Abstract:
A saw blade clamping device has a first clamping device for clamping a first working element and a second clamping device for clamping a second clamping element, wherein the first clamping device and the second clamping device are parallel to each other and mounted to a transmission controlling mechanism. The two clamping devices can be controlled by the transmission control mechanism to can not only clamp a single saw blade but to allow for replacement of the single saw blade by double saw blades without changing the clamping system, which enables the replacement of the saw blade to be more convenient and quick.

Description:
RELATED APPLICATION DATA 
       [0001]    This application claims the benefit of CN 201110316300.7, filed on Oct. 18, 2011, and CN 201110316298.3, filed on Oct. 18, 2011, the disclosures of which are incorporated herein by reference in their entirety. 
       BACKGROUND 
       [0002]    This disclosure relates to a saw blade clamping device and the operation method thereof, which pertains to the technical field of electric tools. 
         [0003]    In a conventional electric cutting tool, a saw blade is mounted to the tool by a clamping device, and controlled and driven to move by a transmission device for a cutting operation. According to various work pieces to be cut, some electric cutting tools adopt a single saw blade to cut relative hard materials, such as wood, steel tube, and copper tube, while some electric cutting tools adopt double saw blades to cut relatively soft materials, such as sponge, foam, temperature preserving glass and fiber material. The prior mechanisms for clamping double saw blades can only clamp double saw blades, and if it is required to clamp a single saw blade, the clamping portion must be replaced, hence, the prior mechanism is not convenient for use. 
       SUMMARY 
       [0004]    The following discloses a saw blade clamping device, which can not only clamp a single saw blade, but also can replace the single saw blade with double saw blades to cut soft materials without replacing the clamping device, thereby improving the using state of the tool and the convenience and speediness of replacing the saw blade. 
         [0005]    More particularly, the following describes a saw blade clamping device comprising a first clamping device and a second clamping device, the first clamping device and the second clamping device being parallel to each other and mounted to a transmission control mechanism for converting a rotational motion of a motor to a reciprocating motion of the saw blade clamping device, wherein either of the first clamping device and the second clamping device is used to clamp a first working element, and the first clamping device and the second clamping device are jointly used to clamp a second working element different from the first working element. 
         [0006]    The first working element may have an engagement portion for engaging with either of the first clamping device and the second clamping device, and the second working element may have two engagement portions for engaging with the first clamping device and the second clamping device respectively. 
         [0007]    The first working element may have a handle portion which may be chosen from the following combination: the handle portion is L-shaped and has a projection along a longitudinal axis of a housing in the direction toward the motor; the handle portion is U-shaped and has a groove along the longitudinal axis in the direction away from the motor; and the handle portion is T-shaped and has a first edge and a second edge, and the handle portion being provided with a convex portion respectively on the first edge and the second edge in a direction vertical to the longitudinal axis of the housing. 
         [0008]    The transmission control mechanism may comprise a sun gear mounted to an output shaft of the motor and engaged with a planet gear, the planet gear engaged with an inner gear ring and a planet carrier, a rotating shaft connected to the planet carrier, a cam shaft mounted to the outer circumference of the rotating shaft and connected to the rotating shaft by an arresting pin, and a first sliding rod and a second sliding rod mounted to two cam portions of the cam shaft respectively, the first clamping device and the second clamping device mounted to the first sliding rod member and the second sliding rod member respectively. 
         [0009]    The rotating shaft may be mounted into a gearbox by a first oil-retaining bearing and a second oil-retaining bearing. 
         [0010]    A sliding rod may be mounted into a gearbox by a first sliding bearing and a second sliding bearing, and the first sliding rod may be mounted into the gearbox by a third sliding bearing and a fourth sliding bearing. 
         [0011]    A first roller may be connected to the second sliding rod by a roller pin a and a second roller may be connected to the second sliding rod by a second roller pin, the first and second rollers being clamped to the cam portion as a pair and a third roller may be connected to a first sliding rod by a third roller pin and a fourth roller may be connected to the first sliding rod by a fourth roller pin, the third and fourth rollers being clamped to the cam portion as a pair. 
         [0012]    The clamping device may comprises a clamping device body having a long groove for accommodating a saw blade therein, a locating hole arranged in the portion of the saw blade extending into the long groove, a cylindrical groove for accommodating a steel ball arranged in a direction vertical to the locating hole, and a pressing plate mounted into the clamping device body, the pressing plate comprising a concave portion accommodating the steel ball and having a slanting surface as its lower end. 
         [0013]    The pressing plate may be connected to a releasing button. 
         [0014]    The pressing plate may be provided with a pressing spring at the bottom thereof. 
         [0015]    An operation method of a saw blade clamping device may include the steps of pressing a releasing button and inserting a first working element into either of a first clamping device or a second clamping device, releasing the releasing button, engaging the engagement portion of the first working element with the first clamping device or the second clamping device, starting a motor so that the rotational motion of the motor is converted into the reciprocating motion of the first working element by a transmission control mechanism, stopping the motor, pressing down the releasing button, removing the first working element and inserting a second working element different from the first working element into the first clamping device and the second clamping device, releasing the releasing button, so that the two engagement portions of the second element are respectively engaged with the first clamping device and the second clamping device, and starting the motor so that the rotational motion of the motor is converted into the reciprocating motion of the second working element by the transmission control mechanism. 
