Patent Description:
Material screening includes the use of vibratory screening machines. Vibratory screening machines provide the capability to excite an installed screen such that materials placed upon the screen may be separated to a desired level. Oversized materials are separated from undersized materials. Over time, screens wear and require replacement. As such, screens are designed to be replaceable.

Vibratory screening machines and their replaceable screens have several drawbacks that limit their productivity and use. In vibratory screening machines, the material to be separated is placed on flat or corrugated replaceable screens. The replaceable screens are tensioned over a surface of the vibratory screening machine such that the replaceable screen tightly fits on the machine. A tensioning arrangement is provided with the machine and is used to provide a tensioning force on the screen. Several techniques are used to tension screens on vibratory screening machines. One technique includes the use of special attachment hooks that grip the sides of the screen and pull it onto a surface of the machine. Replaceable screens have a substantially planar screen area and material often builds up at the screen edges causing maintenance and contamination problems.

<CIT> discloses a screen assembly in accordance with the preamble of claim <NUM>, in particular it relates to a trommel with screen panels.

<CIT> discloses screen elements of polyurethane, or a material having similar characteristics, having metal reinforcing rods embedded in and extending only in a single direction and across the full width of the screen element between lateral support zones.

<CIT> discloses a screen assembly for a vibratory shaker, the screen assembly including at least two screening members, and the at least two screen members connected by sewing material.

<CIT> discloses screen apparatus comprising side walls having a lower edge portion configured to accept tubular screen support members.

The invention is defined by a screen assembly in accordance with claim <NUM>.

In an example embodiment, a vibratory screening machine is provided that simplifies the process of securing a replaceable screen to the machine. The vibratory screening machine and replaceable screen prevent materials to be separated from flowing over the sides of the screen. The replaceable screen is designed to be cost effective and can be quickly installed on the vibratory screening machine.

According to an example embodiment, a vibratory screen machine includes: wall members, a concave support surface, a central member attached to the support surface, a screen assembly, a compression assembly and an acceleration arrangement. The screen assembly includes a frame having a plurality of side members and a screen supported by the frame. The screen includes a semi-rigid support plate and a woven mesh material on a surface of the support plate. The compression assembly is attached to an exterior surface of a wall member. The compression assembly includes a retractable member that advances and contracts. The acceleration arrangement is configured to impart an acceleration to the screen. As the retractable member advances it pushes the frame against the central member forming the screen assembly into a concave shape against the concave mating surface. The top surface of the screen assembly forms a concave screening surface.

According to an example embodiment, a vibratory screen machine includes: a screen assembly; and a compression assembly. The compression assembly deforms a top surface of the screen assembly into a concave shape.

The screen assembly may include a frame having a plurality of side members and a screen supported by the frame. At least one side member may be at least one of a tube member, a formed box member and a formed flange.

The vibratory screen machine may include a wall member. The compression assembly may be attached to at least one wall member and may be positioned on an exterior of a wall member.

The vibratory screen machine may include an acceleration or vibration arrangement configured to impart an acceleration to the screen assembly.

The vibratory screen machine may include a support surface wherein the screen assembly forms a concave shape against the support surface.

The vibratory screen machine may include a central member. The screen assemblies may be arranged between the central member and wall members. The central member may be attached to the support surface. The central member may include at least one angled surface configured to urge the screen assembly into a concave shape in accordance with the deformation of the screen assembly by the compression assembly. A side member may be in contact with the central member and another side member may be in contact with the compression assembly.

The vibratory screen machine may include at least one additional screen assembly having a second frame having a plurality of second side members and a second screen supported by the second frame. A second side member of the additional screen assembly may be in contact with the central member and a side member of the screen assembly may be in contact with the compression assembly. The top surfaces of the at least two screen assemblies may be formed into a concave shape.

The vibratory screen machine may include a second compression assembly and a second screen assembly including a plurality of second side members. A second side member may be in contact with the central member and another second side member may be in contact with the second compression assembly.

