Dynamic gradient binder assisted unsupported metal SLM forming process and system

Abstract

According to the dynamic gradient binder assisted support-free metal SLM forming process, a binder is adopted to play a temporary supporting role in component forming, adding of a supporting structure in the traditional SLM forming process is avoided, powder can be reused after the binder is degreased and volatilized in the later period, and the manufacturing cost is reduced; meanwhile, the first binder and the second binder with the rigidity gradient are matched according to the stress requirement of a supporting area, on-demand supporting is achieved, collapse deformation caused by insufficient supporting of a high-stress area is avoided, the post-treatment problem caused by excessive supporting of a medium-stress area is solved, deformation or collapse of parts is effectively prevented, and the rate of finished products is increased; and a support formed by the binder is easy to fall off in the later period, so that the post-treatment difficulty is greatly reduced, the post-treatment time is shortened, and the impact damage to the component is reduced while the automatic production efficiency is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal additive manufacturing, in particular to a dynamic gradient binder-assisted non-support metal SLM forming process and system. BACKGROUND

[0002] Selective laser melting (SLM) is a metal additive manufacturing technology that melts metal powder layer by layer and solidifies by high-energy laser beam to manufacture metal parts with complex geometry. However, in the traditional SLM forming process, for complex configuration parts such as overhanging and deep cavity, the non-supporting area is prone to deformation or collapse due to structural stress imbalance, so additional support structure is needed, and the support structure also needs to be printed using metal powder sintering. After the part is completed, the support needs to be removed by a machining tool. This not only increases the manufacturing cost due to the consumption of support material, the extension of printing period and the increase of machining process, but also causes surface damage to the part during the subsequent post-processing process of removing the support, which seriously restricts the practicality and preparation efficiency of the process.

[0003] Therefore, it is of great significance to develop a metal SLM forming process without traditional support structure. SUMMARY

[0004] The present application aims to overcome the shortcomings of the prior art by using a binder to act as a temporary support during component forming and matching different binders with a stiffness gradient according to the stress requirements of the support area to achieve on-demand support, effectively prevent deformation and / or collapse of the component, and reduce costs and improve production efficiency.

[0005] According to a first aspect of the object of the present application, a dynamic gradient binder-assisted non-support metal SLM forming process is provided, comprising the following steps: Selecting a target metal powder and pre-treating it, while preparing a binder; wherein the binder includes a first binder and a second binder, the support stiffness of the first binder being greater than that of the second binder, so that the support stiffness of the first binder and the second binder forms a gradient; According to the size of the component to be formed, perform three-dimensional modeling and slicing processing, and divide the support structure area into a first support area and a second support area through an intelligent identification module; wherein the first support area is an area with a hanging length > 5mm and / or an angle < 30°; The selective laser melting process is used to print layer by layer according to the preset program until the component is formed; wherein in each layer printing, the support structure area and the entity structure area are automatically identified by the computer, the binder printing head system sprays the binder corresponding to each support structure area in the support structure area according to the preset program to form the binder support structure, and the selective laser sintering light path system sprays the laser on the metal powder in the entity structure area layer by layer to form the entity component according to the preset program; wherein the binder sprayed in the first support area is the first binder, and the binder sprayed in the second support area is the second binder; by setting the dynamic gradient binder support structure in the laser melting process, the temporary support effect is exerted on the entity component to prevent the entity component from deforming and / or collapsing. After the laser melting of all layers is completed, the formed component is taken out, the binder support structure is naturally detached, and if there is a binder support structure that has not been detached, it is automatically separated from the component after being vibrated and crushed into powder.

[0006] As an optional embodiment, the thermal decomposition temperature of the binder is greater than 250℃.

[0007] As an optional embodiment, the compatibility of the binder and the metal powder satisfies that the binder and the metal powder only form physical contact without chemical bonding reaction.

[0008] As an optional embodiment, the components of the first binder include 92 wt.%~95 wt.% of modified epoxy resin and 5 wt.%~8 wt.% of alumina particles.