         [0016]    As will become apparent, the disclosed embodiments can control two clamping devices by a transmission control mechanism, that is to say, the present invention can not only clamp a first working element, e.g., a single saw blade, but also can replace it by a second working element, e.g., double saw blades, without replacing the clamping system, which enables the replacement of the saw blade more conveniently and quickly. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a front view of an exemplary saw blade clamping device constructed according to the description that follows; 
           [0018]      FIG. 2  is a top view of the saw blade clamping device; 
           [0019]      FIG. 3  is a schematic view of an exemplary releasing button; 
           [0020]      FIG. 4  is a sectional view showing the clamping state of the clamping device taken along B-B of  FIG. 1 ; 
           [0021]      FIG. 5  is a sectional view showing the releasing state of the clamping device taken along B-B of  FIG. 1 ; 
           [0022]      FIG. 6  is a sectional view taken along C-C of  FIG. 1 ; 
           [0023]      FIG. 7  is a schematic view illustrating the saw blade clamping device clamping the first working element; 
           [0024]      FIG. 8  is a schematic view illustrating the saw blade clamping device clamping the second working element; 
           [0025]      FIG. 9  is a schematic view illustrating the structure of an exemplary handle portion of the working element of the saw blade clamping device; 
           [0026]      FIG. 10  is a schematic view of the clamping device having a reciprocating stroke A; 
           [0027]      FIG. 11  is a schematic view illustrating that a distance B between the clamping portion and the nail portion of the saw blade; and 
           [0028]      FIG. 12  a schematic view illustrating that a maximal distance C between the two separated saw blades and a distance D between the clamping portion of one slaw blade and the nail portion of another saw blade. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]    Turning to  FIG. 1 , illustrated is a front view of a clamping device according to the description that follows. The clamping device is intended for use in association with a power tool that includes a motor  21  and a transmission control mechanism to which the clamping device is coupled. A working element, namely a saw blade, is mounted to the clamping device. 
         [0030]      FIG. 2  is a top view of the saw blade clamping device. A first clamping device and a second clamping device are mounted to the transmission control mechanism in a manner parallel to and offset with respect to each other. The transmission control mechanism includes a sun gear  20  which is mounted to an output shaft of the motor  21  and engaged with a planet gear  18 . The planet gear  18  is engaged with an inner gear ring  19  and a planet carrier  17 . A rotating shaft  26  is connected to the planet carrier  17 . A cam shaft  28  is mounted to the outer circumference of the rotating shaft  26  and connected to the rotating shaft  26  by an arresting pin  29 . A second sliding rod component  3  and a first sliding rod component  23  are respectively mounted to two cam portions  2801  of the cam shaft  28 . The first clamping device and the second clamping device are respectively mounted to the first sliding rod component  23  and the second sliding rod component  3 . When the cam portions  2801  drive the sliding rod components, the cam portions will be subject to an axial force. The cam portions are supported by a first end surface bearing  27  and a second end surface bearing  30  so as to reduce the friction between the end surfaces of the cam portions and oil-retaining bearings. 
         [0031]    The rotating shaft  26  is mounted within a gear box  32  by a first oil-retaining bearing  25  and a second oil-retaining bearing  31 . A second sliding rod  10  is mounted within the gear box  32  by a first sliding bearing  11  and a second sliding bearing  16 . A first sliding rod  24  is mounted within the gear box  32  by a third sliding bearing  33  and a fourth sliding bearing  34 . A first roller  13  is connected to the second sliding rod  10  by a first roller pin  12 , and a second roller  15  is connected to the second sliding rod  10  by a second roller pin  14 . The first roller  13  and the second roller  15  are clamped to the cam portion  2801  as a pair. A third roller  38  is connected to the first sliding rod  24  by a third roller pin  39 , and a fourth roller  40  is connected to the first sliding rod  24  by a fourth roller pin  41 . The third roller  38  and the fourth roller  40  are clamped to the cam portion  2801  as a pair. 
         [0032]    The second clamping device includes a second clamping device body  9  having a long groove for accommodating a saw blade therein. A locating hole  201  is formed in the portion of the saw blade extending into the long groove as shown in  FIG. 4 . A cylindrical groove for accommodating a steel ball  6  is formed in a direction vertical to the locating hole  201 . A pressing plate  5  is mounted into the second clamping device body  9 . The pressing plate  5  comprises a concave portion  501  for accommodating the steel ball  6  and has a slanting surface  502  as the lower end of the concave portion  501 . The pressing plate  5  is provided with a pressing spring  7  at the bottom thereof. The pressing plate  5  is connected to a releasing button  43  as shown in  FIG. 3 , and the releasing button  43  protrudes out of the gear box  32  so as to facilitate the operation. 
