Abstract:
A polishing device capable of polishing a repaired surface in a specified shape, comprising a polishing panel body holding a polishing material on a surface opposed to the repaired surface and polishing the repaired surface in the specified shape with the polishing material and a holding part installed on the polishing panel body and held when the polishing panel body is operated, wherein the holding part is installed on the polishing panel body rotatably about an axis set on the polishing panel body, whereby a controllability can be improved, the labor of a worker can be reduced, and the disturbance of smoothness on the repaired surface and the premature wear of sand paper can be suppressed.

Description:
TECHNICAL FIELD 
   The present invention relates to a polishing device for polishing a surface to be repaired into a predetermined shape. 
   BACKGROUND ART 
   When the coated surface of a vehicle has been flawed or dented and needs repairing, a process is performed in which the primer, surfacer, and paint with which the panel surface (steel plate) has been coated are peeled off by polishing. Further, a process is performed in which the damaged portion is filled with putty etc. and in which the putty surface and the body surface are polished so as to make them flush with each other. 
   Usually, in these processes, the operation is conducted by using a polishing device which is, as shown in  FIGS. 21 and 22 , equipped with a polishing panel body  100  having a sandpaper  101  constituting the polishing material glued to its surface opposed to the surface to be repaired, and a holding part  102 ,  103  fixed to the polishing panel body  100 . 
   The holding part, which is formed in a variety of forms according to the use, e.g., for both hands or one hand, is roughly classified in the following two patterns: a first pattern in which it is simply formed as a plate as shown in  FIG. 21 , and a second pattern in which it is equipped with a bar-shaped grip. In both patterns, the holding part is firmly fixed to the polishing panel body  100  so as to protrude upright from the center of the polishing panel body  100 . 
   The polishing operation using the polishing device is performed not only on a flat portion which allows the operation to be conducted in an easy position, but also on a portion having a curved surface and a portion requiring operation in an uneasy position, e.g., a portion around a tire house and an inwardly bent portion at the lower end of a door. Thus, the operator has to appropriately change the operating direction of the polishing device or the way he holds the holding part. 
   However, the conventional polishing device, in which the holding part and the polishing panel body are fixed to each other, can only be held at a fixed holding angle. In other words, the degree of operational freedom of the polishing device is rather low. Conducting operation while holding the holding part in an irregular fashion leads to a pain and fatigue in the hand, resulting in a substantial reduction in the general operational efficiency. 
   Further, when the conventional polishing device is being used, the plate-shaped holding part protruding upright from the polishing panel body is held by hand, so that the external force (pressure) transmitted from the holding part to the surface to be polished is transmitted to a point considerably spaced apart from the surface to be polished. Thus, polishing is performed with the polishing device being in an unstable state, so that the smoothness of the surface to be repaired (the surface to be polished) is disturbed or the sandpaper undergoes unsymmetrical wear, which can not only impair the operability of the polishing device, but also adversely affect the vehicle repairing operation itself. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a polishing device which is superior in operability and which can contribute to reducing the labor of the operator. Further, the present invention aims to provide a polishing device capable of restraining disturbance of the smoothness of the surface to be repaired, premature wear of the sandpaper, etc. 
   The polishing device of the present invention includes a polishing panel body which holds a polishing material on its surface opposed to the surface to be repaired and which polishes the surface to be repaired into a predetermined shape with the polishing material, and a holding part which is provided on the polishing panel body and which is held by hand when the polishing panel body is to be operated. The holding part is provided on the polishing panel body so as to be rotatable around a predetermined axis set on the polishing panel body. 
   Thus, in the polishing device of the present invention, the mounting angle of the holding part with respect to the polishing panel body can be arbitrarily changed. Accordingly, the operator can change the holding angle of the holding part to a desired position according to the shape of the surface to be repaired, so that he can easily polish the surface to be repaired without having to hold the holding part in an irregular fashion. Note that the predetermined axis implies both an axis extending from the polishing panel body and an axis extending from the holding part. 
