DE202016001386U1 - Cylinder head drills - Google Patents

Abstract

Cylinder head drill (1) with a clamping shaft (3) and with a cylindrical drill head (2) comprising a centering tip (4) and an outer, with pre - cutting (13) drill collar (K) and in which between the centering tip (4) and the outer circumference two main cutting edges (5, 6) are arranged, which extend substantially radially, wherein in the drill head (2) to the two free surfaces (9) of the main cutting edges (5, 6) adjoining, open towards the periphery, the drill head (2) obliquely penetrating and the Bohrkranz (K) interrupting chip channels (8) are arranged, wherein the jacket wall (7) is interrupted by substantially obliquely axial recesses (12) to form pre-cutting (13) of the split drill collar (K) characterized in that each main cutting edge (5, 6) is divided radially into at least two separate and axially projecting cutting bodies (10a, 10b; 10c, 10d), that between the cutting bodies (10a, 10b; 10c, 10d) of each main cutting edge (5; 6) a chipmunk furrow (S1; S2, S3) is arranged such that each chip flute furrow (S1) is assigned to the first main cutting edge (5) radially a cutting body (10c) of the second main cutting edge (6) and that the width (B10c) of an associated cutting body (10c) of the second main cutting edge (5c) 6) is wider than the width (BS1) of an associated Spanmehlfurche (S1) of the first main cutting edge (5).

Description

The invention relates to a cylinder head drill of a type as previously by the patent of the applicant DE 41 15 030 C1 got known. However, the invention is specific to embodiments in the patents DE 197 02 423 B4 and EP 0 855 257 B1 the applicant.

Such special cylinder head drills, generally known as Forstner drills or art drills, have consistently proven themselves very well, especially in the processing of wood, wood-based materials and plastics. In particular, due to their relatively large diameter, these tools have to provide a large cutting performance. The inevitable resulting frictional heat affects the performance of the tool, in particular its life at high cycle times, requires a lot of energy and can the quality of the hole, z. B. as a result of combustion or deformation of the material, reduce.

Known causes for the heat development are the friction on the outer surface, the heat of cutting by the main cutting on the one hand and by the precut on the outer surface on the other hand, as well as the deformation heat at the centering, which has only a slight Zerspanwirkung due to their geometry, but as a result of material crushing and material displacement also contributes its part to the heat development.

The invention is based on the desire to further develop the above-mentioned type of cylinder head drill so that in particular the said inevitably occurring process heat is significantly reduced in order to improve the cutting performance quantitatively and qualitatively.

Starting from a cylinder head drill with a clamping shaft and with a cylindrical drill head comprising a centering tip and an outer, precut drill collar and in which between the centering tip and the outer circumference of two main cutting edges are arranged, which extend substantially radially, wherein in the drill head two The invention is first of all proposing to the two free surfaces of the main cutting edges, open towards the periphery, obliquely penetrating the drill head and interrupting the drill collar, wherein the jacket wall is interrupted by substantially obliquely axial recesses to form precuts of the two-part drill collar in that each main cutting edge is radially divided into at least two separate and axially projecting cutting bodies, that between the cutting bodies of each main cutting edge a Spanmehlfurche is arranged, that each Spanmehlfurche the first main cutting edge radially a Schne idkörper the second main cutting edge is assigned and that the width of an associated cutting body of the second main cutting edge is wider than the width of an associated Spanmehlfurche the first main cutting edge, and vice versa.

By this measure, individual short shavings are generated by the cutting body, which are partly derived immediately in the form of chip meal by the Spanmehlfurchen. The consequences are a reduced friction and a lower heat generation in the area of the two main cutting edges, which now receive additional, namely lateral, radial cooling surfaces through their multiple radial breakdown by cutting bodies.

