MACHINE TOOL. Cone pulley drive 10/17/2011. Can Absorb shock High mechanical efficiency Smooth running

Transcription

1 MACHINE TOOL Gear drive system Cone pulley drive Can Absorb shock High mechanical efficiency Smooth running Large number of step is not available Time for setting speed is high 1

2 n d i1 = = n d II1 I1 I II1 i 2 n d = = n d II2 I2 I II2 n d i = n 1 n = d IIn 1 In 1 I II n 1 n d i = n 1 n = d IIn 1 In 1 I II n 1 i d n I d i d d n n 1 =. = n 1 I II So, Q n II n + Q = φ φ Properties of Cone Pulley drive If the central distance of the two cone pulley is larger than 10( dmax dmin ) and summation of diameter pair is constant then the belt remain tight for all position. Transmitted power varies with different belt position. To avoid much variation of power and toque, the drive should be designed so that d max d min < 2 2

3 ADVANTAGES OF ALL-GEAR SPINDLE DRIVE OVER CONE PULLEY DRIVE. High power transmission. Quick speed change though levers. compact and require less floor space. METHOD OF SPEED CHANGING Slip gear The mating gear pair on two adjacent shaft are interchanged or replaced by another pair of gears. The condition for the interchangeability- T1 + T2 = T3 + T4 = T5 + T6 3

4 SLIDING KEY METHOD Two sets of gear on two shaft are constantly in mesh. One set is free to rotate on the shaft. Only one gear of free set is engaged by a sliding key. TUMBLER GEAR A number of gear is placed in one shaft which is at fixed distance from the output shaft. Used usually for feed drives an known Norton gearbox. 4

5 SLIDING TYPE CLUSTER GEAR A set of cluster gear is moved along a shaft to engage another set of gears (one gear cluster is fixed at a time). JAW CLUTCHES Speed can be changed by engaging and disengaging clutches with levers. Advantages of this speed changing method- They require small axial movement. Helical and herringbone gear can be used. Force required to shift them is less than that for sliding cluster gear. 5

6 FRICTION CLUTCHES Limiting torque capacity High torque capacity large axial and radial dimension TYPE OF FEED GEAR BOX Feed gearbox with slip gears Feed gearbox with slip gear quadrant feed gearbox with sliding gears Feed gearbox with sliding key Norton gearbox Meander gearbox 6

7 INFINITELY VARIABLE DRIVE Advantages possible to attain optimum cutting condition Important in reduction of handling time, because speed, feed can be changed without stopping the machine. Constant cutting speed can be obtained for stepped shaft and irregular contour. Tool life is improved and high surface finish. Reduce vibration and noiseless. MECHANICAL INFINITELY VARIABLE DRIVE Through the axial displacement of roller A, the effective diameter of roller B is varied infinitely and thus the transmission ratio, i is changed continuously, r i = R 7

8 WUELFEL KOPP TOURATOR Honda roller based CVT 8

9 P.I.V(POSITIVE INFINITELY VARIABLE) DRIVE P.I.V(POSITIVE INFINITELY VARIABLE) DRIVE 9

10 P.I.V(POSITIVE INFINITELY VARIABLE) DRIVE HYDRAULIC DRIVE SYSTEM Used pressurized oil to transmit energy Higher the viscosity index, better the oil thinner the oil higher the leakage problem but lower energy loss in pipe lines and valves. Other fluid properties: Compressibility Stable chemical composition Low moisture content Low coefficient of thermal expansion Low air inclusion 10

11 GEAR PUMP(INTERNAL) GEAR PUMP(EXTERNAL) 11

12 GEAR PUMP FLOW RATE π bm Q = 2. ( d + 2m) ( d 2m) π 8 dm. b. n Q = π dmbn Q = ( l / min) πtm bn Q = ( l / min) 500 P = Q. p.10 ( hp ) η Q= Theoretical Flow rate(l/min) d= Pitch diameter(cm) m= Module(cm) b=gear width(cm) n=gear speed(rpm) T=Number of teeth of gear P=Power of the electric motor p=delivery Pressure η= Mechanical efficiency= Screw Pump 12

13 Screw Pump Supply rate varies from l/min Speed rpm Working pressure x 10^5 pascal (low pressure) x 10^5 pascal (medium pressure) x 10^5 pascal (high pressure) Vane pump Vanes are subjected to side wise thrust Frictional loss (fric coeff = ) Necessary to maintain low eddy loss and low temperature 13

14 Piston pump Radial Piston pump Maximum supply rate 500 l/min High oil pressure can be obtained(150 x 10^5 pascal) Piston pump Axial piston pump Cylinder body remain static Movement of piston is controlled by swash plate Torque is transmitted through universal joint thus limited 14

15 Number of vanes and pistons Frost-Enor Drive Consists of A hydraulic vane pump A hydraulic motor A casing Oil supply line Derive the expression of speed, power and torque for primary and secondary control of a Frost-Enor Drive 15

16 Hydraulic cylinders Convert the hydraulic energy of a fluid into the kinetic energy of piston. Consist of Hydraulic pump Fluid distributing device Cylinder with piston and piston rod That s all for today Download the slide form 16