US2593320A

US2593320A - Apparatus for heat-treating nylon yarn or cord

Info

Publication number: US2593320A
Application number: US172464A
Authority: US
Inventors: Arthur P Lewis; Charles F Fisk
Original assignee: United States Rubber Co
Current assignee: Uniroyal Inc
Priority date: 1950-07-07
Filing date: 1950-07-07
Publication date: 1952-04-15
Anticipated expiration: 1969-04-15

Description

April 15, 1952 A. P. LEWIS ET AL APPARATUS FOR HEAT-TREATING NYLON YARN OR CORD 4 Sheets-Sheet 1 Filed July 7, 1950 INVENTORS A ril 15, 1952 A. P. LEWIS ET AL 2,593,320

I AP PARATUS FOR HEAT-TREATING NYLON YARN OR CORD Filed July 7, 1950 4 Sheets-Sheet 2 W 6.. GYM

ATTORNEY WIIMWM m m E mm S\ s 14. ELF. W. Wm Q S WM Q i N m\\\ Q I 3 Q III x Q Q k-fi H H w, g 35m 4 1 H fifi Q U A ril 15, 1952 A. P. LEWIS ET AL 2,593,320

APPARATUS FOR HEAT-TREATING NYLON YARN 0R CORD Filed July 7, 1950 4 Sheets-Sheet s 7? 27 '3; J! /J i/ $9.03. ATTORNEY INVENTORS Patented Apr. 15, 1952 2,593,320 APPARATUS FOR HEAT-TREATING NYLON YARN OR com) Arthur P. Lewis, Fairhaven, Mass, and Charles F. Fisk, Clifton, N. J assignors to United States Rubber Company, New

tion of New Jersey York, N. Y., a corpora- Application July 7, 1950, Serial No. 172,464

13.Claims. 1 V

This invention relates to apparatus for heat treating or heat stabilizing coarse nylon yarn or cord, and more particularly to the combination of a loom for weaving low pick cord fabric and an oven for heat treating the nylon warp strands as they are advanced to the loom.

Fuel tanks used in certain types of aircrafts are made of reinforced rubber. The rubber reinforcing elements may be cotton or rayon cords similar to those used in the carcass of pneumatic automobile tires. It is preferable however to employ coarse nylon yarns or cords as the reinforcing elements since a nylon cord is lighter in weight than a cotton or rayon cord of the same strength. Therefore a reduction in the weight of such fuel tanks can be secured by using nylon strands as the rubber reinforcing elements. In order to retain these strands in straight parallel relation to each other until they are covered with rubber, it is customary to form what is called a low pick cord fabric in which 2 or 3 weft yarns per inch are woven with the warp cords to hold the latter in lace. I

Low pick warp fabric formed of coarse nylon yarns or cords and held in place by smaller and widely spaced weft yarns has been produced heretofore, and such web fabric has been heat treated after coming off the loom to stabilize the fabric so that it will be les sensitive to heat if subsequently subjected to an elevated temperature.

The heat treating procedure to which such low pick warp fabric was subjected heretofore was not satisfactory as it caused the fabric to bulge and distort badly so that it would not lie smooth and fiat, and this made it unsatisfactory for use to reinforce flat sheets of rubber.

Nylon strands as purchased from the manufacturer of the same appear to have been heat stabilized up to a temperature of about 212 F. or the boiling point of water, but if subjected to a much higher temperature they will shrink as much as five per cent or more. If coarse nylon yarns or cords are used as rubber reinforcing elements and such reinforced rubber is made into flexible fuel tanks for aircrafts, the vulcanizing temperature of approximately 260 F. which is employed to vulcanize the fuel tank will cause the nylon reinforcing elements to shrink 5% or more in the tank walls. This is likely to pull the seams open during the vulcanizing period. To prevent this it is important to subject the nylon reinforcing elements to a special heat stabilizing treat ment before they are used to reinforce the rubber.

Having in mind the foregoing the present invention contemplates apparatus, such as an oven;

for heat treating or heat stabilizing the nylon 'heat stabilized warps a few picks per inch of smaller weft yarns to hold the warp strands in place until they are bonded to a rubber sheet. This fabric woven of heat treated nylon warps lies fiat and smooth.

