FIELD OF THE INVENTION

The present invention relates to an improved apparatus and method of controlling ring spinning machine especially the driving system of the ring spinning machine which controls the plurality of components such as spindles, drafting systems, ring rail, auto doffing systems, etc.,

More particularly this invention concerns to control the twists imparted in the yarn according to the requirement , by means of controlling the rotational speed of spindles and drafting rollers.

BACKGROUND OF THE INVENTION

Generally in the known art of yarn spinning process, the driving system of a ring spinning system comprises a common or individual motor which drives the plurality of machine components such as spindles, drafting systems, ring rail, auto doffing systems, etc.,

The spindles are driven by a motor connected with a common drive shaft extends along the entire length of the machine. Over the common driveshaft, plurality of pulleys are fixed, each has a driving flat belt engaging in the wharves on the spindles.

In general, the drafting device used in a spinning machine such as a ring spinning machine or a roving machine is provided with 3 or 4 nos of drafting rollers which comprises of front bottom, middle bottom and back bottom rollers. These bottom rollers of the drafting units are interconnected at one end by a gear train, which is driven by lay gear of the common spindle driving shaft or an individual motor. These rollers extend continuously along the machine from one end to the other end wherein each of the drafting units are supported in bearings at spaced intervals. The speed ratio between these drafting rollers is maintained in such way to obtain the desired yarn fineness/count.

In the ring spinning process, there is a predetermined speed relationship between the spindles and the delivery of the material from the front drafting rollers. The speed ratio of the spindles and the drafting rollers decides the amount of twist imparted in the yarn.

In the spinning of a textile yarn, it is usual to establish a pre-selected relationship between the count of the yarn and twist in the yarn with a guideline of TWIST = K (CONSTANT) X SQ.ROOT OF COUNT
In broad sense the count is the relationship between length and weight. The twist (whether S or Z twist) is the relationship between length and number of turns per unit length (Twist) of yarn. These values of count and twist do not have straight relationship with each other, however any degree of variation in one, calls for a different degree of variation in the other. At present, the above said formula is normally used to calculate the twist value, and the result value is set as input to the machine.

Presently ring spinning machines are provided with individual driving motors for each drafting rollers or a driving motor for common drafting assembly/arrangement in respect of all rollers and spindles. Said drafting rollers and spindles are controlled by means of a controller featured with a suitable PLC (Programmable logic controller) or microprocessor. This PLC enables the drafting rollers and spindles to synchronize with each other to achieve the desired twist and count consistently throughout the spinning process. Having selected the process parameters of required count and required twist, the same is fed into the controller. The user enters the desired twist and count and its limiting range in the controller through the man-machine interface. Based on the set value and its range the relationship is to be maintained between count and twist during the spinning of the yarn, so that the yarn is of substantially uniform structure throughout its length. Even minor variation in the speed relationship of the drafting rollers and spindles, the controller acts quickly to adjust the speeds of either one or both, but with a cautious to maintain both the count and twists in the yarn as desired. During spinning process, both count and twist are varied automatically by adjusting at least two of the following: the speed of the spindles,
the speed of the front drafting rollers and the speed of the rear drafting rollers..

On evaluating with the significant sample size of the yarn produced in the above known process, the whole length of yarn from a full bobbin was examined with the usual lab-testing instrument. From the results, variation in the twist found high particularly at the base of bobbin from the start of the bobbin to the stage where the spindle speed reaches a reasonably higher speed. When the machine is
running at slow speed ie upto 10000 rpm, the twist inserted is higher by atleast 2 to 3 TPI than the set TPI. On studying the above phenomena which was confirmed with various studies, this twist variation may be due to various reasons like yarn tension, traveller tilting, traveller drag / lag, friction value between ring and traveller, contact region of traveller over ring, etc., It is known that the position of traveller over the ring flange during high speed and slow speed varies and influences for these reasons which directly leads to variation in twist. This twist variation encounters during every acceleration and deceleration of machine.

Usually the ring spinning machine is allowed to run at more time at the maximum speed to have higher operating speed. Even though the spindle speed and delivery of the drafting rollers are working as per the calculated set values, the variation of twist is severe in particularly slow speed of the machine due to the above reasons. However it is unavoidable to run the machine at slow speed during starting of cop build, during power failure, during manual stoppages, etc., These results were further confirmed with machines having the drafting system driven by the main drive shaft through gearing.

