Patent Grant
7073318
The present invention relates to an apparatus and method for heat-setting yarn. More particularly, the present invention is an apparatus and method for heat-setting bulk continuous filament (BCF) yarns with hot atmospheric air.
Background art methods for making BCF yarns for carpets typically include the steps of twisting, heat-setting, tufting, dyeing and finishing. In particular, heat-setting of twisted yarn is an important step in converting BCF yarns to carpets. Heat-setting develops crimp and locks the twist memory in the BCF yarns. The development of crimp and twist memory have a significant impact on yarn bulk and newness retention of finished carpets.
Two types of heating-setting methods are used in continuous heat-setting machines of the background art. The first type uses pressurized steam (i.e., saturated or near saturated steam). The most common pressurized steam heat-setting machine in the background art is referred to as a Superba® machine and is made by Superba of Mulhouse, France or American Superba, Inc. of Charlotte, N.C. An exemplary Superba heat-setting machine is model number TVP-12-806, which operates with a maximum temperature of 154° C. and typically in the temperature range from 120° C. to 140° C.; and operates with a maximum pressure of 65.26 psi and typical in the pressure range from 22 to 37 psi.
The second type of heat-setting method uses hot atmospheric air. The most common hot atmospheric air heat-setting machine in the background art is referred to as a “Suessen” machine and is made by American Suessen, Inc. of Charlotte, N.C. An exemplary Suessen heat setting machine is the Horauf-Suessen, model number GKK-6R, which typically operates in the temperature range of 160° C. to 210° C.
The crystalline structure of heat-set yarns and the end use performance of the finished carpets produced from heat-set yarns primarily depend on the heat-setting method used in producing the yarn. In general, carpet yarns produced by hot atmospheric air heat-setting machines (e.g., Seussen) have higher bulk and better stain resistance than carpet yarns produced by pressurized steam heat-setting machines (e.g., Superba®).
In addition, there are two types of heat-set carpet yarns: texture set and straight set. Texture set twisted BCF yarns are more versatile in styling than texture set staple yarns. Moreover, it is much cheaper to convert BCF yarns into carpets than it is to convert straight yarns into carpets. The majority of the carpets in today's residential market use texture set yarns.
Texture set yarns are produced by feeding twisted yarn into a stuffer device before directing the stuffed and twisted yarn into a heat-setting machine.
The apparatus of
However, the apparatus of
In addition, when hot atmospheric air is used in heat-setting machines, the yarn ends of the stuffed and twisted BCF yarn bundle tend to shrink. Any minor differences in the shrinkage among the yarn ends of the stuffed and twisted BCF yarn bundle can cause serious winding problems due to frequent yarn breaks. Thus, background art hot atmospheric air heat-setting apparatus and methods typically have not been used to continuously process stuffed and twisted BCF yarn in commercial applications.
Despite the problems discussed above, twisted BCF yarn carpets that are heat-set with hot atmospheric air have the significant advantages of providing higher bulk and better stain resistance than carpets that are heat-set with pressurized steam. Therefore, there is a need in the art to increase use of hot atmospheric air heat-setting machines on a commercial scale to heat-set twisted BCF yarns.
The present invention is an apparatus and method for heat-setting yarns with hot atmospheric air that can be used to texture set BCF yarns and achieve high process yields. In particular, the present invention preheats the twisted yarn bundle prior to the bundle being fed to a stuffer device and a hot atmospheric air heat-setting machine.
One embodiment of the present invention is an apparatus for heat-setting yarns, comprising: a false twisting device configured to produce a twisted yarn bundle from at least two yarns that are preferably texture set bulk continuous filament yarns; a heating device configured to preheat the twisted yarn bundle, preferably in hot atmospheric air provided from a mixture of steam and atmospheric air within a chamber of the heating device that is maintained in a temperature range from 25° C. to 38° C.; a stuffer device configured to crimp the preheated and twisted yarn bundle; and a heat-setting machine configured to heat-set the stuffed, preheated and twisted yarn bundle with hot atmospheric air, wherein the heating device contains at least one internal heating element, preferably a steam pipe, and operates at atmospheric pressure within the chamber.
Another embodiment of the present invention is a method for heat-setting yarns, comprising: false twisting at least two yarns to produce a twisted yarn bundle; preheating the twisted yarn bundle in hot atmospheric air in a heating device, preferably in a mixture of steam and hot atmospheric air that is maintained in a temperature range from 25° C. to 38° C.; pulling the preheated and twisted yarn bundle into a stuffer device configured to crimp the preheated and twisted yarn bundle; and heat-setting the stuffed, preheated and twisted yarn bundle in a heat-setting machine with hot atmospheric air.
