WO2005030418A1

WO2005030418A1 - Drill bit

Info

Publication number: WO2005030418A1
Application number: PCT/EP2004/010509
Authority: WO
Inventors: Helmut Miller
Original assignee: MAPAL Fabrik für Präzisionswerkzeuge Dr. Kress KG
Priority date: 2003-09-24
Filing date: 2004-09-18
Publication date: 2005-04-07
Also published as: DE10346217A1

Abstract

The invention relates to a drill bit (1) for machining workpieces, comprising solid bit tips, which have geometrically defined cutting edges, and comprising lands. The inventive drill bit is characterized in that: four bit tips (11, 11'; 13, 13') and four lands (23, 23', 33, 33'), which are assigned to the bit tips, are provided, and; the bit tips are assigned to one another in pairs so that a first pair is provided as solid bit tips (11, 11') and a second pair is provided as boring bit tips (13, 13').

Description

drill

description

The invention relates to a drill for machining workpieces according to the preamble of claim 1.

Drills of the type mentioned here are known. They are used for the machining of workpieces, whereby rotating drills usually interact with a stationary workpiece. However, it is also conceivable to let the drill stand still and set the workpiece in rotation. The decisive factor is a relative rotation between the tool and the workpiece. Known drills have two solid cutting edges with associated guide chamfers. It has been found that in many cases the machining time, ie the time to drill a hole in a workpiece, is too long and that the geometry of the hole produced, ie its roundness and coaxiality, does not meet high requirements.

The object of the invention is therefore to provide a drill which does not have these disadvantages.

To solve this problem, a drill is proposed which has the features mentioned in claim 1. It is characterized by the fact that four cutting edges and four guide chamfers assigned to them are provided. The cutting edges are assigned to one another in pairs, a first pair being designed as solid cutting edges and a second pair as boring cutting edges. The solid cutting edges are used for full drilling, the other two cutting edges, i.e. the boring edges, support the machining of the solid cutting edges in the outer diameter area of the drill. To this In this way, the feed of the drill can be significantly increased compared to known embodiments when machining a workpiece. The guiding surfaces of the boring cutters stabilize the tool in the bore created in such a way that the geometry of the bore, i.e. its roundness and coaxiality, is significantly improved.

An exemplary embodiment is preferred which is characterized in that the division between the main and boring cutting edge is less than 90 °. This makes it possible to assign a larger flute to the solid cutting edges than the boring edges, which significantly improves chip evacuation.

Further configurations result from the remaining subclaims.

The invention is explained in more detail below with reference to the drawings. Show it:

FIG. 1 shows a top view of the end face of a first exemplary embodiment of a drill,

FIG. 2 shows a side view of the drill according to FIG. 1,

FIG. 3 shows a first side view of a second exemplary embodiment of a drill,

FIG. 4 shows a second side view of the drill shown in FIG. 3 and rotated through 90 ° about its central axis

Figure 5 is a perspective view of the drill shown in Figures 3 and 4 obliquely from the front. FIG. 1 shows a drill 1, namely its end face 3. For better orientation, a vertical first diameter line 5 and a horizontal second diameter line 7 are shown, through the intersection of which the central axis 9 of the drill 1 runs perpendicular to the image plane of FIG. 1. The end view shows that the drill 1 has a total of four cutting edges which are assigned to one another in pairs. A first pair comprises the solid cutting edges 11, 11 ', a second pair the boring edges 13, 13'. The solid cutting edges run parallel to the first diameter line 5 and extend from a circumferential line 15, which is indicated by a circle, over the end face of the drill 1 facing the viewer and even beyond the second diameter line 7. The solid cutting edge 11 is to the right of the first diameter line 5, the solid drilling edge 11 'to the left of the first diameter line 5. The two solid cutting edges 11, 11' are therefore arranged on opposite sides of the first diameter line 5. The solid cutting edges 11, 11 'intersect the second diameter line 7, a transverse cutting edge 19 intersecting the central axis 9 being formed between the ends 17, 17' of the solid cutting edges 11, 11 'lying directly beyond the second diameter line 7.

