FIELD OF THE INVENTION

The present invention relates to an improved device for controlling the air current on a textile spinning preparatory machine. This invention is particularly related with controlling the air currents using a hinged air guide means, called doffer tongue. It is fixed in the under-cover of the doffer of a textile carding machinery.

BACKGROUND OF THE INVENTION

Carding is the heart of textile yarn spinning both with respect to quality and productivity. In addition to the primary functions of removing the trash, neps and non-useful short fibers, the Card converts the physical form of the textile material from that of a wide thick feed sheet to that of a thin rope, called Sliver. The linear density of the feed sheet is reduced from about 300-800 grams/meter to about 3-8 grams/meter of delivery sliver. The rollers of various diameters from about 100 mm to 1250 mm and of different surface characteristics of plain to toothed wire covered run at various speeds and in very close proximity with each other. In many places it is as close as a fraction of a millimetre. The rate of sliver delivery varies from about 40 to 400 meters per minute.

The above details indicate how delicate it is to run the machine and handle a thin sheet of individualized fibers called a 'web'. The web is finally condensed into a sliver.

The revolving rollers at different speeds and directions create many air currents. These have to be handled, controlled and regulated to get the most useful effects and at the same time to avoid any adverse effect. The air currents on the one hand help in transfer of fibers from one roller to the other, in separation of materials of different types and masses, transportation of material etc. On the other hand, these air currents can cause air turbulences, disturb material transportation and transfer, cause dust pollution, cause material chocking and consequential physical damages to material and machinery.

In the context of the above, one of the most important functions highly influenced by air currents is the transfer of fibers from Cylinder to Doffer. These fairly big rollers are rotated in the opposite direction; that is their clothed surfaces move in the same direction at their point of convergence with their teeth in opposite direction. The ratio of surface speeds of Doffer to Cylinder, called the Draft, ranges from about 1/100 to 1/10. It is known as a Condensing Draft.

The process of fiber transfer from Cylinder surface to Doffer surface involves transferring of some fibers at a given time and at the same time retaining and returning of a larger percentage of fibers back along with the Cylinder. The aforesaid exercise of transfer of fibers is influenced and facilitated by factors like the clothing of cylinder and doffer, their surface speeds, the gauge or gap between these surfaces, centrifugal forces and the air current in addition to the physical quality parameters of the fibers. Therefore the fiber transfer at any given point of time is not completed in one full revolution of the Cylinder.

This whole exercise of fiber transfer occurs over a very critical curved distance of about 100 to 200 mm on the cylinder surface from the point of doffer and cylinder convergence to the top edge of the cylinder under-cover.

As per the known art in this area and as per various manufacturers, provision is available to bridge or expand this gap either by raising and lowering or by changing the plates of different sizes on the cylinder under cover. Also the front top edge of the cylinder under cover can be radially adjusted to vary its distance from the cylinder surface. However these provisions are not adequate to avoid fiber liberation from the main stream particularly for wider ranges of speeds, drafts, linear density and fiber materials. These liberated fibers accumulate over various machine components in this area more particularly on the front top edge of the Cylinder under cover and its tongue. This uncontrolled accumulation of fibers causes hindrance to the smooth passage and transfer of fibers leading to quality problems and damages to machine components. The present invention would provide an improved device for a carding machine that would overcome all disadvantages present in the existing art.

OBJECTS OF THE INVENTION

By controlling the air current in the fiber transfer zone between Card Cylinder and Doffer, the objectives are:

To eliminate the fiber accumulation below the fiber transfer zone of Cylinder and Doffer; particularly fiber accumulation over the tongue at the front top edge of the cylinder under cover is eliminated. This thereby prevents any damage to the machine parts in and around this zone.

Another object of the present invention is to provide an improved fiber transfer thereby improving the uniformity in linear density of the sliver.

Yet another object of the present invention is to avoid the patches in the web particularly at the time of doffer speed changes during piecing, slow speed and normal speed of production.

SUMMARY OF THE INVENTION

The Cylinder and Doffer are located within a very close proximity of a fraction of a millimetre. The gap between this point of convergence of Cylinder and Doffer surfaces to the top edge of the cylinder under cover is very crucial. In addition to the available provisions this research provides further means for controls. The invention of splitting the air current in an adjustable proportion using an under cover deflector in the space between the top edge of the cylinder under cover and the converging point of cylinder & doffer surfaces has given substantially better control over the fiber transfer and achieved desired objectives. This deflector means in the form of a tongue is fixed on the Doffer under cover which is capable of being adjusted with respect to its height, radial distance from doffer surface and splitting the air gap in required proportion between the top edges of cylinder under cover and the converging point of cylinder and doffer surfaces.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Figure-1: of the drawings illustrates the overall view and Material passage of a Carding machine.

Figure-2 of the drawings shows the existing working arrangement of the cylinder and doffer zone.

