A high-speed rail brake pad back plate structure and pulse current welding method thereof

Abstract

The present invention relates to a high-speed rail brake pad backplate structure and a pulse current welding method thereof. A unidirectional pulse current ignites a gradient-distributed high-entropy powder between the brake material and the backplate, forming a fluctuating weld surface. The unidirectional pulse current has a pulse frequency of 1250Hz-25000Hz. The high-entropy powder is composed, by mass percentage, of the following components: 7% titanium powder, 10% carbon powder, 10% titanium diboride powder, 40% copper powder, and 33% iron powder. Advantages include a simple welding method, strong adaptability, a wide parameter adjustment range, a secure connection between the brake material and the backplate after welding, excellent impact resistance, and the ability to adapt to varying connection performance requirements and product quality standards by varying the transition powder composition.

Description

Technical Field

[0001] The present invention relates to the field of high-speed rail brake components, and in particular to a high-speed rail brake pad back plate structure and a pulse current welding method thereof. Background Art

[0002] High-speed rail brake pads are a key component of high-speed rail braking and are directly related to the braking effect of high-speed trains. The backing plate on the brake pad is the main body of the brake pad, providing support for the entire brake pad. It is not only the main assembly of all parts, but also the interface between the brake pad and the brake caliper. Due to the high speed level of high-speed trains, the braking energy is relatively large. During braking, the thermal load between the brake pad and the brake disc is high. The friction block of the brake pad must not only be wear-resistant, high-temperature resistant, and low-noise, but also have to have good thermal conductivity and load balancing between the friction block and the components it is mounted on.

[0003] At present, in the braking system of the disc brake device of high-speed trains, since the brake pad friction block is riveted or riveted to the steel back and the dovetail, there is neither relative rotation nor floating between the friction block and the steel back, resulting in uneven braking pressure exerted by each friction block on the brake disc, unable to obtain the maximum effective friction area, and the thermal load during braking is too large, which reduces the service life of the brake pad. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention proposes a high-speed railway brake pad back plate structure and a pulse current welding method thereof, which has a simple welding method, firm welding and simple process.

[0005] The technical solution of the present invention:

[0006] A high-speed railway brake pad backplate structure and a pulse current welding method thereof use a unidirectional pulse current to ignite a gradient-distributed high-entropy powder between the brake material and the backplate, forming a welding surface with a wave structure.

[0007] The unidirectional pulse current has a pulse frequency of 1250Hz-25000Hz, and its waveform satisfies the following equation: f(x)=x 2 / 3 +(1+x 2 ) 1 / 2*sin(ax), where a is in the range of (-100-2). The high entropy powder is composed of the following components in proportion according to mass percentage: titanium powder (7%-10%), carbon powder (7%-12%), titanium diboride powder (20%-35%), copper powder (30%-40%), and iron powder (30%-40%). The high entropy powder gradient distribution structure is prepared by the following method: titanium powder, carbon powder, titanium diboride powder, and copper powder are mixed in the above proportions, and ball milled in a planetary ball mill at a ball milling speed of 200 rpm-500 rpm, a ball milling time of 60-240 minutes, and an argon environment; titanium powder, carbon powder, titanium diboride powder, and iron powder are mixed in proportions, and ball milled in a planetary ball mill at a ball milling speed of 200 rpm-500 rpm, a ball milling time of 60-240 minutes, and an argon environment; in the preparation process, the high entropy powder is prepared by the following method: titanium powder, carbon powder, titanium diboride powder, and copper powder are mixed in the above proportions, and ball milled in a planetary ball mill at a ball milling speed of 200 rpm-500 rpm, a ball milling time of 60-240 minutes, and an argon environment. During the preparation process, the sintered brake material is first placed in a mold, and then the ball-milled titanium powder, carbon powder, titanium diboride powder, copper powder and high entropy mixed powder are spread on the surface of the brake material with a powder spreading thickness of 0.3mm-0.5mm. The powder is then pressed and configured using a configuration mold with a pressing pressure of 0.1-0.25Mpa. After that, the ball-milled titanium powder, carbon powder, titanium diboride powder and iron powder and high entropy mixed powder are spread on the configuration powder with a spreading thickness of 0.5-0.8mm. Finally, the back plate is placed on the titanium powder, carbon powder, titanium diboride powder and iron powder and high entropy mixed powder.

[0008] The interface profile of the configuration mold satisfies the following equation: (cosine curve equation y=acosx, where the value range of a is (0.1-0.3)). The pulse current welding method, after completing the material laying process, uses a graphite electrode to press the material and uses the current for welding. The pressing pressure is 2.5-5Mpa and the welding time is 20-35 seconds.

