| 摘要 |
<p>801,238. Suction rolls of paper-making machines &c. NATIONAL RESEARCH COUNCIL. May 29, 1956 [June 2, 1955], No. "16534/56. Drawings to Specification. Class 96. To-minimize the noise of a suction roll of a paper-making machine &c., the holes are arranged in a regularly recurring pattern of generally axial rows and generally circumferential columns with each row disposed along a line inclined to the axial direction of the roll, the inclination being such as to represent a value of Az lying within a range equivalent to approximately 1 to approximately 6 radians having regard to any differences between the chosen values of the variables and values given in an example in the Specification, where z is a parameter equal to the basic phase shift of adjacent columns divided by lid where K= 2#/#, dαis the spacing between the centres of adjacent holes of each row, # is the wavelength, and #αis the difference betweenα<SP>0</SP> and each particular value that the phase shift may take at any time. The basic pattern and values chosen may be such as to attenuate substantially all frequencies from the fundamental to the highest objectionable harmonic. Such attenuation may be at least 20 decibels. Alternatively, the angles of the sealing strips within the roll may be inclined instead of inclining the rows of holes.</p> |
