MXPA98001781A

MXPA98001781A - Friction lining intended to equip a device exercising a dry friction, procedure for the manufacture of such friction lining, and clutch friction disc equipped with said fo

Info

Publication number: MXPA98001781A
Application number: MXPA/A/1998/001781A
Authority: MX
Inventors: Guerin Richard; Adamczak Loic; Legrand Claude; Kierbel David
Original assignee: Valeo
Priority date: 1997-03-06
Filing date: 1998-03-05
Publication date: 1999-02-24

Abstract

The present invention relates to a friction lining for a dry friction device, characterized in that said liner has a generally flat annular shape and comprises a flat annular body of friction material defining a cylindrical inner surface and a cylindrical outer surface, and which includes a plurality of substantially reinforcing annular zones arranged concentrically, wherein the reinforcement zones are made of materials of different density

Description

FRICTION LINING INTENDED TO FIT A DEVICE THAT EXERTS UNFT DRY FRICTION: PROCEDURE FOR THE MANUFACTURE OF SUCH FRICTION LINING. AND ISCO FRICTION OF CLUTCH EQUIPPED WITH SAID LINING.

The present invention aims at a friction lining, intended to equip a device that exerts a dry friction, in the form of a generally annular plate and of the type comprising a flat annular body, formed of friction material, limited by internal cylindrical surfaces and outside. The invention also relates to a method for forming said friction lining, as well as a friction disk for clutch, rotating, which performs dry friction and which comprises at least one friction lining according to the teachings of this invention. . Numerous examples of said annular friction liners are known, which are presented in the form of a flat ring and which are used to equip a clutch disk or a brake disk, which effect dry friction. Each friction lining having the shape of a flat ring is formed into the shape of a preform that is subjected to a final cooking operation in order to obtain the polymerization of some of its components, possibly followed by a subsequent cooking operation .

The annular plate preform, according to the different known techniques, for example, can be constituted by threads impregnated with a thermosetting resin, which are cut to variable lengths between 5 and 30 mm; and the preform is preliminarily formed in a mold. It can also be made up of impregnated and braided yarns, the length of the braid corresponding to the outer diameter of the preform. The preform can be constituted by impregnated and braided yarns to obtain a band of fabric whose length corresponds to the outer diameter of the preform. The preform may be formed from impregnated yarns that are wound on a mandrel, with the inside diameter of the preform; the tube thus obtained by winding, then cut into sections to form as many preforms of annular plates as sections have been cut. Finally, the preform can be formed from impregnated yarns that are wound overlapping lobes that correspond to the outer diameter of the preform. All these methods for manufacturing the preforms, which are mentioned immediately above, have the main drawback of being directed to annular friction linings, which have insufficient resistance to the phenomenon of centrifugation, mainly in hot.

