US3478812A

US3478812A - Molding machines

Info

Publication number: US3478812A
Application number: US614860A
Authority: US
Inventors: Thomas A Church; George D Davis
Original assignee: INTERN MOLDING MACHINE CO
Current assignee: INTERN MOLDING MACHINE CO
Priority date: 1967-02-09
Filing date: 1967-02-09
Publication date: 1969-11-18
Anticipated expiration: 1986-11-18

Description

MOLDING MACHINES 4 Sheets-Sheet l Filed Feb 9. 1967 FIG nNvENToRs THOMAS A. CHURCH GEORGE D. DAVIS Nov. 18, 1969 T, A CHURCH l-:T AL

MOLDING MACHINES 4 Sheets-Sheet 2 Filed Feb. 9, 1967 nil lax..

.lll

BY /M,

ATTORNEYS Nov. 18, 1989 T, A CHURCH TAL 3,478,812

Y MOLDING MACHINES Filed Feb. 9, 1967 4 sheets-sheet INVENTORS THOMAS A. CHURCH GEORGE D. DAVIS ATTORNEYS. Y Y v Nov. 18, 1969 Filed Feb. 9, 1967 T. A. CHURCH ET AL 3,478,812

MOLDING MACHINES 4 Sheets-Sheet 4 INVENTQRS THOMAS A,cHURcH GEORGE D, DAVIS ATTORNEYS United States Patent O U.S. Cl. 164-183 11 Claims ABSTRACT OF THE DISCLOSURE The foundry machine disclosed herein includes irnproved and novel facilities for adapting, supporting and inverting a match plate while enabling convenient insertion of and removal of the match plate from the machine as well as novel and improved facilities for elevating, squeezing, and impacting the sand mold formed by the machine.

This invention is directed to improvements in molding machines utilized in foundries and is particularly directed to that class of machne which may operate automatically or semi-automatically in order to properly make sand molds.

Molding machines of this general type have been known for many years. Many of them include some table which is operated by power to lift a mold flask together with a pattern plate or match plate upward to a position where a charge of sand is received by the flask. After the charge of sand has been received in the flask, the sand is usually squeezed tightly within the -flask to make the desired mold. Some prior art machines have used some mechanism for imparting impacts or vibrations to the flask during the squeezing operation so as to further enhance the flow of sand within the flask to effect the desired compaction and uniformity of sand distribution. Some other machines have used a mechanism for jolting the flask prior to the squeezing operation. These jolting machines are oftentimes very heavy and expensive. After the sand has been compacted to the desired hardness and density, the match plate or pattern plate is drawn from the mold flask. Thereafter, the machine may be operated to form another mold in another flask. In some prior machines, supporting mechanism has been provided to enable inversion of a match plate, as by rotating it through 180, after the match plate has been removed or drawn from the sand and/or flask. This is done in order to enable selective manufacture of cope halves and drag halves of the mold, with the flask defining the cope half being used with the impression on one side of the match plate, while the flask for defining the drag half of the completed mold is used with the impression or configuration on the other side of the match plate.

Prior machines of the impact-squeeze type have operated satisfactorily but they may not always compact the sand to the hardness and density desired by the foundry operator. Also, while machines of this type have heretofore been operated satisfactorily, the mechanism therein for supporting and rotating a match plate is subject to some operating difficulties, namely, the operation of locating and changing match plates or pattern plates is cumbersome. 1

With the foregoing in mind, the major purposes of the present invention are to provide simple and effective means for lifting a mold flask and squeezing sand therein while enabling the selective use of impact forces to properly cause flow of sand for compaction to the desired hardness and density, the machine being so formed that it enables a rapid and positive roll-over of a match plate by the machine with simple mechanism for locating and changing a match'plate at the same time the machine is so designed and arranged that it is easily adaptable to fully automatic or semiautomatic operation to enable the proper compaction of the sand desired to the same degree in each of a plurality of successive mold-forming operations, these and other purposes of the invention being more apparent in the course of the ensuing specification and claims when taken with the accompanying drawings in which:

FIGURE 1 is a front view of the mold machine incorporating the principles of the present invention;

