Manufacture of resilient foam with contoured face

Sept. 1, 1959

D. E. DAHLE

2,902,091

MANUFACTURE OF RESILIENT FOAM WITH CONTOURED FACE

Filed June 15, 1956

Sheets-Sheet 1

<img file="US2902091A_D0001.tif" />

Sept. 1, 1959

D. E. DAHLE

2,902,091

MANUFACTURE OF RESILIENT FOAM WITH CONTOURED FACE

<img file="US2902091A_D0002.tif" />

2,902,091

Patented Sept. 1, 1959

United States Patent Office

2,902,091

MANUFACTURE OF RESILIENT FOAM WITH CONTOURED FACE

Donald E. Dahle, High Point, N.C., assignor to Wood Conversion Company, St. Paul, Minn., a corporation of Delaware

Application June 15, 1956, Serial No. 591,635

Claims. (Cl. 164—39)

The present invention relates to the splitting of sheets of foamed elastomer to form two sheets each having one contoured cut face.

Apparatus for splitting sheet material into layers is well known. Material such as leather, fiber felts and thicker materials have been so cut by moving the sheet edgewise onto a cutting knife edge which cuts in a straight line. In this way, sheets of foam have been so split into thinner sheets.

The present invention relates to cutting foam materials which are resilient so that a sheet being cut may be variously subjected to compression whereby to vary the line of the cut when the cut sheet is released from compression.

It is the object of the present invention to split resilient foam sheets while both faces thereof are variously compressed at chosen locations over the cutting line to form contoured cut faces.

It is a particular object of the invention to provide the pattern of locations by use of two revolving means between which the sheet passes.

general arrangement of the parts of the apparatus whereby foam is fed to a cutting knife edge on the cutting line of which the foam is compressed by rollers.

Fig. 2 represents in elevation a portion of the apparatus shown in Fig. 1 illustrating the arrangement of the compressing rollers shown in Fig. 1.

Fig. 3 represents in cross-section two layers of foam as cut by the apparatus shown in Figs. 1 and 2, the two layers being separated along the thickness dimension.

Fig. 4 represents in cross-section on the line 4—4 of Fig. 3 the same two layers of foam, to illustrate particularly the effect of the crossbars and recesses on the parallel corrugations formed by the rollers per se.

Fig. 5 is a view of the two patterns of compression rectified from the rollers, the two identical patterns being shown with one a quarter phase behind the other.

In Fig. 1, the numeral 10 designates an uncut sheet of foamed elastomer having a uniform thickness shown only in dotted lines, as it approaches a moving cutting blade 11, of which the line of cutting lies in the plane of the axes of shaft 12 and shaft 13. The shaft 12 has a series of rollers 15 and shaft 13 has a series of rollers 16, all better shown in Fig. 2. The defining cylinders in which lie the peripheries of the two series of rollers are positioned by vertically adjusting the positions of the shafts 12 and 13 so that the cylinders compress each face of the foam 10 over and toward the cutting line of blade 11.

The rollers 15 or 16 on any one shaft may have the same diameter, and preferably all the rollers 15 and 16 30 have the same diameter. When the shafts 12 and 13 are equally spaced from the knife 11 and when the rollers are as illustrated, both faces of the foam 10 are compressed by forces applied in the same predetermined pattern, the pattern at one face being so offset from the patwu ______ ³³ tern at the other face that a symmetrical corrugation is

IHs ^particular object of the invention to provide at produced, particularly by those arcuate portioris of the both faces the same pattern of compression locations and x-j to select a pattern such that both contoured faces are the same.

rollers designated C.

The foam 10 is fed forward on conveyer belt 20 moving at a fixed rate which is the same rate as travel the “ It is also a particular object to split a sheet of foamed 40 peripheries of the rollers 15 and 16. The resulting upper elastomer into two layers with contoured faces such that ' * '’^l the high spots of one are located in positions to be opposed by corresponding high spots in the other layer.

Various other objects and advantages of the invention will become apparent from the following description and explanation.

By practice of the present invention, a sheet of resilient foam may be so split that the cut face is corrugated in the direction of the movement of the sheet over the cutting blade, and so that such corrugations of each sheet are identical with hilltops of each sheet in a plane. As a result, two such sheets may be placed in apposition with the hilltops of one opposed to the hilltops of the other, and the hilltops may be connected by adhesive or by other interposed means, such as, sheet material. Thus, a cored foam structure is readily formed.

