Method and device for producing plastic hollow bodies, and plastic hollow bodies produced therewith

Abstract

The invention relates to a method and a device for producing blow-molded plastic hollow bodies ( 60 ). The device is of enhanced design which avoids the shortcomings of traditional blow-molding technology. The extrusion die according to this invention is adjustable for different settings to produce different, partly overlapping wall thicknesses of the parison blank in order to compensate for the insufficiencies inherent in blow-molding and to obtain a finished blow-molded product with as consistent and uniform a wall thickness as possible, with an overlay, for instance in vertical wall areas, of evenly spaced longitudinal ribs ( 68 ). A technical concept is introduced whereby, as a novel process, the two conventional measures used to achieve a uniform wall thickness in the finished blow-molded hollow body are complemented by an additional, third step which makes it possible to produce containers whose hollow bodies ( 60 ) are provided with targeted, intentional and reproducible irregular wall thickness patterns.

1 - 16 . (Canceled)  
   
   
       17 . A large-volume industrial barrel assembly comprising: 
 a thermoplastic blow molded open-top hollow barrel body including:    a barrel bottom; and    a substantially cylindrical sidewall connected to the barrel bottom and terminating in an upper rim, the sidewall having an inner surface provided with a plurality of circumferentially spaced-apart, vertically oriented ribs extending substantially along a height of the sidewall, wherein the vertically oriented ribs define thicker wall regions spaced apart by thinner wall regions formed on the inner surface;    a clamping ring; and    a substantially circular cover lid configured to seal the open-top barrel body in conjunction with the clamping ring.    
   
   
       18 . The industrial barrel assembly according to  claim 17 , wherein the thicker wall regions and the thinner wall regions alternate around the inner surface in a uniformly increasing and decreasing wave pattern.  
   
   
       19 . The industrial barrel assembly according to  claim 18 , wherein the thicker wall regions are equally thick and the thinner wall regions are equally thin.  
   
   
       20 . The industrial barrel assembly according to  claim 17 , wherein the thinner wall regions between two thicker wall regions are at least about twice as wide as either thicker wall region.  
   
   
       21 . The industrial barrel assembly according to  claim 17 , wherein a ratio of a thickness of the thicker wall regions to a thickness of the thinner wall regions is between 1.1:1 to 1.5:1.  
   
   
       22 . The industrial barrel assembly according to  claim 17 , wherein the number of ribs formed on the inner surface is between 20-60.  
   
   
       23 . The industrial barrel assembly according to  claim 17 , further comprising a lateral fitting formed on the sidewall.  
   
   
       24 . The industrial barrel assembly according to  claim 17 , wherein each vertical rib is strip-like.  
   
   
       25 . The industrial barrel assembly according to  claim 17 , wherein: 
 the thicker wall regions are equally thick and the thinner wall regions are equally thin;    the thinner wall regions between two thicker wall regions are at least about twice as wide as either thicker wall region;    a ratio of a thickness of the thicker wall regions to a thickness of the thinner wall regions is between 1.1:1 to 1.5:1;    the number of ribs formed on the inner surface is between 20-60;    a lateral fitting is formed on the sidewall; and    each vertical rib is strip-like.    
   
   
       26 . A substantially rectangular canister comprising a thermoplastic blow molded rectangular body having: 
 a canister bottom;    first and second pairs of substantially parallel sidewalls joined together at rounded corner areas and connected to the canister bottom, the first pair of sidewalls being longer than the second pair, central portions of the first and second pairs of sidewalls each having an inner surface provided with a plurality of spaced-apart vertically oriented ribs defining thicker wall regions spaced apart by thinner wall regions: and    a canister top having an opening formed at one end thereof, adjacent one member of said second pair of sidewalls.    
   
   
       27 . The canister according to  claim 26 , wherein the vertical ribs are absent from the rounded corner areas.  
   
   
       28 . The canister according to  claim 26 , further comprising a handle member affixed to the canister top.  
   
