阅读说明：本技术 一种选区激光熔化成形致密-疏松一体化模具零件的方法 (Method for selective laser melting forming of compact-loose integrated die part ) 是由 王小新 管航 马一恒 董志家 厉邵 于 2019-11-01 设计创作，主要内容包括：本发明公开一种选区激光熔化成形致密-疏松一体化模具零件的方法,包括:1)选择零件部位并对其进行多孔结构设计；2)在镶件及模板上,设计点阵结构；3)将制作的三维模型导入切片软件中；4)设置参数；5)打印准备；6)开始打印；7)热成像仪进行温度信息采集,将采集的温度数据传递到PC控制中心,进行分析；8)对成形表面进行扫描表征计算成像,并进行信息比对；9)激光扫描成形；10)重复步骤6)至9),直至零件成形；11)分离成型样品；12)对成形样品热处理；本发明能合理地降低多孔结构区域的致密度,增加成形件的透气性,在保证模具零件的结构强度及产品的成形条件下,又能更好地解决复杂模具零件在工作中困气、真空吸附和嵌片定位的问题。(The invention discloses a method for forming a compact-loose integrated die part by selective laser melting, which comprises the following steps of 1) selecting a part and carrying out porous structure design on the part; 2) designing a lattice structure on the insert and the template; 3) importing the manufactured three-dimensional model into slicing software; 4) setting parameters; 5) preparing for printing; 6) starting printing; 7) the thermal imager collects temperature information and transmits the collected temperature data to a PC control center for analysis; 8) scanning, representing, calculating and imaging the forming surface, and comparing information; 9) laser scanning and forming; 10) repeating the steps 6) to 9) until the part is formed; 11) separating the molded sample; 12) carrying out heat treatment on the formed sample; the invention can reasonably reduce the density of the porous structure area, increase the air permeability of the formed part, and better solve the problems of air trapping, vacuum adsorption and insert positioning of the complex die part in the work under the condition of ensuring the structural strength of the die part and the forming condition of the product.)

1. A method for forming a compact-loose integrated die part by selective laser melting is characterized by comprising the following steps:

the method comprises the following steps that firstly, according to the specific application of a compact-loose integrated part, the specific characteristics of a product and the premise of a forming process, the part is reasonably selected and is subjected to porous structure design;

designing a lattice structure on a mold part with a porous structure or a matched insert and template to serve as an exhaust and support structure;

step three, storing the manufactured three-dimensional model in an STL format, introducing the three-dimensional model into slicing software, separating the porous structure part from the non-porous structure part for slicing, and setting the layer thickness and the scanning path; importing the program file into the SLM equipment and respectively endowing the two parts with different parameters;

step four, setting parameters; endowing the part with a non-porous structure with process parameters with good forming performance to form a compact structure; endowing the part of the porous structure with process parameters with lower forming density to form a loose structure;

step five, printing preparation: placing metal powder and a metal substrate, vacuumizing, introducing inert protective gas, and preheating the substrate for printing;

step six, starting printing: descending the working platform by a powder spreading thickness, ascending the powder supply cavity, spreading powder on the forming substrate by using a scraper, and performing laser scanning forming;

step seven, the thermal imager collects temperature information, transmits the collected temperature data to a PC control center, analyzes whether the thermal stress generated by different parameters can cause the formed sample to generate larger deformation or not, and dynamically adjusts the parameters according to the analysis result;

step eight, the surface topography scanning device scans and characterizes the forming surface, the acquired data are transmitted to a PC control center for calculation imaging, information comparison is carried out according to the slice model, the actual forming condition is known, and parameters are dynamically adjusted according to the analysis result;

step nine, after the laser scanning is finished, the workbench descends by a powder paving thickness, the powder supply cavity ascends, the powder paving is continued, and the laser scanning forming is carried out;

step ten, repeating the step six to the step nine until the part is formed, and stopping the equipment;

step eleven, cooling the sample to be molded to room temperature, taking out the sample, and separating the molded sample from the molded substrate by utilizing a linear cutting process;

and step twelve, carrying out heat treatment on the formed sample.

