US2843893A - Apparatus and method for gating with diaphragm packing machines - Google Patents

Description

July 22, 1958 Filed March 5,4 1957 K. E. DAvls 2,843,893 APPARATUS AND METHOD FOR GATING wTH DIAPHRAGM PACKING MACHINES 2 Sheets-Sheet 1 FIG i INVENTOR KenneH/m-Davis ATTORNEY K. E. DAVIS 4 H FOR GATING WITH DIAPHRAGM PA NG MACHINES 2 Sheets-Sheet 2 INVENTOR Kermeh E Davis,

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ATTORNEY July 22, 19.58

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APPARATUS AND METHOD FOR GATING WITH DIAPHRAGM PACKING MACHINES Kenneth E. Davis, Grosse Pointe Woods, Mich., assignor to The Budd Company, Philadelphia, Pa., a corporation of Pennsylvania Application March 5, 1957, Serial No. 644,039

9 Claims. (Cl. 22-38) This invention relates to apparatus and method for gating molds which arepacked by diaphragm packing machines such as those disclosed in the patents to Taccone 2,698,976 and 2,715,758, more specifically for forming a sprue hole and pouring cavity or cup therefor, and has for an object the provision of improvements in this art.

When asks are packed by diaphragms there is considerable ditculty in forming suitable gate sprues and Acups in the sand. Several methods have been tried but all have given much trouble. It is not necessary to note all prior methods and their shortcomings but a couple may be mentioned by way of example.

One method has been to pack a solid body of sand and later to bore out the sprue and cup. This obviously leaves loose sand at the surface which will wash down with the metal during pouring.

Another method is to provide a cupforming protuberance on the lower side of the diaphragm but since the diaphragm is a loose sheet the-protuberance is likely to assume various positions and dispositions other than the one intended.

According to the present invention an extremely simple form of apparatus and procedure are provided which produce in the diaphragm packing operation an accurately formed sprue and cup with a smooth packed surface `free from sand and without the need for any secondary operations.

The invention will be explained in connection with the accompanying drawings showing an illustrative embodiment thereof wherein:

Fig. 1 is a vertical sectional view through a packing machine and a mold part showing the parts after a packing operation has been completed, the view being taken on the line 1-1 of Fig. 3;

Fig. 2 is a partial sectional view of the mold part after the sprue and cup opening have been cleared of sand;

Fig. 3 is a top plan view taken on the line 3-3 of Fig. l before sand is deposited in the mold part; and

Fig. 4 is a vertical section through a full mold assembly after a part has been cast therein.

For illustrative purposes it will be assumed (Fig. 4) that a wheel brake drum is to be cast on a supporting disk 11. In Fig. 4 there is shown a iiask, or mold comprising a drag 12 and a cope 13 with the cast drum therein. The present invention is concerned with the packing of the body of sand 14 in the cope and the formation of a gate 15, sprue 16 and sprue cup or cavity 17 in this body of packed sand. The entire channel may be referred to as a gate.

The usual apparatus with which the present invention is associated comprises a press frame 20 having a base 21 and a pressure head 22 carrying a diaphragm, bladder or obtruder 23 below a cavity 24. Means are provided for introducing lluid under pressure into the cavity to pack sand in a cope 13 positioned therebelow or to create a vacuum to withdraw Ithe diaphragm after the sand has been packed.

United States Patent i 2,843,893 Patented July 22, 1958 ICC A pattern 27 is carried on the base 21 and the cope 13 is positioned over this pattern, suitable means, such as pins, being provided to insure proper registry of parts. The pattern and cope are arranged to be moved in and out from beneath the pressure head 22 for assembly and separation. The cope is first iilled with sand above the pattern and levelled with the top of the cope. Then an open ring frame 28 to laterally confine the diaphragm is placed on top of the cope, suitable positional registry means being provided. The ring frame may be placed first if more sand is needed. Then the assembly is moved on the base to a proper registry position beneath the head. A sprue pin 30 is slidably carried by the pattern member. The pin is provided with means such as a shoulder 31 to limit its down position but its lower end is accessible through the lower end of the hole in the pattern piece so that it may be pushed upward a short distance. The sprue pin, like the pattern, has suitable taper to provide easy separation from the packed sand when the cope and pattern are separated.