FIGURE 2 is a side view of the machine illustrated in FIGURE 1;

FIGURE 3 is an enlarged view, with certain parts in section for purposes of clarity, of the lifting and impacting facilities for the match plate and mold illustrated in FIGURE 1;

FIGURE 4 is a plan view of a match plate assembly utilized in the machine illustrated in FIGURES 1 and 2;

FIGURE 5 is a detail view, with certain parts in section for purposes of clarity, of a portion of the match plate supporting and adapting facilities utilized in the machine of FIGURES 1 and 2;

FIGURE 6 is a top view of a supporting element utilized to support the match plate illustrated in FIGURES 1 and 2;

FIGURE 7 is a side view of the element illustrated in FIGURE 6;

FIGURE 8 is a top view of another supporting element utilized with the match plate assembly utilized in the machine of FIGURES 1 and 2; and

FIGURE 9 is a detail view of a drive connection.

Like elements are designated by like characters throughout the specification and drawings.

With specific reference now to the drawings and in the first instance to FIGURE 1, the numeral 10 generally designates a support which is adapted to rest on the foundry floor. A plurality of upstanding supporting standards 11 are fixed to the support 10 for purposes of supporting other elements of the machine illustrated in FIGURES 1 and 2. The 4elements 11 are in the form of cylindrical rods and are positioned in spaced relation so as to define the corners of a rectangle as viewed from the top.

An elevating and supporting table 12 is supported on the piston rods 13 of a pair of upstanding hydraulic elevating cylinders 14. The hydraulic cylinders 14 are supported on opposite sides of a central guiding assembly generally designated at 15. The -guiding assembly 15 includes a guide piston 16 which is slidably received within the cylindrical bore of an upstanding member 17 which is fixed to the support 10. Upon operation of the elevating cylinders 14, table 12 may be reciprocated vertically.

Table 12 forms a support for a pattern stool 18 which is fixed to the top of table 12. The pattern stool 18 serves to support a match plate assembly generally designated at 19. Supports 20 for a mold flask 21 are positioned at a level above the at rest position of stool 18 shown in FIGURE 1. The supports 20 are adjustably clamped to the standards 11 and may include a plurality of rollers 22 in spaced relation to define a rolling conveyor track for the mold flask 21. It should be understood that the guides 20 may be extended laterally beyond each side of the machine illustrated in FIGURE 1 to any desired length to accommodate any desired number of mold flasks. The supports 20 may be adjusted vertically on standards 11 to a selected fixed position. This adjustment may be made to accommodate mold flasks of different height and provides and adjustable draw of the pattern plate from the mold flask.

An upset frame 23 is adapted to be supported above the mold flask as by means of brackets 24 `carried in an adguides 20 and above the mold flask 21 when the parts are in the position illustrated in FIGURE 1. The vertical adjustment of brackets 24 may be made in accordance with the desires of the operator, with or without adjustment of the clamps for support 20. The upset frame 23 may include pins 25 which rest in recesses 26 in the brackets 24 so that as the mold flask 21 is moved upwardly into engagement with the upset frame 23, the upset frame 23 is simply moved upwardly with the mold ask 21 toward a reaction frame generally designated at 27. The reaction frame may be supported by rollers 28 which ride along parallel rods 29 extending at opposite sides of the machine above the upset frame brackets 24. The rods 29 may be supported by brackets 30 fixed to the standards 11. The reaction frame 27 is adapted to be reciprocated to and from the full line and dotted line positions illustrated in FIGURE 2 through a power means which is not shown in the drawings. Although not shown in the drawings, it should be understood that sand hopper facilities are positioned above the upset frame 23 and above the reaction frame 27 in vertical alignment with the mold ask 21 and table 12 so as to charge a ask positioned beneath the hopper facilities with foundry sand.

The match plate assembly which is generally designated at 19 in FIGURE 1 may include an adapter plate 31 which is illustrated in FIGURE 4. Adapter plate 31 is in the form of a generally rectangular plate with arms 32 extending outwardly at opposite sides thereof. The interior of the plate is cut out in the configuration illustrated by the interior wall 33 dening an opening corresponding to the configuration of a match plate. A match plate having a mold pattern P on opposite sides thereof is then positioned within this opening and pins generally designated at 34 are passed through bores in the walls of the adapter 31 and into matching recesses in the sides of the match plate in order to hold the match plate within the adapter plate 31. The pins 34 may take the form of bolts or screws. Additional pins may be used in the other walls of the adapter plate.

