Apparatus for immobilizing a frame structure in its free state to establish a net datum position thereof

An apparatus for finding and immobilizing a chassis frame in its free state, despite within-tolerance variations in size or location of said chassis frame, so as to establish a net datum position of said chassis frame to enable net datum features to be fabricated net to a fixture and in design-intent position on said chassis frame, said apparatus comprising:

• a pair of opposed hydraulic units, each hydraulic unit of said pair of opposed hydraulic units being disposed on opposite sides of a portion of said chassis frame such that said portion of said chassis frame is between said pair of opposed hydraulic units, each hydraulic unit of said pair of opposed hydraulic units comprising:
• a plunger mounted displaceably therein and terminating in a pad, said plunger being normally biased toward a retracted position clear of said chassis frame;
• means for advancing said plunger from said retracted position to an advanced position, such that said pad contacts said chassis frame without measurably displacing said chassis frame;
• and
• means for locking said pad in said advanced position, so as to immobilize said chassis frame in its free state between said pair of opposed hydraulic units.

An apparatus for finding and immobilizing a chassis frame in its free state, despite tolerance variations in size or location of said chassis frame, so as to establish a net datum position of said chassis frame to enable net datum features to be fabricated net to a fixture and in design-intent position on said chassis frame, said apparatus comprising:

• a pair of fixed platens comprising one platen and an opposite platen mounted opposite said one platen, said opposite being spaced a predetermined distance apart from and substantially parallel to said one platen;
• a plurality of guide bars extending between said pair of fixed platens;
• a pair of displaceable pads mounted about said plurality of guide bars between said pair of fixed platens, said pair of displaceable pads comprising one pad and an opposite pad mounted opposite said one pad, said opposite pad being mounted about said plurality of guide bars a spaced predetermined distance apart from and substantially parallel to said one pad, said pair of displaceable pads being displaceable from a retracted position distal from said chassis frame to an advanced position in contact with said chassis frame;
• means for displacing said pair of displaceable pads, said displacing means being positioned between said pair of fixed platens, whereby said means for displacing displaces said pair of displaceable pads between said retracted position and said advanced position into contact with opposite reference surfaces on said chassis frame without measurably deforming said chassis frame so as to find said chassis frame in its free state;
• and
• means for locking said pair of displaceable pads, said locking means being positioned between said pair of fixed platens, whereby said means for locking locks said pair of displaceable pads in said advanced position so as to immobilize said chassis frame in said free state.