39 of the folding plates 41 41 39 engage the necktie cut 75 and form in cooperation with the folding webs 26 26 39 one side 78 of a left and a right corner fold 79 79 39 also the folding members 51 51 39 do not yet clamp the necktie cut 75 so that also the formation of the corner folds 79 79 39 does not cause an additional stress in the necktie cut 75 finally also the folding members 51 51 39 in connection with the folding webs 26 26 39 engage the necktie cut 75 for forming the other side 80 of the corner folds 79 79 39 thus for producing the various folds in the necktie cut 75 and handling the material fullness it is required to run the individual folding operations on a definite plan so as to cause no additional stress in the necktie cut 75 this is achieved by a stepwise actuation of the individual folding elements as the workpieces 72 75 to be sewn are clamped area wise and in particular at the external zones after the workpiece clamp 2 has been completely closed according to the above description the control triggers to switch over the drive cylinder 17 so that the folding webs 26 26 39 are moved into their retracted positions.