IL39970A - Cutting or abrading elements - Google Patents

Description

CUTTING OR ABRADING ELEMENTS ' iis invention relates to cutting and/or abrading el ment of sheet material for cutting and/or- abrading wo kpieces.

According to the invention there is provided .a cutting and/or abrading element of sheet■ material for cutting and/or abrading of a workpiece by movement of the element over the workpiece in a working direction, (said working direction beis vectorially either the same as or at an acute angle to a "forward" direction of a longitudinal axis of the element, depending upon how the use,) said element comprising a multiplicity of spaced .apart apertures therethrough, said element also comprising a corresponding multiplicity of teeth, each tooth having a substantially straight cutting edge extending widthways of an associated aperture, each tooth being located adjacent a trailing edge of the associated aperture, the length' of the element in the direction of its axis being at least a plurality of times t e length of each aperture, the width of the element transverse!:, of its axis being at least a plurality of times the width of each aperture, characterised in that the orientations of the cutting edges of the teeth change progressively from one part of the element to another part of the element.

In two embodiments of the invention, given by way of example, the associated apertures and teeth are arranged in rows extending across the element from adjacent one side to adjacent an opposite side of the element. In both embodiments the rows are curved so that each row is concave to the front, relative to the forward direction of the axis, each row defining an arc of a respective circle and the working edge oi. each tooth "being oriented so as to be substantially tangential ■ to the respective arc- In both embodiments, the rows stop short of the two sides, (although this is not essential,) to leave border regions without teeth and without associated apertures,. The phrases "ad acent one side" and "adjacent an opposite side" should be construed accordingly.

In a first one of the embodiments, the centre of said circle lies on the longitudinal axis of the element and the working edges of the teeth are oriented to extend substantially perpendiculary to the longitudinal axis of the element in a middle region (which includes said axis) of the element and are oriented to extend at acute angles to the forward direction of the axis in side regions of the element, said side regions being on opposite sides of the middle region, such that the outer end of the working edge of each tooth is further forward relative to the forward direction of the axis than the corresponding inner end in said side regions.

In this first embodiment, the teeth and associated apertures are. arranged so that each space between adjacent teeth and associated apertures is immediately in front of another tooth and associated aperture and/or is immediately behind another tooth and associated aperture, relative to the forward direction of the axis.

In the second embodiment, the centre of said circle lies to one side of the longitudinal axis of the element.

In this second embodiment, the working edges of the teeth are oriented to extend substantially perpendicularly to the •longitudinal axis of the element in a first region of the elemen said first region being a region wholly to one side of the longitudinal axis of the element; the teeth and associated apertures in said first region. are arranged so that each space between adjacent teeth and associated apertures is immediately in front of another tooth and associated aperture and/or is immediately behind another tooth and associated aperture in said first region relative to the forward direction of the axis; the working edges of the teeth each extend at an acute angle to the forward direction of the axis in a second region of said element; said second region being a region wholly to an opposite side of the longitudinal axis from the first region, so that the outer end of the working edge of each tooth is further forward relative to the forward direction of the axis than the corresponding inner end in said second region; and the teeth and associated apertures in said second region are arranged in columns one directly.behind another relative to the forward direction of the axis.

Preferably each tooth and associated aperture is produced by means of a punch and die, the die face having an aperture to receive the punch and a chamfer along one edge of the die aperture so that the punch in forming the aperture pushes the tooth into the chamfer so that the tooth projects from a face of the element before the punch and die together shear a blank from the element so as to form the tooth and associated aperture The element may be flat or curved transversely or curved longitudinally.

The element if flat or curved transversely may have face of the element if. the element is flat or to the chord of the arc of the element (on the concave side) if the element is curved transversely.

The invention will be described by way of example with reference to the accompanying drawings, wherein: - Figure 1 is a plan view of part of a member of sheet metal being formed into a cutting or abrading element forming the above-mentioned first embodiment of the invention; Figure 2 is an enlarged fragmentary section through one aperture and surrounding parts of the member in Figure ; Figures 3A and 315, referred to collectively as Figure 3i are a plan view and a side elevation of a stripper plate used in making the element; Figures 4A and 4-B, referred to collectively as Figure 4-, are an underneath plan view and a side elevation of a punch assembly used in making the element; Figure 5 is a plan view of a centre die used in making the element ; Figure 6 is a plan view of an inner ring used in making the element; Figure 7 is an enlarged section on line A-A in Figure 6; Figure 8 is' a plan view of an outer die used in making the element; Figure 9 s a plan view of another cutting and/or abrading tool element forming the above-mentioned second embodiment of the invention; Figure 10 is a scrap- view of part of the element of Figure 9 to an enlarged scale; and Figure 11 is a scrap view of another part of the element of Figure 9 also to an enlarged scale.