The vibratory screen machine may include a mating surface configured to contact the screen assembly. The mating surface may include at least one of rubber, aluminum and steel. The mating surface may be a concave surface.

The at least one compression assembly may include a pre-compressed spring that is configured to assert a force against the screen assembly. The pre-compressed spring may assert a force against at least one side of the frame.

The compression assembly may include a mechanism configured to adjust the amount of deflection imparted to the screen assembly. The amount of deflection imparted to the screen may be adjusted by a user selectable force calibration.

The compression assembly may include a retractable member that advances and contracts. The retractable member may advance and contract by at least one of a manual force, a hydraulic force and a pneumatic force.

The vibratory screen machine may include at least one additional compression assembly. The compression assemblies may be configured to provide a force in the same direction.

According to an example embodiment, a screen assembly for a vibratory screening machine includes: a frame including a plurality of side members and a screen supported by the frame. The screen assembly may be configured to form a predetermined concave shape when placed in the vibratory screening machine and subjected to a compression force by a compression assembly of the vibratory screening machine against at least one side member of the screen assembly. The predetermined concave shape may be determined by a surface of the vibratory screening machine.

At least two side members may be at least one of tube members, box members and formed flanges.

The screen assembly may include a mating surface configured to interact with a surface of the vibratory screening machine. The mating surface may include at least one of rubber, aluminum and steel.

The screen may include a woven mesh material and the frame may include formed flanges on at least two sides.

The frame may include a perforated semi-rigid support plate and the screen may include a woven mesh material. The woven mesh material may be attached to the support plate by at least one of gluing, welding and mechanical fastening.

The screen may include at least two layers of woven mesh material.

The frame may include a semi-rigid perforated support plate and the screen may include at least two layers of a woven mesh material in an undulating shape. The at least two layers of woven mesh material may be attached to the support plate by at least one of gluing, welding and mechanical fastening.

The plate may include a semi-rigid perforated support plate and the screen may include at least three layers of a woven mesh material in an undulating shape. The at least three layers of woven mesh material may be attached to the support plate by at least one of gluing, welding and mechanical fastening.

According to an example embodiment, a method for screening materials includes: attaching a screen assembly to a vibratory screen machine and forming a top screening surface of the screen assembly into a concave shape. The method may also include accelerating the screen assembly. The method may also include returning the screen assembly to an original shape, replacing the screen assembly with another screen assembly and performing the attaching and forming steps on another screen assembly.

Like reference characters denote like parts in the drawings.

<FIG> shows vibratory screening machine <NUM> with installed replaceable screening assemblies <NUM>. Material is fed into a feed hopper <NUM> and is then directed onto a top surface <NUM> of the screen assemblies <NUM>. The material travels in flow direction <NUM> toward the vibratory screening machine <NUM> end <NUM>. The material flowing in direction <NUM> is contained within the concave configuration provided by the screen assemblies <NUM>. The material is prevented from exiting the sides of screen assemblies <NUM>. Material that is undersized and/or fluid passes through screen assemblies <NUM> onto a separate discharge material flow path <NUM> for further processing. Materials that are oversized exit end <NUM>. The material stream may be dry, a slurry, etc., and the screen assemblies <NUM> may be pitched downwardly from the hopper <NUM> toward an opposite end in the direction <NUM> to assist with the feeding of the material.

Vibratory screening machine <NUM> includes wall members <NUM>, concave support surfaces <NUM>, a central member <NUM>, an acceleration arrangement <NUM>, screen assemblies <NUM> and compression assemblies <NUM>. Central member <NUM> divides vibratory screening machine <NUM> into two concave screening areas. Compression assemblies <NUM> are attached to an exterior surface of wall members <NUM>. Vibratory screening machine <NUM> may, however, have one concave screening area with compression assemblies <NUM> arranged on one wall member. Such an arrangement may be desirable where space is limited and maintenance and operational personnel only have access to one side of the vibratory screening machine. Also, multiple screening areas may be provided.

