Patent GB-745228-A (GB)
Title: An improved machine for trimming and removing bark from timber logs
IPC: B27L1/10
Filed: 1953-05-02
Abstract: 745,228. Removing bark. MEIKLEJOHN, I. G. Aug. 3, 1954 [May 2, 1953], No. 12223/53. Class 145 A machine for removing bark from logs comprises two or more grooved skew rollers 13, 14 for feeding logs to one or more rotary bark-removing tools 19 and the rollers are driven in the same direction and converge towards their delivery ends, where they are mounted on spring-loaded pivoted arms 16, so that they grip the log resiliently to feed it axially and also rotate it; knot-trimming tools 81 may also be provided. The machine may be mounted on a trailer and a pulley 20 on a countershaft 21 may be driven from a motor on the trailer or from the power take-off of a tractor. The rollers, the tools and a chip-removing fan 24 are driven from the countershaft through a variable speed gear box 23 and by drives fitted with tensioning jockey pulleys, the drive to the rollers including chains passing over sprockets 10 and that to the tools including belts 30 and 36. The roller arms 16 and pivoted arms 34 and 50 for each set of tools 19, 81 are pressed inwardly by connecting rods 51 acted on by springs 48 which bear on fixed plates 49 and are .adjustable by means of nuts 53. To maintain the logs in a central position, diametrically opposed pairs of the rollers and of the tools may be interconnected by levers 56 engaging at one end between springs 60 on the connecting rods 51 at one side so that, as one roller or tool is moved in one direction by a large knot, the opposite roller or tool moves in the other direction after one of the springs 60 has been compressed. An eccentric 61 operated by a handle may be provided to depress all the levers 56 in order to remove a jammed log. Guide rods may be provided between the rollers to prevent logs being forced between the rollers and one pair of rollers 14 is longer than the other pair 13 in order to support the log while being operated on by;the tools. The bark-removing tool may comprise a number of blunt scraping abrading or flexible elements carried in inclined or helical fashion in a rotatable head. As shown, both the knot-trimming tool 81 and bark-removing tool 19 are carried by a driven shaft 80 mounted between each pair of arms 34, 50, each tool head 81 having cutters 83 with inclined sharp cutting edges and each bark - trimming tool 19 having rounded - off helical edges 84 with rake and clearance. To prevent the vertical end face of a log from engaging the sides of the knottrimming tool 81, the short rollers 13 are connected to the tool arm 50 by fever mechanism 72, 75 so that the tools move out clear of the log when the delivery ends of the rollers open out. As the log reaches the forward end of the tool 81, it encounters spiral rods 79 connected to the lever mechanism and the rotation of the log moves the rods 79 so that an over-centre action of the lever mechanism allows the springs 48 to move the tools into operative position. De-barked logs emerging from the machine are supported in a cradle formed by long rollers rotatable in Y-shaped end plates and the plates are pivotally mounted in spring-loaded pivoted frames to allow resilient vertical movement of the cradle. One end plate is interconnected with the lower long roller 14 so that the cradle is depressed when the roller is depressed.