US3543625A - Method for providing precisely controlled edge on sheet material and apparatus therefor - Google Patents

Description

United States Patent Inventor Appl. No. Filed Patented Assignee METHOD FOR PROVIDING PRECISELY CONTROLLED EDGE ON SHEET MATERIAL AND APPARATUS THEREFOR 21 Claims, 7 Drawing Figs.

0.8. CI Int. Cl B26d 104 Field of Search. 83/368,

References Cited UNITED STATES PATENTS 4/1919 Hazeltine Primary Examiner-James M. Meister Atlorney- Peter L. Costas ABSTRACT: There is disclosed a method for providing embossed sheet material with at least one edge in predetermined alignment with respect to the embossments by first embossing the sheet material with a longitudinally extending rib in one side marginal portion. Supported on the sheet material is a guide member with a groove receiving the rib which controls cutting means and the guide member tracks with the sheet material so as to cut the sheet material in a predetermined location across the width thereof relative to the rib. The apparatus for performing the method includes a rotatably mounted cutting roll desirably provided with a cutting groove therein receiving the cutting means and the cutting roll is preferably adjustable axially to ensure proper alignment between the cutting means and the cutting groove.

EDGE ON SHEET MATERIAL AND APPARATUS THEREFOR BACKGROUND OF THE INVENTION Synthetic plastic sheet materials embossed with semicylindrical ribs and semispherical or parabolic formations are being used widely for providing optical effects in many applications. By reason of the tendency for such embossments to focus the light rays passing therethrough at various points depending upon theangle of incidence, relative movement between the viewer and an articleemploying such embossed sheet material can provide various interesting optical effects. One extensive application for the cylindrical rib material is the manufacture of cards and other printed materials useful for signs, point of sales displays, greeting cards and decorative accents.

A pattern of printing or a design is provided on the surface of the sheet material opposite that having the cylindrical lenses and is so devised as to comprise two distinct images. The printed image may be printed directly upon the opposite surface of the synthetic plastic sheet material or upon another substrate which is. then bonded to the synthetic plastic sheet material. Upon viewingfrom one direction, one of the two images is seen but as relative movement between the viewer and the printed article occurs, the second image replaces the first due to the variation in the angle of viewing. Exemplary of this type of structure is the disclosure of Lemelson U.S. Pat. No, 3,026,648.

More recently, there have been very significant efforts to obtain three-dimensional effects in printed items such as greeting cards, photographs and the like and these have basically made application of the principles hereinbefore described. Exemplary of the structures which have required highly accurate alinement is the disclosure of Rice et al. U.S.-

Pat. No. 3,241,429, granted Mar. 22, 1966.

In attempting to utilize continuously embossed synthetic plastic sheet material in articles which require precise alinement between printed patterns and embossed lenses, difficulties will generally be encountered since the process of extrusion and embossing produces variations in the width of the sheet material. More particularly, in order to maintain the regular spacing of the embossments on the plastic sheet from one side margin to the other, when the plastic is still. at an elevated temperature and relatively soft as it is being stripped from the embossing roll, the sheet material must normally be considerably wider than the intended width of the finished sheet material. Because the sheet is being drawn over the surface of the embossing roll. it is under some tension and there is a tendency for the heated material to elongate and narrow in width as it cools and hardens. This condition is more pronounced in the side marginal portions of the sheet material so that if a distortion-free product is desired, it has been customary to trim the side marginal portions and retain the principal body portion wherein the embossments are generally undistorted.

However, when such sheet material is trimmed, the deviation or distortion of the side marginal portions makes it most difficult to ensure precise alinement of the trimmed side edges with the embossments in the principal portion of the sheet material. For those applications where precise alinement or registry is required, as when the material itself is to beprinted or when the material is to be laminated with a printed substrate, this deviation presents most significant problems.

It is an object of the present invention to provide a method whereby embossed sheet material may be trimmed in the side marginal portions thereof to provide a side edge which is in predetermined alinement with the embossments in the principal portion thereof.

It is also an object to provide such a method which is readily adapted to deviation'in the width of the sheet material and which will readily accommodate'displacement of the sheet material axially along the surface of a support roll.

Another object is to provide such a method wherein there may be accommodated deviations in thickness of the sheet material occurring by pulsation of the extruder or irregularities in the embossing operation.

A further object is to provide relatively simple yet highly effective apparatus for precisely trimming the side margin of embossed sheet material so as to provide a side edge in predetermined alinement with embossments in the principal portion of the sheet material.

