Patent Application
20050280188
1. Field of the Invention
The invention relates to a mold assembly and method of operating such a mold assembly for an injection molding machine.
2. Description of the Prior Art
In the field of plastic injection molding it is advantageous to reduce the labor and material required to manufacture separate molds for molding parts of differing shapes. Reduction in manufacturing labor and material is often achieved by commonizing components, which allows components to be removed from one assembly and placed on a second assembly without the need of creating a new component, thus decreasing labor and material costs associated with creating a new component. In order to achieve this, several modularized mold assemblies have been developed which include a base for disposition in a molding machine and a mold presenting a shaping surface for forming a part. Typically the mold is attached to the base with a mounting system for mounting the mold on the base to prevent relative movement therebetween during the forming of the part. Such an assembly and method for using the assembly is shown in the U.S. Pat. No. 6,328,552 to Hendrickson et al. This assembly includes a base for use with interchangeable molds to create parts of differing shape. However, the parts are ejected from the mold by an ejection plate which is moveable by an outside source and which includes a plurality of ejector pins which extend through the mold to eject the parts when the ejection plate is moved. In other words, all of the ejection pins are fixed on a movable ejection plate. Such an ejector assembly adds weight and length to the assembly and additional time and labor is required to adapt such an ejector assembly to different molds.
Other assemblies have included an ejection actuator that is located entirely within the base and is removable from the base for reuse in a second base, as illustrated in U.S. Pat. No. 3,645,492 to Edlis. This assembly includes an actuator mounted entirely within the base. However, this assembly also includes an ejector plate to move all of the ejection pins in unison. During ejection, an actuator displaces the ejection plate and the ejector pins extend through the mold to eject part.
The invention is characterized by immovably mounting a plurality of ejectors in a chamber defined by the mold on the base and extending through the mold for actuation independently of one another for ejecting the part from the shaping surface.
The current assemblies or methods do not include independently actuatable ejectors mounted on a base immovable relative to a mold in a chamber defined by the mold, which allows the base and ejectors to be reused with multiple molds by rearranging the ejectors on the base and which decreases the weight and size of the assembly.
Accordingly, the base and ejectors are reusable with a plurality of molds by removing the mold from the base, removing the ejectors from the base, mounting the ejectors on the base in a position to accommodate a second mold, and mounting the second mold on the base.
In addition, the existence of the chamber and the placement of the ejector in the chamber decreases the size and weight of the assembly.
Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
An assembly for an injection molding machine is generally shown in
A plurality of bolts 28 define a mounting system for mounting the mold 20 on the base 22 to prevent relative movement therebetween during the forming of the part 24. The bolts 28 extend through the base 22 and threadedly engage the mold 20 to immovably attach the mold 20 to the base 22.
The assembly is characterized by the mold 20 defining a chamber 30 with the base 22 and by including a plurality of ejectors, each generally indicated at 32, immovably mounted on the base 22 in the chamber 30 and extending through the mold 20 and independently actuatable for ejecting the part 24 from the shaping surface in the cavity. The creation of the chamber 30 results in weight reduction of the mold 20. Also, since the existance of the chamber 30 allows the ejectors 32 to be disposed in the chamber 30 the distance required between the molding machine platens is shortened. The size and weight reduction allows easier movement and mounting of the mold assembly and reduces the required size of the molding machine. Each of the ejectors 32 includes a stationary portion 34 immovably mounted on the base 22 and an actuatable portion 36 extending through the mold 20 and movable relative to the stationary portion 34 and the base 22 for ejecting the part 24 from the shaping surface. Where the actuatable portion 36 extends through the mold 20 the contour of the actuatable portion 36 generally follows the contour of the shaping surface so that the actuatable portion 36 shapes a portion of the part 24. The ejectors 32 include threaded screws 38 defining fastening devices for removably attaching the stationary portion 34 of each ejector 32 to the base 22 independently of one another. The threaded screws 38 extend through the stationary portion 34 of each ejector 32 and into threaded engagement with the base 22.