Recesses 36 are formed in the arms 32 to accommodate circular bushings 37 which are formed and dimensioned to receive the pins in a drag mold half. The opposite side of the arm carries a pin 38 which is formed and dimensioned to -be received in the recess of a cope ask, which recess normally receives the pin of the drag ask. A similar pin and bushing assembly is provided in each arm 32. An additional recess is formed in each arm 32 outwardly of the bushing and pin assembly and serves to support another bushing 39 for purposes of receiving upstanding locator pins 39a. The bushings 39 provide apertures which receive locator pins 39a carried in upstanding relation on arms 39h affixed to the sides of the stool 18. The pins 39a serve to properly align the adapter plate 31 with the mold flask and at the same time allow simple and convenient removal of the adapter plate and match plate from the machine. The locator pins 39a may be made of any height desired and serve to properly locate the adapter plate regardless of the spacing of the adapter plate from the pattern stool 18, as long as the pins are engaged with the bushings. The outer ends of each arm 32 are provided with spaced apertures 40 which apertures receive pins 41 which are passed therethrough and through apertures 42 in the legs of a roll-over trunnion. One trunnion 44l which is seen in FIGURES 5 and 6 is a drive trunnion'. The legs 43 of the roll-over trunnion 44 embrace the arms on opposite lsides thereof and when the pins 42 are passed through the aligned apertures in the arm 32 and the legs 43 of the roll-over trunnion, the trunnion is locked to the adapter plate. The drive trunnion illustrated at the right hand side in FIGURE 1 includes a cylindrical bearing portion 45 and a generally rectangular lug portion 46. The other trunnion 47 which appears in FIGURE 8 may be identical to trunnion 45. It includes a cylindrical bearing portion 47a and preferably, the end of this trunnion is made generally cylindrical. The anged portions 48 on opposite sides of the bearing

structure

45 and 47a of each trunnion provide a stop on opposite sides of the bearing surface 45. Trunnion 47 has legs which are identical to the legs 43 of trunnion 44 and which are fixed to the other arm 32 in the same manner.

In some cases, the adapter plate 31 may be eliminated and the match plate itself is then provided with arm structures identical to the arm structures 32 of the adapter plate.

In the inactive position of the match plate assembly, the

trunnions

44 and 47 rest in upwardly

open bearings

49 and 50 positioned on opposite sides of the pattern stool 18 in FIGURE l. These

bearings

49 and 50 are carried by

arms

51 and 52, respectively, which arms are slidably supported on the upstanding standards 11 as by means of

sleeves

53 and 54. The

sleeves

53 and 54 may be connected by a cross arm 55. A power source, such as a hydraulic cylinder 56, has the piston rod thereof connected to the cross arm so as to elevate the

bearings

49 and 50 and the plate assembly supported thereon upwardly to a position illustrated in dotted outline in FIGURE 2. When in this position, the match plate assembly may be inverted by means of a rotary hydraulic actuator 57 which is supported on arm 52, as for example by means of a platform 58. The rotary hydraulic motor 57 may include a lug fitting 59 on the drive shaft thereof, which tting 59 is recessed to match the configuration of the lug 46 of the drive trunnion 44. The lowermost position of the

arms

51 and 52, which is illustrated in FIGURE l, may be xed by stops for the

sleeves

53 and 54, or by the stroke of cylinder 56.

The fitting 59 carried by the shaft of motor or actuator 57 has a generally U-shaped opening 59a in the end face thereof so as to receive the projecting lug 46 of trunnion 44. This provides for quick coupling and uncoupling of fitting 59 to the trunnions for purposes of roll-over, insertion and removal of the match plate. At the match plate stool and table are lifted towards the ask 21, the lug 46 moves out of its matching recess 59a and after the mold has been formed and the match plate 19 de- -scends with the stool 18, the trunnions move into their upwardly

open bearings

49 and 50 while the lug 46 enters its matching recess 59a in the drive element 59.

