Abstract:
The purpose of the present invention is to provide a plating stripping device that is capable of quickly stripping plating from used plated magnets without reducing the weights of the recovered magnets and recycling the magnets to manufacture new magnets. To solve this problem, the present invention provides a plating stripping device characterized by being equipped with an abrasive projection unit for projecting an abrasive to a plated magnet, a magnet fixing unit for fixing the magnet, and a motor for rotating either the magnet fixing unit or the abrasive projection unit, and characterized in that the magnet fixing unit has a movable mechanism for changing the surface of the magnet that directly faces the abrasive projection unit.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a plating stripping device. 
       BACKGROUND ART 
       [0002]    As a background art of the present technical field, there is JP-A-2001-40425 (Patent Literature 1). In JP-A-2001-40425, there is a statement “a plating film is floated on a part surface by shot peening or combining shot peening with ball mill or the like and the plating film is stripped. A base material after the plating is separated and removed can be used for re-plating or re-solution.” Furthermore, there is JP-A-11-347941 (Patent Literature 2). In JP-A-11-347941, there is a statement “a tumbling blast machine or an apron blast machine is used. An R-Fe-B permanent magnet subjected to surface processing is inserted into a drum part in the blast machine. A steel shot is injected while rotating the drum part. As a result, it is possible to strip the surface processing plating film of the R-Fe-B permanent magnet completely without using a special solvent or the like.” (For example, Nd, Pr or the like corresponds to R.) 
       CITATION LIST 
     Patent Literature 
       [0003]    PATENT LITERATURE 1: JP-A-2001-40425 
         [0004]    PATENT LITERATURE 2: JP-A-11-347941 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0005]    In Patent Literature 1, a stripping method of a plating film of a magnet is stated. According to the stripping method in Patent Literature 1, however, stripping processing using a ball mill for a long time becomes necessary after the stripping processing using shot peening and consequently a long time is needed for processing. In Patent Literature 2, a surface processing film stripping method of the R-Fe-B permanent magnet is stated. According to the stripping method in Patent Literature 2, however, a projection material is projected onto the magnet at random. In a case where plating is stripped completely, the projection material strikes against the magnet excessively and the magnet main body is ground. As a result, the weight of the collected magnet reduces in some cases. 
         [0006]    Therefore, an object of the present invention is to provide a plating stripping device capable of quickly stripping plating from used plated magnets without reducing weights of the collected magnets and recycling the magnets to manufacture new magnets. 
       Solution to Problem 
       [0007]    In order to solve the above-described problem, the present invention provides a plating stripping device including an abrasive projection unit for projecting an abrasive onto plated magnets, a magnet fixing unit for fixing the magnets, and a motor for rotating either the magnet fixing unit or the abrasive projection unit. The magnet fixing unit has a movable mechanism to change surfaces of the magnets facing directly the abrasive projection unit. 
       Advantageous Effects of Invention 
       [0008]    According to the present invention, it is possible to provide a plating stripping device capable of quickly stripping plating from used plated magnets without reducing weights of the collected magnets and recycling the magnets to manufacture new magnets. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0009]      FIG. 1  is a diagram showing a plated rare-earth magnet used in embodiments 1 and 2; 
           [0010]      FIG. 2  is a perspective view of a plating stripping device of magnet fixing unit rotation type in the embodiment 1; 
           [0011]      FIG. 3  is a configuration diagram of a magnet fixing unit in the embodiment 1; 
           [0012]      FIG. 4  is a configuration diagram of a magnet fixing unit in the embodiment 1; 
           [0013]      FIG. 5  is a configuration diagram of a magnet fixing unit in the embodiment 1; 
           [0014]      FIG. 6  is a diagram showing location relations between an abrasive projection unit and a plated rare-earth magnet in the embodiment 1; 
           [0015]      FIG. 7  is a diagram showing location relations between an abrasive projection unit and a plated rare-earth magnet in embodiment 2; 
           [0016]      FIG. 8  is a diagram showing location relations between an abrasive projection unit and a plated rare-earth magnet in comparative example 1; 
           [0017]      FIG. 9  is a diagram showing location relations between an abrasive projection unit and a plated rare-earth magnet in comparative example 2; and 
