Title of Invention

AN APPARATUS FOR PRODUCING UNI-DIRECTIONAL PREPREG TAPE BY SOLUTION IMPREGNATION METHOD

Abstract

An apparatus for producing uni-directional prepreg tape by solution impregnation method is described. Solution impregnation method is employed for manufacturing UD (Uni-Directional) prepreg tape. The scheme of rovings and prepreg (2) transport in the UD prepreg production line is shown in Figure 1. Manufacturing UD prepreg tape involves a complex series of operations, including unwinding of rovings (2), convergence of the rovings (2), impregnation with resin solutions, convective-radiative drying, and winding of prepreg along with release film onto the bobbins. The multiple rovings (2) unwind from the creels mounted in the stand (1) and pass through a convergent stand (3) and finally through a collimator (4) to form a free-rovings web of required width. The free-rovings web comes to the impregnation bath (5) containing the resin solution, inside which stationary rolls [(14) & (15)] are mounted. Then impregnated tape is squeezed through dies (16) to form the tape to required thickness and width. The tape goes to the drying tower (6), where the organic solvent vapours are removed and the resin gelling occurs.

Full Text

THE PATENT ACT 1970 (39 of 1970) & The Patents Rules, 2003 PROVISIONAL / COMPLETE SPECIFICATION (See section 10 and rule 13) 1. TITLE OF THE INVENTION An apparatus for producing uni-directional prepreg tape by solution impregnation method 2. APPLICANT (a) NAME : Larsen and Toubro Ltd. (b) NATIONALITY.: Indian Company, registered under the provisions of the Companies Act, 1956 (c) ADDRESS : L&T House, Ballard Estate, Mumbai, 400 001 . Maharashtra State, India 3. PREAMBLE TO THE DESCRIPTION PROVISIONAL The following specification describes the invention, COMPLETE The following specification particularly describes the invention and the manner in which it is to be performed. 27 MAR 2007 Present invention relates to an apparatus and process for producing uni-directional prepreg tapes. More particularly present invention relates to an apparatus and process for producing UD prepreg tapes, by solution impregnation method. The tapes produced by the method finds wide spectrum of applications in tape lay-up and winding. In prior art unidirectional prepreg tapes with hot melt technique was popular which has its own limitations. Hot melt technique is suitable only for resin systems which forms hotmelts. It was seen that all resin systems cannot be converted to hotmelt form. The present invention provides an apparatus which is suitable for solution impregnation method. According to the knowledge of the applicant no other relevant prior art is available for this purpose. The object of the present invention aims at developing a plant and process for producing uni-directional prepreg tapes using solution impregnation method. It is also the object of the present invention to over come the limitations of the prior art wherein the apparatus is suitable only for hot melt method. The invention will now be described with reference to the drawings of the accompanying specification wherein the salient features have been shown with suitable numerals and referred to appropriately in the following description. Drawing consists of 8 figures. Figure 1 apparatus for production of uni-directional prepreg according to the present invention. Figure 2 is top view of the creel-mounting stand. Figure 3 is side view of the convergence stand. Figure 4 is side view of the collimator 2 Figure 5 is resin impregnation bath. Figure 6 is side view of S-wrap puller. Figure 7 is side view of winding device. Figure 8 is drying tower. Solution impregnation method is employed for manufacturing UD (Uni-Directional) prepreg tape. The scheme of rovings and prepreg transport in the UD prepreg production line is shown in figure 1. Manufacturing UD prepreg tape involves a complex series of operations, including unwinding of rovings, convergence of the rovings, impregnation with resin solutions, convective-radiative drying, and winding of prepreg along with release film onto the bobbins. The multiple rovings (2) unwind from the creels mounted in the stand (1) and pass through a convergent stand (3) and finally through a collimator (4) to form a free-rovings web of required width. The free-rovings web comes to the impregnation bath (5) containing the resin solution, inside which stationary rolls [(14) & (15)] are mounted. Then impregnated tape is squeezed through dies (16) to form the tape to required thickness and width. The tape goes to the drying tower (6), where the organic solvent vapours are removed and the resin gelling occurs. Drawing of the tape with the required tension along the line is performed by means of the special puller device (7), which is equipped with a speed-stabilized drive. Release film (9) is fed from the roll to the driving shaft of the winding unit (8). Finally the prepreg along with the release film is wound on the bobbins mounted on the winding unit. Once the resin mix nears to exhaustion, fresh quantity of resin mix is fed Into the impregnation bath manually or automatically from feeding vessel. Now referring to figure 1 an apparatus for producing uni-directional prepreg tapes by solution impregnation method consists of the following units 1. Roving dispensing unit, 2. Roving convergence unit, 3. Impregnation unit, 4. Drying unit, and 5. Winding unit. Now referring to figure 2 of the accompanying specification, which is the roving dispensing unit. This unit includes unique stacking of roving creels (10) which, dispenses the fiber through tensioners (11) at required speed and with out any overlapping of the said fibers. The said tensioners (11) impart required tension in each of roving. The creels are arranged on a creel mounting stand (1) so that roving do not get abraded with each other