US3672437A

US3672437A - Die casting mold

Info

Publication number: US3672437A
Application number: US878464A
Authority: US
Inventors: Charles H Bennett
Original assignee: Koehring Co
Current assignee: Koehring Co
Priority date: 1969-11-20
Filing date: 1969-11-20
Publication date: 1972-06-27
Anticipated expiration: 1989-06-27

Abstract

A mold for producing decorative name plates or the like by die casting comprises a mold cavity in a fixed die part, gates for the mold cavity in a movable die part, internal runners within the movable die part feeding the gates, an external runner system on the fixed die part feeding the internal runners from a sprue cavity in the fixed die part, and a mechanism for breaking casting material solidified in the runners from casting material solidified in the gates and thereafter removing the casting solidified in the mold cavity in one piece with solidified casting material loosely lodged in the gates.

Description

Bennett [451 June 27, 1972 DIE CASTING MOLD [21] Appl. No.: 878,464

[52] US. Cl. ..l64/265, 18/D1G.51, 18/16 F, 164/347, 164/70, 164/303, 164/131, 164/404 ['51] Int. Cl. ..B22c 31/00 [58] I Field of Search .l64/265, 264, 26,2, 304, 69, 164/70, 131, 404, 347; l8/D1G. 51, 16 F, 16 H [56] References Cited UNITED STATES PATENTS 2,558,027 6/1951- Wilson ..l64/347 X F ORElGN PATENTS OR APPLICATIONS 288,038 10/1915 Germany ..164/265 737,144 7/1943 Germany 164/347 Primary Examiner-J. Spencer Overholser Assistant Examiner-V. K. Rising Att0rney--Charles W. Walton, F. Kristen Koepcke and Wenzel Zierold [57] ABSTRACT A mold for producing decorative name plates or the like by die casting comprises a mold cavity in a fixed die part, gates for the mold cavity in a movable die part, internal runners within the movable die part feeding the gates, an external runner system on the fixed die part feeding the internal runners from a sprue cavity in the fixed die part, and a mechanism for breaking casting material solidified in the runners from casting material solidified in the gates and thereafter removing the casting solidified in the mold cavity in one piece with solidified casting material loosely lodged in the gates.

10 Claims, 5 Drawing Figures PATENTEUJUNN m2 SHEET 10F 2 F/aZ,

lrrak/vzx DIE CASTING MOLD The invention relates to molds for producing relatively flat articles such as decorative name plates by die casting.

Molds for producing articles of the mentioned character have heretofore been conventionally side gated at the parting line. This practice, as is well known, has been somewhat unsatisfactory in that it leaves blemishes on the part caused by the residual metal from inlet and overflow gates.

Another disadvantage of the conventional side gating practice is that the casting with attached sprue and runner system must be die trimmed in a secondary operation.

Generally, it' is an object of the present invention to provide an improved die casting mold which overcomes the abovementioned difficulties and shortcomings of the prior art.

More specifically, it is an object of the invention to provide a die casting mold which will produce a decorative name plate or similar article with one or more integral gate studs extending from the reverse side of the article.

A still further object of the invention is to provide an improved die casting mold of the above-mentioned character which will produce a decorative name plate or similar article having a suitable number of integral mounting studs projecting from its rear side.

These and other objects and advantages are attained by the present invention, various novel features of which will be apparent from the description herein of a preferred embodiment of the invention and will be pointed out by the appended claims.

Referring to the accompanying drawings:

FIG. 1 is a sectional view of a die casting mold embodying the invention, the section being taken on line II of FIG. 2;

FIG. 2 is an elevational view of a movable die half at the left of the parting line PP in FIG. 1, a mold cavity, sprue and runner system of a fixed mold half at the right of the parting line being superimposed in dash dotted lines upon the elevational view of FIG. 2;

FIG. 3 is a view similar to FIG. 1 but showing the movable die half separated an initial distance from the fixed die half;

FIG. 4 is a view similar to FIG. 3 but showing a runner ejector mechanism in a downwardly adjusted position, and

FIG. 5 is a view similar to FIG. 4 but showing the movable die half at an increased spacing from the fixed die half, and a casting ejector mechanism adjusted to its operative position.

The mold shown in the drawings is intended for use in a conventional die casting machine including a fixed platen 1 and a vreciprocable platen 2. A fixed die part 3 of the mold 'is mounted on the platen I by clamps 4,and a movable die part 6 of the mold is mounted on the reciprocable platen 2 by clamps 7.

