Plastic article or earthenware shaping or treating: apparatus – With apparatus assembly or dismantling means or with idle part – For press shaping surface
Reexamination Certificate
1998-12-15
2001-02-13
Pyon, Harold (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
With apparatus assembly or dismantling means or with idle part
For press shaping surface
C425S330000, C425S451200, C425S468000
Reexamination Certificate
active
06186763
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to a threaded actuator for positioning a structure subjected to intense loads and forces, and particularly a motor driven extendible member positioned to receive and support an intense load.
In various systems, an extendible member is accurately located between a rest position and an operative position. In the operative position, an intense force and load may be placed on the member. A typical application developed by the assignee of the present invention relates to injection mold and die casting systems in which a core of a mold body is positioned between an opened and closed position. For example, in a side-action system for molding and casting apparatus, one or more cores are slidably mounted with respect to each other within the mold body to open and close the mold. Each movable core is similarly mounted within a slide cavity and coupled to a threaded actuator secured to the mold base. The threaded actuator includes an hydraulic cylinder unit including a threaded nose or portion from which the piston rod extends. The core slide is secured to the end of the rod and slidably mounted within the mold body. The threaded nose of the cylinder is positioned within a threaded flange secured to the base for accurate positioning of the cylinder and thereby the rod, slide and core with respect to its position by full or near extension of the cylinder unit. The cylinder unit is specially constructed with a high force locking system between the rod and cylinder such that with the core appropriately located, the core is held in place with an intense force often greater than the cylinder motive force and under a pre-loaded condition as a result of interconnection between the core slide and the mold body. Thus, the system is arranged with internal mating parts which develop a very large mechanical advantage in establishing high preload forces where desired or necessary.
The above system has been found to establish high quality parts having essentially zero flash and with minimal wear and maintenance costs in the side-action positioning to produce a highly cost effective system for molding and die casting when compared to other available system using toggle linkages, cam pins, heel blocks or other means for positioning of the cores. The system operation is dependent upon the accurate positioning of the threaded actuator and also in establishing high preloading on the supporting rod structure. Thus, although very rigid members are used for supporting of a core and in the core as such, it cannot be assumed under all conditions and particularly large intense forces, that even the large preload does not positively insure against some compression of the supporting structure during a molding cycle in the presence of the intense loading.
Although the threaded actuator has been operated very successfully in side action molding and die casting apparatus, accurate set up is required to establish the desired initial positioning of the threaded actuator as well as establishing and maintaining the desired preload on the slide system for each particular molding sequence or part formation. Recognizing that both of these factors are of significance in providing optimal constructions, continuous consideration for desired improvement in the positioning system is desirable in maintaining the high quality in the side-action systems.
The same desire for accurate positioning of motor-driven threaded actuators may of course arise in other applications and the present invention with its improvements can be readily applied to other motor-driven applications. The above described system includes a hydraulic cylinder as the motor means. In molds or other systems, motors may be used such as pneumatic, electric and mechanical motor devices including an extendible work member and a threaded connecting portion for positioning of the work member.
SUMMARY OF THE PRESENT INVENTION
The present invention is particularly directed to a motor-driven threaded actuator and particularly to the mounting of the threaded actuator within a threaded support structure and more particularly in a mold system the mounting of a threaded cylinder or other motor unit to the support structure in a high pressure mold apparatus.
In accordance with the present invention, a threaded portion of a motor is connected to a support structure using a special differential thread assembly permitting the final positioning thereof without rotation of the motor. Generally, in accordance with the present invention, the threaded motor and threaded support structure include radially spaced threaded portions, with the motor threaded portion and the support threaded portion having different threads. A connecting threaded member is threaded into the assembly with threads corresponding with inner and outer threads corresponding to the threads of the motor and the threads of the support structure respectfully to form a differential threaded connection. The differential threaded connection may include a pitch difference, a handedness difference or a combination thereof. In assembly, the actuator can be initially mounted and threaded into the threaded connecting member. After the initial positioning of the assembly, turning of the differential connecting member provides fine adjustment of the motor assembly relative to the support structure. A securing device is preferably provided to lock the assembly in the set position, such as a jam member threaded onto the motor and engaging the support structure, to maintain the final adjusted position.
The differential threaded connection permits a very fine adjustment as the rotation of the connecting member will of course provide an axial shift of the motor unit equal to the difference between the motor thread connection and the support thread connection.
In a side action mold system which includes a threaded hydraulic cylinder unit, the very accurate positioning of the cylinder unit permits a precise final movement of the motor unit. In the mold system, it is used for accurate location of the interconnected core, with the same positioning of the core during successive formation of like parts.
In an optimal construction, the connecting threaded member is formed of a sufficient length to allow the member to shift with the cylinder unit while maintaining operative engagement with the support structure. A securing device threaded onto the cylinder and abutting the structure is constructed to permit such necessary desired movement of the connecting threaded member during the inner and outward positioning of the cylinder unit. The differential thread arrangement eliminates any problems which can arise in some applications of threaded actuators by permitting a standard hydraulic cylinder unit maintained in an appropriate desired location prior to final adjustment. Thus, the connection is not subjected to any rotating forces and at most requires simple linear displacement which can normally be readily established without rotational displacement of the several mechanical, hydraulic and/or electrical connections or the like to the threaded actuator. This feature of course is not present with prior mounting of the cylinder unit.
In this application, designing of the respective thread sets in an opposite handedness allow the reverse movement at any given particular rotation of the control adjustment element. The direction of the threads can also be mixed. For example, if one thread is righthanded and the other left-handed, the result would be an addition to a pitch differential movement. The use of opposite handed threads thus provides an increased differential movement relative to the use of simple different thread pitches in the inner and outer threaded connector of the adjustment assembly. Adjusting the range of control to be built into the structure by using a simple pitch differential and/or pitch adder/subtractor would be possible with the use of a single threaded value. In this aspect, the movement for any given rotation of the connecting threaded element can be designe
Andrus Sceales, Starke & Sawall
Luk Emmanuel S.
PFA Incorporated
Pyon Harold
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