DE202009012566U1 - gun drills - Google Patents

Abstract

Single-lip drill having at least one cutting edge formed on a drill head, which has at least one cutting edge, wherein the setting angle (κ _r1 ) at the outermost point (P1) of the cutting edge, which is closest to the circumference of the drill head, greater than 90 ° and the setting angle ( κ _r2 ) at the innermost point (P2) of the cutting edge which is closest to the drill center axis (A) is smaller than 90 °, characterized in that the at least one cutting edge (S) has a strictly convexly curved contour and that a point (P2) P3) of the convex contour which is located farthest in the feed direction, at a distance (E) is arranged to the periphery of the drill head, which corresponds to a fifth to a third, in particular a quarter of the Bohrdurchmessers (D).

Description

State of the art

The The invention relates to a single-lip bur after the genus of independent Claims 1 and 2.

Single-lip drills are used to drill holes in workpieces. Different types of single-lip drills are in the VDI guidelines VDI 3210 and VDI 3208 shown. Single-lip drills are mainly used for making relatively small diameter bores, which are predominantly in the range of 0.5 mm to 50 mm, but the drilling depth can be a multiple of the bore diameter. Typical values for the drilling depth are in the range of 20 times to 100 times the drilling diameter, but may also be above or below it.

Generally consist Einlippenbohrer from a drill head and a drill shank with a clamping end. At the drill head is at least one cutting edge formed, extending from the Bohrermittelachse to Bohrerumfang extends. Furthermore, arranged on the circumference of the drill head guide elements be provided. The drill head and drill shank are either positively or materially connected to each other or they are made in one piece. There is at least one in the drill shaft and drill head running channel, the drill head and at the clamping end has openings. Through this channel Coolant is pressurized from the chuck end fed, which emerges at the drill head and next to the cooling the cutting edge and the guide elements in particular the Task has, the resulting chips during drilling by a in the drill head and in the drill shank existing V-shaped chip removal groove purge.

gun drills are usually machine side at their clamping end recorded in a dedicated receptacle in a spindle and rotated by the spindle about the drill central axis. At the same time the tool is along its central axis with a defined feed per revolution to a workpiece emotional. The single-lip drill penetrates into the workpiece and at the cutting head arranged on the cutting edge, the material of the Parted and in the form of chips from the workpiece Workpiece separated. The resulting chips be by the coolant, which by at least one inside channel fed through the spindle is flushed out of the bore along a chip removal groove.

It is also possible, the workpiece rotation and / or to make the feed movement or the rotation and / or the feed movement in part by the tool and to Part to perform by the workpiece.

gun drills are preferably used to drill holes in workpieces that are not or not economically viable with other manufacturing processes can be produced. Often these workpieces are in large Series produced. Improvements leading to an increase in production speed are therefore generally desirable and even small improvements lead to significant savings at the production costs.

The Production speed of drilling tools is through the product from feed per revolution of the tool and the number of revolutions defined per minute and is generally referred to as feed rate designated.

A Limit for increasing the feed rate is In single-lip drills often given by the fact that the chips can no longer dissipate through the Spanabfuhrnut and it comes to a swirling chip.

Common and widely used cutting geometries, also known as standard probes, are for example in the VDI guideline VDI 3208 shown. In these standard bevels, the cutting edge is divided into two straight part-cutting edges, wherein the outer, adjacent to the circumference of the drill head, part-cutting edge has a setting angle greater than 90 °. Usually, the setting angle is in the range of 110 ° to 130 °. The inner, the Bohrermittelachse nearest lying, part-edge, however, has a setting angle of less than 90 °. This setting angle is usually in the range of 75 ° to 60 °. The setting angle is defined as an angle between the drill center axis and the tangent to the cutting edge. The part-cutting meet at the drill tip at a distance from the circumference of the drill, which usually corresponds to 1/5 to 1/3 of the drill diameter. These standard burrs are particularly easy to manufacture by the straight part-cutting and can be adapted to many different machining situations by varying the setting angle and the distance of the drill bit from the circumference of the drill head.

