Intelligent monitoring and information system for combers:ITRA CIM

Combing is an intermediate value adding process for spinning yarns of fine and superfine counts with higher strength and also with enhanced fabric appearance, say R Prakasam & D Sujatha

The spinning industry has been constantly incorporating sophisticated developments in machinery and intelligent quality monitoring and control systems. SITRA has already developed an Energy and Production Information system named as - “SITRA EnerInfosys” for textile mills. Within the overall spinning process, combing is introduced to remove short fibres below the pre-selected length and trashy substances from the sliver in order to produce clean and even sliver. Combing improves fiber parallelisation and fibre to fibre separation, and minimizes fibre entanglement and disorientation. Thus, combing is an intermediate value adding process for spinning yarns of fine and superfine counts with higher strength and also with enhanced fabric appearance. In order to enhance the machine efficiency in the existing combers in the mills, SITRA has developed a microcontroller based information Intelligent Monitor named as SITRA-CIM (Comber Intelligent Monitor) and this paper describes the details of the same.

Performance of combers

The performance of combers has a considerable bearing or yarn quality as well as the amount of waste extracted. The poor combing performance arises due to improper settings and timings, poor upkeep and inadequate maintenance, unsatisfactory lap preparation and unsuitable process parameters. Mechanical faults in combers results in excessive variation in the quality of web produced. During the normal working of the comber, it is sometimes observed that the is no web/sliver coming from one or more heads. The lap at the back gets exhausted or there is lapping around delivery rollers. If the sliver is allowed to proceed unnoticed, thickness variations might occur. Similarly insufficient pressure in pneumatically operated drafting system also leads to thickness variation. Since a higher U% and CV” of sliver results in higher count variation in yarn resulting in more end breakages, control of short-term irregularity of comber sliver is very important.

Provision of stop motion units and pressure switches at the appropriate places helps to avoid such problems. Today, the emerging trend is to have “user friendly and environmental friendly” atmosphere to ensure zero accidents and zero defects with the use of un-skilled operatives. On-line monitoring, production and machine data management have gained greater importance to bring down the down time of machines and maximize the productivity. It is commonly accepted that production increase per machine can bring down cost which is essential to sustain in the present competitive market environment. Increase in production can be achieved to some extent by reducing the stoppage time of the machine and increasing the efficiency of both machine and operator. With the above things in mind, SITRA has taken up a research project to design and develop a microcontroller based Intelligent Information Monitor with the following objectives:

• To develop an on-line process monitoring and production information system for combers
• To design an user friendly mimic panel for indicating the exact location of the fault in order to reduce the machine downtime
• To incorporate the developed system as a cost effective retrofitting unit for the existing combers in the mills
• To disseminate the acquired knowledge and technical know-how for commercial manufacturing for the benefit of the textile mills

Salient features of SITRA - CIM

SITRA - CIM (Comber Intelligent Monitor) is a micro-controller based state-of-the-art process monitoring and production information system developed to meet the arduous technical requirements. This is an on-line supervisory system works round the clock to monitor all stop motions, to collect production information and to maintain history of individual heads, etc. In order to make the system cost effective, the system utilises the existing sensors in the machine for monitoring purpose except empty lap. Since most of the existing machines are not equipped with any device for detecting empty lap, an unique circuit using photo cell senors has been designed. This is an universal system which can be incorporated in any machine with slight modifications.

The Comber Intelligent Monitoring System comprises of two independent sections - a process monitoring section and a production monitoring section. Both the process and production monitoring sections are integrated together to work through a separate central machine control unit for efficient monitoring of process as well as production.

1. Process monitoring section

Process monitoring section consists of individual plug and play modules for detecting the following stop motion signals.

• Trumpet stop motion signals
• Empty lap stop motion signals
• Safety signals such as door safety, absence of can, insufficient pressure and motor overload, full doff, etc

In addition to the above, this section is also provided with a monitor control unit, a machine control unit and a mimic display.

2. Production monitoring section

The production monitoring and information section is a combination of length of production designed to provide production data sup production, shift wise production data, stop running hours, total number of doffs, nips current time, frequency of stoppage of each. The starting time of all the shifts is user programmable to enable the user to set the time suitable for them.

Increase in productivity by using SITRA-CIM

The anticipated increase in machine productivity by incorporating SITRA-CIM (Comber Intelligent Monitor) in the existing combers in textile mills has been worked out by conducting a detailed time study in two textile mills situated in Coimbatore. The results are as follows:

1. In one mill where 4 combers (running at average speed of 180 nips per minute) are assigned per tenter, the possible increase in machine efficiency will be 1.5 per cent by means of reducing the observing time for the faults in the machine.

2. In another mill where 8 combers (running at average speed of 180 nips per minute) are allotted per tenter, the anticipated increase in machine efficiency will be 2.5 per cent by means of reducing the observing time for the faults in the machine.

In addition to the above increase in production due to increase in machine efficiency, the efficiency of the operatives will also improve due to reduced strain in locating the faults. The SITRA-CIM (Comber Intelligent Comber) is cost effective and can be retrofitted in the existing combers in the mills.

(The authors are with SITRA, Coimbatore)