Patent Publication Number: US-2009223015-A1

Title: Automatic pallet cleaning apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority of prior Japanese Patent Application No. 2008-84847, filed on Mar. 27, 2008, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The embodiments discussed herein are related to an automatic pallet cleaning apparatus which automatically removes dust deposited on a pallet to clean the pallet which is used when precision apparatuses such as a magnetic disk apparatus are assembled. 
     BACKGROUND 
     Conventionally, production of precision apparatuses has been carried out on assembly lines provided in clean rooms without dust in order to enhance reliability and performance of finished products. In such assembly lines, assembly is performed while pallets or trays, on which base housings and parts forming the precision apparatuses are put, are conveyed by conveyor belts. 
     In particular, since magnetic disk apparatuses (HDD: Hard Disk Drive) have extremely precise structures, even if a bit of dust is mixed inside of the magnetic disk apparatuses, yield of the products drastically decreases. Thus, before the base housings and parts of the magnetic disk apparatuses are put on the pallets for being conveyed to the assembly line, the pallets are cleaned by removing dust and dirt deposited on the pallets with a manual operation using pressurized air or the like. 
     Among such conventional pallet cleaning apparatuses, Japanese Laid-open Patent Publication No. H11-319740 discloses a cleaning apparatus in which air is supplied from the outside to the inside of the apparatus to keep the inside of the apparatus in positive pressure, whereby tiny dust (less than 20 μm) which cannot be removed by air jets can be removed. 
     Further, Japanese Laid-open Patent Publication No. H11-244798 discloses an IC pallet cleaning apparatus in which dust deposited on the objects to be cleaned is displaced by blowing from a blower and is immediately sucked by a suction device so that the IC pallet is cleaned without dust spreading around. 
     Furthermore, Japanese Patent No. 3453707 discloses a cleaning apparatus in which static electricity is generated by rubber rolls and adhesive tape rolls in the apparatus to adsorb dust, and air is blown on a substrate or a sheet while conveying it. 
     However, in the above-mentioned conventional cleaning apparatuses for the pallet or the like, there is a problem as shown below. In the case where cleaning of the pallets in the clean room is performed using the air blows in the conventional manner, a large amount of dust spreads in the clean room, resulting in the environment of the clean room being contaminated. There is a way that the cleaning of the pallets is performed using air blown outside of the clean room, but it takes time and care in the cleaning operation, resulting in assembly efficiency (production efficiency) of the precision apparatus on the assembly line being lowered. 
     In addition, considering Japanese Laid-open Patent Publication No. H11-319740 or Japanese Laid-open Patent Publication No. H11-244798, the production efficiency on the assembly line is also low, and the cleaning operation around the assembly environment is not preferred in view of the clean environment. Further, in the cleaning apparatus according to Japanese Patent No. 3453707, although dust is more reliably adsorbed by the static electricity, there is a possibility that the objects to be cleaned may be charged, thus this cleaning apparatus is not preferable as a cleaning apparatus for products which are subject to electrostatic destruction (such as magnetic heads). 
     SUMMARY 
     According to an aspect of the invention, an automatic pallet cleaning apparatus cleans a pallet which is an object to be cleaned by removing dust deposited thereon. The apparatus includes a conveyance mechanism, an air jet unit and a suction unit. The conveyance mechanism conveys the pallet into a body of the automatic pallet cleaning apparatus. The air jet unit jets air against the pallet conveyed by the conveyance mechanism. The suction unit sucks dust removed from the pallet by the air jet unit. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an overall schematic view which shows the inside of an automatic pallet cleaning apparatus according to the first embodiment; 
         FIG. 2  is a top view of the automatic pallet cleaning apparatus shown in  FIG. 1 ; 
         FIG. 3  is an illustrative view which shows a pallet P coming at the automatic pallet cleaning apparatus; 
         FIG. 4  is an illustrative view which shows the pallet P conveyed in the automatic pallet cleaning apparatus; 
         FIG. 5  is an illustrative view which shows cleaning of the pallet P by the automatic pallet cleaning apparatus; 
         FIG. 6  is an illustrative view which illustrates carrying out the pallet P from the automatic pallet cleaning apparatus; 
         FIGS. 7A to 7C  are illustrative views which show an example of a method for positioning the automatic pallet cleaning apparatus; and 
         FIG. 8  is an illustrative view which shows an example of the automatic pallet cleaning apparatus and an assembly line. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Preferred embodiments of the present invention will be explained with reference to accompanying drawings. 
