US2459402A

US2459402A - Mold

Info

Publication number: US2459402A
Application number: US524025A
Authority: US
Inventors: Eric H Zahn
Original assignee: AUSTENAL LAB Inc
Current assignee: AUSTENAL LAB Inc; AUSTENAL LABORATORIES Inc
Priority date: 1944-02-26
Filing date: 1944-02-26
Publication date: 1949-01-18
Anticipated expiration: 1966-01-18
Also published as: NL75417C

Description

Jan. 18, 1949. H- ZAHN 2,459,402

HOLD

Filed Feb. 26, 1944 Patented Jan. 18, 1949 UNITED STATES PATENT OFFICE MOLD Eric H. Zahn,

Pound Rid Austenal Laboratories, N. Y., a corporation of ge, N. Y., aasignor to Incorporated, New York, New York Application February 2.6, 1944, Serial No. 524,025 3 Claims. (Cl. 22-154) This invention relates, generally, to molds, and 'has particular relation to improvements in hollow casting molds having one or more casting cavities the configuration and volumetric proportions of which are the same as a predetermined pattern.

In the production, for example, of wax or like patterns for use is cast and avoidance of distortion of the pattern are of primary importance. As an illustration, in the production of turbine buckets such as disclosed in the copending application of Albert W. Merrick, Serial No. 422,421, led December 10, 1941, now Patent 2,381,459 issued Aug. 7,

ance with the above patent have proved to be highly emcient in casting patterns of wax or proportions ofv the patterns cast therein. This renders the patterns inaccurate and causes corresponding objectionable inaccuracy in the final casting produced in molds formed about the pattern.

pressure to which the mold sections are subjected during the operation of casting the pattern in the mold.

each of the mold sections a forming element of relamounted in hard pressure More specifically, preferably comprises tively soft material means operating through the forming element of that of casting the pattern, whereby the relatively soft forming elements of the mold lsections are not subjected to such pressure and slow flow of the metal of the forming elements, with resultant inaccuracy of the mold cavity, is avoided. Further objects and advantages of my invention will appear from the detail description.

In the drawings:

Figure 1 is a plan view of the lower section of a mold embodying my invention;

Figure 2 is a section taken substantially on line 2-2 of Figure 1, through the upper and lower sections of a mold embodying my invention and through the knockout pins guard plate;

Figure 3 is a sectional view taken substantially on line 3-3 of Figure 2; and

Figure 4 is a fragmentary sectional view taken substantially on line 4-4 of Figure 1.

I have shown my inventiony by way of illustration, as embodied in a mold for producing patterns for articles of generally rectangular shape in plan and of concavo-convex cross section. This'mold comprises an upper section 5 and a lower section 6. In forming section 6 of the mold I first provide a reinforcing member 1 of rectangular shape in plan and suitable thickness, conveniently formed of cast iron, or other suitable reinforcing material, having in its upper face a rectangular recess of uniform depth and of appropriate length and width suitable to the forming element of the mold to be received therein. The reinforcing member 1 is suitably finished by machining or otherwise, and has formed therein suitably disposed registering sockets 8. After the member 1 has been machined and finished and the registering sockets 8 have been applied thereto, a forming element 9 is cast in the recess in member 1, about a suitable pattern, in accordance with the method of my above identified prior patent. This element 9 is cast of a suitable alloy, such as the tinbismuth alloy as referred to in said patent, which is relatively soft and has a low melting point, or of any other suitable material.

It is assumed, for purposes of illustration, that the pattern selected is such as to provide, in the exposed upper face of element 9, which may be referred to as its forming face, a plurality of recesses I of rectangular shape in plan and of arcuate cross section, these recesses -belng connected by pouring passages II of semi-circular cross section extending lengthwise of forming element 9, and relatively short passages Ila, also of substantially semi-circular cross section, extending transversely of forming element 9 and opening from passages Il into the ends of the depressions I0. Incastng the forming element 9 in the reinforcing member 1, the latter member is in inverted position, 4being provided through its then upper wall, which is its bottom wall in the normalposition of member 1, cating sprue and gate openings. The gate opening may are outward of member 1. The reinforcing member 1 is heated to a suitable temperature and the molten alloy is poured or injected into member 1 about the pattern, over which is disposed the rubber membrane, in the manner described in my above referred to patent. After the alloy has cooled and-set to a proper extent, the member 1, with the forming element 9cast and retained in the recess thereof, is rcmoved from the pattern. The sprue and gate openings of the member 1 are lled with the alloy of member 9, providing sprue and gate elements I2 and I3 extending through the bot- '4 tom wall Il of member 1,-as shown. .It will bc noted that the areas of forming element 9 extending outward beyond the passages and depressions in the upper face thereof are ush with the upper face of the surrounding wall of the reinforcing member 1, for a purpose which will appear presently. The forming element 9 is further provided, at the -idcs of passages II and Ila, with narrow horizontal shoulders I and with beveled surfaces I6 extending upward and outward from the shoulders I5, to give the proper parting line for these passages, as will appear more fully later.

After the lower mold section 6 has been pro-Y duced in the manner above described, the pattern is placed in this lower mold section, and the upper mold section is then produced, this upper section comprising an outer reinforcing member I1, conveniently formed of cast iron or other suitable reinforcing material; The reinforcing member I1 is machined and finished, and is provided with registering dowel pins I9, these pins and the sockets 8 being accurately located with respect to each other to assure accurate register of the two mold sections, in a known manner. The reinforcing member I1 is placed upon the lower mold section 6 in accurate register therewith, and over the pattern and the rubber diaphragm disposedvthereover mounted in the lower mold section, after which the molten alloy is poured or injected into the recess in reinforcing member l1. The forming element I8 is thus cast and retained in reinforcing element I1 and is provided with sprue and gate elements and 2 I as shown.

