US2198497A

US2198497A - Casting press plates

Info

Publication number: US2198497A
Application number: US206149A
Authority: US
Inventors: Henry F Hagemeyer
Original assignee: CASTINGS PATENT CORP
Current assignee: CASTINGS PATENT Corp
Priority date: 1938-05-05
Filing date: 1938-05-05
Publication date: 1940-04-23
Anticipated expiration: 1957-04-23

Description

Agi! 23, 1940.

H. Fl HAGEMEYERA 2,198,497

cAsTING PnEss .PLATES Fmd'uays, 193e mi@ Wm@ E@ Q MW@ Dil El man@ TTF. 3A.l I

INVENTOR HENKYf/fdwmx SATES PATENT ori-Alca CASTING PRESS PLATES Henry F. Hagemeyer, Chicago, lll., assigner to Castings Patent Corporation, a corporation of Illinois Application May 5, 1938, Serial No. 206,149

6 Claims.

My invention relates to casting presses, and more specifically to pressure plates used in conjunction with a press for holding together the cope and drag of a mold during the operation of pouring the molten metal into the mold.

In pouring a mold it is desirable to have the mold sections pressed together with suicient force to prevent the molten metal from escaping between the parting surfaces under the pressure exerted by the metal as it flows into the mold cavity. To enable better regulation and quicker application of pressure to A'the mold sections I prefer to use a fluid pressure cylinder, as illustrated in my copending application Serial No. 207,932, filed May 14, 1938, for Casting mechanism, instead of weights or clamps. My invention, however, is adapted for use with any of these types of pressure means.

In preparing molds of the plastic or gypsum base type, it has been found that the mold material sets with more or less of a meniscus on its outer or exposed surface. When smooth, rigid, pressure plates have been used, therefore, it has been necessary to scrape or otherwise finish the back of each mold section to a plane surface in order to obtain uniform pressure over the entire area thereof, which is necessary to prevent unequal or warping stresses in the mold tending to crack it, and to prevent excessive localized pressure between small areas of the parting surfaces. Such smoothing of the mold section back'takes considerable time which increases the expense of preparing the molds, and further is likely to result in breaking off corners or edges of the brit- 35 tle dried mold.

I have found that the pressure of the pressing mechanism' may be distributed substantially uniformly over the back of a mold having a slight concavity or meniscus by the use of a rigid plate having relatively sharp ridges or projections about its margin with ridges. or projections of greater area on its central portion, or even with an unbroken central portion. It is-preferable, however, to have grooves throughout the surface of the plate to permit escape of gas exuding through the mold, and I also prefer that all the projections be of the same height.

My principal object, therefore, it to provide a pressure plate to transmit pressure from pressure creating meanssubstantially uniformly over the surface of a mold having a slightly concave contact surface or one having a meniscus.

Another object is to provide such a plate which will be adapted for use on different molds having contact surfaces with more or less concavity or meniscus.

A further object is to provide a pressure transmitting plate which will not interfere with and may expedite the'escape from the mold back of gas exuding through the mold body from. the cavity.

It is also desired to make such mechanism compact and durable, although economical to construct and efllcient in use.

Other objects will be made clear in the following detailed description of the preferred embodiment of my invention which is shown in the accompanying drawing to illustrate the principles and operation of such invention. The novel features thereof are defined in the appended claims.

Fig. 1 is a plan View showing one half of the preferred form of my pressure plate, which is symmetrical about the center line shown, and

Fig. 1A is a plan view showing one half of a modified form of such plate, als`o symmetrical about its indicated center line.

Fig. 2 is an end elevation of either the plate of Fig. 1 or that of Fig. 1A.

vFig. 3 is a side elevation of the half plate of Fig. 1, and

Fig. 3A is a side elevation of the half plate of Fig. 1A.

Fig. 4 is a side elevation of the pressure plate and mold assembly, illustrating the use of plates such as shown in Figs. 1A and 3A.