[0009] As an optional embodiment, the modified epoxy resin is E-51 type, and the thermal decomposition temperature is 380℃~420℃; the particle size of the alumina particles is 5 μm~10 μm, and the alumina particles are surface modified by silane coupling agent KH-550.

[0010] As an optional embodiment, the components of the second binder include 97 wt.%~98 wt.% of polycaprolactone and 2 wt.%~3 wt.% of polytetrafluoroethylene micro powder.

[0011] As an optional embodiment, the number average molecular weight of the polycaprolactone is 20000~30000, and the thermal decomposition temperature is 290℃~320℃; the particle size of the polytetrafluoroethylene micro powder is 1 μm~3 μm.

[0012] According to the second aspect of the object of the present application, a dynamic gradient binder assisted support-free metal SLM forming system is provided, which comprises: a forming cavity, which is internally configured with a forming platform that is lifted along the height direction of the forming cavity, and the forming platform is used to carry the metal powder and the formed entity component; The binder printing unit comprises a binder printing head arranged at the top of the forming cavity, and the nozzle of the binder printing head faces the forming platform. The binder printing head reciprocates along the X-axis direction and the Y-axis direction relative to the plane where the forming platform is located through the moving device. The selective laser sintering light path unit comprises a laser for emitting laser and a galvanometer system for guiding the laser to irradiate the metal powder along a scanning path to realize laser melting.

[0013] As an optional embodiment, the moving device comprises a first guide rail and a second guide rail; the first guide rail is assembled on the second guide rail and reciprocates along the extension direction of the second guide rail relative to the X-axis direction set relative to the plane where the forming platform is located; the binder printing head is assembled on the first guide rail and reciprocates along the extension direction of the first guide rail relative to the Y-axis direction set relative to the plane where the forming platform is located, so as to realize the coordinated reciprocation of the binder printing head in the X-axis and Y-axis directions in the plane where the forming platform is located through the bearing and guiding of the second guide rail to the first guide rail and the bearing and guiding of the first guide rail to the binder printing head.

[0014] As an optional embodiment, the dynamic gradient binder assisted support-free metal SLM forming system further comprises a PLC control unit electrically connected with the binder printing unit and the selective laser sintering light path unit respectively, for controlling the cooperation of binder spraying and laser melting.

[0015] As can be seen from the technical solutions of the present application above, the dynamic gradient binder assisted support-free metal SLM forming process proposed by the present application uses binder to play a temporary supporting role in component forming, avoids the addition of support structures in the traditional SLM forming process, and the powder can be reused after the binder is debinded and volatilized later, thereby reducing the manufacturing cost. At the same time, the first and second binders with stiffness gradients matched according to the stress requirements of the support areas realize on-demand support, which not only avoids the collapse deformation caused by insufficient support in the high stress area, but also prevents the post-processing problems caused by excessive support in the medium stress area, effectively prevents the deformation or collapse of the parts, and improves the yield. The supports formed by the binder are easy to fall off later, greatly reducing the difficulty of post-processing, reducing the post-processing time, greatly improving the automatic production efficiency while reducing the impact damage to the components. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is the schematic diagram of the exemplary dynamic gradient binder assisted support-free metal SLM forming system of the present application.

[0017] Figure 2is an exemplary process flow chart of the dynamic gradient binder assisted support-free metal SLM forming process of the present application. DETAILED DESCRIPTION

[0018] In order to better understand the technical content of the present application, specific embodiments are described below with reference to the accompanying drawings.

[0019] Aspects of the present application are described in the disclosure by reference to the accompanying drawings, which show many illustrative embodiments. The embodiments of the present disclosure are not necessarily intended to include all aspects of the present application. It should be understood that the various concepts and embodiments introduced above, and those described in more detail below, can be implemented in any of a variety of ways.

