An image reading apparatus includes an image reading unit for reading an image of a document at a reading position, a document feeding unit for discharging the document via the reading position, an abnormality detection unit for detecting a feeding abnormality, and a reading determination unit. The extruder die has a center post parallel to the flow path along with three cone-shaped receiving ports arranged in a cloverleaf pattern around the center post. An insert can be installed into one or more of the grooves. , and the resin layer is a layer which does not substantially deform when the layer is heated to 85\xb0 C. The movable rubber plate includes at least partially a corrugated part expanding generally a form of a corrugated panel by means of continuous depressions and protrusions. After closing of the entrance to the antechamber the position of the piston and the pressure in the antechamber are monitored, and the final position of the piston is determined by a calculation which takes account of at least one value of the measured pressure and of the position of the piston at which said pressure was measured.