Patent Application
20060060008
The invention relates to winding cores for web rolls. The invention relates more particularly to a test device and testing method for assessing the weight capacity of a core.
Tubular winding cores are used for supporting rolls of web materials wound about the cores. Various web materials are commonly supplied in the form of relatively large rolls wound about cores. Such web materials can include paper, plastic film, metal foil, sheet metal, textile, and the like. The cores are often paperboard tubes, but can comprise other materials such as plastic, fiber-reinforced plastic, and others. Particularly in the case of paperboard cores, weight capacity of the cores is a significant issue. In a winding or unwinding process, the web roll is typically supported in the winding or unwinding machinery by engaging the core only at its opposite ends, such that the major part of the length of the core is suspended between the opposite ends. The ends can be engaged by chucks inserted into the ends of the core.
After completion of winding of a roll, it is standard industry practice at least in the case of film to prevent the wound material from contacting the ground or other surfaces that could damage the film material. Accordingly, during various phases of movement of the wound roll from the winding machinery, through handling, storage, shipping, all the way up to the ultimate usage of the roll, the roll is at all times supported by engaging the opposite ends of the core in various support structures. For instance, the ends of the core can be rested in cradles, which can comprise openings of various shapes (semi-circular, V-shaped) in end walls between which the roll is suspended. Alternatively, the roll can be supported between a pair of end walls that support end plugs that fit into the opposite ends of the core. Because most of the core length between the ends is unsupported, with very heavy rolls the core may be stressed to the point of failure. Alternatively, the supporting cradle or end wall/plug structures may be stressed to the failure point.
Accordingly, it would be desirable to be able to test cores and core-supporting structures to determine their weight-holding capacity. The testing advantageously should simulate as closely as possible the actual usage conditions.
The present invention addresses the above needs and achieves other advantages, by providing a testing device and method wherein the core of a web roll is supported by core supports in a manner substantially identical to that used in actual use, and a weight load simulating assembly is used to load the web roll so that the core and core supports are loaded in a manner closely simulating the weight of wound web material on the core and/or core supports in actual use. Either the core, or the core supports, or both, can be tested for strength in this manner.
A test device in accordance with one embodiment of the invention includes a stationary web roll support assembly comprising a base and a pair of core supports spaced apart and affixed to the base with the core supports projecting upwardly from the base, the core supports structured and arranged to engage opposite ends of a core of a web roll so as to support the web roll. The test device also includes a movable weight load simulating assembly comprising a flexible belt having opposite ends, and a belt holder structured and arranged to secure the opposite ends of the belt to the belt holder with the belt forming a generally U-shaped loop about an outer surface of the web roll intermediate the opposite ends of the core. Movement of the belt holder away from the stationary web roll support assembly causes the belt to exert a load on the web roll, simulating weight load on the core and core supports.
In one embodiment, the base is structured and arranged to alternatively support any of various types of core supports including stands with chucks, end walls with cradles, end walls with end plugs, and end walls with cradles and end plugs.
Advantageously, the base is structured and arranged to be affixed to a frame of a load testing machine, and the belt holder is structured and arranged to be affixed to a load cell of the load testing machine.
In the case where the core supports comprise stands and chucks mounted to the stands, the chucks are structured and arranged to engage an inner surface of the core at each end of the core so as to support the web roll.
Alternatively, the core supports can comprise generally plate-shaped end walls projecting perpendicularly from the base and parallel to each other, the end walls defining cradles structured and arranged to engage an outer surface of the core at each end thereof so as to support the web roll. As an alternative to cradles, the end walls can have end plugs structured and arranged to extend into the opposite ends of the core and engage an inner surface of the core at each end so as to support the web roll. Cradles may also be used in combination with end plugs that fit into the core ends for reinforcement of the core ends.
The belt holder in one embodiment includes an adjustment mechanism structured and arranged to adjust the length of the loop of the belt. It is also advantageous in some instances for the belt to comprise two or more separate belt segments arranged side-by-side for engaging different lengthwise portions of the web roll.
A method for testing roll weight capacity in accordance with the invention comprises the steps of supporting a web roll by engaging opposite ends of a core of the web roll with a pair of stationary core supports, looping a flexible belt about an outer surface of the web roll at a position intermediate the opposite ends of the core, and advancing the belt in a direction substantially perpendicular to a longitudinal axis of the core such that the belt exerts a load on the web roll simulating weight load on the core and core supports.
