WO1998023915A1 - Appareil de mesure de position - Google Patents

Appareil de mesure de position Download PDF

Info

Publication number
WO1998023915A1
WO1998023915A1 PCT/UA1997/000011 UA9700011W WO9823915A1 WO 1998023915 A1 WO1998023915 A1 WO 1998023915A1 UA 9700011 W UA9700011 W UA 9700011W WO 9823915 A1 WO9823915 A1 WO 9823915A1
Authority
WO
WIPO (PCT)
Prior art keywords
probe
sensor
tool
contact
workpiece
Prior art date
Application number
PCT/UA1997/000011
Other languages
English (en)
Inventor
Vladimir Aleksandrovich Ostafiev
Vladimir Ivanovich Skitiouk
Original Assignee
Ostafiev Vladimir Aleksandrovi
Vladimir Ivanovich Skitiouk
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Ostafiev Vladimir Aleksandrovi, Vladimir Ivanovich Skitiouk filed Critical Ostafiev Vladimir Aleksandrovi
Priority to AU53541/98A priority Critical patent/AU5354198A/en
Publication of WO1998023915A1 publication Critical patent/WO1998023915A1/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/002—Constructional details of contacts for gauges actuating one or more contacts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; 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
    • B23Q17/00—Arrangements for observing, indicating or measuring on machine tools
    • B23Q17/09—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool
    • B23Q17/0952—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool during machining
    • B23Q17/0957—Detection of tool breakage
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; 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
    • B23Q17/00—Arrangements for observing, indicating or measuring on machine tools
    • B23Q17/20—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring workpiece characteristics, e.g. contour, dimension, hardness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; 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
    • B23Q17/00—Arrangements for observing, indicating or measuring on machine tools
    • B23Q17/22—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring existing or desired position of tool or work

