Fiber reinforced hybrid composite winding core

Abstract

A hybrid fiber reinforced polymer winding core consisting of several layers of different materials. The winding core layers are constructed so that structural reinforcing layers are sandwiched between outer protective layers. The outermost protective layer and innermost protective layer define the outer wall surface and inner wall surface of the winding core.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] Applicant claims the priority benefits of U.S. Provisional Patent Application No. 60/472,608, filed May 22, 2003.

BACKGROUND OF THE INVENTION

[0002] This invention relates to web winding cores for use in winding web material such as tissue paper, paper toweling, and the like. More particularly, the invention is related to a fiber reinforced polymer winding core.

[0003] The tissue making process entails winding the finished tissue product onto a cylindrical tube, commonly called a “core”. The core is supported by a mandrel that is inserted into the core. The mandrel rotates the winding core to a velocity with a surface speed that matches the linear speed of the tissue material moving through the end of the tissue machine. At the start of the winding process an adhesive is typically sprayed onto the winding core and the mandrel-driven winding core is brought into contact with the moving tissue material, which adheres to the winding core and begins to be wound onto the winding core. When tissue winding is complete, the tissue material is cut and the tissue-wound core is brought to a stop by the mandrel. A table or similar means is brought into support for the tissue-wound core and the mandrel is extracted from the core. The tissue-wound core is then either transported to a storage facility or to a converting machine for conversion, i.e., unwinding, transverse perforation and rewinding into commercial sized rolls.

[0004] In the storage facility, the tissue-wound core may be stored either horizontally or vertically. On the converting machines, a plug is inserted into each end of the tissue-wound core. The tissue-wound core is then raised by a mechanical hoist attached to the plugs and lowered into the converting machine. In the converting machine, the plugs support the tissue-wound core as it is rotated to unwind most of the tissue material that was previously wound onto the core. The last several layers of tissue are discarded by cutting them off the core with a sharp knife. The knife often causes damage to the core. After the unwind operation, the core is transported back to the tissue machine where the winding process is repeated. During transportation, the core may be handled manually or with handling equipment.

[0005] The vast majority of prior art winding cores used in tissue making and conversion are constructed from multiple layers of wood pulp fiber (sometimes called paper, board, core board or fiber) and glue that are wound together in a spiral fashion to form a cylindrical tube. Fiber cores can typically be reused on the order of 5-20 times before they are damaged to such an extent that they are no longer usable. Damage to the fiber cores is most commonly caused by storage of the tissue-wound core on its end. The end of the fiber core becomes distorted and crushed when the tissue-wound core is stored in a vertical orientation. After several reuses, the fiber core can become so distorted that the winding core will no longer fit over a mandrel or plugs will no longer fit into its ends. The fiber core is also commonly damaged through the cutting action of the knife that is used to remove the scrap tissue at the end of an unwind operation. During each cutting procedure, the knife penetrates several layers of the fiber core and makes a deep cut over the entire length of the core. After several reuses, the number of cuts becomes great enough that, when the winding core is rotated by the mandrel at high velocity just before the start of a wind operation, the fiber core may begin to delaminate and self-destruct. The integral wall thickness of the fiber core must be such that the winding core can withstand the centrifugal forces caused by high speed spinning and the structural forces caused by the weight of the tissue roll that the winding core must support.

[0006] In the prior art fiberglass composite cores have been utilized in winding applications. However, for the large diameter cores used in winding tissue materials, a typical fiberglass core with adequate resistance to crushing forces imparted by a wound roll weighs considerably more than fiber cores. While a fiber core may weigh one hundred pounds, a comparable fiberglass core will weigh from two hundred to three hundred pounds. This creates safety as well as handling problems. The fiberglass cores used in the prior art for winding applications have been typically constructed from a number of layers of resin impregnated glass fiber wound at a substantially constant angle, i.e., usually 50 to 60 degrees from the axial direction, throughout the wall thickness of the core.

SUMMARY OF THE INVENTION

[0007] The present invention provides a unique solution to the major drawbacks of prior art winding cores. The invention disclosed is a hybrid fiber reinforced polymer core consisting of several layers of different materials that, when combined in a specific sequence and in specific relative quantities, result in a winding core with characteristics superior to prior art cores. The invention winding core weighs approximately the same as fiber cores, but has significantly increased crush strength, crush stiffness, bending strength, bending stiffness, hoop strength, hoop stiffness, impact resistance, cut resistance, moisture resistance, and abuse tolerance. In summary, the present invention hybrid composite winding core has properties which have been specifically tailored to exhibit a high degree of stiffness, strength and resistance to abuse without increasing mass over the prior art. The present invention core is particularly useful when used in conjunction with large-scale tissue manufacturing operations.

[0008] These together with other objects of the invention, along with various features of novelty which characterize the invention, are pointed out with particularity in this disclosure. For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a side view, partly in section, of a winding core constructed according to the present invention.

[0010] FIG. 2 is a cross sectional side view of the portion of the winding core shown in FIG. 1 as area 2.

[0011] FIG. 3 is a close up cross sectional view of an end cap.

[0012] FIG. 4 is a perspective view of a winding core with textured outer surface.

