WO2000061323A1

WO2000061323A1 - Drilling tool

Info

Publication number: WO2000061323A1
Application number: PCT/DE2000/000960
Authority: WO
Inventors: Felix Leeb
Original assignee: Felix Leeb
Priority date: 1999-04-07
Filing date: 2000-03-25
Publication date: 2000-10-19
Also published as: AU4742900A; DE19915536C1; DE10080825D2

Abstract

The invention relates to a drilling tool which is suitable for dry machining boreholes in all materials which can be rapid machined. When drilling tools are used with this type of cutting assembly on computerised numerical control machines, the resulting borehole can be chamfered simultaneously. The conversion of the drilling tip to a recess with an approximate mirror symmetry prevents a built-up edge from forming in the drilling tip area, (similar to cooling exclusively by compressed air), which often occurs during the creation of boreholes in a dry machining process. In addition, the elimination of the zero cutting speed in the central area reduces the axial resistance by at least 50 %. It is thereby possible for the machines which are used in the drilling process to be less stable and to create a borehole of 12mm in diameter, using a hand drill without the aid of attachments (that is to say by hand) in solid material, even in steel. For this type of utilisation, a light centering is necessary beforehand. The problems associated with creating deep boreholes in a dry machining process can also be simply solved by modifying one of the innerlying front flank cutters in the central area. This is achieved by shortening a cutter, thus displacing the drill tool slightly and producing a marginally larger borehole in relation to the tool. The possibility of fitting three high-performance cutters, even to drill tools equipped with interchangeable cutting plates and of drilling a borehole immediately into solid material leads to an increase in rapid machining performance of at least 50 %.

Description

Drilling tool

The invention relates to a drilling tool according to the preamble of claim 1. Such a drilling tool is known for example from DE-05 2420191. Currently, the use of such tools with this M face cutting edge is only possible when machining short-chipping materials such as alloy aluminum. This limited possibility of using the drilling tools with such an M face cutting edge is mainly due to the fact that the removal of the drilling chips in the central area of the drill must also be done more or less by shearing, whereby above all the chip produced in this way cannot flow off unhindered.

This unimpeded outflow in the center area is only made possible by the shortening of a recess on one side of the cutting edge, which extends from the drill axis, the remaining inner side of the cutting edge thereby being lengthened by this dimension. This then enables an unimpeded outflow of the chips then produced in this center area in the cutting process. Drilling tests have shown that the new cutting design shown here can increase the axial feed rate by approximately 2.5 times. This also increases the service life of such tools, at least by this value.

A drilling tool is known from DE 44 16040 A1, which is equipped with indexable inserts, an M cutting edge also being indicated slightly here. With this cutting arrangement in the center area, the drilling swarf is removed by pressing or shearing off, whereby the drilling swarf cannot flow unhindered here either. Furthermore, no three full-fledged cutting edges can be attached to the insert holder with this insert design. A cutting tool which is equipped with an indexable insert is known from EP 42 12 OA1.

The insert consists of a round plate, which can then be fixed in the holder by a 90 ° recess in the circumferential area of the round plate according to its position.

When drilling holes in dry machining (without adding emissions), it often happens that in the area of the drill tip

ERSATZBLAH (RULE 26) (State of the art in the processing of steel, etc.) forms a built-up edge, which then usually ends in a tool breakage. Processing in the dry process is the same as cooling and removing the chips only by means of compressed air, be it during drilling or milling, due to their advantages, it is becoming more and more popular. The ability to dispense with the addition of cooling lubricants saves considerable costs when disposing of the chips that are produced.

In addition to the build-up edge mentioned above, there are other problems with dry machining of bores, such as the chip removal and the diameter expansion of the tool, due to the strong heating of the drill with deep recesses, which can lead to jamming in the upper bore area when withdrawing from the recess, whereby even a tool breakage is not excluded. The problems that can be observed when the drill is withdrawn after the drilling process has been completed are due to the increased heating of the drill in the region of the drill cutting edges during dry drilling. This increasing warming of the drill during the drilling process leads to a continuous increase in the diameter of the drill hole and this increases with increasing drill depth. Depending on the temperature of the drill in its cutting area, this can easily be calculated. The result is that at the end of the drilling process the diameter of the drill and, accordingly, the diameter of the hole are larger than at the start of the hole. This leads to severe jamming in the hole when the drill is withdrawn. One consequence of this jamming is an even greater heating of the tool, its associated further expansion, the audible loud drilling noises and the demonstrable increase in torque when the drill is withdrawn from the bore.