           [0018]      FIG. 10  is a perspective view of a plating stripping device of abrasive projection unit rotation type in a modification of the embodiment 1. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0019]    Hereafter, embodiments will be described with reference to the drawings. Rare-earth magnets refer to permanent magnets made by using rare-earth elements. Neodymium magnets, samarium cobalt magnets, praseodymium magnets and so on have been put to practical use. Surfaces of the rare-earth magnets are plated depending upon the use. For using plated rare-earth magnets as magnet raw materials again, stripping of the plating is needed as pre-processing. At this time, it becomes important that plating does not remain on the magnet surface and only the plating is stripped without reducing the weight of the magnet itself. 
         [0020]      FIG. 1  is an example of a diagram showing a plated rare-earth magnet  1  that becomes an object of plating stripping. As shown in  FIG. 1 , the plated rare-earth magnet  1  includes a top surface ( 1 ), a bottom surface ( 2 ), a front surface ( 3 ), a rear surface ( 4 ), a right surface ( 5 ), and a left surface ( 6 ). In embodiments and comparative examples described hereafter, respective surfaces are defined as the surface ( 1 ) to the surface ( 6 ) as shown in  FIG. 1 . 
       Embodiment 1 
       [0021]    An example of a plating stripping device for rare-earth magnets in the present embodiment will now be described. 
         [0022]      FIG. 2  is an example of a diagram showing a configuration of a plating stripping device  2  of magnet fixing unit rotation type in the present embodiment.  FIG. 6  is a diagram obtained by viewing the plating stripping device  2  in the present embodiment from an angle different from that in  FIG. 2 . The plating stripping device  2  of the magnet fixing unit rotation type shown in  FIGS. 2 and 6  has a configuration in which an abrasive projection unit  21  for projecting an abrasive used to strip plating, a magnet fixing unit  22  for fixing a magnet that strips plating, and a motor  23  for rotating the magnet fixing unit are disposed. A location in which the abrasive is projected by the abrasive projection unit  21  can be changed by rotating the magnet fixing unit with the motor as shown in  FIGS. 2 and 6 . 
         [0023]    As for the abrasive projection unit  21 , its location and a projection angle of the abrasive can be adjusted. Furthermore, a plurality of abrasive projection ports may be provided. 
         [0024]    The magnet fixing unit  22  takes a shape of a disk as shown in  FIGS. 3 to 5 . Within the plating stripping device  2  of magnet fixing unit rotation type, the magnet fixing unit  22  is installed to cause the disk to face directly the abrasive projection port of the abrasive projection unit  21 . A movable mechanism is installed in the magnet fixing unit  22 . A surface of the plated rare-earth magnet  1  facing directly the abrasive projection unit  21  can be changed by the movable mechanism. Furthermore, the disk of the magnet fixing unit  22  is rotated in a circumference direction by the motor  23 . 
         [0025]    By the way, a plurality of jigs that fix the plated rare-earth magnets  1  may be prepared instead of the movable mechanism. Attaching portions are provided in the magnet fixing unit  22  to attach respective jigs. In a state in which the respective jigs are attached to attaching portions, the respective jigs fix the plated rare-earth magnets  1  to cause different surfaces of the plated rare-earth magnets  1  to face directly the abrasive projection unit  21 . 
         [0026]      FIGS. 3 to 5  show the plating stripping device  2  of magnet fixing unit rotation type at the time when surfaces of the plated rare-earth magnets  1  directly facing the abrasive projection unit  21  are changed by using the movable mechanism in the magnet fixing unit. 
         [0027]      FIG. 3  shows the magnet fixing unit  22  at the time when the surfaces ( 1 ) and surfaces ( 2 ) of the plated rare-earth magnets  1  are caused to face directly the abrasive projection unit  21 .  FIG. 4  shows the magnet fixing unit  22  at the time when the surfaces ( 3 ) and surfaces ( 4 ) of the plated rare-earth magnets  1  are caused to face directly the abrasive projection unit  21 .  FIG. 5  shows the magnet fixing unit  22  at the time when the surfaces ( 5 ) and surfaces ( 6 ) of the plated rare-earth magnets  1  are caused to face directly the abrasive projection unit  21 . 
         [0028]    The magnet fixing unit  22  includes magnets  221 , which function as fixing portions for fixing the rare-earth magnets  1 , to be capable of fixing a plurality of plated rare-earth magnets  1  on the same circumference. Since the plated rare-earth magnets  1  contain iron as the principal ingredient, it becomes possible to fix the magnets  1  by magnetic force possessed by the magnets  241 . By the way, as for the method for fixing the plated rare-earth magnets  1 , any method other than use of magnets, such as fixing using suckers or adsorption using air suction, may be used as long as a surface facing directly the abrasive projection port  21  is not covered. 
