Title of Invention

CUTTING INSERT FOR MILLING CUTTER

Abstract

ABSTRACT OF THE INVENTION: Disclosed herein is a cutting insert (10) with a substrate body having mainly a cubical fonn, which as an indexable insert is provided with 8 active (usable) cutting edges with two larger plain surfaces, (II, 12) parallel to one another and with a clamping bore (19) passing through them an adjoining these to larger surfaces four lateral surfaces, namely two small end surfaces parallel to one another (15) at the front face and two larger ioagitadinal surface (17). Each of these two larger longitudinal surfaces have, 9i the middle along their longitudinal axis, a rib (stay) (20), which is projecting and which serves as a supporting surface in the clamping of the indexable insert (10) in a tool holder The larger surfaces (U, 12) merge over connecting surfaces into the small end surfaces (15) in such away, that this results at the longitudinal surfaces (17) in correspondingly shaped cutting edges (18) as border lines to the small and surfaces (IS, 16) m the comer region. Hereby the long cutting edges (U) as borderlines between the larger surfaces (11, 12) and the respective adjoining longitudinal surfaces (17) are bent in the shape of an arc, so that a body, which is mirror symmetrical to the longitudinal center plane and to the transverse center plane, is obtained. The catting insert (10) is distinguished thereby, that the long cutting edges (13) with their respective ends and the rounded edge (14) between the small end surface and the larger surface from an angle 70** < (90**) < (90) and that at least one of the connecting surfaces (180) between the larger surfaces (U, 12) and the smaller end surfaces (IS) is a plain surfaces (11, 12) and the smaller end surfaces (15) and forms a minor cutting edge (ISO) at the side wall.

