Parallel engine bed analysis

The parallel engine bed is based on the spatial parallel organization Stewart platform principle development, is one new concept engine bed which recent years only then appeared, it was the product which the parallel robot organization and the engine bed unified, is high tech product which spatial mechanism, the machine manufacture, the numerical control technology, the computer soft and hard technology and CAD/CAM the technology unified highly. It overcame the traditional engine bed series organization cutting tool only to be able along the fixed guide rail to feed, the cutting tool work degree-of-freedom to be somewhat low, equipment processing flexibility and mobility insufficient and so on inherent flaw, might realize the multi-coordinate linkage numerical control processing, the assembly and survey many kinds of functions, could satisfy the complex special components the processing. appeared on the market from its in 1994 on the American Chicago engine bed exhibition namely is honored as is for the first time “the 21st century’s engine bed”, became in the engine bed family most to have the vitality young blood. 1 parallel engine bed’s characteristic is as for the whole, the traditional series connected organization engine bed, is belongs to mathematics to be simple, but organization complex engine bed, but relative, the parallel organization engine bed organization is simple, but mathematics is complex, the entire platform’s movement involves to the quite huge mathematics operation, therefore the hypothesized axis parallel engine bed is one kind of knowledge intensity organization. This kind of new engine bed has broken the traditional engine bed structure concept completely, has abandoned the fixed guide rail’s cutting tool guidance way, has used the multi-pole parallel organization actuation, enhanced engine bed’s rigidity greatly, causes the working accuracy and the processing quality has the big improvement. other, as a result of its feed rate enhancement, thus makes high speed, the supervelocity processing to be easier to realize. Because this kind of engine bed has the high rigidity, high bearing capacity, the high velocity, the high accuracy as well as the weight light, the mechanism is simple, the production cost is low, the standardized degree higher merit, obtained the successful application in many domains, therefore receives the academic circle the widespread attention. By compound connection type numerically-controlled machine tool which parallel, series connected simultaneously is composed, not only has the parallel engine bed’s merit, and has the use value in the use. along with high-speed cutting’s unceasing development, the traditional tandem type organization constructs the platform the structure rigidity and the traveling carriage high speed becomes the technological development gradually the bottleneck, but the parallel platform then becomes the best candidate object, but was opposite in the tandem engine bed, the parallel working platform had the following characteristic and the merit: The structure is simple, the price is low. The engine bed mechanical spare part number is series connected constructs the platform to reduce largely, mainly by the ball bearing guide screw, the Hooke articulation, the ball articulation, the servo electrical machinery and so on common module is composed, these common modules may by the special factory production, thus this engine bed’s manufacture and the inventory cost are much lower than the same function’s traditional engine bed, easy to assemble and the transporting. The structure rigidity is high.because used closeness structure (closed-loop structure) to enable it to have high rigid and the high speed merit, its structural load streamline was short, but shouldered decomposes pulls, the pressure also to withstand by six connecting rods, by materials mechanics’ viewpoint, when the external force was certain, the bracket quantity’s stress and the distortion were biggest, the both sides inserted the (build-in) next best, came is again both sides Jan supports (simply-supported), next was the bearing two strength structure, what the stress and the distortion were smallest was the tensity two strength structure, therefore it had the high rigidity. Its rigidity load ratio is higher than traditional the numerically-controlled machine tool. The processing speed is high, the inertia is low. if the structure withstands the strength will change the direction, (will be situated between tensity and pressure), two strength components will be most save the material the structure, but it will move to the moving parts weight to reduce to lowly and simultaneously will actuate by six actuating units, therefore machine very easy high speed, and will have the low inertia. The working accuracy is high. Because it for the multiple spindle parallel organization composition, six expandable pole poles long alone has an effect to cutting tool’s position and the posture, thus does not have the traditional engine bed (i.e. connects engine bed) the geometrical error accumulation and the enlargement phenomenon, even also has the being uniform effect (averaging effect); It has the hot symmetrical structural design, therefore the thermal deformation is small; Therefore it has the high accuracy merit. Multi-purpose flexible. is convenient as a result of this engine bed organization simple control, easily according to processing object, but designs it the special purpose machine, simultaneously may also develop the general engine bed, with realizes the milling, boring, processings and so on grinding, but may also provide the essential measuring tool to compose it the measuring engine, realizes engine bed’s multi-purpose. This will bring the very big application and the market prospect, has the very broad application prospect in the national defense and the civil aspect. The service life is long. because the stress structure is reasonable, the moving part attrition is small, and does not have the guide rail, does not have the iron filings either the refrigerant enters the guide rail interior to cause it to scratch, the attrition or the corrosion phenomenon. The Stewart platform suits in the modular production. Regarding the different machine scope, only need change the connecting rod length and the contact position, maintains also easily, does not need to carry on part’s remaking and to adjust, only need the new organization parameter input. The transformation coordinate system is convenient. because does not have the entity coordinate system, the engine bed coordinate system and the work piece coordinate system transform depend on the software to complete completely, is convenient. When the Stewart platform applies in the engine bed and the robot, may reduce the static error (, because high rigidity), as well as dynamic error (because low inertia). But Stewart the platform inferiority lies in its working space to be small, and it has the singular point limit in the working space, but the serial operation platform, the controller meets time the singular point, accountant will figure out the actuation order which the drive is unable to achieve to create the ning error, but the Stewart platform will lose the support partial directions in the strange position the strength or moment of force ability, will be unable to complete the constant load object. the DCB510 parallel engine bed 2 parallel engine