US2700472A - Foundry mold shakeout device - Google Patents

Description

Jan. 25, 1955 R. M. CARRIER, JR., ETAL 2,700,472

FOUNDRY MOLD SHAKEOUT. DEVICE Filed Jan. 28, 1950 w NNN N.

FOUNDRY MOLD SHAKEOUT DEVICE Robert M. Carrier, Jr., and Maurice G. Whitley, Louisville, Ky., assignors, by mesne assignments, to Carrier Conveyor Corporation, Louisville, Ky., a corporation of Kentucky Application January 28, 1950, Serial No. 141,098

1 Claim. (Cl. 209-329) This invention relates to an improved foundry mold shakeout device. More particularly, it has to do vwlthlan improved spring mounted device and means for vibrating the device in synchronism with the natural frequency of the spring mounting.

in foundries, a large portion of the castings are made in molds formed inside removable flasks, such as typical snap flasks. After the mold is formed, the flask is removed, and the molten metal poured into the mold. After the casting has solidified, the sand mold must ybe broken away from the casting.

At present, vibrating shakeout devices are used to separate the sand from the casting. It is an important object 'of the present invention to provide an improved, more ecient vibrating shakeout device.

Another object of this invention is to provide a shakeout device that is portable and may be moved from place to place in th-e foundry.

A still further object of this invention is the provision of a balanced shakeout device that has substantially no frame vibration, thus eliminating movement of the device relative to the floor even though it is mounted on wheels.

In accordance with the principles of the present invention there is provided a shakeout pan mounted on leaf springs above a rigid base. A counterbalance slab is disposed immediately below the pan and is also mounted on springs from the rigid base. A power-driven eccentric mechanism is mounted on the base and is connected to the pan for reciprocating the pan which is connected in driving relation to the counterbalance slab through a coil spring.

A self-adjusting uid cylinder is connected in the eccentric drive mechanism so that the shakeout pan can move to accommodate itself to changes in the weight of the load on the p-an. This`uid cylinder has the ability to slowly expand and contract under changes in loading on the pan. However, when the pan is being vibrated, the fluid cylinder acts as a rigid link which always keeps the drive mechanism and the pan vibrating in synchronism.

Other and further features, objects and advantages of the present invention will become apparent to one skilled in the art from the following detail description taken in connection with the accompanying drawings.

Figure l is a side elevational view of a mold shakeout device, with parts broken away, constructed according to the features of the present invention.

Figure 2 is a vertical sectional view taken substantially on line lI--II of Figure 1.

Figure 3 is a vertical sectional view taken on line III-III of Figure 1.

Figure 4 is a vertical section-al view taken on line IV-IV of Figure l.

As shown on the drawings:

One of the principal reasons why the shakeout device of the present invention is more efficient and more economical than the shakeout devices furnished heretofore is that the shakeout pan is vibrated at the natural frequency of the spring mounting.

This advantageous operation may best be explained by visualizing a long straight leaf spring mounted in a vertical position with its bottom end secured to a support structure and its upper end free to swing. If the upper end is flexed away from the central upright position and then released, the upper end will tend to move back through the central position to an opposite position as far on the other side of the central position as it was in the original nited States Patent 2,700,472 Patented Jan. 25, 1955 position. It will not tiex quite as far away from the E central position, however, due to inertia losses in the spring itself. However, once the spring is flexed, it will continue to make complete, full swing oscillations as long as the internal power loss is compensated for. Thus, in a mold shakeout operating at the natural frequency of the spring mounting, the power means must supply only enough power to replace internal losses. W'hen the power means is not in synchronism with the natural frequency, it must supply power to actually move the' pan and the load. Approximately ten times as much power lis required to drive an empty shakeout device not operating at natural frequency as is required to drive a natural frequency shakeout device empty.

-In the present invention, the advantages of natural frequency operations has been applied to a mold shakeout pan by mounting the pan on springs and providing a drive mechanism that is capable of reciprocating the pan at the natural frequency of the spring mounting.

The natural frequency of a spring mounting under a load mounted directly on the spring with-out extern-ally connected dampening means may be computed from the equation where N equals the frequency in cpm. and d equals the deflection under the load in a vertical direction.

While the natural frequency of a spring mounting may be calculated from the above mentioned formula, it must be remembered that the relation of the drive mechanism land the shakeout device is such that they will operate in resonance in a range which extends approximately `v5% above and below the calculated value. Thus, if the calculated or -mean value of the natural frequency is 285 vibrations per minute, the range of resonance will extend approximately from 270 to 300 vibrations per minute.

Therefore, it is to be understood that hereinafter when the natural frequency range of a spring mounting is referred to, it means the rangeyin which the drive means in the conveyor are in resonance,

Thus, when the natural' frequency of the spring mounting is determined, the drive mechanism may be chosen to maintain the natural frequency recipr-ocation.

