EP0137586A2

EP0137586A2 - Automated mold making system

Info

Publication number: EP0137586A2
Application number: EP84304452A
Authority: EP
Inventors: William A. Hunter
Original assignee: Hunter Automated Machinery Corp
Current assignee: Hunter Automated Machinery Corp
Priority date: 1983-08-29
Filing date: 1984-06-29
Publication date: 1985-04-17
Also published as: JPS6068136A; EP0137586A3

Abstract

A system for making foundry molds comprises the combination of a plurality of mold flasks (11) mounted on indexing means (12) for indexing the flasks (11) through a succession of different stations (A1-A3,B1-B3), and a mold-forming station (A1.B1) associated with the indexing means (12) for pre-filling one of said mold flasks (11) with sand, squeezing the sand within the flask (11) to form a mold with a pattern engaging at least one side thereof, and then drawing the pattern away from the mold. The forming station (A1,B1) includes a sand magazine (20) mounted for movement between a sand loader (10) and the forming station (A1,B1) so that said magazine (20) can be loaded with sand while a mold Is being formed, pre-filling means (50,51,52,53,54,55) for supplying pressurised air to the top of the magazine (20) within the forming station (A1,B1) to quickly discharge sand from the magazine (20) into a mold flask (11) positioned at the forming station (A1,B1), and a squeeze head (22) for forming the top surface of the mold during the squeezing operation at the forming station (A1,B1), said squeeze head (22) being movable in and out of the forming station (A1,B1) to permit the sand magazine (20) to enter said station (A1,B1). A mold discharge station (A3,B3) associated with said indexing means (12) received flasks (11) containing formed molds and removed the molds from the flasks (11) onto a mold platform (14a,14b) or a mold stack 13a, 13b) on the platform (14a,14b).

Description

The present invention relates to automated systems for forming green sand molds for use in foundries. Prior art systems for this purpose are described in, for example, Hunter U.S. Patent No. 3,406,738 for "Automatic Matchplate Molding Machine"; Hunter U.S. Patent No. 3,506,058 for "Method of Matchplate Moulding"; Hunter U.S. Patent No. 3,520,348 for "Fill Carriages for Automatic Matchplate Moulding Machines; and Hunter U.S. Patent No. 4,156,450 for "Foundry Machine and Method and Foundry Mold Made Thereby".
It is a primary object of the present invention to provide an automated mold-making system which is capable of operating at extremely high production rates, e.g., producing over 1,000 molds per hour.
It is another important object of this invention to provide such an automated mold-making system which produces molds with a high degree of reliability and accuracy, so that the mold reject rate is extremely low. In this connection, a related object of the invention is to provide such a system which virtually eliminates mold breakage at the mold ejection station, while at the same time achieving precise mold closing when the ejcted mold is stacked on top of another mold.
A further object of this invention is to provide an improved automated mold-making system which pre-fills the mold flask rapidly but at a low pressure, thereby extending the pattern life and virtually eliminating pattern breakage or deflection while at the same time providing a high rate of productivity.
Yet another object of this invention is to provide such an improved automated mold-making system which is extremely versatile in that it can make cope and/or drag molds, it can make mold stacks with cavities either above or below the parting, it can make molds with half patterns, and it can stack cope and drag molds.
A still further object of the invention is to provide such an improved automated mold-making system which has a particularly efficient indexing drive mechanism.
Other objects and advantages of the invention will be apparent from the following detailed description and the accompanying drawings.
In accordance with the present invention, there is provided a system for making foundry molds comprising the combination of a plurality of mold flasks mounted on indexing means for indexing the flask through a succession of different stations, a mold-forming station associated with saidindexing means for prefilling one of said mold flasks with sand, squeezing the sand within the flask to form a mold with a pattern engaging at least one side thereof, and then drawing the pattern away from the mold, said forming station including a sand magazine mounted for movement between a sand loader and said forming station so that said magazine can be loaded with sand while a mold is being formed at said forming station, pre-filling means for supplying pressurized air to the top of said magazine within said forming station to quickly discharge sand from said magazine into a mold flask positioned at said forming station, and a squeeze head for forming the top surface of the mold during the squeezing operation at said forming station, said squeeze head being movable in and out of said forming station to permit said sand magazine to enter said station, and a mold discharge station associated with said indexing means for receiving flasks containing formed molds and removing said molds from said flasks onto a mold platform or a mold stack on said platform.
An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings in which:

Fig. 1 is a partial perspective view of an automated mold-making system embodying the present invention;
Fig. 2 is a top plan view of the system illustrated in Fig. 1;
Fig. 3 is a side elevation taken generally along line 3-3 in _Fig. 2;
_Fig. 4 is an end elevation taken generally along the line 4-4 in Fig. 2;
Fig. 5 is an enlarged top plan view of the indexing drive mechanism in the system of Figs. 1-4;
Fig. 6 is a fragmentary view of the same mechanism shown in Fig. 5 but in a different operating position;
Fig. 7 is an enlarged vertical section taken generally along the line 7-7 in Fig. 2 and illustrating the mold-forming station of the system during a first stage of a mold-forming operation;
Fig. 8 is a horizontal section taken generally along the line 8-8 in Fig. 7;
Fig. 9 is a portion of the same vertical section shown in Fig. 7 in a later stage of the mold-forming operation;
Fig. 10 is a portion of the same vertical section shown in Fig. 7 during a still later stage of the mold-forming operation;
Fig. 11 is a portion of the same vertical section shown in Fig. 7 showing the completion of the mold-forming operation;
Fig. 12 is a portion of the same vertical section shown in Fig. 7 with the completed mold ready for indexing to an inspection station; and
Fig. 13 is a vertical section taken through the mold-ejection station A3 in the system of Figs. 1-4.

