Abstract:
A grinder with easily installable/detachable grinding disc and a linkage effect. The grinder includes a main body in which a rotary shaft is disposed for a grinding disc mounted under a bottom end of the rotary shaft. A controlling button is switchable for powering on or off the grinder. A linking member is connected with the rotary shaft. A chucking mechanism is mounted in the main body for chucking the linking member. The chucking mechanism has a linking relationship with the controlling button. After powered off, the chucking mechanism is operable to chuck the linking member and prevent the rotary shaft from rotating. At this time, a user can conveniently replace the grinding disc. During replacement of the grinding disc, it is impossible to switch on the controlling button. When the chucking mechanism releases the linking member. The controlling button can be switched on. At this time, it is impossible for the chucking mechanism to chuck the linking member.

Description:
BACKGROUND OF THE INVENTION 
   The present invention is related to a grinder, and more particularly to a grinder in which the grinding disc can be easily replaced without using any tool. In addition, when replacing the grinding disc, the grinder is prevented from being powered on so as to avoid mis-operation. 
   A conventional grinder has a grinding disc mounted on a bottom section of the grinder. The grinding disc has a central threaded rod screwed with a rotary shaft of the grinder. The rotary shaft serves to drive the grinding disc to grind a work piece. 
   In operation, it is necessary to frequently replace the grinding disc. Conventionally, when replacing the grinding disc, a flat wrench is extended into the bottom of the grinder for clogging the rotary shaft of the grinder. Under such circumstance, the grinding disc can be unscrewed from the rotary shaft and taken off. Similarly, when installing the grinding disc, it is also necessary to fix the rotary shaft. Such replacement operation is quite inconvenient and time-consuming. 
   This inventor has developed various grinder structures in which the rotary shaft can be easily fixed for replacing the grinding disc without using any tool. However, it often takes place that when replacing the disc, the grinder is incautiously powered on. Under such circumstance, the components of the grinder may be damaged. 
   SUMMARY OF THE INVENTION 
   It is therefore a primary object of the present invention to provide a grinder with easily installable/detachable grinding disc and a linkage effect. The grinding disc of the grinder can be easily replaced without using any tool. In addition, when replacing the grinding disc, the grinder is prevented from being incautiously powered on so as to ensure safety. 
   The present invention can be best understood through the following description and accompanying drawings wherein: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a rear perspective view of a preferred embodiment of the present invention; 
       FIG. 2  is a longitudinally sectional view according to  FIG. 1 ; 
       FIG. 3  is another rear perspective view of the preferred embodiment of the present invention, showing that the controlling button is switched to a shutoff position and the shift button of the chucking mechanism is positioned in a chucking position; 
       FIG. 4  is a perspective exploded view according to  FIG. 1 ; 
       FIG. 5  is a bottom view according to  FIG. 1 ; 
       FIG. 6  is a sectional view taken along line  6 — 6  of  FIG. 5 , in which the trigger is not shown; 
       FIG. 7  is a perspective view of the chucking pillar of the preferred embodiment; 
       FIG. 8  is a sectional view taken along line  8 — 8  of  FIG. 7 ; 
       FIGS. 9 to 11  are similar to  FIG. 6 , showing the operation of the present invention and the cooperation relationship between the components of the present invention; 
       FIGS. 12 and 13  are sectional views of another embodiment of the present invention, respectively showing the engaging position and releasing position thereof; 
       FIG. 14  is a sectional view of still another embodiment of the present invention; 
       FIG. 15  is a sectional view of still another embodiment of the present invention; 
       FIG. 16  is a right view of still another embodiment of the present invention; 
       FIG. 17  is a sectional view taken along line  17 — 17  of  FIG. 16 ; 
       FIG. 18  is a sectional view taken along line  18 — 18  of  FIG. 17 ; 
       FIG. 19  is similar to  FIG. 17 , showing the operation thereof; 
       FIG. 20  is a rear perspective view of still another embodiment of the present invention; 
       FIG. 21  is a sectional view according to  FIG. 20 ; and 
       FIG. 22  is similar to  FIG. 21 , showing the operation thereof. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Please refer to  FIGS. 1 and 2 . According a first embodiment, the grinder of the present invention is a pneumatic grinder. Alternatively, the present invention is also applicable to an electric grinder. 
