US2852822A

US2852822A - Vacuum seal for pressure pouring apparatus

Info

Publication number: US2852822A
Application number: US527921A
Authority: US
Inventors: Charles F Strom
Original assignee: Griffin Wheel Co Inc
Current assignee: Griffin Wheel Co Inc
Priority date: 1955-08-12
Filing date: 1955-08-12
Publication date: 1958-09-23
Anticipated expiration: 1975-09-23

Description

United Statesy Patent Office A VACUUM SEAL FUR PRESSURE POURING APPARATUS Charles F. Strom, Glen Ellyn, lll., assignor to Griffin Wheel Company, Chicago, Ill., a corporation of Delan ware Application August 12, 1955, Serial No. 527,921

9 Claims. (Cl. 22-69) This invention relates to a method and means for pouring castings and more particularly to the casting of steel by forcing molten steel under pressure upwardly into a mold.

In the pressure casting of molten metal, the metal is forced from a ladle upwardly through a tubular ceramic pouring spout into a mold responsive to a rise in air pressure within a pressure chamber containing the ladle.

Due to the porous wall structure of the pouring spout,

air is sometimes forced through the Wall of the spout into the metal passing upwardly through the spout, thereby causing the production of faulty or defective castings.

it is, therefore, an object of the invention to provide a pressure pouring apparatus and method of operating same embodying means effective to prevent or materially reduce an escape of air through the wall of a pouring spout into a body of molten steel tlowing therethrough,

Another object of the invention resides in the provision of a pressure casting apparatus in which the upper end of the tubular pouring spout is cemented within a metallic head and denes therewith an annular vacuum chamber communicating with an air passageway leading to a vacuum pump, whereby any air leaking through the cement between the spout and head is drawn therefrom into said chamber instead of passing inwardly through the wall of the spout into the molten steel.

The invention embodies other novel features, details of construction and arrangement of parts which are hereinafter set forth in the specification and claims `and illustrated in the accompanying drawing, wherein:

Figure 1 is a central vertical sectional View of the apn paratus utilizing the preferred embodiment of the invention; and t Figure 2 is an enlarged view of a portion of the apparatus illustrated in Figure 1. i

Referring now to the drawings for a better understanding of the invention, the pressure pouring apparatus is shown as comprising a cover 6 adapted to be detachably secured to a housing 10 to form therewith a sealed chamber 10a, the housing being provided with an air conduit leading to a suitable source of air under pressure. The housing is adapted to enclose a ladle 3 lled with molten steel 4 which is forced upwardly through a tubular pouring spout or tube 7 into the cavity of a mold generally designated 8 responsive to an increase in air pressure within the housing.

The pouring spout or tube 7 is formed of a porous gas permeable ceramic material and is secured at its upper end within a bore 9 in a metallic head 11 by means of a suitable Wet type air setting refractory mix comprising,-

for example:

5% combined water.

As illustrated in Figure 2, the mix is adapted to be worked to a putty consistency and inserted downwardly between the bore 9 of the head 11 and the pouring spout 7 to form first a lower refractory section 13, the mix being retained against downward movement out of the head by means of a sealer ring (not shown) snugly encircling the spout and in ilush engagement against the bottom of the head. A retainer ring 14 is then supported within the bore 9 in vertically spaced relation. to the lower section 13 by means of circumferentially spaced rods 16 to define an annular vacuum chamber 17 surrounding the spout.

Another body of porous gas permeable refractory mix is then inserted into the bore 9 to form an upper refractory section 18 between the head and the spout; after which the mix may be dried and set by heating the head by means of a flame. The upper section 118 preferably extends upwardly between the spout 7 and the inner peripheral surface of a graphite ring 19 secured to the upper side of the head 11 by means of cap screws 21.

