US1792505A - Cutting element - Google Patents

Description

Feb. 17, 1931.

v c. w. NOBLE ATTORNEY Patented Feb. .17, 1931 UNITED S ATES" PATENT OFFICE CLARENCE W. NOBLE, OF HOOSIGK FALLS, NEW YORK, ASSIGNOR TO THE NOBLE AND WOOD MACHINE 00., OF HOOSICK FALLS, NEW YORK, A CORPORATION OF NEW YORK CUTTING ELEMENT Application filed October 24, 1929. Serial No. 402,191.

My invention relates to the so-called cutting elements employed in the various machines used in the process of paper making. It refers particularly to the cutting elements used in beating engines and similar devices such as mixing, breaking, pulping and bleaching engines, and also to those elements as used in refining engines and the like.

In a beating engine, for example, the bed plate comprises a plurality of so-called cutting elements which, however, have dull edges and may be steel plates about one-quarter inch in thiclmess. Rotatively mounted over the bed plate is the beater roll which is provided with a plurality of similar cutting ele-' ments arranged about the periphery thereof, and which is supported in vertically adjustable bearings so that the distance between the cutting elements in the beater roll and those in the bed plate may be varied.

The roll is turned from a suitable source of power and the fibers in the material being treated are separated, and brushed, broomed or drawn out by repeated passage between the roll and plate.

These cutting elements are constantly subjected not only to the corrosive action of water but also to that of the various chemicals used in the process. Furthermore, because the machines run constantly in one direction, the elements become worn on one side so that the edges, instead of remaining dull and square, become rounded and comparatively sharp. In this condition they are. more readily susceptible to erosion and corrosion and soon become so rough and uneven that replacement is necessary. Moreover, particles of metal are carried into the stock and cause spots in the finished paper. I

Entirely aside from the fact that the present type of element is susceptible to rust and rapid disintegration, the particular way in which it wears soon renders it extremely ineflicient if not entirely unfit for use in the manufacture of the better grades'of paper. What is desired, is a cutting element which will hold a substantially square, dull edge so that it will brush, comb or draw out the fibers rather than cut them.

In my copending application, Serial No.

242,913 I have disclosed cutting elements which are much harder in their marginal portions than in the interior and hence will maintain substantially square, dull edges. This application is in the nature of a continuation of my application aforesaid and its objects are to provide a cutting element of' the character described which will be s bstantially rustless and which will be higlily resistant to erosion. Another object is to provide an element which 'willv wear slowly in such a way as to maintain the cutting edge substantially square and dull. A. further object is to provide an element in which the central portion of the cutting edge will wear at a somewhat more rapid rate than the outer portions so that the .cutting edge will be slightly concave.

In attaining these objects I follow the general procedure outlined in my application aforesaid. Thatis, I provide a cutting element in which the outer portions are very much harder than the interior or body por-- tions although I obtain this result by a somewhat difi'erent means and method of procedure than that set forth in my application, Serial No. 242,913. Referring to the draWings- Fig. 1 is a fragmentary perspective view them more or less fit for the purpose intended. The elements now in practical use are substantially homogeneous throughout although it has been proposed to weld relatively thick lates of iron to the sides of a steel core an .thus form a composite beater bar having a surface ofifering a higher resistance to corrosion than ordinary steel.

My invention proceeds upon the general principle of constructing these elements of steel or iron containing, as alloying ingredients, certain elements, such, for example,

as aluminum, adapting the material to be Carbon' 0.36 Manganese 0.51 Silicon -L 0.27 Chromium 1.49 Aluminum 1.23 Molybdenum 0.18 Phosphorus l 0.013% Sulphur 0.010% Balance Iron.

Depending upon the character of the heat treatment such an alloy may have a maximum strength varying from 224,000 pounds to 95,000 pounds with an elongation percentage in 2 inches of from 11 to 30, and an initial Brinell hardness of from 445 to 186. The above allo when quenched in oil from 1650 F. and rawn at 1000 F. provides a very satisfactory steel, and when so treated will have an initial hardness of about 364 Brinell.