during their passage. The said creel stand (1) is designed to dispense ail fibers in perfect juxtaposition with out any climbing effect. The creel stand was designed to take care of varying number of roving required for manufacturing different tape width. Now referring to figure 3 and 4 of the specification, which is, roving convergence unit consists of convergence stand (3) and collimator (4) placed after the roving dispensing unit as shown in fig.2. The said roving unit brings all roving to required width and to impart required equal tension to all roving. The convergence stand and collimator (4) are arranged to avoid sharp transition in the fiber path and intermingling of the roving. The convergent stand (3) consists of a board having number of holes to which smooth bush (12) is attached. The bush may be made up of ceramic or any other suitable material. The function of the bush is to reduce the friction between the fibre and the bush, there by reducing the fiber damage. The said reed (13) is having a comb like structure consisting of a frame having number of smooth wires (chrome plated steel or any other suitable material) between which converged roving pass through. The inclination of the collimator with respect to process line is very important as it decides the final roving convergence. The angle should be preferably kept around 25 - 30° with respect to the process line. 4 Now referring to figure 5, which is the impregnation unit. The said unit consists of (14) Guide roller (15) Impregnation roller and (16) Squeeze die. The said unit impregnates the converged fibre with uniform resin pick up and gives the desired resin content very precisely. The resin/hardener/solvent ratio is accurately controlled to give desired viscosity suitable for achieving controlled resin pick up. Smooth Die (16) (chrome-plated steel or any other suitable material) used ensures required thickness, width and uniform resin distribution in the tapes. The resin level in the impregnation bath has to be maintained 30 - 60mm from the center of impregnation roller (15). It is to be noted that higher or lower resin level changes the resin pick up which in turn leads to variation of resin content in prepreg. The said guide roller (14) is to properly direct converged rovings to the impregnation roller (15). The impregnated roving passes through the sqeeze die (16) assembly. The said squeeze die assembly consists of two smooth blocks (chrome-plated steel or any other suitable material) which can adjusted by means of a spring mechanism to various width and thickness depending on the tape dimension required. Now referring to figure 8, which is Drying Unit, consists of Stand (24), Insulation block (25), Thermocouple (26), Embedded heating element (27) and Blower (28). As seen in figure 8 precisely controlled inverted U curing tower bakes prepreg tapes to the required degree of B-staging. The inverted U tower is mounted on stand (24). The said tower consists of multiple zones and each zone is having separate temperature controls. The number of zones can be varied to process various resin systems. The temperature in each zone is sensed by thermocouple (26) that is connected to controller. Each temperature zone is having insulation blocks (25) with embedded heating element (27). The power control provided maintains the desired temperature profile accurately with in ± 3° C. The temperature of each zone 5 can be varied from 40 to 250 °C that makes it possible to process various resin systems. Each zone has doors for conveniently passing rovings at start of the process and to take corrective action when required. Inside the curing tower, four anti-stick guide rollers are provided to direct the impregnated tape. Three blowers (28) are provided in the said tower for continuous removal of solvent during B-stage curing. Two glass windows are also , ^ provided to continuously monitor the prepreg quality. Now referring to figure! 6, which shows pulling roller assembly (7), which consists of Pulling rollers (17), Bearing housing (18), Nip adjusting screw (19). Figure 7 shows Spool (22) and Spool mounting stand (23). The prepreg along with the release film is wound on the said spool (22) mounted on the winding unit. Unique Speed-stabilized DC drive is provided both for puller device and final winding through a chain driving system. There is also a provision to incorporate AC speed control and timer belt drive mechanism instead of above said DC speed control and chain drive mechanism. This drive provides uniform winding of the tapes along with the release film without any humps, wrinkles or folds. The S-wrap puller consists of two anti-stick rollers. The upper roller rotates in anti-clockwise direction where as the bottom roller rotates in clockwise direction. This mechanism gives the pulling action for prepreg tape. The nip gap of the rollers is adjusted by nip adjusting screws (19) to give the required tension to the prepreg tape (20). Break system can also be provided to the rollers to achieve the required tension in the prepreg tape. Since the prepreg tape is tacky, it is wound along with release film (21) from roll (9) on to a spool (22) mounted on spool mounting stand (23). For non-tacky i.e. dry prepreg tapes, release film will not be used. S-wrap puller is also provided with chilling arrangement, either by internal circulation of chilling media inside the rollers or by chilling pads on the rollers, 6 to arrest the advancement of the reaction in the prepreg tape to the same extent for various resin systems. A process for producing uni-directional prepreg tapes by solution impregnation method, the said method comprising the steps of: > unwinding of the roving from the creels (10) mounted in the creel mounting stand (1); > guiding the said roving to the roving convergence unit and passing the said roving through a convergent stand (3) followed by passing the roving through the collimator (4) forming a free-roving web of required width; > passing the said free-roving web through the impregnation bath containing the resin solution followed by passing the impregnated tape through squeeze dies (16) thereby forming the tape of required thickness and width; > passing the said impregnated tape through the drying tower thereby removing the organic solvent vapours and curing to the required B-stage; > drawing the said impregnated tape by means of puller (17) with required tension; and > winding the said tape along with a release film on the bobbins mounted on the winding unit. STATEMENT OF THIS INVENTION: An apparatus for producing uni-directional prepreg tapes by solution impregnation method comprises a roving dispensing unit (fig.2) consisting of a creel mounting stand (1), roving creels (10) which, dispenses.the fiber through tensioners (11) at required speed and without any overlapping of the fibre; a roving convergence unit consisting of a convergence stand (3) having a board consisting of plurality of holes with bush (12) attached to each of the holes for reducing the friction between the fibre and the said bush and a collimator (4) to bring all roving to required width and to impart 7 equal tension to all the said roving; further consists of a reed (13) in the form of a comb like structure consisting of a frame having plurality of smooth wires made of chrome-plated steel or the like material for passing of converged roving; thus converging the said roving by imparting required width and tension to the roving received from the said roving dispensing unit; a impregnation unit consisting of impregnation bath filled with resin and hardener to the level in the range 30 to 60 mm from the center of impregnation roller (15), a guide roller (14) for properly directing the converged roving to the said impregnation roller and a squeeze die assembly (16) capable of varying the width and thickness of the tape depending on the tape dimension required; capable of impregnating the converged fibre received from the said dispensing unit; a drying unit in the form of inverted 'IT tube consisting of multiple zones, each of the said zone having separate temperature controls and a insulation block (25) with embedded heating element (27) a thermocouple (26) to sense the temperature; the inverted U tower is mounted on stand (24); three blowers (28) are provided in the said tower for drying the said impregnated tape received from the said impregnated unit, and a winding unit (7) provided with a said speed-stabilized DC or AC drive for uniform winding of the said tape along with the release film without any humps, wrinkles or folds comprises of pulling rollers (17), bearing housing (18), nip adjusting screw (19), spool (22) and spool mounting stand (23); the prepreg along with release film is wound on the said spool (22) mounted on winding unit; speed stabilized drive is provided for puller device and final winding so as to provide uniform winding of the tapes along with the release film without humps and wrinkles; s-wrap puller is provided to impart pulling action for prepreg and consists of two anti-stick rollers; upper roller rotates in anti¬clockwise direction whereas the bottom roller rotates in clockwise direction; nip gap of the said rollers is adjusted by nip adjusting screws (19) so as to achieve required tension in the prepreg tape (20); only when the prepreg tape is tacky, it is wound along with release film (21) from roll (9) on to spool (22) mounted on spool mounting stand (23). An apparatus for producing uni-directional prepreg tape by solution impregnation method wherein the said squeeze die assembly comprises two smooth (chrome-plated steel or any other suitable material) blocks capable of adjusting by means of a spring mechanism. An apparatus for producing uni-directional prepreg tape by solution impregnation method wherein the said S-wrap roller is provided with chilling arrangement, the said chilling arrangement being any one selected from the group consisting of circulation of chilling media inside the rollers and provision of chilling pad on the rollers. An apparatus for producing uni-directional prepreg tape by solution impregnation method wherein a drying unit (6) in the form of inverted 'U' tube consisting of multiple zones, each of the said zone further comprises plurality of anti-stick guide rollers for guiding the said impregnated tape, glass windows for monitoring the prepreg quality; doors for conveniently passing rovings at the start of the process and to take corrective action when required and at least three blowers for removal of solvent. A process for producing uni-directional prepreg tapes by solution impregnation method, using an apparatus of the present invention, the said method comprising the steps of: i. unwinding of the roving from the creels mounted in the creel mounting stand; ii. guiding the said roving to the roving convergence unit and passing the said roving through a convergent stand followed by passing the 9 roving through the collimator forming a free-roving web of required width; iii. passing the said free-roving web through the impregnation bath containing the resin solution followed by passing the impregnated tape through squeeze dies thereby forming the tape of required thickness and width; iv. passing the said impregnated tape through the drying tower thereby removing the organic solvent vapours and curing to the required B-stage; v. drawing the said impregnated tape by means of puller with required tension ;and vi. winding the said tape along with a release film on the bobbins mounted on the winding unit. Various modifications and workshop alteration will be apparent to those skilled in the art from the aforesaid duplication, without departing from the nature and the scope of the invention. While