Abstract:
A shearing tool configured to be detachably connected to a portable oscillatory power tool is disclosed. The power tool includes a head housing and an output shaft with an axis. The output shaft extends outwardly from the head housing and is able to pivot back and forth about the axis. The shearing tool includes a fixed blade mounted relative to the head housing and a movable blade connected to the output shaft. The movable blade can pivot back and forth about the axis relative to the fixed blade. The fixed blade and the movable blade are connected to the portable power tool by a same fastening element. The shearing tool has simple operational steps and simple structure, thus to facilitate assembling.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a shearing tool, more particularly to a shearing tool configured to be detachably connected to a portable oscillatory power tool is disclosed. 
       BACKGROUND OF THE INVENTION 
       [0002]    An oscillatory power tool is a portable oscillatory power tool commonly used in this field. The operating principle is that the output shaft pivots back and forth about its own axis. Therefore, when the user installs different working heads at the free end of the output shaft, wherein the commonly applied working heads include straight saw blade, round saw blade, triangular disc sander and spade-shaped scraper, diversified operation functions such as sawing, grinding and scraping can be used to adapt to different working demands. 
         [0003]    Shearing is also one of the frequently used operation means. Generally, the shearing operation is achieved by a shearing tool. This shearing tool includes two blades which are pivoted together. The two blades have a knife-edge and the two knife-edges face each other. When the user opens the two blades relative to one another, the opening action of the shearing is done; the closing action of the shearing is done when the user closes the two blades relative to one another. Shearing function can be obtained in such way. 
         [0004]    Certainly, another kind of shearing mode commonly used is electric shearing tools with two blades. Generally, one blade is a fixed blade and the other one is a movable blade relative to the fixed blade. The movable blade connects with the transmission shaft and generates reciprocating movement under the action of a motor; while the other blade keeps still. Shearing function of the shearing tool is obtained via the reciprocating movement of the movable blade. 
       SUMMARY OF THE INVENTION 
       [0005]    It is an object of the present invention to provide a shearing tool. As an integrated attachment adapted for an oscillatory power tool, the shearing tool expands an application scope of the oscillatory power tool. It has a simple configuration and is easy to be assembled. 
         [0006]    To solve above problem, the present invention provides a shearing tool detachably connected to an oscillatory power tool, the oscillatory power tool comprising: 
         [0007]    a head housing; and 
         [0008]    an output shaft extending outwardly from the head housing and having an axis, the output shaft being configured to oscillate about the axis; 
         [0009]    the shearing tool comprising: 
         [0010]    a fixed blade fixed to the head housing; 
         [0011]    a movable blade connected to the output shaft and configured to oscillate about the axis with respect to the fixed blade. 
         [0012]    Preferably, the fixed blade and the movable blade are connected to the power tool by a same fastening element. 
         [0013]    Preferably, the fastening element comprises a bolt and configured to engage with the output shaft. 
         [0014]    Preferably, the shearing tool further comprises a connecting seat connected with the head housing, the connecting seat comprising a base portion and a locating portion extending from the base portion, the locating portion configured to partially cover the head housing. 
         [0015]    Preferably, the head housing is configured as an angular shape, and the locating portion comprises a U-shaped section matching with the head housing in a direction perpendicular to the axis of the output shaft and an arced section matching with the head housing in a direction along the axis. 
         [0016]    Preferably, the base is configured as a ring. 
         [0017]    Preferably, the shearing tool further comprises a connecting seat and a cover fixed to the connecting seat, the movable blade being located between the connecting seat and the cover. 
         [0018]    Preferably, the cover is ring shaped and comprises a first recess, a second recess, and a ring recess located at a centre of the cover, the first and second recess being arranged alternately in a circle direction of the cover with a step therebetween. 
         [0019]    Preferably, the movable blade comprises a mounting portion having a mounting hole engaging with the output shaft, a head portion having a knife-edge, and a connecting portion interconnecting the mounting portion and the head portion. 
         [0020]    Preferably, the mounting portion of the movable blade is configured as a ring shape and is accommodated in the ring recess. 
