Patents by Inventor Tzvetan P. Krestev

Tzvetan P. Krestev 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).

  • Patent number: 4379714
    Abstract: A method for regulating the granulometric characteristics of the components in metallurgical slags comprising the step of imparting a vibration to the slag, after the separation of the slag from the metallurgical furnace while the slag is being cooled. The imparted vibration frequency and amplitude is adjustable and ranges respectively from 12 to 100 Hz and 0.2 to 5 mm and when circular vibration is imparted from 0.4 to 12 mm.
    Type: Grant
    Filed: December 18, 1981
    Date of Patent: April 12, 1983
    Assignee: Vish-Minnogeoloshki Institute
    Inventors: Stoycho M. Stoev, Shtelyana D. Dshendova, Kiril N. Stoyanov, Raycho V. Dochev, Tzvetan P. Krestev
  • Patent number: 4306852
    Abstract: Apparatus for the sprueless injection molding of parts from polymers. The apparatus includes an injection mold having a part-forming cavity, and an injection nozzle having a front end cooperating with the mold. A selectively operated closing valve is disposed in the nozzle, the valve having a movable valve member with a valve seat thereon cooperating with a valve seat on the nozzle body. A gate channel or passage is disposed between the valve seat on the body of the nozzle and the inlet opening of the mold cavity. The movable valve member has an elongated forward end portion which is telescoped within the gate passage, the forward end portion sealingly engaging the wall of the gate passage when the valve member is in its forward, closed position, the forward end surface of the elongated forward end portion of the valve member facing the mold cavity lying substantially flush with the wall of the mold when the valve member is in its forward, valve-closed position.
    Type: Grant
    Filed: May 6, 1980
    Date of Patent: December 22, 1981
    Assignee: Nipki po Technologia na Materialite
    Inventors: Evgeni H. Mateev, Tzvetan P. Krestev