JP3484989B2 - Manufacturing method of aluminum integrated caliper body for disc brake - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a caliper body of an opposed piston type disc brake in which pistons are arranged so as to face both side surfaces of a rotor.

The opposed piston type disc brake has a structure in which a pair of pistons or a plurality of pairs of pistons are opposed to both sides of a rotor fixed to an axle. Specifically, as shown in FIG. 1, which is a plan sectional view showing the piston in use, the head of the rotor 1 is attached to the tip of the piston 3 so as to face the space near the center of the caliper body 2. The brake pads 4 are opposed to both side surfaces of the rotor 1. When the piston 3 is pushed out to the rotor 1 side by the hydraulic pressure sent from the pipe 5, the brake pad 4 moves to the rotor 1 side.
It is pressed against both sides of. The pressing force of the brake pad 4 acts as a braking force on the axle and reduces the rotation speed of the axle. A cast iron casting is conventionally used for the caliper body 2 that supports the piston 3. Since the pipe 5 for hydraulic feeding is arranged in the cast iron casting, the pipe made of steel is incorporated in the caliper body 2 by wrapping it in cast iron.

[0003]

The caliper body made of cast iron is heavy in weight and cannot be reduced in weight, which is strongly required for vehicle-mounted equipment. If a caliper body made of aluminum is used instead of cast iron, the weight can be significantly reduced. However, from the viewpoint of the structure and function of the caliper body, it is not possible to simply replace cast iron with aluminum. That is, the oil is sent from the pipe 5 to the cylinder 6 and the hydraulic pressure is applied to the piston 3 to brake the axle.

In the caliper body 2 made of aluminum,
This reaction force may cause metal fatigue in the bridge portion 7 to cause a crack, and a safety problem remains unsolved.
In order to avoid metal fatigue of the bridge portion 7,
It is known that an outer caliper and an inner caliper are divided into two parts along the line AA to assemble the caliper body by tightening both with a bolt (JP-A-9-177843). However, in the split type caliper body, the number of manufacturing steps increases, resulting in higher cost. In addition, accurate alignment between the outer caliper and the inner caliper is required, and strict control is also required for casting the outer caliper and the inner caliper. Further, stress is concentrated on the bolts that fasten the outer caliper and the inner caliper during operation of the disc brake, which may damage the bolts.

[0005]

SUMMARY OF THE INVENTION The present invention has been devised to solve such a problem, and improves the aluminum alloy used for the caliper body and the casting method to cause the occurrence of a bridge portion. It is an object of the present invention to provide an integral type caliper body that suppresses fatigue cracks that tend to occur and is easy to manufacture and assemble. In order to achieve the object, a method for manufacturing an aluminum integrated caliper body for a disc brake of the present invention is, in order to achieve the object, an aluminum pipe for supplying a hydraulic pressure to a piston pressed against a rotor via a brake pad, as a caliper to be cast. Set in a mold shaped into a body shape, and Si: 5
11% by weight, Mg: 0.25 to 0.7% by weight, Sb:
0.08 to 0.20% by weight, and if necessary, T
i: 0.05 to 0.3% by weight and / or B: 0.000
1 to 0.01% by weight, the balance substantially has a composition of Al, and the elements contained as impurities are P: 0.002% by weight or less, Ca: 0.002% by weight or less, Na: 0.0
01 wt% or less, Sr: 0.001 wt% or less, Fe:
0.3% by weight or less, other impurity elements: Aluminum alloy melt regulated to a total of 0.5% by weight or less is degassed, slag and refined, and then 700 to 760 in a holding furnace.
C., the amount of molten metal required for one casting is transferred to the pool, and the molten metal temperature in the pool is adjusted to 640 to 700.degree. The molten metal is poured into the set mold, and after casting, eutectic Si
And a dendrite arm spacing of 50 μm or less, and an average number of inclusions is adjusted to 0.01 / cm ² or less in K ₁₀ value to obtain a caliper body having a metallographic structure. .

In casting, the required amount of molten metal for one casting is pumped out from the holding furnace, transferred to a cooling trough connected to the mold's pool, and supplied to the pool through the cooling trough. To do. As the cooling gutter, a cooling gutter having a heat dissipation structure, which has a weir for adjusting the flow rate of the molten metal flowing out to the pool, is used. On the other hand, in the hot water pool, a heat insulating material is lined in order to suppress the temperature drop of the contained molten metal and make a uniform temperature distribution.

The flow rate of the molten metal poured into the mold is such that the molten metal fed from the pool to the cavity of the mold is prevented from coming into direct contact with the aluminum pipe. After ascending to cover the aluminum pipe, it is adjusted to rapidly feed the remaining melt into the cavity to improve productivity. Specifically, until the molten metal rising inside the cavity covers the aluminum pipe, the molten metal fed from the molten metal pool does not directly contact the aluminum pipe, so that the molten metal mold is integrated into the mold or An inclined casting method is adopted in which molten metal is fed from a mold to a cavity while gradually rotating a rotatable pool. After filling the cavity with the molten metal, when the sprue is positioned above to exert the pushing effect, defects such as porosity are prevented. During the injection of the molten metal, one end of the aluminum pipe is connected to a vacuum system as necessary, and the outside air is sucked from the other end. This cools the aluminum pipe and prevents melting damage. Mechanical properties required as a caliper body are imparted when performing solution treatment at 520 to 545 ° C. for 1 to 15 hours, water quenching, and aging treatment at 150 to 170 ° C. for 2 to 10 hours after casting.

