WO2004098818A2

WO2004098818A2 - Prismatic cutting insert

Info

Publication number: WO2004098818A2
Application number: PCT/AT2004/000154
Authority: WO
Inventors: Hans-Jörg PUCHER; Wolfgang Koch; Martin Maringele
Original assignee: Ceratizit Austria Gesellschaft M.B.H.
Priority date: 2003-05-08
Filing date: 2004-05-06
Publication date: 2004-11-18
Also published as: AT6851U1; WO2004098818A3

Abstract

The invention relates to a powder-metallurgical prismatic cutting insert (1) for use in a machining process. Said cutting insert (1) is configured from parts (2) that are positioned in an exact fit in relation to one another and are interconnected in a material union, obtained by thermal treatment. According to the invention, in order to position the individual parts (2) in an exact fit, at least some sections of the connecting surfaces (3) of said parts comprise an interlocking gearing, at least part of said respective sections consisting of multiple rows of teeth (4), whereby the adjacent rows of teeth (4) of one section run approximately parallel to one another.

Description

PRISMATIC CUTTING INSERT

The invention relates to a powder-metallurgically produced, prismatic cutting insert for machining, which is formed from precisely positioned parts which are integrally connected to one another by heat treatment.

A corresponding cutting insert is described in EP 0365 505 B1. The cutting insert according to this prior publication has two identical halves, which are integrally connected by sintering along a central plane. For the exact positioning of the two halves relative to one another, each of the two connecting surfaces has at least one recess and at least one projection, which are arranged separately from one another and on an imaginary circle, the center of which coincides with the center of each powder body.

The disadvantage here is that, due to pressing tolerances, dimensional deviations between the projections and the recesses of the halves positioned with respect to one another can occur. If the respective projection is somewhat smaller in size than the respective recess, there is play between the two halves, which makes it difficult to position them exactly with one another.

If, on the other hand, the respective projection is somewhat larger than the respective recess, it can happen that the connecting surfaces of the two halves are slightly spaced from one another, so that there is only an insufficient material connection during sintering.

The object of the present invention is therefore to achieve as good a contact as possible with as little play as possible between the connecting surfaces of the individual parts when positioning one another.

According to the invention, this is achieved in that the connecting surfaces of the individual parts for the precisely fitting positioning at least partially have interlocking teeth, each of which, at least via one Section consists of a plurality of rows of teeth, with immediately adjacent rows of teeth of a section running approximately parallel.

Because a plurality of rows of teeth are arranged on the connecting surfaces, the manufacturing tolerances on the connecting surfaces of the individual parts during pressing are divided according to the number of individual rows of teeth. The greater the number of rows of teeth, the greater the achievable positioning accuracy of the individual parts to one another and the better the contact between the mutual connecting surfaces. If the individual rows of teeth run exactly parallel in one direction only, optimal, immovable positioning of the parts relative to one another can only be achieved in the direction perpendicular to the rows of teeth. The parts can be moved against each other parallel to the individual rows of teeth, so that when the parts are placed one on top of the other, they must be exactly aligned with each other.

It is therefore advantageous if the connecting surfaces of the individual parts each have at least two sections with individual rows of teeth running in parallel, the individual rows of teeth of at least two different sections each running in different directions. In this way, when the individual parts are put together correctly, the parts are optimally and securely positioned relative to one another.

It is advantageous to produce a double-sided, positive cutting insert, which has two opposing rake faces, each of which is delimited by cutting edges, which in turn merge into open areas that run at an acute angle α to the rake face, by two identical halves, each of which the enveloping plane of the ridge lines of the tooth rows runs parallel to the cutting edge plane. In this way, double-sided positive cutting inserts, which would otherwise be difficult to produce using press technology, can be produced using a single pressing tool.

Furthermore, it is particularly advantageous if the connecting surfaces have individual rows of teeth that are at the center of each Cut connecting surfaces. Since the distance between the ridge lines of the rows of teeth from the center is becoming ever smaller and the production of these zones is problematic when pressing, it is advisable to exclude a certain center area from the toothing in cutting inserts without a central hole. In the case of cutting inserts with a center hole, this is usually achieved automatically by the recess in the center hole.

A further advantageous embodiment of the invention provides that the connecting surfaces each have four sections arranged in the manner of a segment of a circle, each with rows of teeth running in parallel, the rows of teeth of sections lying next to one another running at 90 ° to one another.

A method for producing a cutting insert made of hard metal according to the invention consists in that two identical halves are each pressed out of the hard metal powder mixture in the same form of a die pressing tool, that the pressed halves with the connecting surfaces are positioned precisely in relation to one another and that the halves joined in this way are at a sintering temperature of 1,350 ° C to 1,550 ° C are sintered for a period of 0.5 to 2 hours. Under these conditions, there is a perfect material connection between the two halves to form a one-piece cutting insert.

The invention is explained in more detail below with reference to figures.

