WO2005098109A1

WO2005098109A1 - Electromagnetic weaving machine

Info

Publication number: WO2005098109A1
Application number: PCT/IN2004/000095
Authority: WO
Inventors: Rohit Verma
Original assignee: Rohit Verma
Priority date: 2004-04-07
Filing date: 2004-04-07
Publication date: 2005-10-20

Abstract

This embodiment discloses the invention of an Electromagnetic Weaving Machine for converting yarn into fabric with a filling insertion rate of I1000 meters per minute and operating speed of 4800 PPM for a 165 cm wide loom. One weaving cycle comprises of three primary operations shedding, picking and beating, all of these motions in Electromagnetic Weaving Machine are achieved by magnetic levitation and propulsion system. Since friction is eliminated therefore this machine is free from wear and tear and requires least maintenance. The secondary operations of a weaving machine are let-off and take-up decides warp crimp and picks per inch in the fabric. In Electromagnetic Weaving Machine a modified PIV gear box is used for driving let off and take up through which picks per inch can be controlled automatically by a microprocessor. The auxiliary motions of weaving are warp and weft stop motions which ensures quality of fabric. In Electromagnetic Weaving Machine an unique Optically sensed warp stop motion is used which indicates which warp thread has broken. In Electromagnetic Weaving Machine an unique weft tensioning device is used which provides desired tension in the weft and controls weft crimp, improves fabric cover, drape and strength. This Electromagnetic Weaving Machine as it is five times more productive than present air jet looms and ten to twelve times more productive than projectile and rapier looms and due to above mentioned features will definitely bring a revolution in weaving industry

Description

Title of Invention: Electromagnetic Weaving Machine

Field of Invention: Textile weaving

Background of Invention: Weaving is the process in which Yarn is converted into fabric.

The process of weaving is divided into three motions, which are:

1. Primary Motions

(a) Shedding

(b) Picking

(c) Beating

2. Secondary Motions

(a) Take Up

(b) Let Off

3. Auxiliary Motions

(a) Warp Stop Motion

(b) Weft Stop Motion

Weaving machines are distinguished by the method of weft insertion the major picking systems are:

1. Air Jet Picking System

2. Water Jet Picking System

3. Projectile Picking System

4. Rapier Picking System

However in almost all the systems, cams accomplish shedding and beating mechanisms. Out of the above-mentioned picking systems the Air Jet picking system is the fastest. The fastest air jet loom can insert up to 1000 Picks Per Minute (PPM). The disadvantages of present weaving system are:

1. Higher speeds and high weft insertion rates cannot be achieved. The fastest machine is air jet loom but here the weft breakages increase with the increase in speed due to untwisting of weft during insertion.

2. No control over weft tension in air jet weaving machines.

3. Warp stop motion doesn't indicate which thread has broken. This reduces operator's efficiency. 4. All the mechanisms are mechanically driven and have wear and tear and friction at higher speeds therefore requires frequent maintenance.

5. To change picks per inch, mechanical adjustment is required which takes time.

6. Jet looms are not suitable for weaving all kinds of fabrics, and requires good quality of weft.

Object of Invention: The primary objectives of Inventing Electromagnetic weaving machine are:

1. To achieve working speed of about 4800 picks per minute for a 165 cm width loom.

2. To control the tension of weft, and thus improving fabric quality.

3. To change the picks per inch automatically.

4. Minimizing friction and hence reduction in maintenance.

5. Indicating which warp thread had broken.

6. Controlling shedding electronically according to the desired design of the fabric.

7. To insert low and high quality of weft with same efficiency.

Summary of Invention: The principle used in Inventing the Electromagnetic Weaving Machine is that similar poles of a magnet respells each other and opposite poles attract each other, and when direct current is passed through a coil wound on an iron bar it gets magnetized and the poles can be changed by changing the direction of flow of current. By using the magnetic force for levitating the heald, sley and weft carrier slightly above the tracks on which these travels, the friction is eliminated and high speeds can be achieved.

Detailed Description of the Invention: All the operations of a weaving machine are divided into groups, which are: 1. Primary Motions

(a) Shedding

(b) Picking

(c) Beating 2. Secondary Motions

(a) Take Up

(b) Let Off

3. Auxiliary Motions

(a) Warp Stop Motion

(b) Weft Stop Motion

(c) Weft tensioning mechanism.

The detailed working of each of these motions and how the facts/principles mentioned below are used for driving all the primary motions are discussed in the following pages Principles/facts:

1. Similar poles of a magnet repel each other and opposite poles attract each other.

2. When direct current is passed through a coil wound on an Iron bar it gets magnetized and changing the direction of flow of current can change the poles.

Electromagnetic Shedding

Shedding plays a vital role in the conversion of yarn into fabric, its function is to divide the warp sheet into two parts in the form of a shed, So that the weft can pass through the shed. In almost all the present weaving systems shedding is mechanical and is done by cams, and the present shedding system is slow, not flexible according to the design and requires frequent maintenance.

Object: For achieving the working speed of 4800 PPM for a 165 cm wide loom. The shedding operation must be completed in a 1.8 millisecond.

To eliminate the friction, and to avoid breakdowns and frequent maintenance.

To control shedding according to the design by a microprocessor.

Summary: To complete the shedding operation in milliseconds a very high speed is required which is achieved by levitating the heald shaft using magnetic force and using the fact/principle that

The heald shafts are lifted or lowered electromagnetically according to the fabric design by a microprocessor. Since no mechanical drive is used for shedding operation therefore the friction is minimum and this machine is free from mechanical breakdowns and requires least maintenance.

Description: The lifting of warp sheets to form shed is done with the help of heald shafts. Now the lifting of heald shaft must be as low as possible, because the shed has to be formed as fast as possible and the shedding imparts excessive tension in the warp threads as the path of warp threads gets increased during shedding i.e. in open shed, and this may cause excessive warp breakages. The depth of shed directly depends upon the height and width of weft carrier (the weft carrier is responsible for taking the weft across the shed). Therefore the dimensions of weft carrier decides the lift of heald shafts.

The detailed description of weft carrier dimensions is given in Electromagnetic picking here for shedding we are concerned only with its height, width and length. The height of weft carrier is 1.0 cm, width is 1.5 cm, and length is 4.0 cm.

The shed geometry and factors affecting lift of heald shaft

From figure 'B', for a symmetrical shed angle Bl = B2 = B' and hi = h2 = h, where h is the

Weight of shed in the reed when the reed is at its backward most position. b is the distance between cloth fell and reed, when reed is at its backward most position.

H is the lift of heald shaft measured from horizontal line.

B is the distance of first heald shaft from the fell of cloth.

Now, H = btanB ' (1)

It is clear from equation (1) that B' should be as small as possible, so as to reduce the Lift.

Now from geometry tanB¹ = H/B therefore equation (1) can be written as b = h * H B (2)

From equation (2) it is clear that, if the harness lift H is made small (Keeping B and h constant) the reed movement must be increased, in order to permit the weft carrier to enter into the shed. Now, the height h will depend on the height of weft carrier and keeping h and B constant we have to compromise between b and H. It is desirable that h be as large as possible and H and b as small as possible. This can be achieved by placing the heald shafts as near as possible to the reed, when reed is at its backward most position.

From equation (1) and (2) it is clear that 'b¹, the distance traveled by sley affects directly the depth of shed, therefore let's decide the distance traveled by reed in forward direction, figure 'C shows the actual and optimized values of

1. The depth of shed, h = 5.99 cm

2. The distance traveled by sley, b = 17.18 cm

3. The lift of heald shaft nearer to reed, H = 8.12 cm

From equation (2) b = h*H B keeping b and h constant, we find that Η' the lift of heald shaft is directly proportional to its distance from the fell of cloth, i.e. Greater the distance 'B' greater will be the lift required. It must be noted that the sley will not move straight, rather it has to move along a path inclined at an angle of 10 degree with the horizontal. The reason for this is described in

Electromagnetic beating.

Distance traveled by the Sley:

Referring to figure *C AB is the distance traveled by the sley and it is given by

AB^Λ2 = AC^Λ2 + BC^Λ2

AB = (4 + 289) ^Λ 1 / 2 = 17.18 cm.

Lift of heald shafts:

We have already discussed that greater the distance of heald shaft from the reed more will be lift of heald shaft is required. From figure 'C

B ' = 10 degree, b= dB" = 17 cm h/2 = dC = dB"tanl0 h = 2*17*tanl0 = 5.99 cm.

Now considering the width of heald shaft equal to 1 cm and a distance of 2mm between the heald shafts and leaving a space of 4 cm after every fourth heald shaft the reason for leaving distance of 4 cm after every fourth heald shaft is to provide Space for upper and lower Buses and this will be discussed later in details.