Definitions

  • This invention relates to a position measurement apparatus, and in particular to such an apparatus that can simply but very precisely measure the position of a point on the surface of an object such as a workpiece.
  • US 5,208,993 discloses a touch probe having a complex precision biasing mechanism including a helical spring system and a movable shuttle. Upon contact of the probe on the object movement against this bias is detected.
  • a vibrating touch probe is provided with a piezoelectric element at its end remote from the contact point and a change in the piezoelectric effect is used to detect physical contact of the probe with the surface.
  • a precision measurement apparatus for measuring a point on the surface of an electroconductive preferably ferromagnetical object comprising, a measurement probe, means for moving said probe away from and towards an object to be measured and for detecting the position of said probe, said probe and said object to be measured being arranged in use such that a electric and/or magnetic circuit is formed when said probe is in contact with or closely adjacent to said object, and an inductive sensor arranged to detect when said circuit is formed.
  • the apparatus is able to detect when the probe is very close - but not yet contacting - the surface of the object to be measured since the inductive sensor will detect the change in magnetic field created by the formation of the electric and/or magnetic circuit which happens before actual physical contact is made. In cases where physical contact is to be avoided this proximity may possibly be used as the measurement itself, though it would not be very accurate and greater accuracy will of course be obtained normally by allowing the probe to contact the surface, which may in preferred embodiments be confirmed by the completion of an electrical circuit.
  • the inductive sensor simply comprises a wire coil around a ferrite core and which produces an output signal dependant on the strength of the magnetic field the sensor experiences.
  • the sensor is exposed to ambient environmental fields (e.g. from radios, television sets, other items of machinery) and/or fields generated by an exciter.
  • ambient environmental fields e.g. from radios, television sets, other items of machinery
  • the magnetic field experienced by the sensor changes and this change produces a change in the sensor output which may be detected.
  • the detection of this change is relatively simple because it is not necessary to detect absolute values of the magnetic field experienced by the sensor. It is only necessary to detect the change caused by formation of the magnetic circuit, which change will be much greater than the random modulations occurring in the ambient electromagnetic fields.
  • the ambient magnetic field is sufficient, however greater accuracy still may be obtained by using an electromagnetic field exciter.
  • the sensor is preferably located in the magnetic field - for example it may surround the contact probe or a spindle on which the object to he measured is mounted - but it may also be simply located nearby or be simply located around any convenient part of the magnetic circuit.
  • means may be provided for controlling the speed of movement of the probe towards the object to be measured as a function of the proximity of the probe to the object.
  • the output of the sensor is input to processing means, and more preferably still this processing means may be used to control the speed of the probe.
  • the processing means may include a first channel of high sensitivity for determining a change in the sensor output indicative of the probe approaching the surface of the object, and a second channel for determining contact between the probe and the object. The probe may then be caused to move towards the object at a slower speed upon an output from the first channel detecting the approach of the probe to the object. Upon detection of contact the probe will be caused to stop moving, and the pesition of the probe will be stored in a memory and the probe may then be caused to retract from the object.
  • the measurement probe may be a separate element, however a particular advantage of the present invention is that it allows for the possibility of the measurement apparatus being integrated into a machine tool.
  • the measuring probe may be the cutting tool of a cutting machine and the sensor may be provided either surrounding the cutting tool or surrounding the spindle on which the workpiece is mounted.
  • This arrangement has many advantages over conventional arrangements in which a separate measuring probe must be provided.
  • the cutting tool may be used to make measurements of the dimensions of the workpiece without the need to interrupt the cutting operation and bring to the workpiece a separate probe. This makes the measurement much faster and simpler and the results of the measurement may be fed directly back to the cutting tool control means to provide a form of feedback.
  • the cutting tool may be used to ascertain the surface quality (e.g. roughness) of the workpiece.
  • the measurement apparatus may indirectly provide a means for detecting the condition of the cutting tool. For example if the tool were to break or wear out this would result in a change of the magnetic field experienced by the sensor and which could be indicated to the machine operator.
  • the invention also extends to a method for measuring the position of a point on the surface of an object made of electro ⁇ conductive preferably ferromagnetical material comprising, moving a measurement probe towards an object to be measured, and detecting the position of the probe at which a magnetic circuit is formed when the probe is in contact with or closely adjacent to said object.
  • Fig.1 is a schematic view of a position measurement apparatus incorporated into a machine tool
  • Fig.2 is a plot showing a typical sensor output signal as the measuring probe/cutting tool approaches and contacts a workpiece
  • Fig.3 is a block diagram showing the processing of the sensor output signal
  • Fig.4 is a view of a modification of the embodiment of Figs. 1 to 3.
  • a CNC machine tool comprising a rotatably driven spindle 39 on which a workpiece 37 may be mounted, and a cutting tool 36 which is under the control of CNC controller 43 so that the position of the cutting tool 36 is always known.
  • the tool is movable according to CAD/CAM system
  • An inductive sensor 1 is provided in one of a number of possible locations.
  • the sensor 1 comprises a wire coil around a ferrite core and Fig.1 shows three possible locations: surrounding the cutting tool 36, surrounding the spindle 39 between the machine tool frame 38 and a clamping fixture 40, and surrounding a set up attachment 41. It will be appreciated however that other positions may also be envisioned, and indeed more than one sensor could be employed.
  • the sensor 1 provides an output to contact detection means 42 which will be described in greater detail further below.
