Abstract:
An acoustically enclosed apparatus for shaking out sand-cores from metal castings. A plurality of percussive shakeout stations are spaced around the circumference of a turntable. The stations are separated one from the other and from their surroundings by an acoustical enclosure which rotates with the turntable and within a stationary enclosure. The castings are loaded and unloaded through outwardly facing access openings in the rotatable enclosure as they become registered with an access port in the stationary enclosure. Shaking out is effected while the access openings are out of registry with the access port. The sand collector beneath the stations attenuates the sound emitted from beneath the station.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to foundry apparatus and more particularly to apparatus for shaking sand-cores out of metal castings. Such cores are typically removed by imparting sufficient vibration to the casting to disintegrate the core and shake the loose sand from the internal intricacies of the casting. Chipping hammers, or the like, have been particularly effective for this purpose, and involves nothing more than clamping the casting to the tool end of the hammer and rapidly striking the other end of the tool with a reciprocating piston-like hammer. One of the disadvantages of using such tools, however, is the noise that it generates. Accordingly, a variety of sound cabinets have been developed for reducing this noise during the shaking out operation. Use of such cabinets, however, has dramatically slowed down the rate at which castings can be decored, primarily as a result of the lost motion required by the operator in just opening and closing the cabinets alone. 
     It is therefore an object of the present invention to provide a high production rate apparatus for shaking out sand-cores at relatively comfortable noise levels of less than about 90 dBA and with a minimum of lost operator motion. This and other objects and advantages of the present invention will become more readily apparent from the detailed description thereof which follows. 
     BRIEF DESCRIPTION OF THE INVENTION 
     In accordance with the present invention, a plurality of work stations are spaced apart around the circumference of a turntable and encased within an acoustical enclosure which is adapted to rotate with the turntable for the relative silent decoring of castings while they rotate between a load and unload station. The rotatable enclosure includes sound absorbing partitions separating the several stations one from the other, but provides an access opening for each station facing outwardly of the turntable for loading and unloading castings. Each work station includes an appropriate clamp for holding the casting in place and a percussive or impact-type tool (e.g., chipping hammer) for shaking out the core sand. A stationary acoustical enclosure surrounds the turntable and rotatable enclosure and is in sliding sound-sealing engagement therewith at all major joints between them to contain the sound generated as much as possible to each station. Elastomeric (e.g., polyurethane) flaps provide convenient long-wearing effective seals at these joints. The stationary enclosure has an access port at the operator&#39;s station for loading and unloading castings when aligned with the access opening of each station. A sand trap is provided beneath the stations for collecting falling sand and sealing off the undersides of the stations against sound emanations therefrom. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention may be better understood in conjunction with the following detailed description of certain preferred embodiments thereof in which: 
     FIG. 1 is a partially sectioned, side elevational view along the diameter of the turntable of an eight station shakeout apparatus constructed according to the present invention. 
     FIG. 2 is essentially a sectioned, plan view of the direction 2--2 of FIG. 1 (i.e., the shakeout means and the supports therefor have been removed from the load/unload station merely to show in-plan the sand chute and trough). 
     FIG. 3 is a section in the direction 3--3 of FIG. 2 and depicts the sand removal site at the load/unload station. 
     FIG. 4 is a partially sectioned, side elevational view along the diameter of the turntable of another embodiment of apparatus constructed according to the present invention and illustrating an improved sand-seal structure therefor. 
     FIG. 5 is a partial sectioned view in the direction 5--5 of FIG. 4. 
     FIG. 6 is a partial sectioned view in the direction 6--6 of FIG. 4. 
    
    
     In the figures, the shakeout of the present invention has an open supporting substructure including a plurality of radially extending girders 2 joined at the ends by a channel 3 and held above the floor by legs 4. A center shaft 6 is fixedly held to the support in an appropriate pedestal 8. A turntable 10 rotates above the shaft 6 on bearings 12. Struts 14 reinforce the center of the turntable 10 and distribute its load between the bearings 12. The turntable 10 itself comprises a number of radially extending girders 16 encompassed by and welded to a channel 17 at the periphery thereof. Cross members 20 support the shakeout means 22 between the girders 16 at each station and permit the sand from the casting 26 to fall freely therebetween into the sand-seal trap beneath, which will be discussed in more detail hereinafter. 
     Each work station includes a shakeout means 22 which itself comprises an air bag or bladder-type clamp 24 for clamping the casting 26 [shown in phantom in the unclamped (right) and clamped (left) positions] against the tool head 28 of a pneumatic chipping hammer 30 held in place by bracket 32. A rest 34 permits quick accurate placement of the casting in the clamping fixture by simply leaning the casting 26 backwards between the air bag clamp 24 and the tool head 28 as illustrated in the station on the right side of FIG. 1. The casting 26 here illustrated is shown with the casting runners 27 still attached. Upon actuation of the clamp 24, the lower runner 27 is forced into engagement with the tool head 28 as illustrated in the station on the left side of FIG. 1 and is held in this position during decoring. Elastomeric shock absorbing cushions 36 support the shakeout means 22 on the cross members 20. 
