DE8530884U1 - Carbide or ceramic drill bit blank - Google Patents

Description

·· · e · t «at

2 -

FRIED. KRUPP GESELLSCHAFT LIMITED LIABILITY

in food

Carbide or ceramic drill bit blank

The application relates to a hard metal or ceramic drill bit blank with at least one helical shape running internal flushing hole.

The hard metal or sintered drill bit blanks mentioned are known, for example, from EP 0 118 035 A1. From the produced by the helical twist described in the said European patent application The chip chambers still have to be milled out of blanks, which is not insignificant

Costs arise. For making the carbide drill bit a.a.O., page 10, suggests a circular cylindrical sintered metal blank to extrude by means of an extrusion device in which a compression molding nozzle is arranged.

The helically running cooling channels should be produced by twisting the sintered metal blank emerging from the extrusion device with an angular velocity coordinated with the material flow, the desired drill geometry and the helix of the cooling channels uniform axial guidance of the Sintermetallro ^h astride and obtain a likewise continuous and steady twisting motion.

85/155 I.
Vo / B

t · «» it »

Accordingly, in addition to the extrusion die, additional twisting devices are disadvantageous
as well as corresponding control and regulation bodies are required. i

This results in the underlying of the invention

A difficult task, a hard metal or ceramic raw > ■

f ling, in which for further processing to \

Drill a minimum of grinding work is necessary to dig \ the chip spaces. j

The task is on the one hand by the patent application |

Claim 1 described drill blank solved. Pre |

ti partly the helical |

arranged grooves as approaches for the later span i

i chambers of the drill. The chip chambers are thus ί

already largely preformed, so that only i

Layers of insignificant thickness are removed '

have to. The drill blank can be of any length
and if necessary to the length or lengths corresponding to the later drill tip

be cut off. To make the drill :

the finished drill tip with a
Carrier piece in known from the prior art j

Way connected. I.

A further development of the invention are the f

Grooves to the flushing bores at an angle of 0 ° *

Arranged up to 90 °, ie the respective lines which connect the groove centers and the flushing bore centers in cross-section to one another are perpendicular to one another or at an acute angle
to each other or run in parallel.

• ti

t · · «I ItI

4 -

Instead of twisting the sintered blank only after it has left the extrusion device, as previously suggested, the twisting and the production of the flushing bores can be ensured in one process step with the extrusion, if
the hard metal or the ceramic heated to the extrusion temperature is pressed through the space formed by a mandrel and a nozzle, the strand through in the direction of the extrusion guide

iÖ one or more helically extending ones provided on the inner surface of the die (nozzle)
Web (e) is guided and during the pressing process on the mandrel ending in front of the nozzle interior
or several attached wires made of an elastic

see material with the desired flushing hole diameter, possibly in the desired distance of the
The flushing bores protrude into the nozzle. The elastic ones provided on the mandrel of the extrusion die
During the twisting process, wires create flushing bores corresponding to their diameter, their

uniform geometry is not destroyed again by subsequent work steps. Since at the same time with the Extrusion over the guide bar or bars causes the twist, this also depends

no longer depends on external variables such as the material flow rate in the extrusion press. Regardless of the speed at which the punch presses the material into and through the nozzle, there will always be
causes a uniform slope of the hard metal or ceramic drill blank. The slope of the
Grooves in the blank preferably determine the slope of the chip chamber and can vary from drill type to drill type, in extreme cases even to straight grooves. The evenness of the slope is increased if the guide over the said bridge

MIlM "I Il Il H

r · «if * * ι ι

ρ, ι ι I · * · * · II »ι

helix over at least 90 °, preferably over at least 180 °. From apparatus, manufacturing and procedural reasons, a guide this is the web, preferably, which is semicircular in cross section and whose radius is at least 1 mm.

Experience has shown that the spiral angle of the helical web in the nozzle is chosen to be somewhat larger should be than the desired angle for the blank, usually the allowance is approx. 3 up to 7 '

If the wires are supported by spacers up to the level of the nozzle inlet space, then they are increased advantageously the uniformity of the parallel! 15 lelen course to each other or to the circumferential groove.

The wire should be elastic so that it is forced to twist when twisting the hard metal or ceramic pressed material survives without breakage, e.g. Cu wire or a Cu alloy wire is preferred used.

Depending on the intended use of the drill, the final from the blank is to be made, it can be useful to have flushing holes with different Provide diameters. In such a case there is a mandrel with appropriately sized wires to use.

With regard to a good flowability of the pressed material the mandrel is preferably tapered essentially conically on the side facing the nozzle, so that the elastic wires on the cone shell

ft * · * I · ■ II III

MM · · »· 4

6 -

step. The cone shape can end in a point; i or in a substantially cylindrical spacer to support the wires - one Type center pin - pass over.

Embodiments of the invention are shown in Drawings shown. Show it

Fig. I, 2 a Böhrerrohüng with incorporated Groove and flushing holes in different sectional views,

3 shows a drill blank in cross-sectional view.

The hard metal drill blank shown in Fig. 1, 2 has two helically circumferential grooves with a semicircular wall, the radius r 1 mm amounts to. The grooves are "pre-deformed" chip chambers, which is later used to make the drill bit completely be ground out. In addition, the carbide drill blank has two flushing bores 2, here a diameter of 0.8 mm, which run parallel to the grooves 1. The connecting lines of the grooves 1 and that of the flushing bores 2 form an angle of 90 °, whereas in FIG. 3 an embodiment is shown with an angle of ^ A = 0 °. Between every angle dimension is possible as well as an eccentric arrangement in which both flushing bores lie beyond an imaginary cross-sectional center line.

I · · · · · ti III

r ■ · »· t ··« ι · ι

a · · · · aiii

'I * * * * 1 «Ii

7 -

From this drill blank is used to manufacture the Cut off the drill bit a correspondingly long piece, the chip chambers (cutting lips) ground in and the drill bit is ground where the two flushing bores end.

Claims (2)

Expectations j. 1. Carbide or ceramic drill blank with min- I least one helical internal flushing bore, thereby .; marked that parallel to * 5 one or the flushing bores (2) on the circumference several helical grooves (1) are provided. 2. hard metal or ceramic drill blank according to 1 claim 1, characterized in that the Grooves (1) are arranged at an angle ( A-) of 0 ° to 90 ° to 10 of the flushing bores (2). 185/155 I.
IVo / B