Blank with coding for the production of tooth-technical shaped parts and procedures for the identification of a blank

Abstract

The invention relates to a blank for the production of a dental shaped body, wherein the blank has a corpus (2) of tooth restoration material, from which the shaped part to be fabricated is carved by means of a tool (4) by removal of material. The blank has coding means (1) formed on part of the surface (6) of the blank corpus (2), which coding means (1) has at least one structure (8, 9) for identification of the blank. The coding means (1) consists of a plurality of panels (5.1) at the level of the surface (6) of the corpus (2) and a plurality of panels (5.2, 5.3) incorporating a flat structure (8, 9) at a level (h1, h2) which is distinguishable from at least the level of the surface (6) of the corpus (2). The invention further relates to a method for identifying a blank with the aid of coding means (1).

Claims

1. A method of identifying a blank of material from which a dental part is to be carved, the blank includes a coding region that includes (i) a plurality of first panels that each include a first structure that is at a different level from a surface level of the material, and (ii) a plurality of second panels that each include a second structure that is at a different level from the surface level of the material, the method comprising: scanning a first panel of the plurality of first panels with a tool to determine a first value representing a level of the first panel relative to the surface level of the material; scanning a second panel of the plurality of second panels with the tool to determine a second value representing a level of the second panel relative to the surface level of the material, the second panel being adjacent to the first panel; and determining a value of a difference between the first value and the second value; and comparing the difference value to an expected value and identifying the blank based on the comparison.

2. A method according to claim 1, wherein the tool is machining tool or a calibration pin.

3. A method according to claim 1, wherein a position of the adjacent second panel is determined from a stored assignment list of pairs of panels that includes the plurality of first panels and the plurality of second panels.

4. A method according to claim 3, wherein the assignment list is stored in the tool.

5. A method according to claim 3, wherein the expected value is stored with the assignment list of pairs of panels.

6. A method of identifying a blank of material from which a dental part is to be carved and carving the blank to form the dental part, the blank includes a coding region that includes (i) a plurality of first panels that each include a first structure that is at a different level from a surface level of the material, and (ii) a plurality of second panels that each include a second structure that is at a different level from the surface level of the material, the method comprising: scanning a first panel of the plurality of first panels with a tool held in a tool holder to determine a first value representing a level of the first panel relative to the surface level of the material; scanning a second panel of the plurality of second panels with the tool to determine a second value representing a level of the second panel relative to the surface level of the material, the second panel being adjacent to the first panel; determining a value of a difference between the first value and the second value; and comparing the difference value to an expected value and identifying the blank based on the comparison; and carving the blank with a tool held in the tool holder to form the dental part.

7. A method according to claim 6, wherein the tool that is used to scan the first panel and second panel is also used to carve the blank.

8. A method according to claim 6, wherein the tool that is used to scan the first panel and second panel is different from the tool that is used to carve the blank.

9. A method according to claim 8, wherein the tool that is used to scan the first panel and the second panel is a calibration pin and the tool that is used to carve the blank is a machining tool.

10. A method according to claim 6, wherein a position of the adjacent second panel is determined from a stored assignment list of pairs of panels that includes the plurality of first panels and the plurality of second panels.

11. A method according to claim 10, wherein the assignment list is stored in the tool.

12. A method according to claim 10, wherein the expected value is stored with the assignment list of pairs.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The method of the invention is explained with reference to the drawings, in which:

(2) FIG. 1 shows a blank having a corpus carrying coding means,

(3) FIG. 2 a cross-section of the corpus shown in FIG. 1,

(4) FIG. 3 shows a tool tip which has been brought into contact with a structure in a blank corpus,

(5) FIG. 4 shows the coding means shown in FIG. 1, and

(6) FIG. 5 shows an assignment list and stored expected values.