     An acoustical enclosure 38 for absorbing the sound generated by each shakeout means 22 is carried by the turntable 10 and adapted to rotate therewith. The rotatable acoustical enclosure 38 includes a back wall 40 supported by the turntable cross members 37, side walls or partitions 42 supported by the girders 16 and a top 44 integral with the back 40 and side walls 42. A removable sound-absorbing cover 43 closes off the center of the apparatus. An outwardly facing access opening 46 is provided for loading and unloading castings 26. A stationary acoustical enclosure 48 encircles the rotary enclosure 38 and is secured to the channel 3 which joins the ends of the girders 2 together. An access port 88 (see FIG. 2) is provided in the stationary enclosure 48 through which the operator can load and unload castings 26 when the access openings 46 to each of the stations registers therewith. 
     Any acceptable sound-absorbing material is useful with the acoustical enclosures 38 and 48. Preferably, the stationary acoustical enclosures are a laminate of several sound-absorbing materials. The stationary enclosure, for example, preferably includes a perforated metal sheet 50 (i.e., about 1/8&#34; thick) on the inside followed by about 4&#34; of fiberglass insulation 52 (i.e., vinyl covered Owens Corning type 703) and finally a thin layer 54 (i.e., about 1/8&#34; thick) of a lead-filled, sound-absorbing sheet material (i.e., Goodyear Acousta Sheet #200) glued to a steel shell 56 (i.e., about 1/8&#34; thick). Similarly, the rotatable enclosure 38 is preferably formed from about 3&#34; of fiberglass 58 (i.e., Type 703), 1/8 sheets 59 of Acousta Sheet #200 and held in place by an expanded metal grid work 60. Sheet metal panels 62 between the layers of sound-absorbing material in the walls/partitions 42 provide structural support for the walls 42 and top 44. 
     To prevent noise leakage around the periphery of the access openings 46, the distal ends 41 of the partitions 42 are provided with elastomeric flaps 64 appropriately affixed (i.e., as by sheet metal screws 65) to the trailing sides thereof so as to flex and seal against the perforated seal inner liner 50 of the stationary enclosure 48. Similarly, elastomeric sound-sealing flaps 66 and 68 are affixed to the channel 16 and top of enclosure 48, respectively as shown in FIG. 1. In the particular embodiment illustrated, the upper annular seal 68 rides against the outer peripheral surface 70 of the rotary enclosure top 44. It is to be appreciated, however, that the acoustical top could just as well be integral with the stationary enclosure like a stationary hood. Under that circumstance, the sealing flaps would be affixed to the upper edges of the partitions 42 in much the same way as they are affixed to the distal ends 41. 
     A sand and sound trap is provided beneath each station 22 and includes a downwardly sloping chute 72 having an opening 74 at the bottom thereof. In the particular embodiment shown, the opening 74 is at the bottom of a tubular downcomer 76. The upper end of the downcomer 76 extends somewhat above the bottom edge of the chute 72 to form a slight dam 78 and cause the sand 82 to backup on the surface of the chute 72. Sand falling from the castings 26 is channeled to the opening 74 by the chute 72 for ultimate discharge into an annular trough 80 which tracks the path of the openings 74 in their circuit around the shaft 6. Trough 80 is filled with a bed of sand 86 to a level above the opening 74 such that the downcomer 76 drags in the sand bed 86 and the sand effectively seals off opening 74. Hence, the chute 72, sand-sealed opening 74 and sand-filled trough 80 combine to attentuate any sound emanating from the underside of the stations. The trough 80 is provided with a discharge opening 90 (see FIGS. 2 and 3) located at the load/unload station at the access port 88. Here sand accumulated in the trough 80 and pushed ahead of the tube 76 as it rotates is discharged into any appropriate collector 92 for removal from the area. FIG. 2 has been drawn to delete the detail of the shakeout means 22, the supporting cross members 20 and the chute 72 so as to better show the relationship of the discharge opening 90 in trough 80 to the opening 74 in the chute 72. As the shakeout means 22 is inoperative at the loading/unloading station adjacent the access port 88, disruption of the sand-sealing opening 74 thereat does not create a noise problem for the operator. 
