DK3213895T3

DK3213895T3 - cylindrical head

Info

Publication number: DK3213895T3
Application number: DK17000345.3T
Authority: DK
Inventors: Thomas Pomp
Original assignee: Famag Werkzeugfabrik Gmbh & Co Kg
Priority date: 2016-03-04
Filing date: 2017-03-03
Publication date: 2018-11-26
Also published as: DE202016004084U1; EP3213895B1; DE202016001386U1; EP3213895A1

Description

The invention relates first to a cylinder-head drill bit as described in detail in the preamble of Claim 1.

The invention therefore proceeds from a cylinder-head drill bit having a clamping shank and having a drill head, which has a centring point and an outer lateral wall with an at least substantially cylindrical outer surface, and in which, between the centring point and the outer surface, at least one main cutting edge is arranged, which extends substantially radially, wherein at least one chip passage that adjoins the flank of the main cutting edge, is open towards the circumference, passes obliquely through the drill head and interrupts the lateral wall is arranged in the drill head, and wherein the outer surface is provided with a multiplicity of narrow flutes. A cylinder-head drill bit of this type is known from US 4 134 706. A cylinder-head drill bit provided with two main cutting edges is known, firstly from the patent document of the applicant DE 197 02 423 B4 and secondly, but without any grooves, from the patent document of the applicant DE 41 15 030 Cl.

The problems of cylinder-head drill bits are explained thoroughly in said documents, and therefore a detailed repetition can be omitted here. The main aim in particular of the former document, DE 197 02 423 B4, is, in brief, to create a cylinder-head drill bit which heats up as little as possible during operation. As a solution, it is proposed, inter alia, that the outer surface of the otherwise smooth lateral wall be interrupted by what are referred to as radial outward bulges, that is, grooves. As all the exemplary embodiments show, these grooves are relatively wide and run either exactly axially or obliquely axially so that they can be used to form multiple roughing edges which then together form a core drill bit.

Narrow, outer flutes in drill bits of other designs are also already known from the prior art. For instance, what are referred to as round bevels or guide bevels in spiral drill bits are known from FR 1 274 316 A or WO 1998 35 777 Al. These round bevels, flutes or grooves are used for better concentricity, a better or additional cutting action at the spiral edges or for indicating the drilling depth.

In contrast to the relatively long and slim spiral drill bits or also long-hole drill bits, the drill bit diameter of a relatively thick and short cylinder-head drill bit is a multiple of the lateral height. In a cylinder-head drill bit, the centring point and the outer lateral surface already ensure straight drilling of a relatively large drilling diameter. At the bottom of page 3 and the top of page 4 of WO 1998 35 777 Al, a person skilled in the art finds that the spiral drill bit provided with flutes in said document is preferably intended for drilling long holes through a workpiece but not for forming usually relatively short holes, in particular blind holes. The latter is however the typical task of a cylinder-head drill bit.

However, flutes which run around the outer surface are also already known in wood drill bits of a similar design: US 6 354 773 BI discloses a wood drill bit which has multiple flutes running around its two narrow and wing-like outer surfaces. US 4 134 706 A discloses a wood drill bit of a similar design with two approximately radial main cutting edges and two roughing edges. It has some flutes running helically around its outer surface. US 3 180 379 A discloses a long-hole drill bit with a single radial cutting edge which is likewise provided with flutes running helically around its outer surface.

The invention discussed in the first-mentioned document has proven particularly effective. The invention is intended to build on this.

Proceeding from this prior art, the invention is based on the aim of developing the cylinder-head drill bit such that the process heat also unavoidably produced on the relatively extensive lateral wall during drilling is considerably reduced in order to improve the cutting power both quantitatively and qualitatively.

Proceeding from a cylinder-head drill bit of the type mentioned in the introduction, it is consequently proposed that at least two grooves intersect. A particularly distinctive pattern is produced on the outer surface of the drill head if multiple grooves or flutes run helically and with an opposing pitch such that they intersect. Their pitch can preferably be equal but can also be different.

