A clamping method for connecting 3D printing and machining

Abstract

The application discloses a clamping method for connecting 3D printing and machining, and belongs to the field of precision machining. Firstly, a 3D printing part model is established based on part structure, the part model comprises a part body and a process handle which are combined into one, the process handle is arranged along the circumference of the part body, and the outer contour is a rectangular structure for facilitating positioning. Then, 3D printing is carried out. Finally, the printed part is processed according to a 3D printing post-processing procedure to obtain a 3D printing blank. Finally, machining is carried out: the process handle is machined to ensure the flatness of the clamping reference, and the machined process handle is used as a clamping reference for subsequent finish machining to complete the finish machining of the part. The application can not only ensure that warping deformation and tool jamming do not occur during the printing process of a complex special-shaped thin-walled part, improve the printing success rate and quality of the thin-walled part, but also quickly and efficiently realize the accurate positioning and clamping of the 3D printed part in subsequent machining, omit the layout procedure of a bench worker, simplify the technological process, and shorten the machining cycle.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of precision machining, and particularly relates to a clamping method for connecting 3D printing and machining. BACKGROUND

[0002] Selective Laser Melting (SLM) is favored by researchers in the field of aerospace because of its high flexibility, rapid prototyping, and no constraints on the complexity of part shape. The part is a thin-walled special-shaped part with a wall thickness of only 1mm. Due to the influence of the forming limit size of the 3D printing equipment, it is extremely difficult to form when the wall thickness is less than or equal to 1mm. The surface quality of the formed part is poor, and the part is prone to warping deformation, tool jamming and printing failure during the printing process. Even if the printing is successful, the support strength is higher than the part when the support is removed, which can easily cause the part to deform or even break. The method of using 3D printing to form a thin-walled special-shaped complex structure part has a high risk. Due to the limitations of the selective laser melting processing method, the forming precision cannot meet the use requirements of the part, and high-precision matching surfaces often need subsequent machining. The machining allowance of the 3D printed part is small, generally less than 1mm. How to simply, efficiently and accurately achieve the clamping and positioning of the 3D printed part has always been a difficult technical problem. The more complex the part, the more difficult it is to accurately position. The commonly used method is to use the printing substrate as part of the part for machining and clamping positioning. However, the printing position of the part on the substrate cannot be accurately positioned. The zero point bottom surface is generally connected to the substrate by support, and the features at the bottom of the part cannot be machined and clamped by the substrate at one time. After the part is removed from the substrate, it cannot be accurately clamped and positioned. SUMMARY

[0003] Technical problems to be solved:

[0004] In order to avoid the shortcomings of the prior art, the application provides a clamping method for connecting 3D printing and machining. A simple and efficient process handle for accurately positioning and clamping a complex special-shaped thin-walled structure part is designed for clamping and positioning in the subsequent machining process of the 3D printed part. The application can not only ensure that the complex special-shaped thin-walled part does not warp and deform during the printing process, and does not jam the tool, thereby improving the printing success rate and quality of the thin-walled part. The application can also quickly and efficiently achieve accurate positioning and clamping of the 3D printed part in the subsequent machining process, omit the marking process of the bench worker, simplify the process flow, and shorten the machining cycle.

[0005] The technical scheme of the application is a clamping method for connecting 3D printing and machining, characterized by the following specific steps:

[0006] Step 1: model design;

[0007] A 3D printing part model is established based on part structure, the part model comprises a part body and a process handle which are combined into one, and the process handle is arranged along the circumference of the part body and has a rectangular structure for easy positioning;

[0008] The length direction of the process handle is perpendicular or parallel to the printing direction, and the bottom directly contacts with the printing substrate;

[0009] Step 2: model printing;

[0010] Firstly, printing process parameters are set according to part model structure characteristics, and supports are designed; then, the designed process file is imported into equipment for 3D printing; finally, the printed part is processed according to the 3D printing post-processing procedure to obtain a 3D printing rough part;

[0011] Step 3: mechanical processing;

[0012] Firstly, the process handle is processed according to the position of the part to ensure the flatness of the clamping reference and the accuracy of the positioning reference position; then, the processed process handle is used as the clamping reference for subsequent finishing processing to complete the accurate processing of the part.

[0013] A further technical scheme of the present application is that in step 1, before model design, the part placement scheme needs to be determined, and according to the process characteristics of 3D printing, 3D printing placement design needs to be performed on complex thin-walled special-shaped parts to determine the final placement scheme.

[0014] A further technical scheme of the present application is that in step 1, the part model is locally optimized: the local small features are removed, that is, the thread hole, the light hole, the small sharp corner and the boss are removed; and the shape of the chamfer or the transverse hole is changed to facilitate 3D printing.

[0015] A further technical scheme of the present application is that in step 1, the overall thickness of the part model is 0.5mm,

[0016] A further technical scheme of the present application is that in step 1, for the process handle of the thin-walled special-shaped part: a connecting plate is arranged along the circumference between the thin-walled special-shaped part and the rectangular frame process handle, and the thin-walled special-shaped part and the process handle are connected into an integral structure through the connecting plate; the connecting plate is located on the vertical section surface of the thin-walled special-shaped part.

