| 摘要 |
<p>Apparatus is disclosed for producing discrete packaging elements which can be individually varied in length so that they can be used for packaging articles such as cuts of meat which vary in length. The apparatus comprises drive rolls (22, 26) for feeding plastics packaging material (14) through a cut off device (24). Where the material is in the form of a flat tube, the apparatus may also comprise a heat sealing device (50, 52) to form the tube into a bag. A proximity sensor (56) is provided adjacent the cut off device and immobilises the drive rolls when it detects the presence of a leading portion of the material. This leading portion is cut off to form a packaging element. In one mode of operation the sensor actuates a switch (S1) when the element is removed, and causes the drive rolls to immediately feed another leading portion of the material. In another mode of operation, a second switch (S2) must be closed to operate the drive rolls. This second switch may be closed by a human operator or by a remote machine which electronically measures the length of each article to be packaged. Hand operated electronic controls are provided to set the length of each element before it is produced. The controls vary the number of revolutions of the drive rolls, the rotational speed thereof or the period of rotation thereof. These controls can be adjusted to set the length of a following element while a first element is being produced.</p> |