Show it:

Figure 1 shows two identical halves for producing an inventive

Cutting insert in separate, correct position to each other, in side view Figure 2 of the finished from the two identical halves of Figure 1

Cutting insert in side view with still indicated

Dividing line Figure 3 is a half for producing an inventive

Cutting insert according to Figure 1 in plan view of the

interface Figure 4 shows a half for producing an inventive

Cutting insert according to Figure 1 in plan view of the rake face Figure 5 shows another embodiment of a half for producing a cutting insert according to the invention in plan view of the

6 shows another embodiment of a half for producing a cutting insert according to the invention in a top view of the

interface

A cutting insert according to the invention with a positive cutting geometry for double-sided use has two opposite rake faces -5-, each of which is delimited by eight cutting edges of the same length -6-. To produce the cutting insert -1 - two identical halves -2- were pressed from a hard metal powder mixture in the same form of a die press tool. The mutual connecting surfaces -3- of the individual halves -2- each have a toothing with a sinusoidal cross section over the entire surface, the individual rows of teeth -4- converging at the center -10- of the connecting surfaces -3-. This results in a large number of rows of teeth -4- tapering conically towards the center, with immediately adjacent rows of teeth -4- running approximately parallel to one another. Since the cutting insert -1- has a center hole -11 -, the ends of the rows of teeth -4- are still sufficiently spaced from the center -10- of the connecting surface -3- so that their contour can be easily produced with the press tool. The individual halves are positioned correctly in relation to each other with the respective toothed connecting surfaces -3-. The tapered rows of teeth -4- automatically result in a very precise immovable positioning of the halves -2- to each other.

The halves -2- thus joined were then sintered in a sintering furnace at a sintering temperature of 1,450 ° C. for a period of 1 hour.

A cutting insert -1- produced in this way has a perfect material connection between the two halves -2-. To this In particular, two-sided, positive cutting edge geometries, in which the free surfaces -7- enclose an acute angle α with the cutting edges -6-, can be produced without any problems. One-piece cutting inserts with positive cutting geometry would otherwise not be economically feasible, since the cutting insert would be damaged due to the undercut which the free surfaces of the two sides form after being pressed when ejected from simple, undivided dies.

Two different embodiments in the design of the connecting surfaces -3- on individual halves -2- for producing cutting inserts -1- according to the invention are shown in FIGS. 5 and 6. These halves -2- each have on their connecting surfaces -3- four symmetrical sections adjoining each other in a segment of a circle, each section having rows of teeth -4- running parallel to one another and the rows of teeth -4- adjoining sections running at 90 ° to one another.

In the embodiment according to FIG. 5, the rows of teeth -4- each run parallel to the central cutting edge -6-, while the rows of teeth -4- in the variant according to FIG. 6 run perpendicular to the central cutting edge -6-. With these variants, too, a precise, immovable positioning of the respective halves -2- relative to one another is achieved. This type of toothing formation is particularly advantageous when the cutting inserts to be produced do not have a center hole, since then, even with such cutting inserts, a perfect formation of the toothing down to the center area is made possible.

Claims

claims

1. Powder metallurgically produced, prismatic cutting insert (1) for machining, which is formed from precisely positioned parts (2) which are integrally connected by heat treatment, characterized in that the connecting surfaces (3) of the individual parts (2) for Precise positioning at least partially have interlocking teeth, each of which consists of a plurality of rows of teeth (4) at least over one section, with immediately adjacent rows of teeth (4) of a section running approximately parallel.

2. Cutting insert (1) according to claim 1, characterized in that the connecting surfaces (3) each have at least two sections with parallel rows of teeth (4), the rows of teeth (4) of at least two different sections each running in different directions.

3. Cutting insert (1) according to claim 1 or two, characterized in that the cutting insert (1) has two opposite rake faces (5), each of which is delimited by cutting edges (6), which in turn merge into open areas (7), which in run at an acute angle α to the rake face (5) and that the cutting insert (1) consists of two identical halves (2), each of which has the enveloping plane (8) of the ridge lines of the tooth rows (4) parallel to the cutting edge plane (9).

4. Cutting insert (1) according to one of claims 1 to 3, characterized in that the connecting surfaces (3) have rows of teeth (4) which intersect at the center (10) of the individual connecting surfaces (3).

5. Cutting insert (1) according to one of claims 1 to 3, characterized in that the connecting surfaces (3) each have four sections arranged in the manner of a segment of a circle, each with parallel rows of teeth (4), the rows of teeth (4) of adjacent sections at 90 ° to each other.

6. The method for producing a cutting insert (1) made of hard metal according to claim 3, characterized in that the two halves (2) are each pressed in the same form of a die pressing tool from the hard metal powder mixture, that the pressed halves (2) with the connecting surfaces (3 ) are positioned precisely in relation to each other and that the halves (2) thus assembled are sintered at a sintering temperature of 1,350 ° C to 1,550 ° C for a period of 0.5 to 2 hours.