Apparatus for and method of manufacturing of preforms having a longitudinal wall with a variable cross section

An apparatus for manufacturing a tube-like preform having a longitudinal wall with a variable cross-section for blow molding of a hollow body from a thermoplastic material, said apparatus comprising:

• a tubular die having an exit opening with a variable cross-section;
• a collar die having a recess, said collar die being movable into engagement with and away from said tubular die, the thermoplastic material being injected through said exit opening of said tubular die into recess of said collar die when said collar die sits on said tubular die, and the preform being manufactured upon movement of said collar die away form said tubular die;
• first drive means for moving said collar die into engagement with and away from said tubular die;
• second drive means for varying the cross-section of said exit opening of said tubular die;
• first control means for controlling operation of said first drive means;
• and
• second control means for controlling operation of said second drive means;
• wherein said first control means and said second control means are actuatable during movement of said collar die away from said tubular die, and are operable in accordance with displacement paths of said collar die and said second drive means;
• wherein said first control means and said second control means are associated with computer means, constantly operable during movement of said collar die away from said tubular die, for producing the preform, said computer means being connected with storage means containing the program for forming the variable cross-section of the wall of the preform along its entire longitudinal extent in accordance with a displacement path of said collar die when it moves away from said tubular die, whereby a speed of movement of said collar die away from said tubular die, which increases from a zero value, is continuously controlled and oscillations of larger and smaller cross-sections of said exit opening of said tubular die are controlled in accordance with a continuously controlled speed rate of the movement of said collar die away from said tubular die, so that a thickness of the wall of the produced preform changes from peaks to valleys in a wave-like manner to form the variable cross-section of the wall;
• wherein said tubular die includes an axially adjustable die torpedo for changing the cross-section of said exit opening of said tubular die, said second drive means driving said torpedo;
• and wherein said second control means comprises a second continuously operable displacement measuring device for determining positions of said second drive means and connected with said computer means, said second displacement measuring device comprising an ultrasound position sensor including a movable position indicator-ring magnet, a measuring tube encompassing a measuring wire and associated with an electrical pulse sender and an ultrasound pulse receiver.

An apparatus for manufacturing a tube-like preform having a longitudinal wall with a variable cross-section for blow molding of a hollow body from a thermoplastic material, said apparatus comprising:

• a tubular die having an exit opening with a variable cross-section;
• a collar die having a recess, said collar die being movable into engagement with and away from said tubular die, the thermoplastic material being injected through said exit opening of said tubular die into said recess of said collar die when said collar die sits on said tubular die, and the preform being manufactured upon movement of said collar die away form said tubular die;
• first drive means for moving said collar die into engagement with and away from said tubular die;
• second drive means for varying the cross-section of said exit opening of said tubular die;
• first control means for controlling operation of said first drive means;
• and
• second control means for controlling operation of said second drive means;
• wherein said first control means and said second control means are actuatable during movement of said collar die away from said tubular die, and are operable in accordance with displacement paths of said collar die and said second drive means;
• wherein said first control means and said second control means are associated with computer means, constantly operable during movement of said collar die away from said tubular die, for producing the preform, said computer means being connected with storage means containing a program for forming the variable cross-section of the wall of the preform along its entire longitudinal extent in accordance with a displacement path of said collar die when it moves away from said tubular die, whereby a speed of movement of said collar die away from said tubular die, which increases from a zero value, is continuously controlled and oscillations of larger and smaller cross-sections of said exit opening of said tubular die are controlled in accordance with a continuously controlled speed rate of the movement of said collar die away from said tubular die, so that a thickness of the wall of the produced preform changes from peaks to valleys in a wave-like manner to form the variable cross-section of the wall;
• and wherein said apparatus further comprises a pressure piston movable along a straight line for pressing the thermoplastic material through said exit opening of said tubular die;
• and third drive means for displacing said pressure piston;
• third control means for controlling operation of said third drive means for changing a displacement speed of said pressure piston said third control means comprising a third continuously operable displacement measuring device for determining positions of said pressure piston and connected with said computer means, said third displacement measuring device comprising an ultrasound position sensor including a movable position indicator-ring magnet, a measuring tube encompassing a measuring wire and associated with an electrical pulse sender and an ultrasound pulse receiver.

An apparatus for manufacturing a tube-like preform having a longitudinal wall with a variable cross-section for blow molding of a bellows from a thermoplastic material, said apparatus comprising:

• a tubular die having an exit opening with a variable cross-section;
• a collar die having a recess, said collar die being movable into engagement with and away from said tubular die, the thermoplastic material being injected through said exit opening of said tubular die into said recess of said collar die when said collar die sits on said tubular die, and the preform being manufactured upon movement of said collar die away form said tubular die;
• first drive means for moving said collar die into engagement with and away from said tubular die;
• second drive means for varying the cross-section of said exit opening of said tubular die;
• first control means for continuously controlling operation of said first drive means;
• second control means for continuously controlling operation of said second drive means;
• and
• computer means for continuously controlling a speed of said first drive means and displacement of said second drive means in accordance with operation of said first control means and said second control means and in accordance with a program, which controls forming the cross-section of the wall of the preform along its entire longitudinal extent in accordance with the displacement path of said collar die when it moves away from said tubular die, in such a manner that oscillations of larger and smaller cross-sections of said exit opening of said tubular die correspond to a continuously controlled speed rate of the movement of said collar die so, that a thickness of the wall of the produced preform changes from peaks to valleys in a wave-like manner to form the variable cross-section of the wall.