US2130205A - Centrifugal basket - Google Patents

Description

,sept 13, 193s.

J. F. THOLL CENTRIFUGAL BASKET Filed March 19, 1936 2` ,sheets-sheet 1 lllll Hl 'VIH ilu lll oooooooooooll llNvliNToR BY ATTORNEY.; A

Sept. 13, 1938.

J. F. THQLL CENTRIFUGAL BASKET 2 Sheets-Sheet 2 Filed March 19, 1936 NVENTOR ATTORNEY.

Patented Sept. 13, 1938 CENTRIFUGAL BASKET John F. Tholl, Needham, Mass., assigner to American Tool & Machine Co., Hyde Park, Mass., a corporation of Massachusetts Application March 19, 1936, Serial No. 69,676

7 Claims.

This invention relates to the baskets of centrifugal separators, and is more especially concerned with those required in large machines such, for example, as in sugar centrifugals.

In such machines the baskets often run up to forty-four or forty-eight inches in diameter, and they are intended to run at speeds around one thousand or twelve hundred R. P. M. Such a basket may weigh in the neighborhood of seven hundred pounds, and may take a load of, say four hundred pounds.

It has long been recognized that an increased rate of production, a cleaner separation, and better purging of the sugar or other material being treated are produced as the speed of operation is increased. The limiting factor on speed, however, is one of safety. In an endeavor to increase the operating speeds at which these baskets can be run, it has been the practice to reinforce the relatively thin walls of the basket with strong, heavy hoops, shrunk in place. But attempts in this direction are limited by the fact that each hoop reduces the perforated area of the basket through which the liquid is expelled, so that only a relatively limited number of such hoops can be used on a basket of given dimensions.

The present invention is especially concerned with these considerations. It aims to devise a basket which can be operated safely at speeds much higher than those at which baskets of corresponding sizes have heretofore been capable of running. It is also an object of the invention to accomplish the foregoing result without increasing the weight of the basket.

The nature of the invention will be readily understood from the following description when read in connection with the accompanying drawings, and the novel features will be particularly pointed out in the appended claims.

In the drawings,

Figure 1 is a vertical, sectional view, partly in elevation, of a basket embodying the invention;

Fig. 2 is a horizontal, sectional view of the basket shown in Fig. 1, with parts broken away; and

Fig. 3 is a view similar to Fig. 2 illustrating a modication.

Referring rst to Fig. 1, the basket there shown comprises a perforated cylindrical shell 2 which, contrary to the usual practice, has suicient strength to carry the loads usually handled in machines of corresponding sizes and to roperate at speeds higher than normal for such machines.

As above indicated, the invention is especially adapted for use in machines of the larger sizes, although applicable, also, to smaller sizes where it can be used to advantage. This shell instead of being made of the relatively thin sheet metal used in prior constructions, is made of suflicient thickness to give it the requisite strength without the use of reinforcing rings, such as those heretofore used universally in centrifugals of the larger types. Thus the exterior of the basket is, or may be, smooth, and it can be made either of a tubular forging or of a metal plate rolled into a cylindrical form and butt welded. In either event, the shell is of substantially uniform thickness circumferentially, the usual lapped joint or joint plates being eliminated, and it may either be of uniform thickness vertically, or it may, as shown, be somewhat thicker at its central portion than toward its ends in order to reduce weight. Preferably, however, the extreme end portions are of the maximum thickness of the plate. Y

With this construction, therefore, it is entirely possible to utilize some of the exceptionally strong steel alloys having high elastic limits such, for example, as chrome steel, silicon steel, and the like. These metals are capable of withstanding the exceptionally high stresses set up in the shell when it is run at high speeds and carrying heavy loads, and to accomplish this result without the use of reinforcing hoops, and while still maintaining the weight of the basket at a lower value than those customarily used heretofore for similar service.

The basket also includes a head 3 and a bottom 4, both these end members preferably being made of metal plate and welded, respectively, to the top and bottom of the shell. It is desirable to have the welds entirely outside so that the inner surfaces of the basket will be of the same metal composition as the shell, head and bottom. This preferably is accomplished by bevelling the outer edges of the head and bottom and turning a groove in the inner margin of the shell at its top and bottom to provide a suitable annular slot or crevice to receive the welding and also to form shoulders on which the head and bottom, respectively, may be seated and centered in the shell for the welding operation. This provides opposed surfaces on the parts to be welded together, and the welds are made in the outer portions only of said surfaces, as clearly shown in Fig. 1, where the upper and lower welds are indicated at 5 and 6, respectively. It will be understood that these welds extend circumferentially around the entire edges of the head 3 and bottom 4. This construction not only facilitates the Welding operation and produces the desired result of leaving the original metal of the parts undisturbed at and adjacent to the inner surfaces of the basket, but, in addition, it leaves the inside corners, formed by the junction of the top and bottom with the shell, perfectly square. Such a form is of advantage in facilitating an accurate t of the lining or screen into the basket and avoiding the presence of crevices through which solid particles of the material under treatment could escape and which might also present suit-Y able places for corrosion to start. Usually the bottom d is flat, While the head 3 is shaped prior to assembly to give it the bulge typical in machines of this type. The welding operation may be performed electrically, With an oxyacetylene flame, or in any other convenient manner.