[0017] A further technical scheme of the present application is that in step 1, for the process handle of the thin-walled pipe: the process handle is a cuboid structure, the upper surface is combined with one side port of the thin-walled pipe, and the lower surface is used as a positioning reference.

[0018] A further technical scheme of the present application is that in step 2, for the complex special-shaped thin-walled part, small layer thickness sintering parameters are selected to form good internal quality and surface roughness.

[0019] A further technical solution of the present application is that in step 2, the part model with the added support is subjected to process simulation, optimization, and simulation iteration until the printing requirements are met.

[0020] A further technical solution of the present application is that in step 3, when the process handle is processed, a vice clamping method is used to flatten the process handle to ensure a flatness within 0.01, serving as a reference for subsequent part machining.

[0021] Beneficial effects

[0022] The beneficial effects of the present application are that the process handle designed in the present application can not only ensure that complex and special-shaped thin-walled parts do not warp and deform during printing and do not get stuck, thereby improving the printing success rate and quality of thin-walled parts, but also can quickly and efficiently realize accurate positioning and clamping of 3D printed parts during subsequent machining, omit the bench work marking process, simplify the process flow, and shorten the machining cycle. The present application is suitable for 3D printing and machining integrated forming of complex and special-shaped thin-walled structural parts with a wall thickness of 1-2mm that are not easy to clamp for machining.

[0023] Therefore, the present application has strong guiding significance for applying 3D printing to process complex and special-shaped thin-walled parts, can greatly facilitate process design, printing process planning, part shape stability control, etc. of such parts, shorten the product development and production cycle, reduce production costs, and has wide application value. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a model comparison schematic diagram of the present application before and after adding process handles to the periphery of the thin-walled and special-shaped part;

[0025] Figure 2 is a model comparison schematic diagram of the present application before and after adding process handles to the bottom of the thin-walled and special-shaped part;

[0026] Figure 3 is a 3D printed physical diagram of the thin-walled and special-shaped part in the present application;

[0027] Figure 4 is a physical diagram of the thin-walled and special-shaped part after machining in the present application.

[0028] Explanation of reference signs: 1. part body, 2. process handle. DETAILED DESCRIPTION

[0029] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0030] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0031] The process method of the present application mainly includes three important aspects. First, according to the characteristics of 3D printing process, the parts are placed for printing; second, considering the subsequent machining clamping scheme; third, the position, size and shape of the process handle are designed.

[0032] The process steps are as follows:

[0033] (1) Model placement: according to the characteristics of 3D printing process, the complex thin-walled special-shaped parts are placed for 3D printing design, and the final placement scheme is determined;

[0034] (2) Model optimization: according to the placement method and the characteristics of 3D printing process, the model is optimized locally. Mainly remove local small features such as threaded holes, light holes, small sharp corners and bosses; change the local shape for 3D printing, such as adding chamfer, changing the shape of horizontal hole, which is realized by subsequent machining;

[0035] (3) Model sticking amount: considering the positions that need to be machined later, the part model is processed by sticking amount, and the traditional machining finished blank is formed;

[0036] (4) Design of mechanical clamping process handle: add process handle to facilitate 3D printing forming and subsequent mechanical machining clamping and positioning. The process handle should meet the following requirements a) The process handle should be rectangular and the thickness, width and spacing should be appropriate, evenly distributed around the part; b) Its setting and layout should be convenient to operate, reliable, accurate enough for machining, easy to implement, economical, conducive to programming and machining, and not prone to interference and collision; c) The length direction of the process handle should be perpendicular or parallel to the printed square, and the bottom should be in direct contact with the printing substrate to ensure the printing accuracy of the process handle; d) The three perpendicular directions of the process handle should be open and not connected with the part and the printing substrate to facilitate accurate clamping and positioning during machining; d) The process handle should be located at the bottom of the printed part placement direction in direct contact with the substrate, or parallel to the placement direction, but the bottom surface should be in contact with the substrate to ensure the printing accuracy of the process handle and the success rate of part printing forming.

[0037] (5) Selection of printing process parameters: the part is a complex thin-walled part, and small layer thickness sintering parameters are selected, and the internal quality and surface roughness are good;

[0038] (6) Support design: according to the sintering process parameters and model placement, the support addition position, quantity and strength are determined;

[0039] (7) Process simulation: the model with added support is simulated for process simulation, optimization, and simulation iteration until the printing requirements are met;

[0040] (8) 3D printing: the designed process file is imported into the equipment for 3D printing;

[0041] (9) Post-processing: the printed part is processed according to the 3D printing post-processing process to obtain the 3D printing blank.

