|Title of Invention||
A RAPIER DRIVE SYSTEM FOR SHUTTLELESS LOOMS
|Abstract||This invention relates to a rapier drive system. It consists of a rapier drive belt drawably connected by means of a first and second sprocked wheels. The second sprocket wheel is compounded with an eccentric wheel connected to a rotatably drawable rapier drive wheel through a universally coupled rack lever and pinion. The rapier belt is provided with rapier heads and is movably disposed on a sky. FIG 1|
This invention relates to a rapier drive system for shuttleless looms and is useful in powerloom employed in the production of fabrics in the weaving sector of the textile industry.
In general, the weaving operation is carried out by forming a shed by the heald frames and weft yarn is inserted using a shuttle. The shuttle is a device which carries a small quantity of weft yarn. During weaving, the shuttle propels from one end to another by means of a picking mechanism. Once the weft yarn is inserted, the shed is closed and the yam is beaten-up with the fell of the cloth by means of reed which is fixed on the sley. This process continues and the cloth is formed.
In order to simplify the process of weft insertion and to increase the speed of the loom, various weft insertion devices were developed. One such device is called as rapier insertion system. This particular weft insertion system has been used in advanced weaving machines with a cumbersome mechanical movements.
The powerlooms generally incorporate shuttle propulsion technique, which is the simplest and cost effective method when compared to all other systems. The shuttle loom has a limitation of speed and requires additional process like pirn winding etc. Normally the shuttle containing weft pirn is propelled from one end of the loom to another side at a greater speed. Since the shuttle has to travel a small distance before reaching die other side, there are mechanisms to stop the shuttle (check-in-device) on either side of the loom.
While weaving considerable energy is lost by propelling the shuttle from one side to another and stopping the same within a short distance (i.e width of the loom). Hence, to minimise the wastage of energy and to avoid the intermediate process of pirn winding, shuttklcss looms have been developed.
In all shuttle looms, the height of shed opening is more to allow the shuttle to pass through the shed while picking. This process considerably increase the tension on the warp yarn which may result in more breakages during weaving. Whereas, in me case of rapier weaving machines, the depth of shed is very less so as to accommodate the small rapier heads which carries and transfer the weft during weaving.
The energy required to propel the shuttle at a high speed and opening of warp sheets to form a shed are minimised to a greater extent in shuttleless weaving machines. Similarly, the energy loss during shuttle check-in at every pick is also saved. These basic design changes has helped to overcome the speed limitation in weaving. This new invention of rapier drive mechanism can be incorporated even in low cost looms, so that a considerable increase in speed of loom and saving in energy can be achieved. In addition, the intermediate process of pirn winding shall also be eliminated.
Insertion of rapier is a mechanically refined version of the primitive methods of fabric production in which the weft, secured in a slot in a stick, was pushed through the warp shed. It was also the system adopted for the first shuttleless weaving machines. Although all rapier weaving machines can be classified as a single group for convenience, they can be sub-classified by the type of rapier namely rigid, flexible or telescopic.
The rigid rapiers are guided through the shed from outside the working width. Some types are provided with a supporting surface on the sley. In contrast, flexible rapiers used on wider width weaving machines are guided through a track formed by ribs. The disadvantage of the rigid rapier system is that it requires large floor space (at least twice that of the fabric width) because the rigid rapier must be pulled out completely from the warp sheet before beatup. This difficulty is overcome by using a telescopic rapier which consists of two or three telescopic components. One component is directly connected to the rapier drive and its weft way position that of the second one. The rapier drive is connected to a slider whose position determines the rapier component configuration. The rapier is fully extended when inserted into the shed and the components of telescopic together with rapier are out of shed when the rapier is withdrawn.
The rapier mechanism and the drive system used in most of the weaving machines are having the following disadvantages:
- complicated engineering design to be understood by the personnel in the decentralised powerloom industry.
- since more number of components are involved in the drive system, it is costlier.
- maintenance of the machine is expensive.