the invention has been described and illustrated with respect to a typical plant and process for manufacturing of Uni-directional tapes which is the preferred embodiment in accordance with this invention, it will easily be apparent that the art disclosed here in is applicable to other plant and processes. WE CLAIM: 1. An apparatus for producing uni-directional prepreg tapes by solution impregnation method comprises a roving dispensing unit (fig.2) consisting of a creel mounting stand (1), roving creels (10) which, dispenses,the fiber through tensioners (11) at required speed and without any overlapping of the fibre; a roving convergence unit consisting of a convergence stand (3) having a board consisting of plurality of holes with bush (12) attached to each of the holes for reducing the friction between the fibre and the said bush and a collimator(4) to bring all roving to required width and to impart equal tension to all the said roving; further consists of a reed (13) in the form of a comb like structure consisting of a frame having plurality of smooth wires made of chrome-plated steel or the like material for passing of converged roving; thus converging the said roving by imparting required width and tension to the roving received from the said roving dispensing unit; a impregnation unit consisting of impregnation bath filled with resin and hardener to the level in the range 30 to 60 mm from the center of impregnation roller (15), a guide roller (14) for properly directing the converged roving to the said impregnation roller and a squeeze die assembly (16) capable of varying the width and thickness of the tape depending on the tape dimension required; capable of impregnating the converged fibre received from the said dispensing unit; a drying unit in the form of inverted 'U' tube consisting of multiple zones, each of the said zone having separate temperature controls and a insulation block (25) with embedded heating element (27) a thermocouple (26) to sense the temperature; the inverted U tower is mounted on stand (24); three blowers (28) are provided in the said tower for drying the said impregnated tape received from the said impregnated unit, and a winding unit (7) provided with a said speed- n stabilized DC or AC drive for uniform winding of the said tape along with the release film without any humps, wrinkles or folds comprises of pulling rollers (17), bearing housing (18), nip adjusting screw (19), spool (22) and spool mounting stand (23); the prepreg along with release film is wound on the said spool (22) mounted on winding unit; speed stabilized drive is provided for puller device and final winding so as to provide uniform winding of the tapes along with the release film without humps and wrinkles; s-wrap puller is provided to impart pulling action for prepreg and consists of two anti-stick rollers; upper roller rotates in anti¬clockwise direction whereas the bottom roller rotates in clockwise direction; nip gap of the said rollers is adjusted by nip adjusting screws (19) so as to achieve required tension in the prepreg tape (20); only when the prepreg tape is tacky, it is wound along with release film (21) from roll (9) on to spool (22) mounted on spool mounting stand (23). 2. An apparatus for producing uni-directional prepreg tape by solution impregnation method as claimed in claim 1 wherein the said squeeze die assembly (16) comprises two smooth blocks made of chrome-plated steel or the like material capable of adjusting by means of a spring mechanism. 3. An apparatus for producing uni-directional prepreg tape by solution impregnation method as claimed in claiml, wherein the said S-wrap roller (17) is provided with chilling arrangement, the said chilling arrangement being any one selected from the group consisting of circulation of chilling media inside the rollers and provision of chilling pad on the rollers. 4. An apparatus for producing uni-directional prepreg tape by solution impregnation method as claimed in claim 1, wherein a drying unit (6) in the form of inverted 'U' tube consisting of multiple zones, each of the said zone further comprises plurality of anti-stick guide rollers for guiding the said impregnated tape, glass windows for monitoring the prepreg quality; doors for conveniently passing rovings at the start of the process and to take corrective action when required and at least three blowers for removal of solvent. 5. A process for producing uni-directional prepreg tapes by solution impregnation method, using an apparatus claimed in claims 1 to 4 the said process comprising the steps of: i. unwinding of the roving (2) from the creels mounted in the creel mounting stand (1); ii. guiding the said roving (2) to the roving convergence unit and passing the said roving through a convergent stand (3) followed by passing the roving (2) through the collimator (4) forming a free-roving web of required width; iii. passing the said free-roving web through the impregnation bath (5) containing the resin solution followed by passing the impregnated tape through squeeze dies (16) thereby forming the tape of required thickness and width; iv. passing the said impregnated tape through the drying tower (6) thereby removing the organic solvent vapours and curing to the required B-stage; v. drawing the said impregnated tape by means of puller (17) with required tension ;and vi. winding the said tape along with a release film (21) on the bobbins (22) mounted on the winding unit. 6. An apparatus for producing uni-directional prepreg tape as claimed in 1 to Ar and as herein described with reference to the drawings of the accompanying specification. 7. A process for producing uni-directional prepreg tape as claimed in claim $ and as herein described with reference to the drawings of the accompanying specification. Dated this 20th Day November, 2004 M.D.Bhate Agent for applicant 14

