A method for laser selective melting forming of C-shaped plate-like parts with mounting joints

Abstract

The application relates to a laser selective melting forming method for C-shaped plate parts with mounting joints, and belongs to the field of titanium alloy additive manufacturing, and solves the problems of large deformation and low forming efficiency in the additive manufacturing process of a non-closed rotary structure containing a free end in the prior art. The laser selective melting forming method for C-shaped plate parts with mounting joints comprises the following steps: S1, three-dimensional modeling; S2, setting a placing mode and a support structure: two C-shaped plate parts are placed in a mirror image mode, and a solid support connection is added between the two C-shaped plate parts to form a mirror image symmetrical structure; S3, model processing; S4, laser selective melting forming; S5, powder cleaning; and S6, wire cutting: after the wire cutting separates the parts from the substrate, the integrated two C-shaped plates are segmented into two independent C-shaped plates. The laser selective melting forming of the C-shaped plate parts with complex structures is realized with less support, high dimensional precision and high efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of titanium alloy additive manufacturing, in particular to a laser selective melting forming method for C-shaped plate parts with mounting joints. BACKGROUND

[0002] As a rapidly developing technology in the field of additive manufacturing, laser selective melting forming (SLM) is widely used in the fields of aerospace, automobile, medical treatment and the like due to its high precision. Thin-walled and complex structures can be formed with less excess material through SLM, thereby reducing material loss and shortening processing cycle.

[0003] In the fields of aerospace, automobile and the like, there are many manufacturing requirements for TA15 titanium alloy thin-walled and complex C-shaped plate parts with mounting joints. Since the C-shaped plate parts are not closed rotary structures, there are free ends prone to deformation, and there is a large wall thickness difference between the mounting joint position and other areas. Therefore, directly performing laser selective melting forming on the C-shaped plate part body has a high risk of deformation. It is necessary to increase the support density to prevent deformation and sagging during the forming process.

[0004] Currently, in order to reduce gravitational deformation during the 3D printing process of the C-shaped plate part, the C-shaped plate part is usually placed parallel to the printing platform. The commonly used support method is a grid or dot array structure support. After printing is completed, it is difficult to remove the support, and due to the dense support, the design of the part structure is limited, which is not suitable for the forming process of complex structure parts. SUMMARY

[0005] In view of the above analysis, the embodiments of the present application aim to provide a laser selective melting forming method for C-shaped plate parts with mounting joints, to solve at least one of the problems of large deformation, low forming efficiency, high support material loss and the like in the additive manufacturing process of existing complex structure C-shaped plate parts.

[0006] The embodiments of the present application provide a laser selective melting forming method for C-shaped plate parts with mounting joints, comprising the following steps:

[0007] S1, three-dimensional modeling: a model is established according to the outline of the C-shaped plate part;

[0008] S2, setting the placement mode and support structure: mirror image placement of two C-shaped plate parts, and adding a solid support connection between the two C-shaped plate parts to form a mirror image symmetric structure;

[0009] S3, model processing: slice processing of the two C-shaped plate part models with the set placement mode and solid support;

[0010] S4, laser selective melting forming: the processed model is subjected to laser selective melting forming operation, the laser selective melting forming operation is performed on the substrate, and the two C-shaped plate parts and the support structure are integrally formed, wherein the process parameters of the support structure are the same as those of the part body;

[0011] S5, powder cleaning: after the laser selective melting forming is completed, the C-shaped plate part is taken out from the equipment together with the substrate, the substrate is hoisted, and the powder around the substrate and the part is cleaned;

[0012] S6, wire cutting: after the wire cutting separates the part from the substrate, the integrated two C-shaped plates are further separated to become two independent C-shaped plates.

[0013] Specifically, in step S2, the C-shaped plate part includes a body, a mounting joint and a process clamp; the body is a flat plate structure, including two panels, two bottom surfaces and two side surfaces; the mounting joint is located on the panel of the body, and the process clamp is located on the side surface of the body.

[0014] It should be noted that in step S2, the angle between the panel of the C-shaped plate part and the vertical direction is less than 45°; the mounting joint of the C-shaped plate part faces the symmetry axis of the mirror image symmetry structure;

[0015] Specifically, the solid support includes two solid plate structures.

