US3188703A - Apparatus for low pressure permanent mold casting - Google Patents

Description

June 15, 1965 F. H. LE JEUNE 3,188,703

APPARATUS FOR LOW PRESSURE PERMANENT MOLD CASTING Filed Aug. 8, 1962 S Sheets-Sheet 1 A BY Q EL

June 15, 1965 F. H. LE JEUNE APPARATUS FOR LOW PRESSURE PERMANENT MOLD CASTING 3 Sheets-Sheet 2 Filed Aug. 8, 1962 June 15, 1965 F. H. LE JEUNE 3,188,703

APPARATUS FOR LOW PRESSURE PERMANENT MOLD CASTING Filed Aug. 8, 1962 3 Sheets-Sheet 3 I I. J,

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- 1 1 l I l I United States Patent 3,188,703 APPARATUS FOR LOW PRESSURE PERMANENT MGLD CASTING Frank H. Le Jeune, Jackson, Mich, assignor to Kelsey- Hayes Company, Romulus, Mich, a corporation of Delaware Filed Aug. 8, 1962, Ser. No. 215,604 8 Claims. (Cl. 22-77) This invention relates to apparatus for casting metals by the low pressure process and particularly to an index machine supporting a plurality of permanent molds in which metal is cast by the low pressure process.

It is an object of the present invention to provide apparatus for casting metal in permanent molds by the low pressure process at relatively high production rates.

It is another object of the present invention to provide an index molding machine supporting a plurality of paired crucibles and molds, wherein means are provided for successively filling the crucibles, pneumatically sealing the furnaces in which the crucibles are located, feeding metal from the crucibles into the molds by air pressure and removing the cast parts from the molds.

It is another object of the present invention to provide apparatus of the above character having means for conveniently opening up the furnaces in which the crucibles are located for the purpose of performing maintenance on the crucibles or the heating elements Within the furnaces.

It is still another object of the present invention to provide a machine of the above character in which the molten metal within the crucibles and the stalks leading from the crucibles to the molds is kept in a molten condition and at a relatively constant temperature and in which scum and other contaminant matter floating on the surface of the metal in the crucibles is not introduced into the molds.

It is still another object of the present invention to provide apparatus of the above character which is of rugged, sturdy construction, which may be relatively inexpensively fabricated for the volume of its productive capacity and which may be used for the mass production of castings by 1 the low pressure permanent mold system in a highly convenient and inexpensive manner.

These and other objects of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein:

: FIGURE 1 is a perspective view, with parts broken away, of apparatus embodying the principles of the pres ent invention;

FIG. 2 is a reduced scale sectional view of the structure illustrated in FIG. 1, taken along the line 2-2 thereof;

FIG. 3 is an enlarged sectional view of the structure illustrated in FIG. 2, taken along the line 33 thereof; and

. FIG. 4 is a sectional view of a portion of the structure illustrated in FIG. 1, taken along the line 4-4 thereof.

Referring now to the drawings, the apparatus of the present invention will be seen to include a large circular table or platform having a plurality of depending legs 12 provided with rollers or Wheels 14 at the ends thereof. The wheels 14 roll in a common circle over the surface of a floor 16 as the table 10 is rotated about its central vertical axis. The legs 12 are spaced radially inwardly from the outer periphery 18 of the table, while braces 20 extend from the lower ends of the legs 12 to the table 'outer periphery 18. A plurality of cross members 22 interconnect the legs 12 to form the legs 12 and the table 14) into a rigid unitized structure. A central column 24, connected to the table 10, is journaled in the floor at its lower end to establish the axis of rotation of the table 10. The table '10 includes a plurality of angularly spaced radially extending beams 26 secured to the column 24 at their inner ends. An annular supporting surface is formed on the table 10 by a plurality of segmentally sector-shaped plates 28 resting on the beams 26 in side-byside relation.

Each of the plates 28 defines a separate work station, as indicated at 28a, 28b, 28c, 28d, 28e, 28 28g, 2811, 281', 28 28k and 28l. A pair of cooperating mold halves 3i) and 32 are positioned at each of the work stations. The lower mold half is supported on the adjacent plate 28 with an annular insulating pad 34 disposed therebetween. The upper mold half 32 is secured to a vertically movable plate 36 having a bracket 38 by which it is attached to a piston rod 40. The piston rod 40 of each Work station extends from and is operated by a hydraulic cylinder 42. A separate cylinder 42 is provided for each work station and each cylinder 42 is carried on a separate support member 44 fastened to the upper ends of three spaced vertical rods 46. The rods 46 pass through the plate 36 and form ways for guiding the vertical travel of the plate 36, thus assuring the proper alignment of the upper mold half 3-2 with the lower mold half 30. The upper mold half 3-2 is thereby adapted to be raised and lowered by its associated cylinder 42 for the purpose of opening the cavitydefined by the mold halves 30 and 32 to remove a part cast therein.

