US3528480A - Molding machine pressure head - Google Patents

Description

Sept. l5, 1970 R. J. SMITH ETAL l .MOLDING MACHINE PRESSURE HEAD s sheets-sheet 1 Filed Nov. 21, 196'? 'Fmi William H. Fromakn Sept. 15, 19519v R;J.jsM|1'H 'ET A1. 3,518,480

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j lfqir Attorney l Inventors:

Russell J. Smith /9 william H. Froman nomma mamma rnsssun um Filed Nov. 21 1967 a sheets-sheet a Inventors;

Russell Smith y William H. Froman their `Attorney United States Patent O 3,523,480 MOLDING MACHINE PRESSURE HEAD Russell J. Smith, Toledo, and William H. Fromau, Luckey, Ohio, assignors to Midland-Ross Corporation, Cleveland, Ohio, a corporation of Ohio Filed Nov. 21, 1967, Ser. No. 684,765 Int. Cl. BZZc 08; B301) 5/02 U.S. Cl. 164-171 10 Claims ABSTRACT OF THE DISCLOSURE A molding machine pressure head for compacting molding sand in a flash against a pattern, the head having a lower rubber diaphragm acting alone under fluid pressure applied directly thereto for initially compacting the sand and being backed for final compacting by a multiplicity of individually vertically movable plungers uniformly powered by higher fluid pressure applied thereto through a separately pressurizable upper diaphragm. The plungers slide in apertures therefor in vertically spaced fixed guide plates mounted between the diaphragms, bottom for limiting their downward movement on the lower plate, and are of such number and arrangement as uniformly to compact the sand even of gang molds or single molds having numerous high spots.

BACKGROUND 'OF THE INVENTION Heretofore, some of the molding machines used for making sand molds for casting steel, have had pressure heads capable of compacting in two stages the molding sand filling a flask above a pattern. In such a machine, the pressure head has separately pressurized upper and lower rubber diaphragms, the lower acting alone in the first stage and being backed in the second by rubberfaced ends of a pair of cans sliding vertically against rubber rings and powered through the upper diaphragm. While the pressure head is usually effective in making single molds, its pair of cans,V even with their rubber facings, have not proved satisfactory in their final cornpacting for either gang molds or single molds having a number of high points. It is with this problem that the present invention is primarily concerned.

SUMMARY OF THE INVENTION The primary object of the present invention is to provide a molding machine pressure head which generally resembles the prior two-stage head, above described, but improves thereupon in being effective in making gang molds and single molds having a number of high spots, as well as usual single molds.

Like the prior two-stage pressure head in having separately pressurized lower and upper rubber or like elastic diaphragms for applying pressure respectively at one level for the initial compacting and at a higher level for the final compacting, the improved pressure head replaces the prior pair of cans by multiplicity of rigid, individually vertical movable plungers fitted compactly in the space between the diaphragms and each of such small cross-sectional areas relative to that of the head as to accommodate any height irregularities in a pattern, whether few or many. Each plunger has a head and a depending stem of reduced cross-section, the distal ends of which are presented to the diaphragms, and the plungers are individually guided against both rotation and cocking in vertically spaced guide plates fixed between the diaphragms, on a lower of which, apertured for their stems, they bottom and are normally supported. In the preferred pressure head the stems of all of the plungers are uniform in their dimensions. The heads of the plungers are uniform in crosssectional area and together substantially laterally fill the space between the diaphragms, but outside plungers next to the periphery of the lower chamber preferably have 3,528,480I Patented Sept. 15 1970 ICC longer heads for completing the final compacting first adjacent the periphery of the mold to minimize lateral flow of sand therewithin when the force of the inside plungers is applied.

