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| United States Patent |
3,567,086 |
|
Wark
, et al.
|
March 2, 1971
|
METHOD OF FRACTURING SHEET MATERIAL
Abstract
A process for fracturing sheet material, particularly sheets of polymer
material that include as an ingredient reinforcing filler material, such
as particles of siliceous compounds which are useful in resisting
abrasion; this process includes scribing the sheet along the line of
desired fracture, and subjecting the sheet to opposing forces of pressure,
especially along the score line, thereby causing a stressing of the sheet
in this vicinity and effecting its fracture along said score line. This
process is especially useful in a sustained operation wherein the sheet is
progressively moved into the instrumentalities for scribing and applying
pressure, thereby effecting a continuing fracture of the scored sheet. An
embodiment of the apparatus for performing the fracturing operation
includes a scribing instrument aligned with a sheet elevating device, such
as a skid, cooperating with a pair of offset rollers laterally of the skid
for creating the opposing forces necessary for effecting stressing of the
sheet and its fracture along the score line.
| Inventors: |
Wark; John D. (Freeport, NY), Holzwarth; Henry A. (Bayside, NY) |
| Assignee: |
Monsanto Company
(St. Louis,
MO)
|
| Appl. No.:
|
04/780,076 |
| Filed:
|
November 29, 1968 |
| Current U.S. Class: |
225/2 ; 225/96.5; 493/352 |
| Current International Class: |
B23D 31/00 (20060101); B26F 3/00 (20060101); C03B 33/00 (20060101); C03B 33/033 (20060101); B26f 003/00 () |
| Field of Search: |
225/2,3,96.5
|
References Cited [Referenced By]
U.S. Patent Documents
Primary Examiner: Yost; Frank T.
Claims
I claim:
1. A process for fracturing sheet material formed as a polymer-containing reinforcing filler material comprising scribing the sheet upon its surface along the line of the intended
fracture, applying pressure to the sheet proximate the location of scribing and along said score line beyond the point of initial scribing, applying supplemental pressure to the sheet in a direction substantially opposite to the pressure being applied to
the sheet proximate the location of the score line, said supplemental pressure being applied at a location approximately normal to the direction of the line of score whereat pressure is being applied and being of a magnitude to cause fracturing of the
sheet intermediate the point of scribing and the location where said pressure is being applied to the sheet proximate the score line.
2. In the process of claim 1 wherein the act of scribing and the application of the forces of pressure are performed immovably, and the sheet material is progressively moved into subjection to the scribing action and cooperating pressures
causing its continuing fracture along the score line intermediate the point of scribing and the location where pressure is applied to the moving sheet proximate the score line.
3. In the process of claim 2 including vibrating said moving sheet material upon the side opposite the score line and along a path approximating the alignment of the score line, said vibration being exerted between the point of scribing and to a
vicinity near the location of the continuing fracture.
4. In the process of claim 1 wherein the application of the supplemental pressure effects an angular bend in the sheet material at the location where pressure is applied to the sheet proximate the score line therein causing fracture of the sheet
along said score line.
5. A process for fracturing sheet material formed as a polymer-containing reinforcing filler material comprising scribing the sheet upon its surface along the line of the intended fracture, applying pressure to the sheet proximate the location
of scribing and along said score line beyond the point of initial scribing, applying supplemental pressure to the sheet in a direction substantially opposite to the pressure being applied to the sheet proximate the location of the score line, said
supplemental pressure being applied at a location approximately normal to the direction of the line of score whereat pressure is being applied and being of a magnitude to cause fracturing of the sheet intermediate the point of scribing and the location
where said pressure is being applied to the sheet proximate the score line, and aperturing the sheet material along the score line at the location where said sheet is to fracture along an angular turn.
Description
BACKGROUND OF THE INVENTION
This invention relates particularly to the fracturing or cutting of sheet material, especially sheet material which is brittle in texture and when cracked lacks directional control of its path of fracture, and is not pliable and soft enough as to
be sheared through use of any common cutting apparatus. More specifically, the invention relates to the fracturing of sheet material formed from a polymer containing filler material which renders the finished product more abrasion resistant and of
greater tensile and flexural strength, but more difficult of severing into a required pattern.