[0020] The present application adopts a binder printing support structure as auxiliary support, which plays a temporary support role, and matches binder support structures with different support stiffness according to the differentiated support strength requirements of different regions (such as large-span overhang, thin-walled, complex internal cavity, near-plane support, short cantilever), while identifying the support requirements of different regions in real time during the printing process, forming a dynamic gradient binder assistance, which avoids the use of traditional support structures and solves the problems of collapse due to insufficient support in overhanging areas or difficulty in removing due to excessive support in simple areas.

[0021] It can be understood that the binder support structure adopted by the present application plays a temporary support role, which is different from the traditional support structure, so in the metal SLM forming process, it can be considered as a kind of support-free process.

[0022] Dynamic gradient binder assisted freeform metal SLM system

[0023] In combination Figure 1 The exemplary dynamic gradient binder assisted support-free metal SLM forming system of the present application is shown, which includes a forming cavity 1, a binder printing unit 2 and a selective laser sintering light path unit 3.

[0024] Among them, the inside of the forming cavity 1 is configured with a forming platform 11 that rises and falls along the height direction of the forming cavity, the forming platform 11 is used to carry metal powder and formed solid components, and the binder support structure.

[0025] The binder printing unit 2 includes a binder printing nozzle 21, the binder printing nozzle 21 is arranged at the top of the forming cavity, so that the nozzle of the binder printing nozzle 21 faces the forming platform 11, to realize the binder spraying operation on the load carried by the forming platform 11.

[0026] The binder printing nozzle 21 reciprocates along the X-axis direction and the Y-axis direction set relative to the plane where the forming platform 11 is located through the moving device.

[0027] In one of the optional examples, the mobile device comprises a first guide rail 22 and a second guide rail 23.

[0028] The first guide rail 22 is assembled on the second guide rail 23 and reciprocates along the extension direction of the second guide rail 23 relative to the X-axis direction set in the plane where the forming platform 11 is located.

[0029] The binder printing head 21 is assembled on the first guide rail 22 and reciprocates along the extension direction of the first guide rail 22 relative to the Y-axis direction set in the plane where the forming platform 11 is located.

[0030] Through the bearing and guiding of the second guide rail 23 to the first guide rail 22 and the bearing and guiding of the first guide rail 22 to the binder printing head 21, the binder printing head 21 realizes coordinated reciprocation in the X-axis and Y-axis directions in the plane where the forming platform 11 is located, thereby realizing two-dimensional plane covering binder injection to the bearing object on the forming platform 11.

[0031] In one of the optional examples, the binder printing head 21 has a double-channel switching head, which can switch different binders in real time according to requirements during work, so as to realize gradient strength distribution of the same layer of support.

[0032] The selective laser sintering light path unit 3 comprises a laser 31 and a galvanometer system 32, the laser 31 is used for emitting laser 311, and the galvanometer system 32 is used for guiding the laser 311 to irradiate the metal powder along the scanning path to realize laser melting.

[0033] In one of the optional examples, the selective laser sintering light path unit 3 further comprises a feeding system, including a powder feeding device and a powder laying device, the target metal powder is transported to the forming platform 11 through the powder feeding device, and the target metal powder is uniformly laid on the forming platform 11 through the powder laying device.

[0034] The binder printing unit 2 and the selective laser sintering light path unit 3 are electrically connected with the PLC control unit, and the cooperation of binder injection and laser melting is controlled through the PLC control unit.

