초록 ▼

Sound attenuating composite articles and methods of making same are provided. Sound attenuating composite article include first, second and/or third and/or fourth layers of material. The first layer of material may be either an acoustic fiber batting and/or an acoustic foam material and may be an el

Sound attenuating composite articles and methods of making same are provided. Sound attenuating composite article include first, second and/or third and/or fourth layers of material. The first layer of material may be either an acoustic fiber batting and/or an acoustic foam material and may be an elastic or inelastic material. The second layer of material is a thermoplastic material that is fused to a surface of the first layer of material. The third layer of material is a thermoplastic material that is fused to a surface of the second layer of material. The fourth layer of material is a woven or non-woven mixture of fibers, such as scrim material, that is attached to a surface of the third layer of material. Selected portions of the sound attenuating composite article are heated and then compressed (referred to as "tuned") so as to have an acoustic impedance that is greater than an acoustic impedance of adjacent portions.

대표청구항 ▼

Sound attenuating composite articles and methods of making same are provided. Sound attenuating composite article include first, second and/or third and/or fourth layers of material. The first layer of material may be either an acoustic fiber batting and/or an acoustic foam material and may be an el

Sound attenuating composite articles and methods of making same are provided. Sound attenuating composite article include first, second and/or third and/or fourth layers of material. The first layer of material may be either an acoustic fiber batting and/or an acoustic foam material and may be an elastic or inelastic material. The second layer of material is a thermoplastic material that is fused to a surface of the first layer of material. The third layer of material is a thermoplastic material that is fused to a surface of the second layer of material. The fourth layer of material is a woven or non-woven mixture of fibers, such as scrim material, that is attached to a surface of the third layer of material. Selected portions of the sound attenuating composite article are heated and then compressed (referred to as "tuned") so as to have an acoustic impedance that is greater than an acoustic impedance of adjacent portions. . 19. The bi-center drill bit as defined in claim 14 wherein a radially outermost surface of each of the reaming blades extends at most to a radially least extensive one, with respect to the longitudinal axis, of a pass-through circle and a drill circle, the drill circle substantially coaxial with the longitudinal axis, the pass-through circle axially offset from the drill circle and defining an arcuate section wherein the pass-through circle extends laterally from the longitudinal axis past a radius of the drill circle, so that radially outermost cuffing elements disposed on the reaming blades drill a hole having a drill diameter substantially twice a maximum lateral extension of the reaming blades from the longitudinal axis while substantially avoiding wall contact along an opening having a diameter of the pass through circle. 20. The bi-center drill bit as defined in claim 14 wherein at least one jet disposed proximate to the reaming blades is oriented so that its axis is within approximately 30 degrees of a line normal to the longitudinal axis of said bit. 21. The bi-center drill bit as defined in claim 14 wherein at least one jet disposed proximate to the reaming blades is oriented so that its axis is within approxi