EP0255267A2 - Dressage des meules de rectification - Google Patents

Dressage des meules de rectification Download PDF

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Publication number
EP0255267A2
EP0255267A2 EP87306327A EP87306327A EP0255267A2 EP 0255267 A2 EP0255267 A2 EP 0255267A2 EP 87306327 A EP87306327 A EP 87306327A EP 87306327 A EP87306327 A EP 87306327A EP 0255267 A2 EP0255267 A2 EP 0255267A2
Authority
EP
European Patent Office
Prior art keywords
wheel
speed
dressing
rotation
dressing wheel
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.)
Withdrawn
Application number
EP87306327A
Other languages
German (de)
English (en)
Other versions
EP0255267A3 (fr
Inventor
John Malcolm Barnard
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.)
Unicorn Industries Ltd
Original Assignee
Unicorn Industries 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
Priority claimed from GB868618882A external-priority patent/GB8618882D0/en
Priority claimed from GB868621387A external-priority patent/GB8621387D0/en
Application filed by Unicorn Industries Ltd filed Critical Unicorn Industries Ltd
Publication of EP0255267A2 publication Critical patent/EP0255267A2/fr
Publication of EP0255267A3 publication Critical patent/EP0255267A3/fr
Withdrawn legal-status Critical Current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
    • B24B53/00—Devices or means for dressing or conditioning abrasive surfaces
    • 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
    • B24B1/00—Processes of grinding or polishing; Use of auxiliary equipment in connection with such processes

