# US 11,439,484 B2 · Method for controlling a machine tool > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,439,484 B2 - Document ID: US11439484B2 - Status: Granted - Kind: B2 - Application number: 16/472,541 - Filed: 2017-03-17 - Published: 2021-03-18 - Granted: 2022-09-13 - Earliest claimed: 2017-01-10 - Assignees: Ivoclar Vivadent AG - Applicants: Ivoclar Vivadent AG - Inventors: Gottfried Rohner; Christian Seiler - Web page: https://patentgrep.com/patent/US11439484B2 ## CPC - A61C 13/0004: {Computer-assisted sizing or machining of dental prostheses} - B23Q 17/2428: {for measuring existing positions of tools or workpieces} - A61C 13/0006: {Production methods} - A61C 13/0022: {Blanks or green, unfinished dental restoration parts} - B23Q 17/2233: {for adjusting the tool relative to the workpiece} - B23Q 17/249: {using image analysis, e.g. for radar, infrared or array camera images} - G05B 2219/37555: Camera detects orientation, position workpiece, points of workpiece - A61C: DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE (non-driven toothbrushes A46B; {tongue scrapers A61B17/24;} preparations for dentistry A61K6/00; preparations for cleaning the teeth or mouth A61K8/00, A61Q11/00) - B23Q: DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING (tools of the kind used in lathes or boring machines B23B27/00); MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) ## Abstract The invention relates to a system of a method for controlling a machine tool, and a workpiece, in particular a milling blank, and the method for machining this workpiece, said machine tool comprising a robot arm movable in at least 2, in particular at least 3 spatial axes in a range of motion, said robot arm carrying, guiding and moving at least one workpiece, possibly by means of a workpiece holder, with a control unit for controlling the machine tool. The machine tool (62) comprises a sensor, in particular a spatially fixed optical sensor or is assigned said sensor, whose detection range (66) at least partially overlaps the range of motion. The workpiece (10) comprises a change in geometry, in particular a hole (12), is moved in the detection range (66) by the robot arm (70), and upon detection of the hole (12) by the sensor the control unit determines a reference point, reference axis and/or reference surface for controlling the machine tool (62). ## Claims ### Claim 1 A system for controlling a machine tool and a workpiece and for machining the workpiece, comprising a machine tool, a workpiece, and a control unit for controlling the machine tool, said machine tool comprising a robot arm movable in at least 2 spatial axes in a range of motion, said robot arm configured for carrying, guiding and moving at least one workpiece, wherein the machine tool (62) comprises a fixed sensor or is assigned said fixed sensor, wherein a detection range (66) of the fixed sensor at least partially overlaps the range of motion of the workpiece, wherein an exchangeable tool (40) or the workpiece (10) comprises a code (52), wherein the workpiece (10) is movable in the detection range (66) by the robot arm (70), and wherein upon detection of the code (52) by the fixed sensor, the control unit is configured to carry out identification of the workpiece (10) and/or the tool (40) for controlling the machine tool (62) to perform a machining process adapted to an identity of the workpiece (10) and/or the tool (40). ### Claim 2 (depends on 1) The system as claimed in claim 1, wherein the machine tool (62) is configured to machine a surface (14) of the workpiece (10) to be planar, which workpiece is fabricated of ceramics, and wherein the robot arm (70) is configured to align the surface (14) substantially parallel to an axis of the detection range (66) of the fixed sensor, and wherein the robot arm (70) is configured to move the workpiece (10) past the fixed sensor through the detection range (66) to detect an edge between the surface (14) and an adjacent surface. ### Claim 3 (depends on 1) The system as claimed in claim 1, wherein the workpiece comprises a milling blank, and wherein the fixed sensor comprises a spatially fixed optical sensor. ### Claim 4 (depends on 1) The system as claimed in claim 1, wherein the tool (40) is mounted to a gripper or a mount (76) of the robot arm (70) and wherein a tool shaft (44) extends in the detection range (66) of the fixed sensor. ### Claim 5 (depends on 4) The system as claimed in claim 4, wherein the shaft (44) of the tool (40) is provided with a one-dimensional code (52), which is supplied to the control unit by the fixed sensor to identify the tool (40). ### Claim 6 A system for controlling a machine tool and a workpiece and for machining the workpiece, comprising