GB2134426A - A vibratory ram compaction mold forming machine for a foundry - Google Patents

Abstract

The machine includes a frame (12) having upper and lower ends, through which a horizontal conveyor (32) extends to define with the frame a flask receiving station (42). A plurality of compacting heads (46) are mounted on the frame for vertical movement toward and into and away from and out of a flask at the receiving station. A flask or pattern carrier vibrating system including at least one anvil (52), and at least one vibration generating member (55) resiliently mounted between the anvil and a base (82), is located at the lower side of the flask receiving station to engage the flask or a pattern carrier. The vibration generating member is operatively driven in the high frequency range of from about 720 cycles per minute to about 3600 cycles per minute to vibrate the anvil in the vertical direction prior to and during operation of the compactor heads to work the sand into all voids in the pattern prior to compaction by the compactor heads. Pneumatic means (173) (Figure 6 not shown) may be provided, to raise the vibrating system into and out of contact with the flask. <IMAGE>

Description

SPECIFICATION A mold forming machine for a foundry Field of the invention This invention relates to mold forming machines and more particularlyto an improved mold forming machine having a vibratory impact apparatus in combination with a ramming assemblyforforming a mold about a pattern.

Background of the invention In a foundry, many different methods and techniques have been adopted in recent years to modernize the age old system of forming metal in a desired shape by melting and casting the metal in a mold. Early forms of such metal forming employed the use of a pattern in a lower half or drag of a flask or mold box with sand and clay tamped or packed around the appropriate portion of the pattern until the sand and clay assumed the shape of the appropriate portion of the pattern, whereupon the pattern was removed. The same procedure was used for form the shape of the pattern in the upper half or cope of the flask. Appropriate core pins were inserted when needed and a gating system using sprues and risers were provided whereupon the cope was assembled with and locked to the drag and the metal was poured.

One type of mold forming machine available on the market employs a pattern carrier for receiving a plate upon which a portion of a pattern is mounted.

The pattern projects upwardly into a flask or mold box that has been filled with loose foundry sand. The machine provides for lining up the flask with a platen having a plurality of downwardly projecting squeeze or compressing heads which advance into the flask for pressing the sand around the pattern. The squeeze heads are withdrawn and the pattern carrier with the mold box is moved to the next station.

Another type of mold forming machine, called a single station machine, has a cope and a drag pattern shuttled in, squeezed and removed alternately on pattern carriers. Another example of a mold forming machine has a cope and a drag pattern both mounted on the same carrier with a cope flask and/or a drag flask brought in simultaneously or alternately whereupon the flask is filled, squeezed and removed.

Although the above described mold forming machines are but a few of the many available and although they are efficient and generally acceptable, there are certain patterns that have shapes and/or configurations that do not fully accommodate to the squeeze or compressing effect so that less than fully rammed flasks are produced, resulting in rejected molds or, if the mold is used, it results in less than an acceptable casting.

Different systems have been tried to overcome this problem, such as blowing air up through the loose sand to agitate the sand and distribute the sand prior to ramming. Nonetheless, certain areas of the pattern are sometimes bridged, producing less than acceptable rammed flasks which must be rejected or which produce inferior castings.

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

Summary ofthe invention It is the principal object of the invention to provide a new and improved mold forming machine having improved compaction and flowability characteristics of the sand in the making or producing of the molds.

More specifically, it is an object of the invention to provide such a machine wherein undesirable bridging in flasks is avoided or minimized to an acceptable level to eliminate rejected molds and/or inferior castings produced using such molds.

An exemplary embodiment of the invention achieves the foregoing objects in a mold forming machine having a base including means defining a mold making station. Ram means are movably mounted on the base for movement into the flask at the mold making station to ram the contents of the flask. A vibratory impact apparatus is directly beneath the pattern and is in contact with the pattern carrier supporting the pattern and flask in the mold making station. The vibratory action produced by the vibratory means before and/or during the ram operation causes the foundry sand in the flask to flow more uniformly around the pattern and eliminates voids therein and provides increased and uniform density to the mold.

In a preferred embodiment of the invention, the ram means and the vibratory means are disposed above and below the mold making station. Preferably, the vibratory means comprises an anvil located generally below the flask receiving station and mounted to engage the pattern carrier received at that station. The vibratory means includes a vibratory impact assembly consisting of a motor, an unbalanced rotor, a spring assembly and a frame operatively associated with the anvil.

Means may be provided to mount the unbalanced rotor on the base through a spring system to the anvil.

