CA1061706A - Compound angle cutting edge and method of using same - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A cutting press has a resilient die pad aligned with an axially reciprocal die rule having a cutting surface defined by generally equally spaced piercing points and cutting edges between the piercing points. Each cutting edge extends from a piercing point toward a next adjacent piercing point for substan-tially the entire distance between the two. The cutting edges extending in a direction away from the die pad at an angle with a line through the tips of the piercing points of between about only one and fifteen degrees, thereby forming a generally check-marked shaped cutting surface valley between each of the piercing points, the valley having a depth of not more than three six-teenths of an inch. The piercing points thereby have to penetrate into the pad for a distance equal only to the depth of the valley for the die rule to completely cut through the thickness of the material being cut.

Description

The present invention relates generally to a cutting press, employing a novel cutting edge configuration.
Several unsolved problems have existed in the art of cutting devices prior to the present invention. For example, many cutting devices have somewhat elaborate cutting configurations which are costly to form on the cutting blade. Many other cutting blade arran~ements simply do not give a clean cut on the stock material as desired.
Still other problems arise in connection with a cutting die press. For example, many of the prior art cutting blades require a relatively high tonnage or force to press the cutting blade entirely through the stock material. In die presses where a resilient die pad is used, inordinate wear of the die pad has been experienced with various types of notched blades because of the cutting blade cutting away the die pad after it has sliced through the stock material. If a hard metallic back up die pad is used, the cutting blade is dulled by metal-to-metal contact after the cutting operation.
Specific examples of prior art cutting blade configura-tions are disclosed in United States Patents Nos. 3,277,764 to Henc, 3,422,712 to Lovas, and 201,104 to Frary. Each of these ~ prior art devices likewise include inherent disadvantages not `~ experienced by the present invention.
In short, the prior art does not provide the overall `~ range of advantages or the structural arrangement or method of cutting edge disclosed herein.
According to the present invention, there is provided a -~ cutting press including a resilient die pad aligned with an axial-ly reciprocal die rule, the improvement of the die rule having a cutting surface defined by (a) a plurality of generally equally .:
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spaced piercing points and (b) a plurality of cutting edge between the piercing points, each of the cutting edges extending from a piercing point toward a next adjacent piercing point for substantially the entire distance between the two piercing points, the cutting edges extending in a direction away from the die pad at an angle in side elevation of the die rule with a line through the tips of the piercing points of between about one and fifteen degrees, thereby forming a generally check-marked shaped cutting surface valley between adjacent piercing points, the valley having 1~ a depth of not more than three sixteenths of an inch, and the die rule piercing points thereby having to penetrate into the resi-lient die pad for a distance equal only to the depth of the cutting surface valley for the die rule to completely cut through the thickness of the material being cut.
This invention will more fully appear from the following description of an embodinlent with reference to the accompanying drawings, in which:
Figure 1 is a schematic, cross-sectional view of a die press which includes a cutting tool having the cutting edge confi-guration of the present invention;
Figure 2 is a perspective view of the cutting tool ofFigure l;
Figure 3 is a schematic, partially cross-sectional view o~ another die press and cutting tool in combination with a punch ~ tool;
"~ Figure 4 is a perspective view of the cutting tool of Figure 3; :
, Figures 5-10 are perspective views of various cutting ` tools which may include the cutting configuration of the present ; 30 invention; ~ .
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Figure 11 is an enlarged, fragmented plan view of one embodiment of the cutting edge configuration;
Figure 12 is an enlarged, fragmented side elevational view of the cutting edge configuration of Figure 11;
Figure 13 is a cross-sectional view taken along plane 13-13 of Figure 12.
Referring to the drawings, Figure 1 illustrates a cutting pre~s 10 which is primarily suited for use in cutting thick or tou~h materials, such as soft metallic materials. The die press 10 includes a fixed die base 12 surmounted by and connected to mounting plate 14 in a conventional manner. A male punch 16 and a resilient stripper pad 18 are suitably mounted on top of mounting plate 14 for receiving stock material 20. The stock material is cut with a flat die rule 22 which is shown in per-; spective in Figure 2. The cutting edge of die rule 22 includes a plurality of side-by-side notched configurations 23 which form a novel cutting edge that will be more fully explained below.
Die rule 22 is mounted in a die rule mounting block 24, which is illustrated as being a wood block. Mounting block 24 is suitably mounted to a back up plate 26 which i9 connected to a punch holder 28. A compressible stripper pad 30 is also attached to mounting block 24 in conventional manner and comprises, for example, hard rubber as is somewhat conventional in the art. The die rule 22, stripper pad 30, mounting block 24, back up plate 26, ~-and punch holder 28 comprise a vertically reciprocal cutting die. ~ ~
Operation of the embodiment of Figure 1 includes -. , ' ` : - .

