Running smoothness even at highest speeds. TIRA balancing station in a new railway wheels manufacturing line

The traffic safety of locomotives, rail cars and high-speed trains essentially depends on their wheels. An important criterion is the running smoothness which is affected by unbalances. They arrise when the rotation axis of the wheels does not comply with their axis of inertia in axial direction. Unbalances manifest themselves during the journey by vibrations and cause increased wear on the wheels, wheel bearings and undercarriage components and on the rails. For this reason, railway wheels must be tested for unbalances and be balanced during production and later during maintenance measures. Therefore, a balancing station is part of a new manufacturing line for railway wheels which was built by an internationally leading manufacturer of metal forming machines for a renowned manufacturer of railway wheels. This line has a length of approximately 200 m and contains several workstations where the starting material, cylindrical steel blanks, gradually is shaped, processed, measured and tested. The transportation and the delivery to the stations is automatically carried out by a linear portal, the cycle time is 60 secs. At the end of the line the wheels are tested and, if necessary, balanced in a balancing station for wheel discs which was developed and built by the testing machine manufacturer TIRA.

Operating principle
The balancing station consists of two force measuring vertical balancing machines type KV 1200 HA and type KV 1200 F which are essentially identical. The machine mentioned first is integrated in the production line, while the other one is installed off-line. The off-line machine is equipped with a POWERmaster type precision axis system from the Swiss company Otto Suhner, Division Automation. The control of the high performance machining spindle and the slide units, which are all new developments, is precisely adapted to the interaction with the balancing machine. The wheels are put automatically into the in-line balancing machine where the measurement of the unbalance and the turning to the marking position according to the UIC 812-3 and EN 13262 standards are carried out in one clamping. The process is done automatically and controlled by the operator of the complete line at its control desk.
The machine measures piezoelectrically the unbalance behaviour of each loaded wheel. In the case that the unbalance exceeds a predefined tolerance value, the machine determines the position at the wheel where a certain quantity of mass must be milled out in order to compensate the unbalance. As the entire process takes less than 45 secs it lies clearly within the takt of the production line. If the unbalance of a wheel needs more machining because of its size, the wheel is automatically inserted into the off-line balancing machine in order to be processed and finally guided into the manufacturing line again. In this case, the operator who is responsible for the off-line balancing machine has only the task of inserting the wheels into the take-up device, starting on a display the automatic measurement procedure and treatment processes and returning the wheels into the manufacturing line when the processes are terminated.
Using the measured values, the line control also calculates the milling path width, length and depth values which are actually necessary and controls the processing spindle. The chips which are produced during the milling are sucked off. After processing the unbalance behaviour of the wheel is measured again and controlled, and the unbalance position is marked. In this way, the line speed will not be effected. After leaving the balancing station, the wheels pass through a marking station in the manufacturing line and are then fully operational. The TIRA balancing machines are characterized by a fast, precise and clean operation and can be connected to a computer-aided quality (CAQ) management system.

Technical data
Balancing machine (model) KV 1200 HA / KV 1200 F

Wheel disc
Weight, max. (kg) 1500
Outside diameter (mm) 600 – 1350
Machine
Width x depth x height (mm³) 2500 x 4800 x 3250
Loading height (mm) 1100
Balancing speed (1/min) 400
Measuring uncertainty (gm) < 0.4
Cycle time < 45 secs. (KV 1200 HA)
< 4 min (KV 1200 F)

TIRA GmbH develops and manufactures measuring and testing systems. The company founded in 1947 is divided into the special fields vibration testing, material testing and balancing systems. About half of the approximately 130 employees are engineers or technicians. Up today, several thousand of TIRA systems are in use in a wide range of industries. Among the users there are automotive manufacturers and their suppliers, rolling-stock builders, manufacturers of aviation and aerospace equipment, manufacturers of electronic components as well as test centres and research institutes.

TIRA GmbH
Eisfelder Straße 23/25
D 96528 Schalkau
Web: www.tira-gmbh.de
Tel.: +49 (0) 36766 280 - 0
Fax: +49 (0) 36766 280 - 99
E-Mail: info@tira-gmbh.de

Andreas Zehner
Tel. +49 (0) 36766 280 20
E-Mail: andreas.zehner@tira-gmh.de

This release was published on openPR.