GB2216066A

GB2216066A - Method of manufacturing a pad for a disk brake

Info

Publication number: GB2216066A
Application number: GB8904192A
Authority: GB
Inventors: Takeshi Tanikoshi; Masao Inoue; Katsushiro Shibata; Choichi Sugawara
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 1988-02-23
Filing date: 1989-02-23
Publication date: 1989-10-04
Anticipated expiration: 2009-02-23
Also published as: DE3905627A1; GB8904192D0; CA1323979C; GB2216066B; DE3905627C2

Description

2216066 METHOD OF MANUFACTURING A PAD FOR A DISK BRAKE The present

invention relates to a method of manufactur ing a pad for a disk brake in which a plurality of different lining portions molded by heating and pressing granules are secured to a plurality of areas of one surface of a back plate.

In the past, such a method of manufacture has been well known, for example, from Japanese Patent Application Laid-Open No. 252,925/1986. However, in the above-described prior art, a plurality of lining portions which have been molded in advance are secured to one surface of a back plate, and joining between the adjacent lining portions is not satisfactory, posing a problem in terms of strength at the boundary areas.

According to the present invention there is provided a method of manufacturing a pad for a disk brake wherein the pad has a back plate "and a lining on the back placte ;hich -liningis molded by heating and pressing qranules, the lining being-Nformed of a plurality of different lining por tions which are secured to a plurality of areas of one surface of the back plate, the method comprising charging granules for the respective lining portions into areas which are defined in a molding frame by one or-more partitioning plates so as to correspond to the said areas of the back plate, removing the partitioning plate(s) from the molding frame, subject2 ing the granules in the molding frame to a pressing treat ment in- which the granules are pressed against the back plate which is disposed so as to close an opening end of said molding frame, subjecting the granules also to a heat ing treatmentr and securing the lining portions which have been molded to said one surface of the back plate.

With the above-described method, the granules charged in the said are-as ccateinto mutual contact prior to the pressing step and then they are pressed and molded. Therefore, the granules for different lining portions. are mixed with each other at the boundary areas, and accordingly, the adjacent lining portions become firmly joined together through the molding step. In addition, molding of each lining portion and securing thereof to the back plate may be simultaneously carried out so that the manufacturing process can be simplified.

In one form of- the above-described method, it may be arranged that the plurality of areas of the one surface of the back plate comprises a first area occupying a main portion of the plate surface and a second area located at an end portion of the surface, and that one of the areas defined in the molding frame corresponding to the first area of the plate surface is charged with granules for forming a lining portion of such a property that assures a sufficient braking force at the time of pressure contact with a rotary disk of the brake and the other of the areas 3 in the molding frame corresponding to the second area on the plate surface is charged with granules of such a property that is not prone to damage the rotary disk. This permits the production of a pad for a disk brake which is excellent in obtaining a frictional force in the central portion thereof and serves to prevent a partial wear from occurring in the rotary disk. Accordingly, when the pad produced in this manner is attached at least to the inner side of the disk brake, it is possible to prevent an occurrence of abnormal vibration and/or sound while suppressing the lowering in the frictional force between the pad and the rotary disk.

Some embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which:

FIG. 1 is a longitudinal sectional side view of a 4 disk brake to which are attached pads manufactured according to the method of the present invention; FIG. 2 is a front view of the pad shown in FIG. 1; FIGS. 3(a) to 3(e) are explanatory views successively showing the steps for manufacturing the pad for a disk brake; F IG. 4 is a longitudinal sectional side view of a disk brake to which are attached modified inner and outer pads manufactured by the method of the present invention; FIG. 5 is a partially cutaway front view as viewed in 10a direction of arrow V in FIG. 4; FIG. 6 is a plan view of the entire pad, taken on line VI-VI of FIG. 4; FIG. 7 is a plan view showing an arrangement of two pads relating to a rotary disk; FIG. 8 is an entire plan view showing another modified example of an inner pad for a disk brake manufactured according to the method of the present invention; FIG. 9 is an entire plan view showing an outer pad used in the paired relation with the inner pad shown in FIG. 8; FIG. 10 is an entire plan view showing a further modified example of an inner and outer pad for a disk brake manufactured by the method of the present invention; FIG. 11 is a view taken in a direction of arrow XI in FIG. 10; and FIG. 12 is an explanatory view of the operation of a conventional disk brake.

