AIR PERMEABILITY MEASURING INSTRUMENT FOR POROUS SHEET AND AIR PERMEABILITY CONTROLLER FOR POROUS SHEET MANUFACTURING APPARATUS USING THE SAME

PURPOSE:To improve a quality by continuously measuring an air permeability in the flow direction of a sheet and, if necessary, in the direction of its width, rapidly controlling the air permeability and controlling the air permeability of the sheet flowing through a manufacturing apparatus. CONSTITUTION:An air permeability measuring instrument is composed of a suction box 1 provided with several slit-shaped suction openings 3 in the direction of the width of a sheet 2 and a pressure gate M mounted to a piping 4 communicating with a vacuum pump P. Then, the box 1 is arranged, for example, downstream of the hot press rolls 7, 7 of a transfer mechanism 6 for the nonwoven fabric sheet 2. A relationship between a suction pressure and an air permeability under a prescribed reduced pressure is obtained for a variety of the sheets in advance, the suction pressure is compared with the measured one, a flow direction is adjusted by adjusting the pressing degree of the hot press rolls 7 by a manual operation or the like and the pressing degree in the width direction is adjusted by the lateral balance of the rolls 7. Thus, a quality can be improved, a manufacturing cost can be reduced and a production efficiency can be improved.