MXPA97006684A - Insert cutter helicoidal with edges cortadoresdesnivela - Google Patents

Abstract

A cutter insert (209) is provided for use in a tool called a rotary mill 10. The cutter insert (20) includes an insert body comprising a lower face (22), an upper face (24) and a side face (20). 26) A stepped cutting edge (30) is formed at the intersection of the upper face (24) and the side face (26) to attack a work piece and remove a cutout of this stepped edge includes at least two portions Uneven edge portions (30a-c) which produce different, transversely spaced cut segments during the cutting operation The uneven edge portions (30a-c) are connected by transition edge portions (30d-e) which are arranged in an obtuse angle with respect to the uneven edge portions The angle of the transition edge portions tends to disseminate the individual trim segments separated during the machining operation to cause an effect ligation of the trimmings between the individual trim segments. All and all the cutting edges are helically curved in such a way that the cutting edges are on the surface of a circumscribed cylinder defined by the rotation of the cutting edges around the axis of a cut mill.

Description

INSERT CUTTER HELICOIDAL WITH EDGED CUTTERS EDGES BACKGROUND OF THE INVENTION The present invention relates generally to cutter inserts for rotary cutter mills, and more specifically to a replaceable cutter insert having a plurality of uneven cut portions, arranged helically to each other, to cut straight sidewalls.

A cutter mill typically includes a cylindrical body with a plurality of notches, grooves or concavities formed in the outer surface to receive replaceable cutter inserts. Each cutter insert has at least one cutter edge that attacks the work piece to perform the operation of the mill. During the design of the cutting inserts for the cutter mills, it is desirable to reduce the cutting forces present at the cutting edges of the inserts. Reducing cutting forces will reduce wear and tear on inserts and increase tool life. Low cutting forces also reduce the power required in the operation of the mill. The magnitude of such cutting forces is greatly determined by the geometry of the cutting insert, and its orientation with respect to the work force.

In most cutting mills, the inserts are formed with straight cutting edges. In order to reduce the cutting forces experienced by such straight edges, normally the cutter insert is mounted in such a way that it is inclined at an angle relative to the axis of rotation. An axial inclination in this manner is referred to an axial sweep angle, and corresponds to the angle A of FIG. 7, where CL represents the axis of rotation. But while such an axial tilt improves the cutting efficiency of the insert, it also causes a variation in the distance of the cutting edge and the axis of rotation of the mill head along the length of the cutting edge, since Contact points of the cutting edges with the workpiece are not all arranged at the same radial distance from the axis. This variation is reflected in an undesirable convex curvature on the lateral surface of the cuts made by the cutter.

The greater the axial sweep angle, the greater the curvature on the lateral surfaces of the resulting cuts will be. Additionally, for inserts inclined to an axial sweep angle, the cut absorbs forces, and then the power requirements for cutting, are proportional to the length of the cutting edges, due to the effect of such axial tilt in the angle between the cutting edge and the surface that is being cut.

The upper face of the insert is also important for cutting efficiency. A characteristic of the upper face is the angle formed by the scanning surface of the insert and that of the workpiece. Such an angle is known as the radial sweep angle and is illustrated as the angle d, c2 and c3 in Figures 9 to 11, respectively. When the radial scanning angle is positive, the edges of the inserts cut the work piece by means of a shaving action. When the radial sweep angle is negative, the edge of the inserts cuts the work piece by means of a scraping action that is substantially less efficient than the shaving action. The more the length of the cutting edges grows, the greater the amount of these tend to be oriented at a negative radial angle with respect to the work piece, thereby causing the increase of the loaded cutting forces. Such an increase is contrary to the objectives of reducing the cutting forces fed as far as possible, to reduce the risk of breaking the tool, reduce the wear of the inserts and reduce the energy requirements needed by the cutting operation.

To reduce cutting forces, it has been known to use a plurality of cutting inserts with relatively short cutting edges instead of a single insert with a single long cutting edge. The inserts are arranged in such a way that the short cutting edges overlap. While such an arrangement significantly decreases cutting forces, the cutting inserts must be precisely aligned with each other to produce a smooth cut.