One embodiment of the method according to the present invention will be described hereinafter with reference to the drawings. Prior to the description-of the method according to the present invention, pads for a disk brake manufactured according to the method of the present inven tion and a disk brake to which are attached the aforesaid pads will first be briefly -described. Referring to FIGS.

1 and 2, a pair of opposed rotary disks 1 and 2 are spaced apart from each other and are connected by means of a plurality of connecting portions 3. One rotary disk 2 is integrally provided with a support portion 4 which is mounted on a rotary body to be braked, for example, a wheel of a vehicle.

A caliper body 5 of a disk brake Br is arranged so as to straddle. both the rotary disks 1 and 2, and pads 6 and 6 are disposed on the caliper body 5 and more specifically on mutually opposed side surfaces of the rotary disks 1 and 2. The caliper body 5 is equipped therein with a piston (not shown) which is capable of moving toward and away from the rotary disks 1 and 2 so that during braking one pad 6 is urged against the rotary disk1 by said piston and a reaction generated thereby 6 urges the other pad 6 against the rotary disk 2.

Each pad 6 comprises two kinds of linings 8, 9 and 9 secured to one surface of a back plate 7 which is disposed on the caliper body 5. That is, in such pads 6 and 6 for a disk brake, an uneven wear is liable to occur on one side portion of each rotary disk 1, 2 in the circumferential direction thereof (the right end side or left end side in FIG. 2).

When this uneven wear occurs, a less-worn portion on the disk, that is, its other end side portion in the circumferential direction,encounters a larger drag than the one side portion during non-braking,to allow generation of a local wear on the rotary disk 1, 2, which may lead to an abnormal vibration or sound generation during braking. In view of this, on one surface of the back plate 7 there are provided an area 10a at a central portion thereof and areas 10b and 10c on opposite sides thereof. The area 10a at the central portion is secured with a lining 8 formed of a material capable of assuring a sufficient braking force when it is pressed against the rotary disk 1, 2, and the areas 10b and 10c on the opposite sides are secured with linings 9 and 9, respectively, which are formed of a material having such a property that makes the rotary disk hard to bring forth a local wear thereon when a drag occurs.

The linings 8, 9 and 9 are formed'by molding the 7 - granules in pressing and heating conditions. As the granules used, there can be mentioned a composition comprising, for example, fibers, lubr icants, polishing material, filling material and binding material, and specific examples thereof are mentioned below. Numerals in parentheses indicate the compound quantity (weight Fibers: Steel, asbestos, etc. (20 to 40%) Lubricants: Black lead, molybdenum disulfide, baryte, calcium carbonate, etc. (15 to 20%) Polishing material: Oxides and non-oxides (1 to 5%) Oxides: Al 2 O3r Sio 2' Cr 2 0 3 Fe 2 0 31 Fe 3 0 4' ZrO 2 MgO, CaO, etc. Non-oxides: SiC, BN, BC, Si 3 N 4' A1N, etc.

Filling material: BaSO 4" CaCO 3' etc.

Binding material: Phenol resin (which is often used as denatured resin to which is added melamine, nylon, epoxy, oil, cresol, etc.) or the like. (6 to 12%). In addition to the above, vulcanized or unvulcanized natural rubber or synthetic rubber, cashew grains obtained by pulverizing cashew resin (5 to 10%). These are mainly used as a material for regulating the frictional coefficient and also have a function for improving the damping character istics of pads to prevent occurrence of noises.

Moreover, the lining 8 corresponding to the central 8 area 10a is molded with a greater content of polishing material than that of the linings 9 and 9 corresponding to the areas 10b and loc on the opposite sides.

