US3036349A - Sprue for molding apparatus - Google Patents

Description

May 29, 1962 R. EDGERTON SPRUE FOR MOLDING APPARATUS Filed March 30, 1960 R0440; [065R ro/v ATTORNEY United rates I 3,036,349 Patented May 29, 19612 free 3,036,349 SPRUE FOR MOLDING APPARATUS Rollie Edgerton, 1603 13th St., Boone, Iowa Filed Mar. 30, 1960, Ser. No. 18,740 1 Claim. (Cl. 22162) This invention relates to molding apparatus generally and more particularly to an improved molding sprue for use during a foundry mold packing operation.

During the typical foundry molding operation, a pattern plate supporting the pattern to be reproduced is placed at the bottom of a container or mold flask. This flask is then filled with sand which is placed under pressure, so that it will be compacted around the patternpro vided on the pattern plate. When the pattern plate is removed, the pattern to be reproduced will remain imprinted in the sand, and the sand will thus form a mold for the casting operation. It is necessary toplace a removable sprue in the sand prior to the compressing operation, so that a passage through the sand to the mold cavity is formed for the molten casting material utilized.

The necessity for providing a removable sprue in the sand mold to form a passage to the pattern plate has presented numerous problems, for when pressure is applied to compress the sand within the flask, pressure is also applied to the sprue. When single piece rigid sprues are utilized, if the sprue does not conform exactly to the height of the flask, pressure applied thereto might result in damage to both the pattern plate and the sprue itself. In a normal foundry operation, patterns and pattern plates of various sizes and thicknesses are utilized, and the flasks used therewith must therefore vary in size and height. When single piece rigid sprues are used for molding, an excessive number of sprues is required, for a sprue which conforms in height to each individual flask must be provided.

In the past, numerous attempts have been made to overcome the difliculties arising from the use of sprues in the foundry operation. The sprues of the prior art have been constructed from single solid pieces of rubber or other elastic material so that applied pressure does not damage the sprue or the pattern plate. These sprues, because of their solid construction, are not readily adaptable for use with flasks of widely varying heights. In an attempt to overcome this height difficulty, other sprues known to the prior art have been constructed from several pieces of non-elastic material which are held in a telescoping relationship by springs or other suitable connecting members. Although these sprues may be easily adjusted in length, and are therefore adapted for universal usage, they do not possess the flexibility of the elastic sprue and are therefore subject to a greater degree, to damage and wear.

It is a primary object of this invention to provide an improved molding sprue capable of withstanding the pressures of a foundry molding operation.

Another object of this invention is to provide a molding sprue having a single piece outer body which will yield under pressure.

A further object of this invention is to provide a yieldable molding sprue which will automatically accommodate, within certain limits, flasks of varying heights.

With the foregoing and other objects in view, the invention resides in the following specification and appended claim, certain details of construction of which are illustrated in the accompanying drawings, in which:

FIGURE 1 is a sectional detailed view in front elevation of the molding sprue of the invention;

FIGURE 2 is a sectional view in front elevation of the sprue of FIGURE 1 applied to a sand mold; and

FIGURE 3 is a sectional view in front elevation of the 2 sand mold of FIGURE 2 with the molding sprue and pattern plate removed.

Referring now to FIGURE 1, the molding sprue of the present invention indicated generally at 10, includes a one piece resilient body 11 of rubber or other suitable yieldable material. Body 11 is flared outwardly at one end to provide a tapered head section 12 at the upper portion of the molding sprue 10. A longitudinally extending core passage 13 is formed through the center of sprue body 11. Core passage 13 includes an upper section '14 which extends through the center of the tapered head 12, and a lower section 15. The upper section 14 of the core passage is larger in diameter than the lower section, so that a shoulder 16 is formed at the junction of the upper and lower sections 14 and 15. The enlarged upper section 14 of the core passage 13 is provided with a liner 17 of metal or other suitable material which is molded in place within the core section. Liner 17 extends upwardly within the core section 14 from the shoulder 16 to a point below the top surface 18 of the tapered sprue head 12. The upper edge of the liner 17 forms a seat 19, which supports an elastic plug member 20. Plug member 20 is of the same diameter as the upper core section 14, and is constructed so that when the plug rests upon seat 19, its upper edge is flush with the upper edge 18 of the tapered sprue head 12.

