GB2195944A

GB2195944A - Process for manufacturing a moulded friction component member, in which grinding is not a required operation

Info

Publication number: GB2195944A
Application number: GB08720093A
Authority: GB
Inventors: Harunobu Kani
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 1986-09-11
Filing date: 1987-08-26
Publication date: 1988-04-20
Also published as: GB8720093D0; JPS6369833A; DE3730430A1

Description

GB2195944A 1

SPECIFICATION

Process for manufacturing a molded friction component member, in which grinding is not a required operation 5 BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a method for manufacturing a molded friction component member in which a grinding operation is not needed.

10 Discussion of the Background

Conventionally compositions used to manufacture a friction component member have been dry mixed, heat molded, heat treated and ground. These compositions contained the following materials: (1) a matrix fiber, such as an organic fiber and an inorganic fiber, (2) organic material such as phenol resin binders, rubber and the like, and (3) an inorganic filler such as barium 15 sulfate, calcium carbonate and the like.

It has heretofore been necessary to subject such compositions to a grinding operation, after a heat treatment, to obtain the friction component member. This caused the following problems with friction component member obtained.

1. A molded body having a thickness of 5.Omm, as shown in Figure 2, is required to obtain a 20.

friction component member product having a 3.5 mm thickness. Hence, approximately 30% of the molded body is discarded as waste.

2. Heat treatment for a relatively long period of time is required to provide for sufficient heat treatment of the interior of the molded body. However, heat treatment for long periods does not result in enough oxidation of the resin inside the molded body. This causes an anti-fading 25 property problem to arise.

Further disadvantages arise if the friction component member is manufactured without a grinding operation. Although the friction component members thus manufactured do not show fading, their coefficient of friction (a) is generally small. And the coefficient of friction (u) changes greatly as the wearing increases with service time. Accordingly, friction component members 30 have so far not been manufacturable without grinding.

The aforesaid drawbacks with the conventional method is caused by the following reason.

Referring to Figure 2 which is a schematic illustration of a molded body, the layer adjacent to the surface of the molded body is rich in resin components because the resin components tend to gather in portions in contact with a die after heat molding. Accordingly an oxidation propagated layer 1 and a resin-rich layer 2 are formed because the oxidation propagates in the outermost surface layer due to the heat treatment.

Fading hardly occur in the oxidation propagated layer 1 because the organic components has been thermally decomposed and decreased in the oxidation propagated layer 1, but a large amount of wearing occurs in the oxidation propagated layer 1 because the strength of the 40 oxidation propagated layer 1 is low. Further, when the oxidation propagated layer 1 has become worn and the resin-rich layer 2 is exposed, fading is likely to occur because the resin-rich layer 2 is rich in resin components.

Thus, the coefficient of friction for the oxidation propagated layer 1 is different from the coefficient of friction for the resin-rich layer 2. This causes the problem that a major change in 45 the coefficient of friction (a) of the article occurs as the service time increases.

There is therefore a strongly felt need for a new method for making a molded friction component member not suffering from the disadvantages outlined above.

SUMMARY OF THE INVENTION 50

Accordingly, it is an object of this invention to solve the problems mentioned above.

It is a further object of the present invention to provide a process for manufacturing a molded friction component member, which method does not require a grinding operation.

It is a further object of this invention to provide a novel molded friction component member manufactured in accordance with the present process. 55 The inventors have now surprisingly discovered such a process which satisfies all of these objects and other objects which will become apparent from the description of the invention given hereinbelow. The present method for manufacturing a molded friction component member without requiring a grinding operation features the following sequential processes steps:

(1) preparing a composition of a friction component member comprising (1a) a matrix fiber 60 having a fiber diameter of 50 micrometers (um) or less, (1b) an organic material, which can be a resin binder, a rubber or the like, and an (1c) inorganic filler having a grain diameter of 50 micrometers (um) or less; wherein the composition ratio of the organic material flowing during molding is from 20 to 30% by volume based on 100% by volume of the total friction compo nent member obtained; 65 2 GB2195944A 2 (2) molding the composition into a molded body using a die, wherein a pressure of 200 to 400 kg CM-2 and heat is applied to the composition; and (3) subjecting the molded body to a heat treatment process.

BRIEF DESCRIPTION OF THE FIGURES 5

A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description considered in connection with the accompanying figures, wherein:

Figure 1 provides a cross sectional view of a clutch friction component member of a preferred embodiment according to the present invention. 10 Figure 2 provides a cross sectional view of a conventional type clutch friction component member before grinding.