   It is also possible for the holding part to be rotatably provided in a plane parallel to the panel surface of the polishing panel body. That is, the polishing device of the present invention allows the mounting angle of the holding part to be changed two-dimensionally parallel to the panel surface of the polishing panel body. 
   Further, in the present invention, it is also possible to adopt a construction in which there is provided a fixing means for fixing the holding part at a predetermined rotating position with respect to the polishing panel body. That is, the operator can fix the holding part at a desired position with respect to the polishing panel body. As a result, even in the case of a heavy operation, the mounting angle of the holding part is not changed. Thus, this construction helps to further improve the operability of the polishing device. 
   It is desirable for the fixing means to fix the polishing panel body and the holding part to each other at a position spaced apart from the rotation center of the holding part. In this case, it is possible to enhance the fixing strength for the polishing panel body and the holding part as compared with the case in which the polishing panel body and the holding part are fixed together at the rotation center of the holding part. 
   Further, the fixing means may comprise a lock member which can freely move to a lock position where the polishing panel body and the holding part are normally fixed to each other and a lock releasing position where the fixation of the polishing panel body and the holding part is canceled to permit rotation of the holding part. That is, it is possible to adopt as the fixing means a lock mechanism which automatically locks when rotation of the holding part is not required. Thus, the operator can easily change the mounting angle of the holding part with respect to the polishing panel body. 
   Further, the holding part may comprise a swollen portion whose surface comes into contact with the palm of the hand during operation of the device, and finger rest recesses arranged on both sides of the swollen portion and held between fingers during the operation of the device. That is, a configuration is adopted which provides the most stable holding state when the holding part is held so as to be wrapped in the entire hand. Further, due to the finger rest recesses arranged on both sides of the swollen portion, the palm of the hand is not shifted from the swollen portion even in the case of a heavy polishing, making it possible to maintain a stable holding state. Thus, a uniform pressure is applied to the surface to be polished. Further, the external force (pressure) from the holding part is transmitted to the surface to be polished at a point near the same. 
   It is desirable that the connecting portions between the swollen portion and the finger rest recesses be formed as continuous curved surfaces. That is, the portions in contact with the hand are formed as continuous curved surfaces conformable to the hand. 
   Further, the swollen portion may be provided at a position spaced apart from the center of the polishing panel body. In this construction, due to the deviation of the swollen portion from the center of the polishing panel body, it is possible to apply a uniform pressure to the polishing panel body as a whole by the entire hand. 
   Further, the holding part may be equipped with a plurality of swollen portions, at least two of the plurality of swollen portions are arranged in a straight line passing the predetermined axis so as to be symmetrical with respect to the predetermined axis. That is, due to the swollen portions arranged symmetrically with respect to the predetermined axis, the polishing device can be suitably held by both hands. 
   Further, it is also possible for the holding part to be composed of a plurality of members, each of which is equipped with a swollen portion and rotatable with respect to the predetermined axis. That is, a holding part for the holding by the right hand and a holding part for the holding by the left hand are separately provided, and these holding parts are connected so as to be rotatable with respect to the predetermined axis. Thus, in this construction, the holding angle for the right hand and that for the left hand can be set individually. 
   Further, the polishing panel body may comprise a base panel portion retaining a polishing material on its surface opposed to the surface to be repaired, a movable base panel portion bendably hinged on an end portion of the base panel portion and retaining a polishing material on its surface opposed to the surface to be repaired, and an urging means for urging the surface of the movable base panel portion so as to make it flush with the surface of the base panel portion. Thus, in this construction, the end portion of the polishing surface for polishing the surface to be repaired is formed so as to be bendable. As a result, even when polishing is performed by using the end portion of the polishing surface, the polishing surface comes into contact with the surface to be repaired not as a line but as a plane, whereby it is possible to restrain a polishing failure such as overpolishing. 
