US 1999769 A
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Description (OCR text may contain errors)
pm 30, i935. c. s. LINCOLN VIBRATING SCREEN Filed Sept. 16, 1932 Patented Apr. 30, i935 UNITD TATES PATE rice VIBRATIN G SCREEN Charles S. Lincoln, Wauwatosa, Wis., assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Application September 16, 1932, Serial No. 633,395
of the longitudinal extreme side portions thereof supported cantilever-wise from the side walls of a pair of spaced walls or of a screen body and with the medial longitudinal portions of the screen held at the desired elevations and restrained against movement in one direction by a suitable skeleton frame also associated with said walls or screen body.
It has been recognized by the art that lateral l tensioning of a screen mounted in a screen body such that all points of the screen move in a single plane is not the most satisfactory, especially in the wider screens. Further, it has been appreciated that to support medial longitudinal portions of a screen at desired elevations to form a certain crowning of these portions of the screen is desirable in connection with lateral tensioning devices for the screen and such tensioning should preferably be carried out in the curvature determined by the medial longitudinal portions of the screen held, as aforesaid, at desired elevations and against movement in one direction. When such a screen is insuiciently tensioned the ordinary dangers due to the vibrating mechanism may be met with. The wires of ythe screen would become loose allowing them to whip and thus the wires would soon become destroyed through fatigue or other forces generated in the screen when the vibrating screen is in operation. i It is, therefore, the prime purpose of this inention to provide in connection with a screen body, screen tensioning and crowning devices each employing a lever plate of the said cantilever type suspended from the side walls of the screen body, and further being of such a nature that all the elements of the device may at all times be em.- ployed and irrespective of the thickness of the wire said device effects a desired and sufficient lateral tensioning of the screen while maintaining with the extreme longitudinal side portions of the 'screen a continuation of the crown as determined by the medial portions of the screen held in the desired crown position by suitable longitudinal bars of a skeleton frame also supported within the screen body.
Another object of this invention is to provide a screen adjusting and crowning device as above described whereby the adjustable feature as to tensioning and as to crowning may readily be carried' out from the exterior portions of the screen body.
Another object of the invention is to provide a screen tensioning and crowning device which is readily adaptable to any existing form of screen bodies supporting present screens, which is relatively simple, inexpensive to manufacture and highly successful for the purposes for which it was devised.
Other objects and advantages of this invention `will appear from a consideration of the description given in the specication and of the drawing forming a part of the specification and on which the same reference numerals have been employed to designate like parts throughout the various views. l
Fig. 1 is a transverse sectional View through a screen body provided with the novel screen tensioning and crowning devices of this invention.
Fig. 2 is an enlarged fragmentary sectional view through the portion of the novel device which anchors the lever plates to the side walls of the screen body.
Fig. 3 is a corresponding fragmentary sectional View of a modified form of screen tensioning and crowning device constructed according to this invention.
Fig. 4 is a fragmentary sectional view corresponding to Figs. 2 and 3 and illustrates a still further and simpler modification of the screen tensioning and crowning device of this invention.
Referring to Fig. 1, the screen body l vibrated through any suitable means and constituting a vibrating screen device, comprises side walls 2 having a suitable number of pairs of angle irons 20 at different elevations to provide support for more than one deck of screen. The pairs of angle irons 20 Secured to the side walls 2 of the screen body l may be used to carry a skeleton frame 3 having a middle longitudinal bar and two other longitudinal bars equally spaced therefrom but each at the same lower elevation than said middle bar and these bars 4 are employed to restrain the movement of the screen 5 resting thereon in a downward direction and to support the medial portions of said screen 5 at the desired crown curvature. The extreme side portions 0f the screen are each shown as directly engaged by a pair of marginal grip bars 6 on the upper one of which are positioned hook bars l and each hook bar l, as well as the corresponding pairs of grip bars 6, is rigidly secured to the corresponding side portion of screen 5 by means of suitable bolts I9. It is to be understood, however, that in case the individual wires constituting the screen 5 are sufficiently stiff and rigid that the function of the hook bars l may be executed directly by suitably bent portions of the screen 5 itself. In order to suspend the extreme side portions of the screen 5 from the side walls 2 of the screen body I each hook bar 'I is engaged by a horizontal leg of a lever plate 8 which extends for the entire length of the side walls 2 of the screen body I and which is bent transversely as shown and whose upper or other end is received within a slot I8 in a novel anchoring means forming a portion of the instant novel screen tensioning and crowning devices. Each anchoring means