2. The method for selective laser melting forming of the compact-loose integrated die part according to claim 1, characterized in that: in the first step, the material of the die part is stainless steel or maraging steel, and the porous structure, the lattice structure and the compact part structure are integrally formed.

3. The method for selective laser melting forming of the compact-loose integrated die part according to claim 1, characterized in that: in the first step, the size of the structural unit is designed and adjusted according to the material and shape of the mould part, the material and shape of the product, the injection molding process parameters, the SLM technology and the equipment parameters.

4. The method for selective laser melting forming of the compact-loose integrated die part according to claim 1, characterized in that: in the second step, a mathematical model is required to be established for designing the lattice structure, and the lattice structure is subjected to static mechanical analysis; after the lattice structure is designed, static state simulation analysis is carried out by using finite element analysis software, and the structure size is adjusted according to the analysis result.

5. The method for selective laser melting forming of the compact-loose integrated die part according to claim 1, characterized in that: in the fourth step, the process parameters of the part with the porous structure are changed, and the laser energy input density and parameters need to be reasonably changed, so that the compactness of the part is reduced, and the part has proper air permeability; meanwhile, the mechanical property of the structural material is ensured, and the forming of parts and the quality of final products cannot be influenced.

6. The method for selective laser melting forming of the compact-loose integrated die part according to claim 1, characterized in that: and seventhly, analyzing the temperature field, the thermal stress and the deformation caused by the thermal stress by using finite element analysis software, and if the thermal gradient is larger and larger deformation is possible, reducing the difference between the laser energy input densities of the two parts as much as possible.

7. The method for selective laser melting forming of compact-loose integrated mold parts according to any of claims 1-6, characterized in that: in the eighth step, the surface topography scanning device can select one or a combination of a plurality of laser scanning imaging devices, electronic scanning imaging devices or optical imaging devices; and if the deviation between the formed actual size and the theoretical size of the model is large, analyzing the reason in the step seven and adjusting the parameters.

8. A method for solving the problem of air permeability of an injection mold part in operation is characterized by comprising the following steps of:

step one, determining an injection molding process of a product, and performing mold flow analysis on the product;

designing a porous structure at the gas trapping part of the die part; the product material is plastic such as ABS, PS, PP, PE and the like, the overflow edge value is 0.015-0.03 mm, the injection pressure is 30-100 MPa, and the SLM laser spot diameter is 0.05-0.1 mm; selecting a unit structure as a cube structure with the side length of 1-8mm, and selecting a square or a circle with the side length of 0.015-0.03 mm as a unit structure hole shape;

designing a lattice structure on the die part with the porous structure and the matched template; selecting maraging steel as a material, selecting a body-centered cubic (BCC) structure, forming a lattice structure by a selective laser melting technology, wherein the unit size of the lattice structure is generally 1-8mm, and designing the BCCThe length-diameter ratio of the element structure rod is 4-10, then

step four, storing the manufactured three-dimensional model in an STL format, introducing the three-dimensional model into slicing software, separating the porous structure part from the non-porous structure part for slicing treatment, and setting a scanning path to set the layer thickness to be 0.03-0.05 mm; importing the program file into the SLM equipment and respectively endowing the two parts with different parameters;

step five, setting parameters; process parameters for imparting good formability to a part of non-porous structure, wherein the parameters include: the laser power is 220-280W, the scanning speed is 1000-1500 mm/S, the scanning interval is 0.07-0.12 mm, and the scanning strategy is S-shaped orthogonal scanning; changing a scanning strategy, increasing the scanning speed and the scanning interval, properly reducing the laser energy input density, and endowing parameters to a part with a porous structure, so that the structure density is properly reduced through a forming process to improve the air permeability; wherein the parameters include: the laser power is 180-220W, the scanning speed is 1500-1800 mm/s, the scanning distance is 0.12-0.15 mm, and XY scanning is performed in scanning measurement;

step six, printing preparation; selecting 18Ni300 maraging steel metal powder with the powder particle size distribution range of 15-53 mu m as a forming material, preparing the metal powder into a powder supply cavity of SLM equipment, mounting a metal substrate, preheating the metal substrate to 150-200 ℃, closing a working bin, vacuumizing and filling high-purity argon with the concentration of 99.9%;

