Patent Publication Number: US-9421664-B1

Title: Table top rock tumbler

Description:
FIELD OF INVENTION 
     The invention relates to rock tumblers that are used to polish stones. 
     BACKGROUND OF THE INVENTION 
     A common procedure in the abrading, polishing and finishing of irregularly shaped objects, for example, stones and minerals in lapidary practice, both professional and amateur, is to tumble the objects with a suitable abrasive composition in the barrel of a tumbling apparatus. U.S. Pat. No. 4,045,918 to Freedman discloses an abrading and polishing tumbler apparatus having one or two barrels in which in which the tumbler barrel is concurrently rotated and rocked and includes an internally ribbed barrel having a separable closure cap at one end. This apparatus has a fairly complex drive mechanism and is noisy when being operated as the stones in the tumbler clang against the side wall of the tumbler as the tumbler is rotated. 
     U.S. Pat. No. 6,254,466 B1 discloses a tumbler for abrading small parts and rocks in which the objects are placed into a cylindrical drum or barrel along with a grinding medium and liquid. This patent teaches that the barrel can be made of rubber. But, like Freedman this patent also does not mention noise as being a problem, perhaps because the rocks are in a liquid as they are being ground. 
     Rock tumblers have been made is several sizes ranging from those having barrels that are several meters in diameter for industrial use to table top tumblers which are about 10 to 15 centimeters in diameter. Smaller rock tumblers are available in some toy stores and craft stores for use by children. These products are often used indoors where noise from rocks clanging in the tumbler can be annoying. Consequently, there is a need for a very quiet rock tumbler that can be used by children indoors. 
     SUMMARY OF THE INVENTION 
     I provide an ultra-quiet rock tumbler which has a barrel assembly supported on two uprights extending from a base. The barrel assembly has an inner barrel with a removable top, that fits into a middle barrel having a removable top, that fits into an outer barrel having a removable top. Energy absorbing material, preferably polyurethane foam, surrounds both the inner barrel and the middle barrel. The energy absorbing material creates a snug fit of the inner barrel within the middle barrel and of the middle barrel within the outer barrel. Rocks and minerals are placed in the inner barrel with a grinding powder material such as sand and preferably a small amount of water. The user puts the top on the inner barrel, places the inner barrel within the middle barrel, places the top on the middle barrel, places the middle barrel in the outer barrel and puts the cover on the outer barrel. Preferably the foam has a thickness which results in at least a portion of the foam being compressed between adjacent sidewalls of the inner barrel and middle barrel and of the middle barrel and outer barrel. This assembly is then placed on the uprights. A motor on the base engages and turns the barrel assembly to polish the stones. This arrangement enables the foam material to absorb the sound and vibration of the rocks striking the wall of the inner barrel such that the rock tumbler is much quieter than a conventional rock tumbler having a single barrel or tumbler. 
     Preferably the outer barrel side wall, the middle barrel side wall and the inner barrel side wall each define a polygon. The polygon defined by the middle barrel side wall is the same polygon shape as the polygon defined by the outer barrel side wall and has a smaller diameter than the polygon defined by the outer barrel side wall. The polygon defined by the inner barrel side wall is the same polygon shape as the polygon defined by the middle barrel side wall and has a smaller diameter than the polygon defined by the middle barrel side wall. This arrangement prevents the inner barrel from rotating relative to the middle barrel and prevents the middle barrel form rotating relative to the outer barrel. 
     The barrel assembly may be rotated by a motor on the base or in one of the uprights. In a preferred embodiment the motor has an axle that is turned when the motor is activated and there is a roller on the axle. The outer barrel side wall has a circular portion that is engaged by the roller such that when the motor is activated the turning roller will cause the barrel assembly to rotate. 
     Other features and advantages of the present rock tumbler will become apparent from a description of certain present preferred embodiments shown in the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of a present preferred embodiment of the rock tumbler. 
         FIG. 2  is a rear perspective view of the embodiment of the rock tumbler shown in  FIG. 1 . 