The phenomenon of rupture by centrifugation is generally due to the fact that the maximum tangential restriction is made at the level of the inner cylindrical edge of the lining, in the form of a crown that exceeds the tensile breaking force of the friction material that constitutes it. The invention aims to propose a new conception of a friction lining, of the type mentioned above, whose resistance to the phenomenon of centrifugation is improved and whose retail price is reduced. For this purpose, the invention proposes a friction lining, characterized in that it comprises at least one annular reinforcing zone. According to other characteristics of the invention, taken independently or in all its technically possible combinations: the annular reinforcing zone is provided in the vicinity of the inner cylindrical surface of the lining; -comprises several annular reinforcement zones, arranged substantially concentric; -the annular reinforcement zones are arranged substantially concentric from the vicinity of the inner cylindrical surface of the liner; -comprises several annular reinforcement zones, arranged substantially concentric and distributed over the entire lining, between the interior and exterior cylindrical surfaces of the same; -the reinforcing annular zones are formed of a material of the same density; -the annular reinforcing zones are formed of materials of different densities; -the reinforcing annular zones are formed of materials of different densities, which decrease from the inner cylindrical surface of the lining; each annular reinforcing zone is a reinforcement ring, formed of a substantially annular cylindrical layer, inserted in the flat annular body; each annular reinforcing zone comprises a reinforcing material of organic, mineral and / or metallic origin; each reinforcing annular zone comprises a reinforcing material, constituted in the form of continuous threads, of discontinuous threads, of fibers, of a fabric, of a tranza or of a tape; - the friction lining is formed from a fiber mat, in which a thermosetting resin has been dusted; - said fibers have a length comprised between 40 mm and 120 mm; -fibers are selected from the group of cotton, viscose, linen, polyacrylonitrile, pre-oxided polyacrylonitrile, para-a ramide, meta-aramid fibers, mineral fibers: glass E-C-R, mineral wool, ceramics; - glass is incorporated into the mat in the form of silicon and / or of strands of vitrofibre and / or textured or volumized; - the diameters of the glass fibers are between 6 and 21 microns; -the glass fibers are subjected to an adhesion, an impregnation with phenolic resin, or an impregnation with rubber; - Powdery loads that are totally or partially constituted by the following elements or compounds are incorporated in the mat: copper, mineral wool, nitrile rubber powder, carbon black, hexamethylenetetraamine, glisonite, litarium, melamine resin, phenolic resin, sulfur , cardolite, zirconium silicate, iron sulphide, alumina, latex, powdered used clutch linings, friction linings rectifier powders, zinc oxide. The invention thus proposes a method for manufacturing a friction lining, intended to be equipped with a device that performs a dry friction, generally of flat annular shape, and of the type comprising a flat annular body, of friction; wherein a flat annular body preform is formed by winding on a mandrel, a given length of a band of a mat of a friction material; characterized in that, in the course of the winding step, at least one piece of a band of reinforcement material of sufficient length is inserted to form at least one annular reinforcing zone for the subsequent obtaining of a friction lining of in accordance with the teachings of this invention. According to other characteristics of the process, the material constituting the friction lining is formed in the following manner: a) a mixture of fibers of the same nature or of different natures, such as those defined above, is formed in a mixer; b) the mixture is carded to form a card web; c) the card veil is carmena; d) the glass is incorporated into the card veil during the carmenado; -between steps b) and c) above, powdery loads are sprinkled on the card web; - the carding is carried out by means of a card of the wool type; e) the mat is placed at a thickness between 3 mm and 10 mm, between heated plates; -the temperature is within 50 ° C and 100 ° C; -the pressure is between 1 baria and 10 barias; g) the strip is cut into strips, preferably in the direction of the length; -the width of the bands is between 8 and 25 mm; h) the bands thus cut are welded by heating sheets; -the temperature of the sheets is between 50 and 100 ° C; -The coating of the welded bands has between 3 mm and 20 m; i) the welded strip is wound on a reel, with introduction of the reinforcing material, to form a ring. In order to obtain a device coated with the friction material, the procedure according to the invention is as follows: j) a ring or, alternatively, a plurality of sectors forming a ring, is cut on the mat formed as indicated above; k) the ring, or the plurality of sectors forming a ring, is placed at the bottom of a mold; 1) a pressure cook is made in the mold. The invention also proposes a rotary clutch friction disk, which performs a dry friction, comprising at least one friction lining; characterized in that said friction liner conforms to the teachings of this invention. The rotating clutch disk, according to the invention, is characterized in that the friction lining has been obtained according to the method according to the teachings of this invention. In accordance with the invention, a friction lining is obtained which exhibits good friction characteristics, wear resistance, as well as the effects of centrifugal force. The invention advantageously allows to obtain linings of friction whose characteristics of friction, wear resistance, on the one hand, and the characteristics of mechanical resistance to the effects of the centrifugal force, can be selected and controlled separately. Other features and advantages of the invention will appear from a reading of the detailed description that follows for the understanding of which reference will be made to the accompanying drawings, in which: Figure 1A is a schematic view illustrating an annular friction lining of according to the state of the art. Figure IB is a view similar to that of figure 1A, illustrating a first example of obtaining a friction lining according to the teachings of the invention. The figure IC is a view similar to that of the figure ÍA, which illustrates a second example of obtaining a friction lining according to the teachings of the invention; and Figure 2 is a diagram illustrating a part of an installation for the implementation of a method for manufacturing a friction liner according to the teachings of this invention. In FIG. 1A, a friction lining 10 according to the state of the art has been shown as having a generally flat annular shape, which is limited by an inner cylindrical surface 12 and by an outer cylindrical surface 14.

