Web-tensioning apparatus

Description

TECHNICAL FIELD

[0001] The present disclosure generally relates to apparatuses for adjusting web tension and more particularly to apparatuses for evenly distributing web tension at multiple locations having varying degrees of bagginess across the web.BACKGROUND

[0002] Many products are manufactured in a continuous web format in order to realize benefits from the processing efficiencies and capabilities that can be achieved with such an approach. Certain manufacturing processes (e.g. fluid bearing dies) function based on an evenly distributed tension in the web. Consequently, if webs have one or more baggy lanes, i.e., areas where one section of the web is longer than an adjacent section of web, it can create an uneven tension distribution at those locations, which can then directly cause defects in the final product.

[0003] Apparatuses for equalizing the tension of webs are known in the art. For example, U.S. Pat. No 2,696,192 (Birchler et al.) discloses an apparatus for equalizing web tension that includes a plurality of adjustable springs and associated "shoes" that press against the web and U.S. Pub. No. 2004 / 0129818 (Sugawara et al.) describes a magnetic tape tension controller including tension-detecting and tension-adjusting units configured to contact a surface of the magnetic tape to facilitate adjustment of pushing forces. Another device for equalizing tension across a web is known from US 5 971 313. This document discloses a device comprising finger elements made from low friction and high wear material of UHMW-PE and being controlled by a pressurized bladder.SUMMARY

[0004] The present disclosure is directed to an apparatus that self-adjusts a plurality of actuators positioned to evenly tension baggy webs. The apparatus comprises a transverse series of actuators, where each actuator is controlled pneumatically and self-adjusts to provide uniform tension across the width of a web.

[0005] The term "web" is used herein to describe thin materials which are manufactured and / or processed in continuous, flexible strip form. Webs can include, for example, plastics, papers, textiles, metals, and composites of such materials.

[0006] Features and advantages of the present disclosure will be further understood upon consideration of the detailed description as well as the appended claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 is a general configuration drawing of a web-handling system including a web-tensioning apparatus of the present disclosure. FIG. 2 is a perspective view of an embodiment of a web-tensioning apparatus of the present disclosure. FIG. 3 is a cross section view of the web-tensioning apparatus of FIG. 2. FIG. 4 is a cross section view of a portion of the piston assembly of the web-tensioning apparatus of FIG. 3.

[0008] Repeated use of reference characters in the specification and drawings is intended to represent the same or analogous features or elements of the disclosure. The figures may not be drawn to scale.DETAILED DESCRIPTION

[0009] The present disclosure provides apparatuses and methods for evenly tension webs having varying degrees and locations of bagginess. Such even tension of the web may allow tension-dependent processes such as, for example, web coating and lamination, to be performed with reduced waste and increased throughput and using substrates with which such processes were not previously possible.

[0010] FIG. 1 shows one embodiment of a web-handling system 50 including a web-tensioning apparatus 10 of the present disclosure. The web-handling system 50 may be suitable for various web handling applications, such as, for example, general web transport, web lamination processes, and web coating processes involving both planar and nonplanar webs. Web-handling systems contemplated by the present disclosure generally include frame elements 42, 43, 45 configured to support a plurality of rollers (also referred to herein as "idlers") 44, a tension measurement device 46, and the web-tensioning apparatus 10. During manufacturing processes, the web 5 is advanced from a supply roll (not shown) around the rollers 44 that guide the web 5 over the web-tensioning apparatus 10 and tension measurement device 46 to a take-up roll (not shown).