In accordance .with the present invention the nylon warp strands, such as coarse nylon yarns or nylon cords, are subjected for a short period of time to a temperature which is considerably above the temperature to which they will be subjected during a later vulcanizing period. In carrying out the present invention the time, temperature, and tension of the nylon strands are all important, and it is found that highly satisfactory results are secured by treating the nylon strands in the form of parallel warps for approximately one minute at a temperature of about 338 F. During this treatment each strand is under very slight tension so that it is free to contract about 4% under the action of the heat. This heat treatment lowers the modulus of the strands slightly :but does not appreciably reduce their tensile strength, and enables them to be subjected later to a vulcanizing temperature of approximately 260 F. for an hour or more without causing them to shrink as much as one per cent. As aresult of such treatment it is now possible to use nylon reinforcing elements in fuel tanks in a very satisfactory manner, and without causing such fuel tanks to distort or open at the seams, as frequently occurs when nylon reinforcing elements'are not subjected to a high temperature stabilizing treatment before they are subjected to the vulcanizing temperature employed to cure a fuel tank.

Since, in accordance with the present invention, the nylon warp strands are heat treated as they advance to the loom, and since in operating any loom an occasional stoppage occurs when a thread breaks or something else goes wrong, it is essential that means be provided to prevent the portion of the nylon warps which are passing through the oven when the loom stops from being overheated.

. Therefore one important feature of the present invention resides ,inthe combination of a loom for weaving a low pick warp fabric and an oven positioned adjacent the loom for heat treating the nylon warps as they approach the weaving position, and in means controlled by the loom and adapted to force air in a closed circuit within the oven so that it moves past the heating ifneans and then to said auxiliary chambers to pass therefrom into the warp chamber to heat quickly the warp strands when the loom isrnnning. If the loom stops for a short period it is important to maintain the oven at this high temperature, but to prevent such circulating hot air from reaching the warps in the oven when the'loom is not operating.

'In accordance with the present invention, the

control of the temperature within the warp chamber is such that the warps are subjected to a temperature of approximately 338 F. when the loom is running, and this temperature is quickly reduced to below 260 F. when the loom stops. This is secured by providing a series of dampers arranged so that the auxiliary chambers will serve to by pass" the warp chamber when theloom stops, and the hot air within such warp chamber will be quickly exhausted therefrom. This is accomplished by providing a control connection between the loom and said dampersv whereby the dampers will remain closed as long as the loom isoperating but will open when the loom stops.

The above and other features of the present invention will be further understood from the following description when 'read in connection with the accompanying drawings, wherein Fig. 1 is a side view with parts in section of a warp creel and associated oven.

Fig. 2 is a continuation of Fig. 1 and shows the heat treated warps as they travel from the oven of Fig.1 to a loom." v

Fig. 3 'is a horizontal sectional view through the oven of Fig. 1, the section being taken on the line 3-3 of Fig. 4. I

Fig. 4 is a vertical sectional view through-the oven, the section being taken on the line 4-4 of Fig. 3.

Fig. 5 is a similar view, the section being take on the line 55 of Fig. 3.

Fig. 6 is a side'view of a warp threading device for pulling the warp ends through the oven;

Fig. '7 is a side View with parts in section of electrical switch mechanism controlled by the Now referring to the drawings and more particularly to Fig. 1, the nylon warp strands ll] such' as coarse nylon yarns or nylon cords are supplied from individual spools ll supported by the creel 12 of usual construction, and the strand from each spool ll passes through an eyelet on the creel eyelet board l3. The strands l0 then move in a converging direction to pass between the lon horizontally disposed guide rolls l4 that are spaced a slight distance apart so as not to pinch the strands. As these strands l0 approach.

the rolls l4 they pass through the comb I5. The nylon strands [D which are now disposed side by side in a horizontal plane to form a warp pass horizontally through the heat treating oven 16. These warp strands in enter the oven through a narrow horizontally extending slot ll and leave through a similar exit opening 18. The warp strands that are now heat treated or heat stabilized pass to the loom of Fig. 2 and it should be pointed out that these warp strands II) are drawn forward from the creel supported spools I I by the loom take-up mechanism to be described.