While the invention will be described in connection with certain preferred embodiments, it will be understood that it is not intended to limit the invention to those particular embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalent arrangements as may be included within the spirit and scope of the invention as defined by the appended claims.
Turning now to the drawings and referring first to Fig. 1, the illustrative machine is a "dual" machine in that stations Al, A2 and A3 are identical to stations Bl, B2 and B3. In other words, each half of the machine is the mirror image of the other half. As will be discussed in more detail below, this machine represents only one particular embodiment of the invention, and numerous variations thereof are contemplated. Since stations Al-A3 are identical to stations B1-B3 in the illustrative machine of Fig. 1-4, only the one set of stations A1-A3 will be described in detail herein; it will be understood that the other three stationaBl-B3 are identical in both structure and operation.
Foundry sand enters the machine of Fig. 1 through a sand-loading hopper 10 from any conventional feeding device such as a conveyor lOa (Fig. 3). As is well known in the foundry art, the sand is normally premixed with a certain amount of bentonite or other binder to bind the sand particles together during the formation of a mold therefrom. The molds are formed within six mold flasks 11 which are carried by an indexing turntable 12. More specifically, molds are formed at stationsAl and Bl, inspected at stations A2 and B2, and discharged at stations A3 and B3. In the particular embodiment illustrated, the molds are discharged at stations A3 and B3 onto mold stacks 13a and 13b which are supported by platforms 14a and 14b. When a mold stack 13a or 13b has been completed, a hydraulic or pneumatic cylinder 15a or 15b advances an arcuate pusher plate 16a or 16b which transfers the completed mold stack onto a suitable conveyor 17a or 17b represented by the brocken lines in Fig. 1.
Returning to the sand-loading hopper 10, the sand which enters this sleeveitepetitively fills a sand magazine 20 which is carried by a kidney-shaped shuttle plate 21. This shuttle plate 21 also carries a squeeze head 22, and the plate 21 is pivotally mounted at 23 so that it can be pivoted back and forth to alternately bring the sand magazine 20 and the squeeze head 22 into register with the mold-forming station Al. The sand magazine 20 is automatically filled with sand, by gravity feed from the hopper 10, each time the shuttle plate 21 is pivoted to bring the magazine 20 into register with the loading hopper 10. When the shuttle plate 21 is pivoted to transfer the sand magazine 20 to the mold-forming station Al, a solid portion of the plate 21 wipes across the bottom of the hopper 10, serving as a gate to close the bottom of the hopper. Pivotal movement of the shuttle plate 21 about the axis 23 is effected by a hydraulic or pneumatic cylinder 24 (Fig. 2).
At the mold-forming station Al, one of the mold flasks 11 carried by the turntable 12 is aligned with the sand magazine 20 on the shuttle plate 21, and sand is discharged from the magazine 20 into the flask. The mold is then formed by a squeeze and draw operation, as will be described in more detail below.
From the forming station Al, the flask containing the formed mold is indexed to an inspection station A2 where it dwells for manual inspection during the interval required to form a mold in the next flask. During the same dwell interval, the mold in the flask at station A3 is ejected from the flask 11 at that station. The ejected mold is controllably and precisely deposited onto a mold stack on the platform 14a or, in the case of the first mold or a single mold-forming operation, directly onto the platform 14a.
To drive the turntable 12, a gear motor 25 is connected to the turntable spindle 26 via a Geneva drive mechanism 27 which is shown most clearly in Figs. 5 and 6. More specifically, the motor 25 rotates a Geneva-type drive arm 27a having follower rollers 27b and 27c mounted on opposite ends thereof. As the drive arm 27a is rotated with the motor output shaft 25a, the rollers 27b and 27c pass in and out of radial slots formed by six pairs of index tracks 27d, 27e affixed to the top surface of a rotar 27f to produce the desired intermittent or indexing movement of the rotor 27f. The rotor 27f, in turn, is secured to the upper end of the turntable spindle 26 so that indexing movement of the rotor 27f is translated into indexing movement of the turntable 12.
Each half revolution of the drive arm 27a indexes the rotor 27f and the turntable 12 by one sixth of a revolution, thereby causing each flask 11 carried by the turntable to be indexed progressively through the six work stations Al_-A3 and Bl-B3. More specifically, during alternate half . revolutions of the drive arm 27a the first follower roller 27b rides along the cam surface formed by one of the index tracks 27a to cam the rotor 27f through one sixth of a revolution; similarly, during the intervening half revolutions of the drive arm 27a, the second follower roller 27c advances the rotor 27f by one sixth of a revolution via the same type of camming action.
