Patent Application
20130323349
An aspect generally relates to (but is not limited to) a mold-tool system including (but not limited to) a plate-actuator assembly coupled with a first movable-plate assembly and with a second movable-plate assembly, the plate-actuator assembly configured to move the first movable-plate assembly and the second movable-plate assembly in opposite directions between a valve-open position and a valve-closed position.
U.S. Pat. No. 7,086,852 discloses a stack injection molding apparatus has first and second arrays of valve gate injection nozzles and separate mechanisms for independently actuating the nozzles of each array. A separate reciprocating yoke plate engages the valve pins of each nozzle array, and is actuated by either one centrally located actuator or a pair of symmetrically located actuators.
The inventors have researched a problem associated with known molding systems that inadvertently manufacture bad-quality molded articles or parts. After much study, the inventors believe they have arrived at an understanding of the problem and its solution, which are stated below, and the inventors believe this understanding is not known to the public.
More and more, users of molding systems doing precision molding are calling for synchronous valve pin actuation for valve-gated hot runners. The valve pins move together as they are attached to a single plate that moves back and forth. Plate-actuated systems typically use hydraulics, pneumatics or electric motors to move the plate. As these systems become more accepted in the molding industry, molders are likely to move on to stack hot runners with plate actuated valve pins to increase molding-machine output. Using known plate actuation techniques, a stack hot runner with plate actuated valve pins may have an extremely large shut-height (which is a disadvantage).
According to one aspect, there is provided a mold-tool system (100), comprising: a first movable-plate assembly (102) being configured to attach with a first valve-stem assembly (202) of a first runner assembly (200); a second movable-plate assembly (104) being configured to attach with a second valve-stem assembly (204) of a second runner assembly (201); and a plate-actuator assembly (106) being coupled with the first movable-plate assembly (102) and with the second movable-plate assembly (104), the plate-actuator assembly (106) being configured to move the first movable-plate assembly (102) and the second movable-plate assembly (104) in opposite directions between a valve-open position and a valve-closed position.
Other aspects and features of the non-limiting embodiments will now become apparent to those skilled in the art upon review of the following detailed description of the non-limiting embodiments with the accompanying drawings.
The non-limiting embodiments will be more fully appreciated by reference to the following detailed description of the non-limiting embodiments when taken in conjunction with the accompanying drawings, in which:
The drawings are not necessarily to scale and may be illustrated by phantom lines, diagrammatic representations and fragmentary views. In certain instances, details not necessary for an understanding of the embodiments (and/or details that render other details difficult to perceive) may have been omitted.
The definition of the mold-tool system (100) is as follows: a system that may be positioned and/or may be used in an envelope defined by a platen system of the molding system, such as an injection-molding system for example. The platen system may include a stationary platen and a movable platen that is moveable relative to the stationary platen. Examples of the mold-tool system (100) may include (and is not limited to): a runner system, such as a hot runner system or a cold runner system, a runner nozzle, a manifold system, and/or any sub-assembly or part thereof, etc.
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By way of example, the first runner assembly (200) may include (and is not limited to) a first nozzle assembly (502) that is connected with a first manifold-plate assembly (506). The first manifold-plate assembly (506) may include a first manifold assembly (510) that defines a first melt channel (511) that is used for distributing a resin (melt) to the first nozzle assembly (502). The first nozzle assembly (502) then conveys the resin to a mold assembly (known and not depicted). The first manifold-plate assembly (506) may also include a first backing plate (514), which may be used with the first manifold-plate assembly (506) to house and support the first manifold assembly (510). A first insulator (515) may be positioned between the first backing plate (514) and the first manifold assembly (510).
By way of example, the second runner assembly (201) may include (and is not limited to) a second nozzle assembly (504) that is connected with a second manifold-plate assembly (508). The second manifold-plate assembly (508) may include a second manifold assembly (512) that defines a second melt channel (513) that is used for distributing the resin to the second nozzle assembly (504). The second nozzle assembly (504) then conveys the resin to another mold assembly (known and not depicted). The second manifold-plate assembly (508) may also include a second backing plate (516), which may be used with the second manifold-plate assembly (508) to house and support the second manifold assembly (512). A second insulator (517) may be positioned between the second backing plate (516) and the second manifold assembly (512).
