Core for aluminum sheet

Abstract

A core for winding metal sheet thereon to provide the sheet metal free of lap marks upon unwinding, the core having a generally cylindrical configuration and having an outside surface, said outside surface having a wedge-shaped notch formed generally transverse to winding direction of the core, the notch having a stepped end and a tapered end disposed opposite the stepped end, the stepped end extending from the surface to a bottom, the stepped end having a tapered end extending from the bottom of stepped end to the outside surface of said core to provide a transition zone.

Description

BACKGROUND OF THE INVENTION

This invention relates to aluminum sheet material and a new method and apparatus for winding sheet material such as metal sheet material to provide a product free of defects, lap marks or arbor breaks upon unwinding of the sheet material.

When aluminum sheet material is wound on a core, defects occur where the second winding crosses over or laps the beginning edge of the sheet. This edge is usually sharp and as the lap material is forced down on it by the additional winding, defects occur and can extend through many windings or layers of metal, resulting in substantial amounts of sheet being scrapped. The defects are referred to by different names in the industry, such as arbor breaks, lap marks and cross breaks.

Many attempts have been made to solve the problem of winding sheet on a core. For example, U.S. Pat. No. 5,816,525 discloses winding core (10) for the winding of a web of pressure-sensitive material, which has a bituminous covering (23) which affords a supporting pressure for at least the central portion of the web which is uniform over the circumference of the core.

U.S. Pat. No. 5,441,212 discloses a device and method for eliminating the problem of head or lead end creasing in coiled materials. The method comprises fitting a coiling mandrel with a mandrel sleeve adaptor that includes a narrow soft zone which is more compressible than the remainder of the outer surface of the adaptor. When the adaptor is incorporated into a coiling apparatus that includes sensors for sensing the rotational position of the soft zone, and the head end of the material to be coiled, the head end of the material to be coiled can be accurately nested in the narrow soft zone during coiling to eliminate the problem of creasing.

U.S. Pat. No. 3,390,762 discloses a roll of thermoplastic sheeting comprising in combination a core, a web of thermoplastic sheeting wound thereon and a resilient foam plastic insert between the leading end of the web and the second circumvolution thereof whereby damage of said second and successive circumvolutions of the web by said leading edge is prevented.

U.S. Pat. No. 3,318,549 discloses a web attachment means for spools including a spool, adapted for use as a take-up device for a web comprising an outer substantially cylindrical surface around a longitudinal axis with at least one longitudinal slot in the surface comprising a pair of facing walls disposed inwardly from the surface, at least one substantially sharp bearing edge formed at the corner of the first of the walls and the surface of the cylinder, at least one other substantially sharp bearing edge formed on the second of he walls substantially parallel to the first mentioned bearing edge and at a smaller radius from the axis than the first mentioned bearing edge, the second mentioned bearing edge being displaced from a plane which includes the first mentioned bearing edge and the axis of the spool, and bearing means contiguous with the first wall substantially in a plane at an obtuse angle to the plane of the first wall and cutting through the plane in which the first mentioned edge and the axis lie.

U.S. Pat. No. 3,313,497 discloses a core for pliable strip material including a hollow cylindrical core for thick pliable adhesive strips having a radially depressible tab formed by cuts through the thickness thereof, two of the cuts being substantially parallel to the ends of the core, the two cuts being interconnected by a third transverse cut, the tab within the area defined by the cuts being radially depressed to form an indentation adapted to receive the end of an adhesive strip wrapped around the core.

U.S. Pat. No. 2,714,493 discloses a core for sheet material comprising a tubular non-metallic core and sheet material wound thereon, the core carrying an externally-positioned flap skived partly into the core and lying closely contiguous to the wall of the core, the flap tapering outwardly to a feathered edge substantially tangential to the surface of the core and forming a continuation of the core periphery, the inner end of the sheet material being held between said skived flap and the core wall adjacent thereto, whereby the sheet material wound on said core presents no lap marks in the initial layers of wound material.

U.S. Pat. No. 2,074,968 discloses a reel comprising a cylindrical body portion having a longitudinal slot therein, one of the side walls of the slot having recesses at both of its ends, each of the recesses extending away from the side wall and outwardly to the periphery of the cylindrical body portion, whereby the manual insertion of the material to be reeled into the slot may be facilitated.

U.S. Pat. No. 1,475,622 discloses a cloth roll for looms having a cylindrical periphery provided with a groove extending longitudinally thereof throughout the cloth-engaging portion and with sharply defined meeting edges between the groove and the roll periphery whereby, after the cloth has been wrapped around the roll and two or more times over the groove, the cloth is held against slipping during the further winding of the cloth on the roll.

In spite of these disclosures, there is still a great need for a core which prevents lap marks on additional winding of a web such as aluminum sheet.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an improved method for winding sheet metal on a core.

It is another object of the invention to provide a method which permits sheet material to be wound on a core free of arbor or lap marks.

