Title of Invention

"AN IMPROVED DEVICE AND METHOD FOR MANUFACTRING A SPIRAL COIL STRUCTURE"

Abstract

The present invention relates to an improved device for manufacturing a spiral from a monofilament polymeric material comprising: a bobbin rotatably mounted on a spindle, having the said monofilament material wound on it; a mandrel rotatably mounted on a frame passing through the said spindle, enabling the bobbin to rotated clockwise or anticlockwise; a revolving winding head fixed to one end of the said mandrel to produce continuous length of monofilament spirals; means as herein described for maintaining a desired temperature zone around the said device; a drive means as herein described attached to the said mandrel rotating the spindle at a predetermined rpm; a heater box provided over the said mandrel to heat set the said spiral; and means as herein described for cooling the said spiral.

Full Text

The present invention relates to an improved method and apparatus for manufacturing a spiral coil structure used for and in the formation of spiral link belts. The spiral link belts formed from the spiral coil structures display an 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. Surface of spiral link belt thus formed is even, flat and extremely smooth. Inspite of its very open appearance, spiral link belt actually provides a greater area of contact with paper than woven monofil fabrics. This provides even contact with the cylinder and an effective drying. In order to display the desired characteristics of a link belt, the spiral coil structures play an important part. In the prior art known for the formation and manufacture of the spiral coil structure, the coil structure is manufactured by winding a strip or strand of the thermoplastic material around a mandrel of appropriate cross sectional shape and dimensions, and to heat the material whilst wrapped around the mandrel to set the strand in the coiled configuration. The coil is thereafter removed from the mandrel overend, the resulting coil then being assembled with other like and alternate oppositely handed coils into a link belt. A known method of forming such a coil is to wind a strand of thermoplastic material from a bobbin supply thereof onto a rotating mandrel, heat the coil strand whilst on the mandrel and then remove the coil over end from the mandrel. Another known method is to wind a strand of thermoplastic material from a bobbin supply thereof onto a stationary mandrel by means of a flyer, heat the coiled strand whilst moving it longitudinally of the mandrel and then remove the coil overend from the mandrel. The means for moving the coiled material longitudinally of the mandrel comprises a sleeve surrounding the mandrel and driven so as to reciprocate longitudinally thereof whilst abutting the end most wrap of the strand material around the mandrel. The movement of the coil longitudinally of the mandrel through the heating zone may be controlled by means of one or more helically ribbed rollers disposed parallel to the mandrel and in contact with the outer surface of the coil. Alternatively, the movement of the coil may be resisted by means of a small local protrusion on the mandrel adjacent the downstream end thereof, and over which the coil must pass before being removed from the mandrel, thus ensuring that each wrap of the strand is pushed against the trailing end of the coil by the reciprocating sleeve. The coils for use in the manufacture of link belts are of oval or flattened cross-section, and the mandrels used in the aforementioned methods are of appropriate oval or flattened cross section. However, such coils, when removed from the mandrel after manufacture, may exhibit a degree of secondary twisting, i.e., the major axes of the coil at successive sections along its length are not in a common plane, and in consequence, the coil does not 'lie flat' on a plane surface. This phenomenon which is thought to be caused by the relaxing of the coil on the mandrel whilst cooling after the heat setting stage, tends to make assembly of such coils into a link belt difficult and, furthermore, the resulting link belt may be distorted. This distortion of the link belt, caused due to secondary twisting, is a major drawback in the conventional methods. To overcome these drawbacks associated to secondary twisting, the improved process comprises the steps of winding a strand of polymeric material onto a first section of a mandrel of a given cross section to form a coil followed by heating the coil whilst moving the said coil longitudinally. Thereafter, the coil formed is cooled and twisted in its coiled form. However, there are certain inherent disadvantages associated with this method specifically relating to heat and mechanical or friction loss during the formation of the spiral coil. Further, a motor employed for forming the spiral coils of required diameter employs an AC motor which though performs the function well but at the same time its speed for different spindles can not be altered as per the requirements of each device. Therefore employment of an AC motor does not enable optimum utilisation of the input energy. The present invention aims to overcome the drawbacks existing in the prior art and relates to an improved method of producing a coil for use in the manufacture of a link belt wherein the improved method not only precludes secondary