SLM technology-based sealing cavity bottom-lockable welding powder cleaning hole structure

Abstract

The invention relates to a seal cavity bottom-lockable welding powder cleaning hole structure based on SLM technology, which is composed of a seal cavity (1), an external hole (2), a bottom locking structure (3), a top hole (4) and a lateral hole (5), the external hole (2) is located on the surface of the seal cavity (1), the bottom locking structure (3) is of a tripod-shaped boss structure and located on the inner surface of the seal cavity (1), the top hole (4) is formed in the top of the bottom locking structure (3), and the lateral hole (5) is located in the lateral hole (5). And a plurality of lateral holes (5) are formed in the circumferential direction of the bottom locking structure (3). According to the powder cleaning hole structure, the tripod-shaped boss structure is designed, the weight is extremely small, the normal function of the powder cleaning hole is guaranteed, the lock bottom welding structure form is provided, and the welding seam performance is stable and reliable. And meanwhile, machining is not needed after welding, only redundant craters and welding patch allowance need to be ground off when necessary, and the manufacturability is greatly improved.

Description

Technical Field

[0001] The invention belongs to the field of metal additive manufacturing, and in particular relates to a sealing cavity bottom-lockable welding powder cleaning hole structure which improves sealing performance and structural stability. Background Art

[0002] With the continuous development of industrial technology, the application of selective laser melting (SLM) technology is becoming more and more extensive, and its extremely high degree of design freedom continues to promote innovation in structural design. SLM technology has a significant weight reduction effect on product structures. The common structural form is the internal sandwich or cavity structure, and some products need to ensure the sealing of the internal cavity. SLM technology requires layer-by-layer laying of powder and melting during the printing process, so it is necessary to set up a powder cleaning hole, and the internal cavity cannot be directly made into a sealed structure. At present, the most commonly used is welding technology. In the welding process, lap joints and bottom locking are common welding forms. Welding lap joints are achieved by partially overlapping and welding two metal plates together to achieve a firm connection of the structure. Welding lap joints have the advantages of enhancing structural strength, dispersing stress concentration, and strong adaptability to shape and size. Bottom locking welding is a special welding technology that is widely used in situations where high-strength connections are required. It is formed by placing the end of one weldment on the reserved bottom edge of another weldment to form a butt joint. This type of joint can ensure that the root of the weld can be penetrated and achieve a more reliable connection. However, both of the above methods require the design of bosses inside the powder cleaning holes to meet welding needs. The structural form of the bosses inside the powder cleaning holes will inevitably affect the function of the powder cleaning holes and increase the difficulty of the powder cleaning process. In addition, combined with the advantages of SLM technology, the powder cleaning holes are usually small, and the impact of the internal bosses is more severe on small powder cleaning holes, resulting in the inability to take into account both the powder cleaning function and the high-performance welding form at the same time. Summary of the invention

[0003] The purpose of the present invention is to enhance the welding processability of powder cleaning holes of products manufactured by SLM technology and simplify the post-processing process. The present invention provides a sealed cavity lockable bottom welding powder cleaning hole structure based on SLM technology.

[0004] The technical solution of the present invention is:

[0005] A sealed cavity bottom-lockable welding powder cleaning hole structure based on SLM technology consists of a sealed cavity 1, an external hole 2, a bottom-locking structure 3, a top hole 4 and a lateral hole 5, wherein the external hole 2 is located on the surface of the sealed cavity 1, the bottom-locking structure 3 is a "trip"-shaped boss structure, located on the inner surface of the sealed cavity 1, the top of the bottom-locking structure 3 is provided with a top hole 4, and the bottom-locking structure 3 is provided with a plurality of lateral holes 5 in an annular direction.

[0006] It is characterized in that the sealed cavity 1 is a hollow structure, the internal metal powder needs to be discharged from the sealed cavity 1 after the product is printed, and the external hole 2 on the surface is welded and sealed.

[0007] The characteristic is that the diameter of the external hole 2 is 2mm-5mm.

[0008] The feature of the invention is that the inner side of the lock bottom structure 3 is a cavity, the height of the cavity inside the lock bottom structure 3 is 4 mm, and the wall thickness of the lock bottom structure 3 is 1 mm.

[0009] The characteristic is that the diameter of the inner wall 7 of the bottom lock structure is consistent with the diameter of the external hole 2.

[0010] The characteristic is that the diameter of the outer wall 8 of the lock bottom structure is 7 mm.

[0011] The feature is that the top hole 4 has a diameter of 3 mm, and four lateral holes 5 with a diameter of 3.5 mm are opened in the annular direction at the bottom, so that the top and annular directions of the bottom locking structure 3 are both powder cleaning passages.

[0012] The characteristic is that the top hole 4 is smaller than the diameter of the inner wall 7 of the bottom locking structure, forming a bottom locking welding structure.

