Patent Application
20050067128
Not Applicable.
Not Applicable.
Not Applicable.
1. Field of Invention
This invention relates to a system and method for increasing production efficiency and protecting injection molds.
2. Prior Art
Articles molded in an injection mold may not eject from the mold's first ejection sequence. The inherent characteristics of the material being molded, the geometry of the article, or molding imperfections, such as flash, often cause an unsuccessful first ejection sequence. Portions of molded articles may remain in the mold after the first ejection sequence due to a failure in the ejection system, breakage of the molded article, or insufficient material being supplied to the mold cavity. If the molded articles, or portions thereof, are not properly ejected from the mold prior to the mold closing, mold damage can occur or subsequent molded articles may be defective. If multiple ejection sequences are performed to ensure that articles, or portions thereof, have ejected prior to mold closing, production efficiency is compromised.
Article-sensing vision systems and radiation emitting and receiving article sensors are currently utilized to protect injection molds, but these devices simply prevent the mold from initiating its next cycle and typically require operator intervention to correct the problem. If the time for the operator to react to the identified problem is significant, the material in the machine's barrel can degrade, requiring additional time and expense for the material to be purged. Molding machines are often equipped with a low-pressure mold protection feature, closing the mold at a lower pressure in an attempt to detect any resistance at mold closing due to an unwanted article in the mold. Low-pressure mold protection does not protect the mold when the low pressure is enough to damage the mold, or when improper ejection occurs often. To help reduce the potential for mold damage and reduce operator intervention, it is common to increase the amount of ejection sequences during the molding cycle, decreasing production efficiency. Increasing production efficiency, protecting the mold, increasing part quality, and reducing operator requirements are important since these directly relate to the cost of the molded articles and the competitiveness of the molder.
3. Objects and Advantages
Accordingly, several objects and advantages of my invention are:
Further objects and advantages of my invention will become apparent from a consideration of the drawings and ensuing description.
This invention provides a method of performing ejection sequences in an injection mold on demand, increasing production efficiency and protecting the mold.
Operation—
When the article-detection devices, such as the article-sensing vision system 14 or radiation emitting and receiving article sensors 16,18,20, detect a molded article, or portion of an article 30, the article-detection controller 24 is alerted of the condition. The article-detection controller 24 enables the molding machine controller 26 to perform an additional ejection sequence on the mold ejector system 22. The mold ejector system 22 can encompass all methods of ejection known to the ordinarily skilled artisan such as, and not limited to, mechanical ejection and pneumatic ejection. If the molded article, or portion thereof 30, is not detected by the article-detection devices after the second ejection, the mold is allowed to close and start its next cycle. If the molded article, or portion thereof 30, is detected by the article-detection devices after the second ejection, subsequent ejection sequences and inspections are performed to self-correct the problem. After exhausting the predetermined number of ejection sequences, the molding machine controller 26 will signal for alternative intervention.
From the description above, a number of advantages of the system become evident:
These advantages enable a higher production efficiency, lower labor cost, and better preservation of the mold than with existing methods.
Although the description above contains many specifics, these should not be construed as limiting the scope of the invention, but as merely providing illustrations of some of the presently preferred embodiments of this invention. For example, the article-detection controller and molding machine controller can be one and the same, wireless communications can be utilized to communicate between the devices, etc. The scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.
