Shielding Device
The present invention is a shielding device and method of use that is designed to protect the edge of an article, such as a paper towel roll with a mating inner boundary, from becoming wet or soiled by a user's fingers. The present invention includes a planar base having a first face portion and an opposing second face portion, the first face portion includes a ridge within an outer periphery portion of the base. The second face portion is adjacent to the article, and an extension projects therefrom with a longitudinal axis substantially perpendicular to the planar base. Furthermore, the extension is sized and configured to have an interference fit in relation to being received by the mating inner boundary such that the shielding device and article form a unitary assembly.
The present invention relates generally to a new and improved accessory to be placed at the end of a roll of paper material to prevent dirtying or wetting the unused portion of the paper roll when removing another portion for use. More particularly, the present invention relates to a device having a ridge on both the inner and outer circumferences placed at the end portion of a paper towel roll wherein, operationally, a person can use a hand that is wet or soiled to turn the roll to dispense paper towels and then hold it steady while one or more paper towels are removed or torn off from the roll without wetting or soiling the towels that remain on the roll.
FIELD AND BACKGROUNDRolls of paper material are ubiquitous in American society, finding uses in the printing industry as well as, and perhaps most commonly, for cleaning purposes. The paper towel has become a staple in the American household as it is useful for cleaning and wiping up spills and other messes in the kitchen, bathroom, garage, and virtually every other room in the house. A paper towel roll typically consists of several hundred towels separated by perforations loosely wrapped around a hollow cylindrical cardboard core. These rolls are commonly placed on a vertical or horizontal dispenser that may be mounted on another surface, however such a dispenser is not required and the roll can be used as it is.
There are several problems with using a paper towel roll without any sort of dispenser. First, the person must pick up the roll either by gripping the roll and directly touching the exposed paper towels, or by inserting their fingers or another object into the hollow cylindrical core. If the person's hands are wet or soiled, the top layer of exposed paper towels or alternatively, the ends of the entire paper towel roll will also become wet or soiled due to their high level of absorbency by design. Second, because of this absorbent nature of paper towels, any moisture will necessarily soak through to additional layers and is not confined merely to the paper towel first touched. Additionally, because the paper towels are loosely wound around the hollow cylinder, moisture and dirt may drip down between the sheets as well if the roll is placed in a vertical standing position.
Paper towel roll dispensers typically are either mounted on a wall or underneath a cabinet and hold the roll horizontally, or they hold the roll vertically via a pole extending from a base on a table top for instance. The vertical placement of paper towel rolls is gaining popularity because the dispenser is portable and takes up less room on a countertop. One problem with current designs of paper towel roll dispensers is that in order to steady a roll so that some towels may be removed, as with using the paper towel roll without the dispenser, the person generally must touch some of the remaining towels. Some dispensers feature an end cap which may partially protect the unused towels, however, without some sort of lip or groove on the edge, when the paper towel roll is in a vertical position liquids may still drip over the sides onto the unused towels, wetting or soiling them. Continuously wetting and soiling the unused paper towels while tearing off others for use can lead to many problems. Of primary concern is the simple waste of paper towels that could otherwise be used had they not become wet or soiled from a prior use. A mechanic working in a garage may find himself unnecessarily throwing away an entire roll of unprotected paper towels because of one ill-placed oily hand.
Of further concern is the dirt and bacteria that may be transferred back to the person using the paper towel roll, or on to another person who uses the roll later. Kitchen workers and backyard barbeques alike work with raw meat, and using a paper towel is a convenient, disposable way to keep their hands clean. The e. coli or salmonella bacteria can transfer onto the unused paper towels either by absorbing through the towels, or from the edges the person touched, and then when the next person touches the roll to clean their hands, they are instead dirtying them with deadly bacteria that could then be unknowingly introduced into their system. Additionally, many restaurants serving barbeque, ribs, or wings have begun placing a roll of paper towels on each table instead of napkins, either vertically directly on the table or in a bucket, or on a vertical dispenser. Because this style of food is generally meant to be eaten with the person's hands, dirt and germs that may transfer from the ends of the roll to the next person to touch it is particularly concerning because they will likely then touch their food and put it directly in their mouth.
The prior art of paper towel roll dispensers has attempted to address these concerns, however the cap portions of the prior art are often too small to protect the entire end portion of the paper towel roll from liquids or dirt, and because they are often attached to a larger apparatus or device, the cap portion itself cannot be used to assist the user in unwinding the roll. Furthermore, none have ridges on the inner or outer circumferences to contain liquids and prevent them from dripping over the edges and wetting or soiling the unused paper towels.
