IL31426A - Machines for the heat treatment of textile yarns - Google Patents

Description

IMPROVEMENTS IN MACHINES FOR THE HEAT TREATMENT OF TEXTILE YARNS D'^'DDDD Ο'ΌΙΓΟ 71ΕΡϋ7 11131383 D*>7173W This invention relates to machines for the treatment of textile yarns, and usually synthetic yarns, by a process involving some heat treatment. The invention is particularly applicable to false twist crimping machines.

At the present' time machines of the kind referred to tubular incorporate/heating units which are contained in heat insulated casings. These are usually situated vertically adjacent to each other and extend vertically down each side of the machine substantially along the whole of its length. In consequence a large volume of space within the machine is rendered inaccessible so that it cannot be effectively used. Such space could otherwise contain components such as the yarn supply bobbins and dispense with the need for a separate creel which usually stands alongside each side of the machine using up considerable floor space. Moreover, it is usually necessary for the yarn feeding device to be sited inconveniently near to floor level.

Also a yarn heating path which is vertical has a disadvantage in that owing to the thermodynamic increase in yarn length which occurs, the working height of the machine has to be increased thus giving rise to further and inaccessible and unusable space within the machine.

Further, a vertically disposed heating unit is subject to convection affects along the whole of its length; consequently the lower portion of the yarn heating path is at a lower temperature than the upper portion and the heat gradient is not linear.

Further, the vertical attitude of the yarn whilst it is being heated subjects it also to the effects of convection which causes uneven stretching and bad heat transfer since uniformity of heat transfer into the yarn over the heating surface and it is required to pull the yarn back onto the heated face. Thus the consequent increase in the tension in the yarn causes extension in the thermoplastic yarns and variation in the yarns being processed at the various positions along the length of the machine. In the processing of some yarns it is necessary for the yarn to pass over the heated surface at a very low tension and this on a vertical heating surface allows the yarn to twirl and sag away from the heated surface with consequent variations in the heat transfer.

The width of the vertical heating surfaces combined with their individually heat insulated cases occupy a substantial width along the machine and consequently the number of positions for yarns that can be processed is limited for a practical length of machine. Thus the total output of the machine for a given floor area and machine volume is limited.

A disadvantage of using tubular heating units for yarn in machines is the tendency for fumes and vapours from the heated yarns to condense upon the walls of the tubes due to the restricted ventillation within the heated tube and the fact that part of the tube is unheated. These deposits form a highly viscous tar-like residue which increases the fractional drag between the yarn and the tube wall causing a serious increase in the tension in the yarn. This condition, varying from tube to tube, causes variations in the yarn process and results in poor quality or sub-standard yarn.

The roughness of the residue also causes poor heat transfer with consequent further deterioration in the yarn quality. At times tubes become completely blocked and the condition of the interior surface cannot be visually inspect instance the introduction of a hot air stream blown through the tubes to prevent condensation, and the use of suction drainage via small holes in the tubes to draw off the condensate and which in turn may become blocked themselves .

A yarn heating path should be perfectly clean and smooth to give the best and most uniform heat transfer to the yarn but the cleaning and polishing of the interior surface of the tubular heating elements is difficult particularly when the tubes are curved and fixed within the machine. The use of flexible cables, plugs or other pull through devices often result in scoring the tube wall and it is difficult to ascertain whether these devices have removed all deposits.

Finally, when the tube walls are not perfectly smooth and clean some difficulty is experienced in drawing or threading a new yarn through the tubes by either suction or air pressure, and frequently a cable or hooks have to be used.

A yarn left stationary, momentarily within the heated tube will cause it to adhere to the walls of the tube and melt thus causing a further difficult restriction.

Some difficulties exist with a further type of machine for processing yarn which uses a heated surface which is continuous along both sides of the machine in that the yarns being heated pass diagonally and obliquely across the surface in close proximity so that a broken yarn at one processing position interferes and intertwines with the adjacent yarn and consequently the breakages become progressive and rapidly escalate along the length of the machine. This occurs with what is regarded as a normal spacing of yarn processing positions along a machine and elaborate means are used to prevent it. Because of this the capacity and ability of a machine of this type to Further, the open type of heating surface employed is difficult to enclose and insulate and consequently is subject to considerable heat loss.