     First Embodiment 
     [Overview and Feature of the Automatic Pallet Cleaning Apparatus  1 ] 
     First, the overview and the feature of the automatic pallet cleaning apparatus  1  according to the first embodiment will be described with reference to  FIG. 1 .  FIG. 1  is an overall schematic view showing the inside of the automatic pallet cleaning apparatus  1 .  FIG. 2  is a top view of the automatic pallet cleaning apparatus  1  shown in  FIG. 1 . 
     Herein, the automatic pallet cleaning apparatus  1  according to the first embodiment has: a conveyor  11  which conveys a pallet P to be cleaned into a cleaning apparatus body  10  of the automatic pallet cleaning apparatus  1 ; an air jet nozzle  21  which jets air against the pallet P conveyed by the conveyor  11  to remove dust deposited on the pallet P for cleaning the pallet with the air; and an air sucking device  40  which sucks the dust removed from the pallet P by the air jet nozzle  21 . 
     Further, the automatic pallet cleaning apparatus  1  keeps the inside of the cleaning apparatus body  10  in a negative pressure state by the air sucking device  40  to prevent the air and the dust from flowing outside, so that outside air is not contaminated and the automatic pallet cleaning apparatus  1  can be suitably used in the clean room. 
     [Configuration of the Automatic Pallet Cleaning Apparatus  1 ] 
     Specifically, as shown in  FIGS. 1 and 2 , the automatic pallet cleaning apparatus  1  has: the cleaning apparatus body  10  which is generally formed in a substantial rectangular and elongated shape and has the conveyor  11  therein; and a convex housing  20  which is provided on the top of the cleaning apparatus body  10  and formed in a substantially trapezoidal shape. The cleaning apparatus body  10  is supported by a pair of leg portions  8  which are vertically arranged at the bottom of the cleaning apparatus body  10 . 
     As shown in  FIGS. 1 and 2 , the pallet P has: a housing arrangement area for putting a housing which forms a magnetic disk apparatus; and a part arrangement area for putting mounted parts which forms the magnetic disk apparatus. 
     In the convex housing  20 , the air jet nozzle  21  which jets air toward the inside of the cleaning apparatus body  10  is housed. A supply tube  31  of the air jet nozzle  21  is connected to a supply duct  33  of an air supply device  30  through an air inlet port  32 . Thus, the air supply device  30  can supply air to the air jet nozzle  21  through the air supply duct  33  connected to the air supply device  30 , the air inlet port  32 , and the supply tube  31 . 
     The angle of the air jet nozzle  21  is adjustable by an air jet angle adjustment mechanism  22 , and can be manually adjusted so as to be any angle (efficient angle for cleaning). 
     In this regard, after a cleaning test is made by the cleaning apparatus body  10  and a level for dust removal is checked by a dust counter (not shown), the angle of the air jet nozzle  21  can be set to an assembly angle which is optimal for cleaning and enables most efficient removal of dust. 
     A pair of openings  15  are formed on a partition board  9  which divides the cleaning apparatus body  10  substantially at the center, and a pair of branch suction ducts  41  are connected to the pair of openings  15 , respectively, and a suction duct  42  which is connected to the air sucking device  40  is connected to the branch suction ducts  41 . 
     The air sucking device  40  sucks dust floating in the cleaning apparatus body  10  to recover the dust. Further, air suction of the air sucking device  40  can provide a negative pressure state in the cleaning apparatus body  10  as compared with outside pressure. This prevents air from flowing outside of the cleaning apparatus body  10  and dust from spreading inside of the clean room. 
