Force release device for preventing bottom cracking in 3D printing

Abstract

The utility model discloses a force relief device for preventing bottom cracking in 3D printing, which comprises a two-dimensional collimator, the side inner wall of the two-dimensional collimator is fixedly connected with a plurality of grid walls, the grid walls are regularly distributed, a grid groove is arranged between two adjacent grid walls, the lower surface of the two-dimensional collimator is provided with a force relief groove, and the force relief groove is provided with a plurality of grooves. The force unloading grooves are divided into a transverse group and a longitudinal group, the number of each group is determined according to the size of a part, all the force unloading grooves are distributed at equal intervals or unequal intervals according to the condition of the part, the distance between every two adjacent force unloading grooves is 0.5-20 mm, further, the effect is more obvious when the distance is 1-10 mm, and round wrapping edges are arranged on the edges of the grooving positions of the force unloading grooves. Through the ingenious design of the parts and the force unloading groove, according to the structural characteristics of the parts of the two-dimensional collimator, the structure of the lower allowance part of the bottom is optimized, so that the stress originally released between the parts and the substrate is released at the groove, and the cracking condition of the bottom is effectively reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of 3D printing, in particular to a stress relief device for preventing the bottom from cracking in 3D printing. Background Technique

[0002] Tungsten has excellent absorption and blocking characteristics for X-rays. Therefore, in high-end medical imaging equipment such as CT, tungsten materials are often used in the preparation of key components with high requirements. Among them, the collimator is a core component on the CT, which is used to eliminate the scattered X-rays generated by the Compton effect and can greatly improve the image quality and resolution. At present, the collimator has developed from a one-dimensional collimator to a two-dimensional collimator, and it is difficult to meet the characteristics of high density, thin walls, and micropores of the two-dimensional collimator by traditional manufacturing processes. In recent years, 3D printing technology has developed rapidly, and research on the forming of some metal components with lower melting points such as titanium alloy, aluminum alloy, superalloy, and stainless steel has reached a relatively high level, and it has been successfully applied in the fields of aerospace and medical treatment. In particular, the Selective Laser Melting (SLM) technology has become an alternative method for preparing tungsten products due to its advantages such as short R & D and manufacturing cycle, high material utilization rate, good surface metallurgical quality, and the ability to prepare complex and precise structures. However, tungsten and tungsten alloy materials have the characteristics of high melting point, high brittleness, high viscosity, and high surface tension in the molten state, which are different from the substrate materials. Coupled with the temperature gradient difference in the 3D printing process, and the non-parallel layout of the thin walls of the two-dimensional collimator parts, and the stress change caused by the structure with a certain angle between the thin walls arranged longitudinally and transversely, so the bottom cracking phenomenon often occurs during the 3D printing process.

[0003] Selective Laser Melting (SLM) uses a high-energy laser beam to irradiate the pre-laid metal powder material, directly melting, solidifying, and forming it to obtain a metal part. Usually, a margin is added to the three-dimensional model, and it is directly placed on the virtual printing platform of the 3D printing software, and then the three-dimensional model is sliced and discretized and the scanning path is planned to obtain the path information for controlling the laser beam scanning. Secondly, the computer layer by layer loads the path information, and the laser beam is controlled by a scanning galvanometer to selectively melt the metal powder, and the powder in the area not irradiated by the laser remains loose. After processing one layer, the powder cylinder rises, the forming cylinder lowers the slice layer thickness height, and the scraper scrapes the powder from the powder cylinder onto the forming platform, and the laser melts the newly laid powder and fuses it with the previous layer. However, during the printing process, the bottom cracking phenomenon of the part often occurs due to stress. In order to prevent this phenomenon from occurring, a stress relief groove can be added to the frame of the two-dimensional collimator part and the margin under the internal grid, and the grooved part of the part can be rounded, such as Figure 3As shown, the length and width of the part are 20 - 50 mm. Multiple stress relief grooves are opened at the bottom of each side frame, one every 1 - 10 mm. The internal grids are also grooved at the same position at the bottom, and the grooved parts are rounded to prevent the high-stress material from cracking. Summary of the Invention