The present machine has been devised with the general intention of avoiding the foregoing limitations and disadvantages inherent in the machines at present used* . According to the present invention therefore a yarn processing machine comprises yarn feed means and yarn receiving means arranged in rows along the length of the machine, and \ extending| plurality of heating elements^transversely of the length of the machine between the rows, each said heating element comprising a substantially upright panel from at least one side of which there projects at least one plate-like heat transfer surface having its longitudinal axis substantially horizontal, said panels being detachably mounted side by side in a magazine and located so as to guide the yarns transversely o the length of the machine over the plate-like heat transfer surfaces* .. The yarn guiding means is effective to feed a plurality of yarns back and forth over or under the heat transfer surfaces , · the outward and return paths of any particular yarn or yarns being parallel or inclined one to the other. he panels may be slidably mounted in the magazine so as to be easily removable for purposes of cleaning, polishing, maintenance, replacement or repair. , The magazine may thus have partitions, guide rails or the like which define compartments transversely of the machine for accommodating the heating panels.

The magazine may also be constructed so as to act as a heat conserving or insulating device and a fume extractor.

A part of each heating panel can form a seal or cover to assist in retaining the heat within the magazine.

For a better understanding of the invention, however, reference should be made to the accompanying diagrammatic drawings which illustrate five typical and preferred heating unit arrangements and in which : -- Figure 1 is an end elevation; Figure 2 is a side elevation of a magazine shown accommodating two different forms of heating ιΛίίΦ^ panelj Figure 3 is a plan view equivalent to Figure 2; Figures 4 and 5 a∑*e end elevations of two different panel forms of heating Xtttfxt ; whilst Figures 6, 7» 8 and 9 are end elevations of four panels alternative arrangements of heating xuol&fe in a yarn processing machine .

Referring now primarily to Figure 1 there is shown a plurality of yarn supply bobbins 1 from which the yarn is unwound by a feeding device 2 and passed by guide rollers along a yarn heating path transversely of the machine between and against a series of individually removable electrical panels yarn heating :oxct*36 each comprised of a horizontal heat bar transfer element or fljeKtxscx3 which extends transversely from side to side of the machine.

The yarn then passes around a guide returning along the same yarn heating path in a parallel direction on through a false twisting device 5j through a second yarn feeding device 6 and passing to a processed yarn receiving bobbin 7.

In the opposite direction from the right side of the machine as shown in Figure 1 a supply of yarn is taken from the supply bobbin through the yarn feeding device over the yarn heating surface and through the false twist device, through the second yarn feeding unit and onto the receiving bobbin for processed yarn. respectively so that they can be individually removed and replaced as will be apparent from Figure 2 and alternate panels are removable from the same side of the machine. The left and right ends of Figure 2 indicate different forms of heating panel which are shown in greater detail in Figures 4 and 3.

Referring now to Figure 4» wherein the yarn guiding means, for purposes of clarity, are not shown the yarn heating panels comprise vertical standards 11, 16 which each support a series of parallel horizontal hollow bars 12* the upper parts of which constitute heat transfer surfaces. Bach such bar contains insulated sheathed resistance wire elements 13 supplied by a relatively low voltage electric current.

The heating panel standards 11 pick up the current by means of pairs of contacts 14 through posts 13» Each heating panel can be readily removed for cleaning purposes. Bach alternate yarn heating, panel 11 and 16 is insertable and removable from the same side of the machine, every other intermediate unit being insertable and removable from the Opposite side of the machine.

Figure 3 shows a pair of heating panels of alternative preferred suitable design and each comprised of a vertical standard to which there is attached a series of four heat transfer bars each providing a pair of inclined plate-like heat transfer surfaces 18. Four of these surfaces to one side of the standard, heat yarn supplied from one side of the machine whilst the four surfaces on the other side of the standard heat yarn supplied from the opposite side of the machine. In Figure 3 the yarn guides have been omitted from the view of one heating panel to simplify the drawing.

Electrical resistance heating elements 19 are insetted as An advantage of this design is that a single XMxdx panel panel carries eight heating surfaces per ¾¾ϊ¾ instead of four as shown in Figure and the heating elements, thermistor and thermocouple are common to all eight heating surfaces.

A further advantage is that the yarn is less likely to drag on the inclined heating surface for although the yarn will be held into contact with the heater face by gravity only a component of the weight is bearing onto the heater surface, a feature which is useful when heating fine denier yarns under low tension.

An alternative to be used when several yarns are to be processed whether in combination or not is shown in Figure 6 as follows : - The yarn from two or more supply bobbins 1 is fed vi the yarn feeding device 2 over the various yarn heating bars 3 pQxackssx. 3 around the guides 4 returning over the respective yarn heater paths through the false twisting device 5 via the second yarn feeding device 6 onto the yarn receiving reels 7· An alternative for two or more yarns over the same bars yarn heating ixiJbee is shown in Figure 7 where two or more yarns travel outwards from the supply bobbin along the lower yarn heating plate 3 around the guide returning along the upper yarn heating path 3 through the false twist unit 5 through the second yarn feeding device 6 and onto the receiving reel 7 for processed yarn.