After the pouring spout 7 has been cemented to the head 11, a non-porous gas impermeable glaze coating 22 is applied to the outer surface of the spout and radially across the lowerend of the lower refractory section 13 onto the lower face of the head to prevent a leakage of air through the wall of the spout into molten steel passing therethrough. The glaze coating may extend down wardly to within 18 or 20 inches from the lower end of the spout and at least down to the level of' the molten metal in the ladle as shown in Figure 1. A suitable glaze coating may comprise, for example, the following mix:

Percent PbO 6 KZO 7 B203 l1 The head 11 is journaled for rotational adjustment in a wedge-shaped ring 23 continuously welded at 24 to the cover 6 formed with an aperture 26 to receive the lower end of the head. An annular ange 27 is formed on the `upper end of the head for annular abutting engagement Patented Sept. 23, 1958` tion to an inclined position to prevent entrapment of air within the mold' cavity as the latter is being filled with molten metal, as disclosed in the patent applications heretofore referred to.

An air passageway 33 is provided in the head 11 leading from the vacuum chamber 17 to a pipe 34 which is connected to a conventional vacuum pump 36 employed to exhaust air from said chamber. As the pouring spout 7, upper and lower

refractory sections

18 and 13, glaze coating 22, head 11, and graphite ring 19 have different coefficients of expansion, it is diicult to maintain an airtight seal between the pouring.. spout and the head during operation of the pouring apparatus. This is because as these three elements, expand and contract at ditierent rates, there developsl between the glaze coating4 22y and The IQWQI surface, 15. of head 11 a minute orice 25 which permits pressure to pass from housing chamber lila between the housing and tube and thence through the porous wall of the tube at a place on the tube above the glaze coating where the tube is gas permeable. By providiugl any annular. vacuumi'cha'mberf17 ybetween the ypouringl spout and the headgitl is apparent that any air leale ingthereinto through orilicev 2-5 from-the interior of the housing past thev lower refractory section 13 will be withdrawn therefromi'by the vacuum. pump. 36, It will also beynoted that'` the` vacuumpump 36. could be omitted from the structure, if desired, whereby air under pressure leaking, from the interior of the housing into the vacuum chamber would be exhaustedtothe atmosphere. It has been found, hovvever, that the pump 36 affords positive protection'. against leakage of' air' into the tube through refractory section 13.

Whiley the invention-has: been shown in but one form, it is obvious'tothose-skilled in the art that it isnot so limited but is; susceptible;l offvarious; changesf and moditications without departing from the spirit and scope of the claimed invention.

I claim:

l. In a pressure pouringlv apparatus of the typewherein liquid material is forced. b'ythe; exertion ofsuperatmos pheric gas pressure thereagainst from a gasftight container to a molddisposed without the container, theA combination of: means for introducing.PressureV gas. into the container, a porous gas permeablepouring; tube having one end disposed to extend through au aperture in. the container andI into thematerialto ibeypoured andihaving the other endv in communication with the mold,4v a" gas'impermeablecoatingl onthe tube extendingyfrom the material to 'the container-aperture, andymeans toimaintain in the apertureofY thefcontainer externally' of the tuibefa pressure value no greaterrthan' atmospheric pressurevto prevent the pressure gas from permeating the tube.

2.V In a pressure pouring apparatus of the type wherein' liquid-material is forced bythe exertion of superatmospheric gas"pressure"thereagainst from` a gas-tight container'V structure to a mold-'disposed without the container structure, thecombinationof: means for'introducing pressurel gas-into the containerv structure; a porous gas permeable pouring tube having one end'disposedto extendy through lan aperture in the container structure and-'into the material to be poured and having the other endfl in communicationwith the mold, a non-porousl gas impermeable coatingvv on. the-v tube extendingV from the material to. be poured to the` container kstructure at said aperture and definingy therewithwanj orifice through which pressure gas. in the container struct-ure can pass to the tube, said tube and container structure delining. therebetweenin said aperture an annular airchamber surrounding the outer surface ofthe tube, andin said chamber being at atmosphericpressure or less, to prevent pressure gas from permeating the tube.

3. A pressurepouring. apparatus accordi-ngl to claim 2, wherein said container structure presents a passageway therein communicating with saidchamber, and wherein said apparatus includesfpump--means communicating with 2t said passageway and operable to exhaust gas from said chamber.

