The present invention generally relates to molded part pickers, and more specifically the present invention relates to, but is not limited to, a molded part transfer device including the molded part picker.
Some injection molded parts, for example plastic preforms of the variety that are for blow molding into beverage bottles, require extended cooling periods to solidify into substantially defect-free molded parts. To the extent that the cooling of the molded part can be effected outside of the injection mold by one or more post-mold transfer and cooling devices then the productivity of the injection mold may be increased (i.e. lower cycle time). A variety of such post-mold molded part transfer and cooling devices, and related methods, are known and have proven effective at the optimization of the injection molding machine cycle time.
In a typical injection molding system a molded partially cooled molded part is ejected from the injection mold and into a cooled carrier of a take-out plate, for post-mold cooling thereof, once an initially cooled surface skin has formed on the molded part that allows for its ejection without a deformation thereof.
U.S. Pat. No. Re. 33,237 discloses a post-mold transfer and cooling device that includes a robotically-controlled multi-position take-out plate for removing molded partially cooled injection molded parts from the core side of an injection mold. The molded parts are ejected from the mold directly into cooled carriers, as disclosed in commonly assigned U.S. Pat. No. 4,729,732, and transported by the robot to an outboard position. The plate has multiple sets of carriers, each set being sufficient in number to hold one molded part from each of the cores of the multi-cavity mold. There are multiple sets of carriers on the plate so that multiple sets of molded parts can be held and cooled, the set that is ejected from the carriers being the set that has been cooling the longest. Without a positive ejection force, molded parts can stick in the carriers and cause an interruption in the molding cycle.
Commonly assigned U.S. Pat. No. 6,171,541 discloses a post-mold cooling transfer and cooling device that includes a cooling pin for insertion into the interior of a molded partially cooled molded part, while the molded part is arranged in the cooled carrier of the take-out plate, to discharge a cooling fluid therein. The foregoing is sold under the trade name of COOLJET, a trade-mark of Husky Injection Molding Systems Limited. Also disclosed is a procedure to apply a vacuum through the same cooling pin to cause the molded part to remain with the pin when it is moved away from the carrier holding the molded part, thereby removing the molded part from the carrier. The pins, mounted to a frame, may be rotated 90 degrees to a discharge position and the vacuum terminated to allow the molded parts to fall off the pins.
Co-pending, commonly assigned, United States published application 2004/0185136 published Sep. 23, 2004 describes an injection molding system that includes both of the foregoing take-out and COOLJET devices that cooperate to handle and cool the molded parts once ejected from the injection mold.
The foregoing injection molding system has been sold under the trade name of HYPET, a trade-mark of Husky Injection Molding Systems Limited, for the manufacture of beverage preforms and the like. The HYPET system is known to incorporate an expandable picker 50, as shown with reference to
U.S. Pat. No. 4,783,108, assigned to Bridgestone Corporation, describes the construction of an expandable picker that is similar to the ‘folded-over’ picker used on the HYPET system.
Examples of commercially available expandable pickers are the AIRPICKER, a trade-mark of Firestone Corporation, that is available from Firestone Industrial Products (www.firestoneindustrial.com), and the expandable pickers available from Anver Corporation (www.anver.com). Expandable pickers are sold for many uses that also include preform handling in a blow molding and bottling environments.
With reference to
The take-out device 13 is mounted on the stationary platen 16 and includes a horizontal “Z” beam 20 that projects to the non-operator side of the machine and upon which rides a carriage 21, moved along the beam by (typically) a servo-electric driven belt drive (not shown). Multi-position plate 23 is attached to the carriage 21. Multiple sets of carriers 24 are mounted on plate 23 and may be cooled for transporting multiple molded shots of molded parts ejected from the mold from an inboard (loading) position (not shown).