- requires qualified engineers to install and maintain.
- difficult to manufacture with the available facilities.
- requires precision setting
The main objects of the invention are:
- to design and develop a low cost rapier drive system which can be manufactured by small powerloom manufactures.
- to arrive at a simple design so that it shall be maintained by the powerloom weavers themselves.
- simple gearing and transmission mechanism to reduce the power consumption.
- to enable the weaving of muhi colour weft without using drop box mechanism.
- to increase the speed of the loom and thereby fabric production and labour productivity.
- to improve the quality of the fabric when compared to ordinary plain loom.
The new type of rapier drive mechanism according to this invention facilitates continuous weft insertion directly from the cone. Hence, the intermediate process of pirn winding is eliminated.
Stopping of loom for weft replenishment in the shuttle is eliminated and the loom can be worked continuously. This eliminates the occurrence of starting mark (a fabric defect) in the cloth.
Continuous working of loom increases the fabric production and labour productivity. Weaving of defect free fabrics enables higher cloth realisation. Very simple mechanism which can be easily understood and maintained by the power loom weavers.
Flexibility of weaving plain, stripped and checked fabrics using weft selector mechanism. Even in plain grey fabrics, mixing of weft using the selector enhances the quality by minimising weft way defects such as weft bars.
In most of the rapier looms, the to and fro movement of the rapiers is derived from a cam. The type of cams employed for driving the rapier is
either a grooved cam or matched pair of cams. The first suffers from the defect arising from the need for the grooves to be wide enough for the cam follower not to touch both sides of it simultaneously. This results in unduly high noise and wear. Matched cams, if made accurately, are quiet and durable, but expensive.
The drive system according to our invention provides to and fro movement of the rapiers by means of a linkage mechanism and an eccentric. The use of this linkage mechanism has the advantages of simplicity and reliability and is cheap, quiet and consumes less energy than a cam mechanism. The mechanism can be easily incorporated in the poweiioom either in the new loom or as a conversion to the existing plain loom.
This invention essentially consists of an eccentric wheel driven by a chain drive or set of wheels from the bottom shaft of the loom. An oscillating lever connected to the eccentric connected to a vertical rack drives the pinion compounded to the rapier drive wheel. The rapier drive wheel drives the perforated timing belt in which the rapier heads are attached. The rapier heads carries the weft yarn from the right side of the loom to the left side of the loom by transferring the yarn in the middle. The stationary weft feeder and weft holding cum cutting device facilitates the rapiers to insert the exact length of yarn into the warp to complete the process of weft insertion.
This invention relates to a rapier drive system for shuttleless looms comprising at least one endless rapier belt provided with rapier heads thereon, said belt being movabry disposed on a sky, a drive assembly consisting of a drivably connected first and second sprocket wheels, said second sprocket wheel compounded with an eccentric wheel, said second sprocket wheel and said eccentric wheel revolvable on a loose boss of a rocking shaft, a rotatabry drivable rapier drive wheel drivably coupled to said eccentric wheel through a rack lever, the rotary motion of said rapier drive wheel driving said rapier drive belt and the up and down movement of said rack lever providing to and fro movement to said rapier heads.
This invention will now be described with reference to the figures in the accompanying drawings, wherein Fig. 1 shows the side sectional view and Fig. II shows the elevation.
The rapier drive system essentially consists of a sprocket wheel (1) connected to the bottom shaft (2) of the loom. A chain drive (3) connecting the sprocket drives the other sprocket wheel (4). This sprocket is compounded to an eccentric wheel (5) and the entire unit is revolving on a loose boss of the rocking shaft (6). The eccentric wheel is connected by means of two universal coupling (7) which drives the rack lever (8). The pinion ( 9) compounded to the rapier drive wheel (10) is rotated by the rack.
