Patent Application
20190316999
This disclosure relates generally to enabling roll-to-roll additive manufacturing methods and, more particularly, to systems and methods for measuring parameters associated with the wound roll.
Roll-to-roll (R2R) additive manufacturing methods pervade many automated process industries today. R2R manufacturing methods require one or more substrates known as webs to be transported continuously through processes which add value to a web and ultimately result in a commercial product. The webs are very long compared to their width and thickness dimensions and the only means by which these webs can be stored with minimal damage while they await further processing is by winding them into rolls. Storage is a necessity, as each web process requires a unique web velocity. Therefore, webs must be wound into rolls at the end of a process. The rolls are then transported to the next web process machine where they will be unwound and processed again. Webs can be unwound and rewound many times for subsequent processing prior to conversion to a final product. The web value increases after each process, thus damage loss due to winding becomes more costly based on the number of manufacturing processes that have been completed.
Numerous instruments have been previously developed or adapted that attempt to measure roll hardness. The majority of these instruments can be described as dynamic hardness testers. Some of these testers can be described as deceleration devices where a wound roll is struck and the deceleration of the striker is measured. U.S. Pat. Nos. 3,425,267 and 5,079,728A are examples of these technologies. Other testers can be described as coefficient of restitution devices where a projectile is launched towards the roll surface and the projectile velocity is compared before and after impact. U.S. Pat. Nos. 4,034,603 and 5,176,026 are examples of that technology.
Prior art attempts to determine static and dynamic hardness testers might have one or more of the following limitations:
Before proceeding to a description of the present invention, however, it should be noted and remembered that the description of the invention which follows, together with the accompanying drawings, should not be construed as limiting the invention to the examples (or embodiments) shown and described. This is so because those skilled in the art to which the invention pertains will be able to devise other forms of this invention within the ambit of the appended claims.
According to a first embodiment, the teachings herein make it possible for a user to determine the radial stiffness of the outer surface of a winding or wound roll, and, when coupled with a winding/contact model, results in a virtual instrument that can allow the user to explore the residual stresses due to winding in roll-to-roll manufacturing process machines. Additionally, various embodiments will allow the user to predict winding defects and hence roll quality based upon the known residual stresses. Wound roll models require the input of a radial modulus of elasticity which is state dependent on interlayer pressure.
The hardware of an embodiment can be used to determine this radial modulus and serves to enable the user to use winding/contact models and, with measurements made during or after winding, enable the user to estimate the winding residual stresses.
In more particular, an embodiment of the apparatus is designed to measure, record, compute, or otherwise determine radial stiffness. The major components include but are not limited to devices that measure applied force, indenter displacement, an indenter of known diameter, a housing to contain and constrain the afore described components, and component(s) or systems to record, transmit, perform calculations, or otherwise perform operations on the measured test data.
Various embodiments can be used to create a profile of radial stiffness with respect to winding radius and across the roll width. Additionally, disclosed herein is an apparatus for evaluating the true winding stress and the actual winding residual stresses in the wound roll. Further, an embodiment is disclosed that provides a method for improving the quality of wound rolls by avoidance of defects that can be predicted with knowledge of winding residual stresses.
Additionally, some variations can be used iteratively in connection with a winding motel to predict defects inside and on the surface of the roll. This combination of a radial stiffness tester and the methods disclosed herein provide a method of improving wound roll quality not available in any other form.
According to another embodiment there is provided an apparatus for measuring a radial stiffness of a wound roll, comprising: a housing; an indenter, said indenter having a first end external to said housing and a second end internal to said housing; a force sensor within said housing and in mechanical communication with said indenter, said force sensor at least for measuring a force when said force is applied to said housing to urge said indenter against the wound roll; a displacement sensor within said housing, said displacement sensor at least for measuring a displacement of said indenter when said force is applied to said housing to urge said indenter against the wound roll; and, a CPU in electrical communication with said force sensor and said displacement sensor, said CPU at least for reading said force from said force detector and said displacement from said displacement sensor.