[0035] Dynamic gradient binder assisted freeform metal SLM process

[0036] In combination Figures 1-2 As shown, the example dynamic gradient binder auxiliary support-free metal SLM forming process of the present application adopts the foregoing forming system, which comprises the following steps: Selecting a target metal powder and pretreating it, and preparing a binder at the same time; wherein the binder comprises a first binder and a second binder, the support stiffness of the first binder is greater than that of the second binder, so that the support stiffness of the first binder and the second binder forms a gradient; According to the size of the component to be formed, a three-dimensional model is established and slice processing is performed, and the support structure area is divided into a first support area and a second support area by an intelligent recognition module; wherein the first support area is an area with a hanging length > 5mm and / or an angle < 30°; A selective laser melting process is used to print layer by layer according to a preset program until the component is formed; wherein in each layer of printing, the support structure area and the solid structure area are automatically recognized by the computer, the binder printing jet unit 2 sprays the binder corresponding to the support structure area in each support structure area according to the preset program to form a binder support structure 4, and at the same time, the selective laser sintering light path unit 3 sprays the metal powder in the solid structure area layer by layer according to the preset program to form a solid component 5; wherein the binder sprayed in the first support area is a first binder, and the binder sprayed in the second support area is a second binder; by setting a dynamic gradient binder support structure during laser melting, a temporary support effect is exerted on the solid component to prevent deformation and / or collapse of the solid component; After laser melting of all layers is completed, the formed component is taken out, and the binder support structure falls off naturally. If there is a binder support structure that has not fallen off, it is automatically separated from the component after being shaken and crushed into powder.

[0037] In an optional example, the thermal decomposition temperature of the binder is greater than the residual temperature of the SLM laser action area, which is about 250℃, to prevent the binder from failing prematurely during the forming process.

[0038] In an optional example, the compatibility of the binder and the metal powder satisfies that the binder and the metal powder only form physical contact without chemical bonding reaction.

[0039] In one of the optional examples, the first binder has the characteristics of high thermal stability, high rigidity and strong support force, and the components include 92 wt.%~95 wt.% modified epoxy resin and 5 wt.%~8 wt.% aluminum oxide particles.

[0040] In a more preferred example, the modified epoxy resin is E-51 type, and the thermal decomposition temperature is 380℃~420℃, matching the local high temperature during SLM laser melting; the particle size of the aluminum oxide particles is 5 μm~10 μm, and the surface is modified by silane coupling agent KH-550 to improve the compatibility with the resin.

[0041] In one of the preferred examples, the first binder is 92%~95% modified epoxy resin + 5%~8% aluminum oxide particles by mass ratio, stirred in a planetary mixer at 300~500r / min for 1~2h to form a uniform suspension, and the first binder is used for support in large-span suspended areas (cantilever length > 5mm and / or angle < 30°).

[0042] In one of the optional examples, the second binder has the characteristics of low bonding strength, low temperature embrittlement, easy to separate, and the composition includes 97 wt.%~98 wt.% polycaprolactone and 2 wt.%~3 wt.% polytetrafluoroethylene micro powder.

[0043] In a more preferred example, the number average molecular weight of polycaprolactone is 20000~30000, and the thermal decomposition temperature is 290℃~320℃; the particle size of polytetrafluoroethylene micro powder is 1 μm~3 μm, and it is used as a lubricant.

[0044] In one of the preferred examples, the second binder is 97%~98% polycaprolactone + 2%~3% polytetrafluoroethylene micro powder by mass ratio, melt mixed in a twin-screw extruder at 120~140℃, crushed after cooling, and then dissolved into a solution with a mass fraction of 20%~30% using a solvent (such as dichloromethane) for use. The second binder is used for simple support areas of parts (such as near-plane support, short cantilever).

[0045] Next, taking printing components with different overhanging structures as an example (areas with overhanging length >5mm and / or overhanging angle <30°, areas with overhanging length 3-5mm and angle 30°~45°), we provide a specific preparation process as follows:

[0046] [Step 1, raw material processing]

[0047] {1-1, metal powder selection and pretreatment} Select spherical metal powder with a particle size of 15 μm~53 μm (such as stainless steel 316L, titanium alloy TC4, which meets the powder flowability requirements of SLM forming), and dry it in a vacuum drying oven at 80℃~120℃ for 2 h~4 h to remove the water adsorbed on the surface of the powder (to avoid agglomeration when spraying the binder later).