4. A pressure pouring apparatus according to claim 2, wherein said chamber is disposed between and defined by a pair of axially spaced annular sections of a composition which serves to support the tube within the aperture of said container structure.

5. In a pressure pouring apparatus of the type wherein molten steel is forced by the exertion of gas pressure thereagainst from a gas-tight container to a mold disposed without the container, the combination of: means 'for introducing pressure gas into the container, a mounting member disposed within' an aperture of the container and having a `bore extending therethrough, a gas-tight seal between the container and the member, a` porous gas permeable pouring tube having one end communi-l cating with thef mold and having the other end disposed to extendy through the bore of the member andA into the material to be poured, a non-porous gas impermeable coating'l onthe tube extending from the material to be poured tothe member, and means to maintain within the bore of the member externally of the tube above said coating a pressure value no greater than atmospheric pressure to prevent the pressure gas from permeating the tube.

6. Ina pressure pouring apparatus offy the/type whereinmoltensteel! is' forced by the application of pressurel thereagainst from a gasftight container to a mold dis@ posed without theV container, the combination of: means for introducingl pressure gas into the container, amounting` member disposedfwithiny anA aperture of the-'container and having abore extending therethrough-'from top' to bottom, av gas-tight seal between the memberfand the `container, a porous gas permeable pouringl tube'having one endv communicating with the mold and the other end* dis` posed to extend' through 'the bore ofthe member. andfinto the container, a non-porous gas: impermeableicoating on the tube extending 'from thematerial: tofbe poured onto the container, said member and." said tubef presenting therebetween in said Ybore'y an *annular ehamber surround'- ing the outer surface ofthe tube; and means toy maintain in said chamber a pressure'valuefnotgreaterz than: atmospheric pressure to prevent the pressure," gas' from permeating the tube. Y

7. A pressure pouring apparatus. according to claim' 6, wherein the chamber inthe? bore ofrthe member is dis posed'between and dened by ap'air of axiallyy spacedl annular-'sections of ak composition which. serve to support the tube withinsaid` bore.

8. A pressure pouringapparatus according to claim'6, wherein. said member presentsla passagewaytherein communicating with said chamber, and: wherein said'A ap paratus includesA pump means communicating` with said passageway and` operable to exhaust, gas: from said chamber.

9.- In a pressure pouring'apparatus of the tube wherein molten steel is forced by the exertion of gas pressure thereagain'st from a gas-tight' container to a1 mold disposed without the container, the combination of: means for introducing1 pressure gask into` the container, a mounting member mounted:y withinA an aperture-- of.; the container end; disposed to extendythroughv the-'bore of the member` andyinto thev container, axiallyl spacedannularsections of a refractory mix supportinggthetube in the bore of-thc member and definingV between the outerl surface. of the tube and the inner surface of the member an yannular chamber, a non-porous gas impermeable coating on the tube extending from thez material to be-poured onto the member-and defining with-the; member an orifice through which` pressure gas' canpass from; thelcontainer` to thetube, and means for maintaining a pressure value inthechamber which is no greater than atmospheric pressure to prevent pressure 4gas from permeating said means including a passageway in said member and means to exhaust gas from said chamber through said passageway.

References Cited in the le of this patent UNITED STATES PATENTS 6 Saunders Ian. 5, 1926 Baily Sept. 3, 1929 Summey Nov. 10, 1936 Daesen Mar. 26, 1940 Poulter June 26, 1945 Foster Feb. 8, 1949 Hubbard et al. Oct. 18, 1949 FOREIGN PATENTS Great Britain Dec. 23, 1946 Great Britain Mar. 16, 1955 Great Britain Nov. 17, 1954 UNITED STATES PATENT oEETCE CERTIFICATE CE CORRECTION Patent No 2,852y822 September 23, 1958 Charles E, Strom It is herebjST certified that error appears in the-prnted specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, line 2, after "permeat'ing" insert m the tube m.,

Signed and sealed this 10th day of February 195% (SEAT.)

Attest:

KARL HMMLINE ROBERT C. WATSON Commissioner of Patents Attesting,r Ocer