Title of Invention

''A PROCESS FOR THE MANUFACTURE OF A LINK BELT''

Abstract

A process for the manufacture of a link belt having a plurality of helical coils joined by a hinge wire of a thermoplastic monofilament material threaded through the interdigitated turns of such coils, comprising, arranging adjacently placed spirals of opposite hands in an interdigitated disposition, linking the spirals, threading a respective hinge wire through the interdigitated turns of each pair of adjacent coils, sealing the edges of the resultant link structure so formed, subjecting the said link structure with sealed edges to heat setting and suitable longitudinal tension; subsequently cooling the resultant link structure thus formed.

Full Text

The present invention relates to an improved spiral link dryer fabric and an improved process for manufacturing such spiral link dryer fibre and the spiral link dryer fabric thus manufactured. The main embodiment of the present invention resides in the spiral link dryer fabric which overcomes problem of seam wear and failure and seam making. This specific embodiment ensures that once joined on the machine the seam is identical to the fabric in all respects and also that the spiral link dryer fabric becomes effectively endless. The main object of the present invention is to produce a link belt of the aforesaid kind having improved dimensional stability and salvage strength as compared with known structures, the belt itself being substantially flat and the hinge wires being firmly fixed in position relative to the individual coils. This link belt fabric is produced for extensive use in paper manufacturing process and is also used in paper dying group. Besides paper industry, the link belt fabric finds various uses in different applications, such as it can be used as a conveyor or can be used for filtering of sewage water and various other uses. The surface of spiral link dryer fabric is even, flat and extremely smooth. In spite of its very open appearance, spiral link dryer fabric of the present invention actually provides a greater area of contact with paper than woven monofil fabrics. This provides more even contact with the cylinder and more effective drying. As known in the prior art, the coils are connected together in such a way that two successive turns of one coil receive a turn of adjacent coil therebetween with the said turn of the next adjacent coil in contact with and clamped between the flanks of the said successive turns by virtue of a spring like tension in the individual coils. However, the link belt thus manufactured does not show the adequate degree of dimensional stability. The present invention aims to overcome the problems associated with stability of the link belt fibre. The present invention therefore relates to an improved process for the formation of link belt fibre and defines an improved link belt thus manufactured. The process of the present invention produces a smooth, clean running fabric with at least 100% more contact area than woven monofilaments and an integral seam that eliminates marking. Various improved methods have been proposed in the past for the manufacture of link fibre. However, the problems related to permeability, stability, flexibility and wear resistance have persisted. The present invention aims to overcome these problems and provide a link felt fabric with a much better contact area than woven monofilaments and an integral seam that virtually eliminates marking. The present invention also relates to manufacturing link belts of the kind comprising a multiplicity of helical coils of a polymeric material arranged in adjacent interdigitated disposition and the link belts thus formed. The link fabric of the present invention has an extraordinarily long life span in hot, moist environments where large diameter round monofilament yarn provides ultimate resistance to hydrolysis and abrasion for longer fabric life. Further, a high degree of interlock is provided to the link felt fibre of the present invention which improves performance of fabric through resistance to bowing and distortion and offers exceptional dimensional stability. The improved link fabric of the present invention displays an improved drying rates due to efficient purging of moisture and as a result, runs drier than woven monofilaments at the same permeability. It is an easy to clean fabric which retains fewer contaminants than woven fabric. Another advantage of employing use of the link felt fabrics resides in repair work being easy due to all spiral construction. The spirals of polymeric monofilament of appropriate diameter are chosen to form the link belt. The selection of an appropriate diameter of a monofilament depends on the particular use or function that the link belt fabric shall be subjected to. Therefore as per the suitability and the applicability of the link belt, the dimensions of the monofilament are selected. Apart from these two dimensional monofilaments, high temperature grade as well as hydrolysis grade monofilaments are also used. Depending upon the dimensions of the monofilaments used for formation of the spiral, the joining wire of appropriate dimensions are selected. In a preferred embodiment, monofilaments of 0.6mm- 0.95 diameter are used with 0.50-0.60mm and 0.60-0.80mm monofilament spirals respectively. The thermal shrinkage of material used for making spirals is very high and particular degree of spin finish additive is to be applied for spiral making process. The thermal shrinkage of the material used as joining wire is relatively