bed’s research present situations since 1965 Stewart proposed that the famous Stewart platform organization, henceforth started based on the Stewart parallel organization hypothesized engine bed research. But start, the people also are only pause to this kind of organization in the theoretical analysis. in 1994, displayed and causes the world stir’s parallel 6 leg engine bed for the first time at the American Chicago IMTS exposition (to call parallel engine bed), after passing through continues three year whole world to follow up afterward the tide, around the world decreased temperature gradually. This is because the parallel engine bed has a series of difficult problems in the theory and the practice, solves in a short time with difficulty. At present, domestic and foreign has many companies and the research unit in the research hypothesized axis engine bed. Our country’s parallel engine bed research start is late, but the achievement is remarkable. the Tsinghua University is the home starts to carry on one of most early hypothesized axis engine bed research units, has conducted the deep research to the hypothesized axis engine bed as well as many related domains, and in December 25, 1997 and the Tianjin University cooperation, developed our country first large-scale boring mill class hypothesized axis engine bed prototype prototype - VAMT1Y together. And so on key technologies aspect have achieved the international advanced level in the hypothesized axis engine bed design theory and the prototypical construction, the partial theory achievement is the international origination. At present is carrying on the hypothesized axis engine bed seriation, the practical research, has carried on the new hypothesized axis engine bed commercialization prototype’s development work with many engine bed backbone factory, realizes the hypothesized axis engine bed’s industrial production by the time. and the Kunming engine bed Limited liability company, the East of the lower reaches of the Changjiang river Machine tool factory and Dalian Machine tool factory union development’s three kind of different configuration’s engine beds already came out, and displayed with 2001 on CIMT, will realize the commercialization hopefully in the near future. XNZ63 hypothesized axis engine bed which develops together with the Kunming engine bed Limited liability company, may realize the multi-coordinate linkage numerical control processing, the assembly and survey many kinds of functions, can satisfy the complex special components the processing, its overall target has achieved the international advanced level. With an East of the lower reaches of the Changjiang river Machine tool factory unit exploitation’s Dragon Gate type hypothesized axis engine bed, the structure uses the biprism Dragon Gate work table mobile, may complete 4 coordinate linkages. With Dalian Machine tool factory union development DCB-510WU the axis linkage series-parallel connection engine bed, can realize X, Y and the Z direction migration through the parallel organization, uses traditional the series connected way to realize main axle neck A and the C direction rotation. moreover also obtains by the Tianjin University design and with the Tianjin first machine tool factory union development’s parallel engine bed successful and achieves the practical level. Harbin Engineering University and the Tsitsihar second engine bed enterprise group unites the development the BJ-1 parallel engine bed, the existing type technical parameter is:①Working range: f400×250;②Spindle speed: 0~8000 r/min;③Electricity main axle power: 9kW;④Trussing servo electrical machinery power: 0.75kW;⑤Duplicated precisions: 0.002mm (static state);⑥Pointing accuracy: 0.015mm;⑦Volume: 1800×1500×2300;⑧Numerical control system: Grinds the overseas Chinese laborer to control machine + six axis linkage card. The Northeast University newest development’s DSX5-70 three pole hypothesized axis engine bed is five degree-of-freedom hypothesized axis engine bed which is composed of three degree-of-freedom’s parallel organizations and two degree-of-freedom’s series connected organization compound connection. And, two degree-of-freedom series organization puts in the movement platform, the entire organization may realize five axis linkages through three pole’s expansions and two drive shafts, with completes many kinds of job tasks. unites the development by the National University of Defense Technology and the Hong Kong University of Science and Technology the Milky Way - - 2000 hypothesized axis engine bed is one kind of parallel six degree-of-freedom engine beds, is comes by the traditional parallel engine bed development, at maintains the original parallel organization many merits, if the high rigidity, outside the high accuracy and the high velocity of movement, expanded engine bed’s movement scope with the variation organization. Sweden Neos Robotics Corporation, because has used the parallel Canadian series plan, does from the low level application, gains in the experience and the financial resource gradually, to the top level application development, as well as has used three pole central central tubes and so on correct measure, its parallel engine bed product already enters practical, until now has created 200 Taiwan’s shocking sales results. This company displays the Tricept845 machining center, its volume pointing accuracy achieves ±50m, the redundant pointing accuracy reaches ±10m, although these two targets also have the big disparity from the traditional engine bed, but already is the significant breakthrough to the parallel engine bed, has the use value. Its feed rate has reached 90m/min, the acceleration has reached 2g, the main axle power is 30~45kW,24,000~30,000r/min, uses the Swiss IBAG Corporation electricity main axle, the Siemens840D numerical control system and the Heidenhain measurement system. This machining center uses the modular structure. Three pole structure module has 0°, 45°, 90° three kind of layouts to be possible optional (i.e. to compose horizontal type, incline separately 45° and vertical machining center). The German Fraunhofer engine bed and the formation Technical research institute develops the 6x engine bed is suitable for mold’s high speed processing, its major technique parameter is: Work table: 630×630, X, Y, the Z traveling schedule is 630mm, two rotational degree of freedom scope for 30°, the main axle maximum speed is 3000r/min, the power is 16kW, leg’s most roughing feed speed is 30m/min, the acceleration is 10m/s. the German Index American Subsidiary company uses in the parallel engine bed the lathe, produced the V100 three pole parallel organizations “to stand upside down the vehicle” (i.e. main axle and work piece makes X, Z axis movement on, but cutting tool under motionless, might return transforms knife, but did not make any translation vertical lathe, our country custom was called “stands upside down vehicle”). It has the following merit:①The contour is compact. The lathe did not look like the machining center, the work piece relative cutting tool’s moving range is small, has overcome the parallel organization space effective use factor low weakness.②The lathe only needs two degrees-of-freedom generally (X and the Z axis), presently uses three pole geometry organization, may obtain X, Y, the Z three degrees-of-freedom, a redundant degree-of-freedom may serve as in the freedom the yummy treats to use. In addition