Clearly it can be seen here that cutting inserts that are capable of producing cuts with straight and smooth side edges, need, especially when operating at substantial sweeping angles, do not require deep debilitating concavities in the body of the tool. Ideally, the cutting edge of such an insert should condition the workpiece to a positive radial sweeping angle over substantially its entire length to minimize the cutting forces and wear of the insert. Finally, it would be desirable, if i / n insert with such characteristics could break more effectively the cuts of the metal that result from the cutting action, increase the efficiency in its entirety of the tool that uses the insert.

DESCRIPTION OF THE INVENTION The present invention is a cutter insert particularly designed for use in rotary cutting tools, such as rotary cutter mills and augers. The insert includes a polygonal insert body having a flat underside, an upper face, and a plurality of side faces extending between the upper and lower face. A cutting edge is defined at the intersection of the top face with at least one of the side faces to attack, and remove cutouts of the work piece. The cutting edges include at least two uneven edge portions that are connected by a transition edge portion. The transition edge portion is disposed at an obtuse angle with respect to the uneven edge portions.

The cutting edges of each edge portion and the transition edge portion are arranged in a cylindrical shell defined by the rotation of the cutting edges around the cutter shaft axis, which causes each of the cutter edges to be helically bent. . The helical curvature of each portion of the cutting edges ensures a smooth and straight sidewall surface on the workpiece.

During the machining operation, the uneven edge portion of the cutting edge produces narrow cut segments transversely spaced, while the edge transition portions dissect the different cut segments to effect a reduction in the size of the cutouts. Such size reduction produces localized hardening in the cuttings and makes them easily breakable.

In another aspect of the present invention, the cutting edges of each of the uneven portions are inclined with respect to the lower edge of the insert. By inclining each of the cutting edges with respect to the low edge, it is possible to reach wider sweeping axial angles without deepening the seats of the inserts in the cutter mill, which in turn could cause weakening I structural excess in the body of the cutter.

Based on the above, it is an object of the invention to provide cuts in pieces of work with straight side walls even when the inserts are inclined to substantial axial sweeping angles in the body of the cutter mill.

Another object of the present invention to provide a cutter insert for a cutting tool with increased breaking capacity.

It is also an object of the present invention to provide a cutter insert for a rotary cutting tool that has a cutting edge that attacks the piece of work at a positive radial sweep angle through its entire length to reduce cutting forces and wear of the insert.

Another object of the present invention is to provide a cutter insert for a rotary cutting tool that reduces the power requirements in the cutting operation, compared to the cutter inserts of the state of the technique.

Other objects and advantages of the present invention will become apparent. of the study of the following description and the attached drawings, which are merely illustrative of said invention.

BRIEF DESCRIPTION OF THE DIFFERENT FIGURES Figure 1 is a perspective view of a cutter mill using the cutter insert of the present invention; Figure 2 is a perspective view of the cutter insert of the present invention; Figure 3 is a side elevation view of the cutter insert of the present invention; Figure 4 is a top plan view of the cutter insert of the present invention; Figure 5A is a cross-sectional view of the present invention taken through the cut line V-V of Figure 4; Figure 5B is an enlarged view of the section enclosed in the dotted circle of Figure 5A; Figure 6 is a schematic illustration showing the cutting edge of the insert in a cylindrical shell defined by the rotation of the cutting edges around the axis of the rotary cutting tool; Figure 7 is a side elevational view of the cutter insert shown in silhouette; Figure 8 is an elevational view of the cutter mill showing the cutter inserts in the assembled one.

Figures 9 to 11 are views of the fragmented cross sections taken from the cuts indicated by lines IX-IX, X-X and XI-XI respectively, of Figure 8, and Figure 12 is a top plan view of the cutter inserts during the operation of the cutter mill, showing the production of a cutout removed from the workpiece.

