BLANK INSERT, AND INSERT AND CUTTER UTILIZING THE

SAME

Technical Field

[1] This disclosure is related to blank inserts of specific shapes, inserts machined from the blank inserts, and cutters mounted with the inserts. These inserts are typically used with cutters for rail machining, have longer durability by providing more cutting edges than conventional inserts, and allow reduced production cost. Background Art

[2] Rail machining cutters may have various shapes according to the shape of the rail to be machined, and thus various insert shapes are also needed. FIGs. 1 and 2 depict situations where cutters mounted with various kinds of inserts in a specific arrangement are machining specific portions of rails. Inserts mounted on these cutters need edges with various convex or concave curvatures which are generally formed by grinding regular quadrilateral negative blanks.

[3] However, although a plurality of inserts with various shapes are mounted in the insert pockets of the cutter, it is very uneconomical to form pockets of different shapes to adapt to the various curves of the ground edges of different inserts. Therefore, by grinding only the upper surface of an insert as shown in FIG.3, the lower surface of a conventional insert remained flat so as to be in contact with the flat bottom wall of the pockets, thereby having an identical shape. In this case, when only the upper face is grinded, the insert is provided with only two cutting edges. As tangential inserts, as shown in FIGs. 1,2 and 3, have larger scrap volumes generated from grinding than those of radial type inserts, the cost for grinding accordingly becomes higher. Disclosure of Invention Technical Problem

[4] The present invention aims to expedite the grinding process, to save raw material, and to extend the service life of cutting inserts which have various curvatures of their cutting edges. Also, the present invention aims to provide cutters which have a pocket structure that allows stable mounting for cutting inserts which have various curvatures of their cutting edges. Technical Solution

[5] A blank insert according to the present disclosure comprises upper and lower surfaces joined by peripheral side surfaces provided with a through-hole extending between the upper and lower surfaces, each of the upper and lower surfaces comprising two raised portions and a central notch; the two raised portions have a flat upper surface, adjoin two opposing side peripheral side surfaces, and extend along the entire length of the two opposing side peripheral side surfaces; and the central notch is formed as a flat plane between the two raised portions.

[6] An insert according to the present disclosure comprises upper and lower surfaces joined by peripheral side surfaces provided with a through-hole extending between the upper and lower surfaces, each of the upper and lower surfaces comprising two raised portions and a central notch; the two raised portions adjoin two opposing side peripheral side surfaces, and extend along the entire length of the two opposing side peripheral side surfaces, and the upper surface comprises concave or convex surfaces curved along the two opposing side peripheral side surfaces; and the central notch is formed as a flat plane between the two raised portions.

[7] The central notch may be depressed stepwisely from the raised portions.

[8] A cutter mountable with the insert according to the present disclosure has an insert pocket comprising two side walls for supporting the peripheral side surfaces of the insert and one bottom wall that supports the lower surface of the insert, wherein the bottom wall has a protruded contact portion in the form of a flat plane corresponding to the central notch of the insert and depressed receiving portions for receiving the raised portions of the insert.

Advantageous Effects

[9] The inserts according to the present invention are ground such that there is less removed volume during grinding and thus raw material can be saved, and the grinding burden is much reduced compared with conventional inserts. The inserts according to the present invention have a lower surface having the same structure as the upper surface and thus allows four cutting edges of the same shape. Therefore, the service life can be extended compared to that of conventional inserts.

[10] The cutter pocket according to the present invention provides a sufficient support force in a radial direction by surface contact with the insert, and at the same time, can mount inserts with cutting edges of various curvatures. Brief Description of Drawings

[11] FIGs. 1 and 2 are perspective views depicting situations where cutters mounted with various kinds of inserts are machining rails.

[12] FIG. 3 is a perspective view showing a conventional blank insert and inserts ground from it.

[13] FIG. 4 is a perspective view showing a blank insert of an embodiment according to an example of the present invention.

[14] FIG. 5 is a perspective view showing inserts ground from the blank insert according to an example of the present invention. [15] FIG. 6 is a perspective view showing the ground portions of inserts according to an example of the present invention.