Definitions

  • the invention relates to the dressing of grinding wheels, by which is meant the shaping of the outer peripheral surface of a grinding wheel to ensure that the wheel is perfectly circular and to provide its peripheral surface with an accurate cross-sectional profile having the desired surface characteristics.
  • the process of making the grinding wheel perfectly circular is normally referred to as “trueing” and the process of providing the required surface characteristics of the periphery of the grinding wheel is normally referred to as “conditioning”.
  • the invention is particularly applicable to the dressing of so-called "superabrasive" grinding wheels, as will be described hereinafter, but it may also be applied with advantage to the dressing of conventional grinding wheels.
  • Profiled grinding wheels are used for the accurate shaping of many different types of rotary machine parts, such as engine camshafts.
  • a grinding wheel which has been dressed to perform a certain operation will become worn in the course of its use and may require re­dressing many times during its working life to remove worn abrasive material and metal particles from the peripheral surface of the wheel as well as to restore the required exact cross-sectional profile to the peripheral surface.
  • Grinding wheels are normally manufactured from grains or particles of abrasive material held together and moulded into disc form by a bonding agent.
  • Typical abrasive materials are aluminium oxide and silicon carbide.
  • Various bonding agents are used such as synthetic resins, metals or vitrified materials.
  • dressing wheels consist of diamond particles embedded in a hard material such as nickel, tungsten carbide or other hard matrix.
  • the present invention sets out to provide a new method and apparatus for dressing a grinding wheel, providing a further parameter which may be varied to vary the conditioning of the surface of the grinding wheel.
  • a method of dressing a grinding wheel to form thereon a peripheral surface of a required cross-sectional profile comprising rotating the grinding wheel at a predetermined speed about its central axis, rotating about a parallel axis a dressing wheel having a hard peripheral forming surface the cross-sectional profile of which is the complementary inverse of said required cross-sectional profile, effecting relative movement between the dressing wheel and grinding wheel in a direction perpendicular to their axes of rotation to bring the peripheral surface of the dressing wheel into pressing engagement with the peripheral surface of the grinding wheel, maintaining said pressing engagement, and controlling the speed of rotation of the dressing wheel in a manner to provide a difference in speed between said engaging peripheral surfaces of the dressing wheel and grinding wheel.
  • the dressing wheel is controlled in such manner that its peripheral speed is less than the peripheral speed of the grinding wheel.
  • the surface conditioning of the grinding wheel may be varied by adjusting the speed of rotation of the dressing wheel and thereby varying the speed difference between the engaging surfaces of the wheels. Accordingly, for a given composition of grinding wheel and dressing wheel, the surface characteristics of the finished wheel may be determined in a predictable fashion by setting an appropriate predetermined speed of rotation for the dressing wheel. The effect of the surface speed difference will be to cause rotational "scuffing" of the surface of the dressing wheel relatively to the surface of the grinding wheel, in addition to the normal action. It is this scuffing, the extent of which depends, for given wheels, on the predetermined value of the speed of rotation of the dressing wheel, which determines the surface characteristics of the finished wheel.
  • the speed of rotation of the dressing wheel may be controlled by driving the wheel by means of a speed-­controllable electric servo-motor.
  • the speed of rotation of the servo-motor may then be continuously controlled so as to maintain the speed of rotation of the dressing wheel at a substantially constant predetermined value.
  • the speed of rotation of the servo-motor, and hence of the dressing wheel may be varied in a cyclic fashion.
  • the speed of rotation of the dressing wheel may be controlled by applying thereto a braking load when the speed of rotation of the dressing wheel is greater than a predetermined value, the magnitude of the braking load being variable and being such as to tend to reduce the speed of rotation of the dressing wheel towards said predetermined value.
  • the pressing engagement between the peripheries of the grinding wheel and dressing wheel may be maintained, in known manner, by feeding one wheel towards the other at a predetermined rate.
  • this feed rate may be controlled in accordance with the speed of rotation of the dressing wheel, in such manner that the feed occurs at a first rate when the speed of rotation of the dressing wheel is below said predetermined value, and at a second, lower rate when the speed of rotation is above said value.
  • the speed of rotation of the dressing wheel will be at or below the predetermined value before the wheels are brought into engagement and the wheels may thus be fed towards each other comparatively rapidly.
  • the grinding wheel will accelerate the dressing wheel above the predetermined rate of rotation with the result that the feed rate will be switched to a lower value appropriate for the wheels being in operative engagement.
  • the invention also provides apparatus for dressing a grinding wheel comprising means for rotating the grinding wheel at a predetermined speed about its central axis, means for rotating a dressing wheel about a parallel axis, means for effecting relative movement between the dressing wheel and grinding wheel in a direction perpendicular to their axes of rotation, means for sensing the speed of rotation of the dressing wheel, and control means for controlling the speed of rotation of the dressing wheel in accordance with signals from said speed sensing means in a manner to tend to return the speed of rotation towards a predetermined value when it departs from said value.
  • the means for rotating the dressing wheel about its central axis may comprise a rotatably mounted shaft having means for mounting the dressing wheel coaxially thereon, the brake means being operable on said shaft or a part rotatable therewith.
  • the brake means may comprise a disc brake mechanism, the disc of which is mounted on the shaft or part rotatable therewith.