Using the equation H = BtanB' the lift of different heald shafts can be found. From figure 'C

H/2 = Btanl0

The value ofB will change for each heald shaft and it can he calculated as:

H/2 for first heald shaft = (17 +6) tanlO = 4.06cm

H/2 for second heald shaft = (17 + 6 + 1 +. 2) tanlO = 4.06cm

H/2 for third heald shaft = (17 + 6 + 2 + .4) tanlO = 4.26cm

H/2 for fourth heald shaft = (17 +6 + 3 + .6) tanlO = 4.69cm

Adding 4 cm for providing space for buses

H 2 for fifth heald shaft = (17 + 6 + 4 + .8 + 4) tanlO = 5.61cm

H/2 for sixth heald shaft = (17 + 6 + 5 + 1 + 4) tanlO = 5.82cm

H/2 for seventh heald shaft = (17 + 6 + 6 + 1.2 + 4) tanlO = 6.03cm

H/2 for eight heald shaft = (17 + 6 + 7 + 1.4 + 4) tanlO = 6.24cm

Adding 4 cm for providing space for Buses

H/2 for ninth heald shaft = (17 + 6 + 8 + 1.6 + 8)tanl0 = 7.16cm H/2 for tenth heald shaft = (17 + 6 + 9 + 1.8 + 8)tanl0 = 7.37cm

H/2 for eleventh heald shaft = (17 + 6 + 10 + 2.0 + 8)tanl0 = 7.58cm

H/2 for twelfth heald shaft = (17 + 6 + 11 + 2.2 + 8)tanl 0 = 7.79cm

Adding 4 cm for providing space for Buses

H/2 for thirteenth heald shaft = (17 + 6 + 12 + 2.4 + 12) tanlO = 8.71cm

H/2 for fourteenth heald shaft = (17 + 6 + 13 + 2.6 + 12) tanlO = 8.92cm

H/2 for fifteenth heald shaft = (17 + 6 + 14 + 2.8 + 12) tanlO = 9.13cm

H/2 for sixteenth heald shaft = (17 + 6 + 15 + 3.0 + 12) tanlO = 9.35cm

Thus the maximum lift of heald shaft is 18.7 cm for sixteenth heald shaft. From the previous calculations we found that lift for each heald shaft is different. Therefore instead of providing different velocities to different heald shafts, a provision is provided for lifting or lowering theheald shafts in a group of four and leveling initially all the heald shafts according to their respective lifts for bringing all the warp threads in line when shed is fully open.

Velocity of heald shaft and time available for the operation of shedding:

The one machine cycle comprises of five operations, which are shedding, picking, beating, take up, and let off. Therefore the time available for one machine cycle is divided into these five operations and the time available for one machine cycle is .0125 seconds for 4800 PPM.

Now the shedding and beating operations will work simultaneously, the shedding will start when the sley commences its forward journey during beat up the shed must be in crossed position and at the backward position of sley the new shed must be fully open.

When sley starts moving back after beat up the let-off and take-up operations comes in action.

Let-off and take-up operations will be discussed later in detail. Now the time required to complete one cycle can be divided in two motions

1. For picking

2. For beating

The major portion of the available time will be used by picking operation in each machine cycle, Let's calculate the time required for picking and beating. Let, vl, si, tl be the velocity, distance, and time available for picking and Let, v2, s2, t2 be the velocity, distance, and time available for beating.

Now for achieving the speed of 4800 PPM for a 165 cm wide loom, one cycle must be completed in 0.0125 seconds and this is the total time available therefore tl +t2 = 0.0125...(3)

For a loom width of 165 cm a 40 cm track on both sides of loom is required for accelerating the weft_carrier, this will be discussed in details in picking mechanism. Therefore the distance traveled by weft carrier is

165 + 40 cm = 205 cm

From figure C the inclined distance traveled by sley is 17.18 forward and 17.18 backward i.e.

34.36 cm.

From equations of motion v = u + at, v^Λ2 = u^Λ2 + 2as, s = u + 1/2 a*t^Λ2

Where v = final velocity, u = initial velocity, a = acceleration, s = distance traveled, and t time in seconds. tl = 2sl/vl , t2 = 2s2/v2 from above equations tl +t2 = 2[ sl/vl + s2/v2 ]

0.0125 = 2[2.05/vl + .344/v2] (7) (taking si and s2 in meters)

Taking the velocities vl and v2 be the same then vl = v2 = v

0.0125 = 2/v * (2.05 + .344)

Or v = 383.04 m/s vl = v2 = 383.04 m/s as tl = 2sl/vl tl = 2*2.05/383.04 = 10.699 * 10^Λ-3 seconds t2 = 2*345/383.04 = 1.801 * 10^Λ-3 seconds

Hence the time available for picking is 10.699 * 10^A-3 seconds and time available for beating is equal to 1.801 * 10^Λ-3 seconds. Since the time available for beating is the time available for shedding therefore time available for shedding = 1.801 * 10^A-3 seconds.

The vertical lift of first four heald shafts is 8.12 cm since they travels in a group of four.

The vertical lift of second four heald shafts is 11.22 cm.

The vertical lift of third four heald shafts is 14.32 cm.

The vertical lift of last four heald shafts is 17.42 cm.

Since, all the heald shafts have to travel different distances in equal time (1.801 * 10^A-3 second) therefore their velocities must be different, this can be achieved by varying current in the electromagnets of maglev track and bus. From equations of motions t = 2s/v

For first set of heald shafts the velocity will be 1.801 * 10^Λ-3 = 2*0.0812/v v = 90.17 m/s

For second set of heald shafts the velocity will be 1.801 * 10^Λ-3 = 2*.1122/v v = 124.6 m/s

For third set of heald shafts the velocity will be 1.801 * 10^Λ-3 = 2*.1432/v v = 159.02 m/s

For first set of heald shafts the velocity will be 1.801 * 10^Λ-3 = 2*.1742/v v = 193.45 m/s

Mechanism for Shedding: The mechanism driving the heald shafts has to overcome the tension of warp threads, because during shedding the length of warp yarn increases which imparts tension in it, and if the yarn tension increases than the individual yarn strength then warp breakage will occur. This can be reduced by moving the back rest down at the time of shedding this technique provides extra length of warp threads and reduces increase in tension.

Thus we have to think only for initial tension in warp because later on during shedding the back rest will take care of it.

When the heald shafts are in center position then there will be no effect of warp tension on the heald shafts, but we have to move the heald shafts with some initial critical tension, as we have to weave-up cloth in some tension to ensure good quality. Thus the initial tension of warp will be maintained throughout the shedding process. The figure D shows how the mechanism for shedding will work, here 'A' is the magnetic levitating track or in short we call it maglev track

On which the bus B will move up and down, before going in details let's see how the bus B levitate on maglev track and how it will move up and down.

Figure E-1 gives the enlarged view of maglev track and bus arrangement, in which A is the maglev track in which the electromagnets a, b, c, d, e... are placed. B is the bus having electromagnets embedded in it in all the directions i.e. top, left, right, bottom-left, and bottom- right. The top view of figure E-1 is given in figure E-2 which clears the arrangement of electromagnets in maglev track and the bus. Now, the bus B levitates on A the maglev track, due to the repulsive magnetic force of the electromagnets placed in bus and maglev track. The movement of bus B on maglev track is explained using the principles:

It is clear from figure E-1 and E-2 that the bus B have two strong electromagnets in each direction i.e. total ten electromagnets, now how the bus B will travel on maglev track can be explained by considering any one side of the bus and the maglev track.

Consider figures E-3, E-4, E-5, E-6 in which a, b, c, d and e represents the electromagnets of maglev track and al, a2 represents electromagnets of bus 'B'. The electromagnets al, a2 of bus have opposite polarities and this will remain maintained throughout the journey of the bus. Figure E-3 shows the starting position of bus B here when the electromagnets a and b activated their similar poles repels al and a2 thus due to this magnetic force the electromagnets al and a2 and thus the bus levitates above the maglev track. Now when it is desired to move the bus the electromagnet c is activated, whose north pole attracts a2, due to this the electromagnets al and a2 moves towards c. The figure E-4 shows how the magnetic forces make the bus to move just by changing the polarities of electromagnets. Here al is repelled by a and at the same time al is attracted by b. a2 is repelled by b and attracted by c. Now when al and a2 reaches just above b and c the polarities of b and c are changed in such a way that b starts repelling al and c starts repelling a2 because of this arrangement the bus continues to levitate. Figure E-5 shows further movement of the bus when al and a2 were just above b and c electromagnet d is activated so it starts attracting a2 and the bus moves further towards d. In figure E-5 it is shown that al is repelled by b and attracted by c and a2 is repelled by c and attracted by d.

