| 摘要 |
PURPOSE:To easily and closely fit a writing tip in an inner cylinder and to certainly support the inner cylinder by receiving the inner cylinder in an outer cylinder opened at both ends thereof and integrally connecting the inner and outer cylinders by a plurality of support walls so as to form an air passage communicating in the axial direction between the inner and outer cylinders. CONSTITUTION:An inner cylinder 2 is received in an outer cylinder 1 and integrally connected to the outer cylinder 1 by an appropriate number of the support walls 3 between the outer surfaces of the outer periphery and top part of the inner cylinder 2 and the inner periphery of the outer cylinder 1 and an air passage 4 communicating up and down is formed to the other parts in the axial direction. A cap is integrally molded along with the outer cylinder 1, an inner cylinder and the support walls 3 and the lower end edges 12 of the support walls 3 are positioned above the lower end edge of the inner cylinder 2 and an annular space part 5 is provided to the step part. When a writing shaft is fitted in the lower end of the inner cylinder 2, a sink at the time of molding is generated in this opening part by the shrinkage difference due to the thickness change of the parts of the support walls 3 and other parts not only to prevent the formation of strain deformation around the opening part but also to impart elasticity to the inner cylinder 2. Further, the air passage 4 may be formed by providing unconnected parts to the centers of the support walls 3 of the top part of the inner cylinder 2. |
