Sample feed auger structure
This is a division of application Ser. No. 260,985, filed June 8, 1972, now U.S. Pat. No. 3,808,881. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to sample feed structure and refers more particularly to a feed auger including a tapered, helical, flexible fin thereon. 
     2. Description of the Prior Art 
     In the past, feed augers have generally included rigid, helical fins which have been untapered over their entire radius. Wherein the feed augers of the past have been in conjunction with the rigid troughs, they have been damaged by large, hard articles placed in the trough. Further, feed augers of the past have not generally been contructed of a plastic sleeve with a flexible fin thereon molded over a rigid cylindrical member having spaced apart, annular, external recesses therein for rotation therewith without relative axial movement therebetween. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, there is provided sample feed structure including a feed auger comprising a rigid, hollow metal member having annular, exterior recesses therein, a urethane plastic sleeve molded on the hollow cylindrical member whereby the sleeve is prevented from relative axial movement with respect to the rigid cylinder and is secured to the rigid cylinder for rotation therewith, which sleeve includes a flexible, helical fin integral therewith which is tapered toward the outer periphery of the fin in conjunction with a rigid trough extending over substantially 180° of the feed auger structure and in closely spaced relation thereto. Means for rotating the feed auger are provided. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partly broken away, longitudinal elevation view of the sample feed structure of the invention, showing the trough in section in conjunction with the feed auger. 
     FIG. 2 is a cross section of the sample feed structure illustrated in FIG. 1, taken substantially on the line 2--2 in FIG. 1. 
    
    
     The sample feeder 18 includes a feed auger 40, best shown in FIG. 1, which is rotatably supported in a feed trough 42. 
     The feed auger 40, as shown best in FIG. 1, includes a metal cylinder 58, adapted to be rotated by conventional means such as a gear (not shown) secured to one end thereof. A plastic sleeve 60 with integral helical auger fins 62 thereon is molded on the cylinder 58. The fins are flexible urethane and as shown are tapered toward the outer periphery thereof. The annular recesses 64 in the cylinder 58 lock the plastic sleeve 60 onto the cylinder 58 against axial movement with respect thereto. 
     In operation, material such as foundry sand is moved through the trough 42 on rotation of the feed auger 40, and should hard, foreign objects such as nails, bolts or the like be fed into the sample feeder 18, they will be passed through the trough 42 without damage to the feed auger 40 or trough 42 due to deformation of the outer periphery of the fins 62 in contact with the hard objects. Thus, no shutdown time is required with the sample feeder 18 due to broken shear pins or actuation of overload relays due to hard objects jammed between the feed auger and trough. 
     While one embodiment of the present invention has been considered in detail herein, it will be understood that other embodiments and modifications thereof are contemplated by the inventor. It is, therefore, intended to include all embodiments and modifications as are defined by the appended claims within the scope of the invention.