Abstract:
A metal chip and shaving compactor includes a compaction housing ( 80 ) having a compaction chamber ( 82 ) with a compaction piston ( 64 ) extending into the chamber Metal chips and shavings are admitted to the chamber through an inlet opening ( 84 ). Separate ball screw drive mechanisms ( 50  and  92, 94 ) move the piston and the compaction housing along an axis ( 58 ) between positions where each is either proximal or distal from the base ( 30 ) Independent operation of the ball screw drive mechanisms permits metal chip and shaving to be admitted into the chamber, compacted and subsequently discharged as compacted puck-like pellets Computer controls ( 162 ) operate the ball screw drive mechanisms and sense ( 182, 184, 186 ) operation of the compactor based on rotational positions of the screw drives of the ball screw drive mechanisms.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to metal compacting apparatus, and particularly to metal compactors that compact incompressible metal shavings, chips and the like into easily transportable pellets, and remove cutting fluids from the metal, so that the cutting fluid and metal may be separately recycled.  
           [0002]    U.S. Pat. Nos. 5,391,069 granted Feb. 21, 1995, 5,542,348 granted Aug. 6, 1996 and 5,664,492 granted Sep. 9, 1997, all assigned to the same Assignee as the present invention, describe a compactor that compacts metal chips and shavings into puck-like pellets that are free of interstices. Cutting fluid is extruded from the metal during the compacting process so that the resulting pellets are clean of cutting fluids. The compactor described in the aforementioned patents is commercially available as the PUCKMASTER® compactor, and is marketed primarily to machine shops and other metal-working operations where metal is processed by cutting, grinding and other processes. These metal-working processes use cutting fluids, such as cutting oil, to dissipate heat generated during the cutting or grinding process. The metal-working process results in scrap metal chips, shavings and the like that is laden with cutting oil. Machine shop operators use the PUCKMASTER compactor to recover nearly all of the cutting oil used in the metal-working process, as well as to compact the scrap metal into puck-like pellets that are free of cutting fluids. The machine shop can re-use the recovered cutting oils in subsequent metal-working operations, and can sell the metal pellets to reclamation foundries to recover raw metal material from the scraps. The foundries pay significantly higher prices for the pellets than for oil-laden metal chips and shavings because the cost of reclaiming the metal from the pellets is greatly reduced over that of reclaiming metal from oil-laden metal chips and shavings. Moreover, the cost of transportation of the pellets is significantly less than the cost of transporting the chips and shavings. Thus, the PUCKMASTER compactor provides savings to the machine shops in the form of (a) lower transportation costs for shipping the scrap metal to reclamation foundries, (b) higher prices received for the scrap metal due to its cleanliness, and (c) reduced costs in cutting fluids due to reclamation of the cutting fluid from the chips and shavings.  
           [0003]    The PUCKMASTER compactor employs a compaction chamber into which the metal chips and shavings are introduced. A hydraulically-driven piston, capable of achieving pressures of 20,000 to 40,000 pounds per square inch (psi), compacts the metal chips and shavings. The high pressure extrudes cutting fluid from the metal chips and shavings and compacts the chips and shavings into a pellet that is substantially free of interstices. The pellets have a generally cylindrical shape, with a diameter between 2.5 and 4.5 inches (6.3 and 11.4 cm) depending on the diameter of the compaction chamber, and a thickness between 1 and 2 inches (2.5 and 5.1 cm) depending on the volume of chips and shavings in the compaction chamber during compaction. The pellets are known in the trade as “pucks” due to their vague resemblance to hockey pucks.  
           [0004]    The PUCKMASTER compactors require high technical skill in several disciplines to service or refurbish the machine. More particularly, the PUCKMASTER compactors employ hydraulic drive mechanisms (hydraulic circuits, regulators, valves, pumps, and the like). While the hydraulic drive mechanisms of the prior compactors operated quite well in the field, technicians skilled in hydraulics were required to repair or refurbish those machines. Moreover, the PUCKMASTER compactors also employ computer control technology that operate the hydraulic valves and electric sensors, and employ electric power technology to operate the hydraulic pumps and computer. It was not always possible to find technicians skilled in all three disciplines of hydraulic, computer and electric power. Consequently, it was often necessary to send a team of as many as three technicians to customer sites for on-site repair and refurbishment.  
           [0005]    Recent developments in ball-screw drive technology have made it feasible to achieve the operating pressures necessary to compact the metal chips and shavings as in the PUCKMASTER compactor. Moreover, use of electric ball-screw drive systems renders the compactor more economic to manufacture and assemble, and more economical to repair and refurbish. Therefore, the present invention is directed to a metal compactor employing a ball-screw drive.  