The method of manufacturing the pads 6 for the disk brake will now be described with reference to FIGS. 3(a) to 3(e). In the manufacture of the pad 6, a molding frame 11 is first prepared as shown in FIG. 3(a). This molding frame 11 has a cross-sectional shape corresponding to the entire shape of the linings 8, 9 and 9 shown in FIG. 2, and the bottom of the molding frame 11 held in an upright state is closed by a detachable bottom plate 12. The mold ing frame 11 has an interior partitioned previously by parti tioning plates 13 and 14 in order to define the areas 10a to loc to be set by the back plate 7, and respective required quantities of granules 15, 16 and 16 for molding of the corresponding linings 8, 9 and 9 are charged into the portions in the frame 11 corresponding to the areas 10a to loc.

Subsequently, as shown in FIG. 3(b), the partitioning plates 13 and 14 are removed. In this step, before or after removing the partitioning plates 13 and 14, the upper sur face of the granular layer accumulated on the bottom plate 12 is levelled by means of a brush or the like.

Thereafter, as shown in FIG. 3(c), the granular layer on the bottom plate 12 is pressed relatively lightly from 9 the top to achieve a preliminary molding as linings 81, 91 and 91. Upon termination of this preliminary molding step, the bottom plate 12 is removed from the molding frame-11.

The thus preliminarily molded linings 81, 91 and 9' are placed on a heat molding die 17 while keeping their state housed in the molding frame 11 as shown in FIG. 3(d). This molding die 17 comprises an upper die half 19 having a through-hole 18 formed therethrough which can be flush with and continuous to the inner surface of the molding frame 11 and a lower die half 20 which is detachably coupled to the upper die half 19. The back plate 7 is placed on an upper surface of the lower die half 20 so as to be flush with said upper surface and close the lower end opening of the molding frame 11, the back plate 7 having its peripheral edge held between the upper die half 19 and the lower die half 20. In this state, into the interior of the molding frame 11 is relatively powerfully pressed down a press means or the like from the top thereof whereby molding of the linings 8, 9 and 9 is completed on the back plate 7.

Next, as shown in FIG. 3 (e), the molding frame 11 is removed, and the linings 8, 9 and 9 are pressed from the top thereof while being subjected to heating, whereby the linings 8, 9 and 9 are secured to one surface of the back plate 7 at the predetermined areas 10a to 10c. Thus the pad 6 is obtained by molding. Then, the pad 6 may be removed from the heat molding die 17.

During this molding process of the linings 8, 9 and 9, the granules present at boundary portions between the areas 10a and 10b and between the areas 10a and 10c are pressed from the top in a state placed in contact with each other after the partitioning plates 13 and 14 have been removed, as shown in FIG. 3(b). Therefore, the granules of different compositions are mixed together at the positions between the areas 10a and 10b and between the areas 10a and 10c. Accordingly, the joining force obtained between the linings 8, 9 and 9 after molding becomes large, and the strength of the linings 8, 9 and 9 between the areas 10a to 10c will not be weakened.

Furthermore, molding of the linings 8, 9 and 9 and securing of these linings 8, 9 and 9 to the back plate 7 are carried out in a series of steps, and therefore the manufacturing process can be simplified.

Next, one embodiment of a disk brake to which is attached a modified form of a pad for a disk brake manufactured by the aforementioned method of the present invention will be described with reference to FIGS. 4 to 7.

Prior to the description of this embodiment of the disk brake, an outline of one conventional disk brake will be described with reference to FIG. 12 for the purpose of comparison. A conventional disk brake BrI is provided with a pair of pads 104' and 105' each having a lining 112' which is entirely formed of one and the same material and is secured to one surface of a back plate 1111. As a material for the lining 112' there is normally used a relatively hard material capable of obtaining a sufficient frictional force when the lining comes into frictional contact with a rotary disk 1011. Accordingly, when an uneven or one sided wear occurs in the lining 1121 at one end thereof in the rotational direction of the rotary disk 101' due to the caliper rigidity or the like, a less-worn portion 112'a on the lining 1121 comes into one-sided contact with the rotary disk 101' during non-braking as shown in FIG. 12 to cause the rotary disk 101' to be partly worn out. Such a partial wear of the rotary disk 101' results in abnormal vibration or sound occurrence during braking operation.