In this way the bus can be made to move, on the maglev track just by changing the polarities of the electromagnets. The polarities of the electromagnets is controlled by the microprocessor or precise control.

Now let us understand the electromagnetic shedding mechanism given in figure D. Here A the maglevs on which the bus will move up and down, The upper maglev tracks will be used to take the selected heald shafts upwards and the lower maglev tracks takes the selected heald shafts downwards. This selection of heald shafts will depend on the weave and will be accomplished by the lock pin D, the electromagnet J, and the hole F made in the heald shaft.

The selection of heald shafts must be accomplished before the lifting of heald shaft i.e. before the shedding starts.

There are four holes F in heald shafts two at top and two at bottom on each side of the heald shaft in which the lock_pins D will be inserted. Two lock_pins will be inserted in holes on each side for either raising or lowering the heald shafts.

The lock_jnns D have their head made up of permanent magnet of high pole strength, which will be attracted or repelled by the electromagnets J placed in the bus. When attracted the two lockjnns will be inserted in the holes of the heald shaft and when repelled the lockjnns will come out of the hole of the heald shaft. The heald shafts will travel in the slot made in guide.

The purpose of E the strong electromagnet centrally placed is to propel or accelerate the buses

B.

When the buses are on the verge of completion of their journey the electromagnets El have to decelerate them to zero velocity in a fraction of a second for this they have to use repelling magnetic force on the buses. Hold the buses at top position so that picking operation gets completed by attractive magnetic force and then again propelling the buses by repulsive force for downward (for upper bus) and upward (for lower bus) motion. At the end-of this motion E has to accomplish the goal of decelerating and stopping the buses.

The complete working of the electromagnetic shedding mechanism is described below:

1. The electromagnets J will be activated for selecting the heald shafts by inserting the lock_pins in them, according to the design.

2. After the first operation the lockjώis D will move towards, the heald shafts and gets engaged in the holes F made in heald shafts so that when the buses moves the heald shafts also moves along with them.

3. The central electromagnet E will repel the buses, it will repel the upper bus towards up and the lower bus towards down. At this time the electromagnets placed inside the maglev tracks and in the buses will be activated and the electromagnets performs their job of attracting or repelling the bus and moves the corresponding bus up or down. 4. When the buses are on the verge of accomplishing their respective journeys the electromagnets El will impart repelling force on them for decelerating and when their velocity becomes zero hold the buses at top or bottom position for allowing the picking to become completed.

5. When the change of shed is required the electromagnets El will repel the buses for their downward or upward journey and here at this moment the central electromagnet E has to stop them by repulsive magnetic force and hold them at the central position when their velocity becomes zero by attractive force.

When the heald shafts reaches their end positions (upper or lower), the warp tension tries to bring them towards the center, to nullify this effect the electromagnets El has to hold bus at top or bottom position by attractive force when their velocity becomes zero.

The selection of heald shafts is made when all the heald are at center closed shed position.

Therefore during their journey the bus stop for a fraction of a second at the center position.

Also the lock >ins according to the new shed are inserted the heald shaft at this position and then the old lockjpins are removed from the heald shaft.

Side view of the shedding mechanism:

To make clear the working of electromagnetic shedding considers the side view of the mechanism given in figure F. The figure F shows that how the various heald shafts gets selected and engaged with the bus according to the weave (lift plan). It is clear from the figure that each bus B have 8 lockj ins D arranged in two rows and how each bus is capable of carrying 4 heald shafts. The movement of heald shaft depends on its engagement with lockjnn

D, i.e. of which bus's (upper or lower) lockjjin it gets engaged.

Now as it is decided at nm time that how many heald shafts a bus will carry therefore the force required to lift the heald shafts must be varied or decided at run time by varying current in the various electromagnets of the maglev track, buses, and E, El in multiple of number of heald shafts a bus will carry.

Force required for shedding:

The electromagnet E or El has to repel the buses for accelerating the heald shafts this force will be added to the magnetic force applied by the electromagnets placed inside the maglev tracks and the bus. This net force must be equal to Fn = [(weight of heald shaft) + (tension in one warp thread)*no. of warp threads]* acceleration required to achieve the desired velocity in given time. First of all we will find out the forces due to one pair of electromagnets of top of the bus and then multiply the force by no. of pairs.

The magnetic field intensity due to an electromagnet is given by

H = Uo * N * i / 2 * l where N = no of turns, i = current, Uo = permeability of free space and 1

= length of solenoid.

Let NI, il, 11 represents the number of turns, current and length of solenoid of maglev track and Let N2, i3, 14 represents the number of turns, current and length of solenoid of bus. Then field intensity due to solenoid of maglev track is

Uo*Nl*il/2*l, and

The field intensity due to solenoid of bus is

Uo*N2*i2/2*12

From figure E-4 it can be seen that at any instant the electromagnets of bus are in influence of two forces one is attractive and other is repulsive. Consider al of the bus in figure E-4 it is in influence of repulsive and attractive forces of electromagnets a and b respectively of maglev track. Therefore the field intensity due to a and b will be added and given by

2*( Uo*Nl*il/2*ll) (a)

Similarly, a2 is influenced by repulsive and attractive forces of electromagnets b and c.

Therefore the field intensity due to b and c will be added and given by

2*( Uo*Nl*il/2*ll) (b)

Adding equations (a) and (b) we get the total field intensity due to electromagnets a, b and c of maglev track which is

2*( Uo*Nl*il/ll) (c)

Now the electromagnet al of bus at the same time is repelling electromagnet a and attracting / electromagnet b of maglev track, therefore its field intensity also be doubled, it is given by

2*(Uo*N2*i2/2*12) (d)

Similarly for electromagnet a2 of bus field intensity is given by

2*(Uo*N2*i2/2*12) (d')

Total field intensity due to electromagnets of bus is given by

2*(Uo*N2*i2/12) (e) This force is due to the top pair of bus, Now considering all electromagnets of the bus the force will be calculated. Since the dimensions of bus are different therefore the number of turns and the current will be varied for different elecfromagnets.

Let, N3,i3 represents the no of turns and current for left and right electromagnets of the bus and

Let, N4,i4 represents the no of turns and current for bottom left and bottom right electromagnets of the bus.

Field intensity due to right and left electromagnets os bus is given by.

4*(Uo*N3*i3/12) (f)

Field intensity due to bottom right and bottom left electromagnets of bus is given by.

4*(Uo*N4*i4/12) (g)

In equations f and g 12 is taken because the length of all the electromagnets of the bus is same.

Now the total field intensity of electromagnets of bus is given by adding the equations (e), (f), and (g)

2*(Uo*N2*i2/12) + 4*(Uo*N3*i3/12) + 4*(Uo*N4*i4/12), or

2*Uo/12(N2*i2 + 2*N3*i3 + 2*N4*i4) (h)

The electromagnets of the maglev track will also influence all the electromagnets of bus with the same force. Therefore we have to multiply the equation (c) by 4 (for left, right, bottom left, and bottom_right electromagnets of the bus) We have,

4*(Uo*Nl*il/ll)...(i)

Now the force between two magnets is given by

F = k * (ml * m2) / r ^Λ 2, where ml and m2 are the pole strengths of the magnets and r is the distance between them, k is constant depends upon the medium between the two magnets k = 1 1 A * 3.14 * Uo * Ur, Uo = permeability of free space and Uris the relative permeability of the medium w.r.t the free space. The value of Uo = 4*3.14*10^Λ-7 Henry/mfr for air Ur = 1.

Equation (h) is field intensity due to the electromagnets of bus and represents the pole strength of the bus and Equation (g) is field intensity due to the electromagnets of maglev track and represents the pole strength of the maglev track. Thus the force applied by the maglev track on bus is given by.

F = 8*k*Uo r^Λ2*l^Λ2[( 2*i2 + 2*N3*i3 + 2*N4*i4)*(Nl*il)]....(j) Now for accelerating the bus we are using electromagnets E and El the field intensity of these is given by ..