[0008]

The present inventors investigated the cause of fatigue cracks found in the bridge portion 7 and examined the effects of alloy composition, casting method, etc. on the occurrence of fatigue cracks. as a result,
It was found that fatigue cracks originate from inclusions such as oxides and coarse intermetallic compounds contained in the aluminum alloy of the caliper body. Therefore, the alloy design and casting method for suppressing inclusions and coarse intermetallic compounds were clarified. The aluminum alloy used to manufacture the caliper body according to the invention is designed as follows.

Si: 5 to 11 wt% Improves the flow of molten metal poured into the mold, and M during heat treatment
Precipitates g ₂ Si to improve the mechanical strength of the alloy. Further, by adjusting the Si content to 5 to 11% by weight, the melting point is lower than that of the aluminum pipe which is the cast-in-roll material, and it is possible to prevent the aluminum pipe from being melted by the molten metal poured into the mold. To do. Si content 5 to 1
The range of 1% by weight is a hypoeutectic composition, which is also advantageous in improving machinability during machining. In the hypereutectic region where the Si content exceeds 11% by weight, the primary crystal S generated during solidification
i becomes a crack generation source due to stress, and reduces fatigue strength. Further, in the hypereutectic region, since there are almost no α-Al crystals, the elongation of the material becomes very small, and when a fatigue crack occurs, the propagation speed of the crack is high and the fatigue strength is reduced. On the other hand, if the Si content is less than 5% by weight, the flow of molten metal tends to be poor, and casting defects, machinability, strength, etc. tend to decrease. Further, if the melting point rises as the Si content decreases, the aluminum pipe that is the material to be cast may be melted and damaged.

Mg: 0.25 to 0.7% by weight Heat treatment forms Mg ₂ Si to improve the mechanical strength of the alloy. However, a large amount of Mg exceeding 0.7% by weight
The content of Mg increases the amount of Mg-based oxide. When the Mg-based oxide is mixed in the product, it becomes a crack generation source and reduces the fatigue strength. It also causes a decrease in elongation and a decrease in fatigue strength. Conversely, less than 0.25 wt% Mg
With the content, Mg ₂ Si is not sufficiently precipitated and the required strength cannot be obtained. Sb: 0.08 to 0.20 wt% Eutectic Si is refined into a slender shape to increase elongation and fatigue strength and to secure wear resistance due to eutectic Si. Sb is unlikely to be oxidized in the molten metal even at high temperatures such as during melting and holding. Therefore, the oxide of Sb does not become a crack generation source and is not mixed into the product, and the fatigue strength is increased. Moreover, during solution treatment, the eutectic Si refined by Sb does not grow into massive Si, and the corners of the elongated eutectic Si are rounded. This will also improve the growth. Such an effect is 0.08 to 0.20.
It becomes remarkable in the range of weight%. The refinement of eutectic Si is 0.
Even if Sb is added in an amount exceeding 20% by weight, the effect commensurate with the increase in amount is not observed. Conversely, less than 0.08 wt% Sb
With the content, eutectic Si is not sufficiently refined.

Ti: 0.05 to 0.3% by weight and / or
B: 0.0001 to 0.01% by weight By refining the casting crystal grains of α-Al crystal and improving the dendrite structure with a small dendrite and no directionality, the elongation and fatigue strength anisotropy of the material are improved. It has the effect of improving the values of elongation and fatigue strength. But,
If the Ti content exceeds 0.3% by weight or the B content exceeds 0.01% by weight, coarse TiB ₂ , T which becomes a source of cracks is generated.
iAl ₃ or the like is generated, which causes a decrease in fatigue strength. On the contrary, a Ti content of less than 0.05% by weight or 0.000
If the amount of B is less than 1% by weight, the effect of refining becomes small. The cast crystal grains can be refined by adding Ti or B alone,
The addition effect of Ti and B in combination makes the effect of refinement more remarkable. P: 0.002% by weight or less An element used as a refiner of primary crystal Si,
Since the l-P-based compound acts as a crystal nucleus of Si, it causes coarsening of eutectic Si and crystallization of primary Si. Coarse eutectic Si or primary crystal Si becomes a crack generation source and reduces fatigue strength. Further, if the eutectic Si is coarsened, the elongation is reduced. For this reason, the smaller the P content, the more preferable, but it is unavoidable that it is mixed as an impurity when the alloy is mixed. Therefore, in the present invention, the upper limit of the P content is set to 0.002% by weight.

Ca: 0.002% by weight or less, Na: 0.
001% by weight or less and Sr: 0.001% by weight or less Both are elements known as a eutectic Si refiner, but are easily oxidized in the molten metal. Generated Ca system, Na
When incorporated in the product, the Sr-based and Sr-based oxides become a source of fatigue crack generation, and further act to suppress the function of Sb which makes eutectic Si fine. Therefore, Ca, N
The smaller the content of a and Sr, the better, but it is unavoidable that they are mixed in as impurities during alloy formulation. Therefore, in the present invention, the upper limits are 0.002% by weight,
It was set to 0.001% by weight and 0.001% by weight.

Fe: 0.3 wt% or less It is an element that produces an Al—Fe—Si compound that becomes a crack generation source, so the smaller the amount, the more preferable. But F
If the e content is extremely reduced, the raw materials used during alloy formulation are restricted, resulting in an increase in alloy cost. Therefore, in the present invention, the upper limit of the Fe content is set to 0.3% by weight. Other impurity elements: 0.5% by weight or less in total The aluminum alloy used in the present invention adopts an alloy design that prevents the inclusion of oxides that cause fatigue cracks and the crystallization of intermetallic compounds. . Therefore, it is necessary to reduce other impurity elements as much as possible. From such a viewpoint, in the present invention, the total amount of other impurity elements is regulated to 0.5% by weight or less.