SUMMARY OF THE INVENTION It has now been found that the foregoing and related objects can be readily attained by a method in which a length of plastic material is embossed with at least one rib extending longitudinally of the sheet material in at least one side marginal portion thereof and with embossments of desired configuration in the principal portion between the side marginal portions thereof. A guide member is supported on the sheet material and controls cutting means adapted to cut the sheet material as it passes thereby. The guide member has a groove in one surface thereof receiving the rib on the sheet material and is supported at a cutting station so as to be movable to track in the direction extending transversely of the path of movement of the sheet material.

The embossed sheet material is passed through the station with the rib thereof being received in the groove of the guide member and with the guide member tracking transversely of the direction of the path of movement of the sheet material in response to movement of the sheet material in this direction. As the sheet material passes through the station, the cutting means operates to cut the side marginal portion of the sheet material at a predetermined location across the width thereof relative to the rib. Thereafter, the trimmed side marginal portion is separated from the principal portion of the sheet material to provide an edge of predetermined alinement and spacing with respect to the embossments in the principal portion thereof.

As will be readily appreciated, the preferred embodiment of the present invention utilizes ribs in both side marginal portions of the sheet material and guide means with associated cutting means to trim both side margins as the material passes through the cutting station. In accordance with one aspect, the cutting means is a simple cutting blade carried by the guide member and extending into a cooperating groove in a roll over which the sheet material is passing.

More particularly, the apparatus of the present invention incorporates a roll assembly including a rotatably mounted cutting roll and providing for passage of the sheet material about a substantial portion of the periphery of the cutting roll. A guide member support means is mounted for movement axially of the cutting roll and a guide member on the guide member support means overlies the cutting roll and has at least one groove therein adapted to receive a longitudinally extending rib on the sheet material passing about the periphery of the cutting roll. The guide member controls cutting means adapted to cut the sheet material at a predetermined location across the length thereof relative to the groove. lnoperation of the apparatus, the guide member support means may move axially of the roll in response to axial displacement of the sheet material along the surface of the cutting roll. Thus, necking in or drift of the sheet material may be readily compensated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a semidiagrammatic illustration of apparatus embodying the present invention and showing the path of synthetic plastic sheet material passing therethrough in solid line and of trimmed material in broken line;

FIG. 2 is an enlarged view of a portion of the apparatusof FIG. 1 in section intermediate along the length of the rolls;

FIG. 3 is a fragmentary perspective view of a portion of the apparatus of FIG. 1 to an enlarged scale;

FIG. 4 is a fragmentary plan view to an enlarged scale of the cutting roll portion of apparatus of FIG. 1;

FIG. 5 is a perspective view of the guide block and guide block support subassembly of the apparatus to a greatly enlarged scale;

FIG. 6 is a partially diagrammatic fragmentary sectional view to a greatly enlarged scale showing the guide block, cutting blade and cutting roll in operation with a sheet of material passing therethrough; and

FIG. 7 is a fragmentary perspective view to an enlarged scale of embossed synthetic plastic sheet material of the type used in the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Turning now in detail to the attached drawings, therein is illustrated apparatus embodying the present invention for cutting synthetic plastic sheet material generally designated by the numeral 10 and which formed by extrusion of molten metal from the fragmentarily illustrated extruder 2 into the nip between the embossing roll 4 and the back up roll 6. One configuration for the sheet material 10 in this embodiment is best seen in FIGS. 6 and 7 wherein the upper surface is provided with longitudinally extending ribs 12 of triangular cross section in the side marginal portions thereof and with longitudinally extending ribs 14 of semicircular cross section in the principal portion thereof.

On the support posts 16 is a base member 18 which has mounted thereon a roll assembly generally designated by the numeral 20 and a slitter assembly generally designated by the numeral 22. The fasteners 24 secure the base portions of the roll mounting frame 26 and the slitter support frame 28 to the base member 18, and the frames 26, 28 have spaced apart, upstanding sidewalls 30, 32 respectively, between which the sheet material 10 may pass. The sidewalls 30 of the roll assembly 20 support therein the shafts 34 of three rolls 36, 38 and 40 arranged in a triangular cluster, and a guide element 42 with arcuate faces adjacent the surfaces of the rolls 36, 38, 40 is disposed therebetween.

The sidewalls 32 of the slitter mounting frame 28 are stabilized at their upper end by the tie bar 44 extending therebetween and support the shafts 46, 48 which have their axes lying in a common plane extending normally to the base member 18. Slidably mounted on the shafts 46, 48 are slide blocks 50, 52 which secured thereto by fasteners 54 the slide support members 56, 58 which have an undercut slideway or key way (not shown) in the lower portion of the face thereof spaced from the blocks 50, 52. The pressure between the bushings 60 in the slide blocks 50, 52 and the shafts 46, 48 may be varied by the thumb screws 62.