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1()6~7(~6 raising the cutting die so that a piece of stock material 20 may be properly positioned on male punch 16 and stripper pad 18.
The cutter die is then driven under pressure downwardly so that the die blade 22 severs the stock material to form a blank of predesired configuration, thereby leaving scrap material 33.
As illustrated, die rule blade 22 cuts through the stock material and barely extends into a slot 32 defined between punch 16 and stripper pad 18. Downward movement of the die press i~
limited substantially to the position shown in Figure 1, so that the cutting edge on rule 23 does not strike mounting plate 14. As the die rule blade 22 projects into slot 32, the stripper pad 30 is compressed. Then as the die press is raised, stripper pad 30 expands and leaves the cut stock material on punch 16.
Figure 3 illustrates a die press primarily suited for cutting soft stock material. This embodiment includes a fixed base 42 and a vertically reciprocable punch holder 44 to which back up plate 46, mounting block 48, and die rule blade 50 are mounted. In this particular embodiment, the die rule blade is cylindrical as shown in Figure 4 and includes a plurality of side-by-side notches 52 in accordance with the present inven-`~ tion~ Also in this embodiment, a punch 54 is suitably mounted in mounting block 48, and may include the cutting edge config-uration of this invention.
In operation of the embodiment in Figure 3, the punch -; holder 44 is raised from the position illustrated and a piece of stock material 56 is properly positioned on a resilient die ; pad 58. Die pad 58 is suitably mounted on the fixed base 42 and .
is comprised of a rubber or polyurethane material. Scrap - 30 material is formed during the cutting operation by punch 54, '' ~ .

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1()617(~6 the scrap being removed through a knock-out hole 60 in punch 54, as is conventional.
After the stock material is properly positioned on the die pad, punch 54 is moved under pressure by suitable power means, such as a hydraulic cylinder and pi~ton, to drive the die rule cutting blade through the stock material 56. At about the same time, punch 54 forms a scrap slug.
As shown in Figure 3, the die rule cutting edge barely cuts into the die pad. This is necessary so that the notched configuration of the cutting edge in the present invention will completely cut through the stock material. However, in later ; portions of this disclosure, it will be explained that the present invention limits the extent to which the die rule cuts into the die pad, thereby yielding one of the advantages of the present invention; i.e., greater die pad longevity, with very little resurfacing required.
From the embodiments shown in Figures 1 and 3, it can be readily seen that the cutting edge configuration of this invention can be used in a variety of ways. Figures 5-10 further illustrate that the cutting edge configuration is not limited to a die rule, per se, but is virtually unlimited in its application. For example, Figure 5 illustrates a circular hole saw 7~ having a shaft 71 and being conventional in every aspect except the novel cutting edge configuration 72 of the present invention.
Figure 6 illustrates a flat die rule blade similar to that of Figure 2 and including a shank 74. A chamfer 75 at the cutting edge of the die rule is formed by two conver-` ging, generally V-shaped surfaces. The novel cutting edge con-figuration of this invention is formed on the chamfer 75 and ".