  • the brake mechanism may be pneumatically actuated, and in this case said control means may include an air control valve which controls the supply of pressurised air to the brake mechanism.
  • the control means may further include a differential control device for comparing signals from the speed sensor with a pre-set datum indicative of said required predetermined speed, and actuating said air control valve in a manner to reduce the difference between said signals and the datum.
  • a dressing wheel 10 is mounted on the end of a rotary shaft 11 which is driven by an electric servo-motor 12 through a suitable coupling.
  • the arrangement is such that when the speed of rotation of the dressing wheel 10 departs from the value pre-set in the differential control device, as determined by the device comparing signals from the speed sensor 17 with the pre-set value, the servo-motor 12 is automatically controlled in a manner to restore the speed of the dressing wheel to the pre-set value.
  • Servo-motors and control systems to operate in this fashion are readily available commercially and the control system will not therefore be described in detail.
  • the electric motors 12 and 16 are initially switched on.
  • the dressing wheel 10 while it is not subjected to any external load, then rotates at the predetermined speed set in the differential control device which may, for example, be 750 rpm.
  • the grinding wheel 14 may, for example, be rotating at a speed of a 1000 rpm.
  • the grinding wheel 14 is fed towards the dressing wheel until the peripheries of the two wheels come into contact.
  • the grinding wheel increases the speed of rotation of the dressing wheel above 750 rpm.
  • the relative diameters of the wheels may be such that if the dressing wheel were freely driven by the grinding wheel it would reach a speed of something over 3000 rpm).
  • the differential control device 18 responds to reduce the speed of the servo-motor and hence of the dressing wheel.
  • the differential control device is also arranged to control the rate of feed of the grinding wheel towards the dressing wheel so that the feed rate drops, as soon as the dressing wheel speeds up over 750 rpm, from an initial rapid indexing rate to a lower operating rate.
  • the rate of feed of the grinding wheel may be controlled in accordance with the positions of the axes of rotation of the grinding wheel and dressing wheel, the rate of feed being reduced when the axes of the wheels reach a position where the peripheries of the wheels will be in contact.
  • the relative positions of the axes of rotation of the wheels may be sensed, for exammple, by using an optical grating, linear voltage differential transformer (LVDT), capacitive transducers, inductosyn transducers, or the like.
  • the signals from such devices are then used to control the rate of feed of the grinding wheel, so that the feed rate is reduced when a predetermined relative position of the wheels is reached.
  • LVDT linear voltage differential transformer
  • the grinding wheel 14 constantly tries to rotate the dressing wheel 10 at a speed greater than the predetermined 750 rpm, and the servo-motor 12 is constantly controlled to maintain the pre-set speed.
  • the invention thus allows predictable conditioning of the grinding surface of a grinding wheel where the profile of the surface, and/or the material of the wheel, makes such predictable conditioning difficult or impossible using conventional methods.
  • the differential control device 18 is again connected to the electric motor 12 driving the dressing wheel 10 and is arranged to switch off the motor when the speed of rotation of the dressing wheel reaches or exceeds a predetermined value.
  • this value is adjustable and may be pre-set in the differential control device.
  • the differential control device 18 also controls a solenoid actuated air control valve 20 which controls the supply of air from an air supply source 21 through a regulator 22 to a manifold 23 which distributes the air supply to a number of pneumatically operated brakes in the coupling and brake apparatus 13 associated with the drive to the dressing wheel 10.
  • the pneumatically operated brakes are indicated diagrammatically at 24.
  • the arrangement is such that when the speed of rotation of the dressing wheel 10 is greater than the value pre-set in the differential control device, as determined by the device comparing signals from the speed sensor 17 with the pre-set value, the air control valve 20 is operated so as to actuate the brakes 24 and thus reduce the speed of the dressing wheel 10.
  • the electric motors 12 and 16 are initially switched on.
  • the dressing wheel 10 while it is not subjected to any external load, then rotates at the predetermined speed set in the differential control device which may, as in the previous embodiment, be 750 rpm.
  • the grinding wheel 14 may, as before, be rotating at a speed of a 1000 rpm.
  • the differential control device is also arranged to control the rate of feed of the grinding wheel towards the dressing wheel so that the feed rate drops as soon as the dressing wheel speeds up over 750 rpm, from an initial rapid indexing rate to a lower operating rate.
  • the rate of feed of the grinding wheel may also be controlled in accordance with the positions of the axes of rotation of the wheels.
  • the dressing wheel 10 is mounted on one end of the shaft 11 the opposite ends of which are rotatably mounted in bearings 25 and 26 in a casing 27.
  • the end of the shaft 11 opposite to the dressing wheel 10 is connected by a coupling 28 to the output shaft of the aforementioned electric motor 12. Adjacent the coupling 28 there is mounted on the shaft 11 the disc plate assembly of a pneumatically actuated disc brake mechanism.
  • One of the pneumatically actuated brake pad mechanisms of the disc brake is indicated at 30 and a suitable number of such brake pad assemblies are disposed around the periphery of the disc.
  • the brake mechanism may be of a kind which is commercially available where the number of brake pad assemblies may be selected according to the braking power required. As previously mentioned, the brake mechanism is preferably of a kind where the braking torque is proportional to the operating air pressure.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Grinding-Machine Dressing And Accessory Apparatuses (AREA)
EP87306327A 1986-08-01 1987-07-17 Dressage des meules de rectification Withdrawn EP0255267A3 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB868618882A GB8618882D0 (en) 1986-08-01 1986-08-01 Dressing of super-abrasive grinding wheels
GB8618882 1986-08-01
GB8621387 1986-09-04
GB868621387A GB8621387D0 (en) 1986-09-04 1986-09-04 Dressing of grinding wheels