In a highly preferred embodiment, the anvil comprises a housing which contains a motor for driving the unbalanced rotor through a spring assembly producing a linear motion that is so arranged with respect to the anvil of the machine to produce or impart a vertical motion to the pattern carrier thereby migrating the sand and together with the squeeze heads will compact the sand about the pattern.

A rotating air vibrator or an electric vibrator can be used to produce a high frequency but will not produce the required force. However, by using such high frequency vibrators with a two mass system it is possible to amplify the small force to produce the force necessary to impart movement to the sand in the flask. Using a high frequency of between about 720 cycles per minute to 3600 cycles per minute when amplified with a two mass system will produce the force necessary to get migration of the sand particles around the pattern.

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 a mold forming machine made according to the invention with parts broken away and shown in section for clarity; Figure 2 is an end elevation of the machine taken at right angles to the showing of Figure 1, also with parts shown in section; Figure 3 is an enlarged, sectional view of a vibratory machanism employed in the machine; Figure 4 is a further enlarged view taken at right angles to the view of Figure 3 showing the vibratory mechanism; Figure 5 is an end elevational view of a modified form of vibratory mechanism; Figure 6 is a side elevation view taken at right angles to the showing of Figure 5; and Figure 7 is a partial sectional view taken on the line 7-7 of Figure 6.

Best mode for carrying out the invention An exemplary embodiment of a mold forming machine made according to the invention is illustrated in the drawings and with reference to Figures 1 and 2 is seen to include a base or frame, generally designated 10. The base 10 includes four vertical posts 12 disposed on the corners of a rectangle and interconnected at their upper ends by a rectangular configuration of two beams 14 and two beams 16, only one of each being shown. The upper ends of the posts 12 receive fasteners 18 to securely fasten the beams 14 and 16 in place.

The lower ends of the posts 12 terminate in feet 20 which in turn are seated and secured to an underlying surface 22 in the form of a floor orthe like. A first pair of spaced cross plates 24 extend between end plates (not shown) secured to the feet 20 below the beams 16 at the lower end of the base 10 as do a second pair of cross plates 26. In addition to the usual function of strengthening the base 10, the plates 26 together with four plates 28 (Figure 1) which extend between and are secured to the plates 26, serve as guide for purposes to be described hereinafter.

As seen in Figures 1 and 2, a pair of horizontally disposed, spaced box beams 30 extend through the base 10 at about the height of the upper ends of the cross plates 24. Each of the box beams 30 journals a plurality of flanged rollers 32 which serve as a conveyorfor conveying an object to be processed by the machine into and out of the machine. More specifically, that part of the conveyor defined by the beams 30 and rollers 32 within the base 10 defines a flask receiving station, generally designated 34. In one form of machine, a four sided frame 36 is sized to ride on the rollers 32 and is retained by the flanges thereon to removably mount a pattern board 38 having a pattern 39 on at least the upper surface thereon.A conventional flask 40 in turn is placed on the pattern board 38 in any suitable fashion and will either contain loose foundry sand before the flask arrives at the flask receiving station or will have loose foundry sand added thereto at the flask receiving station.

Above the flask receiving station 34, the base 10 mounts a so-called "squeeze head", generally designated 42, which may be of any known type. For example, one suitable construction is that embodied in the commercially available Herman Moldmaster.

The squeeze head 42 includes a plurality of fluid cylinders (not shown) each having an extendable rod 44 terminating in a respective compactor head 46. As can be seen in Figures 1 and 2, the compacting heads 46 are arranged in close adjacency in multiple rows and are movable between the solid line position where they have entered the flask 40 and the dotted line position where they are removed from the flask 40. As is well known, the compacting heads 46 are driven downwardly into the flask 40 when the flask is at the flask receiving station 34 under the influence of fluid under pressure and serve to compact the foundry sand about the pattern 39 carried by the pattern board 38. As alluded to previously, in the case of many patterns, operation of the compacting heads 46 is sufficient to produce satisfactory molds.However, as also alluded to previously, in the case of a number of patterns, particularly those of complex shape, the action of the compacting heads 46 is insufficient to produce satisfactory molds due to the tendency of the foundry sand not to fill the voids and crevices in the pattern and due to the sand bridging during compaction by the compacting heads 46.