     An air flow through hole  16  is formed in an oblong shape, and by bringing a slip of paper or the like close to the air flow through hole  16  for direct view of the movement of the slip of paper, the air flow condition (as compared with outside pressure) in the cleaning apparatus body  10  can be checked. 
     On both sides of the cleaning apparatus body  10  (right and left ends in  FIGS. 1 and 2 ), pass-through ports  2 ,  3  are formed, through which the pallet P conveyed by conveyance belts  13  of the conveyor  11  passes. The pass-through ports  2 ,  3  can be opened and closed by an inlet shutter  4  and an outlet shutter  5 , respectively, which are vertically opened and closed. 
     The inlet shutter  4  is raised upward by the operation of a cylinder  6  when the pallet P comes close to the pass-through port  2 , and is lowered to be closed when the pallet P passes therethrough and is housed in the cleaning apparatus body  10 . The outlet shutter  5  is raised upward by the operation of a cylinder  6  when the cleaning of the pallet P is finished and the pallet P comes close the pass-through port  3 , and is lowered to be closed when the pallet P is conveyed outside of the cleaning apparatus body  10 . 
     As shown in  FIGS. 1 and 2 , the conveyor  11  having a plurality of conveyance rollers  12  (six rollers are shown in  FIGS. 1 and 2 ) is provided in the cleaning apparatus body  10 . The pallet P is conveyed by driving of the conveyance belts  13  which are stretched with tension on the conveyance rollers  12  when a drive motor  14  is driven. Namely, the conveyor  11  is rotated by driving from the drive motor  14 , and by revolution of the conveyance rollers  12  and the conveyance belts  13 , the pallet P which is put on the conveyor  11  can be conveyed. 
     Herein, a height T ( FIG. 7C ) of the conveyor  11  forming the automatic pallet cleaning apparatus  1  and a height T 1  of conveyors  11   a ,  11   a  forming an assembly line are identical, thus the pallet P can be smoothly conveyed on the assembly line. 
     The automatic pallet cleaning apparatus  1  constructed as described above is disposed on the assembly line ( FIGS. 7 and 8 ), and the operation (ON/OFF) of the conveyor  11  and the drive motor  14  in the processes on the assembly line can be performed by an operation panel of a control apparatus (not shown) provided in the clean room. 
     [Cleaning Procedure of the Pallet P According to the Automatic Pallet Cleaning Apparatus  1 ] 
     A cleaning procedure of the pallet P according to the automatic pallet cleaning apparatus  1  will be described in detail below with reference to  FIGS. 3 to 6 . Herein,  FIG. 3  is an illustrative view which illustrates a pallet P coming at the automatic pallet cleaning apparatus.  FIG. 4  is an illustrative view which illustrates the pallet P conveyed in the automatic pallet cleaning apparatus.  FIG. 5  is an illustrative view which illustrates cleaning (suction and removal of dust) of the pallet P by the automatic pallet cleaning apparatus  1 .  FIG. 6  is an illustrative view which illustrates carrying the pallet P out from the automatic pallet cleaning apparatus  1 . 
     Specifically, as shown in  FIG. 3 , when the pallet P conveyed by the conveyance belts  13  of the conveyor  11  comes to the pass-through port  2  which is formed in front of the cleaning apparatus body  10 , approach of the pallet P is detected by a sensor for sensing approach (not shown). Then, the cylinder  6  goes into an ON operation and the inlet shutter  4  is raised upward as shown in  FIG. 4 , so that the pallet P is conveyed into the cleaning apparatus body  10  by the conveyor  11  through the pass-through port  2  of the cleaning apparatus body  10 . 
     Next, when the pallet P is housed in the cleaning apparatus body  10 , as shown in  FIG. 5 , the inlet shutter  4  is lowered and closed, and clean air which is supplied from the air supply device  30  is jetted against the pallet P through the air supply duct  33  and the supply tube  31  from the air jet nozzle  21 , thus removal of dust deposited on the surface of the pallet P and cleaning of the pallet are performed by the air which is jetted from the air jet nozzle  21 . 
