Method and system for additive manufacturing of same layer hetero-materials

Abstract

The present application belongs to the field of metal part additive manufacturing, and particularly relates to a same-layer heterogeneous material SLM additive manufacturing method and system, comprising the following steps: step 1, transferring metal powder to a hot melt adhesive film; step 2, pressing the metal powder laid on the surface of the hot melt adhesive film into the hot melt adhesive film; step 3, repeating step 1 and step 2 for several times, and using different metal powder each time to transfer different patterns composed of different metal powder on the same hot melt adhesive film; and step 4, using the hot melt adhesive film with the laid powder to form. The present application adds a special porous hot melt adhesive film, which can accommodate a certain amount of metal powder inside, and the surface can still be kept flat after passing through the traction assembly, so as to ensure that the powder inside can be laid flat on the forming table. The hot melt adhesive can also ensure that the powder transferred from the photosensitive drum will not be disturbed by the charge, airflow and hot melt adhesive traction movement on the part.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of metal part additive manufacturing, and particularly relates to a same-layer heterogeneous material SLM additive manufacturing method. BACKGROUND

[0002] In the field of metal part additive manufacturing, selective laser melting (SLM) technology has high forming precision, good mechanical properties, and is a relatively advanced rapid prototyping technology. However, since SLM is a powder bed-based technology, the raw material supply mode is that the powder is sent from the powder bin in the equipment into the forming bin, and then is flattened by a scraper. The source of the raw material is only one kind of powder in the single powder bin, and it is difficult to freely add different kinds of materials during the forming process.

[0003] Therefore, a method for freely adding different materials in the same layer of powder is needed to realize same-layer heterogeneous additive manufacturing. SUMMARY

[0004] In order to make up for the deficiencies of the prior art, the present application provides a same-layer heterogeneous material SLM additive manufacturing method and system.

[0005] A same-layer heterogeneous material SLM additive manufacturing method, comprising the following steps:

[0006] Step 1, transferring metal powder to a hot melt adhesive film;

[0007] Step 2, pressing the metal powder on the surface of the hot melt adhesive film into the inside of the hot melt adhesive film;

[0008] Step 3, repeating steps 1 and 2 several times, and using different metal powders each time to transfer different patterns of different metal powders on the same hot melt adhesive film;

[0009] Step 4, using the hot melt adhesive film with the laid powder to form.

[0010] Further, the step 1 comprises: emitting a low-power laser beam from a laser towards a photosensitive drum, and scanning the single-layer slice information to the rotating photosensitive drum by the laser beam. Only the shape information of a single kind of metal powder in a single layer is transmitted by a single scan. The scanning process comprises: removing the positive charge on the surface of the photosensitive drum by the laser beam, and as the photosensitive drum rotates, the other surfaces with positive charge attract the metal powder in the powder box when passing through the powder box, so that the metal powder pattern adhered to the surface of the photosensitive drum is consistent with the single-layer slice information of the solid model.

[0011] Further, the step 2 comprises: moving the hot melt adhesive film by traction of the fixing roller and the pressure roller, so that the hot melt adhesive film passes through the transfer electrode, the discharge bulb and the photosensitive drum in sequence, the lower side of the hot melt adhesive film is applied with negative charge by the transfer electrode, the hot melt adhesive film adsorbs the metal powder on the photosensitive drum by the negative charge, then the positive charge on the photosensitive drum is removed by the discharge bulb, and finally the metal powder is pressed into the porous structure inside the hot melt adhesive film by the joint action of the fixing roller and the pressure roller, so that the pattern transfer of the same metal in the single-layer slice of the solid model is completed.

[0012] Further, in the step 2, the fixing roller heats the hot melt adhesive film to soften it.

[0013] Further, in the steps 1 and 2, when the powder is laid on the surface of the hot melt adhesive film, the single-layer slice of the shaped piece is enlarged outwardly to increase the area of the laid powder.

