Preparation method of ventilated powder metallurgy brake disc

Abstract

The invention relates to a preparation method of a ventilated powder metallurgy brake disc, which comprises the following steps of: preparing a ventilated powder metallurgy brake disc sintered blank with a heat dissipation channel in any shape by using a disc blank overlapping and pressure sintering mode, and then filling soluble solid powder which is calculated in advance in the heat dissipation channel by using a filling mode, so as to prepare the ventilated powder metallurgy brake disc. Due to the existence of the soluble solid powder, it can be guaranteed that the disc body cannot collapse or deform in the hot-press shaping process, the soluble solid powder can be easily removed by placing the brake disc in a dissolving medium after hot-press shaping, and therefore low-cost preparation of the ventilated powder metallurgy brake disc with the heat dissipation channels in various shapes is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of brake disc preparation, in particular to a method for preparing a ventilated powder metallurgy brake disc. Background Art

[0002] Aluminum-based composite materials have attracted extensive attention due to their low density, high strength, high hardness and excellent wear resistance. Aluminum-based brake discs can reduce weight by 40% to 65% compared to traditional cast iron brake discs, with a significant lightweight effect. A large number of studies and applications have been conducted in the fields of rail transit and passenger car brake discs.

[0003] At present, the preparation methods of aluminum-based composite brake discs include stirring casting, powder metallurgy, melt infiltration, spray deposition, etc. Due to the complex working conditions of automobile brake discs and high braking temperatures, it is necessary to select medium and high volume fraction aluminum-based composite materials for use in automobile brake discs to improve the temperature resistance of aluminum-based brake discs. The aluminum-based composite materials prepared by stirring casting have limited content and insufficient temperature resistance; the melt infiltration method can only prepare aluminum-based composite materials with a high overall ceramic content, which is difficult to process; the powder metallurgy method is relatively flexible and can locally strengthen the brake disc, specifically increase the ceramic content of the friction ring, and significantly improve the temperature resistance of the brake disc.

[0004] However, the traditional powder metallurgy method can only make holes vertically and cannot produce transverse ventilation channels, which limits the ventilation and heat dissipation capabilities of ceramic reinforced aluminum-based composite brake discs, causing ceramic reinforced aluminum-based composite brake discs to face more severe high-temperature working conditions. At the same time, the inability to produce transverse ventilation channels also reduces the lightweight effect of the brake disc, affecting the promotion and application of ceramic reinforced aluminum-based composite brake discs.

[0005] CN115045932B discloses a method for preparing a ventilated brake disc, which is to overlap a first disc blank with a second disc blank, so that the corresponding grooves enclose a ventilation channel, and then perform hot pressing and sintering, and then insert a support sleeve into the ventilation channel and perform densification, and by selecting an aluminum tube as a support sleeve outside a steel rod, applying high-temperature lubricating oil between the aluminum tube and the steel rod, and then calculating the outer diameter of the support sleeve according to a calculation formula, the steel rod can be easily removed after the densification treatment, and the aluminum tube can be removed by machining or retained in the ventilation channel according to the situation, thereby realizing the preparation of a ventilated brake disc with a transverse ventilation channel by a powder metallurgy method. However, this technical solution can only be used to prepare ventilation channels distributed in a straight line, and it is difficult to prepare ventilation channels distributed in an arc. Summary of the invention

[0006] Based on this, it is necessary to provide a method for preparing a ventilated powder metallurgy brake disc that can prepare various types of heat dissipation channels.

[0007] A method for preparing a ventilated powder metallurgy brake disc comprises the following steps:

[0008] A first disk blank and a second disk blank are provided, wherein the first disk blank comprises an integrally formed end portion, a neck portion extending axially along the end portion, and a disk portion extending radially along the neck portion, a surface of the disk portion facing away from the end portion is uniformly provided with a plurality of protrusions, and the second disk blank is mirror-symmetrical to the disk portion;

[0009] The first disk blank is overlapped with the second disk blank so that the protrusions of the disk portion contact with the protrusions of the second disk blank in a one-to-one correspondence, and the contacting parts are pressurized and sintered to obtain a sintered blank with an open outer diameter and a closed inner diameter;

[0010] Providing a closed aluminum housing with a feed port and a soluble solid powder;

[0011] After the outer diameter of the sintered blank is sealed by the sealed aluminum shell, the soluble solid powder is added through the feed port, and the feed port is sealed to obtain a sintered blank filled with the soluble solid powder. The amount of the soluble solid powder added is calculated according to the following formula:

[0012]

[0013] in,

[0014] M is the amount of soluble solid powder added, in g;

[0015] φ1 is the outer diameter of the brake disc to be prepared, in cm;

[0016] φ2 is the inner diameter of the brake disc body to be prepared, in cm;

[0017] φ3 is the equivalent diameter of the brake disc connector to be prepared, in cm;

[0018] n is the number of connectors;

[0019] H is the height of the ventilation channel of the brake disc to be prepared, in cm;

[0020] ρ is the compacted density of the soluble solid powder, in g / cm 3 ;

[0021] After hot pressing and shaping the sintered blank filled with soluble solid powder, the closed aluminum shell and the soluble solid powder are removed to obtain the ventilated powder metallurgy brake disc.

[0022] In one of the embodiments, the outer diameter of the brake disc body is 28 cm to 40 cm.

[0023] In one of the embodiments, the inner diameter of the brake disc body to be prepared is 15 cm to 20 cm.

[0024] In one of the embodiments, the equivalent diameter of the brake disc connector to be prepared is 0.5 cm to 1.5 cm.

[0025] In one embodiment, the number of the connecting members is 100 to 300.

[0026] In one of the embodiments, the height of the brake disc ventilation channel to be prepared is 0.5 cm to 2 cm.

[0027] In one embodiment, the thickness of the closed aluminum shell is 0.4 mm to 0.8 mm.

[0028] In one embodiment, the temperature of the hot pressing shaping is 500° C. to 570° C., and the pressure is 100 MPa to 400 MPa.

[0029] In one embodiment, the compaction density of the soluble solid powder under the hot pressing shaping condition is 2.0 g / cm 3 ~2.1g / cm 3 .

[0030] In one embodiment, the soluble solid powder is a neutral water-soluble powder, and the particle size of the neutral water-soluble powder is 200um to 1000um.

[0031] The above-mentioned method for preparing a ventilated powder metallurgy brake disc can realize the preparation of a sintered blank of a ventilated powder metallurgy brake disc having a heat dissipation channel of any shape by means of disc blank superposition and pressure sintering, and then fill the heat dissipation channel with a pre-calculated soluble solid powder by means of filling. The presence of the soluble solid powder can ensure that the disc body will not collapse and deform during the hot pressing process. After the hot pressing process, the brake disc can be placed in a dissolving medium to easily remove the soluble solid powder, thereby realizing the low-cost preparation of ventilated powder metallurgy brake discs having heat dissipation channels of various shapes. DETAILED DESCRIPTION

[0032] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively below, and preferred embodiments of the present invention are provided. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0033] It should be noted that when an element is referred to as being "disposed" on another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be an intermediate element at the same time.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0035] A method for preparing a ventilated powder metallurgy brake disc according to an embodiment of the present invention comprises the following steps S110 to S150:

[0036] S110, providing a first disk blank and a second disk blank.

[0037] The first disk blank includes an integrally formed end, a neck extending axially along the end, and a disk portion extending radially along the neck, and a surface of the disk portion facing away from the end is uniformly provided with a plurality of protrusions. The second disk blank is mirror-symmetrical to the disk portion.

[0038] It can be understood that the first disc blank and the second disc blank can be obtained by designing corresponding molds according to the ventilated powder metallurgy brake disc to be prepared, and then forming the first disc blank through powder compression molding.

[0039] S120, superimposing the first disk blank and the second disk blank so that the protrusions of the disk portion contact with the protrusions of the second disk blank one by one, and then pressurizing and sintering the contacting portions to obtain a sintered blank with an open outer diameter and a closed inner diameter.

[0040] The pressure sintering temperature is 580°C to 640°C, and the pressure is 5MPa to 10MPa.

[0041] It will be appreciated that pressure is applied at the point of contact.

[0042] Pressurizing and sintering the contact points can make the first disc blank and the second disc blank tightly connected, and the liquid phase generated during the sintering stage can fully diffuse and fuse, offsetting the disadvantage of loose interface due to sintering shrinkage.

[0043] The protrusions on the disc portion are in one-to-one contact with the protrusions on the second disc blank, and after pressure sintering, they become connecting parts for the subsequent ventilated powder metallurgy brake disc.

[0044] S130, providing a closed aluminum shell with a feed port and soluble solid powder.

