JP2000205312A - Brake disc and manufacture there of - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conform the sliding direction of a pad to the groove direction due to machining streak by forming the machining streak into a concentric circle centering around a disk rotary axis, in a brake disk having machining streak on the sliding face with which a brake pad pressure contacts and made of aluminum alloy. SOLUTION: In the sliding face 20 of a brake disk 3, surface finishing streak is formed into a concentric circle centering around a disk rotary axis C, and a concentric groove 28 is formed following to the streak. At this time, the grooves 28 are formed into concentric circles at small intervals of under 1 mm or in the order of several μm. By forming the grooves 28 into such concentric circles, a brake pad does not traverse the recessed and projecting section, consequently, the brake pad does not hit the projecting part of a plating surface not to apply intermittent impulsive force, and hence the plating is prevented from peeling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake disk for a disk brake device for vehicles such as motorcycles and automobiles, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In a disk brake device, a brake disk is sandwiched between calipers, and a brake pad provided on the caliper is pressed from both sides of the brake disk with a hydraulic piston or the like, and the pad is slid while being pressed against the disk surface to thereby generate friction. The disc is braked by force.

[0003] Such a brake disk is usually made of an iron-based material having excellent wear resistance such as stainless steel. To reduce the weight of the brake disc and improve heat conductivity, the brake disc body is made of a lightweight aluminum alloy, and cast iron is applied to the sliding surface with the brake pad to increase the wear resistance of this aluminum alloy. Brake disks joined by friction welding or Alfin joining have been proposed (JP-A-5-10667, JP-A-5-26268).

On the other hand, if the pad sliding surface of the brake disk has undulation or warpage, the braking force will be uneven, and it will not be possible to brake with a stable frictional force, and it will also cause vibration and abnormal noise during braking. . For this reason, a high flatness is required for the friction surface (pad sliding surface) of the brake disk. In order to obtain such a high flatness of the brake disk, surface finishing is performed by grinding or polishing using abrasive grains.

FIGS. 15A and 15B show a conventional method of finishing the surface of a brake disk by grinding. (A), a brake disk 60 which is a work is eccentrically mounted on a rotary table 51 which rotates as indicated by an arrow a, and is rotated as indicated by an arrow b and moves as indicated by an arrow c. 52 is a configuration for performing surface finishing.

FIG. 1B shows a configuration in which a brake disk 60 is placed on a reciprocating table 53 which reciprocates as shown by an arrow d, and surface finishing is performed by a rotating grindstone 54 which rotates as shown by an arrow e.

When finishing is performed by such surface grinding, processing streaks always remain on the surface. In the above-described conventional surface finishing, the processing streak is formed on the surface of the brake disk in a spiral, radial, combination thereof, or other irregular trajectory in a direction different from the disk rotation direction.

[0008]

However, in the above-mentioned brake disc made of an aluminum alloy,
Aluminum alloys and iron-based materials such as cast iron have significantly different coefficients of thermal expansion. Aluminum alloys have a large coefficient of thermal expansion,
Iron-based materials such as cast iron are small. For this reason, in a brake disc in which cast iron is joined to the above-mentioned aluminum alloy, the cast iron cannot follow the thermal expansion of the aluminum alloy due to the temperature rise during use of the brake, and a large thermal stress acts to cause bending or bending of the disc. This causes the aluminum alloy and cast iron to peel off. For this reason, it has been difficult to commercialize a brake disk made of an aluminum alloy with the configuration proposed conventionally.

In view of this, the present invention makes it possible to commercialize a brake disk made of an aluminum alloy by applying high-hardness plating to the surface of the aluminum alloy disk in a state in which it is difficult to peel off, instead of joining cast iron. It is assumed that.

However, in this case, as described above, the disk surface is ground and finished in order to give a high flatness to the sliding surface, and thereafter plating is performed.
For this reason, a large number of grooves are formed on the plated surface according to the processing streaks of the grinding finish marks, the cross sections of which are uneven. Conventionally, since the groove of the processing streak is different from the disk rotation direction, the brake pad slides on the disk surface through the concave and convex cross section while obliquely crossing the groove. In this case, there is no problem even if the pad traverses the groove in the case of a single brake disk made of only conventional stainless steel or the like. However, in the configuration in which the aluminum alloy is plated, when the pad passes across the uneven cross section as described above, the hard particles included in the pad may hit the convex portion and the plating may be peeled off.

The present invention takes this point into consideration,
The plating on the sliding surface due to the processing marks on the pad sliding surface is reliably prevented from peeling off, and a lightweight aluminum alloy is used as a component of the brake disc, and the surface is plated with high hardness. The object is to provide a brake disk which is lightweight and has excellent wear resistance by being applied.

[0012]

According to the present invention, there is provided a brake disc made of an aluminum alloy having a processing streak on a sliding surface against which a brake pad is pressed, wherein the sliding surface is made of aluminum. The present invention provides a brake disk, wherein a metal plating having a hardness higher than that of the alloy is applied, and the processing streak is formed concentrically about a disk rotation axis.