According to still another embodiment there is provided an apparatus for measuring a radial stiffness of an object, comprising: an indenter; a pressure contact area in mechanical communication with said indenter; a force sensor in mechanical communication with said indenter, said force sensor at least for measuring a force when said force is applied to said pressure contact area to urge said indenter against the object; a displacement sensor, said displacement sensor at least for measuring a displacement of said indenter when said force is applied to said pressure contact area to urge said indenter against the object; and, a CPU in electrical communication with said force sensor and said displacement sensor, said CPU at least for continuously reading said force from said force detector and said displacement from said displacement sensor as said force is applied.
According to an additional embodiment, there is provided a method of identifying defects in a wound roll of material, comprising the steps of: accessing values of Tw, h, Rcore, Rout, E□, and Er for said material, where, Tw is a winding tension of said wound roll, h is a thickness of caliper of the material, Rcore is an outside radius of a core of said wound roll, Rout is an inner radius of the wound roll, E□ is modulus of the material in the machine direction, Er is the modulus of the web in the radial direction, and Ec is a modulus of a core on which the material is wound; using a winding model to obtain a relationship between Er and r, where r is a radial distance from a center of said wound roll; using at least Er and one or more of Tw, h, Rcore, Rout, E□, and Er to calculate a contact model, thereby producing one or more values of Kcode, where Kcode is a slope of relationship between force and displacement from said contact model; obtaining a plurality of different force and displacement values at a single point on said wound roll; using said plurality of force and displacement values to obtain one or more values of Ktest at said single point on said wound roll; comparing said one or more value of Kcode with said one or more values of Ktest; if said one or more Kcode values are approximately equal to said one or more Ktest values, conclude that a winding tension is correct; and, if said one or more Kcode values is significantly different from said one or more Ktest values, conclude that said winding stress is not correct; and, if said one or more Kcode values is significantly different from said one or more Ktest values, modifying Tw and performing the above steps again with Tw replaced by said modified Tw until Ktest is not significantly different from Kcode.
The foregoing has outlined in broad teems some of the more important features of the invention disclosed herein so that the detailed description that follows may be more clearly understood, and so that the contribution of the inventors to the art may be better appreciated. The invention is not to be limited in its application to the details of the construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. Rather, the invention is capable of other embodiments and of being practiced and carried out in various other ways not specifically enumerated herein. Finally, it should be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting, unless the specification specifically so limits the invention.
These and further aspects of the invention are described in detail in the following examples and accompanying drawings.
While this invention is susceptible of embodiment in many different forms, there is shown in the drawings, and will herein be described hereinafter in detail, some specific embodiments of the instant invention. It should be understood, however, that the present disclosure is to be considered an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments or algorithms so described.
The current development eliminates various shortcomings of certain prior art approaches instruments by making a measurement of the static or steady state radial stiffness on the outer surface of the wound roll. Radial stiffness is determined by the relationship between an applied force on a material and the resulting deformations. The radial stiffness, in most cases, will increase as the user increases the applied force. As the applied force is increased, the contract pressure and hence the state dependent radial and shear modulus will increase. The increase in modulus with pressure is responsible for the increase of radial stiffness with the applied force. There may be cases, due to material properties or the small magnitude of the applied force that the radial stiffness may be nearly constant. These stiffness measurements start at zero contact pressure and continue up to maximum contact pressures defined by the user.
For purposes of the disclosure contained herein, these symbols are defined as follows:
Various aspects of a first embodiment are shown in
In the embodiment of
The force measuring device 115 is in mechanical communication with an indenter 140 which is designed to come into contact with the material that is to be tested 110 as is more fully described below.
Within the device 100, there is a sensor for measuring displacement 120, which might be a DCDT (Direct Current Differential Transformer) or something similar. Those of ordinary skill in the art will readily be able to devise alternatives. Additionally provided in this embodiment are a displacement stop plate 125, a return spring 135, and a spring retainer 130.
Not pictured is a communications module (e.g., Bluetooth®, WiFi, etc.) or communications interface (e.g., a serial port, a USB port, etc.) which can be used to communicate force and displacement readings to an external data recorder or computer. Alternatively, instead of or in addition to the foregoing, a CPU processing unit might be resident on the device and in electrical communication with the force measuring device 115, and the displacement sensor 120. The CPU could have some amount of local storage and the computational ability to read measurements from the force measuring device 115 and displacement sensor 120. It further could optionally be programmed to calculate and display radial stiffness measurements directly to a user as the device 100 is used, preferably via a display device that is part of, or in communication with, the device 100. The CPU will likely be internal to the housing of the device 100 but it could also be external is that were desired.
