Pneumatic grinder

Abstract

The present invention provides 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; the coupling mechanism of the tilting head and the main body is simplified into a single component--retaining cover having two counter revolving oriental threads for securing, meanwhile the sizes of said main body and the driving gear are shortcut; 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.

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'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.about.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.

Claims

I claim:

1. A pneumatic grinder, comprised of a main body housing a pneumatic motor at the inside from the front end, by fitting the locating shaft of the rotor into the back bearing at the inside of the main body, and a space ring put on the coupling shaft at the front end of said rotor, and a front cover holding said space ring at the inside, and the retaining cover securing on the front tip end of said main body; wherein, said retaining cover has an inner housing for holding said front cover in and pushing and locating said pneumatic motor in place, the coupling shaft has a thread portion built on the tip end for securing the driving gear, which is located at the inside of said front bearing with the small end for clamping and locating the bearing, said front bearing is located the inside of the tilting head with the outer surface for keeping the concentricity with said coupling shaft, and said tilting head is secured on the inner threaded hole of said retaining cover with the outer thread portion, thereby as screwing said retaining cover into the main body to retain the front cover, simultaneously to fasten the tilting head and to gear the driving gear to the spindle gear located on the spindle for driving the spindle in high speed simultaneous spinning.

2. A pneumatic grinder as claimed in claim 1, wherein said main body has a shaft tube with a bearing housing at the back end for holding in a bearing in.

3. A pneumatic grinder as claimed in claim 1, wherein said retaining cover has an inner thread at the inside hole and an outer thread at the external surface, the said both threads have different revolving orient each other.

4. A pneumatic grinder as claimed in claim 1, wherein, the main body has an external thread built on the outer terminal end, the retaining cover has two counter revolving oriental inner threads for securing on the external threads of said main body and said tilting head to get locking function as above-mentioned structure in claim 3.

5. A pneumatic grinder as claimed in claim 1, wherein, said rotor including shoots is shaped by molding in injection casting directly.

6. A pneumatic grinder as claimed in claim 1, wherein, the forcing slots on the surface of said rotor are molded in injection casting directly.

7. A pneumatic grinder as claimed in claim 1, wherein, the coupling shaft, the space ring, and the locating shaft of said rotor can be obtained by turning in a whole piece, the segment between the space ring and the locating shaft may be cut into polygon bar, the shoot shaft and shoots are obtained by molding in injection casting directly.

8. A pneumatic grinder as claimed in claim 1, wherein, said rotor including the shoot shaft and shoots is molded in plastic injection mold.

9. A pneumatic grinder as claimed in claim 7, wherein, said rotor including the shoot shaft and shoots is molded in plastic injection mold.