When machines grow

Spinning machines use different technologies to ultimately produce yarn from the starting product in the form of many cotton bales - in mass and continuous operation. The machines, which are set up in parallel in large numbers at yarn manufacturers, usually have to be able to run 365 days a year without interruption and are only shut down on public holidays. What they all have in common is that they reach considerable dimensions - due to the large number of spinning positions (> 1600) connected in parallel, which are required to be able to produce economically and efficiently.

Expansion in longitudinal direction

The length of a machine, starting from the centre of gravity, can increase by centimetres if the machine temperature rises during operation. What remains hidden to the eye, however, presents the machine builders in Winterthur with considerable problems. During operation, robots move the individual parts of the machine around.

It's about centimeters

spinning positions to reattach broken threads - to do this by hand would be far too uneconomical. Over all spinning positions, and thus over the entire length of the machine, it must therefore be ensured that the robot approaches exactly the position in front of the spinning position which it is supposed to approach; if this does not happen, its operation remains unsuccessful, the spinning position fails and the efficiency of the system drops.

In order to document online how machines "grow", they are measured every five minutes during operation. Martin Tobler, calculation and measurement engineer in the Analytics department at Rieter, carries out measurements that ensure this with mobile laser trackers that are set up directly between the machines for this purpose. They measure not only the positions of the spinning points, but also the rails themselves on which the robot hangs. And even when selecting the fixed points on the floor for setting up the laser tracker, the tendency of the machines to expand in the longitudinal direction must be taken into account. The automatic changing of the bobbins - on the largest machines, up to 1632 yarn carriers are changed simultaneously - is also clearly dependent on the precision achieved in the assembly of the system; for this, the grippers of a subsystem called doffer must be measured as precisely as possible. Laser trackers are also used here.

Energy-saving drives

Energy costs are a major factor in spinning machines, along with raw material utilization and durability. In a single machine, up to 12 motors can

Stable efficiency

The actual main motor for ring spinning is joined by drafting system motors and motors for suction. The great length of the machines also presents a particular challenge for their drive; a drive shaft of such length, set in motion at one end, would exhibit a different, time-delayed rotary motion at the other end. For this reason, spinning machines are equipped with a central drive, which only enables a multi-station simultaneous spinning process. Trackers help Rieter to optimise the alignment of these drive components, which increases efficiency and reduces energy costs.

All technologies from a single source

The customer selects his machine depending on the desired properties of the end product: Rieter is the only textile machinery manufacturer able to offer not only all processes for spinning preparation but also all four end spinning processes established on the market (ring, compact, rotor and air-jet spinning) from a single source. Which one the customer ultimately chooses depends mainly on the yarn properties required, such as strength, fibre abrasion and yarn diameter. It is undisputed, for example, that shirting fabrics which are also finished non-iron are best produced from compact yarns with high yarn strength.

Laser measurement technology with a long tradition

Rieter was already working with laser measurement technology 20 years ago; however, it was not able to establish itself at that time. Too expensive, too inflexible in handling; even interferometers could not meet the requirements of the machine builders. Only the use of laser trackers in combination with powerful software (SpatialAnalyzer) fulfilled the expectations that were placed on the measurements on the machines. Here, too, special challenges had to be mastered: The fiber fly occurring in spinning mills due to the fiber material consisting of fine fibers and dust particles during spinning can require special measurement strategies for laser trackers - the particles in the air may impede the propagation of the laser beam.

In contrast to the waxing of the plant, this effect is even directly observable: The normally invisible laser beam of the measuring systems becomes visible during ongoing spinning operation, an unmistakable sign of the increasing pollution of the air and thus a serious problem for all laser-based measuring systems - not only laser trackers are affected here. The RADIAN laser tracker from API used by Rieter is designed for a measuring distance of 80 meters and must be able to work reliably in this area even under these unfavorable conditions. Its use in the confined environment between the spinning machines also had to be tested. The final selection of the system from several suppliers took place within the framework of an extensive test procedure at Rieter in Ingolstadt.

Mobile measurement in assembly

Interlinked systems such as ring spinning machines require a high degree of precision, especially during assembly; and here only a mobile measuring system can provide information as to why the individual systems in the devices are correct, but why deviations occur after assembly. Again, it is the large dimensions of the system that give rise to the suspicion of deflections that could not be measured or localized with any other system in this constellation. The here driven measuring

Control the main mass

The laser tracker is worth the effort, as the machines can be designed for a continuous operation of 40,000 hours, which is equivalent to an uninterrupted 5-year operation. Thanks to its compactness, the laser tracker can be set up directly in front of or between the parallel spinning machines for measuring.

However, its small size also has a disadvantage; from a distance of 20 meters, the indicator lights can hardly be seen with the naked eye in this environment. But here, too, Rieter is one step ahead: an iPod attached to the wrist informs the user about the tracker's measured values and enables the user software to be controlled via a convenient user interface. The corresponding app is offered free of charge by the manufacturer of Spatial- Analyzer New River Kinematics in the Apple Store.

Further fields of application

Mobile laser-based measuring systems can also show their advantages in the measurement of individual components at Rieter. If the individual parts are too large for the measuring machine, the tracker can also be used for on-site measurement. In addition, it is possible to compare the measured data directly with the CAD model read in. For example, entire sheet metal housings can be measured in the simplest way. Once the measuring points and processes have been defined, the decisive dimensions can be checked very quickly and easily.

Due to their portability, laser trackers are also used for service missions, as their size allows them to fit into the boot of a station wagon (although the portable tripod still requires the largest transport box). Likewise, they can be carried in personal luggage when traveling by air. Only one person is required for operation; at Rieter, depending on the measuring task, two people may be required at times due to the large measuring distances.

Mature technologies

The basic technology of spinning is considered mature, its beginnings date back 150 years. The focus is increasingly on increasing the efficiency and performance (which increases the machine length) as well as the quality of the machines, whereby their service life plays a not inconsiderable role. Designed for 10-20 years, 30-40 year old Rieter machines are still being traded today. Many achieve legendary operating times; for example, Rieter's oldest producing spinning machine (a bale breaker for opening cotton bales) was built as early as 1940 - and is still in use.

Increasing globalization has meant that spinning machines from Winterthur are now produced locally around the world, such as in China or India; these machines are in turn sold worldwide. More recent innovations concern compact spinning, for example. This refers to more sophisticated machines with even more mechanics. They produce yarns that have fewer hairs, which equates to less fly. They can be used to produce even finer shirts, for example. Rieter also offers the new Air-Jet technology; here the fibres are twisted supersonically with air, which can almost double the production output per machine.

Ready for the future

The textile industry is one of the oldest and, in terms of the number of employees and turnover, still one of the most important branches of the manufacturing industry. Especially in recent times, many competitors have entered this global market. Winterthur, with the headquarters of Rieter and others, continues to be the location where textile machinery is improved, provided with new functions and further developed. The company is represented with 19 production sites in 9 countries and employs

Technology and world market leader

around 4,700 employees worldwide, of which about 28 percent are in Switzerland. It's good to know that the use of modern laser-based measurement technology ensures the performance, quality and innovation of new machine generations - which ensures their success on the market.