In Figure l, the reference numeral 10 indicates mold and shakeout pan'having a solid bottom wall 11 on which the molds are placed. At one end of the bottom wall 11, an opening 12 therein is covered by a' plurality of rods 13 which may be suitably secured to the underside of the Wall 11, as by welding.

The mold pan 10 is supported on spaced spring assemblies 16 and 17 from a rigid support base 14. The support base 14 maybe suitably made of longitudinal channel members secured at their ends by cross channel members and mounted intermediate their ends on wheels 15. Each of the spring assemblies 16 and 17 includes a plurality of separate spring members 19 (Figure 2) secured at their ends by bolts 21 to transverse channel members 22 and 23. The channel member 22 is secured at its end as by welding between flange plates 25 which are welded to the side of the moulding pan and extend slightly therebelow to receive the channel member 22. The lower channel members 23 are welded at their ends between the web of the channel members of the base 14.

The shakeout pan 10 is reciprocated `by means of a drive mechanism 28 including a pulley wheel 29 driven by a belt 30 from a motor 31. Pulley wheel 29 is keyed to a crankshaft 33 that is journalled in spaced bearings 35 (Figure 2) which are mounted on a transverse plate 37. The plate 37 issecured at either end to channel members 38 supported on the base 14.

The crank arm 39 hlas one end connected on the throw of the crankshaft 33 and the other end pivotally connected to a block 40 sldably disposed ina composite lever 41. The lever 41 may be preferably made up of two spaced bars 42 connected at their ends by bolts 43 and spacer washers 44.

Each link 42 has a longitudinal slot 46 arranged to receive upstanding outwardly extending projections 48 on the block 40 which is sldably disposed between the arms. VThe upper end of the lever 41 pivotally receives a ange, 49 of a transverse angle 50 while the lower end pivotally receives the end of a piston rod 51 which extends from a fluid power cylinder 52 which may take the form of a conventional direct actingshock absorber. The cylinder 52- has an ear SZasecured to one end thereof and pivotally connected to an upstanding ear 53 of a ange plate 54 by means of a bolt 55. The ange plate 54 may be formed integrally with the cross transverse plate 37 on which the bearing members 35 are mounted.

To permit an adjustment of the lengthfof stroke during operation of the pan, a feed screw 57 is mounted in the composite lever 41'between the side arms 4Z extending longitudinally thereof and having a reduced portion 59 journalled in a cross block 60 which is secured between the arms 42. The feed screw extends through a threaded opening in the sliding block 40 so that rotation of the screw will cause the block to move up and down in the composite lever arm 41. A collar 63 is secured to the screw 57 above the block 60 together with a bevel gear 65 which is in mesh with a bevel gear 66 keyed to a shaft 67. The shaft 67 is journalled in a bracket 69 secured to the lever 41 and is provided with a hand wheel 70. It will be seen that rotation of the hand wheel 70 causes rotation of the feed screw 57 and movement of the block 40 up and down longitudinally of the arm 42 to vary the point of connection of the arm 39 with the lever 41 and thus vary the length of stroke of the shakeout pan 10.

It is to be particularly noted that the shock absorber 52 is connected to the composite link 41 at a much greater distance from the shakeout pan than is the crank arm 39. Thus, the movement of the end of shock absorber will be much less than the movement of the crank arm. In a typical installation there is no noticeable movement of the telescoping parts of the shock absorber while the pan is being reciprocated with a standard length of stroke.

The shock absorber 52 has the ability to slowly expand and contract on a change in load on the mold shakeout pan. However, when the pan is operating, the shock absorber acts as a substantially rigid link.

The shock absorber 52 therefore is connected in the drive linkage to aid the machine in starting and stopping; to allow the conveyor to settle on the spring mounting, and to guarantee that no weight is transferred back to the eccentric drive. The slow automatic settling action of the shock absorber could be accomplished of course through mechanical devices such as a friction link, inertia link, a pivotal link, or a magnetic link.

To counterbalance this mold shakeout device and make it substantially vibrationless in operation there is provided an elongated rectangular slab 72 which is mounted on spaced spring assemblies 73 and 74, identical to the spring assemblies 16 and 17, and similarly mounted on cross-channel members 75 and 76.

The slab has an opening 77 in its surface through which a portion of the drive linkage 28 extends and an opening 78 through which a coil spring 79 extends. The coil spring 79 is suitably secured at one end in a slanted ange S connected to the bottom of the slab 72 by means of reinforcing side anges 81. At the upper end the coil spring is suitably secured in a slanted cross flange 82 which is braced by side flanges 83. The slanted anges 80 and 82 are substantially parallel so that the motion of the pan 11 can be transmitted to the slab 72 by means of the coil spring. Thus, when the drive mechanism 2S is started up, the mold pan 11 will begin to reciprocate and, through the medium of the coil spring 79, the counterbalance slab 72 will begin to oscillate at the same sneed but 180 out of phase. Thus. when the mold pan 11 is going in one direction, the slab is going in the opposite direction.