[0009] The advantages of the present invention are simple welding method, strong adaptability, large parameter adjustment range, firm connection between the brake material and the back plate after welding, good impact resistance, and the ability to achieve different connection performance requirements and adapt to different product quality standards by changing the transition powder composition. DETAILED DESCRIPTION

[0010] The following is an explanation with reference to specific embodiments:

[0011] Example 1

[0012] A high-speed rail brake pad backplate structure and a pulse current welding method for the same. A unidirectional pulse current ignites a gradient-distributed high-entropy powder between the brake material and the backplate, forming a fluctuating weld surface. The unidirectional pulse current has a pulse frequency of 1250Hz-25000Hz, and its waveform satisfies the following equation: f(x)=x² / 3+(1+x²)¹ / 2*sin(ax), where a is -80. The high-entropy powder is composed, by mass, of the following components: 7% titanium powder, 10% carbon powder, 10% titanium diboride powder, 40% copper powder, and 33% iron powder. The high entropy powder gradient distribution structure is prepared by the following method: titanium powder, carbon powder, titanium diboride powder, and copper powder are mixed in a ratio of 7%, 10%, 10%, 40%, and 33%, and ball milled in a planetary ball mill at a speed of 200 rpm to 500 rpm for 60-240 minutes in an argon atmosphere; titanium powder, carbon powder, titanium diboride powder, and iron powder are mixed in a ratio and ball milled in a planetary ball mill at a speed of 200 rpm to 500 rpm for 60-240 minutes in an argon atmosphere. The atmosphere is argon. During the preparation process, the sintered brake material is first placed in a mold. A ball-milled high-entropy mixture of titanium powder, carbon powder, titanium diboride powder, and copper powder is then applied to the surface of the brake material to a thickness of 0.3mm-0.5mm. The powder is then pressed and configured using a configuration mold at a pressure of 0.1-0.25 MPa. A ball-milled high-entropy mixture of titanium powder, carbon powder, titanium diboride powder, and iron powder is then applied to the configured powder to a thickness of 0.5-0.8mm. Finally, a backing plate is placed on the high-entropy mixture of titanium powder, carbon powder, titanium diboride powder, and iron powder. The interface profile of the configuration mold satisfies the following equation: (cosine curve equation y = acosx, where a is 0.1). In the pulse current welding method, after the material placement process, the material is pressed using a graphite electrode and welded using the current at a pressure of 2.5-5 MPa and a welding time of 20-35 seconds.

Claims

1. A pulse current welding method for a high-speed railway brake pad back plate structure, characterized in that: A unidirectional pulse current is used to ignite the gradient-distributed high-entropy powder between the brake material and the backplate, forming a welding surface with a fluctuating structure. The high-entropy powder is composed of the following components in proportion by mass: titanium powder (7%-10%), carbon powder (7%-12%), titanium diboride powder (20%-35%), copper powder (30%-40%), and iron powder (30%-40%). The unidirectional pulse current has a pulse frequency of 1250Hz-25000Hz, and its waveform satisfies the following equation: f(x)=x 2 / 3 +(1+x 2 ) 1 / 2 *sin(ax), where a is in the range of (-100-2); the high entropy powder gradient distribution structure is prepared by the following method: titanium powder, carbon powder, titanium diboride powder, copper powder, and iron powder are mixed in a ratio of (7%-10%), (7%-12%), (20%-35%), (30%-40%), and (30%-40%), and ball milled using a planetary ball mill at a ball milling speed of 200 rpm-500 rpm, a ball milling time of 60-240 minutes, and an argon atmosphere; in the preparation process, the sintered brake material is first placed in a mold, and then the ball-milled high entropy mixed powder is spread on the surface of the brake material, and the powder spreading thickness is 0 .3mm-0.5mm, and then use a configuration mold to press and shape the powder with a pressing pressure of 0.1-0.25Mpa, and then lay the ball-milled high-entropy mixed powder on the configuration powder with a laying thickness of 0.5-0.8mm, and finally place the backplane on the high-entropy mixed powder; the interface profile of the configuration mold satisfies the following equation: (cosine curve equation y=acosx, where the value range of a is (0.1-0.3)); the pulse current welding method, after completing the material laying process, uses a graphite electrode to press the material, and uses the current for welding, the pressing pressure is 2.5-5Mpa, and the welding time is 20-35 seconds.