   Thus, according to the present invention, polishing operation can be performed while holding the polishing device at a reasonable holding angle, so that the operator is spared a pain and fatigue in the hand. Further, due to the adoption of a holding part which provides the most stable holding state when held so as to be wrapped in the entire hand, the polishing panel body is improved in terms of stability. In this way, the present invention can provide a polishing device which is superior in operability and which can contribute to a reduction in the labor of the operator. Further, it is possible to provide a polishing device also capable of restraining disturbance of the smoothness of the surface to be repaired, premature wear of the sandpaper, etc. 
   The axle serving as the rotation center of the holding part may consist of an imaginary axis. That is, when a mechanism such as an arcuate guide rail for rotating the holding part relative to the polishing panel main body is provided in the connecting portion between the polishing panel body and the holding part, there is no need to provide an actual axle at the rotation center. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view of a one-hand polishing device according to a first embodiment of the present invention; 
       FIG. 2  is a front view of the one-hand polishing device of the first embodiment of the present invention; 
       FIG. 3  is a plan view of the one-hand polishing device of the first embodiment of the present invention; 
       FIG. 4  is a perspective view of the polishing panel body of a polishing device according to the present invention; 
       FIG. 5  is a side view of the polishing panel body of the polishing device of the present invention; 
       FIG. 6  is a front view of the polishing panel body of the polishing device of the present invention; 
       FIG. 7  is a plan view showing how a base panel portion and a movable base panel portion are connected together in a polishing device according to the present invention; 
       FIG. 8  is a perspective view showing how a base panel portion and a movable base panel portion are connected together in a polishing device according to the present invention; 
       FIG. 9  is a diagram showing how polishing is performed using a polishing surface end portion; 
       FIG. 10  is a perspective view showing how the movable base panel portion of a polishing device according to the present invention is movable; 
       FIG. 11  is a diagram showing an elastic member in a polishing device according to the present invention; 
       FIG. 12  is a perspective view showing a lock mechanism in a polishing device according to the present invention; 
       FIG. 13  is a diagram showing the movement of each component in the lock mechanism of  FIG. 12  in a lock releasing state; 
       FIG. 14  is a diagram showing the movement of each component in the lock mechanism of  FIG. 12  in a locking state; 
       FIG. 15  is a side view of a two-hand polishing device according to a second embodiment of the present invention; 
       FIG. 16  is a plan view of the two-hand polishing device of the second embodiment of the present invention; 
       FIG. 17  is a plan view of a two-hand polishing device according to a third embodiment of the present invention; 
       FIG. 18  is a diagram showing the fixing angle of the holding part when the polishing device of the first embodiment is operated obliquely with the right hand; 
       FIG. 19  is a diagram showing the fixing angle of the holding part when the polishing device of the first embodiment is operated obliquely with the left hand; 
       FIG. 20  is a diagram showing the fixing angle of the holding part when the polishing device of the first embodiment is operated horizontally with the right hand; 
       FIG. 21  is a perspective view showing a conventional polishing device; and 
       FIG. 22  is a perspective view showing a conventional polishing device. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The polishing device of the present invention will now be described in detail with reference to the drawings. 
   FIRST EMBODIMENT 
   First, a one-hand polishing device according to a preferred embodiment of the present invention, which is to be held by one hand when used, will be described. 
   As shown in  FIG. 1 , a one-hand polishing device  1  according to the present invention includes a polishing panel body  2  having a sandpaper S serving as a polishing material glued to its surface opposed to a surface to be repaired, a holding part  3  provided on the polishing panel body  2  so as to be rotatable around a predetermined axle  33  provided on the polishing panel body  2 , and a lock mechanism  32  for fixing the holding part  3  at a predetermined rotating position with respect to the polishing panel body  2 . 
   As shown in  FIG. 4 , the polishing panel body  2  includes a retaining panel  21  serving as the mounting portion for the holding part  3 , a base panel portion  22  arranged under the retaining panel  21  and detachably retaining the sandpaper S on the surface opposed to the surface to be repaired (the surface to be polished) (not shown), movable base panel portions  23  bendably hinged on end portions  22   a  of the base panel portion  22  and detachably retaining the sandpaper S on the surfaces opposed to the surface to be repaired, elastic members  24  arranged on the lower surface side of the retaining panel  21  and supporting the base panel portion  22  and the movable base panel portions  23  in the same plane, and a dust suction passage R for guiding dust generated during polishing to a dust suction device (not shown) provided separately from the polishing device. 
