CA1076319A - Method and apparatus for making castings - Google Patents
Method and apparatus for making castingsInfo
- Publication number
- CA1076319A CA1076319A CA280,698A CA280698A CA1076319A CA 1076319 A CA1076319 A CA 1076319A CA 280698 A CA280698 A CA 280698A CA 1076319 A CA1076319 A CA 1076319A
- Authority
- CA
- Canada
- Prior art keywords
- chamber
- mold
- nodularizing
- pouring
- molten metal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D35/00—Equipment for conveying molten metal into beds or moulds
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
- B22D1/007—Treatment of the fused masses in the supply runners
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Molds, Cores, And Manufacturing Methods Thereof (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A method and apparatus for making metal castings and particularly nodular iron castings. The castings are made in molds, each having a chamber in the upper portions of the mold, the chamber being connected by gating passages to the casting cavities. In the manufacture of nodular iron castings, a nodu-larizing agent as placed in the chamber. The chamber is open at the top and the molten metal flows from the chamber into the gating passages of the mold through openings that are disposed above the floor of the chamber. During the pouring operation the upper surface of the mold, including the open top of the chamber, is closed by a refractory sealing member having a pas-sage through which the molten metal can flow. This passage is connected to a launder or the like to which molten metal is sup-plied by a furnace. At the end of the launder there is a ver-tical conduit that extends downwardly and provides a closed conduit for the vertical flow of metal from the launder through the refractory sealing member into the chamber. The molten metal is supplied to the launder from the furnace at a rate faster than the rate at which the metal flows out of the cham-ber into the gating passages. Thus, during the pouring opera-tion, a head metal is formed extending from the launder through the conduit and the seal and into the chamber, all of which may be filled with molten metal for a short period of time during the pouring process. The molds are moved step-by-step succes-sively along a pouring rail, past a station where a nodularizing agent is placed into the chamber, if nodular iron is being pro-duced, and another station where molten metal is automatically poured into the chamber through the refractory seal member that is positioned in contact with the top of the mold when the mold is stopped at the pouring station and then after pouring is completed is removed from contact with the mold to permit the mold to be advanced and another mold positioned at the pouring station.
A method and apparatus for making metal castings and particularly nodular iron castings. The castings are made in molds, each having a chamber in the upper portions of the mold, the chamber being connected by gating passages to the casting cavities. In the manufacture of nodular iron castings, a nodu-larizing agent as placed in the chamber. The chamber is open at the top and the molten metal flows from the chamber into the gating passages of the mold through openings that are disposed above the floor of the chamber. During the pouring operation the upper surface of the mold, including the open top of the chamber, is closed by a refractory sealing member having a pas-sage through which the molten metal can flow. This passage is connected to a launder or the like to which molten metal is sup-plied by a furnace. At the end of the launder there is a ver-tical conduit that extends downwardly and provides a closed conduit for the vertical flow of metal from the launder through the refractory sealing member into the chamber. The molten metal is supplied to the launder from the furnace at a rate faster than the rate at which the metal flows out of the cham-ber into the gating passages. Thus, during the pouring opera-tion, a head metal is formed extending from the launder through the conduit and the seal and into the chamber, all of which may be filled with molten metal for a short period of time during the pouring process. The molds are moved step-by-step succes-sively along a pouring rail, past a station where a nodularizing agent is placed into the chamber, if nodular iron is being pro-duced, and another station where molten metal is automatically poured into the chamber through the refractory seal member that is positioned in contact with the top of the mold when the mold is stopped at the pouring station and then after pouring is completed is removed from contact with the mold to permit the mold to be advanced and another mold positioned at the pouring station.
Description
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This invention relates to the production of metal castings and is described herein as applied to the production of ductile iron castings, where the invention is especially advantageous. Ductile iron is also referred to as nodular or spheroidal graphite cast iron and ductile iron castings are highly advantageous as compared to ~ray iron castings because of their ductility and because they have increased tensile strength and resistance to impact as compared to ordinary gray iron castings. Also, ductile iron has much better castability characteristics than steel and for an increasing number of uses ductile iron castings can be used where steel castirlgs or forg-in~s were formerly required.
Ductile iron is produced by innoculating molten iron of the proper composition with a nodularizing agent that causes the graphite flakes that are ordinarily present in gray cast iron to assume a nodular or spheroidal form. It is this change in the characteristic of the graphite present in the cast iron that appears to give the ductile iron its advantageous charac-teristics. Numerous nodularizers are known; they are ordinarily alloys, compounds or mixtures embodying magnesium, calcium, sod-ium, lithium, strontium, barium, cesium, and other similar metals. Magnesium is the preferred nodularizing agent because of its effectiveness and availability and because its cost is less than other rarer metals that can be used. Magnesium and the other nodularizing agents, in addition to their cost, pre-sent problems because they have boiling points below the pouring temperature of cast iron and because they are easily oxidized.
Because of these characteristics, attempts to add nodularizing agents in the conventional manners employed in adding alloying agents to molten iron, present serious difficulties in tha-t the addition of the agents to a ladle, for example, is likely to result in a violent reaction with a pyrotechnic display that -1- ~
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results in a hazard to foundry personnel and serious atmospheric contaminationO Also, some of the nodularizing agent is o~idiz-ed or otherwise lost, making it necessary to supply nodularizing agents in amounts in e~cess of the amounts required to effect nodularization. Also "fading" or a reduction in the amount of nodularizing agent in solution in the iron may take place dur-ing the time that elapses between the innoculation of the iron with the agent and the time the iron containing the nodulariz-ing agent reaches the mold, causing unreliability and inconsis-tency in the results.
Attempts have been made to eliminate these problemswith varying degrees of success. For example, the nodularizing agent has been alloyed with another metal in order to slow down the reaction that takes place when the nodularizing agent en-counters molten iron. This system results in increased cost for a given weight of nodularizing agent and further, the alloy-ing metal employed may have an undesired effect on the casting.
According to another method, a special intermediate chamber in-to which the nodularizing agent is disposed and through which ~0 the molten metal flows is interposed between the ladle and the mold. The chamber in which the nodularizing agent is disposed can be closed and the pyrotechnic display eliminated. However, fading can occur during the travel of the iron from the chamber in which the nodularizing aaent is disposed to the mold and scrap losses are freauently increased because of iron remaining in the intermediate chamber and passages. secause of the in-creased scrap losses, correspondingly increased amounts of nodu-larizing agents must be employed, adding to the cost of the casting. A system of this type is illustrated in United States Patent ~o. 3,819,365, issued June 25, 1974.
Another system, which is disclosed in Canadian Patent No. 925,265 involves the use of an intermediate chamber in the ~6~7~3~
mold itself in which the nodularizing agent is disposed. This system has met with some success but it is open to objection for various reasons, including the ~act that since the nodularizing agent is placed within the mold, it is not possible to inspect the mold immediately prior to pouring to determine that the nodularizing agent is, in fact, in place. Also, the necessity of providing an intermediate chamber and additional gating with-in the mold limits the size or number of the mold cavity or cavi-ties that may be included in a mold of given external dimensions.
This reduces the productive capacity of the apparatus and makes it necessary to employ a greater number of molds for a given production of castings. While this method eliminates the prob-lem of fading and also avoids pyrotechnics, another difficulty has arisen because results are sometimes inconsistent insofar as the characteristics of the cast metal are concerned. The intermediate chamber in the mold also requires the pouring of metal in an amount greater than would be required in a conven-tional mold within an intermediate chamber and this additional metal makes it necessary to supply a correspondingly increased amount of nodularizing agent. Both of these factors increase the cost of the castings.
A ~eneral object of the present invention is to pro-vide a method and apparatus for supplying an addition agent such as a nodularizing agent in the casting of molten metal such as iron in which the problems noted above are largely eliminated.
Another object is to provide an improved method and apparatus for making ductile iron castings. A further object is the pro~
vision of a method and apparatus for making iron castings that is particularly adapted to automatic molding and automatic pour-ing techniques whereby a high rate of production, reasonablecosts and excellent uniformity of quality of castings can be obtained. Another object is the provision of a method and 1~63~9 apparatus for makin~ metal castings in which it is not necessar~
to employ a pouring cup and in which defects in castinys due to aspiration of air into the mold passages during pouring and de-fects due to slag inclusions in the metal are minimized. An-other object is the provision of a method and apparatus for pro-ducing iron castings that is particularly adapted for use with vertically parted molds.
Briefly, according to the present invention, a chamber is provided in the upper portion of the mold in which the cast-ing is to be formed. An innoculating agent is deposited in thechamber and the molten metal flows into the chamber as it is poured ~rom an appropriate supply into the mold. The chamber in which the nodularizing agent is disposed is open at the top and is connected to appropriate runners, sprues and the like leading to the mold cavity or cavities in which the castings are produced. ~t the time of pouring the molten metal, the nod-ularizing agent is disposed in the chamber and the open top of the chamber is closed by a separately formed refractory seal that engages the top surface of the mold surrounding the cavity.
