FIELD OF THE INVENTION

The present invention generally relates to the field of textile industry. Particularly, the present invention relates to combing machine of a textile spinning machinery. More particularly, the present invention relates to a nipper frame in the lap nipping mechanism of a combing machine.

BACKGROUND AND PRIOR ART

Generally, a comber comprises a combing cylinder, a top comb, a pair of detaching rollers, and a nipper apparatus. The nipper apparatus rocks back and forth while nipping sheet-like fibers, so-called "lap", supplied thereto. The combing cylinder has a series of needles embedded on its peripheral surface. As the nipper apparatus moves backward, the needles comb the forward end of the lap. This action is called "combing". This combing action removes short fibers from the lap, producing a thin sheet-like fiber product, so-called "fleece".

In general, the nipper apparatus comprises a nipper frame, a bottom nipper fixed on the nipper frame at its front end, and a top nipper to nip the lap in cooperation with the bottom nipper. The top nipper nips the lap at the tip of the bottom nipper. The nipper frame can rock between a backmost position where the tip of the bottom nipper is proximate to the cylinder needles and a foremost position where the tip is proximate to the detaching rollers.

In the known art, the nipper frame is driven by a nipper shaft located below the frame, and is supported in a rock able manner by a four-bar link mechanism with the nipper shaft. The nipper shaft is mounted on the machine frame and is oscillated by a slider crank mechanism. The swinging motion of the nipper shaft converted as rocking motion of the bottom nipper through the four bar link mechanism. Said four bar link mechanism consist a crank arm and its one end is pivotally connected with nipper shaft and other end is being connected with the back end of bottom nipper. The front end of bottom nipper is connected with a rocker arm. The rocker arm is pivotally mounted on the circular comb shaft.

As the nipper frame rocks, the tip of the bottom nipper moves along an upward projecting arc, which is part of a circle encompassing the combing cylinder circle. In a total path along which the tip of the bottom nipper together with the nipper Frame rocks, there exists a point where the bottom nipper tip nips a lap in cooperation with the top nipper and releases the lap. The section in which the tip of the bottom nipper approaches the cylinder circle results in combing. When the tip of the bottom nipper reaches the foremost position in the rocking stroke, the tip is located below a position where a pair of upper and lower detaching rollers nip a succeeding fleece.

This racial movement and the clearance between nip and combing surface decides the level of combing and the nipper movement decides the nipping speed. In the aforementioned combing technology, it is not possible to reduce the clearance than a certain extent. Because, it would lead to hindrance of combing cylinder with bottom nipper. In addition, the rocking stroke of the nipper frame generates more vibration during high-speed machine operation. To reduce such abrasion, the to and fro motion distance of nipper frame (nipper movement) has to be reduced. Reducing the nipper movement is also not possible in the existing combing technology which is disadvantageous.

There has thus been a persistent need to develop a nipping mechanism that would increase nipping speed of the combing machine with out compromising the out put quality. The present invention would provide an improved combing machine that would overcome all disadvantages present in the nipping mechanism of the existing combing machines.

SUMMARY OF THE INVENTION

In accordance with the basic aspect of the present invention, said nipper frame comprising a top nipper and bottom nipper and is driven by nipper shaft through four-bar linkage mechanism, said four-bar linkage mechanism comprising a crank arm, one end of which is pivotally mounted on the nipper shaft, and other end is connected with back end of a bottom nipper arm which connects bottom nipper and crank arm; a rocker arm is connected to the front end of said bottom nipper; wherein the rocker arm centre is hinged at a predetermined distance from circular comb shaft centre.

In accordance with the another aspect of the present invention, the offset distance between centre point of circular comb shaft and the centre hinge point of rocker arm is preferably in the range of 0.5mm to 10 mm.

In accordance with the still another aspect of the present invention, said crank arm is being fixed in the machine frame in the region of second quadrant (angle of 90° to 180° in polar graph) with respect to ground line of circular comb shaft centre.

The above mentioned nipper frame overcomes the disadvantages present in the conventional nipper frame and nipping mechanism and by this, improved combing arc and minimum clearance can be achieved.

OBJECT OF THE INVENTION

It is thus the basic object of the present invention to provide a nipping mechanism which avoids aforementioned disadvantages of conventional nipping mechanism in the existing combing machines.

Another object of the present invention is to provide a textile combing machine with improved nipping mechanism that will minimize the clearance between combing surface and nipping point compared to the existing combing machines.

