Methods for forming injected molded parts and in-mold sensors therefor

• US 8,753,553 B2
• Filed: 04/14/2009
• Issued: 06/17/2014
• Est. Priority Date: 04/14/2008
• Status: Active Grant

• Current Assignee: University Of Massachusetts
• Original Assignee: University Of Massachusetts
• Inventors: Kazmer, David, Panchal, Rahul, Johnston, Stephen
• Primary Examiner(s): HEITBRINK, JILL LYNNE
• Application Number:
  US12/937,639
• Publication Number:
  US 20110101555A1
• Time in Patent Office: 1,890 Days
• Field of Search: 264/40.1, 264/40.5, 264/40.6, 264/328.7, 425/170, 425/149, 425/150
• US Class Current: 264/40.1
• CPC Class Codes: B29C 2945/76006 Pressure
• CPC Class Codes: B29C 2945/76103 shrinkage, dilation, dimensional change, warpage
• CPC Class Codes: B29C 2945/76257 cavity
• CPC Class Codes: B29C 2945/76381 Injection
• CPC Class Codes: B29C 2945/76384 Holding, dwelling
• CPC Class Codes: B29C 2945/76391 Mould clamping, compression of the cavity
• CPC Class Codes: B29C 2945/76414 Solidification, setting phase
• CPC Class Codes: B29C 2945/76585 Dimensions, e.g. thickness
• CPC Class Codes: B29C 2945/76892 Solidification, setting phase
• CPC Class Codes: B29C 2945/76933 The operating conditions are corrected immediately, during the same phase or cycle
• CPC Class Codes: B29C 45/76 Measuring, controlling or regulating measuring in general G01; controlling or regulating in general G05

Abstract

A method for use in forming a molded part includes providing a mold having a cavity and a movable pin, injecting a moldable material into the cavity, biasing the movable pin to maintain an end of the movable pin in contact with the moldable material in the cavity during the curing of the moldable material and until the moldable material is cured, and monitoring movement of the biased movable pin during curing of the moldable material in the mold. Also disclosed is a sensor engageable with an end of a movable pin of a mold for monitoring the forming of a moldable part, and systems employing the same.

Claims

1. A method for use in forming a molded part, the method comprising:

providing a mold having a cavity and a movable pin, wherein the movable pin is movable with respect to a surface of the cavity from which the movable pin protrudes;

injecting a moldable material into the cavity;

biasing the movable pin to maintain an end of the movable pin in contact with the moldable material in the cavity during the curing of the moldable material and until the moldable material is cured; and

monitoring movement of the biased movable pin with a sensing device during curing of the moldable material in the mold.

2. The method of claim 1 further comprising controlling the forming of a plurality of the parts based on the monitored movement of the biased movable pin.

3. The method of claim 1 further comprising monitoring the biasing force exerted on the movable pin by the moldable material during curing of the moldable material in the mold.

4. The method of claim 3 further comprising controlling the forming of a plurality of the parts based on the monitored movement of the biased movable pin and the monitored biasing force exerted on the movable pin.

5. The method of claim 1 further comprising monitoring the biasing force exerted on the movable pin by the moldable material during curing of the moldable material in the mold, and monitoring the temperature of the moldable material at the end of the movable pin during curing of the moldable material.

6. The method of claim 5 further comprising controlling the forming of a plurality of the parts based on the monitored movement of the biased movable pin, the monitored biasing force exerted on the movable pin, and the monitored temperature of the moldable material.

7. The method of claim 1 wherein the monitoring the movement of the movable pin comprises using a displacement transducer.

8. The method of claim 7 wherein the displacement transducer comprises at least one of a strain gage, a capacitive displacement transducer, and a piezoelectric cell.

9. The method of claim 1 wherein the biasing the movable pin comprising applying the biasing force using at least one of a diaphragm, a coil spring, and an elastic member.

10. The method of claim 1 further comprising monitoring a biasing force exerted on the movable pin during the curing of the moldable material with at least one of a strain gage and a piezoelectric element.

11. The method of claim 1 wherein the movable pin comprises a movable ejector pin.

12. The method of claim 1, wherein the biasing of the movable pin causes the movable pin to move to maintain an end of the movable pin in contact with the moldable material when a pressure of the moldable material is zero.

13. A sensor for use in forming of a moldable part in a cavity of a mold, said sensor comprising:

a housing connectable to the mold;

a movable pin disposed in said housing, said movable pin having an end engageable with a moldable material in the cavity of the mold, wherein the movable pin is movable with respect to a surface of the cavity from which the movable in protrudes;

an elastic member supported in said housing and engageable with said movable pin for applying a biasing force on said end of said movable pin to maintain said end of said movable pin in contact with the moldable material in the cavity during curing of the moldable material and until the moldable material is cured; and

a sensing device to monitor movement of said movable pin when said movable pin is in contact with the moldable material during curing of the moldable material in the cavity.

14. The sensor of claim 13 wherein the sensing device comprises at least one strain gage operably connected to said elastic member.

15. The sensor of claim 13 wherein the sensing device comprises a capacitive device.

16. The sensor of claim 13 wherein the sensing device comprises a piezoelectric element.

17. The sensor of claim 13 wherein said elastic member comprises a diaphragm.

18. The sensor of claim 13 wherein said elastic member comprises at least one coil spring.

19. The sensor of claim 13 wherein said elastic member comprises a resilient sleeve.

20. The sensor of claim 13 further comprising means for monitoring a biasing force exerted on said movable pin by the moldable material during curing of the moldable material in the cavity during curing of the moldable material.