The CPU might be any sort of active device which is designed to execute computer instructions according to its programming, including, for example, a conventional microcontroller or microprocessor. More generally, the term “CPU” as used herein minimally requires a device that is programmable in some sense and is capable of recognizing signals from a force sensor and displacement sensor. Of course, these sorts of modest requirements may be satisfied by any number of programmable logic devices (“PLDs”). The CPU might, alternatively or additionally, be embedded in another device (e.g., in a Bluetooth chip, or WiFi module, etc.). Thus, for purposes of the instant disclosure the terms “processor,” “microprocessor” and “CPU” should be interpreted to take the broadest possible meaning, and such meaning is intended to include any PLD or other programmable device of the general sort described above. The term CPU should also be interpreted to include multiple CPUs if, for example, one CPU reads the displacement sensor and another reads the force sensor.
An alternative embodiment is shown in
In operation, the device 100 is pressed against the material that is to be measured which would typically be either wound onto a roll or assembled into a stack of material (e.g., the stack 710 of
After a test of material is concluded and pressure is removed therefrom, the indenter 140 may be (but is not required to be) returned to its original position by a return spring 135. Force measuring components 115 may include but not limited to load cells, force meters, spring scales, optical means or any other embodiment of a force measuring component. Displacement measuring components 120 may include but are not limited to DCDT (direct current displacement transducer), LVDT (linear variable differential transformer), linear or rotary potentiometers, optical devices, capacitance devices or any other embodiment of a displacement measuring device.
Given the force displacement pairs calculated during the previous test, the CPU in the device 100 itself, or a computer 600 external to the device 100, will prepare a force versus deformation curve (e.g., a curve of the sort illustrated in
This device can be embodied in handheld form or incorporated into a mechanical system that can make measurements of the surface stiffness of a stationary wound roll or a rotating roll for measurement during winding. As described previously, if plotted the measurements will yield a force (F) versus deformation (u) curve of the form shown in
Winding models output the internal pressures and stresses within a wound roll as a function of roll radius. The inputs typically include the tension in the outer layer of a winding roll, the web modulus of elasticity in the tangential and radial directions, web thickness, inner and outer radius of the wound roll and the core stiffness. The radial modulus is state dependent on pressure.
An additional aspect of various embodiments is that the radial modulus can be measured by using devices of the sort generally illustrated in
(1)
where P=pressure (units of load per unit area), K1=a material constant (units of load per unit area), K2=a material constant (dimensionless), and εr=strain (dimensionless). The derivative of the pressure (P) with respect to the normal or radial strain (εt) establishes the radial modulus:
where K1 and K2 are determined by testing stacks of web layers in compression. The measured forces from the device shown in
A least square curve fit method can then be used to fit expression (1) to the test data and produce the empirical values of K1 and K2. Expression (1) works reasonably well for many web materials but does not necessarily work well for all webs. Those of ordinary skill in the art will readily be able to devise alternative functional forms that might be fit to such data. It has been shown that in some instances the modulus is state dependent on pressure through a polynomial expression. However, one aspect of the disclosure herein is that the device can be used to establish the radial modulus regardless of the expression chosen to characterize the radial modulus.