[0042] (10) Machining: the process handle is a reference for clamping and positioning of the complex thin-walled special-shaped part. The out-of-tolerance flatness of the process handle or inaccurate positioning of the process handle will directly lead to size out-of-tolerance and scrap. When the 3D printed part is formed, the process handle and the part are formed together to accurately ensure the relative relationship between the process handle and the part. However, the surface flatness and roughness of the process handle of the part formed by 3D printing are poor, and it cannot be directly used as a positioning and clamping reference for subsequent finishing. During machining, the process handle needs to be machined first to ensure the flatness of the clamping reference and the accuracy of the positioning reference. The machining of the process handle is an important process that determines the success or failure of the part machining, and is also a difficulty in the entire machining process. Because a special process handle is designed during 3D printing, the process handle has high forming precision and accurate relative relationship with the part, so it can be directly clamped and positioned for process handle machining. The machined process handle is used as a clamping reference for subsequent finishing to complete the accurate machining of the part.

[0043] Example 1

[0044] Referring to Figures 1-4 , the 3D printing and machining process of the complex thin-walled special-shaped part is as follows:

[0045] (1) Model placement: according to the 3D printing process characteristics, the 3D printing placement design of the complex thin-walled special-shaped part is performed, the part is placed vertically, the mating surface is parallel to the printing direction, and the part is appropriately adjusted in the other two directions according to the local features to form the final placement scheme, as shown in Figure 1 ;

[0046] (2) Model optimization: according to the placement method and 3D printing process characteristics, the local small features such as threaded holes, light holes, small sharp corners and bosses are removed, and are realized by subsequent machining;

[0047] (3) Model paste amount: considering that the part has high requirements on surface quality and installation surface precision, the part model is pasted with 0.5mm as a whole, and a traditional machining precision blank is formed to ensure the surface quality of the part;

[0048] (4) Design of mechanical clamping process handle: add a process handle to facilitate subsequent machining clamping and positioning, consider the semi-open nature of the part, and add a process handle around the part and at the bottom, as shown in Figure 1 .

[0049] (5) Selection of printing process parameters: the part is a complex and irregular thin-walled part, and small layer thickness sintering parameters are selected, so that the internal quality and surface roughness of the part are good;

[0050] (6) Support design: determine the support addition position, quantity and strength according to the sintering process parameters and model placement;

[0051] (7) Process simulation: simulate the process of the model with added supports, optimize, and iterate until the printing requirements are met;

[0052] (8) 3D printing: import the designed process file into the equipment for 3D printing;

[0053] (9) Post-processing: process the printed part according to the 3D printing post-processing procedure to obtain a 3D printed blank.

[0054] (10) Machining: use a vice to clamp the process handle when machining the process handle, and sweep the process handle to ensure that the flatness is within 0.01, which serves as a reference for subsequent machining. The machined part is shown in Figure 4 .

[0055] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those skilled in the art can make changes, modifications, replacements and variations to the above embodiments without departing from the principles and purposes of the present application within the scope of the present application.

Claims

1. A clamping method connecting 3D printing and machining, characterized in that... The specific steps are as follows: Step 1: Model Design; A 3D printed part model is established based on the part structure. The part model includes a part body and a process handle that are integrated into one piece. The process handle is set along the circumference of the part body and the outer contour is a rectangular structure that is easy to position. The length direction of the process handle is perpendicular or parallel to the printing direction, and the bottom is in direct contact with the printing substrate. For the process handle setup of thin-walled irregular parts: a connecting plate is set circumferentially between the thin-walled irregular part and the rectangular frame process handle, and the thin-walled irregular part and the process handle are connected into an integral structure by the connecting plate; the connecting plate is located on the vertical cut surface of the thin-walled irregular part. For the process handle setting of thin-walled pipe fittings: the process handle is a cuboid structure, with the upper surface fitting against one side port of the thin-walled pipe fitting, and the lower surface serving as a positioning reference. In step 1, the part model is locally optimized: small local features are removed, such as threaded holes, open holes, small sharp corners, and bosses; the shape of chamfers or horizontal holes is changed to facilitate 3D printing; the overall thickness of the part model is 0.5mm. Step 2: Print the model; First, the printing process parameters are set according to the structural features of the part model, and the support is designed; then, the designed process file is imported into the equipment for 3D printing; finally, the printed part is processed according to the 3D printing post-processing procedure to obtain the 3D printed blank. In step 2, a small layer thickness sintering parameter is selected for complex irregular thin-walled parts, which can form better internal quality and surface roughness; the process model of the part after the support is added is simulated, optimized, and iterated until the printing requirements are met. Step 3: Machining; First, the process shank is machined according to the position of the part to ensure the flatness of the clamping datum and the accuracy of the positioning datum. Then, the machined process shank is used as the clamping datum for subsequent finishing to complete the precise machining of the part. When machining the process shank, a vise is used to clamp it and flatten it to ensure that the flatness is within 0.01, which serves as the datum for subsequent machining of the part. The clamping method described herein is applicable to the integrated 3D printing and machining of all complex, irregularly shaped, thin-walled structural parts with a wall thickness of 1-2 mm that are difficult to clamp and machine.

2. The clamping method for connecting 3D printing and machining according to claim 1, characterized in that: In step 1, before model design, it is necessary to determine the part placement scheme. Based on the characteristics of 3D printing process, it is necessary to design the placement of complex thin-walled irregular parts for 3D printing and determine the final placement scheme.

Images