very low. Further, the permeability of each spiral link felt fabric can be varied as per the requirement. To vary the permeability of a link belt, polyester braided tape, polyester spun yarn, polyurethane foam and similar material is inserted inside the link belt so formed. The link belt formed and joined by the joining wire is thereafter sealed at the edges. The edge sealing compound is essential to bind the two side edges of the link fabric in machine running direction to arrest the fringes to come out with suitable compound. Preferably two component polyurethane compound is used as an edge sealing compound. The belt thus formed is thereafter subjected to heat treatment and stretching tension. To reduce permeability and to make non-marking smooth surface, a special kind of fibre is desired. The present invention defines a novel fibre where sheet of fibre is punched on link fabric on a needle punching machine employing special needles, after thermosetting of the link fibre. STATEMENT OF THE INVENTION According to the present invention there is provided a process for the manufacture of a link belt having a plurality of helical coils joined by a hinge wire of a thermoplastic monofilament material threaded through the interdigitated turns of such coils, comprising: arranging adjacently placed spirals of opposite hands in an interdigitated disposition; linking the spirals; threading a respective hinge wire through the interdigitated turns of each pair of adjacent coils; sealing the edges of the resultant link structure so formed; subjecting the said link structure with sealed edges to heat setting and suitable longitudinal tension; subsequently cooling the resultant link structure thus formed. The improved process for the preparation of the link belt fabric comprises formation of spirals in a spiral forming device which can be made by horizontal or vertical delivery, to increase productivity and quality. Preferably spirals are produced on mandrels using revolving winding heads. As the spirals are pushed up the mandrel they passed through heater box and allowed to cool and guided down to a collection can. Preferably left handed and right handed spirals are simultaneously formed. The same direction spiral can not be zipped together to form cloth. The machine produce even spirals with electronically controlled thermal fixation, which even when produced on different machines exhibits the same characteristics. The present invention can be understood in a better manner with reference to the accompanying drawings. These drawings act as an illustration of the device and the link belt of the present invention, however, does not restrict the broad scope of the present invention. Figure 1 depicts a spiral linking machine whereas figure 2 shows a device for inserting the hinge wires. Figure 3 shows a left and right handed spiral with hinge wires inserted. The present device for forming the spirals is preferably operated under controlled temperature zone to give most suitable spiral formation of definite size of spiral. To overcome individual loss of heater and mechanical/friction loss, D. C. drive is inducted to our machines so that out put of all the machines become even. The controlled temperature reduces the statistical electricity generation and provides dust free working. The spirals thus formed are thereafter joined on a joining or a spiral linking table where on one hand of the table linking arrangement is fixed. The spiral linking table employs use of a guide bar of predetermined size and also a pair of hand driven rollers. Spirals of alternate hand are linked together by placing inter digitated turns of adjacent coils and form a sheet of spirals. N number of spirals of alternate hands are guided through the guide plate and rollers. This N is defined by the requirements and the particular use to which the link belt is subjected to. On the other hand of the table there are N-l number of hinge wire guides and a roller. The hinge wires are fed to the guide tubes from a hinge wire creel and a hinge wire heater box. By the turn of the handle of rollers, N-l hinge wires are pushed forward through the N-l void space of N spirals and arrange to lock N spirals in form of nonportable sheet, called as Section. Length of the section is ascertained by the width of the fabric to be produced, after joining of one section with the other section, length of cloth is produced. In the spiral linking machines shown in figure 1, the weights (1), placed on weight rack (2) provide weight to the spirals and spirals are guided through the device with the help of a spiral guide bar (3) and spiral guide frame (4). A set of rollers, i.e., top roller (5) and bottom roller (6), press the incoming spirals into the flattened shape. Guillotine (7) having a blade (8) enables cutting of the spirals of desired length. The spiral winding device is operated by an operating handle (9). Further, after joining of the spirals hinge wires are inserted in voids between the spirals thus formed. For N spirals linked together, N-l hinge wires are required. As shown in the accompanying figure 2, the spirals are fed in the device for inserting hinge wires which are subjected to pressure, applied with the help of weights (10) placed on a weight rack (11). The rollers, help the movement of the spirals further. The top roller (12) is covered and therefore smooth whereas the bottom roller (13) is grooved. The hinge wires (14) are inserted in the voids between the linked spirals (14). Tubing lubrication slots (19) are provided for smooth movement of the