WO1994014558A1

WO1994014558A1 - Metal-cutting tool

Info

Publication number: WO1994014558A1
Application number: PCT/DE1993/001161
Authority: WO
Inventors: José AGUSTIN PAYÀ; Erwin Stallwitz
Original assignee: Krupp Widia Gmbh
Priority date: 1992-12-28
Filing date: 1993-12-03
Publication date: 1994-07-07
Also published as: CN1090801A; DE4244316A1; DE4244316C2

Abstract

The invention concerns a metal-cutting tool with a tool-holder having at least one recess (11) for a replacable cutter insert (14). The recess has a bearing surface (112) which matches the shape of the cutter insert and at least one lateral locating face (111) which is cylindrical or truncated-conical in shape, the cutter insert (14) and the recess having indexing means (13, 19; 22, 23; 24 to 32) which enable the position of the cutter insert to be determined unequivocally and to be aligned accurately with respect to the tool-holder._________________________________

Description

description

Cutting tool

The invention relates to a cutting tool with at least one cutout for a replaceable cutting insert, the cutout in each case having a contact surface adapted to the cutting insert geometry and at least one cylindrical or frustoconical segment or conical side contact surface.

Cutting inserts which are interchangeably arranged in tool holders have the advantage that the actual tool can be replaced by a new one after wear, which avoids long downtimes as well as higher costs if parts not exposed to wear (such as the tool holder) ) must be replaced with. Further progress was also made by the so-called indexable insert, which, after wear of a cutting corner or cutting edge, could be positioned in the insert seat of the tool holder by turning such that a next, previously unused cutting edge can be used. Indexable inserts are known in practically all machining processes, such as turning, milling, broaching, grooving, turning-broaching or turning-turning-broaching or similar variants.

DE 26 53 222 A1 also discloses a cutting tool on which at least a first localization element is designed in the form of a projection and that the basic tool body forms a fastening support on which at least a second localization element designed as a recess is formed. However, the above-mentioned localization elements are designed such that they can be inserted into one another, so that the insert and the support are fixed in a certain selectable, relative orientation to one another a relative displacement between the insert and the support is prevented if these are firmly clamped together. Apart from the fact that this is not a cutting tool with a cylindrical or truncated-cone-like or conical lateral contact surface, the localization elements mentioned serve as positive locking and clamping elements with the risk of geometric overdetermination.

DE 28 26 564 C2 relates to an insert holder which is adjustably secured to an elongated shaft in the form of a cassette and on which a triangular indexable insert is positioned. The insert holder has a generally cylindrical main part and an insert support part protruding from the side surface of the main part, this large-volume part having a through hole for receiving a screw bolt, with which the insert holder is fastened to the tool holder. To align the angular position of the insert holder relative to the shank, an adjusting device is provided which has angularly arranged recesses on the surface of the insert holder as well as an adjusting and locking screw which is in screw connection with the upper arm of the shank of the tool holder, optionally to come into engagement with one of the depressions on the surface of the insert holder. However, this embodiment requires a large amount of space.

DE 38 18 970 C1 also describes a tool on which a cutting plate held in a receptacle of an intermediate plate is fastened, the intermediate plate being rotatable in an arcuate recess in the tool carrier and being lockable in several angular positions relative to the tool carrier, for which purpose the Intermediate plate or the recess carries approaches that can be inserted into one of several recesses of the same cross section of the recess or intermediate plate. The intermediate plate has a receptacle for a triangular indexable insert. DE 33 21 184 AI describes a turning tool with a holder for an interchangeable cutting insert, which has a recess in which an increase in the support surface of the holder engages with play in the untensioned state. The aim of this is to ensure that the countersunk screw can be easily inserted into the bore of the holder through the bore of the cutting insert when it engages in the fastening hole. If the countersunk screw is tightened for fastening the cutting insert, the respective surfaces of said recess and said elevation opposite when the screw is tightened form the lateral (and only) contact of the cutting insert with the holder, since the rear insert free surface is at a distance from the opposite insert seat wall surface lies. Furthermore, the cutting insert can have recesses in the floor or in the open space, into which two pins provided on the holder engage when the cutting insert is placed on the holder and which, with their possibly oblique end faces of the recess, form the contact surfaces. This can also result in the risk of the cutting insert jamming.