An elongated metal pin 21 having an enlarged head portion 22 extends from outside of the lower portion of sprue body 11 through the lower section 15 of core passage 13 and into the lower portion of core section 14. The enlarged head portion of pin 21 rests upon the shoulder 16 so as to permit downward movement of the head section 12 when sprue body 11 is compressed. A washer 23 is secured around the lower portion of pin 21 by welding or other suitable means. Washer 23 is positioned so that it abuts the lower edge of sprue body 11 and holds the enlarged head portion 22 of pin 21 in contact with the shoulder 16. The lower portion of pin 21 which projects outwardly beyond sprue body 11 and washer 23, forms a stud 24 which, when inserted in an aperture provided in a pattern plate, acts to hold the sprue 10 in place.

Referring to FIGURE 2, the sprue 10 of the present invention is shown in operational position within a sand mold. The mold forming process consists of placing a flask 25 upon a pattern plate 26 which supports a pattern 27. A gate form 28 may be placed on top of pattern plate 26 to form a gate between the sprue 10 and the pattern 27. Both the gate form 28 and the pattern plate 26 are provided with an aperture 29 to receive the stud 24 of the sprue 10. With the sprue 10 in position, the flask 25 is filled with molding sand 30. A squeezer board 31 is then placed across the top of the flask so that it rests on the top surface of the sand, and the top edge 18 of the sprue 10. Pressure is then applied to the squeezer board which in turn compresses the sand about the pattern 27 and the sprue 10. As pressure is applied to the head 12 of the sprue 10, the elastic body ll of the sprue will expand, concurrently with being contracted relative to the pin 21. Pin 21 insures that the sprue body 11 will not bend, but will instead bulge outwardly against the sand 30. When the pressure is removed from the squeezer board 31, the body 11 of the sprue contracts and returns to its normal shape so that the sprue may be easily withdrawn from the compressed sand mold.

If the sprue 10 is longer than the height of flask 25 so that the top surface 18 of the tapered head 12 projects above the sides of the flask, the squeezer board 31 will contact the upper surface 18 of the head 12 before contacting the surface of the sand 30. As pressure is applied to the squeezer board, the yieldable elastic body 11 of the molding sprue 10 will be compressed and contracted relative to the pin 21 so as to move downwardly on the pin 21. Continued compression of the yieldable sprue body 11 causes the sprue to decrease in length until the squeezer board 31 contacts the surface of the molding sand 30. Thus the molding sprue automatically adjusts itself for use with flasks of varying heights within the compression and extension limits of the 'sprue'. i V

, FIGURE 3 shows the sand mold 30 after thecornpression process has been completed and the pattern plate, pattern, gate form, and sprue have been removed.

Moltenmater'eial may now be poured through the aperture 10a formed by the sprue. This molten material will flow from the aperture 10a through the gate 28a to the molded pattern 27a. i

It will be readily apparent to those skilled in the art that the present invention provides a suitable and effective molding sprue which is automatically adaptable for use with molding flasks of varying sizes. This invention may besubject to numerousmodifications well within the purview of the inventor who only in tends to be limited to a liberalinterpretation of the specification and appended claimr w I claim:

A molding sprue comprising a one piece body member of rubber, one endof which is flared outwardly to form a tapered head portion, said body member having a 1ongitudinal core passage provided centrally therethrough, the core passage including an enlarged upper section extending centrally through said tapered head portion and a lower section of smaller diameter than said upper section, a shoulder formed at the junction of said upper and lower sections, a liner provided within said enlarged upper section and extending upwardly from said shoulder to a point below the outer extremity of said core passage, a plug member inserted in said core passage and supported by the upper edge of said liner, and an elongated pin extending through said lower section and projecting from the body member at the end opposite to said head portion, the elongated pin being provided with an enlarged head at one end, and an integrally at tached washer member positioned inwardly of the opposite end thereof in contact with the lower'end of said resilient body member, the enlarged head of said elongated pin normally resting on the shoulder at the junction of said upper and lower core passage sections, to provide for the downward longitudinal movement of said head portion, whereby when pressure is applied to said head portion toward said washer member, said body member is longitudinally contracted and transversely expanded relative to said pin.

References Cited in the file of this patent UNITED STATES PATENTS 275,332 Depew Apr. 3, 1883 411,962 Heaphy Oct. 1, 1889 968,799 Prowse Aug. 30, 1910 1,001,887 Rothbone Aug. 29, 1911 2,275,806 Perazo Mar. 10, 1942

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