Abstract:
The invention discloses a utility knife, including at least a utility knife body, which has a first end part and a second end part; the first end part is arranged with a first mounting bracket, and the second end part is arranged with a second mounting bracket. A first blade is arranged detachably on the first mounting bracket; a second blade is arranged detachably on the second mounting bracket. Users can select appropriate blades to work during operation, or alternatively use different blades to operate without replacing blades. When a blade on one end becomes non-serviceable, users can immediately switch to use the blade on the other end to continue operation, which prolongs the time of continuous work and enhances the efficiency.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to the field of manual tools, and particularly to a utility knife. 
       DESCRIPTION OF THE PRIOR ART 
       [0002]    A common utility knife structurally includes a handle for gripping, one end of which arranged with a cutting part, such as a blade, etc. The cutting part can be contained inside the handle when not in use. Such utility knives, having only one cutting part, have a rather limited and simplistic functionality, and are unable to satisfy the practical demand for its diversified usage. 
         [0003]    Of a utility knife with replaceable blades, the blade holder is adaptable to mount blades of different functionalities. To use a blade of a different functionality, just replace the original with a blade of above functionality. Besides, if a blade is worn out, it can be replaced with a new blade of identical functionality for continual usage. 
         [0004]    However, replacing blades is sometimes inconvenient, especially in certain working environment, such as operation at a high place like on a roof, in that usually one of the hands is reserved to hold on to some object to ensure safety, and normally two hands are needed for replacing blades, which would induce safety hazard. Moving to a safe place for blade replacement, however, would waste time. In some further situation that blades of different functionalities are used frequently for different operations, like using a trapezoidal blade ( FIG. 5 ) for incision and using a horn-shaped blade ( FIG. 6 ) for segmentation, frequent replacement of blades is inconvenient and trouble-some. 
         [0005]    Thus, technicians of this field endeavor to develop a utility knife which minimizes frequency of blade replacement. 
       SUMMARY OF THE INVENTION 
       [0006]    In view of the above defects with the prior art, the present invention aims to provide a utility knife with multiple blades for simultaneous use which minimizes frequency of blade replacement. 
         [0007]    In order to realize the above purpose, the invention provides a utility knife, including at least a utility knife body which has a first end part and a second end part, where the first end part is arranged with a first mounting bracket for holding a first blade, and the second end part is arranged with a second mounting bracket for holding a second blade. 
         [0008]    In an embodiment, the first blade and the second blade can be identical blades, or blades of different cutting functionalities. 
         [0009]    Further, the first mounting bracket and/or the second mounting bracket are in a first work position exposed outside of the utility knife body and in a second work position contained inside the utility knife body. 
         [0010]    In an embodiment, the first mounting bracket and/or the second mounting bracket which are in the first work position when in unfolded state and in the seconded work position when in folded state, connect pivotally to the utility knife body by pivots. In other embodiments, the first mounting bracket and/or the second mounting bracket can extend and retract relative to the utility knife body through an extendable mechanism. At least one mounting bracket locates in the first work position when in extended state and locates in the second work position when in retracted state. 
         [0011]    The present invention adopts the above structure, where mounting brackets are arranged respectively on the end parts of the utility knife body, and identical or different blades can be arranged detachably on mounting brackets, respectively. Users, especially those who work at high places in special environments, with limited freedom allowed to both hands, find it difficult to replace blades. While using the utility knife with blades at both ends according to the present invention, users can select an appropriate blade to work during operation, or alternatively use different blades to operate, so as to be able to work continuously without replacing blades. 
         [0012]    If mounting brackets are mounted with blades of identical type respectively, when a blade on one end becomes non-serviceable, users can immediately switch to use the blade on the other end to resume working, which prolongs the time of continuous work and enhances the efficiency. 
         [0013]    Referencing now to the figures, the conception, detailed structure and induced technical effect of the present invention will be expounded for due understanding of the purpose, characterizations and effects of the present invention: 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  shows a structural schematic view of an embodiment in an unfolded state. 
           [0015]      FIG. 2  is a structural bottom schematic view of the embodiment as shown in  FIG. 1 . 
           [0016]      FIG. 3  is a structural vertical schematic view of the embodiment as shown in  FIG. 1 . 
           [0017]      FIG. 4  is a structural schematic view of the embodiment as shown in  FIG. 1  in a folded state. 
           [0018]      FIG. 5  is a structural schematic view of the blade  21  as shown in  FIG. 1 . 
           [0019]      FIG. 6  is a structural schematic view of the utility knife  22  as shown in  FIG. 1 . 
           [0020]      FIG. 7  is another schematic view of  FIG. 1  in use. 