Mounted in the slideway of the slide support members 56, 58 are slides 64, 66 which have cooperating keys (not shown) formed thereon, and the slides 64, 66 may be adjusted along the length of the keyways by the adjusting screws 68 which have their lower ends journaled in the upper ends thereof. The screws 68 are threadably received in an aperture in the upper portion of the slide support members 56, 58 so that upon rotation of the handles 70 thereon, the slides 64, 68 will be moved along the length of the keyways to vary their position vertic'ally.

Mounted on the slides 64, 66 by the fasteners 72 adjacent the lower end thereof are link connecters 74 and adjacent the upper end thereof are the guide arms 76 which are of sufficient length to project over the roll 38. Elongated connecting links 78 are pivotably mounted at one end in the link connecters 74 by the pins 80 and have pivotably mounted at the other end thereof by the pins 82 the guide block supports 84. As best seen in FIGS. 5 and 6, the guide block supports 84 have mounted thereon by the fasteners 86 the guide blocks 88, and by the fasteners 90 the cutting blade holders 92 which in turn carry the cutting blades 94 extending downwardly therefrom through the sheet material 10 and into a circumferential groove 96 in the roll 38.

The guide block supports 84 and thereby the guide blocks 88 and the cutting blades 94 are biased against the periphery of the roll 38 by the spring 98 which is disposed about the bolt 100 and serves to bias the guide block supports 94 downwardly aboutthe pivot pins 82. The pressure exerted by the spring 98 may be adjusted by varying the length of the bolt 100 between the guide block support 84 and guide arms 76. As can be seen, the bolt 100 is pivoted at its lower end in the guide block support 84 and extends through the guide arms 76 with adjusting nuts 102, 104 threadably engaged with the upper end thereof. Theadjustment of the length of the bolt 100 projecting above the guide arm 76 will vary the amount that the guide block support 84 is pivoted upwardly toward the guide arms 76 and thereby the initial compression of the spring 98. Thus, the pressure which must be exerted against the bottom surface of the guide blocks 88 during operation to effect deflection or pivoting thereof relative to the guide arms 76 can be varied to maintain the blocks 88in firm surface contact despite variations in thickness of the sheet material 10.

Turning now to FIG. 4, the roll 38 may be moved axially between the sidewalls 30 of the roll mounting frame 26 to maintain the cutting blades 94 in alinement with the groove 96 therein by the apparatus shown therein, The shaft 34 of the roll 38 has a collar 106 adjacent the inside surface of one of the sidewalls 30 and a shaft adapter 108 on the end thereof outwardly of the sidewall 30. A yoke 110 supported on the sidewall 30 has an aperture therein which threadably receives the adjusting screw 112, and the axial disposition of the roll may thus be varied by rotation of the handle 114 to move the adjusting screw 112 within the aperture of the yoke 110. The inner end of the adjusting screw 112 has a bearing 116 of larger diameter which is secured thereon by the fastener 117 and which is rotatably seated within the shaft adapter 108 and held against axial movement outwardly therefrom by the engagement of the bearing 116 against the shoulder 119.

In operation of the apparatus, the length of sheet material 10 issuing from the embossing apparatus is passed about the inner periphery of the roll 40, is wrapped about the upper periphery of the roll 38 and then is passed downwardly about the inner periphery of the roll 36. As the sheet material 10 passes over the periphery of the roll 38, the carbon guide blocks 88 are guided along the triangular ribs 12 in the side marginal portions thereof, and the cutting blades 94 incise the sheet material 10 adjacent the semicircular ribs 14 along both side marginal portions of the material.'The trimmed sheet material 120 and the scrap material 122 from the side margins thereof both pass about the roll 36, and the trimmed sheet material 120 is guided by the guide rolls 124 to a roll winder (not shown). The scrap material 122 from both side margins is guided by the guide rolls 126 for collection in apparatus (not shown).

As will be readily appreciated, the slides 64, 66 may be moved up and down by rotation of the handle 70 in order to compensate for significant changes in the thickness of the embossed sheet material 10. However, the biasing pressure of the spring 98 and the adjustment provided for the length of the bolt 100 affords compensation for the normal range of deviations in thickness occurring during operation of the apparatus with a sheet material of a preselected thickness.

