Injection molding machine with shot size regulation

Claim 2

A rotary injection molding machine including a plasticator unit, a plurality of molds for displacement along a path into a work position adjacent the plasticator, an injection assembly including an accumulator chamber, a reciprocable member positioned at least partially in the chamber, means for regulating movement of said member within the accumulator chamber, a valve effective in a first position to complete a passage between the accumulator chamber and an input channel through which molten plastic is received from the plasticator, and effective in a second position to complete a passage between the accumulator chamber and output channel for discharging the accumulated plastic toward the mold, and first and second control systems for regulating the amount of plastic accumulated and discharged into first and second molds by regulating displacement of said member; said first control system comprising: a comparator circuit having first and second input connections and an output connection for providing a control signal responsive to equality between signals received at the input connections, a first potentiometer coupled to a first input connection of The comparator circuit for presetting a reference signal indicating the desired quantity of plastic to be accumulated and discharged to the first mold, a second potentiometer electrically coupled to the second input connection of the comparator circuit and mechanically coupled for operation as a function of displacement of said member to provide a position signal that varies as a function of the position of the member, and switching means connected for operation by the control signal to terminal displacement of said member when the desired quantity of plastic material is present in the accumulator chamber; and said second control system comprising: a comparator circuit having first and second input connections and an output connection for providing a control signal responsive to equality between signals received at the input connections, a first potentiometer coupled to a first input connection of the comparator circuit for presetting a reference signal indicating the desired quantity of plastic to be accumulated and discharged to the second mold, means for coupling the second input connection of the comparator circuit to said second potentiometer which provides the position signal as a function of the displacement of said member; and switching means connected for operation by the lastmentioned control signal to terminate displacement of said member when the desired quantity of plastic material for the second mold is present in the accumulator chamber.

Claim 3

A rotary injection molding machine as claimed in claim 1, in which each of the control systems further includes a signal inversion stage for providing a ''''not'''' output signal to prevent injection into the associated mold until the comparator circuit of the given control system recognizes equality between the reference and position signals, thus indicating the desired quantity of plastic material has been accumulated for the mold then in the work position.

Claim 4

A rotary injection molding machine including a plasticator unit, a plurality of molds for displacement along a path into a work position adjacent the plasticator, an injection assembly including an accumulator chamber, a reciprocable member positioned at least partially in the chamber, means for regulating movement of said member within the accumulator chamber, a valve effective in a first position to complete a passage between the accumulator chamber and an input channel through which molten plastic is received from the plasticator, and effective in a second position to complete a passage between the accumulator chamber and an output channel for discharging the accumulated plastic toward the mold, and first and second control systems for regulating the amount of plastic accumulated and discharged into first and second molds by regulating displacement of said member; said first control system comprising a comparator circuit having first and second input connections and an output connection for providing a control signal responsive to a predetermined relationship between signals received at the input connections, a first potentiometer coupled to a first input connection of the comparator circuit for presetting a reference signal indicating the desired quantity of plastic to be accumulated and discharged to the first mold, a second potentiometer electrically coupled to the second input connection of the comparator circuit and mechanically coupled for operation as a function of displacement of said member to provide a position signal that varies as a function of the position of the member; and switching means connected for operation by the control signal to terminate displacement of said member when the desired quantity of plastic material is present in the accumulator chamber; and said second control system comprising: a comparator circuit having first and second input connections and an output connection for providing a control signal responsive to a predetermined relationship between signals reCeived at the input connections, a first potentiometer coupled to a first input connection of the comparator circuit for presetting a reference signal indicating the desired quantity of plastic to be accumulated and discharged to the second mold, means for coupling the second input connection of the comparator circuit to said second potentiometer which provides the position signal as a function of the displacement of said member; and switching means connected for operation by the lastmentioned control signal to terminate displacement of said member when the desired quantity of plastic material for the second mold is present in the accumulator chamber.