           [0021]      FIG. 8  is further schematic view of  FIG. 1  in use 
           [0022]      FIG. 9  is a structural schematic view of a second embodiment of the present invention in unfolded state. 
           [0023]      FIG. 10  is a structural schematic view of a third embodiment of the present invention in unfolded state. 
           [0024]      FIG. 11  is a structural vertical schematic view of the embodiment as shown in  FIG. 10 . 
           [0025]      FIG. 12  is a structural schematic view of the embodiment as shown in  FIG. 10  in folded state. 
           [0026]      FIG. 13  is a structural vertical schematic view of the embodiment as shown in  FIG. 10  in folded state. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0027]    As shown in  FIG. 1-2 , the first embodiment of the present invention includes a utility knife body  10 , which also functions as a handle part and has a first end part  101  and a second end part  102 . 
         [0028]    The first end part  101  is arranged with a first mounting bracket  11 , and a blade  21  is arranged detachably on the first mounting bracket  11 . 
         [0029]    The second end part  102  is arranged with a second mounting bracket  12 , and a blade  22  is arranged detachably on the second mounting bracket  12 . 
         [0030]    As shown in  FIG. 1 , in this embodiment, the first mounting bracket  11  is arranged pivotally on the utility knife body  10  by the pivot  103 . The first mounting bracket  11  is in a first work position exposed to the outside of the utility knife body when in unfolded state. 
         [0031]    Likewise, the second mounting bracket  12  is arranged pivotally on the utility knife body  10  by the pivot  104 , which is in a first work position exposed to the outside of the utility knife body when in unfolded state. 
         [0032]    A shown in  FIG. 2-3 , further, the utility knife body  10  is arranged with a retaining member  13  thereon and the first mounting bracket  11  is arranged with a retaining part  111  thereon engaging with the retaining member  13  for retaining purpose. 
         [0033]    In this embodiment, the retaining member  13  is a resilient steel sheet. When the first mounting bracket  11  is in unfolded state, the retaining member  13  bears against the retaining part  111  and keeps the first mounting bracket  11  stably in unfolded state to ensure smooth operation and also to avoid harming the user due to operation errors. 
         [0034]    As shown in  FIG. 4 , the first mounting bracket  11  is in a second work position contained inside the utility knife body  10  when in folded state. Likewise, the second mounting bracket  12  is in a second work position contained inside the utility knife body  10  when in folded state. 
         [0035]    As shown in  FIG. 5 , the blade  21  is a trapezoidal blade, whose thickness is between 0.3 mm and 1.0 mm Said blade  21  has on its back a clamping notch  211  arranged for snapping-fit with the first mounting bracket  11 . 
         [0036]    As shown in  FIG. 6 , in the above embodiment, the blade  22  is a horn-shaped blade having a different cutting functionality to a trapezoidal blade. 
         [0037]    Further, said blade  22  has on its back a clamping notch  221  arranged for snapping-fit with the second mounting bracket  12 . 
         [0038]    By designing the clamping notch  211  and clamping notch  221  with identical sizes and structures, the blades  21 ,  22  can be mounted interchangeably on mounting brackets  11 ,  12 . 
         [0039]    As shown in  FIG. 7 , during operation, users can keep the second mounting bracket  12  and the blade  22  in folded state, which is in the second work position. And the first mounting bracket  11  and the blade  21  can be rotated clockwise around the pivot  103  to switch to unfolded state, which is in the first work position for operation. 
         [0040]    When the working part needs to be switched during operation, as shown in  FIG. 8 , users can rotate anti-clockwise the first mounting bracket  11  and the blade  21  around the pivot  103  to switch to folded state, which is in the second work position. And the second mounting bracket  12  and the blade  22  are rotated anti-clockwise around the pivot  104  to switch to unfolded state, which is in the first work position for operation. 
         [0041]    The utility knife of the present invention has on both ends of its utility knife body arranged with mounting brackets  11 ,  12 , which are used for mounting different blades  21 ,  22 , allowing the present invention to satisfy the demands for different operations using different types of blades in practice. 
         [0042]      FIG. 9  shows the second embodiment of the present invention, this embodiment has a basically identical structure to the first embodiment, the difference of which lies in that the second mounting bracket  12  is mounted with an identical blade with what is mounted on the first mounting bracket  11 , such as the trapezoidal blade  21 . 
         [0043]    During operation, when the blade  21  on the first mounting bracket  11  becomes non-serviceable or drops down due to carelessness, users can resume working by using the other blade  21  on the second mounting bracket  12 , which prolongs the time of continuous work and enhances the efficiency. 