In the region of the ends 21, 21 'of the solid cutting edges 11, 11' which intersect the circumferential line 15, first guide chamfers 23, 23 'are provided, by means of which the drill 1 is supported on the wall of a bore produced.

FIG. 1 shows that the guide chamfers 23, 23 ′ extend to the right and left of the first diameter line 5.

Seen in the direction of rotation of the drill 1, indicated by an arrow 25, there are flutes 27, 27 ', with the flute 27 being assigned to the full cutting edge 11 and the flute 27' being assigned to the full cutting edge 11 '. The boundary line of the flute 27 is essentially arc-shaped, practically circular-arc-shaped and extends in the direction of the central axis 9 and extends close to the first diameter line 5 and the second diameter line 7. The flute 27 'is point symmetrical to the central axis 9. The flutes 27, 27 'serve to pick up and remove the chips removed by the solid cutting edges 11, 11'.

At an acute angle α to the first diameter line 5 there is an imaginary third diameter line 29 on which the second pair of cutting edges of the drill 1, namely the boring cutting edges 13, 13 ', lie. The length of the boring cutters 13, 13 'is significantly shorter than that of the solid boring cutters 11, 11'. They extend from the circumferential line 15 in the direction of the central axis 9 approximately over an area which is in each case half the radius of the drill 1. The length of the boring cutters 13, 13 'can be adapted to the material of the tool and the workpiece. The boring cutters 13, 13 'serve in particular to machine the material of the workpiece in the outer diameter range, so they generally end at a clear distance from the central axis 9.

Seen in the direction of rotation of the drill 1 indicated by the arrow 25, flutes 31, 31 'are provided in front of the boring cutters 13, 13', which take up and remove the chips removed by the boring cutters 13, 13 '. The flute 31 is assigned to the boring edge 13 and the flute 31 'to the boring edge 13'. The front view according to FIG. 1 shows that the flutes 31, 31 'are significantly smaller than the flutes 27, 27' assigned to the solid cutting edges 11, 11 '. The size of the Chip flutes 27, 27 'and 31, 31' depend on the one hand on how far the inner boundary line of the chip flutes extends in the direction of the diameter lines 5 and 7 or the central axis 9, but on the other hand also on the division between the full bore cutting edges 11, 11 'and boring cutters 13, 13'. the division, i.e. the angle α, is in a range from 45 ° to 90 °. As shown in FIG. 1, a pitch angle of <90 ° is preferably selected in order to be able to assign a larger flute 27, 27 'to the solid cutting edges 11, 11' than the boring cutting edges 13, 13 '. These proportions are chosen because the solid cutting edges 11, 11 'remove more chips than the boring edges 13, 13'.

Guide chamfers 33, 33 'are also provided in the area of the boring cutters 13, 13', by means of which the drill 1 is supported on the wall of a bore produced.

It can be seen from FIG. 1 that, seen in the direction of the peripheral line 15, the width of the guide chamfer 23 is defined on the one hand by the intersection of the boundary line of the flute 27 with the peripheral line 15 and on the other hand by the intersection of the boundary line of the flute 31 with the peripheral line 15. These two intersections lie to the left and right of the first diameter line 5. The width of the guide chamfer 23 'is corresponding. The width of the guide chamfer 33 is determined on the one hand by the intersection of the boring cutter 13 with the circumferential line 15 and on the other hand by the intersection of the boundary line of the flute 27 'with the circumferential line 15. The width of the guide chamfer 33' is defined accordingly.

The width of all guide chamfers 23, 23 ', 33, 33', measured in the circumferential direction of the drill 1, is selected such that the sum of the widths is preferably approximately 5% to 15% of the diameter of the drill bit. Make out rers 1. In accordance with the loads occurring during the machining of a workpiece, the guide chamfers 23, 23 ', which are assigned to the solid drilling cutters 11, 11', can be made wider than the guide chamfers 33, 33 'assigned to the drilling cutters 13, 13'.

