Patent Publication Number: US-2019184471-A1

Title: Cutter fastening apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a cutter fastening apparatus, and more particularly, a cutter fastening apparatus that enables a cutter to be easily detached from the body and the collet. 
     2. Description of Related Art 
     A conventional cutter fastening apparatus comprises a body, a collet, a cutter, and a cap. The body has a front end, an installing hole, and an outer thread. The installing hole is formed through the front end of the body. The outer thread is formed around the front end of the body. The collet is mounted in the installing hole and has a front surface and a through hole, and the through hole is formed through the front surface of the collect. The cutter is mounted through the through hole of the collet. The cap is threaded with the outer thread of the body. The cap has a driving ring portion protruding from an inner surface of the cap. The driving ring portion contacts an outer surface of the collet, and this makes the cap detachable from the collet via the driving ring portion when the cap is detached from the body. Accordingly, the cutter fastening apparatus is easy to be detached. 
     However, when the conventional fastening apparatus is in use, the cutter would rotate at a high speed and the cap has the driving ring portion, and this makes the moment of inertia of the cutter unbalanced. The cutter would vibrate during rotation to negatively influence the accuracy of the cutter in the operating process. 
     To overcome the shortcomings of the conventional cutter fastening apparatus, the present invention provides a cutter fastening apparatus to mitigate or obviate the aforementioned problems. 
     SUMMARY OF THE INVENTION 
     The main objective of the present invention is to provide a cutter fastening apparatus that enables the cutter to be easily detached from the body and the collect. 
     The cutter fastening apparatus has a body, a collet, a cutter, and a cap. The body has an outer thread. The collet is mounted in the body and has an abutting groove formed in an outer surface of the collet and a through hole formed through a front surface of the collet. The cutter is mounted through and fixed to the through hole of the collet. The cap is screwed with the outer thread of the body and has a driving ring portion protruding from an inner surface of the cap and a balance groove formed in the inner surface of the cap and being adjacent to the driving ring portion. The cap has a clamping portion protruding from the inner surface of the cap and a holding portion protruding from the inner surface of the cap. 
     Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a cutter fastening apparatus in accordance with the present invention; 
         FIG. 2  is an exploded perspective view of the cutter fastening apparatus in  FIG. 1 ; 
         FIG. 3  is a cross sectional side view of the cutter fastening apparatus in  FIG. 1 ; 
         FIG. 4  is an enlarged perspective view in partial section of the cap of the cutter fastening apparatus in  FIG. 1 ; 
         FIG. 5  is a cross sectional side view of the cap in  FIG. 4 ; 
         FIG. 6  is a cross sectional front view of the cap along line  6 - 6  in  FIG. 5 ; 
         FIG. 6A  is an enlarged cross sectional front view of the cap in  FIG. 6 ; 
         FIG. 7  is another enlarged cross sectional front view of the cap in  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     With reference to  FIGS. 1 to 5 , a cutter fastening apparatus in accordance with the present invention comprises a body  10 , a collet  20 , a cutter  30 , and a cap  40 . 
     The body  10  has a front end  101 , a rear end  102 , an installing hole  11 , and an outer thread  12 . The installing hole  11  is formed through the front end  101  of the body  10 . The outer thread  12  is formed in an outer surface of the front end  101  of the body  10 . The collet  20  is connected to and fixed at the installing hole  11  of the body  10 . The collet  20  has an annular abutting groove  21  and a through hole  22 . The abutting groove  21  is formed in an outer surface of the collet  20 . The through hole  22  is formed through a front surface of the collet  20 . The cutter  30  is mounted through and fixed to the through hole  22  of the collet  20 . The cutter  30  has a mounting end  31  and a sharp end  32 . The mounting end  31  of the cutter  30  is a smooth rod and is mounted through and fixed to the through hole  22  of the collet  20 . The sharp end  32  of the cutter  30  is a sharp knife body and extends out of the through hole  22  of the collet  20 . 
     With further reference to  FIG. 3 , the cap  40  is screwed with the outer thread  12  of the body  10 . The cap  40  has a driving ring portion  41 , a balance groove  42 , a clamping portion  43 , and a holding portion  44 . The driving ring portion  41  protrudes from an inner surface of the cap  40 . The driving ring portion partly extends into the abutting groove  21  of the collet  20 . The balance groove  42  is formed in the inner surface of the cap  40  and is adjacent to the driving ring portion  41 . When the cutter fastening apparatus in accordance with the present invention is rotating, the balance groove  42  and the driving ring portion  41  achieve a dynamic balance effect. Furthermore, with reference to  FIGS. 6 and 7 , the clamping portion  43  and the holding portion  44  protrude from the inner surface of the cap  40 . The clamping portion  43  and the holding portion  44  are disposed on the inner surface of the cap  40  at a spaced interval. Preferably, the clamping portion  43  and the holding portion  44  are disposed along a diametrical line (D) of the inner surface of the cap  40 . 
     When the cutter fastening apparatus in accordance with the present invention is in use, since the balance groove  42  is formed in the inner surface of the cap  40 , the moment of inertia of the driving ring portion  41  and the moment of inertia of the balance groove  42  can be balanced. When the cutter fastening apparatus in accordance with the present invention is rotating, the cap  40  can rotate stably and can be kept from vibrating. Furthermore, with reference to  FIG. 6 , since the clamping portion  43  and the holding portion  44  protrude from the inner surface of the cap  40 , in the procedure of detaching the cap  40  from the body  10 , the clamping portion  43  and the holding portion  44  can hold and abut the collet  20  to prevent the collet  20  from falling to the ground. 
     The cutter fastening apparatus in accordance with the present invention has the balance groove  42 , so the driving ring portion  41  and the balance groove  42  can achieve moment balance. Furthermore, the design of the clamping portion  43  and the holding portion  44  can prevent the collet  20  from falling to the ground when the collect  20  is being detached from the body  10 . 
     Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.