step seven, printing is started; work platform descends one and spreads powder thickness, supplies the powder chamber to rise, and wherein, supplies powder chamber to rise the height and the workstation descending height ratio to be 4: 1; spreading powder on a forming substrate by using a rubber scraper, and performing laser scanning forming;

step eight, acquiring temperature information by using an infrared thermal imager, transmitting the acquired temperature data to a PC control center, analyzing whether the formed sample generates larger deformation due to thermal stress generated by different parameters by using finite element software, dynamically adjusting parameters according to the analysis result, and when the thermal gradient is larger, standing and cooling for a period of time and properly improving the laser energy input density of the porous part;

step nine, selecting laser scanning imaging equipment to scan the forming surface, transmitting data acquired by a receiver to a PC control center for calculation imaging, comparing the forming size and the forming shape according to a slice model, and dynamically adjusting parameters according to an analysis result; when the pore size is inconsistent, stopping the equipment in time, and analyzing reasons and adjusting parameters according to the feedback result of the temperature field; the laser scanning imaging working speed is relatively low, so that 5 layers are selected to be formed for once surface topography imaging;

step ten, after the laser scanning is finished, the workbench descends by a powder paving thickness, the powder supply cavity ascends, the powder paving is continued, and the laser scanning forming is carried out;

step eleven, repeating the step seven and the step ten, and stopping the equipment after the part is formed;

step twelve, cooling the sample to be formed to room temperature, taking out the sample, and separating the formed sample from the formed substrate by utilizing a linear cutting process;

and thirteen, carrying out heat treatment on the formed sample, wherein the heat treatment is solid solution at 850 ℃ and aging heat treatment at 480 ℃ for 5 h.

9. A method of addressing venting of an injection mold part during operation as recited in claim 8, wherein: the method is applied to the aspects of demoulding of injection products or in-mould decoration of the injection products.

10. A method of addressing venting of an injection mold part during operation as recited in claim 9, wherein:

in the aspect of demoulding of injection products, lattice structures are designed on a mold core and a matched template and are connected with a porous structure, so that smooth air inlet is ensured, and the size parameters of the porous structure and the unit structure of the lattice structure are as in claim 8;

in the in-mold decoration process of an injection molding product, a plurality of symmetrical parts are selected on a part to carry out porous structure design;

in the second step of claim 8, the porous structure is selected from the group consisting of a cube having a structural unit side length L of 1 to 8mm, a circular through hole having a pore unit diameter of 0.3Lmm, and a pore node distance of 1 Lmm; the unit structure size parameters of the lattice structure are the same as in claim 8; in steps four and five of claim 8, SLM process parameters of the porous structure forming part are not changed;

and an air suction device or an air blowing device is arranged outside the dot matrix structure and is connected with the dot matrix structure.

Technical Field

The invention belongs to the technical field of advanced manufacturing, and relates to a method for combining the forming of a breathable non-compact die part based on a selective laser melting technology and the design of an injection die part with a lattice porous structure, namely a method for forming a compact-loose integrated die part by selective laser melting.

Background

By virtue of its advantages over conventional processes, 3D printing technology has evolved dramatically in recent years in the manufacturing industry. The selective laser melting technology is one of the main technical means of metal 3D printing, the process means of layer-by-layer additive forming has the unique advantage aiming at the forming of complex parts, and is widely applied in the fields of aerospace, military, medical treatment and automobiles at present.

The metal porous material consists of a metal framework and internal pores, has large specific surface area, small specific gravity and excellent shock resistance, and also has the performances of ventilation and heat exchange when the porosity reaches a certain percentage. The lattice structure has regular hole shapes and holes which are arranged periodically, the relative density is low, the mass is small, and the cost can be reduced under the condition of ensuring the structural strength. At present, the two structures are widely applied in the fields of vehicle manufacturing, weapon preparation, medical instruments and aviation.