   The grinder  10  includes a main body  20 . A rear end of the main body  20  has an air inlet  21  for connecting with a high-pressure air source. Referring to  FIG. 2 , the main body  20  is formed with an internal pneumatic cylinder chamber  22  in which a pneumatic cylinder  24  is mounted. A rotary shaft  28  is disposed on the bottom of the main body  20  and connected with a central shaft  26  of a rotor  25  of the pneumatic cylinder. A bottom end of the rotary shaft  28  is formed with a thread hole  29 , whereby a grinding disc A (as shown by the phantom line) can be screwed with the rotary shaft. Referring to  FIG. 1 , a controlling button which is an intake button  30  (or an on-off switch for electric grinders) is movable between an activation position of  FIG. 1  and a shutoff position of  FIG. 3 . When the intake button  30  is positioned in the activation position, the high-pressure air can flow into a flow way  31  inside the main body  20  (as shown in  FIG. 2 ). 
   In use, as shown in  FIG. 2 , a user presses the trigger  34  to downward push a valve  36  and unblock the flow way  31 . At this time, the high-pressure air flows into the cylinder chamber  22  to drive the rotor  25  of the pneumatic cylinder  24 . The rotary shaft  28  is driven to drive the grinding disc A for grinding or buffering a work piece. 
   Referring to  FIG. 4 , a button room  40  is formed on one side of the main body  20 . A vertical slide way  42  is formed in the main body as shown in  FIG. 6 . A bottom end of the slide way extends to the bottom end of the main body. A top end of the slide way communicates with the button room  40 . An opening  44  is formed on the circumference of the main body  20  to communicate with the slide way  42  as shown in  FIG. 1 . 
   The intake button  30  is a rotary button disposed in the button room  40 . The intake button  30  is partially exposed to outer side for a user to turn. A recess  32  is formed on the circumference of the intake button  30 . 
   A linking member  50  is fixedly connected with bottom end of the rotary shaft  28  as shown in  FIGS. 2 and 6 . In this embodiment, the linking member  50  is a disc. Alternatively, the linking member can be an elongated plate or the like. The linking member  50  is rotatable with the rotary shaft. The circumference of the linking member is formed with several chucking sections  52 . 
   A chucking mechanism  60  is vertically movably mounted in the slide way  42  as shown in  FIG. 6 . The chucking mechanism  60  includes a chucking pillar  62  and a shift button  80  for controlling the chucking pillar  62 . Referring to  FIGS. 7 and 8 , the chucking pillar has a pillar body  64  and a dogging section  65  disposed at bottom end of the pillar body  64 . The pillar body  64  is fitted through a tunnel  68  of the dogging section  65 . A fixing pin  71  is passed through the pillar body and inlaid in an insertion split  72  of the dogging section, whereby the pillar body will not rotate when moving within the tunnel  68 . Two ends of a spring  74  respectively abut against a locating pin  75  of the pillar body  64  and the dogging section  65 . An arc recess  78  is formed on the circumference of upper half of the pillar body  64 . 
   By means of operating the shift button  80 , the chucking pillar can be controlled to move up and down. The shift button and the chucking pillar cooperate with each other to achieve a cam effect. Referring to  FIG. 4 , the shift button  80  has a cylindrical button body  82  and a shift section  84  connected therewith. The bottom face of the button body  82  has a cam section  86 . The button body  82  is fitted through the opening  44  of the main body  20  into the slide way  42  and fitted on the pillar body  64  of the chucking pillar  62 . The cam section  86  contacts with the locating pin  75  of the chucking pillar. The shift section  84  is positioned outside the main body  20 . The circumference of the intake button is snugly attached to the arc recess  78  of the chucking pillar  62 . In this position, the bottom end of the chucking pillar is higher than the linking member  50 . 
   A base seat  90  is fixedly connected with bottom end of the main body  20 . The dogging section  65  of the chucking pillar  62  is accommodated in a dent  94  of the base seat, whereby the chucking pillar can only move up and down without possibility of rotation. A lifting spring  95  is disposed in the dent of the base seat for lifting the chucking pillar  62  as shown in  FIG. 6 . 
   In common use, the intake button  30  of the grinder is switched to the activation position as shown in  FIGS. 1 and 6 . At this time, the power source is turned on, permitting the high-pressure air to flow into the main body. When pressing the trigger, the pneumatic cylinder  24  is driven to drive the rotary shaft  28 , the linking member  50  and the grinding disc to synchronously rotate for grinding or buffering a work piece. The shift button  80  of the chucking mechanism  60  is positioned in the releasing position as shown in  FIG. 1 . Referring to  FIG. 6 , the recess of the cam section  86  contacts with the locating pin  75  of the chucking pillar  62  and the arc recess  78  of the chucking pillar  62  is engaged with the intake button  30 . 