[0004] The purpose of the present utility model is to solve at least one of the technical problems existing in the prior art, and to provide a stress relief device for preventing bottom cracking in 3D printing. The process method designed by the present invention only performs process treatment on the lower margin part of the part, which can effectively solve the problem that the bottom of the part is prone to cracking under the influence of internal stress during the 3D printing process of the tungsten alloy material two-dimensional collimator. The previous process method added too much margin at the bottom of the part and cut off the cracked part at the bottom of the part through post-processing. This method reduces the consumption of materials by adding stress relief grooves to the bottom margin part without adding additional margin, and prevents the part from cracking during the process treatment through a smooth transition rounded structure.

[0005] The present utility model also provides a stress relief device for preventing bottom cracking in 3D printing, including: a two-dimensional collimator, the side inner wall of the two-dimensional collimator is fixedly connected with grid walls, there are multiple grid walls and they are regularly distributed, a grid groove is arranged between two adjacent grid walls, the lower surface of the two-dimensional collimator is provided with stress relief grooves, the stress relief grooves are divided into two groups of horizontal and vertical ones, each stress relief groove can be regularly distributed at equal intervals or according to the structure of the part at unequal intervals, and a rounded edge is arranged at the edge of the grooved part of each stress relief groove. Through the above components, with the ingenious design of the stress relief grooves, according to the structural characteristics of the two-dimensional collimator part, the structure of the lower margin part at the bottom is optimized, so that the stress originally released between the part and the base plate is released at the grooved part, effectively reducing the bottom cracking situation.

[0006] For a stress relief device for preventing bottom cracking in 3D printing according to the present utility model, the upper surface of the two-dimensional collimator is square with a side length of 20 - 50 mm, the lower surface of the two-dimensional collimator is square with a side length 1 - 5 mm larger than the upper surface, and the height of the two-dimensional collimator is 8 - 20 mm and the side view of the outer frame is an isosceles trapezoid. Through the above components, determining the size of the two-dimensional collimator is convenient for production and manufacturing and opening stress relief grooves.

[0007] For a stress relief device for preventing bottom cracking in 3D printing according to the present utility model, the grid grooves do not grow vertically upward and the side surfaces are flat inclined surfaces, and each stress relief groove is located between two adjacent grid walls. Through the above components, the part frame and the internal grids are uniformly grooved regularly, so that the overall force of the part is uniform and the structure is stable.

[0008] A stress relief device for preventing bottom cracking in 3D printing according to the present utility model. The distance between two adjacent stress relief grooves is 0.5 - 20 mm. One end of a set of stress relief grooves penetrates the right side of the two-dimensional collimator and extends to the left side of the two-dimensional collimator, and one end of the other set of stress relief grooves penetrates the front side of the two-dimensional collimator and extends to the back side of the two-dimensional collimator. Through the above components, the spacing of the stress relief grooves and the positions where the stress relief grooves are opened are determined, which facilitates the stress relief grooves to release the internal stress of the two-dimensional collimator. At the same time, uniform grooving treatment is carried out on the part border and the internal grid, so that the overall force of the part is uniform and the structure is stable.

[0009] A stress relief device for preventing bottom cracking in 3D printing according to the present utility model. The front view of the stress relief groove is arched. The width of the stress relief groove is 0.2 - 2 mm, the height is 0.4 - 2 mm, and the height shall not exceed the additional allowance added to the bottom of the part. The radius of the semi-circle is half of the width of the stress relief groove. Through the above components, the shape and size of the stress relief groove can be determined, so that the stress relief groove can effectively release the internal stress and reduce the cracking of the part. At the same time, the part does not need to add too much allowance, reducing the material loss, shortening the printing time, and improving the printing efficiency.