To solve the problem, the invention contemplates that the machine be provided with vibratory means mounted on the base 10 in proximity to the flask receiving station 34 and operable to vibrate the flask 40 and its contents of foundry sand when the flask 40 is in the flask receiving station 34 to flow or move the sand into the crevices and voids and to break up any bridging prior to and during operation of the compactor heads 46. As seen in Figure 1, two such vibratory means, each generally designated 50, are disposed in the lower end of the base 10 between associated ones of the plates 28. As seen in Figure 2, such vibratory means 50 are also disposed between the plates 26. Turning now to Figure 3, one version of a suitable vibratory means 50 includes an upper anvil or hammer 52 and a vibration generating member 55.As best seen in Figure 4, the upper surface 54 of each anvil 52 is slightly crowned. When assembled into the remainder of the apparatus as illustrated in Figure 1, the upper surface 54 of each anvil 52 will be approximately in the plane of the lower edge of the carrier frame 36. The crowning of the surface 54 insures that as the carrier frame 36 is being rolled on the rollers 32 into the flask receiving station 34, edges of the frame 36 will not encounter edges of the anvil 52 and prevent such movement.

Such edges of the frame 36 will gradually engage the crown surface 54 of the anvil 52 as the frame 36 is advanced into the station 34. Thus, the crown surface 54 prevents any hangup of the frame 36 during such movement.

Depending from each anvil 52 is one vibration generating member 55 which includes side plates 56 as can be best seen in Figure 4. At the lower end of the side plates 56 there is an interconnecting end plate 58 and the anvil 52, the side plates 56 and end plate 58 define a housing having an interior generally designated 60. Within the housing interior 60, there is located a vertically directed base plate 62 which mounts a motor 64, preferably electric, having a rotary output in the form of a shaft 66. While not shown, the shaft 66 extends from both ends of the housing of the motor 64 and each such end mounts an unbalanced rotor 68. As a consequence, when the motor is energized, vibration will result.

The upper end of the base plate 62 mounts a horizontally directed plate 70, also within the interior 60 while a similar plate 72 is suitably secured to the lower end of the base plate 62. Side plates 74 extend between the plates 70 and 72 and are secured to the same along with the plate 62. The vibratory motion produced upon energization ofthe motor 64 will, of course, be imparted to the plates 70 and 72 by reason of their connection to the base plate 62 on which the motor 64 is mounted. This motion is in turn conveyed to the anvil 52 via first spring means in the form of spring pairs 76 and 78. Specifically, the springs 76 are interposed between the plate 70 and the undersurface of the anvil 52 while the springs 78 are interposed between the plate 72 and the upper surface of the end plate 58.As best seen in Figure 3 and 6, the springs of each pair may be separated by a separator plate 80 mounted on the appropriate one of the anvil 52 or the end plate 58.

Returning to Figures 1 and 2, cross plates 82 extend between and are secured to the lower edges of the plates 26 and in turn mount a second spring means in the form of a coil spring 84 which abuts the undersurface of the end plate 58. The springs 84 act as isolation springs for the vibrating means 50.

It will be recalled that the plates 26 and 28 act as guide means. Specifically, they act as guide means for each of the anvils 52 and the associated housing defined by the plates 56 and 58. The same serve to guide both the anvil and the motor 64 and unbalanced rotors 68 associated therewith in a vertical direction, thereby limiting vibratory movement imparted to the anvil 54 primarily to pure vertical motion.

The apparatus is completed by other structural interconnecting plates and box beams in the locations illustrated for strengthening purposes. And, of course, circular locating disks such as that shown at 90 in Figure 4 may be secured to various ones of the plates at the points where the springs 76,78,84 abut the same to properly maintain the springs in the desired position. It is to be understood that the vibratory means 50 could operate without the springs 76,78 using only the isolation springs 84 and brute force from the vibrating means to the frame, pattern board, pattern, sand and flask.

Foundry sand of the type used in mold forming machines is generally wet such that particles of sand will have shear angle forces therebetween which combine with external static forces to create resistance to relative movement between adjacent particles. It has been found that operating the motor and unbalanced rotor at high frequencies will produce a small force which is not sufficient to overcome the shear forces necessary to create migration of the sand particles. However, using the high frequencies with a two-mass system will amplify the small forces enough to reduce the shearforces between the particles so that the particles will move relative to each other and will work into the crevices of the pattern. Using a vibratory means 50 of the general type described above or as is shown in U.S. Patent No.3,353,815 to A.Musschoot, a range of high frequencies from about 720 cycles per minute to about 3600 cycles per minute when combined with the two-mass system incorporating one mass, anvil 52, and a second mass, unbalanced rotor 68, has been found to produce the unexpected movement of the sand particles relative to each other such that the sand particles move into apertures, crevices and other surface irregularities on the pattern 39 to fill same.