Full Text

This invention relates to a cutting insert with a substrate body having mainly a cubical form, which as an indexable insert, is provided with eight active (usable) cutting edges, having two larger plain (flat) surfaces parallel to each other with a clamping bore passing through them and adjoining these two larger plain surfaces four lateral surfaces, parallel to one another, two small end surfaces at the front and two larger longitudinal surfaces. Each of these two larger longitudinal surfaces have, at the middle along their longitudinal axis, a stay (rib) which is projecting and which serves as supporting surface in the clamping of the indexable insert in a tool carrier. The larger surfaces merge via (over) connecting surfaces into the small end surfaces in such a way, that this resuUs at the side wall in correspondingly shaped cutting edges as border line to the end surfaces in the comer region. The long cutting edges, as border Ime between the larger surfaces and the respective adjoining longitudinal surfaces, are bent in the shape of an arc, so that a body, which is mirror symmetrical to the longitudinal center plane and transverse center plane, is obtained. Such a cutting insert is known from DE 295 16 668 Ul. This cutting insert has four long cutting edges, which have a convex, (curved) ground contour. The longitudinal surfaces are limited at the small end surfaces through small (short) straight cutting edges towards the respective and surfaces, which merge (extend) into the long cutting edges over the respective quarter circle shaped cutting edges. In order that all the above mentioned cutting edges have positive wedge angles, chip troughs are provided at the side wall in continuation to the long cutting edges. Similarly, chip troughs are also provided in the region of the quarter shaped cutting edges. Many such cutting inserts are to be mounted, distributed uniformly in the periphery, on a milling cuttCT head, whereby the cutting inserts in the peripheral face as well as in the front face of the tool carrier are mounted in such a way, that each of the cutting edges, which are in active cutting position, of all the cutting inserts can tanove (chip) metal in the radial or axial direction. However the cutting edges in radial direction project a little above each of those, which are in active cutting position, of the cutting insert located in the front face of the tool carrier, in axial direction project above each of the cutting edges, which are in active cutting position, of the cutting inserts located in the peripheral face of the tool carrier. In order to achieve the function described in the above patent documentation, the cutting inserts must be mounted both in axial and radial direction, so that the eight cutting edges can be used effectively. Disadvantageously, the first cutting insert must be shifted (staggered) from the next one by a certain value, so that in the adjustment of the required clearance angle, due to the projection of the cutting insert there will be no damage to the milled contour of the workpiece. In any case the above described indexable insert is not suitable for millmg crankshafts. Correspondmg is applicable for the cutting insert described in US - A - 3 762 005, which, to a large extent, is designed similar as the above mentioned one. A cutting insert is known fi-om DE 83 114.2 Ul, which in the top view is designed mainly rectangular and whose long sides, which is the face of the tool, have in their centre a certain contraction. However the lateral (end) edges are not designed to be used for machining or that is they are not cutting edges. It is the task of the present invention, to develop a cutting insert for achieving a tangential mounting position m a milling cutter and with which the depth of the cut during milling can be increased and simultaneously a smooth and satisfactory chip flow away from the work-piece which is to be machined, is guaranteed. In the present invention the cutting insert has long cutting edges, which form with their respective end and the rounded edge between the small end surface and the larger surface an angle between greater than 70° and less than 90°. In addition at least one of the connecting surfaces between the larger surfaces and the small end surfaces is a plane surface, which is provided at an angle between 90° and 180° to the small end surface and forms at the side wall a minor cutting edge, which is consequently provided at a tool cuttmg edge angle 'k' between 0 A further advantage of this cutting edge is seen, for example, in the machining of bearing regions of crankshafts, where the above described cutting insert with the concave shaped long cutting edges and the minor cutting edge is used for rough-machining, for which still (finishing) subsequent machining operations follows. Thus each of the long cutting edges consist of sections bordering each other at an angle greater than 180°, where by the length of the earlier described minor cutting edge is maximum and is as big as the length of each of the outer sections. Preferably the plain surface provided at an angle less than 90° and the adjacent surfaces border each other over rounded edges. As per another design version of the invention, the concerned radius of the edge between the plain surface and the larger surface is maximum 3 mm. The radius between the plain surface and the small end siurface should be preferably between 1 mm and 4 mm. A concrete example of the design version is described in the accompanying drawings, wherein; Figure 1 a perspective view of a cutting insert according to this invention, Figure 2 a top view of this cutting insert. Figure 3 respective side views of this cutting insert and Figure 4 an alternative design form of the cutting insert according to this invention. The cutting insert 10 designed as an indexable insert, which is shown in Figure 1 to 4, consists ofan essentially cubical substrate body, which has two larger surfaces 11 and 12, which are located parallel to each other and which are bordered at die side walls by long cutting edges 13. Each of the long cutting edges have a contraction 131 at the center, which is located between the respective cutting edge ends 132 and 133. The long cutting edge 13 consists of the sections 132 and 133, each of which are linear, whereby the cutting edge ends 132 and 133 with the rounded edge 14 or the plain surface 180, which in each case borders the larger surfaces on both the sides, form an angle 90°-p with 0 The ratio of the cutting edge ends 132 or 133 to 131 in the present case is approximately 1 :1.4, however can basically be selected between 1 : 2 and without the central region. The ratio ofthe length to width a/b, according to the invention, lies between 1.2 and 2. The small end surfaces 15,16 at the front faces verge into the larger surfaces 11, 12 over the respective rounded edge 14. Thereby, at each ofthe longitudinal surface 17 there are more or less quarter circle shaped cutting edges 18, namely two each on the longitudinal surface 17. At the remaining, opposite located sides, the cutting insert has a beveled (inclined) surface 180, which is designed plain and provided at an obtuse angle to the small end surface. This surface 180 verges over rounded edges into the adjacent surfaces 15 or 16 and II or 12. The radius R2, which is clearly seen in figure 3 and which also corresponds to the radius R ofthe rounded edge 18, is 1.6 mm, whereas the radius R2 is selected as 1.6 mm. The cutting insert as per figure 4 is distinguished fix)m the cutting insert as per figure 1 to 3 thereby, that in each ofthe comer regions there exists, in each case, inclined connecting surfaces 180, whose extension forms with the respective end sxuface 15 or 16 an angle 'x' of more than 0° and less than 90°. The dimensioning of the radii R1 and R2 corresponds to that, which is described