FR2648153A1 - METHOD FOR MANUFACTURING ROLLING BEARING ELEMENTS - Google Patents

Abstract

A method of manufacturing rolling bearing elements comprising a low alloy steel support and at least one through-hardened rolling steel raceway. For the support 6, a steel with a carbon content of 0.15-0.40% is used which is also austenitized when maintaining the rolling element at the hardening temperature and which is also transformed into a structure. martensitic during abrupt quenching of the bearing element.

Description

i

  METHOD FOR MANUFACTURING BEARING BEARING ELEHENTS

  The present invention relates to a method of manufacturing rolling bearing elements comprising a low-alloy steel support and at least one raceway made of steel for a core-hardening bearing, in which the support is securely joined together and the one or more rolling tracks into one and the same bearing element by force joining and / or forming, after which the element is heated to the quenching temperature and maintained at this temperature for the austening of the of the raceway (s), followed by quenching in the oil, salt or water to obtain a martensltlque structure with a Rockwell C hardness of 58 to 64%.

  the steel of the raceway (s).

  In a known process of this type, the materlaux of the support and of the raceway of an outer ring of a bearing are chosen so that, during quenching, the raceway undergoes a greater increase in volume than the surrounding support (German Patent 27 45 527). A major disadvantage of this known method lies in the fact that due to the greatest increase in the volume of the raceway, there occurs at the transition between the raceway and the support significant internal tensions which can affect the shape precision of the outer ring of the

  rolling and its resistance to fatigue.

  In addition, with the known method, it is possible to manufacture only the outer ring, but not the inner ring and / or the corresponding rolling elements of a rolling bearing. In the case of a bearing pallet element comprising a raceway installed on a lateral surface of the support, the raceway increasing more volume during quenching would indeed detach from the support. However, efforts are also made to provide interlocking rings or rolling elements with a bearing of one

  hardened steel raceway for rolling.

  It is therefore an object of the invention to improve a method of manufacturing rolling bearing elements of the aforementioned type, so that it can also be used for the manufacture of rolling bearing elements of any shape. . In addition, it aims to ensure that rolling bearing elements manufactured with this process have only low internal tensions in the transition zone.

  between the raceway and the support.

  This result is achieved according to the invention by the fact that for the support, a steel with a carbon content of 0.15 to 0.40% is used, which is also austenitized when the rolling element is held at temperature. quenching and is also transformed into a martensltic structure during quenching

of the element to pallet.

  With the method according to the invention, it is possible that it is only the runway of the bearing element that is made of an expensive rolling steel. hardening at heart, for example 100 Cr 6, while the support can be made of a better steel step. During quenching of the bearing element, each running track, as well as the corresponding support, as a result of common austenitization, undergo an increase in volume which is about equal in size. In this way, during quenching, only low internal stresses occur, caused by the change of structure, at the level of

  the transition between the raceway and the support.

  The raceway can therefore also be made thin-walled, so that it can be of a significantly lower weight than that of the corresponding support. Thanks to the uniform increase of volume of the raceway and the support during the quenching of the bearing element, the raceway can also be installed on a lateral surface of the support without there being any risk that the path rolling away from the support during quenching of the bearing element. With the method according to the invention, it is therefore possible to manufacture bearing elements of any shape, for example the inner ring, the outer ring and / or the

  rolling elements of a rolling bearing.

  In a process according to the invention, before they are assembled by force and / or shaped into a one-piece bearing element, the at least one raceway and / or at least one support surface is coated on their reciprocal transition surfaces. a thin metal layer which diffuses into the acler of the raceway (s) as well as into the steel of the support during quenching of the roughness path (s) and support. Thanks to this operation, we obtain one. particularly intimate assembly of the raceway (s) and the corresponding support, since the metallic layer diffuses into the steel of the race (s) and the support at their mutual transition surfaces, and this, as well as during the force-fitting and / or shaping of the support with the raceway only when

  the resultant quenching of the bearing element.

  The invention will be better understood using the

  description of a mode of realization taken as an example,

  but not ilmitatlf, and illustrated by the accompanying drawing, wherein: Figure 1 is a longitudinal section of a rolling bearing comprising an outer bearing member and an inner bearing member which are manufactured according to the method according to the invention; FIG. 2 is a longitudinal section of an alternative rolling bearing comprising an outer bearing element and rolling elements which are

  in accordance with the process according to the invention.

  In FIG. 1, there is shown a rolling bearing comprising an annular outer member 1 and an eleinmen: L-interleveled in the form of a machine shaft. Between the outer bearing element 1 and the inner pallet element 2 are cylindrical rollers as rolling elements 3 which are embedded in an annular honeycomb cage. 4 in piastic and turning in the direction

  perlpherlque during operation.

  The outer bearing element 1 and the element

  internal bearing 2 are constituted by a rolling track 5 in.acler rolling soaking heart and by

  a support 6 of low alloy steel.

  In FIG. 2, a variant rolling bearing is shown which comprises an annular outer element 7, an annular inner element 8 and, between

  them. cylindrical rolling elements 9.

26 4 8 153

  In the present case, the pallet elements 9 comprise a continuous central bore 10 extending in the axial direction. A cylindrical axis 11 of a cage 12 passes through the bore 10 of each bearing element 9. At its two ends, each axis 11 is securely connected by rivets 13 to a lateral washer 14 of the cage 12. The axles 11, which engage with low sliding clearance in the bore 10 of the corresponding bearing element -9, maintain the bearing elements 9 at a mutual distance from each other on the periphery

rolling bearing.