By the DE 299 11 945 U1 Although it is already known to provide the one main cutting edge with three grooves and the other main cutting edge in another radial region with two grooves, so that on one main sheath resulting sub-cutting the grooves of the other main cutting edge. Here, the span of a main cutting edge is to be broken by the grooves of the same main cutting edge. In this design, however, there is a risk that parts of the broken chip settle in the groove and thus creates a so-called built-up edge. A really ordered chip formation then no longer takes place, the main cutting presses, heats up and dulls off. Exactly these hot pursuit are avoided by the design according to the invention.

If it is provided in a further development of the invention that the cutting body has lateral undercuts, thus consequently having a chip flute furrow diverging side surfaces which increase the width of the chip flute furrow backwards, counter to the direction of rotation, then any damming of chip meal in these chip flute furrows is avoided. The chip meal is a small part of the amount of chips that forms at the breaking edge of the chip. Through the rear opening of the cutting body it passes over the free surface behind the main cutting edge, then flows freely to the free space of the chip channel and mixes there with the main chip flow, which is discharged directly from the main cutting edge over the chip channel surface and the free space of the chip channel.

In order to optimize the particle flow, in contrast to the prior art, it can be provided that a chip flute furrow is arranged directly between the centering tip and a cutting body. In this way, fine chip meal produced by the centering tip can also be selectively removed by a short path.

There are different ways to realize the cutting body in the context of the invention: First, it can be provided that the cutting body formed as a separate, separate cutting body and are fixed or interchangeable connected to the drill head. Such bodies can z. B. made of hard metal, ceramic or other high-strength materials.

However, it may also be provided that the cutting bodies are indeed formed as a separately axially projecting cutting body, but form a single body with the rest of the drill head. If desired or necessary, these protruding cutting bodies can then be subsequently hardened and / or tempered, also together with the other cutting edges.

The cutting body and the Spanmehlfurchen be radially offset from one another on the two main cutting edges, that the cutting body mutually engaged. Each cutter body generates a torque to the drill center axis. This torque is particularly dependent on the size or length of the cutting body, its cutting angle and its distance from the drill center axis, as well as the feed of the cylinder head drill.

With unfavorable design of some of these sizes, on both sides of the drill center axis, ie in the two main cutting edges, very different torques can occur, which act on the cylinder head drill. This inequality can lead to vibrations in the cylinder head drill and thus to additional friction on its lateral surface or centering losses. This is prevented by the fact that the sum of all torques generated by the cutting body of the first main cutting edge of the sum of all the torques generated by the cutting body of the second main cutting edge is at least almost equal. This desired equality can be achieved at least approximately by corresponding differential or integral calculation models and / or by appropriate tests and should as far as possible not exceed a deviation of 10%.

Another feature of the invention for reducing heat buildup is improving the geometry of the center point. In order to ensure a good centering of the cylinder head drill at the beginning of the drilling process, the centering tip is generally constructed as a square pyramid, When penetrating the centering point in the material, for. B. in wood, this is pressed more radially to the side than cutting efficiently. The edges of the center point have negative rake angles. Thus, only part of the displaced amount becomes wood flour. For deep holes - or very hard material - the center point can heat up so much that the wood is scorched in the area around the center point and dulls the centering tip.

The DE 27 09 830 B2 describes in an older center drill a tetrahedron as a centering tip with an area that is cut inwards. Although this improves the rake angle in the direction of rotation at one of the three edges, the centering effect inevitably deteriorates.

The above already mentioned DE 197 02 423 B4 Although already shows a pyramidal centering, which has at their main cutting surfaces facing surfaces, so that there is an arrow-like tip. However, this form does not lead to a significant improvement.