The rotary motion of rapier wheel moves the rapier drive belt (11) and in torn the rapier head. The up and down movement of the rack lever gives to and fro movement for the rapiers. The flexible rapier drive belt is guided in an enclosure rib (12). A similar set of arrangement drives the other rapier at the other side of the loom. A set of rapier heads left (13) and right (14) are moving on the sley (15) till they meet at the middle and return back.
During weaving operation the weft yarn from right side of the loom is picked by the right side rapier head (14) and the tip of the yarn is transferred at the middle portion of the sley to the left hand rapier head (13) which takes to the left extreme of the cloth selvedge end at the same time the right side rapier returns to its extreme of the sley to pick the next pick of yarn for inserting into the shed.
The weaving process consists of three primary functions and they are called shedding, picking and beating-up. A sheet of parallel yarns is separated (shed formation) during shedding operation. A single yarn is inserted into the shed which is termed as picking or weft insertion. The beat-up is the process of pushing the weft thread as close as possible to the earlier weft thread thus forming the cloth.
The picking or weft insertion is carried out by various mechanisms such as propulsion of shuttle, gripper or projectile, rapier, air-jet, water jet etc. Different types of rapier drives are commercially used in the weaving machines. All these looms are costly and beyond the reach of power loom weaver. The newly invented rapier drive mechanism is very simple in design and can be used in any of the low technology looms available in the market. The same can be used in new looms and also it can be retrofitted in the existing loom.
During operation of loom, the sprocket connected to the bottom shaft of the loom drives the eccentric wheel through chain drive. The universal coupling and the lever connected to the rack is given vertical up and down movement from the eccentric. The movement of the rack gives the oscillating motion to the rapier drive wheel through an integral pinion. The rapier drive wheel provides the rapier belt a to and fro motion and the giver and taker rapier head on either side inserting the weft thread from one selvedge (edge of the fabric) to another.
Alterations and modifications known to persons skilled in the art are within the scope of this invention and the appended claims.
1. A rapier drive system for shuttleless looms comprising at least one endless rapier belt (11) provided with rapier heads (13, 14) thereon, said belt being movably disposed on a sley (15) characterized in that said drive system comprises a drive assembly consisting of a drivably connected first and second sprocket wheels (1, 4), said second sprocket wheel (4) compounded with an eccentric wheel (5), said second sprocket wheel (4) and said eccentric wheel (5) revolvable on a loose boss of a rocking shaft (6), a rotatably drivable rapier drive wheel (10) drivably coupled to said eccentric wheel (5) through a rack lever (8), the rotary motion of said rapier drive wheel (10) driving said rapier drive belt (11) and the up and down movement of said rack lever (8) providing to and fro movement to said rapier heads.
2. The rapier drive system as claimed in claim 1, wherein said first sprocket wheel is connected to the bottom shaft of said loom.
3. The rapier drive system as claimed in claim 1 and 2, wherein said first and second sprocket wheels are connected by means of a chain drive.
4. The rapier drive system as claimed in claims 1 to 3, wherein said eccentric wheel is connected to said rapier wheel by means of two universal couplings and a rack lever.
5. The rapier drive system as claimed in claims 1 to 4, wherein said rapier wheel is connected to said rack lever through a pinion to rotatably drive the same.
6. The rapier drive system as claimed in claims 1 to 5, wherein said rapier belt is flexible and is guided through an enclosure.
7. The rapier drive system as claimed in claims 1 to 6, provided with at least two
rapier heads, one on the left and the other on the right side of said sley.
8. A rapier drive system for shuttleless looms substantially as herein described with
particular reference to the accompanying drawings.
DATED 16 DAY OF OCTOBER 2001
|Indian Patent Application Number||851/MAS/2001|
|PG Journal Number||11/2011|
|Date of Filing||16-Oct-2001|
|Name of Patentee||THE SOUTH INDIA TEXTILE RESEARCH ASSOCIATION|
|Applicant Address||AERODROME POST, COIMBATORE-641 014, TAMIL NADU|
|PCT International Classification Number||D03D 47/00|
|PCT International Application Number||N/A|
|PCT International Filing date|