US 4,043,901 AGranted

Wood chip screens

AssigneeGauld Equipment Sales Company

InventorWarren Thomas Gauld

Life of this patent

Estimating the term…

Loading patent…

Abstract

A drum screen for cleaning and classifying wood chips is mounted for rotation. The screen has apertures of varying size to permit cleaned chips to pass through to be deposited on conveyors located below. An internal annular spiral baffle extends the full length of the drum and a series of chip lifters are located between the flights of the spiral baffle and project radially inwards from the interior surface of the drum. Wood chips are fed into the drum at one end and are carried through the drum while being lifted towards the axis of the drum by the chip lifters to effect loosening of waste material from the chips. Cleaned chips pass through the apertures in the drum and chips too large to pass through are carried forward and discharged from the end of the drum onto a conveyor. A casing surrounds the upper portion of the drum and partially encloses the discharge end of the drum. An air suction device is connected to the discharge end of the drum, drawing off all waste material loosened from the chips.

Claims10

Dependent claims

A wood chip screen of the rotary type comprising a screen having perforations in a first inlet portion thereof to permit passage therethrough of fines material and having perforations in a second discharge portion thereof to permit pasage therethrough of acceptable chips, a hollow spiral baffle secured to the inner surface of the screen, means to separate unwanted material from the wood chips and to float said unwanted material into the interior of the screen, air suction means creating an air stream to withdraw from the interior of the screen the said unwanted material, said air suction means including a conduit communicating with the interior of the screen at an end thereof such that the unwanted material can pass with said air stream directly from the interior of the screen into said conduit without passing through the screen perforations, and including a fan means for drawing air from the interior of the screen into said conduit, a cyclone separator in communication with the fan, first conveyor means below the said screen to receive the fines and acceptable chips, and second conveyor means adjacent the discharge end of the screen to receive oversize wood chips, and a casing enclosing the upper half and a portion only of the lower half of the screen in spaced relation thereto, the said casing including an end closure plate adjacent to the discharge end of the screen, said conduit connecting the said fan with the interior of the screen through the said casing and closure plate.

Dependencies are inferred from the claim text.