The embodiment of the disk brake shown in FIGS. 4 to 7 overcomes the problems involved in the aforementioned conventional disk brake by mounting a modified pad which is manufactured by the method according to the present invention.

The construction of this disk brake will be described hereinafter with reference to FIGS. 4 and 5. A disk brake Brl is operable to apply a braking force to a wheel of a vehicle and it comprises a bracket 102 mounted on a vehicle 12 body (not shown) so as to straddle over a rotary disk 101 mounted on the wheel, a caliper 103 supported on the bracket 102 in a manner movable in a limited range in a direction parallel with the axis of the rotary disk 101, and a pair of pads, that is, an inner pad 104 and an outer pad 105 which are respectively arranged between opposite sides of the rotary disk 101 and the caliper 103 for-frictional contact with the opposite sides of the rotary disk 101.

The bracket 102 is provided with a bracket body 102a having a pair of mounting hole.s 106 adapted to be mounted on the body-through bolts not shown and arranged on one side.of the rotary disk 101, and a pair of supporting arms 102b and 102b each being formed into an approximately U-shape and extended from the upper portion of the bracket body 102 so as to straddle over the rotary disk 101 at positions spaced from each other in the rotational direction of the rotary disk 101.

The caliper 103 comprises a caliper body 103a arranged on one side of the rotary disk 101, a pair of arms 103b and 103b extended from the upper portion of the caliper body 103 toward the other side of the rotary disk 101 at positions spaced from each other in the rotational direction of the rotary disk 101, a connecting portion 103c connect- ingboth the arms 103b and 103b on the other side of the 13 rotary disk 101, and a pair of caliper pawls 103d and 103d suspended downwardly from opposite ends of the connecting portion 103c. To the caliper body 103a are secured a pair of slidable pins 107 and 107 which are slidably fitted into the supporting arms 102b and 102b of the bracket 102 in a direction parallel with the axis of the rotary disk 101.

Thus, the caliper 103 is supported on the bracket 102 by means of the slidable pins 107 and 107 su6h that the caliper 103 may be slidably moved in the direction along the axis of the rotary disk 101.

The caliper body 103a of the caliper 103 is formed with a cylinder bore 108 extending parallel with the axis of the rotary disk 101 and having its side remote from the rotary disk 101 being closed. A piston 110 is slidably fitted into the cylinder bore 108 to define an oil pressure chamber 109 against the closed end of the latter. The piston 110 is formed into a bottomed cylindrical shape and is slidably fitted into the cylinder bore 108 with the closed end thereof facing the oil pressure chamber 109.

Referring also to FIG. 6, each of the inner pad 104 and the outer pad 105 is formed with a lining 112 which is secured to one surface of a back plate 111. The inner pad 104 is arranged between the caliper body 103a and the rotary disk 101 in such a manner that an open end of the piston 110 is placed in contact with the back of the back 14 - plate 111, whereas the outer pad 105 is arranged between the rotary disk 101 and the caliper pawls 103d and 103d such that the pair of caliper pawls 103d and 103d of the caliper 103 are -Djaced in contact with the back of the back plate 111. Shoulders llla and llla are provided on opposite ends of each back plate Ill and are respectively supported on guide steps 113 and 113 provided on the supporting arms 102b and 102b of the bracket 102.

The lining 112 comprises, unlike the one in the 10preceding embodiment of FIGS. 1 to 3, a first-lining portion 112a located at one end in the rotational direction of the rotary disk 101 and a second lining portion 112b which occupies the remaining principal portion (FIG. 6). The second lining portion 112b is formed of a material capable of obtaining a sufficient frictional force when the lining comes into frictional contact with the rotary disk 101, for example, a material having a composition as given in Table A below.

