GB2130511A - Method and apparatus for making foundry molds - Google Patents

Abstract

The apparatus includes a base 10 with a flask receiving station. A vibrator means 30, 34 is employed to vibrate the foundry flask 20 disposed in the station in at least a vertical direction and there are provided a plurality of movable compacting heads 54 of substantial mass. The heads are mounted with vertical lost motion to a cross member 44 for movement into and out of the station by means of fluid cylinders 40, and also for movement permitted by the lost motion relative to each other in a generally vertical direction as the flask 20 is vibrated. The apparatus is free of any devices for applying a downward force to the compacting heads such that the sole downward force applied thereto is that supplied by gravity. <IMAGE>

Description

SPECIFICATION Method and apparatus for making foundry molds Field of the Invention This invention relates to an apparatus for making foundry molds by compacting foundry sand about a pattern. The invention additionally relates to a method of forming such molds through the compaction of foundry sand about a pattern.

Background of the Invention Over the years, many different methods and apparatus have been adopted in the age old process of forming metal in a desired shape by melting and casting the metal in a mold. In a usual case, the mold is formed using patterns about which sand and a binder are packed. The packing may be performed in a variety of ways and various techniques have evolved.

For example, in one currently available foundry mold forming apparatus known as a Herman Moldmaster, provision is made for lining up a flask containing foundry sand and binder as well as a pattern with a platen having a plurality of downwardly projecting squeeze or compacting heads which are advanced under the influence of fluid under pressure into the flask for pressing the sand and binder around the pattern. After the desired compaction is achieved, the compacting heads are withdrawn and the flask moved to the next stage in the foundry process. Although such a machine is very efficient and generally acceptable, there are certain patterns that have shapes and/or configurations that are not fully susceptible to complete ramming due to the squeeze or compressing effect with the result that less than fully rammed flasks are produced.Frequently, such flasks may be rejected, or if the flask is used in the process, an inferior casting may result.

Furthermore, the need for pressurized fluid and operators responsive thereto for driving the compacting heads results in a relatively complex, and thus, expensive, apparatus.

In my co-pending application Ser. No. filed September 29, 1 982 and entitled "Vibratory Method for Packing Foundry Sand Into a Pattern Prior to the Pouring of Molten Metal" (attorney's docket No. Case 30A) which is a continuation-in-part of my earlier application entitled "Vibratory Method for Packing Foundry Sand Into a Pattern", Ser. No.

212,988, filed December 4, 1980, now abandoned, there is described methods and apparatus which may be employed to obviate the problems encountered in prior art methods and apparatus in causing sand and binder to enter and compact within the unusual shapes of complex patterns to avoid the difficulties encountered with nonfully rammed flasks.

While the method and apparatus disclosed in my co-pending application is considered to work well for its intended purpose, occasionally there arises a need for greater compaction than can be provided by the vibratory system therein disclosed alone.

Consequently, there has been proposed apparatus which provides for compaction of foundry sand about a pattern contained in a flask utilizing both vibratory motion and fluid pressurized compacting. Again, such system works extremely well for its intended purpose but the need for compacting head operators and a relatively large source of pressure fluid for such operators increases the complexity of the apparatus and again, the expense thereof.

The present invention is directed to overcoming one or more of the above problems.

Summary of the Invention It is the principal object of the invention to provide a new and improved method and apparatus for making foundry molds. More specifically, it is an object of the invention to provide a simple apparatus that provides for compaction of sand in a foundry flask containing a pattern through the use of vibratory motion and a non-vibratory compacting force that is inexpensive in cost. It is also an object of the invention to provide a simple and inexpensive method of compacting sand in a flask containing a pattern through the use of vibratory motion and a non-vibratory force.

An exemplary embodiment of an apparatus made according to the invention achieves the foregoing objects in a structure including a base having means defining a flask receiving station. Means are disposed on the base for vibrating a flask disposed in the station in at least a vertical direction. There are provided a plurality of vertically moving compacting heads of substantial mass and means for lowering the heads into the station and allowing relative vertical movement between the heads while they are in the station without applying a downwardly directed force other than gravity thereto.

Consequently, the vibratory force provides compaction as does the force of gravity acting through the heads. A pressure source, and the cost of providing the same along with operators responsive thereto are eliminated.