The decorative name plate to be produced by the mold is indicated in FIG. 2 by the dash-dotted interconnected script letters forming the word Starts." Mirror images of the letters are recessed in an impression insert 8 of the fixed die part 3 and form an external mold cavity 9 therein along the parting line P-P.

In the closed condition of the mold as shown in FIG. 1, molten casting material may be injected into the mold cavity 9 from a shot cylinder 11 through material feed passages comprising a sprue cavity 12, an external runner system 13 recessed within the fixed die part 3 along the parting line P- P, an internal runner system extending from the parting line into an insert 14 of the movable die part and generally designated in FIG. I by the reference character 16, and a gate system within the insert 14 and generally designated by the reference character 17.

The external runner system 13, as shown in dotted lines in FIG. 2, comprises a trunk cavity 18 which has a lower end in communication with the sprue cavity 12. At its upper end the trunk cavity 18 communicates with branch cavities 19 and 21 which extend in laterally opposite directions between overlapping upper and lower parts (FIG. 1) of the

inserts

8 and 14. As best shown in FIG. 3, the upper part of the impression insert 8 is recessed to present an upwardly facing oblique shoulder 22 which extends across the face of the fixed die part along the parting line P-P, and the lower part of the insert 14 is recessed to present a complementary downwardly facing oblique shoulder 23 which extends across the face of the movable die part along the parting line P-P. The branch cavities l9 and 21 are recessed in the oblique upwardly facing shoulder 22 of the fixed die insert 8.

FIG. 1 shows a passage 24 of the internal runner system 16 within the movable die insert 14, and FIG. 2 shows additional

internal runner passages

26, 27 and 28 which, like the passage 24, extend'upwardly into the insert 14 and as shown in FIG. 1, are spaced rearward from the upper front face of the latter. As shown in FIG. 2 the runner passage 24 extends upward to a level above the lower end of the letter S," the runner passage 26 extends upward to a level near the upper end of the letter t,and the runner passages '27 and 28 extend upward to a level beyond the letters r and s.

The gate system 17 comprises a gate 29 which, as shown in FIG. 1, merges with the upper end of the runner passage 24 and, as shown in FIG. 2,

additional gates

31, 32 and 33 which merge with the

runner passages

26, 27 and 28, respectively. The

gate passages

29, 31, 32 and 33 taper toward their junctures with the

runner passages

24, 26, 27 and 28, respectively. At their inner ends the gate passages are conically restricted to provide relatively small orifices through which casting material may flow from the runner passages into the associated gate passages. As shown in FIG. 2 the gate 29 feeds the lower end of the letter S, the gate 31 feeds the upper ends of the letters 8" and t," and the

gates

32 and 33 feed the letters a, t and s.

A runner ejector mechanism is mounted on the movable die part 6 and comprises an up and down adjustable horizontal beam 34 (FIR. 2) mounting depending ejector pins 36, 37, 38 and 39. As shown in FIG. I, the insert 14 has a vertical bore 41 leading into the upper end of the runner passage 24, and the ejector pin 36 is axially reciprocable in the bore 41 in longitudinal alinement with the runner passage 24. As shown in FIG. 2, the ejector pins 37, 38 and 39 are similarly reciprocable in vertical bores 42, 43 and 44 of the insert 14 in longitudinal alinement with the

runner passages

26, 27 and 28, respectively. A double acting hydraulic cylinder 46 (FIG. 2) is suitably mounted on the movable die part 6 and operatively connected with the ejector beam 34 for adjusting the latter from the raised position in which it is shown in FIGS. 1, 2 and 3 to the lowered position in which it is shown in FIGS. 4 and 5, and vice versa. The length of the ejector pin 36 is such that its lower end, in the raised position of the beam 34 as shown in FIG. 1, coincides flush with the upper end of the runner passage 24. Similarly, the ejector pins 37 38, and 39, as shown in FIG. 2, extend downwardly to but not into the upper ends of the

runner passages

26, 27 and 28, respectively, when the runner ejector beam 34 is in its raised position. Lowering of the ejector beam, as illustrated by FIGS. 4 and 5, advances the runner ejector pins into the respective runner passages of the die insert 14. The ejector beam 34 is guided on

upright guide pins

47 and 48 which are fixedly mounted on the movable die part 6.

