Abstract:In order to obtain the high quality of large -diameter and thin -wall bend, the bending of pipes can be realized by the intermediate frequency induction heating the hydraulic push -bending style pipe bender, but the ultra -low and constant speed control in the push -bending style pipe bender is one of the key technical problems for assuring the quality of large -diameter and thin -wall bend. Based on the analysis of the creeping phenomenon for hydraulic cylinder, started from the actual working condition, the ultra -low and constant speed control of the system was realized by using the digital hydraulic control technology to avoid the low speed creeping phenomenon in bending process. The result proves that the system can ensure low speed stability of the hydraulic cylinder, and avoid the phenomenon of vibration and curved wrinkle during the bending process, so it is easy to be used in engineering practice.