[0016] The solid plate structure includes two isosceles trapezoidal plate surfaces, an upper base, a lower base and two side edges; the solid plate structure plate surface is perpendicular to the substrate; the lower base of the solid plate structure is connected with the substrate; the two side edges of the solid plate structure are respectively connected with two C-shaped plate panels with mounting joints and are coplanar;

[0017] The two solid plate structures and the two C-shaped plate parts form a prism structure without upper and lower bases.

[0018] Preferably, the solid plate structure is distributed with periodically arranged water drop-shaped holes.

[0019] Further, the support structure further includes a surface support, and the surface support is distributed at the lowest point of the part and the region that does not meet self-forming.

[0020] Illustratively, the C-shaped plate part laser selective melting forming adopts TA15 titanium alloy powder, and the particle size range of the TA15 titanium alloy powder is 15-53 μm.

[0021] Specifically, in step S4, the laser selective melting forming process parameters are: laser power 160-200 W, scanning speed 600-1000 mm / s, scanning interval 0.08-0.12 mm, and powder layer thickness 30-40 μm.

[0022] Further, the deformation control of the C-shaped plate laser selective melting forming process is ±1mm.

[0023] Compared with the prior art, the present application can achieve the following beneficial effects:

[0024] 1. The present application is aimed at the structural characteristics of large-scale, non-closed rotation of C-shaped plate parts with mounting joints. Each part is placed with an angle less than 45° between the panel and the vertical direction, so that most of the area of each C-shaped plate and mounting joint meets the self-forming condition. In order to ensure the structural strength and control the quality of the profile, two C-shaped plate parts are arranged in mirror image symmetry and connected through a solid plate-shaped support structure, which increases the structural strength and stability, avoids deformation of the parts during printing, improves the dimensional accuracy of the profile, and controls the deformation of the forming process within ±1mm. A large amount of support is reduced, and only the lowest point of the part and part of the area that does not meet the self-forming condition need to be added with support structure, reducing the loss of support material.

[0025] 2. The present application adopts the placement form of two C-shaped plate parts arranged in mirror image symmetry and connected through a solid plate-shaped support, which can realize the placement of a single C-shaped plate part with an angle less than 45° between the vertical direction. Compared with the placement of plate parts in the prior art 3D printing parallel to the printing platform, the forming area of a single part is reduced by more than 25%, greatly improving the utilization rate of the printing platform and thus the forming efficiency.

[0026] 3. The present application designs periodic water droplet-shaped holes on the solid plate-shaped support structure connecting the two C-shaped plate parts, which does not affect the support strength while further reducing material loss.

[0027] 4. The present application forms two C-shaped plates at a time, which on the one hand reduces the addition of support structure and improves material utilization, and on the other hand reduces the forming area of a single C-shaped plate, realizes the placement of more parts on the substrate, and improves the forming efficiency.

[0028] In the present application, the above technical solutions can be combined with each other to realize more preferred combination schemes. Other features and advantages of the present application will be described in the subsequent specification, and some advantages will become apparent from the specification or be understood through the implementation of the present application. The purpose and other advantages of the present application can be achieved and obtained through the specific indications in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0029] The accompanying drawings are included to provide a further understanding of the application and are incorporated herein and constitute a part of the application. The drawings illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0030] Figure 1A three-dimensional structural schematic view of a TA15 titanium alloy C-shaped plate part with a mounting joint in an embodiment of the present application (excluding a process clamp);

[0031] Figure 2 A front view of a TA15 titanium alloy C-shaped plate part with a mounting joint in an embodiment of the present application;

[0032] Figure 3 A left view of a TA15 titanium alloy C-shaped plate part with a mounting joint in an embodiment of the present application;

[0033] Figure 4 A three-dimensional structural schematic view of a two-piece TA15 titanium alloy C-shaped plate part with a mounting joint in an embodiment of the present application with an added solid support;

[0034] Figure 5 A front view of a two-piece TA15 titanium alloy C-shaped plate part with a mounting joint in an embodiment of the present application with an added solid support;

[0035] Figure 6 A yz plane cross-sectional view of a two-piece TA15 titanium alloy C-shaped plate part with a mounting joint in an embodiment of the present application with an added solid support;

[0036] Figure 7 A top view of a two-piece TA15 titanium alloy C-shaped plate part with a mounting joint in an embodiment of the present application with an added solid support;

[0037] Figure 8 A partial cross-sectional view of a mounting joint portion of a two-piece TA15 titanium alloy C-shaped plate part with a mounting joint in an embodiment of the present application with an added solid support;

[0038] Figure 9 A coordinate system schematic view of a TA15 titanium alloy C-shaped plate part with a mounting joint in an embodiment of the present application.

