Conveyors: power-driven – Conveyor system for establishing and moving a group of items – Subdivides continuous item stream into longitudinally spaced...
Reexamination Certificate
1998-11-20
2001-02-20
Olszewski, Robert P. (Department: 3652)
Conveyors: power-driven
Conveyor system for establishing and moving a group of items
Subdivides continuous item stream into longitudinally spaced...
Reexamination Certificate
active
06189679
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an apparatus for holding and conveying spacing sticks to a stick placer in a sawmill, and in particular relates to an apparatus capable of automatically metering spacing sticks on a conveyor, for uniform delivery to a stick allocator for allocating spacing sticks for subsequent delivery and placing between tiers in a lumber stack being formed by a stacker in a sawmill.
BACKGROUND OF THE INVENTION
Previously automatic stick conveyors incorporated a stick un-loading area. The sticks were un-loaded onto a chain conveyor by a transportable stick bunk. The stick bunk was typically placed by a forklift on to the top of a hoist raised above the stick conveyor. The hoist was then lowered and the sticks set down onto the chain conveyor. Once the bunk was lowered completely below the conveyor, the conveyor began to move the sticks to an unscrambler. The unscrambler separated the sticks into a mat of adjacent sticks lying on their sides. The mat was then translated to a stick allocator. The allocator separated and allocated the sticks for timed and sequenced delivery to an automatic stick placer.
In this form of prior art system, the sticks often arrived bunched up at the unscrambler and needed to be manually prodded and straightened for even delivery to the allocator by the stick unscrambler.
It is therefore an object of the present invention to produce a stick metering apparatus wherein the delivery of sticks is automatically controlled on the stick transfer for even delivery of sticks to the stick unscrambler.
It is another object of the invention to produce a stick transfer metering apparatus that can be retrofitted to existing stick transferring systems.
SUMMARY OF THE INVENTION
Sticks are loaded onto a chain conveyor by a transportable stick bunk. The stick bunk is placed on to the top of a scissor hoist which has been elevated between a parallel pair of chains comprising the upstream end of chain conveyor. The hoist is lowered to rest the sticks on the chain conveyor. The bunk is lowered completely below the stick conveyor to release the sticks free of the bunk uprights onto the stick conveyor.
A pair of rigid translatable stick gates, one upstream and one spaced and parallel downstream, are mounted below and between the pair of conveyor chains. The stick gates can be selectively elevated so as to extend into the flow path of the sticks so as to block flow of the sticks downstream on the conveyor. The gates may be retracted down out of the stick flow path. Alternating sequential extension and retraction of the two gates meters the flow downstream of the sticks bunched on the chain conveyor following removal from the stick bunk.
After the stick bunk has been fully retracted down releasing the sticks into a pile on top of the chain conveyor, the chain conveyor starts up momentarily moving or jogging for a short period the stick pile downstream towards and against the first stick meter gate in its elevated position. The first stick gate is elevated so as to assist in straightening any sticks that might have become skewed as the sticks spill from the bunks onto the conveyor. To begin metering the flow of sticks, the second, i.e. downstream, gate is raised. The first stick gate is then lower, allowing the sticks which were bunched up against it to tumble down against the second gate. After a brief pause (approximately 2 seconds) the first gate is elevated pushing its way up through the shallow downstream portion of the pile of sticks, that is, up through the sticks which had tumbled down. Elevating the first gate gently lifts, separates, and straightens the sticks so that a shallow layer, bunch or bundle of sticks is contained between the two elevated gates, leaving a deeper layer, bunch, bundle or pile of sticks upstream of the first gate. After another brief pause (approximately 2 seconds) the second gate lowers to a position below the stick conveyor chains. The stick conveyor chains then jog forward downstream (approximately 2 seconds, equal to approximately 2 feet of travel) advancing the shallow layer of sticks toward the stick unscrambler, and causing the deeper pile of sticks upstream of the first gate to bunch or pile up against the first gate as they were at the beginning of the breakdown cycle.
Repeating this breakdown cycle produces a spaced apart series of shallow piles of sticks, spaced apart downstream of the second gate, effectively creating a continuous layer of shallow piled sticks on the stick conveyor chains. Because the sticks are retained between and against two elevated gates during a holding time pause in the breakdown cycle, the sticks in the resulting shallow layer are essentially parallel as they travel to the unscrambler.
A photo-eye may be located at the unscrambler trough at the bottom of the unscrambler to detect the presence or absence of sticks waiting to be unscrambled. If no sticks are detected, the two gates and chain conveyor are cycled through the breakdown cycle repetitively until sticks are detected in the unscrambler trough, at which time translation of the stick gates and the chain transfer is stopped. Each time the photo-eye in the unscrambler trough causes a monitoring processor to call for more sticks, the stick chain conveyor advances approximately 2 feet, depositing the corresponding volume of sticks from the shallow layer carried on the conveyor into the unscrambler trough. Because the shallow layer of sticks on the stick chain conveyor is controlled by the stick metering apparatus, the volume of sticks deposited into the unscrambler trough is consequently controlled, allowing the unscrambler to operate with an optimal amount of sticks in the unscrambler trough. As a result, the stick unscrambler operates at peak efficiency, delivering an adequate and continuous supply of sticks to downstream stick placing equipment. The unscrambler lifts and separates sticks from the unscrambler trough, and transfers the unscrambled sticks to the unscrambler outfeed to form a mat for allocation to the stick placer. The unscrambler stops and starts as required to maintain a constant supply of sticks at the allocator.
In summary, the stick metering device of the present invention is mountable beneath a stick conveyor, and includes an upstream gate and a downstream gate. The downstream gate is generally parallel to and spaced apart a first distance from the upstream gate. The upstream gate cooperates with a first actuator for vertical actuation of the upstream gate between an upstream elevated position and an upstream lowered position. The downstream gate cooperates with a second actuator for vertical actuation of the downstream gate between a downstream elevated position and a downstream lowered position. When in the upstream and downstream elevated positions, respectively, the upstream and downstream gates intersect a stick flow path so as to interrupt a downstream flow of sticks along the stick flow path on the stick conveyor. When in the upstream and downstream lowered positions, respectively, the upstream and downstream gates do not intersect the stick flow path so as not to interrupt the downstream flow of sticks along the stick flow path on the stick conveyor.
The upstream gate has an exposed vertical length which is exposed across the stick flow path when in the upstream elevated position. The exposed vertical length is sufficient to dam a pile of sticks loaded onto the stick conveyor from an upstream reservoir of sticks.
The first distance between the upstream and downstream gates is sufficient to allow segregation, between the upstream and downstream gates, of a leading portion of the pile of sticks.
The first and second actuators are selectively sequentially actuated by timing and actuating means. During a first breakdown cycle phase, the first actuator elevates the upstream gate into the upstream elevated position so as to accumulate the pile of sticks against the upstream gate. During a second breakdown cycle phase, the first actuator lowers the upstream gate into the upstream lowered position an
CAE Electronics Ltd.
Edwards Antony C.
McAllister Steven B.
Olszewski Robert P.
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