When machining particularly tough materials, however, a certain feed per revolution can not be exceeded with these standard bevels. With further increase of the feed, the formation of the chips becomes increasingly unfavorable, since they no longer break and become longer and therefore no longer able to be safely removed from the bore. By the un favorable shape of the chips, the chips between Chipabfuhrnut and bore wall can jam and it comes to a chip bank, whereby the tool can break and thereby the workpiece can be damaged or destroyed.

It was therefore tried, the resulting chips in such a way to influence that they can be dissipated safer. For example, the chips were tried in their width divide. For example, chip splitters were used.

One in the JP 59 196108 A1 described cutting edge of a drill has, according to an embodiment described therein, a notch, which is to act as a chip splitter. In another embodiment, a step is provided in the rectilinear cutting edge which has an undercut at a predetermined angle.

Furthermore, was tried by the use of chipbreakers or chipformers to achieve a defined chip breakage in order to get the chips in to limit their length.

One in the DE 203 21 368 U1 described cutting edge of a drill has according to an embodiment of a chip former with a positive rake angle, which should lead to the breakage of the chips.

at this known embodiments is intended by a limitation the chip in terms of its width or length a cheaper Removal of the chips are achieved. Especially for materials but with high toughness and high feed also shavings that arise when using such tools, Often an unfavorable shape, which in turn the disadvantages described above arise, namely a Chip accumulation in the chip removal groove with all the above mentioned Disadvantages. Furthermore, the production of such chip breaker requires or chipbreaker a considerable extra effort in the production, as for the production of such grooves or notches often additional grinding wheels must be used, on grinders for grinding or regrinding these Tools are usually not available.

Of the Invention is therefore the object of a Einlippenbohrer to convey a high feed rate at the same time unproblematic Removal of chips by the chip removal grooves allows and at the same time is particularly easy to manufacture.

These The object is achieved by that in the independent claims 1 and 2 specified characteristics solved.

Disclosure of the invention

The basic idea The invention is in a single-lip drill a cutting geometry which is particularly easy to make and at the same time to a particularly favorable shaping of the chips leads, which makes this particularly favorable let the bore dissipate.

The allow single-lip drill according to the invention especially one compared to the known single-lip drills much higher feed rate, which in an industrial Manufacturing a correspondingly higher production speed allowed. This allows more than twice as high feed rates as can be achieved with known single-lip drills.

The Improvements are made by the advantageous shaping of the drilling obtained chips. Become by the geometry of the cutting edge when cutting tensions introduced into the chips, so that These break even with tough materials and short chips arise. This is achieved with the inventive Single-lip drills achieve high process reliability. In particular, will a drill breakage, the destruction of the workpiece to be drilled would result, by avoiding constipation the chip evacuation groove reliably avoided.

The Therefore, single-lip drills according to the invention have Overall, significant advantages in use, especially in the industrial Series production by a single-lip drill with only two Part-cutting are not feasible.

simplistically In the further consideration it is assumed that the flow direction of the cut material perpendicular to each point of the cutting edge Setting angle at this point of the cutting edge is while the workpiece directed away in the direction of the chip removal groove.

The Cutting are shaped according to the invention in such a way that by the different flow direction of the chip to the different sections of the cutting edge stresses introduced into the chips be and by the convex shaped cutting edge or the convex arranged part cutting achieved as rigid as possible chip becomes. The introduced stresses with simultaneous stiffening the chips lead to exceeding the tensile strength of the material and thus the breakage of the chips. This will be achieved a separation of the chips, causing the chips be limited in their length.

A first embodiment of the invention provides that the cutting edge has a strictly convex curved contour. In this case, the cutting edge at the outermost part, the the circumference of the drill head is closest, an adjustment angle greater than 90 ° while they are at the innermost part closest to the drill center axis is, has a setting angle less than 90 °. Farther is provided that a point of strictly convex curved Contour that is furthest in the feed direction, at a distance is arranged to the circumference of the drill head, the 1/5 to 1/3 of the drill diameter equivalent. Convex in this context means that the single-lip drill viewed convex at its lower end viewed from the front in such a way that the increasing gradient starting from one negative value over a zero crossing to a positive one Value increases strictly monotonically and thus a lowest point of the convex Education exists, namely the point, the furthest is arranged in the feed direction. This point indicates the mentioned Distance from the drill diameter.