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includes the plurality of notches and side-by-side peaks 76.
Figures 7 and 8 illustrate cylindrical die rules, or punches, 78 and 82 having respective chamfer regions 79 and 83. -In these embodiments, the internal bore of the die rule is generally cylindrical, but there still exists two converging surfaces to define the cutting edge. Notches 80 and 84 are formed on the terminus of the cylindrical die rules to define the cutting edge configuration of this invention. Each punch includes a knockout hole 77 and 85, respectively, for scrap material ejection.
Figure 9 illustrates a slitter wheel 86 including a circular hole 87 and being conventional in every respect except for the cutting edge configuration 88 of the present invention.
As is known to those who are skilled in the cutting art, a . slitter wheel traverses stock material under pressure to effect the cutting operation.
Figure 10 illustrates another version of a cylindrical die rule 90 which is substantially similar to die rule 50 illus-trated in Figure 4. Of course, the cutting edge configuration 92 is that of the present invention.
Figures 11-13 show in enlarged fashion a cutting edge configuration according to a preferred embodiment of the ~;
the present invention. From Figure 11, it can be seen that the illustrated tool is a cylindrical die rule 100, similar to that in Figure 10. The die rule 100 includes a shank 102 and a chamfer formed by converging surfaces 104 and 106. Figure 13 shows the converging sides forming an angle ~
- which in preferred embodiment, should be chosen to fall in the range of between one and thirty degrees. As discussed pre-viously in regard to Figures7 and 8, surface 104 could be cylin-- ,~ _ 1061~06 drical, but there would still exist two converging surfaces to define the die rule cutting region.
The cutting e*ge configuration includes side-by-side notches or indentations which are formed on only one of the chamfer converging surfaces, for example, by grinding.
These notches define a plurality of teeth having generally e~ually spaced peaks 108 which serve to pierce the stock material to initiate the cutting action. The notches are also configured to form a plurality of primary cutting or slicing edges 110, each extending away from one peak into an associated`notch and toward a next adjacent peak. It can be seen from Figure 12, that cutting blade edge 110 extends approx-imately 75 to 80 percent or more of the distance between two adjacent peaks. For purposes of defining the present invention, it is considered that this constitutes the primary cutting edge extending substantially across the entire distance between two adjacent peaks.
Further, it can be seen from Figure 12 that the primary cutting edge 110 forms an angle "b" with a line through 20 piercing points 108. According to the invention, this angle should be no more than about fifteen degrees. More preferably, the angle should be within the range of between about one and ive degrees.
Figure 11 also shows that cutting edge 110 forms an angle `'a" in plan view with a line through peaks 108. This angle is directly related, in general, to the slope angle of surface 104 relative to the vertical. This relationship can . .
be seen in Figure 13, wherein the notch is illustrated in phantom. In most instances, this angle "a" will be between ; 30 about one and fifteen degrees, but this is not critical. In :' .. . .... . . . ...... . . ..
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~()61~70~i die rule embodiments having a cylindrical inner bore, such as in Figures 7 and 8, angle "a" would appear to approach zero for strict geometrical reasons.
The notched configuration of the present invention also defines a pair of pyramidal notch surfaces 112 and 114 and an incidentally-occurring secondary cutting edge 116. The secondary cutting edge, of course, cuts only small portions of the stock material so that the cutting action is substantially unidirectionally along primary cutting edge 110 from one - 10 piercing point to the next. In some embodiments, edge 116 may even become purely vertical so that the entire cutting action is along a primary cutting edge 110. For definitional purposes, surfaces 110 and 116 are considered to constitute a check-marked shaped edge interconnecting adjacent piercing points.
Pyramidal-shaped surface 112, the major pyramidal surface, is bounded on one side by primary cutting edge 110 and - has a common side with secondary pyramidal surface 114. For definitional purposes, these surfaces are considered to define a generally boomerang-shaped notch configuration. However, it is not necessary that the notches be defined by these pyramidal surfaces. The important consideration would appear to be the combination of the piercing points, the major cutting edges establishing progressive angular cutting from one piercing point to the next, and the notches being formed on only one side of the chamfer.
`~ Figure 12 also illustrates that the small angle "b"
defines a relatively sha~low valley depth "d". This depth will, of course, be a direct result of the angle "b" and the distance between adjacent piercing points. For most applications of the ~0 present invention, this depth will not be more than about three _ ~ --.. . . . .