The oven l6 and creel [2 are shown asresting upon the floor I9 of a building, and this floor rests upon the concrete surface 20. A pit 2| which receives various pipes, to be described, is preferably provided beneath the floor at a point between the creel and oven.

The oven is shown as rectangular in shape and has the oven floor 22, side and end walls 23 and top 24, and these walls are all insulated asshown. Within the upper portion of the oven [5 is provided the warp chamber 25. This chamber has the end walls 26 and 21, slotted upper wall 28 and slotted lower wall 29. Between the slotted'upper wall 28 and oven top 24 is provided a space which forms an upper auxiliary chamber 30. Between the lower slotted wall 29 and a horizontal parti tion 31 is provided the lower auxiliary chamber 32.

Mounted in the lower portion of the oven l6 below the horizontally extending partition 3| is a high velocity fan 33 which iscapable of circulating heated air at high speed, such as about 2000 cubic feet per minute, in an endless path within the oven. This fan which is mounted upon the floor 22 of the oven may be driven by a laterally extending shaft 33 that is driven by a motor, not shown, but disposed outside of the oven. This fan has the inlet opening 33" and the outlet opening 33, and the air discharged from this fan passes through a lint screen 34. The blast of air then passes between and around a large number of electrically heated bars 35. The number of these heating elements that are supplied with electricity at any one time may be increased or decreased as is necessary to maintain the circulating air at the desired high temperature. The number of such heating elements in operation can be manually controlled, but they are also controlled automatically when the oven is inoperation by an oven thermostat not shown. Y

The hot air upon leaving the heating elements 35 passes upwardly in the space 36 as shown in Figs. 4 and 5 to enter the upper auxiliary chamber 30 and lower auxiliary chamber 32, and to pass from these chambers through the slotted

floors

28 and 29 into the warp chamber 25 to heat the warp strands l0 passing through this chamber. This serves to subject the strands to a temperature of about 338 F. for approximately one minute, which is the time required for any one point upon the warp to pass through the oven. As long as the loom continues to run, the heated air will flow along the paths indicated by the arrows in Fig. 4 of the drawing, where it will be seen that such hot. air is directed against the warps I0 from above and below the same. This hot air then travels to the right in Fig. 4 towards the wall 26 and then upwardly through the damper controlled openings disposed at each side of the central vertical plane of the oven. This used air then passes downwardly through the passages 31 to the intake opening 33" of the position of Fig. 4, they close the discharge end of the-

chambers

30 and 32 so that the hot air forced into these chambers by the fan 33 will pass through the slotted

floors

28 and 29 into the warp chamber 25 to heat the warps. When the loom bangs-oil or stops the

dampers

38 and 39 will be automatically shifted from the vertical position in which they are shown in Fig. 4 to the horizontal position in which they are shown in Fig. 5. This serves to open the discharge end of the

auxiliary chambers

30 and 32 so that the hot air supplied to these chambers will by-pass the warp chamber 25, as shown by the arrows of Fig. Sand travel downwardly through the passage 31 and return to the fan 33. The air will continue to circulate in this manner through the oven at full temperature, but will not be supplied to the warp chamber 25 when the loom is not running. In order to quickly lower the temperature of the air within the warp chamber 25 after the loom bangs-off, the air is exhausted from this chamber by the pipe 49, which is normally closed by the exhaust damper 41, but this damper is opened as shown in Fig. when the loom stops. The exhaust pipe 40 extends downwardly through the floor of the even into the pit 2| and is connected with the horizontally and upwardly extending pipe 42 which leads tothe intake side of a fan 43. A discharge pipe 42' leads from this fan to a point outside of the building. The fan 43 is driven by a motor 44 that is controlled by the loom, so that this fan operates only when the loom is not running, as its function is to remove the hot air from the warp chamber 25.