The COOLPIK device 14 includes a cooling plate 25 upon which are mounted multiple cooling pins 26. A hollow structure 45 attaches a plenum 29, on which the plate 25 is mounted, to the hollow cylinder 40, and allows services to be carried from the machine through the structure 45 to the plenum 29 and plate 25. The plate 25 and plenum 29 can be rotated very quickly through a 90-degree arc by any suitable means. For example, the rotation of the plate 25 can be effected by an electric drive (not shown) mounted to the hollow structure 45. The plate 25 and plenum 29 preferably move toward and away from the carriers 24 with the movement of the moving platen 41.
In operation, one shot of molded parts is transferred into the carriers 24 when the mold is open and the multi-position take-out plate 23 is positioned such that empty carriers are aligned with molded parts on the mold cores. In the example shown in
When the molding cycle ends and the mold opens, the pickers extract one third or, in this case, 32 of the molded parts 109 from the carriers 24 on the plate 23, as shown with reference to
The plate 25, preferably made of lightweight aluminum, or similar material, carries cooling pins 26 sufficient in number to exceed the number of carriers 24 on the multi-position carrier plate 23 by a number equivalent to two rows of carriers 24. Rows of picker devices 50 are provided with every third row of cooling pins 26′. As shown with reference to
A significant problem with foregoing picker 50 involves a premature wear-related thinning of the tubing 52 along the outside comer 64 of the tubing 52 where it folds over on itself (the interrupted line represents the worn outer surface of the tubing at the outer comer 64). The thinning tubing 52 eventually ruptures when expanded. The wear along the outside comer 64 is thought to be the result of the repeated rubbing between the tubing 52 and the inside surface of the molded part 2. The rubbing is exacerbated whenever there is misalignment between the picker 50 and the molded part 2. The service life of a typical picker 50 is between a half and one million cycles. The failure of even one picker 50 in the array will require its immediate replacement and will result in a significant interruption in the productivity of the injection molding system.
By improving the wear characteristics of the picker, its service life can be extended. By increasing the service life of the picker, a reduction in the maintenance requirements in a molded part handling system can be achieved, particularly unplanned maintenance, and thereby improve the availability and hence productivity of the overall system which may increase manufacturing profitability. The present invention mitigates the problems associated with known pickers at least in molded part.
According to a first aspect of the present invention, there is provided a molded part picker for a molded part handling system. The molded part picker includes a balloon having a wear member for contacting a molded part when the balloon is positioned and inflated to do so, and the wear member disengages from the molded part when the balloon is deflated to do so.
According to a second aspect of the present invention, there is provided a molded part transfer device that includes the molded part picker in accordance with the first aspect of the present invention.
According to a third aspect of the present invention, there is provided an injection molding system having a molded part transfer device that includes the molded part picker in accordance with the first aspect of the present invention.
A technical effect of the aspects of the present invention is to immolded part an increased wear resistance in a molded part picker, whereby its service life can be extended. By improving the service life of the picker a reduction in the maintenance requirements in a molded part handling system can be achieved, particularly unplanned maintenance, and thereby improve the availability and hence productivity of the overall system which may increase manufacturing profitability.
A better understanding of the exemplary embodiments of the present invention (including alternatives and/or variations thereof) may be obtained with reference to the detailed description of the exemplary embodiments along with the following drawings, in which:
The exemplary embodiments of a molded part picker are described below along with a description of the increased wear resistance associated with using some of the exemplary embodiments.
In view of the foregoing, the description hereinafter will focus only on the implementation of the wear members 166, 266, 366, 466, 566, 666, and 766.
Of course, other shapes and dimensions of wear members are possible. For example, alternative tubing has a width W and height H dimensions that are each preferably about 0.7 millimeters. In addition, the shape of the wear member shape may otherwise be semi-circular, triangular, or just about any other polygon.
Notwithstanding the foregoing, the tubing 152 is preferably configured to have a nominal wall thickness between about 1 and 2 millimeters, and wherein the wear member has a nominal height of between about 0.4 and 1 millimeter and a width between about 0.4 and 1 millimeter.
