| 摘要 |
<p>At least one of the two opposed areas (4, 8) is shaped such that when the plate (1) is not stressed, the front and rear zones (13, 14) rest against the support surface (6). A central region (15) is out of contact. The hold-down force (FN) of the clamping assembly (5) acts in the non- contacting zone (15). One or more of the surfaces (4, 8) has convex contour (K) in the central zone (15). The convexity corresponds with the line of plate flexure under the influence of pressure (FD) and the hold-down force (FN). In the non-contacting zone, the plate clamping assembly is spring-loaded. The hold-down clamp exerts force such that the clearance (A) between surfaces (4, 8) in the non-contacting zone is very small, preferably tending to zero. The spring-loading forces exerted, exceed those acting on the plate as a result of normal head box operation. The clamping assembly (5) comprises a pack (16) of dished spring washers located in plate recesses (17). The spring washers (18) are held in a cup with a machine screw (21) and nut (20) applying compression to the assembly. Overall height is up to 25 mm, preferably up to 20 mm. The cavity (25) in the central zone, is filled with soft material. Plate width exceeds 5 mm, and preferably exceeds 8 mm.</p> |
