FIELD OF INVENTION
The invention relates to a circular loom to manufacture doup fabric. In particular it relates to doup fabric circular looms provided with heald assemblies to achieve high speed weaving.
BACKGROUND OF INVENTION
Doup fabric is of importance for producing light weight fabric with suitable ventilation of product. In such fabric, two neighbouring warp threads no longer lie parallel next to each other, but the so-called doup thread loops or crosses the other warp thread, here referred to as the ground thread, in such a way that the weft threads are bound in unable to slip.
Conventional circular looms employ healds that have lateral displacement mechanisms. However, one key problem faced by the existing devices is that at high operating speeds and which involve complex movements of the threads, there is a lot of friction between the elements of the heald and the warp threads passing through. Further, the lateral displacement system for doup end of warp should also be structurally reinforced to sustain high speed operation with minimal maintenance.
There are systems available for producing such doup fabrics also on circular looms, in particular for the manufacture of tubular fabrics made from narrow plastic strands for the fabrication of sacks, however, they have higher maintenance issues and low production speeds.
OBJECTS OF INVENTION
The object of the invention is to arrange and guide the oppositely-phased up-and-down-moving partial healds in such a way that after each shed-forming alternating motion, the two interacting weft threads permit a reciprocal displacement of one end.

Another object of invention is to provide a partial heald that has longer service life.
A further object of the invention is to provide a lateral displacement system for the partial heald that is able to operate at a high speed of the modern doup looms with minimal maintenance.
SUMMARY OF INVENTION
The invention relates to a circular loom to manufacture doup fabric (F). In particular it relates to circular looms provided with plurality heald assemblies to achieve high speed weaving. The circular loom for producing endless tubular doup woven fabric (F) basically consists of the main frame on which the main motor driving the shedding cam and swing control cam are mounted; it also propels the shuttles on the endless reed (14). A partial healds belt assembly which facilitates displacement of the interacting warp threads is provided on the loom. The warp threads of at least one of the pair of partial healds (4, 5), which are provided with thread eyes (3) through which the threads pass, are guided freely by thread guide means to bring about the shedding, and, on the other partial heald, to bring about a side change. In one aspect of the invention, to cope with the high operating speeds and which involve complex movements of the threads, and the friction generated therefrom, the eyes (3) are provided with a ceramic insert (3A). The lateral movement needed to create the doup fabric (F) facilitated by a swing control cam (6B) that pushes the swing control cam roller (6A) against the torsion spring (13) mounted with swivel bush (12) resulting in the swinging motion of swivel arm (11). As an aspect of the invention, the swivel bush (12) is made of metallic material.
LIST OF FIGURES
Figure 1 shows a perspective view of the assembled heald belt assembly of the invention

Figure 2 shows a schematic of the movement of the assembled heald belt
assembly of the invention
Figure 3 shows a circular loom fitted with the partial heald assembly of the
invention
Figure 4 shows the doup weave tubular fabric portion

LIST OF PARTS
1. Pulley
2. Belt 25
3. Thread eye
3A. Replaceable insert
4. Partial heald-A
4A. lateral movement facilitator
4B. vertical movemerSO
facilitator
4C. Guide means
5. Partial heald-B
6. First cam/follower assembly
6A - first follower or roller o35
swing control cam
follower/roller
6B - first cam or swing control cam

7. Second cam/follower assembly
7A - second follower or roller or
shedding cam follower/roller 7B - second cam or shedding cam
8. Prongs or teeth of guide means
9. Pivot
10. Rocking Lever
11. Swivel arm
12. Swivel bush
13. Torsion spring
14. Reed
15. Shedding cam lever
16. Ground warp end or thread
17. Cross-over warp end of thread
18. Weft thread
F - Fabric

DETAIL DESCRIPTION OF INVENTION
The circular loom for producing endless tubular doup woven fabric (F) basically consists of the main frame on which the main motor (not shown in figures) driving the shedding cam (7B) and swing control cam (6B) is mounted; it also propels the shuttles (not shown in figures) on the endless reed (14). The take-up drive and motor are mounted on the top frame while the warp let-off drive and

