Patent Publication Number: US-6212977-B1

Title: Spring chuck

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a spring chuck, and more particularly to an improved spring chuck provided with a locking mechanism to hold two handles of the spring chuck at desired position, preventing the spring chuck from unexpected loosening during working. 
     2. Description of the Related Art 
     There are various types of spring chucks available in the markets. These spring chucks are, however, similar in their structural design and mainly include a spring to achieve the function of tightly clamping working pieces between two jaws thereof. Since there is not any auxiliary locking mechanism designed for such conventional spring chucks, jaws of these chucks tend to unexpectedly separate from each other when considerably thick working pieces, such as two planks, are clamped between the jaws for machining, such as cutting and drilling, and the spring chucks are subjected to vibration or external force during such machining. The quality of produced items would therefore be seriously and adversely affected. 
     It is therefore desirable to develop a locking mechanism for the spring chucks, so that the spring chucks provide safe and good clamping effect to ensure convenient use thereof and best production of desired items. 
     SUMMARY OF THE INVENTION 
     A primary object of the present invention is to provide a spring chuck having an auxiliary locking mechanism to lock handles of the spring chuck to a desired position, so that safe and firm clamping of working pieces between jaws of the chuck can be ensured. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The structure and technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein 
     FIG. 1 is a perspective of the spring chuck according to the present invention; 
     FIG. 2 is a plan view of the spring chuck of FIG. 1; and 
     FIG. 3 is another plan view of the spring chuck of FIG. 1 in a working state with handles thereof set in a locked position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Please refer to FIGS. 1 to  3 . A spring chuck  1  according to the present invention includes a locking mechanism  2  provided between a pair of handles, that is, a first handle  11  and a second handle  12  of the spring chuck  1 . 
     The locking mechanism  2  mainly includes a sleeve  21 , a shaft  22 , a brake  23 , and a compression spring  24 . 
     The sleeve  21  is fixedly connected at an upper end to a predetermined point on an inner side surface of the first handle  11  in a predetermined manner. The sleeve  21  defines an inner space  211  for an end of the shaft  22  to movably locate in the inner space  211  via a lower open end of the sleeve  21 . The lower open end of the sleeve  21  is provided at one side, preferably the side facing toward a front end (or jaws) of the spring chuck  1 , with a downward extended lug  212 . Another end of the shaft  22  is fixedly connected to a predetermined point on an inner side surface of the second handle  12 . 
     The brake  23  includes a handle  230 , a ring-shaped head  232  that forms a lower front portion of the handle  230 , and a U-shaped lug  231  upward extended from one side of the ring-shaped head  232  corresponding to the lug  212  of the sleeve  21 . The brake  23  is movably connected to the sleeve  21  by pivotally connecting the U-shaped lug  231  to the lug  212 , so that a predetermined distance exists between the lower open end of the sleeve  21  and the ring-shaped head  232  of the brake  23 . The ring-shaped head  232  defines a central hole  2321 , an inner diameter of which is slightly larger than an outer diameter of the shaft  22 . The compression spring  24  is mounted around the shaft  22  at a position between the lower open end of the sleeve  21  and the ring-shaped head  232  of the brake  23 . When the first and the second handles  11 ,  12  of the spring chuck  1  are not subjected to any external force pressing them toward each other, the compression spring  24  normally pushes the ring-shaped head  232  to pivotally turn away from the sleeve  21 . 
     When the compression spring  24  elastically pushes the brake  23  from the sleeve  21 , the pivotal connection of the U-shaped lug  231  to the lug  212  brings the ring-shaped head  232  and accordingly the central hole  2321  thereof to an inclined position relative to the shaft  22 , causing the shaft  22  to frictionally contact with an inner wall surface  2322  of the hole  2321 . Such frictional contact of the shaft  22  with the hole  2321  of the brake  23  in turn locks the first and the second handles  11 ,  12  to an unmoved state. 
     When a force is applied to push the handle  230  of the brake  23  toward the sleeve  21 , the central hole  2321  of the ring-shaped head  232  of the brake  23  is brought to a position aligned with the inner space  211  of the sleeve  21 . At this point, the shaft  22  separates from the inner wall surface  2322  of the central hole  2321  of the brake  23 , allowing the shaft  22  to freely move in the sleeve  21 . That is, the first and the second handles  11 ,  12  of the spring chuck  1  can be moved toward or away from each other. And, when the handle  230  of the brake  23  is released, the compression spring  24  immediately pushes the ring-shaped head  232  of the brake  23  to the inclined position to frictionally contact with the shaft  22  and accordingly locks the first and the second handles  11 ,  12  to a previously set position. 
     With the above arrangements, the spring chuck  1  of the present invention could be conveniently used to safely and firmly hold working pieces simply by pushing the brake handle  230  inward with a finger to free the chuck handles  11 ,  12  and releasing the brake handle  230  to lock the chuck handles  11 ,  12  to a desired position. 
     The present invention is by no means restricted to the above-described preferred embodiments, but covers all variations that might be implemented by using equivalent functional elements or devices that would be apparent to a person skilled in the art, or modifications that fall within the spirit and scope of the appended claims.