Uo*N6*i6/2*16 (k)

In the bus two more electromagnets are placed for repelling and attracting the propelling electromagnets E and El. The position of these electromagnets in bus is shown in figure F-l and F-2 and denoted by S Let Ns, is, Is be the no of turns, current and length of the solenoid S then its magnetic field intensity is given by

Uo*Ns*is/2*ls (1)

Force due to propelling of bus by E or El is given by

Fp = (Uo*k/2*r^Λ2*ls)*(N6*i6 + Ns*is) (m) as 16 = Is

Now total force Fn acting on the bus is given by adding equation (j) and (m)

Fn = (8 * k * Uo / r ^Λ 2) * [(N2*i2 + 2*N3*i3 +2*N4*i4)*(Nl*il)/l^A2 + (N6*i6 +

Ns*ls)/16*ls]...(n)

Let the force Fn is be applied against the weight of heald shafts, tension T of warp threads and for accelerating the heald shaft to achieve the desired velocity. If a be the required acceleration, m = mass of the heald shaft and g = acceleration due to gravity and T is the tension in warp threads then, The net force will be equal to

+T + m*a + m*g (o)

When the heald shaft moves down then weight m*g becomes positive and when the shaft moves against gravity then mg becomes negative. Moreover, the warp tension T will be positive for the first half of motion of bus i.e. upto the centre from top position and becomes negative when bus moves from centre to bottom position. Similarly when bus moves from bottom position to centre T becomes positive and becomes negative from centre to top / position.

Thus, considering different situations:

If a the acceleration of heald shaft then from equations of motion a = H/t^A2 where H = lift of the heald shaft and t is the time available

1. When the bus moves top to centre position

Fn = T + m * (a + g)

Fn = T + m * (H /t ^A 2 + (g)) 2. When the bus moves centre to bottom position Fn = -T + m * (a + g)

Fn = -T+ m * (H /t ^Λ 2 + (g))

3. When the bus moves bottom to centre position Fn = T + m * (a - g)

Fn = T+ m * (H /t ^A 2 - (g))

4. When the bus moves centre to top position Fn = -T + m * (a - g)

Fn = -T+-m * (H / t ^A 2 - (g))

Thus from the above equations it is clear that the force required to move the heald shaft will vary according to the direction of motion of the heald shaft

Electromagnetic Picking

Background: The picking plays a vital role in the conversion of yarn into fabric, its function is to insert the weft into the shed formed by the shedding motion across the machine.

The present picking systems are:

1. Air jet picking system

2. Water jet picking system

3. Projectile picking system

4. Rapier picking system

Out of the above mentioned picking systems the air and water jet is the fastest the fastest air jet loom can insert 1000 picks per minute, but its speed cannot be increased.

The disadvantages of present systems of picking are:

1. For air jet looms the weft breakages increases with the increase in the speed, due to untwisting of weft during insertion. In projectile and rapier system this high speed cannot be achieved.

2. There is no control over the weft tension.

3. Air jet picking system is sensible to pressure and temperature variations. Object:

The objectives of the Invention are:

1. To achieve filling insertion rate up to 10000 meters per minute or 190 m/s in a 165 cm wide loom.

2. To insert low grade and high-grade quality of weft with same efficiency.

3. Minimizing friction and hence reduction in breakdowns and maintenance. Summary: For achieving filling insertion rate of 10000 meters per minute a average velocity of 191.6 m/s is required here the maximum speed of weft carrier goes to 383.04 m/s. For achieving this speed the friction has to be reduced and a large amount of instant force is required for accelerating the weft carrier with in a Short distance. For this the weft carrier is levitated inside the maglev track specially designed and strong propelling electromagnets are used for propelling or accelerating the weft carrier which is made up of permanent magnet of high pole strength. The principle 's used for achieving this speed are:

2. When direct current is passed through a coil wound on an Iron bar it gets magnetized and the poles can be changed by changing the direction of flow of current.

At this high speed due to inertia of rest and unwinding tension weft breakages will be excessive to avoid this, a metered quantity of weft is unwounded from the cone by a weft metering device this device is placed on both sides of the loom. When picking starts the weft- metering device relieves the weft without tension. The weft-metering device wounds a metered quantity of weft in advance.

Description: Note that all the calculations we are going to make are based on the loom having 165 cm width and the speed required is 4800 PPM. The /operation of inserting weft through the shed across the loom is called as picking. The weft is carried across the loom by a magnetic weft carrier of high pole strength which is accelerated by a maglev track and propelling electromagnets. Since 4800 picks have to be inserted in one minute across the loom of 165 cm width therefore 80 picks are inserted in 1 second and time available for inserting one pick is 1/80 = 0.0125 second. Now this time is divided into various motions to get performed. The division of time for different for different operations will be divided in two parts:

1. Picking

2. Shedding, beating, take up, let off.

The major portion of time is consumed by the picking operation and rest of the time is available for other operations since they all work more or less simultaneously. Let tl is the time available for picking and t2 is time available for beating then tl + 12 = 0.0125

For accelerating the weft_carrier to achieve the desired velocity before entering into the shed, maglev tracks of about 40 cm are provided on both sides of the loom. Therefore the total width of the loom for weft carrier becomes 245 cm, but the other side of maglev tunnel which is not accelerating the weft carrier is not considered in calculations because beating operation will started as the weft carrier passes the reed Moreover the other side maglev tunnel is used for decelerating the weft carrier.

Using equations of motion we have tl = 2*sl/vl; tl, si, vl represents the time, distance travelled and velocity of weft carrier. t2 = 2*s2/v2; t2, s2, v2 represents the time, distance traveled and velocity of sley. tl + 12 = 0.0125 or, 0.125 = 2*[2.05/vl + .345/v2], (here the lift of 16 th heald shaft is 34.5 cm or .345 m)

If vl = v2 = v Then v = 383.04 m/s and vl = v2 = 383.04 m/s thus, the velocity of weft carrier is 383.04 m/s this is the maximum velocity and average velocity is 191.6 m/s since it starts its journey from rest. tl = 10.699 * 10^A-3 s t2 = 1.801 * 10^A-3 s

Thus the time available for picking is 10.699 * 10^A-3 second and the velocity required is

383.04 m/s and the average velocity is 191.6 m/s. To attain this high velocity our first objective is to minimize friction this can be done by levitating the weft carrier inside the maglev tunnel. The weft carrier is then accelerated by electromagnets of maglev tunnel and the propelling solenoids using the principle that

2. When direct current is passed through a coil wound on an Iron bar it gets magnetized and the poles can be changed by changing the direction of flow of current. The mechanism of picking: As shown in figure G-1 A represents the maglev tunnel, S represents the propelling electromagnets, 1 represents the reed. Before going in details let's see how the we-ftjcarrier is accelerated by magnetic force. Consider figure G-2 in which the electromagnets a, b, c, d, e are placed in maglev tunnel are shown and al is the weft_carrier made up of permanent magnet of high pole strength.

Initially when the weft_carrier was just above the electromagnet their similar poles repels each other and thus the weft carrier levitates above the maglev tunnel. Now for accelerating the weft carrier the electromagnet b is activated whose opposite pole attracts the weft carrier. It is shown in figure G-2 that weft carrier is repelled by electromagnet a and attracted by electromagnet b due to this forces the weft carrier moves towards b. Now when weft carrier reaches to electromagnet b, its polarity is changed and it starts repelling the weft carrier again the electromagnet c is activated and it starts attracting the weft carrier an electromagnet b repels it in this way the weft carrier gets accelerated by magnetic force and moves ahead with a high velocity.

When the weft carrier enters in the reed area its actual journey starts, but before this the weft carrier must have sufficient acceleration so as to pass through the reed in definite time, and for accelerating a body it must travel some distance in a given time and by equations of motion a = 2 * S /t ^A 2.

So for providing sufficient acceleration to the weft carrier a maglev tunnel shown as A in figure G-1 of predetermined length is attached to the sley on both sides of the loom. This will increase the width of loom and for keeping the length of maglev tunnel minimum an unique electromagnetic propulsion system is used.

In figure G-1 A is the maglev tunnel, c is the weft carrier, B is the reed we have already discussed that how the weft _carrier gets accelerated.

Before the beginning of journey of weft -arrier the first electromagnet of maglev tunnel A (LHS side) is activated with same polarity as that of the we_ft_carrier and due to repulsive force the weft carrier carrier will levitate inside the maglev tunnel at a distance of 1mm or 2mm. The force will be same in all directions of maglev tunnel in figure G-3 the side view of maglev tunnel and we:ft_carrier is given where E is the weft_carrier, A is the maglev tunnel and a is the electromagnet inside maglev. Thus the attractive and repulsive force between weft_carrier and electromagnet a will be in all directions Top, left, right, bottom.

Now, before accelerating the weft_carrier by activating the second electromagnet of maglev tunnel, the propelling elecfromagnet S is activated with strong repulsive force so the weft carrier is propelled towards the reed into the shed, and the maglev tunnel will work as discussed previously.

In the reed space special weft carrier guides are placed into which the weft carrier continues its journey the arrangement and schematics of weftj-arrier and weft arrier_guides and reed is shown in figure G-4.

The weft carrier guides are placed such that three guides can come in the length of weft carrier, this arrangement eliminates the fly-off of weft carrier.