[0039] Reference signs:

[0040] 1 - a solid plate structure support connecting two C-shaped plates; 2 - a solid support of a non-self-forming area in a C-shaped plate; 201 - a surface support of a non-self-forming area at a machining process clamp of a C-shaped plate; 202 - a surface support of a non-self-forming area at a mounting joint of a C-shaped plate; 203 - a surface support of a non-self-forming area at a lowest point of a C-shaped plate; 3 - a machining process clamp of a C-shaped plate; 4 - a mounting joint; 5 - a C-shaped plate body; 501 - a surface plate of a C-shaped plate body; 502 - a bottom surface of a C-shaped plate body; 503 - a side surface of a C-shaped plate body. DETAILED DESCRIPTION

[0041] The preferred embodiments of the present application will be described in detail below with reference to the drawings, wherein the drawings constitute a part of this application, and are used to explain the principles of the embodiments of the present application, but not to limit the scope of the present application.

[0042] The C-shaped plate part forming process includes a body 5, a mounting joint 4 and a process clamp 3; the body is a flat plate structure, including two face plates 501, two bottom surfaces 502 and two side surfaces 503; the mounting joint 4 is located on the body face plate 501, and the process clamp 3 is located on the body side surface 503.

[0043] The C-shaped plate part face plate 3D printing process usually needs to set dense entity supports, and the setting of the dense supports will limit the design of the complex structures such as the mounting joint and the process clamp on the C-shaped plate part face plate; and due to the setting of the mounting joint and the process clamp and other suspended structures prone to deformation or sagging on the face plate, the geometric discontinuity of the entity support is easy to appear, and the stress concentration is easy to occur.

[0044] At present, in order to reduce the gravity deformation in the 3D printing process of the C-shaped plate part, the C-shaped plate part is usually placed parallel to the printing platform, and the commonly used support method is the grid or dot array structure support. When this method is used, the grid or dot array structure support is difficult to remove after printing, and due to the dense support, the design of the part structure is limited, and the method is not suitable for the forming process of the complex structure part, especially not suitable for the 3D printing forming of the large-area C-shaped plate part with the mounting joint.

[0045] Based on this, the embodiment of the present application discloses a laser selective melting forming method of a C-shaped plate part with a mounting joint, including the following steps:

[0046] S1, three-dimensional modeling: a model is established according to the outline of the C-shaped plate part;

[0047] S2, setting the placing mode and the support structure: the two C-shaped plate parts are placed in mirror image, and entity support connection is added between the two C-shaped plate parts to form a mirror image symmetric structure;

[0048] S3, model processing: the two C-shaped plate part models with the set placing mode and entity support are subjected to slicing processing;

[0049] S4, laser selective melting forming: the two C-shaped plate parts and the support structure are integrally formed on the substrate, wherein the process parameters of the support structure are the same as those of the part body;

[0050] S5, powder cleaning: after the laser selective melting forming is completed, the C-shaped plate part is taken off from the equipment together with the substrate, the substrate is hoisted, and the powder around the substrate and the part is cleaned;

[0051] S6, linear cutting: after separating the part from the substrate by linear cutting, the integrated two C-shaped plates are divided into two independent C-shaped plates.

[0052] Compared with the method of using a grid or dot matrix structure support in the 3D printing process of the C-shaped plate part placed parallel to the printing platform in the prior art, the placement method and support scheme of the application reduce the forming area by more than 25%, improve the utilization rate of the printing platform and the forming efficiency, and the support structure is easy to remove, shortening the post-processing time.

[0053] Specifically, in step S2, the C-shaped plate part includes a body, a mounting connector and a process chuck; the body is a flat plate structure, including two panels, two bottom surfaces and two side surfaces; the mounting connector is located on the panel of the body, and the process chuck is located on the side surface of the body.