Average length of eutectic Si: 10 μm or less The smaller the eutectic Si, the more effective it is to give elongation to the alloy material and improve the fatigue strength. The size of eutectic Si is S
It is adjusted by the addition amount of b. When the average length of eutectic Si exceeds 10 μm, it tends to be a source of fatigue cracks. In addition, since wear resistance is required in the cylinder portion where the piston slides, excessively fine eutectic Si is not preferable. Dendrite arm spacing (DAS): 50 μm
Below, the smaller the DAS of the α-Al crystal, the more the alloy material is stretched and the fatigue strength is improved. Therefore, in the present invention,
The upper limit of DAS was 50 μm. If the DAS exceeds 50 μm, coarse intermetallic compounds are generated and aggregated at the boundaries between dendrites and dendrites and at the crystal grain boundaries, which easily becomes a source of fatigue cracks. In order to reduce the DAS, it is necessary to rapidly cool the molten metal poured into the mold, but in the casting method according to the present invention, a cooling mechanism is set at a required position inside the mold and supplied to the cooling mechanism. It is also possible to cool the mold with cooling water.

Average number of inclusions: 0.01 / K ₁₀ value
cm ² or less Coarse inclusions having a length of 0.1 mm or more, which are observed with the naked eye or a 10 times magnifying glass, are sources of fatigue cracks. Coarse inclusions of this type include oxides and oxide films of Al, Na, Ca, Sr, Mg, etc., Al-Si-Fe-based, Al-Ti-based,
It is derived from crystallized intermetallic compounds such as Ti-B type and Mg-Sb type, and foreign substances mixed in from furnace materials, tools and the like. It is important to keep the number of coarse inclusions below 0.01 / cm ² in the observation field of view.
Fatigue cracking does not occur in the bridge portion 7, and an integrated caliper body excellent in fatigue strength and safety can be obtained. The average number of the inclusions is displayed as a K ₁₀ value obtained by observing the fracture surface of the cast alloy material with a 10 times magnifying glass and converting the counted number per unit area. When measuring the average number, two fracture surfaces on the left and right are treated as one piece, and 5 to 6 pieces are treated as one sample. In the present invention, the area 2
The data of one sample was obtained at 5 cm ² , and the average number of inclusions was calculated as the average value of the data of 7 samples. When the K ₁₀ value thus obtained is 0.01 / cm ² or less, excellent elongation characteristics and fatigue strength are imparted to the alloy material. On the other hand, if the K ₁₀ value exceeds 0.01 / cm ² , the required fatigue strength cannot be obtained.

A K ₁₀ value of 0.01 / cm ² or less can be achieved by the following method. N mixed in when alloy is mixed
A, Ca, Sr, etc. are suppressed as much as possible by selecting the blended raw materials, and the high temperature treatment of the molten metal after oxidation causes the mixed Na, Ca, Sr, etc. to float and separate from the molten metal as a furnace slag. When the floating slag is removed from the molten metal, N
It becomes an aluminum alloy melt with very little a, Ca, Sr, etc. Mg, Al, etc. also form an oxide film and float on the surface of the molten metal, but these oxide films are separated from the molten metal during slag removal. When transferring the molten metal from the holding furnace to the pool, a method is adopted so that the oxide or oxide film is not caught in the molten metal. Further, by adjusting the manufacturing conditions, Fe,
It prevents Ti and other elements from growing into coarse crystallized substances. Inclusions originating from furnace materials and tools are separated from the molten metal by holding the molten metal at a high temperature.

High temperature holding: Hold at 700 to 760 ° C in a holding furnace
The raw materials mixed to have a predetermined composition are melted, degassed, refined, and slag-deposited to prepare an aluminum alloy melt. The molten metal produced is 700
Maintained at ~ 760 ° C, stable high quality molten metal can be obtained. As the holding furnace, a small hand-held furnace of about 500 to 1000 kg is preferable. By the high temperature holding treatment, inclusions such as oxides generated in the melting step, foreign materials derived from the furnace material and tools are separated from the molten metal and float on the surface of the molten metal as a furnace slag. Therefore, when the furnace slag is removed, it is possible to prevent the furnace slag such as oxides from being brought into the product, and it is possible to obtain a molten alloy containing as few inclusions as the source of fatigue cracks.

From the above, the holding temperature is 700 to
The temperature range is set to 760 ° C. Among them, Ca, N
Since a, Sr and the like are oxidized during the high temperature holding treatment and transferred to the furnace slag, the amounts of Ca, Na and Sr in the molten alloy after the holding treatment are significantly reduced. On the other hand, since Sb is dissolved in the molten metal without being oxidized, the amount of Sb effective for refining eutectic Si is not reduced by the holding treatment. 760
At a holding temperature above 0 ° C, the amount of heat energy consumed becomes too large. On the contrary, at a holding temperature below 700 ° C, the viscosity of the molten metal becomes high and the floating separation of inclusions becomes insufficient.
Moreover, if the molten metal is kept at a temperature of less than 700 ° C. for a long time,
There is a possibility that the Mg-Sb based plate-like compound may grow. Ti
Also becomes TiAl ₃ and crystallizes under similar temperature conditions. M
The g-Sb-based plate-like compound or TiAl ₃ crystallized product becomes a source of fatigue cracks when mixed in the product. Also in this respect,
It is important to set the molten metal holding temperature in the range of 700 to 760 ° C.