         [0021]    Preferably, the connecting portion is configured as a rectangular shape and has a width less than the first recess, thereby being accommodated in the first recess. 
         [0022]    Preferably, the connecting seat comprises a base portion and a locating portion extending from the base portion, the base portion being configured as a ring shape and comprising a bearing retainer located on an interior surface thereof and a bolt receiver located on an exterior surface thereof. 
         [0023]    Preferably, the fixed blade comprises a fixed portion having a bolt hole, a head portion having a knife-edge, and a curved portion interconnecting the fixed portion and the head portion, the bolt receiver penetrating the bolt hole for fix the fixed blade to the connecting seat. 
         [0024]    Preferably, the fixed portion has a width less than a width of the second recess of the cover, and is accommodated in the second recess. 
         [0025]    Preferably, the cover comprises a locating slot, the connecting base comprises a locating post corresponding to the locating slot, the fixed portion of the fixed blade further comprises a locating hole aligned with the locating slot, and the locating post penetrates through the locating hole into the locating slot. 
         [0026]    Preferably, the mounting portion of the movable blade contacts the bearing retainer of the connecting base surface-to-surface, and the head portion of the movable blade is disposed between the head portion of the fixed blade and the fixed portion. 
         [0027]    Preferably, the shearing tool further comprises a connecting base and a drive element, the connecting base interconnecting the head housing and the fixed blade, the drive element interconnecting the output shaft and the movable blade. 
         [0028]    Preferably, the connecting base is ring shaped and comprises a cavity for receiving the drive element, and a bearing is disposed between the connecting base and the drive element so that the drive element is able moving relative to the connecting base. 
         [0029]    Preferably, the shearing tool further comprises a block element mounted on the connecting base by a plurality of screw holes formed on the connecting base. 
         [0030]    Preferably, the connecting base further comprises a first bulge having a first fixed hole, and the fixed blade is mounted on the first bulge by a bolt. 
         [0031]    Preferably, the drive element has two opposite surfaces, one of the two surfaces defining a recessed portion, the other one of the two surfaces defining a plurality of bores between each two of which a locating protrusion is disposed. 
         [0032]    Preferably, the movable blade defines a through hole aligned with the bore and a locating hole aligned with the locating protrusion, and the movable blade is mounted on the drive element by a bolt. 
         [0033]    Preferably, the fixed blade is approximately trapezoidal shaped and comprises a fixed portion and a knife-edge, the knife-edge being located at a waist side of the fixed blade, the movable blade being configured as an L-shape and comprises two free ends, one of the two free ends defining a mounting portion, the other one of the two free ends being configured as an inverted trapezoidal shape and comprising a knife-edge at a waist side thereof, the two knife-edges overlapping each other. 
         [0034]    Preferably, the shearing tool further comprises a bracket, the bracket comprising a contacting portion, an upholding portion perpendicular to the contacting portion, and a projecting portion abutting against the fixed blade. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]      FIG. 1  is a perspective view of the oscillatory power tool fixed the shearing tool in accordance with the first embodiment of the present invention; 
           [0036]      FIG. 2  shows a perspective view of a head housing of the power tool according to  FIG. 1 ; 
           [0037]      FIG. 3   a  shows a perspective view of the shearing tool according to  FIG. 1  in front view; 
           [0038]      FIG. 3   b  shows a perspective view of the shearing tool according to  FIG. 1  in rear view; 
           [0039]      FIG. 4  is an exploded view of the shearing tool according to  FIG. 1 ; 
           [0040]      FIG. 5   a  is a front view of the shearing tool and the power tool according to  FIG. 1 ; 
           [0041]      FIG. 5   b  is a cross-section view of the shearing tool and the power tool according to  FIG. 1 ; 
           [0042]      FIG. 6   a  is a schematic view of the shearing tool, in which the movable blade moves left relative to the fixed blade; 