As the sheet material 10 tends to displace axially along the surface of the roll 38 during normal operation of the apparatus, the guide blocks 88 will be moved axially therewith as a result of the engagement of the ribs 12 in the grooves 96 thereof. The slide blocks 50, 52 will permit this movement since they are slidably supported on the shafts 46, 48. If the ple, a vibrating cutter, or a vibrator operated shears or a hot wire cutter all may be employed if so desired. In practice, it has been found that the illustrated cutting blade has been highly efficient and avoids possible mechanical difficulties with more complex structures.

In the illustrated embodiment, the roll assembly is employed to provide a support surface for the sheet material at the cutting station and to maintain the sheet material in firm surface contact at the point of cutting while eliminating any possible buckling across the width of the web. It can be seen that the sheet material is threaded through the triangularly disposed set of rolls so that it wraps about the cutting roll through an angle of approximately 180. Thus, the sheet material lies straight in the axis of the roll and does not buckle across the width thereof since it is held firmly against the surface. However, alternative means may be substituted for the roll assembly such as a bed plate with suitable pressure plates or rollers holding the sheet material firmly against the surface thereof. Where a cutting blade is employed, or where the cutting means requires a portion extending below the surface of the sheet material, the support surface should be provided with a groove or other recess to receive that portion of the cutting member. This will minimize wear and any possibility that the sheet material will be distorted or displaced thereby.

If it is necessary that only one edge of the sheet material be trimmed, it will be appreciated that the illustrated apparatus may be modified so as to omit one of the guide blocks 88 and the supports and other elements therefor. Although it is possible to link the two guide blocks together for simultaneous movement thereof to precisely control the width of the sheet material, generally it is desirable to allow these elements to track independently inorder to ensure optimum edge alinement with the pattern of embossments despite minor deviations in width.

The guide blocks are desirably formed from a material which is relatively readily abradable such as carbon block or cake graphite or plastic. In this manner, the guide blocks may have their operating surface formed with the grooves in precise alinement with the pattern of ribs formed by a given embossing roll. More particularly, a carbon block or the like is first provided with an arcuate surface of a radius cooperating with that of the roll. The block is ground or lapped by use of lapping compound therebetween and relative movement between the sheet material and the block. The lapping com-.

pound on the surfaces of the ribs will cause the material of the guide block to wear away and produce the grooves in precise registry with the ribs in the reference sheet material. This can conveniently be done on the apparatus per se during startup of the run utilizing the first portion of the sheet material produced.

The configuration of the ribs and of the embossments may vary depending upon the.intended application. For example, the ribs may have a rectangular cross section or some other form of polygonal cross section. The embossments in the body portion of the sheet material may be parabolic in cross section or they may be, infact, semispherical or portions of a parabola arranged in some pattern across the width of the sheet material. Although generally the sheet material will be incised between the guiding ribs and the pattern of embossments, for some applications it may be desired to leave a portion of the ribs on the trimmed sheet material. Although it is possible to have but one rib in the side marginal portion for cooperation with the guide block, generally at least two and preferably 'a multiplicity of such ribs are utilized to ensure proper alinement and operation.

Thus, it can be seen that the present invention provides a method for trimming sheet materialin the side marginal portions thereof to provide side edges which are in predetermined alinement with the embossments in the principal portion thereof. The method and the apparatus therefor are readily adapted to deviation in thewidth of the sheet material and accommodate displacement of the sheet material axially along the surface of the support roll. Deviations in thickness of the sheet material produced'by pulsation in the extruder or irregularities in the embossing operation do not detract from the firm surface contact between the guide block and the sheet material so that trouble-free operation is readily attainable.

I claim:

1. In apparatus for trimming embossed sheet material to provide at least one side edge of predetermined alinement with respect to the embossments, the combination comprising; a member providing a support surface for sheet material passing thereby; guide member support means; means mounting said guide member support means for movement relative to said support surface transversely of the direction of travel of the sheet material thereby; and a guide member on said guide member support means overlying said support surface and having at least one groove therein adapted to receive a longitudinally extending rib on the sheet material passing over said support surface, said guide member controlling cutting means for cutting the sheet material at a predetermined location across the width thereof relative to said groove, whereby said guide member support means may move relative to said support surface in response to displacement of the sheet material relative to said support surface transversely of the direction of travel of the sheet material thereby.

2. The apparatus in accordance with claim wherein said member providing a support surface is a rotata'bly mounted cutting roll in a roll assembly providing for passage of the sheet material about a substantial portion of the periphery of said cutting roll.

