Sound absorbing body, sound absorbing structural body, and method of manufacturing these bodies
First Claim
1. A sound absorbing body comprising a molded body including two unexpanded layers and an expanded layer with a number of voids and held between these unexpanded layers, wherein a plurality of holes each of a depth that passes through one of the unexpanded layers and do not reach the other one of the unexpanded layers are formed at any positions of the molded body, and a cross-sectional area of the hole is in the range from 0.785 to 314 mm2 and the pitch is 1 mm or more.
4 Assignments
0 Petitions
Accused Products
Abstract
A sound absorbing body 40 has a molded body 44 including two unexpanded layers 41, 42 and an expanded layer 43 having a number of voids and held between these unexpanded layers 41, 42, a plurality of holes 41A of a depth that passes through the unexpanded layer 41 and does not reach the other unexpanded layer 42 are formed at any positions on the molded body 44, a cross-sectional area of the hole 41A is in the range from 0.785 to 314 mm2, and the pitch is 1 mm or larger. Laminating a plurality of materials is not required, and both the sound absorbing capability and sound insulating capability can be secured by integral molding, and further, only unpleasant sounds can selectively be absorbed.
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Citations
13 Claims
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1. A sound absorbing body comprising a molded body including two unexpanded layers and an expanded layer with a number of voids and held between these unexpanded layers,
wherein a plurality of holes each of a depth that passes through one of the unexpanded layers and do not reach the other one of the unexpanded layers are formed at any positions of the molded body, and a cross-sectional area of the hole is in the range from 0.785 to 314 mm2 and the pitch is 1 mm or more.
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9. A method of manufacturing a sound absorbing body comprising the steps of:
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molding a formed body comprising two unexpanded layers and an expanded layer having a number of voids therein and held between these unexpanded layers with a die having a movable die capable of moving forward to and backward from an internal cavity by melting fiber-containing thermoplastic resin containing reinforcing fiber pieces each with the length adjusted within a range from 2 to 100 mm and injecting the melted resin into the cavity of the die, and then moving backward the movable die to expand the cavity for forming voids in the fiber-containing thermoplastic resin; and
forming a plurality of holes of a depth that passes through one of the unexpanded layers and does not reach the other one of the unexpanded layers at any positions of the molded body, wherein a cross-sectional area of the hole is in the range from 0.785 to 314 mm2 and the pitch is 1 mm or larger. - View Dependent Claims (11, 12, 13)
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10. A method of manufacturing a sound absorbing body comprising the step of:
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molding a molded body comprising two unexpanded layers and an expanded layer having a number of voids therein and held between these unexpanded layers with a die comprising a movable die having a plurality of cavity forming surfaces capable of moving forward to and backward from an internal cavity by melting fiber-containing thermoplastic resin containing reinforcing fiber pieces each with the length adjusted within a range from 2 to 100 mm and injecting the melted resin into the cavity of the die, and then moving backward the movable die to expand the cavity for forming voids in the fiber-containing thermoplastic resin and also forming a region having a different expansion ratio from that of the peripheral area in sections corresponding to the cavity forming surfaces of the unexpanded layers; and
forming a plurality of holes of a depth that passes through one of the unexpanded layers and does not reach the other one of the unexpanded layers at any positions of the molded body, wherein a cross-sectional area of the hole is in the range from 0.785 to 314 mm2 and the pitch is 1 mm or larger.
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Specification