Method and apparatus for measuring the temperature of molten material in a mold cavity

Abstract

An injection molding apparatus comprises a manifold having a manifold channel for receiving a melt stream of molten material under pressure and delivering the melt stream to a nozzle channel of a nozzle. A mold cavity receives the melt stream from the nozzle and the nozzle channel communicates with the mold cavity through a mold gate. A thermocouple is coupled to the mold core of the mold cavity in order to measure the temperature of the molten material in the mold cavity.

1. An injection molding apparatus comprising:
 a manifold having a manifold channel;  
 a mold cavity having a mold core with a melt temperature sensor;  
 a nozzle having a nozzle body, a nozzle channel and a nozzle heater, wherein the nozzle channel is in fluid communication with the manifold channel and with the mold cavity through a mold gate; and  
 a controller electrically coupled to the melt temperature sensor to control the nozzle heater.  
 
     
     
       2. The injection molding apparatus of  claim 1 , wherein the nozzle heater is located in a groove disposed in the nozzle body. 
     
     
       3. The injection molding apparatus of  claim 1 , wherein the nozzle heater is a sleeve heater that is disposed about the nozzle body. 
     
     
       4. The injection molding apparatus of  claim 1 , wherein the mold core includes a cooling duct. 
     
     
       5. The injection molding apparatus of  claim 4 , further comprising a second melt temperature sensor disposed within the cooling duct, wherein the controller is electrically coupled to the second melt temperature sensor. 
     
     
       6. The injection molding apparatus of  claim 5 , wherein the melt temperature sensor is disposed on a surface of the mold core. 
     
     
       7. The injection molding apparatus of  claim 1 , wherein the controller is electrically coupled to the nozzle heater through a heater control unit. 
     
     
       8. The injection molding apparatus of  claim 1 , further comprising:
 a nozzle temperature sensor disposed about a  the mold gate and coupled to the controller.  
 
     
     
       9. The injection molding apparatus of  claim 1 , wherein the nozzle is valve-gated. 
     
     
       10. An  The injection molding apparatus comprising:
 a manifold;  
 a mold cavity having a mold core and a  of  claim 1  wherein  
   the  melt temperature sensor is disposed in a hole in a wall of the mold core;  
 a nozzle having athe nozzle heater that  is located in a groove disposed in a body of the nozzle andthe nozzle body, and the nozzle has a nozzle temperature sensor disposed adjacent to athe mold gate; and  
 athe controller is electrically coupled to the nozzle temperature sensor and the melt temperature sensor to control the nozzle heater.  
 
     
     
       11. The injection molding apparatus of  claim 10 , further comprising: a second melt temperature sensor, wherein the mold core includes a cooling duct and the melt temperature sensor is disposed within the cooling duct. 
     
     
       12. The injection molding apparatus of  claim 10 , wherein the melt temperature sensor is disposed in a tip of the mold core. 
     
     
       13. An injection molding apparatus comprising:
 a manifold;  
 a plurality of nozzles each having a nozzle heater and a nozzle temperature sensor;  
 at least one mold cavity having a melt temperature sensor disposed adjacent to the mold cavity; and  
 a controller electrically coupled to the melt temperature sensor and the nozzle temperature sensor of at least one of the plurality of nozzles to control the nozzle heater of the at least one of the plurality of nozzle heaters  nozzles.  
 
     
     
       14. The injection molding apparatus of  claim 13 , wherein the mold cavity includes a mold core. 
     
     
       15. The injection molding apparatus of  claim 14 , wherein the melt temperature sensor is disposed within the mold core. 
     
     
       16. The injection molding apparatus of  claim 13 , wherein the controller is electrically coupled to the nozzle heaters through a heater control unit. 
     
     
       17. The injection molding apparatus of  claim 13 , wherein at least one of the plurality of nozzles includes a nozzle temperature sensor and the controller is electrically coupled to the at least one nozzle temperature sensor to control the nozzle heater. 
     