U.S. Pat. No. 5,938,141 to Kanbar discloses a vertical or horizontal holder for a paper towel roll in which the element is formed by a cap and a plug projecting therefrom, the plug being received in one end of the tubular core whereby the cap then abuts an end of the roll. However, as shown by FIGS. 2 and 6 in Kanbar, the cap at the top is a dome shape having no ridge at the edge to prevent liquids from dripping over the sides and contaminating the remaining paper towels. Additionally, as Kanbar explains in the abstract, the purpose of this invention is to allow a user to tear off a portion of paper towels with one hand while using the other to press the cap down to prevent the roll from unwinding any further. In looking at FIG. 6, element 17P, in Kanbar, the cross shaped insert is taught to be “jammed” into the core, wherein this not any teaching at all for an interference fit.
U.S. Pat. No. 4,720,053 to Vance discloses a device for holding a roll of paper towels in an upright position. Vance shows in figures one and two a cap that screws onto an upstanding pole attached to the base. This cap, however cannot assist the person in turning the paper towel roll without wetting or soiling the unused paper towels because it is attached to the device, and not the paper towel roll itself. Additionally, like the cap in Kanbar, Vance does not have a ridge around the inner and outer circumferences so liquids may drip off of the person's hands, onto the cap, and over the sides, soiling the remaining paper towels.
U.S. Pat. No. 5,605,304 to Ahern Jr. discloses a unitarily molded vertical towel dispenser comprising an arcuate arm member, a cap member connected to the top end of the arm member, and a platform connected to the bottom end. Additionally, Ahern Jr. teaches that the arm member may be used as a carry handle once the roll is inserted between the cap member and the platform. Like Vance, because the cap member in Ahern Jr. is attached to the arm member, it cannot be used to assist the person in turning the paper towel roll without wetting or soiling the unused paper towels. Furthermore, as shown in Ahern Jr.
U.S. Pat. No. 6,502,781 to Tramontina discloses a method and apparatus for more efficiently and easily dispensing paper products disposed horizontally from commercial wall mounted dispensers. While Tramontina teaches an apparatus that fully encases the paper product to prevent it from becoming unnecessarily wet or soiled, the end cap again, like Vance and Ahern Jr., cannot be used to assist the user in turning the paper product, and if the paper becomes caught inside the dispenser the user must stick their hand inside to attempt to free the paper.
U.S. Pat. No. 7,328,869 to Zies discloses a vertical sheet product dispensing device including a base, a shaft connected thereto and extending upwardly, and a top removably connected to the upper portion of the shaft. Column 1, lines 61-67 explains that the object of Zies is to provide a device allowing a user to selectively stop the rotation of the roll without having to touch the exposed sheets. As shown in
What is needed in the present invention is a device capable of being placed on the end of a roll of paper towels with an inner portion to slip fit frictionally inside of the hollow tube core at the center of the roll so that the roll may be easily manipulated and unwound rotationally without needing to touch either the end portion of the paper towel roll or the main body of the roll, thus protecting the unused paper towels from becoming unnecessarily wet or soiled and preventing waste and transfer of dirt or bacteria to the next person who uses the paper towels. Furthermore, what is needed is a ridge on the inner circumference and outer circumference so as to prevent liquids that may have dripped off of the person's hands from dripping over the edges of the device when the paper towel roll is in a vertical position, wetting or soiling the remaining paper towels. This device can be used alone or in conjunction with a dispenser.
The present invention is a shielding device and method of use that is designed to protect the edge of an article, such as a paper towel roll with a mating inner boundary, from becoming wet or soiled by a user's fingers. The present invention includes a planar base having a first face portion and an opposing second face portion, the first face portion includes a ridge within an outer periphery portion of the base. The second face portion is adjacent to the article, and an extension projects therefrom with a longitudinal axis substantially perpendicular to the planar base. Furthermore, the extension is sized and configured to have an interference fit in relation to being received by the mating inner boundary such that the shielding device and article form a unitary assembly.