           [0043]      FIG. 6   b  is a schematic view of the shearing tool, in which the movable blade holds still relative to the fixed blade; 
           [0044]      FIG. 6   c  is a schematic view of the shearing tool, in which the movable blade moves right relative to the fixed blade; 
           [0045]      FIG. 7  is a perspective view of an oscillatory power tool fixed a shearing tool in accordance with a second embodiment of the present invention; 
           [0046]      FIG. 8  is a schematic view of a head housing of the power tool according to  FIG. 7 ; 
           [0047]      FIG. 9  is a perspective view of the shearing tool according to  FIG. 7 ; 
           [0048]      FIG. 10  is an exploded view of the shearing tool according to  FIG. 9 ; 
           [0049]      FIG. 11  is a vertical view of a connecting seat of the shearing tool according to  FIG. 9 ; 
           [0050]      FIG. 12  is a schematic view of the connecting seat viewed from an A direction according to  FIG. 11 ; 
           [0051]      FIG. 13  is a schematic view of a cover of the shearing tool according to  FIG. 9 ; 
           [0052]      FIG. 14  is a vertical view of the cover according to  FIG. 13 ; 
           [0053]      FIG. 15  is a front view of the shearing tool and the power tool according to  FIG. 9 ; 
           [0054]      FIG. 16  is a cross-section view of the shearing tool and the power tool according to  FIG. 9 ; 
           [0055]      FIG. 17  is a schematic view of the shearing tool according to  FIG. 9 , in which the movable blade moves left relative to the fixed blade; 
           [0056]      FIG. 18  is a schematic view of the shearing tool according to  FIG. 9 , in which the movable blade holds still relative to the fixed blade; 
           [0057]      FIG. 19  is a schematic view of the shearing tool according to  FIG. 9 , in which the movable blade moves right relative to the fixed blade; 
           [0058]      FIG. 20  is a cross-section view of the shearing tool along line B-B of  FIG. 17 . 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0059]    As shown in  FIGS. 1 and 2 , in the first preferred embodiment of the present invention, a shearing tool  1  adapted for shearing operations which can be applied to the oscillatory power tool is provided. The oscillatory power tool, designated to be Number  10 , comprises a cylindrical housing  11  and a head housing  12  connected at the front end of the housing  11 , wherein the head housing  12  has a right angle arrangement, an output shaft  13  (as shown in  FIG. 2 ) extends therethrough, the free end of the output shaft  13  is configured as a regular hexagon and has an axis X. A motor for providing driving force and a transmission assembly for transmitting torque are mounted inside the housing  11  of the oscillatory power tool  10 . A cable  14  is connected at the tail end of the housing  11  to supply power to the motor. When the motor is enabled and generates driving force, the torque of the driving force is transmitted to the output shaft  13 . Under the action of the torque, the output shaft  13  oscillates about the axis with the movement direction as shown in double-headed arrow A-A of  FIG. 1 . 
         [0060]    It shall be noted that, the oscillatory power tool  10  used herein is the commonly used oscillatory power tool in this field. The oscillatory power tool is a power tool making oscillatory movements based on the oscillatory principle. Generally, the motor drives the eccentric wheel connected on the motor shaft to rotate, a fork assembly is linked with the eccentric wheel in the horizontal direction, and the other end of the fork assembly is connected with the output shaft. When the eccentric wheel makes eccentric rotation, the fork assembly is driven to oscillate about the axis of the output shaft. Therefore, when the user configures working heads at the free end of the output shaft, the working head can also generate oscillatory movement. 
         [0061]    As shown in  FIGS. 3 and 4 , the shearing tool  1 , connected on the head housing  12 , is an integrated accessory detachably connected to the head housing  12 . It is connected with the output shaft  13  via a fastening element  600  (see  FIG. 5   b ). In the present invention, the fastening element  600  is a bolt fit for the corresponding threaded hole on the output shaft and is capable of being fastened. It is known to the person who skilled in this art, to achieve the same function by fastening means well-known in this field such as a pin or a spring. 