In operation, a carrier frame 36, pattern board 38 and flask 40 with foundry sand in the latter is moved along the rollers 32 into the flask receiving station 34. During this operation, the compacting heads 46 are in the dotted line position illustrated in Figures 1 and 2. Once the flask 40 is properly positioned in the station 34, the vibrating means 50 is activated to operate in the high frequency range between 720 and 3600 cycles per minute. This vibratory motion is conveyed to the anvils 52 which are vibrated in the vertical direction due to the guiding action provided by the plates 26 and 28. As a consequence, the upper surface 54 of each of the anvils 52 will abut and vibrate the frame 36 which in turn will convey such vibratory motion to the flask 40.Consequently, the sand in the flask will be vibrated to cause the sand particles to move and work into the voids and crevices in the pattern 39. The vibrating motion applied to the sand will cause any sand bridges to break up, eliminating voids within the flask 40. At an appropriate time either almost simultaneously with or shortly after the vibrating means 50 has been activated, the squeeze head 42 is operated to move the compactor heads 46 into the flask 40 to exert a compacting force against the sand to compress the sand into conforming relationship with the shape of the pattern 39. The vibratory means 50 is shut down once the compactor heads 46 have substantially pressed the sand around the pattern. Continued action of the compacting heads 46 will cause compaction of the sand after the voids have been eliminated to assure that the flasks are fully rammed.

This in turn results in fully acceptable flasks and high quality castings made using such flasks.

Although the drawings in Figures 1 and 2 show a solid line position ofthe plural compactor heads 46 to be substantially in a common plane, in practice the sand will compact differently at different locations in the flask partially due to the presence of the pattern and partially due to less dense sand accumulating in one location as distinguished from another.

The result will be that each compactor head 46 is likely to end up at a different level -- higher over the pattern, lower in the corners. After the flask 40 and carrier 36 pass beyond the receiving station 34, additional sand and binder mix are added to fill up the flask. Appropriate sprues and risers either are molded into the sand (for instance, as part of the pattern) or are cut into the sand in the flask after compacting. The movement of the sand caused by the high frequency vibrating means 50 into the voids and crevices of the pattern and the breaking up of bridges in the sand prior to or simultaneous with the squeeze compaction of the sand creates an improved mold upon completion of the squeeze compaction of the sand in the flask.

A rotating air vibrator or an electric vibrator may be substituted for the motor and unbalanced rotor vibration generating system, the only limitation being that they are capable of operating in the high frequency range between about 720 cpm and 3600 cpm.

A modified form of the invention is shown in Figures 5-7 wherein a vibratory means 150 includes an anvil 152 which has two anvil surfaces 153,153 spaced apart from each other (Figure 6) while having a common connecting base 157. Appropriate guides 159 are provided to guide the anvil 152 in a vertical direction both when under vibration and when moved up or down as will be described hereinafter.

The anvil 152 is carried on a rigid plate 161 which extends beneath both anvil surfaces 153,153. Plural sets of springs 163 are mounted between the rigid plate 161 and an exciter plate 165, which exciter 165 is supported by isolation springs 167 mounted on platforms 169 on the floor. There are three sets of springs 163, with one set aligning with one pair of isolation springs 167, a second set aligning with the other pair of isolation springs 167 and the third set being mounted at the midportion of the anvil 152, plate 161 and exciter 165. A rigid mounting platform 171 is mounted to the floor and supports a pair of inflatable air mounts 173 which air mounts are connected to the underside of exciter 165.The air mounts 173 are positioned with respect to the center of the anvil in such a way that both spaced surfaces 153,153 of the anvil 152 are raised or lowered simultaneously upon inflating or deflating the air mounts 173. A source of air under pressure is used to inflate the air mounts 173 which air mounts are of a conventional, commercially available type.

A pair of vibration generating members 155 are provided and include a motor 164 and a pair of unbalanced rotors 168 driven by the motor. Each motor 164 is supported on a bracket 177 secured to the underside of the exciter 165. The brackets 177 are symmetrically mounted to the exciter 165 on opposite sides of the air mounts 173 such that the two vibration generating members 155 are mounted relative to the two surfaces of the anvil 152 so as to produce a uniform vibratory motion to both surfaces. The vibration generating members 155 are operated by driving the motors 164 in opposite directions so that pure vertical vibratory motion is provided to both surfaces of the anvil 152.

The vibration generating system is a two-mass system with one mass being the anvil 152 and the other mass being the unbalanced rotors 168. The two mass system when combined with the motors 164 and unbalanced rotors 168 operating at high frequencies in the range of about 720 cpm to 3600 cpm will produce the unexpected phenomenon in the wet sand in the flask whereby the sand particles move and work relative to each other so as to fill crevices and voids in the pattern.