   When replacing the grinding disc, the present invention provides an idleproof and security linkage effect. A user must first shut off the power source and switch the intake button  30  to the shutoff position as shown in  FIGS. 3 and 9 , whereby the recess  32  is aligned with the chucking pillar  62 . At this time, the arc recess  78  of the chucking pillar is free from the body of the intake button and thus is freely movable. Then the shift button  80  is turned to the engaging position as shown in  FIGS. 3 and 10 . After the shift button is angularly displaced, the plane face of the bottom end of the cam section  86  contacts with the locating pin  75  of the chucking pillar  62  to drive and move the chucking pillar downward to an engaging position. At this time, the dogging section  65  of the bottom end of the chucking pillar is chucked in the chucking section  52  of the linking member  50 . Under such circumstance, the rotary shaft  28  is located without possibility of rotation, whereby the user can replace the grinding disc. 
   Referring to  FIG. 10 , the grinder is powered off so that when replacing the grinding disc, in the case that the user incautiously touches the trigger, the grinder will not be activated. Therefore, the mis-operation of the grinder is avoided to ensure safety. Also, the components of the grinder are protected from being damaged. 
   After the replacement is completed, the user must turn the shift button  80  back to the releasing position of  FIG. 9 . At this time, the chucking pillar  62  is pushed upward by the lifting spring  95  and restored to the releasing position. Then the intake button  30  is switched back to the activation position of  FIG. 6  so as to restart the grinder. 
   The protection design of the present invention is such that after the grinding disc is replaced, in the case that the user fails to restore the chucking mechanism and the intake button to the state of  FIG. 6 , that is, the grinder is still in the state of  FIG. 10  and the user doesn&#39;t notice that and intends to switch the intake button back to the activation position for activating the grinder, since the chucking pillar  62  chucks the recess  32  of the intake button  30 , therefore, it is impossible to switch the intake button. This idleproof measure reminds the user to first restore the chucking pillar to the releasing position and then switches the intake button back to the activation position. Accordingly, with the linking member  50  still chucked, the grinder is prevented from being incautiously powered on by the user. 
   Similarly, when replacing the grinding disc, in the case that the intake button  30  is still in the activation position of  FIG. 6  without being switched to the shutoff position of  FIGS. 9 and 10 , the chucking mechanism  60  cannot be moved to chuck the linking member  50 . Therefore, it is ensured that before the grinder is powered off, the rotary shaft and the linking member will not be locked due to mis-operation. 
   Moreover, in the case that the chucking section  52  of the linking member  50  is not positioned right under the chucking pillar  62 , the chucking mechanism  60  can be still operated to the engaging position. At this time, as shown in  FIG. 11 , the pillar body  64  of the chucking pillar is moved downward. When the dogging section  65  touches the top face of the linking member  50 , the pillar body  64  stops moving. Thereafter, the grinding disc is manually rotated to rotate the linking member  50 . When the chucking section  52  is moved to a position right under the chucking pillar  62  as shown in  FIG. 10 , the dogging section  65  is pushed by the spring  74  to move downward into the chucking section  52  to chuck the linking member. 
     FIGS. 12 and 13  show another embodiment of the grinder  100  of the present invention, in which the pillar body  104  of the chucking pillar  102  is free from any arc recess. Instead, the pillar body  104  is formed with a projecting stop section  106 . When the intake button  108  is positioned in the activation position of  FIG. 12 , the stop section  106  is stopped by the body of the intake button, whereby the chucking pillar  102  cannot move downward to the engaging position. 
   Reversely, as shown in  FIG. 13 , when the intake button  108  is switched to the shutoff position, the recess  110  is aligned with the chucking pillar  102  and the stop section  106  is not stopped. Therefore, by means of turning the shift button  112 , the chucking pillar is driven and moved downward to the engaging position for chucking the linking member  114 . It should be noted that in the embodiment of  FIG. 6 , the section B of the chucking pillar  62  above the arc recess  78  is also a structure equivalent to the stop section. 
     FIG. 14  is still another embodiment of the grinder  120  of the present invention, in which the chucking mechanism  130  also includes a chucking pillar body  132  and a shift button  134 . The shift button is totally identical to that of  FIG. 4 . The chucking pillar is movable within the slide way  138  of the main body  136 . 
     FIG. 14  shows that the shift button  134  drives the chucking pillar  132  downward to the engaging position for chucking the linking member  142 . When the shift button is restored to the releasing position, the chucking pillar  132  is pushed by a lifting spring  140  to restore to the releasing position so as to release the linking member from the chucked state. 