Heretofore, the cutting of various sheet materials, including even sheet material in the nature of vitreous compositions, or glass, were, and presently are, cut by the manual method of scribing the glass along the desired line of fracture, and
then through the manual or implemental application of force hopefully the scribed sheet breaks or cracks along the contemplated line. Since vitreous materials are so fragile in composition, they are not generally susceptible to any process or method
which allows for their fracture mechanically or automatically. Thus far, the process has usually been performed by a skilled artisan exerting his manual dexterity in this particular art. Furthermore, sheet material formed from the compositions such as
plastic or rubber have been more inclined to severance and cutting, especially if they have been molded into thin sheets, by the usual methods of shearing as through the application of any common cutting apparatus which is useful for performing such a
function. These more pliable types of sheet material are generally soft enough in texture that they may be readily cut to any particular design when acted upon by the blades of the shearing apparatus.
The problems associated with the shearing or cutting of sheet material become more acute when the sheet is formulated from a polymeric composition which incorporates a filler ingredient for the purpose of enhancing its appearance, coefficient of
expansion, abrasion resistance, and strength, among other characteristics. Examples of such reinforced polymers and their process of preparation are more accurately described in the U.S. Pat. No. 3,419,517, and owned by a common assignee. More
particularly, where the cast polymer sheet contains particles of minerals, for example, siliceous compounds, for the purpose of imbuing the sheet with abrasion resistant qualities, it becomes impractical to attempt to cut such a sheet by the common
shearing method, since a shear blade exposed any length of time to such operating conditions would readily deteriorate, and quickly dull to the point of uselessness. Furthermore, where such sheet material needs to be severed into particular designs, or
even into square sheets that may be laid as any standard floor tile, it is impractical to attempt substantial production of such a product through the exertion of manual efforts for individually fracturing each sheet, as similarly employed in the cutting
of glass or related vitreous products. Therefore, it becomes readily apparent that a process for the continuous fracture of polymer sheets through use of an apparatus and process which not only sustains the cutting operation along the intended line of
fracture, but does so mechanically with least manual participation, is a necessary and beneficial addition to the art.
It is, therefore, the principal object of this invention to provide for the continuing fracture of sheet material which contains abrasion resistant particles that normally prevent said sheet from being sheared under standard and known methods.
It is another object of this invention to provide a sheet-fracturing method which will sever the sheet material along the required line of cut regardless of its direction.
It is an additional object of this invention to provide an apparatus which automatically scores sheet material in the desired pattern and immediately fractures it through the continued advancement of the sheet to the operations of the apparatus.
It is a further object of this invention to provide an apparatus which incorporates means for applying cooperating but opposing forces which effect a stressing and continuing fracture of sheet material.
It is yet another object of this invention to provide a fracturing apparatus which is useful for cutting sheet material, and which incorporates vibrating means for weakening the sheet along the line of intended fracture.
It is still another object of this invention to provide an apparatus useful for fracturing sheet material and which is adjustable for allowing proper measuring and dimensioning of the sheet prior to and during the cutting operation.
Another object of this invention is to provide an apparatus, and method of its use, which is simple in operation and effective.
Other objects will become apparent to those skilled in the art in the light of the following description and accompanying drawings.
SUMMARY OF THE INVENTION
This invention contemplates the application of multiple forces, said forces being somewhat oriented in substantially opposing directions, for the purpose of fracturing sheet material, of the type as previously described, along a scribed or scored
line etched upon the surface of the worked sheet. It has been found that by scribing a sheet of cast polymer materials and then applying pressure to said sheet, preferably upon the side opposite to the scribed surface, that the stress developed in the
sheet effects a weakening and eventually produces its fracturing along a path that uniformly follows the line of score. Although the scribed surface of the particular sheet may reveal nothing more than a scratching indentation upon the sheet, properly
applied points of pressure in the vicinity of this scribed line produces a fracture substantially in alignment with the score. One reason that may be advanced as a basis for this action is that polymer sheets, and in particular polymer sheets reinforced
with mineral, metallic or vitreous particles can be severed in a manner which produces a gradually continuing but complete line of fracture along the sheet as distinct from a mere instantaneous breaking or cracking of the sheet as customarily occurs, as
for example, when glass is cut. For this reason, as the continuing fracture due to the stressing of the polymer sheet occurs, the point of incipient yet advancing fracture exhibits a tendency to slightly lag the area of exerted force, and therefore,
will follow any weakened path along the sheet, which in this instance, may be defined as the point of maximum stress in the sheet. This type of fracturing function has been identified in trade terminology as a "zipperlike" fracture, which may be more
technically described as a continuous cutting or severing of material through the exertion of forces with the shifting point of fracture usually slightly lagging these stress producing forces. Although the scribing of the sheet material during its
fracturing operation may or may not be essential, it has been found to comprise a useful expedient in guiding the fracture along the desired course of precise separation.