Due to the dimensioning of the guide chamfers described here, optimal guidance of the drill 1 in the machined bore is achieved, whereby it is ensured that the friction of the guide chamfers on the bore wall does not become too great, because this would lead to an undesirably high heating of the drill.

It should also be pointed out here that the cutting edges of the drill 1, which have geometrically defined cutting edges, can also be part of cutting inserts inserted into the basic body of the drill 1.

The drill 1 can be provided with channels which are used to supply coolant / lubricant. In the embodiment shown here, two channels are provided which open into the end face 13 of the drill 1. The mouth 35 of a first channel lies in the first quadrant, the mouth 35 'of a second channel in the third quadrant. In the face 3, troughs 37, 37 'and 39, 39' adjoining the orifices 35, 35 'are provided, which serve to distribute the coolant / lubricant emerging from the orifices 35, 35'. This can be fed from the mouth 35 via the trough 37 to the full cutting edge 11 'and from the mouth 35 via the trough 39 to the boring cutting edge 13. Correspondingly, it can be fed to the solid cutting edge 11 via the mouth 35 'and the depression 37' and to the boring cutting edge 13 'via the mouth 35' and the depression 39. The flow cross-section of the troughs 37, 37 'on the one hand and the troughs 39, 39' on the other hand is preferably different: The troughs 37, 37 ', via which the coolant / lubricant is fed to the solid cutting edges 11, 11', has a larger cross-section than the troughs 39, 39 ', via which the coolant / lubricant is fed to the boring cutters 13, 13'. This dimensioning of the trough cross section serves, on the one hand, to be able to better remove the larger chip volume in the chip spaces 27, 27 'assigned to the solid drilling cutters 11, 11', and, on the other hand, to allow the solid drilling cutters 11, 11 'to receive more coolant because they are one subject to greater thermal stress than the boring cutters 13, 13 '.

Due to the fact that the size of the flutes is adapted to the volume of the chips, the solid cutting edges can be provided with a sufficiently large chip space, while the chip space of the boring edges is designed accordingly small. Overall, a maximum cross-sectional area of the drill, i.e. a maximum core size, can be achieved with optimal chip removal behavior.

Figure 2 shows the drill 1 in side view. The same parts are provided with the same reference numbers, so that in this respect reference is made to the description of FIG. 1 in order to avoid repetitions.

The side view according to FIG. 2 shows that the drill 1 has, for example, a cylindrical fastening shaft 41, which can also be designed conically or as a hollow shaft. This is followed by an area 43 provided with flutes 27, 27 'and 31, 31'. The guide chamfers 23, 23 'and 33, 33' lie between the flutes. In Figure 2, the side rake angle β is drawn, which is included between the central axis 9 and here, for example, to the boundary edge of the flute 27 '. The drill 1 is characterized by the fact that the side rake angle β can be in a range from 0 ° to 45 °, so that both twist drills and straight-grooved drills can be realized.

In the area of the end face 3 of the drill 1, the solid cutting edge 11 and the boring cutting edge 13 'can be seen. The drill 1 shows an acute angle of preferably 140 °. In the area of the fastening shaft 41, the channels 45, 45 'for the coolant / lubricant can be recognized by dash-dotted lines, which have the orifices 35, 35' shown in FIG.

The drill 1 explained on the basis of the figures is distinguished by the fact that it has four cutting edges formed in pairs, namely the solid drilling cutting edges 11, 11 'and the boring cutting edges 13, 13'. In this case, the solid cutting edges 11, 11 'together with the transverse cutting edge 19 are used for full drilling, and the boring edges 13, 13' are used for machining in the outer diameter range. All four cutting edges are preferably arranged at the same height, both radially and axially, so that the feed can be significantly increased when machining a workpiece. Twice the feed rate can be achieved that could be achieved with conventional drills. Since all four cutting edges are assigned guide chamfers, the drill 1 is optimally supported in a machined bore, which leads to a better geometry thereof, that is to say an optimal roundness and coaxiality. The drilling performance is thus improved on the one hand by the additional boring cutters 13, 13 'and the associated guide chamfers 33, 33', which leads to an increase in the feed rate, on the other hand the guidance of the drill 1 in the bore to be made in a workpiece.

