CS230364B1 - Cutting plate - Google Patents

Description

(54) Gray plate

The object of the invention is a cutting insert suitable for efficient machining of tough low-carbon materials referred to as difficult to machine, or soft materials, but also materials of high strength or hardness.

A number of cutting insert designs are already known. Until now, the insert is radially inserted into the tool body and clamped by various mechanisms. The basic disadvantage of a radially clamped insert is that its stress is always transmitted by several times smaller cross-section than in the case of a tangentially clamped insert. At a relatively low tensile strength of cemented carbide, this is the main cause of the limiting cross-section of the material to be cut and thus the machining performance. Another disadvantage is that in the case of a positive cutting insert, only half the cutting edges of the insert are used. Another disadvantage is the necessity of using shank splitters etc.

Cutting inserts tangentially clamped in tools are also known, but they have the disadvantage that all the cutting edges of the inserts have a negative cutting edge angle λ and little positive near the tip of the cutting edge, up to σγ, ηγ the rake angle y. This geometry is not suitable for machining low-carbon, high-toughness, so-called hard-to-cut materials, cutting inserts are known which have a positive cutting angle λ and a positive rake angle γ, but only half the cutting edges of the insert are used.

The above-mentioned drawbacks are eliminated by the cutting insert according to the invention, whose two adjacent surfaces are provided with a groove forming the face of the cutting edge in the form of a helical groove with the opposite direction of its inclination (+ p) (- p). Each of the helical grooves has a pitch angle p and a pitch angle λ of the cutting edge directly proportional. A transition surface is formed on the cutting edge between the dorsal surface and the helical groove surface. This transition surface is formed only once on any of the cutting edges.

The advantage of the cutting insert according to the invention is that behind it there are created completely different cutting edge geometries, which can be used to optimally solve the problem of highly productive machining of very different types of materials. For example, four-sided cutting inserts produce eight, three-sided six cutting bits and the like, of which a portion of the cutting edge has a geometry suitable for machining hard-to-machine materials with high toughness or soft materials such as some light and nonferrous metals. This part of the cutting edge has a positive cutting edge angle λ and a maximum rake angle γ around the cutting edge. Said geometry ensures good cutting properties and at the same time ensures non-forceful chip forming as well as minimal thermal loading around the tip of the cutting edge. This has a favorable effect on the durability of the cutting edges, especially when machining difficult-to-machine materials. The other part of the cutting edges has a geometry suitable for machining carbonaceous materials characterized by significantly higher strength or hardness. These cutting edges have a negative cutting edge angle and a rising rake angle γ away from the cutting edge. This geometry ensures maximum blade tip strength, favorable and gradual loading of the blade at the start of engagement. The combination of the helix angle of the work surfaces in addition to the changes in the cutting edge geometry at the same time causes the opposite cutting edges to be increased, so that part of the cutting edge can always be used for tools with an adjustment angle κ 90 °. Furthermore, it ensures the unusual versatility of the use of the cutting insert, since it enables different ways of grinding the transition cutting edges and creates different possibilities for the use of the cutting insert in terms of the machining sense. For example, the insert may be used as right-hand, left-hand, or a portion of the edges as right-hand and the other portion of the edges as left-hand.

Another advantage of the cutting inserts according to the invention is that the working surface in the form of a screw groove acts simultaneously as a very reliable chipbreaker. Another important advantage of the cutting inserts according to the invention is the variable rake angle γ at each cutting edge point. It manifests itself in both types of geometries and very positively affects the rigidity of the system machine, tool, workpiece, because it counteracts its oscillation. It is also an advantage of the cutting inserts according to the invention that they can be used with all the above mentioned advantages for tools providing various machining methods, for example: turning, planing, milling, boring and the like. A further advantage of the invention is that it can also be used for radially mounted inserts, although the full benefit of the invention is primarily achieved with tangentially clamped inserts. The tangential cutting insert with these advantages is the optimum type of cutting insert, especially for difficult machining conditions.

An exemplary embodiment of a combination cutting insert according to the invention is shown in the accompanying drawings, in which Fig. 1 shows the combined cutting insert according to the invention, shown in an overall view, and Fig. 2 from the left or right side and the top or bottom view in Fig. 3. Figs. 4 and 5 show different inserts of different shapes. Various embodiments resulting from different grinding of the transition surfaces are shown in Figs. 6, 7 and 8.

The variation of the cutting edge 2 angles, indicated by the angles (+ A) and (—AJ), creates an elevation p at the tips of the cutting edges 2 to determine whether the cutting edge can be used in a tool with κ to 90 ° or κ <90 °. the angle of inclination λ of the cutting edge 2 and the angle of the face γ can be selected by the radius r and the pitch angle (+ pj (-—p) of the screw groove 1, which is not a condition of uniformity of selected values. and the negative cutting angle λ according to the assortment and properties of the machined materials for which the cutting insert will be designed.

For the values of angles v and λ and the resulting values r and p, a clear table can be drawn up according to which the optimal values of cutting angles of the insert can be selected according to known principles for different types of machined materials. Fig. 6 shows an example of a method of sharpening transition surfaces 4 between a dorsal surface 3 and a helical flute surface 1 on a quadrilateral cutting insert for right-cutting machining to obtain: 4 cutting edges 2 with a cutting angle (+ A) and an angle κ 90 ° and 4 cutting edges 2 with cutting edge angle (AA) and for setting angle κ <90 °. Fig. 7 shows an example of a method of sharpening the transition surfaces 4 between the dorsal surface 3 and the surface of the helical groove 1 on a quadrilateral cutting insert for left-hand machining to obtain: 4 cutting edges 2 with cutting angle + A and set angle κ ≥ 90 ° and 4 cutting edges with cutting edge angle (—A) and for setting angle κ <90 °. Fig. 8 shows an example of a method of sharpening the transition surfaces 4 between the dorsal surface 3 and the surface of the helical groove 1 on a four-sided cutting insert for machining in both directions to obtain: 2 right cutting edges 2 with cutting angle (+ AJ) 90 90 ° and 2 right cutting edges 2 with cutting angle (—Aj and for setting angle κ <90 °, 2 left cutting edges 2 with cutting angle (+ AJ and for setting angle κ κ 90 ° and 2 left cutting edges 2 with cutting edge angle (—A) and for setting angle κ <90 °.

230384

Claims (4)

palubdmet 1. A cutting insert characterized in that two adjacent surfaces each have a groove forming the face of the cutting edge (2) in the form of a helical groove (1) with the opposite direction of its inclination (+ p) (—p). The cutting insert according to claim 1, characterized in that each of the helical grooves (1) has a pitch angle p and an angle of inclination λ of the cutting edge (2) directly proportional. KYNALIIU Cutting insert according to claim 1 or 2, characterized in that a transition surface (4) is formed on the cutting edge (2) between the dorsal surface (3) and the surface of the helical groove (1j). The cutting insert according to claim 3, characterized in that the transition surface [4j] is formed only once on any of the cutting edges (2).