Conveyors: power-driven – Conveyor system for arranging or rearranging stream of items – By laterally or vertically moving successive items in...
Reexamination Certificate
1999-06-21
2001-11-06
Rada, Rinaldi I. (Department: 3724)
Conveyors: power-driven
Conveyor system for arranging or rearranging stream of items
By laterally or vertically moving successive items in...
C083S075500, C083S409000, C083S419000, C083S422000, C083S425200, C083S732000
Reexamination Certificate
active
06311828
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a positioning fence, and in particular to an automatically adjustable stepped board positioning fence.
BACKGROUND OF THE INVENTION
In a typical lumber mill or planer mill, each board is moved along sideways. That is, oriented transversely on a lugged transfer prior to trimming or sorting. Typically, the lugs on the transfer are evenly spaced at precise intervals. Moving boards through an electronic scanner by the lugged transfer, the scanner determines the shape and/or length of each board and sends the information to an optimizer. The optimizer in turn sends the information to a controller. The controller activates saws above a trimer saw deck to trim the board in the corresponding lug space, in an attempt to maximize board utilization.
Typically, however, saws are spaced about two feet apart, so that depending upon the physical defects of a board, up to almost two feet on each end of the board can be trimmed and thus wasted, which can result in a considerable wastage of useful wood.
In order to minimize such wastage, in the prior art, board positioners have been developed which utilize a plurality of parallel rollers that are driven in a direction perpendicular to the transfer deck, thus moving the ends of the boards against a positioning fence. When on the rollers, the boards are continually thrust laterally across the transfer deck. The boards are elevated out of contact with the rollers at a predetermined time. Such devices suffer from the fact that tapered ends of the boards abutting the positioning fence can be so structurally weak as to collapse or break when driven against the fence by the rollers. Because the board has been optimized based on the inclusion of the tapered ends, if one end of the board is broken off, the optimized positioning of the board is adversely affected as the broken board is driven against the positioning fence, resulting in a board that is trimmed non-optimally.
Thus, it is the object of the present invention to provide a board positioning device which can accurately position selected boards lengthwise, and process the boards through the trimmer at a higher rate of speed than prior art devices, without collapse of the board's weak ends, to thus provide an improvement in maintaining a consistently accurate and optimally trimmed board.
Further, if the board is translated laterally by the rollers more than a small distance before the board contacts the positioning fence, the lateral velocity and acceleration of the board will often result in the board bouncing off the positioning fence. This also causes loss of accuracy in optimizing positioning of the board for trimming the optimizer and controller regulating the lateral optimized positioning of the board relative to the saws is based on the assumption that the board is ended closely against the positioning fence.
Thus, it is an object of the present invention to provide a board positioning device which can accurately position selected boards lengthwise, that is, transversely across the transfer deck and process the boards through the trimmer at a higher rate of speed than prior art devices. Controlled ending substantially reduces board bounce, and/or collapse of the board's weak ends, thus providing an improvement in maintaining a consistently accurate and optimally trimmed board.
It is yet another object of the present invention, to provide a stepped fence board positioning device for sorting of boards by length or grade.
SUMMARY OF THE INVENTION
A stepped board positioning fence has a plurality of rigid elevated steps extending longitudinally along the fence in an adjacent stepped array, mounted upstream of a trimmer in the direction of flow. Alternatively the fence is mounted upstream of sorter bins or the like when using fixed stepped fence in an alternative embodiment. The boards are translated on lugged transfer chains, and simultaneously translated over a plurality of ending rolls. The ending rolls are mounted parallel to the lugged transfer chains. The boards are perpendicular to the transfer chains and ending rolls.
The ending rolls end the boards against the stepped fence. At the upstream end of the stepped fence, the boards are urged laterally (i.e. ended) against a selectively pivotable positioner which is pivoted by selective actuation of a multistage cylinder (or other means). The positioner directs boards along one of the laterally spaced apart travel paths defined by the steps on the stepped fence.
Alternatively, a short ending roll is mounted adjacent the upstream end of the stepped fence. The short ending roll is selectively elevated from below the level of the boards on the ending rolls when needed to boost a board on a step required for that board's particular ending requirements.
The boards are continually urged against the fence as they are translated both towards the fence and simultaneously towards the trimmer saws. The steps have fixed profiles which define progressively diverging travel paths diverging in the downstream direction. The step profiles straighten so that the travel paths become parallel near the end of the fence. As the board reaches the downstream end of the ending rolls and the stepped fence (that is, just before clearing the fence), the fence is accurately adjusted by a Temposonic™-type selectively actuable cylinder (or other means) to accurately set the board's position. The end of the board then slides off the end of the fence and translates in direction A into the saw blades.
An optional flexible overhead hold down device, or other hold down means, is made of a smooth and flexible material such as UHMW plastic. The flexible overhead hold down device presses boards down onto the ending rolls to help insure traction of the board on the ending rolls, as well as helping to prevent chattering of the board after the board reaches its ending point against the fence. Chattering can cause the board to be out of position slightly as the board comes off the downstream ends of the ending rolls.
The present invention allows boards to follow along the fence at all times, inhibiting bouncing of the boards off the fence and helps to prevent the breaking off, and loss of a structurally weak end of the board. Both bouncing and breaking of boards may cause missed target points on the board which have been set by the optimizer as sawing points based both on a scanned board profile, that is, based on a profile which included the structurally weak end of the board.
In summary, the board positioning device of the present invention is a device for selectively positioning in a lateral direction in a generally horizontal plane a board translating on a board transfer. The board is transferred in a longitudinal direction in the horizontal plane. The board is aligned along its length in the lateral direction and urged in the lateral direction by board ending means. The board positioning device includes a stepped fence lying in the generally horizontal plane. The stepped fence has a plurality of adjacent terraced steps extending downstream in a generally spaced array from an upstream stepped fence entrance. The steps extend downstream in generally the longitudinal direction from an upstream stepped fence entrance whereat the board may be slid onto one step of the plurality of adjacent terraced steps. Each step of the plurality of adjacent terraced steps defines a corresponding transition path for transitioning an end of the board from the upstream stepped fence entrance to a downstream position. A selective positioning means selectively positions the end of the board onto a desired step of the plurality of adjacent terraced steps at the upstream stepped fence entrance so as to correctly position the end of the board at the downstream position.
Advantageously, the selective positioning of the end of the board onto a desired step is in accordance with instructions from an optimizer. The downstream position is thus an optimized board ending position optimized relative to at least one trimmer saw downstream of the
Newnes William R.
Wight Geoff
CAE Inc.
Edwards Anthony C.
Rada Rinaldi I.
Tran Kim Ngoc
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