US2148139A - Screen - Google Patents

Description

Feb. 21, 1939. v

L. G. SYMO NS gunman Filed July so, 1937 5 Sheets-Sheet l W 6% m S W Feb. 21, 1939.

L. G. SYMQNS SCREEN 5 Sheets-Sheet 2 Filed July 30, 1957 .Zkflezezar lore)? d fy/ww 20 [tier/eggs.

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Feb. 21 1939. L, a SYMO'NS 1 2,148,139

SCREEN Fi led July 30, 1937 '5 Sheets-Sheet 3 L. G.- SYMONS Feb. 21, 1939.

SCREEN Filed July 30, 1957 5 Sheets-Sheet 4 1 null: IN N NU Feb. 21, 1939. c; sY oNs 2,148,139

SCREEN Filed July 30, 1957 5 Sheets-Sheet 5 .Zkmzzezfor H lire)? flyzzwas' U m Patented Feb. 21, 1939 scenes Loren G. Symons, Hollywood, Calif., assignor to N ordberg Manufacturing Company, Milwaukee, Wis, a. corporation of Wisconsin Application July 30, 1937, Serial No. 156,511

My invention relates to an improvement in screens and has for one purpose the provision of a screen which shall be of lmaximum efficiency and durability.

Another purpose is the provision. of a screen structure which shall be" relatively cheap and easy to manufacture.

Another purpose is the provision of improved means for imparting a snap action surface or cloth whereby increased efliciency is obtained.

Another purpose is the provision of an improved screening means for surface.

Figure 1 is a plan view with parts broken away;

Figure 2 is a. side elevation;

Figure 3 is a section on'the line 3--3 of Figure 2;

\ Figure 4 is a side elevation of the screen deck itself with parts in section;

Figure 5 is a partial transverse section through the screen deck on anenlarged scale.

Figure 6 is a section on the line-G-G of Figure 5;

Figure 7 is a side elevation of the actuating weight;

Figure 8 is a front elevation of 'the structure shown in Figure 7;

Figure 9 is a section on an enlarged scale along the line 9-9 of Figure 7;

Figure 10 is a section on the line l0-|I| of Figure 9;

Figure 11 is a section on an enlarged scale on the line l|l I of Figure 2; and

Figure 12 is a diagram of ment of the screen.

- Like parts are indicated by like symbols through the specification and drawings.

Referring to the drawings, I indicates any suitable base or surface upon which the screen structure may be mounted. It will be understood that the two sides of the screen frame are substantial- 2 indicates a bottom structural element .for one of the sides herein shown as an 3 indicates a top side frame member. The members 2 and 3 are connected by vertical supports 4 and 5, by an end inclined support 6, and an intermediate inclined support 6a. two side frames thus formed may;.be connected at the top by any suitable transverse members members. 1 practical, it will be understood that it is not ably identical.

angle.

I, and 9, herein shown as angle the vibratory move- 6 Claims. (01. 209-329) and 8 may be connected for example by reinforcing and supporting plates l0 and II. If desired any suitable motor support l2 may be posi tioned 'adjustabiy upon the supporting plate I l and may carry any suitable motor I3, with its drive pulley l4 and belt [5, the purpose for which will later appear. Additional transverse members 2a and 212 may be provided to connect an; space the angle members 2.

I illustrate a screen box as including side plates l6, l6 which may be reinforced by strengthening plates i! to which the screening structure proper is secured; l8 indicates a transverse angle at the feed end of the screen box. A plurality of transverse plates 19 also connect the plates I! at various intervals along the length of the screen box. Intermediate these plates I!) are transverse plates 20. At the tops of the plates 19 are channels which may be welded thereto. In the intermediate plates I9 there are two such channels 2|, 2| secured together as by upper holding plates 22 which may also be welded thereto. In the end plates l9 at the opposite ends of the screen are merely single end channels 23 and at the tops of the intermediate plates 20 are upwardly extended channels 24. In the channels 2| and 23 are positioned strips of material such as rubber indicated at 25 which may be reinforced with fabric or wire as a 26 and are provided with holes 21 adapted to. receive the ends of flexible metal bars 28. It will be understood that each bar 28 at each end penetrates one of the strips 25,