The method can further include the steps of measuring the amount of force exerted on the belt and thus on the web roll, and optionally measuring strain of the core and/or strain of the core supports with at least one strain gage. The method can entail gradually increasing the amount of force exerted on the belt until a failure of either the core or the core supports occurs, and recording a maximum amount of force at which the failure occurs. The amount of force exerted on the belt (and the strain of the core or core supports, if measured) can be recorded as functions of time.
As noted, the core supports can be affixed to a frame of a load testing machine, and the belt can be secured to a load cell of the load testing machine. The load cell is advanced to cause the belt to exert a load on the web roll.
Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The present inventions now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.
The test device 20 is mounted in the testing machine between the foundation F and the load cell L. With reference to
The test device 20 also includes a pair of core supports 30 and 30′ mounted atop the base 22. In the embodiment of
The test device 20 further includes a movable weight load simulating assembly 50. The weight load simulating assembly includes at least one flexible belt 52 having opposite ends secured in a belt holder 54, with the belt forming a generally U-shaped loop about an outer surface of a web roll 56 wound about the core test specimen S, intermediate the opposite ends of the core. In the illustrated embodiment, two belts 52 are employed, with each belt engaging a partial lengthwise portion of the web roll, but alternatively a single belt could be used. The belt holder 54 has a pair of belt-securing mechanisms 58 (only one shown in
The frame 60 includes a box member comprising an upper support plate 62, a lower support plate 64 vertically spaced below the upper support plate, and vertical plates 66 extending between the opposite longitudinal edges of the plates 62, 64. A bottom mounting plate 68 is disposed below the box member and affixed thereto. The mounting plate 68 is wider than the box member such that portions of the plate extend beyond the opposite longitudinal edges of the box member. Vertical mounting plates 70 are affixed to the opposite ends of the box member and mounting plate 68, and the plates 70 have portions that extend vertically downward beyond the plate 68. Midway between the two end plates 70, another mounting plate 71 is affixed to the plate 68 and extends downward therefrom, as shown in
With reference to
The opposite end of each belt 52 can be secured in the belt holder 54 by a mechanism substantially as described above, but without necessarily having the adjustability feature provided by the rotatable plate 80. Alternatively, the opposite end of each belt can be secured in the belt holder in any other suitable fashion allowing removal and replacement of the belt when broken or worn out.
In use, the base 22 of the test device is affixed by threaded fasteners 86 or the like to the foundation F of the testing machine M, and the belt holder 54 is affixed to the load cell L. A web roll 56 is mounted in the test device by placing the web roll into the loops of the belts 52 with one or both of the core supports 30, 30′ removed, and temporarily resting the web roll in the belts while fastening the removed core support(s) to the base 22. The chucks 32, 32′ are inserted into the opposite ends of the core specimen S before one or both of the core supports are affixed to the base 22. Once the core supports are affixed to the base, with the chucks engaged in the ends of the core, the belts 52 are adjusted to the correct length, if necessary, so that the belts snugly engage the outer surface of the web roll. The test can then proceed by operating the load testing machine to advance the ram R upwardly so that load is exerted on the web load by the belts, thereby simulating weight load on the core specimen S.
As known in the art, the load testing machine includes its own instrumentation, including the load cell L, for measuring the tensile force exerted between the ram R and the foundation F of the machine, which is equal to the load exerted on the web roll by the belts. The load can be recorded as a function of time. Generally, the ram R is advanced at a predetermined constant rate, and the load increases with time until a catastrophic failure occurs in the test specimen, at which point the load suddenly drops to zero or thereabouts. In the embodiment of
Other parameters of interest can be measured and recorded in addition to the load exerted on the core versus time. For instance, one or more strain gages 88 can be attached to the core specimen S for measuring strain in the core at one or more locations, which also can be recorded as a function of time and can be correlated with the measured load.
The test device in accordance with the invention can be used to test more than just core strength. As previously noted, there are times during temporary storage and transportation of web rolls when the rolls are rested in cradles that support the opposite ends of the cores or mounted between end walls having end plugs that fits into the ends of the cores to support the rolls. It may be desired to test the strength of the cradle, end wall, and/or end plug structures. To do so, the chain of components connecting the machine ram to the machine foundation must be such that the component being tested is the weak link. Thus, for example, if the cradles are to be tested for strength, then it must be assured that the core does not fail before the cradles. This can be assured by using a special thick-walled core of great strength.
In some cases, web rolls are supported in cradles that are configured as semi-circular or arcuate, or V-shaped, structures that engage only a part of the circumference of the core ends resting in the cradles.
Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
