機械專業(yè)畢業(yè)設計---英文翻譯原文-免費閱讀
【正文】 dimensional tolerances are on the order of 177。 servo system based on orderdriven control system for machine tools, cutting tools and ponents to enable the implementation of the provisions of NC code movement。 they may be less than one second for small tools , or up to 30 seconds for tools weighing 110 kg (250 lb) ． The trend in tool changers is to use simpler mechanisms ,resulting in faster toolchanging times ． Machining centers may be equipped with a tooland/or partchecking station that feeds information to the puternumerical control to pensate for any variations in tool settings or tool wear ． Touch probes can be automatically installed into a tool holder to determine reference surfaces of the workpiece , for the selection of tool settings , and for the online inspection of parts being machined． Note in that several surfaces can be contacted , and that their relative positions are determined and stored in the database of the puter software ． The data are then used to program tool paths and to pensate for tool length and diameter , as well as for tool wear in more advanced machine tools ． Types of Machining and Turning Centers Although there are various designs for machining centers , the two basic types are vertical spindle and horizontal spindle 。 they collect chips along the two troughs and deliver them to a collecting point ． Other systems may use chaintype conveyors ． Machinetool Selection Machining centers can require significant capital expenditures , so to be cost effective , they generally have to be used for at least two shifts per day ． Consequently , there must be sufficient and continued demand for products made in maching centers to justify this purchase ． Because of their inherent versatility , however , machining centers can be used to produce a wide range of products , particularly with justintime manufacturing ． The selection of the type and size of machining centers depends on several factors , among which are the follwing : ? The type of products , their size , and their shape plexity ? The type of machining operations to be performed and the type and number of cutting tools required ? The dimensional accuracy required ? The production rate required Although versatility is the key factor in the selection of machining centers , these considerations must be weighed against the high capital investment required pared to the costs of manufacturing the same products using a number of more traditional machine tools ． Basic Operation of NC Machining Centers Manual Operation of Machining Centers Manual operation involves JOG and MDI. 1) Jogging control JOG method After turning the machine on, press “jogging” key on the machine control panel and thoose JOG operation mode. If JOG state interface appears on the screen, then the adjustment for the spindle worktable location can be performed. 畢業(yè)設計◆英文翻譯原文 第 5 頁 共 6 頁 2) Manual control MDI method. With MDI mode, a part program block can be made to control its operation. Detailed procedure is as follows. First, press the key “manual data input” on the machine control panel, choose MDI operation mode , press “inset” and “delete MDI program soft key” , then input different kinds of programs. With this procedure, all the function op
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