When the loom is operating and the oven is heated to heat-treat or heat-stabilize the warps Ill, very little hot air will escape through the warp inlet opening I? and outlet opening 18 due to the comparatively low air pressure maintained in the warp chamber 25. The warp strands upon entering the oven will contain moisture absorbed from the atmosphere and this will be picked up by the hot air. It is therefore desirable to continuously bleed off a small amount of the air within the oven, and to this end there is provided a bleed pipe 45 which extends downwardly into the pit 2! where it is connected to a horizontally and upwardly extending pipe 46 that discharges outside of the building. In addition to the bleed pipe mentioned, it may be desirable to provide means for removing from the warp chamber released vapors which have an objectionable odor. To this end there may be provided the vapor hoods 41 which lead outwardly from the warp chamber 25 and are connected by the incline pipes 48 and vertical pipe 49 to the vapor removing fan 50 having leading therefrom to the outside of the building the discharge pipe 51.

The oven I6 is, as above stated, provided with five dampers; two number 38 control the upper auxiliary chamber 30, two number 39 control the lower auxiliary chamber 32, and one marked 4| controls the means for exhaustinghot air from the warp chamber 25. The mechanism for operating these five dampers as the loom starts or stops will now be described. The upper dampers 6. 38 are secured to and controlled by the horizontally extending shaft 52 and the lower dampers 39 are secured to and operated by the horizontally extending shaft 53 (Fig. 1). The exhaust damper 4| is secured to and operated by the horizontally extending shaft 54, see l. The shaft 52 is operated by a compressed air cylinder 55. The shaft 53 is operated by a compressed air cylinder 56. The shaft 5 is operated by a compressed air cylinder 51. These three cylinders are shown in Figs. 4 and 5 and also in Fig. 8. In each cylinder is mounted a piston and sliding piston rod 58 which is connected to a rod operating lever 59. Within each of these cylinders is provided a coil spring 63 which normally hold each piston rod 58 in its retractive position, but when compressed air is introduced into a cylinder it will force the piston lengthwise of the cylinder in opposition to the coil spring. 60. As a result, when these cylinders are permitted to exhaust to the atmosphere the pistons will be retracted, but when the cylinders are supplied with air under pressure the piston rods 58 will be extended.

One good practical means for controlling the supply of compressed air to the cylinders is illustrated in Fig. 8 wherein there is shown the compressed air supply pipe 6! leading from a suitable source of compressed air, not shown. This pipe connects with the valve casing 62 shown in section and within which is provided the sliding valve 63. casing 62 is the pipe 6-! having the connections to one end of the

cylinders

55, 58 and 5?. The valve 53 is shownlowered in position to shut off the supply of compressed air from the pipe 6!, and to exhaust air from the

pipes

64, and 55. This alve 63 is held depressed in the position in which it is shown by the valve stem 66 When permitted to rise this valve will be moved upwardly by the coiled spring 61 to bring the valve passage 68 into alignment with the pipes BI and 64 and admit compressed air to the

cylinders

55, 56 and 57. It will be noted that the valve stem 66 is surrounded by a solenoid 55 which is connected in a circuit controlled by the cam switch 10. This switch is controlled by the running loom in a manner to be described. As long as the loom runs this switch is closed as shown in Fig. 8 and the solenoid remains excited to hold the valve shaft 66 downwardly in the position in which it is shown in Fig. 8. When the switch 10 opens due to the stoppage of the loom the valve 63 will move upwardly under the force of the spring 6? to supply compressed air to the three cylinders as above mentioned. As this rod 68 moves upwardly it will close a switch H to thereby start the motor 44 which operates the exhaust fan 43 above described.

It sometimes happens that a loom will stop for only a second or so and is then started up by the loom operator. If this should occur, it is unnecessary to operate the five oven dampers. Therefore the construction of Fig. 8 may be provided with a delay action dash pct 12 having a piston 13 therein secured to the lower end of the valve rod 65. Within this dash pot may be confined oil or other liquid, and'the piston is provided with a small bleed aperture which will cause the piston to rise slowly, but at the upper face'of this piston is provided a one-way valve 14 which will allow the piston to move downwardly rapidly. The effect of this is to delay'for several seconds the rising of the valve B3 when the loom stops but not to delay the lowering of the valve 63 when the loom starts up.-

