Simulation Driven Optimized Mechanism Drive

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1 Simulation Driven Optimized Mechanism Drive August 30, 2011 Elias Taye, PhD Wm Wrigley Jr. Company Subsidiary of Mars Inc. 1

2 AGENDA Introduction of Wm Wrigley Jr. Company Original Design of the Mechanical Linkage Objective of Simulation Rigid Dynamic Analysis Transient Structural Analysis Issues First Design Optimization Objective of Simulation Rigid Dynamic Analysis Transient Structural Analysis 1 st Optimization Summary Second Design Optimization Objective of Simulation Rigid Dynamic Analysis Transient Structural Analysis 2 nd Optimization Summary Experimental Validation of Actuator Driven Mechanical Linkage Conclusion 2

Wm Wrigley Jr. Company Wrigley is a recognized leader in confections.

Family owned company founded in 1911 Products Gum, Mints, Hard & Chewy Candies, Lollipops and

Chewing: Increased alertness, focus and concentration Improve Oral Health: helps fight

3 Wm Wrigley Jr. Company Wrigley is a recognized leader in confections. Headquarter is in Chicago, IL, & operates as subsidiary of Mars Inc. Family owned company founded in 1911 Products Gum, Mints, Hard & Chewy Candies, Lollipops and Chocolate Operates in more than 40 countries and distributes in 180 countries Benefits of Chewing: Increased alertness, focus and concentration Improve Oral Health: helps fight cavities, neutralize plaque acids, remineralize enamel to strengthen teeth and wash away food particles. Weight management help control cravings Stress relief 3

ORIGINAL DESIGN Mechanism Has one rotational input that further splits

structural steel Boundary Condition Input: Angular Rotation of cam shaft

Objective of modeling: Calculate the Shaking Force, Bearing load and

4 ORIGINAL DESIGN Mechanism Has one rotational input that further splits into two different translation motions All components are made of structural steel Boundary Condition Input: Angular Rotation of cam shaft ( 0) Constraints: Applied joints between rigid & flexible bodies Objective of modeling: Calculate the Shaking Force, Bearing load and structural stiffness for current speed ( 0) To model the mechanism for high speed (2x 0) 4

5 Original design Simulation Results and Issues Has high max. Shaking Force 464 Lbf (2063N) Has high max. Driving Torque 590 Lbf ft (800Nm) Cam generating the vertical motion has the max load The cams have harmonic motion profile The jerk function is infinite at dwell ends Has sudden change in acceleration This is a source for vibration and noise The Fork performs a triangular motion abrupt of smooth motion Stresses are within the material strength limit Fork Motion Profile Fx Fy Fz Sum Shaking Force Transfer Fork Total Reaction Force, 600 RPM 2063N Input Torque 590Lbf ft 1000 Force (N) Rotation ( ) 5

1 st design optimization - cam Objective: Reduce Dynamic Load 1. Redesign both Cams 2.

Cam Synthesis Current Design Harmonic Cams Sudden change of acceleration at dwell The jerk

Design Cycloidal Cams NO Sudden change in acceleration Used for high speed application Very

6 1 st design optimization - cam Objective: Reduce Dynamic Load 1. Redesign both Cams 2. Improve Fork motion profile 1. Cam Synthesis Current Design Harmonic Cams Sudden change of acceleration at dwell The jerk function is infinite at dwell two jerks per revolution this generates vibration & noise New Design Cycloidal Cams NO Sudden change in acceleration Used for high speed application Very low vibration Jerk function is finite across the entire 360 interval The first and second derivatives of displacement are continuous reduces the dynamic inertia of machine 6

1 st design optimization Redesign linkage & Motion

7 1 st design optimization Redesign linkage & Motion profile 2. Optimizing Fork Motion Profile Understand existing motion profile Eliminate the abrupt motion and redesign new cams timing Original Motion Profile 3. Redesign Linkage To reduce bearing load To fit within packaging constrain on horizontal direction Modified Motion Profile 7

8 1 st design Optimization dynamic analysis - Bearing Load F = 305Lbf (1356N) F = 286Lbf (1272N) F = 239Lbf (1063N) F = 89Lbf (395N) F = 74Lbf (329N) F = 100Lbf (445N) 8 Max. Bearing Load has Reduced

9 1 st design Optimization dynamic analysis Input torque T = 1082Lbf in (122Nm) T = 1207Lbf in (136Nm) Input Torque has significantly REDUCED 9

1 st design Optimization kinematic analysis 1 = 8.0679 2 = 13.057 3 = 22.

