Abstract: A method includes steps of: performing preparation-phase measurements on a spindle of a machine tool to generate normal-condition signals; establishing a reference model based on the normal-condition signals; generating abnormal-condition signals based on the reference model and a preset damage value; utilizing principal components analysis (PCA) to characterize the normal-condition and abnormal-condition signals to obtain normal and abnormal probabilistic models, determining normal-condition and abnormal-condition reference curves based on the normal and abnormal probabilistic models; determining an alert-triggering line based on the abnormal-condition reference curve; determining a permissible range between the alert-triggering line and the normal-condition reference curve; and generating a warning signal when it is determined that a detection value falls outside of the permissible range, wherein the detection value is obtained based on application-phase measurements performed on the spindle.

Abstract: A mini cutting bit includes a shank and a cutting part. The cutting part has a first spiral portion and a second spiral portion parallelly and twistedly formed thereon. The cutting part further has two chip removal flutes between the first and the second spiral portions. The first spiral portion has a first chip breaking flute on a top thereof while the second spiral portion has a second chip breaking flute. Widths of the first and the second chip breaking flutes are smaller than that of the tops of the first and the second spiral portions respectively.

Abstract: A mini cutting bit includes a shank, a cutting part and a bit tip, wherein the cutting part has opposite ends connected to the shank and the bit tip. The bit tip and the cutting part are made of different materials, and the bit tip is harder than the cutting part.

Abstract: A differential gear apparatus includes a housing, left and right shafts respectively having journal ends disposed in the housing and rotatable relative to the housing about a central axis to rotate wheels of a vehicle, a ring gear received in the housing and driven by a motor to rotate about the central axis relative to the housing, a central mount disposed at the center of the ring gear to be rotated therewith. Front and rear differential pinions and left and right bevel gears are journalled on front and rear bearing members on the central mount and left and right anti-frictional bearings in the housing, respectively. Each of the left and right bevel gears meshes with both the front and rear differential pinions, and is rotated with a respective one of the shafts so as to transmit rotational force thereto.