The block diagram showing the principal parts of the double housing planer is shown in Fig. 15.1 and the various parts are described below:
Part # 1. Bed:
Planer bed is a very strong and robust structure, made out of cast iron and strengthened with cross-ribs. On very long planers the bed is sometimes made from two or more castings bolted together in perfect alignment with each other. As the table has to make complete stroke on the bed surface, the length of bed is usually twice the length of the table.
For installation purposes, levelling pads or jacks are provided under the bottom of the bed for levelling. A new planer or new foundation should be re-levelled at least once a week for the first month. Thereafter it should be checked periodically for being level, the period depending upon the stability of the foundation.
The table driving mechanisms are accommodated inside the bed. For supporting and permitting the table to reciprocate in constrained form, V- ways or flat ways or dovetail slides are provided on the top of the bed. For lubrication of the ways, pressure lubrication is adopted.
Part # 2. Table:
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It is a box like ribbed structure and sufficiently strong to take cutting forces and the weight. It reciprocates over the bed ways and its top surface is finished accurately to accommodate the heavy jobs which are secured to it by tightening the clamping bolts in the T-slots provided throughout the table length. To do accurate work the planer table must be kept free of scratches, dents and burrs.
A group of holes is drilled and reamed into the table top at regularly spaced intervals, and stop pins for clamping the workpiece are placed in these holes. Table may be single casting or divided in several units bolted together.
At either end of the table a trough is provided to collect chips and also sometimes utilised for supporting the overhanging jobs. For reversing the table automatically at the end of each stroke adjustable legs is provided which operate some mechanism. Arrangements are also made to avoid the running away of the moving loaded table.
On very large planers, two tables are fitted. One table is used for machining and on other, the work is set up.
Part # 3. Upright or Columns:
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These are provided for carrying horizontal cross-rail and are fastened to the sides of planer bed. In order that the cross-rail may travel on the columns, the front face of each upright is well machined and scraped.
The cross-rail can be held in any position with the help of clamps. Vertical feed shaft, cross-rail elevating screw and feed bar for cross-feed etc. are accommodated within the body of uprights.
Part # 4. Cross-Rail:
It is a sound structure mounted horizontally on the vertical ways of the columns and carries the tool feeding arrangements on it. Cross rail can be clamped on the columns at any desired height by clamps which may be operated manually, hydraulically or electrically.
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It may be moved vertically up and down by elevating screws accommodated within the column. A horizontal shaft carrying the bevel gears on its end is placed at the top of the column. The cross-rail carries two saddles with tool head mounted on each, and for this purpose the cross-rail face is perfectly machined and scraped. For down feed of the tools, the feed screws are enclosed in the cross-rail.
Part # 5. Tool Head:
Normally two tool heads are mounted on the saddle fitted on the ways of cross-rail and are operated independently. The tool head (clapper box) carries a tool post in which the cutting tool is held. The tool post is hinged at the tool head for lifting the tool in the return stroke. The clapper box can also be adjusted at an angle whenever desired.
Part # 6. Control:
The controls for governing the various actions of different parts of a planer are provided in centralised panel. (Generally a pendent having all the push buttons is usually suspended within the easy approach of the operator).
From this central location the operator is able to obtain very close control of all cutting tools. The various controls included are start, stop, automatic cut, automatic return, inch cut, inch return and table speed reducer etc.