Patent Publication Number: US-2006019810-A1

Title: Machine with conveyor belts for cardboard boxes provided with a belt stop device in absence of boxes

Description:
The present invention concerns a machine with conveyor belts for cardboard boxes provided with a device for the stop of the belts in the absence of boxes.  
      There are known machines for closing and sealing cardboard boxes, which comprise conveyor belts for the movement of the boxes along a bearing surface.  
      The belts for moving the boxes are usually two for each machine and they are moved, in continuous, by an appropriate ratio-motor unit.  
      Equally generally, the conveyor belts are always in operation, also in the moments in which there is no passage of boxes on the bearing surface.  
      This determines problems with wear of the components in motion and with safety of the utilisation of the machine against possible work accidents.  
      Object of the present invention is now to provide a machine of the aforesaid type with a device capable to stop the movement of the conveyor belts in the absence of boxes.  
      According to the invention such object is attained by a machine with conveyor belts for cardboard boxes, characterised in that it is provided with a device for the time control of the movement of the belts which, in the absence of boxes, automatically stops the movement of the belts after a pre-set time.  
      In this way the wear of the various components in motion is reduced and the degree of safety of the machine is increased. 
    
    
      The characteristics and the advantages of the present invention will become evident from the following detailed description of an embodiment thereof which is illustrated as a non-limiting example in the encolsed drawings, in which:  
       FIG. 1  shows a longitudinal section of a machine with conveyor belts for cardboard boxes made according to the present invention;  
       FIG. 2  shows a cross-section of the same machine according to the line II-II of  FIG. 1 ;  
       FIG. 3  shows top plan view of the aforesaid machine;  
       FIG. 4  shows a simplified block diagram of the device for the control of the movement and the stop of the belts. 
    
    
      The machine shown in the drawings comprises a frame  1  which supports a succession of idle rollers  31  which form a bearing surface for cardboard boxes  18 . In addition the frame  1  supports, by means of a coupling support  2 , a motor unit  3 .  
      The motor unit  3  comprises a ratio-motor  4  which controls a reduction shaft  5  on which a driving pinion  6  is fastened which moves a chain  7  tightened between said driving pinion  6  and a second pinion  8  supported by a bearing  10  and fastened on a splined transversal shaft  9  in median position between the two sides of the frame  1  ( FIG. 2 ).  
      Ball bearings  11  are bound to the frame  1  and support the transversal splined shaft  9 , onto which two transmission units  12  are engaged in sliding way comprising a horizontal conical pinion  13  and a vertical conical pinion  14  which allow the transmission of the rotary motion of the transversal shaft  9  to vertical shafts  15 , which by means of pulleys  16  fastened to them move belts  17  which move the boxes  18  on the bearing surface defined by the idle rollers  31 .  
      A device  32  for the movement and stop of the belts  17  is provided, whose block diagram is shown in  FIG. 4  and comprises a photoelectric cell  19  located at the entrance of the machine ( FIGS. 1 and 3 ) in order to detect the arrival of a box. The photoelectric cell  19  controls a remote control switch  20 , which controls in turn the power supply of the ratio-motor unit  4 .  
      When a box  18  interrupts the photoelectric cell  19 , the latter signals the passage of the box to the remote control switch  20 , which then controls the power supply of the ratio-motor unit  4 , which puts into motion the reduction shaft  5  which, in virtue of the transmission comprising the pinions  6  and  8  and the chain  7 , makes the transversal splined shaft  9  to rotate.  
      The transmission units  12  allow to transmit the rotary motion from the transversal shaft  9  to the vertical shafts  15  thanks to the gearing between the horizontal conical pinion  13  and the vertical conical pinion  14 .  
      The pulleys  16  fastened on the vertical shafts  15  transmit the motion to the vertical belts  17  which move with perfect synchrony, thus guaranteeing to the box  18  an effective and risk-free movement.  
      Once completely transited, the box  18  lets the photoelectric cell  19  free, which signals the event to a timer  21  ( FIG. 4 ), which starts the counting of a pre-set time from this moment.  
      Once said time has elapsed the remote control switch  20  is controlled to remove the power supply to the ratio-motor unit  4  and consequently the conveyor belts  17  stop.  
      As the next box approaches the cycle starts again as described above.