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By way of example, the gear assembly (150) may include (and is not limited to) a bi-directional ball screw assembly (300) connecting the first movable-plate assembly (102) with the second movable-plate assembly (104). The bi-directional ball screw assembly (300) may be configured such that along a first direction of rotation of the bi-directional ball screw assembly (300), the first movable-plate assembly (102) and the second movable-plate assembly (104) may move closer together; along a second direction of rotation of the bi-directional ball screw assembly (300), the first movable-plate assembly (102) and the second movable-plate assembly (104) may move further apart from each other. The bi-directional ball screw assembly (300) may be attached to each of the first movable-plate assembly (102) and the second movable-plate assembly (104). By way of another example, the gear assembly (150) may include (and is not limited to) the gear assembly (150) may include (and is not limited to) a rack-and-pinion-gear assembly (not depicted but known) connecting the first movable-plate assembly (102) with the second movable-plate assembly (104).
By way of further example, the first movable-plate assembly (102) may define a first shaft channel (602) that may be configured to receive the bi-directional ball screw assembly (300). The first shaft channel (602) may define a first threaded channel (610) that may interact with the bi-directional ball screw assembly (300). In addition, the second movable-plate assembly (104) may define a second shaft channel (604) that may be configured to receive the bi-directional ball screw assembly (300). The second shaft channel (604) may define a second threaded channel (612) that may be configured to interact with the bi-directional ball screw assembly (300). The plate-actuator assembly (106) may include a rotatable shaft (301) of the bi-directional ball screw assembly (300), and the rotatable shaft (301) may be received in the first shaft channel (602) and the second shaft channel (604).
For
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It will be appreciated that the bladder assembly (402) may be used with another equivalent structure other that the spring assembly (400), so long as the first valve-stem assembly (202) and the second valve-stem assembly (204) are returned to the valve-open position upon deflation of the bladder assembly (402). For example the another equivalent structure may be configured to include an electrically-driven actuator that may be configured to push on each side (such as a nozzle side) of each of the first movable-plate assembly (102) and the second movable-plate assembly (104). For example, another bladder (not depicted) may be used to push the first movable-plate assembly (102) and the second movable-plate assembly (104) apart (to the valve-closed position), and then separate bladders may be used to push each plate to the valve-open position, etc.
For the case where the spring assembly (400) is used as depicted, the bladder assembly (402) may be configured to inflate, abut, move and then maintain the first movable-plate assembly (102) and the second movable-plate assembly (104) in the valve-closed position while overcoming the spring assembly (400). In addition, the bladder assembly (402) may be also configured to deflate so as to permit the spring assembly (400) to move the first movable-plate assembly (102) and the second movable-plate assembly (104) back to the valve-open position. For the case where the gear assembly (150) includes the bladder assembly (402), the gear assembly (150) may further include (and is not limited to) the bi-directional ball screw assembly (300) connecting the first movable-plate assembly (102) with the second movable-plate assembly (104). For the case where the gear assembly (150) includes the bladder assembly (402), the gear assembly (150) may further include (and is not limited to) a rack-and-pinion-gear assembly (not depicted but known) connecting the first movable-plate assembly (102) with the second movable-plate assembly (104).
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One purpose of the mold-tool system (100) may be to provide an actuation system that may enable stack hot runner systems with plate actuated valve pins to be produced with smaller shut-heights relative to what is available today. Single face hot runners with plate actuated valve pins are currently available with pneumatic, hydraulic or electric actuation means. Known systems with pneumatic or hydraulic actuation typically use a number of piston assemblies that push or pull the first movable-plate assembly (102) and the second movable-plate assembly (104). These known piston assemblies consume significant amounts of space in the hot runner assembly. Systems using an electric motor to actuate the first movable-plate assembly (102) and the second movable-plate assembly (104) typically have belt, gear or ball screw drives that move the first movable-plate assembly (102) and the second movable-plate assembly (104) using some form of cam mechanisms. These known systems may also suffer from similarly large hot runner shut-heights. Placing two independently actuated systems back to back for a stack mold may result in a prohibitively large hot runner shut-height. The mold-tool system (100) provides or permits a smaller hot runner shut-height by combining the motion and actuation systems for the first movable-plate assembly (102) and the second movable-plate assembly (104) into a singular system.
The plate-actuation system for a single faced hot runner typically consists of a drive system, which moves the first movable-plate assembly (102) and the second movable-plate assembly (104), an alignment bearing system that ensures consistent movement and physical stops that define the stroke of the first movable-plate assembly (102) and the second movable-plate assembly (104) (valve pin open and close). The integration of this actuation system into a hot runner requires a significant amount of plate thickness to be added, which in turn increases the overall mold shut-height. For known stack hot runner using individual pneumatic pistons to actuate each valve pin, the standard course of action would essentially be to place two single face hot runners back to back (maintaining independent actuation for all valve pins). If the same principle were to be applied to a stack system with plate-actuated valve pins, that is placing two independent plate-actuation systems back to back, the result may likely increase the hot runner shut-height (disadvantage) so much so that the overall mold shut-height may be too large to fit in an available injection molding machine.