[0014] Further, the step 4 comprises: moving the hot melt adhesive film into the forming bin, irradiating the hot melt adhesive film with low-power laser to gasify the hot melt adhesive film, and retaining the metal powder inside the hot melt adhesive film, then irradiating the metal powder with high-power laser to melt and then solidify the metal powder to form a single-layer solid of the solid part, and repeating the step to stack the workpiece layer by layer to form a complete solid part.

[0015] Further, the hot melt adhesive film is TPU foaming material.

[0016] The application also discloses a system for realizing the same-layer heterogeneous material SLM additive manufacturing method.

[0017] A laser assembly is configured to emit laser to the photosensitive drum and the hot melt adhesive film.

[0018] The photosensitive drum is configured to transfer the metal powder to the hot melt adhesive film.

[0019] A powder box is configured to provide the metal powder for the photosensitive drum.

[0020] A traction assembly comprises a fixing roller and a pressure roller arranged oppositely, and is configured to move the hot melt adhesive film.

[0021] The discharge bulb is configured to remove the positive charge on the photosensitive drum.

[0022] The transfer electrode is configured to apply negative charge to the hot melt adhesive film.

[0023] The rubbing roller is configured to move the hot melt adhesive film.

[0024] Compared with the prior art, the present application has the following advantages:

[0025] 1) A special porous hot melt adhesive film is added, which can accommodate a certain amount of metal powder inside and keep the surface flat after passing through the traction assembly, so that the internal powder can be evenly laid on the forming table. The hot melt adhesive can also ensure that the powder transferred from the photosensitive drum will not be disturbed by the charge, air flow, and hot melt traction movement on the part.

[0026] 2) The present application can separate the powdering and melting forming in two areas at the same time by using hot melt adhesive film as the medium for powder transfer, which is more efficient than the traditional SLM equipment with only one working area.

[0027] 3) The radiation expands the powder area, ensuring that the powder at the edge will not flow due to the loss of hot melt support, affecting the forming precision. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A method flow chart for the same layer heterogeneous material SLM additive manufacturing of the present application;

[0029] Figure 2 A powder laying principle diagram for the same layer heterogeneous material SLM additive manufacturing method of the present application;

[0030] Figure 3 A forming flow chart for the same layer heterogeneous material SLM additive manufacturing method of the present application.

[0031] In the figure: low-power laser 1, laser beam 2, photosensitive drum 3, photosensitive drum surface 4, powder box 5, positive charge 6, metal powder 7, fixing roller 8, hot melt adhesive film 9, negative charge 10, discharge lamp 11, pressure roller 12, transfer electrode 13, high-power laser 14, low-power laser 15, to-be-processed hot melt adhesive pile 16, forming area hot melt adhesive pile 17, formed part 18, rubbing roller 19. DETAILED DESCRIPTION

[0032] The present application will be further described below with reference to the accompanying drawings.

[0033] Please refer to Figures 1-3 A same layer heterogeneous material SLM additive manufacturing method, the main equipment includes laser powder laying equipment and laser selective melting equipment, and the main raw materials include a special hot melt adhesive film with a foam type structure surrounded by nylon filaments and various metal powders.

[0034] The basic principle of SLM is to cut the three-dimensional model of a solid part into slices of equal thickness, and then use a high-power laser to melt and solidify the shape of the slices on a single layer of metal powder. Finally, multiple layers of metal are fused together to form a solid. The same-layer heterogeneous material is an improvement on the above principle in terms of powder laying, which allows the same layer of part to be composed of different types of powder, and the shapes of different powders in a single layer of powder can be precisely laid.

[0035] Step 1: The metal powder 7 is transferred onto the hot melt adhesive film 9 using a powder spreading device. The powder spreading device used is as follows: Figure 1 As shown, a low-power laser 1 emits a low-power laser beam 2 towards the photosensitive drum 3. The laser beam 2 scans the slice information of a single layer onto the rotating photosensitive drum 3, transmitting only the shape information of the same type of metal powder within a single layer in a single scan. After the laser beam 2 scans the photosensitive drum surface carrying a positive charge 6, the positive charge 6 is removed. As the photosensitive drum 3 rotates, other positively charged surfaces, upon passing through the powder box 5, attract the metal powder 7 from the powder box 5. This ensures that the powder pattern adhering to the surface of the photosensitive drum 3 matches the slice information of the solid model.

