Title of Invention

"A FIBER WINDING APPARATUS"

Abstract

This invention relates to a fiber winding apparatus comprising a brake and spool unit (1) for controlling the tension applied to the fiber during a winding operation, a traversing unit for providing a transverse motion to the fiber, a chuck unit (3) for winding the fiber from said transverse unit on to a mandrel unit, said chuck unit holding the mandrel unit, said mandrel unit having a piezo electric eylinder for winding of the fiber. Said brake and spool unit (1) comprising a rotatable shaft (8), one side of a sid shaft (8) connected to a brake drum (9) and the other side connected to a spool (100, said brake drum (9) being capable of rotating between two brake shoes (33) & (34), said traversing unit (2) comprising a lead screw (11) connected to a thyrister controller DC MOTOR (12), said lead screw (11) connected to a carriage (14), a load cell connected to said carriage (14)and limit switches mounted on the either sides of said carriage (14) to control the winding length of the piezo-electric cylinder (7) of said mandrel unit (5), said chuck unit (3) comprising a 3-jaw chuck (18) powered by a thyrister controlled DC motor (19), said 3-jaw chuck (18) connected to said motor (19), said 3-jaws chuck (18) holding said mandrel unit (5) using the jaws and capable of rotating by said motor (19) to wind the fiber over the circumference of the said piezo-electric cylinder (7) of said mandrel unit (5), a tail stock unit (4) comprising a bed (21) for sliding the tail stock (22) along the axis of rotation of said 3-jaws chuck (18) and capable of taking the leads of the piezo-electric cylinder (7) of said mandrel unit (5) for the charge measurement, said mandrel unit (5) comprising said piezo-electric cylinder (7)held by clamping plates (23) & (24) and nuts (28) & (29) and further connected to the mandrel shaft (27), slip rings (25) & (26) and carbon brushes (30) & (31), said piezo-electric crystals connected to standard digital multi-meter through electrical leads, a control unit (6) comprising for digital display of the speed of the said DC motors (12) & (19) indicating the pitch of the winding.