DETAILED DESCRIPTION OF THE DIFFERENT FIGURES Referring now to the drawings, and particularly to Figure 1, there is shown a rotary cutter mill indicated generally by the number 10. The cutter mill 10 rotates about the longitudinal axis CL. The rotary cutter mill 10 includes a rod portion 12 adapted to be mounted on a tool (not shown) and a cutting head portion 14. The cutting head portion 14 includes a plurality of concavities 16 spaced circumferentially. Each concavity includes a support surface 18 on which the insert 20 is mounted.

Referring now to Figures 2 to 5, there is shown a cutter insert 20 with the features of the present invention. The cutter insert 20 comprises a generally polygonal insert body, of a hard wear-resistant material, such as one of the numerous carbide materials cemented with a refractory coating, which are well known in the state of the art.

The body of the insert has a central opening 50 through which a security screw (not shown) is inserted to secure the insert to the support 18 of the cutter mill 12. The insert includes a generally flat bottom face 22, an upper face 24 , opposite lateral flanks 26, and flanks of opposite ends 28. Both the side flanks 26 and the end flanks 28 are flat. The intersection of the side flanks 26 with the top face 24 defines a pair of cutting edges indicated generally by the number 30. The intersection of the end flanks 28 with the top face 24 defines a pair of side edges 32.

The pair of cutting edges 30 has a stepped configuration. Each cutting edge 30 is fractioned into uneven edge portions 30a, 30b and 30c, and transition edge portions 30d and 30e. The uneven edge portions 30a, 30b and 30c are inclined with respect to the lower face 22 of the insert 20 at an average angle of about 5 ° as can be seen more clearly in Figures 3 and 7. By regulating the angle of the portions of Uneven edges 30a, 30b and 30c with respect to the base of the insert 20, it is possible to obtain a relatively wide axial sweep angle "A", as shown in Figure 7 without the need to increase the depth of the seat concavities of insert in the portion 14 of the cutter. Such depths of the concavities of insert seats could cause an excessive structural weakening of the cutter body 12.

Uneven edge portions 30a, 30b and 30c are connected by transition edge portions 30d and 30e. The transition edge portions 30d and 30e are inclined with respect to the base 22 of the insert 20 at an angle of inclination that is much larger than the angle formed between the base 22 and the uneven edge portions 30a, 30b and 30c, for example 45 ° against 5o. The transition edge portions 30d and 30e form an obtuse angle "a" with the uneven edge portions 30a, 30b and 30c (as shown in Figure 7). That is, the angle "a" formed between the transition edge portion and its adjacent uneven edge portions is greater than 90 °.

Figure 7 schematically shows an insert 20 as normally oriented with respect to both the centerline CL of the cutter mill 10, and the workpiece. The tail end of the uneven edge portion 30a is spaced apart by the distance V from the forward end of the uneven edge portion 30b when measured along the centerline CL of the cutter mill 10. The uneven edge portions 30b and 30c are similarly spaced. Then, when the cutter insert 20 is mounted in a cutter mill 10, the uneven edge portions 30a, 30b and 30c do not overlap. A plane that extends perpendicular to the center line and intersects with an uneven edge will not intercept any other portion of uneven edge. As a result of this, the transition edge portion 30d and 30e will attack by cutting the workpiece W during the operation of the mill, as shown in Figure 12. The uneven edge portions 30a, 30b and 30c will produce three different segments of trimming during the operation of the mill. The transition edge portions 30d and 30e will create grooves between the three trim segments which will tend to divide the cutout and help to embrittle it, so that breaking of the cut is facilitated.

As best seen in Figure 6, each of the uneven edge portions 30a, 30b and 30c, and the uneven edge portions 30b and 30c have a helical curvature in order to ensure a substantially straight machining along the cutting wall produced by the cutter 10. All the cutting edges 30 lie in a cylindrical shell defined by the rotation of the cutting edges 30 around the centerline CL of the cutter mill 10. Each of the uneven edge portions 30a, 30b and 30c form a part of a large pitch propeller lying on the surface of the cylindrical envelope. The three helices corresponding to the uneven edge portions 30a, 30b and 30c are parallel to each other. That is, the helix defined by each of the uneven edge portions 30a, 30b and 30c equidistant from its neighbor over its entire length. The transition edge portions 30d and 30e define in the same manner two parallel helices 31 a and 31 b (as indicated in dotted line). The helices defined by the transition edge portions 30d and 30e have a smaller pitch than the helices defined by the uneven edge portions 30a, 30b and 30c. When the cutting edges 30 are formed by a curvature of this type, the lateral surface produced during the machining operation will be flat.

