[Fig. 3157] represents a roll feed wood planing machine, designed and constructed by George Richards & Co., of Broadheath, near Manchester, England, the construction being more fully shown in the detailed figures following. The machine consists essentially of a framework, carrying a cutter head with two knives, and having a pair of feed rolls, in front and a pair behind it. The front pair feed the timber to the cutter head and the back pair deliver it from the cutter head.
Fig. 3157.
Each pair of rolls is geared together, so that both the top and bottom rolls act to give a positive feed. Immediately in front of the cutter head and between it and the feed rolls (i. e. the front pair of rolls), is a pressure bar extending across the full width of the machine, and having at its lower extremity a steel spring which presses the work down to the table, and thus causes it to be planed of an equal thickness throughout its length. Immediately behind the cutter head and between it and the delivery rolls (i. e. the back pair of rolls), is a pressure bar that also extends across the machine and prevents the timber from rising up from the table after it has passed the cutters, all timber being found to have a tendency to rise after having been acted upon by the cutters. The arrangement of the feed rolls, delivery rolls and pressure bars is shown in [Fig. 3158], in which t, t, t, represents three sections of the work table and w, w, a piece of work passing through the machine in the direction of the arrow. Feed roller f is fluted to increase its grip upon the work and insure a positive feed. The lower feed roller f′, and the lower delivery roller d′, are fixed in position, their upper surface projecting above the work table to about 1⁄100 inch. This is necessary to take the thrust of the upper rolls (f, d) and prevent them from forcing the work down upon the surface of the table with an undue amount of pressure, which would induce friction and consume an unnecessary amount of power in driving the rolls. The method of adjusting the lower rolls will be explained presently.
Figs. 3158, 3159.
Between the cutter head c and the feed roll f is the pressure bar p, and behind the cutter head is the pressure bar b, both these bars being more clearly seen in [Fig. 3159], in which the work w is shown entering the machine, and the lower rolls and work table are removed.