Patent Application
20200078826
The invention relates generally to vibratory screens. More particularly, the present invention relates to a mechanism for exchanging compliant members of vibrating screen.
With initial reference to
Material to be classified by particle size flows across the length of each screen deck 102, and generally, at least some of it passes through the sizing media 108 as the impulse mechanism vibrates the screen deck 102. The vibrations imparted to the screen deck 102 cause material small enough to pass through the media 108 to pass through to a lower screen deck or transfer chute or conveyor. It also helps to convey the material across the screen deck 102 and prevents material build-up on the sizing media 108.
The screen frame 104 is supported by compressible compliant members 112, which are commonly formed from metal or elastomer springs, which isolate the screen frame 104 from a screen base 114. A compliant member 112 is positioned below each of one or more bracket assemblies 116 located on or near each corner of screen frame 104. Bracket assemblies 116 include a back plate 118 to which are attached a pair of spaced apart side stiffeners 120. A stationary contact plate 122 is fixedly attached to the back plate 118 and extends between and is connected to a bottom end of the side stiffeners 120. Bracket assemblies 116 are configured to transfer forces between the compliant members 112 and the side plates 106. The compliant members 112 are configured to compress as a compression force, such as the weight of screen frame 104 or a vibrational force, is applied to them and to decompress as the compression force is removed or is eliminated. Compliant members 112 are configured to compress between the base surface 114 and the contact plate 122. Compliant members 112 compress to an equilibrium point, where the downwardly-directed force (e.g., the weight of screen frame 104) is equivalent to the combined upwardly-directed forces of all the compliant members. The number of compliant members 112 is dependent on the mass of the screen frame 104 and the stiffness of the compliant members 112.
At times, compliant members 112 may require replacement due to wear or to change the stiffness of the vibratory screen 100, or for other reasons. Typically, when beginning the exchange process, compliant members 112 are under compression due to the weight of the screen frame 104. The compliant members 112 store potential energy when compressed and an uncontrolled release of that energy could cause serious injury or damage. Thus, in order to safely exchange compliant members 112, the potential energy should be released prior to beginning the exchange process.
One conventional method for releasing the potential energy stored in the compliant members 112 is to convert the stored potential energy to gravitational potential energy by raising the screen frame 104 off of some or all of the compliant members. Raising the screen frame 104 allows the compliant members 112 to decompress, at which point the compliant members can be safely exchanged. Frequently, the lifting device used in raising the screen frame 104 is a counterweighted crane or a mechanical jack. Such lifting devices may require several operators working in tandem to complete the task of exchanging the compliant members 112. These lifting devices also may not be readily available at the locations which the vibratory screen assemblies 100 are located. Consequently, replacing compliant members 112 in a screen frame 104 according to conventional methods may require significant down time as the proper equipment is re-located. Additionally, raising a screen frame 104 with respect to screen base 114 is inherently dangerous due to the potential of the screen frame falling.
What is needed, therefore, is a method and apparatus that enables compliant members to be quickly and easily swapped without requiring raising the screen frame.
The use of the terms “a”, “an”, “the” and similar terms in the context of describing embodiments of the invention are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising”, “having”, “including” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. The terms “substantially”, “generally” and other words of degree are relative modifiers intended to indicate permissible variation from the characteristic so modified. The use of such terms in describing a physical or functional characteristic of the invention is not intended to limit such characteristic to the absolute value which the term modifies, but rather to provide an approximation of the value of such physical or functional characteristic.
Terms concerning attachments, coupling and the like, such as “attached”, “connected” and “interconnected”, refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both moveable and rigid attachments or relationships, unless otherwise specified herein or clearly indicated as having a different relationship by context. The term “operatively connected” is such an attachment, coupling or connection that allows the pertinent structures to operate as intended by virtue of that relationship.
The use of any and all examples or exemplary language (e.g., “such as” and “preferably”) herein is intended merely to better illuminate the invention and the preferred embodiments thereof, and not to place a limitation on the scope of the invention. Nothing in the specification should be construed as indicating any element as essential to the practice of the invention unless so stated with specificity.
