Patent Publication Number: US-2004058631-A1

Title: Pneumatic grinder

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to a pneumatic grinder, and more particularly to a reformed structure of a pneumatic grinder, by changing pneumatic motor&#39;s structure and positions of bearings.  
       [0003] 2. Description of Prior Art  
       [0004] In accordance with the conventional pneumatic grinder in the market so far, the most of them are divided into two kinds—tilting head type (as shown in FIG. 1 and FIG. 2) and straight type (as shown in FIG. 3 and FIG. 4) in the grinding head structure, therein their driving styles are almost same, the only a bit difference is on the cramping way of the grinding component; the energy of driving spinning is to take the advantage of compressed air led in from the inlet  11  or  21 , then via air valve  12  or  22  the compressed air enters said pneumatic motor  13  or  23  to push the blades  14  or  24  to move, and simultaneously to bring up rotor  15  or  25  spinning; said pneumatic motor  13  or  23  has a front cover  131  or  231  and a back cover  132  or  232 , in which a pair of bearings  133 ,  233  and  134 ,  234  bear up said rotor  15  or  25  from the coupling shaft  151  or  251  and the locating shaft  152  or  252  separately; but whatever the conventional pneumatic grinders in the both structures may generate eccentric vibration and be poor concentricity as follows:  
       [0005] 1. Tilting Head Pneumatic Grinder:  
       [0006] Referring to FIG. 1 and FIG. 2, a conventional tilting head pneumatic grinder  10  is shown, in which said pneumatic motor  13  is retained by securing a retaining ring  16  on the tip end of said main body  17  for tightly pushing the front surface of said front cover  13 , for driving the grinding head or locating said front bearing  133  in place, a driving gear  18  is secured on the tip of said coupling shaft  151 , and simultaneously to press tightly the terminal end of said bearing  133 , meanwhile the teeth portion of said driving gear  18  is extended into the inside of the tilting head  19  for gearing to the spindle gear  192  of the spindle  191 , and said tilting head  19  and said retaining ring  16  are fastened on tip end of said main body  17  by securing a retaining cover  171 ; by driving said pneumatic motor  13  to spin, via gearing transportation of said driving gear  18  and said spindle gear  192 , said spindle  191  can spin at 20000 r/min. at least, further to drive the grinding tool  193  to spin in high speed.  
       [0007] In above-mentioned driving mechanism, the driving gear  18  may often generate shake and poor gearing condition with the spindle gear  192  so that the whole body is shaken and striking phenomenon happens between the both gearing gears to bring up poor running further to shortcut service life; the explored sake is that the suspended length (about 39 mm) of said driving gear  18  from the front end of said bearing  133 , meanwhile because this length includes the front cover  131 , retaining ring  16  locating said front cover  131 , the flange of said tilting head  19  and the retaining cover  171  securing said tilting head  19  and retaining ring  16  in architecture, so the suspending length of said driving gear  18  is unable to be cut shorter, therefore over length must create shaking phenomenon, meanwhile the suspended driving gear  18  without any support has to generate shake phenomenon at the tip end under the high speed spin.  
       [0008] On the other hand, the coupling connection of said driving gear  18  and the tip end of said coupling shaft  151  is designed into secure joint, in which the back lash must be existed in securing connection, and when the combined central axis has a bit of deviation, the eccentric rotation may be happened, especially at high speed spinning striking phenomenon must be occurred. Therefore, the engaging friction and interruption phenomena between said driving gear  18  and said spindle gear  192  may be occurred by said shake caused by eccentric spin, over suspending length of said driving gear  18  and gearing deviation, so as to create over laude of noise, affect the output power of the spindle  191  relatively, and increase relatively product percent defective.  
       [0009] The said driving mechanism is belong to small power device, when output power is increased, the sizes of every part may be increased too relatively, the length of said driving gear  18  is relatively increased, so that the spinning deviation and shaking scales must be increased too, the strike and noise are relatively improved too, therefore any same sized pneumatic grinder outputting relative bigger power has not turned out. Additionally, for fastening said tilting head  19  on the main body  17 , via two parts—said retaining ring  16  and said retaining cover  171 , the combination process is divided into two steps for finishing, and the parts may take much manufacturing time (especially cutting inner and outer threads) relatively, the production cost may be relatively increased; this assembly mechanism—via two parts must occur length increasing, this is main sake of causing over length of the driving gear  18 .  
       [0010] 2. Straight Head Pneumatic Grinder:  
       [0011] A conventional straight head pneumatic grinder  20 , referring to FIG. 3 and FIG. 4, is shown, wherein the pneumatic motor  23  is located by the securing retaining ring  26  via the front cover  231 , then secure the retaining cover  271  for fastening; the coupling shaft  251  is secured with the spindle  28  at the tip end directly, via a clamping nut  281  said spindle  28  is connected to a grinding tool  29 , so it is obvious that the front cover  231  and the back cover  232  are not fastened tightly axially in the inside of the main body  27  besides the retaining ring  26 , but securing connection exists a bit of back lash, therefore when at high speed spinning shake may be easily created, and the coupling shaft of the rotor  25  is suspended out of the front bearing  233  of the front cover  231 , and secured to the spindle  28 , so the securing joint portion may have error of concentricity existing so that the spindle  28  running at high speed (20000 r/min.) may bring all the parts on it to eccentric shaking, additionally plus the shaking coming from the front and back covers  231   232 , the shake is enough big to affect the concentricity and cutting accuracy of said grinding tool  29 , this is a vital sake that the running speed can not be further improved.  
