Error Factors in Vertical Positioning System

Machine tools are improved capacity remarkably during the 20th century. Improving the precision of machine tools are related with precision of products and accurate processing is always associated with the subject of interest. There are a lot of the elements that determine the precision of the machine, as guides, motors, structure, control, etc. In this paper we focused on the phenomenon that vertical movement system has worse precision than horizontal movement system even they were made up with same components. The vertical movement system needs to be studied differently from the horizontal movement system to develop its precision. The vertical movement system has load on its transfer direction and it makes the movement system weak in precision than the horizontal one. Some machines have mechanical counter balance, hydraulic or pneumatic counter balance to compensate the weight of the machine head. And there is several type of compensating the weight. It can push the machine head and also can use chain or wire lope to transfer the compensating force from counter balance to machine head. According to the type of compensating, there could be error from friction, pressure error of hydraulic or pressure control error. Also according to what to use for transferring the compensating force, transfer error of compensating force could be occur.

• Hyun-Gwang Cho
• Wan-Seok Yang
• Su-Jin Kim
• Jeong-Seok Oh
• Chun-Hong Park

• Chain chordal action
• counter balance
• setup error
• vertical positioning system.

[1] S. W. Lee, H. Z. Choi, S. W. Hwangbo, D. J. Kim, 2000, "A Study on
Optimal Design of Perpendicular Guideway Mechanism", Korean Society
for Precision Engineering spring conference, pp. 982-986.
[2] C. Raksiri, M. Panichkun "Geometric an force errors compensation in a
3-axis CNC milling machine", Int. J. Mach Tools Manuf. Vol. 44, 2004,
pp. 1283-1291
[3] I.W Yeo, C.W Park, S.J Lee, 1996 ,"A study on Optimal Design of
perpendicular Guide way Mechanism", Proceeding of KSMT Spring
Conference, pp. 641-645
[4] G. C. White, Y. S. Xu, 1994, vol. 43, "An Active Vertical-Direction
Gravity Compensation System", IEE transactions on instrumentation and
measurement, pp. 786 ~ 792
[5] S. Y. Lin, Y. C. Fang, C. W. Huang, 2008, "Improvement strategy for
machine tool vibration induced from the movement of a counterweight
during machining process", Int. J. Mach Tools Manuf, vol. 48, pp.
870-877.
[6] M.H Tsai, M.C Shih, 2006, vol. 49, "A Study of the Pneumatic
Counterweight of Machine Tools Conventional and Active Pressure
Control Method", JSME Int. Journal, Series C, pp. 890-896.
[7] I. H. Song, J. H. Choi, H. S. Ryu, D. S. Bae, 2003, "Nonlinear Dynamic
Modeling and analysis of Automative Silent Chain Drive", The Korean
Society of Automotive Engineers autom conference, pp. 1067-1072.