This invention relates to a screen assembly for separating materials and, more particularly, to a screen assembly that prevents the vibrations from reaching the structural support.
Screens are used in the aggregate business for separating rock, crushed rock, gravel, sand, and the like (herein referred to as “material”) into various sizes. Screens typically comprise one or more screen decks containing a perforated screening medium that acts as a sieve, through which the material is separated. A charge of material is deposited on the receiving end of the screen deck and, as the material is conveyed to the discharge end, smaller material falls through the openings, leaving the larger material retained on the screen deck.
Screens generally use a vibrating mechanism to assist in the separation process, as well as in the conveyance of the material towards the discharge end. The assembly typically includes a screen box having a screen deck and a common frame. Generally, the screen box is vibrated by a vibrating mechanism that is coupled to the common frame. The vibratory motion promotes stratification in the material bed, bringing the smaller material down to the screening medium surface to pass through the openings.
Vibrating mechanisms may be characterized by the form of the vibration and the number of bearings used in the mechanism. Vibrating mechanisms may produce motions that include circular, elliptical, and straight-line reciprocal movement. For example, a suspended double eccentric screen utilizes a counter weight on a shaft to vibrate the screen box, and consequently the screen deck, in a circle-throw motion. The material is propelled toward the discharge end by the motion of the vibrating mechanism.
Typically, the screen box for a suspended double eccentric screen is isolated from the support structure by coil springs, rubber buffers, or shear rubber mounts. Such support systems are costly and require a great deal of space, which may restrict maintenance access. In addition, such mounts generally have a high tolerance in shear rates and do not sufficiently restrict lateral movements that can damage machinery components such as bearings and shafts. Further, conventional springs often break in corrosive environments and on overloading. Therefore, there is a need for a screen and support system that allows a more cost-effective design, is easier to maintain, requires less space, has a longer service life, and restricts lateral movements in the support system.
Additional information will be set forth in the description that follows, which will be obvious in part from the description or may be learned by practice of the invention.
A screen assembly for separating material according to particle size is provided. The screen assembly may have a base, a screen box having a screen medium and a pair of mutually opposed bearings, a shaft having a pair of eccentric journals that are rotatably supported in the respective pair of mutually opposed bearings. The shaft is rotatable about its axis to vibrate the screen box. At least one articulated suspension assembly having a first leg having a first torsion joint and a second torsion joint, a second leg having a third torsion joint and a fourth torsion joint, and a third leg having a first end pivotably secured to the second torsion joint and a second end pivotably secured to the third torsion joint, pivotally interconnects the screen box and the base so that the first torsion joint is pivotally secured to the screen box and the fourth torsion joint is pivotally secured to the base so that vibrations acting upon the screen box are dampened so that substantially no vibrational forces are transmitted to the base.
Operation of the invention may be better understood by reference to the following detailed description taken in connection with the following illustrations, wherein:
While the present invention is described with reference to the embodiments described herein, it should be clear that the present invention should not be limited to such embodiments. Therefore, the description of the embodiments herein is illustrative of the present invention and should not limit the scope of the invention as claimed.
Reference will now be made in detail to the embodiments of the invention, as illustrated in the accompanying figures. Embodiments of a screen assembly 10 are shown in
As shown in
It is understood that a plurality of screen decks 25 may be used in a stacked arrangement in the screen box 20, one above the other, to separate material into multiple sizes. In one embodiment (not shown), a three-deck screen may be provided with an upper, middle, and lower screen deck, the upper screen deck having the largest openings, the middle screen deck having smaller openings, and the lower screen deck having the smallest openings. In such embodiments, the larger material is retained on the upper screen deck and removed from the screen deck at the upper discharge end. Likewise, the medium-sized material is retained on the middle screen deck and removed from the screen deck at the middle discharge end, the smaller size material is retained on the lower screen deck and removed from the screen deck at the lower discharge end, and the smallest material is deposited below the lower screen deck.
