Abstract:
A sheet cleaning apparatus having sets of cleaning rollers, wherein the rollers are integrated into a removable cartridge structure. Couplers are provided at roller shaft ends to connect to the roller drive. The cartridge is received in a slide carriage, permitting the cartridge to be readily removed from the apparatus by sliding the carriage out, and lifting the cartridge out from the slide carriage. With this arrangement, the down time for the sheet cleaning apparatus is minimized, since the sheet cleaning apparatus can be provided with two cartridges, and the cartridge needing maintenance can simply be quickly removed and replaced with a fresh cartridge. The production line can quickly be put back into operation, and the removed cartridge can be serviced off line for subsequent use.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation of application Ser. No. 09/162,078, filed Sep. 28, 1998, U.S. Pat. No. 5,989,358, in turn a continuation of application Ser. No. 08/722,857, filed Sep. 26, 1996, issued as U.S. Pat. No. 5,813,073. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to an improved apparatus for cleaning dust and other surface particulate contaminants from material in sheet form. 
     BACKGROUND OF THE INVENTION 
     This invention is an improvement to the sheet cleaning apparatus described in U.S. Pat. No. 5,349,714, the entire contents of which are incorporated herein by reference. These apparatus are typically arranged in a printed circuit board production line, with other, very expensive machines. When the sheet cleaning apparatus needs servicing, typically to clean the sheet cleaning rollers ( 52 ,  54 ,  56 ,  58 , shown e.g. in FIG.  8 ), the apparatus must be disassembled to remove the rollers, or the operator must clean the rollers in place. With either technique, considerable time is required for this maintenance procedure, idling not only the sheet cleaning apparatus but the other, very expensive machines on the production line. 
     It would therefore be advantageous to provide a sheet cleaning apparatus which can be quickly serviced to minimize the machine down time. 
     SUMMARY OF THE INVENTION 
     To overcome the foregoing problems, a sheet cleaning apparatus is described, having one or more sets of cleaning rollers, wherein the rollers are integrated into a removable cartridge assembly. Couplers are provided at roller shaft ends to connect to the roller drive. The cartridge assembly is held in a slide carriage, permitting the cartridge assembly to be readily removed from the apparatus by sliding the carriage out, and lifting the cartridge out from the slide carriage. With this arrangement, the down time for the sheet cleaning apparatus is minimized, since the sheet cleaning apparatus can be provided with two cartridges, and the cartridge needing maintenance can simply be quickly removed and replaced with a fresh cartridge. The production line can quickly be put back into operation, and the removed cartridge can be serviced off line for subsequent use. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     These and other features and advantages of the present invention will become more apparent from the following detailed description of an exemplary embodiment thereof, as illustrated in the accompanying drawings, in which: 
     FIG. 1 is a front view of a sheet cleaning apparatus embodying the invention. 
     FIG. 2 is a side cross-sectional view taken along line  2 — 2  of FIG.  1 . 
     FIG. 3 is a side view illustrating the relative orientation of the sheet cleaning rollers and the roller cleaning adhesive rolls. 
     FIG. 4 is a simplified perspective view illustrating an exemplary motor/gear drive arrangement for driving the roller couplers. 
     FIG. 5 illustrates the sheet cleaning apparatus with the roller cartridge exposed and removed from the cartridge slide arrangement for replacement. 
     FIG. 6 is an exploded view of the drive end of the cartridge roller assembly. 
     FIG. 7 is an isometric view of a roller lifting device employing in the apparatus of FIG. 1 to bias the position of the upper set of sheet cleaning rollers upwardly for separation from the lower set of sheet cleaning rollers when the apparatus is not in use. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1-7 illustrate an exemplary embodiment of a sheet cleaning apparatus  50  embodying the invention. The apparatus  50  includes two pairs of sheet-contacting cleaning rollers  52 ,  54  and  56 ,  58 . Rollers  52  and  54  are disposed in vertical alignment adjacent each other to define a nip  62 . The surfaces of the cleaning rollers  52 ,  54 ,  56 ,  58  are defined by a layer of resilient compressible material which has a surface tack or adhesion sufficient to transfer dust and other foreign particulate contamination from a sheet coming into compressive contact with the roller surface. It is also desirable that the roller surfaces be smooth, in order to obtain complete contact with the surface of a sheet pressed against the surface. Typically, the roller surfaces will have a Shore A durometer value of up to 35. 