Now when the weft ;arrier moves ahead across the reed in weft carrier guides it starts decelerating due to air resistance, to compensate this and to maintain the uniform acceleration strong electromagnets D are placed inside the sley body their function is same as that of maglev tunnel but as they are placed farther away from the path of weft carrier therefore the force applied by them on the weft .aπier is low, because the attractive or repulsive force between two magnets is inversely proportional to the square of distance between them. When the weft carrier reaches to other side of the reed it must be stopped and returned back. The force required to stop the weft carrier is equal to m*a, where m = mass of the weft carrier and a is its acceleration. But here the force for stopping the weft carrier is applied in gradually increasing manner. When weft carrier reaches maglev tunnel of other side its all electromagnets applies a repulsive force, and finally when weft carrier reaches near the propelling solenoid S it applies strong repulsive force and when its velocity becomes zero the propelling solenoid attracts the weft_carrier and places it at its correct projecting place and the same cycle is repeated again.

Force required for picking: Magnetic field intensity of an electromagnet is given by Uo*N*i/2*l, where Uo = permeability of free space (4*3.14*10^A-7 H/m), N = number of turns, i = current and 1 = length of the solenoid Considering one side weft carrier and electromagnet of maglev tunnel a is repelling weft_carrier and b is attracting it therefore magnetic field intensity is doubled and is. given by 2*Uo*N*i 2*l

Considering all sides we have magnetic field intensity = 4*Uo*N*i/l (a) let the magnetic moment of the weft carrier is m2 and for four sides it becomes 4*m2 (b)

Now the force between two magnets is given by F = k*ml*m2/r^A2, where ml and m2 are magnetic moments and r is the distance between them, k is constant.

Let ml and m2 are the pole strengths of the electromagnets of maglev tunnel and weft -aπier and r is the distance between them

F = k/r^Λ2[4*Uo*N*i*m2/l] or F = 4*k*Uo*N*i*m2/l*r^A2 (c)

The field intensity of propelling solenoid is F = Uo*Ns*is/2*ls , Ns is the number of turns, is is the current and Is is length of propelling solenoid

Force between propelling solenoid and weft -arrier is given by

F = k*Uo*Ns*is*m2/2*ls*r2 (d)

The total force acting on

is found by adding equations c and d if Fn is the net force then Fn = (4*k*Uo*m2)[N*i/l*r^A2 + Ns*is/81s*rs^Λ2]

Now if m is the mass of weft carrier and a is the acceleration required to attain a velocity of

383.04 m/s then

Fn = m * a

In the above equation if m, m2, N, Ns, rs, r, 1, Is are constant then a is directly proportional to i and is i.e. the acceleration of the weft carrier can be varied by varying the current flowing in the electromagnets of maglev tunnel and propelling electromagnet.

Electromagnetic beating

Background: The function of beating mechanism is to beat the weft upto fell of cloth with required force to ensure firm weave and good quality of fabric.

Conventional beating system are driven by mechanical drives through cams and cannot be operated at high speeds as in our case for achieving 4800 PPM the velocity of sley must be 383.04 m/s. Object:

1. To complete the beating operation in 1.8 milliseconds and to achieve maximum velocity of 383 m/s.

2. To minimize friction and reduce maintenance.

3. To select heald shafts electromagnetically according to the weave and controlled by microprocessor.

Summary: To complete the beating operation in milliseconds a very high speed is required which is achieved by levitating the sley on the maglev track and propelling it by the magnetic force using the principles/facts.

Description: The newly inserted weft is beated up to the fell of the cloth by the reed, which is rigidly fixed, on the sley. The beating mechanism is same as that of the shedding mechanism but here four maglev tracks are used with powerful propelling electromagnets throughout the length of the reed because the sley becomes heavy due to

1. Its own weight.

2. The weight of the weft_carrier_guides.

3. The weight of electromagnets placed inside the sley for maintaining constant acceleration of weft carrier.

4. The weight of weft tensioning device.

Mechanism of Electromagnetic beating: In figure H-l the side view of the beating mechanism is shown, here A is the maglev track and B is the bus on which sley is fitted, S are the propelling elecfromagnets and R is the reed. The sley will levitate on the maglev track A and is propelled by propelling electromagnets S. During picking when the weft -arrier just passes the reed the elecfromagnets of maglev track and the propelling elecfromagnets are activated. The working of maglev track and the bus is explained below.

Figure H-1 gives the enlarged view of maglev track and bus arrangement, in which A is the maglev track in which the electromagnets a, b, c, d, e are placed. B is the bus having electromagnets embedded in it in all the directions i.e. top, left, right, bottom-left, and bottom- right. The front view of figure H-1 is given in figure H-2 which clears the anangement of electromagnets in maglev track and the bus. Now, the bus B levitates on A the maglev track, due to the repulsive magnetic force of the electromagnets placed in bus and maglev frack. The movement of bus B on maglev track is explained using the principles:

2. When direct cunent is passed through a coil wound on an Iron bar it gets magnetized and the poles can be changed by changing the direction of flow of cunent.

It is clear from figure H-1 and H-2 that the bus B have two sfrong electromagnets in each direction i.e. total ten electromagnets, now how the bus B will travel on maglev frack can be explained by considering any one side of the bus and the maglev frack. Consider figures E-3, E-4, E-5, E-6 in which a, b, c, d and e represents the electromagnets of maglev track and al, a2 represents electromagnets of bus 'B'. The electromagnets al, a2 of bus have opposite polarities and this will remain maintained throughout the journey of the bus. Figure E-3 shows the starting position of bus B here when the electromagnets a and b activated their similar poles repels al and a2 thus due to this magnetic force the electromagnets al and a2 and thus the bus levitates above the maglev frack. Now when it is desired to move the bus the electromagnet c is activated, whose north pole attracts a2, due to this the electromagnets al and a2 moves towards c. The figure E-4 shows how the magnetic forces make the bus to move just by changing the polarities of electromagnets. Here al is repelled by a and at the same time al is attracted by b. a2 is repelled by b and attracted by c.

Now when al and a2 reaches just above b and c the polarities of b and c are changed in such a way that b starts repelling al and c starts repelling a2 because of this arrangement the bus continues to levitate. Figure E-5 shows further movement of the bus when al and a2 were just above b and c electromagnet d is activated so it starts attracting a2 and the bus moves further towards d. In figure E-5 it is shown that al is repelled by b and attracted by c and a2 is repelled by c and attracted by d. In this way the bus can be made to move, on the maglev track just by changing the polarities of the electromagnets The polarities of the electromagnets are controlled by the microprocessor for precise control.

The figure H-2 shows front view of the beating mechanism in which four buses Bl, B2, B3, B4 are shown over four maglev tracks Al, A2, A3, A4. The bus have five electromagnets in pair positioned in all the directions Top, left, right, bottom eft, bottom ight and two elecfromagnets on side for attracting and repelling propelling elecfromagnets. The anangement of electromagnets placed in side of the bus for propelling is shown in figure F-l and 'F-2.

In the figure H-1 two propelling electromagnets are shown which are placed at the forward and backward positions of the reed. The Function of these elecfromagnets is to propel the bus and to stop it also during its return journey. This is explained as suppose that picking is completed now the propelling electromagnet S placed in the backward position of sley gets activated along with maglev frack and propels the sley when the sley reaches its forward most position the propelling electromagnet S placed at the forward most position of sley under the fell of cloth applies repulsive force on the buses carrying the sley to decelerate them, when velocity of the sley reaches to zero the same propelling electromagnet attracts it for bringing it at its conect projecting place and then again propels it by applying repulsive force now when the sley reaches to its backward most position the same task is performed by the propelling elecfromagnet placed at back side of the sley, but at the backward most position the propelling electromagnet holds the sley for a longer time for facilitating the picking operation.

In the bus two more elecfromagnets are placed for repelling and attracting the propelling electromagnets S. The position of these electromagnets in bus is shown in figure F-l and F-2 and denoted by S

Force required for beating: To make the sley to move with the desired velocity the magnetic force has to accelerate the bus with the acceleration a, the force between one bus and maglev track, and between bus and propelling electromagnets is given as

The electromagnet S has to repel the buses for accelerating the sley this force will be added to the magnetic force applied by the electromagnets placed inside the maglev tracks and the bus.

This net force must be equal to

Fn = mass * acceleration required

First of all we will find out the forces due to one pair of electromagnets of top of the bus and then multiply the force by number of pairs.

