Plastic article or earthenware shaping or treating: apparatus – With apparatus assembly or dismantling means or with idle part – For extrusion or injection type shaping means
Reexamination Certificate
2002-12-10
2004-10-12
Mackey, James P. (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
With apparatus assembly or dismantling means or with idle part
For extrusion or injection type shaping means
C029S426100
Reexamination Certificate
active
06802704
ABSTRACT:
TECHNICAL FIELD
The present invention relates to molds used in injection molding machines. More particularly, the present invention relates to a latching device for use with an injection mold that includes removable inserts, to facilitate removal or changing of the mold inserts.
BACKGROUND ART
An injection molding machine operates so rapidly that it can quickly finish a run of a particular molded part in a comparatively short period of time. In view of the substantial cost of the machine, it should not be allowed to sit idle. When changing the set-up of the molding machine from production of one part to another, the article-forming mold in the machine has to be removed and a new mold inserted so that the machine can begin to operate and produce the new molded part. The time taken in changing the mold must be minimized so the machine can begin productive use as soon as possible. It currently takes from one to several hours to complete a complete mold change. The time lost in the mold change process has a marked effect on the profitability of a molding business.
Master Unit Die Products, Inc. (“MUD”) significantly reduced the time required for mold changes with its invention of a “Quick Change System for Mold Bases” as described in U.S. Pat. No. 5,350,289. The MUD quick change system is used with molds having adapter frames that are attached to the platens of the injection molding machine. The adapter frames are readily transferable from machine to machine using the existing mounting hole patterns on the platens of the machines. The molds are typically supported on ear plates that are adapted to support many different size molds. The ear plates are also readily transferable from adapter frame to adapter frame. The adapter frames have a U-shaped guide and support channel for receiving the ear plates on the mold base. T-shaped guide rollers are mounted in line with the entrance to each side of the guide channel. The T-shape configuration for the guide rollers enables the edge of the ear plate to roll along the vertical portion of the “T” while the larger horizontal portion of the “T” captures the ear plate, keeping the ear plate in line with the guide channel on the adapter frame. The adapter frames are attached to the platen faces using the existing standard threaded hole pattern on the platen face. Clamps can be used for the initial installation of the adapter frame. The clamps are preferably removed after bolts or cap screws, or the like, are used to fasten the adapter plates to the face of the platen. When the ear plate is inserted into the adapter frame, all of the fasteners are covered, eliminating a potential source of damage during the operation of the machine. The MUD quick change system allows mold assemblies that are equipped with standard ear plates to be changed in a molding machine in ten minutes, or even less time.
However, when the MUD frame is used with a hot runner manifold system, the “A” side frame that accepts the “A” side insert is bolted to the hot runner system nozzle plate. If the MUD inserts need to be changed to a different set, the “A” side mounting screws have to be removed, and the “A” side has to be pulled away from the hot runner system, so that the nozzles are pulled out of the seal-off and gate well in the mold frame. This is necessary to obtain sufficient clearance so that the nozzles of the hot runner system do not interfere with removal of the inserts and installation of the replacement mold inserts. The removal of the “A” side mounting screws is time consuming and slows the process of changing the mold inserts significantly, somewhat negating the advantage of the MUD quick change concept.
DISCLOSURE OF INVENTION
Briefly stated, in accordance with one aspect of the present invention, a latching device is provided that uses a cam action to hold the “A” side plate against the hot runner system (nozzle plate) during operation, thus replacing the screws used in prior art mold constructions. Preferably, the latching device is provided on each side of the mold to hold most effectively the “A” side plate against the nozzle plate during the high pressure injection of plastic melt.
For purposes of a mold insert change, each latch is rotated to release the “A” side plate from the nozzle plate, and hold the “A” side plate against the “B” side of the mold. This enables the “A” and “B” portions of the mold assembly to be moved away from the nozzle plate, thereby avoiding interference between the hot runner nozzles and “A” side insert and enabling quick mold insert change.
The latching device of the present invention includes dowel pins in both the nozzle plate and “B” side plate. A pivoting latch arm is configured to engage one or the other of the pins, depending on the function to be performed. The latch arm pivots on a center hub with and offset to provide a cam-tightening effect when the hub is rotated by a latch lever. The latch is engaged with the dowel in the nozzle plate during operation. To perform a mold insert change: (i) the clamp mechanism of the molding machine is operated to close the mold, (ii) the center hub of the latching device is rotated using a lever to release the latching force between the “A” side and nozzle plate, (iii) the latch arm is rotated to engage the pin on the “B” side, (iv) the center hub is rotated by the latch lever to generate a latching force between the “A” and “B” sides, (v) a safety pin is inserted in the latch arm, (vi) the clamp mechanism of the molding machine is operated to open the mold, moving the “B” and “A” sides together to clear the hot runner nozzles, (vii) the mold inserts are removed, (viii) new mold inserts are installed, and (ix) sequence is reversed so that latch arm ends tightly engaged with the pin in the nozzle plate.
Accordingly, the latching device of the present invention provides for a time-saving means of releasing and connecting a mold assembly and a hot runner manifold system.
REFERENCES:
patent: 4655275 (1987-04-01), Worner
patent: 5114330 (1992-05-01), Nielsen
patent: 5350289 (1994-09-01), Martin
Adas James O.
Eigler Frank J.
Steil Frederick G.
D-M-E Company
Friskney Stephen H.
Gregg John W.
Mackey James P.
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