According to a known design, the flat annular friction lining 10 or at least its preform, before the final firing operations, is formed, for example, by winding in a mandrel of adjustable diameter, a band of a material of friction 16, and then cutting sections of the material tube thus formed by winding. In this way, the friction lining is presented in the form of a succession of layers adjacent to the mat of friction material. For the constitution of the friction material and its manufacture, reference may be made to what is described above, as well as to the content of the examples of the French patent application No. 95 0544 of June 21, 1995. In accordance with The teachings of the invention, and as illustrated in FIGS. IB and IC, it has been proposed to improve the rupture strength by centrifugation of such a friction lining, at least in the vicinity of its internal cylindrical surface. , by means of hands an annular zone of reinforcement. For this purpose, and as can be seen, for example, in FIG. IB, several annular reinforcing zones 18 are provided, which are arranged concentrically and interspersed between corresponding annular zones, formed in the friction material which is the base constitutive of the flat annular body 16, according to the state of the art.

In another exemplary embodiment, illustrated in Figure IC, the entire annular friction liner 10 is the one that is reinforced; that is, that annular reinforcing zones are present, from the vicinity of the internal cylindrical surface 12, to the vicinity of the external cylindrical surface 14. The structure and composition of a reinforced liner, such as that illustrated in the figures IB and 1C, by way of example, is as follows: By way of example, the mat of fibers constituting the friction material can be formed from six weight compositions of the following fibers, expressed in parts: EXAMPLES FIBRAS A B _ PAN (poíiacri? Oni- 13.6 12.4 9.3 8.5 7.7 trilo) or pre-oxidized PAN.

Glass E 4.6 4.2 9.3 8.5 7.7 The average length of the fibers used is as follows: - PAN fibers: 42 mm; -Fiber glass: 50 mm. The fibers or mixtures of the above fibers, formed in a mixer, are introduced into the loader of a feeding device of a card of the wool type, which It comprises a feed hopper. Powdery loads are sprinkled, at the exit of the card, on the veil of card formed, by means of a sprinkling device. The pulverulent fillers have the following composition (composition by weight, with respect to the fiber parts mentioned above): PULVEEJEMPLOS RULENT LOADS. A B C D E F Rectifying powders38.1 34.6 31.7 8.2 7.5 6.7 of rectification of de-fterings.

Phenolic resin 37.4 34.7 31.1 19.6 17.8 16.0 Ca rdo li ta 4.7 4.1 3. 1 Rubber or film 16.2 14.7 13. 2 Azuf re 3.2 2.9 2.6 Barium sulfate 12.9 11.7 10.5 Magnesia 3.3 3.0 2.7 Melamine resin 18.0 16. 1.

Each annular reinforcing zone 18 is a ring of a band of glass fabric that is inserted into the rolled mat band during winding, as will be explained below. For example, the reinforcement fabric is a fabric unidirectional without chain. The diameter of the glass filaments that constitute it is substantially equal to 17 microns. The reinforcing fabric has the following composition (composition by weight, with respect to the parts by weight of fibers and of pulverulent fillers mentioned above).

EXAMPLES FABRIC A B C D Unidirectional fabric 0 8.4 16.8 0 8.8 17.7 It will be understood, from the reading of the three preceding structure and composition tables, that examples A and D are examples without reinforcement fabric, ie, examples corresponding to the state of the art illustrated in FIG. Examples B, C, E and F are examples of reinforced liners according to the teachings of this invention. The samples of linings obtained from the six preceding examples have been subjected to a cold and hot centrifugation test. The test was carried out in a centrifuge that can reach 20,000 revolutions per minute, and which is equipped with an adjustable automatic speed variator, a control tachometer and a heating system for the test chamber. The conditions of the test are as follows: For the cold centrifugation test, it is used a start from 0 to 4,500-5,000 revolutions per minute in 7 to 10 seconds; after reaching 4,500-5,000 revolutions per minute, a constant acceleration of 5,000 revolutions per minute is maintained for 25 seconds, that is, 3.3 revolutions per second2. For the hot acceleration test, we proceed to a constant acceleration of 5,000 rpm for 25 seconds, that is, 3.33 revolutions per second2. During the hot test, the thermocouple that measures the temperature is placed in the same plane as the corona being tested. The results of the test are summarized in the following table.

