Method for estimating the rotational speed of a tool mounted on a rotating spindle of a machine tool and such a machine tool

摘要

In a machine tool (1) comprising a rotating spindle (2) and a vision system (7) for acquiring images of a tool (3) mounted on the spindle, for each value (VC) of an interval (ICN) of preselected rotational speed values centered on a nominal rotational speed value (VN) of the spindle, an image acquisition period (TA) is determined, that is a multiple of the rotational period (TR) of the spindle calculated for that preselected speed value and compatible with the vision system, and, while the spindle is rotating at the nominal rotational speed, a representative couple of tool images that are temporally spaced apart from one another of the image acquisition period is obtained, in order to obtain an estimated speed value (VS), associated to the nominal speed value, by selecting that preselected speed value to which the representative couple of images that are the most similar to each other on the basis of a similarity rule corresponds.

主权项

1. A method for estimating the rotational speed of a tool mounted on a rotating spindle of a machine tool by using a visual system which acquires images of the tool while it is rotating; the method comprising the following steps:
rotating the spindle at a nominal speed value; positioning the tool in the visual field of the visual system; obtaining, by said visual system, representative couples of images of the tool; defining a first interval of preselected speed values of rotational speed that is substantially centred on the nominal speed value of rotational speed of the spindle; for each of said preselected speed values, determining a respective image acquisition period such that it is equal to a multiple of one rotational period of the spindle as calculated for that preselected speed value and compatible with said visual system; said images of the tool obtained by said visual system being, within each representative couple, temporally spaced apart from each other of the image acquisition period corresponding to one of said preselected speed values; and determining an estimated speed value to be associated with said nominal speed value as that preselected speed value, selected among all the preselected speed values, to which the representative couple of images that are the most similar to each other on the basis of a similarity rule corresponds.