Kneading apparatus with rotary shafts having stirring members

A kneading apparatus comprising:

• a first rotary shaft having a plurality of first stirring members provided on an external periphery thereof so as to be arranged helically at a predetermined helical pitch and at predetermined angular pitch intervals;
• and
• a second rotary shaft having a plurality of second stirring members provided on an external periphery thereof so as to be arranged helically with an inverse helix from that of the first stirring members at a predetermined helical pitch and at predetermined angular pitch intervals, the first and second rotary shafts being mounted parallel to one another to undergo rotation in opposite directions at unequal speeds to one another for kneading an object with the first and second stirring members;
• wherein a helical pitch ratio of the first and second stirring members is the inverse of a rotational speed ratio of the first and second rotary shafts, and an angular pitch ratio of the first and second stirring members is the same as the rotational speed ratio of the first and second rotary shafts;
• wherein the first and second stirring members are arranged so that the surfaces of the first and second stirring members assume a normal phase to advance the kneaded object in a feed direction, a reverse phase symmetrical to the normal phase relative to a center axis of each of the first and second shafts rotary shafts, or a flat phase oriented along the axial direction of the first and second rotary shafts, and the first and second stirring members that are positioned equidistant from the ends thereof as viewed in the axial direction of the first and second rotary shafts face to each other with the surfaces thereof assuming the same phase;
• wherein the first and second stirring members are arranged so that the normal phases, flat phases and reverse phases cyclically repeat in a predetermined sequence as seen in the axial direction of the first and second rotary shafts, the predetermined sequence being normal, flat, reverse;
• and
• wherein when the first and second rotary shafts rotate in opposite directions at unequal speeds, the kneaded object is advanced in a feed direction by surfaces of the first and second stirring members facing each other and assuming the normal phase, passes through the first and second stirring members facing each other assuming the flat phase, and is pushed back in a direction opposite to the feed direction by surfaces of the first and second stirring members facing each other and assuming the reverse phase.