Improving Technologies
When a customer takes a look at our tyre gleaming with its black side from the store shelf, he only sees the details of tread pattern, marking, takes a glance at the price label and technical specifications printed on the leaflet. Usually no one even thinks that several thousand people have had a hand in its production – and these people are the employees of Altai Tyre Plant.
Special responsibility lies on the shoulders of engineering department stuff, who are constantly seeking to improve tyre production process. This is essential because the company wishes to offer durable products of highest possible quality to its customers. We have asked the main specialists of ATP about how they manage to maintain the reputation.
Cord is the Basis
Alevtina Mikhailovna Ogneva, chief production manager, told us about what is done for tyre quality improvement.
— One of the main working steps in tyre quality improvement process is the improvement of the quality of rubberized cord. Carcass is the main strength part of pneumatic tyre and is usually comprised of several layers of rubberized textile cord. That is why performance characteristics and technology of preparation and assembly operations strongly depend on the quality of rubberized cord.
Real-life tests have shown that tyres having stronger interconnection between cord and rubber have better operating abilities. Determinant factor allowing stronger interconnection is intermolecular and chemical interaction at the phase boundary.
To implement such interaction the maximum possible contact between duplicated surfaces is required. This contact can be achieved through a high-quality cord rubberizing with rubber compound in the area of calender rolls gap during rubber-cord system vulcanizing.
Quality of rubberizing also depends on many things: quality of rubber compound, its uniform plasticity, steadiness of physical and mechanical properties.
To increase quality of cord fabric and life-time of tyres the project of cord rubberizing exclusive of straight flow has been designed. After rubber compound has been produced the so-called rest process takes place, which facilitates stabilizing of physical and mechanical characteristics of rubber compound.
Feeding of calender rolls of cord line is performed while heating rubber compound on the roll mills that is why the twin roll mills unit was purchased for this purpose.
Implementation of this project will help to enhance rubberized cord quality and the fabricability of the process significantly, which in its turn will increase the quality of goods produced. As of now the equipment has been brought into operation, and we work on the optimization of production process.
Rubber of new quality
Enhancement of the quality of rubber compounds is also an important aspect of the quality of goods produced. For this purpose the stock preparation shop of Altai Tyre Plant has undergone modernization of the system responsible for ingredient batching management and rubber interfusing in four two-phase production lines.
Automatic system of rubber interfusion management (ASRIM) provides preciseness of material metering and allows the operator to control and manage temperature and time mode of rubber compound interfusion.
Computer control system allows storing data of material batching and temperature and time mode of interfusion during production process. In case of performance failure in weighing system and equipment (failure to provide batching preciseness, increased time of weighing amount gathering, end plate of weighing system is not closed, etc) computer generates “failure” warning. Thus an operator has the opportunity to interfere with the production process immediately and fix the problem.
Transfer of rubber interfusion lines to ASRIM system control makes it possible to decrease the influence of human factor on the production process and achieve enhancement of repetitive accuracy of final output characteristics.
Product quality enhancement requires continuous improvement of production process. Thus in the beginning of the year 2009 the ASRIM system was installed in tube shop for the first and second stages of rubber interfusion process.
The “Duplex” line was also brought into operation in the beginning of 2009, which is used for production of twin profile components for assembling of radial tyres for motor cars and light-duty trucks. We also designed and implemented a new formula of rubber compound of tread base of radial type tyres for motor cars and light-duty trucks and the mode of feeding and overlapping of tread base using five-roll mill calender included with the production line.
“Duplex” production line made it possible to increase tyre quality and avoid unnecessary operations that were performed before manual assembly of tyres.
More modern materials
Work on quality enhancement by means of new materials is being actively done at ATP. Each year steel wire cord takes leading positions among reinforcing materials more steadily. Steel wire cord for breaker of radial tyre still remains unrivalled among all other standard cord types.
In order to extend variety of steel wire cord types and to provide compatibility in case of absence of one or another cord type fine-tuning of steel wire cord (9L30NT) fabricating technology has been performed this year according to the conditions of OJSC AP “Altai Tyre Plant” instead of steel wire cord 8L33NT. Complex assessment of pilot batch of 9L30NT steel wire cord of 2+7x0.30NT structure (made in Orel) in lab and production environment has shown that physical, mechanical and adhesive properties of the metal cord meet the requirements of normative documents, namely: the 9L30NT metal cord type was straight-line, non-spin, and remanent rotation on separate spools did not exceed 2-3 circumvolutions. Since strength properties of 9L30NT metal cord type are higher than those of 8L33NT metal cord, change in thread pitch during the process of rubberizing was not required for this cord type. The diameter of metal cord thread of 9L30NT type was 1.15mm, and for 8L33NT cord type it was 1.2mm.
9L30NT metal cord rubberizing on the MCRL-800 line and further pattern cutting of rubberized bed and the assembly of breaker bands were performed with no difficulties.
To determine working ability of tyres for trucks pilot batches were produced with the use of metal cord breaker of 2+7x0.30NT (9L30NT) structure. Bed tests of tyres were then performed in the lab of OJSC PA “Altai Tyre Plant”. Positive results that were achieved during the testing met the requirements for general working ability and proved the practicality of the usage of 9L30NT metal cord type in breaker of tyres for trucks together with 8L33NT cord. At present the abovementioned cord type is used as mass product.