In prior constructions it has been customary to cast the bottom and usually, also, the head of the basket. This invention, however, eliminates the use of castings and consequently effects an important reduction in Weight. This is accomplished very simply in the case of the head 3, but a novel construction is provided at the bottom of the basket where it is to be attached to the spindle, shaft, or other supporting member.

Referring to Figs. 1 and 2, it will be seen that the hub construction there shown comprises a flat upper ring 'l and a series of vertical ribs 8, consisting of bars cut from metal plate and Welded at their upper edges to the bottom plate 4 and the ring l. Usually, also, another at ring or bearing plate I0, like the ring 1, is Welded to the lower edges of the ribs, these two parts 'l and l being provided with a central opening to receive the shaft and also having alined holes drilled or punched in them to take the bolts l2 by means of which the basket is secured to the flange or other coupling member carried by the shaft or spindle. An exceptionally strong connstruction may be provided by locating the ribs Vtangentially to the central hole I3, shown in Fig. 2, and abutting the innerend of each rib against the side of another and Welding the parts together in this relationship. An outer ring I4, consisting of a short section of a cylinder, encircles the entire series of ribs and its inner surface ls Welded against the outer ends of the ribs Where it covers said ends.

A modification of the bottom construction above described is shown in Fig. 3. Here the ribs 8 8 are radially disposed but are bent near their inner ends so that their relationship to the bearing plates 'l and IU is practically the same as in the construction shown in Figs. 1 and 2.

The invention thus provides a basket which is immensely stronger for the same sizes and weights than prior constructions of the same dimensions and Which, consequently, is capable of operating at much higher speeds than these former types, while still providing an ample margin of safety. In addition, this construction lends itself to more economical and more rapid production, and to greater flexibility in meeting the demands of special circumstances. The elimination of castings effects an important saving in Weight and in the time required to ll orders for special sizes.

While I have herein disclosed a preferred embodiment of my invention, it will be understood that the invention may be embodied in other vforms Without departing from the spirit or scope thereof. For example, in many centrifugals the shell is imperforate, and bailles of various kinds and arrangements are used in them. The present invention is equally as applicable to baskets of this type as to the more common perforated forms. f

Having thus described my invention, what I desire to claim as new is:

1. A centrifugal basket comprising a shell of approximately cylindrical form, a bottom for said basket comprising a circular metal plate welded at its edge to said shell, a plurality of reinforcing ribs welded to the bottom of said plate and extending fromk the central portion of the basket bottom toward its periphery, and a ring concentric with the basket and welded to the outer ends of said ribs.

2. A centrifugal 4basket comprising a shell of approximately cylindrical form, a bottom for said basket comprising a circular metal plate welded at its edge to said shell, and a plurality of reinforcing ribs Welded to the bottom of said plate and extending from the central portion of the basket bottom toward its periphery, the inner end of each of said ribs being abutted against the `side of another rib and welded to it.

3. A centrifugal basket comprising a shell of approximately cylindrical form, a bottom for said basket comprising a circular metal plate Welded at its edge to said shell, a plurality of reinforcing ribs Welded to the bottom of said plate and extending from the central portion .of the basket bottom toward its periphery, and a central bearing plate Welded to the edges of said ribs.

4. A centrifugal basket comprising a shell of approximately cylindrical form, a bottom for said basket comprising a circular metal plate welded at its edge to said shell, a plurality of reinforcing ribs Welded to the bottom of said plate and extending from the central portion of the basket bottom toward its periphery, the inner end of each of said ribs being abutted against the side of another rib and welded to it, and a central bearing plate welded to the edges of said ribs.

5. A centrifugal basketcomprising a shell of approximately cylindrical form, a bottom for said basket comprising a circular metal plate welded at its edge to said shell, a plurality of reinforcing ribs Welded to the bottom of said plate and extending from the central portion of the basket bottom toward its periphery, the inner end of each of said ribs being abutted against the side of another rib and Welded to it, and a ring concentric with the basket and Welded to the outer ends of said ribs.

6. A centrifugal basket comprising a shell of approximately cylindrical form, a bottom for said basket comprising a circular metal plate Welded at its edge to said shell, and a plurality of reinforcing ribs Welded to the bottom of said plate and extending from the central portion of the basket bottom toward its periphery, each of said -ribs having a lateral bend at the central portion of said basket bottom.

'7. A centrifugal basket comprising a shell of approximately cylindrical form, a bottom for said basket comprising a circular metal plate welded lat' its edge to said shell, a plurality of reinforcing ribs Welded to the bottom of said plate and extending from the central portion of the basket bottom toward its periphery, and top and bottom central bearing plates between which the inner ends of said ribs are located and to which they are welded.

y Y JOI-IN F. THOLL.

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