In continuation of the invention is therefore proposed that the pyramidal centering tip are formed in the direction of rotation cutting. In particular, it is proposed that the centering tip be formed on two diagonally opposite edges at least in the lower third or even total cutting. This gives the square pyramid in cross-section a diamond-like shape. Within this area, the centering point has one long and one short diagonal in the sectional plane. During rotation, only the edges with the long diagonal press into the wood, because the area of the edges with the short diagonal stand inside the circular arc formed by the long diagonal. Furthermore, the two flat surfaces in the area of the flattening and the long diagonal are reworked into hollow surfaces. This creates two more cutting edges with improved rake angle at the pyramid base. The two new cutting edges open directly on the main cutting edges of the cylinder head drill. This ensures a better cutting action of the centering without negatively affecting its main function of centering. In addition, the chip dust generated by the centering tip is better dissipated.

With the reduction of heat development in the lateral surface, the above already mentioned DE 197 02 423 B4 , There, it is proposed to interrupt the otherwise smooth-walled jacket wall by means of essentially radially extending recesses which are provided there. This leads to a smaller contact surface between the lateral surface and the borehole wall.

In a continuation of the invention, it is proposed that the jacket wall is provided on the outside with a large number of peripheral, virtually tangential grooves. As a result, although the outermost lateral surface is still reduced, but without the Guide height of the jacket to reduce. At the same time, however, the grooves increase the effective outer surface area, ie an increased surface area is now available for heat removal. In the process, the finally circular grooves encircle the radial bulges, which are slightly angled in the direction of rotation. This design leads to an increased heat transfer in the space facing away from the cutting edge. The warm air is thus led out of the borehole. The additional grooves reinforce this effect by first supplying the heat generated on the diamond-shaped contact surfaces directly to the radial bulges, from which the heat is then dissipated in the rear drilling. The grooves may be formed in cross-section preferably at least approximately semicircular or arcuate.

From the FR 1 274 316 or even from the WO 98 35 777 Although spiral grooves already have external grooves. However, these serve there in the form of round bevels or guide chamfers for better concentricity, for better or additional cutting action on the spiral edges or to display the drilling depth of twist drills. In contrast to the relatively long and slender twist drills, the diameter of a cylinder head drill is a multiple of the shell height. Here already ensure the centering and the outer surface for a straight bore of a relatively large diameter drill, so that so far no such grooves can be found here.

In the drawing, an embodiment of the invention is shown, which will now be described in more detail.

1 shows a cylinder head drill in perspective view.

2 shows the cylinder head drill 1 in front view.

3 shows the cylinder head drill 1 in side view, from left.

4 indicates the area of the centering point of the cylinder head drill 1 in greatly enlarged representation.

5 indicates the area of the center point 4 in the view A.

6 indicates the area of the center point 4 in view B.

7 indicates the area of the center point 4 with two cuts.

8th shows the front view of the centering tip on the cutting plane EF of 7 ,

9 shows the front view of the centering tip on the cutting plane GH of 7 ,

The cylinder head drill 1 consists essentially of a drill head 2 and a clamping shaft 3 , The drill head 2 is formed substantially circular cylindrical and comprises two of a centering tip 4 almost radially outgoing main cutting edges, each as a cutting zone sections 5 and 6 formed, extending to the shell wall 7 extend. The cutting zone sections 5 and 6 be on sloping open spaces 9 from two axially projecting cutting bodies, namely on the one hand 10a and 10b and on the other hand 10c and 10d , educated.

The cutting zone sections 5 and 6 upstream are each the drill head 2 obliquely penetrating chip channels 8th and then backward the open spaces 9 that go into the chip channels 8th open out.

The mantle wall 7 is through the two chip channels 8th interrupted. The mantle wall 7 is alternately made of arcuate surface sections 11 and corresponding obliquely axially extending grooves 12 produced, so that at the top a multiplicity of Vorschneiden 13 are formed, which together only one through the chip channels 8th form interrupted drill collar K.

The arcuate surface sections 11 be of tangential circumferential grooves 14 interrupted. As a result, the effective outer surface of the shell wall becomes 7 significantly reduced without reducing their leadership in the borehole.

