A special machine builder in Canada , who has specialized in custom integrated lines to automate packaging lines for global companies approached Motion Index Drives for a precision rotary solution. The customer wanted a 5-station (72 degree rotation) rotary index table able to rotate in a fast and extremely smooth fashion without vibrations or sudden jerking movements when starting and stopping of rotation. The indexer would have to be capable of an extreme offset load as it was normal for only two or three stations at a time while the opposite side would be empty. The total load per each station on the palletizer frame was 3000 lbs. per station. The weight of the steel fabricated pentagon structure added an additional 6500 lbs. to be rotated. Accuracy of the rotation at each station had to be within 45 arc seconds as the swing diameter of the pentagon structure was just over 16 feet (192”). The accuracy was required for the palletizer to line up with the loading elevator system. Another critical component to the application was the 5-station rotary table had to stop the load as quickly as possible.
Motion Index Drives barrel cam rotary index drive RT900-5 five station rotary index table fit the end customer’s specification. Our RT900-5 is equipped with a fixed five station barrel cam and output dial to achieve a 72 degree rotation and locking dwell when in position. The fixed five station barrel cam in the RT900 unit is machined to give a smooth acceleration and smooth deceleration that is free of vibration and jerky movements when starting and stopping. The cam profile is machined on a CNC 5 axis machine. After machining the cam track is heat treated to a 62 HRC. Our heat treat process achieves a minimum of a 5 mm case hardening depth allowing for a very robust cam track. After the cam is heat treated it is machined again to take out any imperfections the heat treating process may have caused. In addition to the heat treated cam track we equip the RT900 (and most of our other models) with cylindrical cam followers. The cam follower is also case hardened and ground. Because of these features our rotary index tables are capable of moving heavier loads in a smaller package than what our competitors offer. These features are also engineered with safety in mind. The case hardened cam and cylindrical cam followers enable us to have very fast stop times for emergency purposes. In this application the RT900 was able to stop the load of 20,000 kgm2 (68,343,438 in lb2) of inertia at the highest velocity in 0.7 seconds. The accuracy of +/-15 arc seconds for the RT900-5 far exceeded the requirement the customer needed for the palletizing application. The large ~53 inch slewing ring bearing assembly that RT900 utilizes has a capacity of 1000 kNm giving the customer over 10:1 safety factor in regards to the tilting moment when the palletizer would be loaded only on one side. The calculated tilting moment for the application was 81kNm.