US 2244816 A
Description (OCR text may contain errors)
June 10, 1941. c, VON YNN 2,244,816
DIE CASTING APPARATUS Filed Sept. 27. 19:59
INVENTOR Charles EVon Lynn w/atm ATTORNEY Patented June 10, 1941 DIE CASTING APPARATUS Charles F. Von Lynn, Cranford, N. 1., assignor to Alumin um Company of America, Pittsburgh,
Pa., a corporation of Pennsylvania Application September 27, 1939, Serial No. 296,782
1 Claim. (CI. 22-68) This invention relates to die casting machines of the type employing a plunger to force into th mold cavitythe material to be cast.
Die casting machines have heretofore been used in which molten material to be cast is first introduced into a horizontally disposed well or receptacle, and is then forced from the receptacle by means of a plunger reciprocable therein into a mold cavity formed by a stationary die and a movable die, which dies are replaceable in order to permit the making of a variety of objects in the machine. In suchmachines, the stationary die is provided with a horizontal transverse sprue hole which forms a continuation of the bore of the receptacle mentioned, and together with that bore forms the chamber into which the molten material to be cast is placed preparatory to forcing it into the mold cavity. The injecting stroke carries the plunger into the sprue hole and almost to the die parting line in order that as much as possible of the material being cast may be forced into the mold cavity.
However, certain difficulties have been encountered with such machines. Since the injection stroke of the plunger carries it into the sprue hole, and the sprue hole comprises part of the chamber from which the molten material is injected into the mold cavity, it is necessary that the sprue hole align accurately with the bore operation likewise varies. As a result, it is necessary to use receptacles and plungers of various lengths if the stroke of the plunger is to remain constant.
A further difilculty is encountered when such machines are used for casting the higher melting point metals, such as aluminum or brass, chiefly because of rapid deterioration of'the chamber from which the molten metal is forced by the plunger. To check deterioration of the receptacle which forms part of that chamber, it has been proposed to cool it artificially by means of a suits able cooling chamber, but to provide the sprue hole with a cooling chamber and the necessary accompanying mechanism complicates the die construction and assembly, and also results in detrimental fatigue stresses in the die.
It is an object of this invention to provide die casting apparatus of'the type described, in which a mold cavity is formed by a fixed die and a movable die, and in which a plunger is reciprocable in a chamber formed by the bore of a receptacle and by a transverse sprue hole in the fixed die, but in which a plug fixedly attached to the movable die prevents molten metal in the receptacle from fiowing into the mold cavity until pressure is applied to the metal by the plunger.
It is a further object of this invention to provide die casting apparatus in which a plunger is reciprocable in the bore of a horizontally disposed receptacle and in a sprue hole which forms a continuation of that receptacle bore, and in which a plug fixedly attached to the movable die prevents molten metal in the receptacle from fiowing into the mold cavity until pressure is applied to the metal by the plunger, but cooperates with the wall of the sprue hole when the dies are in a closed position to provide a passage through which the'molten metal is forced into the mold cavity when pressure is applied thereto.
It is a further object of this invention to provide die casting apparatus for the casting of high mleting point metals in which the metal is forced into the mold cavity by a plunger which is reciprocable'in a horizontally disposed receptacle and in asprue hole in a die, but in which the chamber in which the metal to be cast is placed lies within the receptacle mentioned and is artificially cooled along substantially its entire length.
Referring to the drawing,
Fig. 1 is a vertical sectional view of a portion -of a die casting machine embodying my invento the. fixed die i and'is provided with a pouring hole 5 therein through which molten materialto be cast can be poured into the bore 6 of the receptacle from a hand ladle or the like. The fixed die i is provided with a transverse sprue hole I which" forms a continuation of the receptacle bore 6 and communicates with the mold cavity 3 through the gate "I. Iiie sprue hole I is preferably slightly larger in diameter] at its inlet end than the end of the sprue hole. Sumcient metal is poured into the receptacle I initially that when the casting has been formed a small amount of the metal will remain in the receptacle between the end of the from the mouth of the sprue hole toward the gate 8 and serves to conduct material being cast from the receptacle 4 into the mold cavity 3 when pressure is applied thereto as hereinafter described. It is preferable that, except for the groove ill, the plug 9 fit closely in the sprue hole along its entire length'whlch projects from the face of the movable die, though it is also possible for the plug to fit closely in the sprue hole only at the latters mouth. The plug 9 closes the mouth of the sprue hole 1 except for that portion thereof which iorms the entrance to the passage mentioned which is defined by the wall of the groove l0 and the wall of the sprue hole, and since the outlet of the groove I0 is above the level of the end of the receptacle bore 8, moltenmaterial in the receptacle bore cannot flow into the mold cavity without the application of pressure thereto. Thus, the plug 9 acts as a dam between the receptacle bore 6 and the mold cavity.
