CA2265086A1 - Band saw apparatus and method for production cutting of sheet type material - Google Patents

Abstract

The present invention relates an apparatus, which employs band type blade in a mass production cutting technique that accurately and quickly reduces sheet type material such as textiles, sheet wood, sheet wood composites and other sheet materials, into usefully shaped and sized pieces.

Description

Technical field Rotating band saws, reticulating saws, and automated derivatives thereof, are employed where curved cuts are desired. They reduce a workpiece of sheet type material to usefully shaped and sized pieces, generally by cutting from some 15 determined point at the edge of the worksheet, along a marked or determined planar path on the worksheet surface, to some other determined edge point, and repeating until all determined planar paths have been cut, and all usefully shaped and sized pieces have.thereby been extracted from the original sheet.
A blade and worksheet are displaced relative to one another so that a moving 20 blade cutting edge contacts the worksheet and cuts at the point of contact.
Movement is created either by rotation of a continuous loop blade mounted in guides and driven by a pulley, or by reticulation of a blade segment attached by one or both ends and moved rapidly in a sawing motion.
Mass production techniques employ autonomous or semi-autonomous machines 25 to repeat the same cuts for many sheets of material. A template, digital or physical, represents worksheet to blade movement relationships, and directs cutting. Sensing, feedback, and control mechanisms ensure cutting progress is confined as best as possible to the determined planar path.
Previous improvements to cutting efficiency include better cutting edge or tooth 30 design, material specific tooth design, stronger more durable cutting edge, faster blade action, unique blade movement patterns.
Previous improvements to automated processes include better control of blade from deviations to planar path, and considerations of work and material flow.
It is the object of the present invention to describe a new and useful apparatus 35 employing band type blades to cut sheet type material along planar paths, and repeat the same pattern of cuts for many sheets of material. It is fiuthur the t object of the present invention to decrease the cutting time, reduce cutting costs, and increase the range of shapes and curves employed to create greater variety in mass-produced items.

Specification The present invention is an assemblage and ordering of component parts into a cutting apparatus suited to a predetermined pattern of cuts. Cutting occurs along whole lines of cut. The cutting direction is adapted to proceed from the surface of a worksheet, through its shorter thickness dimension, to the opposite surface.
For a simpler description the following terms are defined.
A 'cutter bed' is a sheet of fairly rigid material with two flat parallel sides, probably rectangular, allowing relatively easy and secure attachment of component parts. An example of a cutter bed is a plywood sheet.
A 'line of cut' is a marked or otherwise determined path to be cut, linear and or curvilinear, along the plane surface of a worksheet.
A 'blade' is a band type blade, two mainly flat parallel sides, width much greater than thickness, length to suit specific application, a cutting edge suited to cut a desired worksheet material, selected rigid and elastic properties.
Assume for descriptive purposes that the blade cutting edge describes a straight line when the blade is laid flat on its side.
'Proper orientation' means the plane sides of a blade conform to a cylindrical surface, and a plane contains the lines or curves made by its cutting edge.
A 'vibrator' is a prime mover, which offers good force to reticulate a blade.
A 'blade segment' is the arc length of band type blade which equals the arc length of a desired line of cut minus the overall distance a vibrator is set to reticulate the blade.
Flexibility of a band type blade allows the line of the cutting edge to be adapted to match the shape and proportion of a desired line of cut by varying the surface revolution of the relatively thin flexible sides along the length of the blade.
Consider curves possible within the elastic limits of a given blade.
A blade segment cutting edge is maintained in a desired shape by a guide. Said guide engages both smooth sides of the blade and conforms said blade segment along its arc length, by increments and or continuously, by rolleable and or slideable means, to describe a planar path that matches the shape and proportion of a desired line of cut. Said guide is affixed securely to a cutter bed. Said guide maintains a blade in proper orientation, with the plane containing the cutting edge parallel to the plane of the cutter bed surface. Said blade segment is allowed to travel along the path defined by its guide. Said guide directs and confines reticulate motion of a blade segment, by said rolleable and or slideable means, along the planar path matching a desired line of cut. Said guide is positioned behind the cutting edge to allow a portion of the blade width to project beyond said guide, to allow unimpeded blade cutting and penetration of the thickness of a chosen worksheet material. Guide and blade are further adapted to each other, by increments and or continuously, along the arc length of a guided blade segment, so that the cutting projection height is maintained.
A vibrator is affixed to the cutter bed and engages a blade segment, behind the cutting projection, to impart forced reticulate movement to the blade segment.
Said force is projected in a direction generally asymptotic to the cutting edge subtended to the place of vibrator-blade engagement. Said force is transmitted along a blade segment through blade rigidity and confined to a desired planar path by its respective guide. Said force is appropriate to cut a given worksheet material along the arc length of said blade segment. Where one vibrator is insufficient to deliver the appropriate force, a series of syncronously acting vibrators spaced along the blade segment, are used.
Numerous independent guides are affixed to a cutter bed surface, to match the shape and spatial relationship of blade segments to numerous respective desired lines of cut. Each guided blade segment is equipped with vibrator or vibrators.
An assemblage of guides, blade segments, and vibrators, affixed to a cutter bed, may be manoevered as a whole, and displaced relative to the surface of a worksheet for a cutting operation.
A guide may be modular, or continuous and flexible, or chainlike, for easy deployment and fixed attachment to a cutter bed surface.
Varying design properties and proportions of blade and guide allows varying thicknesses and types of sheet material to be cut.
The illustration of a preferred embodiment should not be construed to limit the underlying principals of the present invention.
The preferred embodiment of the present invention will be discussed with reference to the following illustrations.
Figure 1 is a partial topographical view of a cutter bed surface showing four types of modular guide units maintaining blade segments on respective planar paths. Four types of guide units are rolleable, slideable, small profile rolleable, and powered.
Figure 2 is an enlarged partial view of figure 1 showing modular guide units and one blade segment abutting another.

