The disclosed subject matter is directed to a mold and a core element, associated with an injection molding process, and in particular the disclosed subject matter is directed to a dynamic core system, for use in injection molding of articles having a distinct undercut. The disclosed subject matter further pertains to articles having a distinct undercut.
A collapsible core for molding parts is known in the art and is described for example in US2006/0188602, US2009/01152770. US2006/0188602 discloses a two sleeve collapsible core. US2009/01152770 addresses a collapsible core for injection molding of hollow articles that have an internal undercut near opening.
The disclosed subject provides for a dynamic core system for use in molding, e.g. injection molding, and is configured for molding hollow articles having a width of its opening substantially narrower than the articles' largest width extending between the opposite sides of the articles inner surface. The disclosed subject matter is further directed to a mold comprising the dynamic core system. In accordance with the disclosed subject matter, there is further disclosed an injection molded unitary article having a distinct internal undercut.
In accordance with the disclosed subject matter, the core system is assembled of a plurality of co-operable components that function together and are manipulable between a first molding position at which the core is fully deployed and a second position in which the core system is configured to axially retract and radially contract into a second, drawing position. The second drawing position facilitates removal of the injection molded article from the mold in accordance with the disclosed subject matter.
The system in accordance with the disclosed subject matter comprises an axially displaceable core pin and at least one of at least radially displaceable core segments extending around the central core, the outer shape of core system being substantially complementary to the inner shape of the molded article. In accordance with an embodiment of the disclosed subject matter, the system comprises a plurality of core segments. The geometry of the outer shape can vary from a sphere, ellipsoid etc. to any polygonal shape such as a cuboid or more complex shapes having its largest diameter, i.e. the longest distance between two opposite walls defining the inner surface hollow space, substantially wider/longer than that of the opening of the article, e.g. a spherical zone having at least one base such as a ¾ of a sphere or a sector of a sphere.
The core pin in accordance with an embodiment can be a cylinder having a substantially constant radius along its length, between its cap and base. In accordance with the disclosed subject matter, the core pin is at least partially retractable from the core system in a first axial direction, parallel to the central axis of the core system. In accordance with a specific embodiment, the core pin is fully retractable from the core system, such that upon its axial retraction thereof, volumetric space occupied thereby remains void.
The term “volumetric space” as defined herein refers to the space bounded by the outer perimeter of the core pin. The circumference of the volumetric space substantially corresponds in its dimensions to the outer circumferential shape of the core pin. In accordance with an embodiment, the core pin can have a circular cross section e.g. its volumetric space is that of an inscribing cylinder of the core in case of a substantially cylindrical shape and in a cross section it is the circumcircle which passes through all the vertices of the core pin. In accordance with an embodiment of the disclosed subject matter the radius of the circumcircle remaining substantially constant along the height of the core pin, such that the radius of the cylinder circumferencing (circum-cylinder) the core pin has a substantially constant diameter. Alternatively, the core pin can have any polygonal shape and the volumetric space defined thereby will be that defined by its general circumference.
In accordance with an embodiment of the disclosed subject matter, two or more of at least radially displaceable core segments extending around the central core comprise at least one group of dynamic segment member(s) configured for radial displacement towards the central axis of the core system. In accordance with the disclosed subject matter, the number of groups can vary from 1 to n as long as the total volumetric space of at least n minus 1 group when radially displaced towards the central axis of the core system does not exceed the volumetric space of the core pin, e.g. the space defined by its outer perimeter, when axially retracted. Each group can comprise any number of segments, as long as the above special relationship is maintained. It will be appreciated that the larger the ratio of diameter of the core pin to the largest diameter of the core system, the larger is the number of groups of dynamic segments that can be received within the space.
In accordance with an embodiment of the disclosed subject matter, at least one of the groups of the dynamic segment members can be further axially displaced in a direction opposite the axial direction of the core pin translation in the first axial direction.