motor is mounted on both side frame (not shown in figures). Each system drive has individual motor and are controlled through central electronic control unit.
The aforementioned objects are met by providing a plurality of partial healds belt assembly around the main frame circumference which facilitates displacement of the interacting warp threads. The partial healds belt assembly comprises (see Figure 1 for the perspective view) a pair of partial healds - partial heald-A (4) and partial heald-B (5) - of which at least one partial heald is engaged after each shedding motion. This allows production of the doup fabric (F) via an instantaneous lateral relative counter-displacement of the partial healds (4, 5) for the reciprocal displacement of the doup thread (17) which extends lengthwise to the ground warp thread (16). The warp threads of one of the pair of partial healds (4, 5) are guided freely by thread guide means (4C) to bring about the shedding, and, on the other partial heald, to bring about a side change. However, one key problem faced by the existing devices is that at high operating speeds and which involve complex movements of the threads, there is a lot of friction between the elements of the heald and the warp threads passing through. Further, the lateral displacement system for doup end (17) of warp should also be reinforced to sustain high speed operation with minimal maintenance.
The partial heald-A (4) is made in two components - a vertical movement facilitator (4B) and a lateral movement facilitator (4A). The components of the lateral movement facilitator (4A) are preferably made of plastic material. The vertical movement facilitator (4B) is made of any material that is capable of withstanding jerks, vibrations, and shocks, such as metals and/or plastic or their combination.
Figures 2 and 3 show a schematic of the movement of the assembled heald belt assembly of the invention while making the doup fabric (F). The two partial healds (4, 5) are formed from slit belt strands of flexible material, whereby the

partial healds are connected using a belt (2) in a continuous belt form. A pair of pulleys (1) supports the continuous belt holding the pair of healds (4, 5). A relative lateral movement is imparted to the lateral movement facilitator (4A) which moved about a pivot (9). The relative lateral movement is imparted using a first cam/follower arrangement which allows the lateral movement facilitator (4A) to rotate in its own plane. The first cam/follower assembly comprises a first follower (6A) and a first cam (6B) that ultimately facilitate the rocking movement of the lateral movement facilitator (4A) in its own plane. A shedding movement is imparted to partial heald-A (4) through a second cam/follower assembly (also termed as shedding cam assembly) that allows upward/downward movement of the vertical movement facilitator (4B). The second cam/follower assembly comprises a second follower or a shedding cam follower or roller (7A) and a second cam or a shedding cam (7B).
For example, doup fabric (F) is a result of one warp thread jumping onto the other side of the other warp thread caused by the preliminary tension developed in the warp threads produced by the pair of partial healds (4, 5). To facilitate this, the pair of partial heads engages with each other in a comb-like arrangement of guide means (4C) provide on at least one of the partial healds (4, 5). The guide means have a thread eye (3) at their free ends through which threads (16, 17) pass for shedding and also thread guide slits between the consecutive guides which are used for bringing about the side change. To facilitate the relatively friction-free contact between the warp thread and the eye (3), for at least one of the two partial healds (4 or 5) of the pair of partial healds (4, 5), the eye (3) is provided with a replaceable insert (3A), made preferably of ceramic material or of metallic material provided with coating or lamination of suitable wear resistance.
The mechanism through which the doup fabric (F) is weaved is now explained in detail.

As discussed earlier, in the inventive circular loom for cross warp weave, the partial healds (4, 5) can be made from slit belt strands, wherein for approximately each partial heald (4, 5), an endless flexible belt (2) extends over each of the rotating supported guide rollers (1) on the upper respectively lower frame sections. Preferably the inner partial heald-A (4) and the outer partial heald-B (5) of the belt (2) assembly each carry a thread eye (3) provided with a replaceable insert (3A) through each of which a warp thread of one or the other warp-thread sheets is drawn. The generation of an oppositely phased up-and-down reciprocating motion of the strands of the belt (2), permits the change-of-shed motion on the two warp-thread sheets to take place. For this change-of-shed motion, it is known that preferably the inner strand is fastened tightly with heald slide or shed cam lever (15), the shed cam lever (15) being slid vertically up and down on guide means.
Projecting from the shed cam lever (15) are guide rollers (1) which bear against a corresponding surface of shedding cam (7B) centrally and rotatable with the main shaft of the loom.
In order to form cross over weave pattern, it is necessary each time after a weft passage, to produce a preliminary tension on the warp threads by the displacement of the partial heads (4, 5) relatively against each other in the one or the other direction, which causes the warp threads, at the alternating motion thereof, to jump each time onto the other side of the warp thread, which consequently results in a cross-over weave/doup fabric (F) as shown in Figure 4.
Such a doup fabric (F), wherein cross-over warp ends (17) or doup threads and the ground threads (16), which are two neighbouring warp threads, are bound in a manner so that they are unable to slip, with several weft threads (18). Consequently, it is necessary that for the reciprocal arrangement of the doup thread, running lengthwise to the ground thread (16), two neighbouring warp