Insofar as the cutting inserts are not necessarily aligned due to their outer geometry, to which the insert seat of the tool holder is adapted, as is the case, for example, with triangular, square or hexagonal cutting inserts, the cutting inserts must be adjusted in each case. This applies in particular to those cutting inserts which have chip-forming elements on their rake face which are aligned with respect to the direction of chip removal. If the actual chip run-off angle and the optimum chip run-off angle desired in relation to the chip form elements do not match, the chip form elements may become at least partially ineffective or wear of these parts may increase. The same also applies with regard to other rake face, free face or cutting edge geometries, insofar as these require a special alignment of the insert with respect to the workpiece. In the case of cutting inserts of this type, which are either circular in a plan view or are shaped in the form of a segment of a circle in their contact surface with the tool holder, it is necessary to check after each realignment of the cutting insert whether the set position satisfies the adjustment instructions.

It is an object of the present invention to further develop a cutting tool of the type mentioned at the outset in such a way that this allows the cutting inserts to be clearly aligned without the risk of jamming, in a manner which is easy to handle and without great construction effort.

This object is solved by the cutting tool according to An¬ claim 1., the novelty is that the cutting insert and the recess have a _{<predetermined} by the arrangement location of the cutting insert in respect to the holder enabling indexing means, the other border of each inein¬ recesses and There are ridges between which there is play of 0.1 mm to 0.2 mm on at least one side. There is clearance in the form of play between the depressions and the elevations of an indexing agent, so that an overdetermination of the position of the cutting insert in relation to the cutting insert seat in the tool holder is avoided, which in the worst case can lead to jamming. All geometric shapes can be used as indexing means, which enable the cutting insert to be oriented in relation to the tool holder receptacle without the interlocking elevations and depressions being positively locked. Special embodiments are those of a bolt, a pin or a spherical cap, which are opposed by corresponding recesses, grooves or bores. In practice, the manufacture of indexing means does not involve a great deal of effort since, for example, depressions to be made in the base surface can be introduced directly during powder metallurgical pressing of the sintered body, as well as other chip-forming elements. Corresponding applies to the production of tool holders surface in their contact ^¬ or lateral contact surface bolts, caps, or may be arranged son¬ BUSI ESS. The indexing means consist regularly of a positive and a negative part (male-female) which interlock so that only one or more predetermined positions of the cutting insert with respect to the tool holder recess are possible.

According to a further embodiment of the invention, the indexing means can additionally be designed as a fixation or anti-rotation device, for example absorbing cutting forces or additional torques. The indexing means can be attached either in the cylindrical segment-like side wall of the tool holder or in the base surface or in both parts. The same applies to the corresponding indexing medium parts of the cutting insert. This makes it possible, for example, to use one and the same holder of a tool holder for different types of cutting inserts, one type of which has indexing means in the side surface (free area), while the other type has indexing means in the ground, in this case designed as elevations.

According to a further embodiment of the invention, the indexing means are shaped polygonally asymmetrically, so that they are unambiguous with respect to a type of cutting insert.

In order to allow the operator easy control over the correct positioning of the cutting inserts in the recess of the tool holder, the depressions in the transition to the base or side surface of the cutting insert or the corresponding corresponding surfaces of the tool holder are designed with sharp edges. Driving over a "corner" or sharp edge is easier to determine than driving over a "smooth transition". Possible with the indexing agents are also combinations of bolts with spherical caps or similar variants, insofar as the tolerance dimensions to be observed in the game still allow a sufficient orientation of the cutting inserts in relation to the insert seat.