Leading from the valve As above stated time or period heat is applied, temperature, and strand tension are important in heat-treating the nylon warps, so that they will not contract more than a fraction of 1% when later subjected to a vulcanizing temperature of around 260 F., and also so as not to cause such strands to undergo a loss in tensile strength. The time is determined by the normal operation of the loom which lays 2 /2 picks per inch and weaves about 60 inches per minute so that if the oven measures about 60 inches from the inlet passage I! to the outlet passage I8, each warp strand will be subjected to the high temperature for about one minute. The temperature in'the oven is, as above mentioned, controlled by a thermostat which controls the number of electric heating elements 35 which are in operation at any one time. The strand tension should be very low, and this is secured by mounting the spools II on the creel posts at a slight angle to the horizontal so that they will turn freely, and cause very little tension to be placed on the individual strands I as they are pulled forward from the supply packages II by the loom take-up mechanism.

Since all of the warp strands I0 pass through the oven I6, it is deemed desirable to provide threading means in the form of the endless chain both runs of which pass through the warp chamber 25. This chain loops about sprockets 16 disposed at the intake and at the outlet sides of the oven, see Figs. 3 and 6. These sprockets are supported outside the oven at one side of the warp path. The endless chain 15 has secured thereto at spaced points along its length small springs I1 adapted to frictionally engage and hold a warp end In to thread up the same. Each sprocket wheel I6 may be manually rotated by an auxiliary sprocket chain I8 which passes around the sprockets I9 and 80, the latter of which can be rotated by the crank arm BI. The threading mechanism just described is shown at only one side of the warp in Fig. 3 but if desired a similar threading device may be provided at the opposite side of such warp, so that when a strand breaks its end may be engaged with a spring I? upon the nearest chain I5 and then the chain operated by the crank 8| to draw the strand I0 through the oven, whereupon it may be moved laterally to its proper position within the warp sheet. 7

Having described the oven I6 which serves to heat stabilize the warps as they are advanced towards the weaving position the loom which is provided to weave a low pick cord fabric will now be described. This loom is shown in Fig. 2, which view is as above stated a continuation of Fig. l and the line A-A in Fig. 1 and Fig. 2 represent the same position along the warp plane. The loom of Fig. 2. for the most part is of well known construction and operates in a well known manner and therefore will be only briefly described. The take-up mechanism of this loom serves to pull the warp strands I0 forward from the supply creel I2 of Fig. 1, through the oven I6 and to the loom.

The loom has the supporting

frame

82, 83 which rests upon the floor I9 of the building. The warps II) upon leaving the oven I6 pass through a comb 84 supported at the right hand end of the loom. The warp then passes over a pair of horizontally disposed rolls 85 and under a floating roll 86. Since the warps I5 are subjected to very little tension while they pass through the oven I6, it is desirable to increase that tension as they approach the weaving point; This is accomplished by causing the warps to loop around a retarding roll 81 the rotation of which may be controlled by brake means not shown. These warps then pass around the upper roll 88, and then in a horizontal plane through the loom. In order to make sure that all warps are separated one from another as they approach the weaving position it is desirable to interlace between the warp strands the transverselyextending separating bar 89, which is connected with the lay of the loom by the connecting rods 90. The arrangement is such that this bar will slide back and forth within the warp threads to separate them as the lay moves back and forth. The warp then passes to the drop wire mechanism SI, of usual construction and having the drop wires 92, one of which is suspended from each warp strand, so that if the strand 2c; breaks the loom will stop. The warps then pass to the harness mechanism of usual construction and comprising the two

harnesses

33 and 94 which are operated from the cam shaft 95 having the cams that operate the treadles B6 and 91. -Above the cam shaft 95 is disposed the crank shaft 98 which is driven through suitable gears from a motor 99. The cam shaft 95 is driven from the crank shaft 98 by the gears'shown. The loom has the usual lay I00 and reed II. The lay is supported by the lay swords I02, and the shuttle is driven back and forth across the loom by the picker sticks I03, only one of which is shown. The lay is moved back and forth in the usual manner by the crank arms I04 which connect it with the crank shaft 98.

