US2213050A - Sifter - Google Patents

Description

Allg 27 1940 c. L.. REIMULLER ET AL 2,213,050

S IFTER SSheetS-Sheet 1 Filed March 19, 1937 Al1g 27, 1940- c. REIMULLER ET Al. 2,213,050

SIFTER Filed March 19, 1937 5 Sheets-Sheet 2 @DFE CARYL L. REIMULLER Aug- 27, 1940. c. L.. REIMULLER E-r Al. 2,213,050

S IFTER Filed March 19, 1937 3 Sheets-Sheet 3 CARYL L. RE/Mu/ LER EUGENE G. BERRY Patented Aug. 27, 1940 UNITED STATES PATENT OFFICE SIFTER Application March 19, 1937, Serial N o. 131,826

2 Claims.

This'invention relates to a sifter and concerns itself with novel features for increasing the effectiveness thereof whereby its sifting capacity is greatly increased.

The screens of such sifters are usually covered with bolting cloth such as bolting silk or the like, and in use there has always been a back pressure against the bolting cloth due to the updraft of air from the outlet spoutings. This back pressure not only retards or decreases the siftu ing operation, it also prevents a certain amo-unt of the desired product from passing through the bolting cloth with the result that such product would pass off with the screenings or tailings.

A further defect in sieves generally used resides in the uneven distribution or depth of the product upon the sieve. Toward the rear end of the sieve there has always been a thinner layer of material. That is, the material would be of less depth at the rear than at the forward end. Due to this condition, there would not be the desired pressure or weight to force the material through the bolting cloth in an effective .manner. This would also cause good products to pass off with the tailings.

It is an object of this invention to remedy the defects above noted in the provision of means for excluding as far as possible the inflowing air and in arranging the sieve to provide a more uniform depth or distribution o-f material.-

The invention comprises the novel structure and combination of parts hereinafter described and more particularly pointed out and dened in the appended claims.

In the accompanying drawings which illustrate a preferred form of this invention and in which similar reference numerals refer to similar features in the different views:

Figure l is an enlarged sectional view through a sifter involving this invention;

Figure 2 is a sectional view taken upon the line II-II of Figure 1 looking in the direction of the arrows;

Figure 3 isa sectional view taken upon the line III-III of Figure 1 looking in the direction of the arrows;

Figure 4 is a top plan View of the sifter;

Figure 5 is a top plan view of the sifter with the cover removed showing the upper sieve;

Figure 6 is a sectional View taken upon the line VI-VI of Figure 1 looking in the direction of the arrows;

Figure 7 is an enlarged sectional view taken upon the line VII-VII of Figure 6 looking in the direction of the arrows;

f Figure 8 is a top plan View of the second or bottom sieve;` f Figure 9 is a top plan view, of the drift board under a sieve; and Figure l0 is an enlarged sectional view taken upon the line X--X, of Figure 1 looking in the direction of the arrows,

The sifter involving this invention comprises a box or receptacle and one or more sieves-contained in superimposed relation therein. While any number of sieves may be used, in the present instance only two sieves have been illustrated.

In the drawings the box I is preferably ofrectangularV form having suitable openings in its bottom for discharge spouts as will later appear. In this box are contained the sieves and drift boards that make up the sifters.

The upper sieve 2 (Figure 5) consists of a rectangular frame or spreader which rests upon the bolting cloth 3 and its frame therebelow in the usual manner. The bolting cloth 3 extends transversely of its frame between the vpoints 4 and 5 leaving an uncovered margin at each en d. At the forward edge of the spreader there is a baflie board 6 that extends from one sideof the frame to a point beyond the center line of the sieve. A strip 'I .extends from the baffle board 6 tol the end frame member at the casing and divides the front uncovered margin into two parts. A plate 8 attached to the bolting cloth frame covers `onehalf of such margin for the deposit of material to be handled by the upper sieve. The other part 9 of such margin is left open for the passage of material to the lower sieve.

At the rear margin of the spreader 2 there is a baiile or board -I that extends from the nearside ofthe frame to a suitable point spaced from the other side. At the inner end of the baiile board Ill there is a strip II that extends between such baiiie board and the rear end of the sieve and forms with the farside of the sieve a discharge opening I 2 for tailings or screenings. Between the bale boards 6 and I I are baie boards I3, I4, I5, and I6. The'baiiles I3 and I5 extend inwardly from one side wall to points suitably spaced from the other side wall. The baiiles I4 and I6 extend inwardly from the other side wall to suitable points spaced from the other side walls. The arrangement of the baille boards or partitions as they are frequently termed define a circuitous path that the material traverses. Flights I'I are attached to certain of the partitions and sides of the sieve to assist in conveying the material, and a longitudinal bracing member |4a may be app-lied over -the baflles.

