United States Patent 3924422
There is provided an improved stopper assembly to terminate the flow of molten metal into a mold cavity and to prevent reverse flow of molten metal after the mold has been filled. The stopper assembly includes a mounting spider secured within an opening of the mold cope and a stopper is frictionally held by the mounting spider and aligned so that a stopper washer is adapted to seat against the ingate of the mold.
Sandor, Louis (Hammond, IN)
Germain, Andrew Gerald (Itasca, IL)
Wiles, Donald Ray (Kansas City, KS)
Filippini, Ronald A. (Chicago, IL)
Amsted Industries Incorporated (Chicago, IL)
B22D18/04; (IPC1-7): B22D17/30
Field of Search:
Shore, Ronald J.
Attorney, Agent or Firm:
Bootz, Andrew Faust Ralph Kostka Fred J. M. P.
What is claimed is
1. A mold structure comprising, in combination,
2. A mold structure as set forth in claim 1 wherein the opening in said cope has an enlarged counterbore at it supper end receiving said mounting ring.
3. A mold structure as set forth in claim 1 and including electrical insulation between said stopper assembly and said cope.
4. A mold structure as set forth in claim 1 wherein said biasing means is a spring.
5. A mold structure as set forth in claim 1 wherein said cope and drag are formed of graphite and wherein said stopper washer is formed of graphite.
BACKGROUND AND SUMMARY OF THE INVENTION
This invention relates to the casting of metals and more particularly to the casting of ferrous metal objects such as iron or steel railway car wheels.
It is known to cast railway car wheels by a bottom pressure casting process, such as is illustrated and described in U.S. Pat. No. 2,792,606, granted May 21, 1957 to E. Q. Sylvester. As therein described, the casting method comprises a system for forcing the molten metal upwardly through an ingate in the mold drag to fill the mold cavity. A stopper is provided which is forced downwardly to shut off the flow of molten metal in the mold upon completion of the pressure pouring operation. In addition, the stopper assembly prevents the reverse flow of molten metal out of the mold after the pressure has been shut off and the mold has been moved from the ladle. Heretofore, a stopper comprising a stopper plunger and a stopper washer have been provided through an aperture in the cope adapted to seat against the ingate in the drag and held open in any convenient manner such as, in the referenced patent, by a deformable wire or nail passed through one of a series of openings in the stopper pipe. In commercial practice an electrical probe is provided in the mold riser to cut off the flow of molten metal when the cavity of the mold is full. Thus it has become desirable to electrically insulate the stopper from the cope. The stopper plunger was commonly held in position by a cardboard cylinder which served to frictionally hold the stopper open and additionally served to electrically isolate the stopper from the mold.
Difficulty was experienced in the assembly of the stopper with the cope and further by the installation of the cardboard cylinder so that the method was cumbersome, time consuming and costly.
Accordingly, it is an object of the present invention to provide an improved stopper for a mold.
It is a further object of the present invention to provide a stopper assembly which overcomes the above-mentioned difficulties.
Further features of this invention will hereinafter appear.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional vertical view of a bottom pressure pouring system embodying the stopper assembly according to the invention;
FIG. 2 is a fragmentary cross-sectional view of the stopper assembly of FIG. 1 illustrated to a larger scale; and
FIG. 3 is a plan cross-sectional view of the stopper assembly of FIG. 2 taken along line 3--3 thereof.
DESCRIPTION ON THE PREFERRED EMBODIMENT
Referring now to the drawings and particularly to FIG. 1, there is illustrated a bottom pressure pouring system according to the present invention and including a pressure tank generally designated as 10 connected to a pneumatic supply line 11 adapted to deliver pneumatic pressure fluid such as compressed air to act on molten metal 12 within a ladle 13. A cover 14 pneumatically closes the pressure tank 10 and carries a pouring tube 15 having its lower end extending into the molten metal 12.