Referring now to the upper face 24 of the insert 20, shown more clearly in FIG. 4, it can be seen that a ridge 34 is formed adjacent and parallel to the cutting edges 30. The ridge 34 is divided into five ridge surfaces 34a, 34b , 34c, 34d and 34e. Each of the ridge surfaces 34a, 34b, 34c, 34d and 34e is a continuously curved surface that follows the contour of the cutting edges 30. These surfaces could have a helical contour. The ridge surfaces 34a, 34b, 34c are joined at one edge to the respective unleveled edge portions 30a, 30b and 30c of the cutting edges 30, while the ridge surfaces 34d and 34e are edge-joined to the respective portions thereof. of transition edge 30d and 30e. A plurality of scanning surfaces 36a, 36b, 36c, 36d and 36e extend downward from their respective surfaces 34 to 34e. The scanning surfaces 36a to 36e are curved to blend with the ridge surfaces 34a to 34e. Each of these surfaces may also have a helical contour.

The side flanks 26 of the insert 20, best shown in Figure 3, includes a generally flat lower portion 38 and an upper portion 40 that is curved along two different axes, as explained below. The lower portion 38 facilitates the assembly of the insert in the cutter body 12. The upper portion 40 is divided into five raised surfaces 40a, 40b, 40c, 40d and 40e. The raised surfaces 40a to 40e curve uninterrupted with respect to the cylinder defined around the center line CL of the cutter 10 (as shown in Figure 6) to provide a smooth transition from the flat lower portion 38 to the cutting edges. helical 30. Each of these surfaces can have a helical contour.

As best seen in Figure 5B, the relief surfaces 40a to 40e are also rounded with respect to the plane P (shown with cut line) extending over the lower portion 38. The provision of such radial curvature just below the cut edges. increases the resistance of the cutting edges 30a to 30e by providing them with more support. The raised surfaces 40a, 40b and 40c are joined at one edge to the respective unleveled edge portions 30a, 30b and 30c, while the raised surfaces 40d and 40e are joined to the respective portions 30d and 30e of the cutting edge 30.

Each end flank 28 of the cutter insert 20 is substantially flat. The end flank 28 forms a side edge 32 at an intersection with the top face 24 of the cutter insert 20. The side edge 32 includes a generally horizontal cleaning portion 32a, and a downward sloping portion 32b (FIG. 4). A recessed surface 42 is formed on the upper face 24 of the insert 20, adjacent the side edge 32. The recessed surface 42 includes portions 42a, and 42b that are disposed adjacent the cleansing portion 32a and the descending slope portion 32 respectively. The scanning surfaces 44a and 44b are inclined downwards from the relief surfaces 42a and 42b.

Referring now to Figures 8 to 11, the radial scan angles and relief angles are shown at selected points along the cutter edge 30 as shown in Figure 8. Figure 9 shows the view of a section of the insert taken along line IX-IX in figure 8. Figure 10 shows a sectional view of insert 20 taken along line XX of figure 8, while figure 11 shows a sectional view taken along line XX. line XI-XI of figure 8, respectively. In Figures 9 to 11, the circular path followed by the cutting edge 30 of an insert mounted on a rotary cutter mill, rotating around the central line CL, overlaps into different cross sections of the insert 20.

Figures 9 to 11 show the following angles: bx = radial sweep angle of the swept surface; c = radial scanning angle of the relief surface; and dx = relief angle.

The relief angle bx is the angle between the scanning surface and a reference plane RP, measured in a plane perpendicular to the axis of the center lines CL and extending between the central axis CL and a point along the cutting edge where the measurement is made. The sweep angle cx is the angle between the relief surface and the reference plane RP. As will be discussed, the relief and scanning surfaces may be curved. Under these circumstances, a straight line that best fits each curved surface will be sufficient to determine the radial sweep angles.

