US2314880A - Screen - Google Patents

Description

March 30, 1943. R HELLER 2,314,880

SCREEN Filed May 23, 1941 l I i I I QICHAED D: HELLER,

Patented Mar. 30, 194-3 ST TE i ATEN T O F F 1 C151 6 Claims.

This invention relates to screens particularly adapted for use in vibratory apparatus and one of its objects is the provision of improved and efilcient'means for mounting such screen on the deck of the vibratory apparatus.

Another object of the invention is the provision of improved and efiicient means for mounting a parallel wire screen on a deck of a vibratory apparatus.

Other objects of the invention will appear hereinafter, the novel features and combinations being set forth in the appended claims.

In the accompanying drawing,

Fig. 1 is a sectional elevational view of the screen comprising my invention;

Fig. 2 is a plan view of the screen shown in section in Fig. l;

Fig. 3 is a sectional perspective view of a portion of the cross strip mounting'means shownin Fig. 1;

Fig. 4 is a view like that of Fig. 3 but showing a modification; and

Fig. 5 is a side view of the unitary cross-strip shown mounted in a troughin Fig. 4.

This application is a continuation in part of my co-pending'application S. N. 234,014, filed Oct.

8, 1938, Patent No. 2,283,877, granted May 19, 1942, for an improvement in screens.

In a vibratory type of screen, particularly of the type energized from mixed or alternating current'of 60 cycle frequency or from rectifiers, in which the frequency of vibration is relatively high, such as 3600 vibrations per minute, or in excess thereof, as derived from a source of commercial current of 60 cycle frequency, there is a considerable whipping action imparted to the screen cloth which tends to reduce the life of said screen cloth not onlyby virtue-of the whipping ac tion which tends to break the 'clothat its points of anchorage, but also because'of the wearing at positions where the wires of the screen cloth contact the deck of the vibrating screen.

In the invention herein disclosed an essentially new type'of screen cloth is provided fora high frequency vibratory screen in which the lif of the screen ismaterially increased due to the fact that very high earbonsteel wires, such as music or piano wires, make up the-screen cloth and further, at the points of bearing between the screen cloth and the deck, resilient rubber or similar bearing means are provided.

It may be stated that the structure of the screen and its general mode of operation, insofar as above described, is disclosed and claimed the'patent to James A. Flint, No. 1,846,326, dated February 23, 1932, for an Electric reciprocating motor.

Mounted upon and rigidly attached to .the frame ll] of the vibratory apparatus is .a deck comprising a pair :of longitudinally extending channel members 38, 35, the bottom 'Jlanges of which are rigidly-attacheditogether-bycross channels 3'! of which there is one at each end and preferably two intermediate the ends. The top flanges of the channel members 38 are also attached together-by three spaced angle members 38.

Extending longitudinally of the 'deck and supported in notches in the channels 31 to which they are welded, is a plurality of upstanding ribs 39 having elongated channel tops 40 adapted to receive elongated longitudinally extending wood strips il which support the screen cloth 42, as hereinafter described in complete detail.

Referring particularly to-Fig. 2 of the drawing, it will be'seen that thescreen cloth i2 comprises -a pair of end bars 43, 43,:prefera1biy rectangular in shape, though other shapes may be employed, said end bar-s43 being made of steel or iron.

Extending betweenthe said end bars 43 is a plurality of parallel wires M which are preferably made of high "carbon steel, such as "bright pianoor music wire. It-is to-be noted that these parallel wires 44 are straighter substantially straight, therefore difiering -fr0mthe common screen cloth in which the strands are interwoven transversely and longitudinally whereby substan-' tially each. strand forms a zigzag path or is crimped at eachcontact area with another strand.

The wires 4% maybe secured to the end bars :23, 33, as explained in "my Patent No. 2,220,106, granted Nov. 5, 1940, for an improvement in b'creen clo thand'methodof making same. 1

Intermediate the end-barsSK-dS the wires 44 are pref erably attached together through the iongitudinal-length of the'screen by top and bottom tinstrips 5! (sheet iron coated with tin) which are attached 't0gethe1andto saidwires 4 by solder. The 'tin strips *51 are preferably so positioned that they will be 'directlyabove thea'forementioned'wood strips 41 as shown in 3.

Adjacent each bearing area between the screen cloth #2 and the deck I provide rubber or other depressibie material-cushion means which-periorms three functions, hereinafter set forth.

