US1803924A - Laminated doctor - Google Patents

Description

' May 5,1931. VEDD g 1,803,924

LAMINATED DOCTOR Filed April 2, 1928 JJ/zzz War-re)? We Ede Patented May 5, 1931 UNITED STATES PATENT OFFICE JOHN WARREN VEDDER, OF WORCESTER, MASSACHUSETTS, ASSIGNOR TO RICE, BARTON & FALES, INCORPORATED, OF WORCESTER, MASSACHUSETTS,

MASSACHUSETTS A CORPORATION OF- LAMINATED DOCTOR Application filed April 2, 1928. Serial No. 266,618.

This invention relates to doctors for calenders, dryers or other rolls. Its object is to provide a doctor of a flexible nature with means whereby the edge of the doctor blade in contact with the roll will be suiiiciently flexible longitudinally but not materially so transversely.

Reference is to be had to the accompanying drawing which is a transverse sectional perspective view of a doctor showing a preferred form of this invention.

It is desirable to so construct the doctor blade in contact with the roll, that it will have sufiicient longitudinalflexibility to so conform its edge as to accommodate itself to any unevenness in the surface of the roll. However, flexibility in the transverse direction is undesirable. In a doctor which is flexibleboth longitudinally and transversely,

pressure on the doctor causes the blade to turn u on an axis parallel with the roll, and rovi es awedge shaped recess at the end of the blade wherein paper, grit, etc. tends to force itself and cause the doctor to be ineffective. The grit will get into this wedgeshaped recess and score the roll, causing considerable damage. I

My invention comprises a flexible blade formed in laminated sections so that its edge will be longitudinally flexible but will be prevented from bending transversely to such a degree as to permit said recess to be formed. 7

In the drawing I have shown the invention as applied to a rigid doctor back 10 which is ample ed in connection with the usual roll 11. T is doctor back has a portion projecting toward the roll, preferably above the center thereof. On this back is mounted, by screws or the like 12, the doctor blade. This is made up of a series of flexible leaves 13 and 14, each of which is adapted to engage the surface of the one below it along a line at a short distance from its edge. Thus the blade isbacked up to prevent its operative edge bending upwardly far enough to provide a wedge shaped recess at its end where it touches the roll 11.

Although it will be seen that this blade is flexible, its flexibility operates only in the comparatively narrow space between the edge of the leaves 13 and the roll. It is free to yield beyond that edge but is held down at a plurality of points at a distance from the doctor back and along lines parallel with the roll and progressively farther away from it.

In this way it will be seen that while the flexibility of the blade is taken advantage of to hold the blade against the roll and allow the blade to bend slightly all along its. edge to accommodate any irregularities in the surface of the roll, it is held from any material transverse bending by its successive leaves.

This provides for the flexibility of the blade in a lengthwise direction and allows for the blade to accommodate itself perfectly to any unevenness of the roll. At the same time it avoids material flexibility in a transverse direction. The backing up of the blade by the upper leaves causes it to act practically as a rigid blade as far as transverse bending is concerned, although made of flexible material.

It will be noted that the blade '14, in the embodiment shown is unsupported from below except by the rigid member 10, the leaves 13 all operating on the upper side of the blade 14.- It is to be understood that the terms upper and below are but relative and that if the roll- 11 is reversed and the doctor accordingly turned about that such arrangement is contemplated by the presentinvention. 85

Although I have illustrated and described only one form of theinvention I am aware of the fact that modifications can be made therein without departing from the scope of the invention as expressed in the claims.

Therefore I do not wish'to be limited in this respect but what I do claim is 2-- 1. A doctor for the urposes described comprising a flexible bla e mounted at a distance from its point of contact with the sur- 95 face which it engages and made up of a series of flexible leaves, each bearing on the one below alon a line at a short distance from the edge t ereof and parallel therewith to prevent the blade from bendingf or getting out 100 of position along that line and also prevent enough transverse flexibility to cause the hpper edge of the doctor to become spaced ffrom the roll at any point. i 2. A doctor for the purposes described, comprising two separate flexible leaves, a rigid support by which said leaves are carried, the lower leaf projecting beyond the edge of the support and unsupported from below beyond said edge, the upper leaf projecting beyond said edge and its edge engaging the lower leaf along a line parallel to the operative edge of the lower leaf and said edge of the support and at a material distance from both. i

3. A doctor for the purposes described, comprisin a flexible blade, a rigid support having a ront edge parallel with the operative edge of the blade, said blade being se- 29 cured to said support, projecting beyond the edge thereof, and unsupported from below beyond the edge of the support, and a series of entirely separate flexible leaves, all secured to the support at their rear edges and each projecting over the one next below to a line part way between the line along which it is secured to the support and the outer edge of the blade or leaf next below. w 4. A doctor for the purposes described, 39 comprising a flexible blade, a rigid support therefor beyond the edge of which the blade projects, and a spring leaf secured along one edge to said support and projecting over and engaging said blade along an area which 35 is unsupported directly by said support, said leaf being free from the blade.

In testimony whereof I have hereunto affixed my signature.

40 JOHN WARREN VEDDER.

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