According to this configuration, since the processing marks on the pad sliding surface are formed concentrically about the disk rotation axis, the pad sliding direction and the groove direction by the processing marks match. The pad slides along the groove and does not cross the uneven cross section of the groove. Therefore, peeling of the plating formed on the aluminum alloy is prevented. This makes it possible to obtain a brake disc having sufficient wear resistance using a lightweight aluminum alloy having good heat conductivity.

In a preferred configuration example, a mesh-like crack is formed in the metal plating.

[0015] According to this configuration, since mesh-like cracks are formed in the metal plating, when a difference in thermal expansion due to frictional frictional heat occurs due to a difference in the coefficient of thermal expansion between the metal plating and the aluminum alloy, the crack is generated. The difference in the amount of elongation is absorbed by the expansion of the cracks, thereby preventing the thermal stress from acting between the metal plating and the aluminum alloy, and preventing the metal plating from peeling off.

Further, according to the present invention, as a method of manufacturing the brake disk of the present invention, one surface of the disk is supported on a support surface and the other surface is ground, and then the ground surface is ground. A method of manufacturing a brake disk, characterized in that the opposite surface is ground by being supported on a support surface, and then the metal plating is performed.

According to this structure, the surface is finished by grinding each side of the disk to form the above-mentioned concentric processing streak, and thereafter metal plating is performed. In this case, the disk is supported on the support surface and one surface is surface-finished, and then the disk is turned over and supported on the same support surface and the other surface is surface-finished. Finished.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a disc brake device equipped with a brake disc according to the present invention, FIG. 2 is a cross-sectional view of the brake caliper, FIG. 3 is an enlarged cross-sectional view of a surface portion of the brake disc, and FIG. FIG. 5 is a plan view of the entire surface of the brake disk.

A disc brake device 1 shown in FIG. 1 is for a front wheel of a motorcycle, and includes a brake disc 3 fixed to a front wheel hub 2 and a brake caliper 5 fixed to a front fork 4. In FIG. 1, reference numeral 6 indicates a front wheel, reference numeral 7 indicates a spoke, and reference numeral 8 indicates a rim.

The brake disc 3 has a ring-shaped disc body 11 made of an aluminum alloy, and friction surfaces on both sides of the brake disc body 11 where the brake pads 12 of the brake caliper 5 are pressed and slidably contacted. Sliding surface (Brake disc body 1
Plating layer 13 formed on both front and back sides of outer peripheral portion of 1)
(See FIG. 3), and the brake disc body 1
1 is attached to the hub 2 with a bolt 14
(Fig. 1).

The plating layer 13 is made of a metal having high wear resistance, such as Fe, Fe-Cr alloy, Cr, or Ni, and is formed by subjecting the brake disk body to electrolytic plating. As shown in FIGS. 3 and 4, fine mesh-like cracks 15 are formed in the plating layer 13 over the entire plating range. By forming the cracks 15 in this manner, many fine metal pieces 13a separated from each other by the cracks 15 are formed on the friction sliding surfaces on both sides of the brake disk main body 11.

As shown in FIG. 2, a support plate 12a on which a brake pad 12 is mounted is provided with a bolt 1
It has a conventionally known structure in which hydraulic pistons 16 detachably attached by 2b are provided. At the time of braking, the pair of brake pads 12 are pressed against both surfaces of the brake disc 3 by the hydraulic piston 16, and the two brake pads 12 sandwich the brake disc 3 and press-contact.

The brake pad 12 is formed of a material having a lower hardness than the metal material forming the plating layer 13 of the brake disk 3. This brake pad 12
Examples of the material include a synthetic resin material and a sintered material containing Cu. By setting the hardness of the brake pad 12 relatively low in this way,
Wear of the plating layer due to friction during braking can be prevented.

As shown in FIG. 5, the brake disc 3 according to the present invention has a plurality of holes 21 formed in a sliding surface 20 against which the above-mentioned brake pad 12 (FIG. 2) is pressed, and a long slot in the radial direction. 22 are formed radially. As shown in FIG. 1 described above, the annular brake disc 3 is
Is fixed to the hub 2. By providing the holes 21 and the slots 22, it is possible to reduce the weight of the brake disk 3 and improve the heat radiation effect by increasing the surface area. In particular, in the radial slots 22, an air flow is generated by the action of centrifugal force in the slots, and the cooling effect is enhanced.

The holes 21 and the slots 22 have a function of discharging wear powder of the brake pad 12. That is, as described above, the hardness of the brake pad 12 is lower than the hardness of the plating layer 13 of the brake disk. Therefore, the pads are worn by the friction welding action of the brake and wear powder is generated. The abrasion powder is introduced into the holes 21 and the slots 22 on the disk surface while the pad is being pressed, and is released to the outside when the pad passes. Also in this case, since the slot 22 has a large opening area and is accompanied by the action of the air flow due to the centrifugal force, the effect of discharging the wear powder is large.
By effectively discharging the abrasion powder in this manner, it is possible to prevent the abrasion powder from adhering to the disk surface and prevent the brake friction characteristics from deteriorating and abnormal wear of the brake disk, thereby providing a highly reliable braking operation for a long time. can get.