         [0029]    As for the plating stripping processing, if plating stripping from a certain surface is completed by using the magnet fixing unit, stripping from a different surface is conducted by using the movable mechanism. Plating of all surfaces of the rare-earth magnets  1  is stripped by repeating this. 
         [0030]    By the way, as for the device used in the plating stripping, a plating stripping device  2  of abrasive projection unit rotation type may be used instead of the plating stripping device of magnet fixing unit rotation type. In the plating stripping device  2  of abrasive projection unit rotation type, the plated rare-earth magnets  1  are fixed and the abrasive projection unit is rotated by a motor as shown in  FIG. 10 . 
         [0031]    According to the present embodiment, the abrasive can be projected on to the surfaces ( 1 ) to ( 6 ) evenly as described heretofore. As a result, it is possible to quickly strip plating without reducing weights of the collected magnets and recycle the magnets to manufacture new magnets. 
       Embodiment 2 
       [0032]    A plating stripping device  2  according to the present embodiment will now be described with reference to  FIG. 7 . The same component as that in the embodiment 1 is denoted by a like reference character, and description thereof will be omitted. 
         [0033]    The plating stripping device  2  according to the present embodiment shown in FIG.  7  has a feature in that the abrasive is projected by using two abrasive projection ports in the abrasive projection unit  21 . As for locations of abrasive projection ports, the abrasive projection ports are installed at some distance to project the abrasive onto the entire plated rare-earth magnet  1 . 
         [0034]    In  FIG. 7 , the two abrasive projection ports are oriented in the same direction. However, orientations of the two abrasive projection ports may be made different from each other. In this case, it is necessary to project the abrasive at different timing to prevent air flows from the abrasive projection unit  21  from interfering each other. 
         [0035]    By the way, as for the device used in the plating stripping, a plating stripping device  2  of abrasive projection unit rotation type may be used instead of the plating stripping device of magnet fixing unit rotation type in the same way as the embodiment 1. In the plating stripping device  2  of abrasive projection unit rotation type, the plated rare-earth magnets  1  are fixed and the abrasive projection unit is rotated by a motor as shown in  FIG. 10 . 
         [0036]    According to the present embodiment, two abrasive projection ports are used. As compared with the embodiment 1, therefore, plating can be stripped more quickly. 
         [0037]    Using plating stripping devices according to the embodiments 1 and 2 and comparative examples 1 and 2 described hereafter, plating stripping processing was conducted and stripping completion time and stripping states were observed. 
         [0038]    The plating stripping devices according to the comparative examples 1 and 2 are as follows. 
       Comparative Example 1 
       [0039]    As for a plating stripping device according to comparative example 2, plating stripping processing was conducted under the same conditions as those in the embodiment 1 except that the abrasive was projected simultaneously by using abrasive projection ports of two abrasive projection units  21  as shown in  FIG. 18 . Locations of the abrasive projection ports were set to cause directions in which the two abrasive projection ports were oriented to become different directions (vertical). 
       Comparative Example 2 
       [0040]    The magnet fixing unit was not used. The plated rare-earth magnet  1  was rotated around an axis as shown in  FIG. 9 . The axis passed between two surfaces having the widest areas among six surfaces of the magnet, and distances between the axis and two long sides among four sides of the two surfaces were nearly equal. An abrasive projection port was set to cause the abrasive projection direction to become perpendicular to the rotation axis. Other conditions were made the same as those in the embodiment 1, and plating stripping was conducted. 
         [0041]    Conditions of plating stripping processing according to the embodiments and comparative examples are as follows.
       The number of revolutions of the motor 23=136 RPM   Abrasive projection pressure=0.72 MPa   Distance between the abrasive projection port  21  and the plated rare-earth magnet  1 =125 mm   Abrasive material=alumina   Abrasive particle diameter=200 μm   Abrasive projection angle=90°   Size of plated rare-earth magnet  1 =approximately 50*25 mm (surfaces ( 1 ) and ( 2 )), approximately 50*3 mm (surfaces ( 3 ) and ( 4 )), and approximately 25*3 mm (surfaces ( 5 ) and ( 6 ))       
 
