Method for controlling the feed of backup rolls in a veneer lathe and a backup roll apparatus in a veneer

A method of controlling the feed of at least one backup roll of a log backup apparatus for use in a veneer lathe, for feeding said at least one backup roll in the centripetal direction of the log and for preventing a log from bowing while veneer is peeled from said log, said method comprising the steps of:

• bringing said at least one backup roll into contact with said log;
• calculating an amount .DELTA. of bowing of said log from the diameter of said log and the position of said at least one backup roll when said at least one backup roll is brought into contact with said log;
• feeding said at least one backup roll from a control-start diameter .PHI., until elimination of said bowing at the latest, at a provisional feed rate f which is higher than a predetermined feed rate F by a feed rate of a correction value .alpha. per log rotation, said correction value .alpha. being calculated from said amount .DELTA. of bowing of said log, where said control-start diameter .PHI. is the diameter of said log when said amount .DELTA. of bowing of said log is calculated;
• stopping said feeding of said at least one backup roll at said provisional feed rate f by the time said bowing is eliminated from said log at the latest;
• and
• thereafter feeding said at least one backup roll at said predetermined feed rate F.

A log backup apparatus having at least one backup roll for preventing bowing of a log which occurs while veneer is peeled from said log and a control unit for causing said at least one backup roll to be fed in the centripetal direction of said log during veneer peeling, said control unit comprising a compensation controller for controlling the operation of said at least one backup roll so as to:

• feed said at least one backup roll from a control-start diameter .PHI. at a provisional feed rate f which is higher than a predetermined feed rate F by a feed rate of a pre-selected correction value .alpha. per log rotation where said control-start diameter .PHI. is slightly larger than the diameter of said log at which said at least one backup roll is brought into contact with said log;
• stop the feeding of said at least one backup roll at said provisional feed rate f by the time the bowing is eliminated from said log at the latest;
• and
• thereafter feed said at least one backup roll at said predetermined feed rate F,
• whereby the bowing that occurs during the veneer peeling is eliminated from said log during the veneer peeling.

A log backup apparatus having at least one backup roll for preventing bowing of a log which occurs while veneer is peeled from said log and a control unit for causing said at least one backup roll to be fed in the centripetal direction of said log during veneer peeling, said control unit comprising a compensation controller for controlling the operation of said at least one backup roll so as to:

• bring said at least one backup roll into contact with said log;
• calculate an amount .DELTA. of bowing of said log from the diameter of said log and the position of said at least one backup roll when said at least one backup roll is brought into contact with said log;
• feed said at least one backup roll from a control-start diameter .phi., until elimination of said bowing at the latest, at a provisional feed rate f which is higher than a predetermined feed rate F by a feed rate of a correction value .alpha. per log rotation, said correction value .alpha. being calculated from said amount .DELTA. of bowing of said log, where said control-start diameter .PHI. is the diameter of said log when said amount .DELTA. of bowing of said log is calculated;
• stop said feeding of said at least one backup roll at said provisional feed rate f by the time said bowing is eliminated from said log at the latest;
• and
• thereafter feed said at least one backup roll at said predetermined feed rate F.