REFERENCE NUMBERS IN DRAWINGS
- 30 Shielding device
- 31 User
- 32 Fingers of user 31
- 33 Grasping by fingers 32 upon disk 181
- 34 Portion of fingers 32 placed into aperture 145 and void 84
- 35 Article
- 40 Mating inner boundary length of the article 35
- 45 Base
- 46 Generally planar shape of the base 45
- 48 Surface
- 50 First face portion of base 45 or disk 181
- 55 Second face portion of base 45 or disk 181
- 65 Outer periphery portion of the base 45 of disk 181
- 70 Ridge
- 81 Extension
- 82 Proximal end portion of the extension 81
- 83 Distal end portion of the extension 81
- 84 Void of the extension 81
- 86 Axial length dimension of the extension 81
- 88 Chamfer
- 89 Chamfer angle of the chamfer 88
- 90 Axial length of the chamfer 88
- 91 Longitudinal axis of extension 81
- 93 Lengthwise axis of paper towel assembly 200
- 100 Longitudinal axis 90 substantially perpendicular to the planar shape 46 or plane 186
- 115 Lip
- 120 Depression
- 121 Concave depression
- 125 Channel in said first face portion 50
- 126 Annular channel
- 130 Rib
- 145 Aperture
- 146 Margin at aperture 145
- 147 Shoulder at aperture 145
- 181 Disk
- 186 Plane formed by disk 181
- 200 Paper towel roll assembly or paper product roll that includes the core 210 and the paper towel sheets 205
- 202 A primary edge of the paper towel roll 200
- 203 A secondary edge of the paper towel roll 200
- 205 Paper towel sheets roll up
- 206 Outside diameter of the paper towel sheets roll up
- 207 Rotation movement of the paper towel assembly 200 relative to surface 225
- 208 Force movement point to cause rotation of the paper towel assembly upon the surface 225
- 210 Core of paper towel assembly
- 211 Spiral seam of the core 210
- 212 Periphery of the core 210
- 213 Hollow inner volume of the core 210
- 215 Inside diameter of the core 210
- 220 Wall thickness of the core 210
- 221 Spiral failure of the wall thickness 220
- 225 Surface that the paper towel assembly 200 rests upon
- 226 Surface friction area to resist rotation 255 or 256
- 230 Inserting extension 81 into the mating inner boundary 40 or the core 210 diameter 215
- 250 Grasping manually the shielding device 30 by placing the fingers 32 upon the disk 181
- 255 Rotating manually the shielding device 30 in a clock wise direction from the first face portion 50
- 256 Rotating manually the shielding device 30 in a counter clock wise direction from the first face portion 50
- 257 Chord length equal to extension 81 length 86
- 265 Solid
- 270 Liquid
- 300 Inner radius dimension of the extension 81
- 305 Outer radius dimension of the extension 81
- 310 Outer radius dimension of the core 210
- 315 Contact pressure area as between the outer radius 305 and the core 210 inside diameter
- 215 of as termed the “interference fit”
With initial reference to
Next,
Moving ahead,
Continuing,
Broadly the present invention of the shielding device 30 for helping to protect an article 35, with the article 35 having a mating inner boundary length 40, the shielding device 30 includes a base 45 having a generally planar shape 46, the base 40 including first face portion 50 and an opposing second face portion 55, the base 40 further having an outer periphery portion 65 wherein a ridge 70 is disposed in the outer periphery portion 65 being adjacent to the first face portion 50, wherein the second face portion 55 is adjacent to the article 35, see
Referring to
Also as an option of the shielding device 30, an aperture 145 is added that is disposed therethrough the base 45 being positioned about the longitudinal axis 91, wherein the aperture 145 further allows use as a grasp point 34 for a user 31, as best show in
As a more specific embodiment for the shielding device 30 can be used for helping to protect an edge 202 of a paper product roll or more specifically a roll of paper towels 200, the roll 205 having a hollow inner 213 core 210 with a periphery 212. The more specific embodiment for the shielding device 30 includes a disk 181 forming a plane 186, with the disk 181 having a first face portion 50 and an opposing second face portion 55, with the disk 181 further having an outer periphery portion 65 wherein a ridge 70 is disposed in the outer periphery portion 65 being adjacent to the first face portion 50, wherein the second face portion 55 is adjacent to the paper product roll 200, see
The extension proximal end portion 82 projecting from the second face portion 55, wherein the longitudinal axis 91 is substantially perpendicular 100 to the plane 186, the extension distal end portion 83 is sized and configured to have an interference fit 315 of about one and four-tenths (1.4) percent (%) to one and eight tenths (1.8) percent (%) of the periphery 212, see
As an option the more specific embodiment for the shielding device 30, can further comprise a lip 115 disposed in the first face portion 50 inward of the ridge 70 forming a concave depression 121 in the first face portion 50 that is operational to further retain liquid drippings 270 substantially within the concave depression 121 away from the paper product roll 205, see