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There is nothing broadly new in the use of baille partitions and iiights. It will, however, be noted that the partitions are gradually spaced closer together toward the discharge or tail end of the sieve. Thus, the partition baffles IO and I6 are spaced fairly close together in comparison with the spaces between the other partitions at the head end. The space between the baffles IG and is increased over the space between the baffles lil and I6, but is narrower than the spaces between the head bailes.

The feature of decreasing the spacing of the bales toward the rear end of the sieve tends to produce a more uniform distribution or depth of material on the sieve. For the material in passing from a broader space to a narrower space will be caused to assume a greater depth, but as material is constantly passing through the cloth, there will be less material passing into the narrower spaces or channels.

It will be appreciated that the weight of the material on the cloth tends to force the same therethrough. When there is only a thin layer of material on the cloth, there is very little weight to force the material through the cloth. The decrease in the spacing of the bailies at the tail end tends to avoid the thin layer of material that usually occurred toward the tail end of the sieves heretofore in use.

In use, the material is deposited upon the plate 8 from which it passes through the space between the free end of the baille E and the nearside o1 the sieve. It then passes upon the cloth 3. The material will then travel in a circuitous path around the free ends of the baies and between the same toward the rear or tail end of the sieve. The tailings and screening will pass between the baiiies Iil and I5 to the discharge opening I2. A material check I8 is placed in the passage between the baiiies I0 and I6 to prevent any floating product from passing out with the tailings.

The material check I8 consists of a flexible ap I 9 of suitable material such as canvas secured to a strip Zl (Figure 3) that spans the bailies Iil and I6. The tailings and screenings will readily pass under the flap I9, but the ap will prevent any floating or air suspended particles of the product from passing out with the tailings.

Below the bolting cloth and in spaced relation therewith, there is a wire screen 2| best shown in Figure l for supporting cloth cleaners. The wire screen may be attached in any suitable manner, but it is preferably attached to the transverse spacing members 22 that constitute the frame of the bolting cloth.

The material passing through the bolting cloth will drop upon the drift board 23, which is positioned in an inclined plane below the bolting cloth to cause the bolted material to descend by gravity to the discharge spout at the rear end of the sieve. A drift board is shown in plan view in Figure 9 and is of usual construction with nights I'i, except that it is provided with an air lock at its discharge end to prevent air from entering and retarding or obstructing the pas sage of the material through the bolting cloth. In the past, this incoming air or updraft has created back pressure under the bolting cloth with the result that decreased capacity resulted, and some product that should have gone through the bolting cloth floats off with tailings.

The air lock associated with the drift board and outlet may assume various forms. A simple one has been shown merely as a matter of illustrating the invention. It consists of a member 24 of suitable material attached at its front edge to the end member 23a of the drift board from which it slopes downwardly and inwardly. To the inner end of the member 24, there is flexibly hinged as by canvas, a flap 25 which may be metal, wood or composition or any suitable material. The iiap 25 (Figure l) slopes downwardlly toward the discharge opening 26 in the drift board and overlaps the edge of the discharge opening which may consist of the next lower sieve frame or the bottom of the sieve box as shown in Figure l. The flap may be yieldingly urged toward its closed position by any suitable yielding means such as a coiled hinge spring 25a. The air lock is designed to extend the length of the discharge Opening. The hinge of the ap 25 is sufciently flexible to lift and allow the sifted product to pass thereunder, but it will prevent air from entering through the discharge outlet and forming a back pressure under the bolting cloth.

Below the rst sieve, there may be any desired number of other sieves. In the present instance, only a second sieve 2a has been shown. It is shown in plan view in Figure 8 and is similar to the rst sieve with the exception that the forward margin of the cloth frame is closed by a plate 21 which extends throughout the width of the sieve.

Below the sieve 2a, there is another drift board 23 similar to the rst one and which also supports an air lock 2li- 25, as clearly shown in Figure l.

The tailings and screenings will descend through the passage I2 formed in the sieves, drift boards, and the bottom of the sifter box and will pass out through a chute 23 (Figure 6) attached to the bottom of the box.

rThe bolted material will pass through the openings 26 in the drift boards and through a similar opening 25a in the bottom of the sifter box and through a spout 29 attached to the bottom of the box. The spout 29 maybe also provided with an air lock at its outlet as shown in Figures 6 and '7. This air lock may consist of a pair of metal flaps 30 and 3! pivoted upon a stationary rod 32 extending through the spout. These flaps are normally held in closed position by suitable yielding means which may be in the form of a spring 33, having its intermediate portion coiled around the rod 32, with its terminal portions 34 bearing against the undersides of the aps.