A further alternative is shown in Figure 8 where the yarn to be processed is fed from the supply bobbin 1 through the yarn feeding device 2, over the upper side of bar the yarn heating Jfkbodxe 3 around the guide ¾ returning along the opposite side of the yarn heating unit through the false twisting device 5 via the second yarn feeding yarn to be processed travels outwards from the supply bobbin 1 through ,the yarn feeding device 2 over the yarn heating bar 3 around the guide 4 on through the false twisting device 5 through the second yarn feeding device 6 and onto the receiving reel 7 for processed yarn. In this case it is to be noticed that the heated yarn is passed around the guide 4 returning in "free air" off the yarn heating path as shown.

Further possible arrangements would be ones in which Figures 1 to 9 inclusive are inverted so that the yarn supply bobbins are above the yarn heating bars and likewise the yarn receiving reels are below the yarn heating bars.

It should be apparent from the foregoing that since the heating bars are directed horizontally and are transversely of the machine, and. may be s idably Inserted for example, they occup little space both in vertical planes and lengthwise of the machine as a whole.

Space which is unusable in previous machines can now accommodate the yarn supply bobbins and in addition the yarn feeding device and its driving means can be mounted at a more convenient level above the floor.

Also, in view of the facility now afforded whereby the yarn may be fed and returned over the same heating bar or a different one to the same side of the machine the length of the yarn being heated at any given time can be increase substantially without affecting the height of the machine.

Further, a horizontally directed yarn heating bar is only subject to convection over its cross section, is not subject to a heat gradient along its length and the temperature of it should not vary in the path of feed or return of any particular yarn or yarns. More uniform heating of yarn is thus ensured. ^ Since the yarn which traverses a horizontal heating path is not subject to varying convection effects along its length and since the heat transfer to the yarn does hot depend to the same extent upon the tension in the yarn for its contact with the heating surface but rather on the force of gravity the yarn can be treated when it is in a more relaxed condition. This is very useful when part of the yarn process is to obtain maximum crimp contraction or shrinkage in the yarn since it is then necessary that the yarn should pass over the heating surface under minimum tension to enable the contraction to take place freely.

It is possible that a machine according to the present invention could produce four times the number of processe yarns for a given machine floor area or machine cubic capacity then has hitherto been practicable. This should result from the compact arrangement of the heating panels within the magazines, from closely adjacent vertically separated heating f paths and from a increase In throughput speed.

Also the proximity of the yarn heating units or plates within magazine reduces heat losses to atmosphere and promotes uniformity of temperature throughout the magazine and between the heating paths.

In a machine according to the present invention the yarn heating panels can be readily removable from the machine for examination and to faeliitate cleaning and repolishing of the heated surfaces. The vapours are not held in dose proximity to the heating paths and can to some extent disperse in the atmosphere within the magazine where they are draw away at low pressure and condensed into a vessel in some other part of the' machine. cleaning, polishing and inspection of them and the open nature of the paths permits easy and reliable threading when necessar .

Claims (9)

1. A yarn-processing machine comprising yarn feed means and yarn receiving means arranged in rows along the length of the machine* and a plurality of heating elements extending transversely of the length of the machine between the rows , each said heating element comprising a substantially upright panel from at least one side of which there projects at least one plate-like heat transfer surface having its longitudinal axis substantially horizontal, said panels being detachably mounted side by side in a magazine, and being located so as to guide the yarns transversely of the length of the machine over the plate-like heat trasfer surfaces·

2- A yarn-processing machine as claimed in claim 1 in which . said magazine is elongated In the direction of the length of the machine*

3. A yarn-processing machine as claimed in claim 1 or 2 in which each said yarn-heating panel is elongated in the direction of the width of the machine*

4. A yarn-processing machine as claimed in any of claims 1 to 3 in which each said yarn-heating panel is slidably mounted in said magazine*

5. A yarn-proceasing machine as claimed in any of claims 1 to 4 in which said yarn-heating panels are insertable into the magaaine alternately fro opposite sides of the machine.

6. A yarn-processing machine as claimed in any of claims 1 to 3 in which the plate-like heat transfer surfaces form part of hollow bars projecting in tiers from at least one side of each said panel·

7. A yarn-processing machine as claimed in claim 6 in which said hollow bars have external surfaces located in horizontal planes. I

8, A yarn-processing machine as claimed in claim 6 in which said hollow bars have upper surfaces located in planes inclined to the horizontal*

9. A yarn-processing machine as claimed in any of claims 6, 7 or 8 in. which the hollow heating bars are internally heated by electric resistance heating elements and regulated b temperature-sensing and controlling device. 1). A yarn-processing machine as claimed in any of claims 1 to 9 in which said magaeine is proyided with a fume-extraction device.