Table A

Composition Weight Fibers (a) Aramide fiber 3 - 6- (b) Steel fiber 10 Lubricant (c) Graphite (d) Molybdenum disulfide (MOS2) 5 - 10 (e) Antimony trisulfide (SbS3) Metal powder (f) Copper (Cu) (g) Zinc (Zn) 20 - 40 (h) Brass (CuZn) Polishing material (i) Silica (Si02) Q) Zirconia (Zr02) 1 - 5 (k) Alumina (A1203) Filler (1) Baryte (BaS04) (m) Calcium carbonate 20 30 (CaC03) (n) Cashew dust Binding material (0) Phenol resin 10 - 12 16 The first lining portion 112a is formed of a material which is hard to damage the rotary disk 101 as compared with the second lining portion 112b, and for example, it is formed of a material having the composition of the above Table but excluding (b) steel fiber from its fibers and the polishing material, that is, (i) silica, (j) zirconia and (k) alumina. Both the pads 104 and 105 are manufactured by the aforementioned method of the present invention, and the joining force between the first and second lining portions 112a and 112b is kept at a high level.

Referring also to FIG. 7, the lining 112 is formed to have a thickness d thereof reduced gradually from one to the other side along the rotational direction 114 of the rotary disk 101, and a difference c between the maximum thickness and the minimum thickness is set, for example, to 0.1 to 0.5 mm. The first lining portion 112a is arranged at the end where the thickness d is maximum, and the inner pad'104 and outer pad 105 are each arranged to have the first lining portion 112a positioned on the side thereof on which the possibility of causing a one-sided contact with the rotary disk 101 becomes maximum during non-braking. That is, the bracket 102 is cantilever supported on a vehicle body on the side of the inner pad 104, and the caliper 103 is cantilever-supported on the bracket 102 on the side of the inner pad 104.Therefore, 17 - during braking, a turning moment as indicated by arrow 115 in FIG. 7 acts to cause that end side (right end side) of the inner pad 104 at which frictional contact with the rotary disk 101 begins to be more strongly pressed against the rotary disk 101 and also to cause that end side (left end side) of the outer pad 105 at which.frictional contact with the rotary disk-101---terminatesto be more strongly pressed against the rotary disk 101. Because of this, the lining 112 of the inner pad 104 tends to wear unevenly at its frictional contact beginning end side with respect to the rotary disk 101, whereas the lining 112 of the outer pad 105 tends to wear unevenly at its frictional contact terminating end side with respect to the rotary disk 101.

Accordingly, during non-braking, the lining 112 of the inner pad 104 comes into one-sided contact with the rotary disk 101 at the terminating end side of frictional contact with the rotary disk 101, whereas the lining 112 of the outer pad 105 comes into one-sided contact with the rotary disk 101 at the beginning end side of frictional contact with the rotary disk 101. In the present embodiment, the inner pad 104 is arranged with the first lining portion 112a positioned on the end side thereof at which frictional contact with the rotary disk 101 terminates, whereas the outer pad 105 is arranged with the first lining portion 112a positioned on the end side thereof at which frictional contact with the rotary disk 101 begins. Next, the operation of the disk brake Brl provided with the aforementioned structure will be described. At the time of braking, pressure oil is supplied to the oil 5 pressure chamber 109 whereby the piston 110 is urged leftward in FIG. 4 so that the inner pad 104 is pressed against the rotary disk 101, and the caliper 103 itself is moved by the reaction thereof to push the outer pad 105 by the caliper pawls 103d and 103d toward the rotary disk 101.

Thus the braking force is obtained by the friction between both the linings 112, 112 and the rotary disk 101.

The thickness d of the lining 112 is made uneven in the rotational direction 114 of the rotary disk 101, and therefore, during non-braking, that portion of the lining 112 at which the thickness d is maximum comes into one-sided contact with the rotary disk 101. Moreover, since the first lining portion 112a formed of a material which is hard to damage the rotary disk 101 is arranged at the portion where said one-sided contact occurs, that is, the end where the thickness d is maximum, wear of the rotary disk 101 to be caused by such one-sided contact is suppressed, and the occurrence'of abnormal vibration or sound-can be avoided.

