Plastic article or earthenware shaping or treating: apparatus – Segmented female mold and mold clamping means
Reexamination Certificate
1999-10-18
2001-11-27
Nguyen, Nam (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Segmented female mold and mold clamping means
C425S434000, C425S435000, C425S450100, C264S297600, C264S297800, C264S311000
Reexamination Certificate
active
06322348
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
Not applicable.
BACKGROUND OF THE INVENTION
This invention relates to rotational molding systems in which there are multiple mold halves that are repetitively opened and closed. More particularly, it relates to a system for automatically opening, closing, clamping, and unclamping such molds.
Various types of rotational molding systems are well known. For example, U.S. Pat. No. 5,306,564 and 5,529,481 describe mold systems where two or more pairs of mold halves can simultaneously be brought together to form mold cavities in which molded items are cast.
Meltable particulate (usually a plastic such as polyethylene) is placed inside each cavity, each mold is closed and placed in a furnace where it is heated (or the molds are otherwise heated), and each mold is rotated and sometimes also rocked.
The particulate melts and adheres to the internal surface of each cavity. After cooling, each mold is opened and the molded items are removed. This type of molding is particularly well suited for items that have large hollows in them (e.g. large plastic toys; plastic gasoline containers).
In high production facilities problems can arise in connection with the opening and closing of such molds. As taught in U.S. Pat. No. 5,529,481, a system is needed to hold the mold halves tightly together during the molding process. This is particularly important because of the range of movement of the molds during molding, and because if the mold halves are not tightly held together plastic can seep into the joint between mold halves, thereby creating unwanted flashing (and wasting plastic).
To achieve a tight joint the art had previously used various bolting systems. However, such bolting systems were labor intensive and time consuming to use. In some cases, workers experienced repetitive strain injuries due to the need for repetitive turning of bolts and/or nuts.
Moreover, if the bolts
uts were not evenly tightened there could be uneven wear at the mold joint and/or instances of seepage at the joint. While patents such as U.S. Pat. No. 5,306,564 disclosed a system to reduce the number of bolts required, that system still required some bolts. Even with that system there was some concern regarding achieving even clamping pressure on opposite sides of the molds, and when comparing one mold pair to another.
In U.S. Pat. No. 5,869,109 a system was provided to simultaneously clamp and unclamp a pair of molds. While this system was a significant improvement, it still required manual clamping and locking of the molds.
It can therefore be seen that a need exists for an improved multi-mold closure system that reduces still further the manual operations of the molding process.
BRIEF SUMMARY OF THE INVENTION
In one aspect the invention provides a molding apparatus which includes a first support having spaced apart vertical posts and a first set of mold halves positioned between the vertical posts. There is also a second support having positioned thereon a second set of mold halves, and a clamp bar positioned on the vertical posts adjacent the second support extends across the mold halves of the second set of mold halves. A movable grip member secured to the first support is movable between an engage and disengage position, wherein in the engage position a clamp engages the grip member and the clamp bar so as to drive the respective sets of mold halves into sealing contact with each other. In the disengage position, the grip member is clear of the clamp.
The apparatus can include a spring that biases the movable grip member towards the either engage or disengage position. The grip member can include a vertical grip post having a recess therein for engaging a clamp, the grip post being slidable relative to the first support. The grip post can be slidably mounted to a base, the base being rigidly mounted to the first support.
In other aspects, the grip member can include a guide for guiding a member which slidably moves the vertical post. There can also be a clamp suitable to provide clamping pressure between the grip member and clamp bar where the clamp includes a tongue for engaging the grip member.
In still other aspects, the clamp can include a ram which urges the clamp bar towards the grip member, and the clamp includes a lift arm for lifting the second support. The clamp includes an actuator for locking and unlocking a clamp bar locking means.
In still other preferred forms, the clamp is mounted to a frame for horizontal and vertical movement, there is an actuating mechanism for slidably moving the grip member between the engage and disengage positions, and the grip member is interposed between the vertical posts.
In a different form the invention provides methods of molding parts using the above apparatus. In an automated manner, one can with the apparatus clamp the sets of mold halves together, mold parts in the mold halves, unclamp the mold halves, and then separate the mold halves.
It will be appreciated that the present invention provides a system which permits the clamping member to also serve as a lifting member for lifting the mold halves apart. Still other objects and advantages of the present invention will become apparent from examination of the preferred embodiment and claims which follow.
REFERENCES:
patent: 2298507 (1942-10-01), Kelm
patent: 3293698 (1966-12-01), Bavers
patent: 3546747 (1970-12-01), Stefaniak et al.
patent: 3611506 (1971-10-01), Schroeder
patent: 3801255 (1974-04-01), Meyer et al.
patent: 4043737 (1977-08-01), Greenberg
patent: 4350481 (1982-09-01), Corea et al.
patent: 4472127 (1984-09-01), Cyriax et al.
patent: 4473346 (1984-09-01), Hehl
patent: 4832590 (1989-05-01), Bellmer
patent: 4929166 (1990-05-01), DiSimone et al.
patent: 5094608 (1992-03-01), Piazza et al.
patent: 5277861 (1994-01-01), Zilbert
patent: 5306564 (1994-04-01), Guzikowski
patent: 5529481 (1996-06-01), Guzikowski
patent: 5869109 (1999-02-01), Guzikowski
Heckenberg Donald
Nguyen Nam
Norstar Aluminum Molds, Inc.
Quarles & Brady LLP
LandOfFree
Rotational mold automated clamping system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Rotational mold automated clamping system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rotational mold automated clamping system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2577079