[0013] It is characterized in that after the powder cleaning is completed, the welding patch 6 is placed inside the locking bottom structure 3 through the external hole 2. The welding patch 6 is a cylindrical structure. The mating surfaces of the welding patch 6 and the locking bottom structure 3 are chamfered to ensure that the welding patch 6 is stably assembled inside the locking bottom structure 3. In order to avoid the gap between the welding patch 6 and the inner cavity of the locking bottom structure 3, which causes the welding patch 6 to be assembled tilted, the height of the welding patch 6 is greater than the height of the inner cavity of the locking bottom structure 3 by 0.3 mm.

[0014] The advantages of the present invention are:

[0015] The present invention is based on the SLM technology, and the sealing cavity can be welded with the bottom-locked powder cleaning hole structure. It makes full use of the high degree of freedom of the SLM technology structure design, and designs a "tripod"-shaped boss structure. This structure has a very small weight, which not only ensures the normal function of the powder cleaning hole, but also provides a bottom-locked welding structure, and the welding weld performance is stable and reliable. At the same time, it can be realized without processing after welding, and only the excess weld scars and welding patch remainders need to be polished off when necessary, which greatly improves the processability. This structure is very effective for small powder cleaning hole sealing cavity parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Lockable bottom welding powder cleaning hole structure

[0017] Figure 2 Welding patch

[0018] Among them, 1 is the sealing cavity, 2 is the external hole, 3 is the bottom lock structure, 4 is the top hole, and 5 is the side hole.

[0019] 6 welding patch, 7 inner diameter of bottom lock structure, 8 outer diameter of bottom lock structure DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0021] See attached Figure 1 A sealed cavity lockable bottom welding powder cleaning hole structure based on SLM technology consists of a sealed cavity 1, an external hole 2, a bottom lock structure 3, a top hole 4 and a side hole 5, wherein the external hole 2 is located in the sealed cavity 1, and the top hole 4 and the side hole 5 are located in the bottom lock structure 3.

[0022] The sealed cavity 1 is a hollow structure. The metal powder inside needs to be discharged from the structure after the product is printed, and the powder cleaning hole is welded and sealed. The raw material powder of SLM technology is small, and the powder quality needs to be strictly controlled. The powder cleaning hole can usually be selected between Φ2mm-Φ5mm, and the external hole 2 is selected to be Φ5mm to ensure smooth powder cleaning of the structure.

[0023] The bottom lock structure 3 is a "tripod" shaped boss structure, which has a cavity inside. The thickness is recommended to be 0.5mm to 10.0mm, and the wall thickness here is 1mm. The inner wall 7 of the bottom lock structure is the same size as the external hole 2 to avoid the existence of additional steps. The outer wall 8 of the bottom lock structure is 7mm. A Φ3mm top hole 4 is opened at the top of the bottom lock structure 3, and 4 Φ3.5mm side holes 5 are opened along the annular direction at the bottom. In this way, the bottom lock structure 3 is designed to have powder cleaning passages on all sides and on the top.

[0024] The top hole 4 is smaller than the inner wall 7 of the bottom lock structure, forming a bottom lock welding structure. The welding patch 6 is a cylindrical structure, and the mating surface of the welding patch 6 and the bottom lock structure 3 should be chamfered to ensure that the welding patch 6 can be stably assembled inside the bottom lock structure 3. The length of the welding patch 6 should theoretically be consistent with the height of the inner cavity of the bottom lock structure 3. In order to avoid the gap between the welding patch 6 and the inner cavity of the bottom lock structure 3, which leads to the tilted assembly of the welding patch 6, the length of the welding patch 6 is set to be 0.3mm greater than the height of the inner cavity of the bottom lock structure 3. The specific value can be determined according to the actual structural form. At the same time, the side wall of the bottom lock structure 3 forms a welded overlap with the welding patch 6.

[0025] The sealed cavity based on SLM technology of the present invention has a lockable bottom welding powder cleaning hole structure. This structure makes full use of the high degree of freedom in structural design of SLM technology and designs a "trip"-shaped boss structure, which not only ensures the normal function of the powder cleaning hole, but also provides a lock bottom structure. The welding performance of this structure is stable and reliable. At the same time, considering the process modification after welding, a welding patch with almost the same height as the inner cavity of the lock bottom boss structure is designed, which can achieve no processing after welding. It is only necessary to grind off the welding patch excess and excess weld scars when necessary, which greatly improves the processability. Taking aluminum alloy as an example, the lockable bottom welding powder cleaning hole structure in the case of the present invention is only 0.16g.