Fundamentally, the quantity of force, and the degree to which it bends the sheet material during the fracturing operation essentially depends upon the modulus of strength and flexibility inherent in the case sheet, and which more specifically
relates to the quality and character of ingredients composing the polymeric composition, in addition to the width and thickness of the sheet cast. It has been found through tests that, by way of example, in a sheet of formed polymer having a 3/32 inch
thickness and containing mineral particles for reinforcement purposes, a bend of approximately 1/2 inch in height when viewed in cross section across the point of maximum bend provides sufficient stress within the sheet to induce its continuing fracture
as the sheet progressively shifts forwardly. As to what degree of bend may be required to progressively fracture other sheets of polymer, as previously described, varies with respect to the polymeric formulation of the sheets, their densities,
thicknesses and widths, and the relationship between and the placement of the applied forces exerted upon the sheets. In any event, when all of these factors are considered and the steps of this process properly coordinated, the polymer sheet will be
induced to succumb to a fracture which traverse along the sheet substantially in a direction perpendicular to the alignment of the applied forces and following the score line, and will continue to fracture upon the application of an increased quantity of
force, or upon a shifting forwardly of the sheet through the zone of the applied forces. By way of illustration, FIGS. 1 and 2 of the drawings depict the relationship between the forces P applied to the sheet A during a fracturing operation, and the
angle of bend induced through their exertion. The height y of the bend and the breadth x of the zone of stress z created in the sheet will naturally depend upon the thickness t of the sheet. When the foregoing factors are properly coordinated, the
sheet will fracture, as at F, along the score line S scribed by the tool T.
In the particular instance where the cast polymer contains reinforcement or filler material, such as certain inorganic siliceous materials, a close inspection of the fractured sheet reveals that the fracture substantially occurs along the lateral
surfaces of the particular filler particles, as distinct from fracturing them into discrete parts. This characteristic in the severance of the sheet material is beneficial for a number of reasons: firstly, the jutting particles along the fractured edge
of the sheet provide a score line. rough finish which enhances the adhesion of the sheets to one another through the medium of an adhesive as when the sheets are applied or installed as panelling, while secondly, the substantial area of communication
between the particle surfaces and the surrounding polymeric material conveniently developes a zone of weakness during stressing produced from the applied forces which facilitates the fracturing operation. It appears that this developed zone of weakness
has the tendency to guide the fracture in following the score line. The presence of the filler particles seems to enhance the fracturing of the sheets. On occasion, where tests were conducted on sheets devoid of any filler material, even though a score
line had been scratched upon the surface of the sheet, since the lack of filler comparatively lessened the developed area of weakness in the sheet when stressed under equivalent forces, the line of fracture tended, on occasion, to meander rather than to
definitely follow a score line. In furtherance of the second benefit aforesaid, while the sheet during the fracturing process is subjected to the various forces that cause its stressing in preparation for fracture, there may be included in the process
the step of vibrating, or point vibrating, the sheet at a location just ahead of its incipient fracture with this vibrating action having a tendency to further weaken the integral structure of the sheet, probably in that vicinity where the polymer binds
with the reinforcing particle surfaces. This vibration also tends to stimulate the fracture to continue evenly, and reduces the likelihood that the fracture occurs in segments. The method for scribing, exerting the precise pressure, and for even
inducing this vibration, and the particular apparatuses employed to achieve such, will be hereinafter more accurately described.
Another desirable feature of this invention is indicated in the variety of shapes into which the sheet material may be fractured. For example, not only may the sheets be cut along a lineal fracture, but a variety of curves, and even angular
turns may be severed from a sheet. It has been found desirable, but not essential, that where the scribed line undertakes a turn at an angle upon the surface of the sheet, that as an aid to the fracturing process, a small aperture may be drilled at the
precise location of the turn so as to facilitate and induce the fracture to turn at the same point. Thus, corners may be cut in a sheet. Without the predrilled aperture, it has been discovered that the fracture generally tends to continue along a line
approximately in alignment with the direction of movement of the fracture prior to the turn, instead of diverting at the vertex of the angle. This aperturing of the sheet material lends itself to the continuous fracturing operation disclosed in this
process since a particular sheet prior to its feeding into the apparatus may be set and drilled through the aid of a jig in a singular process, immediately before advancement of the sheet to the fracturing operation. And, in this regard, it might be
remarked that proper control must be made of the velocity at which the sheet is fed through this apparatus during the fracturing process, the speed of fracture being somewhat governed by the dimensions of the sheet being cut and the application of the
forces upon it.
