MXPA98008949A

MXPA98008949A - Method to join brake assemblies to cubes of ru

Info

Publication number: MXPA98008949A
Application number: MXPA/A/1998/008949A
Authority: MX
Inventors: Maurice Mann David; Abram Thornton George
Original assignee: Ford Global Technologies Inc
Priority date: 1997-12-29
Filing date: 1998-10-28
Publication date: 1999-09-20

Abstract

A method for mounting a brake rotor to a wheel hub. This assembly establishes a fixed and sealed bearing, but removable between them. The method comprises the steps of: (a) forming matching metal mounting surfaces on the respective rotor and hub, which extend, at least in part, in a plane normal to the axis of rotation of the hub (e.g., within a tolerance deñ25.4 microns), (b) depositing a sealant material between the mounting surfaces, which consist of a paste based on mineral oil, containing generally similar proportions, by volume, of nickel, graphite and hydrocarbon particles, suspended in the paste, these particles have an ultra-fine size in the range of 5 to 80 microns; (c) hold the surfaces together to complete the assembly, the clamping causes the deposited material to spread evenly between them, to seal the surfaces against corrosion, the paste is deposited in a limited volume, to allow the contraction of metal against metal between the micro-flanges of the surfaces, when they are clamped, the material spread evenly t olerates the micro-movements between the surfaces, during the prolonged use, without friction, to maintain the alignment of the rotor to the cube within the tolerance designates

Description

METHOD TO JOIN BRAKE SETS TO WHEEL CUBES This invention relates to the technology of mounting wheels with a braking assembly and, in particular, to techniques for eliminating the misalignment that may develop between the wheel hub and the braking element of the braking assembly, sometimes referred to as "dislodging". ", which can cause brake pedal pulsations when applied or can cause undue brake wear. Discussion of the Prior Art It has become a common practice to suppress tapered packages of roller bearings in the connection between hubs and wheel elements (ie, a hollow molded rotor plate) and to replace a metal surface for mounting the flange of the rotor. surface of the braking element to the hub flange of the inner hat. The braking element or rotor is designed to operate in a precise plane, normal to the axis of the wheel; there is little tolerance for the deviation of such plane, which must be generally no larger than 25.4 microns in the external diameter of the rotor, to avoid lateral dislocation. To ensure such alignment, the mating flange surfaces of the assembly are machined with very high accuracy and, when worn together under the engaging force of the threaded fasteners, such alignment will be achieved. The caliber of the braking that operates on the rotor depends on the rotor that remains in the plane of rotation designed in relation to the wheel axis so that the caliper brake pads operate with a predetermined movement. If not, the perception of the brake pedal will be different and the driver will detect the pulsating contact by the brake pads as the oblique wobble of the rotor between the pair of brake pads. This misalignment can easily arise from the presence of corrosion between the matching mounting surfaces. The corrosion will appear as non-uniform discontinuous particles, which can force the flanges apart, as little as 12.7 micas, to create some degree of lateral dislodgement of the rotor. It exists as a small deviation, as 0.01% of the external diameter of the rotor from its plane of rotation attempted. Such dislocation creates a cycle of contact and apparent non-contact between the rotor and a brake pad, while the wheel is turning, even without applying the brakes. The driver interprets this as braking system hardness (pedal pulsation) or steering wheel shake detection, both detections occur when braking is applied at vehicle speeds of around 48 to 112 kilometers per hour.