CN201810959975.5 discloses a method for preparing air-permeable die steel by selective laser melting, comprising the following steps: s1, taking powder to be molded, wherein the powder to be molded comprises steel powder and chromium nitride; and S2, forming the powder to be formed by utilizing selective laser melting equipment. The invention successfully prepares the breathable die steel with communicated pores inside and smaller pore diameter by using a Selective Laser Melting (SLM) forming technology and simultaneously adopting a method of adding chromium nitride (CrN), and has better application prospect. CN201410265403.9 provides a preparation method of a titanium alloy thin-wall honeycomb structure, which comprises the following steps: (a) slicing and layering the titanium alloy thin-wall honeycomb structure model according to the thickness of 20-30 mu m layers; (b) uniformly paving the titanium alloy powder on a titanium alloy substrate, and selectively melting the titanium alloy powder layer by a laser beam emitted by a laser according to a determined laser beam scanning track to finish the processing of a layer of titanium alloy thin-wall honeycomb structure; (c) laying titanium alloy powder on the formed layer of titanium alloy thin-wall honeycomb structure again, and selectively melting the titanium alloy powder layer by laser beams emitted by a laser according to a determined laser beam scanning track; (d) and processing the titanium alloy thin-wall honeycomb structure layer by layer to finally form the titanium alloy thin-wall honeycomb structure. The method reduces stress accumulation and deformation of a forming part in the forming process, has high flexibility, and can prepare the thin-wall honeycomb structural member with variable honeycomb distance and even a three-dimensional lattice structure. CN201320215534.7 relates to the technical field of key molds, in particular to an inlaying structure mold for columnar solid plastic keys, which structurally comprises a female mold and a male mold, wherein the female mold is provided with a mold cavity corresponding to the columnar solid plastic keys in shape, the mold cavity comprises a straight column part and an arc chamfering part, the male mold is provided with an injection molding port, the mold cavity is communicated with the injection molding port, the female mold comprises an insert and a bottom plate part, a gap for exhausting is reserved between the insert and the bottom plate part, the straight column part is arranged on the insert, and the arc chamfering part is arranged on the bottom plate part; the invention provides an inlaying structure die for a columnar solid plastic key, which can not form trapped air at the bottom of a die cavity in the injection molding process.

However, in the prior art, when the injection mold closes the mold and injects the hot melt plastic, the gas inside the cavity of a part of complex parts is not easy to be discharged, and the hot melt plastic flows in the cavity to extrude and compress the air in the cavity, so that the phenomenon of gas trapping is formed, the forming of a product is influenced, and the service life of the mold is even reduced. The traditional process solves the problems that the design of a product and a mold is changed or a ventilating insert is arranged in a gas trapping area, the former prolongs the working period, and the latter is high in cost, so that the mold is more complicated, the layout difficulty of a water path is increased, and the heat dissipation efficiency of the mold is influenced.

The in-mold decoration technology puts the insert with printed patterns into a metal mold, and finishes the process of product decoration while the injection molding process. In the injection molding process, the fixation of the insert is an important ring, and the product is defective due to the fact that the insert slides off or is unstable in position. The prior art mainly has the defects of inclined pushing and fixing of an oil cylinder sliding block, fixing of an elastic needle and electrostatic adsorption, complex structural design, long processing period, high cost and the like.

When a closed box-packed product is demolded, vacuum adsorption is easy to occur between a plastic part and a mold core, so that demolding is difficult or even impossible. The existing solution is to set air inlet, optimize injection parameters and process, prolong the processing period and increase the cost.

Disclosure of Invention

In view of the above, the present invention provides a method for selective laser melting forming of compact-loose integrated mold parts, so as to solve the above problems.

The invention creatively provides a compact-loose integrated part forming method based on the selective laser melting technology by utilizing a method of combining the selective laser melting forming breathable mould part and the design of the mould part with a lattice porous structure, and utilizes a feedback system to regulate and control the forming precision.