Figure 3 is a topographical view of a modular rolleable guide unit.
Figure 4 is a vertical cross section of Figure 3 at A-A showing the workings of a mlleable modular guide unit.
Figure 5 is a topographical view of a modular small profile rolleable guide unit.
Figure 6 is a vertical cross section of Figure 5 at B-B showing the workings of a modular small profile rolleable guide unit.
Figure 7 is a topographical view of a modular slideable guide unit.
Figure 8 is a vertical cross section of Figure 7 at C-C showing the workings of a modular slideable guide unit.
Figure 9 is a topographical view of a modular powered guide unit.
Figure 10 is a vertical cross section of Figure 9 at D-D showing the workings of a rolleably engaging power transmitting modular guide unit and vibrator.
Figure I 1 is a side partial view of a blade indicating adaptations to the side of a blade.
Preperation of a cutter bed is a complex task involving stress and force calculations to optimize best placement of modular guide units and vibrators.
Best placements can be calculated using a computer. A life sized printed overlay, applied to the cutter bed surface, showing component placements, aids attachment of guides and vibrators.
Components represented are symmetric. For example, reference to 'rollers 8' means both left and right rollers.
Figure 1 shows sample configuration of a cutter bed surface 1 with affixed modular rolleable guide units 2, modular slideable guide units 3, modular small profile guide units 4, and modular rolleable power transmitting guide units 5, maintaining blade segments 6 along their respective planar paths. Blade, seen topographically, is in proper orientation, so only the cutting edge is visible.
Affxed to the opposite surface of the cutter bed are vibrators 7, shown as hidden outlines. Power transmitting modular guide unit provides indirect blade engagement for a vibrator. Coming through the cutter bed, by way of a hole 16, are vibrator drive shafts 17, seen better in figure 10.
Figure 2 shows the means of directing a blade segment 6 to an abutment with another blade segment. Slideable modular guide unit 3 guides a blade segment 6 to its end. Slideable guide unit is topographically shaped to allow close placement between other guide units. Rolleable modular guide units are spaced closely along a planar path to provide incremental support and blade direction.
Small profile modular guide units are placed as an alternative to rolleable guide units where space is limited.
The desired properties of a blade will offer an optimum combination of high elasticity; high tensile and compressive strength; relatively high structural rigidity over such relatively short stretches as the interstices between guide rollers and blade projection p. Elasticity is necessary to maintain blade functionality, predictability, and accuracy through various desired curves.
Tensile and compressive strength are necessary to transmit force along the length of blade. Rigidity is necessary to maintain blade form through unguided interstices and blade projection p.
Figure 4 shows structural elements of a modular rolleable guide unit maintaining blade segment 6 and cutting edge 22 in proper orientation. Bearing members 8 are fixed to guide unit support structure 10 and guide unit base 12, at connections 15. Bearing members provide support and low friction surface to the hollow of cylindrical rollers 9. Rollers rolleably engage the smooth parallel sides of blade.
Blade engagement is enhanced by slight convergence of bearing members 8, and through them rollers 9, to provide holding force or pincer grip to the opposite sides of the blade. A roller surface of an affixed rolleable guide unit, engaging a blade, is normal to the planar surface of the cutter bed and is in parallel surface contact with the smooth sides of a blade segment; rollers maintain parallel surface contact with a reticulating blade. Roller and bearing structure transmits occurant forces of cutting to the larger guide base, and there dispersed in the cutter bed. A guide is affixed to a cutter bed by fasteners 11. Rolleable engagement of the smooth sides of a blade along roller surface and said blade rigidity provides necessary structural guidance to maintain blade projection p in proper orientation and on desired planar path.
Figures S & 6 show the small profile rolleable guide unit. Support structure and bearing functions are merged. Plates 28 offer circular apertures to hold and maintain bearing supports 27 in proper special relationship to each other.
Plates have grip surface 29 to hold guide position on cutter bed. Fasteners 30a holds unit together. Fasteners 30b affix unit to cutter bed.
Figures 7 8c 8 show modular guide with slideable guide surfaces 23 holding blade 6. Support structure 24 transmit occurant forces to the cutter bed.
Fasteners 26 fix guide to the cutter bed.
Figure 10 shows the preferred form of vibrator-blade engagement as rack and pinion. A power transmitting guide unit 5 has gear rollers 18 offering rolleable guidance and power transfer to blade. Gear rollers have teeth 19 around the roller circumference, equally spaced and with suitable form to conjugally engage a rack type gear adaptation 20, running the length of the blade. Power transmitting guide unit has bearing cradles 21 to provide low friction and support for gear rollers. Gear rollers have an internal profile adapted to accept the external profile of a vibrator driveshaft 17 for a transfer of force. Rack and pinion converts rotational reticulations of vibrator drive shaft into linear reticulation of the blade segment.
The overall distance a blade will be reticulated, here called throw, is determined at the vibrator. Throw must enable a cutting edge to perform its cutting action completely. Accurate match of throw and blade segment length is important to completely cut a desired line of cut. Too large a throw or too long a blade segment will cause damage to blades at abutments.
Angular forces generated in the blade segment finm forced reticulation, and IS material resistance to being cut, would tend to vary projection height.
Differences in projection height, given high strength in width axis would translate to torsion in the weaker blade thickness. Torsion would vary cutting edge from the desired line of cut. A blade-guide adaptation is used to maintain control of blade projection height p. Channels 14, along the sides of blade 6 seen in profile in figures 4, 6, 8, 10, are entered by a raised surfaces 13 continuous or regular to the circumference of both roller surfaces and likewise continuous or regular to a slideable blade guide unit surfaces.
Forced reticulate motion along the guided length of a blade segment introduces tendencies in the blade to transform shape. Such tendencies evolve from variations in rates of acceleration and moment along a blade segment under small-source motive forces. Interstices between guide rollers i and the blade projection p are especially succeptible to transform. Prevention of undo tendencies comes through consideration of various interconnected design factors:
blade rigidity, guide rigidity, interstice i distances, vibration frequency and amplitude, feed rate of cutting through the worksheet, relative position of force between cutting and noncutting blade edges, evenly distributed force over the arc length of a blade segment. Relatively high blade rigidity over short distances provides the main resistance to transformation. Blade-guide adaptation 13 to resists torsional tendencies along curved sections of blade from being convened into changes in cutting projection height. A relatively slow cutter bed feed rate to worksheet surface and low vibration frequency at the onset of cutting heavier worksheet materials allows accurate cutting edge entrenchment into the worksheet. Said entrenchement provides additional guidance to a blade segment projection.

