EP0903200B1 - Verbessertes Schleifverfahren und Vorrichtung - Google Patents

Verbessertes Schleifverfahren und Vorrichtung Download PDF

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Publication number
EP0903200B1
EP0903200B1 EP19980307403 EP98307403A EP0903200B1 EP 0903200 B1 EP0903200 B1 EP 0903200B1 EP 19980307403 EP19980307403 EP 19980307403 EP 98307403 A EP98307403 A EP 98307403A EP 0903200 B1 EP0903200 B1 EP 0903200B1
Authority
EP
European Patent Office
Prior art keywords
grinding
coolant
workpiece
wheel
flow
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
EP19980307403
Other languages
English (en)
French (fr)
Other versions
EP0903200A1 (de
Inventor
Stuart Clewes
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Intermec Europe Ltd
Original Assignee
Unova UK Ltd
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 Unova UK Ltd filed Critical Unova UK Ltd
Publication of EP0903200A1 publication Critical patent/EP0903200A1/de
Application granted granted Critical
Publication of EP0903200B1 publication Critical patent/EP0903200B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B5/00—Machines or devices designed for grinding surfaces of revolution on work, including those which also grind adjacent plane surfaces; Accessories therefor
    • B24B5/36—Single-purpose machines or devices
    • B24B5/42—Single-purpose machines or devices for grinding crankshafts or crankpins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B55/00—Safety devices for grinding or polishing machines; Accessories fitted to grinding or polishing machines for keeping tools or parts of the machine in good working condition
    • B24B55/02—Equipment for cooling the grinding surfaces, e.g. devices for feeding coolant
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B57/00—Devices for feeding, applying, grading or recovering grinding, polishing or lapping agents
    • B24B57/02—Devices for feeding, applying, grading or recovering grinding, polishing or lapping agents for feeding of fluid, sprayed, pulverised, or liquefied grinding, polishing or lapping agents