twisting but also employs use of specific motors which ensure maximum stability of the coil structure thus formed. The employment of variable DC drive enables maximum exploitation of the input energy with minimum heat and mechanical/ friction loss. The improved method of the present invention comprises winding a strand of polymeric material onto a first section of a mandrel of a given cross section to form a coil, heating the coil so formed whilst moving said coil longitudinally of said first section, passing said heated coil through a zone where it is cooled and twisted, in its coiled form, in a twist direction tending to reduce the cross section of the coil, whilst supporting the coil by a second section of said mandrel of a reduced cross section in comparison with said first section, and removing said coil from said mandrel overend thereof. The movement of the strand of thermoplastic material with the mandrel is based on the rotation per minute speed (RPM). RPM of a spindle defines the rate at which the coiling of the said strand of polymeric material occurs. The RPM is adjusted as per the requirements as well as the heat and mechanical or friction loss incurred by each spindle. This adjustment of RPM as per desired parameters enables minimising the heat and mechanical or friction loss and therefore the energy loss. This manipulation of RPM is facilitated by a variable DC drive employed in the device of the present invention. The DC drive helps in calculating the required motion speed in accordance with the heat or mechanical or friction loss effected by each spindle. RPM of DC motor is accordingly controlled and varied. The present invention also provides apparatus for use in the production of a coil by the above mentioned method, comprising a mandrel having a first section of a given cross section and a second section having a reduced cross section in comparison with said first section, means of winding a strand of polymeric material onto said mandrel in first section to form a coil, means for moving said coil so formed longitudinally of said mandrel, means for heating said coil in first section, and means for maintaining a twist in said coil as it passes along said second section in such manner that said twist maintains said coil in its coiled form and is in such direction as to tend to reduce the cross section of the twisted coil. The apparatus of the present invention simultaneously produces spiral coil of two different directions. Said means for maintaining a twist preferably comprises a first restraint and a second restraint spaced apart from said first restraint, whereby the twist is maintained between the first and second restraint. In a preferred arrangement, said twist restraint is provided at the downstream end of the coil therealong and the second restraint comprises a bar extending transversely of the path of the coil and provided downstream of the mandrel. Preferably also a strand supply bobbin is provided and is driven in rotation co-axially with said mandrel. The second section of the mandrel may taper towards its free end or may comprise a parallel sided bar, for example, a round bar. A sleeve may be provided on said mandrel and driven so as to reciprocate longitudinally thereof, and to abut the trailing wrap of the coil so as to move the coil longitudinally of the mandrel over the first and second sections and off the end of the mandrel. The spirals are generally made through vertical or horizontal delivery. The present invention preferably employs a vertical method of delivery of the monofilament. Continuous length of monofilament spirals are delivered and spirals are produced on mandrels using revolving winding heads. As the spirals are pushed up the mandrel they pass through heating zone where they are heated. The heated coil is thereafter allowed to cool and is guided down to a collection can. Spirals of opposite hands are preferably produced simultaneously employing the process and apparatus of the present invention. For manufacturing spirals of opposite hands at the same time, one mandrel is given clockwise rotation while the other mandrel is provided anticlockwise rotation. Further, the process of manufacturing the spiral structure is carried out under controlled cold temperature and under dust free atmosphere. The controlled temperature condition is essential for forming a continuous spiral of desired length. Accordingly the present invention relates to an improved device for manufacturing a spiral from a monofilament polymeric material comprising: a bobbin rotatably mounted on a spindle, having the said monofilament material bound on it,; a mandrel rotatably mounted on a frame passing through the said spindle, enabling the bobbin to rotate clockwise or anticlockwise; a revolving winding head fixed to one end of the said mandrel to produce continuous length of monofilament spirals; a drive means attached to the said mandrel rotating the spindle at a predetermined rpm; a heater box provided over the said mandrel to heat set the said spiral; means for cooling the said spiral; and means for maintaining a desired temperature zone around the said device. The present invention further relates to an improved process for manufacturing a spiral from a monofilament polymeric material as claimed in claim 1, comprising winding a strand of polymeric material onto a first section of a