Manufacturer improves weaving productivity 15 percent with Siemens Digital Industries Software solution and services

Enhancing productivity

Picanol is a leading weaving machine manufacturer that worked with Siemens Digital Industries Software, to realize higher productivity and enhanced noise and vibration standards on its next-generation rapier weaving machines. Simcenter Engineering services and Simcenter portfolio were also used to optimize the new rapier driver mechanism for Picanol’s upcoming rapier loom.

Simcenter Engineering used dynamic evaluations in the motion simulation solution from Simcenter portfolio to enable Picanol to reduce internal peak forces, avoid wearing out bearings, lower the weight of oscillating parts and extend the fatigue life of key parts. This allowed Picanol to significantly speed up the motion of the rapier as it travels through warp yarns, which translated into 15 percent higher weaving productivity.

Developing quality equipment

Industrial weaving mills running on hundreds of Picanol looms around the clock deliver a notable portion of the world’s daily fabric production. Picanol is a leading manufacturer of weaving machines and currently has more than 110,000 of them in operation, with some 2,600 customers around the world. Large and small-fabric manufacturers use Picanol weaving equipment to efficiently create high-quality fabrics, with few interruptions and easy changeovers to maintain high productivity.

Fashion tastes and preferences change frequently, so manufacturers require maximum flexibility. To effectively respond to rapidly changing weaving requirements, Picanol’s rapier weaving machines are designed to flexibly deal with short runs, different styles, colorful designs and diverse fabrics, including cotton, voile, crepe, wool, glass and DuPont™ Kevlar® aramid fiber.

“Ultimately, it’s all about money,” says Kristof Roelstraete, director of rapier weaving machine development at Picanol. “The more machines a single weaver can manipulate, the lower the overall cost of ownership for the fabric manufacturer. Our strategy is to develop quality equipment that features high-weaving quality and operational reliability, translating into premium fabrics and rare weaving stops.

“In addition, the modular design andelectronic control of rapier weaving machines provide straightforward changeover procedures when the loom is set up for a new article. To maintain top-market productivity and flexibility for our rapier weaving machines, we developed and introduced a number of ground-breaking technical advances. One example is the atented Sumo direct-drive engine, which is controlled electronically, stops or slows down immediately if needed and reduces overall power consumption by 10 percent.”

Leveraging a strategic partnership

Picanol partnered with Siemens Digital Industries Software to investigate the noise radiation performance of the rapier weaving machines. Picanol and Simcenter Engineering were able to drill down to the individual operational noise sources through operational modal analysis, operational motion and deflection analysis as well as acoustic intensity and noise radiation measurements.

Measurements confirmed that maximum noise radiation occurred around 1,200 Hertz, a frequency that disturbs conversations in the area surrounding the weaving machine. It was understood that the nature of the excessive sound at this frequency was of a purely kinematic origin, and that it coincided with the noise generated by gearwheel contact. The tests also indicated that during operation, bearing alignment and pretension tended to evolve unfavorably.

“With the development of the successor to the GamMax, Picanol decided to cooperate with Siemens Digital Industries Software,” says Roelstraete. “Joint engineering efforts performed early in development allowed us to increase productivity of our weaving machines, while keeping noise and vibration at acceptable levels. A key assembly in this regard is the cutting-edge rapier driver mechanism, which drastically increased operational speed, and as a result raised noise radiation considerably. The circular motion of this mechanism drives the bidirectional linear movement of the rapier, a dedicated component that transports the lengthwise thread through stretched crosswise threads of the fabric being woven.

“Simcenter Engineering fine-tuned the design of the rapier driver mechanism, and succeeded in reducing noise radiation significantly. This represented a major engineering challenge, as today’s industrial rapier weaving machines relentlessly move the rapier back and forth up to 25,000 times an hour. The staggering rapier accelerations involved in the weaving process even exceed the engine piston acceleration of Formula 1 race cars!”

Enhancing performance through simulation

The extreme forces resulting from this high-speed motion put a lot of pressure on the entire rapier driver mechanism. Simcenter Engineering modeled the rapier driver assembly and concurrently optimized subsystem performance characteristics in an effort to lower assembly weight, prevent components from wearing out, eliminate fatigue-life effects and reduce acoustic radiation.