As a refinement of the interference fit 315 for the more specific embodiment of the shielding device 30 the interference fit 315 is increased to an interference fit 315 of about one and four-tenths (1.4) percent (%) to two and seven tenths (2.7) percent (%) of the periphery 212, requiring that the disk 181 and the extension 81 be rotated clock wise 255 in an amount defined as a chord length 257 on the outer periphery 65 being at least equal to the extension length 86 as viewed from the first face portion 50. When the extension 81 is inserted 230 into the hollow inner 213 core 210, see
In calculating the interference fit as between extension 81 and the core 210 a number of parameters need to be set forth, please reference
Noting that an interference fit is typically where an inner cylindrical part is manufactured to a larger outside diameter that the inside diameter of the cylinder that it is inserted into, hence the term interference, as the two parts will strain or deform each other at their interface, thus forming a permanently stressed condition, wherein consistent contact pressure exists as between the outside diameter of the inner assembled cylinder and the inside diameter of the outer assembled cylinder. The benefits of the interference fit are many, however, being primarily to effectuate two cylinders to be affixed to one another without the need for welding, screws, bolts, adhesives, threads, and the like. Of course the question would be; how do you get the parts together, other than with a hydraulic ram to axially push the cylinders together with brute force (being generally unacceptable due to potential damage to the cylinders), and the answer is typically in the ordinary skill in the art, wherein the cylinders are made of various metals and through the use of thermal expansion and contraction, wherein the outer cylinder is heated to grow and the inner cylinder is cooled to shrink, thus with the combination of the heat expansion and cooling shrinkage, the manufactured interference between outside diameter of the inner cylinder and the inside diameter of the outer cylinder is not only overcome but exceeded by some small amount, say in the thousandth's of an inch to facilitate easy assembly of the two cylinders, and as they both eventually come to an equalized room temperature, the heated cylinder shrinks and the cooled cylinder grows resulting in the desired permanent stress condition at the interference fit interface having contact pressure between the outside diameter of the inner cylinder and the inside diameter of the outer cylinder.
The present invention presents a number of challenges to seeking the benefits of an interference fit as between the extension 81 outer radius 305 and the core 210 inside diameter 215 primarily being due to the materials used for the interference fit being PVC for the extension 81 and the cardboard roll for the core 210, as opposed to the conventional use of two like or dislike metal pieces that make-up the interference fit, wherein the principal characteristics of the modulus of elasticity “E” and poissons ration “u” are known along with the thermal coefficients of expansion “α” for metals. Thus, in the present invention with the materials being PVC and cardboard being so dissimilar required some trial and error testing not only ascertain the values of E, u, and α, but also the parameters of desired contact pressure 315 that are derived from the coefficient of friction “μ” as between the PVC at radius 305 and the cardboard 215, as basically designing an interference fit as between PVC and cardboard is not generally known in the art.
To start, the coefficient of friction “μ” as between the PVC radius 305 and the cardboard 215 had to be determined from experimentation, as generally available information on coefficients of friction between various materials do not include cardboard to PVC, however, many metals, rubber, glass, concrete, and wood are generally known for standard coefficients of friction, however, one must be careful to qualify the coefficient of friction as there are big differences between dynamic and static, wet and dry, and surface finish, so for accuracy, empirical testing may also be done for more commonly mated materials of construction. Thus, an experiment was set up using a flat piece of PVC with the same surface finish as the surface at 305 has and a piece of the core 210 cut and flattened out to form a flat pattern from its normal cylindrical shape. Next a weight was added to the flat PVC piece that equaled 1 pound and 15.75 ounces or 1.981 pounds for the combination of the PVC flat piece and the weight which would equal the normal force or “N”. Thus also assuming that we wanted the static coefficient of friction is a dry-dry condition, the PVC and cardboard were dry and the lateral force “F” would be measure when the PVC just broke free in going from static to dynamic as the force F is applied to the PVC flat piece. The results were that the force F was determined from testing to be 7 ounces or 0.44 pounds. Using the equation that the coefficient of friction “μ” is determined from F divided by N, we end up with a coefficient of friction “μ” as between the PVC radius 305 and the cardboard 215 equaling 0.22 which is considerably less than a typical table value of dry steel on dry steel (static) of 0.8, meaning that more contact pressure will be needed to effectuate this unique interference fit as between PVC radius 305 and cardboard 210.
