Field Of Invention:
The invention relates to a circular loom for producing woven tubular fabric. In particular the invention relates to a circular loom deploying a control lever operating in conjunction with the plate/cam mechanism to control the movement of the heald arrangement.
Background of invention:
In general, a circular looms has a mechanism in which inner and outer partial healds are arranged annularly around a main shaft of the loom. The partial healds, through which the tapes that make up the woven fabric pass, are moved up and down by means of control arm levers operated by a plate cam rotating with the main shaft of the loom.
A circular loom which includes a cam plate that is mounted centrally on a pin and around which it can rotate is known. The cam plate has with two cam control curves which correspond to different lengths of control levers, which are provided with follower rollers that run on the respective surfaces of the control curves to provide an ascending and continuous alternative movement to the warp lifting means.
However, the existing arrangement of the control lever having follower rollers has various drawbacks. First, the horizontal or radial arrangement of the follower rollers requires large operative space which puts a limit on the number of follower roller pairs for a given diameter, whereas for precision of operation of the loom, such limit would be undesirable. Further, the rollers' movement in radial direction with respect to the machine shaft, especially when carried out at a high frequency consumes a lot of energy. Further, due to the differences in the speed (as much as 15%) the control lever experiences high stresses in tangential direction. There is also a lot of noise due to high vibration.

Also known are circular looms wherein open warps are held with two pivoting levers, at the free end of which a loosely rotatable roller is mounted which rolls in the grooves provided in a cam. However, this arrangement is complex and allows low operative speeds at high energy consumption and high noise level. Also known are circular looms in which two coaxially arranged cams are provided, into which tangential pivot lever engage and where the levers are secured to the cams by means of springs - this in itself is a drawback as the springs have to be designed with precision to secure the rollers to the cam. This not only increases the wear, but also requires a higher energy consumption and limits the achievable speeds.
There is therefore a need to provide a circular loom that has a better plate/cam mechanism to control the movement of the heald arrangement - i.e. a plate/cam mechanism that reduces wear and operating noise and has lower energy consumption and allows working of the loom at greater speed than conventional mechanisms known to a person skilled in the art.
Objects of Invention:
One object of invention is to provide circular loom for producing woven tubular fabric which has a plate/cam mechanism to control the movement of the heald arrangement.
Another object of the invention is to provide a loom where tangential stresses experienced by the control lever are reduced.
A further object of the invention is to provide a loom that has a reduced level of operating noise.
Another object of the invention is to provide a loom that consumes reduced level of energy.

Summary Of Invention:
The invention concerns a circular loom for producing woven tubular fabric. It discloses a circular loom deploying a control lever operating in conjunction with the plate/cam mechanism to control the movement of the heald arrangement. Its advantages are that it reduces the noise level and the tangential stresses experienced by the control levers. In the present invention (shown in Figure 1) at least one control lever (C), which is positioned perpendicularly to the central shaft (12) is provided for the activation of the counter-current up-and-down alternating motion on the yarn guiding eyes (9) of each warp guide element (10/11). The control levers (C) have two integrally connected arms or levers - a power arm (17) and a drive arm (18). The control levers (C) are supported on a bearing block (20) and able to turn or rotate on a fixed fulcrum (16). At the far end of the drive arm (18), that is the end of the drive arm (18) away from the bearing block (20), the control lever (C) is in operative connection with a cam (13) provided on the cam plate (23). The power arm (17) is provided with a heald joint/drive (19) with the help of which the power arm is operatively connected to the belt (22) that supports inner partial heald (2A).
Brief Description Of Figures:
Figure 1 shows a schematic view of the invention
6. Woven tubular fabric
7. Bottom Support roller
8. Top support roller
9. Heald eyelet
10. Outer warp guide element
11. Inner warp guide element
12. Main drive shaft or central shaft
List Of Parts:
1. Partial schematic of
circular loom
5 2. Heald assembly; 2A - inner
partial heald; 2B - outer
atrial heald 35
3. Warp ends
4. Shuttle for weft end 3 5. Circular Reed

5. Control plate/cam
6. Bottom roller
7. Top roller
8. Pivot/fulcrum point
9. Power arm lever
10. Drive arm lever

10

19. Heald joint/drive
20. Bearing block
21. Fabric ring or circular ring
22. Belt
23. Cam plate
C. Control level

Detail description of Invention:
Figure 1 shows a schematic view of the circular loom of the invention fitted with a cam mechanism employed to effect the up and down movement of the healds (10/11). It shows central shaft of a circular loom on which a cam plate (23) is mounted. In one aspect of the invention, a cam mechanism or simply a cam (13) is fitted to the underside of the cam plate (23). The cam mechanism or the cam (13) is in the form of a curved plate. The figure also shows a circular reed (5) and the support rollers (7/8) upon partial healds (2A/2B) are supported. There are two partial healds - an inner partial heald (2A), and an outer partial heald (2B). Each partial heald (2A, 2B) comprise a corresponding warp end guide (11, 10) and the portion of the belt (22) which supports it. The support rollers (7/8) are arranged peripherally in circular configuration around the main shaft (12) of the loom (1). Further, the warp ends (3) that are used to form the woven fabric (6) are divided into two warp thread gatherings and are drawn off in a known manner by groups of warp thread spools, which are not illustrated. For the formation of the weaving shed, one of these thread gatherings is lifted up while the other is guided down from the level of the weaving plane through the so-called change of shed motion, so that a warp top shed and a warp lower shed result. In this so-called weaving or multiphase shed, at least one shuttle (4) with a weft yarn bobbin is passed through on a horizontal circular path. Due to the circular motion of the shuttle (4), the weft yarn (not shown) wound off from the weft yarn bobbin provided on the shuttle (4) is transferred onto the edge of a circular ring, so that this weft yarn can be woven, along with the warp ends (3), into the fabric (6). The tubular woven fabric can