       [0012] 3. Shortcomings of the Rotor Mechanism:  
       [0013] Referring to FIG. 1 to FIG. 4, the conventional rotor  15  or  25  is manufactured by turning the coupling shaft  151  or  251  segment, the shoot shaft  153  or  253  segment and the locating shaft  152  or  252  firstly, then milling shoots  154  or  254 ; when milling cutting shoots  154  or  254 , because they are narrow and deep, the milling tool has to keep in a small amount of feed at a low speed, and every rotor  15  or  25  has 4 to 6 shoots  153  or  253  (depending on the output power and rotation speed), therefore the cutting efficient of the shoots  154  or  254  is became obvious, and the production cost is quite high; on the other hand, for facilitating milling, the shoots  154  or  254  cut into said shoot shaft  153  or  253  from the terminal end at the coupling shaft side are in opening state, then turning a block ring  155  or  255  putting on the coupling shaft  153  or  253  for blocking the opening grooves; in assembling, said blocking ring  155  or  255  is placed between the front cover  131  or  231  and the shoots  153  or  253  for preventing they from friction.  
       OBJECTS AND SUMMARY OF THE INVENTION  
       [0014] It is therefore a main object of the present invention to provide a pneumatic grinder connected to a driving gear or spindle at the tip end of the coupling shaft, in which a bearing is set upon the front portion for anti-eccentric-shaking, improving the concentricity of the grinder, in order to suit higher running speed smoothly and higher gearing accuracy.  
       [0015] It is a next object of the present invention to provide a pneumatic grinder, in which the rotor is made of magnesium-aluminum alloy, aluminum alloy, zinc alloy, tin or plastic by injection casting for simplifying procedure and reducing manufacturing cost simultaneously.  
       [0016] The third object of the present invention is to provide a pneumatic grinder, in which the rotor and the shoots on it are formed in a single process in the injection casting simultaneously, in order to improve manufacturing speed and reduce cost.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0017]FIG. 1 is a sectional view of a conventional tilting head pneumatic grinder.  
     [0018]FIG. 2 is an exploded view of the conventional tilting head pneumatic grinder.  
     [0019]FIG. 3 is an exploded view of a conventional straight head pneumatic grinder.  
     [0020]FIG. 4 is a sectional view of the conventional straight head pneumatic grinder.  
     [0021]FIG. 5 is an exploded solid view of the present invention.  
     [0022]FIG. 6 is a sectional view of the present invention.  
     [0023]FIG. 7 is an exploded solid view showing the retaining ring in the embodiment of the present invention.  
     [0024]FIG. 8 is a sectional view showing the retaining ring in the embodiment of the present invention.  
     [0025]FIG. 9 is a sectional view showing a straight head pneumatic grinder in the second embodiment of the present invention.  
     [0026]FIG. 10 is a sectional view showing the stone cutting application embodiment of the present invention.  
     [0027]FIG. 11 is an exploded solid view showing the rotor of the present invention.  
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
     [0028] Referring to FIG. 5 and FIG. 6, a pneumatic grinder  30  provided of the present invention is comprised of a main body  31  having a shaft tube with a bearing housing  310  at the back end for holding in a bearing  341 , a pneumatic motor  32  loaded into the inside of said main body  31  wherein a rotor  33  of said pneumatic motor  32  is located in place by fitting the back end locating shaft  332  into said bearing  341 , and putting a ring  35  embedded into a front cover  36  and a bearing  39  sequentially on the front coupling shaft  331 , and a retaining cover  37  securing on the front end of said main body  31  with one end so that an inside housing  371  of said retaining cover  37  holds said front cover  36  and via it to locate axially said pneumatic motor  32 , a driving gear  38  secured on the thread portion at the front tip end of said coupling shaft  331  and fit into said bearing  39  with the back small end for locating, and said bearing  39  housed at front end of the inside of the tilting head  40  so as to keep the concentricity of said tilting head  40  and said coupling shaft  331 , said tilting head  40  connected with the retaining cover  37  by securing the thread portion  401  to the inner threaded hole  372 , in the said retaining cover  37  the inner thread of the hole  372  having a counter rotary thread with the outer thread on it so that the tilting head  40  can be rotated in any angle as un-securing up the retaining cover  37 , thereby as screwing said retaining cover  37  into the main body  31  to retain the front cover  36 , simultaneously to fasten the tilting head  40  and to gear the driving gear  38  to the spindle gear  42  located on the spindle  41  for driving the spindle  41  in high speed simultaneous spinning.  
