| 摘要 |
<p>The internal circuit pulling vacuum on the molding shell (5a) has two parallel longitudinal channels either side of the molding surfaces. These are connected to openings (7) from the molding surfaces. The channels (18) reach terminal recesses (18a) at one end. At the other they continue transversely as grooves (19) over the end face (11). Connection to the source of vacuum is made via grooves (14) at the rear of the mold shell. Preferred Features: The longitudinal channels (18) connect to semicircular grooves around the mold surfaces (6) made in the end faces of the shell. A transverse groove makes connection. Each of the molding surfaces of a molding pair has a similar system of channels and grooves, making connection with the source of vacuum. In one variation only one of the shells forming a pair has the longitudinal, semicircular and transverse passages.</p> |