     In order to clean the surfaces of the sheet cleaning rollers  52 - 58 , rolls  64 ,  66  of adhesive-coated tape are provided. These rolls  64 ,  66  are disposed so as to be in contact with respective surfaces of rollers  52 - 58  during sheet cleaning operations, as shown in FIG.  3 . In a general sense, the rolls  64 ,  66  are defined by rolls of tape having the adhesive coating on the outward facing sides. The external surface of each of the rolls  64 ,  66  has a surface tack which greatly exceeds the surface tack of the sheet cleaning rollers  52 - 58 , in order to transfer the foreign particles from the sheet cleaning rollers  52 - 58  to the surfaces of rolls  64 ,  66 . 
     To the extent just described, the apparatus  50  is similar to that described in U.S. Pat. No. 5,349,714. 
     The apparatus  50  includes a system for applying a variable preload force, urging roller  64  into engagement with surfaces of rollers  52  and  56 , and urging roller  66  into engagement with surfaces of rollers  54  and  58 . The system includes pneumatic cylinders  100  and  102  which support the lower tape roller  66 , and pneumatic cylinders  104  and  106  which apply pressure to the upper tape roller  64 . Cylinder  100  includes a rod  100 A driven by a cylinder piston to an extended position. The rod is attached to a coupler  100 B which has an opening into which an end of shaft  67  carrying roll  66  is inserted. Cylinder  102  includes rod  102 A driven by a cylinder piston to an extended position. Rod  102 A is attached to a coupler  102 B which has an opening into which the opposed end of shaft  67  is inserted. The roll  66  is therefore supported by the system comprising cylinders  100  and  102  and couplers  100 B and  102 B. The cylinders  100  and  102  are single acting, spring biased devices, wherein the rods are spring biased to the fully retracted position, and the rods are extended against the bias when pneumatic pressure is applied to the cylinders. Further the compression contact force of the roll  66  in relation to the sheet cleaning rollers  54  and  58  is adjustable by adjusting the pneumatic pressure applied to the cylinders  100  and  102 . 
     The system further includes pneumatic cylinders  104  and  106  which apply pressure to the upper tape roller  64 . Cylinder  104  includes a rod  104 A driven by a cylinder piston to an extended position. The rod is attached to a coupler  104 B which has an U-shaped opening into which a portion of shaft  65  carrying roll  64  and adjacent a shaft end is received. Cylinder  106  includes rod  106 A driven by a cylinder piston to an extended position. Rod  106 A is attached to a coupler  106 B which has an opening into which a portion of shaft  67  adjacent the opposite end of the shaft is received. The cylinders  104  and  106  are single acting, spring biased devices, wherein the rods are spring biased to the fully retracted position, and the rods are extended against the bias when pneumatic pressure is applied to the cylinders. Further the compression contact force of the roll  64  in relation to the sheet cleaning rollers  52  and  56  is adjustable by adjusting the pneumatic pressure applied to the cylinders  104  and  106 . 
     The shaft  65  is carried by spring-loaded bracket assemblies  72  and  74 . Exemplary bracket assembly  72  is illustrated in FIG. 7, and includes outer bracket fixture  72 A, sliding bracket  72 B which fits within the outer fixture for sliding movement, and bias spring elements  72 D and  72 E. The spring elements bias the relative position of the sliding bracket  72 B to the upper position shown in FIG. 7, and upon application of force, the springs are compressible to permit the bracket  72 B to slide down. Assembly  74  is identical to assembly  72 . Together, these assemblies bias the upper tape roll  64  to an elevated position out of contact with the cleaner rollers  52 ,  56  when the machine is idle, i.e. when the pneumatic pressure for the cylinders  104  and  106  is released. This prevents the tape roll surface from adhering to the cleaner roller as a result of extended stationary contact. When the pneumatic pressure is removed from the cylinders  100 ,  102 , the lower tape roll  66  drops by force of gravity out of contact with the lower set of cleaner rollers  54 ,  58 , and is supported by a V-shaped cradle in brackets  76 ,  78 . No spring biasing is employed in connection with brackets  76 ,  78 , since such biasing would tend to keep the tape roll surface in contact with the surfaces of the lower cleaner rollers after the pneumatic pressure is released. 