[0045] It is understood that the soluble solid powder cannot react harmfully with the brake disc during the entire preparation process of the brake disc, and its dissolving medium will not react harmfully with the brake disc either.

[0046] In this embodiment, the soluble solid powder is a neutral water-soluble powder, such as sodium chloride, potassium chloride, etc., and its dissolving medium is water.

[0047] Furthermore, the particle size of the neutral water-soluble powder is 200um to 1000um. If the particle size is too large, the gap between particles during the filling process is too large, making it difficult to ensure that enough particles are filled in, or the brake disc thickness is compressed more under the same filling volume. If the particle size is too small, the particle fluidity becomes poor, and it is also difficult to ensure that enough particles are filled in.

[0048] In this embodiment, the thickness of the closed aluminum shell is 0.4 mm to 0.8 mm. If it is too thin, the shell is easily deformed, resulting in insufficient sealing, and if it is too thick, it affects the material distribution on the outside, resulting in the need to leave more disk processing allowance to ensure that the aluminum shell can be removed in the end.

[0049] S140, after the outer diameter of the sintered blank is sealed by the above-mentioned sealed aluminum shell, soluble solid powder is added through the feed port, and the feed port is sealed to obtain a sintered blank filled with soluble solid powder.

[0050] Among them, the loading amount of soluble solid powder is calculated according to the following formula:

[0051]

[0052] M is the amount of soluble solid powder added, in g;

[0053] is the outer diameter of the brake disc body to be prepared, in cm;

[0054] is the inner diameter of the brake disc body to be prepared, in cm;

[0055] is the equivalent diameter of the brake disc connector to be prepared, in cm;

[0056] n is the number of connectors;

[0057] H is the height of the ventilation channel of the brake disc to be prepared, in cm;

[0058] ρ is the compacted density of the soluble solid powder, in g / cm 3 .

[0059] The loading amount of soluble solid powder is calculated according to the above formula. On the one hand, the loading amount of soluble solid powder can be flexibly designed according to the size of the final product. On the other hand, it can effectively evaluate whether the addition of soluble solid powder meets the requirements during actual operation.

[0060] In this embodiment, the outer diameter of the brake disc body to be prepared is 28cm~40cm, that is, the value range of φ1 is 28~40. The inner diameter of the brake disc body to be prepared is 17cm~25cm, that is, the value range of φ2 is 17~25. The equivalent diameter of the brake disc connector to be prepared is 0.5cm~1.5cm, that is, the value range of φ3 is 0.5~1.5. The number of connectors is 100~300, that is, the value range of n is 100~300, and it is an integer. The height of the ventilation channel of the brake disc to be prepared is 0.5cm~2cm, that is, the value range of H is 0.5~2.

[0061] S150, after hot pressing and shaping the sintered blank containing the soluble solid powder, the closed aluminum shell and the soluble solid powder are removed to obtain a ventilated powder metallurgy brake disc.

[0062] In the present embodiment, the temperature of the hot press shaping is 500° C. to 570° C., and the pressure is 100 MPa to 400 MPa.

[0063] The above-mentioned method for preparing a ventilated powder metallurgy brake disc can realize the preparation of a sintered blank of a ventilated powder metallurgy brake disc having a heat dissipation channel of any shape by means of disc blank superposition and pressure sintering, and then fill the heat dissipation channel with a pre-calculated soluble solid powder by means of filling. The presence of the soluble solid powder can ensure that the disc body will not collapse and deform during the hot pressing process. After the hot pressing process, the brake disc can be placed in a dissolving medium to easily remove the soluble solid powder, thereby realizing the low-cost preparation of ventilated powder metallurgy brake discs having heat dissipation channels of various shapes.

[0064] The following are specific embodiments.

[0065] Example 1

[0066] The ventilated powder metallurgy brake disc is prepared by the method of steps S110 to S150. The ventilated powder metallurgy brake disc has an outer diameter φ1 of 40 cm, an inner diameter φ2 of 20 cm, a height of the ventilation channel of 1 cm, a number of connectors n of 200, an equivalent diameter φ3 of 1 cm, and a soluble solid powder of sodium chloride with a particle size of 300 um. The compacted density of the ventilated powder metallurgy brake disc under hot pressing shaping conditions (hot pressing shaping temperature of 520°C and pressure of 300 MPa) is 2.1 g / cm 3 Based on this, it can be calculated that the amount of sodium chloride added is 1648.5g.

