US1333754A - Art of die-casting - Google Patents

Description

C. M. GREY.

ART or me 0131mm APPLICATION FILED MAR. 6,1919.

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Patelited Mar. 16,1920.

c. M. GREY.

ART OF DIE CASTING. APPLICATION men MAR. s. 1919.

1,333,754. I Patent ed Mar. 16,1920.

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UNITEDATSTATES PATE CHARLES H. GREY, OF EAST ORANGE, NEW EItSEY.

am or DIE-CASTING.

To all whom it may concern:

Be it known that 1 CHARLES M. GREY, a citizen of the United States, residing in East Orange, State of. New Jersey,'county of Essex, have invented certain new and" useful Improvements in the Art of Die- Casting, of which the following is a speclfication.

This invention relates to improvements in the art of die casting and is directed, more particularly, to method of, and apparatus for, charging the pressure pot of a die cast: ing machine.-

In die casting machines, as heretofore constructed, there has generally been employed two pots or receptacles, one containing the bath or pool of the metal, commonly called the-melting pot, and the other termed the pressure pot or chamber, from which the metal is forced into the die by either pistons 01' fluid pressure. This pressure pot or. chamber has generally been immersed in the bath or pool of the melting pot, to a greater or less extent, and means have been provided for filling this pressure pot from the metal in the melting pot. These means have consisted of either submerged ports, or means for tilting the nose of the pressure pot beneath the surfaceof the bath or pool. While submerged ports opened by pistons, working inside the fairly satisfactory or low melting point metals it has been found that for metals of higher melting points that such pressure chambers are not practical, as the pistons cut and stick at such high temperatures. It has therefore .been found more satisfactory to use a pressure pot so mounted in the bath as to allow the nozzle end to be submerged in the bath between shots. pots have been found satisfactory, to a greater or less extent, they have certain disadvantages among whiclr'are, the necessity of so supporting them that a large portion of the pot is out-of the bath when inposition for vejecting the metal, the inability to get a full charge, in the pressure pot, the

tendency to get the dross floating on top of the bath into the pressure pot, ande ect .same into castings to be produced, the increased tendency of drossing or oxidizing the bath, due to the fact that as the nozzle end of the pressure pot is submerged it causes a quantity of air to be mixed withthe bath as the surface of the-bath closes in over the submerging'lp'hd of the pot.

ressure pot have been While these Specification of Letters Patent. Patented Bla r, 16, 1920, Application filed March 6, 1919. Serial No. 280,935.

With the foregoing vconsiderations in m1nd,"the object of the present invention is to overcome or minimize the disadvantages adverted to as well as others.

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F eatures' o-f the invention, other than those specified, aswell as the advanta es resulting fromthe employment thereo will be apparent from the following detailed descrlption when read in conjunction with the accompanying drawings.

In the accompanying drawings I have illustrated diagrammatmally one form of ap-pa-. ratus in which the method of this invention may be practically carried out, but it will be understood, however, that the method may be practised with other forms of apparatus and that the apparatus shown is susceptible to various modifications without departing from the spirit of the inven- I t1on.

Figure 1 is a perspective elevation showing those portions of the die casting'ma- Referring to the drawings, A indicates a melting pot containing a pool or bath of molten metal B, which forms the source of .supply for the pressure pot. It is the usual practice to mount the melting pot A in a suitable furnace of which it forms. a part and to heat-said pot externally by any suitable source of heat.

The pressure pot C may, of course, partake of different shapes, but is here shown as substantially U-shaped. The interior of the pot is hollow, and is provided at one end, with a nozzle D adapted to cooperate with a die E insuch manner as to feed molten metal from the pot .to the die, while the other end of the pot is connected in any suitable manner, preferably by a flexible tubing F, to a suitable source of fluid pressure, whereby the metal in the pressure pot may be forced through the nozzle D into the die. The .pot is preferably supported for movement in a horizontal plane on a hanger G by means of a pivotable connection 9 and the link connection g. The link connection 9' is made adjustable for the purposeof obtaining accurate alinement between the nozzle D and the inlet to the die, and the hanger G is mounted for sliding movement longitudinally of a pair of guides H suitably mounted in fixed position in the machine. By mounting the pot as described, it may be slid toward and away from the die so as to occupy the operative or shooting position of Fig. 1, or the filling position of Fi 2. Any suitable means may be provi ed for so shifting the pot. By suspending the pot in the manner described, a portion of the pot is immersed in the molten metal B, and serves to maintain any metal which may be contained in the pot in the desired molten condition.

Associated withthe machine is a vacuum bell I, suspended by a link J, and adapted to be raised and lowered by an suitable means such as a pivoted lever K fulcrumed at k and controlled by any suitable mechanism. The bell I is so positioned in the machine that, when elevated, it is suspended above the position occupied by the nozzle end of the pdt when said pot is retracted from the die and in the filling position shown in Fig. 2. The bell is, however, of :{uch shape and proportions that it may be 'owered from the elevated position shown in Fig. 1 to the depressed position of Fig. 2, wherein the lower mouth of the bell will occupy a position below the surface of the pool of metal- B and the nozzle end of the pot will be housed within the confines of the bell. The interior of the bell communicates, preferably through a flexible communication L, with a suitable vacuum system for exhausting the air from the bell when said bell is in the position of Fig. 2, with the.

result that the exhaustion of the air from the bell at this time will cause the molten metal B to be drawn up into the bell so that the surface of said metal rises in the bell appreciably above the opening of the nozzle D, as clearly shown in Fig. 2. It will thus appear, that, since the metal level in the bell is above the opening of the nozzleD and that as the back end of the pressure pot is open to the atmosphere through the compressed air inlet F, which is connected to a suitable valve system, the metal will flow through nozzle D and into the pot, thereby charging the same.