The metal flows through a launder from a furnace containing the molten metal and which embodies a closed conduit that extends through the seal. The metal is deposited by the conduit in a pouring basin formed in the mold and also closed by the seal.
From the pourin~ basin the metal flows to the chamber in which the nodularizing agent is disposed. From this chamber the molten metal flows through gating passages such as runners, sprues and the like to the mold cavity or cavities in which the castings are formed. The seal prevents the discharge of noxious fumes into the atmosphere during the pouriny operation and also eliminates hazards that miyht otherwise occur from the pyro-technics that can take place when molten iron encounters a nodu-larizing agent containing magnesium. The seal and associated ~0763~9 passages in the launder also provide a head of molten metal over the pouring basin which minimizes slag inclusions and a-spiration of air into the castings without requiring additional passa~es or chambers in the mold itsel~ After the pouring operation has been completed, the seal and the conduit that extends through it are disen~aged from the mold and the mold is moved away from the pouring apparatus where the metal is permitted to cool and solidify and where, thereafter, the castings are removed from the mold and preferably checked and tested in accordance with usual practices. Preferably, a ~lurality of molds are moved successively to a pouring station, ~he~e each mold is stopped, enga~ed by the seal, poured, the seal disengaged from it, and the mold then advanced and an-other mold moved to the pouring station.
The invention consists in the provision o~ apparatus for making iron castings comprising a mold having bottom, side and top surfaces, a casting cavity, a chamber in the upper por-tion of said mold and a gating passage connecting the chamber with the casting cavity, the chamber having a floor and side 20 ~alls and being open at its top, the area of the open top of the chamber being at least substantially equal to the area o~
~he floor thereof, and said gating passage being connected to said ch~mbex at a level above the floor thereof, the level of the connection of said gating passage to said chamber also be-ing above the uppermost portion of the casting cavit~, said chamber being adapted to have a nodularizing agent deposited therein through the open top thereof, the open top of the chamber being disposed at the level of the adjacent top sur-face of the mold, a sealing member composed of refractory ma-terial and adapted to make sealing engagement with the topsurface of the mold surrounding the open top of said chamber, l -5 ~
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means for placing said sealing member in sealing engagement with the top surface of the mold and means for disengaging it therefrom, a conduit extending through said sealing member and adapted to deliver molten metal to said chamber, a launder having a passage for molten metal leading to said conduit and means for supplyi~g molten metal to said passage in said laun-der and thereby supplying molten metal to said conduit and said chamber.
The invention also consists in ~he provision of a method of making metal castings comprising providing a mold ~aving bottom and side and top surfaces, a casting cavity, a chamber and a gating passage providing communication between said chamber and said mold, sai.d chamber having a floor and side walls and being disposed in the upper portion of said mold and being open at its top, the floor of said chamber he-ing disposed at a level above the uppermost portion of the casting cavity, engaging the top surface of the mold with a seal that makes sealing contact with the top surface of the mold surrounding said chamber, and supplying said mold with sufficient molten metal to fill the casting cavity by causing said molten metal to flow into said mold throug~ a downwardly extending closed conduit and an opening extending through said seal and in communication with said chamber, the metal flowing downwardly from said chamber to the casting cavity.
Figure 1 is a plan view of a preferred form of ap-paratus made according to the invention and adapted to perform the method of the invention;
Figure ~ is an end elevational view of the apparatus shown in Figure l;
Figure 3 is a vertical section o~ the apparatus, taken as indicated by line 3-3 of Figure l;
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~763~9 Figure 4 is a fragmentary section to an enlarged scale, showing the launder and the upper part of the mold shown in Figure 3;
Figure 5 is a section at right angles to Figure 4 and taken along line 5-5 of Figure 4;
Figure 6 is a sectional detail showing the launder of the apparatus of Figure 1 in conjunction with fragmentary portions of the furnace and the mold, the launder being shown in its raised position;
Figure 7 is a fragmentary sectional view of the parts shown in Figure 6 but illustrating the launder in pouring - -Sh-i~763~
position:
Figure 8 is a phantom view illustrating the cavities and passages of a mold for use in the apparatus in carrying out the process;
Figure 9 is a top plan view of the mold shown in Figure 8;
Figure 10 is a section through the mold of Figure 9, taken along line 10-10 of Figure 9.
As illustrated somewhat diagrammatically in Figures 1 and 2 of the drawings, a preferred form of apparatus for carry-ing out the invention comprises a pouring rail 10 at the entry cnd of which there is disposed an automatic molding machine 11 which may be any conventional type of molding machine, such as the "Disamatic" machine produced by Dansk Industri Syndikat A/S.
This machine produces molds M successively and deposits them on the pouring rail. With this type of machine, each following mold is in engagement with a preceding mold and, in turn, is engaged by another following mold. A hydraulic ram associated with the molding machine pushes the whole series of molds along ~0 the pouring rail simultaneously, each mold being advanced a pre-determined distance and then remaining stationary while another mold is deposited on the pouring rail, after which the entire series is again advanced. As will appear below, it is during the intervals when the molds are stationary that the nodulariz- !
ing agent is introduced into the molds and the molds are poured.
As the molds travel along the pouring rail 10 they pass beneath an alloy dispensing mechanism 12 which may be of a ~nown type and is arranged to deposit a predetermined amount of nodu-larizing agent in each mold. Each mold stops in register with the alloy dispensing mechanism and while it is stopped, a pre-determined amount of alloy is deposited into the nodularizing chamber of the mold. Thereafter, the mold is advanced beyond a~k ;3~3 the alloy dispensing mechanism 12 and another mold is advanced into a position in registration with the alloy aispensing mech-anism where it, in turn, will receive a desired amount of nodu-larizing material.
m e molds continue to be advanced step-by-step down the pourin~ rail, passing a furnace indicated in general at 14, which is also of known construction, and which is arranged to deposit a predetermined amount of molten iron in a predetermined time into each mold as it stops on the pouring rail opposite the furnace. The molten metal is discharged from the furnace into a launder, indicated in general at 16, and from the launder the metal flows by gravity into the mold and to the casting cavities thereo~ as described in detail below. Each mold stops lon~ enough opposite the furnace to permit the discharge of the required amount of iron into it and after this has taken place, the molds are all advanced another step and a following mold is disposed in pouring position opposite the furnace.
After the furnace, the molds continue on ln their step-by-step movement down the pouring rail where the castings are solidified, then into a coolin~ conveyor of known construc-tion. Ultimately, the castings are removed from the molds, trimmed and preferably inspected and tested. Conventional ex-haust hoods as indicated at 17 and 18 may be placed over the conveyor as desired.
Molten iron may be supplied to the furnace 14 by con~
ventional melting furnaces, not shown, disposed on the other side of the furnace 14 from the pouring rail.
While the invention may be utilized with molds of vari-ous types, the invention is described herein as used in conjunc-tion with the production of castings in vertically partedflaskless molds, a typical mold of this type being ~hown in Figures 8, 9 and 10.
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As shown in these figures, each mold M may comprise two parts 20 and 21, the parting plane of the two parts being indicated at 22. The mold is shown as embodying a plurality of (in this case twelve) casting cavities 24 that are connected by ingates 25, to downsprues 26 which extend downwardly from the runners 30. The runners 30 extend generally horizontally from a centrally disposed nodularizing chamber 31 in which a nodular-izing agent indicated at 32 (Figure 10) is disposed. It will be noted that the exits 33 from the chamber 31 to the runners 30 are elevated above the floor 35 of the chamber 31. This en-sures that the molten iron will react properly with the nodular-izing agent in the chamber 31 before ~lowing into the runners 30 and thence to the downsprues 26, lateral ingates 25 and casting cavities 24.
As shown particularly in Figures 4, 9 and 10, the nod-ularizing chamber 31 is disposed in the upper portion of the mold and is open at the top. The upper edges of the side walls 36 of chamber 31 lie in the same plane as the top surface 37 of the mold.
In order to ensure that the molten iron will flow smoothly and uniformly into the nodularizing chamber 31, the upper portion of the mold is also provided with a shallow poux-ing basin 39. The top edges of the walls 40 of the pouring basin lie in the same plane as the top edges of the side walls of chamber 31, which is the plane of the top surface 37 of the mold.