   Here, the lower surface side of the retaining panel  21  implies the surface opposed to the surface to be repaired when the polishing device  1  is being used. Further, in the following description, the terms “lower surface” and “lower side” imply the surface and the side opposed to the surface to be repaired unless otherwise specified. Further, in some places of the following description, the surfaces of the base panel portion  22  and the movable base panel portions  23  opposed to the surface to be repaired will be simply referred to as the polishing surfaces M. 
   The retaining panel  21  is formed of a rectangular aluminum plate, and has at its center a holding part support hole  21   a  used when the holding part  3  is rotatably mounted to the retaining panel  21 . At positions spaced apart from the holding part support hole  21   a  and in the same radius of curvature whose center is the holding part support hole  21   a , there are formed a plurality of lock holes  21   b  used when the holding part  3  is fixed at a desired rotating angle with respect to the retaining panel  21 . Further, in the center line extending in the longitudinal direction of the retaining panel  21 , there are formed dust collection holes  21   c  for guiding dust (polishing dust) generated during polishing to the dust suction device. The holding part support hole  21   a , the lock holes  21   b , and the dust collection holes  21   c  will be described in detail below together with the holding part  3 . 
   As shown in  FIG. 7 , each of the base panel portion  22  and the movable base panel portions  23  arranged on the lower surface side of the retaining panel  21  consists of a rectangular thin-walled resin plate and is supported by the lower surface of the retaining panel  21  through the intermediation of elastic members  24 . Further, the polishing surfaces M of the base panel portion  22  and the movable base panel portions  23  are arranged in the same plane by the elastic members  24 , and a single adhesive sheet M 1  is attached to the polishing surfaces M (See  FIG. 8 ). 
   That is, the movable base panel portions  23  are bendably connected to the end portions  22   a  of the base panel portion  22  through the adhesive sheet M 1 , and are movable from the positions where they are flush with the base panel portion  22  to the positions where they come into contact with the end portions  21   a  of the retaining panel  21 . The movable base panel portions  23  and the base panel portion  22  are connected to each other at their longer sides. The adhesive sheet M 1  serves to facilitate the attachment and detachment of the sandpaper S. 
   While in this embodiment the base panel portion  22  and the movable base panel portions  23  are connected to each other by means of the adhesive sheet M 1 , it is also possible to form the base panel portion  22  and the movable base panel portions  23  of a single thin-walled resin plate and to form thin-walled flange portions in correspondence with the boundaries between the base panel portion  22  and the movable base panel portions  23  so as to make the movable base panel portions  23  bendable. 
   As shown in  FIG. 11 , the elastic members  24  for fixing the base panel portion  22  and the movable base panel portions  23  to the retaining panel  21  consist of a first elastic support portion  24   a  which is made of hard sponge and which is provided so as to be erect along the periphery of the base panel portion  23  and adapted to support the base panel portion  23  on the retaining panel  21 , and a plurality of second elastic support portions  24   b  which are provided on the movable base panel portions  23  and formed of hard sponge and springs  24   c  and which are adapted to support the movable base panel portions  23  on the retaining panel  21 . 
   The first elastic support portion  24   a , which is formed along the periphery of the base panel portion  22 , forms between the retaining panel  21  and the base panel portion  22  an inner space L separated from the exterior. In view of this, in the polishing device  1  of this embodiment, the above-mentioned dust suction passage R is formed in the polishing panel body  2  by utilizing this inner space L. More specifically, the dust collection holes  21   c  of the retaining panel  21  are formed so as to communicate with the inner space L. Further, dust suction holes M 2  communicating with the inner space L are also formed in the polishing surface M formed by the base panel portion  22  and the movable panel portions  23 , forming in the polishing panel body  2  the dust suction passage R consisting of the dust suction holes M 2 , the inner space L, and the dust collection holes  21   c  (See  FIG. 1 ). 
