| 摘要 |
This upper plate biasing unit is provided with a lower plate (24), an upper plate (17) biased above the lower plate (24) so as to be capable of freely moving vertically, a guide member (19) mounted on the upper plate (17) and adapted to guide the vertical movement of the upper plate (17), and a spring (20) provided below the guide member (19) and adapted to bias the upper plate (17) upwards via the guide member (19). An insertion hole (29) having sufficient size for the spring (20) and the guide member (19) to be inserted vertically is formed on the lower plate (24). A spring reception member (28) for receiving the spring (20) is detachably provided to the insertion hole (29). This configuration makes it possible to inhibit the upper plate (17) from being warped by the biasing force from the spring (20) and to replace the upper plate (17) easily and swiftly. |