Yet, it is another object of the invention to provide an improved core for winding metal sheet.

And yet, it is a further object of the invention to provide an improved core having a controlled wedge shaped on the outer surface to permit winding of sheet material thereon without forming cross breaks, lap marks or arbor deformities.

These and other objects will become apparent from a reading of the specification and claims and examination of the Figures appended hereto.

In accordance with these objects, there is provided a method of winding a metal sheet on a core to avoid formation of arbor deformities or lap marks. The method comprises providing a source of metal sheet to be wound on a core and providing a core on which the metal sheet is to be wound, the core having a generally cylindrical outside surface having a circumference. The outside surface has a notch formed generally transverse to the winding direction of the core, the notch having a stepped end and a tapered end disposed generally opposite the stepped end, the stepped end having a depth substantially equal to the thickness of the sheet to provide a bottom thereon. The stepped end is suited to having an end of the sheet abutted thereagainst. The tapered end extends from about the bottom of the notch to the outside surface of the core to provide a transition zone. An end of sheet is abutted against the stepped end of the core and then the sheet is wound on the core. The sheet is free of arbor deformities of lap marks after being unwound from the core.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the core of the invention.

FIG. 2 is an end view of the core of the invention.

FIG. 3 is another perspective view of the core of the invention.

FIG. 4 is an end view illustrating sheet material wrapped around the core in accordance with the invention.

FIG. 5 is an illustration of the problem of winding sheet without the benefit of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to the Figures, there is illustrated in FIG. 5 the problems of winding aluminum sheet, for example, on a conventional cylindrical core. In FIG. 5, there is shown a core 2. On core 2 is wrapped or wound metal sheet such as aluminum sheet 4. Sheet 4 has a beginning end 6 in contact with surface 8 of core 2. It will be seen that as sheet material 4 completes the first wrap or winding on core 2, it encounters end 6 of sheet 4, which acts as ridge or high spot 10 transverse to the winding direction. This ridge results in a lap mark as the end projects into the sheet material upon the sheet metal making the second layer. The effect of ridge or high spot 10 can extend outwardly for many layers and, in many instances, result in the metal having to be scrapped, greatly interfering with the economics of the system. Thus, it can be seen that there is a great need for a system which avoids lap marks. Applicants' invention provides such a system.

Referring now to FIG. 1, there is shown an improved core on which sheet material can be wrapped without formation of lap marks or cross breaks. Improved core 12 is shown comprised of wall 14 formed in the shape of a cylinder. That is, wall 14 has a generally circular configuration. It will be seen that inside wall 16 in the embodiment shown is generally circular. Core 12 has an outside wall or surface 18, which is generally circular. However, in accordance with the invention, core 12 has a wedge-shaped notch 20 machined into outside surface 18 of wall 14. The extent of wedge-shaped notch 20 is illustrated by the cross hatching. It will be noted that the wedge-shaped notch starts at wall 22 and is tapered smoothly until it reaches surface 18 at point 24. This embodiment can be seen also in FIGS. 2 and 3. That is, the wedge-shaped notch is comprised of walls 26 and 28, which extend fully across the extent of the core, as shown in FIG. 3. It will be noted that wall 26 is formed to extend radially and has a top 30 that coincides with surface 18. Also, wall 26 has a bottom 32 that coincides with wall 28. Preferably, wall 26 of notch 20 has a depth generally equal to the thickness of the sheet being wound on the core. For example, if the sheet is 0.125 inch, then wall 26 should extend into the core approximately 0.125 inch. However, it is within the scope of the invention to use a single wall depth for several different sheet thicknesses. That is, if the notch depth is 0.125 inch, sheet thicker or thinner than 0.125 inch may be used. In such instance, the notch can have the effect of minimizing the lap problems. As noted, wall 28 is tapered outwardly from bottom 32 until it reaches surface 18. Wall 28 should have a length from bottom 32 to surface 18, which provides for a smooth transition between bottom 32 and surface 18. Generally, deeper end walls 26 require longer transition walls 28 to avoid lap marks as the metal is wound on the core. Typically transition wall 28 comprises 5 to 50% of the circumference of wall 18, with a preferred amount being 10 to 25%. It will be seen that longer transition walls 28 are favored in order to avoid lap marks. It will be noted that the radius of the curve depends on the extent or length of transition zone 28. Short transition zones require smaller radii.

It should be noted that the preferred wedge-shaped notch has a transition wall or surface 28 which is curved to provide for lap mark-free winding of metal sheet material.

Referring now to FIG. 4, there is illustrated sheet metal wound on a core of the invention. It will be noted that there are no ridges to create arbor deformities, or lap marks. Thus, in FIG. 4, it will be seen that core 12 is provided with a wedge-shaped notch and that end 40 of sheet material 42 is abutted tightly against notch wall 26. Further, it should be noted that preferably the depth of wall 26 is substantially the same as the thickness of sheet material 42. Thus, the windings of sheet material on the improved core do not experience any sharp edges, and upon unwinding, such sheet material is free of arbor deformities or lap marks, greatly minimizing scrap generation and improving economics of the system.