Referring to Figure.1, there is shown a sheet metal member .10 of 0.020 inch thickness. The member 10 is' shown as having ■ a pair of rows 11 and 12 of apertures 5 therein arranged so that one row 12 is behind the other row 11 in relation to a "forward" direction of a longitudinal axis 19 of the element, ectorial^ fcke sam k U "wo r k i oj " d rre io ^ ^indicated by an arrow 1 . There are seven apertures 15 spaced apart from each other in row 11 and six apertures 13 spaced apart from each other in row 12. Each aperture 13 is 0.1G2 inch wide by 0.0715 inch long. There is a gap of 0.0715 inch- between adjacent apertures in each row 11, 12.

Referring to Figure 2, (in which the- direction left-to- right corresponds .to arrow 14 in Figure 1), a portion 15 of the member 10 protrudes from a surface 16 of the member 10, adjacent a trailing edge of the associated apertn.re, to form a tooth with a substantially straight cutting edge 1? extending widthways of the aperture. The portion 15 is along a trailing edge of the respective. aperture Ί3 in relation to the working direction of the element. Each row 11 and 12 is curved, as shown in Figure 1, in such a direction that each row 11, 12 is concave to the front, that is, in the forward direction of the longitudinal axis 19» More particularly, the centre-line 18 of row 11 is an arc of a circle of radius 1.722 inches centered on the longitudinal axis 19 of member 10, whilst the centre-line 20 of row 12 is an arc of a concentric circle of radius 1 .878 inches, also centered on the axis 19· Referring to Figure 2 , portion 5 measures about 0.04-1 horizontally from where it starts to bend at 21 , · with a radius of 0*020 inch, to working edge 7 and lias a straight portion 22 measuring 0.026 inch from the working edge 17 at an angle of between 52° and 35° to the horizontal, forming a positive clearance angle of 32° to 35° to a horizontal surface of a workpiece (not shown) being cut -or abraded. The face 23 is either vertical or positively raked at an angle of up to 5°· Further pairs of rows of apertures, not shown, identical to the rows 11 and 12 are formed behind the rows 11 and 12, with a uniform pitch of 0.156 inch between adjacent rows along the centre-line 19 of member 10. The centres of the working edges 17 of apertures 13 of row 11 are "offsett" by 0.1167 inch from the centres of working edges 17 of apertures 3 of row 12, so that each space between adjacent "side-by-side" teeth and associated apertures is (except for the rearmost row) immediately in front of another tooth and associated aperture and is also (except for the foremost row) immediately behind another tooth and associated aperture, relative to the forward direction of the axis.

Of course, it will be appreciated that. any or all of the above-mentioned dimensions and angles may be changed. ' However, they have been found to give satisfactory results.

Referring now to Figures 3 to 8 , a stripper plate 24·. shown in Figures 3A'and 3B has two rows 25 and 26 of holes 27 the centres of which are on arcs of concentric circles of the same .radii, 1 - 722 inches and 1 .878 inches,. as the circles on whic the rows 11 and 12 of apertures 13 lie. The holes 7 are spaced apart "by the same distance centre-to-centre as apertures 3» The stripper plate 2 also has a channel 28, 0.125 inch deep and 1 - 750 inches wide between side flanges 29% to accommodate the member 10. ; The punch assembly 30 shown in Figures 4A and 4B comprises a base -33 and (only f the punches 32 equal to the spacings between the holes 27 of stripper plate 24 (and corresponding to the spacings between apertures 13 of member 10) . End portions 35 of the punches 32 have rectangular cross-sections corresponding to the cross-sections of apertures 13· Rearward portions 3S of the punches 32 have cross-sections corresponding to the cross-sections of the holes 2 .

To make the cutting and/or abrading element of Figs. and 2, the punch assembly 30 is located above the stripper plate 24 and the member 10 is located in channel 28 of the stripper plate 24. The punches.32 extend through the: holes 27 into engagement with the member 10 and, after forming the aperture and teeth in member 10 as described below, are withdrawn from the holes 27 ¾ (or at least withdrawn until the tips of punches 32 are flush with the underside of plate 24 so that the plate 24 strips the blank off the punches 32 should it have adhered by friction thereto.