The foregoing and other objects and features of the invention will appear hereinafter in the detailed description, be particularly pointed out in the appended claims, and be illustrated in the accompanying drawings, in which:

FIGURE DESCRIPTION FIG. l is a side elevational view of a molding machine incorporating a preferred embodiment of the improved pressure head of the present invention;

FIG. 2 is a side elevational View on an enlarged scale of the head of FIG. 1;

FIG. 3 is a top plan view of the head;

FIG. 4 is a horizontal sectional view taken along lines 4-4 of FIG. 2; and

FIG. 5 is a fragmentary vertical sectional view on an enlarged scale taken along lines 5-5 of FIG. 3.

DETAILED DESCRIPTION Referring now in detail to the drawings in which like reference characters designate like parts, the improved pressure head of the present invention is designed for use on a molding machine on which the head and a flask filled above a pattern with molding sand or other suitable particulate molding material, are adapted to be moved vertically relative to each other for ramming the head against the sand. Of that type, the molding machine 1, to which the improved pressure head 2 has been applied for purposes of illustration, has a frame 3 of rectangular cross-section formed of upright columns 4 connected at top and bottom by upper and lower frameworks or cross-members 5 and 6, respectively. Upstanding from the lower framework 6 are laterally spaced guide posts 7 slidably mounting and guiding a ram table 8 which is supported on and movable vertically by a hydraulic or other suitable ram 9 acting vertically between the table and the lower framework 6.

On the ram table 8 is mounted a pattern stool 10 carrying or mounting the gang or other pattern, indicated at 11, and its pattern plate (not shown) used in making the cope or drag mold of the particular run. As usual, flasks for the molds of the run will be transported to and from the machine 1 on a roller or other suitable conveyor (not shown) and, within the machine, each flask 12 suitably is supported in absence of the pattern stool on rollers 13 mounted on the frame columns 4 and underlying and engaging the flasks peripheral bottom flange 14. During making of a mold the flask will be lifted from the rollers 13 and supported by the pattern stool 10 in a laterally fixed position about the pattern 11. In the illustrated machine the pattern stool is shown in an intermediate position in which it has lifted the pattern from the supporting rollers 13 to a sand-filling position below the pressure head 2.

To facilitate filling of the flask 12 with molding sand, the pressure head 2 in the illustrated machine is releasably attached to and suspended from the underside of a carriage 15 disposed immediately below the upper framework 5 and shuttleable horizontally on rollers 16 mounted on the frame columns 4 between an operative or molding position vertically aligned with the flask and an outof-the-way or sand-filling position in which the flask is open or exposed for filling by gravity with molding sand through the upper framework. Thrust blocks 17, interposed between the upper framework and the carriage in the latters molding position, act therebetween for transmitting to the frame 3 the force or thrust of the ram 9 on the pressure head 2 during molding.

The improved pressure head is comprised of a rigid, hollow, bottom-opening housing 18 ywhich usually will be generally rectangular in horizontal cross-section. Closed at the sides, the housing 18 conveniently has its sides or side walls 19 formed by a suitably unitary, rectangular or box-shaped, hollow and open-ended casing or frame 20 and, as its top or top wall 21, a cover or cap plate bolted to the upper end of the casing and projecting laterally therebeyond for bolting or other releasable attachment to the underside of the carriage 15. Attached to and covering the opposite ends of the casing 20 are vertically spaced elastic or flexible upper and lower diaphragms 22 and 23, of rubber or other elastomeric material, hereinafter termed generally rubberj suited for long life under the pressures and wear to which they will be subjected in service. The diaphragms are clamped at their peripheries to the adjoining ends of the casing 20, the upper 22 between the casing and the cap plate 21 and the lower 23 between retainer or clamping rings 24 bolted to the casings lower end, the clamping pressure in each case suitably being limited by spacer bushings 25 through which the attaching bolts 26` are inserted. As subjected to more wear, the lower diaphragm 23 usually should be the thicker, the illustrated arrangement in which the upper diaphragm is single thickness and the lower of double thickness, being very satisfactory.