The edges of the hole 21 and the slot 22 are chamfered. This chamfering prevents peeling of the plating on the surface and suppresses abrasion of the pad due to impact on the edge of the hole.

According to the present invention, in such a brake disc 3, a surface finishing machining mark is concentrically formed about the disc rotation axis C on the sliding surface 20 where the brake pad 12 is pressed against and a frictional force is generated. A concentric groove 28 is formed in accordance with the processing streak. Although FIG. 5 shows only a few grooves 28 as representatives, they are actually formed concentrically at fine intervals of 1 mm or less or on the order of tens of microns.

FIGS. 6A and 6B are microscopic views of the plating surface on which such grooves are formed. FIG. 6A is a cross-sectional view along the line AA in FIG. 5, and FIG. It is sectional drawing along the direction (pad sliding direction).

A plating layer 13 is formed on a surface of a disk base material made of an aluminum alloy which constitutes the brake disk body 11 described above. Processing marks 28a are formed on the surface of the disk base material, and grooves 28 having a concave and convex cross section in the radial direction are formed in the plating layer 13 according to the processing marks as shown in FIG. The groove 28 has no irregularities in the sliding direction as shown in FIG.

By forming the grooves 28 formed by the processing streaks for finishing the surface of the brake disk body 11 in such a concentric manner, the brake pads 12 (see FIGS. 1 and 2) do not cross the uneven cross section, and Since the pad does not hit the convex portion of the plating surface to give an intermittent impact force, the peeling of the plating is prevented. In FIG. 6, cracks 15 (see FIGS. 3 and 4) of the plating layer 13 are not shown.

FIG. 7 shows the structure of a surface grinding apparatus for forming such concentric processing streaks on the disk surface. The support plate 42 is placed on the turntable 40 that rotates as indicated by the arrow f.
The brake disk 11 to be finished on the support plate 42 is fixed by the chuck 41 with its center (rotation center when mounted on the axle) coincides with the rotation center of the turntable 40. The brake disk 11 is supported on the support surface 42a of the support plate 42 in close contact therewith. In this state, the brake disc 11 is rotated by the rotating grindstone 43 which can rotate as shown by the arrow g and can move as shown by the arrow h.
Grind one side of the surface. At this time, since the center of the brake disc 11 is the center of rotation,
By adjusting the moving speed in the direction of the arrow h, the rotating speed of the rotary table 40, the rotating speed of the rotary grindstone 43, and the like, processing marks are formed substantially concentrically on the brake disk surface.

After one surface of the brake disk 11 is finished, it is turned over, and the finished surface is brought into close contact with the support surface 42 a of the support plate 42, and is fixed by the chuck 41. In this state, the opposite surface is finished by grinding, and the finishing of both surfaces of the brake disk 11 is completed. In this case, one side is finished first, and the opposite side is finished with the finished surface being in close contact with and supported by the support surface of the support plate, so that the parallelism of both surfaces can be finished with high precision.

FIG. 8 is a flowchart of the brake disk manufacturing method according to the above embodiment. First, as shown in step S1, the molten aluminum alloy is sprayed from a nozzle toward a target having a predetermined radius in a spray form, and the sprayed aluminum alloy droplets generated are passed through cool air or room temperature air to thereby stop the process. By cooling to a semi-solid state, and spray forming the spray droplets of the aluminum alloy in the semi-solid state into a substantially columnar shape having a predetermined radius, for example, a column having a predetermined radius of 350 mm is formed by solidifying aluminum alloy particles. .

In step S2, the aluminum alloy grain cylinder is cut to produce a disk having a thickness of, for example, 50 mm. Next, by pre-forging in step S3,
A disk having a thickness of, for example, 50 mm is compressed to about 30 mm, and a hole is formed at the center to produce a donut-shaped disk having an increased density. This donut-shaped disk is a billet.

The surface hardness of this billet in the forging process of the step S4 is thick with H _RE = 55 to 88 and the donut-shaped disk of about 15 mm. This donut-shaped disk is placed in step S5.
T6 treatment, that is, a solution treatment in which the solution is kept at a solution solution temperature of 500 ° C. for 4 hours and then water-cooled.
After holding at 0 ° C for 4 hours, air-cooling is performed,
The surface and internal hardness and H _RE = 90 to 100.

Next, by rough processing in step S6, inner and outer processing, mounting hole processing, forging processing of the hole 21 and the slot 22 of the sliding surface, and processing of the disk surface are performed. The friction surface of the disk surface was Ra 5 μm as the surface roughness before polishing.
Preliminary processing is applied to the extent. Next, in the finishing in step S7, the friction surface has a surface roughness of Ra1 to 3.5 μm.
Polish until it reaches about m. After finishing processing,
The process proceeds to the plating step as shown in step S8. By the finishing in step S7, concentric processing streaks are formed on the disk surface as described above.