         FIG. 3  is a front view embodiment of the rock tumbler shown in  FIGS. 1 and 2 . 
         FIG. 4  is a sectional view taken along the line IV-IV in  FIG. 3 . 
         FIG. 5  is partially exploded end view of the barrel assembly in the embodiment of the rock tumbler shown in  FIGS. 1 through 4 . 
         FIG. 6  is a view taken along the line VI-VI in  FIG. 5 . 
         FIG. 7  is a perspective view of the top for the inner barrel in the embodiment of the rock tumbler shown in  FIGS. 1 through 6 . 
         FIG. 8  is a perspective view of the top for the middle barrel in the embodiment of the rock tumbler shown in  FIGS. 1 through 6 . 
         FIG. 9  is a perspective view of the top for the inner barrel in the embodiment of the rock tumbler shown in  FIGS. 1 through 6 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1 through 6  a rock tumbler  1  has a barrel support  2  and a barrel assembly  10 . The barrel support has a base  3 , a first upright  4  attached to the base and a second upright  5  spaced apart from the first upright  4  and attached to the base  3 . There is a first axle seat  6  on the first upright  4  and a second axle seat  7  on the second upright  5 . The barrel assembly  10  has an inner barrel  11  with a removable top  12  that fits into a middle barrel  20  which has a removable top  22 . The middle barrel  20  fits into an outer barrel  30  having a removable top  32 . As can be seen most clearly in  FIGS. 4 and 6  energy absorbing material  41  is provided on the inside surface of the base  34  of the outer barrel, on the inside surface of the side wall  35  of the outer barrel and on the inside surface  33  of the top  32  of the outer barrel. This energy absorbing material surrounds the middle barrel when the middle barrel is placed in the outer barrel and the top is placed on the outer barrel. Energy absorbing material  42  is provided on the inside surface of the base  24  of the middle barrel, on the inside surface of the side wall  25  of the middle barrel and on the inside surface  23  of the top  22  of the middle barrel. This energy absorbing material surrounds the inner barrel when the inner barrel is placed in the middle barrel and the top is placed on the middle barrel. The energy absorbing material preferably is a foam material made of polyurethane or polyvinyl chloride. 
     Preferably the side wall of the outer barrel has a circular portion  37  at one end and a larger portion  38  which defines a polygon shape. The polygon in the present preferred embodiment is a hexagon, but the shape could be another polygon such as a square or an octagon. The middle barrel side wall also defines a hexagon shape, but that hexagon has a smaller diameter so the middle barrel fits into the outer barrel. Similarly, the side wall of the inner barrel also defines a hexagon, that hexagon having a smaller diameter than the hexagon defined by the sidewall of the middle barrel. The polygon configuration prevents the inner barrel from rotating relative to the middle barrel and prevents the middle barrel from rotating relative to the outer barrel. A circular rim  14  having threads  15  is provided on the side wall  13  of the inner barrel at the mouth of the inner barrel  10 . The inner barrel top  12  is circular and has a rim  16  with threads  17  that engaged threads  15  on the rim  14  of the inner barrel side wall. This screw type connection provides a tighter seal than the friction fit tops used for the middle barrel and the outer barrel. The tighter seal is needed because the inner barrel may contain water or other liquid with grinding powder and the stones to be polished. 
     Referring to  FIGS. 4 and 5  a first axle  31  is attached to the outer surface of the base of the outer barrel. That axle  31  is seated on the first axle seat  6  of the first upright  4  when the barrel assembly is held on the support  2 . A second axle  39  is attached to the outer surface of the top  32  of the outer barrel. That axle  32  is seated on the second axle seat  7  on the second upright  5  when the barrel assembly is held on the support  2 . Preferably the second axle seat  7  is higher than the first axle seat  6  relative to the base  3  so that the barrel assembly  10  is tilted relative to the base. The first axle  31  and the first axle seat  6  are larger in diameter than the second axle  39  and the second axle seat  7  so that the barrel assembly can only be placed on the support in an orientation where the base  34  of the outer barrel is lower than the top  32  of the outer barrel  30  relative to the base  3 . 