In case there is not suflicient metal in the pressure pot to fill the upwardly projecting nozzle end of the pot and still more than fill the connecting portion between the two ends of the pressure pot, then either the outlet at the back end of the pot must be closed or other means used for obtaining a primary charge in'the pressure pot.

In practice, the exhausting of air from the bell and pot is accomplished very speedily, with the result that the metal level in the bell rises quickly to the position shown haustion of air in the bell and the breaking of the vacuum so that in this manner the pot may be either entirely filled or may be only partially filled as the operator desires.

The operation ofthe device may be briefly outlined as follows. The pressure pot having been moved to the filling position and the partial vacuum built up in the bell I-, while positioned over the nozzle end of the pot, the metal'rises in the bell and flows into the pot in the manner shown in Fig. 2. When the pot is charged as desired, the vacuum is broken in the bell, allowing the metal therein to fall back to the liquid level of the pot A and the bell is then raised out of the path of the pot. The pot is next moved forwardly by suit-able mechanism to the position shown in Fig. 1 wherein the nozzle D is brought into cooperative relation with the sprue of the die E. This having been accomplished, fluid pressure is admitted through the connection F and forces the metal in the pot through the nozzle D and into the die in the manner well known to the art. After the die has been filled, the pressure in connection F is shut off and the pot moved back to the position of Fig. 2, whereupon the bell I is again lowered over the nozzle end of the pot and the recharging and casting operations repeated.

An important practical advantage in the charging of the pot in the manner specified is that the molten metal drawn u into the bell entirely surrounds the nozz e D and thereby serves to melt oif any metal which may have partially solidified at the mouth of the nozzle from' the previous casting operation. As a matter of fact, the nozzle is maintained at such temperature that obstruction thereof through the solidifying of small quantities of metal therein is entirely obviated. In carrying out the method described, the pot is shown as movable toward and away from the die and an apparatus for carrying out the method in this manner is shown in the drawing.

In the charging of a pot in the manner described, the metal which flows into the pot is not only free from slag and dross but is also free from entrained air, since, when the bell is down over the pot, the operation of exhausting the bell, of course, exhausts all the air from the'pot simultaneously so that the pot containsa partial vacuum before the metal rises in the bell. As a result of this feature of the method, the" metal which is subsequently forced from the pot into the die is more free from entrained gas than in the ordinary practice, thereby producing better castings.

Having thus fully described my invention, what I claim as new and desire to secure b Letters Patent is:

1. In the art of die casting, the method of charging the pressure pot which consists in pneumatically raising the level of a'portion of the bath in which the pressure-pot is supported above the normal level of the bath and by such change of level causing l the metal to flow into the pressure pot.

2. In the art of die casting, the method of charging the pressure pot which consists in feeding the molten metal thereto from the melting pot and from beneath the surface of the metal in said melting pot by pneumatic means, whereby the pressure pot is charged without introducing dross therein.

3. In the art of die casting, the. method of charging the pressure pot which consists in pneumatic-ally raising the liquid level of I the metal of the melting pot in the vicinity of the charging opening of the pressure pot to such height that the metal is fed through said opening into the pressure pot.

4. 'In the art of die casting, the method s which consists in so positioning a pressure pot within the melting pot that the metal feed inlet to the pressure pot is located above the normal level of the bath in the melting pot, thereafter incasing said inlet in a receptacle the lower end of which is sealed by the metal of the bath, then ex-- hausting air from said receptacle "and the inlet end of the pressure pot whereby the metal is drawn into the receptacle and abovethe inlet to the pressure pot and feeds into said inlet to charge the pot.

5. In the art of die casting, the method which consist in producing a vacuum around and in the charging end of a pressure pot and above the normal level of the metal in the melting pot, whereby said vacuum raises a portion of the metal above its normal level and above the charging end of the pressure pot and feeds the metal into said pot.

6. In the art of die casting, the method of charging the pressure pot which consists in pneumatically causing molten metal to fiow into the pot at a point-above the normain bath from which said pot is to be charged, 1n combination with pneumatically operated means for raising a portion of the a metal of the bath to a point above the charging inlet to the pot whereby metal is fed to the pot.

8. In a die casting machine, a pressure pot, having its metal charging end positioned above the level of the metal of the main bath from which said pot is to be charged, a. receptacle adapted to inclose the charging end of the pressure pot with its,

sealed by the metal in the bath, and means for exhausting the air from the bell and charging end of the pressure pot whereby the molten metal rises in the bellabove the charging inlet to the pressure pot and feeds into the latter. 1

10. A die casting machine, embodying a die, a pot mounted for movement toward and away from the die, which pot is adapted to be partially submerged in a molten metal pool, a vacuum bell normally occupying a position out of the path of the pot but adapted to be lowered over the pot with its lower end sealed by the metal in the pool when the latter is in a position retracted from the die and means for exhausting the air from the bell and feeding-end of the pot for the purpose of causing the metal to rise therein to a suflicient height to charge the pressure pot.

11. A die casting machine embodying apot adapted to be partially submerged in a molten metal pool, and a die, one of which is movable toward and away from the other so that they are brought into and out of cooperative relation and vacuum means eooperating with the pot, when the parts are out of cooperative relation, for elevating a portion of metal inthe pool and causing it to flow into the pot.

a 12. A die casting machine, a melting pot, a pressure pot positioned therein, .adie, means for causing a relative to and fro movement between the pressure pot and the die, in combination with. vacuum means for rharging the pressure pot with moltenmetal at a point above the normal level of the metal vin the melting pot.

In testimony whereof I have signed my name to this specification.

CHARLES GREY,

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