  • this apparatus In operation of this apparatus, as the cutting tool 36 is advanced towards the workpiece 37 and becomes very close to the workpiece a magnetic circuit is formed between the cutting tool, workpiece, spindle, and machine tool frame as shown by the arrows in Fig.1. The formation of this circuit decreases the magnetic reluctance of the circuit and increases the magnetic flux passing through the sensor 1 producing a change in the sensor output.
  • Fig.2 illustrates the sensor output as the cutting tool approaches and then contacts the workpiece.
  • the output signal F is simply indicative of the noise of the ambient environmental magnetic fields. There is some minor modulation of the noise signal but otherwise it is generally constant.
  • the magnetic circuit starts to form and since the magnetic flux is concentrated within the circuit the sensor output F.
  • ⁇ * X increases. As will be explained in more detail below this increase - which is pre-physical contact - can be detected and the proximity of the cutting tool to the workpiece can be sensed.
  • Fig.3 illustrates how the output signal from the sensor 1 is processed.
  • the signal is passed to two identical channels: a contact approach channel and a contact detection channel through pre-amplifier 2 and buffer 3. Then the signal is sent to respective buffers 6 and 18 through signal refiners 5 and 17 in each channel. Buffer 6 amplifies the signal by a factor lOx greater than buffer 18 in order to provide the contact approach channel with greater sensitivity than the contact detection channel so as to determine the earliest tool approach.
  • comparators 13,25 which compare the signals with adjusted reference voltages taken from the high voltage supplies 7,19 through flip-flops 10,22 to create a high comparator reference level.
  • a lower comparator reference level needed for robust signal registrations are created with adjusted reference voltages taken from low voltage supplies 8,20 through flip-flops 11,23 closed at the beginning. If a comparator reference level is higher than its input signal the comparator output is a "logical 0" signal, otherwise a comparator output is a "logical 1" signal.
  • the flip-flops 10, 11, 22, and 23 also activate optoisolators 9, 12, 21, and 24 that indicate output signals of contact approach or contact determination to the CNC machine.
  • the comparators 13, 25 send signals to AND gates 14,26 and to decimal counters 15,27 that count the impulse number n repeatedly loaded by counter 32.
  • the impulse numher n is calibrated experimentally and has a maximum value for signal recognition from the noise.
  • Counters 15,27 send signals to AND gates 14,26 if pulse number n calculation creates a clock cycle shorter than the duration time of the comparator "logical 1" signal. In the opposite case counters 13,25 are reset by the comparator "logical 0" signal as well as counters 31,32 through OR gate 29.
  • AND gates 14, 26 get comparator "logical 0" signals and counters signal simultaneously.
  • the signals from AND gates 14,26 are sent to triggers 16,28 which switch on low voltage supplies 8,20 through flip-flops 11,23 and to switch off high voltage supplies 7,19 through flip-flops 10,22.
  • Triggers 16,28 are reset by a signal from decoder 30 which in turn receives a signal from the pulse generator 33 through counters 32,31.
  • contact between the cutting tool and the workpiece may be interrupted, for example if the workpiece surface is interrupted (e.g. by b.eing provided with slots), or if a multi-edge cutting tool is used.
  • a multi-edge cutting tool may have from 2 to 20 edges and each edge will have a short contact time depending on various factors, including the number and disposition of cutting edges and the speed of rotation.
  • Such interruptions should not prevent the measurement apparatus and to achieve this aim the system response time needs to be set to be greater than the contact interrupt time. For example, when the cutting edges are further apart or the cutting tool rotation speed is reduced, the response time must be increased and vice versa. This is achieved by the CNC machine being programmed to provide different system response times in conjunction with decoder 30 in accordance with different possible sets of conditions.
  • the output system signals to the CNC serve to reduce cutting tool approaching speed or to stop further advance of the cutting tool, to memorize the co-ordinates and to start retraction of the cutting tool.
  • This retraction breaks the tool/workpiece contact in both channels triggers 16, 28 switch flip-flops 10, 22 on and flip-flops 11, 23 off so that the system is ready to begin a new cycle.
  • the pulse generator 33 activates an electromagnetic field exciter 34 to create an alternating electromagnetic field with a frequency corresponding to the system frequency and recognisable by the sensor 1.
  • the system can function without said exciter 34 using only ambient electromagnetic fields and appropriate setting of the sensor frequency, but the recognisable separation distance will be smaller.
  • contact detection can make use of the background electromagnetic noise. Structurally this simplifies to the loop 1,2,7,8,9,10,11,12,13,16. For this reason the gain of the amplifier 2 may have a wide range such that the resulting signal is always above the supply reference.
  • the establishment of a definite tool/workpiece contact may be additionally verified by detecting current through it from pulse generator 33.
  • the frequency generator 4 simulates the tool/probe's operation to serve as a self-test function.
  • the frequency of pulses generated by frequency generator 4 must be higher of course then the number of pulses n that characterizes noise.
  • An advantage of employing the cutting tool itself as the measuring probe is that the system may also be employed to recognise tool wear. This recognition is achieved by e. m. f. alternative variable analysis. In the course of the machining process the cutting process itself generates an e. m. f. in the workpiece, spindle, machine frame, cutting tool loop which may be detected by sensor 1.
  • the sensor output signal is sufficiently high to reach the contact detection channel - since of course the tool and workpiece by definition are in contact - and a cutting tool wear signal is output to the CNC machine. Breakage of the cutting tool will be recognised by any sudden short loop disconnection and disappearance of output to the CNC machine.
  • the tool itself acts as the measurement probe and this is advantageous in that when it is desired to make a measurement there is no need to bring a separate measurement probe into operation.
  • a completely separate measuring probe could of course be provided. It will be understood, however, that the measuring probe must be made of a material that allows a electric circuit to be formed, i.e. an electroconductive preferably ferromagnetical material.
  • both approach and contact are detected by the formation of an electromagnetic circuit.
  • This invention may be used for positioning various tools, preferably cutting tools, with a high degree of precision in respect of a predetermined point on the surface of an object such as a workpiece.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)

