Composite expanding shaft with external gripping elements

Abstract

A light weight, filament wound carbon fiber base tube, with external longitudinal rails of a dissimilar material housing gripping elements and wear strips, all affixed to the outside of the base tube. The wear strips are made from an ultra high molecular weight polymer. The gripping elements are pneumatically driven.

Description

BACKGROUND OF THE INVENTION

[0002] This invention relates to gripping shafts made from dissimilar materials, and in particular, to carbon fiber reel spools shafts with external gripping elements.

[0003] In any process where web material is rewound, be it in the tissue and paper industry or the plastic and film industry, the material is wound onto a core. The core is held on a shaft. Shafts in their simplest configuration consist of either a solid steel shaft with a rotating outer sleeve or steel tubing with journals secured into it. These basic designs are still prevalent and can weigh from 300 to 30,000+ pounds; be 50 to 330 inches long; and 6 to 18 inches in diameter. While durable in design, productivity is limited because the combined weight and length of these shafts limit high speed operations. Since these shafts do not grip the core, they require the use of clamping mechanisms to prevent the core from moving freely along the body, which in turn allows the web material to shift and intermesh with an abutting roll. Web material is normally slit into several rolls before it is wound onto a core. Lateral movement of the web material causes uneven edges. This leads to handling issues that damage the ends of the cores and the edges of the web material.

[0004] Shafts were later developed with the same basic steel design but with the addition of gripping elements. The gripping elements eliminated the need for the use of mechanical stops since the gripping elements exerted enough outward force to hold the core in place. Typically, the gripping elements are activated pneumatically or mechanically, expanding diametrically to grip the core and hold it in place during winding or unwinding of the web material. To allow the shaft to be extracted from the core within the wound roll, air is then released to deflate the gripping elements or the mechanical drive is reversed. This eliminated the need for the operators to secure the core position with clamps or other mechanical devices. The newer shafts address the issue of core position and operator ease but still suffer from the problem of being very heavy and having a limited high speed operation.

[0005] Metal shafts have many characteristics which are undesirable, namely, high weight and high rotating inertia. This results in high shaft deflection, high vibration, and premature bearing wear and difficulty with dynamic balance, which causes high driving forces.

SUMMARY OF THE INVENTION

[0006] The present invention is the next evolution in gripping shafts. The heavy steel body of prior art shafts is replaced by a base tube material to which are attached manufactured segments of dissimilar material that house pneumatically actuated gripping elements. The base tube material may be a carbon fiber tube, titanium tube, high-grade aluminum tube, steel tube, or any other material that will offer desired physical properties of lighter weight. For example, a shaft made from carbon fiber material rather than metal weighs substantially less (up to 50% less), has a lower rotating inertia (up to 80% less), and high critical speed while maintaining a tube stiffness similar to metal. The main advantage of using dissimilar materials is the ability to optimize the gripping shaft to suit the application, i.e., lighter weight, better wear properties, and strength in appropriate areas. There would not be any benefit to having separate, joinable pieces of the same material.

[0007] The present invention affixes to the above described light weight tube manufactured segments such as extrusions of some different material, such as aluminum, titanium, reinforced plastic. Means for gripping the core and thus securing the core's location are provided by pneumatic gripping elements contained within the extrusions. The resultant reduction in weight from prior art devices is significant and allows a user to dramatically increase web speed while still gripping the core. This ensures that the web material will remain in position relative to the edge of the core. The present invention is most practical with a dead shaft where the journals rotate independent of the body.

[0008] In order to have a gripping shaft body that will accommodate the fixed shaft through the inside, the gripping elements are located on the outside. In order to maximize the critical speed of the shaft body, the base shaft tube is made from carbon fiber. The gripping element extrusions are attached to the outside of the carbon tube. In the case of carbon fiber and aluminum extrusions, the extrusions are affixed by mechanical attachment directly into the carbon fiber tube. Depending on what materials comprise the base tube and the housing for the external gripping elements the bonding methods between the two dissimilar materials may include welding, rivets, adhesive bonding, fasteners, integral interlocking shapes, or any other means available to secure two dissimilar materials.