In the first-mentioned prior art, the grooves, which are referred to as outward bulges in said document, are relatively wide and are also used to open up the outer surface but in particular to form a core drill bit having multiple roughing edges. To this end, they either run axially or have a relatively large pitch, specifically considerably greater than the diameter of the cylinder-head drill bit. The specifically intersecting flutes according to the invention initially serve the sole purpose of virtually indenting the outer surface as far as possible in order to effectively enlarge same thereby.

The formation of intersecting, relatively narrow - and also deep where necessary - flutes allows a multiplicity of flutes to be made in the outer surface. On the one hand, the actual outer surface is thereby considerably enlarged by the additional side faces of the flutes, and on the other hand, the stability of the lateral wall, the guiding height thereof, and thus the guiding function thereof are fully retained, since the lateral wall is only slightly weakened by the narrow flutes. Thanks to the now effectively inwardly enlarged outer surface, the outer contact surface with the material wall to be drilled is reduced, and the friction heat produced at the lateral wall can be dissipated better to the air surrounding the outer surface, specifically also in the flutes.

Therefore, the invention can also be used advantageously in a cylinder-head drill bit of a simple or older design, as is described repeatedly and for example in the second-mentioned document.

The feature "narrow" for the flute-like grooves should be understood here as variable and in relation to the diameter of the cylinder-head drill bit. In particular, the width of a flute can be, depending on the outer diameter, 0.5 mm to 2.0 mm: The larger the drill bit diameter, the wider - and possibly deeper - the flute can be.

The invention initially presupposes only one cylinder-head drill bit having a lateral wall and a single main cutting edge. However, it is preferably used in a cylinder-head drill bit having two to four main cutting edges.

However, it can also be provided within the scope of the invention for at least one groove or flute to extend preferably in a slightly helical manner. In this case, slightly helically is intended to mean that the pitch is relatively small, which means that the pitch is at least as far as possible smaller than the drill bit diameter, as is explained in more detail below.

In this case, such a groove or flute can be right-handed. When the drill bit rotates, an axial moment is then produced in the direction of the centring point, effectively an entry moment.

It can also be provided for at least two grooves or flutes to extend in a helical manner and parallel to one another. The aforementioned positive effect can thus be reinforced.

It has been found that it is advantageous within the scope of the invention if at least half of the outer surface is interrupted by the grooves and flutes. This results in both increased dissipation of heat and good guiding.

The cross-section of the grooves or flutes can be designed in different ways, in particular partially circular, semicircular, V-shaped or U-shaped. Here too, a particular pattern can be produced on the cylinder-head drill bit by choosing or combining cross-sections which differ in shape and/or size, and said pattern can also be used to indicate the manufacturer or provider.

All the aforementioned embodiments can already be implemented in a relatively simple cylinder-head drill bit, specifically if a smooth outer surface is available, as for example in the document mentioned second above, DE 197 02 423 B4. However, the invention is used particularly advantageously in a cylinder-head drill bit designed as in the first-mentioned document, DE 41 15 030 Cl. Such a cylinder-head drill bit is therefore designed such that the outer surface is additionally interrupted by grooves, what are known as recesses or outward bulges, that extend axially or obliquely axially and are wider than the flutes, in order to form roughing edges in the form of a core drill bit. Here, the reduction of the outer surface involved in the friction is extremely reduced, and the dissipation of the heat produced is considerably accelerated.

It has been found that the dimensions of the flutes in relation to the other dimensions of the cylinder-head drill bit play an essential role. Thus, if the pitch is small, it is proposed that the ratio of the outer diameter of the cylinder-head drill bit to the pitch of a flute be between 8 and 30 to 1, depending on the size of the diameter.

