Expander roller for fold-free expansion of foils

Abstract

An expander roller for a fold-free expansion of foils, webs, and sheet materials in a width dimension. The expander roller has a central metal axle mounted in a surrounding synthetic tube with placed on its circumference a grid of implanted brush plugs in an axial direction under an angle alpha and with a mutual distancing and in tangential direction under a center angle beta and with a mutual distance. The roller provides a perfect expanding or stretching of thin widths of different materials.

Claims

1. An expander roller for fold-free expansion of foils comprises: a roller tube with a length L, a radius r, and an axle having ends placed in a support structure for free rotation; a plurality of brush plugs implanted in a grid array in a circumferential surface of the roller tube and having a common free length t, wherein: the brush plugs each form an angle alpha (α) with respect to a radial plane oriented transversely to the outer circumferential surface and a longitudinal axis of the roller tube; the brush plugs are each inclined in the tangential direction and form an angle partly beta (β=α/p) with a normal axial plane, where angle beta (β) is a centre angle; the brush plugs in each of a plurality of axially extending rows have a mutual centre-to-centre distance X; the brush plugs have a mutual separation distance in the tangential direction determined by the centre angle beta (β) and the radius r of the expander roller; and the brush plugs of every other axially extending row are axially shifted by a distance ½X relative to the brush plugs in the other axially extending rows.

2. Expander roller as in claim 1, wherein said roller tube is made of a synthetic material and surround said axle.

3. Expander roller as in claim 1, wherein the expander roller including the brush plugs has an outer radius R between 50 mm and 500 mm, wherein radius r is between 25 mm and 400 mm and length L is between 1000 and 5000 mm.

4. Expander roller as in claim 1, wherein said angle alpha (α) is between 7 degrees and 25 degrees and said partly angle beta β(β=α/p) is between 0.2 alpha and 0.5 alpha.

5. Expander roller as in claim 1, wherein said distance X is between 5 mm and 15 mm.

6. Expander roller as in claim 1, wherein said length t of the obliquely implanted brush plugs is between 5 mm and 25 mm.

7. Expander roller as in claim 6, wherein the material of the obliquely bended brush roller is polypropylene, and wherein the brush plugs have threads, fibers, or bristles with a diameter is between 0.1 mm and 0.8 mm.

8. Expander roller as in claim 1, wherein the bending strength of the brush plugs from the center of the expander roller up towards the end varies.

9. Expander roller as in claim 1, wherein said brush plugs are obliquely cut off in the axial direction of the expander roller.

10. Expander roller as in claim 1 wherein the brush plugs along along each half end portion of the circumferential surface roller are inclined from the centre towards the respective roller end at the angle α.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) A preferred embodiment of the present invention will now be described with reference to the accompanying drawing, in which:

(2) FIG. 1 shows an axial section of the expander roller according to the invention;

(3) FIG. 2 shows a partial side view with only three rows represented with brush plugs according to the invention;

(4) FIG. 3 shows a cross-section taken along line III-III in FIG. 2; and

(5) FIG. 4 shows a top view taken along line IV in FIG. 2 to show the grid of the brush plugs.

DETAILED DESCRIPTION

(6) FIG. 1 represents an axial section of the expander roller 1 according to the invention. The expander roller 1 has a central axle 2, with ends 3 placed in a support structure (20) for free rotation. A tube structure 4 of a mostly synthetic material, such as polypropylene, is mounted around the central axle 2. Tube structure 4 can be made as a tube or in cylindrical parts. Brush parts or plugs 5 are implanted in bore holes in the circumference of tube structure 4 with special machines. As can been seen in FIG. 2, along a left half length L/2 of the axle 2 the brush parts 5 are placed under an angle alpha (α) inclined towards the left and along a right half length L/2 of the axle 2 the brush parts 5 are inclined by angle alpha (α) to the right for implementing the expanding or stretching procedure. The angle alpha (α) is between 7 degrees and 25 degrees, preferably 12 degrees. The distance X is between 5 mm and 15 mm, preferably 10 mm. The distance βr is due to the radius r and angle beta (β). For different applications of expanding or spreading foils, widths of different materials, the measurements X and βr can be adapted to an optimum for special use. In addition, the bending strength of the brush parts or plugs 5 may vary from the center towards the end of the expander roller 1 and more particularly may increase from the center towards the end for special applications.

(7) FIG. 2 represents a partial side view with only three rows with brush plugs 5. For identical parts identical numbers are used.

(8) FIG. 3 represents a cross-section taken along the line III-III in FIG. 2. In the cross-section the foil 6 or other thin material to expand or stretch is forced around a segmental part of the expander roller 1. Some of the brush plugs 5 are deformed for the expanding or stretching operation. The total radius R is diminished to R-AR. The free length t of the brush plugs 5 is between 5 mm and 25 mm, preferably 12 mm. The brush plugs 5 have threads, fibers or bristles with a diameter between 0.1 mm and 0.8 mm, preferably 0.25 mm.

(9) FIG. 4 represents a top view over the line IV of FIG. 2 to show the grid op the brush plugs. Identical parts are indicated with identical numbers. Finally is has to be emphasized, that a preferred embodiment of the invention is described an that it is self-evident that further modifications are possible without leaving the scope of this invention.