The obvious attempt to solve this problem is to apply a coating to the mounting surfaces of metal (ie, steel) that inhibits corrosion. Unfortunately, the introduction of materials typically obvious to the assembly results in (i) the material being removed too easily or migrating during the normal micro-displacement of the hub and rotor flanges, when loading or under centrifugal tension is applied or ( ii) the material becomes too hard and rubs during use, which again results in the uneven distribution of the coating, which becomes equivalent to the corrosion-like disturbance. In any case, there is a progressive evolution of the discontinuity between the coinciding surfaces on a microscopic scale that results in the lateral dislocation of the rotor. The friction of the coatings, which finally become hard, is due to the microscopic movement of the two surfaces coincident during use, which grinds the coating or the material can become unstable at temperatures such as 149 to 315 ° - C, becoming locally unequal. SUMMARY OF THE INVENTION It is an object of this invention to provide a method for assembling wheels with braking rotors, which seal the assembly against corrosion, without allowing friction or modification of the sealant material in use., which could lead to misalignment and alignment of the rotor, such sealing eliminates corrosion for a prolonged period and allows the removal and reassembly of the wheel without contamination of particles or corrosion, which could promote lateral dislocation when reassembled. The invention, which complies with the above object, comprises a method for mounting a brake rotor to a wheel hub, this assembly establishes a fixed, sealed but removable bearing, between them, comprising the steps of: (a) forming matching metal mounting surfaces on the respective rotor and hub, which at least in part extend in a plane normal to the rotation axis of the hub (for example, within a tolerance of ± 25.4 microns); (b) deposit a sealing material between the mounting surfaces, consisting of a paste based on mineral oil, which contains generally similar proportions, by volume, of particles of nickel, graphite and a hydrocarbon, suspended in the paste, these particles have an ultra-fine size range of 5-80 microns; (c) clamping the surfaces together to complete the assembly, this clamping causes the deposited material to spread uniformly between them, to seal the surfaces against corrosion, the paste being deposited in a limited volume, to allow metal-to-metal contact between the micro-flanges of the surfaces when they are clamped, this uniformly spread material will tolerate micro-movements between the surfaces, during prolonged use, without friction, to maintain the alignment of the rotor to the cube within the designated tolerance. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a general perspective view of a wheel assembly showing the rotor in place with the braking sizes properly installed; Figure 2 is a perspective view with separate pieces of the elements of Figure 1, taken from the inverse direction; Figure 3 is an enlarged sectional view, taken substantially along line 3-3 of Figure 1; Figure 4 is a greatly enlarged view of the portion within a circle in Figure 3; Figure 5 is an enlarged view in elevation of the rotor, illustrating a pattern for depositing the sealing material on the flange surface of the hat section of the rotor; Figure 6 is a composite view of the schematic steps of the process of this invention; and Figure 7 is an enlarged view in elevation of the rotor, illustrating yet another alternative method of depositing the sealing material on the flange surface of the hat section of the rotor. BSqRTPC? QM DBTAfrLAPJV AND THE MEJQft HO O As shown in Figures 1-2, the wheel assembly 10, which employs disc braking, comprises a wheel rod 11, a hub 12 in the rod, a rotor 13 attached in 14 the hub 12 and a brake caliper 15 (containing the disc brake pad 15a) is supported on the bracket 15, secured to the steering pin 8, which carries the rod 11; the braking pads of the rotor gauge 15, as illustrated in Figure 3. This rotor 13 is mounted to the hub 12 by coupling a flange 16 of annular, flat steel from the hub to a flange 17 of the rotor, of steel or aluminum, annular, flat, by the use of pins 18 or fastening bolts. Corrosion will be formed on the interframes 19, 20, coupled, unprotected, of the rims in the prolonged use of the vehicle, the presence of the humidity, air and braking temperature (heating) cycle and the subsequent cooling; such corrosion may originate in or migrate and creep between such gussets 19, 20, although they are held by the fastening bolts. The interfacing surfaces 19, 20 are machined to be flat and parallel to each other within about 50.8 microns and have a smooth surface finish of about 38 to 203 microns. It is the presence of corrosion on such interfacing surfaces that leads to the lateral dislodging of the rotor (a side-to-side movement or wobble of the rotor as it rotates about the shaft 22 of the rod, which can cause vibrations, pumping of the pedal * of the brake or rattle of the brake, associated with the caliper, which must be attached to the rotor). The lateral dislodgement of the rotor does not need to be greater to be problematic; for example, preferably it should not exceed 381 microns, measured in the outer diameter of the rotor, to avoid problems. Also, corrosion can effect the dislodging of the rotor for the wheel assemblies that cause the rotor to be removed by exposing the interface surfaces 19, 20. Particles of corrosion can fall out or be dislodged, so that the matching surfaces 19, 20, when reassembled, will be more twisted on a micro-scale, than before disassembly. This invention overcomes such problems related to corrosion. The interface surfaces 19, 20 are formed with micro-finishing of 76 to 152 microns and are carried in a predetermined position perpendicular to the axis 22 of the rod, so that the broken / bucket assembly rotates in a plane 23, which is not evicted from such a predetermined position at all times, the eviction being defined is a deviation of such plane in the outer diameter of the rotor greater than 20.32 microns.

