Metal additive and subtractive composite machining forming method and system

Abstract

This invention provides a forming method for metal additive-subtractive composite machining. The method includes: additive printing forming and subtractive machining, which are performed alternately and cyclically until the desired component is obtained. During each pass of additive printing forming and subtractive machining, after subtractive machining is completed, edge subtractive machining is performed on the junction area of ​​the current workpiece, forming a chamfered surface at the edge of the junction area. Then, the angle of the workpiece is adjusted so that the chamfered surface is parallel to the working surface of the additive printing head. This parallelism between the deposited layer and the working surface of the additive printing head is maintained throughout the subsequent additive printing process, providing support for the molten pool. This method ensures the normal operation of the additive printing process after subtractive machining and guarantees the quality and dimensional accuracy of the additive printing, truly realizing complex additive-subtractive composite machining processes.

Description

Technical Field

[0001] This invention relates to the field of additive and subtractive composite processing technology, and more specifically to a method and system for additive and subtractive composite processing of complex metal parts. Background Technology

[0002] Metal additive manufacturing is an important branch of additive manufacturing (commonly known as "3D printing"). It typically uses heat sources such as lasers or electric arcs to melt metal powder or welding wires, and then manufactures solid parts by layering and stacking them one by one. It is currently widely used in fields such as medical, aerospace, traditional manufacturing, automotive, and dentistry.

[0003] Compared with traditional precision machining, metal additive manufacturing has the following advantages: (1) Short product development and realization cycle. The blanks produced by additive manufacturing technology do not require mold support, the cutting allowance is small, and some parts can even be used after simple post-processing. Compared with traditional process, the process and cost of product development are greatly shortened. (2) More complex structures can be formed efficiently. The principle of 3D printing is to divide complex three-dimensional geometry into two-dimensional cross-sectional shapes for layer manufacturing. Therefore, it can realize the forming of complex components that are difficult to achieve with traditional precision machining, improve the yield of parts, and improve product quality. For additive manufacturing, the increase in structural complexity has little impact on cost, while the cost of traditional manufacturing methods will increase significantly with the increase in structural complexity. (3) Achieve integrated and lightweight design. Under the premise of ensuring performance, additive manufacturing can simplify the number of parts and connection structure, and even achieve integrated forming, thereby reducing the volume and weight of the assembly, reducing costs, and improving product reliability.

[0004] In most cases, parts manufactured using metal additive manufacturing still require subsequent subtractive processing to meet usage requirements. Because the substrate of the metal additive manufacturing blank undergoes significant deformation due to prolonged high heat input, more machining allowance needs to be reserved during the blank manufacturing process to reduce the difficulty of datum alignment in subsequent subtractive processing, resulting in wasted material and processing time. To address this problem, additive-subtractive composite processing technology has emerged.

[0005] This new process organically integrates traditional subtractive machining and additive manufacturing onto the same machine. It uses an additive printing module to quickly produce blanks, followed by rapid and precise machining using a subtractive module. Neither process requires disassembling the substrate; both use the machine tool's own zero-point coordinates as a reference, avoiding the difficulty of blank alignment. Furthermore, the alternating additive-subtractive-additive-subtractive process solves the problem of unreachable tools in traditional machining, leading to its increasing application in recent years. However, challenges also arise during this process. For example, the molten pool in additive printing requires good support to achieve optimal printing quality and dimensional accuracy. However, in many cases, the unprocessed structure after subtractive machining cannot provide ideal molten pool support for additive printing, making the transition between additive and subtractive processes difficult and significantly limiting the application scope of additive-subtractive machining technology. Summary of the Invention

[0006] The purpose of this invention is to solve the technical problem of poor additive printing quality or even failure to add material during the process of alternating additive and subtractive manufacturing, where the subtractive process cannot provide support for the next additive printing. The invention provides a forming method and system for metal additive and subtractive composite manufacturing, which adjusts the shape of the area where the subtractive and additive processes are combined and adjusts the angle of the current printing area in real time to meet the support requirements of the molten pool, thereby completing the switch from subtractive to additive manufacturing and realizing complex additive and subtractive composite manufacturing processes.