Combining some or all of the components of two back to back plate-actuation systems into one, may provide an opportunity to reduce the hot runner shut-height. For example, two back to back plates may be actuated (in opposite directions) using the same drive system, and/or the alignment bearing system may be shared between the first movable-plate assembly (102) and the second movable-plate assembly (104), and/or both the first movable-plate assembly (102) and the second movable-plate assembly (104) may share a physical stop that limits the stroke of each of the first movable-plate assembly (102) and the second movable-plate assembly (104).
It will be appreciated that the assemblies and modules described above may be connected with each other as may be required to perform desired functions and tasks that are within the scope of persons of skill in the art to make such combinations and permutations without having to describe each and every one of them in explicit terms. There is no particular assembly, components, or software code that is superior to any of the equivalents available to the art. There is no particular mode of practicing the inventions and/or examples of the invention that is superior to others, so long as the functions may be performed. It is believed that all the crucial aspects of the invention have been provided in this document. In a back to back stack hot runner system with plate-actuated valve pins, the first movable-plate assembly (102) and the second movable-plate assembly (104) may move towards each other to open the valve pins and away from each other to close the valve pins. The proposed invention seeks to reduce hot runner shut-height by combining components or functions between the first movable-plate assembly (102) and the second movable-plate assembly (104).
In one example, the drive system that moves the first movable-plate assembly (102) and the second movable-plate assembly (104) further apart (to close the valve stems) may be shared. An inflatable bladder may be positioned between the first movable-plate assembly (102) and the second movable-plate assembly (104), such that when the bladder is inflated, the first movable-plate assembly (102) and the second movable-plate assembly (104) are pushed apart, thus moving the valve pins to the valve-closed position.
In another example, an alignment bearing system may be shared between the first movable-plate assembly (102) and the second movable-plate assembly (104). A bi-directional lead screw may be used to ensure that both the first movable-plate assembly (102) and the second movable-plate assembly (104) move the same distance (even in the opposite direction). A nut follower may be located on each lead screw direction, such that as the screw rotates in one direction, the nuts move further apart, and upon reversing the direction of rotation, the nuts move closer together. For each lead screw in the system, one nut may be mounted to each of the first movable-plate assembly (102) and the second movable-plate assembly (104), thus tying the movement of the first movable-plate assembly (102) and the second movable-plate assembly (104) together. In this example, the lead screw may be used for alignment and synchronous movement only (with a separate drive system), or the movement of the first movable-plate assembly (102) and the second movable-plate assembly (104) may be driven by the screw rotation.
In another example, a physical stop that defines the amount of stroke the first movable-plate assembly (102) and the second movable-plate assembly (104) may be capable of being actuated and may be shared. The shared physical stop may be mounted in the hot runner plates, or the first movable-plate assembly (102) and the second movable-plate assembly (104) may in fact stop on themselves, such that when the valve pins are in the valve-open position the first movable-plate assembly (102) and the second movable-plate assembly (104) are in contact and restrict each other's motion to further move the pin position.
It is understood that these examples described above are some examples of the mold-tool system (100). Someone skilled in the art of mechanical system design may be capable of devising a number of different arrangements in which some part of the actuation system is shared between the first movable-plate assembly (102) and the second movable-plate assembly (104) so as to actuate valve pins in different directions. Also, components from the different example listed above may be combined to make a more integrated plate actuation system.
It is understood that the scope of the present invention is limited to the scope provided by the independent claim(s), and it is also understood that the scope of the present invention is not limited to: (i) the dependent claims, (ii) the detailed description of the non-limiting embodiments, (iii) the summary, (iv) the abstract, and/or (v) description provided outside of this document (that is, outside of the instant application as filed, as prosecuted, and/or as granted). It is understood, for the purposes of this document, the phrase “includes (and is not limited to)” is equivalent to the word “comprising”. It is noted that the foregoing has outlined the non-limiting embodiments (examples). The description is made for particular non-limiting embodiments (examples). It is understood that the non-limiting embodiments are merely illustrative as examples.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US12/20864 | 1/11/2012 | WO | 00 | 7/24/2013 |
| Number | Date | Country | |
|---|---|---|---|
| 61437731 | Jan 2011 | US |
