Geometrical instruments – Gauge – Movable contact probe – per se
Patent
1983-03-24
1985-12-03
Haroian, Harry N.
Geometrical instruments
Gauge
Movable contact probe, per se
33558, 33172E, 33172D, 33169C, G01B 728
Patent
active
045558574
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a method for the accurate setting of machine tools using a feeler head which is moved to touch a reference surface or edge of the workpiece to be machined and a device for carrying out the method.
For the accurate setting of machine tools with the objective of accurately determining the centre of a machine tool spindle over the workpiece to be machined, it is generally known to employ mechanically and electromechanically operating feeler devices, which are frequently also referred to as null point receivers or edge feelers. There is, for example, an apparatus which is equipped with optical display means which, however, lights up only at the moment of touch contact with a surface to be machined. Such an apparatus is equipped with a contact ball located at its lower end which triggers the signal when going down and touching the surface.
Commercially available edge feelers attain an accuracy of approximately 0.01 mm when driven in, i.e. on location finding of reference surfaces or edges. During this process, the lower part of the feeler is first pushed out of the running axis of the rotating working spindle by light finger pressure. By slow approach to the contacting surface, the oscillating movement becomes increasingly smaller. On attainment of coaxiality in the upper and lower part, the lower part is displaced along the workpiece surface. The position of the surface contacted relative to the axis of the working spindle then corresponds to the radius of the feeler head with the accuracy tolerance quoted above. However, in many cases, this does not satisfy the required setting accuracy.
The invention is based on the task of providing a new adjustment method for the most accurate setting of machine tools and a device for carrying out the method, a substantially higher setting accuracy with the smallest possible expenditure of time being attainable by this means.
The solution according to the invention is distinguished by the fact that, using a method of the type mentioned at the beginning, the feeler head is slowly approached to the surface or edge to be touched until the contact of the rotating feeler head with the surface or edge to be contacted corresponds to a rotational angle of the feeler head which is greater than 180.degree. but smaller than 300.degree., 180.degree.<.alpha.<300.degree., where .alpha. is the contact angle, that is the angle which corresponds to the contact distance on the periphery of the feeler head. The centre of the machine tool spindle is set most advantageously, i.e. most accurately, when the contact angle=210.degree..
To carry out the method according to the invention, the most suitable feeler device is one consisting of a housing with an electrical voltage source associated with it and circuitry equipment for optical display elements, the housing being penetrated by a hollow shaft connected with one of the poles of the voltage source and the hollow shaft being provided on its machine side end with an accurately ground receiving region while, at its free end, it carries an electrically insulated feeler head connected to the input of the first amplifier. Suitable optical display elements are light-emitting diodes, which can be located adjacent to one another on the outside of the housing.
The circuitry equipment preferably includes four amplifiers connected as comparators and grouped together to an integrated circuit for the same operating voltage with, connected to the negative inputs, different defined reference voltages, the positive inputs being subjected to DC pulses generated as a function of the duration of contact between the feeler head and the workpiece, the outputs of two amplifiers being each connected with a lightemitting diode and the output of one amplifier being connected with a multivibrator circuit known per se, it being possible to switch off the diodes temporarily via a transistor connection by means of the multivibrator circuit as a function of the magnitude of the DC pulses.
Further features providing advantageous embodiments of t
REFERENCES:
patent: 2109976 (1938-03-01), Pierce
patent: 2451904 (1948-10-01), Beatty
patent: 3259989 (1966-07-01), Wilson
patent: 3307267 (1967-03-01), Barr et al.
patent: 3370356 (1968-02-01), Jend
patent: 4342091 (1982-07-01), Whitehouse et al.
patent: 4386344 (1983-05-01), Vecchiatto
Christoffel Reinhold
Wesoly Heiner
Haroian Harry N.
Kontler Peter K.
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