The next step was to determine the torque required to rotate 207 via force causing torque about longitudinal axis 93 at the paper towel assembly 200 outside diameter 206 as against the friction 226 of the paper towel assembly 200 on the surface 225, i.e. desirably going from static to dynamic, see
Based upon the experimental testing, force 208 was determined to be 0.062 pounds force to move the paper towel assembly 200 from the previously described static state to the dynamic state. Next, the force 208 needs to be proportioned to the force required at radius 305 or at the inside diameter 215, by taking outside paper towel sheets 205 outside diameter 206 divided by inside diameter 215 which equals 5 inches divided by 1.63 inches which equals 3.067 then multiplying this by 0.062 pounds which equals 0.19 pounds force that is at radius 305 or converted into torque by multiplying the 0.19 pounds force by the moment arm 0.0675 feet (being one-half of inside diameter 215) equals 0.013 foot-pounds of torque. Thus to effectuate the required torque to manually rotate 255 the paper towel assembly 200 via manually grasping 250 the shielding device 30, we have to transmit at least 0.19 pounds force at the interference interface to overcome the friction 226 between the paper towel sheets 205 and the surface 225 to rotate 255 the paper towel assembly 200 and shield device 30.
Next, to convert the torque of 0.013 foot-pounds of torque or 0.19 pounds force into a contact pressure at the interference fit 315 wherein we will use the previously determined coefficient of friction being 0.22, thus we will calculate the normal force N given the coefficient of friction μ and the lateral force F, thus we divide the lateral force F which is 0.19 pounds by the coefficient of friction μ being 0.22 which equals 0.86 pounds, thus this is the compressive force that the core 210 must at least exert about the extension 81 radius 305. Now we convert this to a contact pressure we need to calculate the area at the interference fit 315, which is two times the radius 305 times Pi “π” times the axial length 86 of the interference fit 315 along the longitudinal axis 91, note not including the chamfer 88. So the calculation is respectively two times radius 305 being 1.63 inches times 3.14 for π times axial length of 0.5 inches which equals 2.56 square inches being the contact area for the interference fit 315. To convert this into a contact pressure at 315 would equal the total force of 0.86 pounds divided by the contact area of 2.56 square inches which equals 0.34 pounds per square inch minimum contact pressure required at the interference fit 315 to be able to transmit enough torque to rotate 255 the paper towel assembly 200 via manually grasping 230 the shield device 30, while the paper towel assembly 200 is resting upon the surface 225, see in particular
Now that we have the minimum required contact pressure of 0.34 pounds per square inch (PSI) we can determine the minimum interference fit 315 required if we have the modulus of elasticity E and the poissons ratio u for both materials, i.e. the PVC extension 81 and the cardboard core 210. These properties for the PVC are available, however, these properties for the cardboard are a challenge as cardboard as previously discussed is not a typical material that is used in constructing interference fits, further for the assembly issue as previously discussed that requires the thermal coefficients of expansion of both the materials to create the temperature dependent clearance for assembly of the larger outside diameter or radius 305 into the smaller inside diameter 215. Again for PVC thermal coefficients of expansion are available in the art, however, also again these properties for cardboard are not easily available, as also again cardboard is typically not used where thermal considerations are important. Also the construction of cardboard is so variable, as box type cardboard material which is corrugated, does have some strength information as it is a commonly used material, however, is a completely different material for its physical properties of E, u, α, and so on, due to corrugated box cardboard material having a completely different cross sectional inertia (being of a type of monocoque-separated stressed skin construction-like an airplane wing) as compared to a solid sheet type cardboard material, as the present invention core 210 is a cylinder of material that probably most matches a paper note pad backing material wherein the cardboard is about one-thirty second of an inch thick, however, the core 210 cardboard material appears to have a more coarse grain structure than note pad backing which could alter the material structural properties of E, u, and α, being the modulus of elasticity, poissons ratio, and the thermal coefficient of expansion respectively.
Note, there is a giant sized core 210 type material termed a Sonotube being typically one to three feet in diameter with a wall thickness of about one-quarter inch constructed of cardboard in the form of a cylinder used as a concrete pier form, i.e. concrete is poured into the Sonotube and when the concrete is set the Sonotube is removed, however, it appears after some research that the direct material structural properties of the Sonotube cardboard are kept as trade secrets, as Sonotube has a single loading with the concrete and the firms that sell it typically just give application tables of Sonotube overall diameter and axial length, wherein no details are disclosed as to wall thickness determination, exact material construction, bonding, deflection, and the like.
