Rough lumber knife planer
A planing machine (or simply “planer”) which may have two planer heads, each head containing the conventional knives and supporting apparatus to perform the actual cutting of material. To improve yield, the board is centered vertically as it progresses longitudinally through the planer. This is accomplished using either or (preferably) both of two systems: (1) a segmented self-centering drive roll system to feed the boards into the machine; and (2) a shoe mechanism which is controlled by a linkage such that the retracting segmented shoe assembly moves away from the planer head as it moves vertically to compensate for varying material thicknesses. The result is a more efficient use of the workpiece because less waste is created.
1. An assembly for planing rough surfaces of a piece of wood, comprising:
(a) a pair of planer heads positioned to remove material from opposing rough surfaces of the piece of wood;
(b) a segmented self-centering drive roll system which feeds a leading edge of the piece of wood toward, and vertically centered between, the pair of planer heads, the leading edge being fed over a longitudinal gap between the drive roll system and the planer heads; and
(c) at least one pair of movable shoe subassemblies, each shoe subassembly comprising a shoe having first, second, and third locations which are different from each other, upper and lower portions, and only one vertically movable shaft, pivotably mounted to only the first location of the shoe such that only the lower portion of the shoe is in the longitudinal gap, in which the lower portion of the shoe vertically holds the leading edge of the piece of wood despite vertical movement of the shaft causing vertical motion of the shoe, and further in which the shoe is mounted to a fixed mount at each of the second and third locations by one of a set of two linkages which are not parallel to each other, so that the lower portion of the shoe moves away from the planer heads as the upper portion of the shoe pivots about the first location and moves vertically due to the vertical motion of the shaft.
2. The assembly of claim 1 , in which the lower portion of the shoe has a lower surface facing the surface of the piece of wood, the lower surface of the shoe comprising multiple stages.
3. The assembly of claim 1 , in which vertical motion of the upper portion of the shoe is reciprocal.
4. The assembly of claim 3 , further comprising a spring for producing the reciprocal vertical motion.
5. The assembly of claim 3 , further comprising a pneumatic assembly for producing the reciprocal vertical motion.
6. The assembly of claim 5 , in which the pneumatic assembly comprises an air-filled bladder.
7. The assembly of claim 1 , in which there are eight movable shoe subassemblies in each member of the pair.
8. The assembly of claim 1 , in which the drive roll system comprises individual drive wheels mounted along a shaft.
9. The assembly of claim 8 , in which each drive wheel comprises a steel core, a resilient material surrounding the steel core, and a knurled rim surrounding the resilient material.
10. The assembly of claim 8 , in which the drive roll system comprises four feed roll assemblies rotationally driven in pairs having opposing directions of motion relative to the piece of wood.
11. The assembly of claim 1 , in which the upper portion of the shoe is pivotably mounted to the shaft farther away from the piece of wood than any linkage is mounted to the upper portion of the shoe.