Claim 5

A rotary injection molding machine including a plasticator unit, a plurality of molds for displacement along a path into a work position adjacent the plasticator, an injection assembly including an accumulator chamber, a reciprocable member positioned at least partially in the chamber, means for regulating movement of said member within the accumulator chamber, a valve effective in a first position to complete a passage between the accumulator chamber and an input channel through which molten plastic is received from the plasticator, and effective in a second position to complete a passage between the accumulator chamber and an output channel for discharging the accumulated plastic toward the mold, and first and second control systems for regulating the amount of plastic accumulated and discharged into first and second molds by regulating displacement of said member; said first control system comprising a comparator circuit having first and second input connections and an output connection for providing a control signal responsive to a predetermined relationship between signals received at the input connections, a first potentiometer coupled to a first input connection of the comparator circuit for presetting a reference signal indicating the desired quantity of plastic to be accumulated and discharged to the first mold, a second potentiometer electrically coupled to the second input connection of the comparator circuit and mechanically coupled for operation as a function of displacement of said member to provide a position signal that varies as a function of the position of the member; and switching means connected for operation by the control signal to terminate displacement of said member when the desired quantity of plastic material is present in the accumulator chamber; and said second control system comprising: a comparator circuit having first and second input connections and an output connection for providing a control signal responsive to a predetermined relationship between signals reCeived at the input connections, a first potentiometer coupled to a first input connection of the comparator circuit for presetting a reference signal indicating the desired quantity of plastic to be accumulated and discharged to the second mold, means for coupling the second input connection of the comparator circuit to said second potentiometer which provides the position signal as a function of the displacement of said member; and switching means connected for operation by the lastmentioned control signal to terminate displacement of said member when the desired quantity of plastic material for the second mold is present in the accumulator chamber.

Claim 6

An injection molding machine for injecting different controlled quantities of plastic material into molds of different capacities, comprising a plasticator, an accumulation chamber, a member in the accumulation chamber displaceable in a first direction to accumulate a volume of plastic material and in a second direction to inject the accumulated volume to a mold, means defining a path for the movement of said molds, means adjacent said path defining an injection station at which said accumulated volume of plastic material is injected into a mold, and control means for varying the volume of the plastic material accumulated in said chamber for different capacity molds, said control means including a plurality of control systems one for each of a plurality of different volumes of material to be accumulated in said chamber for injection into molds of different capacities, each said control system comprising: a comparator circuit, having first and second input connections and an output connection for providing a control signal responsive to equality between signals received at the input connections; a first potentiometer, coupled to a first input connection of the comparator circuit, for presetting a reference signal indicating the desired quantity of plastic to be accumulated and discharged to a mold; a second potentiometer, electrically coupled to the second input connection of the comparator circuit, and mechanically coupled for operation as a function of displacement of said member, to provide a position signal which varies as a function of the position of the member; and switching means connected for operation by the control signal to terminate displacement of said member when the desired quantity of plastic material is present in the accumulator chamber, whereby said first potentiometer of each control system can be preset to establish different reference signals to vary the amount of material injected into different molds.

Claim 7

An injection molding machine for injecting different controlled quantities of plastic material into molds of different capacities, comprising a plasticator, an accumulation chamber, a member in the accumulation chamber displaceable in a first direction to accumulate a volume of plastic material and in a second direction to inject the accumulated volume to a mold, means defining a path for the movement of said molds, means adjacent said path defining an injection station at which said accumulated volume of plastic material is injected into a mold, and control means for varying the volume of the plastic material accumulated in said chamber for different capacity molds, said control means including a plurality of control systems one for each of a plurality of different volumes of material to be accumulated in said chamber for injection into molds of different capacities, each said control system comprising: a comparator circuit, having first and second input connections and an output connection for providing a control signal responsive to equality between signals received at the input connections; a first potentiometer, coupled to a first input connection of the comparator circuit, for presetting a reference signal indicating the desired quantity of plastic to be accumulated and discharged to a mold; a second potentiometer, electrically coupled to the second input connection of the comparator circuit, and mechanically coupled for operation as a function of displacement of said member, to provide a position signal which varies as a function of the position of the member; and switching means connected for operation by the control signal to terminate displacement of said member when the desired quantity of plastic material is present in the accumulator chamber, whereby said first potentiometer of each control system can be preset to establish different reference signals to vary the amount of material injected into different molds.