In order to provide a detent position for the drive arm 27a and the rotor 27f in each half revolution of the drive arm, the index tracks 27d and 27e are positioned and shaped so that both rollers 27b and 27c are simultaneously in engagement with the index tracks 27d, 27e at only one angular position of the drive arm in each half revolution. A brake associated with the drive motor 25 stops the drive arm in this particular angular position at the end of each half revolution. As can be seen most clearly in Fig. 6, the radius of curvature of the outer end of each index rail 27d, 27e is slightly smaller than the radius of the circular path followed by the adjacent surfaces of the rollers 27b, 27c. Consequently, the only time both rollers 27b 27c are in contact with the rails 27e, 27d is when the drive arm 27a is in its "detent" position shown in Fig. 5. Each time the drive arm 27a begins to move from this detent position, the exiting roller (i.e., roller 27c in Figs. 5 and 6) immediately leaves the surface of the index rail 27d, and that roller never re-engages either rail 27d or 27e until the drive arm 27a has completed a half revolution and thereby returned the rollers 27d, 27e to the detent position.
Each indexing movement of the turntable 12 brings an empty mold flask 11 to the forming station Al, in axial alignment with a hydraulic cylinder 30 which carries a platen 31 and a pattern bolster 32 on the upper end of its piston rod 33. While the turntable 12 is being indexed, the shuttle plate 21 is simultaneously pivoted to bring a full sand magazine 20 into register with the forming station Al, directly over the empty mold flask 11, as illustrated in Fig. 7. The sand magazine 20 is completely filled with sand (including a conventional binder pre-mixed with the sand) and contains more than enough sand to make the desired mold. As can be seen in Fig. 7, the manifold holes at the bottom of the magazine 20 are open, but the natural "Packing" of the sand prevents it from flowing out of the magazine until air is applied to the sand at the top of the carriage.
Each time a fresh empty flask 11 enters the forming station Al, the hydraulic cylinder 30 is actuated to elevate a pattern 34 carried by the bolster 32 up into the lower region of the empty mold flask,as illustrated in broken lines in Fig. 7. This closes the bottom of the empty flask, and a gasket 35 is provided around the periphery of the pattern 34 to form a seal betwen the inner wall of the flask 11 and the outer edge of the pattern 34. As the pattern 34 is raised by the hydraulic cylinder 30, a sprue pin 35 is also extended upwardly through the centre of the pattern 34, by an internal hydraulic or pneumatic cylinder 37; this sprue pin 36 defines the size and shape of the sprue opening to be formed in the centre of the mold, as will be apparent from the ensuing description.
After the gasket 35 first engages the bevel at the lower end of the inside wall of the mold flask 11, further upward movement of the cylinder 30 raises the empty flask 11 off the turntable 12 and up into engagement with the underside of a sand manifold 40 on the bottom of the sand magazine 20, as illustrated in Fig. 9. A land lla on the top of the mold flask 11 engages a gasket 41 on the underside of the sand manifold plate to provide a good seal between the top. of the flask 11 and the bottom of the manifold 40. During upward movement of the mold flask 11, the extended sprue pin 36 is also brought into seating engagement with the conical surface of a pin seat 42 extending downwardly from the centre of the manifold 40.
After the flask 11 has been raised into engagement with the sand manifold plate 40, the cylinder 30 continues to elevate the pattern 34 to a desired vertical position within the flask 11 to define a prefill cavity of the desired volume. That is, when the pattern 34, the mold flask 11, and the sprue pin 36 are in their final raised positions, as illustrated in Fig. 9, they define an annular cavity which is predetermined to have the proper size and shape for receiving the proper amount of "prefill" sand for forming the desired mold.
The prefill is effected by supplying pressurised air to the top of the sand contained in the sand magazine 20, thereby causing the sand to flow downwardly through the sand manifold 40 into the prefill cavity within the flask 11. This pressurised air is supplied from a compressed air tank 50 through a control valve 51 and multiple ports 52 in a head plate 53. For the purpose of distributing the pressurised air uniformly over theexposed top surface of the sand in the magazine 20, a perforated air manifold ring 54 is mounted within a annular air distribution recess 55 formed in the underside of the head plate 53 and communi cating with the air ports 52. The pressurised air thus flows downwardly through the ports 52 into the distribution recess 55, and then on through the numerous apertures in the air manifold ring 54. From the manifold ring 54, the pressurised air flows downwardly through the sand magazine 20 and the manifold 40 at the lower end thereof, and then exits through a plurality of air vent holes 44 formed in the bottom of the manifold 40; the vent holes 44 are preferably covered with fine screens (not shown) to block the entry of sand into those holes. This downward air flow through the sand magazine carries the sand downwardly through the manifold 40 into the flask 11, thereby filling the prefill cavity with sand.