A method for forming a compact-loose integrated die part by selective laser melting comprises the following specific steps:

the method comprises the following steps that firstly, according to the specific application of a compact-loose integrated part, the specific characteristics of a product and the premise of a forming process, the part is reasonably selected and is subjected to porous structure design;

designing a lattice structure on a mold part with a porous structure or a matched insert and template to serve as an exhaust and support structure;

step three, storing the manufactured three-dimensional model in an STL format, introducing the three-dimensional model into slicing software, separating the porous structure part from the non-porous structure part for slicing, and setting the layer thickness and the scanning path; importing the program file into the SLM equipment and respectively endowing the two parts with different parameters;

step four, setting parameters; endowing the part with a non-porous structure with process parameters with good forming performance to form a compact structure. Endowing the part of the porous structure with process parameters with lower forming density to form a loose structure;

step five, preparing for printing; placing metal powder and a metal substrate, vacuumizing, introducing inert protective gas, and preheating the substrate for printing;

sixthly, printing is started; descending the working platform by a powder spreading thickness, ascending the powder supply cavity, spreading powder on the forming substrate by using a scraper, and performing laser scanning forming;

step seven, the thermal imager collects temperature information, transmits the collected temperature data to a PC control center, analyzes whether the thermal stress generated by different parameters can cause the formed sample to generate larger deformation or not, and dynamically adjusts the parameters according to the analysis result;

step eight, the surface topography scanning device scans and characterizes the forming surface, the acquired data are transmitted to a PC control center for calculation imaging, information comparison is carried out according to the slice model, the actual forming condition is known, and parameters are dynamically adjusted according to the analysis result;

step nine, after the laser scanning is finished, the workbench descends by a powder paving thickness, the powder supply cavity ascends, the powder paving is continued, and the laser scanning forming is carried out;

step ten, repeating the step six to the step nine until the part is formed, and stopping the equipment;

step eleven, cooling the sample to be molded to room temperature, taking out the sample, and separating the molded sample from the molded substrate by utilizing a linear cutting process;

and step twelve, carrying out heat treatment on the formed sample.

Preferably, in the first step, the material of the die part is stainless steel or maraging steel;

preferably, in the step one, the size of the structural unit is designed and adjusted according to the aspects of the material and the shape of the mold part, the material and the shape of the product, the injection molding process parameters, the SLM technology, the equipment parameters and the like, so that the design capable of completely meeting the use requirement is obtained, and the influence on the product quality is avoided;

preferably, in the step one, the design and optimization of the porous structure are to improve the porosity of the structure as much as possible on the premise of meeting the use strength and avoiding larger defects;

further, in the second step, a mathematical model is required to be established for designing the lattice structure, as shown in fig. 3, and the lattice structure is analyzed by static mechanics. The main contents of the mechanical analysis are as follows:

assuming that the structure has continuous uniformity; assuming that the structure has only elongated beams; the lattice structure is assumed to have only small bending deformation under the action of load and is completely rigid to shearing deformation;

BCC is primarily distorted by bending, which is known from the Euler-Bernoulli Beam theory

EIw＝M，

Wherein F₁Is the force acting on the rod AB, l is the length of the rod AB, and simultaneous integration of two segments can be obtained

Wherein E_sIs the modulus of elasticity of the material, I is the moment of inertia of the rod AB, and w is the deflection of the rod AB. The corner and deflection of the fixed end of the rod are zero, so C₁And C₂All are zero, and the original formula is:

the deformation displacement h generated in the vertical direction is calculated,

the rod is designed to be a cylinder, then

The process is carried out in the above formula,

then strainWherein

The unit structure side length L is 2lcos theta, then

BCC isotropy, so the above formula is the BCC elastic modulus formula, wherein

Therefore, it is

Relative density of BCC structure

Simultaneous upper formula:

E＝0.092E_sρ²

maximum bending moment M of two sections of rod AB_maxI.e. bending moment of yielding of the rod edge, i.e.

To obtain

The relative density is obtained by simultaneous formula,

σ＝0.148σ_sρ^1.5。

from the results of the BCC static mechanical analysis, it is known that the elastic modulus and yield strength of the lattice structure are related only to the aspect ratio of the forming material and the structural rods.