To overcome the above stated disadvantages, it is necessary to provide an improved drive method of ring spinning process, which should have simple controlling apparatus and method and resulting efficient operation. As per the invention, along with entry of the required count and twist, a TPI (twist per inch) compensating value is also being entered in the PLC input device .

OBJECTS OF THE INVENTION

It is an object of the invention to provide an improved driving apparatus and method for a ring spinning machine when compared to prior art machines.

It is further object of the invention to provide a process to produce yarn with a consistent count / twist of yarn in entire bobbin when compared to prior art machines.

Another object of the invention is to provide a PLC which suits to the various process variables of raw materials.

It is yet another object of the invention to provide an arrangement to control the twist and count of a yarn during all stages of process as specified by user when compared to prior art machines.

SUMMARY OF THE INVENTION

According to the present invention, the user defines the required data of count, twist, TPI compensating value and each of its limiting ranges, the operating time, length, etc., through the man-machine interface or display. The ring spinning machine is provided with a controller provided with PLC where TPI compensating value is entered which manipulates the drive relationship between spindles and drafting rollers particularly during the slow speed of the machine or as specified by the user. Moreover the drafting rollers and spindles are provided with individual drive motors that are being controlled as per the PLC to match with the required twist / count level, particularly in slow speed of the machine. The PLC will act based on the input values set by the user at the slow speeds such as during the bobbin/cop build up from starting to 1/4th position, machine stoppages by manually or power failures, etc.,

According to one aspect of the present invention there is provided An apparatus for controlling a driving system of a ring spinning machine comprises:

a motor operatively connected to drive spindles and adapted to be connected to a source of power another motor operatively connected to drive drafting rollers through a train of gears, a PLC provided with a memory containing relationship between speed of spindle and speed of drafting roller. a display and input device in communication with said PLC provided with means for inputting the count, twist, and each of its limiting range, operating time and length means for manipulating the drive relationship between spindle and drafting roller according to input values wherein atleast one compensating value is entered as input in addition to count, twist According to another aspect of the present invention there is provided method of controlling the driving system of a ring spinning machine comprising the steps of driving a motor operatively connected for driving spindles driving another motor operatively connected for driving drafting rollers through a train of gears for producing pre-determined count of yarn entering pre determined count, twist, TPI compensating value operating time and length into display / input device connected to a PLC having memory and manipulating means connecting inverter to motor for supplying power to motor and drafting rollers sensing the speed of spindle and drafting roller connected to each
motor calculating the speed of each motor based on the input values and sensed speed of each motor
controlling the speed of spindle with the drafting rollers according to the calculated values.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING

Fig.1 schematically illustrates the drive arrangement of a ring spinning machine according to the invention.

Fig.2 schematically illustrates the block diagram of control arrangement /circuit for an arrangement shown in figure 1.

The ring-spinning machine consists of a creel arrangement provided with suspended bobbin holders to support the roving bobbins, which is enable to feed the roving to drafting arrangement, which is provided at the downstream position of creel arrangement as known in the art.

According to the invention as shown in Figure-1, the ring spinning machine is having a drafting arrangement (1) downstream of the creel arrangement. In a drafting arrangement (1), there may be of 3 or 4 bottom & top drafting roller pairs which comprise front, middle and back pairs respectively which are not shown in details. Said bottom rollers of the drafting units are interconnected at one end by a gears train, which is driven by lay gears as known in the art. . All drafting rollers are hereafter referred as drafting arrangement (1), which is driven by any one of the following means:

(i) directly by a common single motor (not shown) or (ii) directly by an individual drive motors (2)
Said drafting arrangement (1) is being extended along entire length of the machine from one end to the other. The drafting rollers of the drafting arrangement (1) are intermittently being supported in bearings at spaced intervals as required. The speed ratio between said drafting rollers are maintained in such way to obtain the desired yarn fineness/count.

In the downstream of drafting arrangement (1), spindles (3) are positioned vertically as per spindle gauge on the spindle beam, which extend in the longitudinal direction of the machine. The spindles (3) are driven by a main motor (4) connected with a common drive shaft (5) extends along the machine from

motor end to the other end so as to drive each of all spindles. Over the common drive shaft (5), plurality of pulleys (6) are fixed, each has a driving flat belt (7) engaging in the wharves (9) on the spindles (3).
According to the invention shown in figure 2. the ring spinning machines having independently working motors (2, 4) for the rollers of drafting arrangement (1) and spindles (3) respectively. The speeds of motors (2, 4) are being controlled by means of a controller (10) provided with PLC. The controller (10) continuously monitors the speeds of drafting rollers (1) and spindles (3) through sensors (11, 12), so that the speed relationship between the drafting rollers and spindles can be maintained.