[0007] According to a first aspect of the present invention, a forming method for metal additive and subtractive composite processing is provided, the method comprising: additive printing forming and subtractive processing, wherein the additive printing forming and subtractive processing are performed alternately and cyclically until the desired component is obtained;

[0008] In each pass of additive printing and subtractive processing, after subtractive processing is completed, the edge subtractive processing is performed on the junction area of ​​the current workpiece to form a chamfered surface. Then the angle of the workpiece is adjusted so that the chamfered surface is parallel to the working surface of the additive printing head. In the subsequent additive printing process, the deposition layer is kept parallel to the working surface of the additive printing head to provide support for the molten pool.

[0009] As an optional implementation, the chamfer angle α of the chamfered surface is 0° < α < 90°.

[0010] As an optional implementation, the heat source used in additive printing includes one or a combination of laser, electric arc, and ion beam.

[0011] As an optional implementation, the filler used in additive printing includes one or a combination of two of welding wire and powder.

[0012] As an optional implementation, the additive printing process includes laser fused deposition modeling, laser wire feeding additive manufacturing, electric arc additive manufacturing, or laser-electric arc composite additive manufacturing.

[0013] According to a second aspect of the present invention, a forming system for composite metal additive and subtractive processing is provided, comprising:

[0014] The working platform includes a base and a rotary table located on the base. A three-dimensional coordinate system is established with the center of the base as the origin. The base can rotate around the Z-axis, and the rotary table can rotate around a line parallel to the X-axis or a line parallel to the Y-axis.

[0015] A working axis located above the working platform, the working axis can move along the X-axis, Y-axis and Z-axis, and rotate on its own axis;

[0016] An additive manufacturing system, including a printhead detachably mounted on a work axis, with the working end of the printhead facing a rotary table, is used for metal additive printing.

[0017] A subtractive machining system includes a milling spindle and a subtractive cutting tool mounted on the milling spindle. The milling spindle is detachably mounted on a working axis, and the subtractive cutting tool faces a rotary table for subtractive machining of additively printed parts.

[0018] The additive manufacturing system and the subtractive manufacturing system are set to alternate and cycle until the component processing is completed. In each additive printing and subtractive processing pass during the processing, after subtractive processing and before additive printing, the edge of the subtractive and additive bonding area of ​​the workpiece is processed into a chamfered surface. By adjusting the shape of the bonding area of ​​subtractive and additive processes and using the cradle swing adjustment of the work platform, the angle of the printing area is leveled in real time to provide support for the molten pool of additive printing.

[0019] As an optional implementation, the rotary table is provided with a base plate facing the working end of the print head and the subtractive cutting tool.

[0020] As an optional implementation, the additive manufacturing system further includes a feeding system for conveying the printing material.

[0021] As can be seen from the above technical solution of the present invention, the forming method of metal additive and subtractive composite processing proposed in the present invention processes the edge of the junction area of ​​the subtractive and additive processes of the workpiece into a chamfered surface. By adjusting the shape of the junction area of ​​the subtractive and additive processes and using a cradle-type work platform to level the angle of the current printing area in real time, the support requirements of the molten pool are met, thereby completing the switch from subtractive to additive processes. It can also ensure the quality and dimensional accuracy of additive printing, and truly realize complex additive and subtractive composite processing technology.

[0022] The method of this invention has no requirements on the material and shape of the target part, no requirements on the metal additive printing process, and the processing model is simple and convenient, with high practicality and wide applicability. Attached Figure Description

[0023] Figure 1 This is an example part of the present invention.

[0024] Figure 2 It is a schematic diagram of the stages of manufacturing demonstration parts using existing additive and subtractive manufacturing processes, as well as a top view of the parts corresponding to each stage.

[0025] Figure 3 This diagram illustrates why it is difficult to achieve good additive printing results in the area where additive and subtractive manufacturing processes are combined.

[0026] Figure 4 This is a schematic diagram of the forming system for metal additive and subtractive composite processing of the present invention during the N3 stage.

[0027] Figure 5 This is a schematic diagram of the forming system for metal additive and subtractive composite processing of the present invention during the N4 stage of the processing.

[0028] Figure 6 This is a schematic diagram of the forming system for metal additive and subtractive composite processing of the present invention during the N5 stage of processing.

[0029] Figure 7 This is a schematic diagram of the stages of manufacturing an exemplary part using the metal additive and subtractive composite processing forming method of the present invention, and a top view of the part corresponding to each stage. Detailed Implementation

[0030] To better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0031] Various aspects of the invention are described in this disclosure with reference to the accompanying drawings, in which numerous illustrative embodiments are shown. The embodiments of this disclosure are not necessarily intended to encompass all aspects of the invention. It should be understood that the various concepts and embodiments described above, as well as those described below in more detail, can be implemented in any of a number of ways.