If, in special cases, a base plate is used between the cutting insert and the support surface in the tool holder, the base plate (instead of the support surface of the tool holder) is equipped with the indexing means, which correspond to the corresponding indexing means of the base surface of the cutting insert.

According to a further embodiment of the invention, the indexing agent parts are designed to penetrate through the base plate or the base plate is itself indexed relative to the support surface in the tool holder.

Exemplary embodiments of the invention are shown in the drawings. Show it

1 is a partial view of a tool holder with recess for a cutting insert,

Fig. 2a shows a circular cutting insert in a

Top view of the base area and

2b is a sectional view along the line A - A,

3 shows a sectional view along a line A - A of the cutting insert according to FIG. 2a, which is inserted into a recess of a tool holder according to FIG. 1,

4 shows a circular cutting insert with indexing means in the lateral (cylinder jacket) surfaces, 5 shows a tool holder with an inserted cutting insert in relation to various cutting forces,

6a to i different possibilities of indexing means,

7a to d different cutting insert shapes in one

Top view where indexing is possible and

7e to g are cross-sectional views of the cutting inserts according to FIGS. 7a to d.

1 shows a tool holder 10 with a recess 11, which is delimited by a cylindrical or truncated-cone-like side wall part 111 and a bearing surface 112. As is known in the prior art, the recess 11 is designed as a cutting insert seat and is geometrically open ¬ taking cutting insert adapted. Also known are a threaded fastening hole 12 for receiving a clamping screw which projects through a cutting insert. According to the invention, the bearing surface 112 has a vertically protruding bolt 13 as a (male) part of the indexing means.

A cutting insert for the recess 11 according to FIG. 1 can be seen from FIG. 2a. This cutting insert 14 has a circular shape, a central fastening hole 15 and a plateau 16 with individual chip shaping elements 17 directed towards the cutting edge. Following the cutting edge, a chamfer 18 or a chip shaping groove or the like can also be arranged.

The innovation of this cutting insert 14 is that it has trough-shaped recesses 19 on opposite sides, which are shown in cross section in FIG. 2b. Form The recess 19 can be in the form of a blind hole, it can also be angular, rounded, trapezoidal or, as shown, arcuate with an opening angle α. The depth H of the recess 19 is greater than the height of the bolt 13 insofar as it protrudes from the surface 112.

The type of indexing can be seen from FIG. 3, in particular that the bolt height 13 must be smaller than the depth of the recess 12. There is a distance, a play 20 of to, between the bolt 13 and the wall of the recess 12 adhered to 2/10 mm. This prevents overdetermination. Instead of the bolt 13, an elevation based on the contour of the recess 19 can also be selected, for example in the form of a spherical cap or an ellipsoid of revolution or other three-dimensional conical shapes. The interlocking elevations and depressions can also be designed in the manner of a key lock system as additional securing elements. If an indexing bolt is used, the number of recesses 19 in the cutting insert depends on how often this cutting insert is to be rotated through an angle. In the present case with two recesses 19, only a single turn is possible since all other angular positions are blocked.

Another possibility of indexing, namely via the side surface (free surface) 21 of a cutting element 14, is shown in FIG. 4. The same parts of this cutting element are identified by the same reference numerals as in FIG. 2a. In the side surface, each at a distance from the cutting edge, the cutting insert 14 has sawtooth-shaped depressions 22 which together with a bolt 23 form an indexing.

5 shows which cutting forces F 1 to F 3 occur and how these are compensated by reaction forces G 1 to G 3. Here, the indexings 13/19 can possibly act as abutments, in particular with forces F ^ and F3. 6 shows a selection of possible indexings. 6a to e all lie in the side surface of the circular cutting insert there. The indexings can be four spherical caps as raised parts 24 or corresponding recesses 25, which correspond to respective recesses or raised parts of the side surface 111 (see FIG. 1). In the embodiment according to FIG. 6c (for clarification in an exaggerated representation) smooth-faced millings 26 have been created which, in contrast to the indexings 24 and 25, can possibly also extend into the cutting edge area. The cutting insert according to FIG. 6d has four blind bores 27, while the cutting insert according to FIG. 6e has a bolt 28.