Furthermore, since the first lining portion 112a formed of a material which is hard to damage the rotary disk 101 is provided only on one end portion of each rotary disk 101 19 in the rotational direction 114, a sufficient frictional force can be obtained by the remaining principal portion, that is, the second lining portion 112b during braking.

Even if the first lining portion 112a formed of a material which is hard to damage the rotary disk 101 is provided on the lining 112, the frictional force during braking is not significantly lowered.

As a modified form of this embodiment of the disk brake Brl, the second lining portion 112b in the lining 112 may be formed of the material having the composition shown in the above-described Table A, and the first lining portion 112a may be formed of a material having a composi tion different from the Table composition in the content of lubricant, that is, with the amount of (c) graphite, (d) molybdenum disulfide and (e) antimony trisulfide being increased by 1.5 to 2.5 times, for example, so as to prevent the one-sided wear of the rotary disk 1.

Next, another modified example of a pad for a disk brake manufactured by the aforementioned method of the present invention will be described with reference to FIGS.

8 and 9.

FIG. 8 shows an inner pad 204 of a pair of pads, the inner pad 204 being formed by securing a lining 215 to one surface of a back plate 214. The lining 215 comprises a first lining portion 215a at a central portion in the rotational direction of the rotary disk 101, and a second and a third lining portion 215b and 215c on opposite ends in the rotational direction of the rotary disk 101. The first lining portion 215a is formed of the same material as that of the second lining portion 112b of the embodiment shown in FIGS. 4 to 7 so as to obtain a sufficient frictional force during its frictional contact -with the rotary disk 101. The second and third lining portions 215b and 215c are formed of the same material as that of the first lining portion 112a of the embodiment shown in FIGS. 4 to 7, which is hard to damage the rotary disk 101 as compared with the first lining portion 215a. In FIG. 8, portions indicated at 214a and 214b are shoulders by which the inner pad 204 is supported on the guide steps of the bracket, such as ones 113, 113 shown in FIG. 5. The inner pad 204 is i manufactured by the aforementioned method of the present invention, and the joining force between the lining portions 215a, 215b and 215c can be large.

On the other hand, as shown in FIG. 9, the outer pad 205 is formed by securing a lining 212 to one surface of a back plate 211, the lining 212 being formed of the same material as that of the first lining portion 215a, that is, a material that may obtain a sufficient frictional force at the time of frictional contact with the rotary disk 101.

In FIG. 9, portions indicated at 211a and 211a are shoulders 21 - by which the outer pad 205 is supported on the guide steps of the bracket, such as ones 113 113 shown in FIG. 5. This outer pad 205 is manufactured by a conventional manufactur ing method.

Next, the operation of this embodiment will be described. During non-braking of the disk brake, a drag is liable to occur at opposite ends of the respective linings 212 and 215 in the rotational direction of an associated rotary disk, and when an amount of wear in the rotary disk increases due to occurrence of the drag, an abnormal vibration or sound occurs. In view of this, when the opposite ends of each of the linings 212 and 215 in the rotational direction of the rotary disk are formed of a material which is hard to damage the rotary disk, the wear caused in the rotary disk by the drag is suppressed, and occurrence of an abnormal vibration or sound can be avoided. However, the outer pad 205 is pushed by a pair of spaced caliper pawls such as ones indicated at 103d in FIG. 4, and therefore, the level of surface pressure at the time of braking is nearly equalized over the entire surface of the lining 212. Because of this, when the opposite ends of the lining 212 is formed of a material which is hard to damage the rotary disk, the frictional force obtainable at these opposite ends is liable to become small at the time of braking.On the other hand, in case 22 of the inner pad 204, a piston comes into contact with the back plate 214 at a central portion of the latter in the rotational direction of the rotary disk, and therefore, the level of surface pressure at the opposite ends of the lining 215 becomes low. Owing to this, even if the opposite ends of the lining 215, that is, the second and third lining portions 215b and 215c are formed of a material which is hard to damage the rotary disk, the frictional force obtain able at the time of braking operation is not significantly 0 lowered.