As can be seen most clearly in Figs. 8 and 9, the sand manifold 40 is a relatively thick plate provided with numerous funnel-shaped holes 43 which are spaced relatively uniformly over substantially the entire area circumscribed by the side walls of the sand magazine 20. These funnel-shaped holes 43 permit the sand to flow freely from the magazine 20 into the prefill cavity when the pressurised air is supplied to the top of the sand magazine, while at the same time promoting packing of the sand in the sand manifold holes 43 after the air flow has been cut off. As mentioned previously, this natural "packing" tendency of the foundry sand is sufficient to hold the sand within the manifold 40 so that there is no needto close the open ends of the holes 43 along the bottom surface of the manifold 40 when sand is not being expelled therefrom.
In order to form a seal between the head plate 53 and the top surface of the shuttle plate 21 while the pressurised air is being supplied to the head space of the sand magazine 20, a gasket 56 extends around the periphery of the head plate 53. This gasket 56 is supplied with compressed air through a circumferential tube 57 so that the gasket 56 can be extended downwardly, by air pressure, into sealing engagement with the top surface of the shuttle plate 21.
After the prefill cavity defined by the mold flask 11, the pattern 34, the sprue pin 36 and the lower surface of the sand manifold 40 has been filled with sand, the shuttle plate 21 is pivoted to return the sand magazine 20 to the sand-loading hopper 10. To clear the way for pivoting movement of the shuttle plate 21, the hydraulic cylinder 30 is lowered slightly so that the sand-filled flask 11 is returned nearly to its seated position on the turntable 12. This intermediate position of the flask 11 and the pattern 34 carried by the hydraulic cylinder 30 is illustrated in Fig. 10.
The pivoting movement of the shuttle plate 21 also brings the squeeze head 22, which is also carried by the shuttle plate 21, into register with the forming station Al as illustrated in Fig. 10. This squeeze head 22 forms a rigid structure against which the prefill sand can be squeezed by further upward movement of the hydraulic cylinder 30 carrying the pattern 34. The bottom surface of the squeeze head 22 also determines the shape of the top surface of the mold. In most cases, this top surface of the mold will be perfectly flat, but if desired, the lower surface of the squeeze head 22 can be patterned to provide cavities of a desired configuration in the top surface of the mold. The bottom of the squeeze head 22 also carries a conical sprue pin seat 22a identical to the seat 42 provided on the lower surface of the sand manifold 40.
As soon as the squeeze head 22 has been brought into register with the forming station Al, the hydraulic cylinder 30 is actuated to once again raise the mold flask 11. This time the flask is raised until the land lla on the top surface thereof engages the bottom of the squeeze head 22, as illusrated in Fig. 11. Upward movement of the hydraulic cylinder 30 is then continued to squeeze the sand in the flask 11 against the squeeze head 22, as is also illustrated in Fig. 11. As is well known in the foundry industry, this squeezing of the prefill sand causes it to compact into a coherent structure with sharply defined mold cavities. This is the final mold ready for use in the casting of molten metal. The squeeze head 22 remains stationary during its dwell at the forming station Al, with the final thickness of the mold being determined by the volume of sand in the prefill cavity and the hardness of the mold being determined by the pressure setting for the hydraulic cylinder 30.
Following the squeezing operation, the sprue pin 36 is retracted from the mold, and the hydraulic cylinder 30 is retracted to return the mold flask 11 to its seated position on the turntable 12. At this point, the mold is held tightly within the flask 11 by friction. Continued downward movement of the hydraulic cylinder 30 and the pattern 34 draws the pattern 34 cleanly away from the mold, as illustrated in Fig. 12. As the pattern 34 is drawn away from the mold, the flask 11 is held in place on the turntable 12 by three or more draw pins 12a affixed to the turntable and spaced at equal intervals around the circumference of the flask; the tops of these draw pins 12a register with complementary recesses in the underside of the flanged portion of the flask 11. Downward movement of the pattern 34 is continued to a retracted position that provides a clear path for indexing movement of the turntable 12 and the mold flask 11 carried thereon.
This completes the mold-forming operation, and the system is ready for the next indexing movement of the turntable 12. The next indexing movement advances the flask containing the newly formed mold from the forming station Al to the inspection station A2, at the same time. bringing a fresh empty flask 11 into the forming station Al and advancing the previously formed mold from the inspection station A2 to the mold discharge station A3.
At the mold-ejection station A3, the mold flask 11 containing the completed mold is brought into register with an ejecting head 60. This ejecting head 60 is mounted on the end of a piston rod 61 of a hydraulic cylinder 62, so that the head 60 can be pressed downwardly against the top of the mold within the flask 11. As the ejecting head 60 is brought into engagement with the top surface of the finished mold, a vacuum is applied to a duct 63 communicating with an annular vacuum chamber 64 formed in the lower surface of the ejecting head 60. The purpose of this vacuum is to hold the mold firmly against the underside of the ejecting head 60 as the head 60 continues to advance downwarly into the flask 11, thereby breaking the mold loose from the walls of the flask 11. The mold continues to be held against the .underside of the ejecting head 60 by vacuum as downward movement of the head continues.