Documents:

1100-mum-2003-abstract(27-03-2007).doc

1100-mum-2003-abstract(27-03-2007).pdf

1100-mum-2003-abstract.doc

1100-mum-2003-abstract.pdf

1100-mum-2003-canclled pages(27-03-2007).pdf

1100-mum-2003-claims(27-03-2007).doc

1100-mum-2003-claims(granted)-(27-03-2007).pdf

1100-mum-2003-claims.doc

1100-mum-2003-claims.pdf

1100-mum-2003-correspondence(27-03-2007).pdf

1100-mum-2003-correspondence(ipo)-(18-05-2007).pdf

1100-mum-2003-correspondence(ipo).pdf

1100-mum-2003-correspondence.pdf

1100-mum-2003-description(granted).doc

1100-mum-2003-description(granted).pdf

1100-mum-2003-drawing.pdf

1100-mum-2003-form 1(20-10-2003).pdf

1100-mum-2003-form 1.pdf

1100-mum-2003-form 18(22-01-2005).pdf

1100-mum-2003-form 18.pdf

1100-mum-2003-form 2(cancelled)-22-nov-2004.pdf

1100-mum-2003-form 2(granted)-(27-03-2007).doc

1100-mum-2003-form 2(granted)-(27-03-2007).pdf

1100-mum-2003-form 2(granted).doc

1100-mum-2003-form 2(granted).pdf

1100-mum-2003-form 2(provisional).pdf

1100-mum-2003-form 2(title page).pdf

1100-mum-2003-form 3(22-11-2004).pdf

1100-mum-2003-form 3(27-03-2007).pdf

1100-mum-2003-form 3-27-mar-2007.pdf

1100-mum-2003-form 3.pdf

1100-mum-2003-form 4(20-10-2004).pdf

1100-mum-2003-form 4.pdf

1100-mum-2003-form 5(22-11-2004).pdf

1100-mum-2003-form 5.pdf

1100-mum-2003-power of authority(04-04-2003).pdf

1100-mum-2003-power of authority.pdf

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