sixteenths (3/16) of an inch. In the more preferred embodiments, the depth of the valley will be no more than about 3/32, and may even be as shallow as 1/32 and 1/64 of an inch, depending upon the material to be cut. In the most preferred embodiment, the valley depth will result from angle "b" being from about 1 to 5. It will be recalled from the discussion relating to the embodiment of Figure 3 that this shallow valley depth has great significance when a resilient back up die pad supports the stock material. Specifically, for a notched die rule blade to com-pletely cut through stock material the cutting edge portion mustproject completely through the stock material and therefore into the resilient die pad material. This penetration depth is mini-mized in the present invention because of the shallow notch valley depth. Accordingly, the resilient die pad does not ex-perience the wear associated with prior art notched cutting edges.
The manner of using a cutting tool having the present cutting edge configuration is substantially identical to that ` of prior cutting tools. However, the cutting action created by the present invention is not the same as in the prior art.
Specifically, when tha cutting tool is pressed into the stock material peaks 108 pierce the material to initiate the cutting action~ Continued movement of the cutting tool through the stoc~ material results in a progressive cutting or slicing by the primary cutting edge substantially unidirectionally from " one piercing point to the next. Further, the piercing points and primary cutting edges are formed by a notch which is only on one side of the cutting tool so that stock material exerts a resistive pressure substantially on only one side of the cutting tool which creates a unidirectional cutting pressure on the -~ .

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material being cut. These overall structural limitations and cutting method steps result in the reduced tonnage requirements previously explained.
It will be understood from the foregoing description that the rate of cutting action in the direction between the pierced points on the stock material will be dependent upon the angle of the cutting edges. Specifically, the cotangent for a one degree cutting edge is 57.29, the cotangent for a five degree cutting edge is 11.43 and the cotangent for a fifteen degree cutting edge is 3.73. Therefore, with a one degree cutting edge, the stock material will be cut at a rate of about 57.29 times the rate of relative movement between the cutting tool and stock material; with a five degree cutting edge, the stock material between the pierced positions will be cut at a rate of about 11.43 times the rate of relative movement between the cutting tool and stock material; and with a fifteen degree cutting edge, `
the stock material between the pierced positions will be cut by a rate in comparison with the rate of relative movement between the cutting tool and stock material of about 3.73:1.
It is to be understood that the description and explana-tion herein is merely exemplary of the overall invention and is not intended to be limiting in any respect. For example, the cutting edge con~iguration may be formed by other methods than grindlng and may be used in all equivalent cutting tools.

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Claims (2)

The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:

1. In a cutting press including a resilient die pad aligned with an axially reciprocal die rule, the improvement of said die rule having a cutting surface defined by (a) a plura-lity of generally equally spaced piercing points and (b) a plurality of cutting edges between said piercing points, each of said cutting edges extending from a piercing point toward a next adjacent piercing point for substantially the entire dis-tance between the two said piercing points, said cutting edges extending in a direction away from the die pad at an angle with a line through the tips of the piercing points of between about only one and fifteen degress, thereby forming a generally check-marked shaped cutting surface valley between each of said pierc-ing points, said valley having a depth of not more than three sixteenths of an inch, and said die rule piercing points thereby having to penetrate into said resilient die pad for a distance equal only to the depth of the cutting surface valley for the die rule to completely cut through the thickness of the material being cut.

2. The combination as defined in Claim 1, wherein the angle between the cutting edge and the line through the tips of the piercing points is between one and five degrees and the depth of the piercing valley is approximately one sixty-fourth of an inch.