The upper diaphragm 22 forms with the cap plate 21 an upper pressure chamber 27 within the housing 18, which conveniently is pressurized or supplied with fluid pressure through a supply line 28 leading from a suitable source through the cap plate. Separated from the upper chamber 27 by the upper diaphragm 22 is a lower pressure chamber 29 bounded vertically by both diaphragms and contained laterally in the housing. This lower chamber 29 is individually or separately pressurizable or suppliable with fluid pressure through a second supply line 30` leading from a suitable source through a side wall 19 of the casing 20 between the diaphragms. At the molding machine 1, both of the supply lines 28 and 30v conveniently are mounted on and extend upwardly along one of the frame columns 4 and, therebetween and the pressure head, are flexible to accommodate the shuttling of the carriage 15. Each line also is suitably valved for regulating the pressure introduced or injected into the associated chamber and the supply line 30 also preferably includes beyond its valving a reservoir 30a to compensate for the greater volume of the associated lower chamber.

Mounted in the lower pressure chamber 29 laterally within or inside casing 20 and between the upper and lower diaphragms 22 and 23 and extending laterally over the entire chamber in a rectangularly reticulated or other suitable arrangement and in `close or compact juxtaposition, are a multiplicity of individually vertically movable plungers 31. Preferably equally spaced from each other and arranged in rectangular reticulation with a multiplicity of rows parallel to each side 19 of the casing 20, the plungers 31 individually are very small or diminutive in cross-sectional area or horizontal crosssection relative to the lower chamber as a whole. Each plunger 31 has as its upper portion a head 32 and its lower portion a stem 33 depending from and of reduced cross-section relative to the head and the heads of all preferably are uniform in cross-section, as are their stems. The plungers present their distal or opposite ends to the upper and lower diaphragms 22 and 23 for engagement with the adjoining thereof and, as shown, it is preferred that their upper ends 34 be substantially at and their lower ends 35 outwardly rounded or convexly spherical.

The plungers 31 are individually mounted in and guided in their individual vertical movements by a pair or plurality of vertically spaced upper and lower guide plates 36 and 37, each spaced vertically from the adjoining end and extending horizontally across and substantially coextensive laterally with the inside of the casing and supported in fixed position therein on the side walls 19. While the guide plates 36 and 37 might be fixed to the side walls, it is preferred to X, Qr predetermine 4 their vertical positions relative to the side walls during the molding operation by preferably laterally continuous shims or spacers 38 slidably fitting those walls and lining or facing the insides thereof between and beyond the guide plates.

Normally held in assembled relation by the upper of the clamping rings 24, the shims, along with the guide plates and the plungers, can be removed at will through the bottom of the housing 18 simply by detaching the rings from the casing 20. Thus, Iwithout removing the pressure head and with a minimum downtime of the molding machine, the shims, the guide plates and plungers can be removed as a unit and replaced in whole or part by an identical unit or part for rapid repair or by a different but interchangeable unit or part for changing the operating characteristics of the pressure head. Conversely, when the various parts of the pressure head are in assembled relation, the upper and lower diaphragms 22 and 23 effectively gasket against leakage from the pressure chambers 27 and 29 the joints between the members by which they are clamped, leaving for otherwise gasketing to complete the seal only the joint between the upper of the clamping rings 24 and the lower end of casing 20.

For mounting the plungers 31 in horizontally or laterally spaced relation in the preferred rectangularly reticulated or other desired arrangement, the upper and lower guide plates 36 and 37 are interrupted vertically by corespondingly arranged apertures 39 and 40, respectively, each paired and vertically aligned with an aperture in the other plate. Each pair of vertically aligned apertures slidably receives or seats one of the plungers 31 with its head 32 in the upper aperture 39 and stem 33 in the lower aperture 40 of the pair, in each case with a close sliding fit. The desired non-rotative mounting of the plungers can be obtained by making either or both of the heads 32 and stems 33 of the plungers square or otherwise out-of-round, but the preference is to make the heads and their apertures 39 square and the stems and their apertures 40 round or cylindrical. In any case, since the stems are reduced relative to the heads, the heads will not pass through the lower guide plate and, by acting relative thereto as stops, will enable the plungers normally to be supported and bottom on the lower plate and be limited thereby in their downward movement.