As may be seen in FIG. 3, a separate crucible 48 is supported beneath each of the mold halves 30 adjacent the underside of the associated plate 28. Each crucible 48 is supported by and enclosed within its own thermally and pneumatically scalable enclosure or furnace, generally indicated at 50. Depending from each of the bottom mold halves 30 is a hollow tubular stalk'52, which extends into the subjacent crucible 48. The interior of the upper end of the stalk 52 is tapered inwardly, as indicated at 54. The stalk end 54 is in direct communication with the interior of its mold half 30 and particularly with a portion of the mold half 30 defining a sprue cavity 56. As may be seen in FIG. 3, a heating coil 58 is supported by the annular pad 34 in a position closely spaced around the upper end of the stalk 52 to maintain metal within the stalk in a molten condition.

As further illustrated in FIG. 3, each of the furnaces includes a bottom wall member 60 and an annular enclosing side wall 62. The major portion of the side wall 62 is provided with a ceramic lining 64 for heat insulating purposes. In addition, the lining 64 serves to support heating coils 66. As is indicated in FIG. 3, each of the furnaces 50 has an offset portion 68 which accommodates a spillway or mouth 70 of the crucible 48. The spillway 7b is positioned immediately beneath an inlet opening 72 formed in the adjacent plate 28. Thus, molten metal poured through the opening 72 will fall onto the spillway 70 and run downwardly into the crucible 48. The height to which the crucible is normally filled is indicated by the line 74 and it will thus be seen that this level is substantially above the lower end of the stalk 52.

The crucible 48 is relatively fragile and must be properly supported. For this purpose, a base 75, resting on the bottom wall 60, supports the bottom of the crucible. In addition, a supporting member 76 supports the spillway 70 of the crucible. As may be seen in FIG. 3, an annular bracket 78 of angle iron material is welded to the outer surface of the enclosing side wall 62 and is bolted to the underside of the table 10. The annular furnace side wall 62 is formed with a metal bottom plate 86 to which is secured a continuous seal 82 adapted to sealingly engage the furnace bottom wall 60. An angle iron 8-4 is also welded around the side wall adjacent the lower end thereof and is provided with several spaced brackets 86, each of which pivotally supports a bolt 88 extendable through slots 90 in the furnace bottom wall 60. Nuts 92 and washers 94- are positioned on the ends of the bolts 88 ,to.

Patented June 15, 1965 engage the undersurface of the furnace bottom wall 60 so that, upon tightening of the nuts 92, the furnace bottom' Wall 50 will be drawn upwardly tightly against the seal 82. 7

Means for lowering the bottom wall 60 of a selected one of the furnaces 50 is provided by a pair of spaced,

vertically extending jacks 96 adapted to engagethe underside of the bottom wall '60 of a furnace 59 disposed in vertical alignment therewith. The jacks 96 are provided with rack teeth 98, which mesh with a pair of pinions 99 supported for rotation'about a fixed axis by journalblocks 109. The pinions 99 are co-rotatably associated with a pair of pinions 102 adapted to be rotated by a rack lM which is reciprocable under the influence or" a power cylinder 1%. Thus, upon the horizontal reciprocation of the rack 104, the jacks'96 are raised and lowered. By disengaging its bolts 88 from the slots 99, the bottom wallet) Hydraulic power supply units for operating the power cylinders 42 are indicated generally at 142 as being mounted on the beams 26 inwardly of the plates 28. Electricity for operating the furnaces may be introduced from a suitablepower supply source .througha rotary electrical coupling (not shown) which may be positioned atthe upper end of the column 24. Similarly, compressed air may be admitted to the rotary table 16 through a standard rotary coupling (not shown) also secured .to' the column 24. For sake of clarity, the hydraulic, pneumatic and electrical conduitsor-conductors have been omitted from the drawings. However, FIG. 3 showsa conduit 144 connected to each furnace, through which compressed air may be admitted to the interior of the furnace. A pressure relief .valve 145 is provided'as a safety. measure, protecting against the huild-upof excessive pressure in the furnace.