Definitions

  • This invention concerns a grinding machine and grinding method as per the preamble of claims 3 and 1.
  • An example of such a method and machine is disclosed by DE-A-4 133 754.
  • CBN wheels in grinding processes has resulted in the requirement for large volumes of coolant to be delivered at ever higher pressures and velocity.
  • CBN wheels tend to have a higher density and lower porosity than conventional Aluminium Oxide wheels. Grinding forces are higher and it is possible that the coolant contributes to the generation of high dynamic forces between the grinding wheel and the workpiece.
  • Document DE-A-4133754 discloses a control system for a grinding machine in which the changes in feed rate between rough grinding, finish grinding and spark-out are automatically determined as a result of signals from a grinding position sensor and a grinding load sensor.
  • a method of grinding an external surface of a workpiece comprising the steps of directing liquid coolant onto the external surface being ground, and monitoring the grinding process by means of a probe for detecting the dimension of the surface, characterised in that during a predetermined final stage of a grinding cycle, before final size is reached, the rate and/or direction of flow of liquid coolant onto said surface is altered for at least part of the duration of said final stage, so that a reduced flow of the coolant reaches said external surface, whereby the accuracy of final grinding of the workpiece is improved.
  • the method is particularly applicable when grinding with a CBN grinding wheel.
  • a cam lobe profile can be improved and grinding errors in the final size reduced from 10's of microns to 2 or 3 microns during finish grinding, if the coolant flow is reduced or at least in part directed away from the region of engagement during the grinding of the final 20 microns down to final size.
  • the out-of-roundness of a crankpin has been reduced from a 10 micron envelope to an envelope of less than 1 micron, by reducing or deflecting or even removing the high pressure coolant flow when the component was 25 microns above final size, and maintaining the reduced or deflected flow (or turning off the flow) for the duration of the final 25 micron grind.
  • a grinding machine comprising a grinding wheel, drive means for rotating the wheel to effect grinding of an external surface of a workpiece, means for rotating the workpiece during grinding, means for effecting relative movement between the grinding wheel and the workpiece to bring the wheel and the external surface of workpiece into engagement for grinding and to maintain such engagement for the duration of a grinding cycle, means for directing a jet of liquid coolant onto the wheel or the workpiece or both, at least in the region of the engagement of the wheel and the workpiece, sensing means for sensing when the grind cycle is nearing completion and the workpiece has a predetermined oversize condition remaining to be ground, said sensing means comprising a workpiece engaging probe for detecting the dimension of the external surface being ground, and means for generating a control signal responsive to signals from the sensing means, characterised by coolant control means for altering the rate of flow of coolant from the jet and/or the direction of the jet, sensing means for means for supplying the control signal to the coolant control means to alter the jet of liquid cool
  • the sensing means may comprise means responsive to the advance of the grinding wheel during the grinding cycle, which is programmed to deliver a signal when the grinding wheel has advanced through a given distance thereby indicating that said predetermined oversize condition has been reached during which coolant flow is to be altered.
  • the coolant flow control means may be controlled by signals from the computer.
  • FIG. 1 there is shown part of a grinding machine including a CBN grinding wheel 10 rotating clockwise, as indicated by the arrow.
  • the wheel is shown in grinding contact with a contra-rotating cylindrical workpiece 12, in this case a crankpin rotating about the main axis of a crankshaft (not shown).
  • the wheel In order for the wheel to follow the orbiting movement of the crankpin 12, the wheel is moved horizontally backwards and forwards under computer control by means known per se.
  • a coolant nozzle 14 feeds a jet of coolant liquid down into the zone of contact between the wheel and the crankpin.
  • the nozzle is mounted on a wheelhead (not shown) on which the wheel 12 itself is rotatably mounted.
  • Figure 2 shows the control circuit for the coolant, in which a pump (not shown) feeds coolant under pressure along a supply line 16 to a solenoid operated selector valve 18 which, in this example, is under the control of the computer.
  • the selector valve has two positions, a first normal position (as shown) in which a full flow of coolant passes through it, and is fed via line 19 to the nozzle 14, and a second position in which the flow is throttled so that a reduced flow is fed to the nozzle.
  • the reduced flow can be adjusted by a flow control valve 20 which connects the pump to the selector valve 18 along a line 21 parallel to the line 16.
  • FIG. 3 A typical cycle of grinding feed against time is shown in Figure 3.
  • the feed rate progressively reduces from an initial fast feed 22 and a medium feed 24 down to a slow feed 26, after which there is a dwell period 28 in which the feed ceases and sizing of the workpiece occurs, in this case the crankpin 12.
  • the coolant flow is maintained at a full rate 30 during the fast feed and up to the end of the slow feed 26, whereupon the computer issues a command signal to the selector valve 18 to cut the flow down to a reduced rate 32 for the duration of the dwell period 28.
  • the coolant flow is completely stopped while the grinding wheel executes a rapid retract, as shown at 34 in Figure 3.
  • Adjustment of the control valve 20 enables the ratio of the full flow to reduced flow to be varied to cater for differing conditions.
  • crankshaft Since the crankshaft is not uniformly stiff when subjected to side forces, there is a tendency for different amounts of material to be ground away in different planes, causing the crankpin to be ground to a non-round shape. Reducing the flow rate 32 during the final stage of grinding reduces the coolant pressure at the nozzle 14, and hence the force on the crankpin (when grinding forces are low already), and it has been found that the out-of-roundness of the crankpin can be reduced from approximately 10 microns to less than 1 micron, in terms of its true diameter. Thus, the invention enables a higher accuracy and truer grinding profile to be achieved than previously.
  • the coolant could be directed away from the wheel during the final grinding stage.
  • this alternative would be more complicated and less practical than reducing the flow rate.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Grinding-Machine Dressing And Accessory Apparatuses (AREA)
  • Grinding Of Cylindrical And Plane Surfaces (AREA)

Claims (9)

