Patent Application
20160059460
The invention relates generally to a locking mechanism that maintains holding pressure in an injection mold. In particular, this invention is directed to a mechanical lock used to aid an injection molding machine to hold the injection mold in a closed position during a molding operation.
In one aspect, the present invention provides a locking mechanism for an injection mold including a mold cavity and a mold core moveable between an open position and a closed position. The locking mechanism includes a first locking structure rigidly coupled to and moveable with the mold core, a second locking structure coupled to the mold cavity and configured to selectively engage the first locking structure and moveable between a locked position and an unlocked position, and an actuator selectively actuating the second locking member between the locked position and the unlocked position.
The foregoing and other aspects and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims and herein for interpreting the scope of the invention.
The invention will be better understood and features, aspects and advantages other than those set forth above will become apparent when consideration is given to the following detailed description thereof. Such detailed description makes reference to the following drawings.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings.
The following discussion is presented to enable a person skilled in the art to make and use embodiments of the invention. Various modifications to the illustrated embodiments will be readily apparent to those skilled in the art, and the generic principles herein can be applied to other embodiments and applications without departing from embodiments of the invention. Thus, embodiments of the invention are not intended to be limited to embodiments shown, but are to be accorded the widest scope consistent with the principles and features disclosed herein. The following detailed description is to be read with reference to the figures, in which like elements in different figures have like reference numerals. The figures, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of embodiments of the invention. Skilled artisans will recognize the examples provided herein have many useful alternatives and fall within the scope of embodiments of the invention.
The mold cavity 105 is fixed to a stationary platen of the injection molding machine and defines the lower portion of the cavity established between the mold cavity 105 and the mold core 110 in the closed position (as viewed in
The mold core 110 defines two t-shaped recesses 122 shaped to receive portions of the two locking mechanisms 115, as will be discussed in detail below. The mold core 110 may include other features and components, as understood by those of skill in the art. Additionally, terminology is not always consistent within the injection molding art. It is contemplated, that the mold core may be referred to as the stationary component, both the mold core and the mold cavity may be moveable relative to one another, or the mold as a whole may be arranged differently. The specific arrangement of the mold core 110 and the mold cavity 105 are not limiting on the invention and may be arranged differently, as desired.
One locking mechanism 115 is discussed below with respect to
With reference to
The first locking structure 180 defines a locking face 220 that extends along the head 195 and the arm 200. A slot 225 is defined in the locking face 220 of the arm 200 and is defined by a first slot face 230, a second slot face 235, and a third slot face 240. The slot 225 is configured with non-locking geometry such that during operation, the second locking structure 190 does not become stuck in the slot 225. The third slot face 240 defines a plane.
The first slot face 230 is arranged at a non-locking oblique angle relative to a plane perpendicular to the third slot face 240. In the illustrated embodiment, the first slot face 230 is arranged at about a seven degree angle relative to a plane perpendicular to the third slot face 240. In other embodiments the angle may be between about five degrees and fifteen degrees.
The second slot face 235 is arranged at a non-locking oblique angle relative to a plane perpendicular to the third slot face 240. In the illustrated embodiment, the second slot face 235 is arranged at about a seven degree angle relative to a plane perpendicular to the third slot face 240. In other embodiments the angle may be between about five degrees and fifteen degrees.
In the illustrated embodiment, the first slot face 230 and the second slot face 235 are mirror images of one-another such that the angle formed between the first slot face 230 and the second slot face 235 is about fourteen degrees. In other embodiments, the angle of the first slot face 230 may be different from the second slot face 235. For example, the second slot face 235 may be arranged at ninety degrees relative to the third slot face 240 and the first slot face 230 may be arranged at a non-locking angle such as seven degrees.
The slot 225 includes filleted surfaces 245 between the first slot face 230 and the third slot face 240, and the second slot face 235 and the third slot face 240. The non-locking configuration of the slot 225 is at least partially dependant on the material the first locking structure 180 is formed from. In the illustrated embodiment, the first locking structure 180 is formed from steel. The non-locking angles of the faces discussed above are contemplated for steel but may be applicable to other materials as well.
