Combination weighing apparatus with conveying unit including trough and spiral member

A combination weighing apparatus comprising:

• a dispersion unit configured and arranged to radially disperse product material dropped in from above;
• a plurality of conveying units arranged around a periphery of the dispersion unit;
• and
• a plurality of weighing units arranged around a periphery of the conveying units,
• each of the conveying units including a trough having an inside end positioned below the dispersion unit and an outside end positioned above the weighing unit, at least one of the troughs having a cross-sectional diameter that gradually increases generally from the inside end to the outside end so that the one of the troughs and an adjacent one of the troughs are kept in contact with each other substantially all the way from the inside ends to the outside ends, and
• at least one of the conveying units having a spiral member disposed over a bottom surface of the trough, the spiral member being configured and arranged to convey the product material supplied from the dispersion unit toward the outside end of the trough by being rotatably driven,
• the spiral member having a shape in which a spiral diameter in the vicinity of the outside end is greater than a spiral diameter in the vicinity of the inside end.