The above and other needs are met by an apparatus for use in replacing a compliant member of a vibratory screen assembly. As described above, when supporting the vibratory screen assembly, compliant members are compressed between a base surface and a movable contact plate of the vibratory screen assembly and potential energy is stored by the compliant members as a result of the compression. In a preferred embodiment of the present invention, the apparatus includes an exchanging plate and connectors that hold the exchanging plate at a selectively adjustable distance away from the contact plate. The potential energy stored by the compliant member may be decreased by increasing the distance between the exchanging plate and contact plate by adjusting the connectors. The compliant member may be safely removed and exchanged by eliminating all compression in the compliant member using the exchanging plate.
Certain preferred embodiments of the present invention provide a screen assembly system. The system includes a vibratory screen assembly configured to classify and separate material into two or more differently-sized products based on the size of the material. Bracket assemblies mounted to the vibratory screen assembly include a movable contact plate and a compliant member. The compliant member compresses between a base surface and the movable contact plate when supporting the screen assembly. The compliant member stores potential energy as a result of that compression. The system also includes exchanging plates and connectors. The connectors connect one of the exchanging plates to one of the contact plates and hold the exchanging plate at a selectively adjustable distance away from the contact plate. The potential energy stored by the compliant member may be increased by decreasing the distance between the contact plate and the exchanging plate. Increasing the potential energy stored in one of the compliant members reduces the potential energy stored in the other compliant members. Conversely, the potential energy stored by the compliant member may be decreased by increasing the distance between the contact plate and the exchanging plate. Decreasing the potential energy stored in one of the compliant members increases the potential energy stored in the other compliant members. The potential energy stored in a compliant member may be reduced entirely until the compliant member is no longer compressed and, at that point, the compliant member may be safely removed. Preferably, the bracket assemblies are arranged and configured such that, after the potential energy stored by the compliant member of at least one bracket assembly is decreased entirely, the vibratory screen assembly can be entirely supported by the remaining bracket assemblies.
A preferred embodiment of the present invention provides a method for removing a compliant member from a vibratory screen assembly. The method includes the steps of providing a vibratory screen assembly having a plurality of bracket assemblies, connecting a movable contact plate to each bracket assembly at a selected vertical position such that the contact plate is prevented from moving vertically, and supporting the vibratory screen frame above a base surface by compressing compliant members between the base surface and each of the contact plates. Potential energy stored by the compressed compliant members is equivalent to the weight of the frame such that the frame is located at a first equilibrium vertical position. The method further includes the steps of removably connecting an exchange plate to a selected one movable contact plate at a selectively adjustable distance via one or more connectors and disconnecting the selected one movable contact plate from the bracket assembly such that the contact plate can move vertically within the bracket assembly. The method further includes the steps of increasing the distance between the exchange plate and the selected one movable contact plate until the compliant member is decompressed, removing the decompressed compliant member from between the base surface and the selected one movable plate, and supporting the vibratory screen frame above the base surface by compressing the remaining compliant members between the base surface and the contact plates. Potential energy stored by the remaining compressed compliant members is equivalent to the weight of the screen frame such that the screen frame is located at a second equilibrium vertical position that is different from the first equilibrium vertical position.
Further advantages of the invention are apparent by reference to the detailed description when considered in conjunction with the figures, which are not to scale so as to more clearly show the details, wherein like reference numerals represent like elements throughout the several views, and wherein:
Referring now to
Like bracket assembly 116 (shown in
Additionally, in preferred embodiments, exchange plates 200 are removably attached to the bracket assembly 202 using a plurality of threaded connectors 204. Connectors 204 are preferably inserted through openings 207 formed in contact plate 205 and corresponding openings 206 formed in each of the exchange plates 200 and then held securely by a nut (not shown). These aligned openings 207, 206 are shown best in
By connecting exchange plates 200 to contact plate 205 with connectors 204, the compression in compliant member 112 mounted to a vibrating screen frame 104 may be relieved in a controlled, gradual fashion and without requiring the vibrating screen assembly to be lifted. Relieving this compression without lifting the vibrating screen frame 104 enables the compliant member 112 to be exchanged more easily and in a much safer and faster manner than was previously possible.
