The whole machine is in sheet plate welded structure, with enough strength and rigidity. The structure of 4 vertical shaft and 4 oil cylinders is adopted, to alleviate the stress of synchronous tension bar for a uniform pressure during operation, to ensure the operating precision of machine tool and the precision of the workpiece, and to enhance the service life of machine, with free adjustment of stroke for the gliding block, as well as stable and reliable mechnical stopper and synchronized tension bar. Electric mode is applied for rear stopper, able for separate adjustments, fitted with digital display and ine-tuning device, easy and quick for regulation.