Even at the stage of transferring the molten metal from the holding furnace to the molten metal pool, when the amount of molten metal required for one casting is drawn by the ladle, oxides may be mixed in the molten metal. Therefore, it is necessary to take care so that there is no inclusion of oxides during pumping. Casting The molten aluminum alloy prepared as described above is cast by gravity casting, low pressure casting, or the like. An aluminum pipe for hydraulic pressure is set in advance in the mold, but the DAS of the casting structure can be reduced by cooling the inside of the core and the mold with water. In order to prevent melting damage of the aluminum pipe set in the mold, it is preferable to adjust the temperature of the melt injected into the mold so that the temperature of the melt in the mold is 585 to 640 ° C. . Therefore, an important problem is how to lower the temperature of the molten metal stored in the holding furnace at a temperature of 700 to 760 ° C. before casting. In the present invention, the holding temperature is 700 to 760 ° C. and the pouring temperature is 585 to 6
In order to carry out the temperature reduction to 40 ° C. industrially, the following method is adopted.

(Method 1) In the vicinity of the sprue 11 of the die 10,
A pool 12 capable of accommodating the molten metal M for one casting is provided integrally with the mold 10. If the temperature of the molten metal M contained in the pool 12 is controlled to 640 to 680 ° C., the mold 10
The molten metal M poured in is cooled by the mold 10 and the temperature of the molten metal M is lowered to 585 to 640 ° C. The molten metal M pumped from the holding furnace (not shown) by the ladle 13 is 700 to 760.
It is also possible to directly transfer the molten metal M to the hot water pool 12 and hold the molten metal M until the temperature is lowered to 640 to 680 ° C. in the hot water pool 12. However, 12
The molten metal M housed in is a molten metal with a single casting amount,
Waiting for the temperature to drop after each casting is not productive. Therefore, it is preferable to transfer the molten metal M from the holding furnace to the cooling gutter 14. The cooling gutter 14 has a heat dissipation structure for lowering the temperature of the transferred molten metal M. Specifically, thickness 1 to 20
It is made of mm steel and has a thin coating of release agent on the inside.

A weir 15 is provided on the outlet side of the cooling gutter 14 and an outlet 16 is provided below the weir 15. The weir 15 prevents the furnace slag carried from the holding furnace through the ladle 13 to the basin 12 and the oxide film formed on the surface of the molten metal M while being stored in the cooling gutter 14 from flowing into the basin 12. To do. The cooling gutter 14 is further effective in adjusting the amount of the molten metal M flowing out from the outflow port 16 and controlling the residence time of the molten metal M in the cooling gutter 14 and, consequently, the temperature decrease and temperature of the molten metal M. In addition,
In order to adjust the flow rate more positively, it is preferable that the weir 15 is provided so as to be able to move up and down with respect to the cooling gutter 14 and the flow passage cross-sectional area of the outlet 16 is made variable. The molten metal M passes through the weir 15 and is sent from the outlet 16 to the molten metal pool 12 along the supply gutter 17. The molten metal M transferred to the cooling gutter 14 at 700 to 760 ° C. is cooled to 640 to 700 ° C. when it flows into the basin 12 through the cooling gutter 14 and the supply gutter 17. The time required for the molten metal M to move from the ladle 13 to the pool 12 through the cooling gutter 14 is about ten and several seconds, and the molten metal M is cooled to 640 to 700 ° C. which is effective for pouring in a short time. It is implemented with high productivity. Moreover, since the temperature is not lowered over a long period of time, the Sb-Mg-based compound does not crystallize from the molten metal.

The basin 12 has a heat insulating structure in which a heat insulating material 18 having a thickness of, for example, 1 to 5 cm is lined.
The surface of 8 is coated with a release agent. Therefore, when pouring the molten metal M into the mold 10 from the pool 12, the temperature of the molten metal M does not drop excessively, and the flow of molten metal in the mold 10 is guaranteed. Molten metal M stored in the pool 12
The temperature distribution is made uniform by the heat retaining structure of the basin 12, and is poured and cast into the mold 10 under stable conditions. After confirming that the temperature of the molten metal M in the molten metal pool 12 is in the range of 640 to 700 ° C., the molten metal M is poured into the mold 10 from the molten metal pool 12. In addition, the core 20 and the aluminum pipe 21 are set in advance in the mold 10, and
The mold 10 is arranged so that 1 is oriented in the horizontal direction.

In injecting the molten metal M into the die 10, as shown in FIG. 3, the die 10 is gradually rotated with the end corner of the die 10 on the ground level GL as the center of rotation O. With the rotation of the mold 10, the pool 12 integrated with the mold 10 is tilted, and the molten metal M is pooled with the pool 12.
Then, it is slowly poured into the cavity 19 in the mold 10 through the sprue 11. If the flow of the molten metal M toward the cavity 19 directly contacts the aluminum pipe 21, the aluminum pipe 21 may be melted and damaged. Therefore, if the rotation speed of the mold 10 is adjusted so that the molten metal M flows into the cavity 19 along the inner wall of the mold 10, direct contact between the molten metal M and the aluminum pipe 21 is prevented, and the aluminum pipe 21 is Protected from melting damage.
Direct contact between the molten metal M and the aluminum pipe 21 can also be prevented by devising the bottom surface from the pool 12 to the sprue 11 and the inclined surface of the sprue 11.