         [0044]      FIG. 10  and  FIG. 11  show another embodiment of the present invention. In this embodiment, the first mounting bracket  11  and the second mounting bracket  12  are arranged in the utility knife body  10  with the ability to extend and retract through an extendable mechanism. The mounting brackets  11 ,  12  are in the first work position when in unfolded state; and the mounting brackets are in the second work position when in folded state. 
         [0045]    The utility knife body  10  has a top surface  26  which is arranged with two elongated grooves  28  extending longitudinally along the utility knife body  10 . A pushing block  24  is arranged on the mounting brackets  11 ,  12 , which protrudes out of the top surface  26  of the knife  10 , convenient for holding down by hands to move longitudinally along the elongated groove  28 , so as to drive the mounting brackets  11 ,  12  to move longitudinally to extend out of or retract into the utility knife body  10 . For better result of gripping and reliability, the part of the pushing block  24  protruding out of the top surface  26  has a ridged periphery. 
         [0046]    Each elongated groove  28  has two positioning recesses  27   a;    27   b  arranged longitudinally thereon, where the positioning recess  27   a  locates adjacent to the end part of the utility knife body  10 , while the positioning recess  27   b  locates distantly from the end part of the knife  10 . Each pushing block  24  has a positioning block arranged thereon to engage respectively with the positioning recesses  27   a  and  27   b.  When the mounting brackets  11 ,  12  are in the second work position where the said supports are retracted into the utility knife body  10 , the positioning block coordinates with the positioning recess  27   b,  so as to stop the movement of the pushing block  24  while retaining the mounting brackets  11 ,  12  in the second work position. When using the blades  21  or  22 , firstly use a finger (e.g. a thumb) to push down and move the pushing block  24  to detach its positioning block from the engagement with the positioning recess  27   b,  and then to push forward the pushing block  24  so as to drive the relative mounting brackets  11 ,  12  to extend out of the utility knife body  10 . When the mounting brackets  11 ,  12  reach the first work position, release the force applied on the pushing block  24  to make the positioning block on the pushing block  24  to enter into the positioning recess  27   a  and to engage with said recess under the effect of a reset spring, so that the mounting brackets  11 ,  12  are not allowed to retract freely back into the utility knife body  10 . 
         [0047]    In order to prevent the mounting brackets  11 ,  12  from being unconsciously pushed out of the utility knife body  10  by operators or others, and from sliding out of the utility knife body  10  under unknown impact by other objects while inside a tool bag or pocket, the utility knife body  10  has on its both sides arranged with a lock block  25 . Only when users toggle the lock block  25  to switch it to unlocked position, the mounting brackets  11 ,  12  can be pushed out of the utility knife body  10 , and when the mounting brackets  11 ,  12  are pushed out of the utility knife body  10 , the lock block  25  will automatically switch back to lock position, which is realizable by setting a reset spring. When users pull the mounting brackets  11 ,  12  back into the utility knife body  10  after using, the lock block  25  can automatically lock the mounting brackets  11 ,  12  in the lock position under the effect of the reset spring, so as to prevent any induced security hazard due to negligence of users to toggle the lock block to lock position. Lock block  25  switches between the unlocked position and lock position under toggling of users. When the lock block  25  is moved to the lock position, the mounting brackets  11 ,  12  are respectively locked inside the utility knife body  10 ; while the lock block  25  is moved to the unlocked position, so that the lock to the mounting brackets  11 ,  12  are respectively released, the mounting brackets  11 ,  12  extend out of the utility knife body  10  by moving the pushing block  24 . 
         [0048]    In this embodiment, the top part of the mounting brackets  11 ,  12  are also arranged with lock members  23 , which are used to lock the blades  21 ,  22  respectively to the mounting brackets  11 ,  12 . The blade lock member  23  is a elongated resilient strip member, one end of which adjacent to the utility knife body  10  is fixed on the mounting brackets  11 ,  12 , and the other end is in a free state. In work positions, the blade lock member  23 , under the effect of the resilient force of its own, the free end pressures on the blades  21 ,  22  and keeps the blades  21 ,  22  on the mounting brackets  11 ,  12 . When the blades  21 ,  22  need to be detached for replacement, first the mounting brackets  11 ,  12  are extended out of the utility knife body  10 , and then use fingers to lift up the free end of the blade lock member  23 , releasing its pressure on the blades  21 ,  22 , so that the blades  21 ,  22  can be easily and swiftly detached from the mounting brackets  11 ,  12 . 
         [0049]    The above gives details of the preferable embodiments of the invention. It should be understood that with the general technique of this field, no inventive work is necessary as to make multiple amendments and changes according to conception of this invention. Therefore, all the technical schemes gained from logical analysis, deductions or limited experimentation based on the present invention by technicians in this field, should be considered within the protection range asserted in the Claims.