By Todd Bauernfeind and Russ Hubrich, Summit Machine
Summit Machine typically designs one-of-a-kind custom automation. We have one chance to create a successful robust machine and rarely have the opportunity to build that same machine again. This led our company to a design philosophy that reduces risk, costs and labor, and encompasses the entire project from estimating through mechanical design and naturally flowing to the controls design.
Typically, at the start of estimating a project, we research for standard equipment to perform the main process functions. Standard equipment varies from simple vibratory feeder bowls, pick-and-place units or sonic welders, to more advanced, auger-driven powder fillers or robotics. By using standard equipment, we leverage other companies' specialized expertise to reduce risk and cost. During the design phase, our controls engineers will determine the best way to integrate the standard equipment to allow ease of use and flexibility for the end users.
Perhaps the most important element of our design philosophy is flexibility. We consider flexibility in our choice of major components such as robotics, servo systems or control platforms. This choice is governed by the amount of flexibility that a specific component will allow during the debug stage.
The importance of this element was proven during a project to create a custom packager for packaging cutting tools 2 to 6 in. long with various diameters. The machine pushes the tools into paper envelopes with the shank end leading by pushing on the cutting ends. The two options for this motion were a simple pneumatic cylinder or a servo-controlled actuator. After reviewing the cycle rate and the lengths, we chose an Exlar servo-controlled actuator. This allowed the machine to push with a profile instead of a constant rate from a cylinder. The actuator would advance rapidly to the drill, slow down and make contact with the drill, then rapidly move forward the required distance and finally decelerate at gradual rate. This permitted a soft pickup of the drills, minimizing damage, and a controlled push into the envelope.
Flexibility also influences the estimating phase of a project. Summit built a machine to assemble three similar types of water filters. During estimate development, we worked with the customer to develop a concept for a flexible machine that could switch quickly between any of the three filters and add additional filters in the future. We decided to standardize on six-axis robots from Denso Robotics. The final machine used six of these robots to assemble the filters. We chose to integrate the six robots and each station's I/O using DeviceNet, which allowed the end customer the flexibility to add more stations by simply connecting any I/O to the DeviceNet with minimal wiring.
Typically, Summit standardizes on control and motion platforms from GE Fanuc or Rockwell Automation, but these platforms sometimes can't perform the necessary function or the initial design cost would make the project uncompetitive. Flexibility in control platforms allows Summit to build custom web-converting machines using a Synax 200 motion and PLC solution from Bosch Rexroth. The Synax 200 solution is a freely scalable control and drive solution for machines in the printing and rotary converting industry. This system offers a parameterized motion controller integrated with PLC logic. The motion controller offers electric gears, cams, tension control and register controllers simply by setting parameters in the motion control.
These projects became possible because we or our customers didn't have to bear the cost of low-level code development and testing.
Flexibility also allowed Summit to produce a machine for a customer to assemble foam pads. The customer had experience with programming CNC routers in G code and preferred a solution that allowed programming with this capability for future flexibility. A standard CNC controller from any of the larger suppliers would have made this project cost-prohibitive, so we selected a more-advanced PLC and motion solution from B&R Automation. This solution would let the customer program three axes of motion control using G code, and program other axes using any of the IEC 61131-3 PLC languages. Unfortunately, the end customer forced a process change, eliminating the grinding, during the build portion of the project. That forced us to redesign the machine. Since the PLC was already purchased and had the needed flexibility, the servos and controllers were recommissioned for the new design.
Russ Hubrich and Todd Bauernfeind co-wrote this article. Hubrich is engineering manager and Bauernfeind is president at Summit Machine (www.summitmachineinc.com) in Shoreview, Minn.