[0032] Combination Figure 1 As shown in the figure, the existing additive-subtractive composite processing method and the additive-subtractive composite processing method of the present invention are illustrated using the part shown in the figure as an example.

[0033] Figure 1 The deep hole part 1 shown has a large height H, and the inner wall needs to be processed by material subtraction. Traditional processing methods cannot process the inner wall because the tool cannot reach it. The part can be formed by a combination of material addition and subtraction processing.

[0034] Combination Figure 2 , Figure 3 As shown, an exemplary process for machining a demonstrative part using existing additive and subtractive manufacturing techniques is as follows:

[0035] like Figure 2 As shown in A, a blank part 1a with a height of H0 is first obtained through additive manufacturing. This process is denoted as stage P1.

[0036] Then, as Figure 2 As shown in B, the inner wall allowance k of 1a is removed by subtraction machining to obtain workpiece 1b. This process is denoted as stage P2.

[0037] like Figure 2 As shown in C, the additive manufacturing of part 1c of the workpiece continues on workpiece 1b. This process is referred to as stage P3.

[0038] like Figure 2 As shown in D, the inner wall of 1c is processed by subtraction to obtain part 1d of the workpiece. This process is called stage P4.

[0039] This process is repeated until the required dimensions for the sample part are obtained.

[0040] In the above manufacturing process, such as Figure 3 As shown, during additive manufacturing, the point of action of the additive printhead is point P. Due to the characteristics of metal additive manufacturing, the cross-section of the molten pool in metal additive manufacturing must be a semi-circular shape with point P as the center and radius k, and the radius k fluctuates within a certain range.

[0041] During the process of adding material to the workpiece after subtractive processing, such as in stage P3, when point P coincides with the edge of the machining surface, the molten pool at this time is unstable in shape due to insufficient support, which will inevitably affect the additive printing quality of the edge. If point P shrinks inward, the machining allowance of this section of the blank will be insufficient, resulting in part defects.

[0042] Therefore, in order to solve the problem of poor additive printing quality or even the inability to add material after subtractive processing in the alternating addition and subtraction process, this invention constructs a forming method and system for metal additive-subtractive composite processing. By adjusting the shape of the area where the subtractive and additive processes are combined, and by using a cradle-type worktable to adjust the angle of the current printing area in real time, the support requirements of the molten pool are met, thereby completing the switch from subtractive to additive processing and truly realizing complex additive-subtractive composite processing technology.

[0043] Forming system for metal additive and subtractive composite processing

[0044] Combination Figure 4-6 As shown, the exemplary metal additive and subtractive composite forming system of the present invention includes a work platform 2, an additive manufacturing system, and a subtractive processing system.

[0045] The work platform 2 includes a base 21 and a rotary table 22 located on the base. A three-dimensional coordinate system is established with the center of the base as the origin. The base can rotate 360° around the Z-axis, and the rotary table can rotate 360° around a line parallel to the X-axis or a line parallel to the Y-axis, forming a cradle-type work platform.

[0046] The work platform 2 is equipped with a work axis on its upper part. The work axis can move along the X-axis, Y-axis and Z-axis and rotate on its own axis. In other words, the work axis can move up, down, left and right, and rotate 360° around the Z-axis.

[0047] The additive manufacturing system includes a printhead 3, which is detachably mounted on the working axis. The working end of the printhead 3 faces the rotary table 22, and metal additive printing is achieved through the movement of the working axis and the movement of the working platform.

[0048] The subtractive machining system includes a milling spindle 41 and a subtractive cutting tool 42 mounted on the milling spindle. The milling spindle 41 is detachably mounted on the working axis. The working end of the subtractive cutting tool 42 faces the rotary table 22, and the subtractive machining of the additively printed part is achieved by the movement of the working axis and the movement of the working platform.

[0049] In this process, the additive manufacturing system and the subtractive manufacturing system are set to alternate and cycle until the component processing is completed. In each additive printing and subtractive processing pass during the processing, after subtractive processing and before additive printing, the edge of the subtractive and additive bonding area of ​​the workpiece is processed into a chamfered surface. By adjusting the shape of the bonding area of ​​subtractive and additive processes and using the cradle swing adjustment of the work platform, the angle of the printing area is leveled in real time to provide support for the molten pool of additive printing.