FIG. 9 is a detailed flowchart of the pre-processing of the plating step of step S8 in the flow of FIG. After this pretreatment, electrolytic plating is performed. The plating pretreatment has the same contents as the pretreatment at the time of electrolytic plating, which is generally performed, and includes a degreasing step shown in Step P1 of FIG. 9, a pickling step shown in Step P2, and Step P2.
3, an alkaline etching step shown in Step P4, an acid activation step shown in Step P4, and a zinc substitution step shown in Step P5.
The nitric acid immersion step shown in Step P6, the zinc replacement step shown in Step P7,
7 and a water washing step performed after the zinc substitution step.

In each of the steps P1 to P7, as shown in Table 5 below, the brake disc main body 11 is placed in a bath containing an aqueous solution having a predetermined composition and maintained at a predetermined bath temperature. For a treatment time of. By performing these pretreatments, the adhesion between the plating layer and the base material aluminum alloy layer in the plating process in the next step is improved.

After performing the plating pretreatment, the brake disk main body 11 is subjected to electrolytic plating in step P8.
In this electrolytic plating process, the brake disk body 11 is immersed together with the anode in a stationary bath of a plating solution, using the brake disk body 11 as a cathode.
These are implemented by connecting to a DC power supply. This plating process is performed until the thickness of the plating layer 13 formed on the brake disk main body 11 becomes about 20 μm or more.

In the plating process of step P8, for example, when performing Fe plating or Fe-Cr alloy plating, the plating is performed under the plating conditions shown in Table 6. That is, using a stationary bath filled with the plating solution and the plating solution held at the indicated bath temperature and plating with the current density and plating time shown in Table 6, the plating layer having the plating film thickness and hardness shown in Table 6 was obtained. Is obtained. 20 plating film thickness
In order to make it equal to or more than μm, the current density is made larger than the value in the table or / and the plating time is made longer than the time in the table.

Before the brake disk body 11 is immersed in the plating solution, a mask (not shown) is provided in another portion so that the plating layer 13 is formed only on the friction surface of the brake disk body 11. Note that the plating layer 13 may be formed on the entire outer surface of the brake disk 3 without using such a mask.

By forming the plating layer 13 so as to have a thickness of at least 10 μm or more, the plating layer 13 can be formed on the plating layer 13 without any special treatment.
The crack 15 is generated as shown in FIG. Plating layer 13
When the film thickness of is approximately 10 μm, crack 1 shown in FIG.
Even if the diameter d of the circle inscribed in the plating layer metal piece inside 5 is large, it is about 1.5 mm. This is because an internal stress that tends to shrink occurs in the plating layer. When the film thickness increases, a mesh-like crack is generated on the plating surface due to the internal stress.

After the plating step, the brake disk body 11 is mounted on the hub 2 without any special post-processing. After that, the motorcycle is driven to use the front wheel brake. At this time, when the temperature of the plating layer 13 increases due to frictional heat generated by friction between the brake pad 12 and the outer surface of the plating layer 13, the brake expansion coefficient of the aluminum alloy brake disk body 11 is higher than that of the plating layer. Since the brake disk body 11 is large, the brake disk body 11 tends to expand more. However, the plating layer does not hinder the expansion of the brake disk body 11 due to the widened crack, and the friction surface is not distorted. That is, there is no distortion such as bending or bending which results in a large frictional force being locally exerted by the brake pad 12 during the braking operation, and the plating layer provided for improving the wear resistance is formed by the brake disk body. It does not come off.

Accordingly, in the brake disk 3 configured as described above, the brake disk body 11 can be made of an aluminum alloy to reduce the weight, and the friction surface is made of metal formed by plating to improve wear resistance. Thus, both weight reduction and improvement in wear resistance can be realized.

Further, a metal for improving abrasion resistance is formed by plating with a small temperature change, and a plating apparatus for carrying out this manufacturing method is a general-purpose stationary bath type or a circulating plating solution. Since a high-speed plating type can be used, a metal with high wear resistance is provided on the brake disk main body 11, so that distortion of the friction surface can be reduced as compared with a joining device involving hot melting.
Destraining and repolishing are not always required.

It is desirable that the diameter d inscribed in the plating layer metal piece inside the crack 15 is small, but even if it is large, about 1.5 mm, if the plating layer metal piece inside the crack 15 is joined to the brake disk, Even if the elongation of the main body 11 is hindered, the size of the plating layer metal piece is small, and warpage occurs at the portion of the plating layer metal piece,
The bending and the like are small, and a large frictional force acts locally on the brake pad 12, so that a large shearing stress does not act on the joint surface between the plating layer and the brake disk main body 11. The metal pieces do not come off. Further, as the plating film thickness increases, even if cracks 15 enter the plating surface during plating, internal stress tends to remain, and the frictional heat generated by the brake operation causes the plating layer metal pieces inside the cracks 15 to move into the brake disk body 11. , And finer cracks occur in the metal pieces of the plating layer.

