| 摘要 |
PROBLEM TO BE SOLVED: To prevent the bending of bristles or bristle bundles in a cavity by injection pressure at the time of injection molding even not only when the cross-sections of the bristle bundles are large but also when the cross-sections of the bristle bundles are small and even when the bristles are embedded by one piece each. SOLUTION: Metal molds for injection molding comprise a stationary side metal mold 1 and a moving side metal mold 2. The bristle bundles 3 are inserted into insertion holes 4a and 4b in the contact state of the stationary side metal mold 1 and the moving side metal mold 2 and thereafter, the moving side metal mold 2 is moved by a prescribed distance L, by which the cavity 5 consisting of the thickness corresponding to a bristle support 10 is formed between the stationary side metal mold 1 and the moving side metal mold 2. A melt 6 of, for example, a thermoplastic synthetic resin is packed into the cavity 5 and after the bristle support 10 is injection molded, the ends of the bristle bundles 3 projecting from the rear surface side of the bristle support 10 are melted to form melt fatten parts 8 on the rear surface of the bristle support 10. Further, the melt fatten parts 8 are pressurized and shaped by a shaping plate 9 at need and are welded to the rear surface of the bristle support 10 simultaneously with the shaping.
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