Figure 3 is a graph comparing the flatness of a clutch friction component member of a preferred embodiment as a test example according to the present invention with that of a comparative example. 15 Figure 4 is a graph comparing the oil impregnated porosity of the clutch friction component member of a preferred embodiment according to the present invention with that of the compara tive example.

Figure 5 is a graph comparing the coefficient of friction of the clutch friction component member of the preferred embodiment according to the present invention with that of the 20 comparative example.

Figure 6 is a graph comparing the abrasion amount of the clutch friction component member of a preferred embodiment according to the present invention with that of the comparative example.

25 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the composition of the friction component member of the present invention, a matrix fiber having a fiber diameter of 50 micrometers or less and an inorganic filler having a grain diameter of 50 micrometers or less are used. The mixing ratio of the organic material, which can be a resin binder, rubber and the like, is from 20 to 30% by volume based on 100% by volume of 30 the total friction component member obtained.

The diameters of the materials used are reduced, and the mixing ratio of the organic material used is also reduced to improve the dispersion of the materials and make the molded body porous. Thus, oxygen intrudes into the interior of the molded body, and the structure of the surface of the friction component as well the interior of the friction component member become 35 homogeneous after the heat treatment.

The matrix fiber used includes not only inorganic fibers but also organic fibers. The inorganic fibers include, one or more than two of glass fiber, ceramic fibers, silica fiber, alumina fiber, rock wool, and metallic fiber. The inorganic fiber which may be used are those used in the conven tional type friction component member. Rock wool means amorphous artificial inorganic fiber 40 called asbestos which is made into a fine fiber state after melting several ores with a high heat and applying a centrifugal force or a compressed air to the melted ores.

Of the organic fibers which can be used, heat resistant fiber are preferred. These include, for instance, one or more than two of aromatic polyamide fiber, polyimide fiber, polyamide imide fiber, phenol fiber and carbon fiber. The mixing ratio of the matrix fiber is determined according 45 to the desired type of the friction component member.

The organic material means a resin binder, rubber and the like which flows during the molding.

The resin binder includes a phenol resin binder or a melamine resin binder, although the phenol resin binder is generally used.

The phenol resin binder means a binder mainly consisting of a resin obtained by the condensa- 50 tion of one or more of phenols, such as phenol and cresol, and formaldehyde or formaldehyde forming compound. Phenol resin modified with cashew nut oil, polyvinyl butyral, vegetable oil, melamine or epoxy compounds may be used. Non-modified phenol resins are preferred because they mitigate fading problems.

The rubber which can be used includes styrene-butadiene rubber (SBR) or nitrile-butadiene 55 rubber (NBR).

The composition of the present invention contains an inorganic filler and an optional organic filler. For the filler, the following may be used: a friction conditioner such as graphite, molyb denum disulfide, lead sulfide, antimony trisulfide or the like; an organic dust such as cashew dust, metal powder of copper, brass or the like, and an inorganic filler such as barium sulfate, 60 magnesium oxide, zirconium oxide, cryolite or the like.

In the molding process, a pressure of 200 to 400 kg cm-2 is applied to the molded body. If a pressure less than 200 kg cm-2 is applied, the friction component member obtained will not have sufficient strength. If a pressure more than 400 kg cm-2 is applied, the friction component member obtained will not have ideal porosity. 65 3 GB2195944A 3 In the heat treatment operation, a heat treatment at 200 to 280"C for 4 to 8 hours is generally employed.

The present method for manufacturing a molded friction component member without grinding features the following sequential step:

A first preparation operation in which a composition of the friction component member is 5 prepared. This composition is prepared to contain:

(i) a matrix fiber having a fiber diameter of 50 micrometer (um) or less, (ii) an organic material such as a resin-type binder, rubber and the like, and (iii) an inorganic filler having a grain diameter of 50 micrometer or less. The composition ratio is adjusted so that the organic material flowing during molding is from 20 to 30% by volume based on 100% by volume of the 10 total friction component member obtained.

The next step is a molding operation in which a molded body is obtained by molding the composition in a die. In this step a pressure of 200 to 400 kg CM-2 is used and heat is applied to the composition of the friction component member.

In the final operation a heat treatment operation is used to heat the molded body obtained. 15 As a result of the present process, and in particular the first two steps, the molded body becomes porous. Therefore a sufficient amount of oxygen is contained in the body through the manufacturing method according to the present invention even when a greater molding pressure is applied because materials of small fiber diameters and grain diameters with better dispersion properties are used, and because the mixing amount of the organic material is small in the 20 composition. Accordingly, when the molded body is heat-treated, the difference of the oxidation degree between the surface and inside of the resulted friction component member is extremely small. I Further, the friction component member with improved flatness can be manufactured by the manufacturing method according to the present invention because materials having a uniform and 25 small fiber diameters and grain diameters are used and the molding pressure is increased substantially. Friction component members having a quicker wringing property as well as a stronger bonding force between particles can also be manufactured by the manufacturing method according to the present invention.

