| 摘要 |
PROBLEM TO BE SOLVED: To prevent a dust collecting filter from becomig bulky when folded and stacked. SOLUTION: A cylindrical body 3 is composed using filtering material 5 such as paper having gas permeability at least. In the cylindrical body 3, a bellows part 6 is formed in the cylinder expnding direction, the cylindrical body 3 is sealed without folding both side openings to compose a bag body 2, and a support plate 9 provided with a dust collecting port 23 is installed on a suction port of the bag body 2.
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