The raised angle dx is defined as the angle formed between a line perpendicular to the reference plane RP and a line extending from the cutting edge downward along the relief surface 40. Since the relief surface is curve, then the angle of relief will be measured from a line extending from the cutting edge downwards along the relief surface 40 which is tangential to the relief surface at the cutting edge.

As can be clearly seen in Figures 9 to 11, the sweeping angle bx and cx increases from the anterior portion of the cutting edge shown in Figure 9, to the rear portion of the cutting edge, shown in Figure 11. In the embodiment Preferred, the angle of the swept surface b "increases 39% from the leading end of the cutting edge to the trailing end, while the angle of the ridge surface decreases 34% between these ends. The relief angle dx decreases in a similar proportion from the leading end to the trailing edge of the cutting edge.

Figure 12 illustrates a sketch of a cutter insert of the present invention being in operation to remove a cutout from the workpiece. In this figure, the insert is mounted in a cylindrical cutter mill 10, in such a way that functions in operation. The cutting edge 30 of the insert 20 attacks the workpiece 20 and shears the material of said workpiece W to form the cutout C. As can be seen, the uneven edge portions 30a, 30b and 30c of the cutter edge 30 produce a trimming comprising three relatively narrow clipping segments. During the cutting process, the transition edge portions 30d and 30e of the cutting edge 30 tend to separate the different narrow cut segments to thin or weaken the cut between the segments. In certain materials, the thinning of the cuttings can result in a complete separation of the cut segments into three smaller cuttings.

In view of the foregoing, it will be readily apparent that the cutter insert 20 of the present invention will reduce the shear forces experienced by the cutting edge during mill operation and consequently reduce the power requirements. The reduction of cutting forces will lengthen the life of the tool and finishes of smoother surfaces.

The present invention can, of course, be carried out in other specific ways than those set forth herein without departing from the spirit and essential features of the invention. The present modalities should, therefore, be considered as illustrative and not restrictive and all changes made within the meaning and range of equivalence of the joint claims will be considered as the invention itself.

Claims (18)