[0050] As an optional implementation, the rotary table 22 is provided with a base plate 23 facing the working end of the print head and the subtractive cutting tool.

[0051] The additive manufacturing system also includes a feeding system for conveying the raw materials for printing.

[0052] Understandably, one or more working axes can be set. When only one working axis is set, the print head and subtractive cutting tool can be disassembled and reassembled through automated assembly. When multiple working axes are set, the print head and subtractive cutting tool are mounted on different working axes, and the addition and subtraction processing equipment can be switched by switching the working axes.

[0053] Furthermore, multiple additive and subtractive manufacturing equipment can be set up to enable the simultaneous processing of multiple parts.

[0054] Forming methods for composite metal additive and subtractive manufacturing

[0055] Combination Figure 4-7As shown, the forming system employing the aforementioned metal additive-subtractive composite processing, and the exemplary forming method of the present invention for metal additive-subtractive composite processing, include: additive printing forming and subtractive processing, wherein the additive printing forming and subtractive processing are performed alternately and cyclically until the desired component is obtained.

[0056] In each pass of additive printing and subtractive processing, after subtractive processing is completed, the edge subtractive processing is performed on the junction area of ​​the current workpiece to form a chamfered surface. Then the angle of the workpiece is adjusted so that the chamfered surface is parallel to the working surface of the additive printing head. In the subsequent additive printing process, the deposition layer is kept parallel to the working surface of the additive printing head to provide support for the molten pool.

[0057] As an optional implementation, the chamfer angle α of the chamfered surface is 0° < α < 90°.

[0058] As an optional implementation, the heat source used in additive printing includes one or a combination of laser, electric arc, and ion beam.

[0059] As an optional implementation, the filler used in additive printing includes one or a combination of two of welding wire and powder.

[0060] As an optional implementation, the additive printing process includes laser fused deposition modeling, laser wire feeding additive manufacturing, electric arc additive manufacturing, or laser-electric arc composite additive manufacturing.

[0061] In a more specific exemplary embodiment, the specific process of processing the demonstration part using the aforementioned metal additive-subtractive composite forming method is as follows:

[0062] First, install the print head 3 onto the working shaft, adjust the working platform to be horizontal, add the required metal material to the feeding system, and set the printing parameters;

[0063] like Figure 7 As shown in A, the first part of the blank 1a' is printed on the substrate according to the preset program. This process is called stage N1.

[0064] Then, switch to subtractive processing equipment, such as... Figure 7 As shown in B, the inner wall (A surface) of 1a' is processed by subtraction to the required size to obtain workpiece 1b'. This process is denoted as stage N2.

[0065] like Figure 4 , Figure 7 As shown in C, material is removed from the inner wall edge of workpiece 1b' to form a chamfered surface, where the chamfer α is 0° < α < 90°, resulting in workpiece 1b'-1. This process is denoted as stage N3.

[0066] Switch to printhead mode and adjust base 21 and rotary table 22 so that the chamfered surface of workpiece 1b'-1 is parallel to the working end of printhead 3, that is, so that the chamfered surface of workpiece 1b'-1 is basically horizontal. Figure 5 As shown, additive manufacturing continues on workpiece 1b'-1 until the work platform returns to a horizontal state and the deposition surface is parallel to the working end of the print head. Then, printing continues according to stage N1 to obtain part 1c' of the workpiece, as shown. Figure 7 As shown in D; during this process, the molten pool is supported, and subsequent additive manufacturing can print the shape, and a machining allowance t can be reserved to ensure the quality and dimensional accuracy of additive printing. This process is denoted as stage N4.

[0067] like Figure 6 , Figure 7 As shown in E, the inner wall of 1c' is subjected to subtractive processing, as in stage N3, to obtain part 1d' of the workpiece. This process is denoted as stage N5.

[0068] This process continues through stages N4 and N3 in sequence until the dimensions required for demonstration part 1 are obtained. Figure 7 F).

[0069] Thus, by using the aforementioned method, the edge of the combined area of ​​subtractive and additive manufacturing of the workpiece is machined into a chamfered surface. By adjusting the shape of the combined area of ​​subtractive and additive manufacturing processes and using a cradle-type work platform to level the angle of the current printing area in real time, a machining allowance can be reserved to meet the support requirements of the molten pool. This solves the problem of poor additive printing quality or even inability to add material after subtractive manufacturing in the existing technology.

