surface of the chip channel (6) is ground is. 4. Tool according to claim 1, characterized in that that the pitch angle (). of the chip channel (6) is about 70 to 80, preferably 75. 5. Tool according to claim 1, characterized in that that the Eadius (r) of the chip canal (6) is about 0.4 to 0.6 of the Eadius (E) of the neck part (2). ■ - 9 r- 5 0 9 8 19/0511 6. Tool according to claim 1, characterized ge k e η η ζ ei ehnet that the cutting plate (4-). in on in a known manner provided with several cutting edges and can be implemented or replaced. " 7 · tool according to claim 2, characterized geke NN- \ ei ζ η ch et that the chip channel (6) terminates at the rear of the clamping part (3) adjoining the end of the neck part (2) flat. 8. Tool according to claim 1, characterized in that g e k e- η η draws that on top of the insert (4-) a chip breaker (8) is arranged, which extends to just above the cutting tip (4-a) and on its longitudinal edge (Sa) facing the cutting tip / running in the axial direction ″ an axially parallel edge extending, to the cutting plate and to the cutting tip open ■ has chip breaker channel (9). 9 · tool according to claim 8, characterized; ^g: ek / e NNZ ei ch η et, that the cross-section of the chip 'breaker channel (9) expands them to the chip channel \ (5) towards, 10. Tool according to claim 8 or 9, characterized in that g "e fc e η η, that the chip breaker channel (9) has an approximately semicircular cross-section. Ί1..Tool according to claim 8, 9 or 10, characterized ge t that between the long edge (8a) and the cutting plate '(4) one over the whole Length of the chip breaker (B) extending slot (10) is provided. 12. Tool according to claim 8, characterized in that g e k e η η that the outer contour of the: chip breaker (8) is substantially semi-cylindrical with a Radius that corresponds to the radius (R) of the ^ neck part./(2). BO 9 8 19/0511 \ *