Automatic kneading apparatus and fallen material returning apparatus

A sheet-testing apparatus including kneading rolls, a frame feeder, sheet applicator, foreign material detector, a frame with a light transparent window and a cutter for cutting a sheet. A sheet-testing sample-making apparatus has a cluster of kneading rolls, frame feeder, and sheet applicator. A sheet thickness detection apparatus outputs an electric signal to a memory. A kneading apparatus has a pair of heating rolls separated by a gap. The directions and speeds of rotations of the rolls are adjustable. A sensor detects the gap and a bank sensor detects the condition of a bank in the gap. The distance between the rolls, their temperatures, rotations, and speeds are automatically controlled. A pair of blades peel a sheet from the sheet-winding roll. Material dropped through the gap between the heating rolls is returned to a point above the gap. A cutting device has a length of wire sprung onto a rolled sheet to sever the sheet. A heating roll cleaning device brings cleaning rolls into sliding engagement with the heating rolls. A heating roll cleaning device feeds an elongated cloth-like cleaning member for cleaning heating rolls.