Abstract: There is provided RE-Ba-Cu-O oxide bulk superconductors in which considerably high critical current density is obtained at relatively high temperature. In the present RE-Ba-Cu-O bulk superconductors, RE is a combination of two or more elements selected from La, Nd, Sm, Eu and Gd, at least one of them being La, Nd and Sm and the remainder being Eu or Gd, in which a parent phase thereof comprises a RE.sub.1+x Ba.sub.2-x Cu.sub.3 O.sub.y crystal wherein -0.1<x<0.2 and 6.7<y<7.1, and 5 to 50% by volume of a RE.sub.2 Ba.sub.2 CuO.sub.5 fine dispersed phase having partide size of 0.01 to 0.5 .mu.m. Preferably, a total amount of Eu and Gd in the RE site is 40% by weight or less, while a slight amount of Pt may be added. As a result, the critical current density at liquid nitrogen temperature can be improved to 10,000 A/cm.sup.2 or more under a condition where a magnetic field of 3T is impressed parallel to c axis of the crystal.

Abstract: An injection molding machine employing a mold for molding, e.g., disk-shaped recording medium carriers. A mold-mounting plate has a front surface allowing the mold to be the mounted thereon. A gate-cutting punch is slidably inserted in a hole extending through the plate and opening in the front and rear surfaces of the plate. A bore extends longitudinally in the center of the punch, and an ejector pin is slidably inserted in the bore. A gate-cutting drive cylinder is mounted on the rear surface of the mold-mounting plate, and has a piston capable of abutting against the rear end of the gate-cutting punch. The piston is formed with a stepped bore having a large-diameter front portion and a small-diameter rear portion which are aligned on the same axial line. An ejector rod extends through the stepped bore, and has a large-diameter portion slidable within the large-diameter portion of the stepped bore, the front end of the ejector rod being capable of abutting against the rear end of the ejector pin.