The cavity slot 128 formed in the mold cavity 105 is shaped to match the slot 225. That is to say, the profile of the cavity slot 128, as viewed in
With reference to
The first non-locking bar face 320 and the second non-locking bar face 325 are arranged to match the first slot face 230 and the second slot face 235, respectively. In other words, the first non-locking bar face 320 is arranged at a non-locking angle of about seven degrees relative to the first flat bar face 310, and the second non-locking bar face 325 is arranged at a non-locking angle of about seven degrees relative to the second flat bar face 315. In other embodiments, the non-locking angles may be between about five and fifteen degrees, as desired. Additionally, the first non-locking bar face 320 and the second non-locking bar face 325 may not be mirror images of one another, as desired.
With continued reference to
The housing 255 defines a cylindrically-shaped internal cavity 265 sized to receive the piston head 265 of the moveable member 250 for movement along an axis 270 between a unlocked position (shown in
The stud 260 is threaded and couples the second locking structure 190 to the moveable member 250 of the actuator 185. The stud 260 is threaded into the aperture 342 formed in the exterior face 335 of the second locking structure 190, and into the aperture 275 of the moveable member 250. In other embodiments, the second locking structure 190 is coupled to the moveable member in a different way. For example, the second locking structure 190 could be welded to the moveable member 250, pinned, clipped, or coupled for movement therewith in another way, as desired.
The mounting bracket 192 includes a central through hole 290 sized to provide passage of the moveable member 250, a guide slot 295, and mounting holes 300. The central through hole 290 is coincident with central axis 270 of the housing 255 and the moveable member 250. The guide slot 295 is centrally located on a front face 305 of the mounting bracket 192, extending across the entire width of the front face 305, and is wide enough to receive the second locking structure 190 without interference. The guide slot 295 is sized to slidingly receive the first flat bar face 310 and the second flat bar face 315.
The mounting bracket 192 is affixed to the mold cavity 105 via mounting holes 300 such that the mounting bracket 192 is rigidly coupled to the mold cavity 105. The housing 255 of the actuator 185 is rigidly coupled to the mounting bracket 192 such that only the moveable member 250 and the second locking structure 190 move relative to the mounting bracket 192.
In operation, the injection mold 100 begins in the open position (See
With the mold core 110 in the closed position (see
When the molding medium is injected into the cavity, a force of the injection molding process biases the mold core 110 toward the open position. The force of the injection molding process is opposed by the injection molding machine, and additionally by the mechanical structure of the locking mechanisms 115. At least a portion of the force of the injection molding process is transferred between the mold core 110, the first locking structure 180, the second locking structure 190, the mounting bracket 192, the cavity slot 128, and the mold cavity 105.
The mold core 110 is held in the closed position for a predetermined amount of time before the actuator 185 moves the second locking structure out of the locked position and toward the unlocked position. The non-locking angles formed on the non-locking faces 320, 325 and the slot faces 230, 235 allow the actuator to move the second locking structure between the locked and unlocked positions without sticking or becoming permanently locked within the slot 225.
When the second locking structure 190 is in the unlocked position, the injection molding machine moves the mold core 110 along the leader pins 120 from the closed position toward the open position (see
The injection molding process requires that a specified holding pressure be maintained during a solidification portion of the injection molding cycle. Current systems utilize a hydraulic system along with the weight of the injection molding machine to create and maintain the necessary pressures. The addition of the locking mechanism 115 to an injection mold 100 increases an upper limit of holding pressure that a injection molding machine can achieve and maintain within a given footprint. For example, the injection mold 100 absent the locking mechanisms 115 would not be able to operate with as high a holding pressure as with the locking mechanism 115. In other words, the locking mechanisms 115 add to the capacity of the injection mold 100.
The mechanical locking mechanisms 115 allow for the reduction of the footprint of the injection mold 100. Traditional injection molding machines take advantage of the weight of the machine and mold itself and large hydraulic rams to create additional holding pressure. Therefore, typically, larger machines can produce higher pressures. The addition of a mechanical locking system (e.g. the mechanical locking devices 115) significantly increases the holding pressure of a given machine and reduces the need for larger tonnage to reach required pressures. This allows for smaller machines and more flexibility leading to lower equipment cost and an increase in available production space.
It will be appreciated by those skilled in the art that while the invention has been described above in connection with particular embodiments and examples, the invention is not necessarily so limited, and that numerous other embodiments, examples, uses, modifications and departures from the embodiments, examples and uses are intended to be encompassed by the claims attached hereto. The entire disclosure of each patent and publication cited herein is incorporated by reference, as if each such patent or publication were individually incorporated by reference herein.