Full Text

FIELD OF INVENTION This invention relates to a fiber winding apparatus for winding fibers over the circumference of cylinders particularly piezo-electric cylinders. PRIOR ART Fiber winding is a specialized process in the field of pressure vessel technology. Fibers like glass fibers, carbon fibers, Kevlar fibers etc., which have higher tensile strength than metals for the same weight, are used for making shells over the metal cylinders. For example, glass fiber wound metallic bottles are used in the spacecraft for carrying liquids under pressures where high strength to weight ratio is highly appreciated. Piezo-electric cylinders are used as the active transduction material in the electro-acoustic transducers. During its operation as a transducer, the piezp-electric material experience compression and tension forces cyclically undef'the'" influence of external electrical charge. The piezo-electric material is basically a ceramic and it is very fragile when under tension. During any under water application, shock loads due to underwater explosions may cause the piezo¬electric cylinders to experience tensile stress beyond the limits. As such, it becomes essential to provide certain amount of circumferential pre-stressing to the ceramic so that it compensates the tensile stress developed due to shock pulses of underwater explosions. Pre-stressing of piezo-electric cylinders in the hoop mode is achieved by winding fiber yarn/roving over the circumference under tension. A coating of epoxy resin is applied between each layer to give the required bonding between the fibers. The pre-stressing process requires the tension in the yarn to be monitored and controlled in a continuous manner. Similarly, the extent of hoop stress developed in the piezo-electric cylinders is also to be monitored and controlled in a like wise manner. Electric charge developed between the two electrode surfaces during circumferential compression of rings/cylinders is an indicator of the extent of the stress induced. Use of lathe type machines in the pressure vessel fabrication for winding fibers over the metal cylinders is fairly well known in the art. These machines comprise mainly a rotating chuck & tail-stock for holding the cylinder and a transverse slide for moving the fibers along the length of the cylinders. However, these machines, known to the prior art, suffer from the following disadvantages. Main disadvantage of these machines, known in the prior art, is that these machines can handle only bigger size cylinders having diameter varying from one tenth of a meter to few meters. Another disadvantage of these machines, known in the prior art, is that the pitch of the winding of fibers is limited by the set of gears in the gear trains thereby making it difficult to select any intermediate pitch value. Yet another disadvantage of these machines, known in the prior art, is that these machine may give jerking motion to the fibers thereby disturbing the uniformity of the fiber winding and circumferential pre-stressing. Still Another disadvantage of these machines, known in the prior art, is that online monitoring of tension in the fiber during the winding operation is not possible. Yet another disadvantage of these machines, known in the prior art, is that on line measurement of charge developed due to winding operation is not possible. Another types of fiber winding machine, known in the prior art, are of numerical controlled machines. However, these machines are very sophisticated and costly. It will be impractical to use such machines for fiber winding machines. OBJECTIVES OF THE INVENTION Primary object of this invention is to provide a fiber winding apparatus, which is suitable for winding fiber over the circumference of piezo-electric cylinders. Another object of this invention is to provide a fiber winding apparatus wherein the pitch of the fiber winding can be continuously varied over a range of values. Yet another object of this invention is to provide a fiber winding apparatus, wherein the tension of the fiber during the winding operation can be continuously varied as well as monitored. Still another object of this invention is to provide a fiber winding apparatus, wherein the charge developed during the winding operation can be continuously monitored. Yet further object of this invention is to provide a fiber winding apparatus which does not give jerky motion to the fibers during winding thereby making the process of winding uniform. Still further object of this invention is to provide a fiber winding apparatus which is simpler, cheaper and easy to operate. SUMMERY OF THE INVENTION According to this invention there is provided a fiber winding apparatus comprising a brake and spool unit for controlling the tension applied to the fiber during a winding operation, a traversing unit for providing a transverse motion to the fiber, a chuck unit for winding the fiber from said transverse unit on to a mandrel unit, said chuck unit holding the mandrel unit, said mandrel unit having a piezo electric cylinder for winding of the fiber, said brake and spool unit characterised by having a rotatable shaft, one said of a said shaft connected to a brake drum and the other side connected to a spool, said brake drum being capable of rotating between two brake shoes; said traversing unit comprising a lead screw connected to a thyristor controlled DC motor, said lead screw connected to a carriage, a load cell connected to said carriage and limit switches mounted on the either sides of said carriage to control the winding length of the piezo-electric cylinder of said mandrel unit, said chuck unit comprising a 3-jaw chuck powered by a thyrister controlled DC motor, said 3-jaw chuck connected to said motor, said 3-jaws chuck holding said mandrel unit using the jaws and capable of rotating by said motor to wind the fiber over the circumference of the said piezo-electric cylinder of said mandrel unit; a tail stock unit comprising a bed for sliding the tail stock along the axis of rotation of said 3-jaws chuck and capable of taking the leads of the piezo-electric cylinder of said mandrel unit for the change measurement; said mandrel unit comprising said piezo-electric cylinder held by clamping plates and nuts and further connected