In order to deposit the finished mold on the current mold stack 13a (or on the mold platform 14a in the case of the first mold in a given stack), the hydraulic cylinder 62 continues to lower the ejecting head 60 al1 the way down through the flask 11. To deposit the descending mold gently in the mold stack, an optical fiber sensor 65 senses the bottom of the descending mold when it reaches a predetermined position above the top of the mold stack, and the resulting signal from the sensor 65 is used to decelerate the downward movement of the cylinder 62. This causes the descending mold to make a "soft landing" on the stationary mold stack. The downward movement of the cylinder 62 is terminated, and upward retracting movement is initiated, a predetermined time after the sensor 65 first senses the descending mold, and at the same time the vacuum is turned off by closing a valve (not shown) in the duct 63. The retracting movement of the cylinder 62 withdraws the ejecting head 60 upwardly through the flask 11 and returns the head to its original starting position above the top of the mold flask so that the path of the indexing table 12 and the mold flask 11 carried thereon is clear for the next indexing step.
In addition to controlling the deceleration of the descending mold, the sensor 65 controls the indexing movement of a lower cylinder 70 (Fig. 3) which controls the elevation of the mold platform 14a. Each time a new mold is added to the stack on the platform 14a, the cylinder 70 lowers the platform 14a by one mold thickness. This indexing movement of the cylinder 70 is initiated concurrently with initiation of upward movement of the cylinder 62, and continues until the sensor 65 detects the absence of a mold in the space adjacent the sensor. The downward movement of the cylinder 70 is then terminated so that the top of the mold stack on the platform 14a is always at the same elevation.
While the invention has been described above with specific reference to one particular embodiment, it will be appreciated that there are modifications that can be made in the operating stations traversed by the indexing turntable for different foundry applications. For example, stations A3, Bl and B2 can all-be used simply as inspection and core set stations, with the system producing only a single stack of finished molds, at station B3. Another modification is to convert station A2 to a conventional mold roll-over station so that alternate mold flasks can be rolled over to form symmetrical cope and drag molds using the same pattern.; stations A3 and B2 are then used as inspection and core set stations for the cope molds, and station Bl is used as an inspection and core set station for the drag molds. The mold stack produced at station B3 then comprises a stack of alternating symmetrical cope and drag molds with α-common pouring sprue.
Still another possible modification of the illustrated system involves conversion of station B2 to a conventional roll-over station, and conversion of station B3 to an inspection and core set station. With these modifications, drag molds can be formed at station Bl, rolled over at station B2, and inspected at station B3; cores can also be set in the drag'molds at station B3. At station Al the cope molds are formed, with station A2 again being used for inspection and, if desired, core set. A finished stack of alternating cope and drag molds, formed with different patterns if desired, is then produced at station Al.
Yet another modification involves conversion of both stations A2 and B2 to conventional roll-over stations. The dwell time of the index table can be adjusted to also permit cores to be set in the roll-over stations A2 and B2. If only alternate molds are rolled over at stations A2 and B2, the mold stack produced at station B3 will have symmetrical cope and drag molds; the same will be true of the mold stack produced at station A3, although the pattern of the molds in the stack produced at station A3 may be different from the pattern of the molds in the stack produced at station B3.
As can be seen from the foregoing detailed description, this invention provides an automated mold-making system which is capable of operating at extremely high production rates, e.g., produced in excess of 1,000 molds per hour. This system produces molds with a high degree of reliability and accuracy, so that the mold reject rate is extremely low. Mold breakage at the mold ejection station is virtually eliminated, while achieving precise mold closing when the ejected molds are stacked on top of each other. The system also pre-fills the mold flask rapidly but at a low pressure, thereby extending the pattern life and virtually eliminating pattern breakage or deflection while at the same time providing a high rate of productivity. The system is extremely versatile in that it can make cope and/or drag molds; it can make mold stacks with cavities either above or below the parting; it can make molds with half-patterns; and it can stack cope and drag molds.