  1. Verfahren zum Schleifen einer äußeren Oberfläche eines Werkstücks (12), das die Schritte umfasst: Leiten von flüssigem Kühlmittel auf die zu schleifende äußere Oberfläche und Überwachen des Schleifverfahrens durch einen Sensor zur Erfassung der Abmessung der Oberfläche, dadurch gekennzeichnet, dass während einer vorher bestimmten Endphase (28) eines Schleifzyklus vor Erreichen der Endgröße die Durchflussmenge und/oder die Richtung des Stroms von flüssigem Kühlmittel auf die Oberfläche wenigstens während eines Teils der Dauer der Endphase geändert wird, so dass ein verringerter Strom des Kühlmittels die äußere Oberfläche erreicht, wodurch die Genauigkeit des abschließenden Schleifens des Werkstücks verbessert wird.
  2. Verfahren nach Anspruch 1, bei dem die Änderung des Stroms des Kühlmittels eine Reduzierung des Stroms auf einen Bruchteil des vollen Stroms während der vorher bestimmten Endphase umfasst.
  3. Schleifmaschine, die Folgendes aufweist: eine Schleifscheibe (10), Antriebsmittel zum Drehen der Scheibe, um ein Schleifen einer äußeren Oberfläche eines Werkstücks (12) zu bewirken, Mittel zum Drehen des Werkstücks während des Schleifens, Mittel zum Erzeugen einer relativen Bewegung zwischen der Schleifscheibe und dem Werkstück, um die Scheibe und die äußere Oberfläche des Werkstücks in Eingriff für das Schleifen zu bringen und diesen Eingriff während der Dauer eines Schleifzyklus aufrechtzuerhalten, Mittel (14) zum Leiten eines Strahls von flüssigem Kühlmittel auf die Scheibe oder das Werkstück oder beide wenigstens in dem Bereich des Eingriffs der Scheibe und des Werkstücks, Erfassungsmittel zum Erfassen, wann der Schleifzyklus sich der Vollendung nähert und das Werkstück einen Zustand einer vorher bestimmten Übergröße hat, die noch zu schleifen bleibt, wobei das Erfassungsmittel einen Werkstück-Eingriffssensor zur Erfassung der Abmessung der zu schleifenden äußeren Oberfläche aufweist, und Mittel zum Erzeugen eines Steuerungssignals in Abhängigkeit von Signalen von dem Erfassungsmittel, gekennzeichnet durch ein Kühlmittel-Steuerungsmittel (18) zum Ändern des Durchsatzes des Kühlmittels aus dem Strahl und/oder zum Ändern der Richtung des Strahls, Mittel zum Leiten des Steuerungssignals an das Kühlmittel-Steuerungsmittel (18) zum Ändern des Strahls der Kühlflüssigkeit, so dass der Strahl abgelenkt, umgeleitet oder reduziert wird, wenn der vorher bestimmte Übergrößen-Zustand erfasst wird, während wenigstens eines Teils der Restdauer (28) des Schleifzyklus.
  4. Maschine nach Anspruch 3, die weiterhin aufweist: ein Maschinensteuerungsmittel, das auf das Steuerungssignal zur Wiederaufnahme eines Schleifzyklus reagiert, nachdem die Änderung des Kühlmittelstrahls bewirkt wurde, um das Schleifverfahren zu vollenden.
  5. Maschine nach Anspruch 3 oder 4, bei der das Erfassungsmittel ein Mittel umfasst, das auf das Vorrücken der Schleifscheibe (10) während des Schleifzyklus reagiert und das so programmiert ist, dass es ein Signal erzeugt, wenn die Scheibe über eine gegebene Strecke vorgerückt ist, und dadurch anzeigt, dass der vorher bestimmte Übergrößen-Zustand erreicht ist, während dessen der Kühlmittelstrom geändert wird.
  6. Maschine nach einem der Ansprüche 3 bis 5, die einen Computer zur Steuerung des Schleifverfahrens umfasst, wobei sowohl die Position der Schleifscheibe bezüglich des Werkstücks sowie der Abstand zur Endgröße für den Computer verfügbar sind, wobei das Kühlmittel-Steuerungsmittel (18) durch Signale von dem Computer gesteuert wird.
  7. Maschine nach einem der Ansprüche 3 bis 6, bei dem das Kühlmittel-Steuerungsmittel ein Wahlventil (18) ist, das eine Kühlmittelpumpe und eine Düse (14) zum Bilden des Strahls verbindet und so betätigbar ist, dass es einen vollen Strom oder einen reduzierten Strom des Kühlmittels erzeugt.
  8. Maschine nach Anspruch 7, die weiterhin ein Stromregelventil (20) stromaufwärts des Wahlventils (18) aufweist, das so betätigbar ist, dass es den reduzierten Strom des Kühlmittels variiert.
  9. Maschine nach einem der Ansprüche 3 bis 8, bei der die Schleifscheibe (10) eine CBN-Scheibe ist.
EP19980307403 1997-09-20 1998-09-14 Verbessertes Schleifverfahren und Vorrichtung Expired - Lifetime EP0903200B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9719969 1997-09-20
GBGB9719969.9A GB9719969D0 (en) 1997-09-20 1997-09-20 Improved grinding process