In operation, a frame 36, a pattern carrier 38 with a pattern 39 and a flask 40 with wet sand therein is moved into the flask receiving station. The anvil 152 and vibration generating members 155 are in the lowered position with the air mounts 173 collapsed.

The vibration generating members 155 may be started while the anvil is in the lowered position or may be started after the air mounts 173 are inflated to raise the anvil 152 into contact with the frame 36.

In either situation, the anvil when in contact with the frame 36 provides a high frequency vibratory motion to the flask which moves and works the sand particles relative to each other so as to fill voids and crevices in the pattern 39. At the appropriate time the squeeze head 42 is lowered and the compacting heads 46 are pressed against the sand to compact the sand into pattern conforming configuration. The air mounts 173 can be deflated with the vibratory members operating and with the compacting heads 46 still compacting the sand so as to release the anvil from the frame and flask to prevent damage to the newly compacted mold by the vibratory members continuing to vibrate the flask after the compacting heads 46 have been removed from the flask.

Claims (16)

1. Amoldforming machine comprising: a base including means defining flask receiving station; ram means movably mounted on said base for movement toward and away from said flask receiving station so as to be movable into a flask at said flasks re-receiving station and ramming the contents thereof; and vibratory means mounted on said base in proximity to the flask receiving station and operable to vibrate a flask and its contents when the flask is in said flask receiving station and during operation of said ram means.

2. The mold forming machine of claim 1 wherein said ram means and said vibratory means are disposed on opposite sides of said flask receiving station.

3. The mold forming machine of claim 1 wherein said vibratory means comprises an anvil located on one side of said flask receiving station and positioned to engage an object received therein, and a vibration generating member operatively associated with said anvil.

4. The mold forming machine of claim 3 including means resiliently mounting said vibration generating member on said base, and spring means interconnecting said vibration generating member and said anvil.

5. The mold forming machine of claim 3 wherein said vibration generating member is operated within a high frequency range from about 720 cycles per minute to about 3600 cycles per minute.

6. The mold forming machine of claim 3 wherein means are provided for raising and lowering said vibratory means into and out of contact with said flask receiving station.

7. The mold forming machine of claim 6 wherein said means is a pair of inflatable air mounts.

8. Amoldforming machine comprising: a base including means defining a flask receiving station; a plurality of compactors mounted on said base above said flask receiving station and movable into a flask disposed in said flask receiving station to compact foundry sand contained within said flask; and means for vibrating a flask in said flask receiving station, said vibrating means being mounted on said base below said flask receiving station.

9. The mold forming machine of claim 8 wherein said flask receiving station defines means including a conveyor for supporting a flask in said flask receiving station and for conveying a flask into and out of said flask receiving station.

10. The mold forming machine of claim 8 wherein said vibrating means comprises a two mass means and a vibrating generating member operatively associated with the two mass means.

11. The mold forming machine of claim 10 wherein said vibration generating member is operated with in the high frequency range from about 720 cycles per minute to about 3600 cycles per minute.

12. A mold forming machine comprising: a generally vertically extending frame having upper and lower ends; a generally horizontal conveyor extending through said frame intermediate said ends; that part of the conveyor within said frame cooperating with said frame to define a flask receiving station; a plurality of compacting heads mounted on said frame upper end for generally vertical movement toward and into, and away from and out of said flask receiving station; means for vibrating an object such as a flask or pattern carrier, received in said flask receiving station; said means comprising an anvil means and a vibrating generating means, said anvil means having at least one anvil at the lower side of said flask receiving station and disposed to engage said object; said vibration generating means comprising a rotary output motor in said frame lower end; at least one unbalanced rotor connected to and driven by said motor; means on said frame lower end guiding said anvil and said motorfor movement in a generally vertical direction; and isolation spring means interacting between said vibrating means and a foundation.

13. The mold forming machine of claim 12 wherein said vibrating means includes spring means between said motor and said anvil.

14. The mold forming machine of claim 12 wherein said anvil has a crowned upper surface.

15. The mold forming machine of claim 12 wherein said anvil comprises a housing containing said motor, said unbalanced rotor, and said spring means, said spring means comprising at least two springs sandwiching said motor therebetween, and each abutting said housing.

16. The mold forming machine of claim 12 wherein said vibration generating means is operated with the high frequency range from about 720 cycles per minute to about 3600 cycles per minute.