A sees another solution according to the invention in that the cutting edge has a substantially convex contour, by three or more part-cutting in the form of straight sections is approximated, wherein at least a first part-cutting edge at the outermost part, the circumference of the drill head is closest, an adjustment angle greater 90 °, and at least a second part-cutting edge at the innermost part closest to the drill center axis is, has a setting angle of less than 90 °, and wherein between the first and the second cutting edge S1, S2 at least a third cutting edge S3 is arranged.

Further Embodiments and developments of the invention Single-lip drills are the subject of the dependent claims.

A advantageous embodiment provides that the cutting edge in the having substantially convex contour approximated by exactly three part-cutting is.

A particularly preferred embodiment, in particular is easy to produce, provides that the three part-cutting are currently trained.

there is particularly advantageous provided that the at least three part-cutting Are tangents to a strictly convex curved contour, wherein the strictly convex contour is formed so that a point the contour located furthest in the feed direction, in a distance from the circumference of the drill head is arranged, the one Fifth to one third of the drill diameter corresponds. In this case, the strictly convex contour according to first embodiment of the invention in a sense approximated by tangents to this contour, here three tangents, d. H. three part-cutting, or even more than three Tangents, so more than three part-cutting, can be provided. Also Here, the convex contour is formed so that its slope of innermost to the outermost point increases strictly monotonously, d. H. starting from a negative value on one of the rotation axis nearest point to a positive value increases at a point closest to the circumference, wherein the slope passes through a zero crossing. Of the Zero crossing marks the point of the imaginary contour the furthest is located in the feed direction.

According to one very advantageous embodiment, in which three part-cutting are provided, it is provided that the first part-cutting outermost Part that is closest to the circumference of the drill head, a Setting angle greater than 90 °, and the second part-cutting edge at the innermost part of the Bohrermittelachse is closest, an adjustment angle has less than 90 °. The third part-cutting edge, which cuts between the two other parts is arranged, has a setting angle of 80 ° 100 °, in particular approximately 90 °.

The Length of the third part-cutting edge is preferably so it is equivalent to 5% to 20% of the diameter of the drill.

A particularly favorable shaping of the chips was in Practical experiments observed when the length of the third Partial cutting edge corresponds to 8% to 10% of the drilling diameter.

According to one advantageous embodiment, the three-piece cutting edge designed be that difference of the setting angles of each outermost first and innermost second part-cutting edge 15 ° to 90 °. In the range of an angle of 30 ° to 70 ° results In this arrangement, a particularly favorable influence chips that leads to chip breaking.

The Position of the intersection of the tangents to the cutting edge at the outermost point and innermost part of the cutting edge, as well as the size the setting angle of the outermost and innermost Part of the cutting edge depends on the material to be processed and its forming ability, the process parameters, the used cooling lubricant and other factors.

According to an advantageous embodiment it can be provided that the single-lip drill is composed of a drill head and a drill shank or that the drill head and the drill made of one piece. Alternatively, an exchangeable drill head can be provided.

Further Embodiments relate to the drill head made of hard metal may be and / or with a coating, for example one Hard material layer, can be provided. With these measures can significantly extend the service life of the single-lip drill become.

Further advantageous developments and refinements of the invention Single-lip drills are the subject of the following description.

drawings

embodiments The invention is illustrated in the drawings and in the following Description explained in more detail.

It demonstrate:

1 a single-lip drill according to the prior art;

2 a standard bevel of a single-lip drill according to the prior art;

3 a first embodiment of the cutting edge of a single-lip drill according to the invention;

4 a further embodiment of the cutting edge of a Einlippenbohrers invention and

5 a further embodiment of the cutting edge of a single-lip drill according to the invention.