     FIG. 15  shows still another embodiment of the grinder  150  of the present invention, in which the shift button  160  also has a shift section (not shown) and a cylindrical button body  162 . The locating pin  166  of the chucking pillar  165  is fitted in a guide slot  164  of the button body  162 . The chucking pillar can only vertically move within the slide way without possibility of rotation. By means of turning the shift button  160 , the locating pin  166  of the chucking pillar is moved to a lower end L of the guide slot  164 . At this time, the chucking pillar  165  is moved downward to chuck the linking member  168 . Reversely, when the shift button  160  is turned to the releasing position, the locating pin  166  of the chucking pillar  165  is moved to the higher end H of the guide slot, the chucking pillar is moved upward to release the linking member. 
     FIGS. 16 to 19  show still another embodiment of the present invention, in which the grinder  170  is an electric grinder. A controlling button (electric switch) is mounted in a button room  173 . When the controlling button  172  is switched on as shown in  FIG. 17 , the grinder is powered on. When the controlling button  172  is switched off as shown in  FIG. 19 , the grinder is powered off. An outer end of a link  174  is pivotally connected with the controlling button  172 . When the controlling button  172  is switched on, the link  174  is driven and positioned in a stop position, an inner end of which extends into the slide way  176  as shown in  FIG. 17 . The stop section  184  of the chucking pillar  182  of the chucking mechanism  180  is stopped by the inner end of the link as shown in  FIG. 18 . Therefore, the chucking pillar  182  cannot be moved downward. Reversely, when the controlling button  172  is switched off, the link  174  is positioned in a releasing position with the inner end moving out of the slide way  176  as shown in  FIG. 19 , the chucking pillar  182  is not stopped by the link, whereby a user can move the chucking pillar  182  downward to chuck the linking member  185 . 
   Moreover, when the chucking pillar  182  is moved downward to the engaging position, the stop section  184  is positioned at a height shown by phantom line of  FIG. 18  to stop the inner end of the link  174 , and the link cannot be moved into the slide way  176 . Accordingly, when replacing the grinding disc, the grinder cannot be powered on. 
     FIGS. 20 to 22  show still another embodiment of the present invention, in which the chucking mechanism can be any of those of the above embodiments. Referring to  FIG. 21 , the circumference of the controlling button  210  is formed with a radial conic guide channel  212 . The depth of the guide channel is tapered from one end to the other end. In addition, a small slide way  204  is formed in the main body  202  of the grinder  200  to communicate with the button room  206  and an opening  208  of rear side of the main body. A link  215  is disposed in the small slide way  204  and movable along the small slide way. A spring  216  is disposed in the small slide way. In normal state, the spring  216  lifts the link  215 . 
   When the controlling button  210  is positioned in the activation position as shown in  FIGS. 20 and 21 , the link  215  is positioned in a stop position with bottom end protruding into the opening  208 . Under such circumstance, the shift section  222  of the shift button  220  is stopped by the link  215 , whereby a user cannot operate the chucking mechanism. 
   When the controlling button  210  is positioned in the shutoff position as shown in  FIG. 22 , the deeper end of the guide channel  212  is aligned with the small slide way  204 . The link  215  is pushed upward by the spring  216  to a releasing position and the top end of the link  215  is moved into the deeper end of the guide channel  212 . Under such circumstance, the bottom end of the link no more stops the shift button  220 , permitting a user to shift the shift button to the engaging position, whereby the chucking pillar  224  is moved downward to chuck the linking member  226 . At the same time, the bottom end of the link is stopped by the button body  228  of the shift button from moving downward so that the user cannot switch on the controlling button. 
   Besides, referring to  FIGS. 4 and 6 , the main body  20  is formed with a through hole  37  communicating with the interior of the main body. A cock  38  is screwed in the through hole. In the case of failure of the chucking mechanism, a user can take off the cock  38  and extend an iron bar through the through hole  37  into the main body for chucking the chucking section  52  of the linking member  50 . At this time, the grinding disc can be replaced. 
   According to the above arrangement, the rotary shaft can be easily fixed without using any tool. Therefore, it is more convenient to replace the grinding disc. Also, the present invention is equipped with a linkage mechanism. Before the grinder is powered off, it is impossible to chuck the rotary shaft. Moreover, during replacement of the grinding disc, it is impossible to power on the grinder. Accordingly, when replacing the grinding disc, the grinder is prevented from being incautiously activated; when the rotary shaft is chucked, the grinder will not be activated so as to avoid danger and injury as well as damage of the grinder. 
   The above embodiments are only used to illustrate the present invention, not intended to limit the scope thereof. Many modifications of the above embodiments can be made without departing from the spirit of the present invention.