[0036] Step 2: Using a powder spreading device, the metal powder 7 spread on the surface of the hot melt adhesive film 9 is pressed into the interior of the hot melt adhesive film 9. The hot melt adhesive film 9 is pulled by the fixing roller 8 and the pressure roller 12 from... Figure 2 Moving from right to left, as it passes the transfer electrode 13, the underside of the hot melt adhesive film 9 acquires a negative charge 10. As the hot melt adhesive film 9 continues forward and contacts the photosensitive drum 3, the positive charge 6 on the photosensitive drum 3 is removed by the discharge bulb 11. Simultaneously, the metal powder 7 on the surface is attracted to the surface of the hot melt adhesive film 9 by the negative charge 10. Further, the hot melt adhesive film 9 continues to move to the left, and the fixing roller 8 heats the hot melt adhesive film 9 to soften it. Simultaneously, working with the pressure roller 12, it presses the metal powder 7 into the porous structure inside the hot melt adhesive film 9, completing the pattern transfer of the same metal in a single-layer slice of the solid model.

[0037] Step 3: Repeat the above process multiple times, using different metal powders 7 each time to transfer different patterns composed of different metal powders 7 onto the same hot melt adhesive film 9. To better maintain the outer contour of the single-layer molded part and prevent the metal powder 7 from losing its surrounding hot melt adhesive and changing its boundary shape (during the next selective melting step), this invention, when spreading powder onto the hot melt adhesive surface, radiates and enlarges the outer contour of the single-layer slice of the molded part outward, increasing the powder-spreading area. Selective laser melting involves melting only a specific area on a layer of spread powder. During the process of melting the metal through laser irradiation, the metal will liquefy and flow. The surrounding powder can both prevent the uncontrolled flow of molten metal and serve as raw material to replenish the molten pool. Furthermore, in this invention, when the hot melt adhesive melts, the powder at the edges loses support and flows; the extra powder spread can prevent the powder flow within the melting area.

[0038] Step 4: Use the hot melt adhesive film 9 with the powder spread above to shape the product. Figure 3 The diagram shows a laser selective melting (SDM) device. On the right, a pile of hot melt adhesive 16, which has not yet undergone SDM, is pushed into a forming chamber by a roller 19. A high-power laser 14 irradiates the hot melt adhesive film 9 with a low-power laser, causing it to vaporize. Metal particles inside the film are retained. The high-power laser 14 then irradiates the metal powder 7 with a high-power laser, melting and subsequently solidifying it to form a single layer of the solid part. The hot melt adhesive film 9 is then moved by the roller 19 to the hot melt adhesive pile 17 in the forming area on the left. Repeating these steps allows the workpiece to be layered and formed, ultimately resulting in a complete solid part.

[0039] It should be noted that in the hot melt adhesive pile 16 that has not undergone selective laser melting, the circles filled with different line shapes represent metal powders 7 of different materials. Similarly, in the molded part 18, the squares filled with different line shapes represent parts of different materials in the same layer of the molded part (circles represent metal powder before melting, and squares represent metal powder that has been melted and solidified). In the hot melt adhesive pile 17 that has undergone selective laser melting, the circles on both sides represent the area of ​​excess powder spread after the outer contour of the single-layer slice of the molded part is radiated outward and enlarged when powder is spread onto the surface of the hot melt adhesive in the first step.

[0040] The aforementioned hot melt adhesive film 9 has a thickness of 40-60 micrometers and is made of TPU foam material, which forms a porous structure on the surface and inside after foaming.

[0041] The detailed functional descriptions of the numbers in the attached diagram are as follows:

[0042] Low-power laser 1: Emits laser light based on signals from the computer, causing the photosensitive drum to carry a positive charge at the corresponding position of the shaped part slice.

[0043] Laser beam 2: By irradiation, the photosensitive drum belt is positively charged.

[0044] Photosensitive drum 3: The photosensitive drum surface is positively charged and can adsorb metal powder.