R E I V I N D I C A C I O N S
1. An insert for use in a rotary cutter mill tool characterized by comprising: a) an insert body including a lower face, an upper face, and a side face extending between the lower and upper faces; b) a stepped cutting edge defined at the intersection of the upper face and the side face to attack and cut a workpiece and remove a cutout, said stepped cutting edge including at least two uneven edge portions, each of which creates a cut segment, and c) means for attacking and cutting the workpiece and for creating a thinner cutting portion between the segments created by said uneven edge portions to facilitate the breaking of said trimming segments, including a transition edge portion joining the uneven edge portions.
2. The cutting insert according to claim 1, characterized in that the uneven edge portions are curved in such a way that the uneven edge portions are located on the surface of a circumscribed cylinder defined by the rotation of the cutting edge around the axis of the cutting tool.
3. 3) The cutter insert claimed in claim 2, characterized in that the uneven edge portions are helical.
4. 4) The cutter insert claimed in claim 3 characterized in that the uneven edge portions are parallel to each other.
5. 5) The cutter insert claimed in claim 2 further characterized in that the uneven edge portion means are curved in such a way that the uneven edge portion means are located on the surface of a circumscribed cylinder defined by the rotation of the cutter edge around it. of the axis of the cutting tool.
6. 6) The cutter insert according to claim 5, further characterized in that the unleveled portion means is helical.
7. 7) The cutter insert according to claim 2, further characterized in that the side face adjacent the cutting edge includes a curved relief surface over its entire extension, adjacent to each of the uneven edge portions.
8. The cutting insert according to claim 2, further characterized in that the upper face includes a sweeping surface, curved in all its extension, adjacent to each uneven edge portion.
9. The cutting insert according to claim 1, further characterized in that the uneven edge portions of the cutting edge are disposed at an angle relative to the lower face of the insert to increase the axial sweep angle of the edge portions relative to a axis of rotation.
10. 0) A cutting insert to be used in a cutting tool that rotates around an axis, characterized by comprising: a) an insert body including a lower face, an upper face, and a side face extending between the lower and upper faces; b) a stepped cutting edge defined at the intersection of the upper face and the side face to attack and cut a workpiece and remove a cutout, said stepped cutting edge including at least two uneven edge portions, each of which creates a cutting segment, and c) means for attacking and cutting the workpiece and for creating a thinner cutting portion between the segments created by said uneven edge portions to facilitate the breaking of said cutting segments, including a portion of transition edge joining the uneven edge portions, the transition edge portions having an axial sweep angle less than 90 ° so that the cutting occurs continuously along the entire cutting edge during the operation of the cutter mill .
11. 1) The cutting insert, as claimed in clause 10, characterized in that the uneven edge portions are curved in such a way that the uneven edge portions are located on the surface of a circumscribed cylinder defined by the rotation of the Cutting edge around the axis of the cutting tool
12. 12) The cutting insert, as claimed in clause 11, characterized in that the uneven edge portions are helical.
13. 13) The cutting insert, as claimed in clause 12, also characterized in that the uneven edge portions are parallel to each other.
14. 14) The cutting insert, as claimed in clause 11, also characterized in that the uneven edge portion means are curved in such a way that the uneven edge portion means are located on the surface of a defined circumscribed cylinder by the rotation of the cutting edge around the axis of the cutting tool.
15. 15) The cutting insert, as claimed in clause 14, further characterized in that the transition edge portion means are helical.
16. 16) The cutting insert, as claimed in clause 11, characterized in that the side face of the insert, adjacent to the cutting edge includes a relief surface, curved without interruption, adjacent to each portion of uneven edge, and where the less a portion of the relief surface between said cutting edges and said side face is rounded to reinforce the strength of the cutting edges.
17. 17) The cutting insert, as claimed in clause 11, characterized in that the upper face includes a sweeping surface, curved without interruption, adjacent to each uneven edge portion.
18. 18) The cutting insert, as claimed in clause 10, further characterized in that the uneven edge portions of the cutting edges are disposed at an angle relative to the bottom face of the insert to increase an axial sweep angle of the cut edges. edge portions related to said axis of rotation. The cutting tool, according to clause 11, wherein a radial sweeping angle of a sweeping surface and a relief angle of said cutting edge substantially increases from the part anterior to the top of said cutting edge. ) A cutter insert for use in a cutting tool that rotates about an axis, comprising: a) an insert body including a lower face, an upper face, and a side face extending between the lower and upper faces; b) a stepped cutting edge defined at the intersection of the upper face and the side face to attack and cut a workpiece and remove a cutout, said stepped cutting edge including at least two uneven edge portions, each of which creates a cutting segment, and each of these are convexly curved in such a way that said edge portions are located on the surface of a circumscribed cylinder defined by the rotation of the cutting edge around the cutting tool axis, and c) joining means the uneven edge portions for attacking and cutting the workpiece and for creating thin, spaced cut segments between the cutting segments created by the uneven edge portions to facilitate the breaking of all said trim segments, including a substantially straight transition edge portion, said transition edge portion intercepting said desni portions veiled, at an obtuse angle. SUMMARY A cutter insert (20) is provided for use in a tool called a rotary mill (10). The cutter insert (20) includes an insert body comprising a lower face (22), an upper face (24) and a side face (26). A stepped cutting edge (30) is formed at the intersection of the upper face (24) and the side face (26) to attack a work piece and remove a cutout from it. The stepped cutting edge includes at least two uneven edge portions (30a-c) which produce different cut segments, transversely spaced, during the cutting operation. The uneven edge portions (30a-c) are connected by transition edge portions (30d-e) that are disposed at an obtuse angle with respect to the uneven edge portions. The angle of the transition edge portions tend to disseminate the individual trim segments separated during the machining operation to cause a thinning effect of the trimmings between the individual trim segments. All and all the cutting edges are helically curved in such a way that the cutting edges are on the surface of a circumscribed cylinder defined by the rotation of the cutting edges around the axis of a cutter mill.