Coolants and / or lubricants can be introduced into the drill 1 through the channels 45, 45 ', and so-called minimum quantity lubrication can also be implemented, in which a lubricant is fed dropwise into the channels 45, 45'. The orifices 35, 35 'of the channels 45, 45' feed the coolant / lubricant to the solid cutting edges 11, 11 'and boring edges 13, 13' via the troughs 37, 37 'and 39, 39'. With the help of the two troughs that are assigned to each mouth, all four cutting edges can be adequately supplied.

The embodiment of the drill shown in the figures can be modified. For example, it is possible to design the first pair of cutting edges in accordance with the exemplary embodiment according to FIGS. 1 and 2 as solid drilling cutting edges and the second pair as cutting edges of a milling cutter. The cutting edges serving as milling cutters are preferably provided in an axially recessed rear area.

It is also conceivable that the cutting edges are at the same axial height, but that at least one of them is designed as a milling cutter in its rear region. At least two, in particular all, cutting edges are preferably designed as milling cutters in their rear region.

Incidentally, it is also possible to provide the drill with two different areas which are offset from one another in the axial direction. The front area is designed as a drilling tool and the rear area as a milling tool. In this case, the rear area is preferably offset somewhat, ie it has a different area Outside diameter on than the front area. An embodiment is particularly preferred in which the rear, stepped region is designed as a cylindrical milling tool.

All of the exemplary embodiments have in common that the fastening shaft 41, also referred to as the receptacle, as shown in FIG. 2, can be cylindrical. It is also possible to make the fastening shaft 41 hollow. Instead of the cylindrical configuration, however, conical designs can also be realized, in which case the fastening shaft 41 can also consist of solid material or can be designed as a hollow shaft. Finally, it is possible to provide the receptacle with a flat surface 47 surrounding the fastening shank 41, which is preferably designed as an annular surface and arranged so that it lies in a plane on which the central axis 9 of the tool is perpendicular. This configuration enables the drill to be fixed particularly precisely in a tool holder, an intermediate piece or an adapter.

The two exemplary embodiments have in common that the drills each have four cutting edges and four guide chamfers, which on the one hand results in optimal guidance within the bore, so that the geometry of the bore produced meets high requirements and on the other hand a particularly large feed is possible.

The second exemplary embodiment is explained in more detail with reference to FIGS. 3 to 5. The same parts or parts of the same function are provided with the same reference numbers, so that reference is made to the description of FIGS. 1 and 2. Figure 3 shows the second embodiment of a drill 1 in side view. The conical fastening shaft 41, which is surrounded by a flat surface 47, is clearly recognizable. This is preferably designed as an annular surface and lies in a plane on which the central axis 9 of the drill 1 is perpendicular. To the right of the fastening shaft 41, also referred to as a receptacle, flutes and guide chamfers can be seen. The end face 3 of the drill has a tip angle of preferably 140 °. The solid cutting edge 11 and 11 'and a further cutting edge assigned to a pair of cutting edges can be seen here, which, however, is not designed here as a boring cutting edge but as a milling cutter edge 113'.

When machining a workpiece, the drill 1, viewed from its end face 3, is rotated counterclockwise, which is indicated in FIG. 1 by the arrow 25. Viewed in the direction of rotation, the flute 27 is located in front of the solid cutting edge 11 and the flute 31 'in front of the milling cutter edge 113'. The designations of the cutting edges and flutes are chosen in accordance with the information in FIG. 1.

