Flasks, in particular retractable feeding bottles

Abstract

A flask having a retractable body of approximately cylindrical plastic material formed by a succession of conical upper and lower sections connected at their apexes and in their troughs, an angle α being formed between the conical upper section and a transverse plane and an angle β being formed between the conical lower section and a transverse plane, wherein the succession of conical sections alternate rigid/flexible, making it possible to obtain at least two stable extension positions, and a plurality of stable intermediate positions having axial symmetry, and wherein the radius of curvature of the troughs is less than or equal to about 0.2 millimeters.

What is claimed is:  
     
         1 . A flask having a retractable body of approximately cylindrical plastic material formed by a succession of conical upper and lower sections connected at respective apexes and troughs, an angle α being formed between the conical upper section and a transverse plane and an angle β being formed between the conical lower section and a transverse plane, wherein the succession of conical sections alternate rigid/flexible, to thereby obtain at least two stable extension positions, and a plurality of stable intermediate positions having axial symmetry, and wherein the radius of curvature of the troughs is less than or equal to about 0.2 millimeters.  
     
     
         2 . The flask according to    claim 1   , wherein the angle α is greater than the angle β.  
     
     
         3 . The flask according to    claim 1   , wherein α-β is greater than or equal to about 4°.  
     
     
         4 . The flask according to    claim 2   , wherein α-β is greater than or equal to about 4°.  
     
     
         5 . The flask according to    claim 1   , wherein the radius of curvature of a connection zone between conical upper section and conical lower section is greater than or equal to twice the thickness of the wall.  
     
     
         6 . A flask according to    claim 1   , wherein the angle β formed between is about 35° and about 40°.  
     
     
         7 . The flask according to    claim 1   , wherein a ratio I/R between length I of the lower section and radius R at a trough is between about 0.35 and about 0.50.  
     
     
         8 . The flask according to    claim 1   , further comprising wall calibration marks for determining the volume of liquid contained in the flask in an expanded mode.  
     
     
         9 . The flask according to    claim 1   , wherein the length of the lower section is greater than about 80% of the dimension of the upper section.  
     
     
         10 . The flask according to    claim 1   , wherein stress β is greater than or equal to about 60% of stress α.  
     
     
         11 . The flask according to    claim 1   , wherein stress β is less than or equal to about 80% of stress of α.  
     
     
         12 . The flask according to    claim 1   , wherein the upper sections are thicker than the lower sections.