The apparatus contemplated for performing the foregoing process includes a supporting surface over which the sheets of polymer may be, preferably, mechanically shifted in a direction towards the instrumentalities used to scribe the sheet in the
desired pattern and for applying the necessary forces to induce a continuing fracture along its score line. Since it has been found desirable to exert a force upon the sheet to induce its inherent stressing in the vicinity of the scribed line, elevating
means mounts upon the supporting surface, with the sheet during the course of its movement shifting upwardly onto this elevating means, and a guide, at least along one edge, directs the sheet so that the scribed line is always maintained approximately
within this location of the stress, and the sheet is cut to the desired dimension. The sheet elevating means may take any form expedient for sustaining pressure upon the sheet, and its construction may be made in the form of a skid, mounted rotatable
wheel, or even a spherical roller has produced beneficial results, especially where the sheet is fractured in nonlineal directions. Ordinarily, the sheets are not of such weight that they bend sufficiently under their own load so as to cause the
fracture along the score line and in the vicinity upward of the elevating means, and therefore, preferably a pair of offset rollers are aligned laterally of the sheet elevating means and extend in a direction substantially opposite to said means, and at
an approximate adjusted height so as to exert an opposing force in relation to the pressure of said elevating means. Under properly adjusted conditions, the offset rollers will exert the desired downward force upon the lateral surfaces of the sheet and
therein induce substantial stressing of the sheet above the elevating means, and when these cooperating forces are properly coordinated, they exert a finely adjusted and regulated pressure effecting this area of induced stress and in proximity to the
score line. In this manner, the controlled stress induces incipient fracture of the sheet. As the sheet traverses through this arrangement in force exertions, the sheet can be retained motive either through external driving means, or by a mechanization
of either the offset rollers or the sheet elevating means. During the process the location of its beginning fracture appears to remain seemingly stationary with respect to the pressure exerting devices, but in effect, it will be shifting along the
moving sheet and producing the desired fracture. To cause a weakening inherently within the sheet proximate this area of stress and intended fracture, vibrations, as for example, produced through a mechanization of the inclined portion of the skid
leading up to its upward edge, such mechanization as can be achieved through operation of a cam member to produce minor vibrations, have been found to effectively weaken the sheet along the zone of intended fracture.
Regardless of the foregoing, it is feasible that proper fracturing of the sheet material may be effected by simply applying a singular force to one side of the sheet as it rests or moves across the elevating means, while the opposite side of the
sheet may be held beneath an edge securing or retaining device which may be simultaneously used in acting as a guide for the moving sheet. Such an arrangement may be particularly useful in those instances where only longitudinal fractures are essential. Such an arrangement would be especially useful under the operative conditions where the sheet material fed to the apparatus has been formed as a continuous roll, and it is constantly fed into the fracturing apparatus to be cut to a lesser width.
Although the apparatus has herein been summarily described as formed having a singular sheet elevating means with offset pressure rollers to the sides, it is equally apparent that the elevation and consequential stressing of the sheet may be
achieved through a pair of laterally disposed rollers located under the sheet with a centrally arranged roller fixed in an opposite direction and biasing the sheet over the score line for providing the degree of pressure necessary for effecting the
precise stressing needed to induce continuity of fracture. Where it is desired to produce a continuing fracture which undertakes various angular turns as the sheet shifts through this apparatus, a series of offset rollers, preferably of the spherical
roller type, may be placed equidistant from the sheet elevating means which itself may be a spherical ball-type roller, but arranged in an opposite direction. The scribing instrument may mount substantially, or approximately, above the sheet elevating
means, or is generally disposed in a direction opposite to that force-exerting roller, or the like, which causing stressing proximately of the score line. As the sheet moves through the apparatus it is scribed almost simultaneously, or perhaps slightly
prior to the application of the forces which induce its immediate fracture, and since the force exerting means, as previously described, are arranged surrounding but equidistant from the sheet elevating means, regardless of the direction of movement of
the sheet material through the apparatus, the fracture in motion undertakes a path somewhat synonymous with the course of movement of the progressively advancing sheet. Under this arrangement the stress pervades undirected throughout the area of
fracture.
