USRE21461E - toman - Google Patents

Description

y 21, 1940- M. E. TcSMAN Re. 21,461

Y APPARATUS I'OR HOLDING Original Filed llay 27, 1935 3 SheQts-Sheet 2 'n r ,1 h

I 30 I I Z J7? 0 67? for";

fizz/keel f ybvzarz, I? 1 M em 5 NI. Town: Re. 21,461.

' APPARATUS ron HOLDING Original Filed lay 27, 1935 3 'Sheets-Sheet'3 flit/Peel 5? Ewart.

Reiuued May 21,1940

UNITED [S ATES PATENT OFFICE 21.461 APPARATUS FOR MOLDING Michael E. Toman, Berwyn, lll., assignor to Castings Patent Corporation, a corporation of Illinois Original No. 2,088,123, dated July 27, 1937, Serial No.23,677, May 27, 1935. Application for reissue April 27, 1938, Serial No. 204,695

1 Claim- The invention relates to apparatus for casting, and is particularly adapted to be practiced in connection with the production of metallic castings in molds formed from a plastic material such as calcined gypsum. v In one form of the invention, molds are produced from a mixture of calcined gypsum, asbestos pulp and water. When a mold is to be poured, the two parts thereof are assembled in the usual manner and a sheet or pad of yielding material such as asbestos fiber or rubber is placed My principal object is to enable the pressure to be transmitted from the rigid press plates in substantially uniformly distributed fashion over the surfaces of the mold despite faults or irregularities on the outer mold surfaces so that, localized stresses will notbe set up in the fragile mold sections tending to cause fracture thereof or uneven pressure between the parting surfaces which might result in local failure. For example, when the mold material sets in the flask there is a meniscus formed about the mold edges by capil- -lary attraction between the flask and the mold material. Such faults and other irregularities need not be removed before pouring when my apparatus is used.

Other objects and advantages will become apparent as the following detailed description progresses, reference being had to the accompanying drawings, wherein:

Fig. 1 is a front elevation of apparatus for holding a mold, under pressure, duringthemoiding operation;

Fig. 2 is a section taken on line 2-2 of Fig. 1;

Fig. 3 is a section taken on line.38 of Fig. 1;

Fig. 4 is an enlarged fragmentary section taken on line 4-4 of Fig. 1;

Fig. 5 is a section taken on line 5-5 of Fig. 45

Fig. 6 is an enlarged fragmentary section taken online 5-6 ofFig.1;.

Fig. 7 is a longitudinal section taken through a sheet or a pad of yielding material, which sheet or pad embodies a modified form of the invention;

Fig. 8 is a longitudinal section taken through a sheet or pad of yielding material, which sheet or pad embodies another form of the invention;

Fig. 9 is a fragmentary central-section taken through apparatus embodying another form oi'the invention; Fig. 10 is a perspective view of a hollow sheet metal pad which embodies still another form of the invention, and V Fig. 11 is a section taken on line I ll of Fig. 10. The apparatus shown in the accompanying drawings is particularly adapted to be employed in connection with molds formed from calcined gypsum, asbestos pulp and water.- The pattern is usually formed in metal upon a metallic match plate, the flask being secured to the match plate and being provided with a cover plate. The materials from which the mold is to be formed are preferably placed therein and violently agitated after which the mold is permitted to set. The mold is then removed from the 'fiask and is subjected to a drying operation. The dried mold is extremely porous and when fused metal is poured into it, the gases=evolved during the pouring operation vent through the body of themold. Of course, it is readily understood that the mold is made in two or more parts separately formed in suitable flasks which may be identical with each other in construction.

"As. indicated above, the mold members are removed from the flasks before they are assembled for the pouring operation. In fact, it has been found preferable to remove them from the flasks before the drying operation. When a mold is tobe poured, the bottom member of it may be placed uponany suitable support and the top member is then placed upon the lower member and subjected to pressure so that the two parts of the mold will not separate during the pouring operation and allowa fin to be forined which during the operation of removing the fins.

Referring now'to Figs. 1 to 6, inclusive, wherein improved apparatus embodying the invention is 40 v must be removed subsequently. This, of course, increases the cost of producing castings in quan-- tity as each individual casting must be handled l3 which are bolted to some of the cross members l3 and to the uprights ll.

The cross members i2 carry a-plate 23 adapted to support the molds during the pouring operation. In Figs. 1 to 6, inclusive, a mold is identified generally by the reference character 22 and comprises a bottom half or member 23 and a top member or half 24, the mold being formed with the usual mold cavity 25 and a pouring-passage or sprue. 23. In this instance, part of the mold cavity 25 is formed in the mold member 24 and part in the mold member 23. However, in some instances, the mold cavity is formed entirely in one of the mold members although the mold a cavity is closed by the other mold member.

To insure uniform distribution of pressure over the upper and lower mold surfaces even though they may be of somewhat irregular contour,'I emnoted that the plate 33 is provided with an an-' nular shoulder 33 which engages a similar shoulder'on the sprue 31 and holds the sprue 31 in contact with the top ,surface of the mold 1 member 24. I

