US2978783A - Singeing apparatus - Google Patents

Description

April 11, 1961 F. J. CLENDENING, JR 2,978,783

FRANCIS J. CLENDEN|NG,JR.

April 11, 1961 CLENDENlNG, JR 2,978,783

SINGEING APPARATUS Filed July 31, 1957 2 Sheets-Sheet 2 FURNACE BOUNDARY INVENTOR FRANCIS J. CLENDENING,JR.

BY Q A 61% ATTORNEY United States Patent" 2,978,783 SINGEING APPARATUS Francis J. Clendening, Jr., Wilmington, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington,

DeL, a corporation of Delaware Filed July 31, 1951, Ser. No. 675,411 2 Claims. (cl. 26-6) This invention relates to an apparatus for singeing fabrics and more particularly to an improved process for singeing fabrics constructed of synthetic fibers.

Various singers have been employed in the past chiefly for the finishing of cotton fabrics. Most of these singers possess certain shortcomings, particularly with respect to the maintenance of uniform temperatures across the surface of the fabric. With the advent of synthetic fiber fabrics, the difiiculties in singeing have multiplied. Not only is it necessary to achieveuniform temperatures acrossthe surface of the synthetic fabric, but more importantly, provision must be made to prevent build-up of molten polymer and the formation of molten polymer balls on the fabric surface.

, It is an object of this invention to provide a process for finishing fabrics, and particularly fabrics of synthetic fibers having high pilling propensity. Another object is to provide an apparatus for singeing the surface of synthetic fabrics uniformly without allowing build-up of molten polymer balls. Other objects will be apparent from a more detailed description of the invention given below. i The above objects are accomplished by providing a novel apparatus for finishing fabrics comprising in combination, a hollow metal roll the lower portion of which is suspended in a heating chamber and friction driven by a driving means inside said heating chamber, said driving means in turn being cradled on bearings which are outside said heating chamber, said chamber having heating means preferably only in the sidewalls parallel to and facing said roll and an air gap separating the roll from the chamber at the sides, ends and bottom of the chamber and means for passing fabric counter to direction of roll travel in instantaneous wiping contact with the top surface of said roll. The invention also includes a process for finishing fabrics comprising conveying a fabric in instantaneous wiping contact with the top surface of a uniformly heated hollow metal roll rotating counter to the passage of said fabric, and adjusting the speed of said fabric with the temperature of the roll surface and the contact angle of fabric with roll such that only surface fibers of the fabric are removed by thermal shock treatment without destroying the fibers in the body of said fabric.

The invention may be more readily understood by reference to Figures 1 and 2 which are plan views and illustrate, respectively, a suitable arrangement for singeing a fabric in contact with a rotating heated roll, and a detailed view of a mechanism for supporting and rotating the heated roll to achieve maximum temperature uniformity.

Figure 1 shows a fabric 1 passing over tension bars 2 where the desired amount of tension is applied. From here, it passes over a spreader roll 3 and on to the steel hot roll 4. The amount of contact angle on the hot roll is determined by the position of idler roll 5, which is adjustable ,in the vertical direction. Roll 5 is also used to facilitate string-up in starting the device in that it is mounted on an air operated, lever arm and may be readily retracted so the fabric is not in contact with the heated roll. Driven nip rolls 6 control the speed of the fabric through the machine. The furnace 7 supplies a uniform gas flame which burns in the area indicated as 8 to heat the roll which is mounted in the furnace opening. This is produced by burning the gas at the two inner side wall surfaces of the porous ceramic furnace lining 9, through which it is fed from a manifold not shown.

Figure 2 shows the unique combination of elements for supporting and rotating the hot roll to get maximum temperature uniformity. Hot roll 4 is cradled by two heat-resistant stainless-steel rolls 10. These rolls are in turn cradled outside each end of the furnace between a bearing mounted disc 11 and two backup bearings 12. The roll shafts are extended on one end and have attached gears 13. Separately mounted gear 14 contacts gears 13 to rotate the idlers 10 and hence hot roll 4. Directly connected to gear 14 is sprocket 15, which transmits the power .to rotate the system by means of chain 16.

One of the advantages of the present invention resides in the arrangement of the apparatus whereby the direct wiping contact of fabric with the surface of the roll and the speed of the fabric over the hot roll in opposite directions allows any polymer which builds up on the roll as a result of finishing synthetic fabrics to be burned off completely during the singeing process. Another advantage is that the present arrangement of the apparatus permits the singeing of fabrics at speeds far in excess of those commonly used heretofore. These superior speeds decrease the possibility of dye sublimation when singeing dyed fabrics. Another advantage is based on the fact that the thermal shock which the fabric undergoes in contact with the hot roll promotes retraction or pigtailing of loose fibers back'into the interstices of the fabric.