     As described above, the angle of the air jet nozzle  21  is adjustable by the air jet angle adjustment mechanism  22 . In this way, the air jet nozzle  21  has an adjustable air jet angle for jetting air and an air blowing angle with respect to the pallet P that can be arbitrarily changed, whereby the pallet P can be cleaned over a wide range. 
     As shown in  FIG. 5 , upon the clean air being jetted by the air jet nozzle  21 , the air sucking device  40  gets almost simultaneously into the ON operation, and then remaining dust in the cleaning apparatus body  10  is sucked by the air sucking device  40  through the suction ducts  41 ,  42 . 
     In this way, air in the cleaning apparatus body  10  of the automatic pallet cleaning apparatus  1  is sucked by the air sucking device  40 , so that the cleaning apparatus body  10  is kept in a negative pressure state with respect to outside pressure. This makes it possible to prevent air from flowing outside and prevent the inside of the clean room from being contaminated by dust. Further, the air sucking device  40  can reliably recover the dust which is removed by the air jet nozzle  21 . 
     Then, as shown in  FIG. 6 , when the cleaning of the pallet P is finished with the air jet from the air jet nozzle  21 , the outlet shutter  5  is opened by the operation of the cylinder  6 , and the cleaned pallet P is conveyed from the inside of the automatic pallet cleaning apparatus  1  through the pass-through port  3  to the outside. According to the procedures as described in  FIGS. 3 to 6 , the cleaning of the pallet P can be efficiently performed in a short time. 
       FIGS. 7A to 7C  are illustrative views which show an example of a method for positioning the automatic pallet cleaning apparatus  1 . As shown in  FIG. 7A , a plurality of the conveyors  11   a ,  11   a  which form the assembly line of the magnetic disk apparatus are positioned with being connected with each other. As shown in  FIG. 7B , the connected conveyors  11   a ,  11   a  are spaced from each other. Finally, as shown in  FIG. 7C , the conveyors  11   a ,  11   a  are arranged in a spaced manner by a width L of the automatic pallet cleaning apparatus  1  to make a predetermined space area. 
     Then, the automatic pallet cleaning apparatus  1  is put in the space area which is formed between the conveyors  11   a . According to the above procedures, the automatic pallet cleaning apparatus  1  can be easily positioned in the assembly line. 
     Herein, as described above, the height T of the conveyor  11  which forms the automatic pallet cleaning apparatus  1 , and the height T 1  of the conveyors  11   a ,  11   a  which form the assembly line and are positioned on both adjacent sides of the automatic pallet cleaning apparatus  1  are identical. Thus, the pallet P can be smoothly conveyed on the assembly line (i.e., between the conveyor  11  and the conveyor  11   a ). 
     In this way, since the automatic pallet cleaning apparatus  1  can be positioned in the in-line manner between the plurality of the conveyors  11   a  which form the assembly line of the magnetic disk apparatus, during the process in which the pallet P is used and the used pallet P is returned to the beginning of the assembly line, it is not necessary to spend working hours for temporarily stopping the assembly process to manually clean the pallet P as the conventional way. 
     In this way, since the cleaning of the pallet P can be finished without stopping the process on the assembly line, and in continuation with the assembly process of a precision apparatus, the cleaning of the pallet P can be performed for every use of the pallet P without deterioration of productivity of the precision apparatus. Thus facilities for the cleaning apparatus for cleaning the pallet P are compactly arranged, so that the effect of saving space in the clean room can also be realized. 
     [Assembly Line of the Magnetic Disk Apparatus (HDD)] 
     Next, an example of the automatic pallet cleaning apparatus  1  and the assembly line will be described with reference to  FIG. 8 . Specifically, as shown in  FIG. 8 , on the assembly line of the magnetic disk apparatus (HDD) according to the first embodiment, before operation for assembly of the precision apparatus (magnetic disk apparatus), the pallet P is conveyed toward the conveyor  11  of the automatic pallet cleaning apparatus  1  to be cleaned by the automatic pallet cleaning apparatus  1  (see  FIG. 8  ( 1 )). Next, in the automatic pallet cleaning apparatus  1 , the conveyed pallet P is cleaned (see  FIG. 8  ( 2 )). As described above, the cleaning of the pallet P by the automatic pallet cleaning apparatus  1  is performed according to the procedures described in  FIGS. 3 to 6 . 