However, such a corrugated structure has parallel bands of relatively high resistance to compression alternating with parallel bands of relatively low resistance to compression. The present invention permits varying the pat- _g0tern so that there are also crossing bands of relatively high and low resistance to compression.

Numerous patterns for the contour of the cut faces may be provided by varying the locations of compression of the foam over the cutting line. The accompanying drawings illustrate apparatus designed for making only a preferred pattern, and it is to be understood that it is merely illustrative of the method and of the apparatus and that it is not to be considered as a limitation of the invention expressed in the appended claims.

In the drawings:

Fig. 1 represents in profile on line 1—1 of Fig. 2 the :

layer 18 is carried away on conveyer 21 moving at said fixed rate, and the resulting, lower layer drops to conveyer 22 moving at said rate. The cut layers 18 and 19 are shown in dotted lines merely to indicate the thickness thereof rather than the structure.

In Fig. 2, the rollers 15 and 16 are shown in their relation to each other. Although the rollers may vary in peripheral contour and spacing on each shaft and in location with reference to the rollers on the other shaft, they are shown as all having flat peripheries, all having the same thickness, all spaced apart on each shaft by an amount at least equal to the thickness, and with each roller on one shaft unopposed by a roller on the other shaft.

As a specific illustration, the rollers may be spaced on 3-inch centers, have diameters of about 4 inches and a flat periphery of 1¼ inches width. The shafts 12 and 13 may be vertically adjustable by means not shown, to vary the desired result, and particularly to accommodate foam sheets 10 of varying thickness. In use on a foam of 2.75 inches thickness, the peripheries of the rollers may be separated 0.39 inch. For a foam of 4.75 inches thickness, the peripheries of the rollers may be separated 0.45 inch.

Consider the rollers as so far described, but not as illustrated, that is, disregarding the crossbars 25 and the recesses 26 seen in Figs. 1 and 2, or in other words, consider the effect of the arc portions C. Such apparatus operates as follows:

Each face of the foam 10 is compressed toward but not to the knife 14 by forces applied at spaced locations over the cutting line by the rollers 15 and 16 and the

2,902,091 force at each location on each face is unopposed by a force at the other face. The straight line on which the compressed foam is cut will, upon expansion of the foam, result in a cross-section of corrugation. The layers 18 and 19 will· each have identical· and complementary 5 corrugations of hills and valleys running parallel to the direction of movement and the hilltops of the corrugations: will be in a plane in each layer parallel to the retained face of foam 10.

Fig. 3 in its cross-section illustrates the two comple- 10 mentary layers as. they are merely separated, the crosshatched portion indicating the contour formed when the foam 10 is compressed by the arcuate portions C of the rollers as seen in Fig. 1. In Fig. 3, the lines 10^aare the boundaries of the cut faces, which are cut as a 15 straight line parallel to the approaching uncompressed faces of foam 10. At the lines of. arrows 15^a, the foam 10 was compressed by rollers 15. At the lines of the arrows 16^a, the foam was compressed by the rollers 16. The width of the rollers may be varied, 20 according to the conditions of original foam thickness and extent of compression so that the tops of the hills may be flat or rounded as desired. A slight narrow band of flatness is shown at the tops of the hills 18' and 19'.

The continuity of the corrugations illustrated in cross- 25 section in Fig. 3 may be broken at spaced intervals along the direction of the moving web, at which intervals the pattern of compression locations is changed. One way to do this is to provide one or more of crossbars 25, each across a space between adjacent rollers 15 or 16. ³⁰Another way is to provide recesses 26 in one or more peripheries of the rollers. As shown, there is a pattern of locating crossbars 25 and a pattern of locating recesses 26, and the pattern is preferably the same for each set of rollers, as illustrated. ³ⁱ&gt;

Each intermediate roller 15 and 16 carries two crossbars inlaid into the peripheries, of which one crosses one adjacent ispace to the next roller and the other crosses the other adjacent space to the next roller. These crossbars on each roller are diametrically located, so 40 that in Fig. 1 the arrangement presents a zig-zag line for the rollers 15. The rollers 16 have the same arrangement but the location on the peripheries is advanced 90° in the peripheral direction. When one disregards the presence of the recesses 26, and considers the rollers 45 with the crossbars, the operation above described is so changed that each portion of a crossbar located over a space between its carrying rollers compresses the form 10 against the periphery of a roller on the opposite shaft. Thus, at this location, a foam is compressed from 50 both faces equally, and the line of cut is centered between the faces of foam 10.