The inflowing molten metal M collects from the bottom of the cavity 19 and gradually raises the molten metal surface S. Then, the molten metal M cooled by the mold 10 and the core 20 gradually casts up the aluminum pipe 21. In order to accelerate the cooling of the molten metal M in order to prevent the porosity that causes the fatigue cracks, a mold 10 and a core 20 having a water cooling mechanism for cooling necessary portions with cooling water are used, It is preferable to inject the molten metal M while cooling it. Further, during casting, one end of the aluminum pipe 21 is connected to a vacuum system, and the aluminum pipe 21 is cooled by sucking outside air from the other end.
Is surely prevented from melting. Cooling by vacuum suction is also effective in ensuring the safety of casting work. what if,
Even if the aluminum pipe 21 melts and the inner space of the pipe comes into contact with the molten metal M, the molten metal M fed into the aluminum pipe 21 by vacuum suction solidifies and closes the pipe. , Work safety is improved. On the other hand, in the method of sending pressurized air or cooling water to the aluminum pipe 21 to cool it, the pressurized air or water melts the molten metal M when the aluminum pipe 21 is melted.
It is dangerous to blow out.

The mold 10 is further rotated so that the inclination angle is θ ₁ →
At the stage where θ ₂ is reached (FIG. 4), the molten metal surface S completely covers the aluminum pipe 21. In this state, the molten metal M flowing into the cavity 19 from the pool 12 does not directly hit the aluminum pipe 21. Therefore, in order to increase the productivity, the rotation speed of the mold 10 is increased and the mold 10 is rotated all at once to the upright state (FIG. 5). In the upright state, the sprue 11 faces vertically upward, and the cavity 1
The molten metal M poured in 9 is pressed by the molten metal H to suppress the formation of cavities.

(Method 2) Mold 1 with integrated basin 12
It is also possible to prevent the molten metal M flowing from the basin 12 from directly contacting the aluminum pipe 21 by rotating the basin 12 separated from the mold 10 instead of rotating 0. For example, as shown in FIG. 6, the mold 10 is obliquely arranged at a predetermined inclination angle θ ₃ , and a rotatable pool 12 is provided to extend obliquely upward from the mold 1.
Bring to 1. The sprue 11 is provided in such a positional relationship that the molten metal M flowing into the cavity 19 is collected from the bottom of the cavity 19 so that the molten metal M does not directly contact the aluminum pipe 21. At the initial stage of injecting the molten metal M, the rotation speed of the molten metal pool 12 is slowed down so that the molten metal M is gradually accumulated in the cavity 19. Then, when the poured molten metal M completely covers the aluminum pipe 21, the rotation speed of the pool 12 is increased, and the remaining molten metal M is poured into the cavity 19 all at once. After the molten metal M for one time is injected, the mold 10 is rotated to exert the pushing effect. Alternatively, as shown in FIG.
In case of providing the sprue 11 without rotating the mold 10.
The molten metal M accumulated in the molten metal turns into the molten metal H and becomes the cavity 1.
The molten metal in 9 is pressurized.

The aluminum pipe 21 which is preset to an aluminum pipe molds 10
Is held by the core 20 and secured at a predetermined position in the cavity 19. The aluminum pipe 21 is cast by the molten metal M and the inside serves as a hydraulic pressure supply passage. There is also a method of directly machining a solid casting to make a hole to manufacture a caliper body, but the machining cost after casting increases the manufacturing cost. In this respect, in the present invention, since the aluminum pipe 21 is made of the aluminum casting alloy forming the caliper body, machining after the casting can be omitted, and the manufacturing cost can be reduced. In general, the aluminum pipe 21 has an outer diameter of 5 to 7 mm and an inner diameter of 2 to 4 mm, and since it is formed into a complicated three-dimensional shape, it is generally a material that is easy to process and has little springback after processing. Required. Therefore, 1000 series, 3000 series, 6 series
000 series etc. (Specifically, A1050, A3003, A
Aluminum alloy of 6063) is used.

Since the aluminum pipe 21 is set in the mold 10 and the molten metal M is injected into the cavity 19, it is required that the heat of the molten metal M does not damage the aluminum pipe 21. Since the melting point of aluminum alloys such as 3000 series and 6000 series is 640 to 660 ° C., a casting alloy having a melting point of 630 ° C. or less is used as the molten metal M. The melting point of the casting alloy can be adjusted by the Si content. Preferably, a casting alloy having a melting point near 615 ° C. is used,
The casting conditions are selected so that the temperature of the molten metal M in the mold 10 is 585 to 645 ° C. Further, in order to prevent the aluminum pipe 21 from being melted and damaged, it is also preferable to cover the aluminum pipe 21 with a heat insulating material such as an anodized film or a release agent.

Heat Treatment A cast caliper body (hereinafter referred to as a blank) has an aluminum pipe 21 cast therein. The base material is subjected to solution treatment after cutting and separating the riser H and the like. By the solution treatment, alloy components such as Si and Mg are solid-solved in the matrix, and the corners of the crystallized eutectic Si are rounded to improve the elongation. The average length of eutectic Si is shorter than that during casting. After the solution treatment, an aging treatment for improving the strength by precipitation of Mg ₂ Si or the like is performed. The heat treatment applied to the base material is a solution treatment (520 to 545).
℃ × 1 to 15 hours) → water quenching → artificial aging (150 to 1)
70 ° C. × 2 to 10 hours) → air-cooled T6 treatment is preferable.
When the solution treatment temperature is lower than 520 ° C., solid solution of Si, Mg, etc. does not proceed sufficiently. On the contrary, if the solution treatment temperature is higher than 545 ° C., not only the effect corresponding to the temperature rise is not obtained but it is not economical, and the dissolution is apt to occur partially. In order to obtain uniform hardenability, the solution-processed base material is 5
It is quenched in water maintained at 0 to 80 ° C. Then, Mg ₂ Si is deposited by heating at 150 to 170 ° C., and strength and elongation are secured. At an aging temperature below 150 ° C., the precipitation of Mg ₂ Si is insufficient,
At an aging temperature exceeding ℃, precipitated particles become large and the strength tends to decrease.

