| 摘要 |
PURPOSE:To maintain the dimensional accuracy of a lead at a fixed value and cutting down the repair cost so as to reduce the cost by using metallic materials for the heavily worn section caused by a first carbonic plate contacting with a lead, and a ring-shaped member installed in the through hole of a second plate. CONSTITUTION:A first plate 21 is provided with a plurality of through holes 25 which have steps 25a and 25b above and below for setting metallic T-shaped second bar-form members 24. A second plate 28 is arranged right above the first plate 21 and is provided with a plurality of openings 30 for arranging metallic rings 29, etc., on the topside, and also is provided with a through hole 32 for inserting a lead 31 at the center of the opening 30. The lower end of the metallic second bar-form member 24 is retained at the step 25a of the through hole 25 by a metallic spring 27, and the topside of the lower end part accords with the topside of the first plate 21. Therefore, the abrasion by a lead 31 remarkably decreases because the bottom of the lead 31 contacts the metallic second bar member 24. |
