FR2783641A1 - Machine tool for rectifying contact surfaces includes hard cutting surface at specified angle w.r.t. rotating machine contact surface - Google Patents

Abstract

The device for correcting the rotary contact surface of an electrical machine in situ comprises a very hard cutting tool situated in contact with the contact surface. The cutting tool is inclined w.r.t. the radius of the contact. Waste material is evacuated by a suction device near to the operating edge of the tool. The tool is arranged with its work surface at an angle ( beta ) w.r.t. the surface of the contact ( beta lies in the range 3 - 12 degrees). The support sleeve then lies an at angle ( delta ), this angle ( delta ) preferably lying in the range 5 - 10 degrees. The material uses for the cutting tool may be diamond.

Description

l

  METHOD, TOOL AND DEVICE FOR IN SITU GRINDING OF

  MANIFOLDS AND RINGS OF ELECTRIC MACHINES

  Field of the Invention The invention relates to electrical machines, such as motors, comprising manifolds or rings fixed to the rotor of said machines. It concerns everything

  particularly the rectification of said collectors and rings.

  Said collectors and rings are collectively referred to below as the expression

"rotary contacts".

  State of the art As part of the general maintenance of industrial electrical machines, it is well known to correct their rings or their collectors when they have developed a peripheral circularity defect, that is to say when they do not no longer have a sufficiently uniform radius over their entire periphery. This operation prolongs the life of the rotary contacts, limits the wear of the brushes and stops the

mechanical vibrations.

  The rectification of industrial machines is generally a cumbersome operation which involves significant costs and delays. The traditional methods of rectification require a long intervention on the machine, which involves stopping the machine for a long and variable period of time, depending on the difficulties encountered during the intervention. Typically, the complete rectification operation includes the uncoupling of the machine and its mechanical load, the removal of the machine and transport to a duly equipped workshop where the actual rectification takes place. Workshop interventions include dismantling the rotor and rectifying it in the traditional lathe. In the case of collectors, the rectification may also require an additional step of lowering the micas and the resin, generally using a rotating disc, and breaking the angles.

protruding of the manifold blades.

  However, these methods have significant drawbacks, such as the need to realign the machine following the rectification, the impossibility of taking into account,

  in the workshop, deformations of the shaft line in the bearings.

  In order to avoid these difficulties, it is now known to carry out "in situ" rectification of the rotary contacts. To this end, a rectification device is used comprising a frame, which is mounted in the head of the machine, means for fixing and turning a dry machining tool, and an auxiliary means for driving the machine and thus rotating the rotary contact to be rectified, such as an auxiliary motor. The combination of the rotational movement of the rotary contact and the axial displacements of the tool obtained using the turning means ensures a rectification of the entire i5 surface of the rotary contact. The machining tool is generally an abrasive stone in order to '' avoid the risk of damage by biting or penetrating metal, this type of damage occurring easily with standard tools when the frame

  slightly bends during machining.

  However, rectification in situ, according to the state of the art, remains a long operation which immobilizes the machine for a significant period of time, which is typically a few tens of hours, and which results in the deposition in the winding of the machine waste and machining dust, such as metal shavings removed by machining,

  which can lead to the formation of short circuits.

  The Applicant has therefore sought means and methods for in situ rectification of rotary contacts of electrical machines which reduce the length of interventions significantly and which eliminate the risks of short circuits.

  consecutive to the rectification operation.

Description of the invention

  The first object of the invention is a method of rectifying the rotary contacts of electrical machines in which a cutting tool of very high hardness is used and inclined with respect to the radius of said contact so as to cause low penetration into said contact and to produce cutting waste of small dimensions, and in

  which said waste is evacuated by suction near the pellet of said tool.

  According to the invention, the method of rectifying a rotary contact of an electric machine, said rotary contact being fixed to the rotor of said machine, comprises the installation of a rectification device, the rotational drive of said rotor, so as to produce a rotary movement of said contact, and the machining of said rotary contact using said device, said device comprising a grinding tool and a turning means of said tool, said tool comprising a fixing handle and a pad of dry machining, said pellet comprising a working face, said method being characterized in that said pellet is made of a material of high hardness, that is to say of hardness at least equal to 10 on the Mohs scale, in that the machining waste is evacuated by suction near said pad, and in that said tool is placed relative to said contact so that said working face is inclined at an ang the y, called "cutting angle", towards the front relative to the direction of rotation of said contact, the angle 3 preferably being between 3 and 12, and more preferably still between 5 and 10, and so that said handle is inclined at an angle towards the rear with respect to said direction of rotation, angle 6 preferably being included

between 5 and 10.

