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Boy injection molding machines: faster, more precise, more cost effective  #10 (80), 2009

BOYDuring the crisis production cost effectiveness is more actual than ever. That is why the launch of new super cost effective injection molding machines series from Dr.Boy headquartered in Neustadt, Western Germany can be considered as very well-timed.

E series machines allow to reduce the consumption of expensive electrical energy by 50%. This savings is enabled by a new concept servo-motor pump and screw drive.
Dr. Boy is an exclusive European injection molding machine manufacturer applying this technology. The BOY 55 E and BOY 90 E injection moulding machines (clamping force 55 tons and 90 tons respectively) are equipped with this technology. Gear pump is controlled via special servo drive; volume and pressure are controlled by adjustment of drive speed – in practice this means the drive switches off and no longer requires energy when no oil pressure required.
The speed of the motor is only as high as the respective cycle phase requires. At all times, the motor is performing in an optimum, energy-efficient way. At the pressure containment stage the speed is minimal and the energy is consumed only for pressure control. It proves the fact that energy consumption and hydraulic energy losses are reduced. The drive restart is accomplished without delay.
The patented servo drive is controlled by servo converter acquiring pressure and oil volume data from control system. Real hydraulic pressure value is transmitted to servo converter. In order to perform speed and pressure control the drive has the function of rotary acceleration – more than 3500 radians/s2.
Servo drive synchronization is performed by means of special magnets allowing to double the torque without increasing drive current. Due to such design drive heating was minimized so it requires less energy for cooling improving overall efficiency of the machine. Oil temperature control is the only function that is maintained. Thus every operating mode of the machine features ultimate cost effectiveness.
The kinetic energy released during drive deceleration is partially stored in converter circuit and reused for further operation. Thanks to synergy of high drive performance coefficient and special converter control as well as adaptive drive speed the pump always operate optimally. Due to servo drive energy efficiency matches the values of electro-mechanical machines but without the inherent disadvantages such as wear, high investment and spare parts costs, and high-connected load.
Compared to injection molding machines with electronically controlled variable displacement pumps, the drive energy is reduced by more than 50 % so the energy requirement is even lower than that of electro-mechanical machines.
Also significant improvements are achieved in noise level, precision and dynamics. The noise level is reduced as "drive/pump" block is completely noiseless at inactive position between stage finish and cooling. Improved precision and dynamics are achieved by means of constant acceleration and reduction of drive-pump unit capacity. Response time after speed assignment is 70 ms (for accelerating from still position). Pressure heightening from 0 to 180 bars takes less than 100 ms and reverse operation takes less than 80 ms.
A pilot production run proved machines reliability: with the average part weight of 51.9 grams the maximum deviation in weight was only ±0.06 grams or 0.115%.
Traditionally every Boy injection molding machine feature high precision and ultra-compact size and can be easily equipped with automation mediums. Also the determinative factor for choosing Boy machines is ultimately low cost of machine hour.

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