Abrading – Precision device or process - or with condition responsive... – With indicating
Reexamination Certificate
2001-08-14
2004-02-03
Wilson, Lee D. (Department: 3723)
Abrading
Precision device or process - or with condition responsive...
With indicating
C451S009000, C451S029000, C451S281000, C433S051000, C433S052000
Reexamination Certificate
active
06685538
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the field of machines that allow a machining by the removal of material by reproducing a model, more particularly applied to the medical field, particularly the dental field, for manufacturing ceramic components intended to replace all or part of a dental crown, and relating in particular to machines comprising a machining tool with an axis of symmetry and having at least one degree of freedom in rotation about said axis of symmetry, means for driving the rotation of the said machining tool about its axis of symmetry, means of securing a blank, in which said volume is machined, having at least one degree of freedom in rotation, means for driving the rotation of said blank-securing means, means for securing a template, having at least one degree of freedom in rotation, means for driving the rotation of said template-securing means, a feeler capable of coming into contact with the exterior surface of said template, means for bringing about relative movement between said blank-securing means and said machining tool, on the one hand, and between said template-securing means and said feeler on the other hand, said movement means allowing the machining tool and the feeler to remain in constant contact with, respectively, said blank and said template.
A known method and to an apparatus for manufacturing volumes by copying in. dentistry, particularly for inlays, is disclosed in U.S. Pat. No. 5,135,393. The machine is an eight-axis machine in which all movements of the moving parts of the machine are performed manually by the operator, except for the rotating of the tool which is done by a motor. More specifically, the machine comprises a first carriage carrying a feeler and a tool support which are held together, the axes of which are mutually parallel and are perpendicular to an axis of movement and translation of the feeler and of the tool support; furthermore, this first carriage is free to rotate and to translate along axes respectively parallel and perpendicular to the axis of translation of the feeler and of the tool joined together; this first carriage is kept pressing and moved by an operator during machining against a second free-rotation carriage which carries the template and the blank themselves which are free to rotate on this second carriage; so that under the pressure and movements brought-about by the operator, the feeler travels over the surface of the template and the tool machines the blank accordingly; the template and the blank are incidentally linked in rotation so that when the operator with one hand turns the template, the blank follows this rotational movement, whereas with the other hand the operator takes care to cause the feeler to travel over the surface of the template. A machine such as this is complicated and expensive because of the high number of degrees of freedom and is tricky to use because the copying precision depends on the quality of service provided by the operator.
The prior art in particular teaches a machine of this type with document WO 96/05 782, comprising a diamond-tipped machine tool actuated by a high-speed turbine, a feeler placed on the same machine body of the tool, the tool and the feeler being able to move in translation and in rotation so as to follow the profile of a model secured in alignment with the blank, such a machine allowing a model to be reproduced precisely but entailing a mechanism which is cumbersome, bulky and expensive, particularly because of the high speeds at which the tool rotates. Furthermore, the small-diameter tool which allows small details to be reproduced, which rotates at high speed, may wear rapidly and therefore cause the machine to be expensive to use.
SUMMARY OF THE INVENTION
The present invention essentially sets out to alleviate these drawbacks and to provide other advantages. More specifically, it consists in a machine for machining at least one volume, particularly an inlay, automatically by copying, comprising at least:
a machining tool with an axis of symmetry and having at least one degree of freedom in rotation about said axis of symmetry,
means for driving the rotation of the said machining tool about its axis of symmetry,
means for securing a blank, in which said volume is machined, having at least one degree of freedom in rotation,
means for driving the rotation of said blank-securing means,
means for securing a template, having at least one degree of freedom in rotation,
means for driving the rotation of said template-securing means,
a feeler capable of coming into contact with the exterior surface of said template,
means for bringing about relative movement between said blank-securing means and said machining tool, on the one hand, and between said template-securing means and said feeler on the other hand, said movement means allowing the machining tool and the feeler to remain in constant contact with, respectively, said blank and said template,
means for commanding and controlling said means for driving the rotation of the machining tool, said means for driving rotation of the template-securing means and said movement means, said machine being characterized in that said machining tool is an abrasive disk and in that said movement means comprise a moving carriage on which said blank-securing means and said template-securing means are mounted so that they are free to rotate, said moving carriage having at least two degrees of freedom of movement.
The abrasive disk which makes it possible to reduce the rotational speed of the machining tool appreciably, and the arrangement of the movement means which allow the blank and the template to be moved rather than the machining tool, lead to a significant reduction in the weight and cost of the machine.
According to an advantageous characteristic, said two degrees of freedom of said moving carriage are one degree of freedom in rotation and one degree of freedom in translation, and said movement means comprise means for driving the translation and means for driving the rotation of said moving carriage.
According to an advantageous characteristic of the foregoing, the machine according to the invention comprises a rigid support, and said means for driving the translation of said moving carriage comprise a first motor connected completely to said rigid support, in that said means for driving the rotation of said blank-securing means and said means for securing the template comprise a second motor connected to said first motor via a screw-nut connection, and said moving carriage is free in rotation about the output shaft of said second motor, said output shaft being guided in rotation and in translation by said rigid support.
According to an advantageous characteristic of the foregoing, said means for driving the rotation of said moving carriage about the output shaft of said second motor comprise the friction forces generated by the rotation of said blank-securing means and of said means of securing the template.
According to an advantageous characteristic of the foregoing, said blank-securing means and said means for securing the template are connected completely and have aligned axes of rotation.
According to an advantageous characteristic of the foregoing, the axis of rotation of said abrasive disk is parallel to the axes of rotation of said blank-securing means and of said means for securing the template, said rigid support having a flat wall perpendicular to said axis of rotation of the abrasive disk separating a machining compartment from a drive compartment.
According to an advantageous characteristic of the foregoing, the axis of rotation of said abrasive disk and the output shaft of said second motor are mounted in identical respective bearing supports.
The flat wall perpendicular to the axes of rotation makes the bearing supports easier to mount and the use of identical bearing supports lowers manufacturing costs.
According to an advantageous characteristic, said feeler is secured rigidly to said rigid support so as, by its abrasion resulting from the rubbing against the templa
Dykema Gossett PLLC
Wilson Lee D.
LandOfFree
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