[0054] The mounting connector is a rectangular cylindrical structure, located at the center of the panel on one side of the body, and the four walls of the mounting connector cylindrical body are perpendicular to the panel of the body.

[0055] The process chuck is a rectangular structure, located on the side surface of the body, and the height direction of the rectangular body of the process chuck is perpendicular to the panel of the body.

[0056] In the 3D printing process of the panel of the C-shaped plate part, dense solid supports usually need to be set; and due to the suspended structure of the mounting connector and the process chuck and other structures on the panel which are prone to deformation or sagging in the printing process, the geometric discontinuity of the solid support is easy to cause stress concentration.

[0057] It should be noted that in step S2, the angle between the panel of the C-shaped plate part and the vertical direction is less than 45°; and the mounting connector of the C-shaped plate part is directed to the symmetry axis of the mirror image symmetry structure.

[0058] Specifically, the solid support includes two solid plate structures.

[0059] The solid plate structure includes two isosceles trapezoidal plate surfaces, an upper base, a lower base and two side edges; the plate surface of the solid plate structure is perpendicular to the substrate; the lower base of the solid plate structure is connected to the substrate; and the two side edges of the solid plate structure are respectively connected to the two C-shaped plate panels with the mounting connector and coplanar.

[0060] The two solid plate structures and the two C-shaped plate parts form a prism structure without upper and lower bases.

[0061] The symmetry of the prism structure helps to uniformly distribute the load, reduce structural deformation and increase structural stability.

[0062] The thickness of the solid plate structure is 2-5mm, and preferably 5mm.

[0063] In order to balance the printing self-forming and the surface quality of the plate parts in the 3D printing process, the common placing mode in the prior art is parallel to the printing platform, and the surface area is large, which leads to low utilization rate of the printing platform.

[0064] It is found in the research that the angle between the panel of the C-shaped plate part and the vertical direction less than 45° can make the plate part self-form along the vertical direction; if the single C-shaped plate part is placed along the angle that can self-form in the vertical direction, the panel of the C-shaped plate part is easy to deform and the surface quality cannot be controlled, and the dense support can improve the surface quality, and the setting of the dense support will limit the design of the complex structure such as the mounting joint and the process chuck on the panel of the C-shaped plate part.

[0065] In the application, two C-shaped plate parts are arranged in mirror image symmetry, and the two parts are supported and connected by a solid plate structure to form a stable structure, avoid the deformation of the parts in the printing process, improve the dimensional accuracy of the surface, and control the deformation in the forming process within ±1mm; compared with the parallel placement to the printing platform, the forming surface area of the single part is reduced by more than 25%, which greatly improves the utilization rate of the printing platform and improves the forming efficiency;

[0066] Further, the mounting joints of the two C-shaped plate parts are oriented to the symmetry axis of the mirror image symmetry structure when placed, which facilitates the setting of the linear support structure in the joint and other areas that cannot complete self-forming;

[0067] Specifically, in step S2, the support structure further includes a surface support, the surface support is distributed at the lowest point of the part and the area that does not meet the self-forming, and the surface support structure is a thin plate extending downward to the printing platform substrate at the support position;

[0068] The lowest point of the part and the area that does not meet the self-forming are identified in the model processing process, and then the surface support structure is added;

[0069] The coordinate system of the C-shaped plate part structure is that the direction parallel to the bottom surface of the C-shaped plate body is the x direction, the direction parallel to the side surface of the C-shaped plate body is the z direction, and the center line of the mounting joint cylinder of the C-shaped plate is the y direction;

[0070] In a possible design, the surface support positions of the area that does not meet the self-forming on the side of the mirror image structure symmetry axis of the part include: four edges of the xy direction plane on the side of each process chuck facing the printing platform; three edges on the xy direction plane on the side of the mounting joint facing the printing platform and not connected with the panel of the C-shaped plate body; the edge on the x direction away from the printing platform on the inner wall of the cylinder at one end of the mounting joint and not connected with the panel of the C-shaped plate body; the surface support positions of the area that does not meet the self-forming on the other side of the part are mirror image symmetric to the above positions;

[0071] The surface support structure not meeting the self-forming region is a thin plate extending from the support position to the printing platform substrate; the thickness of the surface support thin plate is 2-5 mm, preferably 5 mm.