Table 12 may be secured to the guide piston 16 by means of cap screws or like 77. The portion of the cylinder 17 beneath piston 16 may be closed by a lower cover plate 76 when it is desired to use the lower portion of the guide cylinder for auxiliary lifting or squeezing purposes.

The piston rods of the hydraulic elevators 13 may be secured to the table by means of cap screws or the like 78. A plug, not shown, may be used to close the threaded opening in the top of the table appearing at 79 and leading to pressure chamber 72.

Actuator 57 is a type which rotates its shaft 180 and then stops.

When the motor 56 is actuated to elevate the match plate assembly to the position illustrated in FIGURE 2, the match plate assembly is at a height sucient that it may be inverted by the actuator 57 after which time the motor 56 lowers the match plate assembly to the inactive position illustrated in FIGURE 1. In this position, the adapter and match plate may be positioned some distance ab/e the pattern stool 18 or it may be in contact therew1 IIn the active position of the match plate assembly, the

v motors 1.4 elevate the table 12 and pattern stool so as to contact the match plate assembly 19 and lift it upwardly into engagement with the underside of a mold flask positioned thereabovevand in vertical registry therewith-As the assembly continues its upward movement, the mold ask 21 is lifted above the rollers 22 and brought into engagement with the upset frame 23. The upward movement continues to a sand-filling position where the flask receives a charge of sand and then the reaction member moves forwardly or to the full line position illustrated in FIGURE 2 where excess sand, if any, is struck off by t'he reaction member 27. The hydraulic cylinders or elevators 14 then continue their upward movement so as to squeeze the sand in the mold flask against the reaction head 27. Impact forces, as later described, may then be delivered to the mold, -at the selection of the operator. When the assembly is then lowered, the upset frame moves down to a point where it is received in the brackets 24 therefor, the mold flask 21 moves down to a point where the flanges thereof engage the rollers 22. The match plate assembly is drawn from the flask 21 and moves down to a point where the trunnions are lengaged by and supported in the

bearings

49 and 50 in the supporting

arms

51 and 52.

When the match plate assembly has been returned to the lower position generally illustrated in `FIGURE l, the cylinder 56 may be actuated to again raise the match plate assembly whereupon the actuator 57 may invert the same to enable the alternate formation of cope halves and drag halves of the mold. In some cases, of course, a plurality of cope halves may be made before the match plate is inverted to make a plurality of drag halves.

The guide assembly is formed with means to enable power impact strokes on the lower surface of the table 12 before, during or after the squeeze cycle of the machine. To this end, the guide piston 16 is formed generally as a cylinder, the upper portion of which carries a cylindrical impact member 60 therein. Impact member 60 carries a wear ring 61, which is adapted to impact the lower surface of the table 12. The lower portion of the cylinder 60 carries a depending stem 62 which is slidably received through a bearing 63 and seal `63a in a portion 64 of the guide piston. The space below guide stem 62 is closed by a cover plate -65 so that a pressure chamber 66 may be defined above the cover plate 65 but below the guide stem 62 while a second pressure chamber 67 may be defined below the cover plate 65.

An internal bore of the impact cylinder 60 is in slidable engagement -with a depending, hollow stem 68 of table 12. A first inlet port 69 is in communication with the chamber 66 and is supplied with air under pressure through a passage leading through the guide piston and connected to an external source of pressure (not shown). A second inlet port 70 is formed in the hollow interior of the stem 68 and is adapted to direct air pressure against the upper surface of the stem 62 as by means of the passages 71. The space above stem 62 and beneath the stem l68 defines another pressure chamber 72 which is supplied -with pressure from the inlet port 70. The area of the upper surface of the guide stem 62 exposed to the pressure in chamber 72 is preferably greater than the area at the lower surface of the guide pin 62 which is subjected to the pressure in the chamber `66. The'areas are such, with relation to the weight of impact member 60, that -whenpressure is supplied to both inlet ports 69 and 70, the result will be to force stem or guide pin 62 and cylinder 60 to which it is affixed downwardly.