21. The sensor of claim 20 wherein the means for monitoring a biasing force comprises a piezoelectric element.

22. The sensor of claim 20 wherein the means for monitoring a biasing force comprises a strain gage.

23. The sensor of claim 13 further comprising means for monitoring a temperature of the moldable material at the end of the movable pin during curing of the moldable material.

24. The sensor of claim 13 wherein the means for monitoring a temperature of the moldable material at the end of the movable pin comprises a thermocouple.

25. The sensor of claim 13, wherein the elastic member applies the biasing force on said end of said movable pin to maintain said end of said movable pin in contact with the moldable material when a pressure of the moldable material is zero.

26. A method for controlling the forming of a plurality of molded parts in a cavity of a mold, the method comprising:

monitoring, using a sensing device, at least one of an in-mold part dimension of a part and in-mold shrinkage of a part based on movement of a movable pin biased to maintain an end of the movable pin in contact with moldable material in the cavity during curing of the moldable material until the moldable material is cured, wherein the movable pin is movable with respect to a surface of the cavity from which the movable pin protrudes; and

controlling a plurality of operating parameters for forming the plurality of molded parts based on the monitored at least one of the in-mold part dimension of the part and the in-mold shrinkage of the part.

27. The method of claim 26 further comprising monitoring a biasing force exerted on the movable pin by the moldable material, and the controlling further comprises controlling the plurality of operating parameters for forming the plurality of molded parts based on the monitored at least one of the in-mold part dimension of the part and in-mold shrinkage of a part, and the monitored biasing force exerted on the movable pin by the moldable material.

28. The method of claim 27 further comprising monitoring a temperature of the moldable material at the end of the movable pin during curing of the moldable material, and the controlling further comprises controlling the plurality of operating parameters for forming the plurality of molded parts based on the monitored at least one of the in-mold part dimension of the part and in-mold shrinkage of a part, the monitored biasing force exerted on the movable pin by the moldable material, and the monitored temperature of the moldable material at the end of the movable pin.

29. The method of claim 28 wherein the controlling the plurality of operating parameters comprises controlling the plurality of operating parameters comprising at least some of a pressure of the molded material, a temperature of the molded material, a temperature of the mold, a clamp force applied to the mold, a cycle time for forming the plurality of parts, material properties of the moldable material, a cooling of the mold, and a flow rate of the moldable material.

30. A system for controlling the forming of a plurality of molded parts in a cavity of a mold, the system comprising:

a sensor for monitoring at least one of an in-mold part dimension and an in-mold shrinkage of the part based on movement of a movable pin biased to maintain an end of the movable pin in contact with moldable material in the cavity during curing of the moldable material until the moldable material is cured, wherein the movable pin is movable with respect to a surface of the cavity from which the movable pin protrudes; and

a processor operable to control a plurality of operating parameters for forming the plurality of molded parts based on the monitored at least one of the in-mold part dimension of the part and the in-mold shrinkage of the part.

31. The system of claim 30 wherein said sensor is operable for monitoring a biasing force exerted on the movable pin by the moldable material during curing of the moldable material until the moldable material is cured, and the processor is operable to control the plurality of operating parameters for forming the plurality of molded parts based on the monitored in-mold part dimension and the monitored biasing force exerted on the movable pin by the moldable material.

32. The system of claim 31 wherein said sensor is operable for monitoring a temperature of the moldable material at the end of the movable pin during curing of the moldable material, and the processor is operable to control the plurality of operating parameters for forming the plurality of molded parts based on the monitored at least one of the in-mold part dimension of the part and in-mold shrinkage of a part, the monitored biasing force exerted on the movable pin by the moldable material, and the monitored temperature of the moldable material at the end of the movable pin.

33. The system of claim 32 wherein the processor is operable to control the plurality of operating parameters comprising at least some of a pressure of the molded material, a temperature of the molded material, a temperature of the mold, clamp force applied to the mold, a cycle time for forming the plurality of parts, a material properties of the moldable material, a cooling of the mold, and a flow rate of the moldable material.

34. An article of manufacture comprising:

at least one computer usable medium having computer readable program code logic to control the forming of a plurality of molded parts in a cavity of a mold, said computer readable program code logic when executing performing the following;

obtaining, using a sensing device, at least one of an in-mold dimension of the part and an in-mold shrinkage of the part based on monitoring a movable pin biased to maintain the end of the movable pin in contact with moldable material in the cavity during curing of the moldable material until the moldable material is cured, wherein the movable pin is movable with respect to a surface of the cavity from which the movable pin protrudes; and

controlling a plurality of operating parameters for forming the plurality of molded parts based on the monitored at least one of the in-mold dimension of the part and the in-mold shrinkage of the part.

35. The article of manufacture of claim 34 wherein said sensor is operable for monitoring a biasing force exerted on the movable pin by the moldable material during curing of the moldable material until the moldable material is cured, and the processor is operable to control the plurality of operating parameters for forming the plurality of molded parts based on the monitored in-mold part dimension and the monitored biasing force exerted on the movable pin by the moldable material.

36. The article of manufacture of claim 35 wherein said sensor is operable for monitoring a temperature of the moldable material at the end of the movable pin during curing of the moldable material, and the processor is operable to control the plurality of operating parameters for forming the plurality of molded parts based on the monitored at least one of the in-mold part dimension of the part and in-mold shrinkage of a part, the monitored biasing force exerted on the movable pin by the moldable material, and the monitored temperature of the moldable material at the end of the movable pin.

37. The article of manufacture of claim 36 wherein the processor is operable to control the plurality of operating parameters comprising at least some of a pressure of the molded material, a temperature of the molded material, a temperature of the mold, clamp force applied to the mold, a cycle time for forming the plurality of parts, a material properties of the moldable material, a cooling of the mold, and a flow rate of the moldable material.