The magnetic field intensity due to a electromagnet is given by H = Uo * N * i / 2 * l Where N = no of turns, i = cunent, Uo = permeability of free space and 1 = length of solenoid. Let NI, il, 11 represents the number of turns, cunent and length of solenoid of maglev track and Let N2, i3, 14 represents the number of turns, cunent and length of solenoid of bus Then field intensity due to solenoid of maglev track is Uo*Nl*il/2*ll The field intensity due to solenoid of bus is Uo*N2*i2/2*12

From figure E-4 it can be seen that at any instant the electromagnets of bus are in influence of two forces one is attractive and other is repulsive. Consider al of the bus in figure E-4 it is in influence of repulsive and attractive forces of electromagnets a and b respectively of maglev frack. Therefore the field intensity due to a and b will be added and given by

2*( Uo*Nl*il/2*ll) (a)

Similarly, a2 is influenced by repulsive and attractive forces of elecfromagnets b and c. Therefore the field intensity due to b and c will be added and given by

2*( Uo*Nl*il/2*ll) (b)

Adding equations (a) and (b) we get the total field intensity due to electromagnets a, b and c of maglev frack which is

2*( Uo*Nl*il/ll) (c)

Now the elecfromagnet al of bus at the same time is repelling elecfromagnet a and attracting electromagnet b of maglev track, therefore its field intensity also be doubled, it is given by

2*(Uo*N2*i2/2*12) (d)

Similarly for electromagnet a2 of bus field intensity is given by

2*(Uo*N2*i2/2*12) (d)

Total field intensity due to electromagnets of bus is given by

2*(Uo*N2*i2/12) (e)

This force is due to the top pair of bus, Now considering all electromagnets of the bus the force will be calculated. Since the dimensions of bus are different therefore the no. of turns and the cunent will be varied for different electromagnets.

Let, N3,i3 represents the no of turns and cunent for left and right elecfromagnets of the bus and

Let, N4,i4 represents the no of turns and current for bottom_left and bottom right electromagnets of the bus.

Field intensity due to right and left electromagnets os bus is given by.. 4*(Uo*N3*i3/12) (f)

Field intensity due to bottom right and bottom_left electromagnets os bus is given by..

4*(Uo*N4*i4/12) (g)

In equations f and g 12 is taken because the length of all the electromagnets of the bus is same. Now the total field intensity of electromagnets of bus is given by adding the equations (e),(f), and (g) 2*(Uo*N2*i2/12) + 4*(Uo*N3*i3/12) + 4*(Uo*N4*i4/12) 2*Uo/12(N2*i2 + 2*N3*i3 + 2*N4*i4) (h)

The elecfromagnets of the maglev frack will also influence all the electromagnets of bus with the same force. Therefore we have to multiply the equation (c) by 4 (for left, right, bottom_left, and bottom jright elecfromagnets of the bus) We have, 4*(Uo*Nl *il/ll) (i)

Now the force between two magnets is given by

F = k * (ml * m2) / r ^A 2

Where ml and m2 are the pole strengths of the magnets and r is the distance between them, k is constant depends upon the medium between the two magnets k = l / 4 * 3.14 * Uo * Ur

Uo = permeability of free space and Ur is the relative permeability of the medium w.r.t the free space. The value of Uo = 4*3.14*10^A-7 Henry/mtr for air Ur = 1.

Equation (h) is field intensity due to the electromagnets of bus and represents the pole strength of the bus and Equation (g) is field intensity due to the electromagnets of maglev track and represents the pole strength of the maglev track. Thus the force applied by the maglev frack on bus is given by,

F = 8*k*Uo/r^A2*l^A2[(N2*i2 + 2*N3*i3 + 2*N4*i4)*(Nl*il)]....(j)

Now for accelerating the bus we are using elecfromagnets E and El the field intensity of these is given by .. Uo*N6*i6/2*16 (k)

In the bus two more electromagnets are placed for repelling and attracting the propelling electromagnets S. The position of these electromagnets in bus is shown in figure F-l and F-2 and denoted by S Let Ns, is, Is be the no of turns, cunent and length of the solenoid S then its magnetic field intensity is given by Uo*Ns*is/2*ls (1)

Force due to propelling of bus by E or El is given by

Fp = (Uo*k/2*r^A2*ls)*(N6*i6 + Ns*is) (m) as 16 = Is Now total force Fn acting on the bus is given by adding equation (j) and (m)

Fn = (8 * k * Uo / r ^A 2) * [(N2*i2 + 2*N3*i3 +2*N4*i4)*(Nl*il)/l^A2 + (N6*i6 +

Ns*ls)/16*ls]...(n)

As there are four pairs of bus and maglev tracks therefore the equation (n) is multiplied by 4, now the net force Fn becomes .

Fn = (32 * k * Uo / r ^A 2) * [(N2*i2 + 2*N3*i3 +2*N4*i4)*(Nl*il)/l^A2 + (N6*i6 +

Ns*ls)/16*ls]...(n')

This force must be equal to the m*a (m is the mass of sley and a is its acceleration required for achieving required velocity). From equations of motion a = 2 * s / t ^A 2 , s = distance travelled by the sley and t is the time

Weft Tensioning Device.

Background: In present weaving systems except dornier and sulzer the tension of the weft cannot be controlled and since in air jet and water jet looms the weft is inserted into the shed with fluid pressure there is no tension in weft and also due to untwisting of weft during insertion the sfrength of weft thread reduces considerably because of this the strength of fabric in width wise direction is lower than the strength of fabric in warp wise direction, due to which under sfress the weft threads of fabric gets deformed permanently and bagging effect is seen in fabrics.

By providing weft-tensioning mechanism the above mentioned problems can be rectified. The weft crimp can be controlled and consistent fabric quality can be ensured.

Object:

1. Controlling the weft tension to ensure consistent fabric quality and increasing the fabric cover.

2. Controlling weft tension also improves the drape of the fabric.

Summary: A unique weft tensioning mechanism is provided on both sides of the sley in between the maglev track and reed inside the sley. The weft tensioning mechanism comes in action when the weft -arrier has just crossed the reed. This mechanism provides the desired tension in weft and removes the weft from the jaw of the weft carrier. This mechanism improves cover, sfrength and drape of the fabric and improves quality.

Description: The weft tensioning performs two functions:

1. Removal of weft from the jaw of the weft -arrier.

2. Providing required tension in the weft before the accomplishment of beating.

Refer to figure 1-1 in between A the maglev tunnel and B the reed, the weft tensioning mechanism is provided inside the sley base in such a way that it doesn't interferes with the picking operation. The thickness of the weft tensioning mechanism is less than 1.5 cm. The weft tensioning device consists of a gripper E, the guide wires G, suction nozzle N, and provider P. The function of gripper E is to grip the weft and it is capable of moving up and down very fast. The guide wires G are used to guide weft when th gripper comes down. The Provider P guides the weft into the jaw of gripper and can move up and down. The suction nozzle N sucks excess length of weft after beating when sley moves back. During picking operation when the weft carrier just crosses the reed and enters the maglev tunnel, the gripper along with guide wires move upwards, and the provider moves downwards such that it guides the weft to the gripper, the gripper after gripping the weft comes down and the provider returns to its position. After gripping the gripper and the guide wires moves downward hi such a way that the velocity of the gripper is more than the velocity of the guides. The weft tensioning mechanisms are provided at both the sides of the machine and will work simultaneously. During the downward motion of the grippers the weft present in the shed gets tensioned upto the desired level. The weft gets tensioned because of the difference in velocities during downward motion of the gripper and the guides. The tension provided in the weft is directly proportional to the difference in velocities of gripper and guide wire. More the difference in velocities more will be the tension in weft.

The function of the cutter C is to cut the weft from the sley side end of the gripper when the shed has just changed and the sley has just started moving back at this cutting position the weft tensioning mechanism enters completely into the sley body. Mechanism for stopping the loom in case if weft is broken during tensioning: If during tensioning. weft breaks the machine should stop immediately and the broken weft must be removed to avoid defects in fabric. For sensing the weft has broken or not the leg of guide wires have a small cylindrical permanent magnet embed in it, and a copper coil wraps the legs of guide wire. If before beating the weft breaks the guide wire will move up suddenly and this sudden process will induce a cunent in the coil, which can be sensed and the machine can be stopped immediately. The figure 1-2 shows the mechanism and the arrangement of guide wire, magnetic and the coil. Now there are two conditions when the guide wire will up suddenly:

1. When picking is complete the guide wire along with gripper moves up and induces cunent in the coil.

2. When the weft under tension breaks suddenly the guide wire will move up suddenly.

The first problem can be rectified by knowing the position of sley because at this time the sley has just started moving ahead for beating.