     [0029] In accordance with above-mentioned, the present invention has some feathers as follows:  
     [0030] 1. Stable Driving Gear:  
     [0031] Referring to FIG. 5 and FIG. 6, the driving gear  38  is fitted into the inside of the bearing  39 , meanwhile the bearing  39  is located on the coupling shaft  331  and in the inside of the tilting head  40 , so the driving gear  38  is got to be supported directly without overlong suspending length, and the concentricity of the located position is greatly improved, even if running under high speed, the eccentric shaking phenomenon will not happen, simultaneously the gearing accuracy is improved, and relatively to improve transmission efficient and service life.  
     [0032] Referring to FIG. 9 and FIG. 10, a straight head type embodiment of the present invention is shown, wherein the spindle  63  of the straight head pneumatic grinder  60  or the spindle  72  of a stone cutting machine  70  is fitted into the bearing  39  directly as same as the way of said driving gear  39  with the small end  631  or  721  for locating the coupling shaft  621  and the spindle  63  or  72 , meanwhile improving the accuracy of concentricity, even if running under high speed, the eccentric shaking phenomenon will not happen, simultaneously the gearing accuracy is improved, and relatively to improve transmission efficient and service life.  
     [0033] 2. Simplifying the Coupling Mechanism of the Tilting Head and the Main Body:  
     [0034] The coupling mechanism is simplified relative to the conventional—from two components to only one—retaining cover  37 , as shown in FIG. 5 and FIG. 6, taking the advantage of two couple of different revolving oriental inner and outer threads instead of the conventional three to finish coupling the tilting head  40  to the main body  31 , so the thread cutting cost and component cost are saved, meanwhile in combination the single component—retaining cover  37  makes the assembly process simple and rapid, and the combination and manufacture cost are reduced too.  
     [0035] Additionally, referring to FIG. 9 and FIG. 10, the retaining cover  66  replaces the conventional two components—retaining ring  26  and the retaining cover  271  as shown in FIG. 3 and FIG. 4, as same as above-mentioned to simplify components, to make the assembly process simple and rapid, and to reduce the combination and production costs.  
     [0036] 3. Shortcutting the Driving Gear:  
     [0037] Due to simplifying the coupling mechanism of the tilting head  40  and the main body  31  into a single component—the retaining cover  37 , and loading the bearing  39  on the driving gear  39  directly, and simplifying the structure and shape of the front cover  36  and back cover  34 , both of the thicknesses are decreased, the front cover  36  is pushed by the retaining cover  37  from the terminal side to locate the pneumatic motor  32  in the inside of the main body  31 , it not only shortcuts the whole length of the main body  31 , but also the length of the driving gear  38  is also shortcut relatively (about 8˜15 mm) and the rigidity is improved, so that the tip end of it will not shake even under high running speed, and simplifying and shortcutting every components makes the part production cost reduce relatively and improve the production competition in the market.  
     [0038] Additionally, referring to FIG. 7 and FIG. 8, in this embodiment the retaining cover  50  couples and fastens the tilting head  40  on the main body  31  by securing on the outer thread  311  on the tip end of the main body  31  and outer thread of the tilting head  40  respectively with the inner different revolving oriental threads  51   52 , in the same way to get fastening and simplifying component function.  
     [0039] 4. Innovation Method of Manufacturing Rotor:  
     [0040] a.) The rotor  33 , as shown in FIG. 5, is made of magnesium-aluminum alloy, aluminum alloy, zinc alloy, tin, and molded in injection casting to get shaped rotor  33  including shoots  33  directly, then turning the both ends—the coupling shaft  331  and locating shaft  332  and the ring  35 , and the forcing slots  334  are molded on the outer surface of the rotor  33 , not only reduce the weight of the rotor  33 , but also increase the front face area, besides the blades  335  receive the pushing pressure of the compressed air, the forcing slots  334  also accept the drive coming from the compressed air so that the front face area of the rotor  33  is increased, therefore the rotor  33  creates the power relatively to be gone up coordinately.  
     [0041] b.) Referring to FIG. 11, the coupling shaft  81 , the space ring  82 , and the locating shaft  83  of said rotor  80  can be obtained by turning in a whole piece, in this way the steel material is used in a small size so that the production cost is lower, the segment between the space ring  82  and the locating shaft  83  may be cut into polygon bar  84  (or other shapes, or surface indentation treatment); and the shoot shaft  85  and the shoots  851  are molded in injection casting directly, it is made of magnesium-aluminum alloy, aluminum alloy, zinc alloy, tin; or made of plastic in injection molding directly without milling shoots  851 , so that the process of manufacturing rotor  80  is simple and rapid, and the production cost of it is efficiently reduced.  
     [0042] The present invention can be applied into variety pneumatic tool machine, just as straight head pneumatic grinder, tilting head pneumatic grinder, pneumatic stone cutting machine, pen type pneumatic grinder and so on, and other fields in the range of utilizing this technology.