[0009] The extrusions which house the external gripping elements are protected from direct contact from the core material by strips or rods which protrude slightly above the extrusion. The strips prevent the core from coming into direct contact with the extrusions. The strips are made from a material which has high strength and good wear characteristics. Materials such as ultrahigh molecular weight polymers are preferred because they have excellent wear properties, are light weight and easily manufactured. The wear strips may be affixed directly to the base tube in the same manner as the extrusions or can be integrated directly into the extrusions. The wear strips are preferably modular in design and easily replaceable as they are a wear item and over time will need to be replaced. The wear strips are positioned between each of the external gripping elements and also provide the shaft with a consistent external diameter. Because of their low coefficient of friction they also aid in the installation and removal of spent and new cores.

[0010] The gripping elements may be made from a wide variety of materials, including steel, silicone, rubber, etc. The selection of a proper material is application dependent. Preferably, the gripping elements are retractable back into the extrusion so that the shaft can be easily extracted from the core. In one preferred embodiment, the gripping elements, which are comprised of small rubber bladder tubes, are independently expanded with air through a manifold used to both deliver air to the bladders and vent the bladders. Each bladder acts independently of the other, thereby ensuring the loss of only one gripping element if there is a bladder failure and air pressure is lost in that particular bladder. The remaining gripping elements will continue to hold the core securely.

[0011] The invention, therefore, is a light weight base tube, preferably a filament wound carbon fiber composite tube, with external extrusions of a dissimilar material, preferably aluminum, which house gripping elements and wear strips, all affixed to the base tube. The wear strips are preferably made from ultra high molecular weight polymer. The base tube replaces a prior art metal bodied dead shaft. The present invention permits end users to retain their current shafts along with all of their bearings. The present invention replaces end users' prior art outer shell with a light weight composite shaft with gripping elements. Since the present invention has its gripping elements attached to the outside of the base tube, end users are not required to change core size and thus can reuse all of their internal components. The present invention may also be used in a shaft with affixed journals.

[0012] The present invention overcomes two of the biggest problems with the traditional shaft, i.e., weight and the ability to grip the core. By utilizing carbon fiber in the body of the shaft, the weight is dramatically reduced and, therefore, the critical speed is increased allowing an increase in the operational speed of the shaft. The weight reduction for any given design may be more than 50%. The end user realizes further gains in productivity, as the operators no longer have to attach clamping collars and secure the core in place. The user simply inflates the shaft, and the external gripping elements grip the inside of the core. In the case of the dead shaft, the present invention allows end users to retain their original axle and bearing assemblies and reuse them. The external gripping elements and wear strips allow for easy preventative maintenance on the only wear items in the shaft, and the modular design ensures that replacement parts will be easily installed and stocked. The same argument exists for a live shaft reel spool, where the journals rotate with the shaft housing.

[0013] 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

[0014] FIG. 1 is a side elevational view of a shaft constructed according to the principles of the invention.

[0015] FIG. 2A is a cross section view along the line B-B of FIG. 1.

[0016] FIG. 2B is close up view of Detail “B” of FIG. 2AFIG. 3 is a cross section view along the line C-C of FIG. 1.

[0017] FIG. 4 is a cross section view along the line D-D of FIG. 1.

[0018] FIG. 5 is a close up view of Detail “C” of FIG. 1.

[0019] FIG. 6 is a close of view of Detail “A” of FIG. 1.

[0020] FIG. 7 is a cross sectional view of a longitudinal rail.

[0021] FIG. 8 is a close up view of a fill and vent valve.

DETAILED DESCRIPTION OF INVENTION

[0022] Referring to the drawings in detail wherein like elements are indicated by like numerals, there is shown a gripping shaft 1 constructed according to the principles of the present invention. The shaft 1 has an elongated cylindrical body 2 with two, opposite end portions 3, said end portions defining a longitudinal axis of the shaft 1. A portion of the elongated body between the opposite end portions 3 is termed the intermediate body portion 4. The shaft 1 is comprised of a generally cylindrical carbon fiber tube 10 having an internal wall 11 and an external wall 12, and two opposite ends 13 joining the shaft end portions 3, said opposite ends 13 and shaft end portions 3 defining the tube 10 and shaft 1 longitudinal axis. The tube external wall 12 has twelve elongated, parallel, aluminum, longitudinal rails 20 attached thereto and forming, in conjunction with fiber tube 10, the shaft intermediate body portion 4. The rails 20 are attached radially to the tube external wall 12 and lay in longitudinal planes parallel to the tube and shaft longitudinal axes. The rails 20 are equally spaced about the tube external wall 12. Other embodiments of the invention could have a different number of rails 20 and could be made from a material different from aluminum but with substantially similar properties and characteristics. The individual rails 20 assembled circumferentially create a cylindrical profile termed the gripping shaft outer diameter 5. The rails 20 are attached to the tube external wall 12 by mechanical means as described below.