Adjacent the positionsof attachment of the wires 44 to the end bars 43 are strips of rubber 52 or any other similar material which extend. longitudinally the entire len'gth -.of the screen cloth and are compressed against the wires 44 so as to extend on both sides of them, being attached to said wires as by rubber cement. Rubber strips 53 are also laid under one of each of the tin strips which is to bear against a wood strip 4| thereby forming a cushion between the wood strip 4| and the tin strip 5|. The rubber strip 53 extends laterally beyond the extremity of the associated tin strip 5| and is compressed between the wires 44 adjacent each edge of said tin strips 5|.

The three-fold function of the rubber strips 52 and 53 is as follows. In the first place, these rubber strips provide a resilient cushion between screen cloth 42 and the associated bearing portion of the deck thereby preventing undue wear of both the deck and the screen cloth. In the second place, these rubber strips are, of course, positioned at areas on the screen cloth at which there is no substantial independent vibration of the wires 44, said wires 44 being free to vibrate individually between any two bearing areas of said screen cloth 42 and the deck. Consequently since the rubber extends beyond the point of rigid connection between an end bar 43 and a wire 44, or a tin strip 5| and the wire 44, this rubber will progressively dampen the vibration of each individual wire 44 as it progresses towards its point of rigid attachment thereby reducing appreciably the tendency of the wire to break on at its point of rigid attachment to a bar 43 or tin strip 5| under the influence of the relatively high frequency vibration of the vibratory screen. In the third place, since there is a very small amount of vibration of each wire 44 adjacent its point of attachment to an end bar 43 or a tin strip 5| the wires 44 are not able to clear themselves of any material which tends to become lodged between adjacent wires due to this lack of vibration and this rubber along this area prevents material being caught between adjacent wires or strands 44 and thereby becoming lodged in the screen cloth 42.

To provide for the attachment of the screen cloth 42 to the deck and for its adjustable tensioning I provide a novel attaching means which is designed particularly to aid inmaintaining the Wires 44 in attachment with the end bars 43. As clearly seen by reference to 1 of the drawing, adjacent the left hand side of the deck there is a longitudinally extending channel member 54 the top flange of which is pivoted in a longitudinally extending groove 55 formed by the top flange of the channel member 36 and a notched longitudinally extended member 56 welded to the upper corner of said channel member 36.

4 Adjacent the bottom of the channel 54 and distributed along the length thereof is a plurality "of holes adapted to receive tensioning bolts 51 which extend through apertures in the channel 36 and receive adjustingnuts 58 provided with bearing sleeves 59 which extend through the re-' ceiving apertures in the channels 36. A washer B0 is also preferably positioned between the outer face of the channel 36 and the head of each nut 58. Another washer 6| is also preferably placed between the head of each bolt 51 and the inner face of the channel member 54. I

The bottom flange of the channel 54 carries a downwardly extending'or inverted channel 62, the inner flange of which carries a bearing plate 63 to increase thebearingarea incontact with the rubber strip 52 which bears against said plate 63 and the inner flange of said channel 62. Extending longitudinally substantially the full length of the channel 62 and in the corner adjacent the inner flange is a ledge 64 formed by a longitudinally extending rectangular bar which is welded at the position indicated. Carried 0n the opposite or outer flange of the channel 62 is an abutment 65 formed by a longitudinally extending bar which is spaced from the outer corner of said channel 62 and is welded to said outer flange thereof.

As is clearly illustrated in Fig. 1 of the drawing, the outer end of an end bar 43 projects over the abutment 65 and engages the bottom of the channel 62 which is, of course, in an inverted position. The top inner edge of the bar 43 abuts the inner flange of the channel 62, and

said bar 43 at a position adjacent said top inner edge engages the ledge 64. It will be seen that the structure defined locks the end bar 43 to the attaching and tensioning mechanism after the end bar 43 is inserted in place.

Furthermore, it is to be noted that the abutment 65 cooperates with the end bar 43 to effect a clamping action on the wires 44 and the tin strip 50 to prevent any of the wires 44 being pulled loose from the end bar 4 3.

As a further action to prevent any wire 44 being pulled from an end bar 43 it is to be noted that each wire 44 bends as it leaves the end bar 43 and bends in a direction to force said wires 44 into engagement with the bar 43. In other words, this results in the wires 44 being at least partially wrapped around the bars 43 which is carried even farther at the outer ends of said wires 44, thereby resulting in a. very secure connection between the two, particularly when supplemented by attaching solder and tin strips 49 and 50.

At the right hand end of the deck the screen cloth 42 is attached in a manner quite similar to that above described by an attaching bracket indicated generally by the reference character 66, except for the fact that the bracket 66 is not adjustable but is fixed to'the channel 36, and the structure of which is obvious from the above description of the adjustable attaching means and by reference to said Fig. 1 of the drawing.