[0011] The web-tensioning apparatus 10 consists generally of an array of hollow, ultra-high molecular weight polyethylene ("UHMWPE") components, referred to herein as "web contact pads," machined with a 3.5-inch (88,9 mm) radius on the external-facing side. In some preferred embodiments, the starting material for the web contact pads is a UHMWPE sheet (obtained under the trade designation "GENPORE" Porous Plastic Sheet from General Polymeric Corporation, Reading, PA). The web contact pads are affixed to an actuator (obtained under the trade designation "AIRPEL" Piston-Cylinder Set Model No. 2KS160-1.0CP from Airpot Corp., Norwalk, CT, USA), which has a 7 / 16" diameter hole drilled through the center of the actuator head to provide an actuator assembly. Opposite the sintered plastic components, through the actuator, is a gas manifold. This manifold may have, for example, two connections, one a ¼" NPT quick disconnect fitting and the other a ¾" NPT barded fitting such that it could be supplied by a blower or high-pressure gas (e.g., air) line. This design allows for gas to flow into the manifold, through the actuator, and through the sintered plastic web contact pads.

[0012] FIG. 2 shows one embodiment of the web-tensioning apparatus 10 of the present disclosure. Referring to FIG. 2, the web-tensioning apparatus 10 includes a gas distribution manifold 11 having at least one of a first gas intake 12 and a second gas intake 13. In some embodiments, the first gas intake 12 may operate at a lower gas pressure than the second gas intake 13. Adjacent to the gas distribution manifold 11 is a piston holder 14 configured to support a plurality of piston assemblies 15 (not shown; see FIGs. 3 and 4). The piston holder 14 is adjacent and attached to a proximal machined connector 16 and distal edge guards 17. The proximal machined connector 16 is secured by a plurality of connectors 18 to a support plate 19 adjacent to a plurality of web contact pad assemblies, i.e., the combination of a piston assembly 15 and a web contact pad 20.

[0013] FIG. 3 shows a cross section view of the web-tensioning apparatus 10 of FIG. 2. Referring to FIG. 3, the web contact pad 20 includes a top surface wall 20a, a side wall 20b, and an interior surface wall 20c surrounding a cavity 40. Typically, the thickness of the side wall 20b is greater than the distance between the top surface wall 20a and the interior surface wall 20c. The vertical arrow shows the direction of pressurized gas flow through the first gas intake 12 to the piston assembly 15 and into the contact pad assembly 20. During operation, the piston assemblies 15 and their associated web contact pads 20 independently move up and down to accommodate variations in web tension as the web 5 passes over the web contact pad 20 top surface 20a, thus evenly tensioning webs having varying degrees and locations of bagginess.

[0014] FIG. 4 shows a cross section view of a portion of the piston assembly 15 of the web-tensioning apparatus of FIG. 3, detailing the arrangement of gaskets 36, spacers 26, the piston shaft 30, the piston head 22, retaining ring 32, and an optional cylinder wall 24.

[0015] Objects and advantages of this disclosure are further illustrated by the following nonlimiting examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this invention which is defined by the appended claims.EXAMPLES

[0016] Unless otherwise noted or readily apparent from the context, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight.Materials

[0017] DescriptionWeb 11.97 mil (50 micron) thick, biaxially oriented polyethylene terephthalate ("PET") film made by 3M Company, St. Paul, MN, USA. The film was altered to create a baggy lane with known bagginess of approximately 1% by inserting 1-foot long brass shims every 100 feet of web in a lane, and then heating the wound roll to 170 degrees Fahrenheit for 12 hoursData Logger8 channel universal input screen data logger. Obtained under the trade designation OMEGA OM-DAQXL from Omega Engineering, Inc., Norwalk, CT, USALoad CellsThree 10 lbf (44.5 N) load cells to measure tension or compression. Obtained under the trade designation "OMEGA LCFL-10" from Omega Engineering, Inc., Norwalk, CT, USA Sample Evaluation

