1) Metalworking machines and tools
To ensure the accuracy of dimensions and surface roughness established by the drawing, most parts of machines and mechanisms are machined on the machines by chip removal. The surfaces to be treated can be flat, cylindrical, conical, shaped or complex curvilinear. Movement of executive bodies of machine tools is divided into working and auxiliary. Workers call movements in which chips are removed; Auxiliary – movements, in which the chip is not removed from the workpiece. The work movement can be divided into main movement and feed motion. The main movement is motion, the speed of which is the greatest.
When turning the workpiece, the rotational main motion is communicated, and the tool (cutter) – the feed motion
When milling, the main movement is communicated to the tool (milling cutter), and the feed motion to the workpiece.
When drilling, both the main movement and the feed motion are usually communicated to the tool, however in special machines this may not be observed.
When planing on cross-planer machines and processing blanks on slotting machines, the main movement is communicated to the tool (cutter), and the feed movement to the workpiece or cutter.
When planing on planer planers, the main movement is communicated to the workpiece, and the feed to the tool (tool).
When pulling, the main movement (rectilinear) is communicated to the tool (broach).
With round and flat grinding, the main motion is always rotational (grinding wheel).
2) Elements of cutting
The main elements of cutting are:
1) t – depth of cutting between the treated and treated surface, mm.
T = (D-d) / 2
2) feed s – displacement of the tool in one turn of the workpiece, mm / rev
3) width of the cut layer b – distance between the treated and machined surface measured along the cutting surface, mm.
The surface of the workpiece with which the chips is removed is called processed (1); The surface formed by the cutting edge of the tool during cutting is called the cutting surface (3). The surface formed after chip removal is called processed (2).
3) Cutter geometry
The cutter is the most common tool used in the processing of materials.
Cutters are distinguished by the type of processing and equipment (turning, boring, planing, grooving, special); On the work performed (through, undercut, cut-off, boring, threaded, shaped, as well as roughing, finishing and diamond turning); In the direction of feed (radial and tangential, as well as right and left); By the kind of tool material (from low and medium-alloy steels, high-speed, hard-alloy, diamond, mineral-ceramic); Depending on the shape of the rod section (rectangular, square, round); By the shape of the head (straight, bent, curved, drawn); By the method of production (solid, with soldered or mechanically fixed plate, with a welded head).
In the processing of soft, carbonaceous steels, copper, the chip is formed; When machining solid steels, chipping chips are formed; When processing cast irons and other brittle metals, shavings of the nelomium are formed.
4) Lathes, types of processing, tools, devices
The group of lathes includes lathe-screw-cutting, turning-turret, multi-lathe turning, carousel-turning, frontal, automatic and semiautomatic machines, drilling-cutting (with rotating workpiece) and special lathes.
The main tools for turning machines are: cutters of different types, drills, countersinks, countersinks, reamers, dies.
The main types of work on lathes: grinding (cylindrical and conical surfaces), grinding and cutting end surfaces, boring cylindrical and tapered holes, threading.
As devices on lathes are: centers, self-centering cartridges (3x – 4x cams), face plates, lunettes.
Milling machines and work performed on them
Milling machines are divided into cantilever, longitudinal, portal, carrousel-milling, drum-milling, copying and special.
Cantilever lathes are designed for processing small and tall workpieces, which is determined by the size of the tables (up to 500-2000 mm) and the largest distance (up to 500 mm) from the table to the end of the spindle (vertical) or to its axis (horizontal).
Milling, milling cutters and auxiliary tools
Milling is one of the high-performance and common methods of cutting, it is used to produce flat or profile (shaped), smooth, corrugated, surfaces of parts, grooves, various grooves.
Mills, depending on the position of the cutting edge with respect to the axis, are with a straight and screwed tooth; On the shape of the posterior surface of the tooth, the milling cutters can be flattened and unkempt (spiky).
By designation, the milling cutters are divided into the following:
A) for the treatment of planes – cylindrical and face;
B) for grooving grooves and splines – disc, groove, end, single-corner, double-angle, T-shaped;
C) to produce shaped surfaces – shaped, modular, worm;
D) for cutting metals – cutting (circular saws).
The process of abrasive processing is called grinding. Abrasive materials (grains of high hardness with sharp edges) can be in free form (powders) or in bound (cemented) in the form of circles, bars, segments.
In the majority of cases, grinding is a finishing operation that provides high accuracy (up to 0.002 mm) and the required grade of surface roughness, and is used for processing the outer and inner cylindrical and conical, flat and curved surfaces of all metals and alloys.
Grinding is also used for grinding work, for sharpening cutting tools. The greatest number of grinding operations is performed using a rapidly rotating abrasive wheel.
Depending on the size of the grains of abrasives, they are divided into grinding grains – granularity from No. 200 to No. 16, grinding powders – from No. 12 to No. 3 (number indicates the average grain size in hundredths of a millimeter) and micropowders – from M40 to M5 (number specifies Grain size in μm). The choice of grain size depends on the required roughness: coarse abrasives are used for roughing, fine-grained for finishing and finishing.
Bundle provides a compact abrasive tools of the desired shape and size and determines their strength and hardness. Inorganic and organic ligaments are used. The most common inorganic bond – ceramic K, composed of refractory clay, liquid glass and other components. Organic bonds – volcanic B and bakelite B have great strength and elasticity and are used for the production of thin (cutting) circles, for tools used in finishing operations; Circles on the vulcanite bond are also used as the leading ones for centreless grinding.
A group of grinding Stoics includes machines for round grinding (center-circular grinding, centerless grinding, intragrinding), machines for flat grinding, lapping and polishing, grinding, abrasive grinding, as well as specialized and special.