In the area of the circumferential surface of the drill 1, the guide chamfer 23 adjoins the solid drill cutting edge 11 and the guide chamfer 33 'adjoins the cutter cutting edge 113'.

In the exemplary embodiment shown in FIG. 3, too, it is provided that a side rake angle> 0 ° is selected, so that the exemplary embodiment according to FIG. 3 is designed as a twist drill. But here, too, it is possible to implement straight-fluted drills.

FIG. 3 shows that in the exemplary embodiment of the drill 1 shown here, the milling cutter edge 113 'counteracts in the axial direction. is set back by the distance d above the tip of the drill. However, it is expressly pointed out that it is very possible to reduce this axial misalignment to zero, i.e. to arrange all cutting edges at the same height.

Figure 4 shows the drill shown in Figure 3 also in side view. However, the drill was rotated by 90 ° about its central axis 9. It is clear from this illustration that the guide chamfer 23 is connected to the solid drilling cutting edge 11 and the guide chamfer 33 'to the milling cutter edge 113'. The flute 27 assigned to the solid cutting edge 11 lies between the two chamfers. Below the guide chamfer 33 ', the flute 31' assigned to the milling cutter edge 113 can be seen.

FIG. 5 shows the drill 1 shown in FIGS. 3 and 4 enlarged in a perspective view obliquely from the front. The same parts are provided with the same reference numerals, so that reference is made to the description of the previous figures.

In the illustration according to FIG. 5, the drill is arranged such that the solid cutting edge 11, as shown in FIG. 4, is essentially vertical.

In FIG. 5 it is clear that the guide chamfer 23 is connected to the outside of the solid cutting edge 11 and that, viewed in the direction of rotation, the flute 27 is arranged in front of the solid cutting edge. The cutter edge 113 'can be seen offset in the axial direction. The symmetrically arranged cutting edge 113 is hidden in FIG. 5. However, it is clear that the full cutting edge 11 'is arranged symmetrically to the full cutting edge 11. On the outside, the milling phase 113 'is followed by the guide phase 31'. The flute 31 'arranged in front of the cutter edge 113' in the direction of rotation can also be seen here.

The basic structure of the drill 1 explained with reference to FIGS. 3 to 5 corresponds to that of the drill explained in connection with FIGS. 1 and 2. Four cutting edges are provided, which are designed in pairs, a first pair of cutting edges forming solid drilling cutting edges 11, 11 'and a second pair of milling cutting edges, of which the cutting edge 113' can be seen in FIGS. 3 to 5. The division of the cutting edges can be selected as in the exemplary embodiment explained with reference to FIGS. 1 and 2. It is also possible, although not shown in FIGS. 3 to 5, to provide the drill 1 according to FIGS. 3 to 5 with channels for a coolant / lubricant in order to cool the cutting edges in accordance with the explanations for FIGS. 1 and 2. lubricate.

It is essential that the four cutting edges are each assigned guide chamfers 23, 23 'and 33, 33', so that in the exemplary embodiment according to FIGS. 3 to 5 a significantly improved geometry of the bore, that is to say an improved roundness and coaxiality, is also achieved a significant increase in feed.

In the case of a drill with two solid cutting edges 11, 11 'and two milling cutting edges 113, 113', it can be provided that all cutting edges are at the same height, that is to say they are not axially offset. At least one of the cutting edges can be designed as a milling cutter in its rear region, that is to say form a milling cutter edge. It is also conceivable to design all cutting edges, provided they are at the same height, in the rear area as milling cutting edges. The drill 1 according to FIGS. 3 to 5 is preferably designed as a drilling tool in the front area and as a milling tool in the rear area. A drill according to FIGS. 3 to 5 is preferred, in which the rear area is offset by the distance d and is preferably designed as a cylindrical milling tool.

Also in the exemplary embodiment according to FIGS. 3 to 5, the fastening shaft 41 can be cylindrical, conical, full or hollow.

