US 4,899,458 AGranted

Process and device for centering a guide mandrel

AssigneeMinelli AG

InventorItalo Minelli

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Abstract

A process and apparatus for centering a pilot shaft which is inserted into a valve guide of a valve seat to be machined, and serves therein as a guide mandrel for a rotary shaping tool. By electronically controlled drive mechanisms, the pilot shaft is supported in a central position by a swiveling ball maintained in a swivelable manner between two clamping shells, and is held between two displaceable clamping plates and centered in the valve guide. To center the pilot shaft, it is moved in two crossing directions by the drive mechanisms through the horizontal displacement of the clamping shells. The clamping shells are successively moved to their two end positions of their two crossing displacement directions. The displacement path lying between these end positions is electronically measured. The drive mechanisms then move the clamping shells into the electronically determined central position of the two measured displacement ranges.

Claims19

Dependent claims

A process for the centering of a pilot shaft (11), serving as a guide mandrel in a valve guide (25), for a precision machining of a valve seat (24), with a device for guiding a rotary shaping tool (12), said device comprising said pilot shaft (11) fitting into said valve guide (25) and passing through a swiveling ball (7), whereby said pilot shaft (11), by means of said swiveling ball (7), is positioned and supported so as to be displaceable and fixable on all sides in a support mounting on an arm (4) of said device, said process comprising the steps:

(a) displacing said pilot shaft (11) back and forth through at least two crossing directions in succession outside said valve guide (25) by means of an electronically controlled drive mechanism (14), measuring, storing and calculating a motion path between both end positions of a horizontal displacement range of a respective support mounting by means of an electronic control unit, moving said pilot shaft (11) into central positions outside said valve guide of calculated displacement ranges by movement of said respective support mounting by means of said drive mechanism (14) which are controlled by said control unit;
(b) inserting said pilot shaft (11) into said valve guide (25) of said valve seat (24), and attaching the arm (4) of said device in a non-movable manner with respect to said valve seat (24);
(c) moving said pilot shaft (11) successively through at least two crossing directions back and forth in an overall horizontal displacement range of the support mounting by means of said electronically controlled drive mechanism (14) thereby centering said pilot shaft (11) within a clearance in said valve guide (25), said pilot shaft (11) moving within the clearance in said valve guide (25), measuring, storing and calculating the motion path between both said end positions of the specific displacement range of the support mounting by means of said electronic control unit, moving said pilot shaft (11) back into the central position of a previously dimensioned displacement range through moving its support mounting by means of said drive mechanism (14), said drive mechanism being controlled by said control unit;
and
(d) clamping said pilot shaft (11) solidly in said respective support mounting with clamping devices in an immovable manner, as a holder for said rotary shaping tool (12) for the precision machining of said valve seat (24).

2 more elements

A device for centering a pilot shaft (11) serving as a guide mandrel comprising a support mounting of which is mounted in a swivelable manner on all sides on a swiveling arm (4), said swiveling arm (4) positioned in a height-adjustable manner on a support stand (1) having support column (3) and a magnetic flange (2) which can be magnetically attached to a clamping plate (22), a swiveling ball (7) rotatably and swiveledly mounted between two opposing clamping shells (6) and two clamping plates (5), said clamping shells (6) having concave clamping surfaces positioned parallel and spaced from one another, said clamping shells (6) being flat on a side turned away from said swiveling ball (7) and supported in a displaceable manner between said two clamping plates (5), said swiveling ball (7) with said pilot shaft (11) positioned rotatably within said swiveling ball (7) can be clamped solidly between said clamping shells (6) by means of compression of said clamping plates (5) toward one another;

a drive mechanism (14) capable of displacing said clamping shells (6), in a released condition, in two crossing directions, said drive mechanism (14) having measuring devices, with which for electronically measuring a displacement range;
and an electronic control unit capable of calculating a measured displacement range and controlling said drive mechanism (14) moving said pilot shaft (11) precisely into a central position between both end positions of a displacement of said pilot shaft (11) in two displacement directions, and fixing said pilot shaft (11) in said central position.

Dependencies are inferred from the claim text.