| 摘要 |
A block is heated to moulding temp. A central guide core is made, whose cross-section is smaller than that of the final core. - The initial core is used for guiding the front end of a mandrel with corresponding cross-section. Spec., the mandrel has several sections of progressively larger dimensions, the final one corresponds to the required bore. Guide bore and final bore are thus produced in one operation with one tool.
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