The centre die 37 shown in Figure 5 has seven notches 3$ in its (otherwise circular) peripheral edge 39- The die 37 is of 3.50 inches outside diameter and fits inside the inner ring 4-0 shown in Figure 6 so that the notches 8 co-operate with the inside peripheral edge 41 of ring 40 to define seven apertures corresponding in dimensions and spacings to the seven apertures 13 in row 11. An inside edge portion 42 of ring 40 is bevelled as shown in Figure 7 to cause portions of member 10 in row 11 to protrude from surface 16. The bevel is at an angle of 35° and its radius measures 0.025 inch horizontally. The' ring 40 has an outside circular edge 4 of 3.81 inch diameter with six notches 44 therein. The ring 40 fits inside the outer disc 45 shown in Figure 7 so that the notches 44 co-operate with the inside peripheral edge 46 of die to .define six apertures corresponding in dimensions . and spacings to the six apertures 13 in row 12. An edge portion 47 of the die 5 is bevelled in the same way as edge portion 42 of ring 40 to cause portions 15 of member 10 to protrude from surface 16 in row 12.

In operation, the punch assembly 30 is located above stripper plate.24, the inner ring 40 is located inside the outer die 45, the centre die is located inside the ring 40. The ring 40 and the dies 37 and 45 are supported so that their upper surfaces are flush with each other and in contact with flange 29 of stripper plate 24. The member 10 is then fed through the channel 28 and the punch assembly 30 is operated repeatedly to produce pairs of rows 11 and 12 of apertures 1 in the member Ί0, the member 10 being advanced 0.312 inch between successive operations of the punching assembly 30. When the member 10 is "full." of rows of apertures, it is lengths, each of which is to form a cutting or abrading element in accordance with the invention. If necessa further forming' operations may now he carried out upon each length to adapt it to form part of or he incorporated in a cutting or ahrading tool.

The lengths are then heat-hardened in known manner.

Grinding is not believed to be necessary, since the shearing of the member 10 involved in the production of the apertures 13 produces the positive clearance angle of 32° to 35° and the face 23 of ,0° to 5° positive rake.

When a cutting or abrading element produced from the member 10 is used, it is moved across a surface of a workpiece (not shown) in the direction of arrow 14- or a working directio at a small angle thereto and pressed against the workpiece.

The arrangement of the apertures 13 ?Jid cutting edge portions 15 facilitates the cutting or abrading action, the break-up of chippings and their removal through apertures.13 from the workpiece. The cutting edges 17 are flat and produce a smooth surface on the workpiece. Furthermore, the portions withstand considerable, usage.

The cutting and/or abrading tool element 50 illustrated in Figures 9* 10 and 11 consists of a generally rectangular sheet metal member having several rows of apertures therein with several apertures in each row. Figure- 9 shows four such rows 51 , 52» 53 and 54-, hut in fact there are very many more rows occupying the whole length of the element .

Each row defines an arc of a respective circle having its centre to one side of a longitudinal axis (not shown) of element 50 extending vertically in Figures 9 to 11 . As shown in Figure 9 > alternate rows have six and seven apertures spaced apart from each other therein, but may have more or less. For example, rows 5 &&d 55 each have six apertures whilst rows 52 and 54 each have seven apertures.

Each row of apertures is associated with a corresponding row of cutting or abrading teeth adjacent f af trailing edges of the apertures, the apertures and teeth. being formed in a manner analogous to the formation of the apertures and teeth of the first embodiment.

Thus, element 50 has several rows of teeth with several teeth in each row and with associated apertures for cut or abraded material to pass through, each row being arcuate in shape or curved with the concave side facing generally in the "forward" direction of the longitudinal axis of the element,' (vertically upwards in Figures 9 to 11 , ) though the working direction may be vectorially either vertically upwards i each of Figures 9 to 11 , or in the direction of arrow 55 » that is to say, at an acute angle to the "forward" direction of the longitudinal axis of the element 50 ; the rows are all one behind another in relation to the said forward direction.

The ends of the rows adjacent one side 6 of the element 50 are rearwardly displaced in relation to the corresponding ends of the rows adjacent the other side 57 of the element 0 $ having regard to the forward direction of the axis of the element and to the working direction in which it is moved during cutting or abrading.