  The angles f3 and 6 are such that the machining produces cutting waste of sufficiently small dimensions to be easily aspirated and evacuated by said suction and

  such as machining does not cause the metal to bite or penetrate.

  The invention also relates to a rectification tool which makes it possible to set up

  implements the rectification process of the invention.

  The grinding tool according to the invention comprises a fixing handle and a machining pad, said pad comprising a working face, and is characterized in that said pad is made of a material of high hardness, that is to say -d say hardness at least equal to 10 on the Mohs scale, in that said working face is inclined upwards by a vertical angle of relative to the main axis of said handle, preferably between 80 and 220, and preferably still between 100 and 200, and in that it comprises means for suction and removal of machining waste

  making it possible to produce a suction zone near said machining pad.

  The invention also relates to a rectification device making it possible to

  implements the rectification process of the invention.

  The device for rectifying a rotary contact according to the invention comprises a frame, a dry machining tool, comprising a fixing handle and a machining pad, and means for fixing and turning said tool, and is characterized in that said frame makes it possible to mount said tool so that said handle is inclined towards the rear with respect to the direction of rotation of said contact by an angle 6 preferably between 5 and 10, and so that the working face is inclined towards the front with respect to said direction of rotation by an angle 3, called cutting angle, preferably between 3 and 120, and more preferably between 5 and 10, and in that '' it includes means of suction and evacuation of machining waste produced at

near said patch.

Description of the figures

  Figure I shows, schematically, a rectification device (1) of rotary contacts of electric machines according to the prior art mounted on an electric machine head, (a) in side view and (b) in axial view according to the section plane AA '(b). n0 The rectification device (1) of the prior art typically comprises a frame (2), which is mounted in the head of the machine (21), fixing means (4) and displacement and turning means ( 5) a dry machining tool (3), and an auxiliary means, such as an auxiliary motor, for driving the machine and thus rotating the rotary contact (20) to be rectified. The grinding device is generally fixed to the machine using the fixing pin (6) of the brush holders (7). The combination of the rotational movement of the rotary contact (S) and the axial displacements (D) of the tool obtained using the turning means ensures rectification of the entire surface of the rotary contact. FIG. 2 illustrates schematically , a contact rectification device

  rotary machines of electric machines according to the invention, seen in the axis of the machine.

  FIG. 3 defines the angles relative to the orientation of the cutting tool and to the face of

  working of the machining pad according to the invention.

  FIG. 4 illustrates the cutting tool according to a preferred embodiment of the invention,

  seen from the side (a) and seen from above (b).

  FIG. 5 illustrates a collector milling cutter intended for lowering the micas and the

  resin used for rectifying the collectors according to the invention.

  Detailed description of the invention

  According to the invention, the method for rectifying a rotary contact (20) of an electric machine (23), said rotary contact being fixed to the rotor (22) of the machine, comprises the installation of a rectification device ( 1, 10), the rotation drive of the rotor (22), and the machining of the contact (20) using the device (1, 10), said device comprising a grinding tool (13) and a means for turning said tool, said tool comprising a fixing handle (32) and a dry machining pad (34), said pad comprising a working face (35), said method being characterized in that said pad (34) is made of a material of high hardness, that is to say of hardness at least equal to 10 on the Mohs scale, in that the machining waste is evacuated by suction near the pellet (34), and in that the tool (13) is placed relative to the contact (20) so that the working face (35), which defines a plane P, is inc lined at an angle 3, called "cutting angle", towards the front with respect to the direction of rotation (S) of the contact (20) and in such a way that said handle (32) is inclined by an angle ô towards the rear relative to said direction of rotation (S), the angles being measured relative to the

radius R of said contact.

  The angle 6 can be measured between the longitudinal axis (31) of the handle (32) or a parallel axis (310) passing through the point of contact between the pad and the rotary contact.

the radius R of the contact.

