US 1943215 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Jan. 9, 1934. c. K. DUNLAP 1,943,215
TEXTILE ROLL AND METHOD OF MAKING THE SAME Filed Oct. 13, 1952 Patented Jan. 9, 1934 UNITE STATES ATE-NT OFFICE TEXTILE ROLL AND METHOD OF MAKING THE SAME Application October 13, 1932. Serial No. 637,638
The present invention relates to built-up tubes and to methods of forming the same.
In Patent No. 1,730,357, issued October 8, 1929, to W. A. Carpenter, there is disclosed a tube primarily intended for use as a covering for textile rolls together with a method of forming the same, such tube being formed in two layers, an outer layer of artificial cork or the like and an inner layer of fabric or any other material well adapted to serve as a core or strengthening layer for the outer covering. Such tube or roll covering is formed preferably by helically winding an elongated strip of artificial cork upon the inner strengthening core or tube, the inner surface of the cork being secured to the core by a suitable adhesive. The present invention contemplates particularly an improvement in the method of forming tubes of the type disclosed in the Carpenter patent referred, to and an improved tube of this type resulting from the improved method of manufacture.
One object of the invention is to provide a method of fabrication which results in closer contact of the helical surfaces of the meeting edges of adjacent windings of the cork layer, thus providing a tube or cot which presents a solid cylindrical surface having no gaps or cracks between the edges of adjacent windings.
As is well-known, artificial cork is, when properly made, well adapted to be bent without breaking and may even be wound around a cylindrical mandrel of relatively small diameter without appreciable cracking of its outer surface. This results from its capacity to elongate under tension to a considerable degree without breaking. Elongation of a strip of cork, of course, will result in a certain reduction of cross-sectional area, the strip becoming attenuated when tensioned. In winding a strip of cork about a mandrel of relatively small radius, the outer layer of cork is placed under a considerably greater tension than is the inner layer, the inner layer as a matter of fact being subjected to little or no tension or even, in some cases, to a slight compression. It may be said, therefore, that the winding operation involves placing the outer areas of the crosssection in tension, the degree of tension lessening as the inner face of the cork strip is approached. Naturally, therefore, the outer layers of cork are reduced in cross-section as a result of the bending operation while the innermost layers are not, it being appreciated, of course, that the layers referred to are theoretical and not actual, a solid strip of artificial cork only being under discussion.
As a. result of the tensioning of the outer layers during winding, unaccompanied by tensioning of the inner layers of the strip of cork, a cork strip which originally was, in all cross-sections, a parallelogram becomes, after the winding W operation, trapezoidal in all cross-sections, the outermost face being narrowed slightly while the innermost face remains the same, the formerly parallel edge surfaces being inclined to each other. As a result, the completed tube is imperfeet, the mutually facing edge surfaces of adjacent windings not being truly contiguous but a V-shaped groove being left between these surfaces which is wider at the cylindrical outer surface of the completed tube than at the core there- Y0 of. These cracks or helical grooves are objectionable, particularly where the completed article is to be used as a textile roll covering, and the presentinvention provides an improved process for the elimination of these winding cracks 7 or gaps.
Thus, I provide a cork strip which is, in the first instance and prior to the winding operation, so cut as to be trapezoidal in all cross-sections. The operation of helically winding the strip so formed upon a. mandrel results in the narrowing of the wider face of the trapezoid, which face is always outermost during the winding operation and in the completed tube, so that, as a result of this narrowing, it is exactly coextensive in width with the inner face. As a result, the helical edge surfaces of adjacent windings are contiguous throughout and gaps or cracks between these windings eliminated.
In the accompanying drawing: to
Figure 1 is illustrative, rather diagrammatically, of a forming mandrel for tubes, showing a backing strip and an artificial cork facing partially wound thereon;
Figure 2 is a transverse section through the strip of artificial cork shown in Figure 1 prior to winding;
Figure 3 is a transverse section through the same strip subsequent to winding;
Figure 4 is a transverse section through an all00 ternative form of cork strip prior to the winding operation;
Figure 5 is a transverse section through the same after having been wound upon the mandrel;
Figure 6 is an axial section through a cork cov- 05 ering for a textile roll and wound in the improved manner; and
Figure 7 is a perspective view of the same.