To achieve such precise alignment during prolonged use, a sealing material 24 is deposited between the interface mounting surfaces 19, 20. The sealing material consists of a paste based on mineral oil, which contains generally similar proportions of particles, mainly nickel, graphite and hydrocarbon, these particles are suspended in the paste. The "base" is defined herein as meaning a paste that has 51% or more by volume of mineral oil. The nickel should preferably not be less than 15% by volume; each graphite and hydrocarbon should preferably not be less than 10% by volume. The paste may contain a small amount of lithium soap (3-5% by volume) and aluminum particles (1-3% by volume) to supply the thermal conductivity. The main particles should have a particle size range of 5-80 microns, so under the clamping pressure, the micro-movement of the interface surfaces are accommodated without extrusion or removal of the material 24 from between the surfaces; the material facilitates the sliding of these particles into the pulp without disturbing the integrity of the pulp. Other solid lubricating compounds or particles can be added to the paste, as long as the paste remains with a sufficiently fluid viscosity and the particles retain their ultra-fine size characteristics. The paste preferably has the consistency of a hard paste for the teeth. The sealing material may contain other solid lubricants as a substitute for all or a portion of the graphite or nickel, the solid lubricants are selected from the group of MoS, BN and lithium or sodium fluoride. The paste is deposited, as shown in Figures 5-6, in a precisely limited volume, to allow for some metal to metal contact at a micro-scale between interface surfaces, when fully clamped (see figure 4 schematic, showing a micro-flange contact to a micro-flange at 32). This can be achieved by extruding (preferably by an automaton) the paste into one or more annular slat rings 25, 26 on at least one of the surfaces. If two ribbon rings are used, as shown, the cross sections of the ribbon rings must be uniform to provide an average of approximately 2.5 grams per rotor (2.1-3.0 g / rotor). The mating surfaces are held together by the twisting of the bolts 27 in the threaded bolts 18, which extend through the openings 31 in the flanges 16 and 17. The pulp is spread under a coupling pressure of approximately 2268 to 2736 kilograms to be smeared across the interface surfaces and migrate into the micro-roughness of the machined surfaces, allowing the micro-crests or ridges 34 of the machined surface variations to achieve metal-to-metal contact with the particles of pasta trapped between them; the rigid and firm viscous nature of the material 24 allows micro-displacements of the surfaces without wear or friction of the sealing material. The thickness 25 of the material, as it extends or smears on the surfaces, is compressed to about 12.7 microns or less. In the embodiment of figure 5, the environmental humidity can not enter between the subject interface surface, 19, 20, through its internal or external peripheries (28, 29). The use of batten rings adjacent to such peripheries, as shown in Figure 5, when the surfaces 19, 20 are clamped together, cause the material 24 to extend somewhat and seal these peripheries against water penetration. However, since the middle region 33 of the surfaces probably does not possess the material, even after the extension due to clamping, there is some risk that the water vapor may migrate in this region or may enter through micro-fissures. around the bolt (openings 3). Corrosion of the friction can thus occur, which is a limited corrosion of stain type, but this corrosion is subjected to micro-grinding (due to the micro-displacement of the subject surfaces during the braking cycles), allowing to accumulate further corrosion under corrosion that has disintegrated by grinding.