With this construction of the mold it is possible to seal the open tops of the nodularizing chamber 31 and the pour-ing basin 39 by a refractory seal 41 (Figures 4-8) during the pouring operation. The fact that the chambers and pouring basins in the molds are open make it possible to check visually the nodularizing chambers before pouring to determine that the ~L~763~
nodularizing agent is present therein~ Also, the refractory seal 41 seals in the products of the reaction between the nodu-larizing agent and the molten iron, thus protecting the environ-ment and personnel from hazards that might otherwise be en-cou~tered. Furthermore, the location of the open topped pouring basin and nodularizing chamber adjacent the top of the mold results in a saving of space that would otherwise be occupied in the mold if these chambers were incorporated in the interior of the mold. Thus, the size and number of the casting cavity or cavities that can be incorporated in a mold of a given size is not substantially reduced as compared to conventional molds by the use of the present invention; the reduction in size and/or number of castin~s possible with a given size of mold that occurs with systems in which the nodularizing chamber is disposed internally of the mold is obviated.
As explained below with particular reerence to Fig-ures 3-7, the present invention lends itself advantageously to automatic pouring of the molten metal into the molds. ~ccord-ing to a preferred form of the present invention, the furnace ~0 14 is of a known type that is adapted to deliver accurately controlled quantities of molten iron at accurately controlled temperatures within a predetermined period of time. Furnaces of this type are known in the art and are commercially avail-able. Suitable type furnaces and controls are illustrated and described, for example, in United States Patents Nos~ 3,395,833 and 3,499,580, to which reference is hereby made~ Furnaces of this general type are manufactured by Inductotherm Corporation of Rancocos, ~ew ~ersey, U.S.A., and are marketed under the tradename "Autopour". The furnace comprises a suitable pressure vessel 42 that is usually round in cross section and which is mounted on a movable carriage 43 so that its position can be adjusted transversely of the pouring rail 10 in order to locate ~7~3.~
the furnace accurately with respect to the pouring basins of the molds as they are successively moved along the rails. The furnace is provided with heating elements and appropriate con-trols to keep the molten iron within it at a temperature that is accurately controlled. The furnace is under a con-trolled super-atmospheric pressure of compressed air, the air pressure being controlled by means of a detecting device positioned at a fixed level beneath the molten iron within the furnace. The detecting device measures the static pressure in the molten metal at the level of the detecting device at all times. This pressure is maintained at desired values by automatic controls even though the level of molten iron in the furnace may vary within a normal operating range. Since the mode of operation and controls of various types of pressure pouring devices are well known, the controls are not described in detail herein.
As shown in Figures 3, 6 and 7, the furnace has a pouring spout 44 that is connected to a conduit 45 that extends downwardly into the furnace vessel 42 ~o an open end disposed substantially below the normal level of molten metal within the vessel 42. Molten metal is supplied to the interior of the vessel 42 through an inlet 46, a typical level of molten metal in the vessel 42 being indicated by the dotted line in Figure 3.
The upper end of the conduit 45 terminates in the pouring spout 44, which is shown in the form of a trough. Slightly below the juncture of the conduit 45 and the pouring spout 44, there is a branch conduit 47 that is open at the top and functions to limit the ferrostatic head of the molten metal that can be developed in the conduit 45. This arrangement assists in main-taining the rate of flow of molten metal in the conduit 45 sub-stantially constant.
In operation, the controls maintain the pressure ofcompressed air on the surface of the molten metal within the ~37~3~
pressure vessel 42 at a value such that the level of the molten metal in the conduit 45 and branch conduit 47 is maintained at a "ready to pour" level, indicated by the line 48 in Figures 3 and 6. During pouring, the pressure on the surface of the mol-ten metal within the pressure vessel 42 is increased to raise the level of molten metal in passage 47 to a pouring level such as indicated at 50 in Figure 7, thus dischargin~ molten metal from the pouring spout into the launder, which is then in its lowered position. The flow of the molten metal is stopped quickly by reducing the pressure within the vessel 42, causing the level o~ metal in passage 47 to drop to the ready to pour l~vel shown at 48 in Figure 6.
The end or lip 49 of the pouring spout is disposed over the inner end 51 of the trough 52 of the launder 16, the l~under being shown in its raised position in Figure 6 and in pouring position in Figure 7.
The launder is supported from the furnace 14 by brack-ets 53 disposed on either side thereof by pivotal connections 54. The opposite ends of the brackets are secured to a trans-verse frame member 55 o~ the launder and the launder may bemoved between its raised position shown in Figure 6 and its pouring position shown in Figure 7, by any convenient mechanism such as a hydraulic piston and cylinder mechanism 56 acting through toggle links 57 and 58.
The link 57 is pivotally supported by a bracket 59 carried by the furnace 14 and is pivoted to link 58 at 60.
Link 58 is pivotally connected to one of the brackets 53. The cylinder of assembly 56 is also pivotally supported by the fur-nace as at 61. The piston rod of assembly 56 is pivotally con-nected to the pivotal connection 60. In the e~tended positionof the piston rod shown in Figure 6, the launder is in the raised position shown thereinO In the retracted position of the piston ~ 7~
rod shown in Figure 7, the launder is lowered so that the re-fractory seal 41 thereof firmly engages the top surface 37 of the mold and makes a seal surrounding the open nodularizing chamber 31 and pouring basin 39.
As shown particularly in Figures 6 and 7, the trough of the launder is supported by cross member 55 and an intermedi-ate support 62 that extends between the pivoted support arms 53.
If desired, mechanism can be provided to permit limited side-ways adjustment of the launder along the pouring rail. The trough comprises a refractory member 65 supported by a built-up steel frame made of L-shaped side members 66 having bottom 1anges 67 and the cross member 55 which has flanges 68 and 69.
In order to support the refractory seal member 41, a shallow metal securing member 71 is ad~ustably supported from flanges 68, 72 and 73, respectively, welded to member 55 and walls 66 of the launder and apertured to receive screws 68a~
74 and 75, the heads of which are welded to the securing member.
The screws are adjustably secured in the flanges as by nuts 76 and 77 50 that the securing member can be accurately located.
m e refractory seal 41 is fastened in the securing member by screws 78 that are threaded in nuts 79 welded to the flanges. By this means the refractory sealing member can be replaced readily if -that should become necessary.
In order to provide for the flow of molten me-tal into the mold, the end of the trough in the launder remote from the pressure vessel terminates in a downwardly extending closed con-duit 80. Openings 81 and 82 aligned with the conduit are pro-vided in the securing member 71 and in the sealing member 41.
With this arrangement, as will be seen from Figures 3-7, when the launder is in its lowered position, molten metal discharged from the pouring spout 44 of the furnace can flow down the trough 52 to closed conduit 80, then through the registerin~
openin~s 81 and 82 directly into the pouring basin 39 of each mold as it is positioned on the pouring rail in alignment with the furnace.
In operation, the stroke of the hydraulic ram that advances completed molds from the molding machine along the pourin~ rail 10 is adjusted so that the molds are advanced a distance equal to the width of a mold after each mold is deposit-ed on the pouring rail. The position and amount of discharge of the alloy dispensing apparatus 12 are adjusted so that the apparatus will dischar~e the correct amount of alloy into the nodularizing chamber 31 of each mold when the mold comes to rest in registration with the dispensing apparatus 12. Similarly, the position of the pressure vessel 42 and the attached launder 16, are adjusted with respect to the pouring rail so that as each mold stops adjacent the furnace, the discharge of conduit 80 and the opening 81 in the sealing member 41 will be disposed immediately above the pouring basin 39.
When these adjustments have been properly made and the moldin~ machine started in operation, the molds will be advanced successively to a position in which they are aligned with the alloy dispensing apparatus 12 and then subsequently to a posi-tion where they are aligned with the launder. m e alloy dis-pensing apparatus is adjusted and timed so tha-t it will auto-matically dischar~e the correct amount of alloy into the nodu-larizin~ chamber 31 of each mold when it comes to rest. An operator stationed on the platform P can readily observe whether or not the alloy dispensing mechanism is operating correctly~
After the alloy has been deposited, the molds are suc-cessively advanced step-by-step to the pouriny station adjacent the launder 16. During the periods of time when the molds are being moved, the hydraulic cyliner 56 is actuated to lift the ~l~7~
launder to the raised position shown in Fi~ure 6 and the con-trolling mechanism of the furnace maintains the level of molten metal in the furnace at the ready to pour level indicated at 48.
When a mold is hrought into position and stopped immediat.ely b~neath the launder, the cylinder 56 is controlled to permit the launder to move to the pourin~ position shown in Figure 7 with the refractory sealin~ member 41 in engagement with the top sur-face of the mold, thereby sealing the surface of the mold surrounding the open topped pouring basin 3g and the open topped nodularizing chamber 31. Then the controls of the pressure pouring apparatus of furnace 14 are actuated to increase the pressure on the metal within the chamber 42 to a predetermined amount which causes molten metal to rise to the pouring level 50 in branch conduit 47 and to flow out of the pourin~ spout 44 onto the inner end 51 of the trough 52 and down the trou~h 52 to the closed conduit 80 and throu~h the registering openin~s 81 and 82 into the pouring basin 39. From the shallow pouring basin, the molten metal flows into the nodularizing chamber where it is subjected to the action of the nodularizing alloy disposed in the chamber.