Another problem with creating a hole is that the drilling tip mentioned above comes to the cutting insert during the drilling process in its central area with zero (identical) cutting speed. This creates a not inconsiderable axial resistance, which on the one hand requires powerful and above all stable machines. because of the already mentioned large axial resistance. Also the removal of the resulting chips during the machining process during dry machining also a bit problematic. On the other hand, the core hole advance in a blind hole should also be shortened if a thread is to be introduced into it. This is especially true for workpieces with thin walls. Furthermore, special deep drilling tools are currently required to create very deep holes. A tool equipped with three cutting edges would be advantageous for precision bores and deep bores, but the use of such tools is not possible with the cutting geometries currently used for cutting, especially in the interchangeable insert design in full material. A cutting tool with three end cutting edges results in an additional increase in cutting performance of at least 50%.

A chamfering of the created bore recesses with the current one is also used. Cutting edge geometry is not possible, even if the tool is used on CNC-controlled machines. This still requires a specially designed step drill for the respective depth of cut. At the moment, even a slight diameter adjustment of the tool cutting edges is not possible, even when using interchangeable cutting inserts for multi-cutting tools. In the case of deep bore recesses, a course of the recess made deviating from the bore axis can often be determined.

The invention has for its object to provide a drilling tool which is also suitable for dry drilling, which solves the problems shown above, regardless of whether the tool is made of solid material or is equipped with a cutting plate that is continuous in its entire width, or can be continuous Cutting plate also consist of several plates, these being above all interchangeably attached, such that at least two mirror-like cutting geometries always come into cutting engagement, at least in the area of the main end cutting edges. When using interchangeable cutting inserts, there should then be a possibility to be able to continuously adjust the cutting diameter with these tools by approx. 1 mm. This object is achieved by the features specified in claim 1. Further advantageous refinements are specified in the subclaims. This object is essentially solved in claim 1. In this case, the drilling tool is not covered with a drilling tip in its face cutting center area, but is this area is provided with a recess. This recess is made at an angle of approximately 2 x 45 ", or this recess can be made in significantly different degrees. The recess size is approximately a quarter to a third of the respective tool diameter. Furthermore, at least one is the inner one End cutting edges are shortened in length starting from the center region of the drilling tool, one of the remaining cutting edges then being extended in this cutting length by approximately this dimension beyond the drill axis. This modification of the center cutting edge region results in the following advantages: the zero cutting speed occurring in the drilling center is eliminated, This means that chip removal in the center of the hole is carried out by a cutting process in this cutting geometry design. This means that no built-up edge is formed in the core area of the drilling tool, furthermore the core hole advance is shortened by approx was reduced by at least 50% during the drilling process. Chip evacuation is significantly improved since the chips are reduced by about 1/4 to 1/3 in their width. This narrowing of the chips also allows the chip removal grooves to be reduced, which means that the tools provide better stability (larger core diameter dimensions possible). The chips break more easily because they are narrower and the diameter size of the bore recess can be increased by this change in the inner flank cutting edges (like this one-sided recess in the core area of the tool) by slightly clearing at least one cutting edge side in the center. As a result of this measure, the bore recess dimension changes slightly upwards compared to the tool diameter dimension. By attaching a 45 ° chamfer in the transition from the main face cutting edges to the flank cutting edges, this chamfer can be used to chamfer the created recess when using such tools on CNC-controlled machines, regardless of the depth of the recess (this eliminates the need for step drills). If a radius is applied in the transition from the main cutting edges to the side cutting edges and from the inner cutting edges to the main cutting edges, the service life of the tools is increased on the one hand, and on the other hand, the drilling chips are rolled better, which further improves chip removal. In order to improve chip evacuation, particularly in the case of very deep bore recesses, the end cutting edges can also be designed in a slight arc shape. By this measure, the chips are connected to a Chip form groove broken into short chips. This means that tools with this type of cutting edge can also be used to create very deep bore recesses (as a replacement for special deep drills). These short chips can then be easily blown out via the internal cooling channels with the aid of compressed air. This new cutting edge geometry makes it possible to attach more than two face and side cutting edges (advantageously three). As a result, tools with three cutting edges can be used to create precision bores and also for deep bores, with a recess being able to be made in the full material even with such cutting edges. The attachment of a third cutting edge also results in a not inconsiderable increase in performance of at least 50%. When using interchangeable cutting inserts, their diameter can be adjusted slightly continuously via their lateral contact. As a result of this change in the cutting edge in the center area, the tool is guided better in its drilling direction by means of these additional inclined inner end cutting edges. As a result, a deviation in the drilling process from the drilling axis is almost impossible. This problem of the deviation from the drilling axis during the drilling process does not arise in the case of tools which are equipped with three cutting edges.