  Said high hardness material is preferably a diamond. The machining pad (34) can be fixed to the tool (30) via a machining plate (33). Preferably, the angle y between the axis (31) of the handle and the front plane (Q) of the pad (34) is less than 100, so as not to hinder the positioning of the pad (34) by

report to contact (20).

  The cutting angle 13 is small, and preferably between 3 and 12, and more preferably between 5 and 10. On the one hand, a too inclined cutting angle

  forward would increase the risk of biting into the metal prohibitively.

  On the other hand, too large a cutting angle would reduce the amount of metal removed by the machining pass and unnecessarily increase the number of passes, and by

  therefore the length of the intervention.

  Preferably, said suction forms a confined suction zone near the pellet (34), so as to efficiently channel the machining waste, to limit its dispersion and to increase the efficiency of the suction. This confinement is advantageously obtained using means such as a sleeve or a cover, these

  means preferably being of electrically insulating material.

  The Applicant has surprisingly found that the combined use of a material of great hardness to perform the rectification of the rotary contact, of a slight inclination towards the front of the machining pad and of a slight inclination towards the back of the tool handle allows grinding to be carried out quickly and very reliably, with high precision and without deterioration of the contact, while effectively eliminating machining waste. The high hardness pad offers a wear rate during machining which is sufficiently low that it is not necessary to advance said tool with each pass and to penetrate deeply into the material to be machined. The invention thus makes it possible to produce small waste which is easy to evacuate by means of suction of small dimensions and to carry out the rectification at high speed, without causing untimely bites of the contact surface by the pad. machining when the frame bends or deforms during grinding, which avoids breaking the contact and damaging it irreparably. It seems that the inclination of the tool (30) produces a spring effect which appreciably limits the grip in the metal in the event of bending of the grinding device and thus reduces the risks.

of bites.

  According to a preferred embodiment of the rectification method of the invention, the working face (35) is inclined upwards by a vertical angle c, which is preferably between 8 and 22, relative to the axis (31) of the handle (32) of the tool (30), and the cutting angle f3 is obtained by tilting the handle (32) relative to the radius R of the contact (20) by a vertical angle 5 between 5 and 10. The angle c thus corresponds to the sum of the angles 3 and o. When the angle AC is too small, the working face (35) approaches the vertical with respect to the surface of the contact (20) and the bending tolerance of the grinding device decreases sharply. When the angle c is too

  large, the support of said device is subjected to excessive torsional forces.

  The grinding tool (130) according to the invention comprises a fixing handle (132), a rear part (141), a front part (140), and a dry machining pad (134) fixed on said part. front and comprising a working face (135), said tool being characterized in that the pad (134) is made of a material of high hardness, that is to say of hardness at least equal to 10 on the scale of Mohs, in that the working face (135) is inclined upward by a vertical angle oE, relative to the main axis (131) of the handle (132) - or relative to a parallel axis (1310) passing through the point of contact between the patch (34) and the rotary contact (20) -, which is preferably between 8 and 22, and more preferably between 10 and 20, and in that it comprises means suction and evacuation of machining waste near the machining pad (134), said suction and evacuation means producing

  a suction area near the tool pad.

  Said high hardness material is preferably a diamond. The machining pad

  (134) can be fixed to the tool (130) by means of a machining plate (133).

  The insert (133) is firmly attached to the tool using a fastening means (1331), such as a bolt. Preferably, the angle y between the axis (131) of the handle and the front plane (Q) of the pad (134) is less than 100, so as not to hinder the positioning of the pad (134) relative to on contact (20). The front plane (Q) of the pad (134) is preferably slightly set back relative to the front end (142) of the tool, that is to say that said end is slightly prominent, so as to offer sufficient mechanical support and avoid, in particular,

  too much shear on said pellet.

