外文翻译--液压传动系统设计与计算-液压系统(编辑修改稿)

外文翻译--液压传动系统设计与计算-液压系统(编辑修改稿)内容摘要：

putation, generally includes the start acceleration, quickly enters, the labor enters, quickly draws back, decelerates applies the brake and so on several stages, each stage overall load strength has the difference. (a) starts the acceleration period: By now the hydraulic cylinder or the piston were in from static enough to starts and accelerates to the certain speed, its overall load strength including guide rail friction force, packing assembly friction force (according to cylinder mechanical efficiency ηm= putation), gravity and so on item, namely: bmgif FFFFFF  () (b) fast stage: bmgf FFFFF  (c) the labor enters the stage: bmgfc FFFFFF  （ ） (d) decelerates: bmgif FFFFFF  () To the simple hydraulic system, the above putation process may simplify. For example uses the single proportioning pump to supply the oil, only must calculate the labor to enter the stage the overall load strength, if the simple system uses the limiting pressure type variable displacement pump or a pair of association pumps for the oil, then only must calculate the fast stage and the labor enters the stage the overall load strength. oil motors load When the operating mechanism makes the rotary motion, the oil motor must overe the outside load is: ife MMMM  () (1) operating duties moment of force Me. The operating duty moment of force is possibly a definite value, also possibly as necessary changes, should carry on the concrete analysis according to the machine working condition. (2) friction moments. In order to revolve the part journal place friction moment, its formula is: )( MNG F RMf  () In the formula: G is revolves the part weight (N)。 F is the rubbing factor, when the start for the factor, after the start for moves the rubbing factor。 R is the journal radius (m). (3) moment of inertiaMi. The moment of inertia which in order to revolve the part acceleration or decelerates when produces, its formula is: )( MNtJMi   () In the formula: ε Is the angle acceleration (r/s2)。 t is the acceleration or decelerates the time (s)。 J is revolves the part rotation inertia ( 2mKg ), GGDJ 41 2 In the formula: 2GD In order to rotate the part the flywheel effect ( 2MN ). Each kind may look up Machine design Handbook According to the type (), separately figures out the oil motor in a operating cycle various stages load size, then may draw up the oil motor the duty cycle chart 2 determinations hydraulic system main parameter hydraulic cylinders design calculations initially decides the hydraulic cylinder working pressure In the hydraulic cylinder working pressure main basis cycle of motion various stages biggest overall load strength determined, in addition below, but also needs to consider the factor: (1) each kind of equipment different characteristic and use situation. (2) considerations economies and the weight factor, the pressure elects lowly, then part size big, the weight is heavy。 The pressure chooses high somewhat, then part size small, the weight is light, but to the part manufacture precision, the sealing property requests high. Therefore, the hydraulic cylinder working pressure choice has two ways: One, elects according to the mechanical type。 Two, according to cuts the load to elect. If the table , the table shows. The table presses the load to choose the execution file the working pressure Load /N ＜ 5000 500～10000 10000～20200 20200～30000 30000～50000 ＞ 50000 Working pressure /MPa ≤～ 1 ～ 2 ～ 3 3～ 4 4～ 5 ＞ 5 The table presses the mechanical type to choose the execution file the working pressure Mechanical type Engine bed Farm machinery Project machinery Grinder Aggregate machinetool Dragon Gate digs the bed Broaching machine Working pressure /MPa a≤2 3～ 5 ≤8 8～ 10 10～ 16 20～ 32 oil motors design calculation putations oil motor displacement Under oil motor displacement according to the type decided that, )( 3m in rmPTV mm  () In the formula: T is the oil motor load moment of force (Nm)。 PmFor oil motor import and export pressure difference (n/m3)。 is the oil motor mechanical efficiency, the mon gear and the plunger motor takes ~ , the leaf blade motor takes ~ . putations oil motor needs the current capacity oil motor the maximum current capacity )( 3m axm ax smnVq m () In the formula: Vmis the oil motor displacement (m3/r)。 nmaxis the oil motor highest rotational speed (r/s). 3 hydraulic pressure parts choice hydraulic pumps determinations with need the power the putation (1) determines the hydraulic pump the biggest working pressure. The hydraulic pressure pumping station must the working pressure determination, mainly acts according to the hydraulic cylinder in the operating cycle various stages to have most tremendous pressure p1, in addition the oil pump loses Sigma Delta p the oil mouth to the cylinder place always pressureΣΔp, namely  PPPB 1 () P loses, the pipeline including the oil after the flow valve and other parts local pressures along the regulation loss and so on, before system pipeline design, may act according to the similar system experience to estimate, mon pipeline simple throttle valve velocity modulation system ΣΔp is (2 ~ 5) 105Pa, with the velocity modulation valve and pipeline plex system P is (5 ~ 15) 105Pa, P also may only consider flows after various control valves pressure loss, but ignores the circuitry along the regulation loss, various valves rated pressure loses may searches from the hydraul。