Machine tool generally means a dynamic machinery apparatus used for precisely cutting metal to produce metal elements for other machining centers. In order to fabricate a working piece the machine tool generates a relative motion between the working piece and a tool. The motion can be divided into main motion and feed motion. Through this relative motion machining can be done on the working piece. The conventional machine tools mainly can be divided into a stationary machine tool and a hand-held machine tool. The fixed type machine tool generally has a relatively larger size. Its operation mode is moving the working piece to the machine tool to perform machining. The machine tool is fixedly located on a workstation or work area, and stands alone by itself. The hand-held machine tool is formed in a smaller size and functions in another operation mode by moving it to the working piece to do machining. The machine tool can be held or braced by hands or suspended or mounted onto a rack, and can be easily carried to a working site.
With advance of technology the goods being used now follow a trend of slim and light. Fabrication technique also is more precise and delicate. Take operation of the hand-held machine tool as an example, it also has to be made smaller and operable easier in response to the prevailing trend. The conventional hand-held machine tools mostly have two end plates to hold a spindle coupled with a tool head. For instance, R.O.C. patent No. M323163 discloses a motor including mainly a casing, a rotor set, a stator set, an air fan set and a plurality of cooling tubes. The rotor set has a spindle extended outside a front end plate and a rear end plate of the casing. The stator set is held inside the casing to receive electric current to generate a magnetic field to drive the rotor set spinning. Such a design uses the front and rear end plates to hold the spindle, hence needs space to accommodate the two end plates. As a result, trying to shrink the size of the machine tool encounters constraints. Moreover, when in need to increase power output larger ball bearings have to be installed on the front and rear end plates, as a result the size of the machine tool also increases. All these cannot conform to the prevailing trend of slim and light.
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