10 1 st design Optimization kinematic analysis 1 = = = Calculated also Speed & Acceleration at each Kinematic Pairs These are important information for the next Design Optimization 10

11 1 st design Optimization Transient structural Analysis Fork Displacement Max. VM Stress = 8.56E6Pa (1241psi) 11

12 1 st design Optimization Transient structural Analysis Max. VM Strain = Max. Normal Stress 9.16E6Pa (1347psi) Max Principal Stress 1.138E7Pa (1673psi) The stresses are way below the material strength limit Aluminum material 7075 T6 ( y ~ 36000psi) 12

13 1 st design Optimization - animation Mechanism Animation 13

1 st Optimization summary Analysis Result Dynamic load has reduced significantly Less bearing load Less input torque requirement observed less vibration/ noise Replaced the structural steel by

14 1 st Optimization summary Analysis Result Dynamic load has reduced significantly Less bearing load Less input torque requirement observed less vibration/ noise Replaced the structural steel by Aluminum material Better Space usage behind the machine frame The improved fork motion profile (rectangular vs. triangular) reduces the dynamic load ANSYS Rigid Body Dynamic and Transient Structural Analysis have greatly helped us to improve our design within a short period of time. The final design of the First Design Optimization is built and installed in our machine. 14

15 2 nd Optimization Electronic Camming Mechanical Cams are replaced by Electronic Camming Servos Timing in angular position is calculated to produce the same motion profile Results obtained from Rigid Body Dynamic Without ANSYS it would be difficult to extract this important information Developed Prototype Pros of Servo Driven Mechanism Less mechanical components Less inertia Simplified design Less power, torque and current consumption Better position control 15

16 2 nd Optimization - Animation Servo Driven Mechanism Animation 16

17 2 nd Optimization electronic Camming Defining Cam Timing Developed cam timing as a function of time Converted the timing to drive machine (master axis) angular position Modified the cam timing 17

18 2 nd Optimization Transient structural Analysis VM Strain = 5.637e 5 Von Mises Stress 4.0E6Pa (588 psi) Max Principal Stress 3.256E6Pa (479 psi) The stresses are way below the material strength limit Aluminum material 7075 T6 ( y ~ 36000psi) 18

19 2 nd Optimization Dynamic Analysis F = 17Lbf (75N) F = 25Lbf (111N) F = 87Lbf (386N) F = 29Lbf (129N) V = 42in/sec V = 90 in/sec Bearing Load has Reduced significantly even without optimizing the linkage 19

20 experimental validation Front View of Test Setup Yaskawa Servo Control Test Bench Rear View of Test Setup 20

21 experimental validation video clip SLOW SPEED run of Servo HIGH SPEED run of Servo 21

component or system is not operating close to its natural frequencies Excited

22 experimental validation Modal analysis At higher speed the motor starts chattering due to overload Lower Rated Motor Torque Conducted Modal Analysis to make sure that the component or system is not operating close to its natural frequencies Excited frequencies are not close to its natural frequencies 6 th Mode 1 st Mode 4 th Mode 309 Hz 622 Hz 1525 Hz 22

23 2 nd design optimization - conclusion The Servo Driven Mechanism Design has been validated and showed significant improvement compared to Original & 1 st Design Optimization The prototype is designed to replace the existing mechanical cam linkage for proof of concept has potential for further optimizing the linkage the mass can be reduced up to 60% or more which eventually reduces the dynamic load of the system The Servo Design has Less mechanical components Less inertial mass Less power, torque and current consumption this leads to cost reduction Very low vibration and noise The Optimized Servo Design will be used in our new high speed machine. 23

24 THANK YOU 24

Cam makes a higher kinematic pair with follower. Cam mechanisms are widely used because with them, different types of motion can be possible.

CAM MECHANISMS Cam makes a higher kinematic pair with follower. Cam mechanisms are widely used because with them, different types of motion can be possible. Cams can provide unusual and irregular motions