Automatic abrasive sand delivery machine especially for water-jet cutting machines

Abstract

An automatic loader of abrasive sand into a storage and supply tank (T) of a machine tool that uses the abrasive sand, and in particular of a cutting machine, includes a loading chamber ( 1 ) for loading the abrasive sand arranged above the supply opening of the tank (T) and having a suction inlet, connected through an air suction pipe ( 6 ) to a vacuum pump ( 2 ), and a sand inlet, in a lower position, connected through a sand suction pipe ( 7 ) to a supply container (S) for abrasive sand. A filter (F) is arranged inside the loading chamber ( 1 ), between the suction inlet and the sand inlet, and the loading chamber ( 1 ) is closed below by a butterfly valve ( 9 ) provided with spring element apt to retain the valve in the closed position when there is no sand inside the loading chamber ( 1 ).

1 ) Automatic loader of abrasive sand into a storage and supply tank (T) of a machine tool using said abrasive sand, and in particular of a cutting machine, characterised in that it comprises a loading chamber ( 1 ) of the abrasive sand arranged above the supply opening of said tank (T) and having a suction inlet, connected through an air suction pipe ( 6 ) to a vacuum pump ( 2 ), and a sand inlet, in a lower position, connected through a sand suction pipe ( 7 ) to a container (S) for the supply of abrasive sand, a filter (F) being arranged inside the loading chamber ( 1 ) between said suction inlet and said sand inlet, and in that said loading chamber ( 1 ) is closed off at the bottom by a butterfly valve ( 9 ) provided with spring means apt to retain said valve in the closed position when there is no sand inside said loading chamber ( 1 ). 
     
     
         2 ) Automatic loader of abrasive sand as claimed in  claim 1 , wherein the operation of said vacuum pump ( 2 ) is controlled by a control unit ( 3 ) which actuates said pump for a predetermined adjustable number of subsequent work cycles, the duration of each work cycle being predefined so that the activation of the vacuum pump ( 2 ) for an entire work cycle causes just the partial filling of said loading chamber ( 1 ). 
     
     
         3 ) Automatic loader of abrasive sand as in  claim 2 , wherein said butterfly valve ( 9 ) further comprises a micro-switch ( 10 ) connected to said control unit ( 3 ) apt to indicate whether said butterfly valve is open or closed, and wherein the operation of the pump ( 2 ) is switched off when said butterfly valve is in the open position. 
     
     
         4 ) Automatic loader of abrasive sand as in  claim 1 , wherein said supply container consists of a non-rigid bulk bag (S) full of abrasive sand hooked, by integral ties ( 5 ) positioned at its top, to corresponding hooks ( 4 ′) formed in the upper part of a sturdy, metal support frame ( 4 ). 
     
     
         5 ) Automatic loader of abrasive sand as in  claim 4 , wherein said sand suction pipe ( 7 ), at the supply container (S) side, is provided with an end intake nozzle ( 8 ), consisting of a double-walled metal pipe provided with a plurality of inlet slots formed in its side walls. 
     
     
         6 ) Automatic loader of sand as in  claim 5 , wherein the inner wall of the intake nozzle ( 8 ) is connected to the sand suction pipe ( 7 ), while the outer wall of the intake nozzle ( 8 ) causes the formation of a protection gap to prevent the intake nozzle from becoming blocked by the walls of the bulk bag (S). 
     
     
         7 ) Automatic loader of sand as in  claim 1 , wherein said air suction pipe ( 6 ) and sand suction pipe ( 7 ) are flexible pipes made of abrasion-resistant, plastic material, reinforced with metallic materials in order to prevent them from being crushed. 
     
     
         8 ) Automatic loader of sand as in  claim 1 , wherein said number of work cycles pre-set in the control unit is a finite number calculated in proportion to the size of the storage tank (T) and/or to the anticipated consumption of abrasive in respect of one production batch. 
     
     
         9 ) Automatic loader of sand as in  claim 1 , wherein said number of work cycles pre-set in the control unit is an infinite number and the operation of the vacuum pump ( 2 ) is interrupted only when the micro-switch ( 10 ) indicates that the butterfly valve ( 9 ) is open, i.e. when the abrasive sand of a work cycle leaving the loading chamber ( 1 ) is fully housed in the underlying storage tank (T).