Manufacturing method and apparatus for shell of universal-joint

A manufacturing apparatus for a tubular shell of a universal-joint for flexibly coupling a first rotary shaft to a second rotary shaft, said shell being adapted to be secured at a flange formed on one end thereof to said first rotary shaft and being provided at a suitable number of places inside thereof with grooves extending along the axis thereof for being engaged with engaging portions disposed on one end of said second rotary shaft which is to be inserted inside said shell from the other end thereof, said apparatus comprising:

• (1) a groove and preliminary flange forming apparatus comprising
• (a) a first die to be inserted inside a hollow cylindrical blank and having a plurality of axially elongated recesses formed on an external circumference thereof with an equal interangular distance and a plurality of non-recessed portions remained between each adjacent pair of said recesses, circumferential configuration of said first die being corresponding to internal configuration of said shell,
• (b) a second die consisting of a plural die blocks radially arranged to surround said first die, said die blocks being radially movable and defining a space corresponding to an external configuration of said shell at the most inwardly advanced position thereof,
• (c) a preliminary flange forming die of a funnel shape convergent from a fixed end to a free end thereof, which is axially movable, and
• (d) actuating means for simultaneously advancing said die blocks and said preliminary flange forming die to make the former urge a side wall of said blank to said first die and to simultaneously make the latter expand one end of said blank to a preliminary flange of funnel shape for making said blank into a semi-finished article;
• and
• (2) a flange forming apparatus comprising
• (a) restraining dies holding said semi-finished article in a restrained status under pressure from either side, external and internal, except at said preliminary flange thereof, and
• (b) a flange forming die having a flat surface axially pressing said preliminary flange for forming the same into a completed flange perpendicular to the axis of said shell.

A manufacturing apparatus for a tubular shell of a universal-joint for flexibly coupling a first rotary shaft to a second rotary shaft, said shell being adapted to be secured at a flange formed on one end thereof to said first rotary shfat and being provided at a suitable number of places inside thereof with grooves extending along the axis thereof for being engaged with engaging portions disposed on one end of said second rotary shaft which is to be inserted inside said shell from the other end thereof, said apparatus comprising:

• a first die to be inserted inside a hollow cylindrical blank and having a plurality of axially elongated recesses formed on an external circumference thereof with an equal interangular distance and a plurality of nonrecessed portions remained between each adjacent pair of said recesses, circumferential configuration of said first die being corresponding to internal configuration of said shell;
• a second die consisting of a plural die blocks radially arranged to surround said first die, said die blocks being radially movable and defining a space corresponding to an external configuration of said shell at the most inwardly advanced position thereof;
• a preliminary flange forming die of a funnel shape convergent from a fixed end to a free end thereof, which is axially movable;
• first actuating means for simultaneously advancing said die blocks and said preliminary flange forming die to make the former urge a side wall of said blank to said first die and to simultaneously make the latter expand one end of said blank to a preliminary flange of funnel shape for making said shell into a semi-finished article;
• a flange forming die having a flat surface to be axially urged to said preliminary flange and being axially movable, at least one of said preliminary flange forming die and said flange forming die being laterally movable;
• and
• second actuating means for axially retracting said preliminary flange forming die while holding said die blocks at said most inwardly advanced position for restraining said semi-finished article from either side, external and internal, in cooperation with said first die, laterally moving at least one of said preliminary flange forming die and said flange forming die, and axially advancing said flange forming die to form said preliminary flange into a completed flange perpendicular to the axis of said shell.