         SUMMARY OF THE INVENTION  
         [0006]    A compactor according to a preferred embodiment of the present invention is adapted to compact fluid-laden incompressible metal chips and shavings into puck-like pellets for separate reclamation of the metal and fluid. The compactor comprises a frame having a base. A compaction housing defines a compaction chamber. A compaction piston extends through an end of the compaction housing and has a working surface in the compaction chamber. An inlet in the wall of the compaction housing allows metal chips and shavings to be admitted into the compaction chamber. A ball screw drive mechanism has a motor supported by the frame to move the compaction housing along an axis between a first position where an open end of the compaction chamber is distal from the base and a second position where the open end is closed by the base. A second ball screw drive mechanism, has a motor supported by the frame to move the compaction piston along the axis between a first position where the working surface of the compaction piston is distal from the base and a second position where the working surface is proximal to the base.  
           [0007]    The compactor operates such that when the working surface of the piston is distal from the base and the compaction chamber is closed by the base, metal chips and shavings may be admitted through the inlet opening into the compaction chamber. When the piston is moved to its position proximal the base, the piston closes the inlet and compacts the metal in the chamber against the base into a puck-like pellet. When the compaction housing is thereafter moved to its position distal from the base, the piston discharges the pellet from the compaction chamber. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a partly cutaway perspective view of a metal compactor according to the presently preferred embodiment of the present invention.  
         [0009]    [0009]FIG. 2 is a top view of the metal compactor illustrated in FIG. 1 with the compaction piston in a load position.  
         [0010]    [0010]FIG. 3 is a top view of the metal compactor as in FIG. 2 with the compaction piston in a compaction position. FIG. 4 is a partly cutaway frontal view of the metal compactor.  
         [0011]    [0011]FIGS. 5 and 6 are top views of the right end portion of the metal compactor as illustrated in FIG. 2 with the compaction housing in compaction and discharge positions, respectively.  
         [0012]    [0012]FIG. 7 is a partly cutaway perspective view of the metal compactor illustrating the feed mechanism and connection to an inlet hopper.  
         [0013]    [0013]FIG. 8 is a block diagram of the control system for the metal compactor illustrated in FIGS.  1 - 7 .  
         [0014]    [0014]FIG. 9 is a flow diagram of the process of operation of the metal compactor to compact metal chips and shavings into puck-like pellets. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]    FIGS.  1 - 6  illustrate a metal compactor  20  having a support structure frame  22  consisting of side members  24  and  26 , end member  28 , base member  30 , cross beams  32 ,  34  across the top of compactor  20 , and cross beams  36  and  38  across the bottom of compactor  20 . Frame  22  further includes a brace  40  mounted by straps  42  and  44  to side member  26 . Frame  22  is preferably constructed of steel or other rigid metal, with the members and beams bolted together to form rigid frame  22 . A skin or metal cover (not shown) is fastened over frame  22  to enclose the mechanisms and parts supported within the frame. As shown particularly in FIG. 7, frame  22  is supported by legs  46 .  
         [0016]    Ball screw drive mechanism  50  comprises an electric drive motor  52 , screw drive  54  and coupling  56 . Coupling  56  is coupled to the threads of screw drive  54  by a ball and race assembly well known in the art so that coupling  56  moves axially along axis  58  as screw drive  54  is rotated by motor  52 . Motor  52  is reversible to rotate screw drive  54  in opposite directions about axis  58  to move coupling  56  to the right or left along axis  58  depending on the direction of rotation of screw drive  56 . Member  60  couples coupling  56  to piston housing  62 , which in turn is coupled to piston  64 . As shown particularly in FIG. 4, member  60  is journaled by journals  66  and  68  to shafts  70  and  72 . The ends of shafts  70  and  72  are mounted to respective cross beams  32 ,  34 ,  36  and  38  of frame  22  to extend parallel to axis  58 . Hence, rods  70  and  72  serve as a guide to assure correct movement of piston  64 .  
