Brazing method for small gap or interference fit surface

Abstract

The invention discloses a brazing method for a small clearance or interference fit surface, which is used for performing vacuum brazing on a part a and a part b, and comprises the following steps of: 1) processing a matching piece: processing and forming the matching piece according to the structure of the welding end of the part b under the condition of meeting the welding requirement, and making the matching piece and the welding end of the part b have the same material; (2) primary brazing is conducted, specifically, the mating part and the part a are assembled, and then vacuum brazing is conducted; (3) removing the mating part: processing and removing the mating part subjected to primary brazing, and reserving a brazing filler metal layer in a welding gap of the part a; and (4) secondary brazing is conducted, specifically, the part b and the part a with the brazing filler metal layer reserved are assembled, and then vacuum brazing is conducted. According to the brazing method, it is ensured that the welding seam is filled with the brazing filler metal, a brazing groove does not need to be formed in the part, and the welding quality of the part is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of vacuum brazing, in particular to a brazing method for small gap or interference fit surface. Background Art

[0002] During vacuum brazing, a certain gap should be left between the joints of the parts to be welded before welding, and brazing material should be pre-placed in the brazing material groove reserved at one end of the welding gap or inside. When the parts are heated to the welding temperature, the brazing material melts into liquid state, and the liquid brazing material will be sucked into the reserved gap by the capillary action formed by the surface tension, and diffuse with the base material. After cooling, the brazing material solidifies, achieving the welding effect.

[0003] The size of the capillary action during brazing determines the quality of the weld. When welding parts with small gaps or interference fits, the resistance to the flow of liquid brazing material is much greater than the capillary action due to the small welding gap, which results in the brazing material being unable to enter the gap or unable to fill too far in the gap, affecting the welding quality. In addition, when the welding length is long, pre-setting the brazing material at only one end of the weld cannot fill the entire welding surface. At this time, it is necessary to process a brazing material groove inside the weld for pre-setting the brazing material. However, when the structural strength of the parts does not allow for grooving inside the weld, effective welding cannot be performed. Summary of the invention

[0004] In view of the above defects or deficiencies in the prior art, it is desirable to provide a brazing method for small gaps or interference fit surfaces, which ensures that the brazing filler metal fills the weld and does not require a brazing groove to be opened on the parts, thereby ensuring the welding quality of the parts.

[0005] The present invention provides a brazing method for small gap or interference fit surface, which performs vacuum brazing on part a and part b, and is characterized by comprising the following steps:

[0006] 1) Processing of matching parts: According to the structure of the welding end of part b, the matching parts are processed and formed under the condition that the welding requirements are met. The matching parts are made of the same material as the welding end of part b;

[0007] 2) Primary brazing: Assemble the mating parts with part a, and then perform vacuum brazing;

[0008] 3) Removing the mating parts: removing the mating parts after the first brazing, and retaining the brazing material layer in the welding gap of part a;

[0009] 4) Secondary brazing: Assemble part b with part a that retains the brazing material layer, and then perform vacuum brazing.

[0010] Furthermore, the welding end of the part b is easier to process and shape than the welding end of the part a.

[0011] Furthermore, in the step 2), the welding length and direction between the fitting and part a are consistent with the designed welding length and direction between part a and part b.

[0012] Furthermore, in the step 3), when removing the mating parts, remove them cleanly without considering the welding gap. It is only necessary to ensure the assembly gap between parts a and b, and check whether the solder layer on the mating surface of part a after processing is intact. If the solder layer is intact, proceed to the next step, otherwise start over.

[0013] Compared with the prior art, the beneficial effects of the present invention are:

[0014] When the brazing method of the present invention is performed on parts a and b with a small gap or interference fit, the mating parts are processed so that the weld between the mating parts and part a meets the welding requirements, which can effectively avoid the problem that the weld is too small and the brazing material cannot be filled; and when the weld is too long, a brazing groove can be opened on the mating parts to pre-place the brazing material, avoiding the problem that the parts cannot be welded due to the strength requirements and the brazing groove cannot be opened, thereby ensuring that the brazing material effectively fills the weld and the welding quality is guaranteed.

[0015] It should be understood that the contents described in the summary of the invention are not intended to limit the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0017] Figure 1 A flow chart of a brazing method for small gap or interference fit surfaces;

[0018] Figure 2 It is a schematic diagram of the assembly structure of part a and its matching parts;

[0019] Figure 3 It is a schematic diagram of the structure of part a after the mating parts are removed after one brazing;

[0020] Figure 4 It is a schematic diagram of the assembly structure of parts a and b.