Still another object of the present invention is to provide a textile combing machine with improved nipping mechanism that will minimize the moving distance of nipper frame and improves the nipping speed compared to the existing combing machines.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Example embodiments are illustrated by way of example and not limitation in the figures of the accompanying figures, in which like references indicate similar elements and in which:

Fig -1 and Fig - 1a illustrates a schematic view of circular comb and nipping mechanism of the existing combing machines.

Fig - 2 illustrates a schematic view of circular comb and nipper frame according to the present invention.

Fig - 3 illustrates a schematic view of another embodiment of nipper frame according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.

Fig - 1 and Fig - 1a of the drawings illustrates the circular comb and nipping mechanism of the existing combing machines. The circular comb (1) consist a base cylinder (2) and a combing segment (3) which is being mounted on a shaft (4) and the shaft (4) is being driven by a driving means such as motor (not shown). A nipper frame is provided over the circular comb (1). Said nipper frame consist a bottom nipper (5), top nipper (6) and a feed roller (7). The bottom nipper (5) rocks to and fro and feed roller (7) feeds the lap sheet (8) and top nipper (6) open and close to clamp the lap sheet during combing. The nip portion (9) formed by the top and bottom nipper holds the lap sheet firmly to facilitate combing action. The bottom nipper (5) is oscillated by an oscillating nipper shaft (10).

Said oscillating nipper shaft (10) is mounted on the machine frame and oscillated by means of a slider crank mechanism. The swinging motion of the nipper shaft (10) converted as rocking motion of bottom nipper (5) through a four bar link mechanism.

Said four bar link mechanism consists a crank arm (11) and its one end is pivotally connected with nipper shaft (10) and other end is being connected with the back end of bottom nipper arm (12). The front end of bottom nipper arm (12) is connected with a rocker arm (13). The rocker arm (13) is pivotally mounted on the circular comb shaft (4).

The fiber material combed by the combing segment (3) is collected by the pair of detaching rollers (14).

Fig - 2 illustrates the circular comb and nipper frame according to the present invention. According to the embodiment of the invention, hinge point (A) of rocker arm (13) which is mounted on the circular comb shaft (4) in the existing machines is shifted to the hinge point (E) located on the machine frame. Said hinge point (E) is located in an offset manner from the circular comb shaft hinge point (A) at a predetermined distance (H). Said offset distance (H) is preferably in the range of 0.5 mm to 10 mm.

Fig - 3 illustrates another embodiment of nipper frame according to the present invention. Said rocker arm (13) is being fixed in the machine frame in the region of second quadrant (X) ie. an angle of 90° to 180° in polar graph with respect to ground line of circular comb shaft centre.

The invention allows the following advantages to be obtained. The moving distance of bottom nipper is minimized and collision between bottom nipper and combing cylinder can be avoided. Advantageously, minimum clearance between nip portion and combing segment can be achieved and said clearance can be maintained uniform while combing.

By maintaining desired clearance between nipper and combing segment, higher lap weight with desired quality level can be achieved and the nipping speed and feed weight of the comber can also be increased. Advantageously, over all productivity can be improved.

While the invention has been described above by way of embodiment, the invention is not limited to such embodiment. Various modification, equivalent substitution or improvement may be made to the invention without departing from spirit and scope of the invention as described.

We claim:

1. Nipping mechanism for a combing machine having a nipper frame comprising a top nipper (6) and bottom nipper (5) which is driven by a nipper shaft (10) through a four bar linkage mechanism; said four bar linkage mechanism comprising a crank arm (11), one end of which is pivotally mounted on the nipper shaft and other end is connected with back end of a bottom nipper arm (12) which connects bottom nipper and crank arm; a rocker arm (13) is connected to the front end of said bottom nipper; wherein said rocker arm centre (E) is hinged at a predetermined distance (H) from the circular comb shaft centre (A).

2. Nipping mechanism for a combing machine as claimed in claim 1, wherein the distance between centre point (A) of comb shaft (4) and hinge point (E) of rocker arm (13) is preferably in range of 0.5 to 10 mm.

3. Nipping mechanism for a combing machine as claimed in claim 1, wherein said rocker arm (13) is mounted in the region of second quadrant (X) with respect to ground line of comb shaft centre.

4. Nipping mechanism for a combing machine as claimed in claim 3, wherein said second quadrant (X) is preferably in range of 90° to 180° in polar graph.

5. Nipping mechanism for a combing machine substantially as herein described with reference to accompanying drawings.