Claims

1. A system for making foundry molds comprising the combination of

a plurality of mold flasks (11) mounted on indexing means (12) for indexing the flasks (11) through a seccession of different stations (Al-A3, B1-B3),

a mold-forming station (Al,Bl) associated with said indexing means (12) for prefilling one of said mold flasks (11) with sand, squeezing the sand within the flask (11) to form a mold with a pattern engaging at least one side thereof, and then drawing the pattern away from the mold, said forming station (A1,B1) including

a sand magazine (20) mounted for movement between a sand loader (10) and said forming station (A1,B1) so that said magazine (20) can be loaded with sand while a mold is being formed at said forming station (A1,B1),

prefilling means (50,51,52,53,54,55) for supplying pressurised air to the top of said magazine (20) within said forming station (A1,B1) to quickly discharge sand from said magazine (20) into a mold flask (11) positioned at said forming station, and

a squeeze head (22) for forming the top surface of the mold during the squeezing operation at said forming station (A1,B1), said squeeze head (22) being movable in and out of said forming station (Al,Bl) to permit said sand magazine (20) to enter said station (A1,B1). and

a mold discharge station (A3,B3) associated with said indexing means (12) for receiving flasks (11) containing formed molds and removing said molds from said flasks (11) onto a mold platform (14a,14b) or a mold stack (13a,13b) on said platform (14a,14b).

2. A system as set forth in claim 1 wherein said sand magazine (20) includes a sand manifold (40) for distributing sand uniformly throughout the flask (11) when sand is discharged from the magazine (20) into the flask (11).

3. A system as set forth in claim 2 wherein said sand manifold (40) comprises a plate with a multiplicity of funnel-shaped holes (43) extending downwardly therethrough and uniformly spaced over an area corresponding to the open area of the flask (11).

4. A system as set forth in claim 1 wherein said pre- filling means (50,51,52,53,54,55) comprises a source of pressurised air (50), an air manifold (54) for distributing the pressurised air uniformly over the top surface of the. sand in the sand magazine (20) when the magazine (20) is positioned over a flask (11) within said forming station (Al.Bl), and air vent means (52) at the bottom of said sand manifold (54) for exhausting the air after it has carried the sand through the same manifold (54).

5. A system as set forth in claim 1 wherein said pre- filling means (50,51,52,53,54,55) is a stationary part of said forming station (A1,B1) and is located directly above the position of said sand magazine (20) and said squeeze head (22) in said forming station (A1,B1).

6. A system as set forth in claim 1 wherein said sand magazine (20) and said squeeze head (22) are mounted on a common frame (21) which is pivoted to move said magazine (20) between.said sand loader (10) and said forming station (Al,Bl) while simultaneously moving said squeeze head (22) in and out of said forming station (A1,B1.

7. A system as set forth in claim 1 wherein said discharge station (A3,B3) includes vacuum means (63,64) for holding each mold against the removal means (60) at said mold discharge station (A3,B3) while the mold is being moved from its flask (11) to said platform (14a, 14b) or mold stack 13a, 13b.

8. A system as set forth in claim 1 wherein said indexing means (12) comprises a turntable (12) having a plurality of said flasks (11) mounted thereon.

9. A system as set forth in claim 1 which includes a mold inspection station (A2,A3) loacted between said forming (A1,B1) and discharge stations (A3,B3) to permit each mold to be inspected between the forming thereof at said forming station (Al,Bl) and the removal of the mold from its flask (11) at said discharge station (A3,B3).

10. A system as set forth in claim I which includes a mold rollover station between said forming (A1,B1,) and discharge stations (A3,B3), said rollover station including means for rolling over selected flasks (11) after molds have been formed therein at said forming station (Al,Bl)l whereby any given mold can be removed as either a cope or drag mold at said discharge station (A3).