[0026] Since the raw material powder of SLM technology is small and the powder quality needs to be strictly controlled, the size of the powder cleaning hole to be designed is usually small, which can be selected between Φ2mm-Φ5mm. In particular, considering that the mechanical properties of the material structure in the heat-affected zone will be affected and reduced during welding, the powder cleaning hole should be minimized under the condition of meeting the conditions. The typical case of the present invention uses a Φ5mm powder cleaning hole, and 4 Φ3.5mm lateral holes are opened along the annular direction at the bottom of the lock bottom boss structure. The thickness of the lock bottom boss structure is recommended to be 0.5mm~10.0mm. In this case, a thickness of 1mm is selected. This structure can meet the function of lateral powder cleaning while realizing welding overlap. A Φ3mm circular hole is opened on the top of the lock bottom boss structure. In this way, the lock bottom boss structure is designed to have powder cleaning passages all around and on the top, and a Φ3mm hole is opened on the top to realize lock bottom welding. After actual production powder cleaning testing, the powder cleaning of the sealed cavity structure with this specification of powder cleaning hole is smooth, the powder cleaning cycle is significantly improved compared with the conventional boss form powder cleaning hole efficiency, and the welding processability is good. The gap between the welding patch and the powder cleaning hole can be selected according to the actual welding process. The welding patch should be made of alloy materials of the same grade as the powder or compatible with similar grades. The surface should be cleaned before welding to remove oil and oxides. Rust, bubbles, sand holes, delamination and burrs are not allowed. Chemical cleaning is allowed.

[0027] Place the sealed cavity on a vibration platform, blow compressed air into the powder cleaning hole on one side of the sealed cavity, and the metal powder in the sealed cavity is discharged from other powder cleaning holes. The clamping angle of the sealed cavity needs to be adjusted continuously during the powder cleaning process. After the powder cleaning is completed and passed the inspection, clean the inner cavity of the powder cleaning hole and the welding patch to ensure the welding quality. Put the welding patch into the inner cavity of the powder cleaning hole, use laser welding technology to weld along the circumferential direction of the welding patch, and form a firm connection between the welding patch and the powder cleaning hole. After welding is completed, the weld is post-processed by grinding and polishing to improve the surface quality and aesthetics.

[0028] The diameter of the powder cleaning hole is not limited to the typical case size. When the diameter of the powder cleaning hole is larger and the ratio of the hole diameter to the boss height exceeds 3 times, the powder cleaning requirements can be met by simply smoothly transitioning through the bottom of the boss, without the need for this structural form. The powder cleaning hole with a bottom-locking boss structure involved in the present invention is suitable for small powder cleaning hole sealing cavity parts, and the effect is obvious.

Claims

1. A sealed cavity bottom-lockable welding powder cleaning hole structure based on SLM technology, comprising a sealed cavity (1), an external hole (2), a bottom-locking structure (3), a top hole (4) and a side hole (5), wherein the external hole (2) is located on the surface of the sealed cavity (1), the bottom-locking structure (3) is a "trip"-shaped boss structure, located on the inner surface of the sealed cavity (1), the top of the bottom-locking structure (3) is provided with a top hole (4), and the bottom-locking structure (3) is provided with a plurality of side holes (5) in the circumferential direction.

2. A sealed cavity bottom-lockable welding powder cleaning hole structure based on SLM technology as claimed in claim 1, characterized in that: The sealed cavity (1) is a hollow structure. The internal metal powder needs to be discharged from the sealed cavity (1) after the product is printed, and the external holes (2) on the surface are welded and sealed.

3. A sealed cavity bottom-lockable welding powder cleaning hole structure based on SLM technology as claimed in claim 2, characterized in that: The outer hole (2) has a diameter of 2mm-5mm.

4. A sealed cavity bottom-lockable welding powder cleaning hole structure based on SLM technology as claimed in claim 3, characterized in that: The inner side of the bottom lock structure (3) is a cavity, the height of the cavity inside the bottom lock structure (3) is 4 mm, and the wall thickness of the bottom lock structure (3) is 1 mm.

5. A sealed cavity bottom-lockable welding powder cleaning hole structure based on SLM technology as claimed in claim 4, characterized in that: The diameter of the inner wall (7) of the bottom lock structure is consistent with the diameter of the outer hole (2).

6. A sealed cavity bottom-lockable welding powder cleaning hole structure based on SLM technology as claimed in claim 5, characterized in that: The diameter of the outer wall (8) of the bottom lock structure is 7 mm.

7. A sealed cavity bottom-lockable welding powder cleaning hole structure based on SLM technology as claimed in claim 6, characterized in that: The top hole (4) has a diameter of 3 mm, and four lateral holes (5) with a diameter of 3.5 mm are opened in the annular direction at the bottom, so that the top and the annular direction of the bottom locking structure (3) are both powder cleaning passages.

8. A sealed cavity bottom-lockable welding powder cleaning hole structure based on SLM technology as claimed in claim 7, characterized in that: The top hole (4) is smaller than the diameter of the inner wall (7) of the bottom locking structure, forming a bottom locking welding structure.

9. A sealed cavity bottom-lockable welding powder cleaning hole structure based on SLM technology as claimed in claim 8, characterized in that: After the powder is cleaned, the welding patch (6) is placed inside the locking bottom structure (3) through the external hole (2). The welding patch (6) is a cylindrical structure. The mating surfaces of the welding patch (6) and the locking bottom structure (3) are chamfered to ensure that the welding patch (6) is stably assembled inside the locking bottom structure (3). In order to avoid the welding patch (6) and the inner cavity of the locking bottom structure (3) being matched with each other, thereby causing the welding patch (6) to be assembled tilted, the height of the welding patch (6) is 0.3 mm greater than the height of the inner cavity of the locking bottom structure (3).

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