  The outer bearing element 7 comprises a raceway 5 er, a core-hardened rolling steel which is hot rolled on an annular support 6 in one.

steel weakly go.

  The rolling elements 9 are provided with an annular support 6 which, on its lateral surface as well as in its central bore, carries a cylindrical raceway 5 made of roll-hardened steel. The support 6 of the rolling elements 9 is also manufactured

in a low alloy steel.

  The elements 1 and 2 of the rolling bearing shown in FIG. 1, as well as the elements? and 9 of the rolling bearing variant shown in Figure 2, comprise a support 6 of a low alloy steel having a carbon content of 0.15 to 0.40, for example the steel grade 28 Mn 6. Each support 6 carries at least one raceway 5 that can be realized in

  a hardening spring steel of 100 Cr 6 grade.

  All the bearing elements 1, 2, 7 and 9 are manufactured in accordance with the following method according to the invention: - assembly & force and / or shaping of the support 6 with the race or tracks 5 so that the support 6 and the or the raceways 5 are combined into a one-piece bearing element 1, 2, 7 and 9. The shaping is performed in the cold or hot state of the 1D raceways 5 and / or the support 6 After force-fitting and / or shaping, each bearing race 5 of the bearing element, securely fastened in one piece to the suppcrt 6, may have a thickness

wall thickness from 2 to 10 mm.

  - Heating the bearing element 1, 2, 7 and 9 to

  a quenching temperature of, for example 85 ° C.

  - Malntien of the bearing element 1, 2, 7 and 9 at the quenching temperature for austénltisatlon of both the rolling steel of the raceway or 5 of the low alloy steel support 6. Time to

  maintenance for this purpose can be about 1 hour.

  - Sudden quenching of the bearing element 1, 2, 7 and 9 in the oil, salt or water, so that the rolling steel of the race or races 5 takes a martensic structure of a Rockwell C hardness of 58 to 64 and that the corresponding support 6 takes. he too has a martensltic structure. The support 6 can have in

  pareli case a Rockwell C hardness of about 40.

  After quenching, the element of pallet 1, 2, 7 and 9 is still warmed to a normal temperature.

  temperature of 160 to 240 ° C, preferably 180 ° C, and gold.

  leave it at this temperature for a time of

  maintaining 1 to 4, preferably 2 hours.

  Finally, the grinding wheel is finished with the bearing elements and the stones are ground and polished, if necessary.

  level of the surfaces of their tracks 5.

  When the hot forming of the support C with the raceway 5 for the manufacture of the pallet 1, 2, 7 and 9 is provided, the operation is carried out advantageously by hot rolling. To ensure a particularly solid assembly of the raceways 5 and the support 6, it may be judicleux in many cases to coat a thin metal layer each raceway 5 and / or the corresponding support 6 before assembly to force or shaping. During the quenching of the rolling element, the metal of the layer diffuses at the transition point both in the rolling steel of the race (s) 5 and in the steel of the support 6. The metal layer , which may be copper, is preferably applied electrolytically so as to

  it has a thickness of 1 to 2 pm.

  For the support 6, it is possible to use a steel of the 28 Mn 6 grade which has the following analysis:

C 0.25 - G, 32

Mn 1.30 - 1.65 If <0.40

S <0.035

  Remainder of iron and impurities resulting from

the development of steel.

Claims (10)

  A method of manufacturing rolling bearing elements comprising a low-alloy steel support and at least one steel tread for a core-hardened bearing, in which the support and the at least one raceway are securely joined together one and the same bearing element by force assembly and / or shaping, after which the bearing element is heated to the quenching temperature and maintained at this temperature for the austenitization of the steel of the steel or steel; rolling, and then quenching in the oil, salt or water to obtain a martensltic structure with a Rockwell hardness C of 58 to 64 of the steel of the raceway (s), characterized by the fact that a steel with a carbon content of 0.15 to 0.40% is used for the support which is also austened when the rolling element is held at the quenching temperature and is also converted into a martensitic structure the sudden quenching of the bearing element.   2. Method according to claim 1, characterized in that the steel of the support acquires a hardness Rockwell C of about 40 during the hard quenching of the bearing element.   3. Method according to claim 1 or 2, characterized in that the bearing element is   austenitlsé at a quenching temperature of about 850 ° C.   4. Process according to any one of the claims   characterized by the fact that after quenching, the bearing elongation is heated to a temperature of 160 to 220 ° C and is left at this temperature for a hold time of 1 to 4 hours.   5. Process according to any one of the claims   preceding. characterized by the fact that the assembly of each   bearing and support in a single bearing element.   6. Process according to any one of the claims   preceding, characterized in that during the assembly of the support and the race or races in a single bearing element by force assembly and / or shaping. every rolling cylinder acquires a   wall thickness from 2 to 10 mm   7. Process according to any one of the claims   characterized by the fact that prior to their force-fit and / or shaping into a one-piece bearing element, the tread and / or the support is coated at least on their reciprocal transition surfaces a thin metal layer that diffuses into the steel of the raceway (s) and into the steel of the support during the quenching of the runways and support.   8. Process according to claim 7, characterized in that the metal layer is applied electrolytically. 9. Method according to claim 7 or 8, characterized in that the metal layer is made of copper.   10. Process according to any one of the claims   preceding, characterized in that for the support is used a steel having the following analysis (%): C 0.25 - 0.32 Mn 1.30 - 1.65 If <0.40 S <0.035   Remainder of iron and impurities resulting from the elatsratîen of steel.