The improved core can be fabricated from any suitable material, and the configuration can be either cylindrical as shown or solid. The preferred core is fabricated from heavy paper which is wraps of paper and adhesive formed into cylinder, e.g., wall thickness 0.375 inch, and such material is available from Sonoco Products, 3996 US Hwy. 60 East, Morganfield, Ky. 42437-9551, under the name Fibercore. The improved core can be fabricated from the fiber material by applying a groove or cut transverse to the direction of winding. Then, a curved wedge shape is machined from the groove to the face of the core to provide a smooth transition area. For a core having 20 inch diameter, a 12″ transition zone is considered to be satisfactory, although longer or shorter transition zones may be used. Such core, even when notched and machined, has a crush strength in the range of 15 to 25 psi. It will be appreciated that core can be fabricated from a plastic material by injection molding, or a fiberglass reinforced material may be used for higher strengths.

Use of the improved core design eliminates quality problems arising from arbor deformation or lap marks.

The improved core is particularly useful for sheet metal such as aluminum sheet metal having thicknesses that range from 0.08 to 0.2 inch.

Having described the presently preferred embodiments, it is to be understood that the invention may be otherwise embodied within the scope of the appended claims.

Claims

1. A method of winding a metal sheet on a core to avoid formation of arbor deformities or lap marks, comprising the steps of: (a) providing a source of metal sheet to be wound on a core; (b) providing a core on which the metal sheet is to be wound, said core being generally cylindrical and having a circumference and an outside surface, said outside surface having: a notch formed generally transverse to winding direction of said core, said notch having a stepped end and a tapered end disposed generally opposite said stepped end, said stepped end suited to having an end of said sheet abutted thereagainst, the tapered end extending from the bottom of said notch to said outside surface of said core to provide a transition zone; (c) abutting an end of said sheet against the stepped end of said core; and (d) winding said sheet on said core, said sheet being free of arbor deformities or lap marks after being wound on said core.

2. The method in accordance with claim 1 wherein said metal sheet is aluminum metal sheet having a thickness in the range of 0.08 to 0.2 inch.

3. The method in accordance with claim 1 wherein said core is comprised of heavy paper or a plastic material.

4. The method in accordance with claim 1 wherein said transition zone comprises 5 to 50% of the circumference of said core.

5. The method in accordance with claim 1 wherein said transition zone comprises 10 to 25% of the circumference of said core.

6. The method in accordance with claim 1 wherein said core has a crush strength of 15 to 25 psi.

7. The method in accordance with claim 1 wherein said stepped end has a depth in the range of 0.08 to 0.2 inch.

8. The method in accordance with claim 1 wherein said stepped end has a depth substantially equal to the thickness of sheet.

9. A method of winding an aluminum metal sheet on a core to avoid formation of arbor deformities or lap marks, comprising the steps of: (a) providing a source of metal sheet to be wound on a core; (b) providing a core on which the metal sheet is to be wound, said core being generally cylindrical and having a circumference and an outside surface, said outside surface having: a notch formed generally transverse to winding direction of said core, said notch having a stepped end and a tapered end disposed generally opposite said stepped end, said stepped end having a depth in the range of 0.08 to 0.2 inch to provide a bottom, said stepped end suited to having an end of said sheet abutted thereagainst, the tapered end extending from the bottom of said notch to said outside surface of said core to provide a transition zone having a length of 5 to 50% of said circumference, said core having crush strength of 15 to 25 psi; (c) abutting an end of said sheet against the stepped end of said core; and (d) winding said sheet on said core, said sheet being free of arbor deformities or lap marks after being wound on said core.

10. A core for winding metal sheet thereon to provide the sheet metal free of lap marks upon unwinding, the core having a generally cylindrical configuration and having an outside surface, said outside surface having a wedge-shaped notch formed generally transverse to winding direction of the core, the notch having a stepped end and a tapered end disposed opposite the stepped end, the stepped end extending from the surface to a bottom, the stepped end having a tapered end extending from the bottom of stepped end to the outside surface of said core to provide a transition zone.

11. The core in accordance with claim 10 wherein said core is comprised of heavy paper.

12. The core in accordance with claim 10 wherein said transition zone comprises 5 to 50% of the circumference of said core.

13. The core in accordance with claim 10 wherein said transition zone comprises 10 to 25% of the circumference of said core.

14. The core in accordance with claim 10 wherein said core has a crush strength of 15 to 25 psi.

15. The core in accordance with claim 10 wherein said stepped end has a depth in the range of 0.08 to 0.2 inch.

16. The core in accordance with claim 10 wherein said transition zone is curved in the direction of winding.

17. The core in accordance with claim 10 wherein said stepped end has a depth substantially equal to the thickness of said sheet.