The pitch of a flute can in particular be 1 to 3.5 mm. Examples: With a diameter of 8 mm, the pitch is 1 mm; with a diameter of 30 mm, the pitch is 2 mm; and with a diameter of 60 mm, the pitch is 3.5 mm.

On the one hand, the depth of the grooves or flutes enlarges the outer surface in a positive manner, on the other hand, it must not excessively weaken the lateral wall. The larger the diameter of the cylinder-head drill bit, the deeper the groove or flute can be. It has proven very favourable if the depth of a flute is preferably 0.1 mm to 0.65 mm, depending on the diameter. Preferably, the ratio of the outer diameter of the cylinder-head drill bit to the depth of a flute should be between 80 and 160 to 1. Besides, a person skilled in the art would always avoid a greater depth of a groove or flute if the stability of the cylindrical drill bit would be threatened by excessive removal of material.

Depending on the design of the geometry of the drill head, flutes with different widths and/or depths can thus also be made: For example, a deeper and possibly also wider flute can be made at points with more "meat" in the lateral wall, such as in the root region thereof, towards the clamping shank, and, in particular in the case of a relatively large cylinder-head drill bit with a relatively thick lateral wall, for example over 40 mm or even 100 mm in diameter, without the drill head being excessively weakened.

Finally, to further improve cooling of the drill head, it is proposed that a plurality of axial flutes and/or at least one spiral flute also be arranged on the partially circular root face of the drill head which adjoins the outer surface discussed above in the direction of the clamping shank. Here too, the relatively narrow width and possibly depth of the flute(s) depends on the conditions already explained and is for the person skilled in the art to decide.

The invention gives a person skilled in the art an abundance of possibilities of designing a cylinder-head drill bit of a very simple design, or else of the specific design mentioned in the introduction, specifically with a core drill bit, such that the heat unavoidably produced during drilling at the drill head as a whole and in particular at the lateral wall is dissipated as rapidly as possible and very effectively. The design according to the invention therefore leads to a reduction in heating, a longer service life of the cylinder-head drill bit and an improved quality of the borehole produced. Furthermore, the possibility is provided of giving the cylinder-head drill bit a striking, distinct and attractive exterior.

The drawing shows exemplary embodiments of the invention, which are now described in more detail.

Fig. 1 shows a first embodiment as a development of the cylinder-head drill bit according to DE 197 02 423 B4, having a flute in the same plane and having a helical flute, and eight oblique-axial, rounded grooves intersecting virtually all the flutes.

Fig. la shows the cylinder-head drill bit of Fig. 1 in a different perspective.

Fig. lb shows the cylinder-head drill bit of Fig. la in a side view.

Fig. lc shows the cylinder-head drill bit of Fig. la in an end view.

Fig. 2 shows a second embodiment, similar to that of Fig. 1, having a flute in the same plane and having six parallel, helical flutes which intersect eight oblique-axial grooves.

Fig. 3 shows a third embodiment, similar to that of Fig. 1, having a flute in the same plane and having eight right-handed flutes which intersect eight left-handed flutes.

Fig. 4 shows a fourth embodiment, as a development of the cylinder-head drill bit according to DE 41 15 030 Cl, having intersecting flutes and corresponding to Fig. 3.

Fig. 5 shows a fifth embodiment, similar to that of Fig. 1, having a flute in the same plane and having eight right-handed flutes, the flutes intersecting the eight grooves.

Fig. 6 shows a sixth embodiment, similar to that of Fig. 4, having intersecting flutes, similar to Fig. 5.

Fig. 7 shows a drill head of a further cylinder-head drill bit, similar to Fig. 5, but having further flutes in the root region .

The cylinder-head drill bit 101 shown in Fig. 1 to lc is composed of a clamping shank 102 and an in principle virtually pot-shaped drill head 103 which comprises a centring point 104 which protrudes slightly in the drill bit axis X-X and an outer lateral wall 105 having a substantially cylindrical outer surface 106. Two main cutting edges 107 extend approximately radially between the centring point 104 and the outer surface 106. Adjoining each main cutting edge 107 in the drill head 103 there are two flanks 108 which in turn merge into two chip passages 109.