Because of this, in the present modified form, the lining 212 of the outer pad 205 is formed at its whole surface of one and the same material to avoid lowering in the frictional force, and the second and third lining por tions 215b and 215c on the opposite ends of the inner pad 204 are formed of a material which is hard to damage the rotary disk to prevent to the utmost the occurrence of abnormal vibration or sound to be caused by a drag while avoiding lowering in the frictional force, thereby ensuring 0 a sufficient braking force as a whole. Moreover, since the lining 212 of the outer pad 205 is simply formed of one and the same material in its entirety, a cost reduction can be attained.

In this modified form, the first lining portion 215a ofthe inner pad 204 and the lining 212 of the outer pad 205 23 - may be formed of the material having the composition shown in the abovedescribed Table A, and the second and third lining portions 215b and 215c of the inner pad 204 may be formed of a material of the Table composition but with the amount of lubricant,that is, (c) graphite, (d) molybdenum disulfide and (e) antimony trisulfide being increased by 1.5 to 2.5 times, for example, thus making the rotary disk hard to be damaged.

Since, as has been previously mentioned, the lining 215 of the inner pad'204 comes only at one end thereof in the rotational direction of the rotary disk into contact with the disk during non-braking, it may be sufficient that only the said one end is formed of a material which is hard to damage the rotary disk.

Still another modified form of a pad for a disk brake manufactured by the aforementioned method of the present invention will be described with reference to FIGS. 10 and 11.

A pair of pads, that is, an inner pad 304 and an outer pad 305, according to this modified form, have the same construction. As shown in FIGS. 10 and 11, a lining 312 is secured to one surface of a back plate 311. This lining 312 comprises first lining portions 312a and 312a on opposite ends in the rotational direction of the rotary disk and a second lining portion 312b occupied in the remaining portion including a central portion in the said rotational direction.

24 The first lining portion 312a is formed of the same material as that of the first lining portion 112a in the embodiment of PIGS. 4 to 7 which is hard to damage a rotary disk as compared with the second lining portion 312b. The second lining portion 312b is formed of the same material as that of the second lining portion 112b in the embodiment of FIGS.

4 to 7. In the present modified example, on the surface of the second lining portion 312b is provided a polishing material layer 314 having such a thickness, for example, 0 of 0.2 to 0.5 mm that will allow the layer to be fully worn out due to its repeated frictional contact with the rotary disk several times, for example, 5 to 20 times. This polishing material layer 314 is formed of a polishing material used in the embodiment shown in FIGS. 4 to 7, for example. Portions indicated at 311a and 311a in FIG. 10 are shoulders by which the inner and outer pads 304 and 305 are supported on the guide steps of the bracket, such as ones 113, 113 shown in FIG. 5. Both the pads 304 and 305 1 are manufactured by the aforementioned method of the present 3 invention, and the joining force between the first and second lining portions 312a and 312b becomes large.

The operation of this modified form will be described hereinafter.

At an initial stage of use after the inner pad 304 and the outer pad 305 have been mounted on a-disk brake, the surface of the rotary disk is polished by the polishing material layer 314 through several times of braking opera tions. Accordingly, even if the rotary disk has a rugged ness on its surface, the surface can be smoothed and made flat. Since the polishing material layer 314 is provided on the surface of the second lining portion 312b which occupies the central portion of the lining 312, the surface pressure is concentrated thereon during the braking opera tion so that the polishing material layer 314 is worn out relatively early and then the surface of the second lining portion 312b appears. Since the second lining portion 312b is arranged outside the area which comes into one sided contact with the rotary disk during non-braking, the polishing material layer 314 will not frictionally contact with the rotary disk during non-braking.

