Abstract: A method and apparatus for mold protection of motor-driven clamping unit is provided. The method and apparatus is based on high response characteristics of the motor and a new control method. A continuously variable restrictive motor output scheme is used in conjunction with the mechanics characteristics of the toggle mechanism to maintain a substantially constant mold protective force at all positions. Further, the mold protective force can be adaptively adjusted with respect to different types of molds and motional conditions so that the mold can be adequately protected whenever abnormal condition occurs during mold closing action. The motor output will thus not unduly increased to a great level that would damage the mold, the machine, or even the operators. The drawbacks of the prior art are thus eliminated.

Abstract: An interchangeable injection screw for use in an injection molding machine is disclosed. It comprises: (a) an interchangeable feeding section, an interchangeable compression-and-melting section, an interchangeable metering-and-mixing section, and an interchangeable screw head, wherein the interchangeable feeding section, the interchangeable compression-and-melting section, the interchangeable metering-and-mixing section and the interchangeable screw head can severed from each other; (b) a splined shalt integrally formed with the interchangeable feeding section and extending in front thereof so as to sleevedly receive, in order from the feeding section, the compression-and-melting section and the interchangeable metering-and-mixing section; and (c) a screw means for affixing the interchangeable screw head to the splined shalt so as to form a complete injection screw.

Abstract: A screw rotating and advancing device for an injection molding machine, in which a movable pressure plate is provided with a servomotor to drive a ball screw in association with a ball nut provided at a rear fixing plate, so that the movable pressure plate homogeneously drives a screw shaft passing through a front fixing plate to perform the operations of injection, holding pressure, and measuring back-pressure; and accomplish a close-loop control of the pressure of molding material by using a force sensor. The other side of the movable pressure plate is provided with a servomotor to rotate the screw shaft, so that the rotational speed of the screw shaft can be precisely controlled. Furthermore, the present invention includes a pre-load system including at least two pre-loaded hydraulic cylinders, at least tow pistons and a communicating tube to balance the pressure difference between the prepressurized hydraulic cylinders.