The heating device provides a preheating function preferably using, but not limited to, steam and atmospheric air. More specifically, low-pressure steam (e.g., 2 pounds per square inch gauge (psig) to 8 psig) is introduced into the chamber of the heating device through which the twisted yarn bundle is passed. The steam and atmospheric air mixture produces hot atmospheric air that preheats the twisted BCF yarn to develop crimp and twist memory in the twisted BCF yarn bundle. With the addition of preheating, texture set BCF twisted yarn bundles can be produced continuously in a heat-setting machine using hot atmospheric air and excellent process yields are achieved. The addition of the preheating function makes using hot atmospheric air in the heat-setting machine producing texture set BCF yarns commercially viable.
The apparatus and method for heat-setting yarns includes a heating device that makes commercial production of BCF twisted yarn bundles viable. While not wishing to be bound by any one theory, preheating the BCF twisted yarn bundle in the heating device reduces drag and tension on the BCF twisted yarn bundle. Drag and tension can seriously damage twist and crimp memory.
In addition, preheating with a low temperature steam and atmospheric air mixture at low pressure develops crimp and twist memory in the twisted yarn bundle. The crimp and twist memory provides the cohesion to the twisted yarn bundle that helps to avoid frequent breaking in the winding step after the heat-setting machine that occurs in background art hot air heat-set BCF twisted yarns. Therefore, the apparatus and method of the present invention makes continuous processing of the hot air heat-set BCF yarns in commercial production possible since frequent yarn breaking is avoided.
Next, as shown in
Typically, in a false twisting device 3 as shown in
Details of the structure of a preferred heating device 4 are shown in
As the twisted yarn bundle 9 is pulled through the chamber inside of the heating device 4, low pressure steam is fed through steam pipes 19a, 19b. The low pressure steam is in the range from 2 psig to 8 psig, as measured with a gauge at the point of entry of the steam pipes 19a, 19b, to the chamber of the heating device 4. The steam pipe 19a, 19b are located above and below the twisted yarn bundle 9 as the bundle is pulled through the chamber of the heating device 4. A plurality of holes 22 are drilled through the sides of the steam pipes 19a, 19b at locations preferably facing the center line of the heating device 4. The plurality of holes 22 in the steam pipes 19a, 19b deliver the low pressure steam into the volume space within the heating device 4 to fill all or nearly all of the space with steam that heats the atmospheric air inside the chamber of the heating device 4.
The steam and atmospheric air mixture produce hot atmospheric air in the temperature range from 25° C. to 38° C. that penetrates the twisted yarn bundle 9 as the bundle is pulled through the chamber of the heating device 4. The twisted yarn bundle 9 is pulled through the heating device 4 by the feed rolls 25 of the stuffer device 5. The speed at which the twisted yarn bundle 9 is pulled through the heating device 4 is typically in the range of 225 to 650 meters per minute. The draft tension range on the twisted yarn bundle 9 is less than 100 grams and the residence time of the twisted yarn bundle 9 in the heating device 4 is less than or equal to 0.1 seconds.
As can be seen in
As discussed above, due to the size of the entrance 17 and exit 29 of the chamber of the heating device 4, the pressure inside the chamber of the heating device 4 is at atmospheric pressure. Low pressure steam (i.e., with pressure in the range from 2 pounds per square inch gauge (psig) to 8 psig), as measured by a gauge at the point of entry of the steam pipes 19a, 19b to the heating device 4, is fed into the steam pipes 19a, 19b. The heating device 4 is preferably, but not limited to, a steam device with steam input at a pressure from 2 psig (138 kilopascals) to 8 psig (552 kilopascals), as measured by a gauge in the steam pipe at the entrance to the chamber. Alternatively, the steam is at a pressure from 4 psig (276 kilopascals) to 6 psig (414 kilopascals).
The heating device 4 preferably is surrounded by an insulating jacket 21 that helps to maintain a consistent temperature inside the heating device 4. The temperature of the low pressure steam inside the heating device 4 preferably in the temperature range from 25° C. to 38° C. As a result, the temperature of the twisted yarn bundle 9 inside the heating device 4 is also in the range from 25° C. to 38° C. The steam and atmospheric air mixture, where the steam is at least at 100° C., provided inside the chamber of the heating device 4 produces the operating temperature range from 25° C. to 38° C. This temperature range provides sufficient preheating of the twisted yarn bundle 9 but avoids damage to the crimp and twist memory that can occur at higher operating temperatures.
The stuffer device 5, as shown in
The heat setting machine 7, shown schematically in
The apparatus and method of the present invention facilitate heat-set processing of both texture set staple yarns and texture set BCF yarns. That is, the present invention is very robust and applicable to both staple and BCF yarns. Representative yarns that may be processed in the apparatus and in accordance with the method of the present invention include, but are not limited to, nylon 6, nylon 66, Trimethylene Terphthalate, Ethylene Terephthalate and polypropylene.
The present invention is further illustrated by the following examples, but these examples should not be construed as limiting the scope of the invention.