For second case it is obvious that the sley is on the verge of beating and weft under tension is broken, here after knowing the position of sley (during forward motion) the circuit attached with guide wire coil gets activated and stops the loom. We have already discussed that during downward motion the velocity of guide wire will be lesser than the velocity of the gripper, for this different drives are provided to the gripper and the guide wire. The drive will be given by two servo motors because the direction of rotation and RPM of these motors can be easily changed by a microprocessor.

Weft providing mechanism

Background: The function of weft providing mechanism is to insert the weft into the jaws of weft carrier when it reaches near to the propelling elecfromagnet from other side of the loom. The weft is inserted into the shed from both the directions i.e. when the weft carrier moves from left to right and when weft carrier moves from right to left.

Object: To insert weft into the jaw of the weft carrier. Summary: The weft is carried by the weft carrier into the shed but due to unwinding tension the weft will try to decelerate the weft carrier. Moreover as the velocity of weftjaπier is very high and the weft carrier is accelerated in a very short time due to inertia of rest the weft will either breaks or come out of the jaw of weftj-arrier. To avoid this the weft must be inserted into the jaw of weftj-arrier at conect position and a metered quantity of weft should be unwound from the cone and released without friction and tension during the insertion of the pick. The weft-metering device will unwound the metered quantity of weft according to the loom width from cone and will release it during picking. The weft metering device will be same as that used in present air jet looms therefore we will discuss only the weft providing mechanism.

Description: The figure J-l shows how the clips are ananged in the jaws of the weft carrier so as to grip the weft firmly. The weft carrier has two rectangular slots cut at its top and the two leaf spring type clips are fixed into the slot. The clip will hold the weft and ensure that the weft cannot move out of the weft carrier until the picking gets completed. In figure J-2 consider that the weft carrier is traveling from left side to right side of the machine along with the weft. When the weftj-arrier reaches to right side of the machine the weft is fed into the jaw E-2 of the weft_carrier by weft feeding mechanism.

After beating both left and right side cutter cut the weft, consider the case when the sley has just started moving back, the suction nozzle A on its left side sucks the excess length of the weft for getting ready to insert weft in weft carrier on its incoming journey, the cutter CI on the right side cuts the excess length from suction nozzle A.

After the weft has been cut by other side's cutter the trailing end of weft is bring upto the suction nozzle by a motor ml when it rotates the loop attached with it moves up and brings the weft upto the suction nozzle A. The same process is repeated for the return journey of weft carrier. Guides G are provided for guiding the weft coming from metering device to weft carrier. In these guides during picking air is blowed in the direction of motion of weft at high pressure this reduces friction and ensures easy carrying of weft by the weftj-arrier. Optically sensed warp stop motion.

Background: Warp stop motion stops the loom or generates a signal for stopping the loom in the case if warp thread is broken during weaving process to ensure the good quality of the fabric present warp stop motions comes in action when the drop pin drops in a drop wire under acceleration due to gravities. The present system will not work in electromagnetic weaving machine because here the time available to stop the loom in the event of warp breakage is very less and the acceleration due to gravity will be insufficient in our case and before the warp stop motion sends signal for stopping the machine many machine cycles gets completed. Moreover present warp stop motion does not indicates which warp thread has broken, therefore it takes time to find out and mend the broken thread this reduces operator's efficiency.

Object:

1. To increase the sensitivity and reactivity of the warp stop motion so that it can work at high speeds.

2. To indicate the location of warp breakage.

3. To increase the operator's efficiency.

4. Ensure good quality of fabric.

Summary: To make the warp stop motion to work at high speeds specially designed round drop pins are used for sensing whether warp has thread has broken or not. The acceleration of drop pins is increased with the help of springs and electromagnets. Due to the falling of drop pin the laser will gets interrupted and the machine is stopped at conect position. Laser detectors are placed in each row and when they gets interrupted by the drop pin, a signal is send to the microprocessor for flashing the light emitting diode indicating the position of warp breakage.

Description: The function of warp stop motion is to stop the machine at crossed shed position when the warp thread breaks and prevent fabric from damage. The machine must be stopped in the crossed shed because the tension in warp threads in this position is minimum and this will facilitate the mending of broken warp thread. The diagrams K-l, K-2, K-3 shows how the optically sensed warp stop motion will work. A is the top plate having small hole ananged in zigzag manner, The zigzag arrangement accommodates more warp yams in a given space since the diameter of drop pins is 2.5 to 3.5 times that of the diameter of the warp thread. Similar holes ananged in zigzag manner are made im bottom plate B also. In each hole of top plate there is a small spring D whose function is to press the drop pin C against the warp tension towards the bottom plate B. The drop pin C is designed in such a way that warp yarn is inserted in it through the opening provided at its one end. The inner side of the opening is curved so as to guide the warp thread at the center of drop pin during shedding operation and this Anangement ensures that the warp will not come out of the pin during shedding. At the bottom of the drop pin a small magnet is glued having high pole strength shown as M in the figure K-l .

E is the laser transmitter placed in the bottom the plate B, it produces laser through out the working cycle of the machine, and the laser is received by photo receiver F. The laser transmitters are placed in each row of the drop pin in the bottom of the plate B i.e. number of laser transmitters is equal to the number of rows of drop pins. H is the electromagnetic bar placed beneath the bottom plate Band its function is to pull the drop the drop pins by attracting the magnet M glued in the bottom of the drop pin. I is the warp end shown passing through the drop pin.

In the top plate at front side of plate holes are provided which are in line with the opening of the drop pin and ananged in zigzag manner so as to use the space available. Through these holes and the warp ends can be taken out of the opening of the drop pins from either side of the boxes in which the drop pins are placed and can be mended.

Laser detectors are placed in each row and when they gets interrupted by the drop pin, a signal is send to the microprocessor for flashing the light emitting diode indicating the position of warp breakage.

Now when the warp end breaks the drop pin is pulled downwards towards the bottom of the plate B with acceleration greater than "the acceleration due to gravity g" because here the drop pins are accelerated by three forces which are.

1. The strain energy of springs D

2. The attractive force between electromagnet H and the magnet M of drop pin.

3. Weight m*g here m = mass of drop pin and g is acceleration due to gravity 'g'. When the drop pin reaches the bottom of the plate it interrupts the laser the receiver generates a signal to microprocessor for stopping the machine. Now if the distance travelled by drop pin to interrupt the laser is s meter then the time taken by drop pin to reach the bottom plate is calculated as s = u * t + l / 2 * (a * t ^A 2), where v and u are the final and initial velocity of the drop pin, a is its acceleration and t is time or T = (2 * s / a) ^A l / 2 77ze acceleration gained by the drop pin C is due to three forces

1. Due to the springs D:

The spring D is compressed upwards due to the tension in warp and this warp tension causes a twisting moment in the spring wire due to which torsional shear stress is produced in the spring and it is given by f = 8*W*D/3.14*d^A3

Where D = mean diameter of the spring of the coil, d = diameter of the spring wire, n = number of turns, G = the modulus of rigidity, W = axial load on the spring due to tension in warp thread, ' t' = maximum shear stress induced in the wire, C = Spring index D/d, ' d' = deflection of spring due to axial load W or warp tension T

The deflection of spring is given by d' = 8*W*C^A3*n/G*d

The strain energy stored in spring due to warp tension T is U = l/2*(W*d')

On putting values of W and d' from previous equations we get

U = (t'^Λ2/4*k^A2*G)*N, where N is the volume of the spring (3.14*D*n)*(3.14/4 * d^Λ2)

When the warp end brakes this strain energy is converted into the kinetic energy l/2*m*v^A2 of the drop pin. i.e.

(f^Λ2/4*k^Λ2*G)*N = (l/2)*m*v^A2

From equations of motion v^A2 = u^A2 + 2*a*s or v^A2 = 2*a*s since initial velocity is zero

Therefore (f^A2/4*k^A2*G)*N = m*a'*s or a' = (t'^A2*N/4*k^A2*G*m*s) (a)

2. Due to force of attraction between electromagnet H and magnet of drop pin M Let ml be the magnetic moment of magnet M and the field intensity of the electromagnet H is given by Uo*Ν*i/2*l, where N = number of turns, i the cunent and 1 is the length of the electromagnet. Therefore force F = (k*ml/r^A2)*(Uo*N*i/2*l), where r is the distance between the electromagnet H and magnet M

Or F = (k*Uo*N*i*ml)/(2*l*r^A2)

This force will be equal to m*a', where m = mass of the drop pin and a' is the acceleration due to magnetic force. Therefore a* = k*Uo*N*i*ml/2*l*r^A2*m (b)

Let total acceleration acting on the drop pin is a" then a" = (t'^A2*V/4*k^A2*G*m*s) + k*Uo*N*i*ml/2*l*r^A2*m + g (c)

Now as the time taken by drop pin to reach bottom of the plate is given by t = (2*s/a")^Al/2 (d)

Therefore on putting the value of a" in equation d the time taken by the drop pin to interrupt the laser can be find out.