in Fig. 1 is shown to be comprised of a half oval bar 2I also extending the full length of the side walls 2 of the screen body I and provided with the slot I8, as stated above, which slot also penetrates the inner portions of stud bolts I5, suitably distributed along the length of the side walls of the screen body and passing through suitable elongated apertures therein. The inner ends of these bolts are firmly related to the half oval bars 2|. The openings in the side walls 2 receiving the stud bolts I5 are substantially longer than the diameter of said stud bolts to permit adjustments of said bolts with respect to the hook bars I, in a vertical direction, and therefore these openings have their lengths directed vertically with respect to the side walls`2 of the screen body. The intermediate portions of the stud bolts I5 are further somewhat loosely received by openings in individual washer plates I6 and the outer screw threaded ends thereof are adapted for coaction with suitable nuts to firmly clamp the washer plates against the side walls 2 and to retain each oval bar 2I in the selected and required position. In order to enhance said function the inner surfaces of the washer plates I6 are preferably knurled as clearly shown in Fig. 2. Bolts 9 for actuating each lever plate 8 to effect the desired transverse tensioning of the screen 5, are passed through openings in the intermediate portions of the lever plates 8, and through means about to be described preferably held in horizontal positions, and also passed through openings elongated in the vertical direction and in this direction of the same extent as the openings for receiving the stud bolts I5, above described. The bolts 9 further, as do the stud bolts I5, are loosely confined within registering openings in the individual washer plates I6 and through the action of nuts at the threaded outer ends of bolts 9 the effective screen tensioning through said bolts 9 is varied through the intermediary of a tension spring interposed between each washer plate and the nuts at the outer end of the bolts 9.
Considering the elevation of the two outer bars 4 and that they are lower than the middle bar 4, it will be understood that said bars providing a certain crown curvature for the intermediate portions of screen 5 and assuming a certain thickness of screen 5 and the retention of the described hook bars 'l and pairs of marginal grip bars 6 cooperating with each side portion of the screen 5, that with the lever plates 8 received within the slots I8 of the oval bars 2l in a certain position thereof, that the extreme side portions of the screen 5 may be tensioned through the tensioning devices described substantially in the line of curvature of the crown of the intermediate portions of the screen.
However, should a thicker screen be used, assuming further the same setting of the oval bars 2| and the use of the same lever plates, and the same hook bars and the marginal grip bars 6 associated with the side portions of the thicker screen 5, it will be found that the extreme side portions of the screen 5 would under this assumed condition be tensioned at a curvature differing considerably from the curvature xed by the bars 4. However, while retaining this thickness of ,new screen 5 the novel devices permit upon loosening of the nuts from the stud bolts I5 and loosening of the nuts on the bolts 9 of an elevating displacement of the lever plates 8 together with the extreme side portions of the screen 5 to a position of the extreme side portions of the screen 5 in whicli`-the screen may then be tensioned substantially'lin the fixed curvature or as definitely determined by the bars 4 supporting the intermediate portions of the screen 5.
On the other hand, assuming that a thinner screen than that first described were to replace the screen 5 under conditions remainingr the same as at rst described, it would be found that the extreme side portions of the screen 5 would again be in a different curvature and again not in line with that determined for the intermediate portions of the screen by the bars 4. In order, therefore, under this condition also to bring the side portions of the screen 5 at the curvature determined by the bars 4 it would merely be necessary to drop the lever plates 8, through manipulation of the nuts on bolts 9 and I5, by the desired amount.
Fig. 2 shows in detail a stud bolt I5 associated with an oval bar 2| as above described, the stub bolt I5 and oval bar 2l being provided with a common slot I8. This figure also clearly shows the knurls in the inner face of the shown washer plate I6, the face thereof which directly engages the surface of the side wall 2.
Fig. 3, rather than the composite means for anchoring the lever plates 8 to bars as in the modification of Fig. 1, shows distinct ilat anchor plates 24 each provided with a slot I8. The low'- er portion of each anchor plate 24 is provided with suitable openings sufficiently large to receive conventional bolts 25 which firmly grip together the anchor plate 24, the side wall 2 of the screen body I and the several washer plates I6. A suitable number of bolts 9 for actuating each lever plate 8 pass through elongated openings corresponding to the elongated openings in the side walls 2 through which the said conventional bolts 25 pass and these openings are of the dimensions ofthe corresponding openings provided in the side walls 2 for the modification shown in Fig. 1. This gure also illustrates that, as stated above, when the wires constituting the screen are suiiciently stiff and rigid that the function of the distinct hook bars 'I of Fig. 1 may be carried out by suitable hook portions provided in the side portions of the screen 5 itself.