Thus, the grinding process can be eliminated by employing the manufacturing method accord- 30 ing to the present invention because the composition of the friction component member and the conditions of the processes have been largely improved. Further, the friction component member with an improved anti-abrasion property a ' nd anti-fading property can also be manufactured by the manufacturing method according to the present invention.

Other features of the invention will become apparent in the course of the following descrip- 35 tions of exemplary embodiments which are given for illustration of the invention and are not intended to be limiting thereof.

A friction component member as the test example shown in Figure 1 according to the embodiment of the present invention was manufactured with the components and ratios given in the TABLE below. The units used in the TABLE are weight%. 40 The glass fiber used in. the example had a length of approximately 1.5 mm and a diameter of approximately 10 micrometer (,um). For the organic fibers, Kevlar (trademark) produced by E.I. du Pont de Nemours & Company and which is an aromatic polyamide fiber, was used in a pulped state. For phenol resin, non-modified phenol resin was used. For the inorganic filler, barium sulfate (BaS04) was used. A pressure condition of 200 to 400 kg CM-2 molding pressure 45 measured as surface pressure and a heat treatment condition of 250C for 4 hours were employed to manufacture the test example.

The components were mixed in the ratio given in the TABLE below in a Wmixer for 10 minutes to obtain a composition of a molded f riction component member for the clutch disk.

The obtained mixture was filled in a die and subjected to a preliminary molding at room 50 temperature while applying a pressure of 300 kg CM-2 for 1 minute. Then, the preliminary molded body was subjected to a hot press treatment under a temperature of approximately 160C and a pressure of 200 to 400 kg CM-2 for approximately 10 minutes. The molded body was taken out of the die and heat-treated at 250"C for 4 hours.

4 GB2195944A 4 TABLE

Test Example 5 Composition (Present Invention) Comparative Example 10 Glass Fiber 25 25 15 Organic Fiber 20 0 Phenol Resin 18 20 - 20 Rubber 0 20 Organic Dust 0 16 Inorganic Filler 37 19 25 30 The components and the ratio of a comparative example are also given in the above TABLE.

The glass fiber used in the comparative example had a length of 1.5 mm approximately and a diameter of 10 micrometer approximately. Rubber (Styrene-butadie.ne rubber, SBR) and organic dust (cashew dust) were used in the comparative example. The pressurizing condition used was 35 to 150 kg CM-2. - Other than the conditions described above, the comparative example was manufactured under the same conditions for manufacturing the test example of the embodiment according to the present invention.

The following performance of the test example and the comparative example were evaluated: 40 Namely, flatness, oil impregnated porosity ratio, coefficient of friction and abrasion amount are measured.

The flatness in dimensional accuracy was measured by using a roughness gauge. The physical properties of the component member of the present invention and comparative examples were evaluated by measuring oil impregnated porosity ratio. The coefficients of friction and the 45 wearing amounts of the test example and the comparative example were measured under the following conditions by using a clutch dynamometer:

clutch size: 236 mm dia. x 150 mm dia. x 3.5 mm dia.

clutch cover load.: 400 kg temperature: 300"C 50 (about 50 times of clutchings were needed for rising a room temperature to 300'C inertia: 0.4 kgMS2 revolution: 2500 rpm number of clutching: 200 times The results of these evaluations are shown in Figure 3 to Figure 6. As can be seen from 55 Figure 3, the surface flatness, difference between the heights of the highest and lowest surfaces, of the test example according to the present invention is substantially smaller than that of the comparative example. Thus, it is not necessary to grind the test example.

As can be seen from Figure 4, the oil impregnated porosity ratio of the test example has been improved to be approximately double the oil impregnated porosity ratio of the comparative 60 example. It is because the pressure applied to the component member during the manufacturing process of the test example is three times greater than that of the comparative example.

Accordingly, under the same amount of the pressure, the porosity of the component member of the test example would become double that of the comparative example, and therefore the oxidation is fully performed during the heat treatment. As a result, the anti-fading property of the 65 GB2195944A 5 test example according to the oxidation has been propagated.

As can be seen from Figure 5, the coefficient of friction (u) of the test example according to the present invention is large even at the beginning of its service life and no fading occurs.