[0045] Photosensitive drum surface 4: The positively charged surface can adsorb metal powder.

[0046] Powder box 5: For storing metal powder, and the metal powder in it will be adsorbed to the positively charged photosensitive drum surface.

[0047] Positive charge 6: The positive charge on the photosensitive drum surface can adsorb metal powder.

[0048] Metal powder 7: Metal powder is the raw material for forming, which is adsorbed on the photosensitive drum surface and then transferred to the hot melt adhesive after contacting the negatively charged hot melt adhesive.

[0049] Fixing roller 8: After the metal powder and hot melt adhesive film are subjected to the heating electrode in the fixing roller and the extrusion of the pressure roller, the metal powder will be embedded in the porous structure of the hot melt adhesive film, and the hot melt adhesive film will be dried to some extent, making the combination of the hot melt adhesive film and the metal powder more firm.

[0050] Hot melt adhesive film 9: Its structure is a porous structure, which will be negatively charged after passing through the transfer electrode, and then the positively charged metal powder will be contained in the porous structure according to the digital slice information of the printing model after passing through the photosensitive drum and the fixing roller. After several adsorption steps, different types of metal powder will be adsorbed in the same layer.

[0051] Negative charge 10: After the hot melt adhesive film passes through the discharge electrode, it will be negatively charged by the electrons emitted by the electrode.

[0052] Discharge bulb 11: Placed below the hot melt adhesive film, it removes the positive charge from the photosensitive drum surface by irradiation, making it easier for the excess metal powder on the photosensitive drum surface to fall off.

[0053] Pressure roller 12: Exerting pressure on the hot melt adhesive film makes it stick to the fixing roller 8, and the metal powder attached to the surface of the hot melt adhesive film is pressed into the hot melt, making the hot melt adhesive film easier to be dried and enhancing the combination of the metal powder and the hot melt adhesive film.

[0054] Transfer electrode 13: Emitting electrons to make the hot melt adhesive film negatively charged, thereby attracting positively charged metal powder.

[0055] High-power laser 14: Can emit higher power laser, which can first heat the hot melt adhesive film to 400-500℃ to burn it completely, and then further increase the laser power to melt the metal powder and sinter it into a shape.

[0056] Hot melt glue stack 16 to be processed: containing metal powder, embedded with carbon fiber filaments around, moving to the sintering chamber under the rubbing of the rubbing roller.

[0057] Shaped area hot melt glue stack 17: moving out of the sintering chamber under the rubbing of the sintered hot melt glue roller.

[0058] Shaped part 18: the shaped part is sintered from the same layer and heterogeneous metal powder.

[0059] Rubbing roller 19: can rub the hot melt glue into or out of the forming chamber by friction.

[0060] Continued from Figure 2 and Figure 3 , a same layer and heterogeneous material SLM additive manufacturing system for implementing a same layer and heterogeneous material SLM additive manufacturing method as described above, comprising: a laser assembly, a photosensitive drum 3, a powder box 5, a traction assembly, a discharge bulb 11, a transfer electrode 13, a rubbing roller 19, the laser assembly comprising a low-power laser 1 and a high-power laser 14, the traction assembly comprising a fixing roller 8 and a pressure roller 12 arranged opposite to each other, both clamping the hot melt glue film 9, and driving the hot melt glue film 9 to advance by rotation, the low-power laser 1, the photosensitive drum 3, the powder box 5, the traction assembly, the discharge bulb 11 and the transfer electrode 13 forming a laser powder laying device, and the high-power laser 14 and the rubbing roller 19 forming a laser selective melting device.

[0061] Among them, the low-power laser 1 is located above the photosensitive drum 3, the powder box 5 is located on one side of the upper part of the photosensitive drum 3 and close to the photosensitive drum 3, the traction assembly, the discharge bulb 11 and the transfer electrode 13 are all located below the photosensitive drum 3, and are arranged in order from left to right, leaving a gap between the photosensitive drum 3 for the hot melt glue film 9 to pass through.

