Plastic article or earthenware shaping or treating: apparatus – Female mold and charger to supply fluent stock under... – With means between charger and mold to cut off flow of...
Reexamination Certificate
2002-05-15
2004-04-20
Heitbrink, Tim (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Female mold and charger to supply fluent stock under...
With means between charger and mold to cut off flow of...
C425S566000, C425SDIG005
Reexamination Certificate
active
06722874
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention concerns a control and regulating device for a needle element of a hot or cold channel of a plastic molding tool, wherein rotation of a drive device is converted by means of a converting device into an axial movement of the needle element
Such control and regulating devices are known for example from U.S. Pat. No. 5,078,589 or U.S. Pat. No. 5,238,378. The converting devices provided in those known control and regulating devices, for converting rotation of a drive device into an axial movement of the needle element, have a screw and nut element of constant pitch. That constant pitch of the screw and nut element determines the movements of the needle element of the hot or cold channel of the corresponding plastic molding tool.
Demands for up-to-date processing of injection-moldable plastic materials with their individual process-specific and physical criteria to provide the respective plastic moldings are not satisfied or are only inadequately satisfied or are only satisfied by virtue of a suitable compromise, in regard to fastest possible production cycles, dealing carefully with the injection molding materials, that is to say injection-moldable plastic materials, dealing carefully with the molding tools, an optimum injection molding process control, making use of motor-driven drive devices and reducing the level of wear of the respective needle element or the drive device with such screw and nut elements of constant pitch.
Admittedly, small or normal pitches of the screw and nut element involve a high force and a very substantial self-locking action when pressure is applied or in terms of needle locking, as well as fine adjustability, but they suffer from the disadvantage that the respective no-load or idle stroke of the needle element is highly time-intensive and that possible process regulation can be effected only very sluggishly, that is to say involving a great deal of time. That time penalty puts a load on the operating cycle and increases costs in the above-mentioned idle stroke range for example for opening the needle element for the fastest possible quantitative through-flow of the plastic material, as for example hot channel needle elements can have a needle stroke of between 8 and 16 mm or more. Consequently, when the screw and nut element involve small pitches, reactive oscillation as rapidly as possible is not adequately afforded for process regulation purposes so that the efficiency of the regulating device which usually involves an electronic regulating device is not put to use or is not completely put to use. The respectively desired level of quality of production of the respective plastic pars can consequently not be kept stable or stabilised.
Admittedly, a fast movement of the needle element in the idle stroke range can be implemented with a greater or high pitch for the screw and nut clement of the converting device of known control and regulating devices for a needle clement of a hot or cold channel of a plastic molding tool, but during the process control phase the needle element becomes over-active, whereby necessary fine actuation becomes more difficult. In addition such an increased or high pitch results in an increased need for counter-holding force, which means that the expenditure in terms of energy and power is correspondingly increased. A further deficiency of such an increased or large pitch is that so-called spot-wise grinding-in of the needle element as a closure element of the runner region to the mold cavity causes considerable tool wear and is relatively force-less as the self-locking action of the needle element is at least greatly reduced as a consequence of the increased or great pitch of the screw and nut elements.
DE 196 11 880 A1 discloses an injection molding tool with a plurality of hot channel needle closure nozzles which are connected to an actuating device for the simultaneous actuation of a plurality of needle That known injection molding tool has a mechanical drive transmission between a stroke drive and needle carrier elements arranged at the individual needles. Elastic intermediate elements are provided between the needle carrier elements and the respective needle. Transversely with respect to the longitudinal extent of the needles, it is possible to provide a slider connected to the stroke drive, as the rigid mechanical drive transmission. The elastic intermediate elements used can be compression springs which are preferably in the form of diaphragm springs. The slider and/or the needle carrier elements can have inclined guides for converting the slider stroke movement into the working movement of the needles, which working movement is transverse with respect to the slider movement
The object of the invention is to provide a control and regulating device of the kind set forth in the opening part of this specification, in which the opening and closing times of the needle element are reduced, but at the same time fine control is possible.
SUMMARY OF THE INVENTION
The foregoing object is achieved by providing a converting device which has at least one slide path and a feeler or follower element which is guided on the slide path, wherein the at least one slide path is provided on a slide path surface which is concentric with respect to the center line of the needle element.
In consideration of those factors, the object of the invention is to provide a control and regulating device of the kind set forth in the opening part of this specification, which so-to-speak combines together the advantages of a low and a high pitch and eliminates the disadvantages thereof.
In a control and regulating device of the kind set forth in the opening part of this specification, in accordance with the invention that object is attained in that the converting device has at least one slide path and a feeler or follower element which is guided on the slide path, wherein the at least one slide path is provided on a slide path surface which is concentric with respect to the center line of the needle element.
The at least one slide path can be of optimum design in a simple manner and can be individually configured as desired in order to permit the desired axial movement of the needle element, that is to say as desired a rapid idle stroke movement and a process regulation and deceleration movement of the needle element, which is slow in comparison therewith. The needle element may involve a needle element of a full cross-section, a hollow needle combined with such a needle element, for example of a compression needle unit, or the like. Such needle elements or control and regulating devices for a hot or cold channel of a plastic molding tool are described in the present applicant's prior patent application Ser. No. 198 57 735. The control and regulating device according to the invention is suitable by way of example for all needle elements or molding tools described in said prior patent application.
The at least one slide path of the converting device of the control and regulating device according to the invention can in this case extend over an angle of 360 degrees of angle or more, around the center line of the needle element. It may be advantageous if two or more slide paths are provided distributed uniformly around the center line of the needle element in order, with a rotation of the drive device through a small angle, to produce the desired axial displacement of the needle element. That small rotary angle is dependent on the number of slide paths, that is to say inversely proportional to the number of slide paths. With two slide paths the rotary angle can be 180 degrees or less than 180 degrees. With three slide paths the rotary angle can be 120 degrees or slightly less. Implementation of the smallest possible rotary angle is also dependent on the diameter of the slide path surface for the slide paths. The greater that diameter is, the correspondingly greater can be the number of slide paths, that is to say the correspondingly smaller can be said rotary angle. A small rotary movement of the drive device af
Bachman & LaPointe P.C.
Heitbrink Tim
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