Ordinarily the stems 33 will be uniform in length and in normal position project or extend below the lower plate 37 to about the level of the lower diaphragm 23. The plunger heads 32 also may be uniform in length and in normal position project or extend above the upper plate 36, but, as will be explained later, it is preferred that the outside or peripheral plungers closest or next to the sides 19 of the casing 20 and thus the periphery of the lower pressure chamber 29, have longer heads which are uniform in length among themselves.

In the operation of the improved pressure head 2, it is not necessary that the plungers 31 depend to a substantial extent upon gravity for a downward force, their mission, instead, being to apply through the lower diaphragm 23 the downward force applied to them through the upper diaphragm 22 by the pressure in the upper chamber 27. To reduce the load that the lower guide plate 37 otherwise would normally have to carry, the plungers therefor are rigid but light-weight and, as they only have to withstand compressive forces, most conveniently are solid and made of a suitable plastic, rather than being of hollow or solid metal construction.

In the operation of the molding machine 1 in making a mold, the empty flask 12 then at the machine, when lifted off the supporting rollers 13 by the pattern stool 10, surrounds or encloses the pattern 11 and is closed at the bottom by the pattern plate (not shown). Held by the ram 9 at a convenient height below the level of the pressure head 2, the flask 12, after the pressure head has been shuttled out of the way on its carriage 15, will be filled by gravity through the upper framework 5 with the particulate material, usually molding sand, of which the mold is to be made, any excess of which will be struck off by suitable means (not shown) when the filling is completed. After the pressure head has been returned to molding position, the lower pressure chamber 29 will be pressurized for initiaLcompacting, usually to a pressure of around 35 to 40 p.s.i., causing the lower diaphragm 23 to bulge below the plungers 31. Either during or after this pressurizing the ask 12 will be advanced or raised by actuation of the ram 9 to bring the lower diaphragm into contact with the surface of the molding sand in the flask and stop in its advance at a level at which the pressure upon the sand is that in the lower chamber 29 applied through the diaphragm. Under this pressure, which is uniform over the entire surface, the sand is caused to flow to fill any voids in the mold and be partly compacted about the pattern, the flexibility or elasticity of the diaphragm enabling it to yield as necessary to accommodate height irregularities in the pattern.

After the initial compacting by the lower diaphragm 23 alone, the ram 9 is again actuated to advance or raise the ask 12 to a higher level. The pressure applied by the ram during that advance necessarily being higher than the pressure in the lower chamber 29, the lower diaphragm will be pushed up against the lower ends 35 of the plungers, the advance usually continuing until all of the plungers have been unseated from the lower guide plate 37. As the ilask is stopped in this higher position, the upper chamber is pressurized to a higher pressure than that in the lower chamber, usually around 80 p.s.i. The peripheral or outside plungers come into play at that time, their longer heads 32 causing them to react first to the pressure in the upper chamber 27 and enabling them to compact the sand about the periphery of the mold and so limit lateral flow of the sand under the force of the inside plungers when the latter come into play.

When all of the plungers have been brought into play for transmitting to the lower diaphragm 23 the force applied thereto by the upper diaphragm 22, the lower diaphragm will be able to yield almost as though it were unbacked by the plungers because of the individual yieldability of the plungers and the very small area of the diaphragm acted on by each. Numerous high spots in a pattern, such as are met in molding gang molds and some single molds, therefore pose no problem and the final compacting of the sand under the pressure in the upper pressure chamber 27 will be uniform throughout the mold.