Abutting against the top surface of a boss 40 formed integral with the plate 33 is a plunger 42 which projects from the bottom end of a vertically disposed cylinder 43 depending from and secured to the cross member ii. The upper end of the plunger 42 is secured to a piston 45 slidably journaled in the cylinder and urged upwardly by a compression spring 46. The upper end of the cylinder 43 communicates through a tube 43 with a port 53 in a valve casing provided with additional ports 52 and 53, the port 53 being an exhaust port. A valve plug 53 (Figs. 1 and 6) rotatably journaled in the valve casing 5| and adapted to be displaced angularly by a lever 51 is provided with a passage 53 extending diametrically thereof and adapted to connect the ports 53 and 52 to each other. The valve plug Iii has another passage 53 communicating with the passage 53. The port 52 is connected to anysuitable supply (not shown) of fluid under pressure by a pipe 63. When the valve plug is in the position wherein it is shown in Fig. 6, the fluid, under pressure, will flow from the pipe ill, through the port 32, the passage 53, the port 30 and thence through the tube 43 to the cylinder 43 to force the piston 45 and the plunger 42 downwardly against the action of the spring 43. Excellent .results have been obtained when theiapparatus is adjusted so that the mold is subjected to a pressure ranging from 1.5 pounds per square inch to a pressure of 2.5 pounds per squareinch. Of course, the mold is subjected -to this pressure duringthe pouring operation and during the initial cooling operation.

v After a mold has been poured, the valve plug 35 is displaced in a counter-clockwise direction (Fig. 6) so that the outer-end of the passage 33 communicates with the port ill andone end of the passage 53 communicates with 'the exhaust port 3. The valve plug 55 then shuts off the supply (not shown) of fluid under pressure and permits the cylinder 43 to exhaust through the tube 43, the port ill, the passages and 53, and

thence through theexhaust port as. This permits the spring 43 to elongate and lift the plunger 42 from the plate 33 so that it may be removed.

tively thick sheets ID of sponge r'ubber, each sheet being faced on one side by a sheet of asbestos I2, the asbestos sheets I2 abutting against the adjacent surfaces of the mold 22 and protecting the rubber sheets I3 from the heat of the fused metal introduced into the mold cavity.

- In practice it has been found that the yielding pads 30 and 3| will function in such manner that if the mold members set and dry so-that the backs of the mold members 23 and 24 have a slight meniscus or other irregularities so that such outer surfaces are not perfectly plane throughout, the pads 30- will yield to lie in substantially contiguous contact with such surfaces.

Of course, when the yielding members are formed of sponge or relativelysoft rubber, they yield a relatively large amount when they are subjected to the pressure set forth above. The substantial uniformity of pressure over the surfaces of the mold parts will eliminate excessive localized stresses which would tend to crack or fracture the fragile molds or to cause a failure of portions of the parting surfaces having small areas of contact. I 1

The operation of-the apparatusdllustrated in Figs. 1 to 6, inclusive, is substantially as follows: After the mold 22 has been formed in the manner described, the two parts 23 and 24 thereof are assembled with the pads 33 and 3| and inserted between the rigid plates 20 and 33, the plate 33 being lifted from a suitable bench, or the equivalent. and placed upon the pad 3| with the sprue member 31 in place. The valve plug 55 is then adjusted so that the fluid, under pressure, exerts its force upon the plate 33 and clamps the mold members 23 and 24 and the pads 30 and 3| between it and the plate 20. The fused metal is then poured into the mold in the usual manner and after it has set and cooled a sufficient length of time, the valve plug 55 is displaced angularly so that the fluid, under pressure, will be exhausted It has been found that when molds are pro-.

duced by practicing the method describedabove, they are substantially free from fins at the part ing line or lines.

In Fig. .1, a pad 330 formed of asbestos fiber is shown. This pad may be employed in place of either of the pads 30 or 3| described above.':

The pad 30a is formed from braided asbestos fiber.

In Fig. 8, a pad 301; is shown which may be employed in place of the pads 30 and 3|. The

pad sub is formed from rubber, It is readily understood that the pads 30a and 33b may oe superimposed upon each other and employed in place of thepads 30 and 3| described above.

In Fig. 9, a mold 22c'identical with the mold 22 is shown. The mold 22c comprises mold members 23c and 240 formed of calcined gypsum, abestos pulp and water. In this instance as in the instance described above, substantially all the free water and a relatively large part of the water in chemical combination has been removed from the mold members 230 and 240 during the drying operation so that they are extremely porous. The bottom mold 230 rests upon a relatively thin sheet metal plate 80 which forms a closure for a chamber 8| connected to any suitable source (not shown) of fluid under. pressure through a valve 82. In some instances, the chamber II will be illled with compressed air to a suitable pressure and in other instances, the chamber 8| will be filled with water. However, it is contemplated that in both instances the sheet metal member 80 will flex and function in the same manner and for the same purpose as the pads 30 and 3| described above. The upper mold member 240 has a weight 85 resting upon it, which weight is apertured to hold the sprue member 88 having the same function as the sprue member 31 described above.

In Figs. 10 and 11, another embodiment of the invention is illustrated. Thus, a hollow metallic pad is designated generally by the reference character' and comprises top and bottom walls 9| and 92, respectively, which have their marginal portions welded to each other. The walls 9| and 92 are formed from relatively thin sheet metal and form a chamber 93 into which compressed air or water may be introduced through a pipe 95. It is contemplated that thepad 90 may be employed in place of the pads 30 and II and that it will yield and function in substantially the same manner as the pads Ill and 3|.

While I have shown and described certain embodiments' of my invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claim, in which it is my intention to claim all novelty inherent in my invention as broadly as permissible, in view of the prior art.

I claim as my invention.

Apparatus for clamping together complementary mold members for the pouring operation, comprising pressure creating means, an open-topped, rigid metal receptacle havingthe bottom thereof engageable by said pressure creating means, a thin, flexible metal sheet closing the top of said receptacle, engageable directly with a surface oi a mold member and deformable to conform substantially to the irregularities in such mold 'suri'ace, and fluid filling such closed receptacle to afford internal support for said thin, flexible metal sheet, and to press it against the irregular mold surface with substantially uniform pressure over the entire area of said sheet in transmitting to the mold the pressure exerted on said pressure member by said pressure creating means. I

MICHAEL E. TOMAN.

Images