In the particular form of the device herein shown, the bars are somewhat bowed upwardly since their intermediate portions rest upon rubber strips 29 which are notched or apertured as at 30. As will be clear from Figure 6, these apertures are so formed that the rubber more or less hugs the upper portion of each bar or rod 28 so that there is a gripping connection between the strip 29 and the rods which lie in the notches 30. It will be also observed, as in Figures 4 and 5, that the parts are so proportioned that the' to a screen free one or both ends from the apertures 27,

without straightening them, aswould be the case if for instance a high carbon steel were used.

While this bowing of the rods is preferable and The rods are upwardly somewhat bowed and the .remove them upwardly from the notches 30 and soluteiy essential. In any event, the above described arrangement of bars or rods and supporting and gripping rubber members and 29 provides an arrangement whereby the equivalent of screen mesh can be very simply and cheaply applied to and withdrawn from the screen.

Also, a very resilient screening surface is provided and because of the kind of material employed it wears very slowly. A further advantage is the fact that any area or section of excess wear can be replaced without the necessity of replacing the portions of the screen surface which do not wear rapidly. For example, if the maximum zone of wear is at the feed end of the screen, the bars 29 of the feed section may be replaced without the necessity of replacing the bars elsewhere in the screen. The bars may be turned end for end to advantage.

Outer plates are secured, for example by welding, to the outer faces of the side plates I0. As will be clear from Figure 4, these outer plates extend upwardly above the top of the screen box as at 35. Between these upward projecting por-,

tions 36 is a hollow spacing bar or cylinder 31 which may be held at its ends in flanged rings 38. Alined with the spacer 31 is an outer stub 39 flanged as at 40. The flanged stubs the flanged rings 39 are secured together and to the members I6 and 35 by any suitable means as for example by the bolts 4I. Surrounding the stubs 39 are rubber bushings 42 which may be reinforced with fabric as at 43. 39a is any suitable retaining flange for preventing axial displacement. 45 is a screen actuating arm having an eye 45 surrounding the bushing 42. It is herein shown as split, the two parts of the eye being secured together by the bolts 41.

At each end of each side of the screen box and secured to the members I0 are angles 50, 5| arranged back to back. Held between them is a plate 52 with an outward extension 53 to which are secured leaf springs 54 which project upwardly and in turn are secured at their upper ends to extensions 55 extending inwardly from the inclined supports 9 and 5a of the structural members 2; 3. Thus each end of the screen box is secured by a pair of inclined depending leaf spring structures.

Extending across the feed end of the screen box is an angle 55 which is welded to the brackets I 53 and to reinforcing angles 51. It is apertured at each end as at 59 to permit the passage therethrough of pins 59 which have at their outer ends abutments 50. An angle 9| extends inwardly from each of the screen frames and are welded to the diagonal supports, 611. They are also apertured to permit the passage therethrough of the pin 59. Compressed at each end between the angle BI and the abutment 60 is a spring 62. The

function of these springs is to hold the screen' box normally in the position shown with the leaf springs 54 at right angles. In case there is a necessity for adjustment, the pin 59 is provided of the screen box proper.

rests on a bracket 16 secured to the frame members 2 with its centering member II. There is one of these springs at each side of the screen and thus each of the weights I2 is supported on or floated on one of the springs 15 from the main frame.

I9, I0 are bearing members intermediate each pair of side plates, these members being shown also in Figure 11 as surrounded by rubber bushings 19 which in turn are surrounded by the split eye of the arm 45. Thus the arm 45 serves as a vibrating connection between the screen box structure and the weight structure.