The cutting zone sections 5 and 6 consist of the open space 9 and the cutting bodies projecting therefrom 10a to 10d with their front edge and the chip channel surfaces 15 form a surface composite with the same rake angle. The height of the cutting body 10a to 10d in relation to the open space 9 is a multiple of the chip thickness, ie depending on the diameter of the drill head 2 approximately between 0.1 and 0.5 mm. The cutting body, z. B. 10c , tapers at its side surfaces by the angle α of about 3 ° to 8 ° and forms an opposite to the direction of rotation open trapezoidal shape. In other words, those over the sloping open spaces 9 axially rising cutting body 10a to 10d have a lateral or radial undercut.

The radial assignment of the cutting body 10c to the Spanmehlfurche S1 is in 2 For example, with reference to an inserted dash-dotted circle, the following is clarified: The cutting body 10c passes over the turning range of the chip mill groove S1. The explained radial allocation applies the same for the other cutting body 10a and 10b or Spanmehlfurchen S2 and S3. It can be clearly seen that the width B10c of the cutting body 10c is greater than the width BS1 of the chip flute S1.

The 4 to 6 make the center point 4 enlarged dar. In the front view according to 4 form the edges 17 . 17 ' . 18 and 18 ' a pyramidal body. The edges 17 and 17 ' run to the base of the center point 4 at the cutting zone sections 5 and 6 , The edges 18 and 18 ' become through to the central axis 19 radially extending and to the base of the centering 4 inwardly inclined surfaces 20 and 20 ' shortened. Between the line CD in 5 and the base of the center point 4 are between the edges 17 and 18 , as well as opposite between the edges 17 ' and 18 ' , Hollow surfaces 21 and 21 ' formed with the edges 17 and 17 ' Cutting S17 and S18 form directly into the cutting zone sections 5 and 6 open out. It hits the edge 17 ' on the open space 9 of the cutting zone section 5 and the edge 17 on the cutting body 10b of the cutting zone section 6 , The circle of intersection 16 marks the largest radius of the circumferential edges S17 and S17 '. The edges 18 and 18 ' do not come here to the intervention.

6 shows the center point 4 from the view along the cutting zone sections 5 and 6 , From this view, it can be seen how the radially inwardly inclined surface 20 the cutting edge S17 is free.

7 corresponds to 5 and serves to orient the sectional views of the centering tip 4 in the 8th and 9 , The pyramidal design of the penetrating into the workpiece gate of the centering tip 4 on average EF the 8th has no deliberately pronounced cut edges. The only function here is the best possible centric guidance. The cutting 17 and 17 ' are not yet engaged in this position.

Upon further penetration into the workpiece in the area of the cut GH in 9 the blades S17 and S17 'are partially engaged. Once the center point 4 has completely penetrated, have also reached the cutting edges S17 and S17 'their full effect and are then in connection with the main cutting edges 5 and 6 and lead the resulting chips to the chip channel 8th to.

LIST OF REFERENCE NUMBERS

1

Cylinder head drills

2

wellhead

3

clamping

4

centering

5

Main cutting edge, cutting zone section

6

Main cutting edge, cutting zone section

7

shell wall

8th

chip channel

9

open space

10a

Scabbard of 5

10b

Scabbard of 5

10c

Scabbard of 6

10d

Scabbard of 6

11

arcuate surface section

12

obliquely axial recess

13

Vorschneide

14

tangential groove

15

Chip channel area

16

cutting circle

17

Edge of 4

17 '

Edge of 4

18

Edge of 4

18 '

Edge of 4

19

central axis

20

radially inclined surface

21

concavity

BS1

Width of S1

B10c

Width of 10c

K

drill collar

S1

Span flour furrow

S2

Span flour furrow

S3

Span flour furrow

S17

Cutting edge of 4

S17 '