When the level o~ molten metal in the nodularizing chamber reaches the level of the openings 33 leading to the runners 30, the molten metal enters the runners and flows through the runners, down the downsprues 26 and the lateral ingates 25, into the several casting cavities 24.
The rate of flow of molten metal from the pressure vessel 42 is accurately controlled by accurate maintenance of the temperature of the metal, the pressure within the vessel and a timing means adjusted to stop the discharge o~ the molten metal by quickly reducing the pressure within the pressure ves-sel 42 so that the level of the metal in the conduits 45 and 47 is reduced to the ready to pour level 48. By this apparatus, ~B'7~
the amount of metal that is discharged into each mold and the time required for the dischar~e (i.e., th~ rate of discharge) can be controlled accurately so that waste of molten metal and corresponding waste of nodularizing agent can be minimized.
A~ter the pouring is completed, the launder ls automatically raised by the cylinder mechanism 56 and another mold is moved into pouring position.
It is to be noted that in the pouring position the refractory seal 41 reduces the amount of oxidation that takes place when the iron reacts with t~e magnesium and also prevents emission of contaminating reaction products into the atmosphere and protects personnel and equipment from dangerous pyrotechnics ~hat frequently occur when magnesium e~posed to air encounters molten iron. Also, the closed conduit 80 and openings 81 and 82 provide a closed passage that is several inches long from the launder trough 52 to the pouring basin 39. This elevation provides an additional ferrostatic head of metal in the mold and this additional pressure makes it possible to utilize runners, sprues and the like that are smaller in cross-section 2G than would otherwise be required, while securing a suf~iciently rapid flow of molten metal at desired castingtempera~ures into the casting cavities.
Furthermore, the rate of flow of metal from the fur-nace and the dimensions of the passages in the mold are prefer-ably correlated so that the molten metal is supplied to the chamber 31 faster than it can flow out through the exit openings 33 into the runners 30. This results in the condition shown diagrammatically in Figure 7, in which the chamber 31, the open-ings 81 and 82 and the conduit 80 are all filled with molken metal for the period of time during the pouring operation and a head of metal as at 85 i9 formed at the lower end o~ the launder above the passage or conduit 80. With this mode of operation, ~6~
the tendency of the molten metal to carry slag and other unde-sirable inclusions into the mold is reduced, since such inclu-sion can rise to the surface of the head o~ metal 85 and ulti-mately are retained in the chamber 31 and runners 30 when the launder drains instead of being carried into the casting cavi-ties 24 of the mold. Also, aspiration of air into the mold passages and cavities and resultant oxidation is reduced as com-pared to pouring practices where the metal falls to the mold in an open stream.
Thus the invention not only provides for rapid auto-matic production of iron castings, but because of the ferro-static pressure obtained in the flow of metal through the con-duits leading from the trough of the launder to the pouring basin, the dimensions of the gating passages can be reduced as compared to normal practice and the amount of scrap produced for a given casting also can be reduced, thus reducing further the amount of molten iron required, as well as the amount of alloy required for each casting.
As an example, nodular iron insulating caps have been produced in quantity with the apparatus. Each mold has twelve casting cavities arranged generally as shown in Figure 8 of the drawings with similar gating passages. The individual caps hav~ a weight of one and one-half pounds and the total pouring weight for each pour is thirty-five pounds. This gives a yield in the castings themselves of 51.4% of the total metal poured.
For each pour, four and one-half ounces of nodulari~ing alloy is deposited in the nodularizing cavity of each mold. The percent-age of mangesium found in the casting and the scrap or gating system amounts to 80% of the amount supplied and the total pouring time per mold is six seconds.
It is to be noted that while the total pouring time is six seconds, this is the amount of time that elapses from the ~37~3~
beginning of the pouring operation to the completion of the flow of metal out of ~he chamber 31 and to the runners, gates and casting cavities. The furnace controls, however, are pre-ferably ad]usted so that the required amount of metal, thirty-five pounds in the example, is discharged by the furnace into the launder within four seconds from the beginning of the pour-ing operation, resulting in the filling of the chamber 31, open-ings 81 and 82 and passage 30 and the formation of the head of metal 85 with the advantages described above.
The maximum number of molds of this type that can be poured per hour is 240. The molding and pouring operations are carried out with a minimum number of personnel so that costs are maintained at a reasonable value and the uniformity of the pouring operation ensures that high quality castings are pro-duced in which the nodularization of the iron is subtantially complete.
To summarize, the method and apparatus of the present invention result in greatly improved environmental conditions and reduction in hazard to personnel because of the nodulariz~
~0 ing chamber being sealed. Furthermore, the size of the nodular-izing chamber can be designed to make the most efficient use of the nodularizing matexial for the size of the castings being produced. The improved gating characteristics in the mold by reason of the ferrostatic head of the launder seal reduces the weight of the gating metal and thus also reduces the amount of alloy required. The amount of alloy required is further reduc-ed by the fact that the nodularizing chamber is completely closed, thus waste of magnesium through oxidation is minimized~
The precise metering of the amount of molten iron supplied to the mold makes it possible to eliminate waste and, for e~ample, to permit draining of the iron completely from the horizontal runners through which it is distributed to the down sprues.
3~
Waste and scrap forma-tion are also reduced byelimination of spillage of metal outside of the mold cavity and by the fact t~at no convention pouring cup is required.
This invention relates to the production of metal castings and is described herein as applied to the production of ductile iron castings, where the invention is especially advantageous. Ductile iron is also referred to as nodular or spheroidal graphite cast iron and ductile iron castings are highly advantageous as compared to ~ray iron castings because of their ductility and because they have increased tensile strength and resistance to impact as compared to ordinary gray iron castings. Also, ductile iron has much better castability characteristics than steel and for an increasing number of uses ductile iron castings can be used where steel castirlgs or forg-in~s were formerly required.
Ductile iron is produced by innoculating molten iron of the proper composition with a nodularizing agent that causes the graphite flakes that are ordinarily present in gray cast iron to assume a nodular or spheroidal form. It is this change in the characteristic of the graphite present in the cast iron that appears to give the ductile iron its advantageous charac-teristics. Numerous nodularizers are known; they are ordinarily alloys, compounds or mixtures embodying magnesium, calcium, sod-ium, lithium, strontium, barium, cesium, and other similar metals. Magnesium is the preferred nodularizing agent because of its effectiveness and availability and because its cost is less than other rarer metals that can be used. Magnesium and the other nodularizing agents, in addition to their cost, pre-sent problems because they have boiling points below the pouring temperature of cast iron and because they are easily oxidized.
Because of these characteristics, attempts to add nodularizing agents in the conventional manners employed in adding alloying agents to molten iron, present serious difficulties in tha-t the addition of the agents to a ladle, for example, is likely to result in a violent reaction with a pyrotechnic display that -1- ~
~ 6 3~1~
results in a hazard to foundry personnel and serious atmospheric contaminationO Also, some of the nodularizing agent is o~idiz-ed or otherwise lost, making it necessary to supply nodularizing agents in amounts in e~cess of the amounts required to effect nodularization. Also "fading" or a reduction in the amount of nodularizing agent in solution in the iron may take place dur-ing the time that elapses between the innoculation of the iron with the agent and the time the iron containing the nodulariz-ing agent reaches the mold, causing unreliability and inconsis-tency in the results.
Attempts have been made to eliminate these problemswith varying degrees of success. For example, the nodularizing agent has been alloyed with another metal in order to slow down the reaction that takes place when the nodularizing agent en-counters molten iron. This system results in increased cost for a given weight of nodularizing agent and further, the alloy-ing metal employed may have an undesired effect on the casting.
According to another method, a special intermediate chamber in-to which the nodularizing agent is disposed and through which ~0 the molten metal flows is interposed between the ladle and the mold. The chamber in which the nodularizing agent is disposed can be closed and the pyrotechnic display eliminated. However, fading can occur during the travel of the iron from the chamber in which the nodularizing aaent is disposed to the mold and scrap losses are freauently increased because of iron remaining in the intermediate chamber and passages. secause of the in-creased scrap losses, correspondingly increased amounts of nodu-larizing agents must be employed, adding to the cost of the casting. A system of this type is illustrated in United States Patent ~o. 3,819,365, issued June 25, 1974.
Another system, which is disclosed in Canadian Patent No. 925,265 involves the use of an intermediate chamber in the ~6~7~3~
mold itself in which the nodularizing agent is disposed. This system has met with some success but it is open to objection for various reasons, including the ~act that since the nodularizing agent is placed within the mold, it is not possible to inspect the mold immediately prior to pouring to determine that the nodularizing agent is, in fact, in place. Also, the necessity of providing an intermediate chamber and additional gating with-in the mold limits the size or number of the mold cavity or cavi-ties that may be included in a mold of given external dimensions.