A mold 20 is provided having a drag 21 and a cope 22. The drag 21 is provided with a downwardly opening ingate 24 adapted to align with the pouring tube 15. The cope includes an opening 25 aligned with the ingate 24 for receiving a stopper assembly 28. Suitable riser means 29 may be provided as desired. In the illustrated embodiment the cope and drag are formed of graphite and are held assembled in any suitable manner such as with the clamping cylinders 30 to define a mold cavity 32.
It will be understood that in the bottom pressure pouring process the mold 20 and pressure tank 10 are assembled with the ingate 24 aligned with the pouring tube 15 of the pressure tank. The pressure tank 10 is pressurized through the supply line 11 so that the molten metal 12 in the ladle 13 is forced upwardly through the pouring tube 15 and ingate 24 to fill the mold cavity 32. Suitable means such as an electrical probe (not shown) is provided for terminating the flow of molten metal when the mold cavity has been filled to the desired height. At this point, it is necessary to close the ingate so as to terminate such flow of molten metal and further so as to prevent reverse flow of molten metal from the mold cavity when the mold 20 and pressure tank 10 are separated. A plunger operating cylinder 31 is provided to operate the stopper assembly 28.
In accordance with the present invention, there is provided the improved stopper assembly 28 mounted in the cope 22. As herein illustrated the opening 25 in the cope 22 has an enlarged counterbore 25a at its upper end. The stopper assembly 28 includes a mounting spider 35 having a mounting ring 36 securely mounted in the counterbore 25a of the opening 25. The mounting spider further includes a segmented center spool 38 within the ring 36, having an inner bore 39 and defined by a fixed segment 38[a secured to the mounting ring by a rib 40. The center spool 38 further includes a movable segment 38b radially movable relative to the fixed segment. A rib 41 has a free inner end spaced from the movable segment 38b. In the illustrated embodiment the center spool 38 additionally includes an upper ring portion 38c integrally formed with the fixed segment 38a. Suitable biasing means, here shown as a hairpin spring 45, urge the movable segment 38b radially inwardly toward the fixed segment 38a. For this purpose, a pair of parallel grooves 42, 43 are provided in the outer walls of the fixed segment 38a and 38b respectively for receiving the legs 45a, 45b of the hairpin spring 45. The hairpin spring 45 is held in place with its bite portion 45c against a projection 46 extending inwardly from the mounting ring 36 and secured in any suitable manner such as by fasteners 47. A lower spool disk 48 is fixedly secured to the fixed segment 38a of the center spool 38 in any suitable manner as by fasteners 49. Suitable electrical insulation 37 between the mounting ring 36 and counterbore 25a electrically isolate the stopper assembly from the mold 20.
A stopper 50 is provided having a stopper plunger 51 frictionally held within the inner bore 39 and having an outer diameter larger than the contracted width of the bore 39 so as to bias the movable segment 38a outwardly against the return bias of the hairpin spring 45. A stopper washer 52, 1 of graphite or other suitable material, is carried at the lower end of the stopper plunger within the cavity 32 and adapted to seat against the inner opening of the ingate 24.
It will be understood that the stopper 50 is assembled in the center spool 38 prior to assembly of the cope 22 and drag 21, and guided by the spool disk 48 and upper ring portion 38c. Installation of the stopper plunger within the center spool 38 will spread the fixed segment 38a and movable segment 38b against the return bias of the spring 45. The stopper 50 is frictionally held open, as illustrated in FIG. 1, by the friction created between the stopper plunger 51 with the fixed segment 38a and movable segment 38b as a result of the clamping pressure of the biasing spring 45. Upon filling of the mold cavity, the plunger operating cylinder 31 is actuated to drive the stopper plunger 51 downwardly until the stopper washer 52 seats against the inner end of the ingate 24 thereby stopping further flow of molten metal into the mold cavity 32 and preventing reverse flow of molten metal out of the mold cavity 32 after the mold 20 and pressure tank 10 are separated.