While vibratory screening machine <NUM> is shown with multiple longitudinally oriented screen assemblies creating two parallel concave material pathways, screen assemblies <NUM> are not limited to such a configuration and may be otherwise oriented. Additionally, multiple screening assemblies <NUM> may be provided to form a concave screening surface (see, e.g., <FIG>).

Screen assemblies <NUM> include frames <NUM> and screens <NUM>. Frames <NUM> include side members <NUM>. Side members <NUM> are formed as flanges but may be formed of any elongated member such as tubes, formed box members, channels, plates, beams, pipes, etc. Screens <NUM> may include a semi-rigid perforated support plate <NUM> and a woven mesh material <NUM> on a surface <NUM> of the support plate <NUM> (see, e.g., <FIG>). Support plate <NUM> need not be perforated but may be configured in any manner suitable for the material screening application. The woven mesh material may have two or more layers. The layers of a woven mesh material may be in an undulating shape. The woven mesh material may be attached to the semi-rigid support plate by gluing, welding, mechanical fastening, etc. Screens <NUM> are supported by frames <NUM>.

As discussed above, compression assemblies <NUM> are attached to an exterior surface of wall members <NUM>. Compression assemblies <NUM> include a retractable member <NUM> (see, e.g., <FIG>) that extends and contracts. Retractable member <NUM> is a pin but may be any member configured to exert a compressive force against frame <NUM> to urge side members <NUM> toward each other to deform screen assemblies <NUM> into a concave profile. As set forth below, retractable members <NUM> advance and contract by a pneumatic and spring forces but may also advance and contract by manual forces, hydraulic forces, etc. Also as set forth below, compression assembly <NUM> may be configured as pre-compressed springs (see, e.g., <FIG>). Compression assemblies <NUM> may also be provided in other configurations suitable for providing a force against screen assemblies <NUM>.

As shown in <FIG>, compression assemblies <NUM> include retractable members <NUM>, which are illustrated in <FIG> in an extended position asserting a force against frames <NUM>. Frames <NUM> are pushed against central member <NUM> causing screen assemblies <NUM> to form a concave shape against support surfaces <NUM>. Central member <NUM> is attached to support surface <NUM> and includes angled surfaces <NUM> (see, e.g., <FIG> and <FIG>) that prevent frames <NUM> from deflecting upward when they are compressed. Support surfaces <NUM> have a concave shape and include mating surfaces <NUM>. Support surfaces <NUM> may, however, have different shapes. Also, central member <NUM> need not be attached to support surface <NUM>. Additionally, vibratory screening machine <NUM> may be provided without support surfaces. Screen assemblies <NUM> may also include mating surfaces that interact with the mating surfaces <NUM> of support surface <NUM>. The mating surfaces of screen assemblies <NUM> and/or the mating surfaces <NUM> may be made of rubber, aluminum, steel or other materials suitable for mating.

Acceleration arrangement <NUM> is attached to vibratory screening machine <NUM>. Acceleration arrangement <NUM> includes a vibrator motor that causes screen assemblies <NUM> to vibrate.

<FIG> shows the side walls <NUM>, screen assemblies <NUM>, compression assemblies <NUM> and support members <NUM> of the vibratory screening machine <NUM> shown in <FIG>. Frames <NUM> of screen assemblies <NUM> include side members <NUM>. The side members <NUM> form flanges.

As described above, compression assemblies <NUM> are mounted to wall members <NUM>. Retractable members <NUM> are shown holding screen assemblies 20in a concave shape. Materials to be separated are placed directly on the top surfaces of screen assemblies <NUM>. Also as described above, the bottom surfaces of screen assemblies <NUM> may include mating surfaces. The bottom surfaces of screen assemblies <NUM> interact directly with the mating surfaces <NUM> of concave support surfaces <NUM> such that screen assemblies <NUM> are subjected to vibrations from acceleration arrangement <NUM> via, e.g., concave support surfaces <NUM>.