6f to 6i show indexing parts in the base surface of the cutting insert, possibly in the two rake faces in indexable inserts. For example, the cutting insert can have a diagonally extending recess 29 or four crosswise arranged longitudinal ribs 30 or three or more raised spherical caps 31, 32, which correspond to corresponding beads, grooves or dome-like recesses. As shown in FIG. 6i, the recess of the cutting insert can also have a polygonal, completely asymmetrical shape 32, which can also serve as a securing element with regard to a corresponding socket in the support. All indexings are possible both in a corresponding manner in the support surface of the tool carrier 10 and in a washer arranged thereon, which can itself be indexed with respect to the support surface.

FIG. 7 shows part of the cutting inserts for which the present invention is of importance. The individual cutting inserts are circular according to FIG. 7a or, according to FIGS. 7b and 7c, each have plan segment-like contact surfaces 33 in plan view, while the respective cutting edges on the opposite side can have the most varied contours. 7e to g each show sections through known cutting inserts, from which the rake face geometry is clear, in particular chip recesses 34 as well as plateaus 35 and also beveled open faces 36. The cutting insert according to FIG. 7f can be used as an insert on both sides.

A steel crankshaft was machined radially and axially using a RNMX 1205 Mo / P-CVD 2 grade, with a depth of cut between 0.5 and 3.0 mm and a feed between 0.35 and 0.5 mm / v and the cutting speed was 160 to 400 m / min. The tool life could be increased by a factor of 4 to 5 compared to conventional machining with a machining time reduced by approx. 10%.

In another test, the RNMX 1205 Mo / HK 150 grade is used for radial and axial machining with a depth of cut of 2.5 mm, a feed rate of 0.35 to 0.45 mm / v and cutting speeds of 175 to 190 m / min have been used. The amount of tool life for conventional machining could be increased by a factor of 3 to 4. The processing time was reduced by approx. 10%, with an additional reduction in noise during processing.

Claims

1. Cutting tool with a tool holder (10) having at least one recess (11) for an exchangeable cutting insert (14), the recess (11) each having a bearing surface (112) adapted to the cutting insert geometry and at least one cylindrical or has a truncated cone-like or conical lateral contact surface (111), characterized in that the cutting insert (14) and the recess (11) enable a position of the cutting insert (14) with respect to the holder (10) which is predetermined by their arrangement (13, 19; 22, 23; 24 to 32), which each consist of interlocking recesses (19) and elevations (13), between which a play (20) of 0.1 mm to 0.2 mm to at least one Side exists.

2. Cutting tool according to claim 1, characterized gekennzeich¬ net that the elevations (13) from a bolt, a pin or a spherical cap and the depressions consist of a blind bore or milling (19).

3. Cutting tool according to one of claims 1 or 2, da¬ characterized in that the indexing means (13, 19; 22, 23; 24 to 32) is additionally designed as a fixing or anti-rotation device.

4. Cutting tool according to one of claims 1 to 3, characterized by the fact that the cutting insert has the indexing means on its side surface (33) facing the contact surface (111) of the tool holder (10) and / or in its base surface.

5. Cutting tool according to one of claims 1 to 4, characterized by the fact that the indexing means (32) consist of polygonal asymmetrical shapes.

6. Cutting tool according to one of claims 1 to 5, da¬ characterized in that the recesses in the transition to the base or side surface of the cutting insert are sharp-edged.

7. Cutting tool according to one of claims 1 to 6, da¬ characterized in that between the cutting insert (14) and the bearing surface (112) in the tool holder (10) a washer is arranged, the parts of the corresponding to the parts in the cutting insert base Indexing means (13, 19; 22, 23; 24 to 32).

8. Cutting tool according to claim 7, characterized gekennzeich¬ net that the indexing means reach through the washer or the washer is indexed relative to the support surface (112) in the tool holder (10) itself.