As an aid in directing pressure against the upper portion of the guide pin or stem 62, passagesy 73 may be formed in the wall of the impact cylinder and receive air from inlet ports 73a in stem 68.

'Exhaust ports 74 are formed through the impact cylinder'and lead from the internal bore therein to the outside. During operation of the machine, air pressure is introduced and `maintained at inlet port 69 in guide piston 16. This pressure results in an upward force acting on the lower end of the guide pin 62. This force causes the assembly` of the guide pin 62, impact cylinder 60 and wear ring 61 to raise until the wear ring 61 contacts the under side of table 12. The assembly is now in the position as shown in FIGURE 3. The assembly of the guide pin, cylinder and wear ring are gui-ded throughout this 'upward movement, and through the subsequent 6 downward movement by the stem 68 of the inner wall of guide piston 16.

The impact section is caused to operate by introducing air pressure through intake port 70. This pressure and air flow through the stem 68 to the ports 73 in impact cylinder 60, and into pressure chamber 72.

Because the force against the top of guide pin 62 is greater than the force against the bottom (pressure chamber 72 area of the pin 62 is greater than pressure chamber 66 area of the pin 62), the assembly of the gui-de pin 62, impact cylinder 60 and ywear ring 61 is caused to move downward. This downward movement is controlled by the location of exhaust ports 74. After a predetermined downward movement, the exhaust ports become open to the pressure chamber 72. The pressure drop resulting in pressure chamber 72 lessens the amount of downward force against guide pin 62. Therefore, the

assembly

62, 60 and `61 are caused to travel rapidly upward until the wear ring 61 against c-ontacts the bottom anvil surface of table 12. This contact imparts a hard impact force to the bottom anvil surface of table 12. During the final upward travel of the assembly, the exhaust ports 74 are again closed, allowing pressure to build up again in chamber 70. Full pressure again causes the assembly to start downward again. This alternate downward and upward motion is continued until the pressure is removed from port 70 in table 12. The assembly may operate to provide for a number of identical impact strokes during each second of time that pressure is supplied to port 70.

The squeeze cylinders 13 will cause the guide piston and its internal parts to move up in guide cylinder 17. The length of guide cylinder 17 and guide piston 16 is such that an extremely accurate movement upward and downward is obtained.

During the squeeze movement provided by cylinders 14, the impact section may be operated. The position of the squeeze has no effect on the impact section. It may be operated before, after or at any time through the complete movement of the squeeze.

An additional squeezing force may be imparted to the table 12 as by admitting air pressure through a port 75 in chamber 67 below cover plate 65. By use of this pressure, the squeezing force applied to the mold flask and reaction member may be v-aried by varying or omitting the pressure supplied through port 75.

By reason of the use of the locator pins 39a for the match plate assembly, the adapter plate and match plate are easily removed from the machine by simple upward vertical movement and a new and different match plate assembly is easily inserted in converse fashion. At the same time, the locator pins 39a allow the adapter plate and match plate to be stopped at any convenient position above the stoll 18. Thus in the at rest position, the adapter plate may be supported solely on the

bearings

49 and 50 and held in proper position by the locator pins 39a. This has the advantageous result of shortening the automatic molding cycle time because of the match plate and adapter plate are required to move fully to the lowermost position with the table 12 before the match plate can be inverted, this requires additional cycling time even though only a fraction of a second may be involved, depending upon the overall speed of the machine. When spaced above the stool, the adapter plate does not have to rise as far to clear the stool as it does when it is supported on the stool. Elevation of the match plate for rollover purposes can start before the stool have moved to the lowermost position. The match plate may be stopped at any selected distance above the stool and held in the at rest position by making the locator pins 39a of the proper length.

Through use of the bushings 37 and pins 38, the adapted plate is accurately located to the mold ask, whether the flask be a cope half or a drag half.

By reason of the squeeze cylinders 14 which are independent of the impact assembly beneath table 12, the

impact strokes imparted by the impact assembly may be operated at any time during the squeeze portion of the cycle or may, in fact, be operated during the filling of the mold flask and before the squeeze portion of the cycle commerces. It should be noted in this regard that the impact forces imparted to the table and hence to the mold flask are highly effective in causing lateral movement of the sand in the mold flask.