[0070] The forming method for metal additive and subtractive composite processing proposed in this invention is applicable to the processing of any part and to any metal additive printing process, and has wide applicability.

[0071] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A forming method for composite metal additive and subtractive processing, characterized in that, The method includes: additive printing and subtractive processing, wherein the additive printing and subtractive processing are performed alternately and cyclically until the desired component is obtained; In each pass of additive printing and subtractive processing, after the subtractive processing is completed, the edge subtractive processing is performed on the junction area of ​​the current workpiece to form a chamfered surface. Then, the angle of the workpiece is adjusted by the cradle swing of the work platform so that the chamfered surface is parallel to the working surface of the additive printing head. In the subsequent additive printing process, the deposition layer is kept parallel to the working surface of the additive printing head to provide support for the molten pool. The work platform includes a base and a rotating platform located on the base. A three-dimensional coordinate system is established with the center of the base as the origin. The base can rotate 360° around the Z-axis, and the rotating platform can rotate 360° around a line parallel to the X-axis or a line parallel to the Y-axis, forming a cradle-type work platform. A working axis is set above the work platform. The working axis can move along the X-axis, Y-axis, and Z-axis and rotate on its own axis. Furthermore, the working axis can move up, down, left, and right, and rotate 360° around the Z-axis.

2. The forming method for metal additive-subtractive composite processing according to claim 1, characterized in that, The chamfer angle α of the chamfered surface has a value of 0° < α < 90°.

3. The forming method for metal additive-subtractive composite processing according to claim 1, characterized in that, The heat sources used in additive printing include one or a combination of lasers, electric arcs, and ion beams.

4. The forming method for composite metal additive and subtractive processing according to claim 1, characterized in that, The fillers used in additive printing include one or a combination of two of the following: welding wire and powder.

5. The forming method for metal additive-subtractive composite processing according to claim 1, characterized in that, The processes used in additive manufacturing include laser fused deposition modeling, laser wire feeding additive manufacturing, electric arc additive manufacturing, or laser-electric arc composite additive manufacturing.

6. A forming system for composite metal additive and subtractive processing, characterized in that, include: The working platform (2) includes a base (21) and a rotary table (22) located on the base. A three-dimensional coordinate system is established with the center of the base as the origin. The base (21) can rotate around the Z-axis, and the rotating platform (22) can rotate around a line parallel to the X-axis or a line parallel to the Y-axis. A working axis located above the working platform, the working axis can move along the X-axis, Y-axis and Z-axis, and rotate on its own axis; The additive manufacturing system includes a printhead (3) detachably mounted on a working shaft, with the working end of the printhead (3) facing the rotary table (22) for metal additive printing. The subtractive machining system includes a milling spindle (41) and a subtractive cutting tool (42) mounted on the milling spindle. The milling spindle (41) is detachably mounted on the working axis, and the subtractive cutting tool (42) faces the rotary table (22) for subtractive machining of additively printed parts. The additive manufacturing system and the subtractive manufacturing system are set to alternate and cycle until the component processing is completed. In each additive printing and subtractive processing pass during the processing, after subtractive processing and before additive printing, the edge of the junction area of ​​the workpiece for subtractive and additive processing is processed into a chamfered surface. By adjusting the shape of the junction area of ​​subtractive and additive processes and using the cradle swing adjustment of the work platform, the angle of the printing area is leveled in real time to provide support for the molten pool of additive printing.

7. The forming system for composite metal additive and subtractive processing according to claim 6, characterized in that, In each alternating pass of additive printing and subtractive processing, after subtractive processing is completed, edge subtractive processing is performed on the junction area of ​​the current workpiece to form a chamfered surface at the edge of the junction area. Then, the angle of the workpiece is adjusted so that the chamfered surface is parallel to the working surface of the additive printing head, and the deposition layer is kept parallel to the working surface of the additive printing head during subsequent additive printing processes to provide support for the molten pool.

8. The forming system for composite metal additive and subtractive processing according to claim 6, characterized in that, The chamfer angle α of the chamfered surface is 0° < α < 90°.

9. The forming system for composite metal additive and subtractive processing according to claim 6, characterized in that, The rotary table (22) is provided with a base plate (23) facing the working end of the print head (3) and the subtractive cutting tool (42).

10. The forming system for composite metal additive and subtractive processing according to claim 6, characterized in that, The additive manufacturing system also includes a feeding system for conveying the raw materials to be printed.

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