The placement of the top surfaces of screen assemblies <NUM> into a concave shape provides for the capturing and centering of materials. The centering of the material stream on screen assemblies <NUM> prevents the material from exiting the screening surface and potentially contaminating previously segregated materials and/or creating maintenance concerns. For larger material flow volumes, the screen assemblies <NUM> may be placed in greater compression, thereby increasing the amount of arc in the top surface and bottom surface. The greater the amount of arc in the screen assemblies <NUM> allows for greater retaining capability of material by the screen assemblies <NUM> and prevention of over spilling of material off the edges of the screen assemblies <NUM>.

<FIG> shows screen assemblies <NUM> in an undeformed state. Retractable members <NUM> are in a retracted position. When retractable members <NUM> are in the retracted position, screen assemblies <NUM> may be readily replaced. Screen assemblies <NUM> are placed in the vibratory screening machine <NUM> such that side members <NUM> contact angled surfaces <NUM> of central. member <NUM>. While the replaceable screen assemblies <NUM> are in the undeformed state, the retractable members <NUM> are brought into contact with screen assemblies <NUM>. The angled surface <NUM> prevent side members <NUM> from deflecting in an upward direction. When compression arrangement <NUM> is actuated, retractable members <NUM> extend from the compression assembly <NUM> causing the overall horizontal distance between the retractable members and angled surfaces <NUM> to decrease. As the total horizontal distance decreases, the individual screen assemblies <NUM> deflect in a downward direction <NUM> contacting supporting surfaces <NUM> (as shown in <FIG>). Angled surfaces <NUM> are also provided so that the screen assemblies <NUM> are installed in the vibrating screening machine <NUM> at a proper arc configuration. Different arc configurations may be provided based on the degree of extension of retractable members <NUM>.

The extension of retractable members <NUM> is accomplished through constant spring pressure against the body of compression arrangement <NUM>. The retraction of retractable members <NUM> is accomplished by mechanical actuation, electro mechanical actuation, pneumatic pressure or hydraulic pressure compressing the contained spring thereby retracting the retractable member <NUM> into the compression arrangement <NUM>. Other extension and retractions arrangements may be used including arrangements configured for manual operation, etc. {see, e.g., <FIG>). The compression assembly <NUM> may also include a mechanism for adjusting the amount of deflection imparted to the screen assemblies <NUM>. Additionally, the amount of deflection imparted to the screen assemblies <NUM> may be adjusted by a user selectable force calibration.

<FIG> shows a replaceable screen assembly <NUM>. Screen assembly <NUM> includes frame <NUM> and screen <NUM>. Frame <NUM> includes side members <NUM>. Frame <NUM> includes a semi-rigid perforated support plate <NUM> and screen <NUM> includes a woven mesh material <NUM> on a surface of the support plate <NUM>. Screen <NUM> is supported by frame <NUM>. Screen assembly <NUM> is configured to form a predetermined concave shape when placed in a vibratory screening machine and subjected to appropriate forces.

<FIG> shows a replaceable screen assembly <NUM>, Screen assembly <NUM> includes frame <NUM> and an undulating screen <NUM>. Frame <NUM> includes side members <NUM> and a semi-rigid perforated support plate <NUM>. Undulating screen <NUM> includes a woven mesh material <NUM> on a surface of the support plate <NUM>. Undulating screen <NUM> is supported by frame <NUM>. Screen assembly <NUM> is configured to form a predetermined concave shape when placed in a vibratory screening machine and subjected to appropriate forces.

<FIG> show a pre-compressed spring compression assembly <NUM>. Pre-compressed spring compression assembly <NUM> may be used in place of or in conjunction with compression assembly <NUM>. Pre-compressed spring compression assembly includes a spring <NUM>, a retractor <NUM>, a fulcrum plate <NUM> and a pin <NUM>. Pre-compressed spring compression assembly <NUM> is attached to wall member <NUM> of vibratory screen machine <NUM>.