The controller (10) comprises an in-built PLC which is linked to the man-machine interface. Man-machine interface is an electronic device used to receive / show a data from / to the user, hereafter to be referred as display (13). According to this invention, the twist per inch (TPI) is measured in testing equipments by taking a sample yarn from the fully wound bobbins. It is observed that the higher twist variations occurs during built-up portion of first & final layers., For the purpose of testing, the first, middle and final yarn layers of full bobbin is being taken for measurement of twist variation. The TPI variation values of all possible yarn counts are noted down and is used for arriving TPI compensation value . Along with the predetermined count, the twist , twist variation, variation allowances the TPI compensating value arrived by the user is entered into the above system through the display (13). As per command, the controller (10) precisely maintains the speed relationships between spindles (3) and drafting rollers (1) with respect to the input data such as count, twist(TPI), twist variation, variation allowances, TPI compensating values and its operating time and/or length. The controller (10) continuously evaluates the signals received from the sensors (11,12) and initiates the necessary steps by based on the input data, to maintain the speed relationships between drafting rollers (1) and spindles (3). Based on the TPI compensating value the drafting roller speed profile will be modified in software for slow speeds ie the drafting roller speed will be increased in slow speeds to have normal TPI levels.

The apparatus provided with simple PLC helps to precisely control the count and twists in the yarn and so that the yarn is of substantially uniform structure throughout its length. Since the present invention precisely controls the speed relationship between the spindles and drafting rollers (particularly during the slow speed) of the machine with respect to real measured value, it is possible to achieve the accurate TPI in the resultant yarn. Because of the user defined input data instead of calculation derived data, the TPI variation is controlled effectively throughout the yarn spinning process. Uniform TPI throughout cop results in good appearance of fabric / yarn after dyeing. Hence this invention would be more useful and overcome the prior art problems and assures the efficient operation and productivity of the machine.

Having now described the invention in detail as required, those skilled in this art would have no difficulty in making changes and modifications in the individual parts or the relative assembly in order to meet specific need. Such changes and modifications will fall within the scope and spirit of the invention as described.

We Claim:

1. An apparatus for controlling a driving system of a ring spinning machine comprising:

a motor operatively connected to drive spindles and adapted to be connected to a source of power
another motor operatively connected to drive drafting rollers through a train of gears, a PLC provided with a memory containing relationship between speed of spindle and speed of drafting roller.

a display and input device in communication with said PLC provided with means for inputting the count, twist, and each of its limiting range, operating time and length means for manipulating the drive relationship between spindle and drafting roller according to input values wherein at least one compensating value is entered as input in addition to count, twist.

2. An apparatus for controlling a driving system of a ring spinning machine as claimed in claim 1 wherein the compensating value is inputted based on the twist per inch (TPI) variations found in the yarn.

3. An apparatus for controlling a driving system of a ring spinning machine as claimed in claim 2 wherein the twist per inch (TPI) variations of the sample yarn from the wound bobbins are measured in testing equipments.

4. An apparatus for controlling a driving system of a ring spinning machine as claimed in claim 1 wherein the compensating value is entered according to the count and twist of the yarn.

5. An apparatus for controlling a driving system of a ring spinning machine as claimed in claim 1 wherein according to compensating value, the speed of the drafting roller will be increased in slow speed of the spindle to have normal TPI levels.

6. An apparatus for controlling a driving system of a ring spinning machine as claimed in claim 1 wherein sensors are provided at spindle and drafting rollers for sensing the speed.

7. An apparatus for controlling a driving system of a ring spinning machine as claimed in claim 1, wherein display and input device includes for storing and recalling particular data inputted.

8. Method of controlling the driving system of a ring spinning machine comprising the steps of driving a motor operatively connected for driving spindles driving another motor operatively connected for driving drafting rollers through a train of gears for producing pre-determined count of yarn entering pre determined count, twist, TPI compensating value operating time and length into display / input device connected to a PLC having memory and manipulating means connecting inverter to motor for supplying power to motor and drafting rollers sensing the speed of spindle and drafting roller connected to each motor manipulating the speed of each motor based on the input values and sensed speed of each motor
controlling the speed of spindle with the drafting rollers according to the calculated values.

9. An apparatus for controlling a driving system of a ring spinning machine substantially as herein described with the accompanying drawings.

10. Method of controlling the driving system of a ring spinning machine substantially as herein described with the accompanying drawings.