The weft employed in weaving may be a relatively small cotton yarn since its sole purpose is to hold the strong warp strands in the desired side by side relation to each other until the rubberwhich they are to reinforce is applied thereto. These weft yarns are widely spaced, since only two to three picks per inch are needed to retain the warp strands in place. The loom therefore weaves at relatively high speed and produces about sixty inches of low pick cord fabric per minute. The shuttle is thrown back and forth through the shed in the usual manner andas the weft yarn is laid in the shed and beaten up as usual to form the fabric, this fabric which is indicated by the numeral I05 passes over a supporting roll I06, and then downwardly and is looped around the power driven sand roll IGI. It then passesupwardly about an idle roll I08, andthen downwardly again near the level of the floor to pass around and horizontally from a roll I09 to the packagedriving roll II 0. It is then wound into the fabric package III about the core II2 that is supported to move upwardly as the package increases in size. To this end the core engages the guide slots formed in the uprights II3 disposed at the opposite ends of the fabric package. .The sand roll In! is shown as driven from the crank shaft 33 by the revolving shaft H4 which is provided with'a worm H5 at its outer endthat drives the sand roll. The roll III) and H6 that support and rotate the fabric package III are driven from the sand roll I01 by the chains II! and H8. The chain II8 drivesaslip clutch Il9 which drives a gear that operates the rolls I II] and I I6. This slip clutch serves to wind the package under the desired tension.

. When the loom is running it will pull the warp strands I0 through the oven I6 at a speed of approximately inches per minute, and'as long as the warp chamber 25 is maintained at a tem- .9. perature of about 338 F., the warps will be given the desired heat stabilizing treatment. Theloom shown is provided with the usual stop mecha nisms including the drop wires above mentioned,

so that if a warp or weft thread breaks or other defect in the loom operation occurs the loom will automatically stop. This will stop the advance of the warp through the oven. If these strands are allowed to remain in the ovenat the high temperature just mentioned for much over a minute they will be seriously damaged or destroyed. It is therefore important to provide means controlled by the loom operation which will control the temperature of the warp chamber 25 through which the warps extend.

This control from the loom is secured in the construction shown by providing the special switch construction shown in Fig. 7 as enclosed within the casing I20 that is mounted upon the loom frame near, the cam shaft to be operated thereupon. To this end the shaft 95 is provided with a sprocket I2I and chain I22 that drives a sprocket I23 secured to the rotating shaft I24 that is journaled in the casing I 20, and at the inner end of this shaft I24 is mounted the metal disc or core I25. The arrangement is such that as long as the loom operates this core I25 will rotate, and when the loom stops it will stop. Within the casing I20 is rotatably mounted the disc I20 that is rotatably supported by a shaft I21, and secured to this disc are a number of magnets I28 the outer ends of which lie close to the core I25. The arrangement is such that as yarn or cord are satisfactory for a construction that will run about 2,600 yards to the pound before the strands are passed through the heat treating oven I6. It is found that the treatment described does not reduce the strength of the nylon strands noticeably, and such strands will not shrink more than 1% when subjected for a long as the core I25 rotates the magnetic field between this core and magnets I28 will exert a rotating force upon the disc I26, and this will serve to rotate the same through a small angle against the pull of the coiled spring I29 and close the switch I0. When the core I25 stops rotating the magnet supporting discs I26 will be pulled to its at rest position by the spring I29 to open the switch 10 that is included in the circuit formed by the wires I30 which are connected to a suitable source of electric energy.

As long as the loom is running the circuit I30 will be closed by the switch I0 as shown in Fig. 8. and the solenoid 59 will be excited so that it will hold the valve 63 in its depressed position in which it is shown in Fig. 8. When the loom stops the disc I26 will move to the switch open position and this will cut off the electric energy to the solenoid 69 so that the valve 63 will rise under the action-of the compressed spring 61. When this valve rises it will supply compressed air through the connection BI, '64, and B5 to operate the pistons within the compressed air cylinders 55,51 and 51 so that they will shift the dampers above described and cause the stream of hot air within the furnace I5 to by-pass the warp chamber 25 as above pointed out. When the valve stem 66 rises as just mentioned, it will close the switch (I so as to operate the exhaust fan 43 to remove hot air from the warp chamber 25.