Preferably, in the second step, after the lattice structure is designed, static state simulation analysis is performed by using finite element analysis software, and the structure size is adjusted according to the analysis result;

preferably, in the fourth step, the process parameters of the part with the porous structure are changed, and the laser energy input density and parameters are reasonably changed, so that the compactness of the part is reduced, and the part has proper air permeability; meanwhile, the mechanical property of the structural material is ensured, and the forming of parts and the quality of final products cannot be influenced;

preferably, in the seventh step, finite element analysis software is used for analyzing the temperature field, the thermal stress and the deformation caused by the thermal stress, and if the thermal gradient is larger and larger deformation is likely to occur, the difference between the laser energy input densities of the two parts is reduced as much as possible;

preferably, in the step eight, the surface topography scanning apparatus may select one or more of a laser scanning imaging device, an electronic scanning imaging device or an optical imaging device;

preferably, in the step eight, if the deviation between the formed actual size and the theoretical size of the model is large, the parameters are adjusted by combining the analysis reasons in the step seven; the size of the formed pore and the size and the mechanical property of the formed part are ensured to meet the use requirement;

preferably, the porous structure, the lattice structure and the compact part structure are all integrally formed.

The technical scheme of the invention at least has the following advantages and beneficial effects:

1) according to the invention, by carrying out lattice porous structure design on partial regions of the die part and forming based on the selective laser melting technology, the density of the porous structure region is reasonably reduced by controlling process parameters, the air permeability of a formed part is increased, the structural strength of the die part and the forming of a product can be ensured, and the problem of difficult air exhaust of the complex die part in the working process can be solved;

2) according to the invention, by carrying out lattice porous structure design on partial regions of the die part and forming based on a selective laser melting technology, the density of the porous structure region is reasonably reduced by controlling process parameters, the air permeability of the formed part is increased, the rigidity requirement of the die part on the air-permeable steel insert can be solved, and the problems that the die is more complicated and is difficult to arrange water paths, the cost is high and the like due to installation of the air-permeable steel insert are avoided;

3) according to the invention, by carrying out lattice porous structure design on partial regions of the die part and forming based on the selective laser melting technology, the density of the porous structure region is reasonably reduced by controlling process parameters, the air permeability of a formed part is increased, and the problem that the insert is easy to slip or unstable during the injection molding of the die insert can be better solved.

4) According to the invention, by carrying out lattice porous structure design on partial regions of the die part and forming based on the selective laser melting technology, the density of the porous structure region is reasonably reduced by controlling process parameters, the air permeability of the formed part is increased, and the phenomenon of vacuum adsorption during product demoulding can be better solved.

5) The invention utilizes the selective laser melting technology, and can effectively solve the problem of high difficulty in forming complex die parts by the traditional process, thereby saving manpower and material resources and shortening the processing period;

6) the invention combines the selective laser melting forming technology with the design of the lattice porous structure mould part, and has better innovation and application value in the technology.

Drawings

FIG. 1 is a process flow diagram of the selective laser melting technique-based forming of a mold part with a lattice porous structure attached.

Fig. 2 is a schematic diagram of a porous structure and a lattice structure.

FIG. 3 is a diagram of a mathematical model of a BCC lattice structure.

Fig. 4 is an analysis report of the product and the mold in the first embodiment. (a) Reporting screenshot for filling time of product module flow analysis; (b) actual products with defects due to trapped gas; (c) a screenshot of a three-dimensional model of a mold part formed in the first embodiment; (d) is a two-dimensional partial sectional view of the porous structure with the dot matrix structure in the step (c);

FIG. 5 shows a cell structure of a porous structure according to the first embodiment.

FIG. 6 is a schematic diagram of a body centered cubic structure according to the first embodiment.

Fig. 7 is a structural composition of a laser scanning imaging device in the first embodiment.

FIG. 8 is a schematic view of the lattice porous structure on the mesocore of example two.

FIG. 9 is a schematic view of an injection molded part according to the third embodiment. (a) Schematic drawing of slip-off of the insert in the in-mold decoration injection molding process; (b) is a schematic diagram of a lattice porous structure adsorption insert;

FIG. 10 shows a cell structure of a porous structure in the third example.

Detailed Description

The invention is described below with reference to the accompanying drawings and specific embodiments.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments.

Thus, the following detailed description of the embodiments of the invention is not intended to limit the scope of the invention as claimed, but is merely representative of some embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "back", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings or orientations or positional relationships that the products of the present invention are usually placed in when used. Such terms are merely used to facilitate describing the invention and to simplify the description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the invention.

