Phonograph record pressing die assembly

Claim 1

For use in a phonograph record pressing die having upper and lower bases, the combination comprising a. upper and lower die frames, the upper die frame attachable to the upper base, and the lower die frame attachable to the lower die base, and b. upper and lower die faces, the upper die face attached to the upper frame, and the lower die face attached to the lower frame, the upper die face directly overlying the lower die face to press a phonograph record therebetween, c. there being a first set of fluid passing grooves formed in at least one of the upper frame and upper face and exposed to the other thereof, and another set of heat transfer fluid grooves formed in at least one of the lower frame and lower face and exposed to the other thereof, d. the grooves of each set being circular, coaxial and concentric, adjacent concentric grooves of each set being connected only by generally radial passages at multiple locations mutually relatively spaced about the groove axis, there being at least two pairs of said radial escape passages from each circular groove into the next radially outward circular groove, said two pairs being angularly offset about said axis, the pairs of escape passages from each said groove also being angularly offset from the pairs of escape passages from said next radially outward circular groove.