If the loom is stopped for only a few minutes it is desired to maintain the high temperature of 338 within the oven, but in order to prevent the warps from being overheated when the loom is not running the temperature within the warp chamber 25 should bereduced to below 260 F. within about one minute. If it is necessary to shut the loom down for a long period then the oven fan 33 and heaters should be cut off.

The time and temperature conditions above described for heat stabilizing rubber reinforcing elements made of high tensile coarse nylon long period to a vulcanizing temperature of approximately 260 F. If a different weight nylon strand is used from that just mentioned the time 01' temperature may need to be changed slightly.

The following table gives the property of a nylon cord having the construction 210d./4/2, 34 filament type 300 nylon, and of a low pick cord fabric produced from such treated warp cords. The same heat treatment however may be used for an 840d./2, filament, type 300 nylon yarn.

By providing the combination of a warp treating oven and loom for weaving a low pick fabric, in accordance with the present invention, it is possible to heat treat or heat stabilize the nylon warp strands at low cost as they are advanced to the loom. It is also possible due to the control mechanism herein described to start and stop the loom and the travel of the warp through the oven without causing the warp to be overheated when the loom stops and the movement of the warps is arrested. Furthermore, by heat treating the nylon warps before the weft is woven therewith a fabric is produced which lies smooth and flat and which will shrink less than 1% when subjected to rubber vulcanizing temperature.

Having thus described our invention, what we claim and desire to protect by Letters Patent is:

1. In combination, a loom for weaving a fabric formed of coarse nylon warp strands and widely spaced weft strands, an oven adjacent to the loom for heating the nylon warp strands sufficiently to stabilize them against subsequent heat shrinkage as they approach the weaving position, and means controlled by the loom and operable when the loom stops to reduce quickly the temperature of the warp strands in the oven.

2. In combination, a loom for weaving a fabric formed of nylon warp strands and weft strands, an oven adjacent, to the loom for heating the nylon warp strands while they are approximately free from tension to stabilize them against subsequent heat shrinkage as they are advanced to the weaving position, and means controlled by the loom and operable when the loom stops to reduce the temperature of the warp strands in the oven many degrees within a period of one minute.

3. In combination, a loom for weaving a fabric of nylon warp strands and weft strands, an oven adjacent to the loom constructed to have the warp strands pulled therethrough by the operating loom, means for heating the oven to over 300 F. to stabilize the nylon warp strands against subsequent heat shrinkage as they approach the weaving position, and means controlled by the loom and operable when the-loom stops to re- 11 duce quickly the temperature of the warp strands in the oven. w

4. Apparatus for producinga fabric formed of heat treated thermoplastic warps and of wefts that are not subjected to such heat'treatment, comprising in combination, a loom for weaving the warps and wefts into a fabric, an oven adjacent to the 100m and constructed to have the thermoplastic warps pulled therethrough by the loom under slight tension, means for heating the warps in the oven to heat stabilize them, and means controlled by the loom and operable when it stops to reduce quickly the heat supplied to the warps in the oven.

Apparatus for producing a fabric formed of heat treated thermoplastic; warps and widely spaced wefts, comprising in combination, a loom for weaving the warps and wefts into a fabric, an oven adjacent to the loom and constructed so that the thermoplastic warps are pulled therethrough under low tension by the loom, means for supplying hot air to the warps in the oven to heat stabilize them, and means controlled by the loom and operable when it stops to stop the supply of hot air to the warps and reduce the temperature of the warps many degrees within one minute.

6. Apparatus for producing a fabric formed of heat stabilized nylon warps and widely spaced wefts, comprising in combination, a loom operable to weave said warps and wefts into a fabric at a speed of from one to several yards a minute, a heated oven positioned adjacent to the 100m so that the warps are pulled through the oven and heat stabilized as they approach the loom, and means controlled by the loom and operable when it stops to stop the supply of heat to the warps.

l '7. Apparatus for producing a fabric" containing heat stabilized warps, comprising in combination, a loom operable to weave thermoplastic warps and wefts into a fabric, a heated oven positioned adjacent to the loom so that the warps are pulled therethrough and heated as they approach the loom, and means controlled by the loom and operable when it stops to reduce quickly the heat supplied to the warps.