   As indicated by the imaginary lines in  FIG. 11 , the dust suction holes M 2  formed in the polishing surface M are formed not only on the base panel portion, but also on the boundaries T between the movable base panel portions  23  and the base panel portion  22 . Thus, a part of the first elastic support portion  24   a  protrudes on the movable base panel portion  23  side so as to go around the dust suction holes M 2  provided on the boundaries T so that dust generated in the boundaries T can also be guided to the dust suction passage R. The dust suction passage R is connected to the dust suction device (not shown) by way of a dust suction passage R 1  provided in the holding part  3  described below. The dust suction passage R 1  will be described in detail below together with the holding part  3 . As the dust suction device, a general-purpose dust suction device having a suction source is used. 
   In this way, in the polishing panel body  2 , the end portions M 3  of the polishing surface M formed by the movable base panel portions  23  are provided so as to be bendable. Thus, even when polishing is performed using the polishing surface end portion M 3 , the polishing surface end portion M 3  comes into plane contact with the surface to be repaired. As a result, a satisfactory repaired surface can be easily obtained without involving overpolishing. Examples of a polishing operation using the polishing surface end portion M 3  include a feather edge operation for imparting a gentle inclination from the vehicle panel surface to the former coated surface. 
   Next, the holding part  3  will be described. 
   As shown in  FIG. 1 , the holding part  3  includes a hollow holding part main body  31  held during use, a lock mechanism  32  accommodated in the holding part main body  31  and adapted to fix the holding part  3  at a predetermined rotating position with respect to the polishing panel body  2 , and an axle  33  for mounting the holding part main body  31  rotatably to the polishing panel body  2 . 
   The holding part main body  31  includes a swollen portion  34  to be brought into plane contact with the palm of the hand of the user, and finger rest recesses  35  provided on either side of the swollen portion  34  and held by fingers of the user during use, and generally exhibits a round outward appearance formed by continuous curved surfaces. In the state in which the holding part  3  and the polishing panel body  2  are connected together, the swollen portion  34  is situated at a position spaced apart from the center of the polishing panel body  2 . And, inside the swollen portion  34 , there are provided the above-mentioned lock mechanism  32  and a bearing  33   a  for the axle  33 . 
   That is, the holding part  3  has a configuration which provides the most stable holding state when held so as to be wrapped in the entire hand of the user. As a result, a uniform pressure is generated with respect to the entire polishing surface M, whereby premature wear of the sandpaper S and disturbance of the smoothness of the non-polished surface can be restrained. Further, the external force (pressure) transmitted to the polishing surface M from the holding part  3  during operation of the polishing device  1  is transmitted at a point near the polishing surface M. Thus, shake of the polishing panel body  2  is restrained to thereby improve the operability of the polishing device  1 . Further, since the portions coming into contact with the hand of the user are formed by continuous curved surfaces conformable to the hand, it is possible to prevent a pain and fatigue in the palm of the hand. 
   The bearing portion  33   a  fixes and supports the holding part main body  31  and the axle  33  at the center of the holding part main body  31 . The axle  33  is inserted into the holding part support hole  21   a  provided in the retaining panel  21 , and then fixed by a screw from the polishing surface M side of the base panel portion  22  through the intermediation of the base panel portion  22 . A screw  33   b  is fastened with a fastening torque which allows the base panel portion  22  to easily rotate between the end surface of the axle  33  and the screw  33   b . Thus, the axle  33  rotates within the holding part support hole  21   a , permitting the holding part main body  31  to rotate with respect to the polishing panel body  2 . 
   Further, in the surface of the holding part main body  31  coming into contact with the retaining panel  21 , there is formed the dust suction passage R 1  that the dust collection holes  21   c  provided in the retaining panel  21  face inwardly. The dust suction passage R 1  can be connected to the dust suction device provided separately from the polishing device  1  through a hose P. In order that the dust suction passage R 1  may constantly communicate with the plurality of dust collection holes  21   c  provided in the retaining panel  21  so as to be aligned in the center line of the retaining panel  21  even during rotation of the holding part  3 , the width of the dust suction passage R 1  formed in the holding part main body  31  is sufficiently larger than the width of the dust collection holes  21   c.    