Description of exemplary embodiments

1 shows a single-lip drill 10 with a cutting edge, as known from the prior art. The single-lip drill 10 contains a clamping end 11 for receiving the single-lip drill 10 in an in 1 Not shown drill chuck, and a drill shank 12 with a drill head 13 , and a rotation axis A. The drill shaft 12 and the drill head 13 are realized in one piece. In the drill shank 12 is at least one coolant channel 14 provided at the front end of the drill head 13 empties. That through the coolant channel 14 pumped coolant not only has the task of the drill head 13 to cool, but also serves to remove the resulting chips during drilling through a V-shaped chip removal groove 15 at the cutting edge 16 of the single-lip drill 10 begins and extends almost the entire length of the drill shaft 12 extends. At the circumference of the drill head 13 can at least one guide element 17 be provided.

2 shows a cutting edge S of a prior art Einlippenbohrers with a known Standardanschliff. The cutting edge is divided into two straight part-cutting S1, S2, wherein the outer part-cutting edge S1 has a setting angle κ _r1 greater than 90 ° and the inner part-cutting edge S2 has a setting angle κ _r2 smaller than 90 °. The part-cutting meet at the drill tip SP at a distance E from the circumference of the drill, which corresponds to about a quarter of the drill diameter D.

3 shows a cutting edge of a first Einlippenbohrers invention, which has a strictly convex curved contour K. The setting angle κ _r1 at the outermost point P1 of the contour which is closest to the circumference of the drill head is greater than 90 °. The setting angle κ _r2 at the innermost point P2 of the contour closest to the drill central axis A is less than 90 °. The point P3 of the strictly convexly curved contour, which is located farthest in the feed direction, is arranged at a distance E from the circumference of the drill head, which corresponds to approximately one quarter of the drill diameter D. Convex contour means a convex contour of the drill seen from the front. The strictly convex contour has, at all circumferential points, a gradient increasing from the innermost, the axis of rotation, towards the outermost point, which slope is negative (angle κ _r2 ) in the area of the axis of rotation A and increases strictly monotonically up to a positive value at the outermost point, ie at the outer diameter of the drill (angle κ _r1 ). The gradient passes through a zero crossing, which is located at point P3. In this point, the slope is 0, which means that the angle that the tangent at this point includes with the axis of rotation A is 90 °.

At the in 4 shown second cutting edge S according to the invention of a single-lip drill four substantially straight part-cutting S1, S2, S3, S4 are provided. The setting angle κ _r1 at the outermost point P1 of the contour, which is closest to the circumference of the drill head, is greater than 90 °. The setting angle κ _r2 at the innermost point P2 of the contour closest to the drill central axis A is less than 90 °. The point P3 of the convexly curved contour, which lies farthest in the feed direction, is arranged at a distance E from the circumference of the drill head, which corresponds to a quarter of the drill diameter D.

In 4 the contour K is drawn as a dotted line. The cutting edges in this case form tangents to this contour K, wherein the convex In turn, the contour is characterized in that its slope increases strictly monotonically from a negative value in the region of the axis of rotation A (point P2) to a positive value at point P1, which is located on the outside diameter of the drill. The gradient also passes through a zero crossing in this case. This zero crossing is at the imaginary contour K at the point P3. It is - in other words - in a sense the in 3 represented contour K by straight part-cutting "approximated", the part-cutting tangents to the imaginary contour K represent. The straight part-cutting thus take the position of tangents to the contour K according to the embodiment of the invention, as in 3 is shown, a.

5 shows a third cutting edge S according to the invention a Einlippenbohrers having a convex curved contour K, which is approximated by three substantially straight part-cutting S1, S2, S3. The setting angle κ _r1 at the outermost point P1 of the contour which is closest to the circumference of the drill head is greater than 90 °. The setting angle κ _r2 at the innermost point P2 of the contour closest to the drill central axis is less than 90 °. The length F of the sub-cutting edge S3 is dimensioned to correspond to approximately 8% to 10% of the drill diameter D. In the figure, a length F is shown for clarity, which corresponds to 20% of the drill diameter D. The point P3 of the convex curved contour, which is furthest in the feed direction, is arranged at a distance E from the circumference of the drill head, which corresponds to a quarter of the drill diameter D. This embodiment differs from that in FIG 4 represented by the fact that the contour K, in this case, in turn, an imaginary contour K, which is indicated by a dashed line in 5 is partially approximated by three partial cutting, these three partial cutting S1, S2, S3 again represent the tangents to the contour K. Also in this case is the point P3, which is located furthest in the feed direction, ie in 5 below, at a distance E from the drill outer diameter. Also in this case, the imaginary dash-dot drawn contour K of the cutting edge is strictly convex, ie, the pitch increases strictly monotonically from a point P2 closest to the axis of rotation A to a point P1 located at the outside diameter of the drill is. The gradient also passes through a zero crossing, which is arranged at a point P3. This point P3 is the point furthest in the feed direction, located at the distance E from the drill outer diameter.