The invention is illustrated with reference to Figures 1 -1 1 and described in detail.

Figure 1 shows a drilling tool with currently known end cutting edge geometry for machining steel, etc.

Figure 2 shows a hole pattern that is created with a tool according to Fig.1

Figure 3 shows a drilling tool with the proposed face cutting edge geometry

FIG. 4 shows a hole pattern that was created with a tool according to FIG. 3 FIG. 5 shows a drilling tool with a cutting edge transition from the main cutting edge to the peripheral cutting edge with a 45 ° and a one-sided clearance of the cutting edge in the center area

FIG. 6 shows a drilling tool, the face cutting transitions being formed by radii

Figure 7 shows a drilling tool with arcuate main cutting edges

Figure 8 shows a drilling tool which is equipped with two interchangeable cutting plates.

Figure 9 shows this drilling tool in section A-A

Figure 10 shows a drilling tool which is equipped with three interchangeable cutting plates in section A-A.

Figure 11 shows a drilling tool in which the respective main cutting edge is created by two arcuate cutting edges.

1 shows a drilling tool (1) which is equipped with a currently known end cutting edge geometry (2) and also flank cutting edges (3). This end cutting edge geometry has a drilling tip (11) in its center (same as drilling axis) (4)

For this purpose, a hole pattern, which is created with a tool according to FIG. 1, is shown in FIG. 2, the length of the core hole advance (10) also being shown there. Fig. 3 shows a drilling tool (1) which is equipped with the new face cutting geometry. The center area (4a) is covered with a recess (5) on both sides, which extends in a diameter dimension of approximately 1/4 to 1/3 of the entire tool diameter and is offset by 180 "at an angle of approximately 45" in each case. extend to the drilling axis (4), the respective course being at least in the region of the drilling axis (4) on the center line or they can each be a few hundredths of a mm behind. Furthermore, the- se a main cutting edge (6), which then runs at an opposite angle to the flank cutting edge (3). For this purpose, a hole pattern, which is created with a tool according to FIG. 3, is shown in FIG. 4, the core hole advance (10) shortened by approximately 1/3 being shown here. 5 shows a one-sided clearance (7) in the center area (4a), whereby this inner cutting edge (5) is shortened, on the other hand, the opposite cutting edge (5) is extended by this amount. This measure results in an easily controllable deflection of the tool during the drilling process, as a result of which a minimally larger bore recess is produced compared to the tool diameter. The size of the deflection depends on the size of the franking (7). Furthermore, the transition from the main cutting edge (6) to the flank cutting edge (3) is created by a 45 'chamfer (8).

In Fig. 6, the respective cutting edge transitions are formed by a radius (R). In Fig. 7, the main end cutting edges (6) are designed in the shape of an arc (9), and the cutting edge (5) could also be made in the form of an arc. A coolant channel (12) can also be seen. In the case of these new cutting edge geometries, all cutting edges used are provided with the required clearance angle, at least the main front cutting edge (6) being created with a very positive cutting edge engagement angle.

