Application of Alternative Support Fixture System in Vibration Suppression of Thin-Walled Parts

Abstract: Flexible fixture system is widely used in the machining of thin-walled parts, which can effectively suppress the machining vibration of thin-walled parts. The traditional flexible fixture system usually adopts the way of multi-point flexible support. Its basic idea is to use the form of lattice to approximate the actual envelope of thin-walled parts. This method can meet the vibration suppression requirements of different thin-walled parts, but it also has certain defects. Since the fixture system uses too many supporting heads, the control of the system becomes more difficult. In addition, the supporting heads are constrained by the size of the autogenous structure, the motor and the rack, so it is difficult to ensure that the supporting heads in the fixture system have a high arrangement density, resulting in the lack of rigidity in the actual machining position of the thin-walled parts, which is easy to produce vibration. To solve this problem, this paper proposes a new alternative support fixture system for vibration suppression of thin-walled parts. The system includes two supporting heads which support the area near the milling point on the thin-walled part. during the processing, the two supporting heads will move with the cutter in the form of alternating support, so as to improve the local machining rigidity of the thin-walled part. A dynamic model of the new cutter- supporting head- workpiece system is established to analyze the workpiece vibration. In this paper, a thin plate with four sides simply supported is taken as an example to numerically analyze the effects of the supporting head’s location, stiffness coefficient and damping coefficient on vibration suppression. The results indicate that the machining vibration of the thin plate with support is significantly suppressed compared with that without support. The vibration amplitude of the thin plate can be reduced by increasing the stiffness coefficient and damping coefficient of the supporting head. Considering that the stiffness coefficient and damping coefficient of the supporting head cannot be increased infinitely in the actual processing process, the selection of the stiffness coefficient and damping coefficient of the supporting head in the design should be as large as possible within a reasonable range. The position of the supporting head should be selected within the effective support distance. Increasing the stiffness coefficient or damping coefficient can increase the value of the effective support distance. When the position of the support head is outside the effective support distance, the change of the stiffness coefficient or damping coefficient will not play an important role in the vibration suppression of the thin plate. The analysis results can improve the theoretical basis for the design of the alternative support fixture system.

Keywords: thin-walled parts; vibration suppression; alternative support fixture