[16] FIG. 7 is a perspective view showing states where various shapes of inserts are mountable to the cutter pocket according to an example of the present invention. Mode for the Invention

[17] Hereinafter, blank inserts, inserts machined from the blank inserts, and cutters mounted with the inserts according to example embodiments of the present disclosure are described. The figures attached to the present disclosure are for the convenience of explanation and the shapes and the relative scales may be exaggerated or abridged.

[18] FIG. 4 shows a blank insert of an embodiment according to the present invention.

The blank insert 10 comprises upper and lower surfaces 100, 200 joined by peripheral side surfaces 310, 320, 330, 340, and is provided with a through-hole 400 extending between the upper and lower surfaces. Each of the upper and lower surfaces 100, 200 comprises two raised portions 110, 120 and a central notch 130. The two raised portions have a flat upper surface, are formed adjoining two opposing side peripheral side surfaces 310, 330, and extend along the entire length of the two opposing side peripheral side surfaces 310, 330. The central notch 130 is a flat plane between the two raised portions, is formed by undercutting, and thus is depressed stepwisely from the raised portions. Although not clearly shown in FIG. 4, the lower surface has an identical structure to that of the upper surface. The central notch of the lower surface may extend either in a parallel or perpendicular direction to that of the upper surface.

[19] These blank inserts are generally manufactured by mold press forming, and then provided for grinding inserts of various shapes as explained hereinafter. FIG. 5 shows the blank insert before grinding, and examples of (a) a convex insert and (b) a concave insert obtained after grinding on the blank insert is finished. These ground inserts have the same structure as the blank insert except for the ground portions (thickly painted portions in FIG. 6). In other words, the two raised portions adjoin two opposing side peripheral side surfaces, and extend along the entire length of the two opposing side peripheral side surfaces, and the upper surface comprises concave or convex surfaces curved along the two opposing side peripheral side surfaces, and thus provides cutting edges having a concave or convex curvature. Similarly to the blank insert, the lower surface of these inserts has an identical structure to that of the upper surface. However, the central notch of the lower surface may extend either in a parallel or perpendicular direction to that of the upper surface.

[20] Since the inserts according to the present invention are ground only on the raised portions, the volume removed during grinding is reduced and thus raw material can be saved, and the grinding burden is much reduced compared with the conventional inserts shown in FIG. 3. While the lower surface of the conventional insert is a flat surface and is provided with only two cutting edges, the lower surface of the inserts according to the present invention has the same structure as the upper structure, and thus provides four cutting edges of the same shape. Therefore, the durability of the inserts according to the present invention can be doubled compared to that of the conventional inserts.

[21] On the other hand, although the lower surface of the insert according to the present invention has raised portions of curved surfaces having various curvatures, since it has the flat central notch, it is possible to mount inserts of various shapes by forming the cutter pocket 690 as shown in FIG. 7. In other words, the cutter insert pocket of the present invention comprises two side walls 640, 650 for supporting the peripheral side surfaces of the insert and one bottom wall 610-630 to support the lower surface of the insert, but the bottom wall has a protruded contact portion in the form of a flat plane corresponding to the central notch and depressed receiving portions 610,620 for receiving the raised portions of the insert. The central notch of the insert and the protruded contact portion 630 of the cutter pocket are both flat and are in surface contact with each other, providing a support force in a radial direction. However, the receiving portions 610,620 of the cutter pocket receive the raised portions of the insert, but are furnished with a sufficiently depressed space so as not to touch the cutting edges of the insert, so that it can receive raised portions of various shapes.

[22] The disclosed blank inserts, inserts machined from the blank inserts, and cutters mounted with the inserts may have various other embodiments without departing from the basic concept of the present disclosure. Accordingly, all the disclosed embodiments must be understood as being exemplary only and must not be construed to be the limit of the present disclosure. Accordingly, the range of protection for the present disclosure must be determined not by an embodiment described hereinabove, but by the attached claims. An alternative that is equivalent to the attached claims is included in the range of protection of the attached claims.