At the time of non-braking after the rotary disk 314 has been polished, the inner pad 304 and the outer pad 305 are liable to induce a drag at one end in the rotational direction of the rotary disk as has already been described.

However, the first lining portions 312a and 312a at the opposite ends of the lining 312 along the rotational direc tion of a rotary disk are formed of a material which is hard to damage the rotary disk, and therefore, even if the first lining portions 312a and 312a come into one-sided contact with the rotary disk-during non-braking, the wear 26 of the rotary disk 101 can be suppressed. Moreover, since the surface of the rotary disk is smoothed by the polishing material layer 314 at the initial stage of use as mentioned above, it is possible to positively prevent onesided wear of the rotary disk and prevent occurrence of abnormal vibration or sound during braking.

Also in this modified form, the second lining portion 312b of the lining 312 is formed of the material having the composition shown in the abovedescribed Table A, and the first lining portion 312a is formed of a material corresponding in composition to that of Table A but having the lubricant, that is, (c) graphite, (d) molybdenum 1 disulfide and (e) antimony trisulfide increased in quantity by 1.5 to 2.5 times, for example. Thereby the rotary disk can have a property hard to be damaged.

Furthermore, since the lining 312 has a tendency to be brought at only one end thereof in the rotational direction of the rotary disk into one- sided contact with the rotary disk during non-braking, it is sufficient to provide the first lining portion 312a only at one end of the lining 312 and the second lining portion 312b at the remaining -portion including the central portion and the other end. In this manner, the lowering in the frictional force caused by the first lining portion 312a can be minimized.

27 It is to be clearly understood that there are no particular features of the foregoing specification, or of any.claims appended hereto, which are at present regarded as being essential to the performance of the present invention, and that any one or more of such features or combinations thereof may therefore be included in, -added to, omitted from or deleted from any of such claims if and when amended during the prosecution of this application or in thefiling or prosecution of any divisional application based thereon. Furthermore the manner in which any of such features of the specification or claims are described or defined may be amended, broadened or otherwise modified in any manner which falls within the knowledge of a person skilled in the relevant art, for example so as to encompass, either implicitly or explicitly, equivalents or generalisations thereof.

1

Claims

Claims: 1. A method of manufacturing a pad for a disk brake wherein the

pad has a back plate and a lining on the back plate which lining is molded by heating and pressing qranules, the lining 6-ein4-formed of a plurality of different lining por tions which are secured to a plurality of areas of one surface of the back plate, the method comprising charging granules for the respective lining portions into areas which are defined in a molding frame by one or more partitioning plates so as to correspond to the said areas of the back plate, reaoving the partitioning plate(s) from the molding frame, subject ing the granules in the molding frame to a pressing treat ment in which the granules are pressed against the back plate which is disposed so as to close an opening end of said molding frame, subjecting the granules also to a heat ing treatment, and securing the lining portions which have been molded to said one surface of the back plate.
2. The method according to claim 1, wherein said plurality of areas of the one surface of the back plate comprises a first area occupying a main portion of the plate surface and a second area located at an end portion of the surface, and wherein one of the areas defined in the molding frame corresponding to said first area of the plate surface is charged with granules for forming a lining portion of such a C 29 property that assures a sufficient braking force at the time of pressure contact with a rotary disk of the brake and the other of the areas in the mQlding frame correspond- ing to the second area on the plate surface is charged with granules of such a property that is not prone to damage the rotary disk.
3. The method according to claim 2, comprising reducing an amount of polishing material contained in the granules for the second area as compared with the granules for the 10 first area.
4. Methods of manufacturing a pad foi a disk brake, substantially as hereinbefore described with reference to the accompanying drawings.
5. A pad for a disk brake, when produced by the method of any of claims 1 to 4.

PabU 1989 atThe P&tentOlftoe,S House, 86.71 Righ HolborilIOndonWC1R4Tp. Purther copies maybe obtained from The P&tentoffLee. --c EMCes Brancl), St Cray, Orpington, Xent BR6 M. Printed by MUltipleX techniques lid, St]Kent Con. 1187