In Fig. 8 this new cutting geometry is attached to interchangeable cutting plates (13 + 14). The length of the inner cutting edge (5) of the cutting plate (13) extends beyond the drilling axis (4). For this purpose, this dimension is shortened by this dimension in the opposite cutting edge (5) in the cutting plate (14). Both end cutting edges (5 + 6) are created in an arc shape (9), the front cutting edge area being covered with a chip-forming groove (21). The cutter plates can be connected to the cutter carrier (16) by a screw (15). The back of the plate (17) and its opposite side to the end cutting edges (18) lie on the tool carrier (16). Furthermore, the inner lateral contact surfaces (19) rest on an exchangeable, offset dowel pin (20), which can then have a larger or a smaller dimension in its system area (22) compared to its snug fit (23). This means that the upper diameter size of this pin and its Elypsenform and by turning this dowel the cutting diameter can be changed continuously by about 1 mm

the dowel pin can also be exchanged, this then having a dimension corresponding to the targeted tool diameter in its contact area (22), through a bore (12) in the cutter holder (16) which also penetrates the dowel pin (20), then compressed air or the like can be passed through . FIG. 9 shows the section AA from FIG. 8. FIG. 10 shows a further section AA, in which case three interchangeable cutting plates (13 + 14) are preferably attached by screws (15) at an offset of 120 'to the cutter holder (16) are. Here too, the length of the face cutting edge (5) extends beyond the drilling axis (4) in the case of the cutting plate (13). For this purpose, two cutting plates (14) are attached, in which the front cutting edge dimension (5) is shortened by this dimension. It is only through these different cutting lengths in the face cutting area (5) that chip removal is achieved in the cutting process in the area of the drilling axis (4). In the case of very large cutting diameters, a chipbreaker groove offset in the circumferential direction could be introduced at least in the area of the main cutting edge (6) or a further cutting edge in the shape of an arc (24) could follow the curved cutting edge (6) (Fig. 11), which creates smaller chips.

Claims

claims

1) Drilling tool which is equipped with face and flank cutting edges, the end cutting edge equipment is designed in an M-shape and can be rotated and moved with full Z-axis infeed into the full material and is suitable for use on CNC-controlled machines by moving on a bore axis concentric for simultaneous chamfering and which is also suitable for dry machining of bore recesses, characterized in that the end cutting edge geometry of the drilling tool (1) is covered in the center region (4a) with end cutting edges (5) which are in the form of a mirror-like one

Recess are created and at least in the area of the drill axis (4) opposite to the rear, but at most these are aligned cutting and that each opposite cutting edge (5) is followed by a main front cutting edge (6), which adjoins in the longitudinal direction up to one Flanking cutting edge (3) extends, one of the front cutting edges (5), starting from the lowest point of the center area (4a), being shortened in its engagement length by a recess (7), while the opposite cutting edge (5) has a corresponding amount in its cutting length over the Drill axis is also extended.

2. Drilling tool according to claim 1, characterized in that the transition from the main cutting edges (6) to the flank cutting edge (3) is formed by a chamfer (8).

3. Drilling tool according to claim 1-2, characterized in that the chamfer (8) extends in a number of degrees of 45 °.

4. Drilling tool according to claim 1, characterized in that the cutting edge transitions are formed by radii (R).

5. Drilling tool according to claim 1, characterized in that the end cutting edges (5 and 6) in arc shape (9) are created

6. Drilling tool according to claims 1-5, characterized in that the end cutting edges (5) and (6) are employed in a number of degrees from 5 'to 45'.

7. Drilling tool according to claims 1-6, characterized in that the main end cutting (6) is supplemented by an additional arcuate cutting edge (24).

8. Drilling tool according to claims 1-7, characterized in that this cutting geometry can be used for cutting all machinable materials, the cutting tool also being covered with more than two (almost) mirror-like cutting areas and with an angular offset of 120 ° or each are also attached 90 ° around the drilling axis (4).

9. Drilling tool according to claims 1-8, characterized in that this face cutting geometry is also attached to interchangeable cutting plates (13 + 14) and these have a chip-forming groove (21) in the face cutting area.