The heat-treated base material is machined and, if necessary, hard anodized. Hard alumite treatment has a film thickness of 30-40, which is effective for improving wear resistance.
An anodic oxide film of about μm is formed on the cylinder surface. The caliper body thus obtained is combined with other parts to be assembled into a disc brake. Since the caliper body has no inclusions that cause fatigue cracks and the crystal grain size is properly adjusted, cracks are generated in the bridge portion 7 even under the condition where the reaction force of the piston 3 is repeatedly applied. Never. Moreover, since it is an integral type, compared to the split type caliper body, steel tightening bolts, nuts, etc. are not required, and the product is lightened accordingly. Also, since the number of machining steps is reduced, it can be provided at a low cost.

[0031]

[Example] A 700 kg aluminum alloy melt having the adjusted composition was subjected to a normal melt treatment such as degassing, refining, and slag removal, and was held at 742 ° C. for 40 minutes in a holding furnace. Alloy 1 according to the invention was refined with Sb and Comparative Alloy 2 was N with a mixed flux of NaF + NaCl.
It was miniaturized by the treatment a. The composition (% by weight) of each prepared alloy is as follows. Inventive alloy 1: Si: 7.0%, Mg: 0.48%, Sb: 0.13%, Ti: 0.16%, B: 0.001%, P: 0.0007%, Ca: 0 0.001%, Na: 0.0001%, Sr: 0.0000%, Fe: 0.11%, Cu: 0.01%, Mn: 0.00%, Cr: 0.00%, Zn: 0. 01%, Sn: 0.00%, Ni: 0.00%, Pb: 0.00% Comparative alloy 2: Si: 7.10%, Mg: 0.49%, Sb: 0.00% Ti: 0 16%, B: 0.001%, P: 0.0008%, Ca: 0.001%, Na: 0.006%, Sr: 0.0000%, Fe: 0.11%, Cu: 0. 01%, Mn: 0.00%, Cr: 0.00%, Zn: 0.01%, Sn: 0.00%, Ni: 0.00%, Pb: 0.00%

As a casting apparatus, an apparatus having an equipment configuration shown in FIG. 2 is used, and an A300 having an outer diameter of 6 mm and an inner diameter of 4 mm is used.
The 3 aluminum alloy pipe 21 was set in the mold 10 in advance. Inventive Alloy 1 and Comparative Alloy 2 10 kg each
Was drawn into a ladle and transferred to the cooling gutter 14. The molten metal M cooled in the cooling gutter 14 passed through the weir 15 and was stored in the molten metal pool 12. In the pool 12, the temperature of the molten metal M is 67.
When the temperature reached 5 ° C., the mold 10 was rotated, and the molten metal M was poured into the cavity 19 so that the molten metal M did not directly hit the aluminum pipe 21. The surface S of the molten metal M poured into the mold 10 gradually rises from the bottom of the cavity 19,
The aluminum pipe 21 was completely covered. Specifically, when the mold 10 is rotated at a rotation speed of about 2 degrees / second and the inclination angle reaches 50 degrees 25 seconds after the start of rotation,
The entire aluminum pipe 21 dived under the molten metal surface S. Therefore, the rotation speed of the mold 10 was increased to 8 degrees / second, the mold 10 was made to stand upright (FIG. 5), and the molten metal M in the mold 10 was pressurized with the pushing water H. Casting was completed when 30 seconds passed from the start of rotation of the mold 10.

Next, the cooling of the mold 10 was continued, and when 145 seconds had passed from the start of casting, the product was taken out from the mold 10. Thermometer T inside the mold 10 (Fig. 3) during casting
Was incorporated, and the temperature change of the molten metal M during the period from the start of pouring to the completion of casting was investigated. The temperature of the molten metal M in the cooling trough 14 and the pool 12 was also measured in the same manner.
As can be seen from the investigation result of FIG. 7, the molten metal M transferred from the holding furnace is efficiently cooled in the cooling gutter 14 and is cooled to an optimum temperature of 640 to 700 ° C. in a relatively short time. You can see that

In the present embodiment, the aluminum pipe 21 was cast into the molten metal M poured into the cavity 19 without being cooled by the vacuum suction method. In order to investigate the thermal effect of the molten metal M on the aluminum pipe 21, a thermometer T was installed at a position 1 mm near the aluminum pipe 21 and the temperature of the molten metal M near the aluminum pipe 21 was detected. The temperature of the molten metal M indicated by the thermometer T was only 620 ° C. at maximum, which was sufficiently lower than the melting point of about 655 ° C. of the A3003 aluminum alloy used for the aluminum pipe 21. Therefore, when the aluminum pipe 21 that was cut and cast around the molded body obtained after casting was investigated, no damage due to melting loss was detected, and it was found that it can be sufficiently used as a hydraulic circuit.