   
       29 . A substantially rectangular canister comprising a thermoplastic blow molded rectangular body having: 
 a canister bottom;    first and second pairs of substantially parallel sidewalls joined together at rounded corner areas and connected to the canister bottom, the first pair of sidewalls being longer than the second pair, the rounded corner areas each having an inner surface provided with a plurality of spaced-apart vertically oriented ribs defining thicker wall regions spaced apart by thinner wall regions, the rounded corner areas further having an outer surface that is smooth in those regions opposite the vertically oriented ribs provided on the inner surface; and    a canister top having an opening formed at one end thereof, adjacent one member of said second pair of sidewalls.    
   
   
       30 . The canister according to  claim 29 , wherein the vertical ribs are absent from central regions of the first and second pairs of sidewalls.  
   
   
       31 . The canister according to  claim 29 , further comprising a handle member affixed to the canister top.  
   
   
       32 . A closed bung-type barrel comprising: 
 a thermoplastic blow molded hollow barrel body including:    a barrel bottom;    a substantially cylindrical sidewall connected to the barrel bottom, the sidewall comprising an inner surface provided with a plurality of circumferentially spaced-apart, vertically oriented ribs extending substantially along a height of the sidewall, wherein the vertically oriented ribs define thicker wall regions spaced apart by thinner wall regions formed on the inner surface, the sidewall further comprising an outer surface that is smooth in those regions opposite the vertically oriented ribs provided on the inner surface; and    a barrel top provided with first and second lateral bung fittings.    
   
   
       33 . A pallet container having a hollow blow-molded thermoplastic inner body comprising: 
 a container bottom;    first and second pairs of substantially parallel sidewalls joined together at corner areas and connected to the canister bottom, the first and second pairs of sidewalls each having an inner surface provided with a plurality of spaced-apart vertically oriented ribs defining thicker wall regions spaced apart by thinner wall regions and an outer surface that is smooth in those regions opposite the vertically oriented ribs provided on the inner surface; and    a container top having an opening formed in a central portion thereof.    
   
   
       34 . The industrial barrel assembly according to  claim 17 , wherein an outer surface of the substantially cylindrical sidewall is smooth at least in those regions opposite the vertically oriented ribs formed on the inner surface.  
   
   
       35 . The industrial barrel assembly according to  claim 17 , wherein the thicker wall regions are equally thick and the thinner wall regions are equally thin.  
   
   
       36 . The industrial barrel assembly according to  claim 22 , wherein the barrel body has a diameter of approximately 590 mm.  
   
   
       37 . The industrial barrel assembly according to  claim 25 , wherein the barrel body has a diameter of approximately 590 mm.  
   
   
       38 . The substantially rectangular canister according to  claim 26 , wherein outer surfaces of the first and second pairs of sidewalls are smooth at least in those regions opposite said vertically oriented ribs formed on the inner surface.  
   
   
       39 . The substantially rectangular canister according to  claim 26 , wherein the thicker wall regions are equally thick and the thinner wall regions are equally thin.  
   
   
       40 . A blow-molded thermoplastic container comprising: 
 a container bottom;    first and second pairs of substantially parallel flat sidewalls joined together at corner areas and connected to the container bottom, the first and second pairs of flat sidewalls having an inner surface provided with a plurality of spaced-apart vertically oriented ribs defining thicker wall regions spaced apart by thinner wall regions formed on the inner surface; and    a container top having an opening formed in a central portion thereof, wherein a height of said first pair of sidewalls is approximately equal to a height of said second pair of sidewalls.    
   
   
       41 . The container according to  claim 40 , wherein outer surfaces of the first and second pairs of sidewalls are smooth at least in those regions opposite the vertically oriented ribs formed on the inner surfaces.  
   
   
       42 . The container according to  claim 40 , wherein the thicker wall regions are equally thick and the thinner wall regions are equally thin.  
   
   
       43 . The container of  claim 40 , wherein the opening in the container top is substantially centrally located.  
   
   
       44 . The container of  claim 33 , wherein the opening in the container top is substantially centrally located.