to the mandrel shaft, slip rings and carbon brushes, said piezo-electric crystals connected to standard digital multi¬meter through electrical leads; a control unit comprising for digital display of the speed of the said DC motors indicating the pitch of the winding. According to the present invention, there is provided a fiber winding apparatus for winding of fibers over cylinders. The apparatus is particularly suitable for winding of fiber over piezo-electric cylinders. The fiber winding apparatus of this invention has the ability to measure 8B display the charge developed during winding in a continuous manner. It has ability to vary and display the tension of the fiber over a range varying from 0 to 20 kgf in a continuous fashion. The machine can wind fibers on piezo-electric cylinders having diameter varying from 50 to 350 mm. Similarly the pitch of the winding can be continuously varied from 0 to 20 mm by varying the speed of the two DC motors in this machine. This apparatus is simpler, cheaper and easy to operate and it can be conveniently mounted on a tabletop. The apparatus mainly comprises of six main sub units namely Brake 8B Spool unit, Traversing unit, Chuck unit, Tail stock unit, Mandrel unit and Control unit. BRIEF DESCRIPTION OF THE DRAWINGS: Any further characteristics, advantages and applications of the invention will • become evident from the detailed description of the preferred embodiment which has been described and illustrated with the help of following drawings wherein, FIG. 1 of the drawings shows the layout of the fiber winding apparatus. FIG.2 of the drawings shows an isometric view of the fiber winding apparatus. FIG. 3 of the drawings shows the mandrel unit of the fiber winding apparatus. FIG.4 of the drawings shows the brake unit of the fiber winding apparatus. DESCRIPTION OF THE INVENTION Referring to Fig. 1, the fiber winding apparatus of this invention comprises of brake & spool unit (1), traversing unit (2), chuck unit (3), tail stock unit (4), mandrel unit (5) and control unit (6). The brake and spool unit (1) controls tension applied to the fiber during winding operation. The traversing unit (2) provides the necessary transverse motion to the fiber and measures the fiber tension during winding process. The chuck unit (3) winds the fiber under tension over the circumference of the piezo-electric cylinder (7). The tail-stock unit (4) supports one end of the mandrel unit (5) and measures the charge developed during winding. The mandrel unit (5) holds the piezo-electric cylinder (7) during fiber winding and passes the leads through slip rings (25) (26) to the tail-stock unit (4) for charge measurement. The control unit (6) comprises all the electric controls required for the control of two DC motors (12) (19), and limits switches (16) (17). Referring to Fig. 2, the shaft (8) inside the brake and spool unit (1) is supported by two standard taper roller bearings. One side of the shaft (8) is connected to the brake drum (9) and the other side is connected to the spool (10). The brake drum (9) rotates between two brake shoes (33) (34). The brake and spool unit (1) can continuously vary fiber tension from 0 to 25 kgf. The traversing unit (2) comprises of a lead screw (11) powered by 0.5 HP thyristor controlled DC motor (12). The lead screw (11) is supported by two standard taper roller bearings and it is connected to the motor through a flexible coupling (13). The clockwise and anti-clockwise rotation of the lead screw (11) leads to leftward and rightward movement of the carriage (14). The speed of the DC motor (12) connected to the lead screw (11) can be adjusted to get the required pitch of the fiber during winding operation. The pitch of the winding can be continuously varied from 0 to 20 mm. The tension in the fiber is measured using a load cell (15) mounted on the carriage (14). The fiber tension is displayed in the digital readout of the load cell (15). The carriage (14) moves on two guide rods to provide transverse straight-line motion. Two limit switches (16) (17) are mounted on either side of the carriage to control its direction of movement which in turn controls the winding length of the piezo-electric cylinder (7). The limit switches (16) (17) can be adjusted to get a maximum winding length of the piezo¬electric cylinder (7) which can go up to 200 mm . The chuck unit (3) comprises of a 3-jaw chuck (18) powered by 0.5 H.P, thyristor controlled DC motor (19). The 3-jaw chuck (18) is supported by two standard taper roller bearings r^d is connected to the motor (19) through a flexible coupling (20). The 3-jaw chuck (18) holds the mandrel unit (5) using the jaws and rotates under the influence of DC motor (19) to wind the fiber over the circumference of the piezo-electric cylinder (7). The taiistock unit (4) comprises of a bed (21) for sliding the tailstock (22) along the axis of rotation of the 3-jaw chuck (18). It also has the supporting structure for taking the leads of the piezo-electric cylinder (7) for the charge measurement. The control unit (6) provides digital readouts indicating the speeds of the two DC motors (12) (19) which in turn indicate the pitch of the winding. Referring to Fig. 3 the mandrel unit (5) holds the piezo-electric cylinder (7) during winding and passes the leads of the piezo-electric cylinder (7) to the standard digital multi-meter for charge measurement. The piezo-electric cylinder (7) is held by two clamping plates (23) (24) and nuts (28) (29). The clamping force developed by the nuts (28) (29) provides the necessary rigid connection between the piezo-electric cylinder (7) and the mandrel shaft (27). The diameter of the piezo-electric cylinder (7) handled by this machine ranges from 50 to 350 mm. Electrical leads of the piezo-electric cylinder (7) are taken through the mandrel shaft (27), slip rings (25) [26], spring-loaded carbon brushes (30) (31) and the tail stock unit (4) to the standard digital multi-meter. The charge developed during winding is measured and displayed online through these electrical leads. The electrical leads and slip rings (25) [26] are well insulated from the mandrel shaft (27) and between the leads to prevent the electrical short circuit. Referring to Fig.4, the brake drum (32) of the brake & spool unit (1) rotates between two brake shoes (33) (34). The braking force on the brake drum (32) is transferred through lever bolt (35) and spring (36) arrangement. The tension, applied to the fiber, is controlled by the tightness of the lever bolt (35). Since the braking force is given through the spring (36), the applied tension can be varied with great precision. The tension of the fiber can be continuously varied from 0 to 25 kgf. during winding. The piezo-electric cylinder (7) is initially held in the mandrel shaft (27) and electrical leads are connected in the mandrel shaft (27). The mandrel unit (5) is held" using the 3-jaw chuck (18) and tailstock (22). The fiber from the spool (10) is allowed to pass through the pulleys of traversing unit (2) to reach the chuck, unit (3). The pitch of the fiber winding is selected by setting the speed of the two DC motors (12) (19). The fiber is fixed to one end of the piezo-electric cylinder (7) by keeping it in between clamping plate (24) and piezo-ceramic cylinder (7). The tension in the fiber is adjusted to the predetermined value as per overall pre-stressing requirement in the piezo-electric cylinder (7). Once the winding operation is started, this predetermined tension is maintained throughout the winding operation. The amount of charge developed due to winding is measured and displayed by the standard digital multimeter. After winding of each layer of fiber over the piezo-electric cylinder (7), epoxy resin is applied uniformly over the circumference for keeping the fibers in position. After completion of winding of one layer of fiber, the traversing unit reverses its direction of movement and the next layer is wound over the circumference in the similar manner. The reversal of direction is controlled by the limit switches (16) (17). Once the required layers of fibers is wound over.the piezo-electric cylinder (7), the machine is stopped by pressing the switch in the control unit (6). After this, the fiber is clamped to the clamping plate (23) by screws and the fiber is cut to separate it from the spool (10). This helps in keeping the tension of the fiber intact. The mandrel unit (5) is. allowed to rotate freely by running the DC motor (16) alone allowing the resin to spread uniformly over the circumference. After a period of one hour the rotation of the mandrel unit (5) is stopped and is removed from the machine for curing. The layers of epoxy resin keep the fibers intact which in turn maintains the piezo-ceramic cylinder (7) in the pre-stressed condition. The wound piezo-electric cylinder (7) is removed from the mandrel unit (5) and now it can be used for the assembly of transducer. The present embodiment of the invention, which has been set forth above, was for the purpose of illustration and is not intended to limit the scope of the invention. It is to be understood that various changes, adaptations and modifications can be made in the invention described above by those stilled in the art without departing from the scope of the invention which has been defined by following claims. WE CLAIM: 1. A fiber winding apparatus comprising a brake and spool unit (1) for controlling the tension applied to the fiber during a winding operation, a traversing unit for providing a transverse motion to the fiber, a chuck unit (3) for winding the fiber from said transverse unit on to a mandrel unit, said chuck unit holding the mandrel unit, said mandrel unit having a piezo electric cylinder for winding of the fiber. said brake and spool unit (1) characterised by having a rotatable shaft (8), one said of a said shaft (8) connected to a brake drum (9) and the other side connected to a spool (10), said brake drum (9) being capable of rotating between two brake shoes (33) & (34); said traversing unit (2) comprising a lead screw (11) connected to a thyristor controlled DC motor (12), said lead screw (11) connected to a carriage (14), a load cell connected to said carriage (14) and limit switches mounted on the either sides of said carriage (14) to control the winding length of the piezo-electric cylinder (7) of said mandrel unit (5); said chuck unit (3) comprising a 3-jaw chuck (18) powered by a thyrister controlled DC motor (19), said 3-jaw chuck (18) connected to said motor (19), said 3-jaws chuck (18) holding said mandrel unit (5) using the jaws and capable of rotating by said motor (19) tc wind the fiber over the circumference of the said piezo-electric cylinder (7) of said mandrel unit (5); a tail stock unit (14) comprising a bed (21) for sliding the tail stock (22) along the axis of rotation of said 3-jaws chuck (18) and capable of taking the leads of the piezo-electric cylinder (7) of said mandrel unit (5) for the change measurement; said mandrel unit (5) comprising said piezo-electric cylinder (7) held by clamping plates (23) & (24) and nuts (28) & (29) and further connected to the mandrel shaft (27), slip rings (25) 8B (26) and carbon- brushes (30) & (31), said piezo-electric crystals connected to standard digital multi-meter through electrical leads; a control unit (6) comprising for digital display of the speed of the said DC motors (12) 85 (19) indicating the pitch of the winding. 2. A fiber winding apparatus as claimed in claim (1), wherein the diameter of the said piezo-electric diameter vary from 50-350 mm. 3. A fiber winding apparatus as claimed in claim (1), wherein the pitch of the winding continuously vary from 0-20 mm. 4. A fiber winding apparatus as claimed in claim (1), wherein the tension of the fiber continuously vary from 0-20 kgf. 5. A fiber winding apparatus as herein described substantially and illustrated with accompanying drawings.

Documents:

687-DEL-2002-Abstract-(14-06-2008).pdf

687-DEL-2002-Abstract-(25-06-2008).pdf

687-del-2002-abstract.pdf

687-DEL-2002-Claims-(25-06-2008).pdf

687-del-2002-claims.pdf

687-DEL-2002-Correspondence-Others-(25-06-2008).pdf

687-del-2002-correspondence-others.pdf

687-del-2002-correspondence-po.pdf

687-DEL-2002-Description (Complete)-25-06-2008.pdf

687-del-2002-description (complete).pdf

687-del-2002-drawings.pdf

687-del-2002-form-1.pdf

687-del-2002-form-18.pdf

687-DEL-2002-Form-2-(25-06-2008).pdf

687-del-2002-form-2.pdf

687-del-2002-form-3.pdf

687-DEL-2002-GPA-(25-06-2008).pdf

687-del-2002-gpa.pdf