Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – Shaping against forming surface
Reexamination Certificate
2001-11-20
2004-07-27
Heitbrink, Jill L. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
Shaping against forming surface
C425S556000, C425S444000, C425SDIG005
Reexamination Certificate
active
06767497
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed generally to molds for use in injection molding machines and to related apparatus used in conjunction with the molds to process articles produced in the molds. The invention pertains to the operation of elements for causing relative movement of some portions of the molds with respect to other portions, particularly in conjunction with the motion of the related molded article processing apparatus. The present invention is more particularly related to such apparatus for use in three portion molds consisting essentially of a mold cavity assembly, a mold core assembly and an intermediate assembly including space surface defining elements that cooperate with the mold core and cavity assemblies to define the space in which articles are molded of plastic, the apparatus regulating the movement of the space surface defining elements during movement of the intermediate assembly relative to the other portions of the mold and relative to the related molded article processing apparatus. The invention has particular utility in a molding operation in which the related molded article processing apparatus comprises a molded article receiver unit designed to enter into an interval or opening between the mold cavity assembly and the other mold assemblies subsequent to formation of the molded article. Of particular interest is the controlled positioning and/or timing of release of the molded article from the intermediate assembly into the molded article receiver unit.
Brun, Jr., et al., U.S. Pat. No. 5,531,588 discloses an adjustable cam track for a mold having a mold cavity assembly, a mold core assembly that is movable relative to the mold cavity assembly, and a stripper assembly movably interposed between the mold core and cavity assemblies. The stripper assembly has at least one pair of space defining surfaces that together with the mold cavity and core assemblies, defines at least one space for receiving plastic material injected therein to form at least one molded article. The mold core assembly and the stripper assembly can be moved away as a coupled pair from the mold cavity assembly to remove the at least one molded article from the mold cavity assembly. The mold core assembly and the stripper assembly are then separated to remove the at least one molded article from the mold core assembly. The adjustable cam track of Brun, Jr., et al., includes a guide fixed to the stripper assembly. A cam follower is coupled to the space defining surfaces of the stripper assembly platen and is engaged in the adjustable cam track so that movement of the cam follower causes movement of each pair of space defining surfaces relative to each other to release the molded article from the molding machine. The adjustable a cam track also includes a cam insert that is adjustably positionable with respect to the guide to adjust the point of release of the molded article. The cam insert includes a first toothed rack, and a second toothed rack removably fixed to the guide and engaging the first toothed rack to fix the position of the cam insert relative to the guide only at certain preselected locations.
The previously described adjustable cam track of Brun, Jr., et al., has been used in the manufacture of parisons for containers at rates that required special handling of the parisons upon their removal from the mold core assembly. This special handling was accomplished with a molded article receiver assembly that was movable into the interval between the mold cavity assembly and the mold core assembly when the mold was in an open position such as that disclosed in Delfer III, U.S. Pat. No. 4,721,452. Ideally, the position of the molded article receiver assembly was such that movement of the stripper assembly relative to the mold core assembly inserted the parisons into the molded article receiver assembly. This was followed immediately by the release of the parisons by the pair of space defining surfaces, which only occurred when the parisons were properly located in the molded article receiver assembly. However, as a practical matter, even slight misalignment between the mold core assembly and the molded article receiver assembly caused one or more of the parisons to be significantly damaged as they were inserted into the molded article receiver assembly. Furthermore, since release of the parisons was related only to the relative position of the stripper assembly relative to the mold core assembly, is was also necessary to accurately position the molded article receiver assembly and coordinate the timing of such positioning so that as little damage as possible occurred. While substantial efforts were focused on insuring the proper alignment between the mold core assembly and the molded article receiver assembly during the movement of the stripper assembly, this did not always accomplish the desired end.
In co-pending U.S. application Ser. No. 09/726,743, filed Nov. 30, 2000 and assigned to the same assignee, an adjustable cam track is disclosed that includes a guide coupled to a mold core assembly, the guide defining a first portion of the adjustable cam track. A cam follower is engaged in the cam track and is coupled to the space defining surfaces carried by the stripper assembly for causing relative movement of each pair of space defining surfaces as the stripper assembly moves relative to the mold core assembly. The cam follower is engaged in the first portion of the cam track when the mold portions are in the closed position. The first portion of the cam track also includes a ramp to an intermediate portion defining the prerelease position of each pair of space defining surfaces so that the molded article is loosely retained by the space defining surfaces. This loose retention accommodates for any small amount of misalignment between the molded article receiver assembly during the transfer of the molded articles from the stripper assembly to the molded article receiver assembly. The adjustable cam track of the co-pending application also includes a cam insert defining a second portion of the adjustable cam track. The path defined by the cam insert is generally a matter of choice of design except that it defines the point of release of the molded article from the space defining surfaces. The cam insert is adjustably positionable with respect to the guide to adjust the point of release with respect to the ramp defining the onset of prerelease, thereby permitting the adaptation of the cam track to molded articles of a variety of sizes. However this adjustment of position of the cam insert is one made to generally coordinate the position of the release, but is not responsive to the timing of the achievement of the specified position by the molded article receiver apparatus.
It is therefore desirable that each pair of space defining surfaces of the stripper assembly be allowed to separate slightly, but not entirely, from the molded articles so that the molded articles are only loosely retained in a prerelease position. This prerelease position allows some play in the position of the molded articles relative to the stripper assembly thus permitting some variation in position of the molded article receiver assembly at the time of introduction of the molded articles. Due to the variation in length of the molded articles, it is also desirable to modify or adjust the position of product release from the stripper assembly in relation to the position of onset of the prerelease position. It is also desirable for the product release from the stripper assembly to occur in response to an indication of the attainment of a specified position by the molded article receiver assembly.
SUMMARY OF THE INVENTION
Accordingly, an article molding assembly of the present invention includes a mold and a release mechanism for releasing molded articles from the mold. The mold includes a first mold portion, a second mold portion that is movable with respect to the first mold portion, and a third mold portion. The third mold portion is movably interposed between the first and sec
Knepper Carl L
Meiring David P.
Brinks Hofer Gilson & Lione
Heitbrink Jill L.
Wentworth Mold, Inc., Electra Form Industries Division
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