In a preferred embodiment, the lowering means include a means mounting the heads for movement into and out of the station and for movement relative to each other in a generally vertically direction with the sole downward force acting upon the heads being that of gravity. Preferably, each of the heads has a lost motion connection to the mounting means. A powered actuator for raising and lowering the mounting means may also be provided. The powered actuator, the mounting means and the lost motion connections are constructed and arranged so as to be incapable of exerting a downward force on the heads.

A preferred embodiment of a method made according to the invention includes the steps of placing a pattern in a mold flask, filling the flask with foundry sand to a desired level, placing a plurality of weights on the upper surface of the sand and vibrating the flask and its contents including the weights in the absence of a downwardly directed force on the weights other than that of gravity. Preferably, the method includes the step of guiding the weights for substantially solely vertical movement during at least a portion of the step of vibrating.

Other objects and advantages will become apparent from the following specification taken in connection with the accompanying drawings.

Description of the Drawings Figure 1 is a side elevation of an apparatus made according to the invention, with parts broken away for clarity, at an initial stage in the operation of the apparatus; Figure 2 is a view similar to Fig. 1 but showing a subsequent stage in the operation of the apparatus; Figure 3 is a view similar to Figs. 1 and 2 but showing still a later stage in the operation of the apparatus; and Figure 4 is a view similar to the preceding views illustrating a final stage in the operation of the apparatus.

Description of the Preferred Embodiment Apparatus An exemplary embodiment of an apparatus made according to the invention is illustrated in the various figures of drawing and is seen to include a base 10 which may be disposed on an underlying surface 1 2 such as a floor or the like. Extending upwardly from the base 10 is an inverted, U-shaped frame 14.

Within the frame 14 and above the base 10 there is disposed a table 1 6 having an upper surface 1 8 defining a flask receiving station for receipt of a flask 20. As illustrated, the flask 20 has a pattern 22 disposed therein and has been filled to a desired level with a mixture of foundry sand and binder 24.

While not shown herein, it is considered that the table 1 6 may be provided with suitable conveying means to assist in the movement of the flask 20 to and from the station.

The table 1 6 is mounted above the base on a series of coil springs 26. Secured to the undersurface 28 of the table 1 6 are a plurality of electric motors 30 each having rotary output shafts 32 to which eccentric weights 34 are affixed.

As a result of the foregoing structure, when the motors 30 are energized, a vertical vibratory force will be applied to the table 16, and thus to the flask 20 thereon in a manner described in my previously identified co-pending application, the details of which are herein incorporated by reference.

Suspended from the upper end of the frame 1 4 is a pair of fluid cylinders 40 of the double acting variety. Each cylinder 40 includes an extendable rod 42 and a cross member 44 is secured to both of the rods 42 as by nuts 46 such that it overlies the flask receiving station.

The cross member 44 is provided with one or more rows of vertically extending bores or apertures 48 through which rods 50 slidably extend. Preferably, the fit is relatively close so that movement of the rods 50 within the apertures 48 is principally limited to the vertical direction. In other words, the apertures 48 guide the rods 50 for movement in the vertical direction.

The upper end of each of the rods 50 terminates in a cap 52 of larger diameter than the corresponding bore 48. The caps 52 serve as stops to limit downward movement of the rods 50 relative to the cross member 44.

Each of the rods 50, at its lower end, mounts a compacting head 54. The compacting heads 54 are disposed in close adjacency and yet are relatively movable with respect to each other by reason of the lost motion connection to the cross member 44 provided by the rods 50, the bores 48, and the stops 52.

Each compacting head 54 has a lower surface 56 which is adapted to abut the sand 24 contained in the flask to compact the same.

To assure uniform compaction by each to the heads 54, it is preferable that the ratio of the weight of all of the individual heads and their associated rods 50 and caps 52 to the area of their surfaces 56 be equal. Generally, but not always, this will mean that each assembly of a head 54, rod 50 and cap 52 be of identical mass and configuration.

Method The inventive method, contemplates as a first step, the placing of a pattern in a mold flask. For example, this step can be accomplished by placing a pattern such as a pattern 22 in a mold flask such as the mold flask 20.

The next step of the method involves filling the flask with foundry sand, and usually a binder, to a desired level. As illustrated in the drawings, this may be accomplished by filling the flask 20 with a foundry sand and binder mix 24 to a level well above the uppermost end of the pattern 22.

