Apron weigh feeder

Details Apron weigh feeder Apron weigh feeder

2002-07-25

2003-12-16

Hess, Douglas (Department: 3651)

Conveyors: power-driven

With alarm or indicator

C198S817000, C198S820000, C198S959000, C414S021000, C177S052000, C177S119000

Reexamination Certificate

active

06662930

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apron feeder for use in the bulk materials industry and, more particularly, an apron feeder incorporating an integral weighing device.
2. Description of the Prior Art
Apron feeders are typically used in the mining, cement, and other bulk materials industries for extracting bulk materials from bins, hoppers, silos, stockpiles, and the like. The apron feeders are then used to transfer the material to another location. Some specific uses of apron feeders known in the art are applications such as feeding and withdrawing materials from primary crushers, loading and unloading trucks and railcars, removing frozen materials from storage, feeding jaw crushers and belt conveyors, and high abrasion applications frequently found in reclaim circuits. Two examples of apron conveyors known in the art are found in U.S. Pat. Nos. 3,934,712 to Jende and 1,537,444 to Herzog, the disclosures are incorporated herein by reference.
Apron feeders, particularly “tractor type” apron feeders, are often confused with other types of feeders such as pan or belt feeders. Those skilled in the art will appreciate that apron feeders are distinguishable from pan or belt feeders because pan and belt feeders are not capable of being used in the heavy, bulk materials industry such as mining. Apron feeders are uniquely suited for feeding large, lumpy, abrasive, and heavy materials. Pan or belt feeders are not suitable for use with such materials and are typically limited to light duty operations only. Thus, apron feeders are considered in the art to be distinguishable from pan or belt feeders.
Apron feeders come in many different configurations. However, apron feeders generally share certain characteristics in common. Typically, apron feeders include a feeder frame upon which a drive roller is rotatably mounted. A tail roller is located at an opposite end of the feeder frame from the drive roller. A plurality of idler rollers is located between the drive roller and tail roller. Apron feeders further typically include a series of interconnected metal pans or flights that are reeved about the drive roller and tail roller and supported by the idler rollers between the drive roller and tail roller. Two or three strands of endless conveyor chain are often used to drive the pans and material carried thereon.
One known configuration for apron feeders locates the endless conveyor chain outboard of the flights such that the conveyor chain does not directly support the weight of the material on the flights. This arrangement is known as an outboard chain design. Another configuration known in the art for apron feeders was introduced in the early 1970's and is known as a “tractor type” apron feeder. A tractor type apron feeder utilizes tractor type undercarriage chain and rollers that are used on bulldozers and excavators. In the tractor type configuration, one or more conveyor chains are located under the flights. In recent years, tractor type apron feeders, also referred to as crawler apron feeders, have become the preferred design for use in the heavy materials industry.
It is well-known in the art to include a load cell assembly or weighing system with belt conveyors. For example, U.S. Pat. Nos. 4,463,816 to McFarlane; 3,478,830 to Levesque et al.; and 2,882,036 to Lyons are generally directed to belt conveyor weighing systems in which a load cell is located below the belt conveyor for weighing the material received on the surface of the belt conveyor. Specific belt scales for weighing material moving on a belt conveyor supported by an idler assembly are known from U.S. Pat. Nos. 5,294,756 to Lauber et al. and 5,285,019 to Kempf et al. The belt conveyor scale arrangements known from Lauber et al. and Kempf et al. generally disclose the use of a load scale located below an idler support of the belt conveyor. A typical weighing arrangement
10
for a belt conveyor is shown in FIG.
1
. The disclosures of each of the foregoing listed patents are incorporated herein by reference.
In
FIG. 1
, the contents of a hopper or bin
12
may be extracted to an apron feeder
14
located below the hopper
12
. To perform a weighing operation, the apron feeder
14
delivers material to a belt conveyor
16
that includes a belt conveyor scale
18
. The belt conveyor
16
, after weighing the material, delivers the material to a downstream product conveyor
20
through a crusher
22
or other piece of equipment. The arrangement shown in
FIG. 1
is well-known in the heavy materials industry. The apron feeder
14
is provided primarily to absorb the heavy weights associated with the extraction of bulk materials from the hopper
12
. The weighing step is performed entirely by the belt conveyor
16
.
U.S. Pat. No. 4,823,440 to Pinto is directed to a web weight control system for weighing fibers supplied to a carding machine that incorporates an apron conveyor. The apron conveyor includes a weighing device defined by a plunger and a horizontal rod, which bears against the underneath portion of the upper run of the apron conveyor. A transducer is used for sensing the load on the apron conveyor and then sends a weight control signal to a computer. As will be appreciated by those skilled in the art, Pinto discloses the use of an apron conveyor for light, loose fabrics and is not believed to be pertinent to the apron weigh feeder of the present invention, which is specifically directed for use with heavy bulk materials and is a tractor type apron feeder.
In view of the foregoing, an object of the present invention is to provide an apron feeder capable of extracting and weighing heavy bulk materials at the same time with one piece of equipment.
SUMMARY OF THE INVENTION
The above object is accomplished with an apron weigh feeder in accordance with the present invention. The apron weigh feeder of the present invention is intended for use in the heavy, bulk materials industries, such as the mining and cement industries, to extract various types of materials from beneath hoppers, storage bins, silos, reclaim piles, and the like. The apron weigh feeder is a tractor type, also referred to as a crawler type, apron feeder and is capable of weighing extracted material as the material is conveyed from an extraction end to a discharge end of the apron weigh feeder. The apron weigh feeder simultaneously transports and weighs heavy bulk materials.
In general, the apron weigh feeder of the present invention includes a feeder frame, a head drive shaft, a tail traction wheel, a plurality of carry rollers, an endless crawler chain, a plurality of flights, and a weigh scale assembly. The head drive shaft is mounted rotatatably on the feeder frame. The head drive shaft has a drive sprocket mounted thereto. The tail traction wheel is mounted rotatably on the feeder frame at an opposite end of the feeder frame from the head drive shaft. The tail traction wheel is aligned with the drive sprocket. The carry rollers are located and aligned between the drive sprocket and tail traction wheel. The carry rollers are supported rotatably by a plurality of carry roller support frames, respectively. The carry roller support frames are each mounted on the feeder frame. The crawler chain is reeved about the drive sprocket and tail traction wheel. The crawler chain in operation of the feeder moves in a chain path comprised of an upper rectilinear path and a lower rectilinear path connected by two curvilinear paths. The crawler chain is supported by the carry rollers while moving in the upper rectilinear path. The flights are fixed to the crawler chain to define a carrying surface of the feeder. The weigh scale assembly is substituted in place of at least one of the carry roller support frames. The weigh scale assembly is operable to generate an output signal indicative of the weight of bulk material passing over the weigh scale assembly.
The weigh scale assembly may comprise a scale support frame substituted in place of the at least one carry roller support frame and a load cell positioned

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