Abstract

L'invention porte sur un appareil de mesure de précision détectant le point où une sonde de mesure entre en contact avec la surface d'un objet à mesurer en surveillant la formation d'un circuit électrique et/ou magnétique lorsque la sonde approche de l'objet. Cela s'obtient en utilisant une sonde faite en un matériau électroconducteur, de préférence ferromagnétique, et en disposant la sonde et l'objet (qui doit également être métallique ou fait en un matériau ferromagnétique de façon qu'ils viennent former un circuit magnétique. Ce circuit comporte un détecteur inductif réagissant aux champs magnétiques environnants et produisant un signal de sortie variant en réaction à la formation du circuit. Comme le circuit est formé avant que ne s'établisse le contact effectif, l'appareil peut détecter l'arrivée de la sonde au voisinage de l'objet et régler sa vitesse en conséquence. Selon une réalisation préférée la sonde peut être l'outil de coupe d'une machine outil à commande numérique.
PCT/UA1997/000011 1996-11-26 1997-09-19 Appareil de mesure de position WO1998023915A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU53541/98A AU5354198A (en) 1996-11-26 1997-09-19 A position measurement apparatus

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9624469A GB2319615A (en) 1996-11-26 1996-11-26 Position measurement apparatus
GB9624469.4 1996-11-26

Publications (1)

Publication Number Publication Date
WO1998023915A1 true WO1998023915A1 (fr) 1998-06-04

Family

ID=10803437

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/UA1997/000011 WO1998023915A1 (fr) 1996-11-26 1997-09-19 Appareil de mesure de position

Country Status (3)

Country Link
AU (1) AU5354198A (fr)
GB (1) GB2319615A (fr)
WO (1) WO1998023915A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114833637A (zh) * 2022-05-13 2022-08-02 陕西法士特齿轮有限责任公司 一种刀具磨损检测系统及检测方法

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19952807A1 (de) 1999-11-02 2001-05-10 Roland Mueller Verfahren zur spanenden Bearbeitung elektrisch leitfähiger Werkstücke
ITBO20030141A1 (it) 2003-03-13 2004-09-14 Jobs Spa Dispositivo di controllo della posizione di un mandrino
DE102006003761A1 (de) * 2006-01-25 2007-07-26 Robert Bosch Gmbh Verfahren und Vorrichtung zur Prüfung von Eigenschaften eines Werkzeugelementes
CN105234747A (zh) * 2015-10-21 2016-01-13 常州市武进南夏墅苏南锻造有限公司 测量型切割机

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3975667A (en) * 1973-11-19 1976-08-17 Werkzeugmaschinenfabrik Oerlikon-Buhrle Ag Apparatus for a machine tool for the automatic generating of a switching signal and for reducing the speed of a tool
US4408933A (en) * 1981-03-10 1983-10-11 Toyoda Koki Kabushiki Kaisha Contact detecting apparatus
US4451892A (en) * 1980-01-31 1984-05-29 Mcmurtry David R Method of and apparatus for measuring distances in numerically controlled machine tools
GB2172224A (en) * 1985-03-15 1986-09-17 Daishowa Seiki Machine tool contact detector
US4831785A (en) * 1986-09-01 1989-05-23 Meseltron S.A. Wireless arrangement for controlling the speed of advance of a tool toward a workpiece
US5247751A (en) * 1990-09-29 1993-09-28 Nikon Corporation Touch probe