     In accordance with an aspect of the invention, the cleaner rollers are arranged in an easily removable cartridge assembly  120 . The assembly  120  is mounted on a slide assembly  130  which permits the cartridge assembly to be moved from a working position, with the cleaner rollers in position within the apparatus  50  for operation, and a maintenance position (shown in FIG. 5) with the cleaner rollers and the cartridge assembly slid outside the housing  50 A of the cleaner apparatus  50  for ready replacement of the cartridge  120 . 
     As shown in FIG. 5, the slide assembly  130  includes a carriage member  132  which receives the cartridge assembly  120 . Four mounting tabs  122  on the cartridge assembly have holes  122 A formed therein. The cartridge assembly  120  is dropped and locked into position on the carriage  132 , with pins  134  extending upwardly from the carriage  132  and received through holes  122 A registering the position of the cartridge  120  on the carriage  132 . The cartridge assembly is locked into position by spring-loaded locking tabs (not shown) formed with the pins  134 , which locking tabs spring out after cartridge assembly has dropped onto the pins to lock the cartridge in position. This prevents the cartridge from being lifted from the carriage by the tackiness of the roll  64  as pressure is released from the pneumatic system. Other types of locking arrangements can readily be employed. The carriage  132  is mounted between a first set of opposed slide rails  136 A,  136 B, which in turn are mounted on a second set of opposed slide rails  138 A,  138 B. The second set of rails  138 A,  138 B are mounted on bearings (not shown) mounted to the housing  50 A to permit the second set of rails to slide outwardly also. The first set of rails is mounted on bearings to permit telescoping of the first and second sets of rails. The slide rails and bearings are parts of a commercially available slide assembly, such as the three-section linear drawer slides marketed by Jonathan Company, Fullerton, Calif., which lock in both the closed and open positions. 
     The cartridge assembly  120  is shown in further detail in FIG.  6 . Side rails  124 A,  124 B and end rails  126 A,  126 B form a carriage structure which carries the lower set of cleaner rollers  54 ,  58 . The rollers rotate on respective shafts  54 A,  58 A which in turn are mounted on bearings fitted in openings formed in the end rails. For example, bearings  126 AA and  126 AB are mounted in end rail  126 A. only the drive end of the cartridge assembly  120  is visible in FIG.  5 . The lower set of rollers are driven by a motor drive  150  (FIGS. 1 and 4) through a drive coupler  160 . The roller shafts  54 A,  58 A have flats  54 AA,  58 AA formed adjacent the shaft ends to form D-shaped shaft ends for mating with corresponding D-shaped openings  162 A,  164 A formed in hexagonal male coupler elements  162 ,  164  to prevent rotation of the coupler elements on the shafts, while permitting axial sliding movement of the coupler elements on the shafts. Springs  166 A,  166 B are fitted on the shafts and extend between an end surface of rail  126 A and the coupler elements  162  and  164  to urge the coupler elements away from the end surface of rail  126 A. Snap rings  168 A,  168 B lock into position in grooves  54 AB and  58 AB to lock the coupler elements  162 ,  164  onto the shafts, after assembly of the springs  166 A,  166 B and the coupler elements onto the shafts. The coupler elements  162 ,  164  are formed with conical end surfaces  162 B,  164 B which act as lead-in surfaces to align the male hexagonal coupler elements with corresponding female driven hexagonal coupler elements  170 ,  172  shown in the isolation perspective view of FIG.  4 . The driven coupler elements are mounted on shafts  174 ,  176 . Sprocket gears  178 ,  180  are mounted on the respective shafts  174 ,  176 , and have an endless chain  182  mounted thereon. The shaft  176  also has a beveled gear  184  mounted thereon, which meshes with beveled gear  186  mounted on the motor shaft  188 . The cleaner rollers  54 ,  58  are driven in the same direction by the motor drive  150 . 