threads, for producing a portion of a doup fabric (F), displacement means engage on preferably the inner partial heald-A (4) of a partial heald pair (4, 5) after each shedding motion to bring about the instantaneous lateral relative counter displacement. Furthermore, the warp threads of one partial heald of the partial heald pair (4, 5) are in each case guided freely by thread guide means (4C) to bring about the shedding and, on the other partial heald, to bring about a side change, as is subsequently explained.
Accordingly, the partial healds (4, 5) support comb like guide means (4C) for the warp threads, the teeth or prongs (8) of the guide means (4C) each having a thread eye disposed on the free end thereof for the shedding guidance of a warp thread, and, defining between each tooth (8) and the next, thread guide slits for the freely guided warp threads for bring about the side change. In this connection, the development is such that the partial healds of the partial heald pair (4, 5) support comb-like guide means (4C) arranged opposite to each other, which are mounted on heald belt (2).
When, for example, there results an upward movement of the partial heald, and a downward movement of the partial heald due to the so-called Zero-position of the partial healds, at which position the warp threads are found in the weaving plane, the doup thread (17) lies first to the left of the ground thread (16). After a change of movement, by which one of the partial healds is in a downward position and the other partial heald is in an upward position, and after weft insertion has taken place, a displacement of the comb-like guide means (4C) of the inner partial heald-A (4) takes place to the right. Thereby, the warp threads receive a preliminary tensioning that causes the warp threads, at the next zero-passage, to change sides by jumping over, which illustrates the completed change of motion. Thereby, the doup thread (17) lies to the right of the ground thread (16). At the next movement, the comb-like guide means (4C) of the inner partial heald-A (4)

can regain its other (left) extreme position under the effect of the torsion spring (13), which again leads to a change of side of the warp threads, and so forth. The same result is achieved when the lateral displacement of the comb-like guide means (4C) on the inner partial heald-A (4) takes place using the lateral movement facilitator (4A) which has, for this purpose, a rocking lever (10) mounted on pivot position. Further, also for this purpose, a swivelling arm (11), which is also a part of the lateral movement facilitator (4A), having striking means, and being horizontal around an axle, extends below each inner partial heald-A (4), the striking means being swivelled alternately under each inner partial heald-A (4) upon each downward movement thereof, whereupon said comb-like guide means (4C) are tilted in each case from one side to the other and vice versa. Said swivelling of said rocking lever (10) takes place by way of swing control cams (6B) mounted on the plate of the loom.
The swing control cam (6B) pushes the swing control cam roller (6A) against the torsion spring (13) mounted with swivel bush (12) resulting in the swinging motion of swivel arm (11). The swivel arm (11) has striker arm, which imparts the lateral displacement to heald comb through rocking lever (10). As the swivel bush (12) undergoes tremendous strain for cycle of motion, it has higher wear tendency. To overcome this problem as per present invention swivel bush (12) was developed from wear resistance material preferably metallic alloy. The conventional looms use a rubber bush type element for giving swing motion to comb bar. This rubber element is prone to ageing effect and atmospheric effect causing the deterioration in the part, leading to frequent maintenance/replacement and limiting the high speed operation. The metallic swivel bush (12) introduced in this invention has a spring base system (13) for shock/impact resistance. It has been found that this has led to reduction in maintenance/replacement time and expenditure.

From the above described device and method, the developed inventive circular loom can produce doup tubular fabric of consistent quality at about 15 to 40% higher production rate compared to conventional method. It was also found that with the usage of replaceable ceramic insert (3A) and /or metallic low wear swivel bush (12) of the invention the service life of components and inventive circular loom have increased by 10 to 18 times over conventional parts and circular loom.
It should be noted that there are four drives that control operations of some of the key parts of the circular loom fitted with the partial heald assembly. These are:
A centralised main drive (not shown in figures) for both cams (6B and 7B)
A take-up drive (not shown in figures) for fabric haul-off
A warp let off drive (not shown in figures)
A fabric winder drive (not shown in figures)
The invention also discloses a method of manufacturing a doup fabric (F) using a circular loom fitted with the partial heald assembly. It comprises the steps of providing a loom fitted with the partial heald assembly as described here. A method for manufacturing a doup weave tubular fabric (F) in a circular loom wherein both ground warp (16) and doup warp ends (17) are subjected to a positive shedding motion, further the doup warp end (17) lateral displacement on one side of said ground warp (16) is achieved by a swing control cam (6B), and at a next shedding, said doup warp end (17) is shifted on the opposite side of said ground warp end (16) to form a shed after said doup warp (17) passes beneath said ground warp end (16), and the shedding motion of said doup warp ends (1) is repeated. As a result of this method, doup fabric (F) is formed where one warp thread jumps onto the other side of the other warp thread caused by the preliminary tension developed in the warp threads produced by the pair of partial healds (4, 5). As a step of this method, the pair of partial heals (4, 5) engages with each other in a comb-like arrangement of guide means (4C) provide on each of the partial healds (4, 5), wherein the guide means (4C) have a thread eye (3) at their