EXEMPLARY EMBODIMENT OF THE INVENTION

(7) FIG. 1 illustrates a blank consisting of a corpus 2 disposed in a holder 3. The corpus 2 has coding means 1, which are three-dimensionally designed and disposed at that end of the blank corpus 2 that is near to the holder such that it can be scanned and uniquely identified with the aid of the existing machining tools 4 or by means of calibrating or positioning aids, such as is illustrated in FIGS. 2 and 3.

(8) The coding means 1 is for this purpose formed according to the invention as a flat area extending in an x,y plane on the corpus 2, which coding means is divided, for example, into uniform panels 5, as outlined in FIG. 4.

(9) FIG. 2 is a cross-section of a blank corpus 2 as shown in FIG. 1 and taken along the line AB. It can be seen that some of the panels 5.2, 5.3 are formed as structures 8, 9, for example, taking the form of depressions 8 relative to the surface 6 and having a base 8.1 below the level of the surface as regarded in the direction of the z axis. The structures 8, 9 can alternatively be in the form of eminences 9 having a raised roof 9.1 as regarded in the direction of the z axis, as indicated by dashed lines.

(10) Some of the panels 5.1 of the coding means 1 are flush with the surface 6 of the blank corpus.

(11) The position and shape of the panels 5 of the coding means 1 in the corpus 2, and more particularly the distribution of the structures 8, 9 within the coding means 1 are defined such that for example, a word or a picture is recognizable in the coding means 1. This is achieved, for example, in that the lines of the alphabetic characters of a word are represented by appropriately adjoining panels 5.2, 5.3 incorporating a structure 8, 9, while the spaces are completely filled by panels 5.1 at the level of the surface 6. Filling of the spaces entirely has the result that the coding means has panels 5.4 which are surrounded only by panels of the same type, as is the case in FIG. 4, for example, with some panels 5.1 being at surface level.

(12) FIG. 3 shows a tool 4 while scanning a panel 5.3, the structure being in the form of a depression 8.

(13) The structures 8, 9 are, according to the invention, geometrically designed and exhibit an appropriate diameter d such that a machining tool 4 or a calibration aid can advance toward the base 8.1 or the roof 9.1 of such a structure 8, 9 without touching the lateral delimitations of this panel or of an adjacent panel 5.

(14) The absolute value of the depression 8 or the eminence 9 of the structure 8, 9 is such that no noticeable restriction in the usefulness of the blank corpus 2 results and the value, that is the difference in level h1, h2, of the depression 8 or the eminence 9, can still be reliably detected by the position measuring system present in the machine tool.

(15) In the exemplary embodiment, the structures 8, 9 in the form of depressions 8 can, for example, be formed in steps of approximately 100 m so that for example, the difference in level of a panel 5.2 incorporating the structure 8, 9 relative to the surface 2 is 100 m and the difference in level of a panel 5.3 incorporating a structure 8, 9 is 200 m.

(16) The tool 4 or the calibration aid in the machine tool is positioned in the x,y plane on-center in front of a specific, arbitrary or randomly selected panel 5 of the coding means 1 in this case designed as a word and is then advanced along the longitudinal axis 1 of the tool 4 or the calibration aid, corresponding in the figures to the z axis, toward the workpiece 2.

(17) The point of contact between the blank corpus 2 and the front, i.e. the tip, of the tool 4 or the front of the calibration aid within said panel 5 is detected either by the existing load regulation/control means for the tool 4 or the calibration aid or by some other sensor present in a regulation/control means, for example, a force sensor in the longitudinal axis 1 of the tool 4 or the calibration aid.

(18) The position sensing means present in every CAD/CAM machine tool or CNC machine tool makes it possible to determine, as the first position, the absolute value in space of this panel 5 from the position of the tool 4 or calibration aid during detection.

(19) The x,y position is given by the predetermined position of the tool 4 or the calibration aid in this plane. The z position is detected.