         [0049]    Plating stripping completion time and stripping states in the embodiments 1 and 2 and the comparative examples 1 and 2 are shown in Table 1. 
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Stripping 
                   
               
               
                   
                 completion time 
                 Stripping state 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Embodiment 1 
                 28.3 seconds 
                 Stripped completely 
               
               
                 Embodiment 2 
                 14.9 seconds 
                 Stripped completely 
               
               
                 Comparative 
                 At least 30 seconds 
                 Plating remains in end portions 
               
               
                 example 1 
               
               
                 Comparative 
                 At least 30 seconds 
                 Plating remains in end portions 
               
               
                 example 2 
               
               
                   
               
             
          
         
       
     
         [0050]    In the embodiments 1 and 2, first, stripping processing of the surfaces ( 1 ) and ( 2 ) of the plated rare-earth magnets  1  was conducted by using the magnet fixing unit  22 , and it was confirmed by observing the exterior views of the magnets that plating stripping of the surfaces ( 1 ) and ( 2 ) was completed. Then, stripping processing of the surfaces ( 3 ) and ( 4 ) of the plated rare-earth magnets  1  was conducted, and it was confirmed by observing the exterior views of the magnets that plating stripping of the surfaces ( 3 ) and ( 4 ) was completed. Then, stripping processing of the surfaces ( 5 ) and ( 6 ) of the plated rare-earth magnets  1  was conducted, and it was confirmed by observing the exterior views of the magnets that plating stripping of the surfaces ( 5 ) and ( 6 ) was completed. The plating stripping processing was finished. 
         [0051]    In the embodiment 1, the time over which the abrasive was projected onto one plated rare-earth magnet  1  became 28.3 seconds in total. According to a result of observation of the exterior view, plating was stripped completely. The shape of the magnet main body was the same as that before plating stripping, and break off or the like was not found. 
         [0052]    In the embodiment 2, the time over which the abrasive was projected onto one plated rare-earth magnet  1  became 14.9 seconds in total. According to a result of observation of the exterior view, plating was stripped completely. The shape of the magnet main body was the same as that before plating stripping, and break off or the like was not found. It becomes possible to shorten the time required for the plating stripping processing by increasing the projection port to a plurality and stripping plating one surface every projection port in this way. 
         [0053]    In the comparative example 1, for example, in a case where the magnet fixing unit  22  is used, it becomes possible to project the abrasive to the surface ( 3 ) or ( 4 ) simultaneously with to the surface ( 1 ) or ( 2 ). In the case where plating stripping from two surfaces perpendicular to each other is conducted, interference between air flows of abrasive projection occurs and plating cannot be stripped well. It becomes difficult to strip the plating completely. Although projection of the abrasive was continued for at least 30 seconds, therefore, the plating was not stripped completely and the plating stripping processing was finished on the way. The plating remained in end portions of magnets. Furthermore, a hollow was found in a portion where the plating was stripped. It was confirmed that the magnet main body was shaved by the abrasive and the weight was reduced. 
         [0054]    In the comparative example 2, the magnet rotates to change over the surface facing directly the abrasive projection port. Therefore, the surface onto which the abrasive is projected is not one surface, but the abrasive is projected onto a plurality of surfaces. If the surface onto which the abrasive is projected is changed over by rotation, however, plating stripping is not conducted sufficiently by the abrasive and it becomes difficult to strip plating completely. Although projection of the abrasive was continued for at least 30 seconds, therefore, the plating was not stripped completely and the plating stripping processing was finished on the way. The plating remained in end portions of magnets. Furthermore, a hollow was found in a portion where the plating was stripped. It was confirmed that the magnet main body was shaved by the abrasive and the weight was reduced. 
         [0055]    By the way, the present invention is not restricted to the above-described embodiments, but various modifications are included. For example, the above-described embodiments have been described in detail to describe the present invention intelligibly, and the present invention is not necessarily restricted to embodiments including all described configurations. Furthermore, it is possible to replace a part of a configuration in a certain embodiment with a configuration in another embodiment. Furthermore, it is also possible to add a configuration in another embodiment to a configuration in a certain embodiment. Furthermore, with respect to a part of a configuration in each embodiment, it is possible to conduct addition, removal, and replacement of another configuration. 
       REFERENCE SIGNS LIST 
       [0056]      1 : Plated rare-earth magnet 
         [0057]      2 : Plating stripping device 
         [0058]      21 : Abrasive projection unit 
         [0059]      22 : Magnet fixing unit 
         [0060]      23 : Motor