Common basic components of nc machine tool is introduced

Nc machine tools in general by control medium, numerical control equipment, servo system and the ontology of the machine. In order to improve the machining accuracy of machine tool, then add in the system a measuring device ( The dotted line part of the above) That constitute the closed-loop control block diagram for nc machine tools. The working process of the open loop control system is this: to control the machine table movement direction of the displacement and displacement velocity and displacement, displacement track device such as a medium by controlling the input parameter to numerical control machine tool, CNC equipment instructions based on these parameters calculated feed pulse sequences ( Contains the above four parameters) , then amplified by servo system transformation, and finally control the workbench, in accordance with the requirements of the speed, path, direction and distance to move. If for the closed loop system, in the input command values at the same time, feedback of testing machine table is incorrect, the displacement value between feedback and input in the numerical control device is used in the comparison, if investors value, that is poor, the numerical control equipment control to eliminate the error in the direction of the movement of the machine. Will now briefly describes each component is as follows: 1, the control medium CNC machine work, don't need workers to handle operating machine tools, but people's intentions to be executed automatically, it must be in and establish a relationship between nc machine tool, the link intermediary call control medium ( Medium or program, input medium, information carrier) 。 Common control medium is 8 units of standard perforated tape, and it's commonly used punch tape paper, say again so paper tape. Its width is 25. 4 mm, thick 0. 108 mm, besides must have a phi 1 in each row. 17 mm synchronous hole, there can be a maximum 8 phi 1. 33 mm hole of information. With each row 8 hole with and without a permutation and combination of different code ( Tape on the hole arrangement, known as code) 。 Bring perforated tape reader of the input to the numerical control device, again by the perforated tape reader with code into a numerical control device can recognize and deal with electrical signals, and transmits to the numerical control device, and completed the work instruction information input. 2, CNC gear CNC is the centre of the nc machine tool, in the general nc machine tools in general by the input device, memory, controller, arithmetic unit and an output device. Numerical control device receives input media information, and its identification, storage, operation code, the corresponding instruction pulse output to drive servo system, and control for machine tool motion. In computer numerical control machine tool, the computer itself contains arithmetic unit, controller, such as the unit, so the role of the numerical control device are done by a computer. 3 the effect of servo system, servo system is to put the pulse signal conversion from the nc devices for machine tool motion of moving parts, the workbench ( Or walking board) Accurate positioning or track strictly according to regulations of relative movement, finally work out to meet the requirements of drawing parts. In the CNC machine tool servo system, commonly used servo driving element has power stepping motor, electric hydraulic pulse motor, dc servo motor, ac servo motor and so on. 4, machine tool nc machine tools in the machine tool, use the general machine tools at the beginning, only in automatic transmission, automatic tool post or workbench transposition and handle make some change. Practice proves: CNC machine tools in addition to because the cutting parameter, such as continuous processing fever more influence, workpiece precision and automatic control, because it is not like on the universal machine tool in processing can be carried out by artificial intervention. So its design requirements than the general machine tools more strict, more sophisticated manufacturing requirements. So later in the numerical control machine tool design, adopted many new strengthen rigidity, reduce the thermal deformation and improve the precision of measures, such as making the external modelling of nc machine tools, general layout, the transmission system and tool system and so on have been great changes have taken place.