(20) Starting from said first panel 5, a second panel 5 that is, a second position in the x,y plane, is determined. This is carried out with reference to an assignment list 10, as illustrated in FIG. 5, for example, in which the first panel 5 is assigned to a second panel 5, which two panels 5 form a so-called pair 7. Such a pair 7 is indicated, for example, in FIG. 4. The second panel 2 can be ascertained with reference to the assignment list 10, for example, directly in the machine tool due to storage of, inter alia, the assignment list 10 in the machine tool itself. Of course, the assignment list 10 can alternatively be stored in a control computer and the determination of the second panel 5 effected by appropriate communication between the machine tool and the control computer.

(21) The tool 4 or the calibration aid of the machine tool is positioned in front of the second panel 5 in the x,y plane and the absolute position of this further panel 5 in space is determined in the same way as the second position.

(22) These pairs 7 consisting of the first and second panels 5 are predetermined. The pairs 7 can, for example, always consist of a panel 5.2, 5.3 incorporating a structure 8, 9 and a panel 5.1 at the level of the surface 6 of the blank corpus 2 like the pair 7 shown in FIG. 4.

(23) The coding means 1 can, for example, contain only panels 5 which are assigned to not more than one pair 7. Alternatively, the coding means 1 can be provided with an assignment list 10 which assigns individual panels 5 to a plurality of partner-panels, for example, to a first partner-panel with which the designated panel 5 forms a pair 7 when it is tested as the first panel 5 and to a second partner-panel with which the designated panel 5 forms a pair 7 when it is scanned as the second panel 5.

(24) The difference in level h1, h2, h3 of the two positions defined for the two panels 5 of a pair 7 that is, the difference between the z value of the first position and the z value of the second position directly forms, for example, a reference value v, which is compared with an expected value e for the difference in level of these two panels 5 that is, of this pair 7. The result can either be used immediately for a decision concerning further machining of the workpiece 2 or be stored for evaluation following the determination of further differences. The expected values e can, for example, have been stored in a list 11 of the expected values e associated with the assignment list 10, as indicated in FIG. 5.

(25) The provision of pairs 7 of adjacent panels 5 has the advantage that an angle error of the longitudinal axis 1 of the tool 4 or the calibration aid with respect to the x,y plane of the blank corpus 2 has only a very small influence on the determined difference in level.

(26) The determination of further differences in level h1, h2, h3 is carried out in the same way on further pairs 7, and the selection of pairs 7 or of the first partner-panel 5 to be scanned of a pair 7 can be randomly effected. This can be carried out, for example, by the machine tool itself.

(27) The number of determined differences in level h1, h2, h3 is governed by the number of panels 5 and by the desired degree of security against falsification. The more panels 5 that are included in a coding means 1 and the larger the proportion of scanned panels 5 compared with the unscanned panels 5 of a coding means 1, the greater is the security of the identification achieved by scanning.

(28) The evaluation of the determined reference values v can take place, for example, only following the determination of the desired number of differences in level h1, h2, h3 and the determination of the corresponding reference values v. To this end, the determined reference values v can be stored in a list 12 of reference values v, as indicated in FIG. 5.

(29) Execution of the method of the invention makes it possible, for example, by reason of high deviations in individual reference values v or in the sum of such values, not to start machining, and thus to prevent machining of incorrectly coded blank corpuses 2, in a machine tool carrying out the method.

LIST OF REFERENCE NUMERALS OR CHARACTERS

(30) 1 coding means 2 blank corpus 3 holder 4 tool 5 panel 5.1 panel at surface level 5.2 panel incorporating a structure showing a first difference in level relative to the surface of the blank 5.3 panel incorporating a structure showing a first difference in level relative to the surface 5.4 panel adjoining only panels of the same type 6 surface of the blank corpus 7 pair 8 depression 8.1 base of depression 9 eminence 9.1 roof of eminence 10 assignment list 11 list of expected values 12 list of the reference values d diameter e expected value h1 first difference in level h2 second difference in level h3 difference in level l longitudinal axis of tool v reference value