Automated line for the chamfering, turning and threading of straight prestressed steel bars for high-speed railway line sleepers.
A point of reference
The automated line for bars is a genuine point of reference for major steel mills worldwide, which produce prestressed steel bars for high-speed railway lines, and likewise for some of the most renowned manufacturers of railway sleepers. The line is highly renowned on the market for its high level of automation and impressive production volumes, with a level of repeatability and finishing able to satisfy the highest standards requested by its application.
The prestressed steel bar used in high-speed railway lines is for all intents and purposes a safety component used to construct sleepers in cement. For this reason, the machined bar requires a high-level finish, extremely high precision and indisputable repeatability. To ensure all of this, carefully studied measures have been adopted during all stages of machining, from the transfer of the piece to the chamfering, rolling and threading heads, through to the pre- and post-machining control systems. Since each piece of processing waste has a significant cost, systems have been included to correct, where possible, any non-conformities in the starting bar, thus minimising waste.
The line simultaneously works both ends of the bar and consists of a fixed side and a mobile side, which can be adjusted to suit the length of the product being processed. The chamfering, turning, and threading heads are supplied by a leading world manufacturer. They slide on slides driven by brushless motors, allowing the stroke of the units to be adapted to obtain the desired length, while also correcting any errors detected by the length control.
A clamp mounted on the fixed side blocks the bar and aligns it, while the clamp on the mobile side tensions it. As such, the length of the bar is measured before being processed, preventing possible imprecisions due to any bending typical of bars. The measurement is made by means of an actuator complete with potentiometer. If the detected length falls outside the set tolerance values, the bar is shifted and evacuated without being processed. This control prevents pointless wear of the heads.
Thanks to many decades of experience and development, the bar lines include all possible measures for successful and reliable complex machining.
For bars with length less than 3,200mm. The step-by-step conveyor guarantees the safe and efficient transfer of the piece at a lower cost with respect to the gripper conveyor.
The gripper transfer system is the ideal solution for transferring bars with length greater than 3,200mm.
For efficient blocking of the piece during processing; combined with the ISO40 machining heads by leading world manufacturers, they constitute a further guarantee of precision and repeatability.
The machine is equipped with two measuring stations (one for each end), which check the diameter of the thread in multiple points. The check is made on 100% of the bars, and also allows the plate and roll wear to be checked.
For the evacuation of chips, a suitably sized evacuator is used, complete with a pump to ensure the proper lubrication and cooling of the tools.
A chute located before the piece collection system and after the thread diameter control collects all processing waste (non-conforming length or diameter).
The line produces bars with diameter from 7 to 12.5mm, with maximum thread length 90mm.