Fig. 5 is a fragmentary perspective view of a portion ofthe plate illustrated inFigs. 1 and 3,-

and

Fig. 6 is a fragmentary end elevation with parts in section, showing the engagement of a pressure plate with a mold face.

As has been mentioned, the projections or ribs on the pressure plates serve two purposes, first that of providing intermediate grooves to convey to the edge of the mold and plate assembly gases exuding fromv the mold cavity through the body` thereof and escaping from the mold back, and second, to distribute the pressure substantially uniformly over the mold sections and to avoid appreciable unequal stressing thereof when the mold back has a slight concavity or meniscus. To accomplish the first purpose it is not necessary that the projections be of non-uniform area, but to equalize the pressure distribution over the concave mold back the marginal projections should beyof smaller area than the central ones, to penetrate into the fillets a distance suiiicient tok enable the central projections to engage the mold back rmly. As far as the second purpose is concerned, it will be appreciated-that the central portion might be unbroken by grooves.

A pressure plate designed for a. nearly square mold should be like that indicated as I in Figs. 1 and 3, having two` sets of groovesl I0 and I I which mutually intersect. The plate is preferably rectangular in shape and one set of grooves consists of parallel grooves which most conveniently are also arranged parallel to the longitudinal edges of the plate. Likewise, the cross grooves Il are preferably parallel to each other and parallel also to the ends of the plate I, so that the grooves of the two sets intersect at right angles.

In the central portion of the plate may be projections in the form of ribs I2 which are defined by the respective grooves Ill. It will be noted that these grooves extend beyond the edge of the mold M resting thereon, as shown in Fig. 4, to be in free communication with the atmosphere when the plate is in pressing engagement with the mold. Preferably, these grooves extend clear to the edge of the plate I to form notches therein as shown in Fig. 2. The gases escaping from the mold back will thus have a positive passage for their exit from between the mold and the pressure plate. For still better ventilation, the grooves Il may also extend clear to the edge of the plate to form notches therein as shown in AFig. 3. Such provision is desirable where the meniscus is pronounced. As shown in Fig. 6, the meniscus tends to clog the grooves partially and the increase in the exit opening effected by the cross grooves compensates for such clogging. If desired, the grooves may be made progressively wider toward the edge of the plate to increase the vent still further.

To obtain substantial uniformity of pressure over a mold surface having a meniscus, the surface of a rigid pressure plate might be made complementally convex. Such an expedient is not entirely satisfactory, however, for the same plate must be used on' mold surfaces of widely varying degrees of concavity, and such a rigid plate could be made accurately complemental to a mold of only one degree and shape of concavity. Moreover, the machining of a plate surface -substantially plane in the center and having'a margin with a convexity progressively varying in degree is a difficult task. I have therefore made the projections, including the ribs or ridges I2 and the buttons I3 all of the same height, but have spaced the grooves nearer together at the margins than in the central portion of the plate. The central'projections defined by such grooves are consequently of greater width and area than thoseat the margins. As such a plate is forced against the face of a mold the small marginal projections will beI compelled to penetrate into the meniscus, as indicated in Fig. 6, until the central portion of the plate seats on the plane central portion of the mold back.

Over the central portion of the platethe ribs or projections should be of substantially 'the same two successive grooves nearer the center of the plate. Likewise, the Width of every projection or rib will be at least-as great as that of every projection or rib disposed closer than itself to the edge of the plate. Because more gas will ordinarily be liberated from the central portion of the mold surface, I prefer that the width of the central grooves be greater than that of the marginal grooves.

Obviously, the number and widths of the projections, the number, widths and depths of the' grooves, and the relative widths and depths of the marginal and central grooves and projections, as well as of the two sets of grooves and projections, may be varied considerably according to the average requirements of a particular installation. Precautions should be taken, however, to make the marginal projections sufliciently narrow so that the. meniscus will be penetrated deeply enough to enable the central portion or projections'ofthe plate to come into firm pressing engagement with the mold without the marginal portions of the mold being subjectedto excessive pressure. In order to allow the marginal projections to penetrate thus but still to exert finally substantially their proportionate share of 'the pressure on the mold, I prefer that at least the marginal projections be tapered from their bases to their ridges, so that as the penetration of yeach projection increases the pressure exerting area thereof also becomes progressively greater.