Publications (2)

Publication Number Publication Date
EP0255267A2 true EP0255267A2 (fr) 1988-02-03
EP0255267A3 EP0255267A3 (fr) 1989-03-08

Family

ID=26291116

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87306327A Withdrawn EP0255267A3 (fr) 1986-08-01 1987-07-17 Dressage des meules de rectification

Country Status (2)

Country Link
EP (1) EP0255267A3 (fr)
GB (1) GB2193127A (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0485339A3 (en) * 1990-11-07 1992-09-16 Reishauer Ag. Process and apparatus for shaping grinding wheels
US20160059331A1 (en) * 2013-05-15 2016-03-03 D.I.S. Industriesägen E.K. Sawing machine
CN114454042A (zh) * 2022-03-19 2022-05-10 北京博鲁斯潘精密机床有限公司 一种航空发动机叶榫叶片磨削机床的砂轮自动修整机构

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR963809A (fr) * 1947-07-11 1950-07-21
US2787095A (en) * 1955-08-08 1957-04-02 Nicholas M Lovett Wheel truing device
DE2321477C3 (de) * 1973-04-27 1979-11-15 Ernst Winter & Sohn, 2000 Hamburg Verfahren und Vorrichtung zum Abrichten und Schärfen von Schleifscheiben
US4222362A (en) * 1979-04-02 1980-09-16 Litton Industrial Products, Inc. Speed control for a rotary dressing wheel
DE3035635C2 (de) * 1980-09-20 1982-08-12 Ernst Winter & Sohn ( GmbH & Co.), 2000 Hamburg Verfahren zum Abrichten von Schleifscheiben mit Diamant oder kubisch kristallinen Bornitrid
ATE12603T1 (de) * 1980-12-11 1985-04-15 Maegerle Ag Geb Verfahren zum aufbereiten von schleifscheiben und vorrichtung zu dessen ausfuehrung.
CA1184991A (fr) * 1981-03-30 1985-04-02 Roderick L. Smith Methode et dispositif de dressage et de remise a profil des meules
EP0083672B1 (fr) * 1982-01-08 1987-03-25 Ernst Winter & Sohn (GmbH & Co.) Meule et procédé pour le dressage de celle-ci

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0485339A3 (en) * 1990-11-07 1992-09-16 Reishauer Ag. Process and apparatus for shaping grinding wheels
US20160059331A1 (en) * 2013-05-15 2016-03-03 D.I.S. Industriesägen E.K. Sawing machine
CN114454042A (zh) * 2022-03-19 2022-05-10 北京博鲁斯潘精密机床有限公司 一种航空发动机叶榫叶片磨削机床的砂轮自动修整机构
CN114454042B (zh) * 2022-03-19 2022-11-18 北京博鲁斯潘精密机床有限公司 一种航空发动机叶榫叶片磨削机床的砂轮自动修整机构

Also Published As

Publication number Publication date
GB2193127A (en) 1988-02-03
GB8716779D0 (en) 1987-08-19
EP0255267A3 (fr) 1989-03-08

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