Starting from the main cutting edges 107, the chip passages 109 pass obliquely through the drill head 103 to the adjoining round part of the clamping shank 102. As a result, the chip passages 109 interrupt the lateral wall 105 into the root part 110 so that on the drill head 103 both the lateral wall 105 -and thus the outer surface 106 thereof - and the root part 110 are divided into two sections.

In total, eight grooves 111 which run obliquely and axially and have rounded bottoms are made in the outer surface 106, said grooves being referred to in the prior art as outward bulges and being used to form roughing edges 112 which together form a divided core drill bit 113. The width BN of the grooves 111 is on average approx. 6 mm here, the depth TN varies here between 0 in the root region and approx. 1 mm in the region of the roughing edges 112. The diameter D of the cylinder-head drill bit 101 is in this case 50 mm. The number of roughing edges 112 can vary and can be adapted in particular to the respective diameter of the cylinder-head drill bit. In addition to the oblique grooves 111, narrow flutes 114 are made in the divided outer surface 106, said flutes running tangentially around the outer surface 106 or coaxially to the drill bit axis X-X and in the process intersecting the grooves 111. In this case, the flutes 114 consist of a first, upper flute 114.1, which runs in the same axial plane, and a flute 114.2, which runs downwards in a helical and right-handed manner such that it runs around the outer surface 106 multiple times.

In this case, with this diameter D, the width B of a flute 114, 114.1 and 114.2 is approximately 1.6 mm, the depth T is approximately 0.6 mm and the pitch S is approximately 3.5 mm. The cross-section Q is partially circular with a radius R of approximately 1.2 mm. Owing to the very large indentation of the outer surface 106 - specifically by the oblique-axial grooves 111 on the one hand and the tangential flutes 114 intersecting the grooves 111 on the other hand - the original outer surface is reduced to less than half, but the effective outer surface is considerably enlarged by the additional side walls of the grooves 111 and flutes 114.

Fig. la to lc show the cylinder-head drill bit 101 according to Fig. 1 in further views to illustrate the three-dimensional structure thereof better.

Fig. 2 shows a cylinder-head drill bit 101b like the one on which Fig. 1 is based. In this case, although the first, upper flute 114.1 likewise extends in the same axial plane, under it there are six parallel, right-handed, helical flutes 114.3 which intersect the grooves 111.

Fig. 3 shows a cylinder-head drill bit lOld like the one on which Fig. 1 is based. In this case, the first, top flute 114.1 extends in the same axial plane but under it there are eight parallel, somewhat spaced-apart, right-handed, helical flutes 114.4 which intersect eight correspondingly designed and arranged but left-handed, helical flutes 114.4. The pitch S is somewhat larger here than in the above embodiments with a rotation direction.

Fig. 4 shows a cylinder-head drill bit lOle which corresponds substantially to that of Fig. 1 but has the simpler form of what is known as a Forstner bit: In this case, there is no core drill bit with roughing edges like that on which Fig. 2 is based, since the grooves 111 have been omitted here, as is shown in principle in DE 41 15 030 Cl. Here, the flutes 114.1 and 114.4 extend as explained with reference to Fig. 3. In particular, the intersection profile of the flutes 114.4 which produces a diamond pattern can be seen clearly here.

Fig. 5 shows a cylinder-head drill bit lOlf like the one on which Fig. 1 is based. In this case, the first, top flute 114.1 also extends in the same axial plane, but under it there are eight flutes 114.5 which run parallel and somewhat spaced-apart from one another and form right-handed helices. All the flutes 114.1 and 114.5 intersect the eight grooves 111.

Fig. 6 shows a cylinder-head drill bit lOlg like the one on which Fig. 4 is based. The flutes 114.1 and 114.5 extend as explained with reference to Fig. 5 and partially intersect.