In the present invention (shown in Figure 1) in which the sequential means comprise at least one control lever (C), provided perpendicularly to the central shaft (12), for the activation of the counter-current up-and-down alternating motion on the yarn guiding eyes (9) of each warp guide element (10/11). The control levers (C) have two integrally connected arms or levers - a power arm (17) and a drive arm (18). The control levers (C) are supported on a bearing block (20) and able to turn or rotate on a fixed fulcrum (16). At the far end of the drive arm (18), that is the end of the drive arm (18) away from the bearing block (20), the control lever (C) is in operative connection with a cam (13) provided on the cam plate (23). The power arm (17) is provided with a heald joint/drive (19) with the help of which the power arm is operatively connected to the belt (22) that supports inner partial heald (2A).
For performing the shed-forming operation, a plurality of pair of partial healds (2A, 2B) is arranged in a circle around the main shaft (12) of the loom (1) near the outer surface of the circular reed (5). As can be seen in Figure 1, each partial heald (2A and 2B) comprises, for example, warp end guide elements (10/11), being formed by belt (22) strands. For example, an endless belt (22) can, for this purpose, be guided over each of the rotatable supported guide pulleys (7/8) on the upper or lower part of the frame.
The inner strip and the outer strip (or the partial healds (2A, 2B)) of the heald assembly (2) have in each case yarn guiding eyelets (9), through each of which a warp thread (3) of one or the other of the warp thread gatherings is pulled. The making of a counter-current up-and-down alternating motion of the heddle belt strip then produces change-of-shed motion of both warp thread groups.
According to invention, for creating the counter-current up-and-down motion on the thread eye means for each partial heald, at least one control lever (C)

consisting of a power arm (17) and a drive arm (18), which is supported on a bearing block (20) and turns on a fixed fulcrum or a pivot point (16), and with the drive end of its drive arm (18), is in operative connection through a pair of cam rollers, namely a bottom roller (14) and a top roller (15), with a cam (13) on the main shaft (12). As it can be seen from Figure 1, these rollers roll on, respectively, lower and upper sides of said cam (13), i.e. the bottom roller (14) rolls on the lower side of the cam (13), and the upper roller rolls on the upper side of the cam (13). Further, the power arm/lever (17) is operatively connected to the belt (22) that supports the inner partial heald (2A) using a heald joint/drive (19), as is shown in in Figure 1.
As can be seen from Figure 1, the control levers (C) are arranged essentially perpendicularly to the main drive shaft (12) of said loom. It can be further seen from Figure 1 that bottom roller (14) and said top roller (15) are arranged with their respective axes of rotation being in horizontal plane. The rotational axis of the pivot (16) lies in a horizontal plane and is substantially tangential to the cam (13).
The operative connection between the end of the drive arm (18) and the cam (13) is created by a form-closed forced control. As shown in Figure 1, the drive arm (18) is arranged as a linear lever, comprising at least one roller (7 or 8), which rolls on the cam (13), at the end of the drive arm (18) that is in operative connection with the cam (13).
In one aspect of the invention, said power arm (17) is longer than said drive arm (18).
The heald joint/drive with which the power arm (17) is connected to the inner partial heald (11) may be a flexible or hinge connection.

It has been found that the mechanism disclosed herein results in a circular loom that is exceptionally quiet and precise in operation, and robust, and simple in construction.
It was found that the circular loom of the invention operates at a noise level reduced by 5-10% and at energy consumption level reduced by 2-5% compared to the conventional looms. Further, the productivity of the circular loom of the invention was also found to be enhanced at normal operating speed. Further, given that the control levers (C) are positioned radially or perpendicularly to the central shaft (12), the tangential stresses on it are virtually eliminated.
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 to make tubular woven fabric, said circular loom (1)
comprising:
- a circular reed (5), and the support rollers (7/8) upon which a belt (22) carrying warp guide elements (10/11) is supported;
- said support rollers (7/8) being arranged peripherally in circular configuration around the main central shaft (12) of the loom (1);
- a cam plate (23) mounted on a central shaft (12);
- at least one control lever (C) for the activation of the counter-current up-and-down alternating motion on the yarn guiding eyes (9) of each warp guide element (10/11);
characterised in that a cam (13) is provided on the underside of said cam plate (23), and said control level (C) constitutes two integrally connected arms or levers - a power arm (17) and a drive arm (18), wherein said control levers (C) is supported on a bearing block (20) and capable of turning around or rotate on a fixed fulcrum (16) and wherein at the far end of the drive arm (18), the control lever (C) is in operative connection with said cam (13) provided on the cam plate (23), and the power arm (17) is provided with a heald joint/drive (19) with the help of which the power arm is operatively connected to the belt (22) that supports inner partial heald (2A).
2. The circular loom as claimed in claim 1, wherein the operative connection of said far end of said drive arm (18) is in the form of a pair of rollers, namely a bottom roller (14) and a top roller (15) that roll on respectively lower and upper sides of said cam (13).
3. The circular loom as claimed in claim 1, wherein said control levers (C) are arranged essentially perpendicularly to the main drive shaft (12) of said loom.
4. The circular loom as claimed in claims 1 and 2, wherein said bottom roller (14) and said top roller (15) are arranged with their respective axes of rotation being in horizontal plane.

5. The circular loom as claimed in claims 1 to 4, wherein the rotational axis of the pivot (16) lies in a horizontal plane and is substantially tangential to the cam (13).
6. The circular loom as claimed in claims 1 to 5, wherein said power arm (17) is longer than said drive arm (18).