     The barrel assembly is rotated by a barrel mover such as motor  50  having an axle  52  with a roller or wheel  54 . A tire  55  may be provided on the wheel, the tire being made of a softer material such as rubber than the wheel. When the barrel assembly  10  is held on the uprights  4 ,  5  the roller or wheel  54  engages the circular portion  37  of the outer barrel side wall. A switch  56  is provided on the first upright  4  to enable the user to turn the motor on and off. When the motor is operating the roller  54  will turn causing the barrel assembly  10  to rotate around an axis (not shown) that extends from the first axle  31  to the second axle  39 . A receptacle  58  is provided on the back of the first upright for an AC/DC adapter which provides power to the motor. Alternatively the motor can be battery powered. Rather than provide a wheel to turn the barrel assembly the motor can be positioned and configured to drive either axle  31  or  39  on the outer barrel. The motor may be connected to the axle directly or by a belt or gears. 
     The present preferred embodiment of the rock tumbler  1  is intended to be used on a table top or bench. It has a length of 270 mm, a width of 143.5 mm and a height of 227.2 mm. The outer barrel has a diameter of 144 mm between opposite side wall segments and a height of 175.8 mm between the end of the first axle  31  and the end of the second axle  39 . The middle barrel has a height of 122 mm and a diameter of 127.7 mm between opposite side wall segments. The inner barrel has a height of 108.8 mm and a diameter of 112.9 mm between opposite side wall segments. 
     The inner barrel, middle barrel, outer barrel and their tops are preferably made of a plastic such as polycarbonate. The base and uprights of the barrel support as well as the wheel that is driven by the motor can be made of the same plastic material. 
     To operate the rock tumbler the user removes top  12  from the inner barrel  11 . At that time the inner barrel will usually have been separated from the middle barrel. Then the user places the stones to be polished along with a grit powder, such as sand or other abrasive powder, into the inner barrel. A small amount of water can also be added. Next the user tightly secures the inner barrel top  12  onto the rim  14  of the inner barrel. Then the user places the inner barrel into the middle barrel and puts the top on the middle barrel. Finally the user places the middle barrel into the outer barrel and puts the top on the outer barrel. The middle barrel may have been placed in the outer barrel before the user places the inner barrel into the middle barrel. The outer barrel  30  containing the middle barrel and the inner barrel is then placed on the barrel support so that the circular portion  37  of the outer barrel engages the roller or wheel  54  that is turned by the motor. Next the user turns on the motor causing the outer barrel  30  to rotate. The motor is allowed to run a sufficient time for the abrasive powder to polish the stones. This may be several hours. Then the inner barrel is removed and opened to retrieve the polished stones. Preferably two or more grades of abrasive powder including a coarse grind power and a fine grind power are provided. The tumbling process just described is first conducted using the coarse powder and then repeated one or more times using successively finer grades of abrasive powder. The rock tumbler may be sold as part of a jewelry making kit that includes rings, earrings, keychains, and other types of jewelry or jewelry components on which the polished stones can be mounted. An adhesive for mounting the polished stones on jewelry components may also be included in the kit. 
     Although one could make a rock tumbler having an inner barrel surrounded by an energy absorbing material in an outer barrel, the use of only two barrels is noisier that the three barrel rock tumbler described here. In a commercial embodiment of the rock tumbler shown in the drawings one could hardly hear the rocks being tumbled over the hum of the motor. One could also make a similar rock tumbler having three or more barrels, each surrounded by an energy absorbing material and being within an outer barrel. But the use of three or more barrels makes the rock tumbler more expensive and not much quieter than the rock tumbler shown in the drawings. 
     Although certain present preferred embodiments of the rock tumbler have been described and illustrated it should be understood that the invention is not limited thereto and may be variously embodied within the scope of the following claims.