DETAILED DESCRIPTION OF INVENTION

[0013] Referring to the drawings in detail wherein like elements are indicated by like numerals, there is shown a winding core 10 constructed according to the principles of the invention. The invention example shown pertains to a core with a sixteen inch nominal inside diameter with a nominal length of one hundred inches. A prior art fiber core of this size would typically require a wall thickness of between five-eighths inches to three-quarters inches, and would weigh approximately one hundred pounds in order to provide adequate strength, stiffness and resistance to abuse. The invention winding core is not limited to this particular core size, but applies to cores of virtually any size.

[0014] The winding core 10 of the present invention is constructed of multiple layers of polymer impregnated fibrous materials forming a cylindrically-shaped, hollow winding core 10 with two open ends 2, a wall 3 connecting both ends 2, said wall 3 having an exterior surface 4 and an inner surface 5. The wall 3 is comprised of said layers. The wall layers are formed preferably through filament winding, but could also be formed other known manufacturing methods, including by hand by means of a roll table. The winding core layers are constructed so that structural reinforcing layers are sandwiched between outer protective layers. The outermost protective layer and innermost protective layer define the outer wall surface 4 and inner wall surface 5 of the winding core.

[0015] In a preferred embodiment shown in the drawings the winding core has a wall comprised of nine layers, starting with the innermost layer 11 to the outermost layer 19. The innermost 11 and outermost layers 19 are comprised of a composition with a high percentage of polymer resin, i.e., approximately sixty to eighty percent. The innermost 11 and outermost 19 layers act as sealers protecting the other layers from fraying damage. The thickness of each of these layers, i.e., innermost 11 and outermost 19, is approximately one hundredth to two hundredth inches in thickness. The outermost layer 19 defines the winding core wall exterior surface 4 and the innermost layer 11 defines the winding core inner surface 5.

[0016] The next layers in, i.e., second layer 12 and eighth layer 18, are comprised of woven fiberglass cloth with approximately equal amounts of fiber in the warp and fill directions. These layers have a lower resin content than the innermost 11 and outermost 19 layers. The thickness of each of these layers, i.e., second layer 12 and eighth layer 18, is approximately one hundredth to two hundredth inches in thickness and each contains approximately thirty to fifty percent resin. The second layer 12 and eighth layer 18 provide resistance to knife cuts and damage from core plugs.

[0017] The third through seventh layers 13-17 are the structural layers providing resistance to longitudinal bending and radial crushing. Specifically, the third layer 13 and seventh layer 17 contain carbon fiber primarily oriented in the circumferential (hoop) direction. The third 13 and seventh 17 layers are each approximately one hundredth to two hundredth inches in thickness and each contains approximately twenty to forty percent resin. The purpose of the third 13 and seventh 17 layers is to provide extra resistance to crushing.

[0018] The fourth layer 14 and sixth layer 16 contain glass fibers oriented in the circumferential (hoop) direction. The fourth 14 and sixth 16 layers are each approximately three hundredth to six hundredth inches in thickness and each contains approximately twenty to forty percent resin. The purpose of the fourth 14 and sixth 16 layers is to resist crushing.

[0019] The middle layer 15, i.e., fifth layer, contains glass fibers primarily oriented in a longitudinal direction, i.e., parallel with a winding core longitudinal axis. The middle layer 15 is approximately four hundredth to eight hundredth inches in thickness and contains approximately twenty to forty percent resin. The purpose of the middle layer 15 is to resist longitudinal bending. Although this layer is described as the middle layer, it could actually be located at any layer position and provide equivalent resistance to longitudinal bending. However, in the preferred embodiment this layer is centered as the middle layer 15 within the wall thickness. In doing so, the crushing stiffness is maximized. If the fifth layer were placed at any other location, the bending and hoop properties of the tube would not be significantly changed, but the crush properties of the structure would be significantly adversely affected.

[0020] Each layer is typically combined with wet resin, in the percentage ranges indicated above, as the layer is wound over a cylindrical tool commonly called a mandrel. After winding on the mandrel, the resin is cured at an elevated temperature to initiate cross-linking and provide a rigid structure. The resin that is typically used is a Bisphenol F or Bisphenol A epoxy resin combined with an anhydride type hardener. Other types of epoxy resin/hardeners combinations could work as well. The applicable resin systems include, but are not limited to, polyester resins, vinyl ester resins, phenolic resins, or other generally acceptable thermosetting resins suitable for use with filament winding equipment. Thermoplastic resins could also be used with some modifications to manufacturing equipment. The core could also be made with pre-impregnated materials.

[0021] In another embodiment of the invention, a pre-manufactured plastic or metal end cap 20 is mechanically or adhesively (or a combination of both) fastened to either end of the winding core providing further enhanced strength, stiffness and abuse resistance properties. In the example shown, the innermost 11, outermost 19, second 12 and eighth layers 18 are removed near the winding core end to be capped, and the cap 20 slid over the end of the winding core wall. A post-formed bead 22 may be formed on the outside portion 21 of the cap 20 to mechanically attach the cap 20 to the winding core 10.