In accordance with a specific embodiment of the disclosed subject matter, the core segments comprise a first group of dynamic segment members and a second group of dynamic segment members, all substantially circumferentially extending around the core pin. The outer surface of the core system, substantially conforming to the inner surface of the hollow article cavity. In accordance with this example, the first group of segment members are configured for radially translating in a direction towards the central axis of the core system, while the second group of dynamic segment members is configured for radially translating in a direction towards the central axis of the core system and further to axially translate in a direction opposite the direction of the retraction of the core pin. In accordance with an embodiment of the disclosed subject matter, the radial translation towards the axis and the axial translation of the second group can be performed substantially concurrently, i.e. in a combined motion. The movements of both groups can be provided concurrently, however the first group will be moved faster than the second group.
The number of groups of segment members can be more than one, as indicated hereinabove. In accordance with an embodiment of the disclosed subject matter the larger the number of segment members and/or groups comprising these, the smaller the diameter of the opening of the article that can be formed using the system of the disclosed subject matter. This is due to the design of the core system, e.g. the pin and the core segments that are such that, when the pin is retracted in a first direction along a central axis of the core system and the core pin, the core segments remain stationary relative to the translation of the core pin, the core pin is fully retracted, leaving the space occupied thereby void. The first group of secondary segments is allowed to radially translate in a direction towards the central axis. In accordance with the disclosed subject matter, the group can comprise any number of members from 1 to m, however, the total space occupied by segment(s) does not substantially exceed the volumetric space previously occupied by the core pin.
The second group of dynamic segment members in accordance with the disclosed subject matter radially moves generally in the direction of the central axis and concurrently translates axially in the second direction opposite to the first axial direction of the core pin, to extend substantially above the first group of the dynamic segment members. Thus allowing the article to be removed from the mold.
In accordance with one embodiment of the disclosed subject matter, the core pin and the core segments, form together a sphere segment having one base (e.g. ¾ of a sphere). In accordance with an embodiment, the core pin is cylindrical and the secondary core segments are segments of a spherical ring, such that the central axis of the core and the sphere coincide. The core pin can be configured with a spherical end at its cap portion and have a substantially constant radius along the majority of its length. The core segments extend circumferentially around the core.
In operation of the core system, the core pin is retracted in a first axial direction along a central axis of the core pin, the core segments remain stationary relative to the translation of the core pin, the core pin is substantially fully retracted, leaving the space occupied thereby void. The core segments are then allowed to radially translate in a direction toward the central axis of the void space, such that at least some of the dynamic segment members are translated into the void space. This radial translation facilitates contraction of the core system, and thus removal of the molded article. In accordance with an embodiment of the disclosed subject matter, the at least one of the core segments is translated radially towards the central axis of the void space and further translated axially in a direction opposite the first direction. This radial and axial translations can be performed simultaneously or sequentially (e.g. inward and lengthwise movement), e.g. radial contraction of the core system followed by an axial translation of the second group.
In operation, this allows removing the injection molded hollow article away from the mold and removing it from the molding core system. The result of the radial contraction is that the largest diameter of the core assembly of the invention is substantially shrunk and collapsed and the article can be easily removed therefrom.
The number of alternately extending segment members in each group can be more than two.
The core pin radius may vary, such that the core pin has taper or uneven sidewalls. The core pin cap can have any desired geometry to conform to the desired shape of the article. In accordance with one example, the cap is rounded to conform to the semi spherical shape of the core system. In accordance with another example, the cap can have a flat end. The surface of the cap or the segments can be provided with corrugations, e.g. to form aesthetic effects of the final article.
The sidewalls of the core pin can be substantially smooth or can alternatively comprise grooves thereon to engage with components of the system, e.g. the secondary core segments, the retraction mechanism, etc.
The device also includes a base member having a plurality of engaging members, such as grooves, for engaging at least some of the core segments.
The core segments can each have an engaging member, such as a rail or a protrusion, that engages with a respective engaging member of the base member. The engaging members of the core segments and the engaging members of the base member are configured to allow the core segment members to translate both radially and axially.
In accordance with another embodiment of the disclosed subject matter there is provided an injection mold comprising a segmented mold base having a mold cavity corresponding to an outer shape of at least part of the molded article and a mold cover having a cavity corresponding to the remainder of the outer shape of the article. The segmented mold base comprises radially slidable mold segments. The mold further comprises a core system in accordance with the disclosed subject matter, comprising a plurality of co-operable components manipulable between a first molding position at which the core system is fully deployed and a second position in which the core system is configured to progressively axially retract and radially contract into a second retracted position, the outer shape of core system being substantially complementary to the inner shape of the molded article.
