Sensor elements and assemblies, cutting tools comprising same and methods of using same

Patent metadata

Field	Value
Publication number	US-2022381093-A1
Application number	US-202017773540-A
Country	US
Kind code	A1
Filing date	Nov 3, 2020
Priority date	Nov 4, 2019
Publication date	Dec 1, 2022
Grant date	—

Abstract

A sensor element for a cutting tool (100) has a hard portion (110) having a sensing surface (112), first and second electrodes (120, 130), first and second sets of thermocouple wires (122, 132) and an electrically insulating portion. The first and second electrodes (120, 130) are arranged to allow electric current to flow when the sensing surface (112) contacts external material in response to the cutting tool engaging the external material. A first thermocouple junction (124) is operable to indicate a temperature of the first electrode and a second thermocouple junction (134) is operable to measure temperature of the second electrode.

First claim

1 . A sensor element for a cutting tool, comprising a hard portion, having a sensing surface;
a first electrode; a first set of thermocouple wires; a second electrode; a second set of thermocouple wires; and an electrically insulating portion; wherein: the hard portion comprises hard and/or super-hard material; the first electrode and the second electrode each comprising electrically conductive hard and/or super-hard material, and each being attached to the hard portion and exposed at respective areas of the sensing surface; the hard portion including the electrically insulating portion; the first electrode, the second electrode and the hard portion being arranged to allow an electric current to flow between with first electrode and the second electrode through external material, when the sensing surface contacts the external material in response to the cutting tool engaging the external material in use; the electrically insulating portion electrically isolating the sensing surface, operable to prevent electric current from flowing through the sensing surface; wherein the first set of thermocouple wires are electrically connected to the first electrode at a first thermocouple junction operable to indicate a temperature of the first electrode; and the second set of thermocouple wires are connected to the second electrode at a thermocouple junction, operable to measure the temperature of the second electrode.

2 . A sensor element as claimed in claim 1 , wherein the first electrode and the second electrode each comprises electrically conductive super-hard material.

3 . A sensor element as claimed in claim 1 , wherein the hard portion comprises super-hard material comprising any one or more of single crystal diamond, polycrystalline diamond (PCD) material, polycrystalline cubic boron nitride (PCBN) material, and/or chemical vapour deposited diamond.

4 . A sensor element as claimed in claim 1 , configured as a cutter element; the sensing surface comprising a working surface including a cutting edge and providing a rake face area.

5 . A sensor element as claimed in claim 1 , wherein the sensor element comprises a cutter element for an earth-boring bit, or a machine tool for machining a workpiece.

6 . A sensor element as claimed in claim 1 , wherein the electrically insulating portion comprises a volume of the hard material portion coterminous with the sensing surface.

7 . A sensor element as claimed in claim 1 , wherein the hard material portion comprises polycrystalline diamond (PCD) material and includes a surface volume that includes no more than 2 wt. % metallic material.

8 . A sensor assembly as claimed in claim 1 , wherein the first electrode comprises boron- and/or phosphorus-doped diamond.

9 . A sensor assembly comprising
a sensor element as claimed in claim 1 ; a source of potential difference and electric current; a current measurement device; voltage measurement means connected to the first and second sets of thermocouple wires, operable to indicate the temperatures of the first and second electrodes; the first electrode, the second electrode, the source and the current measurement device connected in an electrical circuit, arranged to generate a potential difference between the first electrode and the second electrode, and to allow an electric current to flow between the first electrode and the second electrode, through external material when the sensing surface contacts the external material in response to the cutting tool engaging the external material in use; and to allow the current measurement device to indicate the magnitude of the electric current.

10 . A sensor assembly as claimed in claim 9 , at least the first electrode electrically connected to the source by the first set of thermocouple wires.

11 . A sensor assembly as claimed in claim 9 , comprising a computer system communicatively connected to the current measurement device, to receive measured electric current data from the current measurement device; the computer system configured to process the electric current data, to determine an electrical characteristic of the external material.

12 . A sensor assembly as claimed in any claim 9 , comprising an impedance spectrometry system, operable to process a measured electric current having one or more frequency component; the source of the electric current being configurable to generate varying electric current, having one or more frequency component.

13 . A cutting tool comprising
a tool body; and a sensor element as claimed in claim 1 , attached to the tool body; operable to contact the sensing surface with external material when the cutting tool engages the external material in use.

14 . A cutting tool as claimed in claim 13 , provided as an earth-boring bit, a plurality of cutter elements attached to the bit, operable to cut rock and bore a hole into the earth; the sensor element arranged on the earth-boring bit to allow at least an area of the sensing surface to contact rock.

15 . A method of using a cutting tool as claimed in claim 13 , including
engaging a workpiece body with the cutting tool to remove workpiece material from the workpiece body, and allowing the sensing surface of the sensor element to engage external material containing workpiece material cut from the workpiece body; generating a potential difference between the first electrode and the second electrode; generating an electric current to flow between the first electrode and the second electrode, through the external material contacted by the sensing surface; measuring the electric current; measuring the temperatures of the first electrode and the second electrode; determining the respective electrical resistance of the first electrode and the second electrode at the respective measured temperatures; and analysing the measured electric current to determine an electrical characteristic of the external material.

16 . A method as claimed in claim 15 , including a computer-implemented method to process the measured electric current, to calculate the electrical characteristic of the external material; and to calculate a quantity indicative of a mechanical characteristic of the workpiece material, based on the electrical characteristic.

Assignees

• Element Six Uk Ltd

Inventors

• Ghosh Santonu
• Wort Christopher John Howard
• Vythilingum Vijay Nadasen

Classifications

• E21B12/02 Primary

  Wear indicators · CPC title

• E21B10/52

  with chisel- or button-type inserts · CPC title

• E21B47/07

  Temperature · CPC title

• E21B10/56 Primary

  Button-type inserts (E21B10/52 takes precedence) · CPC title

• E21B10/46

  characterised by wear resisting parts, e.g. diamond inserts · CPC title