[0023] To accommodate journals, other driving hardware and the like at the shaft ends, the shaft end portions 3 each have a protective end external steel sleeve 30 positioned about and joined to the carbon fiber tube external wall 12. The protective end external steel sleeve 30 has an inner surface 31 and an outer surface 32. The protective ends 30 provide a connection point for the tube 10 and a truncation location for individual rails 20. The protective ends 30 are preferably made using a material exhibiting properties such as high wear resistance, high impact and shock resistance, and dimensional stability.

[0024] The gripping shaft 1 is further comprised of an inner steel sleeve 40, having an inner surface 41 and an outer surface 42, positioned within and joined to the carbon fiber tube internal wall 11 beginning approximately at the junction between shaft intermediate portion 4 and shaft end portion 3 and extending toward the shaft end a predetermined distance. In order to accommodate customer bearings, the inner steel sleeve 40 does not extend to the end of the shaft. The inner steel sleeve 40 may be secured to the tube 10 by mechanical fasteners, bonded connection or an interference press fit.

[0025] The tube 10 may be manufactured from any light weight, high stiffness material, provided that it has dissimilar properties from the rails 20. Desirable tube properties include low inertia, high resistance to torsional deflection and high bending stiffness. The present embodiment of the invention utilizes a carbon fiber composite which may be manufactured by filament winding, pultrusion, hand lay-up or roll table wrapping.

[0026] As may be seen most clearly in FIG. 7 illustrating a cross sectional view of a rail 20, each rail has an inner surface 21 and an outer surface 22. The rail inner surface 21 matches tangentially the tube external wall 12. The rails 20 are secured to the tube external wall 12 in a captive manner while allowing longitudinal expansion and contraction due to temperature or operational changes. In one embodiment of the invention, the rails 20 are attached to the tube 10 utilizing a threaded fastener connection with slotted holes 28 in the rails 20. The present invention positions these holes 28 in an alternative fashion longitudinally. The rails 20 encompass three critical components integral to the invention, i.e., gripping elements 50 and their respective components, sliding strips 26, and rotational balance correction weights. The rail outer surface 22 has two longitudinal channels, a first channel 23 and a second channel 24. The second channel 24 has a subchannel 25 formed therein. The channels 23, 24 and subchannel 25 all use an interlocking design to help secure their contents.

[0027] The subchannel 25 provides means for holding and positioning weights for balancing the gripping shaft 1. Balance correction may include, but is not limited to, custom flat bar stock or suitable weight inserted into the subchannel 25 and secured by a central fastener or permanent bonding/adhesion. The second channel 24 provides means for holding sliding strips 26 which protrude slightly above the rail outer surface 22. The sliding strips 26 prevent a core from coming into direct contact with the rails 20. The strips 26 are made from a material which has high strength and good wear characteristics. Materials such as ultrahigh molecular weight polymers are preferred because they have excellent wear properties, are light weight and easily manufactured, but equivalent materials such as Nylon, Acetal, or the like, may be used. The sliding strips 26 are preferably modular in design and easily replaceable as they are a wear item and over time will need to be replaced. The sliding strips 26 are positioned between each of the external gripping elements 50 and also provide the gripping shaft 1 with a consistent external diameter. Because of their low coefficient of friction they also aid in the installation and removal of spent and new cores.

[0028] The rail first channel 23 contains a gripping element 50 comprised of: an elongated expandable pneumatic bladder 51; two elongated, protective polymer strips 52, such as that sold under the trademark MYLAR, placed under and over the bladder 51; an elongated rubber gripping element 53 placed over the outer polymer strip 52. As the bladders 51 are pneumatically activated and expanded, the gripping elements 53 move radially outward thereby engaging a core. The protective ends 30 have longitudinal channels 33 formed therein corresponding to the rail first channel 23. The gripping elements 50 continue through the protective end channels 33 and terminate near to the gripping shaft end portions 3. One end of the gripping elements 50 terminates in a valve assembly 54 interconnected to an air manifold 55.