The base 22 presents a recess 40 presenting a periphery and the mold 20 interfaces with the periphery of the recess 40 in the base 22. The ejectors 32 are disposed in the recess 40. Preferably, the base 22 includes a multiplicity of threaded holes 42 for mounting the ejectors 32 in a variety of configurations, depending upon the particular mold 20 and part 24 being formed. In other words, the shape of the part 24 being formed determines the positions of the various ejectors 32 to eject the part 24 from the mold 20. The ejectors 32 may be electric, hydraulic, pneumatic or mechanical but in any case the ejectors 32 are actuated independently of one another from a controller for actuating each of the ejectors 32 to move the actuatable portion 36 of each ejector 32. This is in contradistinction to the prior art plate or platen supporting a plurality of rods to move the rods in unison to remove the part 24 from a mold 20. Because each ejector 32 includes a stationary portion 34 attached directly to the base 22, a controller, such as a valve or computer, sends an independent actuation signal to each ejector 32. This means, of course, that the respective ejectors 32 may be actuated sequentially to sequentially remove areas of the part 24 from the mold 20.
The base 22 also includes a slide pocket 44 and a slide match 46 slidably supported in the slide pocket 44 for forming a section 48 of the part 24 in a closed position and movable in the slide pocket 44 to an open position to allow the of the part 24 to be removed from the mold 20. In other words, the slide match 46 is in the closed position when the part 24 is being formed and a section 48 of the part 24 is formed between the slide match 46 and the mold 20. Referring to
The mold 20 includes cooling passages 54 extending therethrough and including inlet and outlet connections 56 for connection 56 to a source of cooling fluid independently of the base 22. For the purpose of clarity, only one continuous cooling passage 54 is illustrated in
Accordingly, the invention also provides a method of operating a mold assembly for an injection molding machine comprising the steps of mounting a mold 20 presenting a shaping surface for forming a part 24 on a base 22 to prevent relative movement therebetween during the forming of the part 24 and characterized by immovably mounting a plurality of ejectors 32 on the base 22 to extend through the mold 20 for actuation independently of one another for ejecting the part 24 from the shaping surface.
More specifically, the method includes removing the mold 20 from the base 22, removing at least some of the ejectors 32 from the base 22, mounting at least one of the removed ejectors 32 on the base 22 in a different and new position to define a different configuration of ejectors 32 on the base 22, and mounting a second or different mold 20 on the base 22 to prevent relative movement therebetween with the ejectors 32 extending through the second mold 20.
The steps are further defined as immovably mounting a stationary portion 34 of each of the ejectors 32 on the base 22 and extending an actuatable portion 36 of each of the ejectors 32 through the mold 20 and ejecting the part 24 from the shaping surface by moving the actuatable portion 36 relative to the stationary portion 34 and the base 22. Yet a further definition includes removably attaching the stationary portion 34 of each ejector 32 to the base 22 independently of one another by extending threaded screws 38 through the stationary portion 34 of each ejector 32 and into threaded engagement with the base 22. Since each ejector 32 is independently attached to the base 22, which is in turn immovable relative the machine, the method includes the step of actuating each of the ejectors 32 independently of one another to move the actuatable portion 36 of each ejector 32 relative to the mold 20. As alluded to above, the method includes forming a multiplicity of threaded holes 42 in the base 22 for mounting the ejectors 32 in a variety of configurations.
The steps are further defined by immovably attaching the mold 20 to the base 22 by extending a plurality of bolts 28 through the base 22 and threadedly engaging the mold 20.
At the end of the molding steps, a further step includes moving a slide match 46 to a closed position and forming a section 48 of the part 24 against the slide match 46 in the closed position and moving the slide match 46 to an open position and removing the part 24 from the mold 20.
Obviously, many modifications and variations of the present invention are possible in light of the above teachings. The invention may be practiced otherwise than as specifically described within the scope of the appended claims, wherein that which is prior art is antecedent to the novelty set forth in the “characterized by” clause. The novelty is meant to be particularly and distinctly recited in the “characterized by” clause whereas the antecedent recitations merely set forth the old and well-known combination in which the invention resides. These antecedent recitations should be interpreted to cover any combination in which the incentive novelty exercises its utility. In addition, the reference numerals in the claims are merely for convenience and are not to be read in any way as limiting.
This application claims the benefit of provisional application Ser. No. 60/582,012 filed Jun. 22, 2004.
| Number | Date | Country | |
|---|---|---|---|
| 60582012 | Jun 2004 | US |