Once a winding model has been executed a contact model can be developed. The winding model output includes the pressures, stresses in each layer, and the state dependent radial modulus as a function of wound roll radius. This information is required by the contact model. This model simulates the contact between the devices of
If the inputs to the winding model are accurately known, the measured force versus deformation curve from the device of
As an example, a polyester web 0.002″ thick, has the properties shown in Table 1 below:
Based on the total web tension and average web thickness in the previous example, it is estimated the winding tension stress (Tw) is 500 psi. Inner and outer wound roll radius, web modulus in the r, θ and z directions, Poisson's ratio and the core stiffness are given as inputs to the winding model. Examples of winding models suitable for use with various embodiments may be found in, among others, Hakiel, Z., 1987, “Nonlinear Model for Wound Roll Stresses,” Tappi J., 70(5), pp. 113-117, or Mollamahmutoglu, C. and Good, J. K. “Analysis of Large Deformation Wound Roll Models,”, ASME Journal of Applied Mechanics, V80, July 2013, pp. 041016-1-11, the disclosures of which are incorporated herein by reference as if fully set out at this point. Using a winding model, the wound roll pressures, tangential and axial stresses can be computed as shown in
Next, a contact model is calculated. The contact model is an nonlinear finite element model. This model is setup with the same inner and outer radius as the winding model, the width should be sufficient such that the vertical u deformations approach zero at the right boundary. The model is restrained at the lower surface by a constraint that simulates the stiffness of the core. At the beginning of execution each finite element has a radial modulus set as a function of radius per the computations shown in
The stylus, in this example ⅜″ in diameter, is impinged in increasing deformations (u) in the r direction. This will induce local pressures which will result in further increase in the radial modulus. At the end of each incremental deformation the average pressure in each finite element is computed and used to increase the radial modulus per the expression in Table 1 prior to the next increment of stylus deformation. Using this method the radial force versus penetration curve for the Tw=500 psi case was produced in
The device shown in
In this example, a match between test and model results is produced when the winding tension stress (Tw) approaches 700 psi, also shown in
Turning next to
Preferably the quantities K1 and K2 will have been previously determined using an embodiment via a “stack test” of the sort explained previously using equations (1) and (2) above as described above.
From these quantities, a winding model for the subject material 510 can be calculated according to methods well known to those of ordinary skill in the art including, for example, the methods of Hakiel or Mollamahmutoglu, identified above. That computation will produce data 515 of the general type shown in
Next, the data corresponding to Ktest and Kcode will be compared. That is, the radial stiffness measured by an embodiment (Ktest) is compared with a radial stiffness predicted by a combination of winding and contact models (Kcode). As is indicated by decision item 520, when Ktest is approximately equal to Kcode, the residual stresses predicted by the winding model are likely correct and those stresses can be used to predict defects inside and on the surface of the roll.
When Ktest is different from Kcode, the winding tension, Tw, needs to be iterated until the two quantities are at least approximately equal. Whatever residual stresses are output by the winding code at that point can be used to predict defects and improve roll quality. The percentage difference between Ktest and Kcode that will indicate a need to adjust the winding tension will vary depending on the situation and is intended to be user selectable. It may be that some amount of trial and error will be necessary to establish what an appropriate value would be for a particular scenario. That being said, for purposes of the instant disclosure conditions when Ktest and Kcode are different enough to merit modifying Tw will be referred to as a “significant” different or “significantly” different. Alternatively, if Ktest and Kcode are not approximately equal (as “approximately” is defined herein), that would also be an instance where they are significantly different.
Turning next to
The displacement ring 940 rests upon the undisturbed face of the material to be measured and is free to translate in the housing of the unit 900 in the axial direction of the indenter 920. The displacement ring 940 is held against the material, and returned to its original position after the test, by spring 980. The relative movement of the displacement ring 940 to that of the indenter 920 is measured by displacement transducer 955. Overload protection of the load transducer 930 may be realized by adjusting the spacing between the load transducer 930 and the housing of the device 900.
In this embodiment, the load is continually measured by a load measuring device such as transducer 930 which transmits or otherwise conveys its measured value to the CPU (not shown). The displacement is measured by the displacement transducer 950 which transmits or otherwise conveys its measured value to the CPU. The CPU processes the load and displacement values to produce a curve similar to that of
The foregoing are just examples of the many forms that the instant invention might take. For instance, in this recent embodiment the displacement transducer is an optical LED emitter detector pair that is capable or measuring distance. There are numerous load and displacement transducers that could be used and more are being developed every day. Also, some embodiments may not use a displacement ring 940 and, instead, might sense the displacement solely by optical (or other non-contact) means.
In brief, the combination of radial stiffness as measured by embodiments disclosed herein combined with the example approach of
Disclosed herein are embodiments of a test instrument and method for evaluating the quality of a wound roll which will work on all wound web materials. The invention can be further augmented by coupling the output of the instrument with winding and contact models that are used to determine the true winding tensile stress and the actual residual winding stresses that can then be used to estimate roll defects and hence quality.
It is to be understood that the terms “including”, “comprising”, “consisting” and grammatical variants thereof do not preclude the addition of one or more components, features, steps, or integers or groups thereof and that the terms are to be construed as specifying components, features, steps or integers.
If the specification or claims refer to “an additional” element, that does not preclude there being more than one of the additional element.
It is to be understood that where the claims or specification refer to “a” or “an” element, such reference is not be construed that there is only one of that element.
It is to be understood that where the specification states that a component, feature, structure, or characteristic “may”, “might”, “can” or “could” be included, that particular component, feature, structure, or characteristic is not required to be included.
Where applicable, although state diagrams, flow diagrams or both may be used to describe embodiments, the invention is not limited to those diagrams or to the corresponding descriptions. For example, flow need not move through each illustrated box or state, or in exactly the same order as illustrated and described.
Methods of the present invention may be implemented by performing or completing manually, automatically, or a combination thereof, selected steps or tasks.
The term “method” may refer to manners, means, techniques and procedures for accomplishing a given task including, but not limited to, those manners, means, techniques and procedures either known to, or readily developed from known manners, means, techniques and procedures by practitioners of the art to which the invention belongs.
For purposes of the instant disclosure, the term “at least” followed by a number is used herein to denote the start of a range beginning with that number (which may be a ranger having an upper limit or no upper limit, depending on the variable being defined). For example, “at least 1” means 1 or more than 1. The term “at most” followed by a number is used herein to denote the end of a range ending with that number (which may be a range having 1 or 0 as its lower limit, or a range having no lower limit, depending upon the variable being defined). For example, “at most 4” means 4 or less than 4, and “at most 40%” means 40% or less than 40%. Terms of approximation (e.g., “about”, “substantially”, “approximately”, etc.) should be interpreted according to their ordinary and customary meanings as used in the associated art unless indicated otherwise. Absent a specific definition and absent ordinary and customary usage in the associated art, such terms should be interpreted to be ±10% of the base value.
When, in this document, a range is given as “(a first number) to (a second number)” or “(a first number)−(a second number)”, this means a range whose lower limit is the first number and whose upper limit is the second number. For example, 25 to 100 should be interpreted to mean a range whose lower limit is 25 and whose upper limit is 100. Additionally, it should be noted that where a range is given, every possible subrange or interval within that range is also specifically intended unless the context indicates to the contrary. For example, if the specification indicates a range of 25 to 100 such range is also intended to include subranges such as 26-100, 27-100, etc., 25-99, 25-98, etc., as well as any other possible combination of lower and upper values within the stated range, e.g., 33-47, 60-97, 41-45, 28-96, etc. Note that integer range values have been used in this paragraph for purposes of illustration only and decimal and fractional values (e.g., 46.7-91.3) should also be understood to be intended as possible subrange endpoints unless specifically excluded.
It should be noted that where reference is made herein to a method comprising two or more defined steps, the defined steps can be carried out in any order or simultaneously (except where context excludes that possibility), and the method can also include one or more other steps which are carried out before any of the defined steps, between two of the defined steps, or after all of the defined steps (except where context excludes that possibility).
Further, it should be noted that terms of approximation (e.g., “about”, “substantially”, “approximately”, etc.) are to be interpreted according to their ordinary and customary meanings as used in the associated art unless indicated otherwise herein. Absent a specific definition within this disclosure, and absent ordinary and customary usage in the associated art, such terms should be interpreted to be plus or minus 10% of the base value.
Still further, additional aspects of the instant invention may be found in one or more appendices attached hereto and/or filed herewith, the disclosures of which are incorporated herein by reference as if fully set out at this point.
Thus, the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned above as well as those inherent therein. While the inventive device has been described and illustrated herein by reference to certain preferred embodiments in relation to the drawings attached thereto, various changes and further modifications, apart from those shown or suggested herein, may be made therein by those of ordinary skill in the art, without departing from the spirit of the inventive concept the scope of which is to be determined by the following claims.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/344,091 filed on Jun. 1, 2016, and incorporates said provisional application by reference into this document as if fully set out at this point.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2017/035506 | 6/1/2017 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62344091 | Jun 2016 | US |