So, as far as the cardboard material goes for the core 210, the aforementioned materials structural properties would only be approximations, wherein experimental testing would have to be done to finalize the interference fit 315, as the calculations for the interference fit 315 are only as accurate as the material structural properties that go into the equation. Thus to start the material structural properties for the PVC i.e. for the extension 81 are for the modulus of elasticity E equal to 420,000 pounds per square inch (PSI), the poissons ratio u is equal to 0.41, and the thermal coefficient of expansion α of 0.000028 inches per inch per degree Fahrenheit. For the cardboard core 210 the only remotely applicable material structural properties are from the cardboard model bridge building projects, that typically load a bridge to failure as an exercise to learn bridge equations and assumptions that go into the equations, although the cardboard that is used for model bridges is a high density type, being probably stronger that the core 210 cardboard. Although in the present invention we are not interested in failing the cardboard into rupture, so additional experimentation will have to be done. The material structural properties from the model bridge building arts are for the modulus of elasticity E for cardboard equals 388,000 pounds per square inch in tension as in the case of the present invention, note that the modulus of elasticity for cardboard in compression is vastly different at being 12,000 pounds per square inch, this is completely different than for a typical metal wherein the modulus of elasticity is equal in tension and compression as long as there is no permanent deformation or yielding which is typically assumed in the interference fit calculation as the outer part is in hoop stress tension and the inner part is in hoop stress compression.
The poissons ratio u for cardboard comes from the paper embossing arts, wherein the poissons ratio is equal to 0.3 assuming that the paper is not strained or has deflection of more than 1 percent % in tension. The thermal coefficient of expansion α comes from assuming that a low density more open fiber wood is close like pine wherein the thermal coefficient of expansion α is equal to 0.000002 inches per inch per degree Fahrenheit being about one fourteenth of the thermal expansion of PVC. Thus, for the material structural properties of cardboard for the core 210 being of E, u, and α, being the modulus of elasticity, poissons ratio, and the thermal coefficient of expansion respectively are only loosely approximating the actual core material structural properties, however, this is what is only available in the art, so the calculation for the interference fit 315 will be done, with experimental testing to determine the actual interference fit 315.
The interference equation is basically the summation of deflections of the inner and outer pieces being the extension 81 and the core 210 wherein the deflections are set to be equal to one another and then using the contact pressure at the interference fit 315 the actual deflection is calculated that maintains the contact pressure used in the equation. Basic assumptions that go into the interference equation are that there is no axial loading on either the extension 81 or the core 210 along the longitudinal axis 90, there are no internal or external pressure effects on either the extension 81 or the core 210, there are no temperature effects after the extension 81 and the core 210 are fit together at the interference fit 315, no centrifugal effects from rotation about the longitudinal axis 91 again after the extension 81 and the core 210 are fit together at the interference fit 315, and finally no strength is assumed from the paper towel sheets 205 on the core 210. The deflection of the outer piece being the core 210 is the inverse of the modulus of elasticity E being 1/388,000 multiplied by the quantity ((the radius 305 being 0.81 squared plus the radius 310 being 0.84 squared) divided by the quantity (the radius 310 being 0.84 squared minus the radius 305 being 0.81 squared) plus the poisson ratio being 0.3) which equals 0.000072 inches squared per pound. The deflection of the inner piece being the radius 305 of the extension 81 is the inverse of the modulus of elasticity E being 1/420,000 multiplied by the quantity ((the radius 300 being 0.75 squared plus the radius 305 being 0.81 squared) divided by the quantity (the radius 305 being 0.81 squared minus the radius 300 being 0.75 squared) minus the poisson ratio being 0.41) which equals 0.00003 inches squared per pound. The 0.000072 inches squared per pound is added to the 0.00003 inches squared per pound equaling 0.000102 inches squared per pound which is then multiplied by the radius 305 being 0.81 inches and then being multiplied by the contact pressure at the interference fit 315 being 0.34 pounds per square inch that comes out to equaling 0.000028 inches of interference fit required according to the calculation and the problematic assumptions for the cardboard material structural properties.
Thus now that we have the minimum interference fit as between the radius 305 and the diameter 215 of 0.000028 inches, see
Next to the core 210 diameter 215, as this is fabricated from adhesive and rolled cardboard stock on a steel cylinder, the core 210 is typically called a spiral paper tube, with a standard paper towel 200 having the core 210 at having the diameter 215 at 1.62 inches and the wall thickness 220 at about 0.030 inches that has a tolerance of about 0.010 inches on the diameter, thus we now need to add this tolerance of 0.010 inches to 0.013028 inches which equals 0.023028 inches, which equates to about a one and four-tenths (1.4) percent strain or stretch of the circumference of the core 210. Note that a higher interference fit 315 is acceptable up to the point of causing excessive stress in the inner or outer pieces, being the extension 81 or the core 210 respectively, wherein in the present invention the failure from over stress will be in the core 210, in addition having a higher interference fit 315 would allow a higher torque to be transmitted from the shield device 30 to the core 210 of the paper towel assembly 200, which would be acceptable. In practicality, an interference fit 315 of about 0.025 inches would cover the required minimum interference fit accounting for the manufacturing tolerances of both the extension 81 radius and the core 210 diameter 215 with a safety margin of 0.002 for the actual minimum case interference fit 315.