[0029] Unlike prior art gripping shafts, the present invention incorporates a combination of dissimilar components assembled in a manner that exhibits enhanced characteristics. In the present invention, a carbon fiber tube 10 is mated with an inner steel sleeve 40, steel protective ends 30, and aluminum longitudinal rails 20 containing ultra-high molecular weight sliding strips 26 and rubber gripping elements 50. This combination provides an increased load carrying capacity, higher bending stiffness, low weight and low inertia.

[0030] In one specific embodiment of the invention, the gripping shaft 1 was constructed of a filament wound tube 10, twelve aluminum longitudinal rails 20, and two protective steel ends 30. The filament wound tube 10 was created on a 12.03 inch diameter mandrel and was ground to a finish diameter of 14 inches. The length was machined to 236.5 inches. The protective ends 30 were machined to approximately a 14 inch inner diameter nominal with an outer diameter of 15.95 inches nominal. Insertion of the tube 10 to the protective ends 30 was 14 inches and was secured internally using a 12.03 inch outer diameter machined inner sleeve 40. Aluminum longitudinal rails 20 were made using an extrusion process with an approximate cross sectional width of 4 inches and a height of 1 inch. The inner and outer surface is curved to 14 inches diameter and 15.96 inches diameter, respectively. The twelve longitudinal rails 20 are positioned radially (every 30 degrees) and secured to the tube 10 using fasteners.

[0031] 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.

Claims

1. A gripping shaft having an elongated cylindrical body with two, opposite end portions, said end portions defining a shaft longitudinal axis of the shaft, said shaft having an intermediate body portion between the opposite end portions, comprising: a generally cylindrical light weight tube having an internal wall, an external wall, and two opposite ends joining the shaft end portions, said opposite ends defining a tube longitudinal axis, said tube being made from a material having low inertia, high resistance to torsional deflection and high bending stiffness; a plurality of elongated, parallel, longitudinal rails radially attached to the tube external wall and forming, in conjunction with fiber tube, the shaft intermediate body portion, said rails lying in longitudinal planes parallel to the tube and shaft longitudinal axes, said rails being equally spaced about the tube external wall, said individual rails assembled circumferentially creating a cylindrical profile termed a gripping shaft outer diameter, said rails containing a plurality of gripping elements, sliding strips and rotational balance correction weights; a protective end external sleeve forming each said shaft end portion and positioned about and joined to the tube external wall, said protective end external sleeve having an inner surface and an outer surface, said protective ends being made from a material having a high wear resistance, high impact and shock resistance, and dimensional stability; and an inner sleeve having an inner surface and an outer surface, positioned within and joined to the tube internal wall beginning approximately at the junction between shaft intermediate portion and shaft end portion and extending toward the shaft end a predetermined distance.

2. A gripping shaft as recited in claim 1, wherein: each said longitudinal rail has an inner surface and an outer surface, said rail inner surface matching tangentially the tube external wall, said rail outer surface having two longitudinal channels, a first channel and a second channel, said second channel having a subchannel formed therein, said subchannel providing means for holding and positioning weights for balancing the gripping shaft, said second channel providing means for holding sliding strips which protrude above the rail outer surface, said first channel containing a gripping element comprised of: an elongated expandable pneumatic bladder; two elongated, protective polymer strips placed under and over the bladder; an elongated rubber gripping element placed over one of said polymer strips adjacent the rail outer surface.

3. A gripping shaft as recited in claim 2, wherein: each protective end external sleeve has a plurality of channels formed therein corresponding to the rail first channel, said gripping elements continuing through the protective end channels and terminating near to the gripping shaft end portions, said bladder having an end terminating in a valve assembly interconnected to an air manifold.

4. A gripping shaft as recited in claim 3, wherein: said tube is made from a material dissimilar to said rails, protective end external sleeves and inner sleeve.

5. A gripping shaft as recited in claim 4, wherein: said tube is made of a carbon finer material.

6. A gripping shaft as recited in claim 5, wherein: said rails are made from aluminum.

7. A gripping shaft as recited in claim 6, wherein: said inner sleeve and protective end external sleeves are made from steel.

8. A gripping shaft as recited in claim 7, wherein: said sliding strips are made from an ultra-high molecular weight polymer.

9. A gripping shaft as recited in claim 8, wherein: the rails are attached to the tube utilizing a threaded fastener connection with slotted holes in the rails.

10. A gripping shaft as recited in claim 9, wherein: said first channel, second channel and subchannel each have an interlocking cross section.

11. A gripping shaft as recited in claim 10, wherein: said weights are comprised of flat bar stock.