The foregoing description in summary form of the sheet fracturing apparatus of this invention may be more accurately described in conjunction with an explanation of the general characteristics of the various embodiments and their methods of
operation.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings:
FIG. 1 is a schematic view of a sheet material being fractured along its score line through the application of multiple but opposing forces, and further revealing the estimated range of stress developed in the sheet;
FIG. 2 is a cross-sectional view of the fracturing sheet taken along the line 2-2 of FIG. 1, further showing the angular bend produced in the sheet through the application of the opposing forces;
FIG. 3 is a perspective view of one embodiment of the combination of instrumentalities assembled into the fracturing apparatus of this invention;
FIG. 4 is a perspective view of the instrumentalities used in combination to function as a fracturing apparatus, especially an apparatus useful for producing a curved fracture of the sheet material;
FIG. 5 is a perspective view of a further modified fracturing apparatus of this invention; and
FIG. 6 is a modification of the fracturing apparatus of this invention useful for allowing fracturing of the sheet material in any direction including fractures that make a plurality of angular turns.
DESCRIPTION OF THE PREFERRED
EMBODIMENT
The apparatus, and modifications thereto, employed in performing the process heretofore described integrates various instrumentalities that cooperatively perform each step of the preferred process. By referring to FIG. 3 of the drawings, the
sheet material A of the type that has been heretofore described, is advanced to the apparatus B either in the form of segmented sheets, or may be transferred to the apparatus from a continuous roll of similar material. The apparatus is formed having a
supporting surface 2 which may be constructed as a table or the like, upon which the sheet may be freely advanced forwardly towards the fracturing instrumentalities. Upon the upward portion of the surface 2, preferably approximate one of its sides,
there is provided a guide 3, herein disclosed as being adjustable through the agency of a combination of bolts and wing nuts 4 that project through apertures formed in the guide 3, and which further insert for sliding action through the parallel
elongated slots 5 provided through the support surface 2. Thus, the width of sheet to be acquired during fracturing may be readily determined and achieved through a quick setting of the guide 3 upon the surface, thereby setting its dimensions with
respect to the fracturing devices of the apparatus.
Mounted approximately centrally of the surface 2 and oriented generally in a longitudinal direction is the sheet elevating means 6, which is herein shown comprising an inverted skidlike portion 7 upon which the traversing sheet ascends and glides
over during the fracturing operation. To facilitate movement of the sheet onto the skid, the sheet elevating means, at its leading portion, is herein shown having an inclined edge 8 which unites with the surface 2 of the apparatus at its forward end,
and rises integrally to the upper edge of the skid 7, thereby providing unobstructed passage of the sheet from the support surface continuously up onto the skid portion during the fracturing operation. The function of the sheet elevating means, as
previously described, and as herein shown in the formation of a skid, is to exert pressure upon the underside of the passing sheet to therein cause a zone of stress along that portion of the sheet where fracturing is incident. Just forwardly of that
area where the sheet ascends to the apex of the skid there is provided a tool 9 incorporating a pointed edge 10 useful for scribing a score line upon the surface of the passing sheet and along that particular location where it is gauged to be fractured.
The tool may be rigidly but adjustably mounted to an overhead crossmember or support (not shown) integral of the apparatus so that it will be substantially unyielding during the scribing action, but at the same time, may be readily adjusted with respect
to the height of the sheet proximate the area of scribing so that a score line may be cut upon the surface of the sheet to that particular and precise depth sufficient to cause the point of incipient fracture of the sheet to coincide and follow the score
line. Since it is essential that a careful regulation in the quantity of stress developed within the passing sheet be attained, it is, consequently, required that the amount of pressure induced by the skid upon the underside of the sheet be carefully
regulated. To achieve such, a pair of camlike members 11 are also adjustably mounted to the apparatus, and more specifically to the aforesaid crossmember (not shown) previously described, with the members 11 having upturned or slightly arcuate forward
edges 12 that allow for unencumbered insertion of the sheet material under the cams and to that point where the sheet eventually encounters the full undersurface of the cams and is forced at its lateral areas into a downward direction, thereby allowing
for a precise setting of the quantity of force that may be exerted by the sheet elevating means 6 upon the passing sheet, and consequently the degree of stress developed proximate the area of fracture and the score line of the sheet. These camlike
members may be adjustably mounted to the apparatus so that the precise quantity of downward bend they produce in the sheet may be accurately regulated. The reason for exercising this control is that the amount of force exerted upon the sheet is quite
critical in determining the speed and quality of fracture of the sheet. Although it is not herein shown in this embodiment, any type of motion inducing means, such as a pair of mechanized rollers in contact with the sheet forward of the fracturing
instrumentalities, may be useful for both producing and controlling movement of the sheet material in its passage through the apparatus.