Experimental testing showed that an interference fit of over 0.030 inches started to produce a spiral failure 221 in the wall of the core 210 as shown in
It is suspected that this is because of the spiral construction reduces the diameter 215 when rotational 256 torsion in the core 210 tends to tighten or slightly reduce the diameter 215 somewhat like a helically wound spring that is rotated on one end and static on the other end, wherein in one rotational direction the spring will reduce in diameter and in the opposite rotational direction the spring will increase in diameter, thus on the present invention rotational 255 torsion in the core 210 tends to loosen or slightly increase the diameter 215. The practical benefit of this is that while inserting the extension 81 into diameter 215 if the shielding device 30 is rotated 255 a higher interference fit can be accommodated, see
In so far as the use of heat and cooling to take advantage of the thermal expansion contraction respectively to facilitate ease of assembly of the extension 81 into the core 210 diameter 215, the use of a chamfer 88 is employed, see
Referring on particular to
Continuing to reference
Continuing to the eighth step, with the user 31 holding stationary the paper towel roll assembly 200, via the placing of the user's 31 fingers 32 to be in contact with the disk 181, see again
Claims
1. A shielding device for helping to protect an article, the article having a mating inner boundary length, wherein said mating inner boundary is constructed of a spiral helix seamed cardboard, comprising:
- (a) a base having a generally planar shape, said base including first face portion and an opposing second face portion, said base further having an outer periphery portion wherein a ridge is disposed in said outer periphery portion being adjacent to said first face portion, wherein said second face portion is adjacent to the article; and
- (b) an extension having a proximal end portion and a distal end portion with a longitudinal axis disposed therebetween, said extension proximal end portion projecting from said second face portion, where said longitudinal axis is substantially perpendicular to said planar shape, said extension distal end portion is sized and configured to have an interference fit range of about one and four-tenths (1.4) percent (%) to one and eight tenths (1.8) percent (%) of the boundary length, wherein operationally said base and extension form a unitary assembly with the article, with the article further protected from liquid drippings via said base and ridge.
2. A shielding device according to claim 1, further comprising a lip disposed in said first face portion inward of said ridge forming a depression in said first face portion that is operational to further retain liquid drippings substantially within said depression and away from the article.
3. A shielding device according to claim 2, further comprising a rib adjacent to said outer periphery portion that is oppositely disposed from said ridge, wherein said rib further protects the article from the liquid drippings.
4. A shielding device according to claim 1, further comprising an aperture disposed therethrough said base being positioned about said longitudinal axis, wherein said aperture further allows use as a grasp point for a user.
5. A shielding device according to claim 4 further comprising a shoulder positioned adjacent to a margin of said aperture, wherein a channel is formed from said shoulder, said first face portion, and said ridge, wherein said channel further protects the article from the liquid drippings with the use of said aperture.
6. A shielding device for helping to protect an edge of a paper product roll, the roll having a hollow inner core with a periphery, wherein said hollow inner core is constructed of a spiral helix seamed cardboard, comprising:
- (a) a disk forming a plane, said disk having a first face portion and an opposing second face portion, said disk further having an outer periphery portion wherein a ridge is disposed in said outer periphery portion being adjacent to said first face portion, wherein said second face portion is adjacent to the paper product roll; and
- (b) an extension having a proximal end portion and a distal end portion forming a length therebetween, with a longitudinal axis disposed along said length, said extension proximal end portion projecting from said second face portion, wherein said longitudinal axis is substantially perpendicular to said plane, said extension distal end portion is sized and configured to have an interference fit range of about one and four-tenths (1.4) percent (%) to one and eight tenths (1.8) percent (%) of the periphery, when said extension is inserted into the hollow inner core, wherein operationally said disk and said extension communicate rotational torque into the core and paper product roll, with the paper product roll further protected from liquid drippings via said disk and ridge.
7. A shielding device according to claim 6, further comprising a lip disposed in said first face portion inward of said ridge forming a concave depression in said first face portion that is operational to further retain liquid drippings substantially within said concave depression away from the paper product roll.