The pairs of side arms I0, I0 and II, II are connected as by transverse channels 8|, 82 which define a species of box or housing which is roofed by a' plate 83, the central part of which is upwardly extended or bowed as at 84. 85 indicates spring Penetrating abutments secured to the channels 8| at each end and which penetrate the springs 86 which in turn rest on brackets 81 secured to the vertical supports 5 of the side frames. Thus the springs 88 float and support the upper portion of the above described weight structure. v

The means for vibrating the weight structure and screen includes a hollow shaft 90 which is connected by a flexible driving connection 9| the details of which do not form part of the present invention with a shaft 92 journaled in a bearing 93 supported on one of the structural members 3 along the upper edge of the main frame. It carries a driven pulley 94 about which pass the belts I5. 95 is another flexible connection whereby the shaft 90 rotates a counterweight structure. The counterweight structure is mounted in a pair of bearings including fixed outer sleeves 96, a roller or ball race structure 91, and the shaft portions 98 rotating therewithin. Intermediate these shaft portions 98 is an unbalanced mass of metal 99, which includes circular plates I00 provided with a plurality of apertures IN. The plates are held to the mass 99 as by the bolts I02. I 03 is an adjustable mass or counterweight which may be bolted to the plates I00 at any desired position as by the bolts I04. It will be understood that either by changing the relationship between the member I03 and the plates I00 or by changing the position of the plates I00 in relation to the mass 99, the unbalance of the rotor may be widely varied, as when it is desired to change the stroke or amplitude of vibration.

Note that the bearing members 96 are secured to the transverse channels 8| and -82 by bolts I05.

It will be understood that whereas I have herewith shown and described a practical operative device, nevertheless many changes might be made in the size, shape, number and disposition of parts without departing from the spirit of the invention and I wish, therefore, that my showing be taken as in a sense diagrammatic.

It will be understood, for example, that whereas I have described and shown an element including the arms 10, II, which I have described generally as a weight, I do not wish to be limited to the use of specific weight members I2. I consider it important, however, that some structure having substantial weight shall be movably mounted on the frame or its equivalent and shall serve as the means for controlling the vibration Clearly vasingle weight or a plurality of weights could be used, and a wide variety of structural connections therefor.

The use and operation of my invention are as follows:

I provide an economical and eificient screen in which the direction of movement of the screen itself is linear.

porting springs 54. While the movement is ar.- cuate, the radius of the arc is so great that the effect is so simple linear movement and the screen is simply vibrated in a plane which is at right angles to the extension of the supporting springs. There is no end thrust against the springs themselves and the only' movement imparted to-the screen is the vibration in the said very slightly arcuate path.

In order to impart this movement to the screen, I have employed the above described intermediate weight structure which is floated on the springs 15 and 86, and which includes-heavy weights. The weight structure as a wholeis vibrated by rotation of the unbalanced member or rotor including the members 99 and I03 which may be adjusted in relation to each other in order to get any desired stroke within a very sub stantial range. Thus when the motor I3 is running it imparts a rapid rate of rotation to the unbalanced rotor and the result is a very substantial vibration of the weight structure.

The weight structure, being spring floated on the main frame, transmits a minimum 'of vibration to the main frame and the supporting surfaces or building. The vibration of the weight structure in turn is imparted to the screen box,

proper through the arms or conrods 45. As each end of each arm 45 has associated therewith a rubber bushing 42 or I9, in practice this use of rubber bushings causes a snap action or a sudden change in direction of movement of the screen which imparts a very efficient screening eifect. Furthermore, the torsion of the rubber bushings permits the screen box itself to be driven with a minimum endwise thrust on the supporting springs 54, which would otherwise result because of the slightly arcuate path of movement of the deck.- Whether the path of vibration of the weight structure is slightly oval or somewhat squared or approximately circular, the vibration of the screen box proper will be linear.