     
       18. The injection molding apparatus of  claim 1 , wherein the nozzle includes a nozzle temperature sensor and the controller is electrically coupled to the nozzle temperature sensor to control the nozzle heater. 
     
     
       19. A method of injection molding comprising the steps of:
 delivering a melt stream of molten material from a manifold channel of a manifold under pressure through a nozzle channel of a nozzle and into a mold cavity;  
 measuring a temperature of the molten material at the nozzle channel using a nozzle temperature sensor coupled to a controller; 
 measuring the temperature of the molten material in the mold cavity using a melt cavity temperature sensor coupled to the controller; and  
 controlling the temperature of the molten material by adjusting the output of a nozzle heater located on the nozzle based on the measurement of the temperature of the molten material measured by the melt cavity temperature sensor and the nozzle temperature sensor.  
 
     
     
       20. The method of injection molding of  claim 19 , further comprising the steps of:
 providing the nozzle with a nozzle temperature sensor;    measuring the temperature of the molten material in the mold cavity using the nozzle temperature sensor; and    controlling the temperature of the molten material by adjusting the output of the nozzle heater based on the measurement of the temperature of the molten material measured by the nozzle temperature sensor.    
     
     
       21. The method of injection molding of claim  20    19 , wherein the nozzle temperature sensor measures the temperature of the molten material at a mold gate. 
     
     
       22. The injection molding apparatus of  claim 1  wherein the nozzle includes movable valve pin for controlling the flow of melt into the mold cavity, the controller being electrically coupled to the valve pin to adjust movement thereof in response to information from the melt temperature sensor. 
     
     
       23. The injection molding apparatus of  claim 13  including a plurality of mold cavities each having a respective melt temperature sensor disposed adjacent thereto, each mold cavity being associated with a respective nozzle to receive melt therefrom, the controller being electrically coupled to each of the melt temperature sensors and the nozzle temperature sensors to independently control the nozzle heaters of the plurality of nozzles. 
     
     
       24. An injection molding apparatus comprising:
   a manifold having a manifold channel for receiving a melt stream of molten material under pressure;        a nozzle having a nozzle channel for receiving the melt stream from the manifold channel, the nozzle having a nozzle heater;        a mold cavity for receiving the melt stream from said nozzle, said nozzle channel communicating with said mold cavity through a mold gate;        a melt temperature sensor located adjacent the mold cavity near the mold gate for measuring a temperature of the molten material in said mold cavity near the mold gate; and        a controller coupled to the melt temperature sensor and the nozzle heater for controlling the nozzle heater in response to measurements from the melt temperature sensor.     
     
     
       25. The injection molding apparatus of  claim 24  wherein said nozzle has a nozzle temperature sensor coupled to the controller and said nozzle temperature sensor is used to measure the temperature in the proximity of a nozzle tip. 
     
     
       26. The injection molding apparatus of  claim 24  wherein the flow of melt from the nozzle to the mold cavity is controlled by a movable valve pin and the movement of said valve pin is controlled by the controller in response to measurements from the melt temperature sensor. 
     
     
       27. An injection molding apparatus comprising:
   a manifold having a manifold channel for receiving a melt stream of molten material under pressure;        at least two nozzles each having a nozzle channel for receiving the melt stream from the manifold channel;        a mold cavity for receiving the melt stream from said nozzles, each of said nozzle channels communicating with said mold cavity through a separate mold gate;        a pair of first melt temperature sensors and a pair of second melt temperature sensors located in the mold cavity, each of the first melt temperatures sensors being close to a respective one of the mold gates to provide temperature measurements, each of the second melt temperature sensors being located at a predetermined distance from a respective one of mold gates to provide additional temperature measurements of the melt inside the mold cavity; and        a movable valve pin located in each nozzle channel movable to control the flow of melt from each nozzle through the mold gates into said mold cavity.