JPS58154730A - Manufacture and device for abrasive element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a friction element for a brake or clutch for a motor vehicle, of the type in which the core plate carries on at least one side thereof a layer 7 of friction material with a braking surface. Regarding the manufacturing method of elements.

One conventional method of making a friction ring of the type described above consists of forming an annular disc of friction material and laminating or bonding it to each side of a core plate by hot pressing. With this type of processing, core plate distortion can occur as a result of imprecise pressing or as a result of heat-related effects. This results in a lack of parallelism and/or flatness of the brake surface of the disc, the correction of which involves costly machining of the friction surface. It has been proposed to cast bodies of one or more uncured friction materials containing materials that are curable under pressure, such as resins.However, it has been proposed that such uncured bodies be processed Because it is in a relatively fragile state, it exhibits for various periods of time,
The level of wear and tear increases. Furthermore, the resin has a tendency to melt during the hot pressing process before curing takes place, which makes the porous and unacceptably dense materials desirable for brake friction materials used in friction elements of the type described above. It may happen. This is especially true when using brake elements soaked in oil.

Other conventional methods of making friction elements 7 of the type described above include sintering powdered friction material into a core plate. This again involves high temperature pressing techniques, causing the core plate to become distorted.

It is an object of the present invention to provide an improved method of making a friction doublet of the type described above which reduces or avoids the problems described above.

According to the invention, the method of making the friction element 7 includes forming a layer of granular l# material containing an inert binder on the side of the mold, and forming a layer of the core plate material on the area of the plate that will form the friction lining. The core plate and the layers are cold cast into a homogeneous body of friction material, and the assembly is pressed together with sufficient pressure to form the body and core plate assembly. The method includes a step of activating the binder by applying zero heat.

Preferably, the core plate is provided with a bonding agent or adhesive 7 before being placed in bonding relationship with the granular layer, whereby the application of pressure acts to form the body and core plate assembly. Alternatively or additionally 710 * the body of rubbing material is fixed to the core plate by providing one or more suitable fixing means on the core plate.

Heating the assembly after the assembly operation is preferably done under light pressure sufficient to maintain the shape of the friction body, but not to affect the porosity of the friction body.

The particulate material is preferably provided as a wet mixture with an inert binder solvent, the solvent preferably being a resin.

In this manner, the molten resin coats the individual particles and is first heated to a temperature insufficient to cure the resin in order to dry the mixture before forming the layer on the molded alveoli. . The dried particles are not particles of individual constituent molecules;
The mixture is very compact particles, which are then crushed and sorted to obtain particles within the desired size range.

Wet mixtures are prepared by adding the resin solvent to the dry composition and/or by adding the resin solvent to the dry mixture. This dry mixture may or may not already contain a large amount of resin.

In an exemplary implementation of the method of the present invention, a second layer of particulate friction material is formed on the opposite side of the core plate from the 11-joining side.

From another aspect of the invention, a mold assembly having a casting side;
an apparatus for introducing a quantity of granular friction material into the alveoli and applying pressure between the material and a core plate positioned in contact with the material to cold cast a layer into a homogeneous body of friction material; Apparatus for carrying out the method is provided, including a pressure apparatus for forming the core plate assembly, and an apparatus for heating the casting assembly.

Preferably, the mold assembly includes a member moving between two levels, one on each side of the core plate.

The depth of each of the first and second casting cavities forming the layer of friction material is defined at this location.

After the casting process, the member is preferably movable to another location, including but not limited to the cast alveolus, to facilitate removal of the cast product from the device.

The invention will now be described by way of example only with reference to the attached FIG. 1. The friction element shown in FIG. 1 is of a known type suitable for use, for example, in multi-disc tractor brakes. The friction element consists of a sheet metal core plate with a central hole 2 for carrying by the element shaft, the central hole being provided with internal splines.

It is adapted to engage complementary external splines on the shaft. The core plate 1 carries on each side thereof a respective friction lining 4, 5, which comprises the braking surface of the disc.

The method of the present invention for manufacturing a friction element of the general type shown in FIG. 1 is carried out using the apparatus shown in FIGS. is convenient.

The casting apparatus shown in FIG. 2 is mounted on an annular support 7,
including an outer ring 6 surrounding it.

The ring is urged outwardly by elastic means, shown as spring 8, into a position where it joins support 7 and partially forms first casting cavity body 9. The alveoli are supported by an inner lower core 1 located on an annular support flange 11 carried by the support 7r4'E]
The product is formed by introducing it into the support body 7 of o. In the first step of the process, the casting side 9 is completely filled with granular friction material 12 so that the upper surface of the material is level with the upper surface of the ring 6. Cast alveoli using one or more arms or blades.

Filling is preferably done by a sweep filling technique in which the material is forced into the alveoli and flattens its upper surface. Alternatively, filling techniques that also include metering can be used.

An annular metal core plate (Figure 2) is formed by cutting or stamping from stock sheet material and is ready for use by degreasing with a suitable solvent. 1. It is then shot blasted to remove all foreign material from its major surface. to be removed from The plate is then coated with a bonding material, preferably a thermoset adhesive of the nitrile-phenol type. The adhesive is applied at least over the area to be covered by the friction lining, and the core plate is inserted into the device with a shell 12 of material filling the casting side φ. The outer pushing ring 6 is then raised a suitable amount above the core plate, and the upper core member 14 is inserted into the outer ring to form the inner radial end of the upper cast alveolus 15, and its outer radial end is It is formed by an outer υ ring 6. This alveolus is then filled with particulate material in the same manner as alveolus 9.