Claims (8)

1. A cutting apparatus and method which utilizes a set of individual band type blade segments for the purpose of severing a sheet of work material, in one cutting pass, along various predetermined desired lines of cut. And where each individual blade segment is guidedly directed, by increments and or continuously, along its whole arc length, to match and maintain the shape and proportion of a respective desired line of cut to a worksheet. And forced movement of a blade segment is made to occur, and allowed to occur, in reticulating fashion, along a direction defined as generally asymptotic to every point along the arc length of said desired line of cut. And each of said set of guided blade segments is likewise set in motion. And where the entirety of reticulating cutting edges of said set of blade segments, is guidedly directed as a whole to contact and cut a worksheet from a planar surface, and through its thickness.

2. A guide, as claimed in claim 1, uses rolleable and or slideable means to engage the sides of a blade segment to conform said blade segment, continuously and or by increments, along its arc length.

3. A band type blade, as claimed in claim 1, is adapted along its length to accept a projection or raised formation extant or regular to the circumference of a rolleable guide roller.

4. A band type blade, as claimed in claim 1, is adapted along its length to accept a projection or raised formation extant or regular linearly along a slideable guide slide.

5. A guide, as claimed in claim 1, which rolleabley and or slideabley engages a band type blade is adapted to accept a projection or raised formation along the length of the band type blade.

6. Where force used, as claimed in claim 1, to reticulate a blade is electromechanical and or pneumatic and or hydraulic.

7. A rolleable guide, as claimed in claim 2, creates a pinion type adaptation to a rack type blade adaptation for a transfere of force.

8