From equation d it is clear that for minimum time we have to increase a" and a" has direct relationship with

1. T^A2 (tension due to warp threads), 2. D (mean diameter of the spring D), 3. n (number of active coils), 4. Uo (permeability of free space), 5. N (number of turns), 6. i (cunent)

And in inverse relationship with

1. G (modulus of rigidity), 2. d^A4 (diameter of spring wire), 3. m (mass of drop pin)

4. s (distance through which drop pin falls on bottom plate), 5. 1 (length of the electromagnet).

Now D (mean diameter of the spring D), n (number of active coils) and d (diameter of spring wire), N (number of turns) will depend on the space available and design of the spring and must be constant.

T^A2 (tension due to warp threads), Uo (permeability of free space) are also constant so for increasing the acceleration a" we have to increase the cunent i.

PIVTake up motion.

Background: The function of take up motion is to wind up the cloth formed on the cloth roll under tension without slipping and maintaining a constant surface speed of the cloth roll as its diameter increases. This is achieved by providing the drive to the cloth roll through motor and gears and decreasing the RPM of the cloth roll as its diameter increases. The surface speed of the cloth roll decides the picks per inch in the cloth, more the take up lesser will be the picks per inch in the cloth and vice versa. In all present systems to change picks per inch the pick gear has to be changed this procedure is not automatic and has to be performed manually this takes time and inconvenient.

For automating the take up motion a modified PIN gearbox is used, the PIN gearboxes have been already used in textile spinning and it is only modified to automate the take up motion. The PIV gear box uses movable conical gears to transfer the power. The conical gears can move parallel to the shaft but when the driving shaft gears moves in opposite direction the driven shaft gears comes closer, this anangement changes the speed ratio of the driving and driven shafts very accurately.

Object: To change the picks per inch automatically, and to wind up the cloth on cloth roll under uniform tension and with constant surface speed.

Summary: For changing the picks per inch automatically through a microprocessor certain modifications are done in the present PIN gearbox. The motion of the conical gears is controlled by a servo motor in such a way that when the driving conical gears moves apart the driven conical gears comes closer and vice versa.

Description: The take up motion has to wind up the cloth under tension With uniform surface speed. The surface speed of the cloth roll determines the picks per inch in the cloth more the surface speed lesser will be the picks per inch and vice versa. For automating the take up motion certain modifications are done in the present PIN gearbox. The motion of the conical gears is controlled by the servo motor in, such a way that when the driving conical gears moves apart the driven conical gears comes closer and vice versa. The concept used here is that the surface speed of the driving and driven gears remains same i.e. if Νl, Ν2 be the RPM of driving and driven gears and DI, D2 are the diameters of driving and driven gears then D1*N1 = D2*N2 so from this equation by changing the diameters of conical gears their speed ratio can be changed. The driven shaft is attached with the cloth roll so any variations in speed of this shaft will be reflected in the surface speed of the cloth roll. Mechanism of the PIV take up motion: Consider figure L-l in which Ml is the driving motor, CI is the driving shaft, c2 is the driven shaft, Al and A2 are fixed driving and driven conical gears Bl and B2 are movable conical gears, M2 is the servo motor, L is the link and T is the threaded shaft. The conical gears Bl and B2 can move parallel to their respective shafts.

Drive is transmitted to bottom shaft CI from the main motor Ml, via a gear box From bottom shaft the drive is transmitted to the shaft C2 by a specially designed chain. From shaft C2 the cloth roll, pressure roll and emery rolls are driven. Now when we have to change the picks per inch we have to change the RPM of the cloth roll, which can be done by moving the conical gears Bl and B2 parallel to the shafts CI and C2 inward or outward. If we require to lessen the picks per inch then the RPM of the cloth roll must be increased for this the servo motor M2 is activated and when it rotates clockwise the link L will moves towards M2 and by doing so it moves the upper conical gear B2 away from A2 and hence decreases he diameter of driven gear now as the link L is pivoted at O its lower part pushes the lower conical gear Bl towards Al and hence increases the effective diameter of the gear. Now as D1*N1 = D2*N2 the RPM of the cloth roll increases.

For increasing the picks per inch we have to decrease the RPM of the cloth roll or upper shaft C2. or this the servo motor M2 is rotated anticlockwise so the link L from upper moves away from the Motor M2 and pushes the conical gear B2 towards Al and increases the diameter of of upper gear. The lower part of the link L moves towards motor M2 and pulls the conical gear Bl away from the gear Al this action decreases the diameter of lower gear, so it decreases the RPM of cloth roll according to the relation D1*N1=D2*N2.

As the diameter of the cloth roll increases its surface speed also increases and this increases the tension in the fabric and subsequently the machine ceases to run to avoid this problem for uniform surface speed (3.14*D*N) we have to decrease the RPM of motor Ml as the diameter of cloth roll increases according to the relation D (diameter of gear) is inversely proportional to N (RPM) this can be achieved by varying the speed of main motor Ml by varying the cunent or voltage.

The amount of warp, which has converted into cloth, must be released from the weaver's beam this task of imwinding the warp from weaver's beam is done by the Let off motion which works simultaneously with the take up motion.

Claims

Claims:"The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: "

1. A shedding mechanism which comprises of lifting and lowering the heald shafts by magnetically levitating and moving the upper and lower buses by <the use of electromagnets placed in all directions of the bus and propelling the buses by the propelling electromagnets and selecting the desired heald shaft by pins and electromagnet at the centre position .

2. A shedding mechanism in which heald shafts are selected by bolt like pins having magnetic head by an electromagnet placed in the bus at the side of the heald shaft which is having holes for accommodating the pins.

3. A bus as said in 1 having electromagnets placed in all the directions in a pair of two, at the top of which magnetic pins and electromagnets are placed for selecting the heald shaft and two horse shoe type electromagnets placed on the sides of bus for getting attracted or repelled by the propelling electromagnets placed at the top, bottom and centre of the maglev track which is placed vertically.

4. A maglev track as said in 3 vertically placed and having electromagnets embedded in it for levitating and providing motion to the bus.

5. The selection of heald shafts as said in I at the center by the pins having magnetic head, from both the sides with the electromagnets of either upper or lower bus according to the lift plan.

6. The lifting and lowering of selected heald shaft as said in 1 by four pins two each side in a group of four by the upper or lower bus for providing space for the bus for next four heald shafts.

7. A Picking mechanism comprising of maglev tunnel at both the sides of machine levitating and providing motion to the weft carrier and propelling electromagnets for accelerating the weft carrier and decelerating the weft carrier by the other side maglev tunnel.

8. The magnetic levitating tunnel in which weft carrier can accommodate leaving a space of 1 mm in all directions as said in 7 in which the electromagnets are placed in all directions and the propelling electromagnet having hole in its centre so that weft can pass through it and gripped by the clips of weft carrier.

9. A rectangular magnetic weft carrier as said in 7 having curves at its both ends for minimizing the air resistance and rectangular jaws having clips at both ends for holding the weft.

10. The decelerating mechanism for weft carrier as said in 7 by the maglev tunnel using repulsive magnetic force.

11. The weft carrier guides for guiding the weft carrier across the machine during its journey as said in 7 and having cut at the top left for facilitating the weft to come out. during beating.

12. A sley in which electromagnets are embedded in base through out its length for maintaining the uniform acceleration of the weft carrier.

13. A beating mechanism comprises of maglev track and buses for levitating and moving the sley and propelling electromagnets for accelerating the sley and stopping the same when the bus approaches the propelling electromagnets.

14. A weft tensioning device placed at both sides of loom in between the sley and maglev tunnel comprises of one gripper, two guides and one provider for each, for providing the tension in the weft.

15. The guides as said in 14 and having the magnets in its legs.

16. The velocities of gripper and guides as said in 14 for is different for providing the tension in the weft.

17. The warp stop motion in which the drop pins are accelerated by strain energy of the . springs and the magnetic force of the electromagnets and a signal is generated when the laser is interrupted due to the falling of drop pin for stopping the machine and indicating the position of warp breakage.

18. The drop pins as said in 17 are circular and have a cylindrical magnet glued at its bottom to get attracted or repelled by the electromagnetic bar.

19. The drop pin as said in 17 is circular in cross section and having opening at one end with curves inside so that the warp cannot get out of the drop pin.

20. The top and bottom boxes as said in 17 having holes zigzagly arranged to accumulate springs in the top box and providing space for drop pin.

21. The bottom box as said in 20 having electromagnetic base for attracting the drop pins.

22. A automatic pick changing mechanism comprising of modified PIV gear box.