         [0017]    Compaction housing  80  forms an internal compaction chamber  82  having an opening  84  through a wall of housing  80  forming an inlet for metal chips and shavings to be compacted. Compaction housing  80  is open at opposite ends along axis  58  and is mounted to frame  86  which in turn is coupled by a ball and race assembly to screw drives  88  and  90  of ball screw drive actuators  92  and  94 . Ball screw actuator  92  includes an electric motor  96  mounted to frame  98 , which in turn is mounted to wall  24  of frame  22 . Motor  96  is operated to rotate screw drive  88 . Similarly, ball screw actuator  94  includes electric motor  100  mounted to frame  102 , which in turn is mounted to wall  26  of frame  22 , to rotate screw drive  90 . Ball screw actuators  92  and  94  are positioned parallel to axis  58  so that operation of motors  96  and  100  moves frame  86  axially, thereby moving compaction housing  80  along axis  58 . Ball screw actuators  92  and  94  operate in unison to move housing  80  to the right or left along axis  58 . Guide rod  104  is mounted between frame  98  and frame  106 , and guide rod  108  is mounted between frame  102  and frame  106 . Guide rods  104  and  108  are journaled to frame  86  to guide movement of housing  80 . Frame  106  includes an aperture  110  through which housing  80  passes.  
         [0018]    In preferred forms of the invention, motor  52  is a model MPM190 eight-inch electric motor and motors  96  and  100  are model MPM114 four-inch electric motors, each commercially available from Custom Servo Motors, Inc. of New Ulm, Minn., USA. One feature of motors  52 ,  96  and  100  is the inclusion of feedback lines that provide sine and cosine signals representative of the rotational position of the motor shafts of the respective motors. These signals are used for positional data and controlling operation of the compactor, as will be explained in connection with FIG. 8.  
         [0019]    As shown particularly in FIGS. 5 and 6, piston  64  may include a replaceable piston member  146  that extends through the open end of compaction chamber  82 , with a working surface  143  that engages and compacts the metal chips and shavings in the compaction chamber during operation. A coupling  148  couples member  146  to piston  64  to permit replacement of piston member  146 . This feature is particularly advantageous because the compaction process is typically performed applying a pressure on the metal chips and shavings up to about 50,000 pounds per square inch (psi) (about 3,500 Kg/cm 2 ). The piston is susceptible of wear, and even failure, when subjected to numerous cycles of such pressure. Consequently, a worn or failed piston member is easily replaced in the compactor described herein.  
         [0020]    Base member  30  includes a raised pedestal  112  of a size and shape to be received through the lower opening of compaction chamber  82 . A small clearance between pedestal  112  and housing  80  permits housing  80  to move over pedestal  112 , and permits extruded cutting fluids to pass through the clearance from compaction chamber  82 . A clearance of about 0.020 inches (0.5 mm) is adequate to permit discharge of cutting fluids without allowing metal to escape from the compaction chamber. Fluids expelled from the compaction chamber drop by gravity to a recovery receptacle (not shown) below the compactor to permit extruded cutting fluid to be removed and recovered.  
         [0021]    [0021]FIG. 7 illustrates the details of feed mechanism  120  that feeds metal chips and shavings into compaction chamber  82  of compaction cylinder  80  from inlet hopper  122 . Feed mechanism  120  includes a first conduit  124  fastened by flange  126  to compaction cylinder  80  (FIG. 1). Conduit  124  communicates with chamber  82  through inlet  84 . A second conduit  128 , parallel to axis  58 , is mounted to conduit  124 . An elbow conduit  130  extends into the bottom of hopper  122  to receive metal chips and shavings from the hopper and is rigidly mounted to hopper  122 , such as by welding or the like to prevent leakage of fluid from hopper  122 . An auger (not shown) in hopper  122  is operated by a motor mounted to flange  132  to transport metal chips and shavings to elbow conduit  130 . Elbow conduit  130  supplies the metal chips and shavings to conduit  128 . Preferably, mounts  134  fasten hopper  122  to conduit  128  so that hopper  122  is supported by the conduit.  
         [0022]    Motor  136  is supported by one of legs  46  and includes a belt  137  coupled to ram  138  in conduit  128 . Ram  138  supplies the metal chips and shavings in conduit  128  to conduit  124 . Motor  140  includes a belt  141  to drive ram  142  in conduit  124  to transport metal chips and shavings in conduit  124  through inlet  84  into compaction chamber  82 . Hence, metal chips and shavings in hopper  122  enter conduit  130  and are transported by ram  138  to conduit  124  where they are forced by ram  142  through inlet  84  to the compaction chamber where they are compacted.  
         [0023]    During operation of the metal compactor, compaction cylinder  80  is moved horizontally along axis  58  by ball screw actuators  92  and  94 . During this movement, feed mechanism  120  also moves horizontally, as indicated by arrows  144 . Consequently, hopper  122  and conduits  124 ,  128  and  130  move with motion of cylinder  80 . In preferred embodiments, the maximum movement of cylinder  80  is about 4 inches (10 cm) so feed mechanism  122  moves the same distance.  
