Canadian Plastics

AUTOMATION: Not just for molding anymore

Robots will soon take their place on profile extrusion lines in North America, says Ernie Preiato, Conair Extrusion Systems product manager. It's already being done in Europe, he says, and the use of ...

September 1, 2001   By Cindy Macdonald, associate editor



Robots will soon take their place on profile extrusion lines in North America, says Ernie Preiato, Conair Extrusion Systems product manager. It’s already being done in Europe, he says, and the use of a robot to off-load and palletize extruded profiles at a supplier demonstration this spring caught the eye of many attendees.

Conair has run demonstrations with a Fanuc M6i articulated-arm robot palletizing PVC fence profiles in conjection with a high speed extrusion line in the company’s Pittsburgh Technical Center.

As extrusion rates continue to increase “extruders will need to be able to handle these valuable parts efficiently,” says Preiato. “Considering the length and weight of some of these profiles, you might need to dedicate two workers to handling parts coming off the line. Under those circumstances, it doesn’t take long to justify the use of robots.”

The M6i robot used in the Conair demonstration line is a mid-sized unit with payload capacity to 13 lb. and up to 54 in. of reach. A vacuum gripper was used to pick a cut-off profile from a belt conveyor and place it on a pallet. The robot automatically indexes across the pallet until each layer of product is complete. For longer, heavier profiles, Conair can supply articulated-arm robots with larger payload capacity (to 441 lb.) and longer reach (up to 122 in.) through an Integrator Agreement with Fanuc Robotics.

Jim Healy, Conair automation product manager, says articulated-arm robots would likely be the best option for downstream extrusion applications because of their flexibility of movement due to the six-axis configuration.

Another innovative application of automation is being developed for the injection stretch blow molding field. A preform handling system under development at Ventax is expected to be less expensive and more simple than current systems. It uses a high-speed robot with vacuum-based, end-of-arm-tooling to remove the preforms and a pneumatic system to transport the preforms to a separate air cooling device. This system is not yet commercial, but a test device has returned very encouraging results. It showed that preforms would not suffer any damage due to the handling and cooling system.

The Centre de recherche industrielle du Quebec (CRIQ) has developed a unique tool that imitates the movement of a human wrist during trimming of blow-molded or roto-molded parts. It can be attached to an articulated-arm robot to follow the contours of a part, using a rotating knife for trimming.

“An advantage of our device is the simplification of programming for the robot and the positioning of the part,” explains Louis-Marie Boivin, automation counselor with CRIQ. “Our tool can accept positioning or dimensional variation of up to one inch. This is very useful because you don’t have to program such a precise trajectory.”

INJECTION MOLDING ROBOTS GET FASTER, STRONGER

Returning to the world of injection molding, Engel has redesigned its E-Series servo robots. The robots can interface with any brand of injection molding machine, and have 64-bit RISC controller. The E-Series offers up to six independently programmable servo-driven axes — three linear and three rotational — and the controller has the processing power to deliver simultaneous motion along all six servo axes.

The E-Series has a more compact design than its predecessors. The length of the linear arms has been reduced without compromising available stroke. Through the redesign, Engel has also been able to reduce the cost of the robots.

One of the E-Series models, the ERC-EA, uses asynchronous vector drive (AC motor) technology to achieve speed and precision close to servo performance at substantially less cost.

Fanuc Robotics now offers a dual arm configuration for its Toploader series, which allows manufacturers to increase throughput for multiple machine installations by adding a second robotic arm. The dual arms are independently controlled. When a manufacturer needs to do machine maintenance, one robot can be locked out while the other continues to operate.

Fanuc Robotics has also added new rail lengths to the Toploader line. A short 2.4 m version is designed specifically for use with injection molding machines, and comes with a platen bracket for direct mounting to the injection molding machine.

ACS Group’s Sterltech Automation has introduced a linear drive robot for mid-size injection molding machines with dramatically increased acceleration and velocity. The all-linear design incorporates high performance braking matched to the higher performance drives for precise positioning. Closer tolerances between all drive components also results in higher accuracy.

The units feature a modular traverse beam with dual rack and pinion wrist rotation for increased rigidity to handle higher inertias and ample payloads.

The compact design of the TE-45 top-entry robot from Husky Injection Molding Systems still provides a generous stroke, making the unit suitable for automating large injection molding machines. The robot has an in/out time of 1.6 seconds under full load of 45 kg, with repeatability of +/- 0.5 mm. Digital AC servo drives are used on the main axes.

The robot can be configured to place parts beside the machine or at the clamp end. On Husky machines, robot control is integrated with the operator interface.

The Eagle EL3S servo robot from Mark 2 Automation uses high-speed servo motors on all three axes, combined with a PC-based control system for maximum ease-of-use. The robots are suitable for horizontal injection molding machines from 50 to 1000 ton capacity.

All three axes also use wear-resistant, steel-reinforced polyurethane belt drive systems to minimize maintenance.

THE FINAL WORD: CONTROLLERS

STEC-460 is a new servo robot controller with CNC programming versatility from Star Automation. It is able to control up to eight servo axes, and has several features new to the STEC-400 Series controls: reject-on-start, sampling, Auto-Step and a production monitor with daily, weekly and monthly tracking.

Star’s flexible Pick-and-Place program, with a wide variety of user-selectable operational modes, is standard on the STEC-460. The modes can be used for functions such as posture at part release, fixed-half removal, sprue placement, and product confirmation. The user also has the ability to write an interrupt program before and after each servo movement.CPL


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