To remove the possibility of this type of corrosion, the material 24 may alternatively be lightly tapped, brushed or printed on the interface surfaces at separate points 36 or segmented tapes, as shown in the Figure 7, to provide even greater volume and distribution control. Since the points 36 or segments 37 are applied over a larger area of the interface surfaces, the coupling pressure will extend the material 24 more rigorously around each bolt opening and through the entire middle region 33. Thus, there will be no opportunity so that corrosion by friction can be established. An even more optimal way of depositing can be to combine ribbon rings with closely spaced points printed on the screen, to eliminate all forms of corrosion. The reason why the sealing material not only eliminates or inhibits corrosion, while remaining rigid, but viscous, to tolerate micro-movements of the subject interface surfaces, is that it seals and separates water and contamination, has lubricating properties that prevent friction, provides a barrier and lasts through thermal cycles, mechanical displacement and centrifugal forces to remain sufficiently malleable and ensure metal-to-metal contact. The sealing material is not captured or rubbed at temperatures as high as 1538 ° C. Other solid compounds or lubricants can be added to the composition of the sealing material, provided that the essential characteristics of sealing and viscosity of the material at temperatures up to 815 ° C and under pressures up to 2722 kg are not affected. The paste, when recently deposited, is dark gray, while the machined steel faces are bright metallic in color before assembly. After assembly and dismantling, after a substantial use of the vehicle, the interface surfaces will have a general appearance full of spots, but very fine, due to the distribution of the gray paste in the micro-roughness of the shiny steel. No corrosion is visible to affect the appearance and thus does not appear as a contaminated. Such interface surfaces can thus be reassembled without the addition of a new sealing material and without being concerned that the alignment of the rotor to the rod will be affected. While particular embodiments of the invention have been illustrated and described, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the invention and attempts are made to cover all such modifications and equivalents within the appended claims. of the true spirit and scope of this invention.

Claims

CLAIMS 1. A method for mounting a brake rotor to a wheel hub, which has an axis of rotation, this assembly establishes a fixed bearing sealed, but still removable, among them, the method comprises the steps of: (a) forming metallic assembly surfaces coinciding in the respective rotor and hub, extending in a plane essentially normal to the axis of rotation; (b) depositing a sealing material between the mounting surfaces, consisting of a paste based on a mineral oil, which generally has similar proportions, by volume, of nickel, graphite and hydrocarbon particles, suspended in the paste, these particles have an ultra-fine size, which varies from 5 to 80 microns; (c) clamping the surfaces together to complete the assembly, this clamping causes the deposited material to be uniformly spread between them, to seal these surfaces against corrosion, while preventing lateral dislocation of the rotor, the paste is deposited in a volume limited to allow metal-to-metal contact between the surface micro-flanges, when held, the paste tolerates micro-movement between the surfaces during prolonged use, without friction, to maintain rotor alignment to the hub.
2. The method according to claim 1, wherein the lateral dislocation is limited in step (c) to not more than 12.7 microns, this paste maintains the alignment of the rotor to the bucket to maintain a dense viscosity of the pulp even at such high temperatures. high as of 15382C.
3. The method according to claim 1, wherein, in step (a), the mounting surfaces are machined to a surface finish of 76 to 152 microns.
4. The method according to claim 1, wherein the mounting surfaces are annular flat rings and the sealing material has a viscosity sufficient to be deposited by extrusion into the narrow ring annular rings, spaced concentrically from each other, in an amount by weight on the mounting surface of 2.1 to 4.0 grams.
5. The method according to claim 1, wherein, in step (b), the sealing material additionally contains one or more of a lithium soap and aluminum.
6. The method according to claim 1, wherein, in step (d), the sealing material contains (i) nickel in an amount of not less than 15% by volume, and (ii) graphite and a hydrocarbon, each in a volume not less than 10%.
7. The method according to claim 1, wherein, in step (c), the fastening is carried out with a load of 2268 to 2722 kilograms.
8. The method according to claim 1, wherein, in step (b), the sealing material is deposited in a pattern of separate points or segments, to achieve limited volume, this pattern allows metal-to-metal contact between the surfaces when fastened.
9. The method according to claim 1, wherein, in step (d), the sealing material can contain a solid lubricant as a substitute for all or a portion of the graphite or nickel, this solid lubricant is selected from the MoS group, BN and lithium or sodium fluoride.
10. The method according to claim 1, wherein the subject surfaces can be separated for disassembly of the wheel assembly and reassembly with the same clamping forces, while retaining the same alignment of the rotor to the stem.