     The embodiment of the apparatus shown in FIGS. 4-6 illustrates a preferred sand trap which has the capability of automatically discharging any solid debris, such as broken runners R, or the like, which might fall through the chute 72 and become jammed in a trough 80. Moreover, with this design, an operator can easily and unobstructedly reach up under the work stations to manually clear them of fallen debris if that is necessary. The trough 80 of the embodiment of FIGS. 1-3 is replaced with an annular tray 94. The tray 94 has a bottom shelf portion 96 and an upstanding rim 98 extending upwardly from the shelf 96 to a level above the discharge opening 100 at the bottom of the chute 102. The shelf portion 96 of the tray 94 extends from the rim 98 inwardly towards the shaft 6 such that the inside edge is sufficiently inboard of the opening 100 in the chute 102 that the bed of sand 104 beneath the chute 102 will still seal-off the opening 100 without the need for an inner rim such as was required to form the trough 80 of the FIGS. 1-3 embodiment. The inner edge 105 defines a large opening 106 in the center of the tray 94. This opening 106 has been found to be extremely advantageous in reducing machine down-time. In this regard, it permits the operator to easily reach up through the opening 106 into the tray 94 for removing any debris (e.g., broken runners R or the like) that might fall into the tray 94 through the opening 100 and which would otherwise tend to become wedged and jam the apparatus if a closed sided trough 80 were used (i.e., FIGS. 1-3). Moreover, without an inner rim such as is required by the trough 80 of FIGS. 1-3, the tray 94 tends to be automatically self-cleaning in that much of the debris is actually pushed out of the sand bed 104 through the opening 106 by the bottom of the chute 102 as it advances through the bed. A secondary tray, chute or the like 108 is provided beneath the opening 106 to collect any debris or sand which might fall through the opening 106. As with the embodiment of FIGS. 1-3, sand is removed from the tray 94 principally through a discharge opening (i.e., like 90 of FIG. 1) in the shelf 96 at the operator&#39;s station. The elongated opening 100 (see FIG. 5) in the chute 102 more readily passes broken runners, parts and other debris than does the smaller opening 90 illustrated in FIG. 1 
     The turntable 10 and rotatable, acoustical enclosure 38 are preferably driven about the shaft 6 by pneumatically actuated friction drive means 110 which comprises essentially a rubber wheel 112 and a speed reduced motor 114. Drive means 110 is enclosed in its own removable acoustical housing (not shown) to further contain the noise within the stationary enclosure 48. Obviously the turntable 10 could be rigidly affixed to the shaft 6 and the shaft driven as by gears, chain and sprocket or the like. 
     In operation, a single operator is positioned at the access port 88 in the stationary enclosure 48. By means of manually depressible buttons (i.e., one for each hand) adjacent to but clear of the access port 88, the operator causes the turntable to index 1/8 turn (i.e., for an eight station unit) to sequentially register the access openings 46 in the rotatable enclosure 38 with the access port 88 in the stationary enclosure 48. He then removes the decored casting 26, replaces it with a core-filled casting 26 and indexes the turntable again. As the newly loaded shakeout means 22 leaves the access port 88 and moves within the stationary enclosure 48, a limit switch (not shown) is tripped to commence the shakeout operation. Shakeout may continue for the entire time the station 22 is in transit from the access port 88 and back again but is normally controlled by a timer (not shown) triggered by the starting limit switch to keep the actual decoring operation to a minimum. Regardless, a second limit switch (not shown) is provided on the turntable 10 to insure that, whether timed or not, the shakeout operation is discontinued just prior to the decoring station&#39;s entering the operator&#39;s station at the access port 88. Hence, all decoring is performed within the stationary enclosure 48 and the bulk of the noise generated is confined therein. Lastly, appropriate safety switches are provided at the access port 88 to stop or brake the turntable 10 and enclosure 38 in the event an operator&#39;s limb or obstacle remain in the access port while the enclosure 38 is rotating. 
     In one example of an eight station apparatus made as above, the noise emanating from the access port 88 varied between about 81 dBA to about 85 dBA, whereas the noise generated by a single unenclosed shakeout means 22 was about 135 dBA. This example was based on the use of Ingersol Rand size 2A chipping hammers removing cores from V-8 engine intake manifold castings weighing about 31 lbs. That particular eight station apparatus had a production capability of about 300 castings per hour at the 81-85 dBA level. 
     While the invention has been disclosed primarily in terms of specific embodiments, it is to be understood that numerous variations thereof are possible within the intent of applicant&#39;s invention. In this regard, obviously two or more load/unload sites could be provided (i.e., 180° apart) if decoring can be effected between these sites and control coordination can be safely effected. Moreover, any of a number of acceptable acoustic materials and combinations thereof may well be substituted for the particular materials disclosed herein. Lastly, the turntable could be made to rotate slowly enough that loading/unloading could be effected without stopping the turntable. Accordingly, the invention then is to be considered limited only to the extent set forth in the claims which follow and not otherwise.