   On the other hand, as shown in  FIG. 1 , the lock mechanism  32  accommodated in the holding part main body  31  fixes the polishing panel body  2  and the holding part  3  at a position spaced apart from the rotation center (the axle  33 ) of the holding part main body  31 . 
   As shown in  FIG. 12 , this lock mechanism  32  includes a lock pin  32   a  (lock member) provided so as to be movable in the vertical direction of the holding part main body  31  and extending through the lower surface of the holding part main body  31  to be engaged with the lock hole  21   b  provided in the retaining panel  21 , an operation rod  32   b  extending in the horizontal direction of the holding part main body  31  so as to have its forward end protruded to the exterior of the holding part main body  31  and capable of canceling the engagement of the lock pin  32   a  and the lock hole  21   b , and a support body  32   c  supporting the lock pin  32   a  and the operation rod  32   b.    
   That is, the lock pin  32   a  and the operation rod  32   b  are supported by the support body  32   c  so as to cross each other. Further, in the portion where the lock pin  32   a  and the operation rod  32   b  cross each other, there is provided a guide mechanism composed of a guide groove  32   d  and a guide member  32   e  and adapted to push the lock pin  32   a  upwards when the operation rod  32   b  is operated. 
   This guide mechanism will be described. The guide groove  32   d  is provided on the operation rod  32   b  side, and configured such that its depth decreases as the operation rod  32   b  is pushed in the support body  32   c . The guide member  32   e  is fixed to the lock pin  32   a , and is urged toward the interior of the guide groove  32   d  by a spring  32   f  so as to constantly maintain the engagement with the guide groove  32   d.    
   Thus, when the operation rod  32   b  is pushed in the support body  32   c  as shown in  FIG. 14 , a portion U in contact with the guide member  32   e  and the guide groove  32   d  moves upwards within the guide groove  32   d , which causes the lock pin  32   a  to slide upwards. Thus, the engagement of the lock pin  32   a  and the lock hole  21   b  is canceled, making it possible to rotate the holding part  3 . 
   In the normal state, the operation rod  32   b  is urged by a spring  32   g  so as to protrude to the exterior of the support body  32   c . Here, the “normal state” means the state in which the operation rod  32   b  is not being operated. Thus, when the operation of the operation rod  32   b  is stopped, the portion U in contact with the guide member  32   e  and the guide groove  32   d  moves downwards within the guide groove  32   d  (See  FIG. 14 ), which causes the lock pin  32   a  to protrude to the retaining panel  21  side. Thus, the lock pin  32   a  and the lock hole  21   b  are engaged with each other to regulate the rotation of the holding part  3 . 
   In a state in which the lock pin  32   a  and the lock hole  21   b  cannot be engaged with each other, when the operation of the operation rod  32   b  is stopped, the lock pin  32   a  is maintained in a state in which it is in contact with the panel face portion of the retaining panel  21 . And, when the holding part  3  is rotated to the position where the lock pin  32   a  and the lock hole  21   b  are matched with each other, the lock pin  32   a  is automatically engaged with the lock hole  21   b  due to the tension of the spring  32   f . That is, solely by pushing the operation rod  32   b  into the holding part main body  31 , the lock state is canceled. When the operation of the operation rod  32   b  is stopped while rotating the holding part main body  31  with respect to the polishing panel body  2 , locking is automatically effected at the nearest lock position (the lock hole  21   b ). 
   In this way, in the polishing device  1  of the present invention, the mounting angle of the holding part  3  with respect to the polishing panel body  2  can be arbitrarily changed as desired by the operator. Thus, it is possible to perform polishing operation without having to hold the device in an irregular fashion. Further, due to the provision of the lock mechanism  32  which allows the polishing panel body  2  and the holding part  3  to be easily fixed at a predetermined rotating position, the mounting angle of the holding part  3  with respect to the polishing panel body  2  can be changed through an easy operation. 