The recesses 26 are located so that they lie opposite each crossbar in the rotation of the two shafts, and the depth and width of the recess controls the extent to 55 which the compression by the crossbar is opposed. When the recess is so large that there is no opposing force, then the compression effect is the same as takes place at a portion G of a roller, and the cut will be centered at the same level as the tops of hills 18' and 19' of the 60 corrugations. These two conditions of no recess at all, and of a non-compressihg recess 26, establish limits, respectively, locating the cut centrally of the thickness of foam 10, Or at a level with the tops of the hills 18' and 19' of the corrugations formed by the arcuate por- 05 tions C of the rollers.

The illustrated recesses 26 are niches in the peripheries and as a mechanical convenience are of the same size as the cross-section of the crossbars 26, so that various patterns of crossbars and niches are available 70 by use of the same rollers. The crossbars 25 and recesses 26 predetermine hills and valleys crossing the principal corrugations formed by the roller portions G, i.e., the cross-hatched areas of Fig, 3.

Fig. 4 shows the complementary lower section 19 and 75 upper section 18 as viewed on line 4—4 of Fig. 3. The hills 18' and 19' shown in Fig. 3 are indicated respectively in cross-section and in elevation and numeral 30 designates the slopes of the hills 19'. The cross-hatched area in Fig. 4 shows the hills and valleys resulting from the cooperative action of the crossbars 25 and the recesses 26. Hills 31 are formed with tops below the level of the tops of hills 19'. Since the upper section 18 has hills and valleys the same as the lower section 19, the contour of the hills 19' and their valleys as seen in elevation in Fig. 4 matches the contour of the cross-sectioned area in Fig. 4. In consequence, the ridges, of hills 19', as corrugations, are not continuous but are broken by valleys 31' corresponding to hills 31 in the opposite section. The valley between hills 31 meas- _f. ured from hilltop to hilltop corresponds to one revolution of the rollers. Midway between the hilltops 31 '' (Fig. 4) there is a much lower hill 32 corresponding to _z a depression 32' centered in the top of the ridge of A hill 19'. Between each hill 31 and the next lower hill 32 there is a minor rise 33 which has a matching dip 33' in the said ridge of hill 19 between valley 31' and depression 32'. Said hill 32 is the inherent result of hills 31 being lower than hills 19. The rise 33 and dip 33' are incidental results of the distribution of compressive forces within the foam sheet 10. while being split.

The effect of the rollers as described above may be better understood from Fig. 5, which shows the two sets of rollers 15 and 16 rectified to identical plane patterns of the areas over which compression forces are applied. The identical patterns are applied out of phase, with one 90° behind the other.

The first pattern shows the areas 15 as the peripheries of the rollers 15 rectified to a series of parallel bands spaced apart by a distance at least equal to the band width. The length of the band is the unit length of the pattern. Some crossbars 25 form letters H with each adjacent pair of adjacent bands as legs of the H. The remaining crossbars 25 connect the adjacent letters H at their tops.

The second pattern is identical with the first, and as shown in Fig. 5 is positioned one-quarter of the unit length behind it. The bands 16 are the peripheries of the lower rollers 16, and similar crossbars 25 complete the pattern.

The dotted areas 26 on all the bands are the locations for the recesses 26, which register opposite a crossbar 25. As stated above each region 26 may vary in depth upwardly from zero. When it is zero in depth, the foam sheet is equally compressed at both faces at the cutting line by a crossbar and by an opposite roller, and hence the cut lies in the median plane of the uncompressed sheet. Such regions 26 of zero depth are the only places in the pattern which effect equal compression at both faces. When the regions 26 are as deep as shown the compression is greater on the face with the crossbar leading to the valleys 33' (Fig. 4) and the hills 33. When the recesses 26 are so deep as to provide no compression from their bottoms, the valleys 33' and hills 33 disappear. When the recesses 26 have zero depth, the valleys 33' bottom at the median plane, and the hills 33 , ~ top at the median plane. On every band in the pattern there may be counted the differing areas of compression on the foam sheet. When the recess 26 has depth, these areas are eight in number, and in Fig. 4, in section 19, there are eight corresponding areas from hill 31 at the left to hill 31 at the right.

