DESC:FIELD OF THE INVENTION
The present invention relates to a lap forming machine and method in textile spinning machines. Particularly, this invention relates to textile lap winding machines from which the lap rolls are being produced for feeding the combing machines. More particularly the present invention deals with the machine and method of forming the lap rolls with uniform density as well as great evenness and uniformity.

BACKGROUND OF THE INVENTION
In the formation of a fibrous lap, it is well known that the maintenance of uniformity of laps produced by lap forming machines has always been a problem. The uniformity in the density of the lap is mostly achieved by controlling the density of the fibres upstream of and immediately prior to the compacting of the fibres into a lap. Automatic control devices have been developed to measure the lap and adjust the lap feeding means if the lap does not satisfy a set standard. Various mechanisms have been proposed heretofore for controlling lap density, but have had the drawback that corrections in lap density were made by measuring a section of the lap which was already formed and, in response thereto, rectifying the amount of fibres being fed so that a subsequent section of the lap might be compensatively heavier or lighter than the measured section.

In all said lap forming machines, there is a lap weight variation observed between the starting layer and final layer of every lap. This linear density of the lap is varied based on input sliver uniformity condition and its winding process quality. In initial layers, the lap roll diameter is compact and later it becomes bulky as the number of layers increased or when the lap diameter gets build. This non uniform linear density of lap causes the drawbacks such as web cuts, increased table stops and inconsistency in quality etc., in the subsequent combing process.

OBJECTS OF THE INVENTION
It is an object of this invention to provide an improved machine and method for forming the lap rolls with uniform density, surface evenness and uniformity.

It is another object of this invention to provide an improved machine and method for forming the lap rolls with superior unwinding property which provides a quality resultant product in subsequent combing process.

Yet another object of the present invention is to effectively control the web cuts and table stops in the subsequent processes.

SUMMARY OF THE INVENTION
The lap forming method according to an aspect of the present invention comprises a step by step measurement of the wound lap weight deviation between start and end of wound lap packages offline. This is achieved by completely unravelling a full lap roll, and measuring the weight per unit length. For each diameter of said lap roll, the respective wound lap weight has been measured per unit length. And thus an algorithm can be formed to continuously control and maintain the linear weight per unit length of lap sheet by applying a draft compensation during lap winding. The draft compensation is provided between at least a pair of front drafting roller and rear drafting rollers for changing the draft continuously. Since the drafting rollers are servo/frequency controlled driven, said continuous control over the linear weight density of the lap roll can be maintained effectively.

BRIEF DESCRIPTION OF THE DRAWINGS
Figure-1 shows the illustration of the lap forming machine according to the present invention.

Figure-2 shows the drive arrangement of the lap forming machine according to the present invention wherein the driving elements of drafting rollers and lap rollers are shown.

Figures-3 and 4 represents the graphical illustration between the prior art and invention wherein the comparative data pertains the relation between lap diameter/length and other variation parameters.

DETAILED DESCRIPTION OF THE INVENTION
The lap forming machine (1) according to the present invention as illustrated in Figure 1 comprises a lap winding mechanism (2) to form a fibre lap roll (3); a first set of drafting rollers (4,5) and second set of drafting rollers (6,7) to draft the fibre sheet; in that, the front drafting rollers (5) and (7) are driven separately whereas the middle and back drafting rollers set (4) and (6) are driven separately in a synchronised manner; therein a calender rollers (8) for compact pressing the fibre lap sheet before wound as lap roll (3). The first drive element (M1) and second drive element (M2) are provided for driving the whole machine wherein all of the functioning components are connected to the machine control unit. Said drive elements (M1 and M2) are servo/frequency controlled driven. And also the lap rollers (2) in the lap winding mechanism can be driven by separate servos/frequency controlled devices which can be synchronised to M1 and M2.

Figure-2 illustrates the drive arrangement of the lap forming machine according to the present invention wherein the driving elements of drafting rollers and lap rollers are shown. The first drive element (M1) drives the lap winding rollers (2), calender rollers (8), delivery rollers (11,12) and front drafting rollers (5,7) of each drafting units. The second drive element (M2) drives the remaining rollers (4,6) of each drafting units as well as sliver take up rollers (13,14). Since front drafting rollers (5,7) are driven by a separate driving element (M1) and the remaining (middle and rear) drafting rollers (4,6) are driven by another driving element, a well desired and controlled tension draft on the fibre sheet can be achieved.