In analyzing the movement and mode of operation of the present screen, the flexible leaf mounting of the deck on the leaves" 54, without any bushings or bearings, has in practice proved highly satisfactory. These leaves are preferably ilght spring leaves, which makes for longer life the ideal vibrator has a minimum number of As shown for example in Figure 9, my unbalanced rotor, including the portions 99 and bearings.

I93, rotates in'only two bearings. In order to provide a shaft between the bearings of maximum strength and simplicity I place the bearings close together as shown in Figure 9. The out of balance shaft, including the members 98 and-99,

is preferably cast in one piece, which makes it extremely rigid.

I have provided what in practice has turned out to be a highly eflicient connection between the 4 unbalanced weight structure 99 and the deck which is capable of transmitting linear motion to That is to say, it acts as if it were rotated about the upper ends of the sup the deck while allowing substantially free motion to the vibrator structure. I have therefore employed the arms or conrods 45 provided at each end with rubber bushings or torsion members 42 the deck, it will be well to consider the diagram of Figure 12. The weight W of which X is the center of gravity, may be considered as an inertia member resisting the movement of the vibrator or unbalancedmember 99 only in the discretion of the line A--B. In this direction the vibrator would have to movev itself and the weight; In the direction C-D the vibrator has to move itself plus the weight of the deck, but exerts a leverage on the deck mathematically as the distance ZX is to the distance YX. If the distance XY were the same as the distance YZ the force of the vibrator to move the deck would have to equal only one half of the resistance of the deck, as the leverage would be 2 to 1.- This in turn would mean that in order to make the resistance to the vibrator in the direction AB the same as C--D, the weight W would necessarily be less than the weight of the deck.

Thus placing the vibrator above the point Y where the conrod 45 is connected to the weight structure does two things. In the first place, it places the vibrator at a level higher than the screen or deck itself, where it does not interfere with the movement of the deck or with the feed of bulky material over the deck. In the second place, it enables a reduction of the weight W, which has no function except to act as a controlling medium. The entire weight and cost of the screen may be reduced without any sacrifice of efficiency.

In referring to Figure 12, the motion of the deck is indicated by the arrow M, it being practically linear and only very slightly arcuate, being in effect an arc with its center at the upper edge of the deck, th radius defined by the springs 54. The motion of t e weight is almost linear and at about ninety degrees angle to the motion of the deck. The actual motion is indicated for example by the flat or elongated ellipse shown at E. The vibration of the vibrator or the unbalanced rotor may be generally circular, which effects a substantial reduction of the load on the bearings, as compared for example to the bearing load caused by oval vibration. The parts may be so proportioned as to cause the shaft Z of Figure 12 to vibrate in a. practically circular path or vibration form. In effect what I do in applying a linear vibration to the screen deck is to employ a means for controlling the rotation of the unbalanced weight 99 by subjecting itto resistance at about ninety degrees to the axis of resistance or axis of pull between the vibrator unit as a .whole and the screen deck.

The vibrator and the Weight are floated on the base in such a manner that no vibration can be transmitted to the base except the very small amount that might be caused by the lengthening and shortening of the springs 15 and 88 shown in Figure 2. In actual operation of machines, the

lack of vibration is marked, a fact which permits the employment of a comparatively light base. This use of a. light base makes'for a more economical machine. Also, the fact that the weight 'does not have to be as heavy as the deck makes the entire screen economical to build.

In connection'with the operation of the screen above described, the rubber bushings 42 and I! 75 4 its movement before the deck does.

In practice, as tested in the actual use of screens made in accordance with the above description, the result is a snappy or quick reversal of action at the ends of the strokes and an increase in screening efficiency. This snap action is obtained without acceleration of the speed unit itself and in fact is more effective at certain lower speeds than at higher speeds.