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1279411A (en) * 1968-05-06 1972-06-28 Massey Ferguson Perkins Ltd Improvements in or relating to machine tools
US4000448A (en) * 1974-05-10 1976-12-28 Westinghouse Electric Corporation Control system for sensing the air gap between a cutting tool and a work piece
CH656702A5 (en) * 1979-11-30 1986-07-15 Schmall Karl Heinz Arrangement for compensating disturbing radiation of electromagnetic radio-frequency oscillations in contactless scanning devices
GB2241063B (en) * 1990-02-14 1994-01-05 Rolls Royce Plc Monitoring a machining operation

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3975667A (en) * 1973-11-19 1976-08-17 Werkzeugmaschinenfabrik Oerlikon-Buhrle Ag Apparatus for a machine tool for the automatic generating of a switching signal and for reducing the speed of a tool
US4451892A (en) * 1980-01-31 1984-05-29 Mcmurtry David R Method of and apparatus for measuring distances in numerically controlled machine tools
US4408933A (en) * 1981-03-10 1983-10-11 Toyoda Koki Kabushiki Kaisha Contact detecting apparatus
GB2172224A (en) * 1985-03-15 1986-09-17 Daishowa Seiki Machine tool contact detector
US4831785A (en) * 1986-09-01 1989-05-23 Meseltron S.A. Wireless arrangement for controlling the speed of advance of a tool toward a workpiece
US5247751A (en) * 1990-09-29 1993-09-28 Nikon Corporation Touch probe

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114833637A (zh) * 2022-05-13 2022-08-02 陕西法士特齿轮有限责任公司 一种刀具磨损检测系统及检测方法

Also Published As

Publication number Publication date
AU5354198A (en) 1998-06-22
GB9624469D0 (en) 1997-01-15
GB2319615A (en) 1998-05-27

Similar Documents

Publication Publication Date Title
AU645951B2 (en) Method and apparatus for co-ordinate measuring using a capacitance probe
US7355394B2 (en) Apparatus and method of dynamically measuring thickness of a layer of a substrate
US4059795A (en) Digital eddy current apparatus for sensing and analyzing metallurgical characteristics of an electrically conductive material
EP0683378B1 (fr) Calibrage des sondes capacitives
US10591268B2 (en) Feeler for workpieces being machined
US4750272A (en) Tool measuring device employing gap width detection
US7756672B2 (en) Method for setting a predetermined distance between a machine tool and an electrically conductive workpiece
EP2645052A1 (fr) Tête de mesure à palpeur pour pièces à usiner
JPS62218052A (ja) 工具の破損および摩耗を非接触監視する方法および装置
WO1998023915A1 (fr) Appareil de mesure de position
Valentinčič et al. Uncertainty of the electrode wear on-machine measurements in micro EDM milling
JP7332682B2 (ja) 測定サイクル生成のための方法および装置
JPH02109683A (ja) 数値制御研削盤における自動砥石寸法測定装置
CN113074767A (zh) 电涡流传感器动静态一体化校准装置
JP3009250B2 (ja) 位置検出装置
JP3946827B2 (ja) 近接検出装置
JPH06300593A (ja) 温度及び変位測定装置
SU486889A1 (ru) Устройство дл электрохимической обработки деталей из ферромагнитных материалов
JPH08313242A (ja) タッチプローブおよびタッチプローブによる計測方法
JPH06218652A (ja) バイト移動式切削装置
RU1780930C (ru) Измерительна головка
CN115917080A (zh) 用于精磨机设备的打浆间隙传感器装置和校准方法
US5051694A (en) Device having oppositely spaced coils for determining a shape of screw parts
JPH10328974A (ja) プリント基板の加工方法および装置
Qi et al. A new system for on-machine measurement

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AU BR CA CN CZ HU JP KR MX NO PL RU TR UA US VN

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FI FR GB GR IE IT LU MC NL PT SE

121 Ep: the epo has been informed by wipo that ep was designated in this application
NENP Non-entry into the national phase

Ref country code: JP

Ref document number: 1998524620

Format of ref document f/p: F

122 Ep: pct application non-entry in european phase