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METALWORK AND MACHINE ACCESSORIES

In machine construction semi-products subject to processing are called workpiece. Geometrical configuration is the most important parameter of parts. Configuration of workpiece before operation is called initial configuration; workpiece itself before processing is referred to as rough workpiece. A completely processed workpiece is called a finished part (or part for short) and has the final required form. Forms of workpiece between the two stages are called intermediate forms. The change of geometrical configuration under consideration is performed by means of mechanical removing of material particles. This process is referred to as cutting. Term “cutting” stands for the process of cutting; “cutting work” is used for naming workpiece processing, and “metal removing” refers to removing layers of material.

Geometrical shape of workpieces is changed by tools with fixed or diffuse geometry of cutting unit. The tool and the workpiece make an operational pair and touch each other while cutting, thus forming an interaction zone. Form is created by metal removing, when the workpiece is processed with a cutting tool of fixed geometry, or by relative movement of workpiece and tool, or by combination of these two methods. Task-oriented shaping of workpieces with the use of methods and processing means of metal removing is called cutting tool engineering.

Choice of technologic means depends on processing method: metal-cutting machine tools, cutting tools, machining attachments (clamp mechanisms, auxiliary tools and appliances), measurement instruments.

According to DIN 8589 regulations, following definitions are used in cutting work with fixed geometry tools:

turning – processing with closed (often circular) cutting movement and any feed-motion in one of planes perpendicular to cutting movement direction; axle of circular cutting movement keeps its position toward workpiece in various cutting movement directions;

drilling - processing with closed circular cutting movement, tool can travel its feed-motion along rotation axis only; axle of cutting movement keeps its position toward workpiece and tool independently of feed movement direction;

milling – processing with a tool having circular cutting movement and various feed-motions; axis of cutting movement keeps its position toward tool independently of feed movement direction;

chipping and slotting – processing with step-like repeated (often linear) cutting movements and step-like feed-motion along direction perpendicular to cutting direction;

drawing – processing with a multiflute tool with linear, spiral or circular cutting movement; feed-motion is implemented by means of lifting (stepping) tool’s cutting teeth.

sawing – cutting with circular or linear cutting movement of tool and any feed-motion in plane perpendicular to cutting movement; this type of processing is used for cut-off or making splines by tools with big number of teeth and low cutting width.

trimming – cutting work with repeated linear or circular cutting movement and low chip thickness; performed by tool with densely placed low level teeth.

Following definitions are used in cutting work technological methods with diffuse geometry tools:

grinding – processing with a tool with numerous edges, geometrical indefiniteness of their cutting point is due to vast number of grits made of natural and artificial abrasives; processing is characterized by high cutting speed, material is often removed in unsteady contacts between the workpiece and abrasive grit;

honed finishing – processing with a tool with numerous cutting edges, geometrical indefiniteness of their cutting point is due to vast number of grits made of natural and artificial abrasives; material is removed in permanent contact between the workpiece and abrasive grit;

lapped finishing (finishing, polishing) – processing with grit placed in liquid or paste (lapping mix), which travels toward workpiece by means of a lap; work surface of the lap is usually identical with processed surface, grit is moved as chaotic as possible;

tumble drum processing – cutting operation, when workpiece and abrasive grit or lapping mix travel toward each other in a reservoir, thus performing abrasing or lapped finishing.

irradiation – processing by emission directed at work surface from energy source.

Each component of the technological system ‘machine – accessory – tool – part’ is important for cutting work. Naturally, the most important of these is metal-cutting machine, which can be either manually controlled, with numerical program control, or with CNC control system. Yet appliances (machine accessories) influence processing precision directly. Manufacturing accuracy and structural stiffness of appliances are their determinant features. Manufacturing accuracy of appliances defines tolerances of cutting tools and workpieces location in machine tool, which is often crucial for shape and dimension of processed parts. Operational performance of appliances and accessories like stiffness and vibration resistance impose great influence on precision as well as asperity of processed surfaces and endurance of cutting tools. Economic efficiency of processing depends on degree of utilization of technology appliances. Machine equipment accessories, which enlarge technological capabilities of machine tools, are especially effective in single-job and batch production and can compensate absence of some types of devices, eliminate unnecessary parts transportation between machines and underutilization of specific types of machines. These appliances should not be underestimated. In many instances they define processing precision and performance, allow to implement programmed operations and center production processes together. Metal-processing appliances (also known as auxiliary tools) enlarge technological capabilities of machine tools, allow to boost level of motorization and automation of industrial processes and equipment and influence reliability of technological operations. As a rule, machine accessories are chosen for existing machines with already installed cutting tools for a specific technological operation. On one hand, an appliance must have seating surfaces and clumping elements that match the workpiece and the cutting tool, and on the other hand - seating surfaces and clumping elements that match mounting seats of the machine.

Machine equipment and accessories are various in type and design. They allow to install and secure cutters, drills, tap tools, bolt dies, chamfer bits, milling cutters and other tools, workpieces and parts to be mechanically processed. Often machine accessories allow installation and securing as well as position control of tools and workpieces.