of a given furnace may-be lowered by the jacks 96 for the I purpose of cleaning. or replacing the crucible 48, repairin or' re lacin insulation material, re airin or replac-,

ing a heating'elemennor performing any other desired maintenance. I

A valve mechanism, generally indicated at 163, is carriedby each of the plates 36 for closing the adjacent inlet opening 72 of itsassociated furnace Sill Thevalve mechanism 108 includes a guide tube lltldepending from the underside of itsplate 36 and a valve stem 112 slidably extending through :the tube 110. A flange 114 is: j formed on the'lower end of theitubelltliand is' engaged by one end ofa spring 116 which bears at its other end against a valve element 118 secured to the lower end of the valve stem 112. When aplate 36 is raisedby its cylinder 42, 'a head 120 on the upper end of its valve'stenr 112 will engage. the upper surface of the plate 36to raise the valve element 118 away from the opening 72." When the plate 36 is again lowered, thespring 116 will urge the valve element 118' against the surface of the plate 28 surrounding the opening 72 to seal the opening 72. In so doing, a lost.rnotion relationship valve stem 112 and the tube 110.

Positioned adjacent the table 10 is a holding furnace 122, from which molten metal is fedthrough a pouring spout 124 into the crucibles 43. A melting furnace 126 will occur between the is also desirably located adjacent the holding furnaceand is used for melting the particular alloy being used. A conduit 128 is provided for the direct flow of metal from the meltingfurnace 126 to the holding furnace 122. The pouring spout 124 of the holding furnace 122 is pivotally mounted, so that its pouring end may be moved between a position immediately above the opening 72 of an adjacent work station and a retracted position clear of the table 10, permitting the table ltlto be indexed to a new position.

Means for indexing the table 10 is illustrated as comprising a large Geneva gear 13% mounted on the column 24. The gear 130 has a plurality of circumferentially spaced, radially extending slots or openings '132.- A rotary'drive plate 134 is provided with anrupstanding pin 136 adapted to enter the slots 132 successively upon the rotation of the plate 134. .The'spacing of the slots 132' and the circle of movement of the .pin136 are such that the pin 136 will leave one slot 132 and enter the next adjacent slot 132 during a given rotation thereof tdincrementally rotate thegear 130 and thus the'colurnn 24 The operation of the apparatus of the present invention 7 will :be largely apparent from the foregoing description of the apparatus. Such operation is repeated sequentially at each work station. The plate v36 at a given work station is first raised, both to raise the upper mold half 32 and to open :the opening 72 of the furnace. The interior of j the mold is cleaned out and any inserts required to be placed therein are inserted in the IIIlOld. Thus, in the production of brake drums, a cast iron-"brake liner may be inserted in the lower mold half 30 for the casting of the drum about the liner; At a succeeding station, the crucihis '48 isjfilled to the desired level'by' the introduction of moltenmetal through the opening 72 from the pouring spout 1-24 of the holding furnace 122. Next, the cylinder 42 of the workstation is operated to lower the plate 36, thereby closing the mold and sealing the furnace. The interior of the furnace is then pressurized with compressed air admitted through the conduit 144. Various pressures maybe utilized but pressures between 7 and 15 pounds per square inch are'normail. The pressurization of the furnace is operable to cause molten metal within the crucible to flow up the stalk 52 to theinteriorof the mold.

' As is well known in rhea-rt of low pressure casting, the

metal will solidify within the mold and any shrinkage resulting from the solidification is takenup by the continued feeding under pressure of metal into the mold.

After the metal within the -mold has been permitted to solidify, the air pressure in its furnace is exhausted and the plate 36 is again raised. At the upper limits of its movement, ejector pins 11-48 dependingfrom the supporting members 44 may be. utilized toassist in the removal of the parts from the mold. 11f the construction of the mold is such that the cast :part 'will'li ft with the upper mold hat-M32, such ejector pins .148 may be used to strike ejector plugs (not'shown) withinthe mold to eject the part from the mold. The mold islt hen. cleaned out and readied for the time when it is next positioned adjacent the holding furnace '122. The operation is, of course, repeated in sequence at each work station. While one crucible is being refilled, molds at the other work stations are being filled through airpressure and the cast parts' are solidifying.

I-t*will be seen that the" apparatus of the presentinvem tion permits. the leaving of-a sizable heel of molten metal within each crucible 48 to stabilize the temperature wit-hi n. each furnace, yet each crucible is consider-ably s'mal-lerland less expensive to fabricate, heat and main-' tain than crucibles which have heretofore been used in and table 10 to which it is fixed. Thedrive plate 134 is driven in rotation bya motor 138 through a gearreduction mechanism 140. There are twelve of the. slots 1321.

and each corresponds in angular position to one of the work stations 28a, 28b, 28c, 28d, 28c, 281, 28g, 28h, 28L 28f, 28k and 28]. Thus, the motor 138 may be turned off during a period in which the pm 136 has left one of the slots 132 and prior to its reentry into a'new slot 132 and, during this period, one of the work stations will be in a position adjacent the holding furnace 122. In such p0sition, one of the work stations will also lie 'above'the jacks casting-by the low pressure process, Still, the'oxides or other contaminant matter=within each crucible 48 will float on the top of the metal within the crucible and, by'

virtue of the fact that the inlet of the stalk 52 is positionedbeheath thisleve-l, such contaminants-will not be introduced'into the interior of the mold.