  According to a preferred embodiment of the invention, said suction and evacuation means comprise a pipe (137) integrated into the handle (132), preferably substantially in the longitudinal axis (131) of the handle, said pipe comprising at least one suction inlet (136) near the machining pad (134) and at least one outlet (138) provided with fixing means (139) to an external suction and waste evacuation system machining. Said suction means create an effective suction zone in the vicinity of the machining pad. According to an advantageous variant of this preferred embodiment, illustrated in FIG. 4, the pipe (137) comprises a main channel (1371) exiting on the rear part (141) of the handle (132), that is to say opening at the end of the handle farthest from the machining insert, and three inlets (1361, 1362, 1363) located in the vicinity, and distributed around, from the machining pad, an inlet, called upper inlet (1363) , is located on the top of the handle and the other two inlets, called side inlets (1361, 1362) are located on either side of the handle. The outlet (s) located near the machining insert advantageously have a shape which promotes efficient channeling and aspiration of machining waste, such as a

conical nozzle shape.

  When the drive is carried out under voltage, as is notably the case with the auxiliary power supplies, it is advantageous to provide the tool (130) with electrical isolation means Io, so as to eliminate the electrical risks, in particular the formation of short circuits at the level of the machining plate which could damage the surface of the collector. For this purpose, one or more sides of the handle (132) of the tool (130) may be coated, in whole or in part, with pieces of material

  electrically insulating, such as insulating plates (16).

  According to the invention, the rectification device (10) comprises a frame (12), a dry machining tool (13), comprising a fixing handle (32), a front part (40) and a rear part ( 41), the front part (40) comprising a machining pad (34), the frame (12) comprising at least one fixing means (14) and means of turning and vertical displacement (15) of said tool, the pad (34) comprising a working face (35), and is characterized in that the frame (12) allows the tool (13) to be mounted so that the main axis (31) of the handle (32) is inclined backwards with respect to the direction of rotation (S) of the contact (20) by a vertical angle ô preferably between 5 and 10, and so that the working face (35) of the pad (34 ) is inclined towards the front by an angle 3 relative to said direction of rotation, preferably between 3 and 12, and more preferably between 5 and 10, and in that it comprises suction means ation and disposal of machining waste produced in

  near the pad (34) of the tool (13).

  The frame (12) is generally fixed to the head (21) of the machine using one of the fixing pins (6) of the brush holders (7). In this case, the frame (12) is preferably fixed to one of the fixing axes (6) of the brush holders by means of a support (Il1). The frame support (11) allows the inclination of the frame and the tool to be adjusted and keeps the frame fixed in place during grinding operations. The frame support (II) can be adapted to each type of machine, so as to facilitate the positioning and positioning of the frame and the tool. According to a preferred embodiment of the invention, illustrated in FIG. 2, the frame (12) comprises a frame body (121) which can be fixed to the support (I 1) and which is provided with said fixing means ( 14), turning and movement (15) of the tool. Said 1o means preferably comprise a carriage (155), a rack screw (151), an axial sliding support (152), a vertical sliding support (153) maneuverable using manual means (154) , such as a crank, and fixing means (14), such as a bolt. Said means of suction and discharge of machining waste are preferably integrated into the tool (13), so that at least one suction inlet (36) opens near the pellet (34) of the tool (13) and that at least one evacuation duct (17) fixed to the rear of the tool (13) evacuates the waste (E) using a suction system and outside evacuation. The integration of the suction and evacuation means of machining waste makes it possible to considerably limit the size of the device. Advantageously, the front part (40) of the tool (13) is provided with confinement means (18). , such as a sleeve or a cover, which make it possible to efficiently channel machining waste towards the inlet (s) (36) and to limit their dispersion outside the suction zone produced by said suction means. The confinement means (18) are preferably made of electrical insulating material, so as to avoid the possible formation of short circuits by means of the

metal machining waste.

  When the drive is carried out under voltage, as is notably the case with 3o auxiliary power supplies, the tool (13) is then electrically isolated from the frame (12), so as to eliminate electrical risks, in particular the formation of short circuits to the right of the machining pad which could damage the surface of the collector II. This electrical insulation is advantageously obtained by providing one or more sides of the handle of the tool (13) with pieces of electrically insulating material, such as insulating plates (16), preferably inserted between the fixing means (14) and the 'tool. The insulating pads can also be fixed to the tool, which facilitates the positioning of the tool. For the rectification of the collectors, it is necessary to carry out a drive of the rotor (22), which can be obtained by any known means. The drive is advantageously carried out using low voltage auxiliary power supplies, that is to say capable of delivering voltages below 40 V, the intensity of which is just sufficient to cause the rotation of the motor. The use of a low voltage significantly reduces the electrical risks for the operator and for the devices, and considerably limits the amount of damage to the surface of the collector.

  produced by possible short circuits being rectified.

