Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D53/00—Making other particular articles
  • B21D53/26—Making other particular articles wheels or the like

Definitions

• the present invention relates to a method for producing a wheel for a motor vehicle comprising a wheel disc and a substantially cylindrical rim, the wheel disc being made up, of a substantially planar central part comprising a bearing which serves to center and to fix the wheel on the hub of the vehicle axle, a substantially conical interior rise, another inverted conical part defining, with the interior rise, a curve nose which has a large radius of curvature, the inverted conical part, rear part of the curved nose, ending with a fallen edge intended for the connection of the veil with the rim.
• the wheel disc and the rim are generally obtained by stamping and / or flow turning from a homogeneous sheet blank.
• the operations of forming a wheel wall from a single homogeneous sheet blank have the major drawback of not distributing, in particular, the thicknesses as desired. It is not possible to have physical and mechanical characteristics defined in areas for example, the most stressed or, to have thinning in areas of less mechanical stress. When the wheel is analyzed mechanically, it appears that in operation, the most stressed area of the wheel runout is the curve nose and the least stressed area of said runout is the fallen edge. To ensure in certain places a minimum admissible thickness, the sheet is oversized in thickness because it is necessary to take into account the localized thinning generated by the forming operation of the sheet blank. As a result, the wheel is overweight due to its design.
• the stress is generated by a compression of the sheet by means of a wheel.
• Compression of the work-hardening type causes surface plastic deformations which are detrimental to the visual appearance and the fatigue strength.
• work hardening can lead to incipient fractures.
• the stresses induced by this method are located in the extreme skin of the rim, which consequently limits their effect in the case in particular of the tensile-compression stresses encountered on the wheels in service.
• the recommended type of work hardening must be carried out before painting the surface of the wheel.
• a subsequent paint treatment associated with the thermal treatment of baking the paint has the effect of partially relaxing the stresses induced by the wheel and thereby reducing the effectiveness of the method.
• the stress field resulting from the forming operation in the critical zone of the curve nose has a "Z" characteristic.
• the lower skin of the shaping nose, or else, the concave part of the shaping nose is subjected to compression
• the so-called upper skin, or else, the convex part of the shaping nose is subjected to tension.
• the fatigue of the rotary bending type is locally assimilated to a bending of the alternating plane bending type at the level of the curve nose. That is to say that the loading of the wheel subjects the lower skin of the curve nose sometimes to a tensile force sometimes to a compression force, the behavior being reversed as regards the upper skin of the curve nose.
• the profile of the stresses in service of the wheel is the superposition of the two stress profiles resulting on the one hand from the forming of the wheel face and on the other hand from the load of the wheel in service.
• the object of the invention is to provide lightening of the wheel by locally improving the mechanical characteristics of said wheel, and this, by modifying the internal stress profile resulting from forming in certain parts of the wheel.
• the subject of the invention is a method for producing a wheel for a motor vehicle in which:
• a stress field opposing the stress field induced by the shaping and loading of the wheel in service is generated in the critical stress zones of the wheel in service, to compensate for the internal stress profile resulting from the forming wheel disc and / or rim so that the stress in service remains less than or equal to the maximum allowable stress.
• a coating is deposited on the area which absorbs part of the energy of the LASER radiation, - a layer transparent to the LASER radiation is deposited on the coating.
• the invention also relates to a wheel for a motor vehicle obtained by implementing the method.
• Figure 1 is a sectional view of a wheel of a land motor vehicle having the different parts of said wheel.
• Figure 2 is an explanatory sketch of the physical phenomenon generated by the impact of LASER radiation.
• Figure 3 is a sectional view of a vehicle wheel according to the invention subjected to the impact of LASER radiation.
