中英文翻譯數(shù)控技術(shù)-在線瀏覽
2025-03-25 21:47本頁(yè)面
【正文】 ed，it is stored．When the entire number has been dialed，the equipment bees activated and the call is pleted．Silicon photo diodes，located in the tape reader head on the control unit，detect light as it passes through the holes in the moving tape．The light beams are converted to electrical energy，which is amplified to further strengthen the signal．The signals are then sent to registers in the control unit, where actuation signals are relayed to the machine tool drives．Some photoelectric devices are capable of reading at rates up to 1000 characters per second．High reading rates are necessary to maintain continuous machine—tool motion；otherwise dwell marks may be generated by the cutter on the part during contouring operations．The reading device must be capable of reading data blocks at a rate faster than the control system can process the data．A feedback device is a safeguard used on some N／C installations to constantly pensate for errors between the manded position and the actual location of the moving slides of the machine tool．An N／C machine equipped with this kind of a direct feedback checking device has what is known as a closedloop system．Positioning control is acplished by a sensor which，during the actual operation，records the position of the slides and relays this information back to the control unit．Signals thus received ale pared to input signals on the tape，and any discrepancy between them is automatically rectified．In an alternative system，called an open—loop system，the machine is positioned solely by stepping motor drives in response to mands by a controllers．There are three basic types of NC motions, as follows: Pointtopoint or Positional Control In pointtopoint control the machine tool elements (tools, table, etc.) are moved to programmed locations and the machining operations performed after the motions are pleted. The path or speed of movement between locations is unimportant。 only the coordinates of the end points of the motions are accurately controlled. This type of control is suitable for drill presses and some boring machines, where drilling, tapping, or boring operations must be performed at various locations on the work piece. StraightLine or Linear Control StraightLine control systems are able to move the cutting tool parallel to one of the major axes of the machine tool at a controlled rate suitable for machining. It is normally only possible to move in one direction at a time, so angular cuts on the work piece are not possible, consequently, for mi
畢業(yè)設(shè)計(jì)相關(guān)推薦
鄂ICP備17016276號(hào)-1