Patent ID: 7537044

Claim:
A method for die casting a base frame for supporting a resin shoe in a sliding contact guide for an endless, flexible, traveling, transmission medium, said base frame having a front surface for supporting engagement with a resin shoe, a back surface opposite from said front surface, said front and back surfaces both having elongated side edges, and said base frame having first and second side surfaces, the first side surface connecting a first side edge of the front surface with a first side edge of the back surface and the second side surface connecting a second side edge of the front surface with a second side edge of the back surface, the method comprising: forming an elongated die cavity having the same shape as that of said base frame, the die cavity having front and back internal surfaces on which said front and back surfaces of the base frame are formed respectively, elongated internal edges at which said elongated side edges of the front and back surfaces of the base frame are formed, and first and second cavity side surfaces against which said first and second side surfaces of the base frame are formed, each of said first and second cavity side surfaces extending from one of said elongated internal edges to another of said elongated internal edges, the elongated die cavity being formed from three separable die parts by bringing two of said die parts into mutual contact with each other by relative movement in a first direction transverse to the direction of elongation of the die cavity, thereby forming a first parting line at the location at which said two die parts contact each other, said first parting line extending along the full length of the elongated die cavity, and bringing a third die part into contacting relationship with both of said two die parts by movement of said third die part relative to said first and second die parts in a second direction transverse to said first direction and to the direction of elongation of the die cavity, said third die part contacting the first and second die parts along second and third parting lines that meet the first and second side surfaces of the die cavity, respectively at intermediate locations between said front and back internal surfaces, the parting lines being spaced from said elongated internal edges along substantially the entire length of the die cavity; and casting the base frame in said elongated cavity by pouring molten metal into said die cavity; said third die part having a continuous face against which the front surface of the base frame is formed, the intersections of said face with all cross-sectional planes which extend through the die cavity and to which the direction of elongation of the die cavity is perpendicular being substantially straight, thereby avoiding the formation of a draft on the front surface of the base frame.