When the thickness of the plating layer is about 20 μm or more, generation of further fine cracks in the metal piece of the plating layer surely occurs. Due to the minute cracks, the plating layer does not hinder the elongation of the brake disk body 11 more reliably during the braking operation, and peeling of the plating layer due to warping, bending or other distortion can be prevented.

That is, in the method of manufacturing the brake disk 3 according to this embodiment, the crack is formed in the metal layer in the plating step by using the plating layer having a thickness of about 20 μm or more, and the brake disk 3 is actually used. By doing so, the cracks caused by plating are transferred to finer cracks, so that an apparatus or a special process for exclusively forming cracks in the metal layer formed by plating is unnecessary.

FIG. 10 is a flow chart for explaining another method of manufacturing a brake disk in which a crack is formed by heating. FIG. 11 is an enlarged view of a surface portion of the brake disk formed by the manufacturing method according to this embodiment. FIG.

In order to carry out the method of manufacturing a brake disk according to this embodiment, first, steps S1 to S1 in FIG.
7 (same as steps S1 to S7 in the flow of FIG. 8 described above)
The brake disk main body 11 is formed into a predetermined shape through the steps indicated by, and then plated in step S8. Here, Fe-Cr is used as the plating layer metal having high wear resistance.
An example using an alloy will be described. Table 6 shows the conditions of the surface metal plating treatment at this time.

The metal of the plating layer is Fe-
In addition to the Cr alloy, Fe, Cr, Ni, and the like can be used.

In this embodiment, the plating is
The plating is performed so that the thickness of the plating layer 13 falls within a range of about 10 to 100 μm. The plating method is the same as in the case of the first embodiment shown in FIGS. In the case of the first embodiment, the plating layer 13 must be formed so that the thickness of the plating layer 13 is larger than 20 μm. However, in the case of this embodiment, the plating layer 13 is thicker than in the case of the first embodiment. Even if the thickness of 13 is reduced, further fine mesh-like cracks are surely formed.

After the plating process is completed, as shown in step S9 of FIG. 10, the substrate is heated at about 500 ° C. for 5 hours. This heating is performed by inserting the brake disk body 11 into a heating furnace or the like. By heating the plating layer 13 in this heating step, fine mesh-like cracks 15 are formed in the plating layer 13 and, as shown in FIG. Are formed in a state where they are separated from each other by cracks 15.

According to this method, since the entire brake disc body 11 is heated, the entire body is thermally expanded uniformly, and in addition to the cracks due to internal stress during plating, finer and more uniform cracks can be generated. . Therefore, it does not become a partially large plating layer metal piece,
The size of the inscribed circle of the plating layer metal piece does not vary greatly.

In order to form finer network-like cracks 15, the heating temperature may be set to about 400 ° C. or higher from the difference in the coefficient of thermal expansion between the base material (aluminum alloy) and the plating layer. As shown in this embodiment, a heating temperature of 500
° C, Fe or C forming the plating layer 13
The atoms of r diffuse into the base metal, and the atoms of the aluminum alloy forming the brake disk body diffuse into each other into the plating layer having the cracks 15.
A diffusion layer indicated by 7 is formed. If the heating temperature is about 500 ° C., the diffusion layer 17 can be formed in about 5 hours.

Since the diffusion rate increases exponentially in proportion to the processing time, if the temperature is lowered below 500 ° C. to 400 ° C. or less, the diffusion rate decreases and the formation of the diffusion layer takes an extremely long time. . On the other hand, when the processing temperature is set to 600 ° C. or higher, the brake disk body 11 made of an aluminum alloy partially melts,
1 may be deformed. Also, crack 1
Of 5, the plating layer remains in the diffusion layer 17, and new cracks due to heating are mainly formed in the plating layer.

As described above, even if fine mesh-like cracks 15 are formed in the plating layer 13 by heating the plating layer 13 to 400 ° C. or higher after plating, the same effect as in the first embodiment can be obtained. Is obtained.

As shown in this embodiment, the plating layer 1
By performing the heating so that the diffusion layer 17 is formed between the third layer 3 and the brake disk body 11, the adhesion strength of the plating layer 13 can be increased.

FIG. 12 is a flowchart of another embodiment of the present invention. In this embodiment, the cracks 15 of the plating layer 13 are formed by sulphonitriding.