Fig. 4 shows a stili further modification of the novel tensioning and crowning device of this invention and of simpler construction in that the distinct oval anchor bars 2I of the modication of Fig. 1 and of the anchor plates 24 of the modification of Fig. 3, as separate elements are dispensed with and the function carried out by these separate anchor bars and plates of the modification of Figs. 2 and 3 is performed directly bythe slotted head portions of conventional bolts 35 distributed lengthwise as desired along the side walls 2 of the screen body I. Obviously the slots I8 in the slotted conventional bolts 35 of this modification are preferably not extended to reach the shank or stem portions of the bolts. If they are not, even though the lever plates 8 extend throughout the length of the side walls 2 of the screen body I, it. will be seen that spaces exist between the inner surfaces of the side walls 2 and the extreme upper edges of the lever plates 8 permitting the passage of some material therethrough, which disadvantage in certain cases would have little if Vany appreciable detrimental consequences. However, in order to 'avoid these spaces the edges concerned of the lever plates 8 may be provided with suitable notches to clear the head of the conventional bolts 35. The slotted heads of these bolts 35 may be detachably associated with the stems.
From the above it is seen that applicant has provided various modifications of a novel screen tensioning and crowning device associable with the side walls of screen bodies and said devices cooperating with medial longitudinal bars engaging the intermediate longitudinal portions of a screen 5, readily permitting the association within said screen body of screens of diferentgthicknesses and'irrespective of the thickness selectedfor a particular screen and without the elimination of the use of any element constituting the screen tensioning and crowning devices that any screen may be desirably positioned and then tensioned to bring the extreme side portions thereof in one and the same crown, i. e. that determined, once and for all, by the elevation of the intermediate and two outside bars 4, supported from the skeleton frame 3.
It is to be understood that the invention is not to be limited to the exact details of the construction shown and described for various modications within the scope of the claims may occur to persons skilled in the art to which the invention appertains.
It is claimed and desired to secure by Letters Patent:
1. In combination, a side wall of a screen member, a slotted anchor member engaging said wall, a lever plate having an edge received in said slot, a perforated Washer plate also engaging said wall, means passing through said Wall and washer plate for positively urging a portion of said lever plate towards said `wall, said anchor member being adjustably locatable with said washer plate and said means along said wall, and means for securing the anchor member in the desired location, to the side wall.
2. In combination, a sidewall of a screen member, said wall being provided with pairs of perforations, a longitudinally slotted anchor member engaging said wall, a lever plate having an edge received in said slot, a plurality of perforated, knurled washer plates each engaging said wall and each overlying a pair of said pairs of perforations in 'said wall, means passing through each corresponding one of said pairs of perforations in said wall and through a corresponding washer plate for positively urging a portion of said lever plate toward said wall, said anchor member being adjustably locatable with each washer plate and said means along said wall, and means for securing the anchor member in the desired location to the side Wall.
3. In combination with a side wall of a screen body, a slotted anchor member engaging said Wall, a lever plate having an edge received in said slot, a perforated vwasher plate also engaging said wall, means passing through said wall and said washer plate for positively urging a portion of said lever plate toward said wall, and means passing through said Washer plate and side wall and engaging said anchor member for adjustably locating said anchor member along said Wall and xedly securing it to said wall.
4. In a screening mechanism, the combination with a screen frame including side walls and a central screen supporting element, of a screen carried by said supporting element with its respective edges adjacent to said side walls, and vertically adjustable screen suspending means carried by each side wall in position to engage the respective edges of said screen and adapted to tension it and to regulate its slope over said supporting element, said screen suspending means each including a washer plate mounted for vertical adjustment on the corresponding frame side wall, a fulcrum member and a tensioning member carried in predetermined spaced relation by said washer plate, and a lever plate engaging the adjacent edge of said screen with' one edge and said fulcrum member with the other edge and engaged by said tensioning member at an intermediate position and urged thereby toward said side wall to tension'said screen, said lever plate being movable vertically upon simultaneous vertical movement of said fulcrum member and said tensioning member by said washer plate to regulate the slope of said'screen.
Y CHARLES S. LINCOLN.