The above casting was repeated 7 times using the alloy 1 of the present invention and the comparative alloy 2. A test piece was cut out from the center of each of the obtained raw materials, and the microstructure, mechanical properties and distribution of inclusions were investigated. In the microstructure observation, DAS was measured and the observation result was image-processed to obtain the average length of eutectic Si. In the investigation of the distribution of inclusions, a notch was cut into a long thick plate having a height of 0.5 cm and a length of 5 cm cut out from the form, and the sample was broken with the naked eye and a 10 times magnifying glass to measure 0.5 cm × 5 cm for 10 cm. The fractured surfaces (two surfaces) were observed, the number of inclusions was counted, and the K ₁₀ value was calculated from the counted number. Most of the inclusions are oxide-based, 0.1-3 m
Inclusions of about m had a blackish color tone.

As can be seen from the examination results in Table 1, the eutectic Si in the alloy 1 of the present invention has an average length of 10 μm or less, but is larger than that of the comparative alloy 2.
The difference in the average length of the eutectic Si is due to the fact that the alloy 1 of the present invention is refined with Sb, whereas the comparative example 2 is refined with Na. Therefore, the alloy 1 of the present invention
Exhibits better wear resistance than Comparative Alloy 2. The comparative alloy 2 has much more inclusions than the alloy 1 of the present invention. The fact that a large amount of inclusions are dispersed in Comparative Alloy 2 means that Na used as the refining treatment material is oxidized,
It is caused by the fact that it is caught in the molten metal as an oxide film and its separation is difficult. The inclusion of oxides generated in the process of the molten metal flowing into the mold is also a cause of the large amount of inclusions being distributed. On the other hand, in the alloy 1 of the present invention, since Sb, which is difficult to be oxidized, is used as the refinement treatment material, the dispersion of inclusions is greatly suppressed. DAS is
The value is determined by the alloy system and the cooling rate. Since both of them adopt the same condition, they show almost the same value of 50 μm or less.

[0037]

Next, the T6 treatment (solution treatment 53) is applied to each material.
5 ° C. × 6 hours → water quenching → left at room temperature for 6 hours → artificial aging 155 ° C. × 5 hours). A sample was cut out from the raw material after the heat treatment, and the tensile strength, 0.2% proof stress, elongation and fatigue strength were measured by a Clause type rotary bending fatigue tester.
In the Clause type rotary bending fatigue test, the test piece is 120 N /
A stress of mm ² was applied, and the number of rotations until breakage was obtained.
As can be seen from the survey results in Table 3, the average elongation of the comparative examples is about 7.4%, whereas the inventive examples show a high average elongation of about 12% as shown in Table 2. Was there. From this, it is understood that the product of the present invention is excellent in toughness and impact load. Regarding the fatigue characteristics, the product of the present invention exhibits higher fatigue strength than the comparative example, and can be said to be a material suitable for a caliper body. The cause of such a large difference in fatigue strength is due to the dispersed state of inclusions and the size of eutectic Si. That is, in Comparative Alloy 2, a large amount of inclusions that cause fatigue cracks are dispersed and Na
Since the eutectic Si is shortened to such an extent that crack propagation cannot be prevented by the treatment, it exhibits low fatigue strength. On the other hand, in the product of the present invention, the area of 25 cm ² is 0.14
The number of inclusions (0.0057 / cm ^{2 in} terms of conversion) was only observed, and the small amount of inclusions exhibited excellent fatigue strength.

[0039]

[0040]

Further, in order to investigate the influence of the molten metal holding temperature in the melting furnace on the structure and mechanical properties of the product, the alloy 1 of the present invention was held in the holding furnace at 680 ° C. for 40 minutes and then cast in the same manner. Table 4 shows the cast structure, inclusions, and mechanical properties of the obtained product after T6 treatment. Table 4 shows the number of inclusions.
It was a large value as seen in. This is 680 ℃
In the case of holding treatment at a low holding temperature, although it is refined with Sb, inclusions during melting and oxides during melting are not sufficiently floated and separated from the molten metal and brought into the product. It shows that it was done. Moreover, coarse Mg—Sb-based crystallized substances were also observed, and it is considered that the elongation was also reduced by this.

[0042]

[0043]

As described above, in the method for producing a caliper body of the present invention, Sb, which is not easily oxidized, is used as a refinement treatment agent as an additive of the aluminum alloy used, and is mixed in the molten metal. By separating the apt oxide from the molten metal by a temperature-controlled holding treatment,
The inclusions that cause the occurrence of fatigue cracks are reduced and the form of eutectic Si is controlled. Since the cast body thus obtained exhibits excellent fatigue characteristics and mechanical properties, it is used as an integrated caliper body in which no fatigue cracks occur in the bridge portion.

[Brief description of drawings]

FIG. 1 is a sectional view of an integrated caliper body.

FIG. 2 is an explanatory view of a casting method according to the present invention.

FIG. 3 is a diagram showing a state in which the mold is rotated.

FIG. 4 is a view showing a state in which an aluminum pipe is covered with molten metal.

[Fig. 5] A view of the mold upright.

FIG. 6 is a view showing an apparatus in which a mold is fixed and a basin is rotatable.

FIG. 7 is a graph showing the temperature change of the molten metal in the example of the present invention.