[0062] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of same layer hetero-material (SLM) additive manufacturing, characterized in that, The method comprises the following steps: Step 1: transferring metal powder (7) to hot melt adhesive film (9); Step 2: pressing the metal powder (7) on the surface of the hot melt adhesive film (9) into the internal porous structure of the hot melt adhesive film (9), comprising: moving the hot melt adhesive film (9) by pulling it through the fixing roller (8) and the pressure roller (12), so that the hot melt adhesive film (9) passes through the transfer electrode (13), the discharge lamp (11) and the photosensitive drum (3) in sequence, applying a negative charge (10) to the lower side of the hot melt adhesive film (9) through the transfer electrode (13), and the hot melt adhesive film (9) adsorbs the metal powder (7) on the photosensitive drum (3) by using the negative charge (10), then removing the positive charge (6) on the photosensitive drum (3) by the discharge lamp (11), and finally the fixing roller (8) and the pressure roller (12) jointly press the metal powder (7) into the internal porous structure of the hot melt adhesive film (9), completing the pattern transfer of the same metal in the single layer slice of the solid model; Step 3: repeating steps 1 and 2 several times, and using different metal powder (7) each time to transfer different patterns composed of different metal powder (7) on the same hot melt adhesive film (9); Step 4: using the hot melt adhesive film (9) with powder to form.

2. A method of SLM additive manufacturing of a same layer hetero material according to claim 1, characterized in that, The step 1 comprises: emitting a low-power laser beam (2) from a laser towards the photosensitive drum (3), and scanning the single-layer slice information onto the rotating photosensitive drum (3) by the laser beam (2), and only the shape information of the same kind of metal powder (7) in the single layer is transmitted in a single scan, and the scanning process comprises: removing the positive charge (6) on the surface of the photosensitive drum (3) by the laser beam (2), and as the photosensitive drum (3) rotates, the other surfaces with positive charge (6) attract the metal powder (7) in the powder box (5) when passing through the powder box (5), so that the metal powder pattern on the surface of the photosensitive drum (3) is consistent with the single layer slice information of the solid model.

3. A method of SLM additive manufacturing of a same layer hetero-material according to claim 1, characterized in that, In the step 2, the fixing roller (8) heats the hot melt adhesive film (9) to soften it.

4. A method of SLM additive manufacturing of a same layer hetero material according to claim 2 or 3, characterized in that, In steps 1 and 2, when powdering the surface of the hot melt adhesive film (9), the single layer slice contour of the formed part is enlarged outward, and the powdering area is increased.

5. The method of claim 1, wherein, The step 4 comprises: moving the hot melt adhesive film (9) to the forming bin, irradiating the hot melt adhesive film (9) with a low-power laser to make the hot melt adhesive film (9) gasify, and the metal powder (7) inside the hot melt adhesive film (9) is retained, and as a high-power laser is used to irradiate the metal powder (7), the metal powder (7) is melted and then solidified to form a single layer solid of the solid part, and this step is repeated, and each time a new hot melt adhesive film (9) is laid on the hot melt adhesive pile (17) in the forming area, so that the workpiece is formed by layer-by-layer stacking, and finally a complete solid part is obtained.

6. The method of claim 1, wherein, The hot melt adhesive film (9) is a TPU foaming material.

7. A system for simultaneous layering of heterogeneous materials (SLM) additive manufacturing for implementing a method for simultaneous layering of heterogeneous materials (SLM) additive manufacturing according to any one of claims 1 to 5, characterized in that It comprises: A laser assembly for emitting laser to the photosensitive drum (3) and the hot melt adhesive film (9); A photosensitive drum (3) for transferring metal powder (7) to the hot melt adhesive film (9); A powder box (5) for providing metal powder (7) for the photosensitive drum (3); A pulling assembly comprising a fixing roller (8) and a pressure roller (12) arranged opposite to each other, the pulling assembly being used to pull the hot melt adhesive film (9) to move; A discharge bulb (11) used to remove the positive charge (6) on the photosensitive drum (3); A transfer electrode (13) used to apply a negative charge (10) to the hot melt adhesive film (9); A rubbing roller (19) used to move the hot melt adhesive film (9).

Images