[0072] Preferably, the solid plate structure and parts are distributed with periodic water-drop-shaped holes on the surface support not meeting the self-forming region.

[0073] The water-drop-shaped hole has an upward taper, a hole diameter of 5-8 mm, a long axis of 6-10 mm, a hole spacing of 15-20 mm, and an opening rate of 30-40%.

[0074] The water-drop-shaped hole is arranged without affecting the structural strength, and is conducive to reducing the loss of support material and local deformation compared with a circular hole and a square hole, thereby reducing stress concentration.

[0075] In a possible design, the water-drop-shaped hole has a hole diameter of 6 mm, a long axis of 7.3 mm, a hole spacing of 18 mm, and an opening rate of 38.6%.

[0076] Preferably, in order to facilitate positioning and removal of the support structure, the surface support thin plate connected with the mounting joint is provided with a row of circular holes at the support position, and the circular holes have a hole diameter of 1-2 mm.

[0077] Exemplarily, the TA15 titanium alloy powder having a particle size range of 15-53 μm is used for laser selective melting forming of the C-shaped plate part.

[0078] Specifically, in step S4, the laser selective melting forming process parameters are as follows: a laser power of 160-200 W, a scanning speed of 600-1000 mm / s, a scanning spacing of 0.08-0.12 mm, and a powder layer thickness of 30-40 μm.

[0079] In a possible design, the laser selective melting forming process parameters are as follows: a laser power of 180 W, a scanning speed of 800 mm / s, a scanning spacing of 0.10 mm, and a powder layer thickness of 30 μm.

[0080] Further, the deformation of the C-shaped plate during laser selective melting forming is controlled within ±1 mm.

[0081] A three-coordinate measuring instrument is used to measure the outer dimensions of the 3D printed C-shaped plate part, and the measurement is compared with the design model to evaluate the size deviation. By using the placement method and support design of the present application, the deformation during the forming process can be controlled within ±1 mm.

[0082] The present application places each C-shaped plate part at an angle less than 45° between the panel and the vertical direction, and arranges two C-shaped plate parts in mirror symmetry and connects them through a solid plate-shaped support structure, thereby increasing the structural strength and stability, avoiding deformation of the parts during printing, improving the dimensional accuracy of the profile, controlling the deformation during forming to within ±1mm, reducing the loss of support material, reducing the forming area, and thereby improving the forming efficiency.

[0083] And by designing periodically arranged water-drop-shaped holes on the solid plate-shaped support structure connecting the two C-shaped plate parts, the material loss is further reduced without affecting the support strength.

[0084] The design of the present application will be described below through specific examples.

[0085] Example 1

[0086] The steps of laser selective melting forming the C-shaped plate part in this example are as follows:

[0087] S1, three-dimensional modeling: a model is established according to the outline of the C-shaped plate part;

[0088] The size of each C-shaped plate body is 230mm x 180mm x 5mm (thickness), and the mounting joint is located at the center of one side panel;

[0089] S2, set the placement mode and support structure:

[0090] Two C-shaped plate parts are placed in mirror symmetry, the angle between each C-shaped panel and the vertical direction is 45°, the minimum distance between the two C-shaped plates is 10mm, and the distance between the bottom edges is 310mm;

[0091] A solid support is added between the two C-shaped plate parts to form a mirror-symmetrical structure, the solid support has a thickness of 5mm, is provided with water-drop-shaped holes, the hole diameter is 6mm, the long axis is 7.3mm, the hole spacing is 18mm, and the hole opening rate is 38.6%;

[0092] S3, model processing: slice processing is performed on the two C-shaped plate part models after the placement mode and solid support are set;

[0093] S4, laser selective melting forming: laser selective melting forming operation is performed on the processed model, the laser selective melting forming operation is performed on the substrate, and the two C-shaped plate parts and the support structure are integrally formed, wherein the process parameters of the support structure are the same as those of the part body;

[0094] The laser selective melting forming process parameters are: laser power 180W, scanning speed 800mm / s, scanning pitch 0.10mm, and powder layer thickness 30μm;

[0095] S5, powder cleaning: after the laser selective melting forming is completed, the C-shaped plate parts together with the substrate is taken off from the equipment, hoist the substrate, clean the substrate and the powder around the parts;

[0096] S6, wire cutting: after the wire cutting separates the parts from the substrate, further separates the two C-shaped plates into two independent C-shaped plates.