After the lower mold section has been produced in the manner described, it is bored out from its lower face to provide a plurality of suitably disposed rbores 23, from the upper end of each of which extends a concentric bore 24, of reduced diameter, opening into a coaxial bore extending through forming member 9 'at the mid-width of one of the passages II or Ila therein. The upper portion of bore 25 is counterbored to provide a downwardly tapering irusto-conical seat 25a in which s eats the correspondingly shaped head 26 of a knock-out pin 21 slidabiy mounted through bore 24. Pin 21 extends downward beyond the bottom face of wall I4 of reinforcing member 1 and is urged downward, by a compression spring 28 disposed about pin 21 within bore 23 and confined between the wall at the upper end oi this bore and a washer 29 mounted on pin 21 and restrained against downward movement therealong by the pin 3l] pin 21. Spring 28 normally holds head 26 of pin 21 seated against the seat 25a so as to form a huid-tight closure therewith. In the use of the mold, the projecting ends ofthe pins 21 extend into recesses. 3| in a removable steel guard plate 33 disposed at the bottom or back wall I4 of mold section 5.

vReferring to Figures 2 and ment I8 of the upper mold section is provided with rounded projections 34 overlying the depressions I0 in the forming element 9 and deflning therewith mold cavities of concave-convex cross section. the upper edges of which are in thev plane of the upper face of the peripheral wall of 3, the forming elereinforcing member 1 of the lower mold section.

The upper mold section forming element I8 is further provided with lengthwise passages 35 and with relatively short transverse passages 36 cornplementary to passages Il and IIa, respectively, of forming element 9, and has downwardly exsecured through l lower portion of plate 4U ts The sprue and in any suitable being provided with a notch'--42 ,in which the snugly. and reinplate I0, and a sprue opening 43 concentric with socket I2 and extending through the two mold sections and opening into passage il at the top thereof.

The wax is injected into the mold cavity by means of an injector or gun having a nozzle which seats tightly the guard plate 33, the knock-out pins 21 are moved simultaneously upward through the lower known manner, having a mold cavity conforming accurately to the wax pattern. This refractory in the gate or socket 2 mold is then used for casting therein the desired article.

It will be noted that the mold shown and described herein ing to the passages defined by the semi-circular passages or depressions Il, Ila, and v35 and 36 entirety of the alloy, thus eiectlng a material saving in the alloy or other material used for the forming elements of the mold sections.

cavity in said lining from outside said outer members with the mold sections assembled in casting relation, ejector means slidingly mounted in and guided by at least one of said outer members and operable through its softer lining into engagement with the object cast in said cavity to eject same from the casting cavity, said ejector means being normally constrained to a position projecting from the outer surface of the adjacent outer reinforcing member, and a removable guard plate fitting against the outer surface of said outer member in position covering said ejector means and having a recess for receiving said ejector means to guard said ejector means against actuation and permit application of the guard plate to said outer member Without actuating said ejector means.

2. In a casting mold of the class described, in combination, a plurality of complementary mold sections each consisting of an outer hard and wear resistant reinforcing shell member and an inner lining of low [using cast metal softer than said outer reinforcing member and fitting tightly within said outer wear resistant shell member, the face of at least one of said relatively soft linings which is opposed to the cooperating face of the other lining having a casting cavity of a shaft for casting the desired object, said linings completely enclosing and defining. the casting cavity throughout its entire extent so that none of the surfaces of said outer members is exposed to said cavity, registering ingate openings one in said lining and the other in at leastone of said outer members through which the molten material to be cast is introduced into the casting cavity in said lining from outside said outer members with the mold sections assembled in casting relation, ejector means slidingly mounted in and guided by at least one of said outer members and operable through its softer lining into engagement with the object cast in said cavity to eject same from the casting cavity, said ejector means being normally constrained to position projecting from the outer surface of the adjacent outer reinforcing member, and a removable guard plate fitting against the outer surface of said outer member in position covering said ejector means and having a recess for receiving said ejector means to guard said ejector means against actuation and permit application of the guard plate to said outer member without actuating said ejector means, said guard plate being disposed at the bottom of the mold to support the same and said ejector means being adapted to be actuated to ejecting position by placing the cooperating surface of the outer member of the mold upon a support with said guard plate removed.

3. In a casting mold of combination, a plurality of complementary mold sections each consisting of an outer hard and wear resistant reinforcing shell member and an inner lining of low fusing cast metal softer than said outer reinforcing member and fitting tightly within said outer wear resistant shell member, the face of at least one of said relatively soft linings which is opposed to the cooperating face of the other lining having a casting cavity of a shape for casting the desired object, said linings completely enclosing and defining the casting cavity throughout its entire extent so that none of the surfaces of said outer members is exposed to said cavity, registering ingate openings one in said lining and the other in at least one of said outer members through which the molten material to be cast is introduced into the casting cavity in said lining from outside said outer mem- ,bers with the mold sections assembled in casting relation, ejector means slidingly mounted in and guided by at least one of said outer members and operable through its softer lining into engagement with the object cast in said cavity to eject same from the casting cavity, said ejector means being normally constrained to position projecting from the outer surface of the adjacent outer reinforcing member, a removable guard plate fitting against the outer surface of said outer member in position covering said ejector means and having a recess for receiving said ejector means to guard said ejector means against actuation and permit application of the guard plate to said outer member without actuating ysaid ejector means, and spring means confined entirely within the adjacent outer reinforcing' member of the mold and coacting'with said ejector means normally to constrain said ejector means to nonejecting position.

ERIC H. ZAHN.

REFERENCES CITED The following references are of 'record in the file of this patent: I

UNITED STATES PATENTS the class described, in