We have developed electrically driven injection molding machines for production of large and thin light-guiding plates; “emP Series”. The “emP Series” machines can injection-mold large light-guiding plates in the size of 32″ – 52″.

In order to produce high-quality light guiding plates, we have equipped this highly reliable molding system with U-MHI’s latest comprehensive technologies, including a high precision thickness control by means of 2-platen clamping mechanism and 4-axis parallel injection compression control, F screw for exceptionally effective prevention of yellowing and silver streaks, specification to prevent contamination with selected cylinder material and control of sudden acceleration, deceleration and stop with DD servo motor-driven injection equipment, among others.

Characteristics of light-guiding plate and related technologies of U-MHI

Light-guiding plate size and applicable model

Light-guiding plate size (inch) 32 37 40 42 46 52
Light-guiding plate thickness (mm) 2.0 ~ 2.5
Applicable model 900emP-100 (○)
1100emP-160 (○)
Double cavity mold
(○)

High response, high-speed electrically driven injection equipment

DD (Direct Drive) servo motor

A pair of powerful DD servo motors (or 4 motors for screw diameter of f120 mm or larger), which we have developed originally, is employed on the injection system. These motors are characterized with an acceleration response of injection speed equivalent to that of the accumulator hydraulic servo specification, and their sudden acceleration/deceleration and feedback controls can stop and hold the screws at any desired positions, preventing burrs or shrinkage on products.

4-axis parallel injection compression control

High precision light-guiding plate thickness control

The 4-axis parallel injection compression control enables to homogenize the thickness of and reduce distortions like warping on molded thin light-guiding plates, by detecting the mold opening amount directly with the mold position sensors installed at four corners of mold and controlling four tie bars with the feedback control, coupled with our original feedforward compensation, of high-response hydraulic servo valves.

2-platen 4-axis parallel injection compression molding

Deviation of thickness on prototype PMMA light-guiding plate (equivalent to 40″)

Resin, mold and molding conditions e.g. can change the Deviation of thickness.

Space saving 2-platen clamping mechanism

Space saving

Thanks to our original 2-platen clamping mechanism, the floor space of the model 900emP-100/clamping force 1,050 tons (or 900 tons in the compression force) has been reduced to the level of 850 tons injection molding machine with the toggle type clamping mechanism (based on a comparison by U-MHI).