Fig. 7 shows a drill head 113 of a further cylinder-head drill bit lOlh according to the invention which corresponds approximately to the structure according to Fig. 1. The flutes 114 intersect the grooves 111. In this case, the root surface 115, that is, the surface divided in two between the outer surface 106 and the round part of the clamping shank 102, is likewise provided with flutes 116. In this case, any rounded portion situated between the outer surface 106 and the root surface 115 adjoining it at an angle can also be provided with flutes 116.

These flutes 116 can either be flutes running concentrically to the drill bit axis X-X or consist of one or more flutes running in a spiral manner. In this case too, these flutes 116 can correspond or be similar in shape and size to the described flutes 114 in the outer surface 106.

If the thickness of the wall 105 or the root 110 - which also depends on the diameter of the drill head 113 - allows, these flutes 116 can also be substantially deeper and/or wider. Especially since the root surface 115 does not have a guiding function like the outer surface 106 but is used here to dissipate the friction heat produced at the lateral wall 105 and at the core drill bit 113.

List of reference symbols: 101 Cylinder-head drill bit 101b Cylinder-head drill bit lOld Cylinder-head drill bit lOle Cylinder-head drill bit lOlf Cylinder-head drill bit lOlg Cylinder-head drill bit lOlh Cylinder-head drill bit 102 Clamping shank 103 Drill head 104 Centring point 105 Lateral wall 106 Outer surface 107 Main cutting edge 108 Flank 109 Chip passage 110 Root part 111 Groove 112 Roughing edge 113 Core drill bit 114 Flute 114.1 Flute 114.2 Flute 114.3 Flute 114.4 Flute 114.5 Flute 115 Root surface 116 Flute B Flute width BN Groove width D Diameter S Pitch T Flute depth TN Groove depth X-X Drill bit axis

Claims

A cylinder head drill (10D to 10D) with a clamping shaft (102) and with a drill head (103) comprising a centering tip (104) and an outer casing wall 1 (05) having at least one substantially cylindrical outer surface (106) ) and wherein at least one main cutter (107) extending substantially radially between the centering tip (104) and the outer surface (106) is disposed, with at least one chip channel located in the drill head (103) (109), which joins the free face (108) of the head cutter (107), which is open towards the scope and which penetrates obliquely through the drill head (103) and breaks off the casing wall (109), and the outer face ( 106) is provided with a large number of narrow grooves (114.1, 114.4, 114.5), characterized in that at least two grooves (114.1, 114.4, 114.5) intersect.

The cylinder head drill (101 to 10h) according to claim 1 or according to the preamble of claim 1, wherein the outer surface (106) is interrupted by a large number of axially or inclined axially extending and wider grooves (111 to the grooves (114 to 114.5)). ) for forming pre-cuts (112) in the form of a drill bit (113), characterized in that the width (B) and / or depth (T) of two or more grooves (114 to 114.5) are designed differently.

Cylinder head drill (101) according to claim 1 or 2, characterized in that two to four main cutters (107) are located.

Cylinder head drill (101) according to one of claims 1 to 3, characterized in that at least one groove (114.1) proceeds at the same axial level.

Cylinder head drill (101) according to one of claims 1 to 4, characterized in that at least one groove (114.2) proceeds in a spiral shape.

Cylinder head drill (101b, 101c) according to claim 5, characterized in that at least two grooves (114.3) extend spirally and parallel to one another.

Cylinder head drill (101) according to one of claims 1 to 6, characterized in that at least half of the outer surface (106) is interrupted by the grooves (111) or the grooves (114, 114.1, 114.2).

Cylinder head drill (10h) according to one of claims 1 to 7, characterized in that several grooves (116) extending axially and coaxially to the drill axis (X-X) are located on the foot surface (115) of the drill head (103). / or at least an axially and helically extending groove (116) relative to the drill axis (X - X).