In operation, the mold with the solidified casting is placed on the left hand end of the mold pan 11 as seen in Figure 1. As the mold pan is reciprocated, the mold will gradually move toward the right due to the fact that, as the spring arms reciprocate, the pan 11 will move in a path such as to cause the mold to slightly leave the surface in a direction toward the right, as seen in Figure l. While the molds are off of the surface the shakeout pan 11 moves in an opposite direction and thus the molds are displaced'to the right a short distance at each reciprocation. This action shakes the mold and the casting and, as 'the mold progresses from the left hand side to the right hand side of the mold shakeout pan 11, the sand becomes loose from the casting. When the sand reaches the cross bars 13, it will be discharged therethrough while the casting will continue to the end of the mold pan and be discharged into a suitable casting receptacle.

It is a particular feature of this invention that the mold shakeout pan and the counterbalance slab which reciprocates out of phase are so mounted that they do not set up vibrating or shaking movements. Referring to Figure 1 it will be seen that a line drawn through the channel 23 is exactly the same distance, measured in a direction parallel to the at rest position of the spring, from a line drawn through the base channel 76 of the spring assembly 73 in the spring assemblies, at both ends of the unit. This distance is indicated by the reference character x.

It will be seen therefore that the couple set up by each pair of spring assemblies will exactly balance out. Thus, there will be no tendency to shake the structure during the operation of the pan and the slab.

While we have illustrated and described a counterbalance slab 72 which is driven from the shakeout pan 10 through a spring 79, it will be obvious that the slab could be driven independently from a second eccentric mechanism identical to the drive mechanism 28 but 180 out of phase therewith.

From the foregoing description it will be seen that there is provided in this invention a highly eflicient mold shakeout device which makes use of the natural frequency theory of operation. This method of oscillating the mold pan in synchronism with the natural frequency of spring mounting permits efficient shaking movement which moves the mold and the casting along the mold shakeout pan with a substantial saving in power input.

lt will be understood that modifications and variations may be effected without departing from thescope of the novel concepts of the present invention.

We claim as our invention:

In a mold shake-out device, the combination of a base, a sand mold and casting supporting and conveying structure having a grate portion through which the sand of such mold is adapted to be discharged, a counterbalance structure of substantially the same weight as said conveying structure, substantially identical resilient means respectively extending between said base and said conveying structure and between said base and said counterbalance structure for supporting said structures for directionally controlled vibration along the same paths and at substantially equal predetermined natural frequencies, said conveying structure when thus vibrated being effective to convey a sand mold therealong. drive means extending between said base and said conveying structure for substantially positively vibrating said conveying structure at its said natural frequency and at substantially uniform amplitude under varying conditions of load thereon, said drive-means including a crank bearing mounted on said base, a crank journalled in said bearing, and a drive linkage pivotally connected at one end to said crank and pivotally connected at the other end to said conveying structure, said linkage being characterized in having a shock absorber therein which permits static settling of said conveying structure with respect to said base, under the influence'ofk its own weight and a load thereon, on thel resilientmeans for said conveying structure without imposing any substantial load on said crank and crank bearing, and further characterized in that said shock absorber is substantially inliexible during transmission of natural frequency energy impulses from said crank to said conveying structure whereby the distance between the pivotal connections of said linkage to said conveying structure and to said crank remains substantially constant to thus maintain substantially uniform amplitude vibration of said` conveying structure under varying condition of load thereon, and resilient energy transmitting means extending between said structures and effective to transmit uniform amplitude, opposite phase vibration from said conveying structure to said counterbalance structure whereby the forces of the oppositely vibrating structures are balanced with respect to said base and further effective to transmit settling of said conveying structure due to load change to the resilient means for said counterbalance structure.

(References on following page) References Cited in the le of this patent UNITED STATES PATENTS Roth Apr. 2, 1912 Morrow Dec. 23, 1913 5 Norton July 20, 1915 Jacquelin May 27, 1924 Schieferstein Dec. 1, 1925 Lemont July 9, 1929 Schieferstein et al. Apr. 9, 1935 l0 Symons July 16, 1935 6 Blackburn May 23, 1939 Parks July 23, 1940 Pollitz Mar. 2, 1943 Wolf Nov. 16, 1943 Rapp June 19, 1945 Elliott Apr. 9, 1946 Carrier, Jr., et al Mar. 3, 1953 FOREIGN PATENTS Great Britain of 1901

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