11. A system as set forth in claim 1 which includes two forming stations Al,Bl) and a mold rollover station (A2,B2) therebetween, said rollover station including means for rolling over at least selected flasks (11) after the forming of a drag mold therein at a first forming station (Al,Bl) whereby a cope mold can be formed in the same flask (11) at the second forming station (Al,Bl).

12. A system as set forth in claim 1 which includes sensing means (65J for detecting when each mold removed from a flask (11) at said mold discharge station (A3,B3) is within a predetermined distance from said platform (14a,14b) or a mold stack(13a,13b) on said platform (14a,14b) so that the rate of descent of the mold being removed can be decelerated before it contacts the mold platform (14a,14b) or mold stack (13a,13b) on the platform (14a,14b).

13. A system as set forth in claim 12 which includes means (62) for raising and lowering said mold platform (14a, 14b) at said mold discharge station (A3,B3) , and said sensing means (65) detects when the top surface of said platform (14a,14b) or a mold stack (13a,13b) on said platform (14a,14b) is at a predetermined elevation so that the vertical movement of said platform (14a,14b) can be controlled to maintain said top surface at a selected elevation.

14. A system as set forth in claim 1 which includes a Geneva drive mechanism (27) for indexing said turntable (12); said drive mechanism comprising

a rotatable drive arm (27a) having a pair of follower rollers (27b,27c) mounted pn opposite ends thereof,

a drive motor (25) for rotating said drive arm (27a), and

a driven rotor (27f) coupled to said turntable (12) and having multiple cam surfaces (27d,27e) symmetrically spaced the centre of said rotor (27f) for co-operating engagement with said follower rollers (27b,27c), whereby each half revolution of said drive arm (27a) indexes said rotor (27f) through a predetermined angular displacement by the camming action of said rollers (27b,27c) on said cam surfaces (27d,27c),

said cam surfaces (27d,27c) being positioned and shaped so that both of said rollers (27b,27c) engage said cam surfaces (27d,27c) at only one angular position of said drive arm (27a) in each half revolution, whereby that one angular position serves as the detent position for rotor (27f) in each half revolution of said arm (27a).

15. A system as set forth in claim 14 wherein the radius of curvature of the outer ends of said cam surfaces (27d,27c) is smaller than the radius of the circular path followed by the adjacent surfaces of said follower rollers (27b,27c) so that the roller (27b,27c) that is exiting said rotor (27f) at the beginning of each half revolution of said drive arm (27a) is immediately disengaged from said cam surfaces (27d,27c)

₁₆. A system for making foundry molds comprising the combination of

indexing means (12) carrying a plurality of mold flasks (ll) for indexing movement through a succession of different stations (AI-A3,BI-B3),

a sand-loading station (10) adjacent said indexing means (12),

a mold-forming station (Al,Bl) associated with said indexing means (12) for pre-filling one of said mold flasks (11) with sand, squeezing the sand within the flask (11) to form a mold with a pattern engaging at least one side thereof, and then drawing the pattern away from the mold, and

a shuttle plate (21) mounted for movement through said forming station (Al,Bl), said shuttle plate (21) carrying (1) a sand magazine (20) for conveying a predetermined volume of sand from said sand-loading station (10) to said mold-forming station (Al,Bl), and (2) a squeeze head (22) for forming the top surface of the mold during the squeezing operation at said forming station (A1,B1).

17. A system as set forth in claim 16 which includes a source of pressurised air (50) adjacent said mold-forming station (Al,BI) for supplying pressurised air to the top of said sand magazine (20) to transfer sand from said magazine (20) to a flask positioned at said mold-forming station (Al,Bl).

18. A system as set forth in claim 16 wherein said shuttle plate (21) includes a solid portion which co-operates with said sand-loading station (10) to serve as a gate for opening and closing said sand-loading station (10) as said sand magazine (20) is moved back and forth between said sand-loading station (10) and said mold-forming station (Al, Bl).