Cutting edge of 4

α

Undercut angle

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 4115030 C1 [0001]
• DE 19702423 B4 [0001, 0016, 0018]
• EP 0855257 B1 [0001]
• DE 29911945 U1 [0007]
• DE 2709830 B2 [0015]
• FR 1274316 [0020]
• WO 9835777 [0020]

Claims (10)

Cylinder Head Drill ( 1 ) with a clamping shaft ( 3 ) and with a cylindrical drill head ( 2 ), which has a center point ( 4 ) and an outer, with pre-cutting ( 13 ) and in which between the centering point ( 4 ) and the outer circumference of two main cutting edges ( 5 . 6 ) are arranged, which extend substantially radially, wherein in the drill head ( 2 ) two to the two open spaces ( 9 ) of the main cutting edges ( 5 . 6 ) subsequent, open to the periphery, the drill head ( 2 ) obliquely penetrating and the Bohrkranz (K) interrupting chip channels ( 8th ) are arranged, wherein the shell wall ( 7 ) by substantially obliquely axial recesses ( 12 ) for the formation of pre-cutting ( 13 ) of the split drill collar (K) is interrupted, characterized in that each main cutting edge (K) 5 . 6 ) radially in at least two separate and axially projecting cutting body ( 10a . 10b ; 10c . 10d ), that between the cutting bodies ( 10a . 10b ; 10c . 10d ) every main cutting edge ( 5 ; 6 ) a chip flute furrow (S1; S2, S3) is arranged such that each chip flute furrow (S1) faces the first main cutting edge (S1; 5 ) radially a cutting body ( 10c ) of the second main cutting edge ( 6 ) and that the width (B10c) of an associated cutting body ( 10c ) of the second main cutting edge ( 6 ) is wider than the width (BS1) of an associated chip flute furrow (S1) of the first main cutting edge (BS1) 5 ). Cylinder Head Drill ( 1 ) For protection claim 1, characterized in that the cutting body ( 10a . 10b . 10c . 10d ) has lateral undercuts (angle α), so that a chip flute furrow (S1, S2, S3) has diverging side surfaces which increase the width (BS1) of the chip flute furrow (S1) towards the rear, counter to the direction of rotation. Cylinder Head Drill ( 1 ) For protection claim 1 or 2, characterized in that a tensioning flour groove (S2) immediately (between the centering tip 4 ) and a cutting body ( 10c ) is arranged. Cylinder head drill according to one of the claims 1 to 3, characterized in that the cutting bodies are formed as separate cutting body and fixedly connected to the drill head. Cylinder Head Drill ( 1 ) according to one of the claims 1 to 3, characterized in that the cutting bodies ( 10a . 10b . 10c . 10d ) are formed as separately axially projecting cutting body, but with the rest of the drill head ( 2 ) form a single body. Cylinder Head Drill ( 1 ) according to one of the claims 1 to 5, characterized in that the sum of all by the cutting body ( 10a . 10b ) of the first main cutting edge ( 5 ) generated torques of the sum of all by the cutting body ( 10c . 10d ) of the second main cutting edge ( 6 ) Torques generated is at least almost equal. Cylinder Head Drill ( 1 ) according to the preamble of claim 1 protection or according to one of the claims 1 to 6, characterized in that the pyramidal centering point ( 4 ) acting in the direction of rotation cutting (S17, S17 ') are formed. Cylinder Head Drill ( 1 ) according to protection claim 7, characterized in that the centering point ( 4 ) on two diagonally opposite edges ( 17 . 17 ' ) are formed at least in the lower third cutting (S17, S17 '). Cylinder Head Drill ( 1 ) according to protection claim 8, characterized in that at the centering point ( 4 ) two diagonally opposite edges ( 17 . 17 ' ) are formed overall as cutting edges (S17, S17 '). Cylinder Head Drill ( 1 ) according to the preamble of claim 1 protection or according to one of the preceding claims, characterized in that the shell wall ( 7 ) outside with a plurality of circumferential grooves ( 14 ) is provided.

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