With the snap action obtained by speeding up the power plant or the transmission, the material is in practice thrown sufllciently high in the air at each impulse so that it does not return to the surface of the deck and come to rest before the succeeding impulse. This is disadvantageous because the screening mesh meets the material at the maximum upward and forward speed of the mesh and imparts a batting action. Where the rate of vibration can be made somewhat slower, the material has time during impulses to settle back to the cloth. The result is a better screening action and less damage to the cloth, with a resultant increase in the capacity of the screen.

In connection with particles of critical size, if they are allowed to settle upon the surface oi! the deck, they can slip through the deck apertures. But they can easily be batted upwardly away from the deck if they are struck by the screen cloth when the cloth or deck is in rapid motion. The advantage of the slower movement when accompanied by the snap action obtained by the rubber bushings may be illustrated by changing the speed of movement or vibration rate of a screen made in general accordance with the present description and drawings. In a particular screen, tests showed that the screen had a larger capacity, and that individual particles actually moved faster, and that the screen cleaned cleaner, when run at 900 R. P. M. than when run at 1250 R. P. M. This was because the lower rate of speed prevented the batting action. The lower rate, in turn. was permitted because of the snap action of the rubber bushings I claim: I

'1. In a screen, a base, a screen deck yieldingly mounted on said base, a vibrating unit yieldingly mounted on said base independently of said deck, and including an unbalanced rotary member and means for rotating it and for thereby vibrating said unit, a weight on said unit remote from said rotary member, a structural member connecting said weight and said rotary member, and an actuating connection between said deck and said structural member, connected to said structural member intermediate said unbalanced rotary member and the center of gravity of said weight.

2. In a screen, a base, a screen deck yieldingly mounted on said base, a vibrating unit yieldingly mounted on said base independently of said deck, and including a transverse member extending across the screen above the screen deck and having side arms depending from each end thereof, weights on the lower portions of said side arms, an unbalanced rotary member mounted upon said transverse member, and means for rotating it and for thereby vibrating said unit, and actuating connections between said deck and said side arms, connected to said side arms intermediate said weights and said unbalanced rotary member.

3. In a screen, a base, a screen deck yieldingly mounted on said base, a vibrating unit yieldingly and independently mounted on said base, and including an unbalanced rotary member and means for rotating it and for thereby vibrating said unit, a weight on said unit remote from said rotary member, a structural member connecting said weight and said rotary member, and an actuating connection between said deck and said structural member, intermediate said unbalanced rotary member and the center of gravity of said weight.

4. In a screen, a base, a screen deck yieldingly mounted on said base, a vibrating unit yieldingly and independently mounted on said base, and including an unbalanced rotary member and means for rotating it and for thereby vibrating said unit, a weight on said unit remote from said rotary member, a structural member connecting said weight and said rotary member, and an actuating connection between said deck and said structural member, intermediate said unbalanced rotary member and the center of gravity of said weight, said actuating connection including a connecting rod generally perpendicular to a line connecting the center of rotation of said unbalanced rotary member and the center of mass of said weight.

5. In a screen, a base, a screen deck yieldingly mounted on said base, a vibrating unit yieldinglyand independently mounted on said base, and including an unbalanced rotary member and means for rotating it and for thereby vibrating said unit, a weight on said unit remote from said rotary member, a structural member connecting said weight and said rotary member, and an actuating connection between said deck and said structural member, intermediate said unbalanced rotary member and the center of gravity of said weight, said actuating connection including a connecting rod generally perpendicular to a line connecting the center of rotation of said unbal- 'anced rotary member and the center of mass of the horizontal.

6. In a screen, a base. a screen deck yieldingly mounted on said base, and means for constraining it to a generally linear vibration in a path inclined substantially from the horizontal, a vibrating unit yieldingly and independently mounted on said base and including an unbalanced rotary member and means for rotating it and for thereby vibrating said unit, a weight on said unit remote from said rotary member, a structural member connecting said weight and said rotary member, and an actuating connection between said deck and said structural member, intermediate said unbalanced rotary member and the center of gravity of said weight, including a connecting rod generally parallel with the path

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