In <FIG>, pre-compressed spring compression assembly <NUM> is shown with pin <NUM> in an extended position. In this position, pin <NUM> asserts a force against a screen assembly such that the screen assembly forms a concave shape.

In <FIG>, pin <NUM> is shown in a retracted position. To retract pin <NUM> a push handle <NUM> is inserted into an aperture in retractor <NUM> and pressed against fulcrum plate <NUM> in direction <NUM>. The force on retractor <NUM> causes spring <NUM> to deflect and pin <NUM> to retract. A surface may be provided to secure pre-compressed spring compression assembly <NUM> in the retracted position. Although a simple lever retracting system is shown, alternative arrangements and systems may be utilized.

In <FIG>, vibratory screen machine is shown with multiple pre-compressed spring compression assemblies <NUM>. Each compression assembly may correspond to a respective screen assembly <NUM> so that installation and replacement of screen assembly <NUM> requires retraction of a single corresponding compression assembly <NUM>. Multiple pins <NUM> may be provided in each of pre-compressed spring compression assemblies <NUM>. As set forth above, other mechanical compression assemblies may be utilized.

<FIG> shows vibratory screening machine <NUM> with multiple screen assemblies <NUM> forming a concave surface. The first screen assembly <NUM> has one side member <NUM> in contact with pin members <NUM> and another side member <NUM> in contact with a side member <NUM> of a second screen assembly <NUM>. The second screen assembly <NUM> has another side member <NUM> in contact with central member <NUM>. As shown, pin members <NUM> are in the extended position and screen assemblies <NUM> are formed into a concave shape. The force asserted by pin members <NUM> cause screen assemblies <NUM> to push against each other and central member <NUM>. As a result, the screen assemblies deflect into a single concave shape. The side members <NUM> that are in contact with each other may include brackets or other securing mechanisms configured to secure the screen assemblies <NUM> together. Although two screen assemblies are shown, multiple screen assemblies may be provided in similar configurations. The use of multiple screen assemblies may provide for reduced weight in handling individual screen assemblies as well as limiting the amount of screening area that needs to be replaced when a screen assembly becomes damaged or worn.

<FIG> shows vibratory screen machine <NUM> without a central member. Vibratory screen machine <NUM> includes at least two compression assemblies <NUM> that have retractable members <NUM> that extend toward each other. Retractable members <NUM>, which are illustrated in the extended position, assert a force against side members <NUM> of screen assemblies <NUM> causing screen assemblies <NUM> to form a concave shape against support surfaces <NUM>.

A method for screening materials includes attaching a screen assembly to a vibratory screen machine and forming a top screening surface of the screen assembly into a concave shape. The method may also include accelerating or vibrating the screen assembly, feeding material along the concave top surface of the screen assembly, screening the material, returning the screen assembly to its original shape and replacing the screen assembly with another screen assembly.

In the foregoing example embodiments are described. It will, however, be evident that various modifications and changes may be made thereunto without departing from the scope which is delimited by the appended claims.

Claim 1:
A screen assembly (<NUM>) for a vibratory screening machine (<NUM>), comprising:
a frame (<NUM>) including a plurality of side members (<NUM>); and
a screen (<NUM>) supported by the frame (<NUM>), wherein the screen (<NUM>) includes a woven mesh material (<NUM>),
wherein the screen assembly (<NUM>) is configured to form a concave shape when placed in the vibratory screening machine (<NUM>) and subjected to a compression force by a compression assembly (<NUM>) of the vibratory screening machine (<NUM>) against at least one side member (<NUM>) of the screen assembly (<NUM>), characterized in that: the frame (<NUM>) includes a perforated semi-rigid support plate (<NUM>); wherein the woven mesh material (<NUM>) is attached to the support plate (<NUM>) by at least one of gluing, welding and mechanical fastening.