[0018] A first evaluation was made using a commercial tension equalization device and tension measurement device in an orientation with Web 1 passing through the devices such that the web traveled approximately 80 degrees over a traditional web line idler, 30 degrees over the tension equalization device, and then 80 degrees over the lane tension measurement device. Web 1 was run through the web line at 15 feet per minute (4.57 m / min) and 1 pli (pounds-force per lineal inch) (1.75 N / cm). Winding tension was measured and controlled by use of two rollers that had load cells, application of the brake on the unwind station for the roll of Web 1, and use of a nipped pull roll. Compressed air was supplied at 11.8 scfin (20.1 m 3< / hr) on one side, and 100 psi (689 kPa) open line on the opposite side with unregulated flow. Web 1 lane tension measurements were collected from the tension measurement device with the figures recorded using the OMEGA OM-DAQXL data logger. Two of the blank components were removed and replaced with the OMEGA load cells such that one directly measured the baggy lane, and the others measured force two units away from the baggy lane. These locations are represented by their transverse direction on the web, such as T D@X" and noted in Table 1 as Comparative Example C1.

[0019] A second evaluation was made using the commercial tension equalization device and tension measurement device in an orientation with Web 1 passing through the devices such that the web traveled approximately 80 degrees over a traditional web line idler, 30 degrees over the tension equalization device, and then 80 degrees over the lane tension measurement device. Web 1 was run through the web line at 15 feet per minute (4.57 m / min) and 1 pli (pounds-force per lineal inch) (1.75 N / cm). Winding tension was measured and controlled by use of two rollers that had load cells, application of the brake on the unwind station for the roll of Web 1 and use of a nipped pull roll. No air flow was supplied to the tension equalizing device. As Web 1 was passed through the above-mentioned configuration, lane tension measurements were collected from the tension measurement device with the figures recorded using the OMEGA OM-DAQXL data logger. Two of the blank components were removed and replaced with the OMEGA load cells such that one directly measured the baggy lane, and the others measured force two units away from the baggy lane. These locations are represented by their transverse direction on the web, such as T D@X" and noted in Table 1 as Comparative Example C2.

[0020] A third evaluation was made using the comparative idler roller and tension measurement device in an orientation with Web 1 passing through the devices such that the web traveled approximately 90 degrees over a traditional web line idler and then 90 degrees over the tension measurement device in the same configuration as the first evaluation but with the tension equalizing device removed and replaced with the web-tensioning apparatus of the present disclosure. Web 1 was run through the web line at 15 feet per minute (4.57 m / min) and 1 pli (pounds-force per lineal inch) (1.75 N / cm). Winding tension was measured and controlled by use of two rollers that had load cells, application of the brake on the unwind station for the roll of Web 1 and use of a nipped pull roll. As Web 1 passed through the above-mentioned configuration, lane tension measurements were collected from the tension measurement device with the figures recorded using the OMEGA OM-DAQXL data logger. Two of the blank components were removed and replaced with the OMEGA load cells such that one directly measured the baggy lane, and the others measured force two units away from the baggy lane. These locations are represented by their transverse direction on the web, such as T D@X" and noted in Table 1 as Example 1. Table 1. Web Evaluation Results Web Transverse Direction LocationComparative C1*Comparative C2*Example 1*T D@1.25" 1-1.10.6-0.70.5T D@4.25" Baggy Lane Location0.6-0.80.3-0.40.5*Units in pounds force.

Claims

1. A web-tensioning apparatus (10) comprising a first gas intake (12), a plurality of piston assemblies (15), each piston assembly connected to a web contact pad (20) comprising a sintered plastic material to provide a web contact pad assembly (20), wherein each web contact pad assembly is independently controlled pneumatically and self-adjusts to provide uniform tension across the width of a web.

2. The web-tensioning apparatus of claim 1, wherein the piston assemblies include a cylinder wall (24).

3. The web-tensioning apparatus of claim 1 or claim 2, wherein the sintered plastic material comprises ultra-high molecular weight polyethylene.

4. The web-tensioning apparatus of any one of claims 1 to 3 comprising 2 to 100 web contact pad assemblies (20), optionally 3 to 75 web contact pad assemblies (20), optionally 4 to 50 web contact pad assemblies (20).

5. The web tensioning apparatus of any one of claims 1 to 4, further comprising a second gas intake (13), wherein the first gas intake (12) operates at a lower gas pressure than the second gas intake.