mandrel of a given cross section to form a coil; heating the said coil thus formed whilst moving the said coil through a heating zone; cooling the coil while maintaining the twist inserted in the coil whilst supporting the coil by a second section of a mandrel of reduced cross section as compared to the said first section of the said mandrel; removing the said coil from said mandrel overend thereof; controlling the movement of the said mandrel and the rpm of the mandrel by means of a drive means under a cold atmosphere. The present invention and the main embodiments of the present invention can be understood in a better and explicit manner with reference to the accompanying drawings. These drawings are used as a reference in context to describing various aspects of the present invention and these do not restrict the broad scope of the present invention. Figure 1 specifies a spiral winding device, i.e., an apparatus for producing the spiral coil structure as described in the present invention. Figure 2 shows a part of the arrangement shown in figure 1 drawn to a larger scale. Figure 3 and 4 shows front elevation of a coil winding apparatus in accordance with the present invention. Referring now to the drawings, there is shown a supply bobbin 1 rotatably mounted on a spindle 2 through which passes a fixed mandrel 3 itself mounted on a frame 4. The bobbin spindle 2, and thus the bobbin 1 mounted thereon is rotatably driven by means of a drive belt 5 engaging a pulley 6 secured to or integral with the bobbin spindle 2. On the bobbin 1 is a supply of thermoplastic material in the form of a strand 7. A fixed flyer spindle 8 is provided coaxially with and adjacent the bobbin spindle 2 and carries a flyer head 9 freely rotatable thereon to wrap the strand 7 around the mandrel 3 at a first section 10 thereof on rotation of the bobbin, thus forming a coil 11. A friction pad 26 carried by the fixed flyer spindle 8 bears on the rotatable flyer head 9 to exert a light braking effect thereon. The drive belt 5 is driven by a DC motor where the speed of the motor, i.e., RPM provided to the device is manipulated as per the desired requirements. The heat and mechanical or friction loss suffered by each spindle is different during a process. The difference in heat and mechanical or friction loss by each spindle therefore necessitates that the RPM of each spindle be differed as per the requirements. This is made feasible by the DC drive used in the device of the resent invention. Slidably mounted on the mandrel 3 is a sleeve 12, the movement of the sleeve 12 is longitudinally of the mandrel 3 being limited by means of pins 13 secured to the mandrel 3 and extending into axially aligned slots 14 in the sleeve 12. Between the upper mots of the pins 13 and a shoulder 15 of sleeve 12 there is a spring 16 which urges the sleeve downwardly. The lower surface 17 of the sleeve 12 there is a spring 16 which urges the sleeve downwardly. The lower surface 17 of the sleeve 12 is formed as a cam followed surface and angularly spaced ball cams 18 on the upper surface of the flyer head 9 by the flyer spindle 8 through a friction pad drive causes the sleeve 12 to rise and fall under the action of the cam and follower arrangement as defined by surface 17 and the ball cams 18, and the force of the spring 16. The upper end 19 of sleeve 12 abuts the coil 11, and in consequence, the vertical movement of the sleeve 12 causes the successive winding of the strand 7 in the coil 11 to be moved progressively upwardly. The multiple ball cams 18 causes a corresponding number of reciprocation's of sleeve for each revolution of the flyer head, thus to ensure that the successive turns of the oil be closely together and the resultant coil has a constant helix angle. Above the sleeve 12 and surrounding the first section 10 of the mandrel 3 is a heater 20 having a heating element therein. The coil 11 is thereby heated as it passes along the first section 10. At this first section 10 the cross section of the mandrel 3 is substantially constant, though subject to a slight taper, and is formed by three round rods subject to a slight taper, and is formed by three round rods secured to each other longitudinally, the central rod being of slightly greater diameter than the two outer rods and the grooves between the outer rods being suitably filled to provide an oval cross section. If referred, the mandrel, at least in section 10, may comprise a single rod or bar ground to give requisite cross section. At the downstream end of section 10 the outermost bars are profiled to form a restraint 21, on diametrically opposed sides of the central bar so as to resist the passage of the coil along the mandrel 3 and ensure that each successive wrap of strand 7 around the mandrel 3 is pushed by sleeve 3 against the previous wrap one each reciprocation thereof. Having passed the restraint 21 the coil 11 passes along a second section 22 of the mandrel 3, formed by a rod of reducing cross section provided as a continuation of the central rod of section 10 so that the cross section of section 22 is less then that of section 20. During the passage of the coil 11 along this section 22, the coil rolls and is eventually pushed off the free end 23 of the mandrel and fed to a receiving can 24. Before feeding the leading end of the coil 11 to a receiving can 24, the length of the coil 11 