[0021] Numbers in the figure: 1. Part a; 2. Part b; 3. Matching part; 4. Pre-set solder; 5. Solder layer. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It should also be noted that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0023] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0024] Please refer to Figure 1 to Figure 4 The embodiment of the present invention provides a brazing method for small gap or interference fit surface, vacuum brazing parts a and b, characterized in that it includes the following steps:

[0025] 1) Processing the matching part 3: Select the part b 2 whose welding end is easier to process and shape, and process and shape the matching part 3 according to the structure of the welding end of the part b 2 while meeting the welding requirements. The material of the matching part 3 is the same as that of the welding end of the part b 2;

[0026] 2) Primary brazing: Assemble the fitting 3 and the part a1, the welding length and direction of the fitting 3 and the part a1 are consistent with the designed welding length and direction of the part a1 and the part b2, and then perform vacuum brazing;

[0027] 3) Removing the mating part 3: remove the mating part 3 after the first brazing, and keep the brazing material layer 5 in the welding gap of the part a1; when removing the mating part 3, remove it completely without considering the welding gap, and only need to ensure the assembly gap between the parts a1 and b2, and check whether the brazing material layer 5 on the mating surface of the part a1 after processing is intact. If the brazing material layer 5 is intact, proceed to the next step, otherwise start over;

[0028] 4) Secondary brazing: Assemble part b with part a that retains the brazing material layer, and then perform vacuum brazing.

[0029] In this embodiment, when processing the fitting 3, the fitting 3 is processed and formed according to the welding end which is easier to process and form, so as to reduce the processing difficulty of the fitting 3. Since the welding gap between the parts a1 and b2 is too small, it is easy to cause the problem of insufficient filling of the solder, so the outer diameter of the formed fitting 3 is smaller than the outer diameter of the part b2, so that the weld gap between the fitting 3 and the part a1 meets the welding requirements, ensuring that the solder fills the weld between the fitting 3 and the part a1. In order to ensure the margin when the fitting 3 is removed, the weld gap between the fitting 3 and the part a1 is taken as the upper limit as possible.

[0030] When vacuum brazing the fitting 3 and the part a 1, the pre-set brazing material 4 is placed between the fitting 3 and the part a 1. Since the fitting 3 or the part a 1 may rotate or shake in the gap during the assembly process, the assumed theoretical 0.05mm single-sided gap may become 0.01mm on one side and 0.09mm on the other side after assembly, resulting in an unsatisfactory welding effect. Therefore, some burrs or nickel foil may be pre-set on the welding fitting surface to support the welding surface, so as to ensure the uniformity of the welding gap and the uniformity of the thickness of the brazing material layer 5.

[0031] After a brazing process, since there is already a brazing material layer 5 on the mating surface of part a 1, there is no need to consider the pre-setting of the brazing material again after the assembly of part b 2 and part a 1. During vacuum brazing, after heating to the brazing temperature, the remaining brazing material layer 5 is remelted to firmly weld part a 1 and part b 2.

[0032] The present invention effectively solves the problem that the welding gap is difficult to control during the brazing process, resulting in poor brazing effect, or the brazing material cannot be effectively pre-set, resulting in incomplete filling of the brazing weld, thereby ensuring the welding quality.

[0033] In the description of this specification, the description of the terms "one embodiment", "some embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0034] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A brazing method for small gap or interference fit surface, vacuum brazing of parts a and b, characterized in that: The steps include: 1) Processing of matching parts: According to the structure of the welding end of part b, the matching parts are processed and formed under the condition that the welding requirements are met. The matching parts are made of the same material as the welding end of part b; 2) Primary brazing: Assemble the mating parts with part a, and then perform vacuum brazing; 3) Removing the mating parts: removing the mating parts after the first brazing, and retaining the brazing material layer in the welding gap of part a; 4) Secondary brazing: Assemble part b with part a that retains the brazing material layer, and then perform vacuum brazing.

2. The brazing method for small gap or interference fit surface according to claim 1, characterized in that: The welding end of the part b is easier to process and shape than the welding end of the part a.

3. The brazing method for small gap or interference fit surface according to claim 1, characterized in that: In the step 2), the welding length and direction between the fitting and part a are consistent with the designed welding length and direction between part a and part b.

4. The brazing method for small gap or interference fit surface according to claim 1, characterized in that: In the step 3), when removing the mating parts, remove them cleanly without considering the welding gap. It is only necessary to ensure the assembly gap between parts a and b, and check whether the solder layer on the mating surface of part a after processing is intact. If the solder layer is intact, proceed to the next step, otherwise start over.

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