         [0062]    The shearing tool  1  comprises a connecting seat  2 , a drive element  3  mounted inside the connecting seat  2 , a fixed blade  4  connected on the connecting seat  2 , a movable blade  5  connected on the connecting seat disk  3  and a bracket  6 . The connecting seat  2  is in the shape of approximate cylinder. It includes a circular-ring side wall  21  and a cavity  22  enclosed by the side wall  21 . When the connecting seat  2  is connected to the head housing  12  of the oscillatory power tool  10 , the tail end of the head housing  12  is accommodated in the cavity  22 . Moreover, the output shaft  13  of the oscillatory power tool  10  is also accommodated in the cavity  22 . On the exterior of the side wall  21 , three screw holes  23  and one first bulge  25  are extended at an interval of 90°. The three screw holes  23  are used to fix with a block element  24  so as to seal and support the drive element  3 . A mounting hole  26  is configured on the first bulge  25  to connect the fixed blade  4  and the bracket  6  by a bolt. A second bulge  27  is extended on the exterior of the side wall  21  at an interval of 90° from the first bulge  25 . In addition, a second fixed hole  28  is set on the second bulge  27  to fix the connecting seat  2  with the head housing  12  of the oscillatory power tool  10 . 
         [0063]    It shall be noted that the second fixed hole  28  herein mainly plays a role of installation assistance. Based on the connection between the movable blade and the output shaft, a bolt can be also used for fixed connection to strengthen connection and installation effect. Certainly, the shearing tool can be installed and fixed only by the fastening element  600  without using such second fixed hole  28 . 
         [0064]    Corresponding to the output shaft  13 , the drive element  3  is set inside the connecting seat  2 , namely in the cavity  22 . And a bearing  30  is mounted between the side wall  21  and the drive element  3 . So that the drive element  3  can generate rotation relative to the side wall  21 . A recessed portion  31  is mounted on the side of the drive element  3  towards the output shaft  13  (as shown in  FIG. 2   a ). In this embodiment, the recessed portion  31  corresponding to the free end of the output shaft  13  is also in regular hexagon, thus the output shaft  13  can be accurately inserted into the recessed portion  31 . Two bores  32  symmetrically relative to the recessed portion  31  are mounted on the other side of the drive element  3 , and two locating protrusions  33  are symmetrically relative to the recessed portion  31  are configured between the two bores  32 . In the preferred embodiment, two bores  32  and two locating protrusions  33  are set respectively and arranged alternately. Certainly, their quantity is not limited in the present invention. 
         [0065]    As further shown in  FIG. 4 , the fixed blade  4  is mounted on the first bulge  25  on the side wall  21  of the connecting seat  2  by a bolt. The fixed blade  4  is configured as an approximately trapezoidal shape and comprises a fixed portion  41  and a knife-edge  42 . The knife-edge  42  is located at a waist side of the trapezoidal structure. The fixed blade  4  is made of flexible material which can be bent to certain shapes. In this way, when the fixed blade and movable blade have abrasion due to long-term operation, a clearance therebetween may arise easily. To prevent this, the fixed blade adopts flexible material and presses the movable blade by relying on other elements so that the fixed blade and the movable blade are always kept in a close contacting state. 
         [0066]    The movable blade  5  is configured as an L-shape and comprises two free ends. One of the two free ends defines a fixed portion  51 , a through hole  52  being aligned with the bore  32  and a locating hole  53  being aligned with the locating protrusion  33 . When the movable blade  5  is fixed onto the drive element  3 , localization is realized by inserting the locating protrusion  33  into the locating hole  53 . Afterwards, a movable bolt  5  passing through the through hole  52  is used to fix the movable blade to the drive element  3 . The other free end of the movable blade  5  is configured as an inverted trapezoidal shape relative to the fixed blade  4 . Its knife-edge  54  is also at a waist side thereof, thus the two knife-edges  42 ,  54  of the fixed blade  4  and the movable blade  5  overlap each other alternately. The drive element  3  connected with the movable blade  5  is rotatable relative to the connecting seat  2 , so the movable blade  5  is also rotatable relative to the fixed blade  4  which is connected with the connecting seat  2 . Thus the knife-edges  42 ,  54  are transmitted between an opening state and a closing state, realizing shearing function. 
         [0067]    In such a way, the fixed blade  4  and the movable blade  5  are integrated to be one unit. The center of the fixed portion  51  of the movable blade  5  is on the axis X of the output shaft  13 . The user can mount the shearing tool (a component of the whole set) to the oscillatory power tool or detach it from the power tool only by means of a fastening element  600 . 