Figure-3 of the drawing illustrates the modified and improved arrangement of the cylinder and doffer zone according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Figure-1 shows the passage of textile material (fibers) through various components of a Carding machine. The material is fed by the Feed roller (1) in the form of a thick sheet. This is opened into very small tufts by the revolving Licker-in (2) and passes over the stationary licker-in under casing (3) and other components. The material is transferred to the cylinder (4) surface at the converging point of their surfaces. The material is carried forward by cylinder (4) and subjected to pre-carding or combing action by stationary clothed surfaces called C-Cleaners (5).

The material is carried forward further by cylinder surface and subjected to the Carding action over the clothed surfaces of a set of slow moving flats (6) followed by further opening action over the front C-Cleaners (7). Finally the cylinder (4) surface carries forward the material through the converging point (A) (Ref. Fig.-2) of cylinder and doffer surfaces. As the cylinder surface carrying the fibers emerges from this point (A), the surface remains open for a short distance. Transfer of a small proportion of fibers from the cylinder (4) to doffer (8) surface takes place over this short distance. The remaining fibers are carried forward by the cylinder (4) surface which is covered by the cylinder under-cover (9) till this surface converges with the licker-in (3) surface. Here a fresh set of fibers are added over the cylinder surface and the Carding cycle repeats and further separation of fibers onto doffer (8) takes place. The fibers deposited over doffer (8) are stripped in the form of a web and condensed into a sliver by the help of condenser (12). The whole operation of feeding, opening, carding, fiber transfer and sliver formation is continuous.

Figure-2 shows cylinder (4) and doffer (8) surfaces below their point of convergence (A) according to the existing arrangement. As per the known art and available machine designs, an air deflector called tongue (CT) fixed at the front upper end of the cylinder under-cover (9) controls the air current. The edge (X) of this tongue (CT) is at a distance AX from (A) and can be adjusted either by raising or lowering the tongue or changing the tongue of another length. The doffer surface is either covered or left open.

Figure-3 of the drawings illustrates the modified and improved arrangement of the cylinder and doffer zone according to the present invention. The Cylinder (4) and Doffer (8) surfaces converge at the point (A). The front upper edge of the tongue (CT) fixed on Cylinder under-cover (9) is represented by point (X). The point (Z) represents the upper edge of the deflector means or tongue (DT) fixed on the Doffer under-cover (10). AX, AZ and ZX are the distances between the corresponding points A, X and Z.

The tongue (CT) is hinged on the Cylinder under-cover (9). The distance AX can be varied using the tongue plate (CT) of different dimensions. Also its proximity with the cylinder (4) surface can be adjusted by swinging its free end. This space and the distance AX are critical, affecting the rate of air expulsion and the air currents. This is generally set based on the linear density of sliver delivered, Length and Fineness of fibers and the specification of clothing on cylinder (4) and doffer (8).

In the known art, the air current between A and X is not split using any deflectors. But the present invention however has successfully permitted the splitting of the air current in the required proportion to pass through the cylinder and doffer under-covers by using a deflector means (DT) hinged on the Doffer under¬cover (10). The relative height of this can alter the ratio of division of the distance AX into AZ and ZX. By swinging its free end, the space 'a' and 'b' between it and Cylinder (4) and Doffer (8) surfaces respectively can be adjusted. This versatile controlling device therefore helps the transfer of fibers from cylinder to doffer and also prevents accumulation of any liberated fibers particularly on the top edges (X) and (Z) of Cylinder tongue (CT) and Doffer Tongue (DT) respectively, during any time of machine running whether normal running, piecing or running out of material during any batch change.

We Claim:

1. An improved arrangement for controlling air current in a textile spinning machine, the arrangement comprising:

a carding cylinder having a cylinder surface carrying a cylinder clothing thereon;

a licker-in for feeding fibers to the carding cylinder; and

a doffer cooperating with the carding cylinder for transferring fiber material from the carding cylinder to the doffer, characterized in that the doffer includes at least one under cover deflector.

2. The arrangement of claim 1, wherein the deflector is in the form of a tongue called doffer tongue (DT) which is fixed on the doffer under cover, and wherein the tongue is capable of being adjusted with respect to its height, radial distance from doffer surface and splitting air gap in required proportion between the top edge of cylinder under cover and the converging point of cylinder and doffer surfaces.

3. The arrangement of claim 1, wherein the carding cylinder includes at least one deflector which is hinged on the cylinder under cover, wherein the deflector is in the form of a tongue called cylinder tongue (CT).

4. The arrangement claimed in any of the preceding claims 1 to 3, wherein the doffer tongue (DT) and the cylinder tongue (CT) are placed such that to split air in the required proportion to pass through the cylinder and doffer under cover.

5. The arrangement claimed in any of the preceding claims 1 to 4, wherein the distance between the air deflectors (CT and DT) hinged to the cylinder and doffer respectively can be varied by the free end of the deflectors.

6. The arrangement claimed in any of the preceding claims 1 to 5, wherein with the presence of air deflectors (CT and DT) in the textile spinning machine helps in preventing accumulation of any liberated fibers on the top edges of air deflectors thereby preventing damage to the machine parts.