[0067] After testing, the ventilated powder metallurgy brake disc prepared in Example 1 successfully passed the AMS test under extreme working conditions. This technology successfully realizes the preparation of various ventilated brake discs by powder metallurgy, effectively improves the heat dissipation efficiency of the brake disc under high temperature working conditions, especially under long-term high temperature working conditions, and significantly improves the use effect of the brake disc.

[0068] Comparative Examples 1 to 3

[0069] Comparative Examples 1 to 3 are basically the same as Example 1, except that the amount of sodium chloride added in Comparative Examples 1 to 3 can be filled only based on visual judgment. As a result, it is found that during the preparation process of Comparative Examples 1 to 3, some of them are filled too much, resulting in deformation of the closed aluminum shell during hot pressing and shaping, thereby causing the plate body to collapse and deform, and some are added too little, resulting in partial collapse of the plate body during hot pressing and shaping. Comparative Examples 1 to 3 cannot ensure that just enough sodium chloride is added to ensure that the plate body will not collapse and deform during hot pressing and shaping.

[0070] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a ventilated powder metallurgy brake disc, characterized in that: The following steps are involved: A first disk blank and a second disk blank are provided, wherein the first disk blank comprises an integrally formed end portion, a neck portion extending axially along the end portion, and a disk portion extending radially along the neck portion, a surface of the disk portion facing away from the end portion is uniformly provided with a plurality of protrusions, and the second disk blank is mirror-symmetrical to the disk portion; The first disk blank is overlapped with the second disk blank so that the protrusions of the disk portion contact with the protrusions of the second disk blank in a one-to-one correspondence, and the contacting parts are pressurized and sintered to obtain a sintered blank with an open outer diameter and a closed inner diameter; Providing a closed aluminum housing with a feed port and a soluble solid powder; After the outer diameter of the sintered blank is sealed by the sealed aluminum shell, the soluble solid powder is added through the feed port, and the feed port is sealed to obtain a sintered blank filled with the soluble solid powder. The amount of the soluble solid powder added is calculated according to the following formula: in, M is the amount of soluble solid powder added, in g; is the outer diameter of the brake disc body to be prepared, in cm; is the inner diameter of the brake disc body to be prepared, in cm; is the equivalent diameter of the brake disc connector to be prepared, in cm; n is the number of connectors; H is the height of the ventilation channel of the brake disc to be prepared, in cm; ρ is the compacted density of the soluble solid powder, in g / cm 3 ; After hot pressing and shaping the sintered blank containing the soluble solid powder, the closed aluminum shell and the soluble solid powder are removed to obtain the ventilated powder metallurgy brake disc.

2. The method for preparing a ventilated powder metallurgy brake disc according to claim 1, characterized in that: The outer diameter of the brake disc body to be prepared is 28 cm to 40 cm.

3. The method for preparing a ventilated powder metallurgy brake disc according to claim 1, characterized in that: The inner diameter of the brake disc body to be prepared is 15 cm to 20 cm.

4. The method for preparing a ventilated powder metallurgy brake disc according to claim 1, characterized in that: The equivalent diameter of the brake disc connector to be prepared is 0.5 cm to 1.5 cm.

5. The method for preparing a ventilated powder metallurgy brake disc according to claim 1, characterized in that: The number of the connecting pieces is 100 to 300.

6. The method for preparing a ventilated powder metallurgy brake disc according to claim 1, characterized in that: The height of the brake disc ventilation channel to be prepared is 0.5 cm to 2 cm.

7. The method for preparing a ventilated powder metallurgy brake disc according to claim 1, characterized in that: The temperature of the hot pressing shaping is 500° C. to 570° C., and the pressure is 100 MPa to 400 MPa.

8. The method for preparing a ventilated powder metallurgy brake disc according to claim 1, characterized in that: The thickness of the closed aluminum shell is 0.4 mm to 0.8 mm.

9. The method for preparing a ventilated powder metallurgy brake disc according to any one of claims 1 to 8, characterized in that: The compaction density of the soluble solid powder under the hot pressing shaping condition is 2.0 g / cm 3 ~2.1g / cm 3 .

10. The method for preparing a ventilated powder metallurgy brake disc according to claim 9, characterized in that: The soluble solid powder is a neutral water-soluble powder, and the particle size of the neutral water-soluble powder is 200um to 1000um.

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