[0010] A stress relief device for preventing bottom cracking in 3D printing according to the present utility model. The wall thickness of the grid wall is 0.1 - 0.3 mm, and the radius of the rounded edge is less than half of the wall thickness of the grid wall. Through the above components, the wall thickness of the grid wall and the radius of the rounded edge can be determined. At the same time, the edge part of the grooved part is rounded, making the transition of the grooved part of the part smooth and preventing the occurrence of cracking at the edge of the stress relief groove.

[0011] Beneficial effects: Before using this process method, due to excessive stress on the bottom, cracking occurred at the connection between the bottom of the part and the substrate. Therefore, too much allowance was often added to compensate for the warping of the part caused by cracking. And during the printing process, cracking at the bottom of the part led to unstable printing, resulting in poor forming performance of the part, defects in the finished part, deviation in part size, and poor consistency in printing the same part. After using this process method, due to the release of internal stress through the stress relief groove structure, the cracking of the part is greatly reduced, the part does not need to add too much allowance, greatly reducing the material loss, shortening the printing time, and improving the printing efficiency. Description of the Drawings

[0012] The present utility model will be further described below in conjunction with the drawings and embodiments;

[0013] Figure 1 It is the overall structure diagram of the stress relief device for preventing bottom cracking in 3D printing according to the present utility model;

[0014] Figure 2 It is the partial structure diagram A of the stress relief device for preventing bottom cracking in 3D printing according to the present utility model;

[0015] Figure 3 This is a top view structure diagram of the force relief device for preventing bottom cracking in 3D printing of the present utility model.

[0016] Legend:

[0017] 1. Two-dimensional collimator; 2. Grille wall; 3. Grille groove; 4. Force relief groove; 5. Rounding edge. Specific implementation manner

[0018] This part will describe in detail the specific embodiments of the present utility model. The preferred embodiments of the present utility model are shown in the drawings. The function of the drawings is to supplement the description of the text part of the specification, enabling people to intuitively and vividly understand each technical feature and the overall technical solution of the present utility model, but it cannot be understood as a limitation on the protection scope of the present utility model.

[0019] Referring to Figures 1-3 , an embodiment of the present utility model provides a force relief device for preventing bottom cracking in 3D printing, which includes: a two-dimensional collimator 1. The upper surface of the two-dimensional collimator 1 is square with a side length of 29 mm, the lower surface of the two-dimensional collimator 1 is square with a side length of 30 mm, and the height of the two-dimensional collimator 1 is 10 mm and the side view of the outer frame is an isosceles trapezoid. The product printed by 3D printing has the function of adjusting the beam direction and size. The side inner wall of the two-dimensional collimator 1 is fixedly connected with a grille wall 2, and a grille groove 3 can be formed in the middle of the two-dimensional collimator 1. There are multiple grille walls 2 and they are regularly distributed. The grille grooves 3 do not grow vertically upward and are arranged at a certain angle. The wall thickness of the grille wall 2 is 0.15 mm. Each force relief groove 4 is located between two adjacent grille walls 2, and a grille groove 3 is provided between two adjacent grille walls 2, which reduces the weight of the printed product and the cost of materials required during production. The lower surface of the two-dimensional collimator 1 is provided with force relief grooves 4. There are two groups of force relief grooves 4, namely horizontal and vertical, and each group has five. Each force relief groove 4 is equidistantly distributed, and the distance between two adjacent force relief grooves 4 is 5 mm. One end of a group of force relief grooves 4 penetrates the right side surface of the two-dimensional collimator 1 and extends to the left side surface of the two-dimensional collimator 1, and one end of the other group of force relief grooves 4 penetrates the front surface of the two-dimensional collimator 1 and extends to the back surface of the two-dimensional collimator 1. The front view of the force relief groove 4 is arched. The width of the force relief groove 4 is 0.3 mm, the height is 0.6 mm, and the radius of the semi-circle is 0.3 mm. It can release the stress between the part and the base plate, reduce the situation of bottom cracking, and at the same time reduce the remaining materials reserved during the production process, save materials, and can reduce the printing time, improve the printing efficiency. Moreover, both the part border and the internal grille are grooved, making the overall force on the part uniform and the structure stable. The edges of the grooved parts of the force relief grooves 4 are all provided with rounding edges 5, and the radius of the rounding edge 5 is 0.0745 mm, making the transition of the grooved parts of the part smooth and preventing the occurrence of cracking at the edges of the force relief grooves 4 during the printing process.