free ends through which threads pass for shedding and also thread guide slits between the consecutive guides which are used for bringing about the side change. As an inventive aspect of the method, the eye (3) is provided with a ceramic insert (3A) to reduce friction.
While the above description contains much specificity, these should not be construed as limitation in the scope of the invention, but rather as an exemplification of the preferred embodiments thereof. It must be realized that modifications and variations are possible based on the disclosure given above without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.

We claim:
1. A circular loom for manufacturing doup fabric (F) provided with a pularity of heald assemblies, characterized in that said assembly comprises a pair of partial healds, namely partial heald-A (4) and partial heald-B (5) of which at least one partial heald is engaged after each shedding motion, a shedding cam assembly (7) and a swing control cam assembly (6), said shedding cam assembly consisting of a shedding cam roller (7A) and a shedding cam (7B), said swing control assembly consisting of a swing control cam roller (6A) and a swing control cam (6B), said swing control cam (6B) pushing the swing control cam roller (6A) against a torsion spring (13) mounted with a swivel bush (12) leading to swinging motion of a swivel arm (11) that extends below each inner partial heald-A (4), said partial heald-A (4) consisting of an vertical movement facilitator (4B) and an in-plane lateral movement facilitator (4A) that facilitates rotation around a pivot (9), wherein said two partial healds (4, 5) are formed from slit belt strands of flexible material, whereby the partial healds are connected using a belt (2) in a continuous belt form, and wherein said pair of partial heads engage with each other in a comb-like arrangement of guide means (4C) provided on each of the partial healds (4, 5), said guide means (4C) having a thread eye (3), wherein said at least one of the thread eye (3) is provided with a replaceable insert (3A) and that said swivel bush (12) is made from wear resistance material.
2. The circular loom as claimed in claim 1, wherein said insert (3A) is made from ceramic with low friction surface.
3. The circular loom as claimed in claim 1, wherein said insert (3A) has low friction surface coating or lamination of wear resistant material.
4. The circular loom as claimed in claims 1 to 3, wherein the centralised main drive for both cams (6B and 7B), the take-up drive for fabric (F) haul-off, the warp let off drive, and the fabric winder drive are operated independently.
5. The circular loom as claimed in claims 1 to 4, wherein the swivel bush (12) is made from metallic alloy with wear resistance properties.

6. The circular loom as claimed in claims 1 to 5, wherein the swivel bush (12) has wear resistance coating.
7. The circular loom as claimed in claims 1 to 6, wherein said in-plane lateral movement facilitator (4A) is made from plastic material.
8. The circular loom as claimed in claims 1 to 7, wherein said vertical movement facilitator (4B) is made from jerk-resistant or vibration-resistant materials such as metals or plastic or their combination.
9. The circular loom as claimed in claims 1 to 8, wherein said swivel bush (12) has a torsion spring (13).
10. A method for manufacturing a doup weave tubular fabric (F) in a circular loom characterized in that said method comprises the steps of:
subjecting both ground warp (16) and doup warp (17) ends to a positive
shedding motion using a pair of partial healds (4, 5),
achieving the lateral displacement of the doup warp end (17) on one
side of said ground warp (16) by a swing control cam (6B),
shifting said doup warp end (17) on the opposite side of said ground
warp end (16) at a next shedding to form a shed after said doup warp
(17) passes beneath said ground warp end (16), and
repeating the shedding motion of said doup warp ends (17).
11. The method as claimed in claim 10, wherein the pair of partial heads (4, 5)
that are operated using the shedding and lateral displacement engages with
each other in a comb-like arrangement of guide means (4C) provide on each
of the partial healds, wherein the guide means (4C) have a thread eye (3) at
their free ends through which threads pass for shedding and also thread guide
slits between the consecutive guides which are used for bringing about the
side change, and wherein said eye (3) is provided with a ceramic insert (3 A).