[0022] In another embodiment of the invention, a molded texture 9 could be formed on the outermost layer 19 of the winding core 10 to assist in gripping the tissue material during the start of a wind. The texture could also be sprayed or painted on.

[0023] While the mass density of the invention winding core material is typically two to four times as great as that of a prior art fiber core, the invention winding core for the example described above only requires a wall thickness of approximately one-fourth to one-half that of a typical fiber core. The invention core construction provides a resistance to both crushing and bending forces which is considerably greater than that of a prior art fiber core. This results in a winding core with superior crush and bending properties while weighing essentially the same as a prior art fiber core. Along with superior crush and bending properties comes substantially increased resistance to knife damage and abuse damage from winding and unwinding.

[0024] It is understood that the above-described embodiment is merely illustrative of the application. Other embodiments may be readily devised by those skilled in the art which will embody the principles of the invention and fall within the spirit and scope thereof. A significant portion of this invention are the layers that comprise the structural portion of the winding core. These layers are identified with the reference numerals as 13-17 in FIG. 2. The orientation and location of the fibers is of paramount importance in these layers. It is preferably to have the fibers that resist longitudinal bending located in the center of the wall thickness and the fibers that resist crushing forces located as near to the inner and outer wall surfaces as possible. The remaining layers are essentially protective layers, though they do add a small amount of structural strength and stiffness.

[0025] Making the structural layers from a fiber reinforced material is a preferred choice because the properties of fibers are inherently directional. Applicant has chosen to use primarily glass and carbon fibers in the example shown, but there are many other variable choices, including Kevlar, polyethylene, basalt, hemp, kenaf, and sisal, or other organic fibers.

[0026] The material that holds the fibers of a fiber reinforced composite together is called the “matrix”. Applicants have chosen an epoxy resin as a preferred matrix. However, there are many other materials that could serve as the matrix for this invention including other thermoset polymers like polyester or vinylester, or thermoplastic materials such as polyethylene.

Claims

1. A hybrid, fiber reinforced, polymer, web winding core for use in winding web material, comprising:

a cylindrical, hollow winding core wall having two ends, said two ends defining a winding core longitudinal axis, said wall having an exterior surface and an inner surface, said exterior surface and inner surface defining a wall thickness, said wall being comprised of a plurality of layers made from fiber reinforced material, said plurality of layers having a plurality of structural reinforcing layers sandwiched between a plurality of outer protective layers, said plurality of structural reinforcing layers adapted to provide resistance to longitudinal bending and radial crushing, said outer protective layers having an outermost protective layer defining the wall exterior surface and an innermost protective layer defining the wall inner surface.

2. A winding core as recited in claim 1, wherein:

a plurality of the plurality of structural reinforcing layers contains material with fibers primarily oriented in a longitudinal direction parallel with the winding core longitudinal axis, said layer adapted to resist longitudinal bending.

3. A winding core as recited in claim 2, wherein:

a plurality of the plurality of structural reinforcing layers contains material with fibers primarily oriented in a circumferential direction, said layers adapted to resist crushing.

4. A winding core as recited in claim 3, wherein:

said plurality of layers containing material with fibers primarily oriented in a longitudinal direction are located in the center of the wall thickness; and

said plurality of layers containing material with fibers primarily oriented in a circumferential direction are located near to the inner and outer wall surfaces.

5. A winding core as recited in claim 4, further comprising:

an end cap slidably positioned over and fastened to each end of the winding core wall.

6. A winding core as recited in claim 5, further comprising:

a molded texture formed on said outermost protective layer.

7. A winding core as recited in claim 6, wherein:

said fiber reinforced material is held in a matrix formed from the following classes of materials:

thermoset polymers such as epoxy resins, polyester resins, or vinyl ester resins, phenolic resins and thermoplastic resins.

8. A winding core as recited in claim 7, wherein:

said fiber reinforced material contain fibers made from the following classes of materials: glass, carbon, Kevlar, polyethylene, basalt, hemp, kenaf, and sisal.

9. A winding core as recited in claim 8, wherein:

said plurality of layers containing material with fibers primarily oriented in a longitudinal direction contain glass fibers in a matrix containing twenty to forty percent resin.

10. A winding core as recited in claim 9, wherein:

a plurality of layers containing material with fibers primarily oriented in a circumferential direction contain carbon fibers in a matrix containing twenty to forty percent resin.

11. A winding core as recited in claim 10, wherein:

a plurality of layers containing material with fibers primarily oriented in a circumferential direction contain glass fibers in a matrix containing twenty to forty percent resin.

12. A winding core as recited in claim 11, wherein:

the outermost and innermost protective layers are comprised of a composition with sixty to eighty percent polymer resin, said innermost and outermost protective layers adapted to act as sealers protecting the other layers from fraying damage.

13. A winding core as recited in claim 12, wherein:

a plurality of protective layers being comprised of woven fiberglass cloth with approximately equal amounts of fiber in warp and fill directions, said protective layers containing thirty to fifty percent resin.

14. A winding core as recited in claim 13, wherein:

a portion of said outer protective layers are removed near the winding core end and said cap positioned over that portion of the winding core wall without the outer protective layers.