A suitably sized annular press tool 16 is then brought into contact with the material within the cast alveolus 15, producing approximately 2.5 tons per 10 million inches of friction material.
Start cold press operation using a pressure of 7 kg).

Generally, compression lasts for 15 to 30 seconds. The pressing tool is then removed, the outer ring 6 is lowered, and the upper core 14 is removed to allow the core plate and pressed lining material assembly to be lifted out of the apparatus.

The next step is to harden the resin so that it is fully functional as a binder. The curing process is accomplished by applying π heat to the assembly, which is preferably accomplished by placing the assembly between a pair of metal plates heated to a temperature of about 250°C. s, i, which is sufficient to prevent disassembly of an assembly until curing has taken place.
It can last for 5 minutes. Raise the temperature rapidly and heat the resin.

It is important that the resin be allowed to flow and be distributed throughout the material before curing occurs, as this will maximize the binding effect of the resin. Heating may be carried out entirely between the grates, or the friction element may be heated after an initial short heating period and passed through a plate tunnel oven to complete heating. Alternatively, heating may be by other means such as induction heating. Heating the assembly cures the adhesive and bonds the lining material to the core plate.

After cooling, the lining material needs to be worked to exact dimensions, into which the oil grooves may also be canted, or it may be cast into the lining by suitable shaping of a mold.

A typical composition of a friction lining material is a phenolic resin binder and graphite in a volume percentage of approximately 40:
The ratio is 60. The composition also includes fine grain minerals such as alumina and silica.

It is advantageous to include metal particles such as copper and zinc, organic particles such as rubber and friction dust, and fibers of materials such as cotton, carbon, and steel.

With formulations of this type, it is difficult to achieve satisfactory casting filling, especially when fine particles of 10 microns and smaller are involved, which is often the case with mineral fibres, The method preferably uses about 200
It includes a formulation process that makes it suitable for grading into a narrow particle range between 4DO and 4DO microns.

The formulation is processed by forming a wet mixture of the ingredients, including a solution of resin binder, which coats the particles and allows them to harden prior to use in casting. Suitable solvents for the resins are metasol, ethanol and acetone. When removing the solvent and drying the mixture, crush and classify the resulting dry powder.

Particles within the ideal particle size range described above are produced. The processing method is described in more detail in our pending patent application entitled "Method of Making Granular Composition 2."

The method of the present invention uses cold casting technology and separately heats the two solid bodies after casting, so compared to the conventional hot pressing technology, the pressing process time is relatively short, and the tool is kept at atmospheric temperature. It will be appreciated that this provides a convenient and effective method of creating friction elements that facilitate the establishment of dimensional tolerances on the various parts of the tool. Cold pressing of the lining composition provides good porosity of the cast lining material, which is enhanced by the wet mixing and sorting techniques described above.

Eliminate large fluctuations in particle size of ingredients.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is an exploded perspective view of an embodiment of a friction element manufactured by the method of the present invention, and FIGS. 2 to 5 are embodiment 7 of an apparatus for carrying out the method of the present invention. FIG. 3 is a schematic diagram shown in various states of use.

Claims (1)

Claims: 1. Forming a layer of granular friction material containing an inert binder in a cast alveolus, and placing a core plate in contact with the layer over the area of the plate where the friction lining is to be formed. ,
Cold casting the core plate and layers into a homogeneous body of friction material, applying sufficient pressure to form the body and core plate assembly, and heating the assembly to release the binder. A method for manufacturing a friction element Y including an activation step. 2. In the method according to claim 1. Before placing to bond the granular layer to the core plate,
A method comprising a bonding agent or adhesive 7 whereby application of said pressure acts to form the body and core plate assembly. 6. In the method according to claim 2. The method further comprises providing the core plate with one or more suitable securing means to further secure the body of friction material to the core plate. 4. In the method according to claim 1. A method of fixing the body to the core plate by providing one or more suitable fixing means on the core plate. 5. Any one of claims 1 to 4
In the method described in Section #1, heating of the assembly after the casting operation is carried out under light pressure sufficient to maintain the shape of the rubbing body, but not sufficient to appreciably affect the porosity of the rubbing body. The method I used to do it. 6. Any one of claims 1 to 5
A method according to paragraph 1, in which the particulate material is prepared as a wet mixture containing a solvent for the inert binder. In the method according to claim 6. How the binder is resin. 8. In the method according to claim 7. A method in which the mixture is heated to a temperature insufficient to cure the resin to dry the mixture before the layer is formed on the cast alveoli. 9. The method according to any one of claims 6 to 8, wherein the wet mixture contains a resin solvent in addition to the dry composition and/or the resin bath medium already contains a resin. 10. In the method according to any one of claims 1 to 9, the second layer Y of granular friction material
A method of forming the surface opposite to the surface to be bonded to the first layer of the near 7 plate. 11. The method according to any one of claims 1 to 10, wherein the formation of the layer in the alveoli is performed by a sweep filling technique. 12. A mold assembly having a casting alveolus 7, a means for introducing a granular abrasive material into the alveolus, and a pressure drop between the material and a core plate disposed in contact with the material to form the material. m'
v. An apparatus for producing friction elements comprising pressure means for cold casting into a body of homogeneous friction material and forming an assembly of the body and core plate, and means for heating the casting assembly. 13. In the apparatus according to claim 12. Contains members moving between two levels, with a first
and a second cast alveolus deep, one on each side of the core plate, 1 mY of friction material. 14. In the apparatus according to claim 13. A device in which the member is movable after the casting process to another position where it no longer forms a cast alveolus, thereby facilitating removal of the cast product from the device. 15. In the apparatus according to claim 14. A device in which the member is urged away from the other position by force applying means.