[0048] Use an air flow sieve to screen the powder to ensure uniform particle size distribution (D10≥15 μm, D50=30 μm~40 μm, D90≤53 μm) to prevent fine powder from clogging the binder nozzle. The particle size of the metal powder determines the slice thickness of step 2 (slice thickness = 1.5~2 times the particle size of the powder, such as 30 μm powder corresponding to slice thickness 45 μm~60 μm).

[0049] {1-2, preparation of gradient functional binder} High-strength support type binder (first binder): 92%~95% modified epoxy resin (E-51 type, thermal decomposition temperature 380℃~420℃) + 5%~8% alumina particles (particle size 5 μm~10 μm, surface modified by silane coupling agent KH-550) are stirred in a planetary mixer at 300~500 r / min for 1 h~2 h to form a uniform suspension.

[0050] Easy-to-release type binder (second binder): 97%~98% polycaprolactone (number average molecular weight 20000~30000, thermal decomposition temperature 290℃~320℃) + 2%-3% polytetrafluoroethylene micro powder (particle size 1-3 μm) are melt-mixed in a twin-screw extruder at 120℃~140℃, and after cooling, they are crushed and then dissolved into a solution with a mass fraction of 20%~30% using a solvent (such as dichloromethane).

[0051] [Step 2, 3D modeling and slicing, from 3D model to executable layered path]

[0052] {2-1, 3D modeling} A 3D model of the part to be formed is constructed using SolidWorks (or UG) software, and the model accuracy is controlled within ±0.01 mm to avoid design errors being passed on to the forming stage.

[0053] Boolean operations are performed on the model to remove redundant features (such as sharp corners, which are replaced with R0.5mm fillets to reduce stress concentration during laser melting).

[0054] {2-2, slicing processing} The 3D model is imported into SLM dedicated slicing software (such as Magics), and the slicing parameters are set: slicing thickness 45 μm~60 μm (matching the particle size of the metal powder in step 1), scanning pitch 80 μm~100 μm (1.2~1.5 times the laser spot diameter, such as spot diameter 70 μm corresponding to scanning pitch 84 μm~105 μm).

[0055] Island-like scanning paths of solid structures are generated to reduce thermal deformation during laser scanning.

[0056] {2-3, support area path planning} The support area intelligent identification module of the slicing software is started, and the determination threshold is set: areas with a hanging length > 5 mm and / or a hanging angle < 30° are high-strength support areas (first support area), and the remaining hanging areas are easy-to-release support areas (second support area), and the corresponding binder types of each area are labeled.

[0057] [Step 3, equipment debugging before forming, adapting dual-system function and process parameters]

[0058] {3-1, Core device inspection and modification} Inspect the motion accuracy of the first guide rail 22 and the second guide rail 23 (positioning error ≤0.01 mm, ensuring the accuracy of the nozzle path), and the output power stability of the laser 31 (power fluctuation ≤±5%, for example, if the set power is 200 W, the actual output is 190 W~210 W).

[0059] {3-2, PLC parameter setting} Adhesive spraying parameters: high-strength adhesive spraying flow rate 0.12~0.18 mL / min, easy-to-release adhesive spraying flow rate 0.1~0.15 mL / min; adhesive printing nozzle 21 moving speed 50~80 mm / s (matching the path density to avoid spraying overlap or omission).

[0060] Laser parameters: laser power 180~220 W (180 W~200 W for stainless steel 316L, 200 W~220 W for TC4), scanning speed 800~1200 mm / s (the higher the power, the scanning speed can be appropriately increased to avoid excessive molten pool).

[0061] Timing parameters: delay 2.5 s after the completion of adhesive spraying (to ensure the preliminary curing of the adhesive), and the spacing between laser scanning and the adhesive area is 0.15 mm (to avoid carbonization of the adhesive caused by laser residual heat).