The Invention is not limited to three or four part cutting. Rather, it can be provided that the strictly convex contour K the cutting edge of the single-lip drill by more than four part-cutting, especially more than four straight part-cutting, approximated is. Also in this case, the above conditions apply corresponding.

Of the Drilling head and the drill shank of the Einlippenbohrers can be made in one piece.

alternative The single-lip drill can also be designed so that the drill head and the drill shank are assembled. In particular, the Be replaceable drill head. In addition, at least the drill head made of a wear-resistant metal, in particular hard metal, be prepared. Furthermore the drill head can at least partially provided with a coating be.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - JP 59196108 A1 [0012]
• - DE 20321368 U1 [0014]

Cited non-patent literature

• - VDI 3210 [0002]
• - VDI 3208 [0002]
• - VDI 3208 [0009]

Claims (14)

Single-lip drill having at least one cutting edge formed on a drill head, which has at least one cutting edge, wherein the setting angle (κ _r1 ) at the outermost point (P1) of the cutting edge, which is closest to the circumference of the drill head, greater than 90 ° and the setting angle ( κ _r2 ) at the innermost point (P2) of the cutting edge which is closest to the drill center axis (A) is smaller than 90 °, characterized in that the at least one cutting edge (S) has a strictly convexly curved contour and that a point (P2) P3) of the convex contour which is located farthest in the feed direction, at a distance (E) is arranged to the periphery of the drill head, which corresponds to a fifth to a third, in particular a quarter of the Bohrdurchmessers (D). Single-lip drill with at least one cutting edge formed on a drill head, characterized in that at least three part-cutting edges (S1, S2, S3) together form a convex contour, that the setting angle (κ _r1 ) of a first part-cutting edge (S1), the Greater than 90 ° is the circumference of the drill head, that the setting angle (κ _r2 ) of a second part of the cutting edge closest to the Bohrermittelachse is less than 90 ° and that between the first and the second cutting edge (S1, S2) at least a third part-cutting edge (S3) is arranged. Single-lip drill according to claim 2, characterized in that that exactly three partial cutting (S1, S2, S3) are provided. Single-lip drill according to claim 2 or 3, characterized that the part-cutting are straight. Single-lip drill according to claim 4, characterized in that that the at least three part-cutting tangents to one strictly convex curved contour (K) are, with the convex contour (K) is formed such that a point (P3) of the convex contour (K), which is furthest in the feed direction, at a distance (E) is arranged to the circumference of the drill head, one-fifth to one third, especially a quarter, of the drill diameter (D) corresponds. Single-lip drill according to claim 4 or 5, characterized that the setting angle of the third part-cutting edge (S3) in a Range of 80 ° to 100 °. Single-lip drill according to claim 4 or 5, characterized in that the setting angle (κ _r3 ) of the third part-cutting edge (S3) corresponds to at least approximately 90 °. Single-lip drill according to one of the claims 4 to 7, characterized in that the length (F) of third part cutting edge (S3) is 5% to 20% of the drilling diameter (D). Single-lip drill according to claim 8, characterized in that that the length (F) of the third part-cutting edge (S3) 8% to 10% of the drilling diameter (D). Single-lip drill according to one of the preceding claims, characterized in that the single-lip drill a drill head and a drill shank and that the drill head and the drill shank made in one piece. Single-lip drill according to one of the preceding claims, characterized in that the single-lip drill from a drill head and a drill shank is composed. Single-lip drill according to claim 11, characterized in that that the drill head is replaceable. Single-lip drill according to one of the preceding claims, characterized in that at least the drill head of a wear-resistant Material, in particular hard metal, is produced. Single-lip drill according to one of the preceding claims, characterized in that at least the drill head at least partially provided with a coating.