Sumitomo Plastics Machinery of America LLC has introduced its SED all-electric injection press — a small-tonnage press that uses four direct-drive servomotors.
The machine comes in clamping forces of 33, 55, 83, 110, 143 and 198 tons.
Instead of the traditional belt system, the SED connects the ball screws to the motor with a direct linkage. Sumitomo already has offered direct drive on under-200-ton models of its SES all-electrics, but they use two direct-drive motors to power the injection unit.
Although the direct-drive concept is not new for Sumitomo, the SED takes it a step further — boasting four direct-drive motors, two each on the injection and clamping end. Direct-drive motors run plasticizing, injection, clamping and part ejection.
All the alternating-current servomotors are manufactured by the company's Japanese parent, Sumitomo Heavy Industries Ltd.
By not using belts, Sumitomo claims the motors offer superior mechanical efficiency, repeatability and durability, and avoid issues of belt dust, wear and adjustment.
The SED's synchronous direct-drive motor resulted from extensive research and development, according to Jerry Boggs, executive vice president of Sumitomo Plastics Machinery in Norcross, Ga. The result, he said, is a “lighter, more compact, low-inertia design with the best mechanical configuration for each motion. The result is a low-inertia system that draws power only as it is needed, is easier and faster to stop and start, and is exceptionally precise.”
Unlike induction-type electric motors, synchronous motors do not continue to draw power to maintain position, giving them an energy-efficiency edge over some other all-electric injection molding machines, according to Sumitomo.
Sumitomo also designed the new motors to accept a broader range of incoming power without requiring a transformer.
SED presses are fast, boasting injection speeds up to 500 millimeters per second. Other benefits include higher injection pressure, because the direct drive boosts torque, and a wider selection of injection units. On the clamp end, clamp open-and-close speed has been increased 50 percent, to 1,200mm per second. Ejector speed also has been increased.
Also new is the center press platen toggle-clamp design. Toggle posts are aligned so force is distributed into the center of the platen, instead of at the corners. The extended horizontal spacing between tie bars makes it easier to install larger molds.
Sumitomo offers the SK screw tip on its SED machines. The SK eliminates back flow during screw pullback and precisely controls shot density.
A V-III machine controller has a 12.1-inch color flat display with touch-screen capability.
Tel. (770) 447-5430, fax (770) 441-9168, e-mail [email protected]