The superior temperature uniformity of the heated roll achieved in the present invention is attained in part by restricting heat losses through line contact on rolling bearing surfaces. This eliminates heat loss through conventional shafting and water-cooled bearings. The uniform temperature achieved is aided by using a hollow stainless steel tube and by avoiding spider mandrels. The usual corrugating and rippling effects so often produced with open-flame singers are eliminated in the present invention by having the fabric directly contact the hot roll. For optimum results the fabric should. contact the exposed top surface of the heated metal roll over an arc of at least 10, the larger the arc the more uniform is the control of the singeing and generally the higher the quality of the singed fabric. The contact are may be varied in conjunction with the surface temperature of the hot roll and the speed of the fabric upon the roll depending on the particular fabric being finished. A particularly suitable are for singeing synthetic fabrics using the preferred gas fired porous ceramic Walled heating means illustrated in Figure 1 lies in the range of l5-20. All temperatures reported herein for the hot roll are those measured with a thermocouple at the top outer surface of the roll. It has been found that the roll temperature must be adjusted with the fabric speed andthe composition and construction of the fabric to obtain optimum singeing results. Thus, for example, :a woven fabric of polyethylene terephthalate blended with either cotton or wool in proportions of 65/35 may be singed satisfactorily on a roll at 1200" F. at the surface, whereas a polytheylene terephthalate woven fabric of the same construction should be singed at 600-700 F. roll temperature to prevent destruction of the fabric. This difference is believed to be due to a different moisture content held by the two fabrics. Fabrics of 100% poly hexamethylene adipamide may be singed at roll temperatures of 800 F.l200 F. Cotton and wool fabrics are generally singed at 800 F. to 1400 F. The temperature requirements of the'roll surface are such that the syn thetic fiber ends and fuzz protruding from the fabric be wiped off onto the roll sur'face'a'nd as the roll rotates past the side walls of the heating chamber the temperature be high enough to be above the melting point of any synthetic polymer fibers so as to cause the molten polymer accumulation on the rollto' melt and drop off completely to the bottom of the chamber, leaving the roll surface completely free of polymer when it again rotates into the top position ready to contact a new area of moving fabric. Any fibers composed of non-melting polymers or the natural fibers will contact the roll at a temperature high enough to carbonize the fiber ends and fuzz so that small pieces of the carbonized fibers drop off the roll into the chamber almost as fast as the fabric contacts the hot roll surface. The maximum temperature differential measured across the length of the hot roll in Figure 1 when the top surface is at 1200 F. is only 40 F., and this amounts to a substantial improvement in temperature uniformity compared with prior methods and apparatus available for singeing fabrics. When using water-cooled bearings the differential across the top of the roll at the same temperature of 1200 F. reaches 200-300 F. which leads to muchgreater variations in the hand and aesthetics of the singed fabrics treated on such an apparatus.

The speed of the hot roll is advantageously run at about 5-25 revolutions per minute, whereas most fabrics may be run in contact with the roll at 100-300 yards/ minute for the particular temperatures and fabrics discussed above. The hollow metal hot roll may be constructed of stainless steel tubing or any other type of steel, alloy steel, or iron, provided it will withstand the heating and reheating to stated temperatures and maintain its smooth surface at these temperatures for long periods of time. The two driving rolls (idlers in Figure 2 should be made preferably of some heat resistant alloy steel (such as type 309-C chromium-nickel steel) in order to withstand even hotter temperatures than the hot singeing roll and because these rolls expand upwards of two inches in length during firing of the singeing roll up to temperatures of about 1200" F.

In addition to the porous ceramic gas fired heating chamber illustrated in Figure 1, which is available commercially from Holden Metallurgical Products Company, other heating means may be used provided that the heating source directed toward the hollow singeing roll is not applied in the form of jets and is not concentrated or applied to confined areas. The heating source must be applied to raise and maintain the temperature of the hollow singeing roll uniformly. Other useful heating means include a cyclone fired furnace or an impingement type furnace.

