| 摘要 |
PROBLEM TO BE SOLVED: To prevent a PU carriage from skipping over a tooth even in the case of being applied with a strong shock from outside by making a half-nut part of the feed mechanism less in tooth thickness at the end parts than at the center part. SOLUTION: The half-nut part 5C of the pickup carriage feed mechanism has two round teeth 5C1 projecting from an arcuate recessed surface, and those round teeth 5C1 are made different in thickness between the center part and both the end parts of the tooth thickness so that the tooth thicknesses L2 and L3 at both the end parts are less than the tooth thickness L1 of the tooth-width center part. Only the center part of the round tooth 5C1 which has the tooth thickness L1 engages the screw part of a feed screw and neither of both the end parts having the tooth thicknesses L2 and L3 engages the feed screw. Consequently, the round tooth 5C1 is only engaged with the feed screw in point contact, so the engagement area is reduced, so that component precision is needed only for the center part having the tooth thickness L1.
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