Publications (2)

Publication Number Publication Date
EP0903200A1 EP0903200A1 (de) 1999-03-24
EP0903200B1 true EP0903200B1 (de) 2004-04-21

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EP19980307403 Expired - Lifetime EP0903200B1 (de) 1997-09-20 1998-09-14 Verbessertes Schleifverfahren und Vorrichtung

Country Status (4)

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EP (1) EP0903200B1 (de)
DE (1) DE69823293T2 (de)
ES (1) ES2219847T3 (de)
GB (2) GB9719969D0 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9999960B2 (en) 2013-12-31 2018-06-19 Saint-Gobain Abrasives, Inc. Coolant delivery system for grinding applications

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2357719B (en) * 1999-10-27 2003-06-04 Unova Uk Ltd Grinding machine having two wheels
GB0217593D0 (en) * 2002-07-30 2002-09-11 Raysun Innovative Design Ltd Method and apparatus for grinding
FR2949368B1 (fr) * 2009-08-28 2011-12-16 Essilor Int Dispositif et procede d'usinage de lentilles ophtalmiques
EP2394767A1 (de) 2010-06-10 2011-12-14 Siemens Aktiengesellschaft Durchflusskühlmitteladapter zur Verwendung in hohlen Spindelmaschinenwerkzeugen
JP5935568B2 (ja) * 2012-07-24 2016-06-15 株式会社ジェイテクト 研削盤および研削方法
JP6277705B2 (ja) * 2013-12-20 2018-02-14 株式会社ジェイテクト 研削盤および研削方法
JP7069634B2 (ja) * 2017-10-20 2022-05-18 株式会社ジェイテクト 研削盤及び研削方法

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1752684B1 (de) * 1968-07-02 1971-07-15 Lindner Gmbh Herbert Kuehlvorrichtung an Gewindeschleifmaschinen
GB1546590A (en) * 1976-12-01 1979-05-23 Henderson Diamond Tool Co Ltd Method and means of cooling in grinding operations
US4561218A (en) * 1985-02-08 1985-12-31 Ex-Cell-O Corporation Close tolerance internal grinding using coolant mist
US5402354A (en) * 1990-10-12 1995-03-28 Mitsubishi Jukogyo Kabushiki Kaisha Control apparatus and control method for machine tools using fuzzy reasoning
US5833523A (en) * 1996-09-03 1998-11-10 Hykes; Timothy W. Variable volume coolant system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9999960B2 (en) 2013-12-31 2018-06-19 Saint-Gobain Abrasives, Inc. Coolant delivery system for grinding applications

Also Published As

Publication number Publication date
DE69823293T2 (de) 2005-05-04
GB2329350B (en) 2002-09-11
DE69823293D1 (de) 2004-05-27
EP0903200A1 (de) 1999-03-24
GB2329350A (en) 1999-03-24
GB9819802D0 (en) 1998-11-04
GB9719969D0 (en) 1997-11-19
ES2219847T3 (es) 2004-12-01

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