A casting ejector mechanism is movable mounted on the movable die part 6 and comprises a horizontally back and forth adjustable plate assembly 49 mounting a group of

casting ejector pins

51, 52, 53, 54 and 56 (FIG. 2). Also mounted on the plate assembly 49 are return pins as shown at 57 and 58 in FIG. 1, which slidably support the plate assembly 49 on the movable die part 6. In the closed condition of the mold as shown in FIG. 1 the return pins bear against the fixed die part 3 and the plate assembly 49 and associated casting ejector pins are thereby held in a retracted position. When the mold is opened by movement of the platen 2, in the direction of arrow A in FIG. I, the plate assembly 49 together with its casting ejector and return pins is forced into a projected position (FIG. 5) by engagement of the plate assembly 49 with

stationary bumper pins

59, 61, 62 and 63. Leader pins 64 on the fixed die part 3, and

complementary bores

66, 67, 68 and 69 (FIG. 2) insure precise cooperative engagement of the die parts along the parting line in the closed condition of the mold.

Referring to FIG. 2, the ejector pins 51 to 56 are transversely spaced from each other in such relation to the mold cavity that ejecting thrust will be exerted at properly distributed points upon the cast article.

In operation, molten casting material is ejected from the shot cylinder 11 into the closed mold while the runner ejector pins 36 to 39 are in their raised positions and the

runner passages

24, 26, 27 and 28 are thereby kept closed at their upper ends. The movable die half has a wedge shaped plug cavity 71 opposite the sprue cavity 12, in which molten material will lodge during an injection shot filling the sprue cavity 12, external and

internal runner systems

13, 16, gate system 17 and mold cavity 9. The plug cavity 71 has an oblique inwardly and upwardly slanting bottom surface, and a semi-circular top surface (FIG. 2) slanting downward and outward from the upper end of the bottom surface.

When the cast has solidified the mold is opened by moving the movable die part 6 an initial distance d (FIG. 3) in the direction of arrow A away from the fixed die part 3. During such initial opening of the mold the solidified cast will remain anchored horizontally to the movable die part 6 by the internal runner system 16 and plug cavity 71, and vertically by the gate system 17.

While the movable die part 6 is maintained at the initial distance d from the fixed die part 3, the runner ejector beam 34 is lowered by the hydraulic cylinder 46 from the raised position of FIGS. 1, 2 and 3 to the lowered position of FIGS. 4 and 5. This will thrust the runner ejector pins 36-39 into the

runner passages

24, 26, 27 and 28 with the result that the solidified casting material in the internal runner passages will be broken from the solidified casting material in the gate passages at the inner ends of the latter where they merge through small orifices with the internal runner passages. Such breaking will cause the body of solidified casting material comprising the internal and external runners 16, 17', the sprue l2 and the plug 71 to drop through the space between the separated die halves as indicated in FIG. 4.

A conveyor system, not shown, may be arranged below the mold for returning the

hot waste piece

12, 13', 16', 71 back to the melting furnace, utilizing the residual heat to reduce furnace recovery time or allow a smaller furnace.

After the runner ejector beam 34 has been lowered, the spacing between the stationary and movable die halves is increased from the distance d to the distance D in FIG. 5. As the movable die part 6 moves to the distance D, the ejector plate 49 abuts the stationary bumper pins 59, 61, 62 and 63, with the result that the casting ejector pins 51, 52, 53, 54 and 56 are shifted in the movable die part in a casting ejecting direction as shown in FIG. 5. The casting 9 formed in the mold cavity 9, and the gates formed in the

gate passages

29, 31, 32 and 33 will thus be expelled in one piece from the movable die part, and when the inner ends of the gates clear the outer ends of the gate passages the integral casting and gates will drop through the space between the separated die parts.

A water immersed conveyor, not shown, may be arranged below the mold to deliver the casting to a treatment stage for pickling, chrome plating or the like. The gates which extend from the rear face of the cast article provide mounting studs on which Tinnerman nuts may be installed for securing the article on the structure for which it is intended.

The herein disclosed pin gating of the cast article from the rear also avoids the blemishes which in conventionally side gated castings are produced by the residual metal from inlet and overflow gates.

Finally, the internal runner system of the movable die part reduces the separating pressure to which the die halves become subject during an injection shot.