The strip, indicated at 10 in Figure 1, is the backing strip which forms a reinforcement for the completed tube and which is first helically wound upon the mandrel. It is generally a comparatively thin strip of material, for instance, fabric, and it is usually necessary to take no precautions to secure exact and precise meeting of its edge surfaces as is necessary in the case of the outer covering. It will be appreciated that the inner strip is a strengthening strip and does not contact with the thread in a drawing operation, and hence slight gaps between the edges of adiacent windings are not injurious. Furthermore, as has already been pointed out, it is usually quite thin. The outer layer, however, is the external layer, and its outer surface should not only be truly cylindrical but should be free of surface imperfections so far as possible. The strip 11 which goes to make up this outer layer is preferably of artificial cork, which is resilient, the layer having suflicient thickness to provide the necessary resiliency.
Prior to the winding operation the artificial cork strip, which is indicated at 11, has its edges beveled as shown in Figure 2 to a rather exaggerated degree so that it is in the form of a trapezoid. It is then wound helically upon the core already formed by the strip 10, the wider surface of the strip being outermost asit is wound upon the mandrel. The outer layers of strip 11 are, as has been previously explained, placed under considerably'greater tension than the inner layers and, as a result of this tensioning, are attenuated while the inner layers are not. If the strip is properly cut in the first instance, its outer surface will, after the winding operation, be exactly the same in width as the inner surface, and likewise all intermediate layers will have this identical width so that a cross-section through the strip after the winding operation will be in the form of a parallelogram, such as indicated in Figure 3. The edge surfaces of one winding, therefore, will be contiguous with the edge surfaces of adjacent windings, and there will be no gaps or cracks left between the windings as heretofore. The inner and outer windings are secured together by an adhesive, and the completed tube is thereafter cut into suitable lengths, the surface being ground if necessary to provide coverings having smooth surfaces and of identical thicknesses.
The extent to which the edges of the strip should be relatively inclined prior to the winding operation will depend upon several factors. Obviously it is important to consider the diameter of the mandrel about which the strip is to be wound. The outer layer of an artificial cork strip wound about a mandrel of small diameter will, of course, be tensioned considerably more than the outer layer of a strip of the same thickness wound about a mandrel of larger diameter. Likewise the thickness of the cork strip must be taken into consideration as greater tension will exist in the outer layer of a. relatively thick strip than will exist in the outer layer of a relatively thin strip after winding both strips upon a. mandrel of a given diameter. Finally, consideration must be given to the character of the cork or other material itself. Artificial cork particularly, as is well-known, varies in its capaclty to stretch and laterally deform due to stretching by reason of variations in the nature of the binder which is used to cause the various particles of cork to adhere and also by reason of variations in the pressures to which the cork particles and binder are subjected in the manufacture of the same.
It is not possible, therefore, to set down any definite rule for establishing the proper an ularity between the edge surfaces to secure e desired result. It is found in actual operati n, however, that it is a simple matter to establi by actual test, the exact angle which the edge surfaces of the strip should make with each other prior to winding in order to obtain the desired result.
It is, of course, apparent that the edge surfaces of the original strip need not be approximately normal to the inner and outer surfaces as shown in Figure 2. These edges may both be inclined as shown in Figure 4, the sole consideration being the relative inclination of the edge surfaces to the proper extent so that the strip after winding will be in the form of a parallelogram in all cross-sections as shown in Figure 5. The invention contemplates particularly the use of artificial cork to form the outer or surface layer of the completed roll covering. It is not limited, however, to the use of an artificial cork strip and contemplates the use of any material which is well adapted for the purpose.
Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:
1. The method of fabricating tubes, cots, or the like which comprises forming an elongated strip of material having the capacity to stretch under tension, all cross-sections through said strip being trapezoidal and of equal area, and thereafter Winding the same helically upon a cylindrical mandrel, the wider of the parallel faces being outermost, the bending incident to the winding operation deforming the strip transversely and causing all cross-sections thereof to become parallelograms, whereby the helical faces of the meeting edges of adjacent windings will closely engage.
2. The method of fabricating tubes, cots, or the like which comprises forming an elongated strip of artificial cork, all cross-sections through said strip being trapezoidal and of equal area, and thereafter winding the same helically upon a cylindrical mandrel, the wider of the parallel faces being outermost, the bending incident to the winding operation deforming the strip transversely and causing all cross-sections thereof to become parallelograms, whereby the helical faces of meeting edges of adjacent windings will closely engage.
CHARLES K. DUNLAP.