This reduces the productive capacity of the apparatus and makes it necessary to employ a greater number of molds for a given production of castings. While this method eliminates the prob-lem of fading and also avoids pyrotechnics, another difficulty has arisen because results are sometimes inconsistent insofar as the characteristics of the cast metal are concerned. The intermediate chamber in the mold also requires the pouring of metal in an amount greater than would be required in a conven-tional mold within an intermediate chamber and this additional metal makes it necessary to supply a correspondingly increased amount of nodularizing agent. Both of these factors increase the cost of the castings.
A ~eneral object of the present invention is to pro-vide a method and apparatus for supplying an addition agent such as a nodularizing agent in the casting of molten metal such as iron in which the problems noted above are largely eliminated.
Another object is to provide an improved method and apparatus for making ductile iron castings. A further object is the pro~
vision of a method and apparatus for making iron castings that is particularly adapted to automatic molding and automatic pour-ing techniques whereby a high rate of production, reasonablecosts and excellent uniformity of quality of castings can be obtained. Another object is the provision of a method and 1~63~9 apparatus for makin~ metal castings in which it is not necessar~
to employ a pouring cup and in which defects in castinys due to aspiration of air into the mold passages during pouring and de-fects due to slag inclusions in the metal are minimized. An-other object is the provision of a method and apparatus for pro-ducing iron castings that is particularly adapted for use with vertically parted molds.
Briefly, according to the present invention, a chamber is provided in the upper portion of the mold in which the cast-ing is to be formed. An innoculating agent is deposited in thechamber and the molten metal flows into the chamber as it is poured ~rom an appropriate supply into the mold. The chamber in which the nodularizing agent is disposed is open at the top and is connected to appropriate runners, sprues and the like leading to the mold cavity or cavities in which the castings are produced. ~t the time of pouring the molten metal, the nod-ularizing agent is disposed in the chamber and the open top of the chamber is closed by a separately formed refractory seal that engages the top surface of the mold surrounding the cavity.
The metal flows through a launder from a furnace containing the molten metal and which embodies a closed conduit that extends through the seal. The metal is deposited by the conduit in a pouring basin formed in the mold and also closed by the seal.
From the pourin~ basin the metal flows to the chamber in which the nodularizing agent is disposed. From this chamber the molten metal flows through gating passages such as runners, sprues and the like to the mold cavity or cavities in which the castings are formed. The seal prevents the discharge of noxious fumes into the atmosphere during the pouriny operation and also eliminates hazards that miyht otherwise occur from the pyro-technics that can take place when molten iron encounters a nodu-larizing agent containing magnesium. The seal and associated ~0763~9 passages in the launder also provide a head of molten metal over the pouring basin which minimizes slag inclusions and a-spiration of air into the castings without requiring additional passa~es or chambers in the mold itsel~ After the pouring operation has been completed, the seal and the conduit that extends through it are disen~aged from the mold and the mold is moved away from the pouring apparatus where the metal is permitted to cool and solidify and where, thereafter, the castings are removed from the mold and preferably checked and tested in accordance with usual practices. Preferably, a ~lurality of molds are moved successively to a pouring station, ~he~e each mold is stopped, enga~ed by the seal, poured, the seal disengaged from it, and the mold then advanced and an-other mold moved to the pouring station.
The invention consists in the provision o~ apparatus for making iron castings comprising a mold having bottom, side and top surfaces, a casting cavity, a chamber in the upper por-tion of said mold and a gating passage connecting the chamber with the casting cavity, the chamber having a floor and side 20 ~alls and being open at its top, the area of the open top of the chamber being at least substantially equal to the area o~
~he floor thereof, and said gating passage being connected to said ch~mbex at a level above the floor thereof, the level of the connection of said gating passage to said chamber also be-ing above the uppermost portion of the casting cavit~, said chamber being adapted to have a nodularizing agent deposited therein through the open top thereof, the open top of the chamber being disposed at the level of the adjacent top sur-face of the mold, a sealing member composed of refractory ma-terial and adapted to make sealing engagement with the topsurface of the mold surrounding the open top of said chamber, l -5 ~
~763~L~
means for placing said sealing member in sealing engagement with the top surface of the mold and means for disengaging it therefrom, a conduit extending through said sealing member and adapted to deliver molten metal to said chamber, a launder having a passage for molten metal leading to said conduit and means for supplyi~g molten metal to said passage in said laun-der and thereby supplying molten metal to said conduit and said chamber.
The invention also consists in ~he provision of a method of making metal castings comprising providing a mold ~aving bottom and side and top surfaces, a casting cavity, a chamber and a gating passage providing communication between said chamber and said mold, sai.d chamber having a floor and side walls and being disposed in the upper portion of said mold and being open at its top, the floor of said chamber he-ing disposed at a level above the uppermost portion of the casting cavity, engaging the top surface of the mold with a seal that makes sealing contact with the top surface of the mold surrounding said chamber, and supplying said mold with sufficient molten metal to fill the casting cavity by causing said molten metal to flow into said mold throug~ a downwardly extending closed conduit and an opening extending through said seal and in communication with said chamber, the metal flowing downwardly from said chamber to the casting cavity.
Figure 1 is a plan view of a preferred form of ap-paratus made according to the invention and adapted to perform the method of the invention;
Figure ~ is an end elevational view of the apparatus shown in Figure l;
Figure 3 is a vertical section o~ the apparatus, taken as indicated by line 3-3 of Figure l;
-5a .~
~763~9 Figure 4 is a fragmentary section to an enlarged scale, showing the launder and the upper part of the mold shown in Figure 3;
Figure 5 is a section at right angles to Figure 4 and taken along line 5-5 of Figure 4;
Figure 6 is a sectional detail showing the launder of the apparatus of Figure 1 in conjunction with fragmentary portions of the furnace and the mold, the launder being shown in its raised position;
Figure 7 is a fragmentary sectional view of the parts shown in Figure 6 but illustrating the launder in pouring - -Sh-i~763~
position:
Figure 8 is a phantom view illustrating the cavities and passages of a mold for use in the apparatus in carrying out the process;
Figure 9 is a top plan view of the mold shown in Figure 8;
Figure 10 is a section through the mold of Figure 9, taken along line 10-10 of Figure 9.
As illustrated somewhat diagrammatically in Figures 1 and 2 of the drawings, a preferred form of apparatus for carry-ing out the invention comprises a pouring rail 10 at the entry cnd of which there is disposed an automatic molding machine 11 which may be any conventional type of molding machine, such as the "Disamatic" machine produced by Dansk Industri Syndikat A/S.
This machine produces molds M successively and deposits them on the pouring rail. With this type of machine, each following mold is in engagement with a preceding mold and, in turn, is engaged by another following mold. A hydraulic ram associated with the molding machine pushes the whole series of molds along ~0 the pouring rail simultaneously, each mold being advanced a pre-determined distance and then remaining stationary while another mold is deposited on the pouring rail, after which the entire series is again advanced. As will appear below, it is during the intervals when the molds are stationary that the nodulariz- !
ing agent is introduced into the molds and the molds are poured.
As the molds travel along the pouring rail 10 they pass beneath an alloy dispensing mechanism 12 which may be of a ~nown type and is arranged to deposit a predetermined amount of nodu-larizing agent in each mold. Each mold stops in register with the alloy dispensing mechanism and while it is stopped, a pre-determined amount of alloy is deposited into the nodularizing chamber of the mold. Thereafter, the mold is advanced beyond a~k ;3~3 the alloy dispensing mechanism 12 and another mold is advanced into a position in registration with the alloy aispensing mech-anism where it, in turn, will receive a desired amount of nodu-larizing material.
m e molds continue to be advanced step-by-step down the pourin~ rail, passing a furnace indicated in general at 14, which is also of known construction, and which is arranged to deposit a predetermined amount of molten iron in a predetermined time into each mold as it stops on the pouring rail opposite the furnace. The molten metal is discharged from the furnace into a launder, indicated in general at 16, and from the launder the metal flows by gravity into the mold and to the casting cavities thereo~ as described in detail below. Each mold stops lon~ enough opposite the furnace to permit the discharge of the required amount of iron into it and after this has taken place, the molds are all advanced another step and a following mold is disposed in pouring position opposite the furnace.
After the furnace, the molds continue on ln their step-by-step movement down the pouring rail where the castings are solidified, then into a coolin~ conveyor of known construc-tion. Ultimately, the castings are removed from the molds, trimmed and preferably inspected and tested. Conventional ex-haust hoods as indicated at 17 and 18 may be placed over the conveyor as desired.
Molten iron may be supplied to the furnace 14 by con~
ventional melting furnaces, not shown, disposed on the other side of the furnace 14 from the pouring rail.
While the invention may be utilized with molds of vari-ous types, the invention is described herein as used in conjunc-tion with the production of castings in vertically partedflaskless molds, a typical mold of this type being ~hown in Figures 8, 9 and 10.
