FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003
COMPLETE SPECIFICATION (See Section 10 and Rule 13)
Title of invention:
An Idler Roller for a Jute Slip Draft Spinning Frame
Applicant
NRB Industrial Bearings Ltd, an Indian company, having its address at 2nd Floor Dhannur, 15 Sir P.M. Road, Fort, Mumbai – 400 001, Maharashtra, India.
Preamble to the description:
The following specification particularly describes the invention and the manner
in which it is to be performed.

FIELD OF THE INVENTION
[001] The invention relates to an idler roller for a jute slip draft spinning frame.
BACKGROUND OF THE INVENTION
[002] Jute yarn manufacturing process involves many stages wherein jute fibres are subjected to chemical and mechanical processing. Typically, jute fibres undergo the process of emulsification and softening to obtain softened jute fibres which are then subjected to carding. Carding of softened jute fibres splits the fibres longitudinally and break the fibres transversely to obtain clean and uniform fibrous strand called as slivers. The slivers from carding machine are then fed to drawing frame where the slivers are doubled, straightened, parallelized and fed to a spinning frame. Spinning frame processes the slivers – to reduce the number of fibres in the cross-section according to the count of the yarn, to impart twist to form the final yarn, and to wind the yarn on a bobbin maintaining proper yarn tension.
[003] Typically, a jute sliver spinning frame consists of a creel zone where jute slivers from drawing frame are placed in a manner to feed individual spindle of the spinning frame; a drafting zone where jute fibres are subjected to drafting thereby reducing the number of fibres in the cross-section as well as straightening and parallelising the fibres; and a twisting and winding zone where drafted fibre strand is twisted and then wound in the form of jute yarn on a bobbin.
[004] Drafting zone of all jute spinning frames has two sets of rollers – retaining rollers and drawing rollers. A sliver is retained in a desired position by a pair of

retaining rollers, in combination with breast plates, gill bars, carrier rollers, endless aprons or other intermediate devices, and drawn by a pair of drawing rollers at a desired speed. Due to high fibre length variation and to control movement of short floating fibres in the drafting zone, different mechanisms like apron draft system, slip draft system and grooved roller draft system are used between the retaining and drawing rollers.
[005] Figure 1 shows a typical arrangement of a jute slip draft spinning frame. As shown, a crimped jute sliver S is fed through a guide element 800 and passes between a pair of retaining rollers 500, 600, whereby number of fibres in the cross-section is reduced and fibres are further straightened, parallelised and smoothened. The sliver S is then passed and guided through a curved breast plate 700, mid draft roller 200 and idler roller 100. The breast plate 700 projects forward slightly from the line joining nips of two sets of rollers in order that it may play its proper part in control of short fibres movement. The mid draft roller 200 and idler roller 100 guide the sliver S between the drawing pressing rollers 300, 400 through which the sliver S undergoes further processing before a yarn is delivered for twisting and winding operation. Retaining rollers 500, 600 and drawing pressing rollers 300, 400 are provided with proper loading facilities to grip the fibres during processing. Similarly, idler roller 100 is pressed against the mid draft roller 200 and rotates reactively to the mid draft roller 200.
[006] An idler roller generally consists of a cylindrical housing having a bore and a plurality of teeth formed on an outer surface of the housing, a bush fixed inside the

bore and a shaft configured to be disposed inside the bore such that the bush forms a bearing surface for the shaft. One end of the shaft is configured to abut against an outer surface of the bore and other end of the shaft is configured to be mounted on an idler roller mounting shaft. Thus, in operation, when mid draft roller rotates, it engages with the teeth of the idler roller causing the idler roller to rotate about the shaft whereby the bush acts as a bearing surface for the shaft.
[007] Since bush acts as a bearing surface for the shaft, wear and tear of the bush is inevitable. Moreover, since bush is generally made of copper, which is soft, malleable and ductile, it is more prone to wear and tear. Further, the shaft is generally made of EN32 grade steel which has low tensile strength and therefore generally used for lightly stressed component. However, in operation, shaft is highly stressed when the idler roller is meshed with the mid draft roller. As a result, the shaft is also prone to wear and tear. In view of these, it is noticed that over a short period of operation, the idler roller starts wobbling leading to slippage of jute sliver passing between the mid draft and idler rollers. Due to slippage of jute sliver, it becomes imperative to shut down the operation of spinning frame until the problem is rectified. Consequently, efficiency of the jute slip draft spinning frame and that of the overall jute manufacturing machine is reduced. Further, since idler rollers wear out quickly, it is an expensive proposition to keep replacing worn out idler rollers with new idler rollers for maintain efficiency of the jute manufacturing machine.
[008] Thus, there is a need in the art for an idler roller for a jute slip draft spinning frame that can address at least the aforementioned problems.

SUMMARY OF THE INVENTION
[009] The present invention is directed to an idler roller for a jute slip draft spinning frame. The idler roller comprises a cylindrical housing, a needle roller bearing and a shaft. The cylindrical housing has a bore and the needle roller bearing fits inside the bore. The shaft is rotatably disposed inside the bore of the housing. The housing of the idler roller has an outer surface which is configured to be meshed with a mid-draft roller and to guide a jute sliver. The shaft disposed inside the bore is coupled with an idler roller mounting shaft such that needles of the needle roller bearing act as bearing surface for the shaft. When the outer surface of the idler roller is meshed with the mid-draft roller, the idler roller rotates about the shaft.
[010] In an embodiment of the invention, a portion of the shaft may be a load zone, which may be made with a hard metal and may be manufactured using grinding process or superfinishing process. The load zone may also act as a raceway for needles of the needle roller bearing. The load zone may also have a cross section that is larger than the rest of the shaft.
BRIEF DESCRIPTION OF THE DRAWINGS
[011] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.

