PLASTIC INJECTION MOLDING MACHINE MONITOR

• US 3,750,134 A
• Filed: 02/11/1971
• Issued: 07/31/1973
• Est. Priority Date: 02/11/1971
• Status: Expired due to Term

• Current Assignee: Burke A. Weisend
• Original Assignee: Burke A. Weisend
• Inventors: Weisend, Burke A.
• Primary Examiner(s): Trafton, David L.
• Application Number:
  US05/114,426
• Time in Patent Office: 901 Days
• Field of Search: 340/324A,212,213R,213Q 425/145
• US Class Current: 345/618
• CPC Class Codes: B29C 2037/906 using visualisation means or linked accessories, e.g. screens, printers
• CPC Class Codes: B29C 45/76 Measuring, controlling or regulating measuring in general G01; controlling or regulating in general G05

Abstract

A monitoring system for a plastic injection molding machine adapted to measure the temperature and pressure of the material being plasticized and injected and to determine the position of the machine ram at any selected point in time in the machine cycle. The system employs sensors for the aforesaid measurements and determinations which are connected in electrical circuitry adapted to compare the sensed information with selected and adjustable upper and lower limits and to provide an alarm signal when the limits are crossed. An oscilloscopic display unit is employed to provide a visual comparison of sensed machine information with the said limits when desired.

Claims

1. A monitor system for a plastic injection molding machine having means for plasticizing a material subjected to heat and a reciprocating ram for injecting it into a cavity defined between mold halves which are closed and opened during a cycle of machine operation, the said system comprising a sensor associated with the machine to measure and be responsive to at least one parameter of the group consisting of ram position, material temperature and material pressure and connected in first circuit means for generating trace signal voltages responsive to measurement of the parameter over a time period taken for at least a portion of a machine cycle, said first circuit means being included in a powered electrical circuitry complex which also includes individually adjustable second and third circuit means for selecting and producing upper and lower signal voltages, respectively, at a selected point in time during generation of said trace, and additional circuit means for comparing said upper and lower signal voltages with the trace signal voltage at the selected point in time and for providing an alarm signal output in the event the trace signal voltage exceeds or falls below the respective upper and lower signal voltages at the selected point in time.

2. A monitor system as defined in claim 1 wherein said second and third circuit means are limited in their capability for producing upper and lower signal voltages to the same selected point in time for comparison with the trace signal voltage.

3. A monitor system as set forth in claim 1 wherein there are a plurality of the said sensors, each responsive to one of said parameters;

and at least an equal plurality of powered electrical circuitry complexes, each associated with one of said sensors; and

wherein all such complexes may operate simultaneously, each with the capability of producing its individual alarm signal output.

4. A monitor system as set forth in claim 1 wherein there are a plurality of the said sensors, each responsive to one of said parameters;

an at least equal plurality of powered electrical circuitry complexes, each associated with one of said sensors and each having means for selecting the length of time period during which its first circuit means generates trace signal voltages; and

wherein all such complexes may operate simultaneously, each with the capability of producing it individual alarm signal output.

5. A monitor system as set forth in claim 1 wherein there are a plurality of the said sensors, each responsive to one of said parameters;

an at least equal plurality of powered electrical circuitry complexes, each associated with one of said sensors and each having means for selecting the length of time period during which its first circuit means generates trace signal voltages and each having its seconD and third circuit means limited in capability for producing upper and lower signal voltages to the same selected point in time for comparison with its trace signal voltage.

6. A monitor system as in claim 1 wherein the molding machine is operated to provide two stages of pressure, a first timed stage and a second timed stage thereafter, and wherein one said sensor is provided to measure and be responsive to pressure, the said sensor being connected in said first circuit means included in each of two of said circuitry complexes operable, respectively, during said first and second timed stages.

7. A monitor system as set forth in claim 1 wherein there are a plurality of the said sensors, each responsive to one of said parameters;

an at least equal plurality of powered electrical circuitry complexes, each associated with one of said sensors; and

wherein the ram position sensor comprises a linear resistance potentiometer, the temperature sensor comprises a thermocouple, and the pressure sensor comprises a strain gage transducer.

8. A monitor system for a plastic injection molding machine having means for plasticizing a material subjected to heat and a reciprocating ram for injecting it into a cavity defined between mold halves which are closed and opened during a cycle of machine operation, the said system comprising a sensor associated with the machine to measure and be responsive to at least one parameter of the group consisting of ram position, material temperature and material pressure and connected in first circuit means for generating trace signal voltages responsive to measurement of the parameter over a time period taken for at least a portion of a machine cycle, said first circuit means being included in a powered electrical circuitry complex which also includes individually adjustable second and third circuit means for selecting and producing upper and lower signal voltages, respectively, at a selected point in time during generation of said trace, additional circuit means for comparing said upper and lower signal voltages with the trace signal voltage at the selected point in time and for producing an alarm signal output in the event the trace signal voltage exceeds or falls below the respective upper and lower signal voltages, and a display unit connected with said circuitry complex to provide a display of said trace and said upper and lower signal voltages for visual comparison.

9. The monitor system of claim 8 wherein the said display unit is oscilloscopic and has a storage capability and the circuitry complex includes selector means for displaying one or a plurality of cycle traces for comparison with said upper and lower signal voltages.

10. The monitor system as defined in claim 8 wherein there are a plurality of the said sensors;

each responsive to one of said parameters;

an at least equal plurality of the powered circuitry complexes, each associated with one of said sensors and all said complexes being operable simultaneously; and

wherein said display unit is oscilloscopic and is connected with all of said complexes, the connection including means for selecting individual complexes for display of their traces with their associated upper and lower signal voltages.

11. The monitor system as set forth in claim 8 wherein there are a plurality of the said sensors;

each responsive to one of said parameters;

an at least equal plurality of the powered circuitry complexes, each associated with one of said sensors and all said complexes being operable simultaneously; and

wherein said display unit is oscilloscopic and is connected with all of said complexes, the connection including means for selecting individual complexes for display of their traces with their associated upper and lower signal voltages and for selecting the length of the time period during which the first circuit means of the selected complex generates trace signal voltages.

12. The monitor system of claim 8 wherein there are a plurality of the said sensors;

each responsive to one of said parameters;

an at least equal plurality of the powered circuitry complexes, each associated with one of said sensors and all said complexes being operable simultaneously but each being independent of the other in selecting and adjusting its upper and lower signal voltages and the point in time for such upper and lower signal voltages; and

wherein said display unit is oscilloscopic and is connected with all of said complexes, the connection including means for selecting individual complexes for display of their traces with associated upper and lower signal voltages and for selecting the length of the time period during which the first circuit means of the selected complex generates trace signal voltages.