   While in the above embodiment the polishing panel body  2  has bendably formed polishing surface end portions M 3 , it is naturally also possible to adopt a general-purpose polishing panel body in which the polishing surface M is formed of a flat plate. Further, while the holding part  3  of the above embodiment has a generally round configuration, the configuration of the holding part  3  is not restricted to the above-described one. 
   SECOND EMBODIMENT 
   Next, as a preferred embodiment of the polishing device of the present invention, a two-hand polishing device  1 A to be held by both hands when in use will be described. Since the construction of the polishing panel body  2  and the holding part  3  is the same as that of the above-described one-hand polishing device  1 , the description will be focused on the differences. The components which are the same as those of the first embodiment are indicated by the same reference numerals. 
   As shown in  FIG. 15 , the two-hand polishing device  1 A differs from the one-hand polishing device  1  in the size and configuration of the holding part main body  31 A. More specifically, swollen portions  34  coming into plane contact with the palm of the hand of the user are arranged in a straight line passing the axle  33  so as to be symmetrical with respect to the axle  33 . That is, the swollen portion  34  is formed at either end of the holding part  3 . Further, as in the one-hand polishing device  1 , the finger rest recess  35  is formed on either side of each swollen portion  34 . That is, the device is configured such that it provides the most stable holding state when the holding part  3  is held by both hands so as to be wrapped from both sides. 
   The lock mechanism  32  may be contained in one of the two swollen portions  34 . As in the above one-hand polishing device  1 , the engagement of the lock pin  32   a  and the lock hole  21   b  is canceled when the operation rod  32   b  is operated, permitting the holding part  3  to rotate. When the operation of the operation rod  32   b  is stopped, the lock mechanism  32  is placed in the locking state again. 
   THIRD EMBODIMENT 
   Next, as a modification of the above two-hand polishing device  1 A, a polishing device  1 B in which each swollen portion  34  can independently rotate will be described with reference to  FIG. 17 . The polishing device  1 B described below has substantially the same construction as that of the one-hand polishing device  1  and the two-hand polishing device  1 A, so that the description will be focused on the differences. The components which are common to the first, second, and third embodiments are indicated by the same reference numerals, and a description of such components will be abridged. 
   In this embodiment, the swollen portions  34  arranged in a straight line passing the axle  33  in the second embodiment can independently rotate. That is, while in the two-hand polishing device  1 A the swollen portions  34  are arranged in a straight line on either side of the axle  33 , the swollen portions  34  of this embodiment can independently rotate around the axle  33 . 
   More specifically, the holding part  3  is formed of two mutually independent holding part main bodies  31 , each of which is supported so as to be rotatable on the axle  33 . While in the first and second embodiments the axle  33  and the holding part main body  31  are fixed together, in this embodiment, the axle  33  is fixed to the polishing panel body  2  side, each holding part main body  31  being connected so as to be rotatable on the axle  33 . 
   Further, in the connecting portion X where each holding part main body  31  is connected to the axle  33 , there are provided cutouts (clearances) X 1  in order to avoid interference with the other holding part main body  31  in the case of rotation in the same direction. Due to these cutouts X 1  serving as clearances, the holding part as a whole can assume a V-shaped or a reverse V-shaped pattern. 
   Further, each holding part main body  31  is provided with the lock mechanism  32  as described above, and on the retaining panel  21  side there are provided a plurality of sets of lock holes  21   b  in correspondence with the lock pins  32   a  of the lock mechanisms  32 . Thus, each holding part main body  31  can be fixed at an arbitrary rotating position. 
   In this way, in the polishing device  1 B of this embodiment, the degree of freedom in terms of the holding angle for the holding part  3  is further increased as compared with the above-described two-hand polishing device  1 A, making it possible to further improve the operability of the polishing device  1 . 