The next step of the method involves the placing of a plurality of weights on the upper surface of the sand. This can be accomplished using the above described apparatus as follows. Through suitable conventional controls, the cylinders 40 are caused to extend their rods 42 as illustrated in Fig. 2. This in turn lowers the cross member 44 until the rods 42 are fully extended. In the usual case, this will bring the cross member 42 to a level just slightly above the upper edge of the flask 20 but not sufficiently low as to engage the upper surface of the heads 54.

During the lowering process thus described, at some point in time, the compacting surfaces 56 of the various heads 54 will engage the upper surface of the sand and bear against the same.

The next step of the method involves the vibrating of the flask and its contents including the weights in the absence of a downwardly directed force on the weights other than that of gravity. This is accomplished by energizing the motors 30 as illustrated in Fig.

3. Where a generally purely vertical oscillation is desired, the motor shafts 32 are caused to rotate in opposite directions. Conversely, if a sideways force along with a vertical force is desired, the motor shafts 32 are caused to rotate in the same direction.

As a result of this step, the sand 24 will flow into crevices or passages, no matter how intricate, in the pattern 22 in the manner described in my co-pending application. At the same time, the force of gravity will be continuously operating on the compacting heads 54 to cause the same to move downwardly. Additionally, when the table 1 6 is moving upwardly, inertial forces will tend to cause compaction of the sand and binder mix 24.

When the desired degree of compaction is achieved, the motors 30 may be deenergized at which time oscillation of the flask 20 will cease. The cylinders 40 may then be caused to retract their rods 42 as illustrated in Fig. 4.

As the rods 42 retract, at some point in time, the cross member 42 will be brought against the underside of the caps 52, though not necessarily simultaneously, and continued retraction of the rods 42 will cause the heads 54 to be moved outwardly to a location above the flask receiving station as seen in Fig. 4. At this point, the flask 20 may be removed from the apparatus and moved to any desired location for further processing.

It will also be observed that during the foregoing method, a step of guiding the heads 54 for substantially solely vertical movement occurs during at least a portion of the step of vibrating. This step is performed in the above apparatus by the relationship of the bores 48 to the rod 50 as described previously and assures uniform compaction of the sand and binder mix 24 within the flask 20. Finally, it will be observed that at no time is there a downwardly directed force on the heads 54 other than that of gravity. Thus, the force of gravity is utilized to avoid the need for operators to force the heads 54 downwardly and any source of energy therefore, Consequently, the apparatus is greatly simplified over prior art apparatus and is considerably less expensive to build. Nonethless, the advantages of combined vibratory and non-vibratory compaction of the sand and binder mix 24 are retained.

Claims (9)

1. A foundry mold making apparatus comprising: a base including means defining a flask receiving station; means on said base for vibrating a flask disposed in said station in at least a vertical direction; a plurality of vertically movable compacting heads of substantial mass, and means mounting said heads for (a) movement into and out of said station and (b) movement relative to each other in a generally vertical direction; said apparatus being free of motor means for uring said heads downwardly when in said station such that gravity is the sole downward force acting upon said heads.

2. The foundry mold making apparatus of claim 1 wherein each of said heads has a lost motion connection to said mounting means.

3. The foundry mold making apparatus of claim 2 further including a powered actuator for raising and lowering said mounting means, said powered actuator, said mounting means and said lost motion connection being constructed and arranged so as to be incapable of exerting a downward force on said heads when said heads are in said station and yet move said heads into and out of said station.

4. The foundry mold making apparatus of claim 2 wherein each said lost motion connection includes a stop for limiting downward movement of the corresponding head relative to said mounting means.

5. A foundry mold making apparatus comprising: a base including means defining a flask receiving station; means on said base for vibrating a flask disposed in said station in at least a vertical direction; a plurality of vertically movable compacting heads of substantial mass, and means for lowering said heads into said station and allowing relative vertical movement between said heads while in said station without applying a downwardly directed force thereto.

6. The foundry mold making apparatus of claim 5 wherein said lowering means is further operable to lift said heads out of said station.

7. The foundry mold making apparatus of claim 5 including means for guiding said heads for substantially solely vertical relative movement.

8. In a method of forming a mold for metal casting, the steps of: placing a pattern in a mold flask; filling the flask with foundry sand to a desired level; placing a plurality of weights on the upper surface of the sand; and vibrating the flask and its contents including the weights in the absence of a downwardly directed force on the weights other than that of gravity.

9. The method of claim 8 further including the step of guiding the weights for substantially solely vertical movement during at least a portion of the step of vibrating.