a machine tool, a workpiece, a control unit for controlling the machine tool, said machine tool comprising a robot arm movable in at least 2 spatial axes in a range of motion, said robot arm configured for carrying, guiding and moving at least one workpiece, wherein the machine tool (62) comprises a sensor or is assigned said sensor having a detection range (66) at least partially overlapping a range of motion of the workpiece, wherein the sensor is fixed to a housing of the machine tool, wherein the workpiece (10) comprises a hole (12) that is adapted to move laterally or orthogonally with respect to the fixed sensor, wherein the workpiece (10) is movable in the detection range (66) by the robot arm (70), and wherein upon detection of the surface or section having the hole, the control unit is configured to determine a reference point, reference axis and/or reference surface for controlling the machine tool (62). ### Claim 7 (depends on 6) The system as claimed in claim 6, wherein the surface (14) of the workpiece (10) which comprises the hole (12) is machinable before detection of the hole (12), to produce a planar surface at the surface (14) comprising the hole. ### Claim 8 (depends on 6) The system as claimed in claim 6, wherein the robot arm (70) is configured to align the hole (12) of the workpiece (10) during detection parallel to an axis of detection of the fixed sensor, wherein the fixed sensor is a camera (64). ### Claim 9 (depends on 6) The system as claimed in claim 6, wherein an axis of the hole (12) extends perpendicular to a surface (14) of the workpiece (10), and wherein the surface (14) is machinable or millable to a planar surface before the detection. ### Claim 10 (depends on 6) The system as claimed in claim 6, wherein the workpiece (10) is attachable to a holder (20), said holder (20) being configured for being held or clamped in the robot arm (70). ### Claim 11 (depends on 6) The system as claimed in claim 6, wherein the fixed sensor comprises a camera, wherein the machine tool (62) comprises the camera (64) in an auxiliary space which is separated from a machining space by means of an openable door, and wherein the robot arm (70) is configured to hold the workpiece (10) directly adjacent to the door opening and/or to move the workpiece past the doorfor detection of the hole (12). ### Claim 12 (depends on 6) The system as claimed in claim 6, wherein the robot arm (70) is configured to move the workpiece (10) with the hole (12) in a X-direction straight through an optical axis of the fixed sensor, and in a further step additionally in a direction perpendicular thereto, which direction perpendicular to the X-direction is the Y-direction. ### Claim 13 (depends on 6) The system as claimed in claim 6, wherein the surface (14) of the workpiece (10) facing the fixed sensor and comprising the hole (12) is aligned orthogonally with respect to an optical axis of the fixed sensor. ### Claim 14 (depends on 6) The system as claimed in claim 6, wherein the robot arm (70) is configured to hold the workpiece (10) with the hole (12) in the detection range (66) of the fixed sensor and is configured to supply the workpiece (10) to a tool spindle (72) for machining. ### Claim 15 (depends on 6) The system as claimed in claim 6, wherein the workpiece comprises a milling blank, wherein said robot arm is movable in at least 3 spatial axes in a range of motion, wherein said robot arm is configured to carry, guide and move at least one workpiece by a workpiece holder, and wherein the fixed sensor comprises a spatially fixed optical sensor. ### Claim 16 (depends on 6) The system as claimed in claim 6, wherein the hole (12) is configured as a through-hole through the workpiece (10) and comprises a cone (16) on at least one side of the workpiece (10). ### Claim 17 (depends on 16) The system as claimed in claim 16, wherein the hole (12) with a cone-free end is alignable toward the fixed sensor for detection by the fixed sensor. ### Claim 18 (depends on 6) The system as claimed in claim 6, wherein the workpiece (10) and/or an associated holder (20) comprises a code (52), said code (52) being readable by the fixed sensor configured as a camera (64) when the holder (20) is clamped in the robot arm (70), and wherein the code (52) is attached to a part of the workpiece (10) to be milled off. ### Claim 19 (depends on 12) The system as claimed in claim 12, wherein the code (52) of the workpiece (10) detected by the fixed sensor is configured for feeding to the control unit which is configured to select an appropriate machining process for the workpiece (10). ### Claim 20 (depends on 18) The system as claimed in claim 18, wherein the code (52) comprises a data matrix code.