Automation Profiles: System Assembles Hydraulic Valves
July 28, 2010
Equipped with both SCARA and six-axis robots, this 16-station automated assembly system produces hydraulic valves.
Due in part to increased global industrialization, demand for one manufacturer’s hydraulic valves was soaring. The company needed to increase production. Already familiar with automation and robotics, the company turned to RND Automation & Engineering of Sarasota, FL, to help design and build an automated assembly machine.
With more than 15 years experience designing, manufacturing and retrofitting custom automation and material handing machinery, RND was up to the challenge.
“RND worked closely with the customer to determine the sequence of operation of the machine,” explains Sean Dotson, PE, president of RND Automation. “Machine testing and uptime criteria were considered in the selection of components, [including] motors, actuators and robots.
“Using Autodesk Inventor, a 3D modeling CAD package, RND was able to illustrate to the client how the machine would operate at each design review. Using Inventor, the paths and envelopes of the robots could be animated showing the operation of each station before any materials were purchased.”
After approval of each station, RND worked closely with a stable of machine shops, fabricators and other vendors to procure the parts for the system. Assembly was done at RND’s 5,000-square-foot facility. Simultaneously, RND’s electrical control’s group was designing the electrical enclosure, as well as programming the PLC, robots and human-machine interfaces (HMIs).
“After an extensive debug period, the customer began to run production at RND’s facility to put the machine through a rigorous testing phase,” says Dotson. “Only after the machine had proven to be reliable was it disassembled and moved to the customer’s facility. Its modular design attributed to the...fact that the period of downtime, from the day of disassembly to the day it was producing parts on the customer’s factory floor, was only four days.”
The entire procurement process, from concept to production, took approximately one year.
The system consists of 16 stations linked by a pallet-transfer conveyor from Bosch Rexroth Corp. It includes three SCARA robots and one six-axis robot from EPSON Robots, as well as eight vibratory feeder bowls, six O-ring feeders, two vision inspection cameras, and two touch-screen HMIs.
At the first station, a four-axis SCARA robot unloads an unprocessed valve body from a pallet and inserts into a puck. At the next station, the body is dosed internally with light oil.
At the third station, a SCARA robot loads one of three inserts into the body. One particular insert needs to be aligned with a square recess in the body.
Then, two backup rings and two O-rings are loaded onto the outside of the body, and one of four possible springs is inserted into the body. To ensure that the correct spring has been inserted, a servo-driven load cell measures the spring rate of the part.
At the next station, a six-axis robot picks a sleeve from a feeder bowl, inserts a locking ring onto the sleeve, and inserts it into the body. A backup ring and O-ring are also inserted onto the sleeve.
If required, a SCARA robot loads a hex nut into a servo-driven rotating fixture, then holds the body over the nut. The servo spins the nut onto the body, tightening it to the specified torque.
Finally, the first SCARA robot unloads the completed body and places it into a vision inspection station. As the valve rotates 360 degrees, the vision system checks for the location and presence of all of the backup rings and O-rings.
For more information, call 941-870-5400 or visit www.rndautomation.com.
Editor’s note: Whether you’re a systems integrator or the in-house automation team of an OEM, if you’ve designed a system that you’re particularly proud of, tell us about it. Send an e-mail to John Sprovieri, editor of ASSEMBLY, at firstname.lastname@example.org, or call 630-694-4012.