  Said auxiliary power supplies are connected to a single-phase or three-phase current source, depending on the power required for driving the motor. The current is preferably rectified, then chopped at high frequency, that is to say at a frequency greater than 1000 Hz, which allows fine regulation of the intensity of the current and therefore of the angular speed of the motor driven in rotation by this current. The low voltage is preferably obtained using a transformer integrated into said

  power supplies, so that the motor can be electrically isolated from the mains.

  Said power supplies advantageously include a remote control allowing the operator to remotely control the voltage to be delivered. The precise configuration of these supplies varies according to the type of motor, its nominal power and the type of drive. It is advantageous to use a first auxiliary power supply for the excitation and a second, more powerful auxiliary power supply for the armature, that is to say of sufficient power to drive the rotation in

machining courses.

  In the case of collectors, the rectification process may also include operations of lowering the micas and resins located between the blades and breaking or milling the edges of the blades. These operations of lowering and breaking the angles are also long operations which, moreover, require the use of two different tools, namely a micas cutter to reduce their height and a blade.

  bevelled to deburr the edges of the blades.

  According to the invention, for these operations, it is advantageous to use a collector cutter (50) comprising a mini-drill in a handle (58) provided with an angle gear (51), a disc of mixed milling (53), fixed to the shaft (59) of the bevel gear (51) using a fixing means (57), and at least two support rings (54, 55) allowing the disc (53) to be kept at a calibrated distance from the blades (201) of the collector (200). The mixed disc (53) comprises a central disc (531) of diameter Dl sprinkled with diamond dust (533) on its periphery, which allows the abrasion of resins and micas (202), and, on both sides , two conical burs (532, 534), of diameter D2 less than DI, provided with teeth intended for milling the edges of the blades (201). The support rings (54, 55) are attached on either side of the mixed disc (53) and rest on the collector (200) during milling in order to adjust the milling depth. Advantageously, one of the rings (55) is placed around the bevel gear (51) and the other ring (54) is supported by an arm (56) fixed to the handle (58) using a means of fixing (52). The rings (54, 55) are preferably made of chrome so as to reduce the coefficient of friction between the rings

  and the manifold blades and to facilitate the movement of the micas cutter.

  Tests Rectification operations were carried out, according to the prior art and according to the invention, on 2.5 MW motors. For the tests according to the invention, the device and the rectification tool were very similar to those illustrated in FIGS. 2 to 4. The

  angles 6 equal to 7.5 and angle P3 equal to 7.5 (the angle AC was equal to 15).

  The complete rectification of an engine according to the invention could be carried out in 2 hours

  approximately, whereas it typically takes 24 hours according to the prior art.

  In some cases it was necessary to lower the micas and the resin. This operation was carried out using a collector cutter similar to that illustrated in FIG. 5. This additional step could be carried out in 3 hours on average, so

  that it requires approximately 10 hours with the means of the prior art.

  It has been observed that the size of the machining waste does not exceed about 500 µm.

  No machining waste was found on the surface of the collector following the operation

rectification.

  Advantages The invention easily adapts to all known electrical machines and are

of an easy implementation.

  The rectification device according to the invention allows rectification in a confined environment

thanks to its compactness.

Claims (18)