Automatic cycling and control equipment, not shown or described herein can be conveniently set up so as to allow an operator to select the time at which impact starts and the duration thereof either before, after, or at some time during the squeezing portion of the cycle.

By using the lower portion of the guide cylinder and piston as an auxiliary source of squeezing pressure, additional squeezing forces may be selectively utilized. This additional squeezing force may be controlled so that the operator can easily select the time at which the additional squeezing force is imparted to the sand in the mold. For example, in some cases the operator may wish to use the additional squeezing force at the start of the squeeze operation. In other cases, he may wish to use the additional squeezing force during a later interval in the squeeze portion of the mold forming cycle.

The particular arrangement shown herein provides extreme versatility of the machine and allows a wide range of selective forces which may be imparted to the mold during the mold forming cycle.

The match plate supporting mechanism and power means for inverting the match plate are entirely separate from the remainder of the machine although as a matter of convenience the

guides

53 and 54 are mounted on the standards for the machine. The actuator 47 for effecting inversion of the match plate assembly may be tied in with the same electrical control circuit as that which is used in controlling the elevating, squeeze, and impact operation so that at or near return of the table to the lowermost position, actuator 57 is automatically operated to invert the match plate after which time table 12 may be caused to automatically rise for the start of another mold forming operation. Thus, the machine may be easily adapted to the alternate or selective formation of cope halves and drag halves.

Whereas we have shown and described an operative form of the invention, it should be understood that this showing and description thereof should be taken in an illustrative or diagrammatic sense only. There are many modifications in and to the invention which will fall within the scope and spirit thereof and which will be apparent to those skilled in the art. The scope of the invention should be limited only by the scope of the hereinafter appended claims.

We claim:

1. Supporting mechanism for elevating and impacting a mold flask including a vertically reciprocable support in a molding machine frame, said support being formed and adapted to engage an assembled mold flask and pattern element for raising and lowering the same, said support having a depending portion telescopically received within a guide sleeve for vertical sliding movement therein, hydraulic means for lifting and lowering said support, and separate fluid pressure means within said portion and operable against an element vertically movable therein to cause reciprocation of said element into and out of contact with the undersurface of said support for selectively imparting impact forces to the undersurface of said support independently of said hydraulic means.

2. The structure of claim 1 wherein said last named means includes two fluid chambers defined within said depending portion and an impact element within said member formed and adapted for reciprocation against the undersurface of said support, said element having different areas exposed to the pressure within each of said chambers, fluid pressure means adapted to supply fluid pressure to both of said chambers whereby upon supply of pressure to both of said areas, said impact member will be moved in one direction and exhaust means for the chamber exposed to the larger one of said areas and formed and adapted to be opened after a predetermined amount of movement in said direction and to be closed in other positions of movement whereby said impact element Will be automatically reciprocated against and away from said support to provide successive impact forces as long as pressure fluid is supplied to the chamber exposed to the larger area.

3. In a molding machine for foundry use, means for supporting a mold flask, a support for engaging and lifting a mold flask and match plate assembly positioned beneath said mold flask, means for elevating said Support to engage and carry an assembled match plate and mold flask into a sand filling position, separate support and elevating means for supporting said match plate in a lowermost inactive position, said first named support being positioned below and out of contact with said match plate in a lowermost, inactive position, said match plate including a support with trunnions on `opposite sides thereof, said separate support and elevating means including a pair of arms having upwardly open bearings adapted to receive said trunnions of said match plate, and power means carried thereby for engaging one of said trunnions and selectively rotating the same so as to invert said match plate, said power means being separate from both of said elevating means.

4. A mechanism for supporting a match plate assembly in a molding machine including a support of the type used to elevate a pattern plate toward a superposed mold flask, said support having upstanding pins at opposite sides thereof, a match plate assembly in overlying relation to said support and having apertures in vertical alignment with said pins, said pins being extended through said apertures, said match plate assembly having trunnions received in upwardly open bearings carried by said machine, and power means for elevating said match plate assembly from said support and pins and for effecting inversion thereof, said power means including a driving actuator with a drive lug engaged with one of said trunnions, said one trunnion and drive lug having interfitting projection and recess portions which are formed to allow disengagement thereof upon relative movement of said lug and trunnion normal to the axis lof rotation of said lug and trunn1on.