• the invention relates to a method of producing a wheel 1 for a motor vehicle comprising, as shown in FIG. 1, a wheel disc 2 and a substantially cylindrical rim 3, the wheel disc 2 being made up of a substantially flat central part 4 having a bearing surface 5 which serves to center and fix the wheel 1 on a hub of an axle, a interior rise 6 substantially conical, another inverted conical part 7 defining, with the interior rise 6 a curved nose 8 which has a large radius of curvature, the inverted conical part 7, rear part of the curved nose 8, ending in a dropped edge 9, intended for the connection of the web 2 with the rim 3.
• the invention relates to a method for producing a wheel wall in which:
• the main dimension parameters of the wheels are the thickness of the starting blank and the steel grade used. Taking into account the choice of steel grade, the thickness of the starting blank is chosen by calculating the stress value at the level of the critical zone, for example of the curve nose.
• an internal stress field opposing the stress field induced by the shaping of the web and / or the rim and the load in service are generated in a critical stress area of the wheel in service. said wheel.
• - at least one critical zone of stress of the wheel is subjected to an impact inducing in the zone, compressive stresses by shock wave.
• At least one critical zone of stress of the wheel is subjected to the impact of a water jet. In another example of application of the invention, at least one critical zone of stress of the wheel is subjected to the impact of LASER radiation.
• the method of the invention does not in any way modify the visual appearance of the critical zone.
• the impact does not produce a macroscopic surface defect, which avoids any initiation of induced rupture.
• the impact based on the principle of a shock wave, generates induced stresses in depth, which can influence 8 mm in depth under critical area, the process is therefore well suited for the loading of a sheet.
• the method of the invention can be used on a wheel which has already been coated with a paint and subjected to baking temperature.
• Zone 1 1 focused is transformed into plasma and the high pressure generated is transmitted to the metal surface 1 2 via a very strong shock wave.
• a coating 1 3 absorbing the radiation of the beam 10 LASER.
• a layer transparent to the radiation of the LASER can be deposited on the coating 13.
• the residual stress value generated by the shock can reach 300 MPa at the surface, 100 MPa at 0.5 mm deep and around 1 mm, the stress level is practically zero.
• the pressure of the jet is more than 4000 Kg / cm 2 for a flow rate of 6 liters / min.
• two modes can be envisaged from the point of view of the distribution of the impact.
• a first mode the wheel is fixed.
• the impact for example of a LASER radiation can be generated by a localized beam 10 deflected by a conical prism, a fixed annular mirror directing the beam, for example, on the inner part 12 of the curve nose.
• the impact can be punctual, the beam 10 directed on a mirror 1 6 rotating for the scanning for example of the interior part 1 5 of the curve nose 8.
• the wheel In a second mode, the wheel is in rotation.
• the impact, for example, of LASER radiation is generated by a continuous or pulsed fixed beam, the target of which is a point on a generator of the veil of the wheel, a generator belonging for example to the curve nose.
• the level of stress in service in the critical zone of a wheel disc requires a sheet blank thickness of 4.4 mm when the method according to the invention is not implemented.
• a reduction in the thickness of the sheet blank of the order of 1.4 mm can be accepted by compressing the critical zone of the curve nose by approximately 160 MPa.
• the weight gain is then 1.5 kg, for a wheel which, according to the invention will weigh approximately 3.5 kg, which generates a gain of 30%.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Arrangement Or Mounting Of Propulsion Units For Vehicles (AREA)
• Heat Treatment Of Articles (AREA)
• Electric Propulsion And Braking For Vehicles (AREA)
• Manufacture Of Motors, Generators (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=9488968

Family Applications (1)

Country Status (6)

Families Citing this family (1)

Family Cites Families (3)

• 1996
  • 1996-02-08 FR FR9601526A patent/FR2744657B1/fr not_active Expired - Fee Related
• 1997
  • 1997-02-07 WO PCT/FR1997/000243 patent/WO1997028914A1/fr active IP Right Grant
  • 1997-02-07 EP EP97903421A patent/EP0879105B1/de not_active Expired - Lifetime
  • 1997-02-07 DE DE69704052T patent/DE69704052T2/de not_active Expired - Fee Related
  • 1997-02-07 ES ES97903421T patent/ES2154024T3/es not_active Expired - Lifetime
  • 1997-02-07 AT AT97903421T patent/ATE199070T1/de not_active IP Right Cessation

Non-Patent Citations (1)

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