As can be seen from Figure 6, the wearing amount of the test example according to the present invention is substantially smaller than that of the comparative example, and has a 5 superior anti-wearing property. This results from the increased bonding force with less amount of resin due to the smaller material particles and the greatly increased molding pressure.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein. 10

Claims

1. A process for manufacturing a molded friction component member, comprising the follow- ing sequence of steps:

preparing a composition -for making said friction component member by combining a matrix 15 fiber having a fiber diameter of 50 micrometers or less, an organic material, and an inorganic filler having a grain diameter of 50 micrometers or less, wherein the composition ratio of the organic material flowing during a molding operation is from 20 to 30% by volume based on 100% by volume of the total friction component members contained in the composition.

molding said composition in a die to obtain a molded body, wherein a pressure of from 200 20 to 400 kg CM-2 and heat are applied to said composition; and subjecting the molded body to a heat treatment operation.

2. The process of Claim 1, wherein the organic material is a resin binder or a rubber.

3. The process of Claim 1, wherein- said matrix fiber comprises a glass fiber and at least one member selected from the group consisting of aromatic polyamide fibers, polyimide fibers and 25 polyamide imide fibers.

4. The process of Claim 1, wherein the said matrix fiber is an inorganic fiber comprising a glass fiber, a ceramic fiber, a silica fiber, an alumina fiber, a rock wool fiber, or a metallic fiber.

5. The process of Claim 1, wherein said matrix fiber is a heat-resistant organic fiber, compris- ing an aromatic polyamide fiber, a polyimide fiber, a polyamide fiber, a polyamide imide fiber, a 30 phenol fiber, or a carbon fiber.

6. The process of Claim 2, wherein said resin binder is a phenol resin binder or a melamine resin binder.

7. The process of Claim 6, wherein said phenol resin comprises a resin obtained by the condensation of either phenol or cresol and formaldehyde or a forma Idehyde-forming compound. 35

8. The process of Claim 2, wherein said resin binder is a phenol resin binder modified with cashew nut oil, polyvinyl butyral, vegetable oil, melamine or an epoxy compound.

9. The process of Claim 2, wherein said rubber is a styrene-butadiene rubber or a nitrile- butadine rubber.

10. The process of Claim 1, wherein said inorganic filler comprises molybdenum disulfide, lead 40 sulfide, antimony trisuffide, a copper metal powder, a brass metal powder, barium sulfate, magnesium oxide, zirconium oxide or cryolite.

11. The process of Claim 1, wherein said molded body is subjected to a heat-treatment at a temperature of from 200'C to 2800C for 4 to 8 hours.

12. A molded friction component member, obtainable by a process comprising: 45 preparing a composition for making said friction component member by combining a matrix fiber having a fiber diameter of 50 micrometers or less, an organic material, and an inorganic filler having a grain diameter of 50 micrometers or less, wherein the composition ratio of the organic material flowing during a molding operation is from 20 to 30% by volume based on 100% by volume of the total friction component members contained in the composition, 50 molding said composition in a die to obtain a molded body, wherein a pressure of from 200 to 400 kg CM-2 and heat are applied to said composition; and subjecting the molded body to a heat treatment operation.

13. The molded friction component member of Claim 12, wherein said organic material is the resin binder or a rubber. 55

14. The molded friction component member of Claim 12, wherein said matrix fiber comprises a glass fiber in at least one member selected from the group consisting of aromatic polyamide fibers, polyimide fibers, and polyamide imide fibers.

15. The molded f riction component member of Claim 12, wherein said matrix fiber is an inorganic fiber comprising a glass fiber, a ceramic fiber, a silica fiber, an alumina fiber, a rock 60 wool fiber, or a metallic fiber.

16. The molded friction component member of Claims 12, wherein said matrix fiber is a heat resistant organic fiber, comprising an aromatic polyamide, fiber a polyimide fiber, a polyamide imide fiber, a phenol fiber, or a carbon fiber.

17. The molded friction component member of Claim 13, wherein said resin binder is a phenol 65 6 GB2195944A 6 resin binder or a melamine resin binder.

18. The molded friction component member of Claim 17, wherein said phenol resin binder is a resin obtained by the condensation of either phenol or cresol with formaldehyde or a formal dehyde-forming compound.

19. The molded f riction component member of Claim 17, wherein said phenol resin binder is 5 a phenol resin modified with cashew nut oil, polyvinyl butyral, vegetable oil, melamine or an epoxy compound.

20. The molded friction component member of Claim 13, wherein said rubber is styrene- butadiene rubber or nitrile-butadiene rubber.

21. A molded friction element, substantially as described in any of the foregoing Test 10 Examples (but not comparative Examples).

Published 1988 at The Patent Office, State House, 66/71 High Holborn, London WC1 R 4TP. Further copies may be obtained from The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Burgess & Son (Abingdon) Ltd. Con. 1/87.