~ ~63.~
As shown in these figures, each mold M may comprise two parts 20 and 21, the parting plane of the two parts being indicated at 22. The mold is shown as embodying a plurality of (in this case twelve) casting cavities 24 that are connected by ingates 25, to downsprues 26 which extend downwardly from the runners 30. The runners 30 extend generally horizontally from a centrally disposed nodularizing chamber 31 in which a nodular-izing agent indicated at 32 (Figure 10) is disposed. It will be noted that the exits 33 from the chamber 31 to the runners 30 are elevated above the floor 35 of the chamber 31. This en-sures that the molten iron will react properly with the nodular-izing agent in the chamber 31 before ~lowing into the runners 30 and thence to the downsprues 26, lateral ingates 25 and casting cavities 24.
As shown particularly in Figures 4, 9 and 10, the nod-ularizing chamber 31 is disposed in the upper portion of the mold and is open at the top. The upper edges of the side walls 36 of chamber 31 lie in the same plane as the top surface 37 of the mold.
In order to ensure that the molten iron will flow smoothly and uniformly into the nodularizing chamber 31, the upper portion of the mold is also provided with a shallow poux-ing basin 39. The top edges of the walls 40 of the pouring basin lie in the same plane as the top edges of the side walls of chamber 31, which is the plane of the top surface 37 of the mold.
With this construction of the mold it is possible to seal the open tops of the nodularizing chamber 31 and the pour-ing basin 39 by a refractory seal 41 (Figures 4-8) during the pouring operation. The fact that the chambers and pouring basins in the molds are open make it possible to check visually the nodularizing chambers before pouring to determine that the ~L~763~
nodularizing agent is present therein~ Also, the refractory seal 41 seals in the products of the reaction between the nodu-larizing agent and the molten iron, thus protecting the environ-ment and personnel from hazards that might otherwise be en-cou~tered. Furthermore, the location of the open topped pouring basin and nodularizing chamber adjacent the top of the mold results in a saving of space that would otherwise be occupied in the mold if these chambers were incorporated in the interior of the mold. Thus, the size and number of the casting cavity or cavities that can be incorporated in a mold of a given size is not substantially reduced as compared to conventional molds by the use of the present invention; the reduction in size and/or number of castin~s possible with a given size of mold that occurs with systems in which the nodularizing chamber is disposed internally of the mold is obviated.
As explained below with particular reerence to Fig-ures 3-7, the present invention lends itself advantageously to automatic pouring of the molten metal into the molds. ~ccord-ing to a preferred form of the present invention, the furnace ~0 14 is of a known type that is adapted to deliver accurately controlled quantities of molten iron at accurately controlled temperatures within a predetermined period of time. Furnaces of this type are known in the art and are commercially avail-able. Suitable type furnaces and controls are illustrated and described, for example, in United States Patents Nos~ 3,395,833 and 3,499,580, to which reference is hereby made~ Furnaces of this general type are manufactured by Inductotherm Corporation of Rancocos, ~ew ~ersey, U.S.A., and are marketed under the tradename "Autopour". The furnace comprises a suitable pressure vessel 42 that is usually round in cross section and which is mounted on a movable carriage 43 so that its position can be adjusted transversely of the pouring rail 10 in order to locate ~7~3.~
the furnace accurately with respect to the pouring basins of the molds as they are successively moved along the rails. The furnace is provided with heating elements and appropriate con-trols to keep the molten iron within it at a temperature that is accurately controlled. The furnace is under a con-trolled super-atmospheric pressure of compressed air, the air pressure being controlled by means of a detecting device positioned at a fixed level beneath the molten iron within the furnace. The detecting device measures the static pressure in the molten metal at the level of the detecting device at all times. This pressure is maintained at desired values by automatic controls even though the level of molten iron in the furnace may vary within a normal operating range. Since the mode of operation and controls of various types of pressure pouring devices are well known, the controls are not described in detail herein.
As shown in Figures 3, 6 and 7, the furnace has a pouring spout 44 that is connected to a conduit 45 that extends downwardly into the furnace vessel 42 ~o an open end disposed substantially below the normal level of molten metal within the vessel 42. Molten metal is supplied to the interior of the vessel 42 through an inlet 46, a typical level of molten metal in the vessel 42 being indicated by the dotted line in Figure 3.
The upper end of the conduit 45 terminates in the pouring spout 44, which is shown in the form of a trough. Slightly below the juncture of the conduit 45 and the pouring spout 44, there is a branch conduit 47 that is open at the top and functions to limit the ferrostatic head of the molten metal that can be developed in the conduit 45. This arrangement assists in main-taining the rate of flow of molten metal in the conduit 45 sub-stantially constant.
In operation, the controls maintain the pressure ofcompressed air on the surface of the molten metal within the ~37~3~
pressure vessel 42 at a value such that the level of the molten metal in the conduit 45 and branch conduit 47 is maintained at a "ready to pour" level, indicated by the line 48 in Figures 3 and 6. During pouring, the pressure on the surface of the mol-ten metal within the pressure vessel 42 is increased to raise the level of molten metal in passage 47 to a pouring level such as indicated at 50 in Figure 7, thus dischargin~ molten metal from the pouring spout into the launder, which is then in its lowered position. The flow of the molten metal is stopped quickly by reducing the pressure within the vessel 42, causing the level o~ metal in passage 47 to drop to the ready to pour l~vel shown at 48 in Figure 6.
The end or lip 49 of the pouring spout is disposed over the inner end 51 of the trough 52 of the launder 16, the l~under being shown in its raised position in Figure 6 and in pouring position in Figure 7.
The launder is supported from the furnace 14 by brack-ets 53 disposed on either side thereof by pivotal connections 54. The opposite ends of the brackets are secured to a trans-verse frame member 55 o~ the launder and the launder may bemoved between its raised position shown in Figure 6 and its pouring position shown in Figure 7, by any convenient mechanism such as a hydraulic piston and cylinder mechanism 56 acting through toggle links 57 and 58.
The link 57 is pivotally supported by a bracket 59 carried by the furnace 14 and is pivoted to link 58 at 60.
Link 58 is pivotally connected to one of the brackets 53. The cylinder of assembly 56 is also pivotally supported by the fur-nace as at 61. The piston rod of assembly 56 is pivotally con-nected to the pivotal connection 60. In the e~tended positionof the piston rod shown in Figure 6, the launder is in the raised position shown thereinO In the retracted position of the piston ~ 7~
rod shown in Figure 7, the launder is lowered so that the re-fractory seal 41 thereof firmly engages the top surface 37 of the mold and makes a seal surrounding the open nodularizing chamber 31 and pouring basin 39.
As shown particularly in Figures 6 and 7, the trough of the launder is supported by cross member 55 and an intermedi-ate support 62 that extends between the pivoted support arms 53.
If desired, mechanism can be provided to permit limited side-ways adjustment of the launder along the pouring rail. The trough comprises a refractory member 65 supported by a built-up steel frame made of L-shaped side members 66 having bottom 1anges 67 and the cross member 55 which has flanges 68 and 69.
In order to support the refractory seal member 41, a shallow metal securing member 71 is ad~ustably supported from flanges 68, 72 and 73, respectively, welded to member 55 and walls 66 of the launder and apertured to receive screws 68a~
74 and 75, the heads of which are welded to the securing member.
The screws are adjustably secured in the flanges as by nuts 76 and 77 50 that the securing member can be accurately located.
m e refractory seal 41 is fastened in the securing member by screws 78 that are threaded in nuts 79 welded to the flanges. By this means the refractory sealing member can be replaced readily if -that should become necessary.
In order to provide for the flow of molten me-tal into the mold, the end of the trough in the launder remote from the pressure vessel terminates in a downwardly extending closed con-duit 80. Openings 81 and 82 aligned with the conduit are pro-vided in the securing member 71 and in the sealing member 41.
With this arrangement, as will be seen from Figures 3-7, when the launder is in its lowered position, molten metal discharged from the pouring spout 44 of the furnace can flow down the trough 52 to closed conduit 80, then through the registerin~
openin~s 81 and 82 directly into the pouring basin 39 of each mold as it is positioned on the pouring rail in alignment with the furnace.
In operation, the stroke of the hydraulic ram that advances completed molds from the molding machine along the pourin~ rail 10 is adjusted so that the molds are advanced a distance equal to the width of a mold after each mold is deposit-ed on the pouring rail. The position and amount of discharge of the alloy dispensing apparatus 12 are adjusted so that the apparatus will dischar~e the correct amount of alloy into the nodularizing chamber 31 of each mold when the mold comes to rest in registration with the dispensing apparatus 12. Similarly, the position of the pressure vessel 42 and the attached launder 16, are adjusted with respect to the pouring rail so that as each mold stops adjacent the furnace, the discharge of conduit 80 and the opening 81 in the sealing member 41 will be disposed immediately above the pouring basin 39.