         [0068]    Moreover, in the middle of the movable blade  5 , namely in the middle of the L-shaped structure, a through hole  55  is configured in the first bulge  25  corresponding to the connecting seat  2 . When the fixed blade  4  is installed on the first bulge  25 , the movement of the movable blade  5  may be held back since the bolt may raise protrusion. Therefore, the through hole  55  is set on the movable blade  5  to accommodate the bolt for fixing the fixed blade  4  in the through hole  55  so as to avoid the influence on the rotation of the movable blade  5 . 
         [0069]    As further shown in  FIG. 5 , the bracket  6  is mounted on the first bulge  25  outside the side wall  21  of the connecting seat  2  by a bolt. The bracket  6  is configured as an approximately L shape and comprises a fixed portion  61  connected with the first bulge  25  and an upholding portion  62  perpendicular to the fixed portion  61 . A projecting portion  63 , extended from the side of the upholding portion  62 , is closely contacted with the back of the fixed blade  4 . Because the fixed blade  4  is made of flexible material, the fixed blade  4  is always pushed towards the movable blade  5  to keep the fixed blade  4  always contacting with the movable blade  5 , thus guaranteeing the shearing effect. 
         [0070]    Moreover, the upholding portion  62  can be placed as a bracket on the workbench surface for shearing operation. It is convenient to the user. 
         [0071]    The specific structure features of the shearing tool in the present invention are as described above.  FIG. 6  ( 6   a - 6   c ) shows the schematic views of the operating principle of the power tool. As shown in  FIG. 6   b , when the oscillatory power tool  10  is not started, the output shaft  13  will not oscillate, thus the drive element  3  connecting the output shaft  13  will not oscillate either. The movable blade  5  connected on the drive element  3  is kept in the initial location, namely in the location with the angle formed between the two knife-edges of the movable blade  5  and the fixed blade  4  being 45° as shown in the figure. 
         [0072]    As shown in  FIG. 6   a , when the output shaft  13  drives the drive element  3  to oscillate clockwise, the movable blade  5  will oscillate towards the left side about the axis X, as shown in the figure. The knife-edge  54  moves upwards relative to the fixed blade  4 . In this way, the angle formed between the knife-edges is expanded to 47° to constitute an opening operation of the shearing movement. 
         [0073]    As further shown in  FIG. 6   c , when the output shaft  13  generates a reverse oscillation, namely the output shaft  13  drives the drive element  3  to oscillate anticlockwise, the movable blade  5  will oscillate towards the right side about the axis X, as shown in the figure. The knife-edge  54  moves downwards relative to the fixed blade  4 . In this way, the angle formed between the knife-edges is diminished to 43° to constitute a closing operation of the shearing movement. 
         [0074]    Certainly, the angle herein is indicated for the convenience of explanation only. It can be set to other values for realizing shearing function rather than limited thereby. 
         [0075]    The repeated oscillation of the output shaft  13  drives the drive element  3  to keep repeated oscillation either. Therefore, the movable blade  5  connected on the drive element  3  oscillate in the angle range above repeatedly, thus realizing shearing function. 
         [0076]    It shall be noted that, the fixed blade  4  of the shearing tool  1  is connected on the connecting seat  2  and the connecting seat  2  is further fixed on the head housing  12  of the oscillatory power tool  10 , so the fixed blade  4  keeps still all the time during shearing action, and the movable blade  5  oscillates relative to the fixed blade  4  only. 
         [0077]    As shown in  FIG. 7 , in the second embodiment of the present invention, a shearing tool  100  adapted for shearing operation which can be applied to the oscillatory power tool is provided. The oscillatory power tool, designated to be Number  10 , comprises a cylindrical housing  11  and a head housing  12  connected at the front end of the housing  11  and is configured as an angular shape (the left side of  FIG. 1  is defined as front end), wherein an output shaft  13  extends from the head housing  12 . As shown in  FIG. 8 , the free end of the output shaft  13  is in regular hexagon and has an axis X. The free end of the output shaft  13  further forms a ring-shaped flange  131 . 