     The upper cleaner rollers  52 ,  56  are not actively driven. Referring again to FIG. 6, the upper rollers are mounted to the cartridge assembly  120  by upper end rails  127 A,  127 B. The roller shafts  52 A,  56 A are received in corresponding bores (e.g.  127 AA,  127 AB) formed in the upper end rails. The upper end rails are slidably mounted on pins  128 A,  128 B which are received in bores (e.g. bores  127 AC,  127 AD) formed in the upper end rails. Springs (e.g., springs  129 A,  129 B) can be fitted on the pins to provide a bias force tending to separate the upper end rails  127 A,  127 B from the lower end rails  126 A,  126 B. This in turn biases the upper set of cleaner rollers  52 ,  56  away from the lower set of rollers  54 ,  58 . The upper set of pneumatic cylinders  104 ,  106  can exert a force on the tape roll  64  to push the upper set of rollers toward the lower set of rollers. The bias action of the springs, biasing the upper set of rollers away from the lower rollers and therefor tending to increase the nip gap, provides the advantage of facilitating the cleaning of thicker sheets for cleaning without adjusting the apparatus. For some applications, it is preferable to omit the springs fitted on the pins. 
     The cleaning apparatus employs a pneumatic supply and control system similar to that described in U.S. Pat. No.  5 , 349 , 714 , and illustrated at FIG.  9 . Similarly, the control circuit of FIG. 10 in U.S. Pat. No. 5,349,714 can be employed to control the motor drive  150 . The pneumatic supply and control system and the motor drive control circuit therefore need not be described in further detail herein. 
     The cartridge assembly  120  can easily be replaced with a fresh cartridge. This can be done by releasing the pressure on the pneumatic cylinders  100 - 106 , so that the tape rolls move out of engagement with the cleaner rollers  52 - 58 . The latch of the slide assembly is then released, and the carriage  132  is pulled from the operating position to the maintenance position shown in FIG.  5 . As the carriage is pulled out away from its operating position, the drive coupler elements  162 ,  164  become disengaged from the mating coupler elements  170 ,  172 , thereby disconnecting the cartridge from the motor drive  150 . The cartridge  120  is then removed, without the use of tools in this exemplary embodiment, by lifting the assembly up and out of engagement with the pins  134 . Once the cartridge assembly  120  is removed from the carriage  132 , it can quickly be replaced by a fresh cartridge with clean sets of rollers  52 - 58 . Once a fresh cartridge is positioned in the carriage  132 , the operator slides the carriage into the operating position. As the carriage slides into position, the coupler elements  162 ,  164  are received within the coupler elements  170 ,  172 . There may be some initial rotational misalignment between the hexagonal mating elements. If so, the springs  166 A,  166 B compress as the elements  162 ,  164  are pushed toward the end rail  126 A. The conical surfaces  162 B,  164 B tend to align the mating elements by acting as a lead-in surface. Even if the mating elements do not engage as the cartridge is slid into the operating position, the first time the motor drive is actuated, as the outer coupler elements  170 ,  172  are turned by the motor drive, the mating elements will come into alignment, and the springs  166 A,  166 B will urge the elements  162 ,  164  into an engaged aligned position relative to the outer mating elements  170 ,  172 . 
     The sheet cleaning apparatus can be quickly serviced by replacement of the cartridge assembly  120 , thus minimizing the machine down time. The removed cartridge assembly  120  can be serviced off line. The upper set of rollers  52 ,  56  can easily be removed from the cartridge assembly for cleaning, and to expose the lower set of rollers for cleaning. 
     It is understood that the above-described embodiments are merely illustrative of the possible specific embodiments which may represent principles of the present invention. Other arrangements may readily be devised in accordance with these principles by those skilled in the art without departing from the scope and spirit of the invention.