Plastic and nonmetallic article shaping or treating: processes – With measuring – testing – or inspecting – Positioning of a mold part to form a cavity or controlling...
Reexamination Certificate
1998-11-16
2001-09-25
Heitbrink, Jill L. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
With measuring, testing, or inspecting
Positioning of a mold part to form a cavity or controlling...
C264S299000, C264S320000, C425S149000
Reexamination Certificate
active
06294113
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a touch sensor, and more specifically, to enhancing contact or pressure between a mold closure and a workpiece to prevent lateral movement of the workpiece during compression molding.
Typically, a multilayered workpiece is formed layer by layer, where individual layers can vary by at least 5-10% in thickness. The workpiece is then debulked by applying a vacuum and heat to remove gas and pre-densify the workpiece. Finally, the workpiece is placed in a sealed bag in a mold and further densified into a final formed workpiece using only autoclave air pressure. Compression molding a debulked workpiece, however, has been found to provide better exterior surface geometry than conventional autoclave molding, as well as forcing the workpiece to a final geometry which is less dependent on material layer variability.
In a compression molding process, the preformed workpiece is assembled similar to the autoclave process. Instead of autoclave molding the workpiece for final densification, however, the debulked workpiece is placed in a compression mold cavity and a mold closure moves into contact with the workpiece while the mold is also heated according to a pre-determined temperature schedule. Final densification of the workpiece is performed by compressing the workpiece between the mold cavity and the mold closure within the mold.
Unfortunately, the act of obtaining better exterior surface geometry through compression molding may, in some cases, lead to the generation of excessive lateral flow of one or more layers of the workpiece. The excessive lateral flow may tend to form wrinkles in the one or more layers. Such wrinkles create an abnormality in the workpiece and in some cases may lead to a derating of the strength of the final formed workpiece.
One cause for the excessive lateral flow is believed to be non-uniform contact between the mold and the workpiece, particularly upon initial contact of the mold with the workpiece before compression molding commences. Another cause is believed to be non-uniform pressure applied to the workpiece during compression molding. Consequently, it is desirable to assure that the mold contacts the preformed workpiece as completely and uniformly as possible before and during compression molding to reduce the likelihood of excessive lateral motion of the workpiece relative to the mold. For a similar reason, it is desirable to assure that the pressure applied upon the preformed workpiece during compression molding is tailored to get a high quality part.
Accordingly, there is a need in the art for an improved mold closure.
SUMMARY OF THE INVENTION
An apparatus and method is disclosed for sensing touch between a compression mold and a workpiece located in the compression mold including a mold cavity and a mold closure movable relative to the workpiece. The apparatus may include at least one touch sensor pad positionable to signal touch between the mold closure and the workpiece. The touch sensor pad may be in communication with a touch sensor monitor for indicating touch between the workpiece and the mold closure. The touch sensor pad may also be embodied in a touch sensor assembly.
REFERENCES:
patent: 4307050 (1981-12-01), Greten
patent: 4502857 (1985-03-01), Hinks
patent: 4751029 (1988-06-01), Swanson
patent: 5043111 (1991-08-01), Hinzmann et al.
patent: 5174933 (1992-12-01), Toh et al.
patent: 5427516 (1995-06-01), Bader et al.
patent: 5528452 (1996-06-01), Ko
patent: 5670100 (1997-09-01), Ingram
patent: 5720988 (1998-02-01), Yoneda
patent: 5733486 (1998-03-01), Hayasi et al.
patent: 19517024 (1995-05-01), None
patent: 57046143 (1982-03-01), None
patent: 58219026 (1983-12-01), None
Upadhyay Ram Kumar
Woodmansee Donald Ernest
General Electric Company
Heitbrink Jill L.
Patnode Patrick K.
Stoner Douglas E.
LandOfFree
Touch sensing method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Touch sensing method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Touch sensing method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2442541