         [0078]    As further shown in  FIG. 7 , a motor (not shown) for providing driving force and a transmission assembly (not shown) for transmitting torque are mounted inside the housing  11  of the oscillatory power tool  10 . A cable  14  is connected at the tail end of the housing  11  to supply power to the motor. When the motor is enabled and generates driving force, the torque of the driving force is transmitted to the output shaft  13 . Under the action of the torque, the output shaft  13  oscillates about the axis X with the movement direction as shown in double-headed arrow A-A direction of  FIG. 7 . 
         [0079]    As shown in  FIGS. 9 to 11 , the shearing tool  100 , connected on the head housing  12 , is an integrated accessory detachably connected to the head housing  12 . It is connected with the output shaft  13  via a fastening element  600  (see  FIG. 17 ). 
         [0080]    The shearing tool  100  comprises a connecting seat  200 , a cover  300  fixed to the connecting seat  200 , a fixed blade  400  connected to the connecting seat  200  and a movable blade  500  which is arranged between the connecting seat  200  and the cover  300  moves relative to the fixed blade  400 . 
         [0081]    The connecting seat  200  comprises a base portion  210  in approximate circular-ring shape and a locating portion  220  extending from the base portion  210 . A bearing retainer  230  is fixed inside the circular-ring base portion  210 , wherein the bearing retainer  230  is made of metal material and its diameter is similar to that of the flange  131  of the bearing retainer  230  so that the flange  131  can be fully accommodated in the bearing retainer  230  and the two parts are closely contacted. Several bolt receivers  240  are mounted outside the base portion  210  and in vertical direction along the head housing  12 . In this embodiment, there are three such bolt receivers  240  which are uniformly arranged around the base portion  210 . In addition, the connecting base  200  comprises a locating post  250  for fixing the cover  300 . 
         [0082]    As shown in  FIGS. 12 and 13 , the shape of the locating portion  220  is approximately similar to the lower part of the head housing  12 . A U-shaped section  221  is configured along the longitudinal direction of the head housing  12 , and similarly, an arced section  222  is mounted along the vertical direction of the head housing  12 . In this way, the locating portion  220  can cover the lower part of the head housing  12 . Under the joint action of the U-shaped section  221  and the arced section  222 , the connecting seat  200  can be rapidly fixed below the head housing  12  and free from aptness to shedding. 
         [0083]    As further shown in  FIG. 11 , the fixed blade  400  is fixed to the connecting seat  200 . It comprises a fixed portion  410  and a head portion  420 . They are connected by a curved portion  430  so that the fixed portion  410  and the head portion  420  are located in different planes respectively, thus a location for installing the movable blade  500  is reserved. On the fixed portion  410 , a bolt hole  440  and a locating hole  450  are set respectively. Moreover, a bolt receiver  240  passes through the bolt hole  440  to fix the fixed blade  400  to the connecting seat  200 . The locating post  250  passes through the locating hole  450  to give assistance to the fixation of the fixed blade  400 . On the head portion  420 , a knife-edge  460  is formed towards the connecting seat  200 . 
         [0084]    The movable blade  500  comprises a mounting portion  510 , a head portion  520 , and a connecting portion  530  interconnecting the mounting portion  510  and the head portion  520 . The mounting portion  510  is configured as an approximate ring shape and has a mounting hole  540  in regular hexagon for engaging with the regular hexagon at the free end of the output shaft  13 . The connecting portion  530  is configured as a rectangular shape and has a width d. It is provided with a groove  550  for reducing weight. A knife-edge  560  is formed on the head portion  520  towards the head portion  420 . The knife-edge  460  of the head portion  420  and the knife-edge  560  of the head portion  520  are relative to each other. When the head portion  520  moves relative to the head portion  420 , shearing function is realized. 
