Apparatus for shaping a packaging material and control device for advancing and withdrawing an elastic web material in this apparatus

摘要

An apparatus for giving a tubular configuration to a sheet of packaging material is composed of an elastic material 10 in the form of an elongate web and which is highly flexible and secured at one end, this material extending obliquely upwards, then undergoing a turn in order to form a loop; as well as an actuating mechanism 32, 36a-36c connected mechanically to the other end of the said material, this mechanism having the effect of advancing or withdrawing the said material in order to cause the contraction or the extension of the loop formed by this web material 10. <IMAGE>