In this table, the maximum values of the rotation regime correspond to the beginning of the rupture phenomena by centrifugation. In the case of the first three examples, A, B and C, which belong to the same family of composition and structure, it is found that the presence of reinforcing fabric significantly increases the resistance to rupture during centrifugation, both cold as in hot. The same happens in the case of the other three examples, D, E and F, which belong to another family of structure and composition of the lining. A method for obtaining a liner according to the teachings of this invention will now be described schematically, and by reference to FIG. 2. A roller 20 of the mat strip of the friction material is shown in FIG. that the layers 16 will be formed, and a winding roller 22 of the reinforcement fabric band, with which the annular reinforcement layers 18 will be formed. The two bands 16 and 18 are arranged adjacent when they are passed over a roller intermediate hollow 24, wherein the speed and pitch length are controlled by a captor 26. The two bands are associated with each other as they pass between a pair of heating cylinders 28, to be concentrically wound on a mandrel of controllable diameter 30, to form a tube 32 which is then cut into flat annular pieces by dividing cutters 34. If the strips 16 and 18, divided from the rolls 20 and 22, are associated As a result, during the winding of a complete pipe, the production of friction linings of the type illustrated in FIG. 1C is achieved, that is to say, a lining comprising layers. annular reinforcement over its entire surface; or what is the same, radially from the inside to the outside. If it is desired to obtain a reinforced lining only in the vicinity of its inner cylindrical surface 12, it will be necessary to interrupt the reinforcement of the reinforcing fabric band 18 from the roller 22, after a certain time, and continue the winding of the single band 16, for the formation of a tube 32. According to a known method, the inner and outer diameters of the tube 32, that is to say, of the shells 10 cut subsequently, are the result of the selection of the controllable mandrel diameters. and the length of the band (s) wound on the mandrel.

Claims

NOVELTY OF THE INVENTION CLAIMS

1. - Friction lining (10), intended to equip a device that performs a dry friction, generally flat annular (10) and the type comprising a flat annular body, friction material (16), limited by cylindrical surfaces interior (12) and exterior (14), said liner characterized in that it comprises at least one annular reinforcing zone (18).

2. Lining according to claim 1, further characterized in that the annular reinforcing area (18) is arranged in the vicinity of the inner cylindrical surface (12) of the liner (10).

3. Lining according to claim 1, further characterized in that it comprises several annular reinforcement areas (18), arranged substantially concentric.

4. Lining according to claim 3, further characterized in that the reinforcing annular zones (18) are arranged substantially concentric from the vicinity of the inner cylindrical surface (12) of the liner (10).

5. Lining according to any of claims 3 or 4, further characterized in that it comprises several annular reinforcement zones (18), arranged substantially concentric, and distributed throughout the liner (10) between the interior (12) and exterior (14) cylindrical surfaces of said liner.

6. Lining according to any of claims 3 to 5, further characterized in that the reinforcing annular zones (18) are formed of a material of the same density.

7. Lining according to any of claims 3 to 5, further characterized in that the reinforcing annular zones (18) are formed of materials of different densities.

8. Lining according to claim 7, taken in combination with claim 4, further characterized in that the reinforcing annular zones (18) are formed of materials of different and decreasing densities from the vicinity of the interior cylindrical surface ( 12) of the lining.

9. Lining according to any of the preceding claims, further characterized in that each annular reinforcing zone (18) is a reinforcing ring formed of a substantially annular cylindrical layer, inserted into the flat annular body.

10. Lining according to any of the preceding claims, further characterized in that each reinforcing annular zone (18) comprises a reinforcing material of organic, mineral and / or metallic nature.

11. - Lining according to any of the preceding claims, further characterized in that each annular reinforcing zone (18) comprises a reinforcing material formed in the form of a continuous thread, a discontinuous thread, fibers, a fabric, a braided or of a ribbon.

12. Lining according to any of the preceding claims, further characterized by comprising a friction material, consisting of a mat of fibers impregnated with a resin termoendu recible.

13. Lining according to claim 12, further characterized in that said fibers have a length between 40 mm and 120 mm.

14. Process for the manufacture of a friction lining (10), intended to equip a device that performs a dry friction, generally flat annular, and of the type comprising a flat annular body, friction material, wherein a preform of the flat annular body is formed, by winding on a mandrel (30), of a determined length of a band of a mat of friction material (16), characterized in that said method, in the course of the step of At least one section of a band (18) of reinforcing material of sufficient length to constitute at least one annular reinforcing area for the subsequent obtaining of a lining of the reinforcement is inserted. friction according to any of the preceding claims. 15.- friction disc for rotating clutch, which performs a dry friction, comprising at least one friction lining (10), characterized in that said friction lining is according to any of claims 1 to 13. 16. - Rotating clutch friction disc according to the preceding claim, further characterized in that the friction lining (10) has been obtained according to the method according to claim 14.