  1. Method for rectifying a rotary contact of an electric machine, said rotary contact being fixed to the rotor of said machine, said method comprising the installation of a rectification device, the rotational drive of said rotor, so as to produce a rotary movement of said contact, and the machining of said rotary contact using said device, said device comprising a grinding tool and a turning means of said tool, said tool comprising a fixing handle and a pad of dry machining, said pellet comprising a working face, said method being characterized in that said pellet is made of a material of high hardness, that is to say of hardness at least equal to 10 on the Mohs scale, in that the machining waste is evacuated by suction near said pad, and in that said tool is placed relative to said contact so that said working face of said pad is inclined by an angle 3, called "cutting angle", towards the front relative to the direction of rotation of said contact, the angle f3 being between 3 and 12, and so that said handle is inclined by an angle 6 towards the rear with respect to said direction of rotation, the angle 6 being between 5 and 10.   2. Rectification method according to claim 1, characterized in that said   high hardness material is diamond.   3 Method according to one of claims I and 2, characterized in that said angle of   section 3 is between 5 and 10.   4. Method according to one of claims I to 3, characterized in that said   suction forms a confined suction zone near said pellet, so as to efficiently channel machining waste, to limit its dispersion   and increase the efficiency of the suction.   5. Method according to claim 4, characterized in that said confinement is   obtained using a means such as a sleeve or a cover.   6. Method according to claim 5, characterized in that said confinement means is made of an electrically insulating material.   7. Method according to one of claims I to 6, characterized in that it comprises   the use of low voltage auxiliary power supplies allowing the rotor to rotate when said rectification method is applied to collectors.   8. Method according to one of claims 1 to 7, characterized in that, when said   process is applied to a collector, it includes the use of a collector cutter for lowering the micas and the resin located between the blades of said   collector and for milling the edges of said blades.   9. Method according to claim 8, characterized in that said collector milling cutter comprises a mini-drill provided with a bevel gear, a mixed milling disc and at least two support rings making it possible to maintain said disc at a calibrated distance from the blades of the collector, said mixed disk comprising a central disk of diameter Dl sprinkled with diamond dust on its periphery, so as to allow abrasion of the resins and micas of said collector, and, on both sides other, two conical burs, with diameter D2 less than   DI, provided with teeth intended for milling the edges of the blades of said collector.   10. Rectification tool for implementing the rectification process according to   one of claims I to 9, said tool comprising a fixing handle, a   rear part, a front part and a dry machining pad, said dry machining pad being fixed on said front part and comprising a working face, said tool being characterized in that said pad is made of a hardness material high, that is to say of hardness at least equal to 10 on the Mohs scale, in that said working face is inclined upward by a vertical angle ct relative to the main axis of said handle between 8 and 22, and in that it comprises means for suction and evacuation of machining waste to   near said machining pad.   1 1. Grinding tool according to claim I0, characterized in that said   high hardness material is diamond.   12. Grinding tool according to one of claims 10 or 11, characterized in   that said vertical angle oc is between 10 and 20.   13. Grinding tool according to one of claims 10 to 12, characterized in that   said suction and evacuation means comprise a pipe integrated into said handle, preferably substantially in the longitudinal axis of said handle, said pipe comprising at least one inlet near the machining insert and at least one outlet provided with means fixing to a system   external suction and evacuation of machining waste.   14. Grinding tool according to claim 13, characterized in that said pipe comprises a main channel exiting on the rear part of the handle and   three entrances located close to and distributed around the machining pad.   15. Grinding tool according to one of claims 10 to 14, characterized in that it   includes electrical isolation means.   16. Rectification device for implementing the rectification process according to   one of claims 1 to 9, said device comprising a frame, a tool   dry machining, comprising a fixing handle, a front part and a rear part, said front part comprising a machining pad, said frame comprising means for fixing said tool and means for turning and vertically moving said tool , said pad comprising a working face, said device being characterized in that said frame makes it possible to mount said tool so that the main axis of said handle is inclined rearward relative to the direction of rotation of said contact of a angle 8 of between 5 and 10, and such that the working face is inclined towards the front with respect to said direction of rotation by an angle 3 of between 3 and 12, and in that it comprises means for suction and evacuation of machining waste produced near said tool pad.   17. Device according to claim 16, characterized in that said cutting angle 13 is between 5 and 10.   18. Device according to claim 16 or 17, characterized in that said suction and evacuation means of machining waste are integrated into said tool, so that at least one suction inlet opens near the tool pad and at least one discharge duct fixed to the rear of the tool discharges   waste using an external suction and evacuation system.   19. Device according to one of claims 16 to 18, characterized in that the part   before the tool is provided with confinement means making it possible to efficiently channel machining waste towards the suction inlet (s) and to limit their dispersion outside the suction zone produced by said suction means.   20. Device according to one of claims 16 to 19, characterized in that said tool   is electrically isolated from said frame.