Both exemplary embodiments of the drill have in common that at least one cutting edge, preferably a pair of cutting edges, is designed as a solid drilling cutting edge and at least one, preferably a pair of cutting edges, is used as a reworking cutting edge, either as a boring cutting edge in the exemplary embodiment according to FIGS. 1 and 2 or as a milling cutter edge as in the case of the Embodiment according to Figures 3 to 5.

Claims

Expectations

1. Drill for machining workpieces with geometrically defined cutting edges having full drilling cutting edges and guide chamfers, characterized in that four cutting edges (11, 11 '; 13, 13') and four guide chamfers assigned to the cutting edges (23, 23 ', 33, 33') ) are provided that the cutting edges are assigned to one another in pairs in such a way that a first pair are designed as solid drilling cutting edges (11, 11 ') and a second pair as boring cutting edges (13, 13').

2. Drill according to claim 1, characterized in that the cutting edges (11, 11 '; 13, 13') are arranged radially and / or axially at the same height.

3. Drill according to claim 1 or 2, characterized in that the solid cutting edges (11, 11 ') run essentially parallel to an imaginary first diameter line (5) and are arranged on opposite sides thereof, that the length of the solid cutting edges (11 , 11 ') is selected such that it projects beyond a second diameter line (7) running perpendicular to the first diameter line (5), and that between the ends (17, 17') of the solid cutting edges (17, 17 ') which are close to the second diameter line (7) 11, 11 ') a transverse cutting edge (19) intersecting the central axis (9) of the drill (1).

4. Drill according to one of the preceding claims, characterized in that the division between the main cutting edges (11, 11 ') and boring edges (13, 13') is between 45 ° and 90 °.

5. Drill according to claim 4, characterized in that the pitch is <90 ° in order to assign a solid flute (27, 27 ') to the solid cutting edges (11, 11'), which is larger than the respective drilling edges (13, 13 '). ) assigned flutes (31,31 ').

6. Drill according to one of the preceding claims, characterized in that the side rake angle ß is 0 ° to 45 °.

7. Drill according to one of the preceding claims, characterized in that the - measured in the circumferential direction of the drill (1) - width of the guide chamfers (11, 11 ') associated with the solid cutting edges (11, 11') is larger than that of the boring edges ( 13,13 ') assigned guide chamfers (33,33').

8. Drill according to one of the preceding claims, characterized in that the total width of all guide chamfers (23, 23 '; 33, 33') is 5% to 15% of the diameter of the drill (1).

9. Drill according to one of the preceding claims, characterized in that channels (45, 45 ') are provided for an internal coolant / lubricant supply.

10. Drill according to claim 9, characterized in that two channels (45, 45 ') opening into the end face (3) of the drill (1) are provided and that the mouth (35, 35') of the channels (45, 45 ') ) Troughs (37,39; 37 ', 39') are assigned.

11. Drill according to claim 10, characterized in that the mouths (35,35 ') are preferably each assigned two troughs (37,39; 37', 39 '), one of which is in a solid cutting edge (11, 11 ') assigned flute (27,27') and a flute (33,33 ') assigned to a boring cutter (13,13') opens.

12. Drill according to claim 10 or 11, characterized in that the flow cross-section of the troughs (37,37 '; 39,39') is different and that the troughs (37,37 ') with a larger cross-section in each of a solid cutting edge (11, 11 ') associated flute (27,27') opens.

13. Drill according to one of the preceding claims, characterized in that two of the cutting edges are set back relative to the other cutting edges and that the set back cutting edges are designed as milling cutters.

14. Drill according to one of the preceding claims, characterized in that all cutting edges are at the same height and at least one cutting edge, preferably all cutting edges, is designed in the rear region as milling cutters.

15. Drill according to one of the preceding claims, characterized in that its front area is designed as a drilling tool and the rear area as a milling tool.

16. Drill according to claim 15, characterized in that the rear region is offset and is preferably designed as a cylindrical milling tool.

17. Drill according to one of the preceding claims, characterized by a fastening shaft which is cylindrical, conical, full or hollow.