As shown clearly in Figure 11 , the cutting, edges 5S /.¾·"-■£ and 58 near the first-mentioned ends of the rows (adjacent side 56) extend substantially perpendicularly to the longitudinal axis, that is, substantially perpendicularly to side 56 and are laterally staggered in relation to each other, (see for example the cutting edges 58a near the ends of rows 51 and 53 adjacent side 56 , ) which are further away from side 56 than the cutting edges 5Sb, near the ends of rows 52 and 5^ adjacent side .

As shown in Figure 10 , the cutting edges 58c > near the ends of (all) the rows adjacent . side 57 make respective obtuse angles, such as angle 59 » with side 57 » so that the outer end of each tooth is further forward than its inner end relative to the forward direction of the longitudinal axis of the element 50 ; the cutting edges 58c lying in columns substantially one directly behind another in the forward direction of the longitudinal axis of the element, with only significant lateral staggering, (too little to be shorn in the drawings) „ The ' element 50 has hooks 60 at the ends thereof for . attachment of the element to a holder, not shown.

If the holder is of a form similar to known "Surform" ("SUEFOBM" is a Registered Trade. Hark) blade element holders used with "Surform" blade elements of the same shape in outline as the element 50 , it may be found more convenient to move the element 50 in a working 'direction as indicated by arrow 55 ? (at an angle of about 55° to the forward direction of the longitudinal axis of element 50 , ) or in a- working direction at another angle in the range of, say, 10° to 45° to the forward direction of the longitudinal axis of the element 50 , than actually in the forward direction itself of the longitudinal axis of the element 50, in which case the cut or abrasion produced by the element in the region adjacent side 57 will be of a different nature from the cut or abrasion produced by the element in the region 56· In both the element of Figures 1 and 2 and the element 50 of Figures » 10 and 11, since each tooth is 'located at a respective position on an arc of a circle as described above, with its cutting edge substantially tangential to the arc at that position, the orientations. ofthe cutting edges of the teeth change progressively along each arc, just &s the orientations of tangents to each arc change progressively along the arc.

The above-described and illustrated elements are comparatively inexpensive to manufacture, the tools required being of simple forms. The elements cut both metals and plastics well. with good chip clearance in the case of plastics.

Cutting elements in accordance with the invention may be flat or may be transversely or longitudinally curved, as mentioned above. They may alternatively be cylindrical, that is, of circular cross-section, or of U-shaped cross-section or three-sides-of-a-rectangle (including a square) cross-section or cf V-shaped cross-section, for various cutting tasks.

Claims (1)

1. Appln.No. 39970/2 / ^ C L A I Μ S t - ' ' 1. A cutting and abrading blade of sheet material having a forward end and adapted for stabilized linear movement over a vorkpiece in a direction generall toward said forward end, said blade comprising a multiplicity of individual spaced-apart apertures and a multiplicity of associated cutting teeth forming the trailing edges of said apertures, said teeth having substantially straight working edges, the apertures and associated teeth bein arranged in arcuate rows extending across said sheet material, each row defining an arc and being comprised of a plurality of said individual apertures and associated teeth to effect discrete multiple chip removal of material by each row of teeth, said rows., being generally concave relative to the said forward end, the orientation of the teeth within each row\ progressively changing aoross the sheet material so that said substantially straight edges are substantially tangential to their respective arc and a majority thereof operate at least partly in shear irrespective of the particula forward linear movement employed. 2* The cutting and abrading blade of claim 1, wherein the apertures and associated teeth in each row, are staggered relative the apertures and associated teeth in each immediately adjacent row* 3. The cutting and abrading blade of claim 1 wherein each row defines an arc of a respective circle* 4* The cutting and abrading blade of claim 3 wherein the center of said circle lies on the longitudinal axis of the blade* Appln.No. 39970/2 3. The cutting and abrading blade of claim 1, wherein the apertures and associated teeth adjacent the ends of each ro are closer to said forward end than at least a portion of the remaining apertures and associated teeth within the same row. 6. The cutting and abrading blade of claim 1, wherein the teeth include working edges oriented to extend substantiall perpendicularly to the longitudinal axis of the blade extending between said forward and rearward ends within a region immediately adjacent said axis and are oriented to extend at acute angles to said axis in regions on opposite sides of said middle region such that the outermost end of the working edge of each tooth in said side regions is further forward relative to the, axis than the corresponding innermost end* 7. The cutting and abrading blade of claim 1, wherein the teeth and associated apertures are arranged so that each space between adjacent teeth and associated apertures in one row is behind another tooth and associated aperture in