Handheld power tool with low speed

Abstract

A handheld power tool with low speed includes a housing, a middle sleeve shell and a front sleeve shell connected by threads on the exterior, and a pneumatic motor, a planet gear mechanism, a bearing, a cushion member and a fastened base in the interior. The pneumatic motor connects the planet gear mechanism through a driving shaft. The planet gear mechanism connects a grinding member located in the fastened base through a driven shaft and a flexible shaft. An outer flange portion is disposed around the fastened base. An inner flange portion is disposed on the front sleeve shell in order to press the outer flange portion while the middle sleeve shell is locked by the front sleeve shell so that the fastened base, the cushion member, the bearing, the planet gear mechanism and the pneumatic motor are fixed in a row.

What is claimed is: 
     
         1 . A handheld power tool with low speed comprising:
 a housing having a first opening with a first outer thread portion at an end thereof, a pneumatic motor with a driving shaft extending out of the first opening disposed in the housing;   a middle sleeve shell having a second opening and a third opening at two ends thereof, wherein the second opening is provided with a first inner thread portion to be fit with the first outer thread portion of the housing, and the third opening is provided with a second outer thread portion;   a planet gear mechanism disposed in the middle sleeve shell including a gear base provided with a plurality of planet gears and a gear circuit surrounding the gear base, wherein each of the planet gears is engaged with the driving shaft and the gear circuit respectively, and the gear base is provided with a driven shaft extending out of a bearing that is adjacent to the gear base;   a cushion member disposed in the middle sleeve shell with an end being adjacent to the bearing and an opposite end extending to the third opening, wherein the cushion member has a shaft hole provided with a coupling member connected between the driven shaft and a flexible shaft extending out of the third opening;   a fastened base adjacent to the cushion member with an outer flange portion disposed around a periphery of the fastened base;   a front sleeve shell having a fourth opening and a fifth opening at two ends thereof, wherein the fourth opening is provided with a second inner thread portion to be fit with the second outer thread portion of the middle sleeve shell, and the fifth opening is provided with an inner flange portion that presses the outer flange portion while the middle sleeve shell is locked by the front sleeve shell, whereby the fastened base, the cushion member, the bearing, the planet gear mechanism and the pneumatic motor are fixed in a row;   a side ring disposed adjacent to the front sleeve shell;   a grinding member connected with the flexible shaft including a head portion for grinding objects, a neck portion connected to the head portion and a ball-shaped base connected to the neck portion, wherein the ball-shaped base is provided with a pivot shaft to pivot on the fastened base for swinging so that a working angle of the grinding member is adjustable, the neck portion extends out of the side ring and is provided with a regulating portion for displaying an orientation of the grinding member;   a control ring disposed around the fastened base for locking the working angle of the grinding member.   
     
     
         2 . The handheld power tool with low speed of  claim 1 , wherein the middle sleeve shell is provided with an assembly ring for coupling with an auxiliary handle. 
     
     
         3 . The handheld power tool with low speed of  claim 1 , wherein the regulating portion is a flat plane cut on an arc surface disposed on the neck portion. 
     
     
         4 . The handheld power tool with low speed of  claim 1 , wherein the fastened base is provided with a recess for accommodating the ball-shaped base, the ball-shaped base is pivoted in the recess by the pivot shaft; a plurality of grooves are disposed on the ball-shaped base; each of two opposite sides of the recess is provided with a through hole accommodating a ball that can move along the through hole; the fastened base is surrounded by a C-shaped ring with two abutting portions disposed on an inner surface of the C-shaped ring; the C-shaped ring is surrounded by the control ring and is forced to open or close by turning the control ring; while the C-shaped ring is closed, the abutting portions push the balls so that the balls abut against the ball-shaped base in the groove in order to fix the grinding member; while the C-shaped ring is open, the abutting portions do not push the balls so that the grinding member can swing for adjustment to the working angle.