8. A shielding device according to claim 7, further comprising a rib adjacent to said outer periphery portion that is oppositely disposed from said ridge, wherein said rib further protects the paper product roll from the liquid drippings.
9. A shielding device according to claim 6, further comprising an aperture disposed therethrough said disk being positioned about said longitudinal axis, wherein said aperture further allows use as a grasp point for a user.
10. A shielding device according to claim 9, wherein said extension has a void disposed therethrough along said longitudinal axis, wherein said void and said aperture are in communication.
11. A shielding device according to claim 10 further comprising a shoulder positioned adjacent to a margin of said aperture, wherein an annular channel is formed from said shoulder, said first face portion, and said ridge, wherein said annular channel further protects the paper product roll from the liquid drippings with the use of said aperture.
12. A shielding device according to claim 6 wherein said interference fit range is increased to an interference fit of about one and four-tenths (1.4) percent (%) to two and seven tenths (2.7) percent (%) of the periphery, requiring that said disk and said extension be rotated clock wise in an amount defined as a chord length on said outer periphery being at least equal to said extension length as viewed from said first face portion, when said extension is inserted into the hollow inner core, wherein operationally to further allow said disk and said extension to communicate additional rotational torque into the core and paper product roll, with the paper product roll further protected from liquid drippings via said disk and ridge.
13. A method of helping to protect a primary edge of a paper towel roll, the paper towel roll having a lengthwise axis and a hollow inner core with a periphery, wherein said hollow inner core is constructed of a spiral helix seamed cardboard, to be able to protect the primary edge of the paper towel roll from becoming wet or soiled during consumption of paper towels by a user, comprising the steps of:
- (a) providing a shielding device comprising of a disk forming a plane, said disk having a first face portion and an opposing second face portion, said disk further having an outer periphery portion wherein a ridge is disposed in said outer periphery portion being adjacent to said first face portion, wherein said second face portion is adjacent to the paper product roll, said disk further comprising an aperture disposed therethrough, wherein said aperture further allows use as a grasp point for a user, said shielding device also including an extension having a proximal end portion and a distal end portion forming a length therebetween, with a longitudinal axis disposed along said length, said extension proximal end portion projecting from said second face portion, and said distal end portion having a chamfer, wherein said longitudinal axis is substantially perpendicular to said plane, said extension also having a void disposed therethrough along said longitudinal axis, wherein said void and said aperture are in communication, said extension distal end portion is sized and configured to have an interference fit range of about one and four-tenths (1.4) percent (%) to two and seven tenths (2.7) percent (%) of the periphery, when said extension is inserted into the hollow inner core, requiring that said disk and said extension be rotated clock wise in an amount defined as a chord length on said outer periphery being at least equal to said extension length as viewed from said first face portion, wherein operationally to further allow said disk and said extension to communicate additional rotational torque into the core and paper product roll, with the paper product roll further protected from liquid drippings via said disk and ridge;
- (b) grasping manually the paper towel roll and positioning the lengthwise axis to be substantially perpendicular to a surface wherein a secondary edge of the paper towel roll is adjacent to the surface;
- (c) grasping manually said shielding device and aligning said longitudinal axis to be co-axial with the lengthwise axis, further with said extension positioned adjacent to the hollow inner core of the paper towel roll;
- (d) positioning said chamfer to contact and slightly insert into the hollow inner core of the paper towel roll;
- (e) inserting and rotating simultaneously said shielding device such that said shielding device be rotated clock wise in an amount defined as said chord length on said outer periphery being at least equal to said extension length as viewed from said first face portion, when said extension is inserted into the hollow inner core, wherein operationally to further allow said shielding device to communicate additional rotational torque into the hollow inner core and paper towel roll;
- (e) contacting manually said shielding device with one hand by placing a user's fingers upon said disk;
- (f) rotating manually said shielding device such that the paper towel roll unrolls to provide a sheet, wherein the primary edge of a paper towel roll is protected from contact with the users fingers;
- (g) holding stationary the paper towel roll, via said placing the user's fingers to be in contact with said disk; and
- (h) tearing the required paper towels from the paper towel roll manually.
14. A method of protecting a primary edge of a paper towel roll from becoming wet or soiled during distribution according to claim 13 wherein said step of contacting manually said shielding device further includes placing a portion of the users fingers into said aperture and said void to facilitate an improved grasping of said shielding device by the user.
Type: Application
Filed: Jun 6, 2010
Publication Date: Dec 8, 2011
Inventor: Martin Jay Peters (Denver, CO)
Application Number: 12/794,769
International Classification: B65H 23/00 (20060101);