The plunger II is reciprocable in the bore 6 of the receptacle 4 for the purpose of injecting into the mold cavity through the groove ill the material to be cast. The plunger II is preferably actuated by suitable hydraulic mechanism, and has a stroke sufllciently long to carry it into the sprue hole I when the plug 9 is withdrawn from the sprue hole. During the injecting stroke of the plunger, the plug 9 occupies the sprue hole; and
' the materialto be cast is confined in the receptacle I between the end of the plunger Ii and the face of the plug until it is forced out of the receptacle and into the mold cavity by the plunger. The receptacle 4 has double walls which provide a cooling chamber l2 around the receptacle, extending'substantially the full length of that receptacle, so that a cooling medium, such as water or air, can be circulated therein to cool that element and molten material therein, the inlet pipe I3 serving to introduce the cooling medium into the chamber l2, and the outlet pipe H serving to carry away the coolant.
The apparatus described above operates as follows:
The movable die 2 is advanced to a closed position with the fixed die I, as shown in Fig.1,
' to form the mold cavity 3. During the closing of the dies, the plug 9 advances into the sprue hole I until it closes the mouth of the sprue hole except for the entrance to the passage formed by the groove l0 and the wall of the sprue hole. With the plunger in a fully retracted position, metal in a suitable condition for casting is poured into the receptacle 4 through the pouring hole 5, after which plunger II is advanced rapidly to force the metal into the mold cavity 3 through the passage formed by the groove l0 and the wall plunger H and the face of the plug I. Meanwhile, cooling fiuid is circulated in the chamber l2 through the pipes I l and I4. when the casting has solidified and the movable die is withdrawn to open the mold cavity, the movable die carries with it the plug I, whereupon the plunger ll advances into the sprue hole I and ejects from the bore of the receptacle 4 and from the sprue hole any solidified metal therein.
With apparatus of the type described above, it is unnecessary that the sprue hole I align accurately with the bore of the receptacle 4, although it is essential that the sprue hole and receptacle bore align 'suillciently to permit the plunger to advance into the sprue hole when the plug 9 is withdrawn. Consequently, it is possible for the sprue hole to taper outwardly from the receptacle, as shown in Fig. 1, and that form of sprue hole is preferred since it facilitates removal of any solidified metal remaining therein after the casting has solidified.
Various modifications can be made in the apparatus described above without departing from the spirit of my invention or from the following claim. For example, although it is preferable that the outlet of the groove ll be above the upper level ofthe receptacle bore i in order to prevent the metal in the receptacle from flowing .into the mold cavity without the application of I cavity.
In a pressure casting machine including a fixed die and a movable die cooperating to form a mold cavity, a receptacle adjacent the fixed die for supplying material to be cast, said receptacle having a substantially horizontally disposed bore,
and said fixed die having a sprue hole therein forming a continuation of said receptacle bore, a plunger reciprocable in said receptacle bore and in said sprue hole, and a plug fixedly attached to said movable die; when said dies are closed said plug extending into said sprue hole and terminating in a plane at the juncture of the sprue hole and receptacle bore, said plug and the wall of said sprue hole cooperating to form a passage therebetween communicating with said receptacle bore and said mold cavity, the bottom of the entrance of said passage being above the level of molten metal within said receptacle when said plunger is in its retracted position, and the mouth of said receptacle being closed by said plug except at the entrance of said passage, whereby said plug prevents molten metal within said receptacle bore from flowing into said mold cavity prior to the application of pressure to the molten metal by said plunger.
- CHARLES F. VON LYNN.