[Explanation of symbols]

1: Rotor 2: Caliper body 3: Piston
4: Brake pad 5: Pipe 6: Cylinder 7: Bridge part 10: Mold 11: Gate 12: Hot water pool 13:
Ladle 14: Cooling gutter 15: Weir 16: Outlet 17: Supply gutter 18: Insulation material 19: Cavity 20: Core 21: Aluminum pipe M: Molten metal 0: Rotation center S: Hot water level H: Hot water T: Temperature Total

Front page continued (72) Inventor Kaoru Sugita 2-20 Higashi-Shinagawa, Shinagawa-ku, Tokyo Within Nihon Light Metal Co., Ltd. (72) In-house Akio Hashimoto 1-34-1, Kambara, Anbara-gun, Shizuoka Japan Light Metal Co., Ltd. In the Group Technology Center (56) Reference JP-A-5-293626 (JP, A) JP-A-64-39339 (JP, A) JP-A-2-38545 (JP, A) JP-A-10 -110231 (JP, A) JP 9-209069 (JP, A) JP 4-218634 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16D 65/02 C22C 21/02 C22F 1/043

Claims (10)

(57) [Claims] 1. Pressing against a rotor via a brake pad
Aluminum pie that sends hydraulic pressure to the piston that can be kicked
Is shaped into a caliper body shape
Set in a metal mold and Si: 5 to 11% by weight, M
g: 0.25 to 0.7% by weight, Sb: 0.08 to 0.2
0% by weight, with the balance substantially Al composition,
The element contained as a pure substance is P: 0.002% by weight or less,
Ca: 0.002% by weight or less, Na: 0.001% by weight
Below, Sr: 0.001 wt% or less, Fe: 0.3 wt%
% Or less, other impurity elements: 0.5% by weight or less in total
Regulated molten aluminum alloy is degassed, slag and fine
After the thinning process, hold in a holding furnace at 700-760 ° C,
Transfer the required amount of molten metal for one casting to the pool,
After adjusting the molten metal temperature at 640 to 700 ° C.,
Aluminum pipe, which is a cast material, was set
After pouring the molten metal into the mold and casting, the average length of eutectic Si
10μm or less, 50 dendrite arm spacing
μm or less, average number of inclusions at K 10 value is 0.01 / c
Disc breaker having a metal structure adjusted to m 2 or less
Manufacturing method of aluminum integrated caliper body for g. 2. Pressing against a rotor via a brake pad
Aluminum pie that sends hydraulic pressure to the piston that can be kicked
Is shaped into a caliper body shape
Set in a metal mold and Si: 5 to 11% by weight, M
g: 0.25 to 0.7% by weight, Sb: 0.08 to 0.2
0% by weight, Ti: 0.05 to 0.3% by weight and
And / or B: 0.0001 to 0.01% by weight, the balance
Part has a composition of Al substantially and is included as an impurity
Element is P: 0.002 wt% or less, Ca: 0.002 wt
% Or less, Na: 0.001% or less by weight, Sr: 0.0
01% by weight or less, Fe: 0.3% by weight or less, other
Pure elements: Aluminum regulated to 0.5 wt% or less in total
After degassing, descaling and refining the molten um alloy,
Required for one casting by holding at 700-760 ℃ in a furnace
Move a certain amount of molten metal to the pool, and set the molten metal temperature in the pool to 64
After adjusting the temperature to 0 to 700 ° C., the
Pour the molten metal into the mold set with the aluminum pipe.
After casting, the average length of eutectic Si is 10 μm or less,
Drite arm spacing is 50 μm or less, inclusions
The average number is adjusted to less than 0.01 / cm 2 at K 10 value
Made of aluminum for disc brakes with different metal texture
Manufacturing method of integrated caliper body. 3. A holding furnace for holding an amount of molten metal required for one casting.
Drawn out and transferred to a cooling gutter connected to the mold basin
The molten metal is supplied to the hot water pool through the hot water and the cooling gutter.
Is the aluminum integrated key for disc brakes described in 2.
Caliper body manufacturing method. 4. The flow rate of the molten metal flowing out to the pool is adjusted.
A cooling gutter provided with a weir and having a heat dissipation structure is used.
Made of aluminum for disc brake according to any of 3
Manufacturing method of integrated caliper body. 5. A basin with a heat insulating material lined is used.
A disc brake according to any one of claims 1 to 4.
Manufacturing method of aluminum integrated caliper body. 6. The molten metal is fed into the cavity of the mold from the pool.
The molten metal surface rises and covers the aluminum pipe.
And then quickly feed the remaining melt into the cavity
The molten metal sent from the pool is made of aluminum
What is claimed in claim 1-5 for preventing direct contact with the pipe.
Aluminum integrated type for disc brakes described there
Manufacturing method of caliper body. 7. The molten metal surface rising in the cavity is
Until the Luminium pipe is covered, send it from the basin.
Prevent the molten metal from coming into direct contact with the aluminum pipe
A mold with an integrated pool or a rotatable pool
While slowly rotating, send the molten metal from the mold to the cavity
7. Aluminum for disc brake according to claim 6
Manufacturing method of integrated caliper body. 8. A pouring gate is provided after pouring molten metal into the cavity.
The position of an upper part is made to work, and a hot water effect is worked.
Aluminum integrated for disc brake according to any one of
Of manufacturing type caliper body. 9. A pipe made of aluminum during the injection of molten metal.
Connect one end to the vacuum system, A by the outside air is sucked other end or al
A method for cooling a luminium pipe according to claim 1.
Aluminum integrated carrier for disc brakes described
Manufacturing method of body. 10. After casting, 520 to 545 ° C. × 1 to 15
Solution heat treatment for a period of time, water quenching, 150-170 ° C x 2
The aging treatment for 10 hours is performed, according to any one of claims 1 to 9.
Aluminum integrated calipers for disc brakes
Manufacturing method of Di.