     Then, an HDD base which is a body (housing base) of the magnetic disk apparatus (HDD) and mounted parts are supplied on the assembly line (see  FIG. 8  ( 3 )). Practically, a plurality of the parts which are assembled into the magnetic disk apparatus (HDD) are arranged at predetermined positions on the part arrangement area ( FIG. 1 ) of the pallet P. The housing (base) of the HDD is arranged on the housing arrangement area ( FIG. 1 ) of the pallet P. 
     Then, assembly operation is performed for the housing (base) of the HDD which is arranged on the pallet P, using the mounted parts (see  FIG. 8  ( 4 )). This assembly operation is performed according to an automatic assembly process by robots or the like. 
     Then, a finished assembled product (magnetic disc apparatus) is brought out from the assembly line (see  FIG. 8  ( 5 )). Finally, the product (magnetic disk apparatus) after assembly is finished, is brought out from the assembly line and carried out (see  FIG. 8  ( 6 )). 
     As described above, the automatic pallet cleaning apparatus  1  according the first embodiment has: the conveyor  11  which conveys the pallet P of the object to be cleaned into the body of the automatic pallet cleaning apparatus  1 ; the air jet nozzle  21  which jets air against the pallet P conveyed by the conveyor  11  to remove dust deposited on the pallet P for cleaning the pallet P by the air; and the air sucking device  40  which sucks the dust removed from the pallet P by the air jet nozzle  21 . Thus, the automatic pallet cleaning apparatus  1  is capable of efficiently removing dust deposited on the object to be cleaned (pallet P) in a short time and preventing contamination due to dust in the clean room. 
     Further, a manual cleaning using blowing air or the like as the conventional way in which the assembly process is temporarily stopped is not necessary, thus the production efficiency of the precision apparatus (magnetic disk apparatus) can be enhanced. 
     Although the first embodiment of the present invention has been described, the present invention may be carried out in various different embodiments other than the first embodiment described above within the spirit and scope of the appended claims. 
     Second Embodiment 
     In the above-described first embodiment, the pallet P has been described as an example of the object to be cleaned by the automatic pallet cleaning apparatus  1 , in which the precision apparatus such as the magnetic disk apparatus is put on the pallet P to mount the parts thereon. However, the present invention is applicable to trays, jigs or parts other than the pallet P as the objects to be cleaned by the automatic pallet cleaning apparatus  1 . 
     Further, in the first embodiment described above, although the air jet angle of the air jet nozzle  21  is manually adjusted by the air jet angle adjustment mechanism  22  and after the adjustment the angle is fixed, the air jet nozzle  21  may be automatically turned within a predetermined range of air jet angle. In this case, the cleaning of the surface of the pallet P can be continuously performed over a wide range and the removal of dust and dirt deposited on the pallet P can be more reliably performed. 
     Furthermore, conveyance speed of the conveyor  11  which conveys the pallet P may be variable. Specifically, instead of using the configuration in which the speed of the conveyor  11  for conveying the pallet P in the automatic pallet cleaning apparatus  1  is kept constant, it is possible to use the configuration in which the direction of the conveyor  11  is variable and the conveyance speed thereof is conformed to the conveyance speed of the conveyors  11   a  which are arranged in the rear side and the front side of the conveyor  11 . Thus repeated cleaning can be performed by reciprocating the pallet P in the cleaning apparatus body  10 . In this case, removal operation of dust and cleaning of the pallet P can be more reliably performed. 
     In the automatic pallet cleaning apparatus, the pallet, on which the precision apparatus is placed for being assembled, is cleaned by removing dust with the air jet of the air jet device. The dust which is removed by the air is sucked by a suction device to be reliably recovered without spreading outside, so that the clean room is not contaminated by the dust and fast cleaning and production efficiency can be enhanced. 
     All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiment of the present inventions have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.