' While it will be apparent that the preferred embodiment herein illustratedis well calculated to fulfillthe objects above stated,"it will be appreciated that the-invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. Casting apparatus including a rotary table, a plurality of furnaces carried by said table in angularly spaced relation, a crucible in each of said furnaces, a plurality of molds carried by said table in paired relation to said furnaces, means connecting each of said molds to the crucible in the furnace to which it is paired, a stationary holding furnace, means for successively filling the furnaces on said table with molten metal from said holding furnace as said table is indexed, and means for pressurizing said furnaces.

2. The structure set forth in claim 1 including a plurality of lifting mechanisms on said table disposed one above each of said molds, each lifting mechanism 'being connected to an upper part of its adjacent mold for openiug said molds to remove parts cast therein.

3. Casting apparatus including a rotary table, a plurality of furnaces depending from said table in angularly spaced relation, a crucible in each of said furnaces, a plurality of molds resting on said table and each being arranged in a position directly above one of said furnaces, means connecting each mold to the crucible of the furnace directly beneath it, means for pressurizing each of said furnaces, a stationary holding furnace, means for successively filling the furnaces on said table with molten metal from said holding furnace as said table is indexed, and closable inlet means on each of said furnaces through which metal may be poured into said crucibles.

4. The structure set forth in claim 3 in which each of the furnaces on said table is provided with a bot-tom Wall on which its .crucible rests and including means for disengaging each of said bottom Walls from the remaining portion of said furnaces, and a stationary lowering mechanism adapted to support and lower the bottom wall of a furnace in juxtaposition thereto.

5. Casting apparatus including a rotary table, a pinrality of furnaces carried by said table, a cruciblein each of said furnaces, a plurality of molds disposed on said table, each in a position above one of said furnaces, a stalk depending from each of said molds into the crucible of its adjacent furnace, means for pressurizing each of said furnaces to cause molten metal within the crucible thereof to flow upwardly through said stalks into the molds, and a stationary furnace adjacent the periphery of said table for filling the crucibles of the furnaces on said table.

6. The structure set forth in claim 5 including a heating element surrounding each of said stalks, and a plurality of heating elements in each of said furnaces to maintain metal in said stalks and said crucibles in .a molten condition.

7. Casting apparatus including a rotary table, a plurality of furnaces carried by said table and each having an inlet opening at its upper end, a crucible in each of said furnaces, a plurality of molds on said table disposed one above each of said furnaces and connected to the crucible in its adjacent furnace, a separate lifting mechanism for each of said molds connected to an upper portion of one of said molds, valve means associated with each of said lifting mechanisms operable to automatically close the inlet opening of its adjacent furnace upon the lowering of said upper mold portion, means for pressurizing each of said furnaces, and a stationary furnace adjacent the periphery of said table for successively filling the crucibles carried by said table.

8. The structure set forth in claim 5 including means for incrementally advancing said table in rotation to suc cessively move the furnaces carried by said table to a position adjacent said stationary furnace.

References Cited by the Examiner UNITED STATES PATENTS 1,913,945 6/ 33 Morris et al 22-77 2,195,360 3/40 Daesen 2269 2,7 43,491 5/56 Berry 22-77 2,912,728 1 1/59 Sylvester 22--69 MICHAEL V. BRINDISI, Primary Examiner.

Claims (1)

1. CASTING APPARATUS INCLUDING A ROTARY TABLE, A PLURALITY OF FURNACES CARRIED BY SAID TABLE IN ANGULARLY SPACED RELATION, A CRUCIBLE IN EACH OF SAID FURNACES, A PLURALITY OF MOLDS CARRIED BY SAID TABLE IN PAIRED RELATION TO SAID FURNACES, MEANS CONNECTING EACH OF SAID MOLDS TO THE CRUCIBLE IN THE FURNACE TO WHICH IT IS PAIRED, A STATIONARY HOLDING FURNACE, MEANS FOR SUCCESSIVELY FILLING THE FURNACES ON SAID TABLE WITH MOLTEN METAL FROM SAID HOLDING FURNACE AS SAID TABLE IS INDEXED, AND MEANS FOR PRESSURIZING SAID FURNACES.

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