The tendency of the terminal portions 34 of the spring will tend to force the iiaps to closed position. The spring, however, will readily yield to the weight of the material passing through the spout whereby the flaps will swing downwardly for the passage of the sifted material. While these iiaps will yield for the escape of material, they will tend to check the inflow of airl Thus a double air check has been shown. However, one or' the other may be dispensed with if desired, since it appears apparent that either one will suiliciently che ..1 the inflow of air. Moreover, the forms of these air locks may be varied, so the present forms should be merely construed as the preferred means for checking the inow of air and preventing back pressure against the bolting cloth.

The sifter box I is closed by a cover having transverse latch strips 3G thereon which extend beyond the side edges thereof. The extended portions of these latch strips are bifurcated for receiving swingable latching elements 3l secured to the sides of the box as shown in Figure 6. The

upper ends of these latching elements include threaded nuts 38 whereby the cover can be tightly clamped in place.

Upon the top of the cover and adjacent the forward end of the sieve box, there is a material distributor 39 for evenly distributing the material to the diierent sieves. This distributor comprises an inverted channel shaped casing resting upon the cover with an intermediate flange 40 resting upon the upper sieve frame, and a conical dome 4l supported centrally Within the casing by means of attaching brackets 42 (Figure 1).. The tip of the conical dome extends into an inlet opening 43 provided centrally in the top of the casing. Upon the walls of the casing are suitable conveying flights 44,

Beneath the distributor, are material inlet apertures 45 in the cover 35. 'I'he apertures 45 are substantially square with their opposite sides arranged at angles of substantially 45 with the sides of the casing. Upon the cover 35 are slidably mounted a pair of slide gates 46for adjusting the size of the inlet apertures 45. Each slide gate 46 has a s-lot 41 for receiving a bolt 48 which extends through the cover. A wing nut 49 upon each bolt clamps the adjacentslide gate in adjusted position. Each slide gate has a V- shaped notch 50 in its front end of an angular formation corresponding to the angular formation of the inlet apertures 45 so that in any adjustment of the slide gates, there will always be a square inlet aperture for the material.

The purpose for maintaining a square or angular inlet opening is important for the reason that such an aperture will not become clogged, while a round aperture will become clogged and prove unsatisfactory.

In use, the material to be sifted which may be flour or a similar product is poured through the inlet opening 43 and strikes the conical dome which distributes the same equally tu all parts. Then the shaking or movement that is imparted to the sifter box will cause the ilights 44' to move the material whereby an even distribution of material is obtained. The material falling through one inlet aperture will descend upon one sieve while the material falling through the other inlet will descend upon the other sieve.

From the foregoing it will be obvious that material and important improvements have been made with respect to a sifter involving the even distribution of feeding the material to the sifter,

the more even distribution of the material over the sieves, and the installation of novel air locks which prevent back pressure against the bolting cloth. It has been discovered in actual practice that these improvements, especially the air locks, result in a great increase in the capacity of the sifter. The eilciency thereof is increased about twenty percent vwhich is a notable increase in the amount of product that can be daily sifted.

We are aware that many changes may be made and numerous details of construction may be varied through a wide range without departing from the principles of this invention, and we, therefore, do not purpose limiting the patent granted herein otherwise than is necessitated by the prior art.

We claim as our invention:

l. In a sifter, a vibratory casing, a plurality of vertically spaced screens carried by said casing, said screens being covered by bolting cloth, drift boards respectively disposed below the screens forl conducting screened material towards the screen ends, a common discharge passageway for screened material having lateral communications for respectively receiving the screened material from the drift boards, and baille means in the outlet passageway ateach of said lateral communications including a yieldable flap adapted to allow the escape of the screened material from the adjacent drift board into the outlet passageway but preventing movement of air from the outlet passageway against the underside of the bolting cloth above the adjacent drift board.

2. In a sifter, a vibratable casing, a plurality of vertically spaced sieves carried by said casing, drift boards respectively disposed below said sieves for conducting away the sifted material, a common outlet passageway for receiving the sifted material from the drift boards, inclined bailles i'n the discharge passageway respectively disposed above the discharge ends of the drift boards, and flaps yieldably supported from the respective baffles adapted to allow the escape of sifted material from the adjacent drift boards into the outlet passageway but preventing reverse movement of air from the outlet passageway against the underside of the adjacent sieve, and a by-pass passageway at each baille enabling passage of material from the upper surface of each baille past its associated ilap.

CARYL L. REIMULLER. EUGENE G. BERRY.

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