5. The structure of claim 4 wherein said match plate assembly includes an adapter plate and a match plate held within and supported by said adapter plate, said adapter plate having laterally extended arms, said trunnions being detachably coupled to said arms. K

A6. A molding machine for foundry use and of the type wherein a supporting table is used to elevate a pattern plate into engagement with the undersurface of a mold flask so as to lift the pattern plate and mold flask to a sand filling position, the improvement comprising a guiding piston with a bore therein received within a cylindrical supporting member, a pattern elevating table supported on said piston, an impact cylinder positioned in an upper portion of a bore in said guide piston, means supporting said impact cylinder for axial movement in said piston, said impact cylinder including a depending element at the lower portion thereof, meansl defining separate upper and lower pressure chambers exposed to upper and lower pressure areas, respectively of 'said element, the area of said element exposed to the upper chamber being greater than the area of the element exposed to the lower pressure chamber, exhaust means for said upper chamber, means for closing said exhaust means when said impact cylinder is located at positions adjacent the undersurface of said table, and means for opening said exhaust means when said impact cylinder is below said positions whereby the force developed in said lower chamber causes said impact cylinder to move upwardly and impact against said table and the force developed in said upper chamber after impact against said table causes said impact cylinder to move downwardly until said exhaust means is opened for a subsequent upward movement of said impact cylinder, and sepaarte hydraulic cylinders for elevating said table and effecting a squeezing of sand in a mold ask.

7. A molding machine for foundry use and of the type wherein a supporting table is used to elevate a pattern plate into engagement with the undersurface of a mold lask so as to lift the pattern plate and mold ask to a sand lling position, the improvement comprising a guiding piston with a bore therein received within a cylindrical supporting member, a pattern elevating table supported on said piston, an impact cylinder positioned in an upper portion of the bore of said piston, said table having a depending guide stem, said impact cylinder having a hollow bore and being slidably mounted on said guide stern, said impact cylinder including a depending element at the lower portion thereof and spanning the bore in said impact cylinder, means defining upper and lower pressure chambers exposed to upper and lower pressure areas of said element, the area of said element exposed to the upper chamber being such, with relation to the weight of said impact cylinder, that the resultant forces cause said impact cylinder to move downwardly when both areas are subjected to the same fluid pressure, and an exhaust port formed through said impact cylinder and opening into the chamber above said element when said impact cylinder is located at positions below a position substantially near the undersurface of said table, and means for closing said exhaust port when said impact cylinder is between said last named position and a position in engagement with the undersurface of said table whereby the force developed in said lower chamber causes said impact cylinder to move upwardly and impact against said table, and separate hydraulic means for elevating said table.

`8. The structure of claim 7 wherein said impact cylinder includes a wear ring on the upper surface thereof.

9. The structure of claim 7 wherein the space below said guide piston is a pressure chamber to apply elevating forces to said piston.

10. Foundry apparatus for supporting and inverting mold apparatus of the type having spaced and generally aligned supporting trunnions and spaced locater apertures and wherein one of said trunnions has a noncircular cross-sectional portion including a support having spaced and aligned upwardly open bearings for receiving coaxial trunnions of mold apparatus, power means for elevating and lowering said support, means supporting spaced, upstanding locater pins at a position generally horizontally aligned with said bearings when said rst named support is ina lower position, and a rotatable motor carried by said lirst named support including a rotatable, driven, connecting element generally aligned with one of said bearings, said connecting element having a cross-sectional portion matching said trunnion portion and being formed and adapted for a releasable engagement with said one trunnion portion, said connecting element portion being positioned to receive said trunnion portion in an intertting relation when said trunnions are received in said bearings.

11. The structure of claim 10 wherein said connecting element is in the form of a slotted lug.

References Cited UNITED STATES PATENTS Oyster 164-409 X I. SPENCER OVERHOLSER, Primary Examiner I. I. BROWN, Assistant Examiner U.S. C1. X.R. 164-207