spirals. Perspex cover (15), leveling screws (16) and alignment screw (18) are provided to attain the desired alignment of the spirals and for maintaining the leveling of the linked spirals thus formed. The present device is operated with the help of an operating handle (18). The joining table operation is again preferably carried out under controlled temperature zone to ensure controlled temperature as well as controlled humidity levels. This reduces development of statistical electricity during the friction of the spiral and metal parts. The table top can be wooden. However, the present invention preferably employs use of a laminated top table to reduce friction losses. The link belt so far formed is thereby made to undergo heat setting. The heat setting machine provides required tension, required surface speed and also the desired temperature. The link belt so formed is mounted on two cylinders, where one cylinder is fixed and other moves apart as per the length of the fabric. During the heat setting process a precise stretch is required to enable to move a predetermined length of belt at a desired speed so as to provide desired stretch to the link belt. Preferably 1/4" per minute of link belt is moved to keep required amount of tension in the belt and to avoid localised stretching. Tension is monitored with electronically controlled load cells provided in the device employed for heat setting the link belt. The main drive of the cylinder is again driven by DC drive means which provides desired surface speed. The link belt cloth passes through the gap of two electronically controlled infra red dark heaters and the surface temperature is controlled from room temperature to about 500°-800°C. The low thermal insertion of the infra red radiators produces the exact setting temperatures within seconds. The cloth is exposed to the same temperature from both sides and without contacting the said cloth with the heaters. Cooling of the link belts thus formed provide the spiral link belt fibre of desired length and stability. The link belt thus produced is flattened in cross section as compared to the cylindrical or oval spirals used as the starting material. Heat setting the spiral belt and the stretching results in deformation of the structure thereby providing required stability and rigidity to the link belt thus formed. WE CLAIM: 1. A process for the manufacture of a link belt having a plurality of helical coils joined by a hinge wire of a thermoplastic monofilament material threaded through the interdigitated turns of such coils, comprising: arranging adjacently placed spirals of opposite hands in an interdigitated disposition; linking the spirals; threading a respective hinge wire through the interdigitated turns of each pair of adjacent coils; sealing the edges of the resultant link structure so formed; subjecting the said link structure with sealed edges to heat setting and suitable longitudinal tension; subsequently cooling the resultant link structure thus formed. 2. The process as claimed in claim 1, wherein the said coils are formed of synthetic thermoplastic material. 3. The process as claimed in claim 1, wherein the said linking of the coils is carried by spiral linking device on a joining table. 4. The process as claimed in claim 3, wherein the said spiral linking device comprises of a set of rollers, top roller and bottom roller, and spiral guide frame and spiral guide bars are provided for smooth passing of the spirals from under the applied pressure, i.e., weights provided on a weight rack. 5. The process as claimed in claim 1, wherein the said threading of hinge wire is done by a hinge insertion device. 6. The process as claimed in claim 5, wherein the said hinge insertion device employs a pair of rollers; top roller and bottom roller, for pushing forward the N spirals and the N-1 hinge wires and where the hinge wires are fed to guide tubes from a hinge wire creel and a hinge wire heater box. 7. The process as claimed in claim 1, wherein the said heat setting the edge sealed link belt is done with the help of electronically controlled infra red dark heaters at desired surface temperature. 8. The process as claimed in claim 1, wherein the said coils are initially circular or oval in cross section and after heat setting acquire a flattened shape. 9. The process as claimed in claim 1, which further comprises insertion of polyester braided tape, polyester spun yarn, polyurethane foam and the like material is inserted in the link belt thus formed to vary the permeability. 10. The process as claimed in claim 1, wherein the said link belt so formed is punched on to a needle punching machine after thermosetting of the link fabric to acquire desired permeability. 11. A link belt comprising a multiplicity of helical coils joined by hinge wire of a thermoplastic monofilament material threaded through the interdigitated turns of such coils when manufactured by the process as claimed in claim 1 . 12. A process for manufacturing a link belt substantially as herein before described with reference to the accompanying drawings.

Documents:

3117-del-1998-abstract.pdf

3117-del-1998-claims.pdf

3117-DEL-1998-Correspondence-Others (09-02-2010).pdf

3117-del-1998-correspondence-others.pdf

3117-del-1998-correspondence-po.pdf

3117-del-1998-description (complete).pdf

3117-del-1998-drawings.pdf

3117-DEL-1998-Form-1.pdf

3117-del-1998-form-19.pdf

3117-del-1998-form-2.pdf

3117-del-1998-form-26.pdf

3117-del-1998-form-4.pdf

3117-DEL-1998-GPA-(09-02-2010).pdf

3117-del-1998-gpa.pdf

3117-del-1998-petition-137.pdf