A slight modification in the fracturing apparatus is disclosed in FIG. 4, where in this particular embodiment fracturing of the sheet along a curved path may be produced. As shown, the sheet A is disposed for movement upon the supporting surface
2 of the apparatus, and the instrumentalities for fracturing the sheet, as previously described, such as the sheet elevating means 6, comprising the skid 7 with the inclined leading edge 8, produces sufficient stress in the sheet proximate the vicinity
of the score line S after its having been scribed by means of the tool 9, for effecting fracturing of the sheet. In this apparatus, the guide 13 which also mounts by means of the fasteners 4 within the parallel slots 5 is formed in a curve, and as the
sheet is moved around the guide the line scribed upon the surface of the sheet will also assimulate the curvature of said guide 13. Since the scribed line is oriented to pass substantially over the leading edge of the skid 7 the force of pressure
exerted by the skid 7 upon the sheet causes its fracturing along the score line S. Proper regulation and adjustment of the force exerted by the sheet elevating means 6 and the skid 7 may be achieved through usage of camlike members, as previously
described, or any similar type devices.
In certain instances it has been learned that by producing a slight vibration in the vicinity of the yet unfractured portion of the sheet near the score line has a tendency to weaken and prepare the sheet for its immediate fracture. To achieve
such, the sheet elevating means 6, and more specifically, its inclined leading edge 8, may comprise a separate component from the skid portion 7, with this inclined edge 8 being mechanically vibrated, as by any common means for producing vibration such
as through use of a mechanized offcenter cam being located below the table and in communication with this separated inclined edge 8, so that as the sheet passes upwardly upon this inclined edge and onto the skid 7, the vibrations induced along this edge
will be communicated to the sheet for the purposes just heretofore described. This particular cam arrangement in the embodiment is not shown.
In FIG. 5, the fracturing apparatus of this invention as a further modified structure is more completely revealed, and is herein shown comprising a supporting surface 14 having an integral crossarm 15 mounted to one side of said surface and
useful for supporting adjustably the force-exerting means, herein shown as rollers 16, which exert the lateral forces upon the sheet to cause its bending as it moves through the apparatus and over the sheet elevating means 17. A guide 18 mounted
proximate to one side of the supporting surface 14 furnishes the means for dimensioning the width of the sheet to be fractured by the apparatus. The rollers 16 are herein shown to be spherical ball-type rollers which allow for near frictionless movement
of the sheet thereunder, while these rollers simultaneously exert the necessary downward force upon a contiguous lateral portions of the sheet moving thereunder. Since these force exerting means 16 are adjustable, the quantity of pressure exerted upon
the sheet may be readily controlled and regulated, as for example, by simply turning the rollers downwardly in their threaded engagement with the crossarm 15. A scribing tool 18a, of the type previously described, also mounts to the crossarm 15, extends
downwardly, and is adjusted to that depth which will allow for its scribing of a score line upon the sheet at a location just forward to where the sheet passes over the elevating means 17. As such occurs, the elevating means exerts a force upon the
sheet, causing its bending and stressing to that degree sufficient to produce fracturing of the sheet.
The sheet elevating means is herein shown as a mounted rotatable wheel, which may be more precisely defined under more descriptive nomenclature as a bending wheel 19, and which is mounted by means of an axle 20 to the supports 21. These supports
may also be adjustable, height-wise, with respect to the surface 14, and therein provide for a variation in the elevation of the bending wheel, and therefore, the degree of bend formed in the passing sheet. In addition, it is conceivable that this sheet
elevating means 17 may also be both mechanically operated and rotated so as to form the means for inducing movement of the sheet thereover, and further, that this elevating means may be mounted in a manner to create mechanized vibrations that can be
exerted upon the sheet in the vicinity of its stressed and scribed area thereby weakening it for its impendent fracture. Means for inducing a mechanized rotation of the wheel 19, or even for causing its vibration are rather known in the art and may be
readily incorporated within this apparatus. For example, a cam 21a rotated by means of the rotor 21b may be biased against the lower portion of the supports 21 so as to induce the desired vibrations upon operation.