Claim 8

An injection molding machine as claimed in claim 4, in which said switching means includes at least one amplifier circuit for providing a normal output signal at a first output terminal upon receipt of said control signal to halt displacement of said member.

Claim 9

An injection molding machine as claimed in claim 5, and further comprising a signal inversion stage, coupled to the first output terminal for providing a ''''not'''' output signal at a second terminal until there is equality between the reference signal and position signal.

Claim 10

An injection molding machine as claimed in claim 4, and further comprising means for applying an inhibit signal to the switching means, to prevent operation of the control system associated with a given mold until that mold is moved into the work position adjacent the plasticator unit.

Claim 11

An injection molding machine for injecting different controlled quantities of plastic material into molds of different capacities, comprising a plasticator, an accumulation chamber, a member in the accumulation chamber displaceable in a first direction to accumulate a volume of plastic material and in a second direction to inject the accumulated volume to a path for the movement of said molds, means adjacent said path defining an injection station at which said accumulated volume of plastic material is injected into a mold, and control means fOr varying the volume of the plastic material accumulated in said chamber for different capacity molds, said control means including a plurality of control systems one for each of a plurality of different volumes of material to be accumulated in said chamber for injection into molds of different capacities, each said control system comprising: a comparator circuit, having first and second input connections and an output connection for providing a control signal responsive to a predetermined relationship between signals received at the input connections; a first potentiometer, coupled to a first input connection of the comparator circuit, for presetting a reference signal indicating the desired quantity of plastsic to be accumulated and discharged to a mold; a second potentiometer, electrically coupled to the second input connection of the comparator circuit, and mechanically coupled for operation as a function of displacement of said member, to provide a position signal which varies as a function of the position of the member; and switching means connected for operation by the control signal to terminate displacement of said member when the desired quantity of plastic material is present in the accumulator chamber, whereby said first potentiometer of each control system can be preset to establish different reference signals to vary the amount of material injected into different molds.

Claim 12

An injection molding machine for injecting different controlled quantities of plastic material into molds of different capacities, comprising a plasticator, an accumulation chamber, a member in the accumulation chamber displaceable in a first direction to accumulate a volume of plastic material and in a second direction to inject the accumulated volume to a path for the movement of said molds, means adjacent said path defining an injection station at which said accumulated volume of plastic material is injected into a mold, and control means fOr varying the volume of the plastic material accumulated in said chamber for different capacity molds, said control means including a plurality of control systems one for each of a plurality of different volumes of material to be accumulated in said chamber for injection into molds of different capacities, each said control system comprising: a comparator circuit, having first and second input connections and an output connection for providing a control signal responsive to a predetermined relationship between signals received at the input connections; a first potentiometer, coupled to a first input connection of the comparator circuit, for presetting a reference signal indicating the desired quantity of plastsic to be accumulated and discharged to a mold; a second potentiometer, electrically coupled to the second input connection of the comparator circuit, and mechanically coupled for operation as a function of displacement of said member, to provide a position signal which varies as a function of the position of the member; and switching means connected for operation by the control signal to terminate displacement of said member when the desired quantity of plastic material is present in the accumulator chamber, whereby said first potentiometer of each control system can be preset to establish different reference signals to vary the amount of material injected into different molds.

Claim 13

Apparatus as set forth in claim 3 wherein said plasticator unit includes means operable to separately prepare one after the other first and second quantities of plastic material of different predetermined amounts for transfer to and accumulation in said chamber and successive injection into said first and second molds, respectively.

Claim 14

Apparatus as set forth in claim 8 wherein said plasticator includes means operable to separately prepare one after the other volumes of plastic material of different predetermined quantities for injection into molds of differerent capacities.