It may additionally be mentioned that to reinforce the deck there is provided a plurality of spaced outward extending webs or fins 61 which provide vertical rigidity to the channel members 36.

In the operation of the screen comprising my invention alternating, mixed or rectified, pulsating current is supplied to vibratory motors which will cause vibration of the deck relative to the main frame I0 in a manner well understood in this art and more completely described in the above mentioned patent to James A. Flint. This vibration will be at a relatively high frequency, such as 3600 vibrations per minute though, of course, other frequencies of vibration are contemplated.

Under the influence of this relatively high frequency of vibration the individual wires 44 of the screen cloth 42 vibrate as individual units between the points of bearing between them and the deck, for example, between each of the rubber strips 53 and between each rubber strip 53 and a rubber strip 52. As a consequence, blinding of the screen cloth 42 is substantially prevented because this individual vibratory motion of each portion of a wire 44 in addition to the entire vibratory motion of the deck as a whole will clear the screen cloth 42 of any material which tends to adhere thereto. As a consequence,

the screen cloth of my invention is extremely desirable in combination with a relatively high frequency vibratory type of screen, though its use is not entirely so restricted.

As previously mentioned, to prevent undue wear of the screen cloth 42 or of the deck, cushion means in the form of rubber strips 52 and 53 or any other appropriate cushioning material is provided and interposed between the screen cloth 42 and each point of bearing or contact with the deck. These rubber strips 52 and 53 additionally prevent breakage of the individual wires 44 due to their vibration by virtue of the dampening of the vibration thereof adjacent their points of rigid attachment either to end bars 43 or to tin strips Still further, these rubber strips '52, 53 prevent blinding of the screen at the areas where there is no appreciable individual vibration of the wires 44 as distinguished from the vibration of said wires due to their attachment to the vibratory deck. The wood strips 4| are desirable because there is inherently some wearing at these bearing areas and as said wood strips 4| become worn they can be replaced.

In the modification shown in Figs. 4 and 5 the block of wood 4| is replaced by a hard rubber strip 4| vulcanized to a bottom strip of metal 68 and a strip of relatively soft rubber 53 is vulcanized at the top of the hard rubber strip 4|. The soft rubber strip 53 is provided with spaced apart grooves 59 which serve to space apart the wires 44, 44. It should be particularly understood that in the form shown in Figs. 4 and 5 the grooves 69 are preformed transversely of the soft rubber strip 53 so as to be at such distances apart as will conform to the spacing between the wires 44 as predetermined by their connections to the end bars 43, 43. The soft rubber strip 53 has no grooves preformed therein but when the tensioning mechanism shown at the left-hand portion of Fig. l is operated, the downward pressure of the cross-strips 5|, 5| and of the wires 44 is sufficient to cause the edges of the soft rubber strip 53 to bulge upwardly between the Wires 44 as shown in Figs. 1 and 3.

When the vibratory apparatus is operated the entire screen shown in Fig. 2 vibrates as a unit in unison with the vibration of the deck. In addition, each individual strand of wire 44 is vibrated relatively to the deck which renders the parallel wire screen more efiicient than a woven wire screen in that clogging of the material or blinding the screen is less likely to occur in the parallel wire screen. However, there is a tendency for the individual vibrations of the wire strands to cease adjacent its points of anchorage and therefore at such places the edges of the rubber strips 52, 52, 53, 53 act as resilient abutments to prevent certain sizes of material particles from reaching any wire zone which is static relative to the supports for the wires 44. For instance, any material which tends to get caught between adjacent wires 44 which abuts against an edge of a rubber strip will be vibrated by the individual vibrations of the wire strands so that such material will either be screened or pass over the wires to the discharge end of the deck.

The same is true with regard to the edges of the rubber strip 53' in Fig. 4. However, in this form the tendency to form a zone which is static relative to the deck is reduced to a minimum because the rubber between the grooves 69 is yielding and therefore interfering less with the individual vibrations of the wir strands than when connecting strips 5| are soldered to the wires 44. It should be particularly noted that in the form shownin Figs. 4 and 5 the connecting strips BI and the solder have been entirely eliminated, the grooves 69 being relied on to hold th wires 44 spaced apart at the same distances as spaced apart by the connections to the end bars, '43.

It should be particularly noted that in the form shown in Fig. 3 the soft'rubber strip 53 rests loosely on the block of wood '41 and the crossstrip 5| is relied onto keep the wires spaced apart in parallelism. In the form shown in Fig. 4, however, the soft'rubber strip 53' is vulcanized to the hard rubber block 4| and therefore the .latter prevents lateral distortion of the rubber strip 53 between the preformed V-shaped grooves 69 shown in Fig. 5. That is to say, by vulcanizing the soft rubber strip '53 to the block 4| of hard rubber the grooves 69 are maintained equally spaced and in parallelism and can be relied on to receive the bare wires and hold them equally spaced and in parallelism, particularly when th screen is supported in arched formation and placed under tension tending to flatten the same and exerting such force on the wires as to press them against the bottoms of the grooves.

