Die swell testing

Claim 1

An apparatus for the direct and instantaneous measurement of the die swell S of a visco-elastic material, comprising; a. extrusion means including a cylinder having a bore therein for containing a quantity of said material, a die disposed at one end of said bore, a piston slidably disposed in said bore, and a drive unit operatively connected with said piston for selectively moving the same toward said die so as to force said material, when disposed in said bore, out of the latter via said die at a constant velocity U; b. first sensor means disposed below said extrusion means and in the immediate vicinity of said die adjacent the path of the extrudate after the latter exits from said die; c. second sensor means disposed below and spaced a distance d from said first sensor means adjacent said path of the extrudate, said distance between said first and second sensor means being numerically equal to said velocity; and d. timing means operatively connected to said first and second sensor means so as to be triggered into starting upon a specified section of the extrudate moving into the sensing region of said first sensor means, and so as to be triggered into stopping upon said specified section of the extrudate moving into the sensing region of said second sensor means, said timing means thereby serving to measure the time t it takes said specified section of the extrudate to move said distance so that, with die swell being defined by the relation S (U/d)t, the time reading is a direct and instantaneous measurement of the die swell.

Claim 2

An apparatus for the direct and instantaneous measurement of the die swell S of a visco-elastic material, comprising; a. extrusion means including a cylinder having a bore therein for containing a quantity of said material, a die disposed at one end of said bore, a piston slidably disposed in said bore, and a drive unit operatively connected with said piston for selectively moving the same toward said die so as to force said material, when disposed in said bore, out of the latter via said die at a constant velocity U; b. first sensor means disposed below said extrusion means and in the immediate vicinity of said die adjacent the path of the extrudate after the latter exits from said die; c. second sensor means disposed below and spaced a distance d from said first sensor means adjacent said path of the extrudate, said distance between said first and second sensor means being numerically equal to said velocity; and d. timing means operatively connected to said first and second sensor means so as to be triggered into starting upon a specified section of the extrudate moving into the sensing region of said first sensor means, and so as to be triggered into stopping upon said specified section of the extrudate moving into the sensing region of said second sensor means, said timing means thereby serving to measure the time t it takes said specified section of the extrudate to move said distance so that, with die swell being defined by the relation S (U/d)t, the time reading is a direct and instantaneous measurement of the die swell.

Claim 5

A method of directly and instantaneously measuring the die swell S of a visco-elastic material, comprisIng the steps of: a. extruding said material vertically downwardly through a die at a constant velocity U; b. allowing the resultant extrudate to swell freely immediately after exiting from the die; c. causing said extrudate to travel vertically in a downward direction so as to have a specified section of the extrudate move sequentially past and thereby activate a first sensor located in the immediate vicinity of the die exit and a second sensor located a distance d below said first sensor; d. adjusting said sensors to make said distance d therebetween numerically equal to said velocity U; and e. measuring the time interval between activation of said sensors to provide a reading of the time t taken by said specified section of said extrudate to travel said distance d from said first to said second sensor; f. whereby with the die swell being defined by the relation S (U/d)t, the time reading is a direct and instantaneous measurement of the die swell.

Claim 6

A method of directly and instantaneously measuring the die swell S of a visco-elastic material, comprisIng the steps of: a. extruding said material vertically downwardly through a die at a constant velocity U; b. allowing the resultant extrudate to swell freely immediately after exiting from the die; c. causing said extrudate to travel vertically in a downward direction so as to have a specified section of the extrudate move sequentially past and thereby activate a first sensor located in the immediate vicinity of the die exit and a second sensor located a distance d below said first sensor; d. adjusting said sensors to make said distance d therebetween numerically equal to said velocity U; and e. measuring the time interval between activation of said sensors to provide a reading of the time t taken by said specified section of said extrudate to travel said distance d from said first to said second sensor; f. whereby with the die swell being defined by the relation S (U/d)t, the time reading is a direct and instantaneous measurement of the die swell.