According to the present invention there is provided above the sprue pin, where the gate cup cavity is to be formed, a circumferential frame or barrier support 32 which locally supports the diaphragm to pre-vent -downward movement along this circumferential line.v In the form illustrated the cope frame itself forms part of this barrier support. As a consequence of this local circumferential support, the diaphragm under pressure takes a concave shape with the pointed bottom of the concavity above the end of the sprue pin. By making the upper end of the sprue pin rounded there will be only a thin layer of sand left on it after thepacking operation.

After packing, the sprue pin is pushed up from below by hand, as shown in Fig. 2, or by coordinated mechanism if an automatic machine is provided., to break away the light sand layer between the cup and sprue and the loose sand in the space is blown clear by an air jet in known manner.

As shown, the gate pocket or cup and the main top surface of the sand are near the same height. Actually the diaphragm will press more deeply into the sand at the cup location because of the smaller concave shape which the diaphragm is caused to take there as compared to the broad outer surface elsewhere. The sprue pin effectively stops the downward movement of the pointed protrusion of the diaphragm so that the cup depth will be regulated. The sloping sides are firmly packed so `that no loose sand is present to be entrained with the metal.

If it is desired that there be a difference in bottom level between the cup and the outside area this can readily be regulated by adding or taking away a certain amount of sand in the cup enclosure after the sand in the cope has been initially levelled olf.

It is thus seen that the invention provides very simple and eiiective means and method for forming gate cup and sprue shapes in diaphragm packed molds.

While one embodiment of the invention has been described for purposes of illustration it is to bev understood that there may be various embodiments and modifica tions within the general scope of the invention.

What is claimed is:

1. Molding apparatus for forming a gate cup in the sand in a mold part by means of a sand packing diaphragm, comprising in combination with the press and diaphragm and the mold part, of a barrier frame arranged in the mold part at the gate cup location for supporting the diaphragm in a circumferential line to cause it to press the sand within the barrier frame to form a gate concavity with sloping sides in the sand as it packs the sand in the mold part.

2. Molding apparatus for forming a gate cup in the sand in a mold part by means of a sand packing diaphragm, comprising in combination with the press and diaphragm and the mold part frame, of a barrier loop frame arranged in the mold part extending inward from the side of the mold part frame and forming with it a closed loop for supporting the diaphragm in a circumferential line to cause it to press the sand within the barrier frame to form a gate concavity with sloping sides in the sand as it packs the sand in the mold part.

3. Molding apparatus as set forth in claim 1, wherein said barrier frame is of less depth than the depth of the mold part to allow sand to pack together beneath it.

4. Molding apparatus as set forth in claim 1, which further includes an empty frame arranged on top of the mold part to conne the diaphragm laterally.

5. Molding apparatus as set forth in claim 1, which further includes a sprue-forming pin located at the lower end of the gate concavity formed by the diaphragm.

6. Molding apparatus as set forth in claim 1, which further includes a sprue-forming pin with a convex upper end located at the lower end of the gate concavity formed by the diaphragm.

7. Molding apparatus as set forth in claim 1, which further includes a sprue-forming pin mounted for vertical movement at the lower end of the gate concavity formed by the diaphragm.

8. The method of forming a gate cup in the sand in a mold frame by a sand packing diaphragm which comprises, providing sand in a mold frame having an inner diaphragm-supporting frame within the mold frame above the zone where the gate cup and sprue hole are to be formed supporting the diaphragm on the inner frame in a circumferential line around the upper end of the gate cup location, and applying fluid pressure on the diaphragm to cause it to form a gate cup concavity with sloping sides within the line of support on the inner frame while packing sand in the mold frame.

9. The method of forming a gate cup and sprue hole in the sand in a mold frame in a diaphragm-type packing device which comprises, supporting the diaphragm in an interior circumferential line around the upper end of the gate cup and sprue location of a mold frame filled with sand, arranging a vertically movable sprue-forming pin in the bottom of the gate cup concavity location, applying iluid pressure on the diaphragm to cause it to form a gate concavity with sloping sides within the interior line of support while packing sand in the mold part, the packing action leaving a layer ofv sand above the end of the sprue-forming pin, moving the pin upward to break the sand layer over its end, and later blowing loose sand out of the gate and sprue.

References Cited in the file of this patent UNITED STATES PATENTS 322,203 Rice .Tuly 14, 1885 408,386 Moore Aug. 6, 1889 2,767,446 Pray Oct. 23, 1956 FOREIGN PATENTS 750,979 Great Britain June 20, 1956

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