First, step S1 of the flow of FIG.
As in Steps S6 to S6, a billet is prepared by spray forming of an aluminum alloy (Step R1), and a disc-shaped base material having a predetermined disk shape before punching is formed (Step R2). The hole 2 shown in FIG.
After forming the slots 1, the slots 22, the mounting holes 23, and the like (Step S6 in FIG. 8), finishing is performed in Steps R3 to R5 (Step S7 in FIG. 8). In this finishing, the disc base material (brake disc main body) after the roughing is polished one by one as described with reference to FIG. That is, one side is polished and finished (step R3) with the center of the brake disk body being supported by being aligned with the center of rotation of the support plate of the polishing device, and then the finished surface is turned over. The support surface is fixed by being supported (Step R4), and the opposite surface is polished and finished (Step R5). As described above, concentric processing striations are formed on both surfaces of the brake disk body by such surface finishing. After this finishing, plating is performed (step R6).

In this plating process, for example, an Fe—Cr alloy can be used as a metal having high wear resistance. In addition to such Fe-Cr alloys, Fe, Cr,
Ni or the like can also be used.

In the plating, the thickness of the plating layer 13 is 10 to 1
It is performed so as to fall within a range of about 00 μm. The plating method is the same as in the first embodiment. In the case of the first embodiment, the thickness of the plating layer 13 must be formed to be greater than 20 μm. In the case of this embodiment, however, the thickness of the plating layer is smaller than that of the first embodiment. May be.

After the plating step is completed, as shown in Step R7, a gas sulphated nitriding treatment is performed. This gas sulphonitriding is performed under the conditions of the gas sulphonitriding shown in Table 7. That is, the heating is performed by heating the plated brake disk body 11 in a furnace in an atmosphere of a mixed gas of N ₂ , H ₂ S, and NH ₃ . The heating temperature is 500 ° C. ± 50 ° C., and the heating time is about 5 hours.

By performing the gas oxynitriding treatment in this way, the hardness of the metal of the plating layer 13 can be increased, and the plating layer 1
By heating 3, fine mesh-like cracks 15 are formed in the plating layer 13. That is, the fine metal piece 13a made of a Fe—Cr alloy having higher hardness than the case of taking the second embodiment (FIGS.
Thus, a large number are formed on the brake disk main body 11 in a state of being separated from each other.

As described above, even if the gas oxynitriding process is performed after plating to form fine mesh-like cracks 15 in the plating layer 13, the wear resistance is high as in the first embodiment. This has the effect that the plating layer is difficult to peel off.

Further, since the temperature at the time of performing the gas sulphiditriding treatment is as high as in the second embodiment, the Fe or Cr atoms forming the plating layer 13 and the aluminum alloy forming the brake disk body 11 are formed. Are diffused with each other, and a diffusion layer 17 (see FIG. 11) is formed between the two. For this reason, the adhesion strength of the plating layer 13 can be increased.

Further, since the hardness of the plating layer 13 can be increased, it is difficult to wear and the durability time can be extended, and maintenance of the disk brake device can be performed only by replacing the brake pad 12 which is cheaper than the brake disk. Become.

The cracks 15 in the plating layer 13 can also be formed in a fine mesh shape by subjecting the plating layer 13 to mechanical processing such as burnishing. Also,
After the burnishing is completed, the plating layer 13 may be subjected to a gas sulfide nitriding treatment as shown in Step R7 of FIG. 12 to increase the hardness of the plating layer 13.

After the burnishing, a heat treatment can be carried out in the same manner as in the second embodiment, instead of the gas sulphiditriding treatment. By setting the heating temperature to 400 ° C. or higher, the crack 15 can be further miniaturized. If the heating temperature is 500 ° C., the diffusion layer 17 is efficiently formed between the plating layer 13 and the brake disk body 11 in about 5 hours, and the adhesion strength of the plating layer 13 can be increased.

FIG. 13 is a sectional view showing an embodiment in which an intermediate plating layer is formed between the plating layer and the brake disk body, and FIG. 14 is a flowchart of the plating step.
In FIG. 13, reference numeral 18 denotes an intermediate plating layer. In this embodiment, the intermediate plating layer 18 is formed on the brake disk main body 11 by plating. The metal material forming the intermediate plating layer 18 is a metal having high corrosion resistance, for example, Ni. Between the intermediate plating layer 18 and the brake disk main body 11, a first diffusion layer 17a in which atoms of the intermediate plating layer 18 are diffused in the brake disk main body 11 is formed. Also, the intermediate plating layer 18 and the outer plating layer 1
3, a second diffusion layer 17b in which atoms of the outer plating layer 13 are diffused in the intermediate plating layer 18 is formed.

In order to manufacture the brake disc 3, as in the first embodiment, the brake disc main body 1
1 is formed in a predetermined shape, and steps P1 to P7 in FIG.
After performing the pre-plating process and the subsequent washing with water, Ni plating is performed as shown in Step P9.

The Ni plating is performed by using a plating apparatus used to form a plating layer 13 on the outer surface of the brake disk main body 11. The plating conditions are the same as when the plating layer 13 is formed on the outer surface of the brake disk main body 11.

After the Ni plating step is completed, the substrate is washed with water and subjected to a heat treatment to form the first diffusion layer 17a between the Ni plating layer (intermediate plating layer 18) and the brake disk body 11 (step). P10). The heating temperature at this time is also set to 500 ° C. or higher. This first diffusion layer 1
The formation of 7a increases the adhesion strength of the Ni plating layer.