When these adjustments have been properly made and the moldin~ machine started in operation, the molds will be advanced successively to a position in which they are aligned with the alloy dispensing apparatus 12 and then subsequently to a posi-tion where they are aligned with the launder. m e alloy dis-pensing apparatus is adjusted and timed so tha-t it will auto-matically dischar~e the correct amount of alloy into the nodu-larizin~ chamber 31 of each mold when it comes to rest. An operator stationed on the platform P can readily observe whether or not the alloy dispensing mechanism is operating correctly~
After the alloy has been deposited, the molds are suc-cessively advanced step-by-step to the pouriny station adjacent the launder 16. During the periods of time when the molds are being moved, the hydraulic cyliner 56 is actuated to lift the ~l~7~
launder to the raised position shown in Fi~ure 6 and the con-trolling mechanism of the furnace maintains the level of molten metal in the furnace at the ready to pour level indicated at 48.
When a mold is hrought into position and stopped immediat.ely b~neath the launder, the cylinder 56 is controlled to permit the launder to move to the pourin~ position shown in Figure 7 with the refractory sealin~ member 41 in engagement with the top sur-face of the mold, thereby sealing the surface of the mold surrounding the open topped pouring basin 3g and the open topped nodularizing chamber 31. Then the controls of the pressure pouring apparatus of furnace 14 are actuated to increase the pressure on the metal within the chamber 42 to a predetermined amount which causes molten metal to rise to the pouring level 50 in branch conduit 47 and to flow out of the pourin~ spout 44 onto the inner end 51 of the trough 52 and down the trou~h 52 to the closed conduit 80 and throu~h the registering openin~s 81 and 82 into the pouring basin 39. From the shallow pouring basin, the molten metal flows into the nodularizing chamber where it is subjected to the action of the nodularizing alloy disposed in the chamber.
When the level o~ molten metal in the nodularizing chamber reaches the level of the openings 33 leading to the runners 30, the molten metal enters the runners and flows through the runners, down the downsprues 26 and the lateral ingates 25, into the several casting cavities 24.
The rate of flow of molten metal from the pressure vessel 42 is accurately controlled by accurate maintenance of the temperature of the metal, the pressure within the vessel and a timing means adjusted to stop the discharge o~ the molten metal by quickly reducing the pressure within the pressure ves-sel 42 so that the level of the metal in the conduits 45 and 47 is reduced to the ready to pour level 48. By this apparatus, ~B'7~
the amount of metal that is discharged into each mold and the time required for the dischar~e (i.e., th~ rate of discharge) can be controlled accurately so that waste of molten metal and corresponding waste of nodularizing agent can be minimized.
A~ter the pouring is completed, the launder ls automatically raised by the cylinder mechanism 56 and another mold is moved into pouring position.
It is to be noted that in the pouring position the refractory seal 41 reduces the amount of oxidation that takes place when the iron reacts with t~e magnesium and also prevents emission of contaminating reaction products into the atmosphere and protects personnel and equipment from dangerous pyrotechnics ~hat frequently occur when magnesium e~posed to air encounters molten iron. Also, the closed conduit 80 and openings 81 and 82 provide a closed passage that is several inches long from the launder trough 52 to the pouring basin 39. This elevation provides an additional ferrostatic head of metal in the mold and this additional pressure makes it possible to utilize runners, sprues and the like that are smaller in cross-section 2G than would otherwise be required, while securing a suf~iciently rapid flow of molten metal at desired castingtempera~ures into the casting cavities.
Furthermore, the rate of flow of metal from the fur-nace and the dimensions of the passages in the mold are prefer-ably correlated so that the molten metal is supplied to the chamber 31 faster than it can flow out through the exit openings 33 into the runners 30. This results in the condition shown diagrammatically in Figure 7, in which the chamber 31, the open-ings 81 and 82 and the conduit 80 are all filled with molken metal for the period of time during the pouring operation and a head of metal as at 85 i9 formed at the lower end o~ the launder above the passage or conduit 80. With this mode of operation, ~6~
the tendency of the molten metal to carry slag and other unde-sirable inclusions into the mold is reduced, since such inclu-sion can rise to the surface of the head o~ metal 85 and ulti-mately are retained in the chamber 31 and runners 30 when the launder drains instead of being carried into the casting cavi-ties 24 of the mold. Also, aspiration of air into the mold passages and cavities and resultant oxidation is reduced as com-pared to pouring practices where the metal falls to the mold in an open stream.
Thus the invention not only provides for rapid auto-matic production of iron castings, but because of the ferro-static pressure obtained in the flow of metal through the con-duits leading from the trough of the launder to the pouring basin, the dimensions of the gating passages can be reduced as compared to normal practice and the amount of scrap produced for a given casting also can be reduced, thus reducing further the amount of molten iron required, as well as the amount of alloy required for each casting.
As an example, nodular iron insulating caps have been produced in quantity with the apparatus. Each mold has twelve casting cavities arranged generally as shown in Figure 8 of the drawings with similar gating passages. The individual caps hav~ a weight of one and one-half pounds and the total pouring weight for each pour is thirty-five pounds. This gives a yield in the castings themselves of 51.4% of the total metal poured.
For each pour, four and one-half ounces of nodulari~ing alloy is deposited in the nodularizing cavity of each mold. The percent-age of mangesium found in the casting and the scrap or gating system amounts to 80% of the amount supplied and the total pouring time per mold is six seconds.
It is to be noted that while the total pouring time is six seconds, this is the amount of time that elapses from the ~37~3~
beginning of the pouring operation to the completion of the flow of metal out of ~he chamber 31 and to the runners, gates and casting cavities. The furnace controls, however, are pre-ferably ad]usted so that the required amount of metal, thirty-five pounds in the example, is discharged by the furnace into the launder within four seconds from the beginning of the pour-ing operation, resulting in the filling of the chamber 31, open-ings 81 and 82 and passage 30 and the formation of the head of metal 85 with the advantages described above.
The maximum number of molds of this type that can be poured per hour is 240. The molding and pouring operations are carried out with a minimum number of personnel so that costs are maintained at a reasonable value and the uniformity of the pouring operation ensures that high quality castings are pro-duced in which the nodularization of the iron is subtantially complete.
To summarize, the method and apparatus of the present invention result in greatly improved environmental conditions and reduction in hazard to personnel because of the nodulariz~
~0 ing chamber being sealed. Furthermore, the size of the nodular-izing chamber can be designed to make the most efficient use of the nodularizing matexial for the size of the castings being produced. The improved gating characteristics in the mold by reason of the ferrostatic head of the launder seal reduces the weight of the gating metal and thus also reduces the amount of alloy required. The amount of alloy required is further reduc-ed by the fact that the nodularizing chamber is completely closed, thus waste of magnesium through oxidation is minimized~
The precise metering of the amount of molten iron supplied to the mold makes it possible to eliminate waste and, for e~ample, to permit draining of the iron completely from the horizontal runners through which it is distributed to the down sprues.
3~
Waste and scrap forma-tion are also reduced byelimination of spillage of metal outside of the mold cavity and by the fact t~at no convention pouring cup is required.
Claims (14)
1. Apparatus for making iron castings comprising a mold having bottom, side and top surfaces, a casting cavity, a chamber in the upper portion of said mold and a gating passage connecting the chamber with the casting cavity, the chamber hav-ing a floor and side walls and being open at its top, the area of the open top of the chamber being at least substantially equal to the area of the floor thereof, and said gating passage being connected to said chamber at a level above the floor thereof, the level of the connection of said gating passage to said chamber also being above the uppermost portion of the cast-ing cavity, said chamber being adapted to have a nodularizing agent deposited therein through the open top thereof, the open top of the chamber being disposed at the level of the adjacent top surface of the mold, a sealing member composed of refractory material and adapted to make sealing engagement with the top surface of the mold surrounding the open top of said chamber, means for placing said sealing member in sealing engagement with the top surface of the mold and means for disengaging it there-from, a conduit extending through said sealing member and adapt-ed to deliver molten metal to said chamber, a launder having a passage for molten metal leading to said conduit and means for supplying molten metal to said passage in said launder and thereby supplying molten metal to said conduit and said chamber.
2. Apparatus according to claim 1 wherein said laun-der is pivotally mounted and wherein said sealing member is carried by said launder, and means for moving said launder be-tween a lower position in which said sealing member makes seal-ing engagement with the surfaces of the mold surrounding the chamber therein to a retracted position wherein said sealing member is disengaged from said mold.
3. Apparatus according to claim 1 wherein said mold includes a pouring basin in communication with said chamber, the conduit through the sealing member leading directly to said pouring basin whereby molten metal is delivered through said conduit to said pouring basin and then to said chamber, the pouring basin also being open at the top and being disposed within the area engaged by said sealing member when the sealing member is in engagement with the mold.