         [0024]    The operation of the metal compactor may best be explained starting with compaction cylinder  80  in its right-most position so the end of compaction chamber  82  is closed over pedestal  112 , and piston  64  in a withdrawn position (to the left in the drawings) so that piston  64  is free of inlet  84  of compaction cylinder  80  (FIG. 2) and the inlet is open. Ram  142  is operated to load metal chips and shavings into chamber  82  from conduit  124 . Ram  142  effectively delivers a load of metal chips and shavings to compaction chamber  82  and closes inlet  84  when the camber is loaded. Hence, when ram  142  reaches a design limit, the ram effectively closes inlet  84  to compaction chamber  82 .  
         [0025]    Ball screw actuator  50  is operated to move piston  64  along axis  58  (to the right in the drawings) to compact metal chips and shavings in the compaction chamber  82  between surface  143  of the piston and pedestal portion  112  of the base. During the initial portion of the compaction operation, the compaction pressure on the metal chips and shavings increases due to the movement of piston  64 . Additionally, when piston  64  is moved to a position closing inlet  84 , chips and shavings are prevented from being expelled back into conduit  124 . As the piston moves to a compacting position, between about 1 and 2 inches (2.5 and 5.1 cm) from pedestal  112 , the metal chips and shavings are compacted within chamber  82  into the puck-like pellets  150  (FIG. 6). The compaction position of piston  64  is established based on the size of the metal compactor and the type of metal being compacted. As described below, the design lower limit of piston  64  is programmed into microprocessor  162  (FIG. 8) controlling operation of the metal compactor and may be changed by the operator to accommodate various metals.  
         [0026]    During the compaction of the metal chips and shavings into pucks  150 , excess cutting fluid or oil is extruded from the interstices of the chips and shavings and forced out of compaction chamber  82  through the clearance between cylinder  80  and pedestal  112 . The extruded cutting fluid drains to a collection receptacle (not shown) below the compactor for re-use.  
         [0027]    When ball screw actuator  50  has moved piston  64  to its compaction position, the compaction process is completed and the metal in chamber  82  is completely compacted to form puck  144 . Additional metal chips and shavings are loaded into conduit  128 , and ram  138  transports the chips and shavings to conduit  124 .  
         [0028]    Ball screw actuators  92  and  94  are operated to withdraw or retract cylinder  80  to the left. Piston  64  remains in its right-most position so that as cylinder  80  is withdrawn, piston  64  forces the compacted puck  1150  from chamber  82 . Ball screw actuator  50  is then operated to withdraw or retract piston  64  to its left-most position (FIG. 6), and the finished puck  150  falls free from pedestal  112  to a collection bin (not shown) where it may be collected for eventual reclamation or recycling.  
         [0029]    Finally, ball screw actuators  92  and.  94  are operated to move cylinder  80  to its right-most position engaging pedestal  112 , and the process is repeated.  
         [0030]    [0030]FIG. 8 is a block circuit diagram of the electronic controls for operating the metal compactor illustrated in FIGS.  1 - 7 . Broadly, controller  160  selectively applies power to motors  52 ,  96  and  100 , which in turn provide position signals to microprocessor  162  to control operation of controller  160 . In addition, controller  160  operates the hopper auger motor coupled to flange  132  (FIG. 7) as well as rams  138  and  142 . Three-phase power, such as 450 volt, three-phase AC power, is supplied by source  164 , which may be an industrial power source supplied by a commercial power company. The three phases of the power source are applied to controller  160 . Step-down transformer  166  is coupled to two of the phases from source  164  to supply 120-volt single-phase AC power to microprocessor  162  and to analog-to-digital power supply  168 , which in turn supplies DC power to manual control  170 . Power relay  172  is coupled across the  110  volt supply from transformer  166  through normally open push-button switch  174  and normally closed push-button switch  176 . Relay  172  operates contacts  178  and  180  when energized. When push-button switch  174  is momentarily operated, relay  172  is energized to close contacts  178  and  180 . Closing of contacts  178  ensures that relay  172  remains energized during operation of the compactor. Closure of contacts  180  ensures delivery of power to motors  52 ,  96  and  100 . Shut-down of the compactor is achieved by operating push-button switch  176  to de-energize relay  172 , thereby opening contacts  178  and  180  and removing power from motors  52 ,  96  and  100 .  
         [0031]    As described above, motors  52 ,  96  and  100  provide signals via respective lines  182 ,  184  and  186  representative of the respective angular position of the shafts of each of the respective motors  52 ,  96  and  100 , and hence the angular position of ball screw drive threads  54 ,  88  and  90  of the associated ball screw actuator. The signals, which are representative of the sine and cosine functions of the angular position of the respective shafts, are input to microprocessor  162 . Microprocessor  162  is programmed to respond to sine/cosine signals on leads  182 ,  184  and  186  to control operation of motors  52 m  96  and  100  and rams  138  and  140 , based on the position of the respective ball screw actuators. Hence, the positions of piston  64  and compactor housing  80  are sensed by motors  52 ,  96  and  100  to control operation of the compactor as programmed by microprocessor  162 .  