3. The apparatus in accordance with claim 2 wherein said cutting roll has a circumferential groove therein and therein said cutting means is a blade member incising the sheet material and extending into said groove.

4. The apparatus in accordance with claim 1 wherein a pair of guide members are supported in spaced relationship overlying said support surface and control cutting means for cutting the sheet material along both side marginal portions thereof.

5. The apparatus in accordance with claim 1 wherein said combination includes means of biasing said guide member towards said support surface.

6. The apparatus in accordance with claim 5 wherein said I biasing means is adjustable to provided a predetermined amount of pressure on the sheet material and resultant resistance to deflection as a result of deviation in the thickness thereof. I

7. The apparatus in accordance with claim 1 wherein said cutting means is a cutting blade and wherein said support surface has a recess therein into which said cutting blade extends.

8. The apparatus in accordance with claim 1 wherein said mounting means includes a shaft extending transversely of the direction of travel of the sheet material and a member slidably mounted thereon to provide the support for said guide member.

9. The apparatus in accordance with claim 1 wherein said mounting means includes a pair of vertically spaced shafts extending trans'verselyof the direction of travel of the sheet material and a member slidably supported on each of said shafts, and wherein said guide member support means includes a connecting link assembly and a relatively rigid guide arm spaced above said connecting link assembly, the guide member being pivotably supported by said connecting link assembly and adjustably coupled to said guide arm.

10. The apparatus in accordance with claim 9 wherein the portion of the mounting means coupling said guide block to said guide arm comprises a bolt member and a spring thereabout biasing said guide member towards said support 1 surface, the length of the bolt member between said guide arm groove therein receiving said cutting means.

12. The apparatus-in accordance with claim 9 wherein said slidably supported members carry a slide assembly, the slidable element thereof being slidable in a vertical plane to promote adjustment of the vertical spacing between said guide member and said support surface.

13. The apparatus in accordance with claim 2 wherein said member providing a support surface is a cutting roll in a roll assembly and wherein means are provided for adjusting said roll axially in a direction transverse to the direction of travel of the sheet material, said cutting roll having a circumferential 14. In apparatus for trimming embossed sheet material to provide at least one side edge of predetermined alinement with respect to the embossments, the combination comprising; a roll assembly including a cutting roll and providing for passage of the sheet material about a substantial portion of the periphery of said cutting roll; guide member support means; means mounting said guide member support means for movement relative to said cutting roll transversely of the direction of travel of the sheet material thereby, said mounting means including a shaft extending parallel to the-axis of said cutting roll and a member slidably mounted thereon providing the support for said member support means; a guide member on said guide member support means overlying said cutting roll and having at least one groove therein adapted to receive a longitudinally extending rib on the sheet material passing about said cutting roll, said guide member controlling cutting means for cutting the sheet material at a predetermined location across the width thereof relative to said groove; and means biasing said guide member towards said cutting roll, whereby said guide member support means may move axially relative to said cutting roll in response to displacement of the sheet material axially relative to said cutting roll transversely of the direction of travel of the sheet material thereby.

15. The apparatus in accordance with claim 14 wherein said cutting roll has a circumferential groove therein and wherein said cutting means is a blade member incising the sheet material and extending into said groove.

16. The apparatusin accordance with claim 14 wherein a pair of guide members are supported in spaced relationship overlying said support surface and control cutting means for cutting the sheet material along both side marginal portions thereof.

17. The apparatus in accordance with claim 14 wherein said biasing means is adjustable to provide a predetermined amount of pressure on the sheet material and resultant resistance to deflection as a result of deviation in the thickness thereof.

18. The apparatus in accordance with claim 14 wherein said mounting means includes a pair of vertically spaced shafts extending transversely of the direction of travel of the sheet material and a member slidably supported on each of said shafts, and wherein said guide member support means includes a connecting link assembly and a relatively rigid guide arm spaced above said connecting link assembly, the guide member being pivotably supported by said connecting link assembly and adjustably coupled to said guide arm.

19. The apparatus in accordance with claim 18 wherein the portion of the mounting means coupling said guide block to said guide arm comprises a bolt member and a spring thereabout biasing said guide member towards said support surface, the length of the bolt member between said guide arm and guide member being adjustable to vary the preloading of said spring.

20. The apparatus in accordance with claim 14 wherein said slidably supported member carries a slide assembly; the slidable element thereof being slidable in a vertical plane to promote adjustment of the vertical spacing between said guide member and said cutting roll.

21. The apparatus in accordance with claim 15 wherein said roll assembly provides means for adjusting said cutting roll axially to maintain said groove therein in alinement with said blade member.

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