Patents by Inventor Willem C. DEN Hertog

Willem C. DEN Hertog has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Tube of thermoplastics with thickened end
    Patent number: 4150087
    Abstract: A tube of thermoplastic material is heated to plasticity, whereupon the heated tube is provided with a thickened end by subjecting the tube to an upsetting action in such a way that the thickening starts at a distance from the free end of the heated part and increases gradually from this point towards the free end of the heated part.
    Type: Grant
    Filed: December 3, 1976
    Date of Patent: April 17, 1979
    Assignee: Wavin B.V.
    Inventors: Warner J. de Putter, Willem C. Den Hertog
  • Device for forming tube with thickened socket end
    Patent number: 4131407
    Abstract: A device for manufacturing a plastic tube having a thickened socket end and being provided with an inner circular groove. The device includes a socket forming mandril having a core member associated with it. The mandril is provided with a groove-forming member. A hollow die is also provided which has a portion adapted to fittingly cooperate with the outer side of the mandril. A hollow mould lies in an adjoining relationship with the hollow die and is disposed in front of the core member. The hollow mould has an inner diameter which is greater than the outer diameter of the mandril.
    Type: Grant
    Filed: August 9, 1976
    Date of Patent: December 26, 1978
    Assignee: Wavin B.V.
    Inventors: Warner J. de Putter, Willem C. DEN Hertog