System for feeding portions of material to an injection molding machine

Abstract

The present invention is a system for feeding portions of material to an injection molding machine including a feeding means that can be a screw feeder, an external container, a material hopper with inclined and parallel walls located inside the container, a load cell that is coupled to the material hopper and a controller. The system dispenses portions of material in a given time and for given duration. The system dispenses accurate weight portions. The system controls the portion weight by weighing a number of dispensed portions using loss-in-weight of the hopper, divides the weight to the number of portion and when it need, control the spin of the screw feeder motor.

What is claimed is:  
     
         1 . A system for feeding portions of material to an injection molding machine comprising: 
 i. a feeding means;    ii. a container, with a fill opening and an outlet, and said container is installed with said feeding means;    iii. a material hopper, with a fill opening and an outlet, and said material hopper is located inside said container;    iv. a load cell that is coupled to said material hopper, and    v. a controller operative for: 
 i. calculating the weight of fed material, using said load cell and loss-in-weight method, and  
 ii. controlling said feeding means.  
   
     
     
         2 . The system of  claim 1 , wherein said material hopper has a funnel shaped lower part and an upper part and wherein said upper part has same cross-section-area in each vertical level.  
     
     
         3 . The system of  claim 2 , wherein said upper part of said material hopper has inclined parallel-walls.  
     
     
         4 . The system of  claim 3 , wherein said controller is further operative for: 
 iii. Command said feeding means to dispense at least one portion of material from said material hopper, wherein each said portion is dispensed in a given time and for a given interval of time in order to dispense portions with a predetermined weight.    
     
     
         5 . The system of  claim 4 , wherein said controller is further operative for: 
 iv. calculates the weight of said portion by: 
   1 . dispensing a number of portions;  
   2 . calculating the weight of said number of portions; using loss-in-weight method, and  
   3 . dividing said weight of said number of portions to the number of said portions.  
   
     
     
         6 . The system of  claim 5 , wherein said feeding means is a screw feeder.  
     
     
         7 . The system of  claim 6 , wherein said controller is further operative for: 
 v. adjusting the weight of the further portion by increasing or decreasing the spin speed of said screw feeder, if said weight of said portion is differ said predetermined weight.    
     
     
         8 . The system of  claim 7 , wherein said outlet of said material hopper is shifted from said outlet of said container.  
     
     
         9 . The system of  claim 8 , wherein said outlet of said material hopper is elevated from said outlet of said container.  
     
     
         10 . A material hopper for accurate weighing comprising: 
 (a) a funnel shaped lower part with outlet, and    (b) a parallel walls upper part.    
     
     
         11 . The material hopper of  claim 10 , wherein said upper part is inclined.  
     
     
         12 . The material hopper of  claim 10 , wherein said upper part is a cylinder shaped.  
     
     
         13 . The material hopper of  claim 12 , wherein said upper part is inclined.  
     
     
         14 . A method of accurate weighing of a fed portion comprising: 
 i. storing the material in a material hopper that it upper part is an inclined cylinder or an inclined parallel walls;    ii. feeding a predetermined number of portions;    iii. calculating the weight of said number of portions, using loss-in-weight of said material hopper using a load cell, and    iv. calculating the weight of each portion of said number of portions by dividing said weight of said number of portions to the number of said number of portions.    
     
     
         15 . The method of  claim 14 , wherein said predetermined number of portions is calculated by dividing the sensitivity of said load cell to the estimated weight of said fed portion.