The two-stage compacting of which the improved pressure head 2 is capable, is practical only if the downward forces on the sand in the flask are those applied through the lower diaphragm 23. Consequently, the flask cannot abut and must contain or receive the pressure head 2 and, as in the illustrated machine, the laterial dimensions of the flask and head are appropriate for a preferably snug fit of the head in the ask. Another problem that might be confronted is the blockage by the guide plates 36 and 37 of free flow of the applied pressure throughout the lower pressure chamber 29 not only in the initial compacting but also in the nal compacting in which that pressure is intended to yield to the higher pressure applied to the upper pressure chamber 27. Any difficulty on this score is readily avoided by the provision of slots or apertures 41 conveniently in sides of the plates beyond the plungers for passing the uid, the illustrated pair, one in each plate, being at opposite sides of the lower chamber to ensure by their relative staggering a cross-flow through the chamber. f

From the above detailed description it will be apparent that there has been provided an improved pressure head for a molding machine which is adapted to compact the molding sand or other material of which the mold is composed in two stages and is unaffected in either stage by the number of high spots on the pattern used in forming the mold. It should be understood that the described and disclosed embodiment is merely exemplary of the invention and that all modifications are intended to be included that do not depart from the spirit of the invention and the scope of the appended claims.

Having described our invention, We claim:

1. A molding machine pressure head for two stage cornpacting of particulate molding materials, comprising an open-bottom rigid housing, a lower elastic diaphragm in said housing below a top wall thereof, said diaphragm vertically bounding a lower pressure chamber laterally confined by sides of said housing, said upper diaphragm forming with said top wall an upper pressure chamber and spacing said upper and lower chambers for separate pressurizing thereof, vertically spaced rigid guide plates mounted in said housing between said sides and between and vertically spaced from said diaphragms, and a multiplicity of individually vertically movable rigid plungers mounted in laterally spaced relation in said lower chamber each in vertically aligned apertures in and slidably engaging said plates, said plungers presenting opposite ends to said diaphragms for transmitting force therebetween and means on said plungers engageable with an upper surface of a lower of said plates for bottoming and normally supporting said plungers thereon.

2. A molding machine pressure head according to claim 1, lwherein portions of the plungers and apertures therefor in at least one of the plates are out-of-round for non-rotatively mounting the plungers.

3. A molding machine pressure head according to claim 2, wherein each plunger has a head slidably engaging an upper of said plates and a relatively reduced stem slidably engaging the lower plate.

4. A molding machine pressure head according to claim 3, wherein the stems are uniform in length, and the heads of outside plungers next to a periphery of the lower chamber are longer than the heads of the plungers inside thereof.

.5. A molding machine pressure head according to claim 4, wherein the heads and their `apertures in the upper plate are square, and the stems and their apertures in the lower plate are round.

`6. A molding machine pressure head according to claim 4, wherein the plungers are plastic.

7. A molding machine pressure head according to claim 4, wherein the plungers are mounted in close juxtaposition and each is very small in horizontal cross-sectional area relative to the lower chamber.

8. A molding machine pressure head accordnig to claim 7, wherein the plungers are arranged at equal spacing in a multiplicity of equally spaced rows parallel to each other and opposite sides of the housing and each containing a multiplicity of the plungers.

9. A molding machine pressure head according to claim 4, including shim means releasably mounted in the housing against sides thereof for mounting the plates thereon, and wherein said shim means and plates and plungers are insertable and removable as a unit through the bottom of the housing on detachment of the lower diaphragm therefrom.

10. A molding machine pressure head according to claim 4, including relatively staggered slots in the plates for passing fluid therethrough.

References Cited UNITED STATES PATENTS 2,962,776 12/ 1960 Taccone 164-170 3,172,173 3/1965 `Ellms 164-171 3,284,858 11/1966 Taccone 164-171 I. SPENCER OVERHOLSER, Primary Examiner I. S. BROWN, Assistant Examiner U.S. Cl. X.R.

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