[0062] [Step 4, Gradient adhesive spraying and laser melting linkage, layer-by-layer collaborative forming]

[0063] {4-1, Powder laying} Start the powder laying device (such as a scraper powder spreader) to uniformly lay the metal powder pre-treated in step 1 on the forming platform 11, with a powder laying thickness of 45 μm-60 μm (consistent with the slice thickness in step 2) and a powder laying speed of 10~15 mm / s (to ensure that the powder layer density is ≥4.5 g / cm³, and the loose bulk density of stainless steel 316L is about 4.8 g / cm³). 3 ).

[0064] {4-2, Gradient adhesive spraying} The PLC controls the adhesive printing nozzle 21 to switch to the channel according to the support area type marked in step 2: high-strength support area sprays high-strength adhesive (flow rate 0.12~0.18 mL / min), and easy-to-release support area sprays easy-to-release adhesive (flow rate 0.1~0.15 mL / min); the adhesive switching of different support areas in the same layer is realized through synchronous movement of the guide rail, and a delay of 2.5 s is provided after spraying to ensure that the adhesive is cured to form a temporary support.

[0065] {4-3, Laser melting entity} Start selective laser sintering light path system: the laser 31 emits laser 311, the galvanometer system 32 guides the laser 311 along the entity scanning path generated in step 2 to scan, melts the metal powder at 180 W~220 W power, 800~1200 mm / s speed, forms the entity part; When laser scanning, keep 0.15mm spacing with binder support area, avoid laser direct irradiation binder.

[0066] {4-4, interlayer circulation} The forming platform 11 is lowered by 45 μm~60 μm according to the slice thickness, and steps 4-1~4-3 are repeated until all slice layers (such as 200 layers) are formed; During the period, the inert atmosphere (argon purity ≥ 99.999%, oxygen content ≤ 0.01%, to prevent metal powder oxidation) in the forming cavity 1 is maintained.

[0067] [Step 5, post-processing] After the laser melting of all layers is completed, the forming member is taken out, and the binder support structure is naturally detached. If there is binder support structure that has not been detached, it is automatically separated from the member after being vibrated and crushed into powder.

[0068] Through the process of the application, production efficiency and product quality can be optimized from multiple dimensions. In terms of cost control, the binder replaces the traditional SLM forming support structure, reducing support material consumption and post-removal loss, and unsintered metal powder can be recycled, reducing raw material waste and manufacturing cost. In terms of automation production efficiency, the temporary support formed by the binder is easy to fall off, saving the complex support removal process, shortening the post-processing time, and improving the overall automation operation efficiency. In terms of finished product rate guarantee, the two types of binders with different stiffness gradients are matched according to the stress requirements of different regions of the member to support as needed, avoiding collapse and deformation in high stress areas and damage in medium stress areas, reducing waste throughout the process and stabilizing the finished product rate.

[0069] Although the present application has been disclosed as above with preferred embodiments, it is not intended to limit the present application. Those skilled in the art without departing from the spirit and scope of the present application can make various modifications and improvements. Therefore, the protection scope of the present application shall be subject to the definition of the claims.

Claims

1. A dynamic gradient binder-assisted freeform metal SLM forming process, characterized in that, The method comprises the following steps: selecting a target metal powder and pre-treating it, and preparing a binder; wherein the binder comprises a first binder and a second binder, the support stiffness of the first binder is greater than that of the second binder, so that the support stiffness of the first binder and the second binder forms a gradient; performing three-dimensional modeling and slicing processing according to the size of the to-be-formed component, and dividing the support structure region into a first support region and a second support region through an intelligent recognition module; wherein the first support region is a region with a hanging length > 5mm and / or an angle < 30°; adopting a selective laser melting process, printing layer by layer according to a preset program until the component is formed; wherein in each layer of printing, the support structure region and the solid structure region are automatically recognized by a computer, the binder printing nozzle unit sprays the binder corresponding to each support structure region in the support structure region according to the preset program to form a binder support structure, and at the same time, the selective laser sintering light path unit melts the metal powder in the solid structure region layer by layer according to the preset program to form a solid component; wherein the binder sprayed in the first support region is the first binder, and the binder sprayed in the second support region is the second binder; by setting a dynamic gradient binder support structure in the laser melting process, the solid component is temporarily supported to prevent deformation and / or collapse of the solid component; after laser melting of all layers is completed, the formed component is taken out, the binder support structure falls off naturally, and if there is binder support structure that has not fallen off, it is automatically separated from the component after being vibrated and crushed into powder.