Wear tests which closely correlate to floor trafficking were conducted in a Vetterman drum test apparatus, Type KSG manufactured by Schoenberg & Co. Baumberg, Fed. Rep of Germany, according to ISO (International Standards Organization) Document TC38/12/WG 6 N48. As specified, the drum was lined with carpet samples into which a 16 pound steel ball having fourteen (14) rubber buffers which rolls randomly inside the rotating drum were placed. A circular brush within the drum was in light contact with the carpet surface and picks up loose pile fibers which are continuously removed by suction. After 5,000 cycles, the samples were removed and inspected to evaluate texture retention. Texture retention was reported on a scale of 1 to 5 with a rating of 5 corresponding to a lightly worn sample, 3 to a moderately worn sample, and 2.5 to the turning point from acceptable to unacceptable wear. A rating of 2 corresponds to clearly unacceptable wear, and 1 corresponds to an extremely matted sample.
In this comparative example, approximately 60 pounds of 1120 denier, 61 filaments nylon 66 BCF yarn were converted into 4.75 twists per inch twisted yarn. Three ends of yarns were texture set together on a Suessen hot air heat-setting machine. The ends were fed through a false twisting device, a stuffer device and heat-set in the Suessen hot air heat-setting machine. The belt density was 150 gram/meter and the residence time in the hot air heat-setting machine was 60 seconds. The hot air temperature was set at 190° C. Eleven winding breaks were observed during 3 hours of operation. The test yarn collected was converted into 5/32 gauge, 18/32 inch pile height, 25 oz/square yard cut pile carpets. This carpet had an inadequate textured look and the method was not acceptable for commercial operation.
Approximately 60 pounds of 1120 denier, 61 filaments nylon 66 BCF yarn was converted into 4.75 twists per inch twisted yarn. Three ends of the yarns were texture set together on the hot air heat-setting machine of this invention. The ends of the yarns were fed through a false twisting device, a heating device, a stuffer device and into a hot air heat-setting machine. The steam pressure inside the heating device was atmospheric. The belt density was 150 gram/meter and the residence time in the hot air heat-setting machine was 60 seconds. The hot air temperature in the heat-setting machine was set at 190° C. No process breaks were observed during three hours of operation. The test yarn was converted into 25 oz/square yard carpet similar to Example 1. The finished carpet had much better aesthetics in terms of tip definition and texture look than Example 1.
Approximately 50 pounds of 1120 denier, 61 filaments nylon 66 BCF yarn was converted into 4.75 twist per inch and heat-set on a hot air heat-setting machine as described in Example 2. However, the hot air temperature in the chamber of the heat-setting machine was set at 183° C. instead of 190° C., as in Example 2. No process breaks were observed during the entire test. The test yarn was converted into 25 oz/square yard carpet and had the aesthetic characteristics as described in Example 2.
Approximately 50 pounds of 1120 denier 61 filament nylon 66 BCF yarn was processed similarly to Example 2, except that the hot air temperature in the heat-setting chamber was set at 176° C. instead of 190° C., as in Example 2. No process breaks were observed. The test yarn was converted into 25 oz/square yard carpet and had the aesthetic characteristics as described in Example 2.
Approximately 50 pounds of 1120 denier 61 filament nylon 66 BCF yarn was processed similarly to Example 2, except that the hot air temperature in the heat-setting chamber was set at 170° C. instead of 190° C., as in Example 2. No process breaks were observed. The test yarn was converted into 25 oz/square yard carpet and had the aesthetic characteristics as described in Example 2.
The carpet samples from Examples 1to 5 were tested for texture retention in a Vetterman drum for 5,000 cycles. The texture retention rating system values are in the range from 1-to-5, with 5 being considered as “like new.” The performance ratings are summarized in Table 1.
The test results of Table 1 indicate texture retention ratings of 3.5, which is commercially acceptable. Moreover, the present invention also makes it possible to reduce energy costs associated with a hot air texture set method by reducing the hot air heat-setting machine temperature from above 200° C. to temperatures of 170° C. to 190° C., as shown in Examples 2 to 5. Thus, the description of the present invention and test results demonstrate that an apparatus and method for hot atmospheric air heat-setting of BCF yarns is commercially viable.
The foregoing description of preferred embodiments of the present invention provides illustration and description, but is not intended to be exhaustive or to limit the invention to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The scope of the invention is defined by the claims and their equivalents.
| Number | Name | Date | Kind |
|---|---|---|---|
| 5233736 | Hill | Aug 1993 | A |
| 5414987 | Knoff et al. | May 1995 | A |
| 5647109 | Steiner et al. | Jul 1997 | A |
| 6094790 | Weiss | Aug 2000 | A |
| Number | Date | Country | |
|---|---|---|---|
| 20050223689 A1 | Oct 2005 | US |