[0097] Compared with the same vertical angle, the support material is saved by 35%; compared with the same C-shaped plate parallel printing plane, the area is saved by 29.3%; the deformation in the forming process is controlled within ±1mm.

[0098] The present application is aimed at the structural characteristics of large area, non-closed rotation of C-shaped plate parts with mounting joints, each part is placed according to the angle between the panel and the vertical direction less than 45°, so that most of the area of each C-shaped plate and mounting joint meets the self-forming condition, in order to ensure the structural strength and control the quality of the profile, two C-shaped plate parts are arranged in mirror symmetry and connected through solid plate support structure, which increases the structural strength and stability, avoids the deformation of the parts during printing process, the forming area of a single part is reduced by more than 25%, greatly improves the utilization rate of the printing platform, improves the dimensional accuracy of the profile, the deformation in the forming process is controlled within ±1mm, reduces the addition of a large amount of support, only the lowest point of the workpiece and part of the area that does not meet the self-forming condition need to be added with support structure, which reduces the loss of support material.

[0099] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A laser selective melting forming method for C-shaped plate parts with mounting joints, characterized in that, Includes the following steps: S1. 3D Modeling: Establish a model based on the outer contour of the C-shaped plate part; S2. Setting the placement method and support structure: Mirror the two C-shaped plate parts and add a solid support connection between the two C-shaped plate parts to form a mirror symmetrical structure; The C-shaped plate part includes a body, a mounting joint, and a process chuck; the body is a flat plate structure, including two front panels, two bottom surfaces, and two side surfaces; the mounting joint is located on the front panel of the body, and the process chuck is located on the side surface of the body; the angle between the front panel of the C-shaped plate part and the vertical direction is less than 45°; the mounting joint of the C-shaped plate part faces the axis of symmetry of the mirror symmetry structure. The solid support includes two solid plate structures; The solid plate structure includes two isosceles trapezoidal plate surfaces, an upper base edge, a lower base edge, and two side edges; the plate surfaces of the solid plate structure are perpendicular to the substrate; the lower base edge of the solid plate structure is connected to the substrate; the two side edges of the solid plate structure are respectively connected to one side panel of two C-shaped plate with mounting joints and are coplanar; The two solid plate structures and the two C-shaped plate parts constitute a frustum structure without upper and lower bottom surfaces; S3. Model Processing: Slice the two C-shaped plate part models after setting the placement method and solid support; S4. Selective Laser Melting: The processed model is subjected to selective laser melting. The selective laser melting is performed on the substrate. The two C-shaped plate parts and the support structure are integrally formed. The process parameters of the support structure are the same as those of the part body. S5. Powder cleaning: After the laser selective melting and forming is completed, the C-shaped plate part and the substrate are removed from the equipment together. The substrate is lifted and the powder around the substrate and the part is cleaned. S6. Wire EDM: After separating the parts from the substrate by wire EDM, the two integrated C-shaped plates are divided into two independent C-shaped plates.

2. The forming method according to claim 1, characterized in that, The solid plate structure has periodically arranged teardrop-shaped holes.

3. The forming method according to claim 1, characterized in that, In step S2, the support structure further includes surface supports, which are distributed at the lowest point of the part and in areas that do not meet the self-forming requirement.

4. The forming method according to claim 1, characterized in that, The C-shaped plate part is laser selective melting forming using TA15 titanium alloy powder, and the particle size range of the TA15 titanium alloy powder is 15~53μm.

5. The forming method according to claim 1, characterized in that, In step S4, the laser selective melting forming process parameters are: laser power 160~200W, scanning rate 600~1000mm / s, scanning spacing 0.08~0.12mm, and powder layer thickness 30~40μm.

6. The forming method according to claim 1, characterized in that, The deformation during the laser selective melting and forming process of the C-shaped plate is controlled within ±1 mm.

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