         [0033]    The process of the energy transmission of the transmission control mechanism is as follows: the motor  21  drives the sun gear  20 , the sun gear  20  drives the planet gear  18 , the planet gear  18  drives the planet carrier  17 , the planet carrier  17  drives the rotating shaft  26 , the rotating shaft  26  drives the arresting pin  29 , the arresting pin  29  drives the cam shaft  28 , the cam portion  2801  of the cam shaft  28  then drives the second sliding rod member  3  and the first sliding rod member  23 . As a result, the second sliding rod component  3  drives the second saw blade  2  and the first sliding rod component  23  drives the first saw blade  22 . 
         [0034]    The configuration of the first clamping device is the same as that of the second clamping device. 
         [0035]      FIGS. 3-6  show the clamping operation of the clamping device. The housing  46  supports a arresting plate  45  and the releasing button  43 , wherein the arresting plate  45  supports a button spring  44 , and the button spring  44  presses the button  43  laterally. The pressing plate  5  supports a fifth pin  47  which may slide in the arresting groove  901  of the second clamping device body  9  so as to limit the pressing plate. 
         [0036]    The method for obtaining the releasing state includes pressing the releasing button  43  so that the releasing button  43  presses the pressing plate  5 . When the pressing plate is pressed, the concave portion  501  of the pressing plate is opposite the steel ball  6 , and the steel ball may slide into the concave portion  501  of the pressing plate. When the steel ball  6  is disengaged from the locating hole  201  of the saw blade the saw blade may be removed from the second clamping device body  9 . 
         [0037]    The method for obtaining the clamping state from the releasing state includes the second saw blade  2  being inserted. When the locating hole  201  of the second saw blade  2  is opposite the steel ball  6 , the releasing button  43  is released. At this time, the releasing button  43  is reset under the lateral pressing force of the button spring  44 , and the pressing plate  5  is reset under the lateral pressing force of the pressing spring  7 . Thus, the slanting surface  502  of the pressing plate will push the steel ball  6  to press the locating hole  201  laterally and the second saw blade  2  is then clamped and cannot be removed. 
         [0038]    The clamping mechanism of the present invention not only can clamp a single saw blade to cut hard material, but also can clamp double saw blades to cut soft material. Referring to  FIGS. 7-8 ,  FIG. 7  shows that either of the clamping devices may be used to clamp the conventional first working element, i.e., the single saw blade, for example, a saw blade of a reciprocating saw.  FIG. 8  shows that the two clamping devices cooperate to clamp the second working element, i.e., double saw blades, thus it enables the two saw blades to move relatively back and forth, thereby performing a cutting operation and cutting soft materials. 
         [0039]    The first working element, i.e., the single saw blade may be the second saw blade  2 , which includes a handle portion. The handle portion may be selected from the group consisting of an L-shaped handle portion having a projection  51  extending along the longitudinal axis of a housing and towards the motor, an U-shaped handle portion having a groove  52  extending along the longitudinal axis of the housing and away from the motor, and a T-shaped handle portion having a first edge  53  and a second edge  54  each of which has a projection  55  extending along a direction vertical to the longitudinal axis of the housing. The saw blade with a T-shaped handle portion can not be directly clamped by the clamping device mentioned in the above embodiments. It needs a clamping device which can clamp the saw blade with a T-shaped handle portion to clamp the single saw blade with a T-shaped handle portion or double saw blades with a T-shaped handle portion. 
         [0040]    It is well known to the person skilled in the art that the first and second working elements may also be a file, a blade or a grinding tool, which can perform different operations such as cutting, grinding, etc. 
         [0041]    Auto clamping requirements of the clamping device may be explained by referring to  FIGS. 10-12 . Given that the reciprocating stroke of the clamping device is A, the distance between the clamping portion and the nail portion of the saw blade is B, the maximal distance between the two separated saw blades before assembly is C, then the distance between the clamping portion of one saw blade and the nail portion of the other saw blade is D, in order to enable the double saw blades to be mounted on the clamping device, the device will be started when one saw blade is clamped in position and the other saw blade is not clamped in position, and the other saw blade can be clamped automatically under the action of the reciprocating sliding rod. According to the requirements, it is divided into four circumstances as follows: 
         [0042]    When the two clamping devices are completely aligned with each other, that is to say, A=0, the states are as follows: 
         [0043]    1. When the two saw blades are assembled after aligned with each other, it needs B≧0; 
         [0044]    2. When the two saw blades are assembled after separation, it needs B≧C; generally, C=A+1 mm, thus B≧A; 
         [0045]    When the two clamping devices are completely separated, that is to say, A=stroke, the states are as follows: 
         [0046]    1. When the two saw blades are assembled after alignement with each other, it needs B≧A; 
         [0047]    2. When the two saw blades are assembled after separation, it needs B≧A+C; generally, C=A+1 mm, thus B≧ 2 A. Therefore, given each states, it is advantageous that B≧ 2 A. 
         [0048]    The above-described embodiments are presented by way of example only and are not intended to restrict the present invention. Rather, the claimed invention is intended to have a scope which would encompass equivalent replacements and/or transformations of elements described herein.