   Next, an example of the operation method for the one-hand polishing device  1  of the present invention will be described. It is to be noted that the following operation method is only illustrated by way of example, and the operation method for the polishing device  1  of the present invention is not restricted thereto. 
   First, prior to the description of a specific operation method, an ideal polishing operation which puts no great strain on the operator will be described. A precondition for an ideal polishing operation allowing the operator to perform polishing without experiencing any fatigue is that in the condition in which the holding part  3  is held, the forearm and the back of the hand are arranged in a straight line. That is, in such a polishing operation, no unnecessary load is applied to the wrist when the arm makes a reciprocating movement in the polishing direction. 
   In view of this, in the following example of the preferred operation method, the above precondition is taken into account.  FIG. 18  shows the fixing angle of the holding part  3  when the polishing device  1  is moved obliquely, with the holding part  3  held by the right hand.  FIG. 19  shows the fixing angle of the holding part  3  when the polishing device  1  is moved obliquely, with the holding part  3  held by the left hand.  FIG. 20  shows the fixing angle when the polishing device  1  is held by the right hand and moved horizontally. 
   First, with reference to  FIG. 18 , an oblique polishing operation using the right hand will be described. In this polishing operation, it is recommended that the holding part  3  be fixed, with the swollen portion  34  of the holding part main body  31  being positioned on the front and left side with respect to the front side of the polishing panel body  2 , i.e., the upper side as seen in the drawing. 
   In this case, since the operator performs the operation with the right hand, the elbow is situated on the right-hand side of the polishing operation center C. Thus, when the holding part  3  is held in this state, the back of the hand and the forearm are aligned in a straight line, making it possible to hold the holding part  3  in a natural fashion. As a result, the operability is markedly improved especially in the directions indicated by arrows A 1  and A 2 . Further, also in polishing in the directions of arrows B 1  and B 2 , the twisting of the wrist can be reduced to a minimum, making it possible to perform operation mainly through horizontal movement of the forearm alone. Thus, there is no need to perform polishing operation at an unreasonable holding angle as in the case of an existing polishing device, enabling the user to perform the polishing operation very easily. 
   Next, the polishing operation with the left hand will be described with reference to  FIG. 19 . 
   In this polishing operation, it is recommended that the holding part  3  be fixed, with the maximum swollen portion  34   a  of the holding part main body  31  being positioned on the front and right side with respect to the front side of the polishing panel body  2 , i.e., the upper side as seen in the drawing. 
   In this case, since the operation is performed with the left hand, the elbow is situated on the left-hand side of the polishing operation center C. Thus, when the holding part  3  is held in this state, the back of the hand and the forearm are aligned in a straight line, making it possible to hold the holding part  3  in a natural fashion. As a result, the operability is markedly improved especially in the directions indicated by the arrows B 1  and B 2 . Further, also in polishing in the directions of the arrows A 1  and A 2 , the twisting of the wrist can be reduced to a minimum, making it possible to perform operation mainly through movement of the forearm alone. 
   Next, a polishing operation in which polishing is performed while horizontally reciprocating the polishing device with the right hand will be described with reference to  FIG. 20 . 
   In this polishing operation, it is recommended that the holding part  3  is fixed, with the maximum swollen portion  34   a  of the holding part main body  31  being positioned on the front and left side with respect to the front side of the polishing panel body  2 , i.e., the upper side as seen in the drawing. 
   In this case also, as in the above examples of the operation method, the back of the hand and the forearm are aligned in a straight line, making it possible to hold the holding part  3  in a natural fashion. As a result, while with an existing polishing device (the left-hand side in the drawing) it is necessary to twist the wrist greatly at the left end of the surface to be repaired (the left-hand side in the drawing), the polishing device  1  of the present invention allows operation mainly through horizontal movement of the forearm alone. Thus, the user is enabled to perform polishing operation easily without experiencing any fatigue or pain in the wrist. 
   The above-described embodiments of the present invention should not be construed restrictively. Various modifications are possible for those skilled in the art without departing from the gist of the invention as claimed.