[0020] Working principle: Use 3D printing to print out the two-dimensional collimator 1. Both the upper and lower surfaces of the two-dimensional collimator 1 are square. The side length of the upper surface is 29 mm, the side length of the lower surface is 30 mm, and the height is 10 mm. Print out the grid wall 2 with a thickness of 0.15 mm in the two-dimensional collimator 1. At the same time, leave the same distance between adjacent two grid walls 2 to form the grid groove 3. Then, open 5 unloading grooves 4 at the bottom of each border of the two-dimensional collimator 1. At the same time, perform grooving treatment on the grid wall 2 on the same horizontal line where the unloading groove 4 is opened. The shape of the unloading groove 4 is arched, with a width of 0.3 mm, a height of 0.6 mm, and a semi-circular radius of 0.3 mm. At the same time, round the edges of the grooved part, and the radius of the rounded edge is 0.0745 mm.

[0021] The above has described the embodiments of the present invention in detail with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the purpose of the present invention.

Claims

1. A force relief device for preventing bottom cracking in 3D printing, characterized in that, Including: A two-dimensional collimator (1), on the inner side wall of which a grid wall (2) is fixedly connected. There are multiple grid walls (2) which are regularly distributed. A grid groove (3) is arranged between two adjacent grid walls (2). A stress relief groove (4) is arranged on the lower surface of the two-dimensional collimator (1). The stress relief groove (4) is divided into two groups, namely a horizontal group and a vertical group. Each stress relief groove (4) can be regularly distributed at equal intervals or at unequal intervals according to the structure of the part. A rounded edge (5) is arranged on the edge of the opening of each stress relief groove (4).

2. The force-relieving device for preventing bottom cracking in 3D printing according to claim 1, wherein, The upper surface of the two-dimensional collimator (1) is square with a side length of 20 - 50 mm, the lower surface of the two-dimensional collimator (1) is square with a side length 1 - 5 mm larger than the upper surface, and the height of the two-dimensional collimator (1) is 8 - 20 mm and the side view of its outer frame is an isosceles trapezoid.

3. A force relief device for preventing bottom cracking in 3D printing according to claim 1, characterized in that, All the grid grooves (3) do not grow vertically upward and their sides are flat inclined planes. Each stress relief groove (4) is located between two adjacent grid walls (2).

4. A force relief device for preventing bottom cracking in 3D printing according to claim 1, characterized in that, The distance between two adjacent stress relief grooves (4) is 0.5 - 20 mm. One end of a group of stress relief grooves (4) penetrates the right side surface of the two-dimensional collimator (1) and extends to the left side surface of the two-dimensional collimator (1), and one end of the other group of stress relief grooves (4) penetrates the front surface of the two-dimensional collimator (1) and extends to the back surface of the two-dimensional collimator (1).

5. A force relief device for preventing bottom cracking in 3D printing according to claim 1, characterized in that, The stress relief groove (4) is arched when viewed from the front. The width of the stress relief groove (4) is 0.2 - 2 mm, the height is 0.4 - 2 mm, and the height shall not exceed the allowance added to the bottom of the part. The radius of the semi-circle is half of the width of the stress relief groove.

6. A force relief device for preventing bottom cracking in 3D printing according to claim 1, characterized in that, The wall thickness of the grid wall (2) is 0.1 - 0.3 mm, and the radius of the rounded edge (5) is less than half of the wall thickness of the grid wall.

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