In Picanol’s new compact rapier assembly design, the driving wheel applies circular motion to its connection with a fork element. This fork element holds a cross member piece that is restricted to pivoting in a fixed plane. Through the oscillating motion of the fork element, the cross member (and rapier wheel) pivots in a clockwise and counterclockwise direction, ultimately pushing and pulling the rapier through crosswise threads at high speed.

To reduce the aggressive dynamic forces involved, engineers applied rigid modeling to relocate the center of gravity of moving assembly parts. These actions included position, size, shape and weight modifications of parts.

Rapier driver assembly parts slightly deform during operation so a dynamic multi-body model of the entire rapier driver mechanism was created. By modeling key components as flexible bodies using finite element analysis (FEA), the effects of deflection and resonance were automatically taken into account when simulating the dynamic assembly load cases.

During operation, the deflection of parts slightly changed the location and orientation of the bearings, which introduced a slight misalignment and axial bearing forces. Performing simulations using motion solution from Simcenter portfolio allowed Picanol to establish optimal bearing performance.

Motion simulation solution from Simcenter portfolio provided the foundation for realizing significant improvements in durability, noise and vibration. This was achieved by increasing bearing and housing stiffness, improving bearing alignment and applying appropriate bearing pretension. Dynamic motion simulations also helped Picanol to trim radial bearing forces through further weight reduction of moving and oscillating parts.

Motion simulation solution from Simcenter portfolio helped to trim down radial bearing forces through further weight reduction of moving and oscillating parts.

Extending fatigue life

Picanol used simulations generated using motion solution from Simcenter portfolio to evaluate the fatigue life of rapier driver parts. From simulated dynamic internal loads, engineers were able to retrieve maximum local stress values for each FEA-modeled component. Durability hot spots were identified for locations facing stress variations that approximated or exceeded the material-specific endurance limit. To extend the life of key components, the functional holes of these parts required repositioning and resizing. It is critical to maintain high durability standards so weaving machines will run virtually non-stop for a 7 to 10 year period without having parts that fail due to insufficient fatigue life.

Another important performance characteristic is the noise that weaving machines radiate. One of the major noise sources is the rack-and-pinion transmission that is used as part of the rapier driver assembly. The toothed rack on the pivoting rapier wheel drives the linear motion of the rapier. Each time the rapier reverses direction, the tolerance between rack and pinion teeth results in an impact excitation, which is characterized by a high-frequency bandwidth. The excitation systematically travels through the bearings and initiates vibrations in the housing structure, which in turn radiates noise.

To resolve this, Picanol created a dedicated multi-body model in simulation motion solution from Simcenter portfolio, which took into account gear and rack/pinion tolerance as well as varying contact stiffness of teeth dynamically gripping into one another. This enabled Picanol to derive the dynamic bearing loads through multi-body simulation and apply them to the finite-element model of the housing. Then the average value of the resulting surface vibrations was taken as a measure for the radiated noise. As simulation results indicated, Picanol reduced the noise radiation by increasing the damping of the housing structure, and by using more expensive gears produced with smaller tolerances and higher-quality tooth finishing techniques.

Durability hot spots were identified for those locations facing stress variations that met or exceeded material-specific endurance limits.

Facilitating significant improvements

“The combination of realistic virtual simulation and in-depth testing know-how makes a big difference in designing better weaving machines,” says Roelstraete. “In the ongoing development process, technical excellence helped us raise the productivity of our next-generation rapier weaving machines by 15 percent. This performance boost was realized through higher machine speed and lower downtime, the ability to weave a wider variety of textiles, more flexibility in switching between articles and lower weaving costs.

“We greatly appreciate the contribution of Siemens Digital Industries Software. Advanced tests precisely indicated how machine performance could be further improved, and early process simulation optimized the real-life operation of our new rapier driver mechanism.

“Motion simulation solution from Simcenter portfolio provided the foundation for realizing significant improvements in terms of durability, noise and vibration. As a result, we eliminated at least one complete prototype iteration step, which reduced both development duration and expenditures.”