This invention also embraces the angular fracturing of the sheet material, as distinct from the lineal or curved forms of fracturing through operation of the type apparatuses previously described. For example, it may be desirable to fracture the
sheet material along a right angular cut, or in a pattern which produces a saw-toothed or similar edge along the side of the fractured sheet. The pattern of fracture of the sheet material is substantially dictated by the path of movement of the sheet
through the apparatus, and in this regard, the type of guide employed along the side of the supporting surface of the apparatus may precisely control to fairly accurate dimensions the pattern of fracture of the sheet material. One such embodiment of the
fracturing apparatus for producing cuts of the sheet material at right angles is disclosed in FIG. 6, wherein a supporting surface 22 is of sufficient dimensions so as to accommodate the size of sheet material passing thereover, and is of sufficient
rigidity to endure the movement and forces produced during the fracturing operation. The guide 23 being adjustably and slidably mounted to the surface 22 in a manner as previously described and in association with the other embodiments of the apparatus,
is herein shown having a pair of right-angle bends, which during movement of the sheet therealong will produce angularity in the cut of the sheet when fractured through operation of the fracturing instrumentalities of the apparatus. The sheet elevating
means 24 is herein disclosed comprising an adjustable spherical ball roller having a height above the surface 22 which may be approximately less than half its diameter so as to prevent any obstruction to the passage of the leading edge of the sheet
thereupon and over as at the commencement of a fracturing operation. This roller is adjustably mounted to the supporting surface so that its height projection may be accurately set to a desired level, higher or lower than previously described. In
addition, the elevating means is of the ball type so that the sheet may pass unobstructively in any direction. The force exerting means, which are disposed laterally of the sheet elevating means, are herein disclosed as a series, in this particular
instance, three ball rollers 25 which are disposed downwardly from a crossmember or support (not shown) of the apparatus. These rollers are disposed equidistant around the sheet elevating means, and when properly adjusted, exert force upon the sheet at
positions laterally from said sheet elevating means and to such a degree as to create a zone of stress in the sheet that pervades throughout the vicinity surrounding the sheet elevating means or roller 24. As a result, as the sheet moves through the
apparatus and is scribed for a small distance along the line S by means of the tool 26, regardless of the direction of movement of the sheet, the tool will score a line that coincides with the direction of movement of the sheet, and the stress having no
bearing will cause its fracture along any oath the score line takes. As an illustration, as the sheet moves forwardly upon the supporting surface 22, the line of scribe will be substantially longitudinally oriented, and fracture will occur along that
line. But, as the sheet encounters the lateral portion 27 of the guide 23, and is shifted laterally, the line of scribe will likewise be towards the side of the sheet resulting in the fracture following this orientation in the score line and producing a
90.degree. turn in the fracture. Furthermore, as the sheet reaches and eventually is moved along the second longitudinal portion 28 of the guide, the line of scribe will again undertake another 90.degree. turn resulting in the course of fracture doing
likewise. Thus, depending upon the shape of the guide 23 utilized in conjunction with the fracturing apparatus, the form of cut made upon the sheet will be determined accordingly. As previously discussed, apertures may be drilled at the location of the
turns in the fracture so as to facilitate the process.
It should also be remarked with regard to the association of the various fracturing instrumentalities being employed in this particular embodiment of the apparatus that the scoring tool 26 is preferably located and scribes a line almost
substantially above the sheet elevating means 24, since to locate the tool any distance from this particular position will result in the line of scribe being too far behind or offset from the point of pressure produced by the sheet elevating means,
especially when the sheet is being moved laterally along the portion 27 of the guide. It has been found that through scribing of the sheet substantially above or close to the point where pressure is exerted by the sheet elevating means, there is still
produced adequately proximate scoring of the sheet sufficient for guiding the fracture along the moving sheet. As previously discussed, the sheet elevating means of this embodiment may likewise be subjected to slight mechanical vibration so as to
produce a weakened zone in the sheet in preparation for its impending fracture.
Numerous variations in the construction of the fracturing apparatus of this invention, or even within the sequence of steps set forth in the process for performing this fracturing of sheet material, will occur to those skilled in the art in the
light of the foregoing disclosure. The particular described method for performing this fracturing operation, and the various embodiments of the apparatus analyzed are merely illustrative.
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