In the latest generation of circular combs, largest active combing surface in combination with adjustable settings in height enables customers to achieve an even more economical combing result.
Latest generations of combers such as the Rieter E86 with up to 550 nips/min and production rates of up to 90 kg/h place increased and, in some cases, novel demands on the technology components. To meet customers’ demands for more economic combing results as well as the increased demands of the new combers, Graf has developed the new generation of circular combs FlexComb in cooperation with Rieter.
Phenomenon Even though the customers are very satisfied with existing portfolio, some expressed their desire to extend the application of the comber, particularly for special needs e.g. obtaining minimal noil. In addition a solution was sought to eliminate the differences in the distance RZA from circular comb to nipper from combing position to combing position. These variations that can be due to the tolerances in the manufacturing process of either circular comb or comber can result in differences in noil extraction as well as in the combed sliver.
As a result of the increased nip rate of the latest comber generation additional topics which previously got little attention, i.e., aerodynamics, stiffness and inertia of the circular combs take an increasingly more important role. Thus a new generation of circular combs for a wider range of application in combination with increased versatility but no sacrifice in quality needed to be developed.
The developed solution
To meet the challenges of customers as well as the machinery makers, Graf has devised the FlexComb, a new generation of circular combs.
The distance between circular comb and nipper can be set more easily as a result of the precise, height-adjustable system in the circular comb. Customer-specific requirements as well as local circumstances and variation in the raw material can be better taken into account and the desired result can be precisely chosen with respect to quality, yield and productivity. This provides customers with additional levers and setting options in order to achieve a maximally economical combing performance within the control loop Q, Y, P (see fig. 3).
A further feature of the FlexComb generation is the detachable spoiler which minimises aerodynamic turbulences within the combing position and notably contributes to a substantially improved web formation at increased nip rates. For customers and applications that do not require this spoiler, it can be easily removed, leading to a further reduction in the weight of the circular comb. The excellent interdisciplinary cooperation between development, production and technology has led to a user-friendly, weight-optimised, rigid and highly precise system. Most accurate components and the machining of the key geometries in assembled condition assure that, over the years, the system does not suffer any loss in precision and running performance despite long operating time and repeated dismantling.
Precise setting of distance RZA
The height adjustability of the FlexComb allows the distance from circular comb to nipper to be precisely set for all of the eight combing positions. This results in an optimally even combed sliver and uniform noil at all combing positions. Fig. 5 illustrates the distances between circular comb and nipper across the eight combing positions with conventional circular combs and those with FlexComb, set in this example to a value of 0.2 mm for this trial. Fig. 6 illustrates a trial in which the distance between circular comb and nipper was increased in steps of 0.1 mm. In order to obtain the same amount of noil extraction at each combing position, the detaching distance ‘d’ had to be adjusted, meaning that with the same measurement ‘d’ the amount of noil extraction decreases with a higher distance between circular comb and nipper (RZA).
The circular comb can be set easily and precisely to the relevant needs by different combinations of spacer discs. The setting range of maximum 0.95 mm is carried out individually for each combing position, and, if necessary, can even be varied within a circular comb within a small range as a result of the four positions that can each be set separately. Different combinations of the spacer discs supplied allow the distances between circular combs and nippers to be set from 0.10 mm to 1.05 mm in steps of 0.05 mm in a simple and straightforward manner.
RZA differences from combing position to combing position, owed to the manufacturing process can thus be compensated and with an identical setting, all combs perform in an optimal operational working range, assuring the most economic combing result.
Improved web formation
The increased nip rates added new demands on the aerodynamic properties. Air turbulences caused by increased speed negatively influenced the fibre fringe and the web formation, occasionally leading to inferior yarn values. To eliminate these turbulences, FlexComb is equipped with a spoiler, which improves the web formation through an optimised airflow within the combing position.
Even though the latest generation of circular combs is considerably more complex and consists of multiple components, the engineers of Graf succeeded in keeping weight and inertia nearly equal while even improving the stiffness.
As a result of the steadily increasing nip rates, the resulting forces and resonances were a further demand to this latest generation of circular combs. By performing extensive simulations as well as elaborate field trials all demands were thoroughly taken into account during this development. The resulting light-weight, rigid and exceptionally durable product lives up to the highest requirements.
The height-adjustable circular combs, FlexComb, with the largest active combing surface allow a greater versatility and an extended range of application. The adjustable settings pave the way to consider changes in the market requirements or in the raw material at any time. Furthermore a yarn quality unrivalled to date can be achieved.
Graf + Cie AG places the focus on service
- Jörg Brodermanns, Head Technical Sales
To train employees, customers and service partners on the current level of technology is just as important as the quality of the products. Therefore Graf continuously strives to extend this standard. The newly opened training centre in Rapperswil is thus a clear commitment to reinforce the quality of service and training.
With the application of Graf products the customers can concentrate on their core activity and enjoy advantages such as long service life or maximum fibre yield. Graf customers can thus rely on the highest quality standards, sustainable and sound performance according to DIN EN ISO 9001:2015 certification, the integrated quality control throughout all steps of production as well as process reliability by high vertical integration. These customers not only enjoy the comprehensive product portfolio of Graf. The proximity of our technical consultants and the global distribution and service network also create an important basis of trust for our clientele.
Graf + Cie AG places the focus on service New training centre at Graf Rapperswil Addressing individual customer requirements is one of our outstanding strengths. Graf is familiar with each production step in detail and is in a position to provide, beside the standard products, individual solutions, which, where required, can be developed in close cooperation with interested partners. Particularly in case of the qualitative dimensions the deciding factor for the service quality in the market is, beside the on-site customer service, the continuous further training of employees, distribution partners and customers. Specific trainings assure that employees identify with the products and are motivated to actively contribute to the further development and improvement.
Graf disposes of a global service network with a total of 21 service centres in the main textile areas of the world. Thus Graf is in a position to guarantee the customers and partners quick reaction time in case of new installations, for maintenance and service work and in emergencies.
Together with partners Graf develops service equipment that ensures the maintenance and precision of reclothings and regular service on customers’ production facilities. The handling of this service equipment needs to be trained. For this purpose Graf offers customized instruction and commissioning courses. These trainings take place either at customer’s site or else in our own training facility in Rapperswil.
The Graf service technicians act as an important interface for the customers’ technical personnel. They do not only carry out the training on the use of the service equipment for the employees but also provide active advice to assure a consistent quality in service. In addition to regular workshops for customers all over the globe it is also important to train our employees to the latest state of technology.
Specifically for this purpose our existing service and training centre was relocated to a new and bigger area in the beginning of 2016. We can now offer a modern working and training facility, equipped with all service machines and a complete infrastructure for instruction courses for our service engineers, partners and customers. There is sufficient space for two new cards in the same room.
The Rieter C70 and Trützschler TC11 cards complete the possibility to provide training in maintenance, to actively address resolutions to problems and carry out instruction courses professionally. These cards are also used for the testing and further development of new service equipment.
Already in March 2016 an initial training course for our agent in Pakistan took place. Six members of staff had the opportunity to deepen their knowledge on the refinement of a flat service and the related settings on the card for several days.