extending along section 22 and off the end 23 is given a desired level of real twist, the restraint 21 and off the end 23 is given a desired level of real twist, the restraint 21 and the relatively close fit of the coil 11 around the mandrel 3 in section 10 precluding the twist being transmitted to that length of coil existing in section 10. The twist is inserted so as to tend to reduce the section of the coil 11, this being allowed by the smaller cross section of the mandrel 3 in section 22 and, in so far as the twist extend beyond the restraint, by the reducing cross section thereof in section thereof in section 10. After insertion of the real twist in the coil 11, the leading end thereof is passed around bar 25, making about two wraps therearound, and then fed to the receiving can 24. The bar 24, which constitutes a second restraint and cooperates with restraint 21 to form means for maintaining a twist in the coil may be rotated in order to facilitate such forwarding of desired. Alternatively, other feed means for progressing the coil may be provided if desired. The device of the present invention is preferably placed and run in a controlled temperature zone to give most suitable spiral formation of definite size of spiral. The controlled temperature reduces the statistical electricity generation and provides a dust free working. Further, induction of DC drive to the device of the present invention facilitates an even output from each device. WE CLAIM:- 1. An improved device for manufacturing a spiral from a monofilament polymeric material comprising: a bobbin rotatably mounted on a spindle, having the said monofilament material wound on it; a mandrel rotatably mounted on a frame passing through the said spindle, enabling the bobbin to rotated clockwise or anticlockwise; a revolving winding head fixed to one end of the said mandrel to produce continuous length of monofilament spirals; means as herein described for maintaining a desired temperature zone around the said device; a drive means as herein described attached to the said mandrel rotating the spindle at a predetermined rpm; a heater box provided over the said mandrel to heat set the said spiral; and means as herein described for cooling the said spiral. 2. An improved device for manufacturing a spiral from a monofilament polymeric material as claimed in claim 1, wherein the said drive means are DC drive. 3. An improved device for manufacturing a spiral from a monofilament polymeric material as claimed in claim 1, wherein the said mandrel has a first section oi~ a given cross section and a second cross section having a reduced cross section in comparison with the first cross section. 4. An improved device for manufacturing a spiral from a monofilament polymeric material as claimed in claim 1, wherein the said heating element is electronically controlled heating device. An improved device for manufacturing a spiral from a monofiiaineni polymeric material as claimed in claim 1, wherein the said controlled temperature is preferably achieved by placing the device in a controlled temperature zone. 6. An improved device for manufacturing a spiral from a monofilament polymeric material as claimed in claim 1, wherein the said left handed coil and right handed coil are wound simultaneously. 7. An improved process for manufacturing a spiral from a monofilament polymeric material as claimed in claim 1, comprising winding a strand of polymeric material onto a first section of a mandrel of a given cross section to form a coil; heating the said coil thus formed whilst moving the said coil through a heating zone; cooling the coil while maintaining the twist inserted in the coil whilst supporting the coil by a second section of a mandrel of reduced cross section as compared to the said first section of the said mandrel; removing the said coil from said mandrel overend thereof; controlling the movement of the said mandrel and the rpm of the mandrel by means of a drive means under a cold atmosphere. 8. An improved process as claimed in claim 7, wherein the said rpm of the mandrel is controlled by a DC drive means. 9. An improved process as claimed in claim 7, wherein the said coil is manufactured under a cooled atmosphere and clean environment. 10. An improved process as claimed in claim 7, wherein one of the said mandrel moves clockwise whilst the other mandrel moves anticlockwise to simultaneously form right handed and left handed coils simultaneously. 11. An improved device for manufacturing a spiral from a monofilament polymeric monofilament material substantially as herein before described with reference to the accompanying drawings. 12. An improved process for manufacturing a spiral from a monofilament polymeric monofilament material substantially as herein before described with reference to the accompanying drawings.

Documents:

3116-del-1998-abstract.pdf

3116-del-1998-claims.pdf

3116-del-1998-complete specification (granted).pdf

3116-DEL-1998-Correspondence-Others (09-02-2010).pdf

3116-del-1998-correspondence-others.pdf

3116-del-1998-correspondence-po.pdf

3116-del-1998-description (complete).pdf

3116-del-1998-drawings.pdf

3116-del-1998-form-1.pdf

3116-del-1998-form-19.pdf

3116-del-1998-form-2.pdf

3116-del-1998-form-26.pdf

3116-del-1998-form-4.pdf

3116-DEL-1998-GPA-(09-02-2010).pdf

3116-del-1998-petition-137.pdf

3116-del-1998-petition-others.pdf