From a completed fibre lap roll (3), the fibre sheet is being completely unravelled and deviation in weight per unit length is being measured offline manually for a pre defined set of laps to ascertain a definite trend of length vs weight. Said measurement is being done initially from a plurality of sample lap rolls in a batch, say 2 to 5 samples of lap rolls. From this measured value, an algorithm is being derived which can be stored and recalled to continuously control and maintain the linear weight density of lap sheet during lap winding process by draft compensation. The draft compensation is provided between at least a pair of front drafting roller (5,7) and rear drafting rollers (4,6) for changing the draft continuously. Since the drafting rollers (4,5,6,7) are servo/frequency controlled, said continuous control over the linear weight density of the lap roll can be maintained effectively by varying the draft. As a further embodiment of the invention (not shown in drawings), the said driving arrangement can be extended to lap forming machines that are using belt winding principle. Here the first drive element (9) drives the plurality of belt driving rollers instead of lap rollers shown in the present invention, whereas the second drive element drives the remaining rollers (4,6) of each drafting units as well as sliver take up rollers (13,14) as in present invention.

In general process of lap winding as per known art, the lap weight gets increased (during lap built) with increase in lap roll diameter as illustrated in Figure-3. Figure-4 illustrates the draft compensation with respect to increase in lap diameter/length as per the invention. Uniform linear density in lap roll is achieved by varying the draft (draft compensation) as well as delivery rollers speed, calender rollers speed and lap winding rollers speeds in a synchronous manner.

Because of continuous control over the linear weight density, the lap roll gets more evenness that offers superior unwinding property which provides quality resultant products in subsequent combing process and thus effectively controls the web cuts and table stops in the said subsequent processes. Therefore a better combing performance with increased productivity results in the spinning plant.

Various modifications to these embodiments are apparent to those skilled in the art from the description and drawings herein. The principles associated with the various embodiment defined herein may be applied to other embodiments. Therefore, the description is not intended to be limited to the embodiments shown along with the accompanying drawings but is to be provided broadest scope consistent with the principles and novel and inventive features describe/disclosed or suggested herein. Any modifications, equivalent substitutions, improvements etc. within the spirit and principle of the present invention shall all be included in the scope of protection of the present invention.

,CLAIMS:We Claim:
1. A lap forming machine comprising:
at least a pair of drafting rollers (4, 5, 6, 7) to draft the fibre sheet;
at least a pair of calender rollers (8) for compact pressing the lap sheet;
a lap winding mechanism (2) to form a fibre lap roll (3);
at least a separate drive element for driving the drafting rollers wherein
weight per unit length of the fibre sheet is measured for a set of predetermined wound laps; and
the draft is continuously changed such that weight per unit length of the lap which is being formed is uniform on the lap roll.

2. The lap forming machine as claimed in claim 1, wherein said measuring is finding the deviation of weight per unit length offline in the wound lap packages.

3. The lap forming machine as claimed in claim 2, wherein said drafting rollers and said separate drive elements continuously control and maintain weight per unit length of the lap sheet.

4. The lap forming machine as claimed in claim 1, wherein draft compensation is provided between at least a pair of front drafting rollers (5, 7) and rear drafting rollers (4, 6) for changing the draft continuously.

5. The lap forming machine as claimed in claim 1, wherein the front drafting rollers (5, 7) are driven by the first drive element (M1), the middle and back drafting rollers (4, 6) are driven in a synchronised manner by the second drive element (M2), said first drive element (M1) further drives calender rollers (8) and delivery rollers (11,12), said second drive element (M2) further drives sliver take-up rollers (13,14).

6. A lap forming method comprising the steps of:
measuring weight per unit length of a fibre sheet for a set of predetermined wound laps; and
changing the draft continuously such that weight per unit length of the lap which is being formed is uniform on the lap roll.

7. The lap forming method as claimed in claim 6, wherein the step of measuring weight per unit length of the fibre sheet is manually done offline on a plurality of sample rolls in a batch.

8. The lap forming method as claimed in claim 6, wherein said step of measuring determines deviation of weight per unit length in the wound lap packages.

9. The lap forming method as claimed in claim 8, wherein the weight per unit length of the lap sheet is continuously controlled and maintained.

10. The lap forming method as claimed in claim 6, wherein draft compensation is provided between at least a pair of front drafting rollers (5, 7) and rear drafting rollers (4, 6) for changing the draft continuously

Dated: 03/08/2015

(JAYANTA PAL)
IN/PA 172
REMFRY & SAGAR
ATTORNEY FOR THE APPLICANT [S]