2. The dynamic gradient binder-assisted, freeform metal SLM forming process of claim 1, wherein, The thermal decomposition temperature of the binder is greater than 250℃.

3. The dynamic gradient binder-assisted, freeform metal SLM forming process of claim 1, wherein, The compatibility of the binder and the metal powder satisfies that the binder and the metal powder only form physical contact and there is no chemical bonding reaction.

4. The dynamic gradient binder-assisted, freeform metal SLM forming process of claim 1 wherein, The components of the first binder include 92 wt.%~95 wt.% of modified epoxy resin and 5 wt.%~8 wt.% of alumina particles.

5. The dynamic gradient binder-assisted, freeform metal SLM forming process of claim 4, wherein, The modified epoxy resin is of E-51 type, and the thermal decomposition temperature is 380℃~420℃; the particle size of the alumina particles is 5 μm~10 μm, and the alumina particles are surface-modified by silane coupling agent KH-550.

6. The dynamic gradient binder-assisted, freeform metal SLM forming process of claim 1, wherein, The components of the second binder include 97 wt.%~98 wt.% of polycaprolactone and 2 wt.%~3 wt.% of polytetrafluoroethylene micro powder.

7. The dynamic gradient binder-assisted, freeform metal SLM forming process of claim 6, wherein, The number average molecular weight of the polycaprolactone is 20000~30000, and the thermal decomposition temperature is 290℃~320℃; the particle size of the polytetrafluoroethylene micro powder is 1 μm~3 μm.

8. A dynamic gradient binder-assisted freeform metal SLM forming system, characterized in that, It comprises: a forming cavity (1) internally configured with a forming platform (11) that ascends and descends along the height direction of the forming cavity (1), the forming platform (11) being used for carrying a metal powder and a formed solid component; a binder printing unit (2) comprising a binder printing nozzle (21), the binder printing nozzle (21) being arranged at the top of the forming cavity, with the nozzle of the binder printing nozzle (21) facing the forming platform (11); The binder printing nozzle (21) reciprocates along the X-axis and Y-axis directions set relative to the plane where the forming platform (11) is located through a moving device; The selective laser sintering light path unit (3) comprises a laser (31) and a galvanometer system (32), the laser (31) is used for emitting laser (311), and the galvanometer system (32) is used for guiding the laser (311) to irradiate the metal powder along the scanning path to realize laser melting.

9. The dynamic gradient binder-assisted, freeform metal SLM system of claim 8, wherein, The moving device comprises a first guide rail (22) and a second guide rail (23); the first guide rail (22) is assembled on the second guide rail (23) and reciprocates along the extension direction of the second guide rail (23) relative to the X-axis direction set relative to the plane where the forming platform (11) is located; the binder printing nozzle (21) is assembled on the first guide rail (22) and reciprocates along the extension direction of the first guide rail (22) relative to the Y-axis direction set relative to the plane where the forming platform (11) is located, so as to realize the coordinated reciprocation of the binder printing nozzle (21) in the X-axis and Y-axis directions in the plane where the forming platform (11) is located through the bearing and guiding of the second guide rail (23) to the first guide rail (22) and the bearing and guiding of the first guide rail (22) to the binder printing nozzle (21).

10. The dynamic gradient binder-assisted, freeform metal SLM system of claim 8, wherein, The dynamic gradient binder auxiliary support-free metal SLM forming system further comprises a PLC control unit, the PLC control unit is electrically connected with the binder printing unit (2) and the selective laser sintering light path unit (3) respectively, and is used for controlling the cooperation of binder injection and laser melting.

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