in figures. The cutting edge 10 has a central clamping bore 19 for clamping bolts or a head for a knee lever actuated clamp or lever actuated eccentric clamp. At the center of the longitudinal surface 17, namely along the longitudinal axis, a rid (stay) 20 extends along the entire length. Compared to the adjoining regions, that means, as against the chip forming troughs 21, the rib 20 projects (protrudes) at least by 2 mm. In order to ensure the stability ofthe insert, the rib 20 has a width of at least 1.5 mm. The effective cutting angle formed by the troughs 21 is positive and in the present case is approximately 10°. Each ofthe chip troughs 21 have in continuation to the long cutting edges 13 a basically flat flank, before they verge over the radius of a truncated cone as connecting part into the rib 20. The entire design of the cutting insert as per figure 4 is mirror symmetrical, in fact in each axial direction of a central sectional plane. When the cutting insert according to Figure 1 to 4 is clamped tangentially on a milling cutter, the overdimension ofthe cheeks, which often exists in the bearing region during the machining of crankshafts, can be so overcome, that a depth of the cut which is larger than 0.5 x a' is possible. As mentioned earlier, the middle region 131 of the long cutting edge 13 can be 'jointly used' each tune while machining with the cutting edge end 132 as well as with the cutting edge 133. The above described, specially shaped chip-space (trough 21) is specially provided for the mounting of the cutting insert in the tangential position. The rib 20, located between the long cutting edges 13 which serve as major cutting edges, on the one hand separates the long cuttmg edges 13 from each other and on the other hand, serves especially as a locating support (stay) diuing the mounting of the cutting insert in the tool holder. The distance of the wall of the bore 19 to the cutting edge 13 at the narrowest point is at least 2 mm. Unlike the quarter circle shaped comers 18, because of the edges 180 the maximum thickness of the cut is reduced to h = fc sin k and thereby the risk of breakage of this cutting edge is reduced. The cutting insert as per figure 4 can carry out a rough machining with the regions 132,131,133 and 180. List of designations 10 Cutting insert 11,12 Larger surfaces 13 Long cutting edges 131 Middle cutting edge section 132,133 Cutting edge ends 14 Rounded edge 15,16 Small front face end surfaces 17 Longitudinal surface 18 Quarter circle shaped cutting edge 19 Clamping bore 20 Rib (stay) 21 Chip trough p Tool side rake (radial rake) Y Angle between the sections 131 to 133 k Complementary angle to the angle, which forms the connecting surface 180 with the end surface 15 and/or 16 a Cutting insert length b Cutting insert width c Depth of the cut of tangentially clamped cutting 10 d Depth of the cut of radially clamped cutting insert 100 WE CLAIM : 1. A cutting insert comprising a substantially rectangular parallelopipedal base body formed with two mutually parallel planar large faces pierced by a fastening hole and four side faces respectively bounding same, said side faces including two mutually parallel small end faces and two large longitudinal faces, said longitudinal faces having along respective longitudinal axes, respective projecting ribs serving as a mounting surface upon clamping of the cutting insert in a too! carrier, the large faces transitioning over respective rounded edges into the small end faces so that the longitudinal faces approximately one-quarter-circular cutting edges are formed as boundary lines to the end faces in comer regions of the body, the body having long cutting edges formed as boiindary lines between the respective large faces and the respective longitudinal faces bounding the large faces, said body being mirror symmetrical to a longitudinal median plane and to a transverse median plane, respective ends of the long cutting edges and the respective rounded edges between the small end faces and the large faces, form an angle 70.degree. 2. The cutting insert according to claun 1, wherein the long cutting edges are formed as concave or are assembled from linear segments adjoining one another at an angle .ganima.>180.degree. 3. The cutting insert according to claim 1, wherein the segments are rounded or an intermediate region of one of the long cutting edges is rectilinear with a length up to one-half the total length of said cutting edge. 4. The cutting insert according to claim 1 wherein a chip angle .alpha, between a perpendicular to one of the large faces and an adjoining longitudinal face is between O.degree.<.alpha.> 5. The cutting insert according to claim 1 wherein the lateral chip angle .beta, is between O.degree. and20.degree. 6. The cutting insert according to claim 1 wherein the width of the rib at an intermediate region thereof is at least 1.5mm. 7. The cutting insert according to claim 1 wherein the length/width ratio {a/b) of the large faces at the respective long cutting edges to the short rounded edges lies between 1.2 and 2. 8. The cutting insert according to claim 1 wherein a shortest distance of a fastening hole edge from the longer cutting edges lies below 2 mm. 9. A cutting insert comprising a substantially rectangular parallelopipedal base body formed with two mutually parallel planar large faces pierced by a fastening hole and four side faces respectively bounding same and including two mutually parallel small end faces, and two said longitudinal faces having along respective longitudinal axes respective projecting ribs, the large faces transitioning into the small end faces so that at the longitudinal faces correspondingly shaped cutting edges are provided as boundary lines for the end faces in comer regions, long cutting edges being formed are arcuately curved as boundary lines between the large faces and the longitudinal faces bounding same, said body being mirror symmetrical to a longitudinal median plane and to a transverse median, the long cutting edges forming an angle of 70.degree. 10. The cutting insert according to claim 9 wherein the long cutting edges are assembled respectively from segments angularly adjoining one another at angles. gamma.>180.degree. and the length of the auxiliary cutting edges is at a maximum as large as the length of each of the segments. 11. The cutting insert according to claim 9 wherein the plane is oriented at an angle .kappa, to a respective small end face and the small end face and the face bounded thereby transition with one another via rounded edges, a radius R.sub. I between the plane and the larger face being 0 between the plane and the smaller end face being 1 mm 12. A milling tool having a multiplicity of clamped cutting inserte as defined in claim 9 clamped tangentially on a tool holder. 13. The milling tool as defined in claim 12 wherein additional cutting inserts are radially clamped. 14. The milling tool as defined in claim 12 wherein the tool holder is configured as a disk and has alternating radial and tangential clamped cutting inserts, the disk width being smaller than twice the length of the cutting insert. 15. The milling tool according to claim 12 wherein a surface bounding the rib is configured as a bevel. 16. The milling tool according to claim 15 wherein the bevel bounding the cutting edge has a width up to 0.2 mm and a bevel angle between O.degree. and 20.degree.

Documents:

60-mas-99 abstract-duplicate.pdf

60-mas-99 claims-duplicate.pdf

60-mas-99 claims.pdf

60-mas-99 correspondence-others.pdf

60-mas-99 correspondence-po.pdf

60-mas-99 description (complete)-dupliate.pdf

60-mas-99 description (complete).pdf

60-mas-99 drawings.pdf

60-mas-99 form-1.pdf

60-mas-99 form-14.pdf

60-mas-99 form-19.pdf

60-mas-99 form-26.pdf

60-mas-99 form-3.pdf

60-mas-99 others.pdf

60-mas-99 pct search report.pdf

60-mas-99 petition.pdf