An injection mold in accordance with an embodiment of the disclosed subject matter comprising a segmented mold base having a mold cavity corresponding to an outer shape of at least part of the molded article and a mold cover having a cavity corresponding to the remainder of the outer shape of the article, the segmented mold base comprising radially slidable mold segments. The mold further comprising a core system comprising an axially displaceable core pin and a plurality of at least radially displaceable core segments extending around the core pin, the outer shape of core system being substantially complementary to the inner shape of the molded article.
In accordance with an embodiment of the disclosed subject matter the injection mold being operable in a first, injecting position, in which the core system is in a fully deployed configuration and the mold sliding segments form together a continuous inner surface of the mold cavity and a second position, in which the mold sliding segments are radially displaced and spaced apart and the core system is configured to progressively axially retract and radially contract into a second retracted position.
In accordance with yet an aspect of the disclosed subject matter, there is disclosed a method of injection molding a substantially hollow article having at least one opening substantially narrower than the articles largest width, comprising:
providing a mold comprising a mold base, a mold cover, wherein the cavity extending within the mold base and the cover correspond to the outer surface of the article and a dynamic core system having a central longitudinal axis extending therethrough, the core system comprising at least an axially displacable core pin and at least one radially displaceable core segment, wherein the outer surface of the core system corresponds to the inner surface of the article;
injecting a molten material into the mold wherein the core system is at its first operable position in which the core system is in a fully deployed position, where the mold cover is covering the mold base with the core system extending therebetween, such that the outer surface of the core system substantially corresponds to the inner surface of the hollow article and wherein mold cavity is defined by circumferentially extending mold cavity on the mold base and the mold cover;
releasing the mold cover from the mold base;
translating the core system into a second position, in which the core system is configured to axially retract and radially contract into a second drawing position; and
removing the article from the mold.
In accordance with an embodiment, in the second position, the core pin is axially displaced substantially retracting from the hollow cavity of the article and at least one of the at least one core segments is radially displaced towards the central axis.
This general description has been provided so that the nature of the disclosed subject matter can be generally understood without being limited to a specific example. A more complete understanding of the invention can be obtained by reference to the following detailed description of the examples thereof in connection with the attached drawings.
In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:
Attention is first directed to
The mold base 220 comprises a top portion 240 (best seen in
The central portion of the base mold 220 comprises a dynamic core system 260 comprising a core pin 280 and a plurality of core segments 270 (only two seen in cross section of
The core pin 280 is supported by a longitudinally extending support member 285, further configured for axial displacement of the core pin. The core pin 280 is further provided with lateral grooves 282 extending on its surface (best seen in
The core segments 270 are at least radially displaceable and in the present example comprise two groups of alternating segments, each group comprising four segments, best seen in
The bottom portion of the mold base, comprises circumferentially extending support sliders 290A and 290B (in the current example two, although any other configuration of such slides can be utilized provided they perform similar function). The support slides are configured for extending under at least a portion of the core pin 280, preventing unintentional displacement thereof, and are further configured to be slidably displaced along the arrow “b” to allow the core pin 280 to axially retract via the support member 285 towards the bottom portion 250 of the mold base. The axial direction of retraction is parallel with the central axis X.
In operation, the molten material, e.g. plastic, is injected into the mold through the port 232 (in accordance with the invention the number of ports can vary) with the mold in a first operable position as seen in
While the disclosed subject matter, and in particular the core system have been discussed and illustrated with respect to injection molding, and many details thereof have been presented for the purposes of illustration, it will be apparent to those skilled in the art that the disclosed subject matter is susceptible to additional variations and certain details described can vary without departing from the basic principles of the disclosed subject matter. It will also be appreciated by those skilled in the art, that the dynamic core system can be used not only with injection molding, but also with die casting, blow molding, rotor molding and other similar molding processes, requiring the molded material to take shape within a mold and around a mold/core. The mold and the core system can be conformed to the process, mutatis mutandis, without departing from the principles of the disclosed subject matter.
Number | Date | Country | |
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62043438 | Aug 2014 | US |
Number | Date | Country | |
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Parent | 15507311 | Feb 2017 | US |
Child | 16878770 | US |