Abstract: A concrete mold core assembly for casting catch basins and the like has outwardly facing form panels disposed to form a box with at least two corner members being located at diametrically opposite corners of the box between spaced adjoining edges of the panels and a lid overlies the ends of the form panels and corner members. Each corner member provides opposite side surfaces defining a tapered wedge that matingly inter-engages with the spaced adjoining edges of the form panels such that when the corner members are moved outwardly the core assembly is expanded into its casting condition and when moved inwardly the panels and members are stripped from the hardened concrete. The lid is coupled to the upper ends of the corner members to be raised to casting condition when the members are moved outwardly and lowered to be stripped from the hardened concrete when the members are moved inwardly.

Abstract: A concrete form unit for casting an inside corner structure has a pair of form panels disposed generally perpendicular to each other and an elongated corner member disposed between spaced adjoining edges of such panels with an actuator having relatively movable parts including a first part connected to the midsection of a yoke and a second part connected to the corner member. The ends of the yoke are guidingly connected to the form panels, respectively, and the adjoining edges of the form panels are guidingly coupled to opposite sides of the corner member by slidingly interengaging surfaces, these surfaces defining a tapered wedge where the corner member mates with the adjoining edges of the form panels.

Abstract: A form unit to cast the inside surfaces of a corner of a concrete structure has a pair of form panels disposed generally perpendicular to each other and an elongated corner member disposed between the adjoining edges of such panels with an actuator having relatively movable parts including a first part connected by parallelogram linkage to each of the form panels and a second part connected to the corner member so that when the actuator parts are moved together the form panels are butted against the outer edges of the corner member and when the actuator parts are moved apart the form panels are separated from the corner member. Holding means retains the corner member against displacement toward the panels while the form panels are being stripped from the hardened concrete and latch means holds the form panels against relative movement while the corner member is being stripped.

Abstract: For casting a concrete inside corner wall structure, the corner is defined by a corner member to extend lengthwise of the corner with the adjacent edges of a pair of form panels that are disposed generally perpendicular to each other being butted against the outer edges of the corner member and a control unit is interconnected with the form panels and the angle member to retain this relationship between the panels and angle member incident pouring and hardening of the concrete. The control unit has actuator means associated therewith operable to move the panel edges into abutment with the outer edges of the angle member prior to concrete pouring and to strip both the form panels and the angle member from the hardened concrete structure.