It should also be noted that a bottom strip of metal 58 is vulcanized to the bottom of the hard rubber block 4| to form a cross-strip unit that is readily removable from the trough '40 for replacement purposes. While the strip of metal 68 serves as a wear plate in screen apparatus where the frequency of vibration is relatively hi h, thus maintaining the vertical dimension of the cross-strip unit, such metal strip also serves to maintain the whole cross-strip unit intact by preventing breaking of the relatively brittle hard rubber block 4| either during manual handling or while the apparatus for vibrating the screen is in operation.

Both in the form shown in Fig. 3 and in the form shown in Fig.4, the means for supporting the screen on the deck comprises channels or troughs 40 for frictionally holding the elongated block 4| or 4|. In the form shown in Fig. 4 th soft rubber layer 53' is of the same width as the block 4|. In the form shown in Fig. 3 the flat strip of rubber 53 is wider than the strips 5|.

Although my improvements are particularly adapted to the relatively high frequency vibratory type of screen, they are also useful for general application. For instance, the rubber strips 52, 53, 53 are useful in stationary parallel wire screens where th material to be screened is flowed over the screen while the latter is in such an inclined position as to direct the material along the screen by gravity. In such event it has been found in practice that the rubber strips 52, 53 have reduced to a minimum the tendency for the material to become caught between the wires adjacent the points of anchorage.

Obviously those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as defined by the claims hereto appended, and I therefore'wish not to be restricted to the precise construction herein disclosed.

Having thus described and shown an embodiment of my invention, what I desire to secure by Letters Patent of the United States is:

1. In apparatus of the class described, the combination with a vibratory deck, of a screen comprising a plurality of strands of wire, and means for supporting said screen on said deck comprising an elongated block of hard rubber carried by a support with a strip of relatively soft rubber vulcanized to the top of said elongated block of hard rubber and provided with spacedapart parallel grooves for receiving said strands of wire, such vulcanization serving to hold said parallel grooves in their proper relationship.

2. In apparatus of the class described, the combination with a vibratory deck, of a screen comprising a plurality of parallel strands of wire, and means for supporting the screen on said deck comprising a grooved soft rubber connecting strip for receiving said strands of wire, said strip being vulcanized to a block of hard rubber vulcanized to a base strip of metal, such vulcanization serving to unite said base strip of metal and said block of hard rubber and said soft rubber connecting strip into a single unit with the grooves in the soft rubber strip maintained in their proper relationship.

3. In apparatus of the class described, the combination with a vibratory deck, of a screen comprising a strip connecting a plurality of parallel strands of wire, means for supporting the screen on said deck comprising an elongated block of relatively hard rubber, and a layer of relatively soft rubber vulcanized to the top of said elongated block and of the same width as the latter, the said layer of relatively soft rubber being provided with parallel spaced apart grooves to receive the said parallel strands of wire and serve as a connecting strip intermediate the ends of the screen.

4. In apparatus of the class described, the combination with a vibratory deck, of a screen comprising a plurality of parallel strands of bare wire, and means for supporting the screen on said deck comprising an elongated removable block of relatively hard rubber with a grooved strip of relatively soft rubber permanently vulcanized to said elongated block in position to extend entirely across the screen for receiving the strands of bare wire, the permanent vulcanizing of said strip to said block serving to maintain the grooves in the strip in spaced parallelism to in turn enable the wires to be retained in spaced parallelism and further to form a unit adapted to be removed from the deck.

5. In apparatus of the class described, the combination with a vibratory deck, of a screen comprising a plurality of parallel strands of wire, and means for supporting the screen on the deck comprising a grooved soft rubber connecting strip for receiving said strands of wire, said strip being vulcanized to a block of hard rubber and the latter vulcanized to a base strip of metal, said block and strips forming a removable elongated unit.

6. In apparatus of the class described, the combination with a vibratory deck, of a screen comprising a plurality of strands of Wire, of

- means for supporting said screen on said deck comprising an elongated block of hard rubber with a strip of relatively soft rubber vulcanized to the top of said elongated block of hard rubber and provided with spaced-apart parallel grooves for receiving said strands of wire, such vulcanization serving to maintain the grooves in predetermined spaced relation by reason of the per manent securing of said soft rubber to said block of hard rubber.

RICHARD D. HELLER.

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