         [0032]    Microprocessor  162  is programmed to operate controller  160  to selectively advance or retract piston  64  and compaction housing  80 , and to operate the respective ram  138  and  142  and the auger in hopper  122 . More particularly, as more fully described in connection with the flow chart of FIG. 9, the position feedback on line  182  represents the position of compaction pistion  64 . When piston  64  is moved to its retracted position, as sensed by the signal on line  182 , microprocessor  162  controls controller  160  to operate motors  96  and  100  to move compaction housing  80  to the compaction postion. When housing  80  reaches the compaction position closing the open end of the compaction chamber to pedestal  112 , as sensed by the signals on lines  184  and  186 , microprocessor  162  controls controller  160  to operate ram  138  to deliver metal chips and shavings to ram  142  and subsequently operate ram  142  to deliver metal chips and shavings to compaction the chamber while withdrawing or retracting ram  138 , and, after a programmed delay, to operate motor  52  to move compaction pistion  64  to the compaction postion to form the pucks. When piston  64  reaches the compaction position at a programmed distance from pedestal  112 , as sensed by the signals on line  182 , microprocessor  162  controls controller  160  to retract ram  142  and to to operate motors  96  and  100  to move compaction housing  80  to the retracted postion to release the pucks. When compaction housing  80  reaches the compaction position, as sensed by the signals on line  184  and  186 , microprocessor  162  controls controller  160  to operate motor  52  to move compaction piston  64  to its retracted postion.  
         [0033]    Manual control  170  permits manual initialization of the compactor as well as to independently operate the piston and compaction housing to their respective positions. Manual control  170  additionally allows programming the retracted position of ram  138  and the compaction position of piston  64  to permit different sized puck thicknesses for different metals being compacted.  
         [0034]    [0034]FIG. 9 is a flow chart illustrating the process performed by microprocessor  162 . At step  190 , the position of compaction housing  80  and piston  64  are initialized such that compaction housing  80  is in its closed position over at pedestal  112  and piston  64  is in its retracted position to allow a charge of metal chips and shavings to be input through inlet  84 . At step  192 , the initial or retracted position of ram  138  is established, based on the type of metal being compacted and the size of the pucks to be formed. At step  194 , the hopper auger is operated to deliver metal chips and shavings from hopper  122  to ram  138 . In some cases, it may be desirable to operate the auger continuously, even when ram  138  is in its delivery position and chips and shavings can not enter the ram. Otherwise, the hopper auger may be operated only when ram  138  is retracted to a position able to receive chips from the hopper. In either case, at step  196 , ram  138  is operated to deliver metal chips and shavings to ram  142  and ram  142  is operated at step  198  to delivery the metal chips and shavings to compaction chamber  82 . Also, ram  138  is retracted or withdrawn so as to receive an additional charge of chips from hopper  122 . The withdrawn position of ram  138  is sized, based on the metal being compacted and the size of the puck to be formed.  
         [0035]    The compaction process begins at step  200  with the operation of motor  52  to move piston  64  to the compaction position to form pucks  150  in compaction chamber  82  and against pedestal  112 . At the same time, ram  142  is withdrawn to receive metal chips and shavings from ram  138 . At step  202 , motors  96  and  100  are operated to retract compaction housing  80  forcing puck  150  from the housing compaction chamber. At this point, puck  150  is sandwiched between pedestal  112  and piston  64 . At step  204 , motor  52  is operated to retract piston  64  and allowing puck  150  to drop free to the receiving receptacle (not shown). At step  206 , motors  96  and  100  are operated to move compaction housing  80  back to its compaction position against pedestal  112 , and the process repeats, commencing at step  196 .  
         [0036]    The present invention thus provides a metal compaction apparatus for compacting metal chips and shavings into puck-like pellets for recycling, and for retrieving cutting fluids from the metal chips and shavings, also for recycling. In the preferred form of the invention, ball screw actuators are employed to independently move the compaction piston and compaction housing for operation. Feedback from the compaction motors allows precise sensing of the position of both the compaction piston and the compaction housing during operation to control the process. In addition, in the unlikely event that motors  96  and  100  become skewed, any mis-alignment of the motors is quickly sensed by the feedback to microprocessor  162  to allow controller  160  to correct the angular position of the motor shafts.  
         [0037]    Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.