Cutting elements formed of such material are then subjected to the action of nitrogen as disclosed in the aforesaid Fry patent. This treatment produces in the surface ortions of the element a thin casing (a out 0.03 inches deep) of extreme hardness. The degree of hardness produced is far beyond the range of the Brinell ball but when tested by other means and converted into Brinell terms will be between 900 and 1100 Brinell. In addition to its extreme hardness this nitrided surface is much more resistant to corrosion than the untreated material.

Referring more particularly to the drawings, 1 represents a fragmentary portion of the present t pe of element illustrating how the edge, 2, ecomes worn with use. When new, the cutting edge of the element is substantially as shown by the dotted outline, 3, and it is highly desirable for reasons above mentioned that the cutting edge be maintained substantiall square across and dull, rather than curve and sharp as shown in Fig. 3. Referring to Fig. 1, 4 represents a. fragmentary portion of a cutting element enclosed in a nitrided case, 5, the hardness of this case is, of course, greatest at the surface and uniformly decreases until the nor- 'mal interior hardness of the bar is reached at a depth of between 0.03 and 050$ inch.

In Fig. 2 I have shown a pair of coacting elements, 6 and 7. The element, 6, might, for example, represent one of the cutting elements in the beater roll and the element, 7,

a similar element in the bed plate. The extreme hardness of the nitrided case, 5, prevents the bar from wearing as shown in Fig. 3 and the cutting edges are maintained substantially s uare and dull as shown in Fig. 2 although, ecause of the great differences in hardness between interior of the bar and the surface portions thereof the cutting edge tends to wear slightly concave as shown at 8. This is deemed to be quite an advantage because it gives the fibers an opportunity to turn in passing between the extreme edges of the coacting elements.

While I have described my invention in its preferred embodiment it is to be understood that the words which I have used are words of description rather than of limitation and that the drawings are merely illustrative. Hence changes, within the purview of the appended claims, may be made without departing from the true scope and spirit of my invention.

What I-claim is 1. A cutting element of the character described for use in paper making machinery and comprising a bar of alloyed metals having a nitrided case of extreme hardness.

2.- A cutting element of the character described for use in paper making machinery and comprising a bar of alloyed metals having in its marginal layers a nitrided case of extreme hardness.

3. A cutting element of the character described for use in paper making machinery and comprising a bar of alloyed steel having a nitrided case of extreme hardness.

4. A cutting element of the character described for use in paper making machinery and comprising a bar of alloyed steel having in its marginal layers a nitrided case of extreme hardness.

5. -A cutting element of the character described, for use in paper making machinery and comprising a bar of metal alloyed with a metal adapting said bar to be nitrided, and having in its marginal layers, a nitrided case of extreme hardness.

6 A cutting element of the character de scrlbed for use in aper making machinery and comprising a Bar of steel alloyed with a metal adapting it to be nitrided, andhavmg m its mar 1nal layers, a nitrided case of extreme har ness.

7. A cutting element of the character described for use in paper making machinery and comp'risin a bar of metal containing elements adaptlng it to be nitrided, and having in its marginal layers, a nitrided case of extreme hardness.

8 A cutting element of the character described for use in a paper making machine and comprising a metal bar characterized by nitrided side surface portions ofextreme hardness.

9. In a paper making machine, a cutting element comprising a bar of alloyed metals having nitrided extreme side portions thereof of a greater degree of hardness than the interior portions. a 10. In a paper making machine, a cutting 1 1 element comprising a bar of alloyed steel havingnitrided extreme side portions thereof of a greater degree of hardness than the interior portions.

11.; In a paper making machine, a cutting element comprising a bar of alloyed metals having a nitrided extreme side portion thereof of a greater degree of hardness than the interior portion.

12. In a paper making machine, a cutting element comprising a bar of alloyed steel having a nitrided extreme side ortion thereof of a greater degree of bar ess than the interior portion. 13. A cutting element of the character described for use in paper making machinery and comprising a bar of metal containing elements adaptmg it to be nitrided, and having nitrided side portions of extreme hardness.

CLARENCE W. NOBLE.

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