4. Apparatus for making nodular iron castings com-prising a mold having bottom, side and top surfaces, a casting cavity, a nodularizing chamber disposed in the upper portion of the mold and adapted to receive a nodularizing agent, a gating passage connecting the nodularizing chamber with the casting cavity, the nodularizing chamber having a floor and side walls and having an open top through which nodularizing agent can be deposited in the chamber, the floor of the chamber being dis-posed at a level above the level of the uppermost portion of the casting cavity and the area of open top of the chamber being at least substantially as great as the area of the floor thereof, the side walls of the chamber intersecting the top surface of the mold, a sealing member composed of refractory material and adapted to make sealing engagement with the top surface of the mold surrounding the open top of said nodularizing chamber, means for placing said sealing member in sealing engagement with the top surface of the mold and means for disengaging it there-from, a conduit extending through said sealing member and adapted to deliver molten metal to said mold, and means for sup-plying molten metal to said conduit.
5. Apparatus according to claim 4 having a launder having a passage for molten metal leading to said conduit, said launder being pivotally mounted and said sealing member being carried by said launder, and means for moving said launder be-tween a lower position in which said sealing member makes seal-ing engagement with the top surfaces of a mold surrounding the nodularizing chamber therein to a retracted position wherein said sealing member is disengaged from said mold.
6. Apparatus according to claim 4 wherein said mold includes a pouring basin in communication with said nodularizing chamber, the conduit through the sealing member leading directly to said pouring basin whereby molten metal is delivered through said conduit to said pouring basin and then to the nodularizing chamber, the pouring basin also being open at the top and being disposed within the area engaged by said sealing member when the sealing member is in engagement with the mold.
7. Apparatus for making nodular iron castings compris-ing a pouring rail, means at one end of said pouring rail for successively producing molds, each mold having bottom, side and top surfaces, a casting cavity and a nodularizing chamber con-nected thereto by a gating passage, the nodularizing chamber being at the upper end of each mold and having a floor and side walls and being open at its top, the open top of the chamber be-ing disposed at the level of the adjacent top surface of the mold, the area of the top of the chamber being at least substan-tially equal to the area of the floor thereof and the connection between the gating passage and the nodularizing chamber being above the level of the uppermost portion of the casting cavity, means for intermittently moving said molds along said pouring rail with said nodularizing chambers open, nodularizing agent supply means disposed adjacent said pouring rail, said inter-mittent advancing means being arranged to stop each mold of said succession of molds adjacent said nodularizing agent sup-ply means, means for operating said nodularizing agent supply means for depositing a predetermined amount of nodularizing agent on the floor of the nodularizing chamber of each mold when it is stopped adjacent the nodularizing agent supply means, a furnace disposed adjacent said pouring rail and spaced from said nodularizing agent supply means in the direction of move-ment of said molds along said pouring rail, said furnace being adapted to contain a supply of molten metal, said mold advancing means also being arranged to stop each mold adjacent said furn-ace for a time sufficient to permit discharge of molten metal therein, a launder extending from said furnace to a region above a mold disposed on said pouring rail, said launder being adapted to receive molten metal from said furnace and deliver it to said mold, said launder being movable between a pouring posi-tion and a retracted position, said launder carrying a refract-ory sealing member positioned to make sealing engagement with the upper surface of each mold surrounding said nodularizing chamber when said mold is stopped adjacent said furnace and said launder is in pouring position, said launder having a pas-sage leading from said furnace and a conduit extending from the end of said passage remote from said furnace downwardly through said sealing member for supplying molten metal to said nodular-izing chamber and thence to said casting cavity, means for con-trolling said furnace to deliver a predetermined amount of metal in a predetermined time to said launder when said launder is in its pouring position with said sealing member in engagement with the top of a mold, means for retracting said launder to its re-tracted position after the molten metal has been discharged from said launder and said conduit into said mold, said intermittent advancing means operating to advance each mold along said pouring rail after it has been poured and to position another mold adjacent said furnace.
8. Apparatus according to claim 7 wherein said gating passage opens into said nodularizing chamber at a level above the floor thereof, said controlling means for said furnace being adapted to control said furnace to deliver molten metal to said launder at a rate greater than such molten metal can flow from said chamber into said gating passage, whereby said chamber and said conduit become filled with molten metal during the pouring operation.
9. A method of making metal castings comprising pro-viding a mold having bottom and side and top surfaces, a casting cavity, a chamber and a gating passage providing communication between said chamber and said mold, said chamber having a floor and side walls and being disposed in the upper portion of said mold and being open at its top, the floor of said chamber being disposed at a level above the uppermost portion of the casting cavity, engaging the top surface of the mold with a seal that makes sealing contact with the top surface of the mold surround-ing said chamber, and supplying said mold with sufficient molten metal to fill the casting cavity by causing said molten metal to flow into said mold through a downwardly extending closed conduit and an opening extending through said seal and in communication with said chamber, the metal flowing downwardly from said cham-ber to the casting cavity.
10. In a method according to claim 9 wherein said chamber has a floor and said gating passage is connected to said chamber above the floor thereof, the step of supplying molten metal to said mold through said downwardly extending closed conduit at a rate greater than the molten metal flows out of said chamber into said gating passage, whereby said chamber and said conduit becomes filled with molten metal during the pouring operation.
11. A method according to claim 10 wherein the metal is iron.
12. A method of making nodular iron castings compris-ing providing a mold having side and top surfaces, a casting cavity, a nodularizing chamber having a floor and side walls and an open top, and a gating passage providing communication be-tween said nodularizing chamber and said casting cavity, plac-ing a nodularizing material in the nodularizing chamber through the open top thereof, engaging the top surface of the mold with sealing member that makes sealing contact with the top sur-face of the mold surrounding said nodularizing chamber and sup-plying said mold with sufficient molten metal to fill the cast-ing cavity by causing said molten metal to flow into said mold through a downwardly extending closed conduit extending through said sealing member and in communication with said nodularizing chamber, the metal flowing downwardly from said chamber to said casting cavity.
13. In a method according to claim 12 wherein said gating passage is connected to said nodularizing chamber above the floor thereof, the step of supplying molten iron to said mold through said conduit at a rate greater than the molten iron flows out of said nodularizing chamber into said gating passage, whereby said nodularizing chamber and said conduit become filled with molten iron during the pouring operation.
14. A method according to claim 13 wherein the molds are produced by a molding machine and successively deposited on a pouring rail and then advanced successively step-by-step along said pouring rail to a station where nodularizing material is deposited in the nodularizing chamber of each mold, then advanced successively step-by-step to a pouring station where the tops of the molds are successively engaged by said sealing member and molten iron supplied to each mold, and then the molds are successively moved away from said pouring station and per-mitted to cool.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA280,698A CA1076319A (en) | 1977-06-16 | 1977-06-16 | Method and apparatus for making castings |
| DK263278A DK263278A (en) | 1977-06-16 | 1978-06-13 | MOLDING PROCEDURE AND APPLIANCE |
| GB7826744A GB2000059B (en) | 1977-06-16 | 1978-06-13 | Method and apparatus for making castings |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA280,698A CA1076319A (en) | 1977-06-16 | 1977-06-16 | Method and apparatus for making castings |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1076319A true CA1076319A (en) | 1980-04-29 |
Family
ID=4108899
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA280,698A Expired CA1076319A (en) | 1977-06-16 | 1977-06-16 | Method and apparatus for making castings |
Country Status (3)
| Country | Link |
|---|---|
| CA (1) | CA1076319A (en) |
| DK (1) | DK263278A (en) |
| GB (1) | GB2000059B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109332668B (en) * | 2018-11-14 | 2020-12-01 | 金华市宝琳工贸有限公司 | Automatic piston casting process |
| CN113600805A (en) * | 2021-08-30 | 2021-11-05 | 山东鲁豫阀门有限公司 | Emergency monitoring and releasing device for aluminum melting furnace casting system |
| CN115090862B (en) * | 2022-06-29 | 2023-05-05 | 重庆剑涛铝业有限公司 | Preparation facilities of automobile-used aluminum alloy |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DD112776A5 (en) * | 1973-05-28 | 1975-05-05 | ||
| GB1435871A (en) * | 1973-06-21 | 1976-05-19 | Gen Motors Corp | Continuous mechanicaltiron pouring line |
| DK142533B (en) * | 1974-09-11 | 1980-11-17 | Dansk Ind Syndikat | Installations for the manufacture of castings in incrementally stacked horizontal forms. |
-
1977
- 1977-06-16 CA CA280,698A patent/CA1076319A/en not_active Expired
-
1978
- 1978-06-13 GB GB7826744A patent/GB2000059B/en not_active Expired
- 1978-06-13 DK DK263278A patent/DK263278A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| GB2000059B (en) | 1982-03-03 |
| GB2000059A (en) | 1979-01-04 |
| DK263278A (en) | 1978-12-17 |
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