# US 11,994,412 B2 · Induction sensing method for locating center of metallic nozzle tip > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,994,412 B2 - Document ID: US11994412B2 - Status: Granted - Kind: B2 - Application number: 17/562,354 - Filed: 2021-12-27 - Published: 2023-08-03 - Granted: 2024-05-28 - Earliest claimed: 2021-12-27 - Assignees: Stratasys, Inc. - Applicants: Stratasys, Inc. - Inventors: Michael Bosveld; Thomas Peter Paul - Web page: https://patentgrep.com/patent/US11994412B2 ## CPC - G01D 5/20: by varying inductance, e.g. by a movable armature - B22F 10/80: Data acquisition or data processing - B22F 12/53: Nozzles - B22F 12/90: Means for process control, e.g. cameras or sensors - B29C 64/118: using filamentary material being melted, e.g. fused deposition modelling [FDM] - B29C 64/209: Heads; Nozzles - B29C 64/236: for motion in a direction within the plane of a layer - B29C 64/25: Housings, e.g. machine housings - B29C 64/259: Interchangeable - B29C 64/336: of two or more materials - B29C 64/393: for controlling or regulating additive manufacturing processes - B33Y 10/00: Processes of additive manufacturing - B33Y 30/00: Apparatus for additive manufacturing; Details thereof or accessories therefor - B33Y 40/00: Auxiliary operations or equipment, e.g. for material handling - B33Y 50/00: Data acquisition or data processing for additive manufacturing - B33Y 50/02: for controlling or regulating additive manufacturing processes - G01B 11/002: {for measuring two or more coordinates} - G02B 21/008: {Details of detection or image processing, including general computer control} - B22F 2999/00: Aspects linked to processes or compositions used in powder metallurgy - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR - B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) - B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract An induction sensing method for identifying the center of a tip surface of a nozzle of print head of a 3D printer includes providing an eddy current sensor in a fixed position and providing a metal nozzle with a tip orifice in a main body and a tip surface about the tip orifice. The method includes moving the metal nozzle over the eddy current sensor in a predetermined motion path above the eddy current sensor while the eddy current sensor remains stationary and samples the magnitude of inductance in a generated inductive field, thereby generating a curve representing the inductive field. The method includes identifying a maximum amplitude of the curve to identify the center of the tip surface. ## Claims ### Claim 1 An induction sensing method comprising: providing an eddy current sensor in a fixed position; providing a metal nozzle with a tip orifice in a main body and a tip surface about the tip orifice; moving the metal nozzle over the eddy current sensor in a predetermined motion path above the eddy current sensor while the eddy current sensor remains stationary and samples the magnitude of inductance in a generated inductive field, thereby generating a curve representing the inductive field; and identifying a maximum amplitude of the curve to identify the center of the tip surface. ### Claim 2 (depends on 1) The induction sensing method of claim 1, wherein the predetermined path comprises a circle. ### Claim 3 (depends on 1) The induction sensing method of claim 1, wherein the predetermined path comprises a spiral path, a path of concentric circles or a plurality of spaced apart parallel and orthogonal lines to provide information to generate the curve. ### Claim 4 (depends on 1) The induction sensing method of claim 1, wherein the eddy current sensor is positioned apart from a 3D printer. ### Claim 5 (depends on 1) The induction sensing method of claim 1, wherein the eddy current sensor is located on board a 3D printer. ### Claim 6 (depends on 1) The induction sensing method of claim 1, and further comprising heating the metal nozzle to a selected temperature prior to performing the moving step. ### Claim 7 (depends on 1) The induction sensing method of claim 1, and further comprising moving the metal nozzle away from the eddy current sensor to provide an inductive count and using the inductive count to determine the distance between the nozzle and the eddy current sensor. ### Claim 8 (depends on 1) The induction sensing method of claim 1, and further comprising utilizing a design origin of a center of a surface of the metal nozzle as a base location for the predetermined motion path. ### Claim 9 (depends on 1, 8) The induction sensing method of claim 8 and further comprising: moving the origin of the base location for the predetermined path to the identified maximum amplitude of the curve; and repeating the steps of claim 1 until the identified maximum amplitude of the curve becomes sufficiently stationary. ### Claim 10 (depends on 1) The induction sensing method of claim 1, wherein the curve representing the inductive field is a bell-shaped curve. ### Claim 11 A method of determining a location of a tip orifice in a metal nozzle for a print head of a 3D printer, the method comprising: providing the metal nozzle with tip orifice in a main body and a tip surface about the tips orifice; using an optical sensor to determine a location of a center of an inner diameter of the tip orifice on the tip surface of the metal nozzle; using an eddy current sensor to determine a location of a center of the tip surface of the metal nozzle, comprising the steps of moving the metal nozzle over the eddy current sensor in a predetermined motion path above the eddy current sensor held in a stationary position while the eddy current sensor samples the magnitude of inductance in a generated inductive field, thereby generating a curve representing the inductive field; and identifying a maximum amplitude of the curve to identify the center of the tip surface. ### Claim 12 (depends on 11) The method of claim 11, and further comprising: locating the center of the inner diameter of the tip orifice relative to the center of the tip surface of the metal nozzle; determining a count and a Z distance between the tip surface and the eddy current sensor; and storing information of the locations of the center of the inner diameter of the tip orifice, the center of the tip surface of the metal nozzle, the inductive count and the Z distance in memory for use when the metal nozzle is installed on a print head of the 3D printer and used to print 3D parts. ### Claim 13 (depends on 11) The method of claim 11, and further comprising heating the metal nozzle to a selected temperature prior to using the sensors. ### Claim 14 (depends on 11) The method of claim 11, wherein the optical sensor comprises a confocal microscope. ### Claim 15 (depends on 14) The method of claim 14, and further comprising: identifying a design origin on the tip surface; and identifying a radius on the tip surface a distance from the design origin; and moving the metal nozzle over the confocal microscope in a circular motion path or a spiral motion path between the design origin and the radius the distance from the design origin to sample the surface. ### Claim 16 (depends on 15) The method of claim 15, and further comprising: accumulating the samples into vertices of an equilateral triangle to create an angled plane; and calculating a normal vector that is normal to the angled plane. ### Claim 17 (depends on 16) The method of claim 16, and further comprising: providing a reference vertical vector on the tip surface; and using the reference vertical vector to determine an angle of the normal vector relative to vertical. ### Claim 18 (depends on 17) The method of claim 17, and further comprising: shifting the design origin based upon the difference of the vertical vector and the normal vector. ### Claim 19 (depends on 18) The method of claim 18, and further comprising repeating the sampling, accumulating the samples into vertices of the equilateral triangle, creating an angled plane, calculating the normal vector, providing the reference vertical vector to determine the angle of the normal vector and shift the design origin until a product of the angle vector and the vertical vector is about 1.0 to recalculate the location of the design origin. ### Claim 20 (depends on 19) The method of claim 19, and further comprising locating a point on the tip surface relative to the recalculated location of the design origin and sampling the tip surface with the confocal microscope to determine the inner diameter of the tip orifice. ### Claim 21 (depends on 20) The method of claim 20, and further comprising: defining a chord on the tip surface that intersects the between the point on the tip surface relative to the recalculated location of the design origin; bisecting the chord at a right angle through the recalculated design origin to form a second chord; and bisecting the second chord with a third chord at a right angle to determine a confocal center of the inner diameter of the tip orifice.