Figure 1 shows a schematic representation of a typical slip draft spinning frame.
Figure 2 shows an exploded view of an idler roller according to an embodiment of the present invention.
Figure 3 shows an illustrative representation of the idler roller according to an embodiment of the present invention.
Figure 4 shows an idler roller according to an embodiment of the invention mounted on an idler roller mounting shaft.
DESCRIPTION OF THE INVENTION
[012] The invention relates to an idler roller for a jute slip draft spinning frame. [013] As shown in Figures 2 and 3, an idler roller 100 has a housing 110. Outer surface of the housing 110 has a plurality of protruding spaced apart teeth 112. Each tooth 112 of the housing 110 has a depression 114 in the middle. Further, inner surface of the housing 110 has a bore 116 with a concentric collar 118 such that the inner surface of the housing 110 resembles an “I” shape. Operationally, the teeth 112 mesh with a mid-draft roller 200 (as illustrated in Figure 1) and the depression 114 provides a pathway for a jute sliver.
[014] Further, as shown in figure 2, a needle roller bearing 120 is press fitted inside the bore 116 of the housing 110. The diameter of the needle roller bearing 120 is configured to be such that the needle roller bearing 120 can be inserted in the bore 116 of the housing 110 and fitted therein. The needle roller bearing 120 has a needle

cage assembly 126 which houses, retains, and guides the cylindrical rollers. i.e. the needles. Typically, the needle cage assembly 126 is housed between an outer ring 124 and a pair of retainers 122a, 122b provided at each circumferential end of the outer ring 124, whereby the needle cage assembly 126 and the outer ring 124 are held together in one piece by the pair of retainers 122a, 122b.
[015] Further, as shown in Figure 3, a shaft 130 is rotatably disposed inside the bore 116 of the housing 110. Referring to Figure 2, the shaft 130 has a first end 130a, a second end 130b, and a body 138 extending between the first end 130a and the second end 130b. Referring to Figures 2 and 3, ahead 132 provided at first end 130a of the shaft 130 rests on the collar 118 to hold the shaft 130 in place when the shaft 130 is placed inside the bore.
[016] In an embodiment of the invention, the body 138 has a load zone 134 provided adjacent to the head 132 and a threaded portion 136 provided at the second end 130b of the shaft 130. The shaft 130 is coupled with an idler roller mounting shaft 150 by screwing the threaded portion 136 on the idler roller mounting shaft 150 as shown in Figure 4. In this regard, in an embodiment of the invention, the head 132 has a flat groove to assist in the screwing of the threaded portion 136 of the shaft 130 onto the idler roller mounting shaft 150. Further, at least a portion of the body 138 is inserted in the bore 116 to abut against the needle roller bearing 120 fitted inside the bore 116 of the housing 110. In this regard, the load zone 134 abuts against the needle roller bearing 120 such that needles of the needle bearing roller bearing 120 act as

bearing surface for the shaft 130. Accordingly, the load zone 134 also acts as a raceway for the needles of the needle roller bearing 120.
[017] In an embodiment of the invention, the load zone 134 has a larger cross-section than rest of the shaft 130 so that only the load zone 134 of the shaft 130 abuts against the needle roller bearing 120 fitted in the bore 116 of the housing 110. In a further embodiment of the invention, the load zone 134 is made of a hard metal and is manufactured by using grinding process or superfinishing process. In an embodiment of the invention, the hard metal used to make the load zone is SAE52100 bearing steel.
[018] In operation, when the mid-draft roller 200 rotates, it engages with the teeth 112 of the idler roller 100 causing the idler roller 100 to rotate about the shaft 130. The shaft 130 rotates at a very high speed when slip draft spinning frame is in operation. At this time, needles of the needle roller bearing 120 reactively rotate upon the load zone 134 which acts as the raceway of the shaft 130. Since rotation of needles of the needle roller bearing 120 is parallel to the axis of the shaft 130, load generated by the shaft 130 is carried by the needles of the needle roller bearing 120. [019] Advantageously, the needle roller bearing 120provides a more robust bearing surface for the shaft thereby slowing down the wear and tear of the shaft 130. Further, since the shaft 130 is made of hard metal and is manufactured using grinding process or superfinishing process, this enables the shaft 130 to have precise tolerance. This further reduces the wear and tear of the shaft 130, thereby extending the life of the idler roller 100.

[020] The foregoing description of the invention has been set merely to illustrate the invention and is not intended to be limiting. Since the modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to the person skilled in the art, the invention should be construed to include everything within the scope of the disclosure.

We claim:
1. An idler roller (100) for a jute slip draft spinning frame comprising:
a cylindrical housing (110) having a bore (116), and an outer surface configured to be meshed with a mid-draft roller (200) and to guide a jute sliver (S); a needle roller bearing (120) fitted inside the bore (116); and
a shaft (130) disposed inside the bore (116) and coupled with an idler roller mounting shaft (150) such that needles of the needle roller bearing (120) act as bearing surface for the shaft(130) whereby when the outer surface of the idler roller (100) is meshed with the mid-draft roller (200), the idler roller (100) rotates about the shaft (130).
2. The idler roller (100) as claimed in claim 1, wherein a length of the shaft (130) has a load zone (134) to act as a raceway for the needles of the needle roller bearing (120).
3. The idler roller (100) as claimed in claim 2, wherein the raceway (134) has a larger cross-section than rest of the shaft (130).
4. The idler roller (100) as claimed in claim 2, wherein the load zone (134) is made of a hard metal manufactured by using grinding process or superfinishing process.