Fabric to ensure perfect quality
Advanced drive application for intermediate inspection machine by Spandauer Velours
Spandauer Velours’ production focuses on high-quality velour and plush fabrics for the paint roller and cleaning industries as well as modern velours fabrics for the commercial sector. A retrofit is a testament to the company’s commitment to quality. Machinery Drives ACS880-M04 by ABB control the application.
The products offered by Spandauer Velours are fabrics for large stages as well as for upholstered furniture and rail vehicles. Their portfolio also includes technical textiles such as paint roller or cleaning plush and plush used in textile washing systems. This company from Lichtenstein in Saxony has thrived on the market for more than 30 years. Their global customers include manufacturers in the paint roller and cleaning industry, textile manufacturers and furnishing contractors as well as a large number of small and medium-sized companies.
Spandauer Velours is committed to ensuring that only high-quality materials ever leave the company. As a result of a retrofit, a new intermediate inspection machine now helps to guarantee the company’s quality standards for its products. The intermediate inspection machine is used to check the so-called dyed material. This refers to the raw material that has been dyed by the dyer. The dyed material is unwound directly from the batching roller (metal spool) on the machine, it then undergoes a visual inspection and is finally rewound onto a batching roller for further processing. In the event that any colour defects are detected, the fabric is automatically returned to the dyer. This machine belt operates at a speed of 5 to 60 metres per minute. The diameter of the textile rolls ranges from 220 to 1,800 millimetres with a weight of up to 600 kilogrammes.
“The panel is designed for ease of use and the layout is very clear. I am extremely impressed by it”
The system is based on a material inspection machine from 1960. Formerly, the goods were unwound from the batching roller and conveyed over an inclined inspection table where they were then rewound onto cardboard tubes. The system was subsequently modernised in order to expand its functionality and to be at the cutting edge of technology. A new component has now been added: a winder at the end of the machine. The entire material guidance system had to be adapted in order to be in a position to perform the new task, and the drive technology was also modernised. As part of the retrofit, the originally installed hydraulic motors were replaced by frequency-controlled geared motors. The technical distributor Schultz+Erbse was commissioned with the upgrading of the electromechanical parts, i.e. motors, frequency inverters and gearboxes.
High demands on drive technology
It was Martin Franz from Schultz+Erbse who designed the electric motors and gearboxes. Referring to the requirements of this application, he says: “Seven rollers with a high mass moment of inertia have to be brought to a certain speed with a specific torque value. It is also vital to ensure that the correct ratio of inertia is maintained between the gearbox, the motor and the load hanging on the outside.” Seven ACS880-M04 Machinery Drives with an output of 0.75 kilowatts and 2.2 kilowatts respectively control the roller motors. This series of units is an option-enhanced variant of the ACS880 series for winders, wire-drawing machines, mixers and other heavy-duty applications. The ABB frequency inverters support common motor types in mechanical engineering, from standard asynchronous motors to permanent magnet and synchronous magnetic reluctance motors.
According to Felix Hollstein, technical advisor for Drive Technology at Schultz+Erbse, the direct torque control (DTC) of the frequency inverters is a key feature in this application. DTC enables high static and dynamic accuracy of the motor speed. “It is for such heavy-duty runs or where the torques are difficult to estimate that DTC holds particular advantages because the control is very direct”, says Felix. Previously, the system was equipped with hydraulic motors, which meant that it was only possible to estimate the required torques.
Control loop for the winder
The ACS880-M04, which is responsible for the winder motor, is equipped with a winder control programme to ensure optimal winding and unwinding of the fabric track. The function of the winder is to unwind all incoming material. During this process, the ACS880-04 receives a target value for the winding tension from the higher-level control system and then the current speed via an adaptive programme. An ultrasonic sensor measures the diameter of the winding. In addition, the frequency inverter receives the current value of the intermediate circuit voltage from drive 5 (feeding roller). Should the intermediate circuit voltage of drive 5 increase too much, the tension target value is reduced slightly until the voltage is back within normal range. The drive uses all these values to calculate the current speed at which it must travel and the actual traction value. This results in a simple roll handling.
Sören Rößler is the head of Maintenance at Spandauer Velours. He explains: “The frequency inverter with the winder software obtains the information about the material that is currently running on the machine. It has to independently determine whether more or less material is being fed in and adjust the speed and torque so that the material is neatly wound onto the batching roller.” In addition to the smooth functioning of the frequency inverters, their user-friendliness is equally important to Sören. The ACS880-M04s feature a modern comfort panel equipped with assistants, various display options and configurable screens. He makes the point: “Within our company, even a layman needs to be capable of parameterising the frequency inverter; after all, an expert from Schultz+Erbse is not onsite every day. The panel is designed for ease of use and the layout is very clear. I am really impressed by this.”
“The majority of customers actually only make use of ten per cent of the devices’ potential”
In this application, Felix believes that more functionalities of the frequency inverter have been used than is usually the case. “The majority of customers actually only make use of ten per cent of the devices’ potential. By way of example, in this machine, the adaptive programming that the frequency inverters support had been well used for extended application programming. The drive-to-drive link is also used. This enables straightforward master-slave communication between the master frequency inverter of the feed roller and the slave device of the winder.”