It should also be noted that, in the description of the present invention, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

As shown in fig. 1-10, there are three examples of applications of the method of selective laser fusion forming of a dense-loose integrated mold part of the present invention:

the first application embodiment:

the embodiment is an application of the invention in the injection process of an injection product, and can better solve the problem of difficult air exhaust of an injection mold part in work, namely a method for solving air permeability of the injection mold part in work, and comprises the following specific steps:

step one, determining an injection molding process of a product, and performing mold flow analysis on the product. FIG. four (a) is a screenshot of a mold flow analysis report for a mold part of a product, showing gas entrapment;

and step two, designing a porous structure at the gas trapping part of the die part. The product material is selected to be ABS, the overflow edge value is 0.03mm, the injection pressure is 30MPa, and the SLM laser spot diameter is 0.05 mm. Selecting a unit structure as a cube structure with the side length of 1mm, selecting a square with the side length of 0.03mm as a unit structure hole shape, and setting the pitch of pore nodes as 0.07 mm;

step three, in the mould parts with porous structure and matchingAnd designing a lattice structure on the template. The Body Centered Cubic (BCC) structure is selected, and the forming size of the selected area laser melting technology is generally 1-8 mm. The material of maraging steel is selected, the elastic modulus is 180GPa, the yield strength of an SLM forming piece is 900MPa, and the length-diameter ratio of the BCC unit structural rod is designed to be 4

ρ is 0.255, and E is 1076.8MPa and σ is 17.15 MPa. The side length L of the selected unit structure is 8mm, and the rod diameter d is

A rod length l of

And step four, storing the manufactured three-dimensional model in an STL format, introducing the three-dimensional model into slicing software, separating the porous structure part from the non-porous structure part for slicing treatment, and setting a scanning path to set the layer thickness to be 0.03 mm. Importing the program file into the SLM equipment and respectively endowing the two parts with different parameters;

and step five, setting parameters. Process parameters for imparting good formability to a part of non-porous structure, wherein the parameters include: the laser power is 260W, the scanning speed is 1000mm/S, the scanning distance is 0.1mm, and the scanning strategy is S-shaped orthogonal scanning; the method changes the scanning strategy, increases the scanning speed and the scanning interval, properly reduces the laser energy input density, and endows parameters to the part of the porous structure, and aims to properly reduce the structure density through a forming process so as to improve the air permeability. Wherein the parameters include: the laser power is 260W, the scanning speed is 1800mm/s, the scanning distance is 0.15mm, and XY scanning is measured in a scanning mode;

and step six, printing preparation. Selecting 18Ni300 maraging steel metal powder with the powder particle size distribution range of 15-53 mu m as a forming material, preparing the metal powder into a powder supply cavity of SLM equipment, installing a metal substrate which is made of P20 die steel and has the thickness of 20mm, preheating the metal substrate to 150-200 ℃, closing a working bin, vacuumizing and filling high-purity argon with the concentration of 99.9%;

and step seven, starting printing. Work platform descends one and spreads powder thickness, supplies the powder chamber to rise, and wherein, supplies powder chamber to rise the height and the workstation descending height ratio to be 4: 1. spreading powder on a forming substrate by using a rubber scraper, and performing laser scanning forming;

step eight, acquiring temperature information by using an infrared thermal imager, transmitting the acquired temperature data to a PC control center, analyzing whether the formed sample generates larger deformation due to thermal stress generated by different parameters by using finite element software, dynamically adjusting parameters according to the analysis result, and when the thermal gradient is larger, standing and cooling for a period of time and properly improving the laser energy input density of the porous part;

and step nine, selecting laser scanning imaging equipment to scan the forming surface, transmitting data acquired by a receiver to a PC control center for calculation imaging, comparing the forming size and the forming shape according to the slice model, and dynamically adjusting parameters according to an analysis result. And when the pore sizes are inconsistent, stopping the equipment in time, and analyzing reasons and adjusting parameters according to the feedback result of the temperature field. The laser scanning imaging working speed is relatively low, so that 5 layers are selected to be formed for once surface topography imaging;

step ten, after the laser scanning is finished, the workbench descends by a powder paving thickness, the powder supply cavity ascends, the powder paving is continued, and the laser scanning forming is carried out;

step eleven, repeating the step seven and the step ten, and stopping the equipment after the part is formed;

step twelve, cooling the sample to be formed to room temperature, taking out the sample, and separating the formed sample from the formed substrate by utilizing a linear cutting process;

and thirteen, carrying out heat treatment on the formed sample, wherein the heat treatment is solid solution at 850 ℃ and aging heat treatment at 480 ℃ for 5 h.

