Plastic melt temperature control

Claim 2

A control for the temperature of plastic melt within an injection molding machine having a barrel, heating means for heating said barrel, a screw within said barrel, motor means for rotating the screw and means for applying pressure to said screw in a direction along its longitudinal axis whereby said screw acts as a piston comprising: a. a first control means connected to said heating means for controlling the amount of heat supplied to said barrel by said heating means; b. a second control means connected to said motor means for varying the rotational speed of said screw; c. a third control means connected to said means for applying pressure to said screw for varying the amount of pressure applied to said screw; and, d. means interconnecting said first, second and third control means for rendering said control means selectively operable whereby the temperature of the plastic melt is maintained within predetermined limits.

Claim 3

The invention in accordance with claim 1 wherein said means interconnecting said first, second and third control means includes selection logic circuitry for rendering each of said controls operative in a predetermined order.

Claim 4

The invention in accordance with claim 1 wherein there is further included pulse generating means to generate a train of pulses and in which each of said control means includes a reversible counter selectively responsive to said train of pulses to generate a count indicative of the magnitude of adjustment to be effected by the control.

Claim 5

The invention in accordance with claim 3 in which said pulse generating means is responsive to the temperature of the plastic melt within said barrel.

Claim 6

The invention in accordance with claim 4 in which the pulse generating means is operable to produce pulse trains of different frequencies in accordance with the amount of temperature difference between the melt and a predetermined reference.

Claim 7

The invention in accordance with claim 3 wherein said means interconnecting said first, second and third control means includes selection logic circuitry responsive to the counts in each of said counters for selectively rendering each of said controls operative in a predetermined order.

Claim 8

The invention in accordance with claim 6 wherein said selection logic circuitry determines the direction of count in said counters.

Claim 9

A melt temperature control for use with an injection molding machine having a barrel heated by a plurality of heating elements, a screw adapted for rotary and reciprocal motions disposed within the barrel, a motor for rotating the screw and means for applying pressure to the screw in a longitudinal direction, comprising: a. a source of power; b. a first control means connected to the heating elements and said source of power for varying the quantity of power applied to the heating elements; c. a pulse generating means for producing pulses at varying frequencies; d. a first reversing counter connected to said frequency generating means for selectively counting said pulses; e. means connected to said first control means and said counter for generating a signal proportional to the content of said first counter and applying said signal to said first control means for regulating the quantity of power applied to the heating elements; f. a second control means connected to the motOr and said source of power for varying the quantity of power applied to the motor; g. a second reversing counter connected to said pulse generating means for selectively counting said pulses; h. means connected to said second control means and said second counter for generating a signal proportional to the content of said counter and applying said signal to said second control means for regulating the quantity of power applied to the motor to vary the speed of said motor; i. a third control means connected to the means for applying pressure and said source of power for varying the quantity of power applied to the pressure applying means; j. a third reversing counter connected to said pulse generating means for selectively counting said pulses; k. means connected to said third control means and said third counter for generating a signal proportional to the content of said third counter and applying said signal to said third control means for regulating the quantity of power applied to the means for applying pressure to thereby vary the pressure applied to said screw; l. means connected to said first, second and third counters and said pulse generating means for selectively directing one of said counters to count said pulses; and, m. means for steering the direction of count of said counters.

Claim 10

A melt temperature control for use with an injection molding machine having a barrel heated by a plurality of heating elements, a screw adapted for rotary and reciprocal motions disposed within the barrel, a motor for rotating the screw and means for applying pressure to the screw in a longitudinal direction, comprising: a. a source of power; b. a first control means connected to the heating elements and said source of power for varying the quantity of power applied to the heating elements; c. a pulse generating means for producing pulses at varying frequencies; d. a first reversing counter connected to said frequency generating means for selectively counting said pulses; e. means connected to said first control means and said counter for generating a signal proportional to the content of said first counter and applying said signal to said first control means for regulating the quantity of power applied to the heating elements; f. a second control means connected to the motOr and said source of power for varying the quantity of power applied to the motor; g. a second reversing counter connected to said pulse generating means for selectively counting said pulses; h. means connected to said second control means and said second counter for generating a signal proportional to the content of said counter and applying said signal to said second control means for regulating the quantity of power applied to the motor to vary the speed of said motor; i. a third control means connected to the means for applying pressure and said source of power for varying the quantity of power applied to the pressure applying means; j. a third reversing counter connected to said pulse generating means for selectively counting said pulses; k. means connected to said third control means and said third counter for generating a signal proportional to the content of said third counter and applying said signal to said third control means for regulating the quantity of power applied to the means for applying pressure to thereby vary the pressure applied to said screw; l. means connected to said first, second and third counters and said pulse generating means for selectively directing one of said counters to count said pulses; and, m. means for steering the direction of count of said counters.

Claim 11

The invention in accordance with claim 8 in which the pulse generating means is responsive to the melt temperature.

Claim 12

The invention in accordance with claim 9 in which the pulse generating the frequency of pulses is dependent upon the difference between the melt temperature and a predetermined reference temperature.

Claim 13

The invention in accordance with claim 8 in which said first, second and third control means are rendered selectively operative by selection logic circuitry responsive to the content of each of said counters.