Method for the production of medical fittings, in particular dental fittings

• US 6,454,629 B1
• Filed: 07/05/2000
• Issued: 09/24/2002
• Est. Priority Date: 07/05/1999
• Status: Expired due to Term

• Current Assignee: Sirona Dental Systems GmbH (Sirona Dental Systems Incorporated)
• Original Assignee: Sirona Dental Systems GmbH (Sirona Dental Systems Incorporated)
• Inventors: Wedler, Volker, Rothenberger, Bernd, Basler, Franz
• Primary Examiner(s): Eley, Timothy V.
• Application Number:
  US09/610,358
• Time in Patent Office: 811 Days
• Field of Search: 433/166, 433/223, 451/5, 451/8, 451/9, 451/10, 451/11, 451/41, 451/27, 451/51, 451/52, 408/3, 409/2, 409/79, 409/289
• US Class Current: 451/5
• CPC Class Codes: A61C 13/0003 Making bridge-work, inlays, implants or the like
• CPC Class Codes: A61C 13/0004 Computer-assisted sizing or machining of dental prostheses
• CPC Class Codes: A61F 2/30942 for designing or making customized prostheses, e.g. using templates, CT or NMR scans, finite-element analysis or CAD-CAM techniques
• CPC Class Codes: B24B 1/00 Processes of grinding or polishing; Use of auxiliary equipment in connection with such processes
• CPC Class Codes: B24B 35/005 for making three-dimensional objects by electroerosion B23H5/04
• CPC Class Codes: B24B 49/006 taking regard of the speed
• CPC Class Codes: B24B 49/16 taking regard of the load
• CPC Class Codes: G05B 2219/45172 Prosthesis

Abstract

A method for the production of medical fittings, in particular dental fittings, is proposed. A workpiece (1), from which the fitting is produced, has material removed from it by machining with a tool (7). The tool (7) and the workpiece (1) execute a relative movement with respect to each other along a fixed trajectory. The instantaneous loading of the tool is used to control the speed of this relative movement. In order to avoid the load peaks which occur here, and to ensure a more uniform control, it is proposed that the expected loading of the tool along the trajectory is also calculated and is used to control the speed.

Claims

1. A method for the production of medical fittings, in particular dental fittings, in which a workpiece, from which the fitting is produced, has material removed from it by machining with a tool as a result of moving the tool in the workpiece, the tool and the workpiece executing a relative movement along a trajectory, and an actual loading of the tool as a result of moving the tool in the workpiece being used to control the speed of the relative movement, wherein an expected loading of the tool along the trajectory is calculated and is used to control speed of the relative movement.

2. The method as claimed in claim 1, wherein the tool is essentially cylindrically symmetrical and rotates about its axis of symmetry by means of a rotary drive mechanism.

3. The method as claimed in claim 2, wherein the measure for the actual loading of the tool is its frequency of rotation determined at an essentially constant power consumption of the rotary drive mechanism.

4. The method as claimed in claim 2, wherein the measure for the actual loading of the tool is the power consumption of the rotary drive mechanism determined at an essentially constant frequency of rotation.

5. The method as claimed in claim 2, wherein the relative movement between the tool and the workpiece includes all of the following types of movement:

a) linear feed between the tool and the workpiece along a feed direction which is essentially perpendicular to the axis of symmetry of the tool;

b) change of depth of the tool in the workpiece essentially along the axis of symmetry of the tool; and

c) one-dimensional sideways movement between the tool and the workpiece along a predetermined path in a plane which is essentially perpendicular to the axis of symmetry of the tool.

6. The method as claimed in claim 5, wherein the one-dimensional sideways movement comprises a swiveling of the tool about an axis which is essentially parallel to the axis of symmetry of the tool.

7. The method as claimed in claim 5, wherein the relative movement between the tool and the workpiece moreover includes a pivoting of the workpiece about an axis which is essentially parallel to the feed direction.

8. The method as claimed in claim 5, wherein the tool is an essentially cylindrical grinder rod with a circumferential surface and an end surface.

9. The method as claimed in claim 8, wherein

the linear feed takes place in steps which are small compared to the diameter of the grinder rod,

the trajectory is divided into sections between which no linear feed takes place,

and the expected loading for each section is calculated by comparison of the trajectory along this section and the trajectory along the previous section.

10. The method as claimed in claim 9, wherein, in order to determine the expected loading upon a one-dimensional sideways movement, the height of that portion of the circumferential surface of the grinder rod from which material is removed is calculated.

11. The method as claimed in claim 10, wherein the speed of the one-dimensional sideways movement is limited to a maximum speed which is determined by reference to a table in which, for a number of values of the height of that portion of the circumferential surface from which material is removed, the associated maximum speed is stored.

12. The method as claimed claim 9, wherein, in order to determine the expected loading upon a change of depth of the grinder rod in the workpiece, that portion of the end face approximately is determined from which material is removed.

13. The method as claimed in claim 12, wherein the speed of the change of depth of the tool in the workpiece is limited to a maximum speed which is determined by reference to a table in which, for several values of that portion of the end face from which material is removed, the associated maximum speed is stored.