If the mold, instead of being nearly square, is relatively long and narrow, the meniscus along the ends of the plate may be negligible. For such cases the cross grooves Il may be omitted and the ribs I2 may extend uninterruptedlyrfrom end to end of the plate, as shown in Figs. 1A, 3A and 4. The notched formation of Fig. 2 will press into and perhaps serrate the slight meniscus at each end suiciently to enable the central portions of the ribs to come into contiguous engagement with the mold back. The narrow ribs along the longer edges of the plate will, of course, penetrate into the meniscus along each such edge as has been described and as shown in Fig. 6.

While, for purposes of illustration, the construction of the lower pressure plate has been shown in detail, the -upper pressure plate 2, pictured in Fig. 4, will b e provided with projections and grooves in the same manner as plate I. An escape for pouring gases and substantial uniformlty of pressure will therefore be provided -for both upper and lower mold surfaces.

Escape of the air and pouring gases from the mold cavity through the mold body may, if desired, be expedited by sealing the edges of the pressure plates and the groove ends, .and then evacuating the grooves through the body of each plate to increase the pressure differential between the mold cavity and mold back. Such lowered pressure would also induce ow of air into the edges of the porous mold and out the mold back, tending to cool the metal in the mold cavity, such cooling being greatest in the marginal portions of the mold and progressively decreasing toward the center, so that solidication, and cooling, and hence shrinkage, would occur in the order of first the castings from .their outer portions inward, then the gates, then the runners and nally the sprue.

As my invention, I claim:

1,. A mold engaging pressure plate having on one face thereof mold engaging projections defined by intersecting sets of generally parallel grooves, the spacing'between adjacent edges of successive adeuda? 'to the plate edge than such rib, and the centrally grooves of each sei;` in the central portion of the plate being greater than the spacing between adjacent edges of successive grooves of the same set near the margin of the plate.

2. A rectangular mold engaging pressure plate having on one face thereof mold. engaging projec tions dened by a set of parallel grooves disposed parallel to opposite edges of the plate and a second set of parallel grooves disposed perpendicular to said first set of grooves and parallel to the other opposite edges o the plate, the spacing between adjacent edges of successive grooves of each set in the central portion of the plate being greater than the spacing between adjacent edges of successive grooves of each. set, respectively, disposed near the edge of the. plate.

3. A mold engaging pressure plate having on one face thereof coplanar mold engaging projections adapted to be in simultaneous engagement with a mold back, and defined by a plurality ofv successive grooves, the spacing between adjacent edges of successive grooves in the central portion o the plate being greater than the spacing between adjacent edges of successive grooves near the edge of the plate.

4. A rectangular mold engaging pressure plate having on one face a plurality of parallel ribs disposed parallel to opposite plate edges, each rib being at least as wide as every rib disposed closer disposed ribs being Wider than the ribs adjacent to the plate edge, and the space between adjacent edges of adjacent centrally disposed ribs being greater than the space between adjacent edges of adjacent ribs near the plate edge.l

5. A mold engaging pressure plate having on its mold engaging face a plurality of mold engaging buttons of .small mold engaging surface area spaced along the plate edges, and in the central portion of such face a mold engaging projection of relatively large mold engaging surface area as compared to that of such a button along the plate edge.

6. Al mold engaging pressure plate, having a planar mold engaging surface including a cen= tral contact zone and a marginal contact none adapt@ to be in simultaneous engagement with a mold baclr, both zones of contact being interrupted by depressions denning a plurality of narrow mold engaging surface portions in the marthe central lzone, adapted to abut the central portion of a mold back, thereby to distribute substantially uniformly over the mold back the' e pressure plate.

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