Installation for quenching of the guidances sliding bars of machines tools

This summer, UTTIS has installed and commissioned an installation for quenching of linear guideways for a Swiss company. Until now, the client had installed either discontinuous (chamber furnaces, oil quenching press, tempering pit furnace) or continuous (quenching belt furnace, quenching in air, then transfer to the tempering belt furnace). The installation supplied by UTTIS is based on a new concept of walking beam furnace, quenching in press and then transfer with a robot to the tempering furnace with chains, straightening, then again stress relieving after straightening (see Fig. 1).


Fig.1

The technological process is performed as it follows:
● The austenitizing of the linear guideways is performed in the walking beam furnace, the supply is provided in automatic tact. The linear guideways move step by step and then enter in the forechamber of the walking beam furnace where they are maintained as long as the temperature drops close to the martensitic transformation of the material (this temperature is measured by a thermographic camera). Afterwards it is transferred to the quenching press. The protective atmosphere used for austenitizing has a carbon percentage of 1%.
● The martensitic quenching takes place in the quenching press, this press having double walls cooled by water.
● After quenching, the part is transferred by a robot to the tempering furnace.
● From the tempering furnace, the part is taken for straightening (if necessary) and then it is stress relieved in the furnace.

The installation has a process computer that monitors the entrance and evacuation of the charge in / from the installation and a charge protocol (ncluding heat treatment parameters and hardnesses) is issued. On this computer, the alarms that might occur during the process are enclosed together with the corresponding explanations.

The main advantage of this installation is the automatic operation with perfect reproducible results; the decarburizing of the parts was avoided and the deformations after quenching where much lower than those obtained with conventional process. Therefore, the installation benefits of lower mechanical processing additions, lower mechanical processing and material costs and also a significant increase of the quality and process reproducibility.