         [0085]    Also referring to  FIG. 14 , the cover  300  is configured as a ring. Several screw holes  340  are set corresponding to the bolt receiver  240  on the connecting seat  200 . A step is formed on the edge surface. It comprises a first recess  310  for accommodating the movable blade  500 , and a second recess  320  for accommodating the fixed blade  400  and a ring recess  330  for accommodating the mounting portion  510  of the movable blade  500 . It shall be noted that the width D 1  of the first recess  310  is larger than the width d of the movable blade connecting portion  530  of the movable blade  500 , so that the oscillation of the movable blade  500  is limited to the width D 1 . The width D 2  of the second recess  320  is lightly larger than that of the fixed portion  410  of the fixed blade  400 . The diameter D 3  of the ring recess  330  is slightly larger than that of the mounting portion  510  of the movable blade  500 . Moreover, the cover  300  comprises a locating slot  350  for inserting and fixing the locating post  250  on the connecting seat  200 . 
         [0086]    When the shearing tool is in use, the user shall place the movable blade  500  on the connecting seat  200 . At this time, the head portion  520  lies between the head portion  420  and the fixed portion  410  of the fixed blade  400 , and the mounting portion  510  of the movable blade  500  contacts the end surface of the bearing retainer  230  on the connecting seat  200 . Afterwards, the user installs the cover  300  accordingly, namely the locating post  250  is inserted into the locating slot  350  on the cover  300 , the connecting portion  530  of the movable blade  500  is accommodated into the first recess  310  of the cover  300 , the screw hole  340  is aligned with the bolt receiver  240  on the connecting seat  200  and the cover  300  is fixed onto the connecting seat  200  by means of a bolt. In this way, when the movable blade  500  oscillates relative to the fixed blade  400 , the mounting portion  510  of the movable blade  500  and the bearing retainer  230  on the connecting seat  200  generate end surface oscillation. The oscillation amplitude is limited by the width D 1  of the first recess  310  on the cover  300 . 
         [0087]    As shown in  FIGS. 15 ,  16  and  20 , when the shearing tool  100  is connected to the oscillatory power tool  10 , the mounting hole  540  on the movable blade  500  is engaged with the output shaft  13  by a fastening element  600 , and the bearing retainer  230  is engaged with the flange  131  on the output shaft  13 . When the output shaft  13  oscillates, the movable blade  500  connected on the output shaft  13  is driven to pivot back and forth either, while the fixed blade  400  keeps still. The knife-edges  460 ,  560  of the head portion  420  and the head portion  520  are contacted alternately, and the head portion  520  oscillates relative to the head portion  420 , thus realizing the shearing function. 
         [0088]    It shall be specially noted that, the shearing tool in the present invention requires one fastening element only for realizing the attaching and detaching of the integrated accessory since the fixed blade and the movable blade are integrated as a unit, thus avoiding the respective connection with the oscillatory power tool and the output shaft as if they are separate elements, and simplifying the installation of the fittings and improving the user convenience. 
         [0089]      FIGS. 17 to 19  show the schematic view of the operating principle of the shearing tool. As shown in  FIG. 18 , when the oscillatory power tool  10  is not started, the output shaft  13  will not oscillate, thus the movable blade  500  connected with the output shaft  13  will keep still in initial position rather than oscillate, namely is the position when the angle formed between the knife-edges of the movable blade  500  and the fixed blade  400  is α 1 , as shown in  FIG. 18 . 
         [0090]    As shown in  FIG. 17 , when the output shaft  13  oscillates clockwise, the movable blade  500  will oscillate clockwise about the axis X, the knife-edge  560  generates angular displacement relative to the fixed blade  400 . In this way, the angle formed between the two knife-edges is expanded to α 2  to constitute an opening operation of the shearing movement. As further shown in  FIG. 19 , when the output shaft  13  generates reverse oscillation, namely when the output shaft  13  oscillates anticlockwise, the movable blade  500  will oscillate about the axis anticlockwise, and the knife-edge  560  generates angular displacement relative to the fixed blade  400 . In this way, the angle formed between the two knife-edges is diminished to α 3  to constitute a closing operation of the shearing movement. Certainly, the angle herein is indicated for the convenience of explanation only, but not limited to this. It can be set to other values for realizing shearing function rather than limited by this. 
         [0091]    The oscillation of the output shaft  13  drives the movable blade  500  keeping oscillation either. The oscillation amplitude is within the angle range above. Repeat the operation in the same way above, shearing function can be obtained.