8. Apparatus for producing a fabric containing heat stabilized warps, comprising in combination, a loom operable to weave thermoplastic warps and wefts into a fabric, a heated oven positioned adjacent to the loom so that the warps are pulled therethrough and heated as they approach the loom, means for forcing hot air against the warps in the oven, and means operable when the loom stops to direct such hot air away from the warps.

9. Apparatus for producing'a fabric containing heat stabilized warps, comprising in combination, a loom operable to weave thermoplastic warps and wefts into a fabric, a heated oven positioned adjacent to the loom so that the warps are pulled therethrough and heated as they approach the loom, means for forcing hot air against the warps in the oven and for deflecting the hot air away from the warps when the loom is not running, and mechanism controlled by the loom movement and operable to actuate said deflecting means so that the warps will be subject to the heat treating temperature only whil the loom operates. I

10. Apparatus for producing a low pick warp fabric formed of heat stabilized nylon warps and widely spaced wefts, comprising in combination, a loom operable to weave said warps and wefts and provided with a take-up beam operable to advance the woven fabric and to pull the warps forward from their source of supply, a heated oven adjacent to the loom and constructed so that the warps are pulled therethrough by said take-up beam, and means controlled by the loom and operable when the loom stops to stop the supply of heat to the warps and reduce the temperature ofthe warps many degrees within one minute.

11. Apparatus for producing a low pick warp fabric formed of heat stabilized nylon warps and widely spaced wefts, comprising in combination, a loom operable to weave said warps and wefts and provided with a take-up beam operable to advance the woven fabric and to pull the warps forward from their source of supply, an oven adjacent to the loom and constructed so that the warps are drawn therethrough by the looms, means for forcing hot air against the warp in the oven, and means controlled by the loom and operable to deflect said hot air away from the warps when the loom stops.

12. Apparatus for producing a fabric formed of heat stabilized warps, and wefts that are not.

subjected to the heat treatment, comprising in combination, a loom for weaving thermoplastic warps and wefts, an oven positioned adjacent to the loom and constructed to have the thermo-' plastic warps pulled therethrough by the operating loom, a warp chamber in the oven positioned between two auxiliary chambers, means for forcing hot air into the auxiliary chambers and from these chambers into the warp chamber, and means controlled by the loom and operable when it stops to cause the hot air supplied to said auxiliary chambers to by-pass the warp chamber.

13. Apparatus for producing a fabric containing heat stabilized warps, comprising in combination, a loom operable to weave thermoplastic warps and wefts into a fabric, a heated oven positioned adjacent to the loom and through which the thermoplastic warps pass to the loom, said oven having a warp chamber for heating the advancing warps, means for supplying hot air to such chamber when the loom is running and for by-passing such chamber when the loom is stopped, and means controlled by the loom for exhausting hot air from said chamber when the loom stops to thereby quickly cool the warps therein.

ARTHUR P. LEWIS. CHARLES F. FISK.

REFERENCES CITED v The following references are of record in the .file of this patent:

UNITED STATES PATENTS Number Name Date 2,303,983 Brown Dec. 1, 1942 2,421,135 Walter et a1 May 27, 1947 2,421,532 Welti June 3, 1947 2,444,903 Van Buren July 6, 1948

Claims

1. IN COMBINATION, A LOOM FOR WEAVING A FABRIC FORMED OF COARSE NYLON WARP STRANDS AND WIDELY SPACED WEFT STRANDS, AN OVEN ADJACENT TO THE LOOM FOR HEATING THE NYLON WARP STRANDS SUFFICIENTLY TO STABILIZE THEM AGAINST SUBSEQUENT HEAT SHRINKAGE AS THEY APPROACH THE WEAVING POSITION, AND MEANS CONTROLLED BY THE LOOM AND OPERABLE WHEN THE LOOM STOPS TO REDUCED QUICKLY THE TEMPERATURE OF THE WRAP STRANDS IN THE OVEN.