| 摘要 |
PROBLEM TO BE SOLVED: To remarkably improve Z direction precision, increase rigidity, and make it hard for clearance to be generated when an impulsive force is applied, by mutually moving a fine Z movement cylinder and a fineθrotation case in parallel, via a ball bearing row and a square pillar type sliding member. SOLUTION: A retainer wherein square pillar type sliding members and ball bearing raw are alternately arranged is interposed, and a fine Z movement cylinder 8 is inserted in the hollow part of a fineθrotation case 7. Four first rectangular trenches are formed on the outer side surface of the fine Z movement cylinder 8. Four second rectangular trenches are formed on the inner side surface of theθfine rotation case 7. The first trenches and the second trenches are made to face each other, and form square pillar type spaces, in which the square pillar type sliding members are positioned. Four surfaces of each square pillar type sliding member come into plane contact with one plane of the first rectangular trench and one plane of the second rectangular trench and slide. A ball bearing row is positioned between the outer side surface of the fine Z movement cylinder 8 and the inner side surface of the fineθrotation case.
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