The experiment of linear feed unit studies machine tool of high speed numerical control

1 ～ 0.

2G(G=9.

The level of 8m/s2) . Because the feed distance of the machine tool is short, had not achieved rate of the biggest feed quickly must decelerate, restricted a machine tool thereby of speed of the biggest feed rise, get used to the demand that machine tool of contemporary high speed expands hard. The development of linear electric machinery and advanced frequency conversion control high-power technical development, the development that is system of high speed feed and development offerred advantageous condition. Use linear electric machinery the workbench of direct drive machine tool eliminated link of the transmission intermediate not only, enhanced transmission efficiency, and the rate that raised feed system greatly and acceleration, can better land gets used to the development demand that high speed machines. 1.

Cable towline 2.

Grating feet 3.

Workbench 4.

Primary 5.

Primary dead plate 6.

Lathe bed 7.

Linear slideway 8.

Sub 9.

Sub dead plate pursues 1 GD-4 of composition of a picture of cement of unit of 1 linear feed high speed is linear linear feed unit uses feed unit GD-3 high speed inductive formula is straight electric machinery is direct drive, construction of system is shown 1 times like the graph. The system is used move primary, calm sub, short primary, long sub structural means, among them primary be linked together with workbench installed surface through dead plate, and sub use series connection means to pass dead plate tile to be on lathe bed. When class connects three-phase alternating current first, can produce travelling wave magnetic field, cut is sub, make electromotive force of sub generation reaction, be in thereby close loop forms n/ele be induced by electric current subly. Sub n/ele be induced by electric current and simple are handed in change thrust of electromagnetism of generation of magnetic field interaction, make primary with sub between generation moves relatively. The speed of the size of athletic speed and travelling wave magnetic field becomes direct ratio. Use frequency control technology, will change the rate of electric machinery through adjusting power source frequency, the high speed that can realize workbench is linear feed moves. In unit of GD-3 linear feed, the speed of the biggest feed of linear electric machinery is 100m/min, the biggest thrust that start is 4550N, rated thrust is 2000N, rated power is 8kW, the system uses grating to survey feedback plant, have closed-loop control to feed unit, the resolution of grating is 3 μ M, control construction of system, if pursue 2 show. Graph unit of feed of 2 linear electric machinery controls a system to pursue by the graph 2 knowable, unit of GD-3 linear feed uses total number word to control a system. Control system basically is mixed by computer of transducer, drive 3 parts comprise SERCOS interface. The main effect of transducer is the traversal speed that will control linear feed unit through changing the frequency of power source. The main effect of drive computer is deferent control instruction, the electric current that accepts feedback of the speed that measures systematic feedback by displacement and displacement information and system of electric machinery test and magnetic field information, realize unit to feed closed-loop control. Control system can come true through SERCOS interface take lag quantity and the place that do not take lag amount to adjust, the adjustment of speed adjustment and force, make feed unit acquires precision of high fixed position, tall stiffness and good dynamic character. In high speed treatment, linear feed unit can acquire taller treatment precision and exterior quality through accurate interpolation and minim feed. In the meantime, control system is OK still start feed unitly and breakdown diagnostic information shows directly go up in NC terminal, so that know treatment in time information, remove systematic trouble, those who assure high speed machine tool is efficient move. Accordingly, with traditional NC machine tool " rotate servo electric machinery + ball guide screw " feed means photograph is compared, this kind of new-style linear feed unit has the following characteristic: Use linear electric machinery direct drive. Leave out all mechanical drive intermediate, from go up at all reduced machine rub caustic and transmission error; Feed journey is absoluteness; Move stiffness and static stiffness tall; Have higher rate and acceleration; Have higher control performance and higher Kv factor; Use frequency control technology to be able to implement stepless speed regulation; Orbit error is small, good fixed position precision can be obtained below high speed. 2 experiments study this experiment is research target with unit of GD-3 linear feed, this feed unit is the biggest permission working travel is 750mm. Use process designing of CNC numerical control to undertake to feed unit experimental research and test are analysed. Numerical control program is as follows: G90 G18 G54... G01 X600 F10000/F60000 G04 F1.

0G01 X0 F10000/F60000 G04 F1.

0RET; G74 X0 F10000/F60000 RTS is 10m/min when set of academic feed speed, when working journey set is 600mm, unit to the feed that moves circularly continuously speed and acceleration undertake check in real time and be analyticed, if pursue,as a result 3 are shown. Graph the acceleration when 3 feed speed is 10m/min and speed signal pursue the acceleration when 4 feed speed is 60m/min and speed signal by the graph 3 knowable, the acceleration of the biggest feed of feed unit is 2.

7m/s2, the biggest slowdown is spent for - 2.

7m/s2, speed-distance curve is echelon curve, the oldest rate is instantaneous 12.

5m/min, the largest amount exceeding tone is 25% , rise fast time for 0.

08s. Below steady state, feed speed agrees for the academic feed speed of 10m/min and set. It is 60m/min when set of academic feed speed, when working journey set is 600mm, unit to the feed that moves circularly continuously speed and acceleration have a test, if pursue,as a result 4 are shown. By the graph 4 knowable, below condition of high speed feed, the biggest feed acceleration is 15m/s2, the biggest feed decreases speed to be - 15m/s2, speed-distance curve and graph 3 similar, also present echelon curve feature, speed of the biggest feed is instantaneous 75m/min, quantity exceeding tone is 25% , answer time for 0.

08s, below steady state, the speed of feed unit is the feed speed of 60m/min and academic set to agree, because this shows GD-3 high speed is linear,feed unit has taller acceleration and decelerate to spend and answer character goodly. Comprehensive plan 3, graph 4 knowable, feed unit has good stability in athletic process, without occurrence oscillation phenomenon, at the same time feed unit is in circular campaign process, have good repeatability, avoided the flaw with the as a result of existence backlash poor repeatability in traditional feed system. Because unit of this GD-3 linear feed can obtain taller feed acceleration and decelerate spend not only, and can obtain good repetition fixed position precision, can better land gets used to the requirement of high speed CNC Machining. Linear feed unit uses 3 conclusion GD-3 high speed linear electric machinery is direct drive workbench, have shorter transmission cable length and lesser mechanical wear, eliminated backlash, can obtain taller repetition fixed position precision. This linear feed unit uses frequency control and digital control technology, can implement stepless speed regulation, it is good to can charge a sex, have good low speed character not only, and the acceleration that can obtain 15m/s2 below high speed moving condition and - the decelerate of 15m/s2 is spent, can better land gets used to the need that high speed machines. CNC Milling