The plating thickness of the intermediate layer is 0.1 to 5 μm.
If it is about m, it is not necessary to make it thick enough for corrosion resistance. By making it thin, there is no crack due to internal stress during plating, and it is possible to follow thermal expansion due to heat generated during braking, and to prevent cracks from occurring in this Ni plating layer Can be. Further, since Ni has a thermal expansion coefficient close to that of an aluminum alloy, the generated thermal stress is small, and cracks are less likely to occur.

After the heating, as shown in Step P8, plating is performed to form a plating layer 13 made of a metal having high wear resistance, for example, Fe, Fe-Cr, or Cr on the outer surface of the Ni plating layer. . The plating conditions are the same as in the first embodiment.

After this plating step is completed, fine mesh-like cracks are formed in the plating layer 13 in the same procedure as in each of the above embodiments, and a gap between the plating layer 13 and the Ni plating layer 18 is formed. The second diffusion layer 17b is formed.

As shown in this embodiment, by forming the intermediate plating layer 18 inside, water entering from the crack 15 of the plating layer 13 on the outer surface comes into contact with the aluminum alloy brake disk main body 11. Can be prevented by the intermediate plating layer 18 made of metal (Ni) having high corrosion resistance.

Therefore, the brake disk 3 according to this embodiment does not corrode the brake disk main body 11 even if it is exposed to rainwater, and prevents the plating layer 13 on the outer surface from peeling off due to the corrosion. be able to. Moreover, since both the plating layer 13 and the intermediate plating layer 18 on the outer surface are formed by plating, two types of metal layers can be formed by one plating apparatus, and the manufacturing cost can be reduced.

Although the Ni forming the intermediate plating layer 18 has a higher coefficient of thermal expansion than the aluminum alloy, the coefficient of thermal expansion is closer to that of an aluminum alloy than that of an iron-based metal such as cast iron. The thermal stress generated during thermal expansion is relatively small. Therefore, the brake disk 3 is not bent or bent due to the formation of the intermediate plating layer 18, and the plating layer 13 on the outer surface does not peel off from the brake disk main body 11.

[0080]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an aluminum alloy forming the brake disk body 11, for example, alloys 1 to 1 shown in Table 1 below are used.
The one shown as Alloy 3 can be used.

[0081]

[Table 1]

The use of alloy 1 shown in Table 1 increases the strength of the brake disc 3, and the use of alloys 2 and 3 increases the heat resistance. That is, in a general aluminum alloy, the strength decreases due to a temperature rise during braking, and the aluminum alloy easily deforms. For this reason, strength and heat resistance were improved by adding Fe and Zr. Manufacture of the disc material is based on billet production by spray forming.
This reduces the crystal grain size in the metal composition (1 μm or less)
To improve strength. These alloys cannot be formed by casting. When melted, coarse Al-Fe intermetallic compounds are crystallized and become brittle. Therefore, forming is performed by forging.

The materials shown in Tables 2 to 4 below can be used as the material of the brake pad 12. Tables 2 and 3 show examples of the material of the synthetic resin pad, and Table 4 shows examples of the material of the sintered pad. Brake pad 1
No. 2 has a lower hardness than the plating layer 13 for improving the wear resistance of the brake disk body 11. For this reason, the maintenance limit of the disc brake device 1 is reduced by shortening the use limit (durable time until replacement is required) of the brake pad 1 which is smaller than the brake disc 3 and is likely to be inexpensive. Can be.

[0084]

[Table 2]

[0085]

[Table 3]

[0086]

[Table 4]

In Tables 2 and 3, some of the reinforcing members and abrasive particles contain components harder than the metal of the plating layer. However, by making the overall hardness including the base material lower than that of the plating layer, the same hardness as the plating layer is obtained. Use limit or reach use limit earlier than plating layer.

The hardness of the pad made of the sintered material formed of the material shown in Table 4 is 50 or less in terms of HV. Table 4
Materials shown as others in the above have a composition ratio of 10% or less.

The plating pretreatment performed in each of the embodiments was performed under the conditions shown in Table 5 below.

[0090]

[Table 5]

Table 6 shows the plating conditions when the outer surface of the brake disk is plated with Fe or Fe--Cr alloy.

[0092]

[Table 6]

The items shown in Table 6 include Fe plating, F
For e-Cr plating, the film thickness is 20 μm, and the plating is performed so that the hardness of Fe plating is 300 to 400 in HV and the hardness of Fe-Cr plating is 600 to 700 in HV. I have. The fine mesh cracks 15 formed in the plating layer 13 have a width of 1 to 10 μm and a crack density of 10 to 30 mm / mm ² . At this time, the diameter d of the mesh-shaped inscribed circle due to the crack 15
Most are 1.5 mm or less. The crack density is defined as crack 15 per 1 mm ^{2 of} plating surface.
Is the sum of the lengths (mm).

