Materials science

13-LABORATORY WORK
DRILLING MACHINES AND THE WORK PERFORMED ON THEM
Purpose of work. Getting acquainted with the structure and operation of the drilling machine, creating a technological card for the work performed on it, and determining the main time spent on it.
Drill have not had significant structural changes since time immemorial, but have developed in the group of small-size table top, large-size floor-mounted, hand-operated machines for making simple holes. It is necessary to create a technological system to perform the hole processing operation. This includes the machine tool, Billet, device, instrument and auxiliary elements. It is known that in the processing of instruments, metal or non-metallic Billet, i.e., open and closed holes (Fig. 1), various constructive types of drills, countersinks, and reamers are used. In the process of cutting metal, first of all, the Billet is precisely placed on the table of the drilling machine. It is achieved by adjusting the centre of the machined hole to the Morse taper (a cone-shaped cavity designed to connect with the taper of the drill tail in the machine tool spindle) to the drill axis.
Figure 2. Types of drill:
a - spiral drill; 6 — cylindrical countersink; eat-cone countersink; g-butt working countersink; d — reamer; here are the elements of the cutting part of the cylindrical norm: 1 - blade of the cutting base; 2 —front face; 3 — tape; 4 — auxiliary cutting blade; 6 — front face; 7 - cross stitch.
T he spindle is pushed by hand with the help of a steering wheel sitting on the axis of the gear wheel. If it is necessary to push the spindle by hand at a lower speed, the gear wheels with 22 and 64 teeth from the handle are a single worm, a worm wheel with 60 teeth and a rack gear with 14 teeth. pushed back. Before starting the machine, a machine tool or piece of equipment is installed on the table, and a Billet is attached to it. The centre of the opening in the Billet is aligned opposite the axis of the spindle. Then the tail of a drill or other cutter is mounted on the spindle (Fig. 1). If necessary, transition bushings are used. Then the gears and gearbox levers are moved to the required speeds, the engine is started, and then the flywheel 8 is turned (or automatically) to bring the drill closer to the Billet, and then it goes to the cutting. Grinding is carried out with or without lubrication, depending on the material of the tool, cutting tool and other parameters.
Cutting speed refers to the cutting speed in meters per minute (m/min) of the farthest point of the cutting edge on the drill. The cutting speed is calculated according to the following formula:
V= n/1000
Drilling machines are of great importance in performing work such as cylindrical and conical holes, opening of various grooves, routing of grooves, drilling of tores, opening of chamfers in details (Fig. 3).

Figure 2. Schemes of drilling, galvanizing and deburring: a) drilling; b) galvanizing; d) liquidation; e) loosening of conical holes.

Fig. 4. Kinematic representation of the RDB vertical-drilling machine
TECHNICAL DETAILS OF THE MACHINE
The largest diameter of the processed hole, mm ............35
The number of spindles in the revolver head ...................................6
Number of rotation frequencies................................................... ........12
Rotational frequency limits rpm ...........................31.5–1400
The number of thrusts of the revolver head support ....................................18
Support push limits, mm/min...................................10–500
The speed of rapid movement of the support, mm/min...................................3360
Table speed, mm/min:
— in fast movement .............................................. .........................3210
— in slow motion ................................................... .....................2,1
The largest path of the table in mm:
— in the longitudinal direction ........................................ ..............560
— in the transverse direction ........................................ ...........360
Shift step, mm................................................ ....................0.01
Number of coordinates ................................................ .................4
Number of simultaneously controlled coordinates...................2
Type of RDBq................................................... ...........S-70-3 coordinates
Power of the main electric motor, kW ......................4

Drill diameter, mm	Steel and aluminum alloys with Mpa	Steels with Mpa	Cast iron and copper alloys	Speed of drilling
10 16 25 30	0,22—0,28 0,31—0,37 0,39—0,47 0,45—0,55	0,17—0,21 0,22—0,28 0,29—0,35 0,32—0,40	0,47—0,57 0,52—0,64 0,78—0,96 0,90-1,1