In accordance with an eight embodiment of the present invention (not shown) the balloon includes a random distribution of wear members.
Preferably the balloon 153, 253, 353, 453, 553, 653, and 753 comprises tubing 152, 252, 352, 452, 552, 652, and 752 and wear members 166, 266, 366, 466, 566, 666, and 766 that are integrally extruded, and wherein they are made from the same material. In an accordance with an alternative embodiment of the invention, the tubing 152, 252, 352, 452, 552, 652, and 752 and wear members 166, 266, 366, 466, 566, 666, and 766 are integrally co-extruded, and wherein the tubing 152, 252, 352, 452, 552, 652, and 752 and wear members 166, 266, 366, 466, 566, 666, and 766 are made from materials having at least one distinct physical property. Alternatively, the wear members 166, 266, 366, 466, 566, 666, and 766 may be separately formed and bonded to the balloon 153, 253, 353, 453, 553, 653, and 753. Preferably the bonding is achieved by means of vulcanizing. Of course, the balloon 153, 253, 353, 453, 553, 653, and 753, tubing 152, 252, 352, 452, 552, 652, and 752, and/or wear members 166, 266, 366, 466, 566, 666, and 766 may be formed by other means such as injection molding, either integrally or separately. As another alternative the wear members 166, 266, 366, 466, 566, 666, and 766 may be configured as a coating that is bonded to the balloon 153, 253, 353, 453, 553, 653, and 753. Presently preferred materials for forming the tubing 152, 252, 352, 452, 552, 652, and 752 and wear members 166, 266, 366, 466, 566, 666, and 766, although not an exclusive listing, includes elastomers such as SANTOPRENE (a trade-mark of Monsanto Corporation), Latex, ethylene propylene diene monomer (EPDM), Urethane, PVC-Urethane blends, and any combination or permutation thereof.
In accordance with an alternative embodiment, the wear members 166, 266, 366, 466, 566, 666, and 766 may be molded to have a different physical property than the tubing 152, 252, 352, 452, 552, 652, and 752. For example, the wear member 166, 266, 366, 466, 566, 666, and 766 may have a contrasting colour with the tubing 152, 252, 352, 452, 552, 652, and 752 as a visible indication of wear. As another example, the wear member 166, 266, 366, 466, 566, 666, and 766 the physical property is wear resistance and wherein the wear member material has a higher wear resistance than the tubing material.
A further advantage may be derived from an embodiment of the molded part picker 150, 250, 350, 450, 550, and 650 in a molded part transfer and cooling device, such as the COOLJET device 14, wherein the cooling fluid flow from the cooling pin 26 may continue to flow during the period that the molded part 2 is being gripped by the molded part picker 150, 250, 350, 450, 550, and 650. In particular, any gap that may be defined between an inside surface of the molded part 2 and the space between adjacent the wear members 166, 266, 366, 466, 566, and 666, may be used to support the cooling fluid flow. Clearly, the flow is a function of the size of the gap and the fluid pressure.
In conclusion, a wear resistant molded part picker 150, 250, 350, 450, 550, 650 and 750 has been described that is molded particularly well suited, although not exclusively, for the handling of molded parts such as injection molded preforms, blow molded bottles, and the like, by gripping an inside surface thereof. Accordingly, the molded part picker 150, 250, 350, 450, 550, 650 and 750 may be fitted, or otherwise retrofitted into devices such as a post-mold transfer and cooling device, a molded part transfer device in a blow molding system, or a molded part transfer device in a bottling system.
The description of the exemplary embodiments provides examples of the present invention, and these examples do not limit the scope of the present invention. It is understood that the scope of the present invention is limited by the claims. The concepts described above may be adapted for specific conditions and/or functions, and may be further extended to a variety of other applications that are within the scope of the present invention. Having thus described the exemplary embodiments, it will be apparent that modifications and enhancements are possible without demolded parting from the concepts as described. Therefore, what is to be protected by way of letters patent are limited only by the scope of the following claims: