Upright Drill Presses

The primary cutting motion of these machines is the rotation of the spindle which holds the cutting tool, while the feed motion is the axial motion of the spindle.

The workpiece is placed on the work table or directly on the base. The axis of the hole to be machined is aligned with the spindle axis by moving the workpiece along the table or base.

The principal units of an upright drill press are: column, base, speed gearbox, spindle, feed gearbox and feed mechanism and work table.

The column is a hollow box-shape casting which is mounted rigidly on the base and carries all other principal units. Vertical ways are provided on the front face of the column for the sliding spindle head and the table. The electric control devices and the spindle counterweight are housed in the cavity of the column.

The base is the footing on which the whole machine is supported. In the medium- and heavy-duty drill presses, heavy workpieces are placed on the top surface of the base. The cavities of the base serve as a reservoir for the cutting fluid.

The speed gearbox usually consists of sliding gears which are engaged in various combinations to obtain different spindle speeds. The spindles of modern drill presses run at 6 to 12 different speeds.

The spindle has a spline shank which fits the spline hole in the hollow shaft of the speed gearbox and rotates together with this shaft. At the same time the spindle can travel in the axial direction to provide the feed motion. The cutting tool is held at the lower end of this attachment.

The feed mechanism in upright drill presses provides for power and hand feeds of the spindle. When power feeds are engaged, a clutch links the output shaft of the feed gearbox to the spindle quill. When manual feed is engaged, rotation is transmitted directly from the handwheel or pilot wheel to the pinion which meshes with the rack of the spindle quill. The mechanism is equipped with a device for automatically disengaging power feed when the preset depth of machining is reached. The table of the drill press is the unit on which the workpiece is clamped. It can usually be adjusted vertically along the column and can be swung out of the ways in machines with a round column to enable heavy work to be placed directly on the base. The table is mounted on the column way (box column), on the column itself (round column), or it is of box shape and is mounted on the base.

Special program-controlled tables are available for drilling a series of holes in a workpiece without resorting to a jig. First the coordinate dimensions of the holes are set up and then the table and the saddle are automatically positioned for each hole in a definite sequence. This procedure is repeated for each workpiece of the lot.

EXERCISES

1.Underline the suffixes in the following words and state what part of speech they belong to:

Axial, directly, casting, principal, cavity, attachment, considerable, different, manual, rotation, clamped, heavy, enable, available, motion, housed.

2. Give different meanings of the following words:

Way, work, head, house, hand, power.

3.Translate the following sentences observing different meanings of the italicized words and word combinations:

1. Drilling means removing some metal from the work.

2. A drilling machine is by all means the most important machine for drilling holes of different size in metal.

3. By no means can a boring machine be used at speeds exceeding permissible ones as it may result in breakage.

4. Boring may be performed on drilling machines.

5. The main drilling motor drives the shaft by means of V-belts.

6. When we speak of the operations performed on the drilling machine, we mean such operations as tapping, reaming, lapping, etc.

4. Guess the meaning:

6.Try to translate the text without using the dictionary:

A considerable part of the handling time in hole-making operations involves the changing of the cutting tool. The use of a quick-change chuck, enabling tools to be changed without stopping the spindle, substantially reduces this handling time. The degree of automaticity of the machine, however, is not increased since tool changing is still done by hand.

The degree of automaticity can be increased if the upright drill press is equipped with a special turret which is indexed and locked automatically. In this case, automatic control of the spindle speeds and feed is also required. Promising in this line is the new upright drill press, model 2B135, designed in the ENIMS Institute. The speed gearbox of this machine is equipped with noncontact electromagnetic clutch incorporated in the feed gear train, enabling spindle feeds to be automatically controlled in a stepless range. An overrunning mechanism is provided in the feed gear train for hand traverse of the spindle.

A drill press of this type can be readily built into an automatic transfer machine or automated production line.

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