As best shown in
As shown in
One or more balance (or fly) wheels 75 may be provided on shaft 30 to balance the screen assembly 10. In one embodiment, the balance wheels 75 may be positioned along the shaft 30 on either side of the screen box 20 to dynamically balance the screen assembly 10. In one embodiment, as best shown in
As best shown in
Turning now to the screen assembly 10, an example of how to use the screen assembly 10 as illustrated in
The combination of the articulated suspension assemblies 35, 40 with a suspended eccentric screen provides an unique suspension system, which combines the functionality of springs, dampers, and bearings. As shown in
In addition, due to the free-floating configuration of the screen box 20 and the 180 degree offset of the journals 55, 60, the dynamic reaction forces resulting from the circular motion of the screen box 20 are directionally opposite to the dynamic reaction forces of the bearings 70. Therefore, the dynamic reaction forces acting on suspension assemblies 35, 40 cancel each other out, thereby allowing no substantial dynamic reaction forces to be transmitted from the base frame 80 to the supporting structure 85.
Accordingly, use of the articulated suspension assemblies 35, 40 with a suspended double eccentric screen box 20 provides spring rates with lower tolerances than those of shear rubber mounts and increases the accuracy of the suspension system, which in turn extends the life of machinery components such as the shaft 30 and bearings 65, 70. The overall dimensions of the articulated arm suspension assemblies 35, 40 are smaller than the commonly-used shear rubber mounts, thereby decreasing the vertical clearance necessary to install the screen assembly 10. Additionally, the top and bottom base members 100, 105 provide a less complicated design, allowing for easy installation and removal of the suspension assemblies 35, 40.
The invention has been described above and, obviously, modifications and alternations will occur to others upon the reading and understanding of this specification. The claims as follows are intended to include all modifications and alterations insofar, as they come within the scope of the claims or the equivalent thereof.
This application claims priority from U.S. Provisional Patent Application No. 60/815,403 entitled “Suspended Double Eccentric Screen,” filed on Jun. 21, 2006, which is hereby incorporated by reference herein.
Number | Name | Date | Kind |
---|---|---|---|
2009219 | Blackburn | Jul 1935 | A |
2225444 | Gary | Dec 1940 | A |
2230316 | Wolz | Feb 1941 | A |
2335425 | Kouyoumjian | Nov 1943 | A |
2509769 | Hirst | May 1950 | A |
2659487 | Caler | Nov 1953 | A |
2821292 | Spurlin | Jan 1958 | A |
3003635 | Wood | Oct 1961 | A |
3347373 | Dahlberg | Oct 1967 | A |
3473396 | Schwake | Oct 1969 | A |
4486302 | Jorgensen | Dec 1984 | A |
4661245 | Rutherford et al. | Apr 1987 | A |
4819810 | Hoppe | Apr 1989 | A |
4839036 | Slesarenko | Jun 1989 | A |
4960510 | Wolff | Oct 1990 | A |
5341939 | Aitchison et al. | Aug 1994 | A |
5361911 | Waites, Sr. et al. | Nov 1994 | A |
5377846 | Askew | Jan 1995 | A |
5735409 | Malmberg | Apr 1998 | A |
5829599 | Woodgate | Nov 1998 | A |
5868259 | Bielagus | Feb 1999 | A |
5899340 | MacNaughton | May 1999 | A |
5984107 | Bleh | Nov 1999 | A |
6003682 | Bielagus | Dec 1999 | A |
6082551 | Kai | Jul 2000 | A |
RE38303 | Askew | Nov 2003 | E |
6827223 | Colgrove et al. | Dec 2004 | B2 |
6889846 | Olsen et al. | May 2005 | B2 |
6957741 | Freissle et al. | Oct 2005 | B2 |
6988624 | MacNaughton | Jan 2006 | B2 |
7445121 | Mainin et al. | Nov 2008 | B2 |
Number | Date | Country |
---|---|---|
4140210 | Jun 1993 | DE |
2037618 | Jul 1980 | GB |
Number | Date | Country | |
---|---|---|---|
20080011652 A1 | Jan 2008 | US |
Number | Date | Country | |
---|---|---|---|
60815403 | Jun 2006 | US |