When in use, exchanging plates 200 are preferably placed on opposing sides of the compliant member 112 (e.g., front and back) and are sized and configured to substantially surround the compliant member. Preferably, the plates 200 are sized to fit between the compliant member 112 and the side plate 106 of the screen frame 104. While a single exchange plate 200 could be used, the installation process is simplified using a pair of separate plates, as shown. Each plate 200 preferably has a curved inner face 208 (
With reference now to
The bracket assembly 202 of
Referring to
Once the exchanging plate 200 has been brought into contact with the bracket assembly 202, the fasteners 210 can be removed from both the side stiffeners 203 and the contact plate 205 by the operator. Removing the fasteners 210 disconnects the contact plate 205 from the bracket assembly 202, which allows the contact plate to move vertically with respect to the bracket assembly. More particularly, the contact plate 205 can move vertically within the vertical slot defined by the back plate 201 and the side stiffeners 203. This vertical movement is guided by the slot and the positioning of the contact plate 205 with respect to the bracket assembly 202 is determined by the connectors 204.
The force of the weight of the screen frame 104 is transmitted through the bracket assembly 202 downwards onto the exchanging plates 200. That force is then carried through connectors 204 up to contact plate 205. Finally, the force is then transmitted down to compliant member 112 via contact plate 205. Thus, the weight of the screen frame 104 is still borne (i.e., indirectly) by the compliant members 112, even though the bracket assembly 202 is not rigidly connected to the contact plate 205. Importantly, since the screen frame 104 is at the equilibrium point (i.e., the point where the entire weight of screen frame 104 is borne by the compliant members 112), the compliant members do not compress further when fasteners 210 are removed; rather, the compliant members 112 are already fully compressed under the weight of the screen frame 104.
Since the contact plate 205 is no longer mounted to the bracket assembly 202, the contact plate can be moved upwards between side stiffeners 203 if the compliant member 112 decompresses. Similarly, the contact plate 205 can be moved downwards between side stiffeners 203 if the compliant member 112 compresses (i.e., if connectors 204 were tightened further). However, when the fasteners 210 are first removed, the contact plate 205 remains stationary. The contact plate 205 does not move because the length of the compliant member 112 remains fixed by the connectors 204 connecting the contact plate to the exchanging plate 200 and by contact between the exchanging plates 200 and bracket assembly 202. As such, the compliant member 112 does not compress or decompress and the position of the contact plate 205 within the bracket assembly 202 remains fixed.
Referring to
As the weight of the screen frame 104 is transferred, the remaining compliant members 112 temporarily experience a greater compressive force and the equilibrium point of the screen assembly is lowered slightly as the compliant members compress further under the added weight. Once the compliant member 112 is fully decompressed, as shown in
In order for the new compliant member 112 to be installed, the above-described process is reversed. Once the new compliant member 112 has been correctly positioned below the contact plate 205, a portion of the potential energy stored in each of the remaining compliant members can be transferred to the replacement compliant member. The connectors 204 associated with the replacement compliant member 112 are gradually tightened until holes 212, 214 are aligned. This tightening process transfers potential energy from the other compliant members 112 to the new, replacement compliant member. At that point, fasteners 210 are re-inserted through openings 212, 214 and tightened in order to re-connect the contact plate 205 with the bracket assemblies 202. Connector 204 may then be loosened entirely and removed from contact plate 205 and bracket assemblies 202. Lastly, exchanging plates 200 may be removed, which returns compliant member 112 and screen frame 104 to regular operation.
With reference now to
An alternative embodiment is illustrated in
Although this description contains many specifics, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments thereof, as well as the best mode contemplated by the inventor of carrying out the invention. The invention, as described herein, is susceptible to various modifications and adaptations as would be appreciated by those having ordinary skill in the art to which the invention relates.
This application claims the benefit of U.S. Provisional Patent Application No. 62/729,604, filed on Sep. 11, 2018 and entitled MECHANISM FOR EXCHANGING COMPLIANT MEMBERS OF VIBRATING SCREENS, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62729604 | Sep 2018 | US |