The temperature uniformity obtained across the face of the fabric in the operation of the present invention is realized by having the fabric in direct fiush supported contact with the hot moving smooth surface of the hot roll, which keeps the fabric flattened during singeing and while at maximum temperature, compared with known open-flame singers which fire the fabric in unsupported condition and produce rippling, and known stationary hot surfaces which cause the fabric to be overheated in some areas and unsinged in others.

The present invention may be used for singeing any type fabric composed of either natural or synthetic fibers or blends of the two. Examples of such fabrics include those made from cotton, wool, rayon, cellulose acetate, polyamides, polyethylene terephthalate, acrylonitrile polymers and copolymers, vinyl chloride and vinylidene chloride polymers and copolymers, and the like. The fabric may be dyed or undyed before singeing. The present invention may be applied to fabrics having a wide variety of constructions, such as shitting goods, dress goods, suiting fabrics, work clothes, and the like, particularly staple fabrics and those having a tendency to form pills and fuzz.

The following examples are not limitative but illustrate specific embodiments of this invention. All parts are by weight unless otherwise specified. The data given in the examples for pill counts was determined on standard fabric test swatches which were subjected tot a pilling test for 60 minutes in the random tumble pilling tester, as described by Baird, Legere and Stanley, Textile Research Journal, 26, 731 (September 1956).

Example I A batiste shirting fabric of 65/ 35 polyethylene terephthalate/cotton spun yarns was singed on the hot roll singer of Figures 1 and 2 with the hot roll surface at 1200 F. and a fabric speed of 200 y.p.m., and then compared with commercially finished'goods, singed at y.p.m. with an open-flame singer. Data obtained from the test are as follows:

Hot Roll Commer- Singed clally Singed P111 nmmi' 1 2 1,4; Melt ball count (per sq. in. of fabric above 400 2,400. surface). Aesthetics (Subjective) Very smooth-.. Smooth Example I] A madras shirting fabric woven of 100% polyeaproamide spun yarns was run on the same hot-roll singer at 1200 F. with remarkable aesthetic improvement over open-flame singed samples. The vastimprovement was attributed to the dramatic reduction of the usual attendant surface melt balls.

Example 111 On Oxford shirting fabric of 65/35 polyethylene terephthalate/ cotton spun yarns was singed on the same hot roll at 1200 F. at 250 yards per minute fabric speed and compared to the commercially finished goods, singed at 75-100 yards per minute on a conventional openfiame singer. Data obtained from the test are as fol- Example IV A batiste fabric of 60/40 polyethylene terephtha late/cotton spun yarns was dyed with a dye formula designed to emphasize sublimation. This fabric was singed on the same hot roll as in Example I. A wetparison of uniformity from selvedge to selvedge and end to end revealed no sublimation of dye or other shade change as a result of the singeing procedure.

Example V Swatches of the same fabric from Example IV were pill tested and results of the hot-roll samples end to end and selvedge to selvedge showed perfect uniformity of 1.0 pill rating. Swatches of the same fabric singed on a standard open-flame commercial singer gave variable ratings of 1.5 to 2.0 pills.- r

The present invention offers many advantages over the prior art. It has been found that fabrics which have a. tendency to form pills on their surface may be heated 5 superficially at certain critical temperatures to eliminate or greatly decrease pill formation. It is necessary, however, to heat only the surface of the fabric and not the main body of fibers. The present invention oflers a simple, economical, and highly efiicient method for accomplishing this purpose.

It will be apparent that many widely different embodiments of this invention may be made without departing from the spirit and scope thereof, and therefore it is not intended to be limited except as indicated in the appended claims.

I claim:

1. A singeing apparatus comprising a hollow metal roll the lower portion only of which is suspended in a heating chamber, a pair of friction rolls located eutirely inside the heating chamber for rotating the hollow roll and both rolls being in contact with the said hollow roll throughout its length, the said pair of rolls being mounted on bearings which are outside the said 6 heating chamber, means outside the heating chamber for driving the said pair of rolls, heating means within the heating chamber along the sides thereof parallel to and facing the said hollow metal roll, a narrow air gap separating the roll from the chamber sides, and means for passing a fabric in wiping contact with the top surface only of the said hollow roll.

2. The apparatus of claim 1 in which the hollow roll is heated by means of a gas burning on the surface of the heating chamber walls.

References Cited in the file of this patent UNITED STATES PATENTS 1,655,233 Machlet Ian. 3, 1928 1,664,993 Osthoif Apr. 3, 1928 FOREIGN PATENTS 21,995 Great Britain of 1903 314,597 Great Britain July 4, 1929

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