The Design And Study On A New-type Of High Density Screed Unit

Screed unit is the core working device of asphalt paver, which consisting of tamper mechanism and vibrator mechanism. It has an impact of pre-compaction, vibrating compaction and leveling on the asphalt mixture. Double tamper and single vibrator are commonly used in traditional screed unit. But in this kind of working mechanism, tamper beam’s inertial force and vibrator’s horizontal component force would bring additional vibration to the body of screed unit. Besides, the inertial force would also affect quality of vibrating compaction. A new- type of high density screed has been presented in the paper, which would reduce those force’s negative influence on screed unit.First, structure and working theory of traditional screed unit are studied. The cause of tamper beam’s inertial force and vibrator’s horizontal component force and influence they have on working stability of screed unit are analysed. After that, a new-type screed unit is put forward. In the new screed unit, the shaft of tamper mechanism is replaced by hydraulic impactor and double temper is replaced by single temper. The shaft of vibrator is replaced by two shafts with same eccentricity and eccentric mass. Working theory and characteristic of the new screed unit are introduced. The new structure’s improvement on tamper beam’s inertial force and vibrator’s horizontal component force is analysed and dynamics model is built. Second, virtual machine is built by means of 3D modeling software Pro/Engineer and dynamics simulation is completed by software ADAMS. Feasibility of design proposal is validated by comparing and analysing the simulation result. Finally, influence of the rod and screed plate on rigidity of the whole screed unit is studied by simulation software ANSYS Workbench and the rod’s position and plate’s width and thickness are confirmed. Thus, optimal design of the whole new-type screed unit is completed.