The diffusion layers 17, 17a and 17b have a thickness of 1
About 50 μm. The intermediate plating layer 18 has a thickness of about 0.1 to 5 μm when the material metal is Ni.

The gas sulphiditriding was carried out under the conditions shown in Table 7 below.

[0096]

[Table 7]

When the gas sulphidizing treatment is carried out under the conditions shown in Table 7, the hardness is 75 HV in the case of Fe plating.
0 (700 to 800), and in the case of Fe—Cr alloy plating, the hardness is about 1250 in HV (1100 to 1).
350).

In each of the above embodiments, the hub 2
The example in which the inner peripheral portion of the aluminum alloy brake disc main body 11 having good thermal conductivity is directly fixed to the hub 2 with the aim of releasing the friction heat generated by the brake pad 12 to the hub 2 has been described. When the heat radiation property other than the area where the brake pad 12 is in contact is sufficient, such as when the surface area of the brake pad 12 is large, an annular iron-based alloy mounting plate is attached to the inner periphery of the brake disc body 11,
It is possible to adopt a structure for mounting to the hub 2 via this mounting plate. Further, the brake disk main body 11 may be provided with an annular iron-based alloy mounting plate on the outer peripheral portion, and mounted on the hub 2 via this mounting plate. In the case of this structure, the brake pad is slid on the inner peripheral side of the brake disc main body 11.

[0099]

As described above, in the present invention, since the processing marks on the pad sliding surface are formed concentrically about the disk rotation axis, the sliding direction of the pad and the processing marks are different. The groove directions match, and the pad slides along the groove and does not cross the concave and convex cross section of the groove. Therefore, peeling of the plating formed on the aluminum alloy is prevented. This makes it possible to obtain a brake disc having sufficient wear resistance using a lightweight aluminum alloy having good heat conductivity.

[Brief description of the drawings]

FIG. 1 is a sectional view of a disc brake device to which the present invention is applied.

FIG. 2 is a sectional view of a brake caliper.

FIG. 3 is an enlarged sectional view of a surface portion of a brake disc according to the present invention.

FIG. 4 is an enlarged plan view of a surface portion of a brake disc according to the present invention.

FIG. 5 is a plan view of the entire brake disc of the present invention.

FIG. 6 is an explanatory view of a shape of a plating surface portion of the brake disk of the present invention.

FIG. 7 is an explanatory view of a configuration of a surface finishing grinding device of the present invention.

FIG. 8 is a flowchart of a method of manufacturing a brake disk according to the present invention.

FIG. 9 is a flowchart of a plating step in the manufacturing method of FIG. 8;

FIG. 10 is a flowchart of another method for manufacturing a brake disk according to the present invention.

FIG. 11 is an enlarged sectional view of a surface portion of a brake disk formed by the method of FIG. 10;

FIG. 12 is a flowchart of another manufacturing method of the present invention.

FIG. 13 is an enlarged sectional view of a surface portion of a brake disc according to another embodiment of the present invention.

FIG. 14 is a flowchart of a plating process according to the embodiment of FIG.

FIG. 15 is a configuration explanatory view of a conventional surface finishing grinding device.

[Explanation of symbols]

1: disc brake device, 2: hub, 3: brake disc, 4: front fork, 5: caliper, 6: axle, 7: spoke, 8: rim, 11: brake disc body, 12: brake pad, 12a: support plate,
12b: bolt, 13: plating layer, 13a: metal piece, 1
4: bolt, 15: crack, 16: hydraulic piston, 1
7, 17a, 17b: diffusion layer, 18: intermediate plating layer, 2
0: sliding surface, 21: hole, 22: slot, 23: mounting hole, 24: disk base material, 25: hole (or groove), 25
a: chamfer, 26: thin plate part, 27: plating layer, 28:
Groove, 28a: processing streak, 30: sag, 31: burr, 4
0: rotary table, 41: chuck, 42: support plate, 4
2a: support surface, 43: rotating grindstone.

Continuation of the front page (72) Inventor Hiroshi Yamagata 2500 Shinkai, Iwata-shi, Shizuoka Prefecture F-term in Yamaha Motor Co., Ltd. (reference) 3J058 AA43 AA48 AA53 AA66 AA77 BA35 BA47 BA68 CB27 CB29 EA08 EA31 EA34 EA39 FA01 FA02

Claims (3)

[Claims] 1. A brake disk made of an aluminum alloy having a processing streak on a sliding surface against which a brake pad is pressed, wherein said sliding surface is plated with a metal having a hardness higher than that of the aluminum alloy. Is a brake disc formed concentrically about the disc rotation axis. 2. The brake disk according to claim 1, wherein mesh cracks are formed in said metal plating. 3. A disk is supported on one side on a supporting surface and the other side is ground, and the ground side is supported on the supporting surface and the opposite side is ground. 2. The method according to claim 1, wherein the metal plating is performed thereafter.