US117319A - Improvement in furnace-grates - Google Patents

Description

heat to which they are to be subjected.

CALVIN M. Nonrnnnr, or Nnvv YORK, N. Y.

IMPROVEMENT IN FURNACE-GRATES.

Specication forming part of Letters Patent No. 117,319, dated July 25, 1871.

To all whom it may concern:

Be it known that I, CALvIN M. NORTHRUP, of the city and State of New York, have invented certain Improvements in the Uonstruc` tion of Grates for Furnaces of Steam-Boilers,- &c., of which the following is a speciication:

My invention, briefly, consists in combining in a grate, for the uses above mentioned, alternate straight and corrugated bars, and tie-bolting77 a series of such bars together, i'or advantages and reasons set forth hereinafter.

As I tie-bolt my grate-bars, necessarily, to accomplish my object in the construction of the grate, as presently to be descibed, I dispense with the lugs or projections that are usually cast on the sides of grate-bars, and, in so far as relates to the bar itself, save metal and do not impede the draught; and the tie-bolts and thimbles binding the bars in position will ontlast several sets oi' grate-bars, and can bc many times used.

As above stated, I use in my compound grate an alternation of fiat-sided bars and corrugated bars, and in different furnaces, according to size, length oi' bars wanted, and the intensity of the I may alternate the different styles of bars in pairs or in relatively odd numbers.

rlhe flat-sided bar that I prefer to use is represented byv A, Figure l, on the accompanying drawing, that igure representing a cross-section (of a section) of grate on `my plan, cutting through one of the tie-bolts, and the rings or thimbles b fitted loosely on the tie-bolts c c, and abutting against the bars between which they are interposed, to hold the bars apart at distances corresponding to the width and number oi'thimbles so interposed, to suit the nature oi' fuel (size of coal, for instance) to be used on the given grate. Fig. 2 is a plan View corresponding to Fig. 1. On Fig. 1 one of the flat-sided bars A and one oi' the corrugated bars B are section-lined 5 also a couple or' the thimbles between them, b. For my use in my improved grate I extend the concaves oi' the corrugated bar to the top edge ofthe bar, and similarly extend the line of the convex of each corrugationstraight to the top of the bar, the bottom line being waved or corrugated its entire length. Thus in this corrugated bar there is no rib, strict- 1y termed, but the corrugations blend into and constitute a characteristic of the bar as a simple whole. Fig. 3 is intended to represent a side view of a corrugated bar (broken in two) with the convolutions carried up to the top, as stated, and cast with the holes below the iirefsurface to receive the tie-bolts through the bar at corresponding distances from each end. In extra long bars I would put a tie-bolt, as (l G, Figs. l and 2, through the middle of the set. I

The plain grate-bars in common use, having dat sides and tapering downward on an acute angle when warped, or buckled upward when heated7 do not shrink back to their normal level on cooling; but a grate-bar corrugated as described, when expanded by the heat yields, in a sense, as a spring 5 and being also the thinnest at the bottom portion where it is least exposed to the heat, this portion especially, I may say, springs back, drawing the upper surface of all the bars while cooling to their original level. 0n the other hand, plain nat-sided bars of a given length and depth require less metal for a given vertical strength than a bar with a corrugated lower portion 5 yet my corrugated bar is lighter and stronger than any other form of corrugated bar known to me, and saves metal without sacricing strength to lightness.

For the above reasons I employ, alternate with the plain bar, as A, Fig. 1, the corrugated bar, as described, (see B, same figure 5) and the corrugated bars,bein g tie-bolted together with the plain bars in certain alternation, restrain the greater buckling tendency ofthe latter, and draw them back, while cooling, to their proper level, while the plain bars reduce the total cost of the grate and enhance its general strength.

By the use of the sectional thimbles b between the bars I can, by the adding or removal of one or more, correspondingly widen or decrease the draught-space between them, as will be readily understood, and thereby fit the same grate for the use of different qualities of fuel 5 and the saine size of pattern of bars can thus be used to cast any number of bars with different openings, if oi' the same length, whereas now a pattern is required for every set of bars to be of different openings between.

I may add that the bars of my grate being tie-bolted together render it particularly adapted for furnaces in which agitated or dumpinggrates are required.

The corrugated bar is less liable to warp when corrugated (transversely of its length) nearly or quite to its top than when the flange alone is corrugated. The tie-bolts and rings hold these bars firmly in position, and further tend to prevent their warping or springing laterally or Vertically, and easily allow a bar to be added or removed froin the set or changed for another bar.

The bolts and thirnbles being entirely below the {ire-surface tend to keep the tops of the bars cool, by allowing freer access of air or draught, and freer access for raking than when lugs are carried up to the fire-surface.

What I claim is- Witnesses:

WM. MONT STORM, FRANCIS G. BARTLETT.

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