It is claimed and desired to secure by Letters Patent:

1. A die casting mold comprising a fixed die part having a sprue cavity, an external runner cavity in communication with said sprue cavity, and an external mold cavity spaced from said sprue and runner cavities; a movable die part engageable with and disengageable from said fixed die part and having gate means and internal runner means in communication with each other, said gate and runner means being adapted. upon engagement of said movable die part with said stationary die part, to communicate with said mold cavity and with said external runner cavity, respectively; runner ejector means movably mounted on said movable die part and operable, upon disengagement of said movable die part from said stationary die part, to eject solidified casting material from said internal runner means; and casting ejector means movably mounted on said movable die part and operable, upon disengagement of said movable die part from said stationary die part, to eject solidified casting material from said gate means integrally with a casting formed in said mold cavity.

2. A die casting mold as set forth in claim I, wherein said movable die part has an external plug cavity in facing relation to said sprue cavity of said fixed die part, said plug cavity being undercut so that cast material lodged therein and in said external runner means will be releasably anchored to said movable die part for withdrawal therewith from said fixed die part.

3. In a die casting mold having a parting line, the combination of a fixed die part having external runner means along said parting line, a sprue cavity extending transversely of and communicating with one end of said runner means, and a mold cavity along said parting line spaced from said runner means and sprue cavity; a back and forth movable die part having gate means in angular relation to said parting line, and internal runner means merged with and extending angularly from said gate means; said gate and internal runner means communicating, in the closed condition of the mold, with said mold cavity and with the other end of said external runner means, respectively, on said parting line; runner ejector means movably mounted on said movable die part and operable, in the open condition of the mold, to eject solidified casting material from said internal runner means together with casting material solidified in said external runner means and sprue cavity; and casting ejector means movably mounted on said movable die part and operable, in the open condition of the mold, to eject solidified casting material from said gate means integrally with a casting formed in said mold cavity.

4. A die casting mold as set forth in claim 3, wherein said internal runner means are afforded by a plurality of feed passages in transversely spaced relation to each other, and wherein said gate means are afforded by a plurality of elongated passages in communication, respectively, with said feed passages.

5. A die casting mold as set forth in claim 4, wherein said runner ejector means comprise a plurality of reciprocable pins in axial alinement respectively, with said feed passages.

6. A die casting mold as set forth in claim 4 wherein said casting ejector means comprise a plurality of reciprocable pins in transversely spaced relation to each other and movable endwise in the general direction of said gate passages.

7. A die casting mold as set forth in claim 3, wherein said external runner means are afforded by a trunk cavity merged at one end with said sprue cavity, and by branch cavities merged with the other end of said trunk cavity, and wherein said internal runner means are afforded by a plurality of feed passages extending, in the closed condition of the mold, transversely of said branch cavities in merging relation therewith.

8. A die casting mold as set forth in claim 7 and further comprising a plug cavity in said movable die part along said parting line and in facing relation to said one end of said trunk cavity; said plug cavity being obliquely undercut so that cast material solidified therein and in said trunk cavity will be releasably anchored to said movable die part for withdrawal therewith from said fixed die part.

9. A die casting mold as set forth in claim 4, wherein said elongated gate passages are tapered toward their junctures with their respective feed passages.

10. A die casting mold as set forth in claim 9, wherein said gate passages extend in the general direction of back and forth movement of said movable die part, and wherein said runner passages extend at generally right angles to said gate passages.

Claims

1. A die casting mold comprising a fixed die part having a sprue cavity, an external runner cavity in communication with said sprue cavity, and an external mold cavity spaced from said sprue and runner cavities; a movable die part engageable with and disengageable from said fixed die part and having gate means and internal runner means in communication with each other, said gate and runner means being adapted, upon engagement of said movable die part with said stationary die part, to communicate with said mold cavity and with said external runner cavity, respectively; runner ejector means movably mounted on said movable die part and operable, upon disengagement of said movable die part from said stationary die part, to eject solidified casting material from said internal runner means; and casting ejector means movably mounted on said movable die part and operable, upon disengagement of said movable die part from said stationary die part, to eject solidified casting material from said gate means integrally with a casting formed in said mold cavity.

2. A die casting mold as set forth in claim 1, wherein said movable die part has an external plug cavity in facing relation to said sprue cavity of said fixed die part, said plug cavity being undercut so that cast material lodged therein and in said external runner means will be releasably anchored to said movable die part for withdrawal therewith from said fixed die part.