The contoured layers which may be formed by the present invention have many uses. The preferred and illustrated forms are especially suitable for assembling the two layers so that the hills 19' of one layer oppose the corresponding hills of the other layer. These hilltops, being each in a plane, may be adhesively united or otherwise connected by interposed material, such as,

2,902,091 the rollers, the bridges on each intermediate roller being 180° apart.

8. Apparatus comprising a length of cutting blade arranged to cut on a straight cutting line, means to feed a uniformly thick sheet of resilient foam having two parallel faces onto said blade with said blade midway between the two faces of the approaching sheet, two shafts parallel to the cuttting line and in the plane thereof, which plane is perpendicular to the direction 10 of movement of the sheet, said shafts being arranged to rotate at the same speeed in opposite directions, said shafts being equidistant from' the nearest face of the moving sheet, a plurality of like rollers on each shaft equally spaced apart by a distance at least as great as the 15 width of the rollers, each roller on each shaft being unopposed by a roller on the opposite shaft, the faces of each roller being spaced from the cutting line a distance less than half the thickness of the sheet, and each shaft having adjacent rollers connected by one bridge with 20 an outer surface substantially coextensive with the peripheries of the rollers, the bridges on each intermediate roller being 180° apart, and each roller having a recess in its perpihery positioned to register in opposition to a bridge in rotation of the two shafts.

9. Apparatus comprising a length of cutting blade arranged to cut on a straight cutting line, means to feed a uniformly thick sheet· of resilient foam having two parallel faces onto:said:blade with said blade midway between the two faces of the approaching sheet, two shafts parallel to the cutting line and in the plane thereof, which plane is perpendicular to the direction of movement of the sheet, said shafts being arranged to rotate at the same speed in opposite directions, said shafts being equidistant from the nearest face of the moving sheet, a plurality of like rollers on each shaft equally spaced apart by a distance at least as great as the width of the rollers, each roller on each shaft being unopposed by a roller on the opposite shaft, the faces of each roller being spaced from the cutting line a distance less than half the thickness of the sheet, and each shaft having adjacent rollers connected by bridging means with outer surface substantially coextensive with the peripheries of the rollers, each roller having its bridging means equally spaced about its periphery. .

10. Apparatus comprising a length of cutting blade arranged to cut on a straight cutting line, means to feed a uniformly thick sheet of resilient foam having two parallel faces onto said blade with said blade midway between the two faces of the approaching sheet, two shafts 60 parallel to the cutting line and in the plane thereof, which plane is perpendicular to the direction of movement of the sheet, said shafts being. arranged to rotate at the same speed in opposite directions, said shafts being equidistant from the nearest face of the moving sheet, a plu55 rality of like rollers on each shaft equally spaced apart by a distance at least as great as the width of the rollers, each roller on each shaft being unopposed by a roller on the opposite shaft, the faces of each roller being spaced from the cutting line a distance less than half the 60 thickness of the sheet, and each shaft having adjacent rollers connected by bridging means with outer surface substantially coextensive with the peripheries of the rollers, each roller having its bridging means equally spaced about its periphery and each roller having a recess,in.its 65 periphery positioned to register in opposition to bridging means in rotation of the two shafts.

11. The method which comprises continuously moving in one direction a sheet of resilient foam material normally characterized by two parallel faces defining the 70 thickness^ locating a moving slitting blade substantially midway between the normal location of said faces of said sheet at a fixed straight cutting line parallel to said faces and at right angles to said direction of movement, displacing alternate portions of each face of the sheet toward 75 said cutting line first at one side and then at the other sheets of fabric of of foam, to provide a cored cushion of suitable foamed material, such as polyurethane, as described and claimed in my copending application Serial No. 591,636, filed June 15, 1956, now Patent No, 2,836,238 issued May 27, 1958.

The present application is directed to the method and apparatus for forming contoured faces on resilient foam.