Mold for forming composite-material structures

In a mold for forming a workpiece of a composite material between upper and lower parts of a press, which are relatively movable vertically toward and away from each other, said mold having die members placed between said upper and lower parts and being horizontally slidable, vertically movable wedge means for forcing said die members toward each other due to a wedge action so as to form a part of said workpiece between said die members and a pressing plate extending horizontally in vertically adjoining relation to said die members for vertically pressing a part of said workpiece when said upper and lower parts of the press are moved toward each other, the improvement in the mold comprising:

• a first layer covering a surface of each of said die members where said workpiece is in contact therewith;
• and
• a second layer covering a surface of said pressing plate where said workpiece is in contact therewith;
• each of said first layer and said second layer being made of a material having a thermal expansion coefficient substantially equal to that of said workpiece so as to precisely produce a product from said workpiece by uniformly pressing all surfaces of said workpiece without generating internal strain due to different thermal expansion coefficients between said workpiece and said die members and pressing plate.