In the second step, the product material is plastic such as ABS, PS, PP, PE and the like, the overflow edge value is 0.015-0.03 mm, the injection pressure is 30-100 MPa, and the diameter of the SLM laser spot is 0.05-0.1 mm; selecting a unit structure as a cube structure with the side length of 1-8mm, and selecting a square or a circle with the side length of 0.015-0.03 mm as a unit structure hole shape;

as a preferred embodiment of the invention, in the third step, the material maraging steel is selected, the Body Centered Cubic (BCC) structure is selected, the unit size of the lattice structure formed by the selective laser melting technology is generally 1-8mm, and the length-diameter ratio of the designed BCC unit structure rod is 4-10, then

Selecting the range of the side length L of the unit structure to be 1-8 mm;

as a preferred embodiment of the present invention, in the fourth step, the thickness of the setting layer is 0.03-0.05 mm;

in the fifth step, the laser power is 220-280W, the scanning speed is 1000-1500 mm/s, the scanning distance is 0.07-0.12 mm, the laser power is 180-220W, the scanning speed is 1500-1800 mm/s, and the scanning distance is 0.12-0.15 mm;

as a preferred embodiment of the present invention, in step six, a metal substrate is mounted;

in the fourth and fifth steps, in order to ensure the structural strength, the SLM process parameters of the porous structure forming part are not changed.

Application example two:

the embodiment is the application of the invention in the aspect of demoulding of injection products, and can better solve the phenomenon of vacuum adsorption when the injection products are demoulded.

As shown in FIG. 9, as a preferred embodiment of the present invention, a porous structure is designed on a core by selecting a suitable position, and the size parameters of a unit structure are the same as those of the first embodiment;

as a preferred embodiment of the invention, a lattice structure is designed on a mold core and a matched template and is connected with a porous structure, so that smooth air inlet is ensured, and the size parameters of the porous structure and the unit structure of the lattice structure are the same as those of the first embodiment;

as a preferred embodiment of the invention, if necessary, an air blowing device is arranged outside the lattice structure and connected with the lattice structure;

as a preferred embodiment of the present invention, the remaining steps are the same as in the first embodiment.

Application example three:

the embodiment is the application of the invention in the aspect of the in-mold decoration process of injection molding products, and can better solve the problem that the embedded sheet is easy to slide or unstable during in-mold decoration and injection molding.

As a preferred embodiment of the invention, a plurality of symmetrical parts on the part are selected for porous structure design;

further, the number of the symmetrical parts is four.

As shown in fig. 10, as a preferred embodiment of the present invention, the design of the porous structure is related to its mechanical properties and the adsorption force of the slug, and the overflow value of the material is not considered, so that the side length L of the unit of the porous structure is 1mm cube, the diameter of the pore unit is 0.3mm circular through hole, and the distance of the pore node is 1 mm;

furthermore, the side length L of the porous structure structural unit is a cube of 1-8 mm; the diameter of the pore unit is 0.3L of a circular through hole, and the distance of pore nodes is 1L; the unit structure size parameters of the lattice structure are the same as those of the first embodiment;

as a preferred embodiment of the invention, if necessary, an air suction device is arranged outside the dot matrix structure and connected with the dot matrix structure, and the air suction pressure is adjusted to avoid influencing the injection molding of the product;

as a preferred embodiment of the invention, in order to ensure the structural strength, the SLM process parameters of the porous structure forming part are not changed;

as a preferred embodiment of the present invention, the remaining steps are the same as in the first embodiment.

As a preferred embodiment of the present invention, in the first, second and third embodiments, the lattice porous structure and the dense structure are integrally formed; namely the porous structure, the lattice structure and the compact structure of the part per se are integrally formed.

The above embodiments are merely illustrative and not restrictive of the technical solutions of the present invention. Any modification or partial replacement without departing from the spirit of the present invention should be covered in the scope of the claims of the present invention.