Support-free 3D printing method

Abstract

A support-free 3D printing method, comprising: in a first direction, dividing into a plurality of printing units a three-dimensional model of a piece to be printed, the first direction being parallel to the height direction of the three-dimensional model of said piece, and in the first direction, dividing each printing unit into a first regional portion and a second regional portion (S1); and sequentially printing the plurality of printing units from bottom to top in the first direction, wherein during printing of each printing unit, the first regional portion is printed first, and after the first regional portion has been printed, the second regional portion is divided into at most two printing layers in the first direction, and the lowest printing layer among the at most two printing layers is formed by means of scanning at a first scanning power, a first scanning speed and a first scanning interval, the bulk energy density of the lowest printing layer in each printing unit being denoted as E1, the bulk energy density of the second regional portion in each printing unit being denoted as E2, and 0.25*E1≤E2 (S2).

Description

Support-free 3D printing method

[0001] This application claims priority to the Chinese patent application No. 202411391520.X, filed on September 30, 2024, with the Chinese Patent Office, the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the field of photoelectric composite cables, for example to a support-free 3D printing method. BACKGROUND

[0003] When printing a 0° large-format overhanging part, a support structure is usually needed to be set at the bottom of the overhanging part for printing, but the setting of the support structure increases the printing time and material cost, and it is also time-consuming and laborious to remove the support structure. SUMMARY

[0004] The present application provides a support-free 3D printing method to solve the problem of setting an overhanging part when printing a 0° large-format overhanging part in the related art.

[0005] The present application provides a support-free 3D printing method, comprising: dividing a three-dimensional model of a to-be-printed part into a plurality of printing units along a first direction, the first direction being parallel to the height direction of the three-dimensional model of the to-be-printed part, and further dividing each printing unit into a first zone and a second zone along the first direction; printing the plurality of printing units in turn from bottom to top along the first direction, and when printing each printing unit, the first zone is printed first, and after the first zone is printed, the second zone is divided into at most two printing layers along the first direction, and the lowermost printing layer of the at most two printing layers is formed by scanning with a first scanning power, a first scanning speed, and a first scanning pitch; wherein the volumetric energy density of the lowermost printing layer in each printing unit is set as E1, the volumetric energy density of the second zone in each printing unit is set as E2, and 0.25*E1≤E2.

[0006] In a possible implementation, the lowermost printing layer in the second zone of each printing unit is printed in a straight line scanning manner, and the number of scanning times is one, the first scanning power is not less than 180W, the first scanning speed is not greater than 850mm / s, and the first scanning pitch is not greater than 60μm-95μm.

[0007] In a possible implementation, the volumetric energy density E1 of the lowermost printing layer in each printing unit is not less than 108J / mm 3 .

[0008] In a possible implementation, when the number of the printing units is not more than 5, the bulk energy density E2 of the second section in each of the printing units satisfies the relationship 0.25*E1≤E2, where E1 is the bulk energy density of the lowermost printing layer in the printing unit.

[0009] In a possible implementation, when the number of the printing units is more than 5, the first printing unit to the fifth printing unit satisfy the relationship 0.25*E1≤E2;

[0010] The bulk energy density of the lowermost printing layer in the fifth printing unit is set as E 51 The bulk energy density of the second section in each of the printing units after the fifth printing unit is set as E 52 , 0.25*E 51 ≤E 52 ;

[0011] The bulk energy density of the lowermost printing layer in each of the printing units after the fifth printing unit is set as E3, and the bulk energy density of the second section in each of the printing units after the fifth printing unit is set as E4, 0.55*E 51 ≤E3≤0.9*E 51 ; 0.55*E 52 ≤E4≤0.9*E 52 .

[0012] In a possible implementation, when each of the second sections has two printing layers, the uppermost printing layer in each of the second sections is scanned and formed at a second scanning power, a second scanning speed, and a second scanning pitch.

[0013] The second scanning speed is 1000-1250 mm / s, and the second scanning pitch is 0.1-0.12 mm.

[0014] In a possible implementation, after printing one of the printing units, at least 30 min is waited before continuing to print the next printing unit.

[0015] In a possible implementation, during printing of the lowermost printing layer in each of the printing units or other sections of the object to be printed, the bulk energy density is changed by adjusting the layer thickness of the current printing section.

[0016] In a possible implementation, after printing of the second section in each of the printing units, the bulk energy density is changed by maintaining the scanning power unchanged and adjusting the spot diameter.

[0017] In a possible implementation, after ten of the printing units are printed each time, the method further comprises: detecting a temperature difference between the second section of the first printing unit and the second section of the last printing unit among the ten printing units, and in response to the temperature difference exceeding 40℃, stopping printing until the temperature difference does not exceed 40℃ and then resuming printing. BRIEF DESCRIPTION OF DRAWINGS

[0018] Fig. 1 is a flowchart of a support-free 3D printing method according to an embodiment of the present application.

[0019] Fig. 2 is a schematic diagram of a workpiece to be printed according to an embodiment of the present application.

[0020] Fig. 3 is a schematic diagram of a printing unit according to an embodiment of the present application.

[0021] Fig. 4 is a photograph of a workpiece formed by using a printing method.

[0022] Fig. 5 is a photograph of a workpiece formed by using another printing method.

[0023] Fig. 6 is a photograph of a workpiece formed by using another printing method.

[0024] Fig. 7 is a photograph of a workpiece formed by using a support-free 3D printing method according to an embodiment of the present application.

[0025] Fig. 8 is a photograph of a workpiece formed by using a support-free 3D printing method according to an embodiment of the present application.

[0026] Main element symbol explanation: support-free 3D printing method 100 first direction Z workpiece to be printed 1 printing unit 10 first section 11 second section 12 DETAILED DESCRIPTION

[0027] The following description will describe the present application with reference to the accompanying drawings. The drawings shown in the accompanying drawings are exemplary embodiments of the present application. However, the present application can be implemented in many different forms, and should not be interpreted as being limited to the exemplary embodiments set forth herein. These exemplary embodiments are provided in order to make the present application thorough and complete, and to adequately convey the ratio range of the present application to those skilled in the art. Like reference numerals indicate the same or similar components.

[0028] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Furthermore, to the extent that the terms "including", "includes", "having", "has", "a", "an", "one" or "said" are used in this specification and / or claims, they are intended to be inclusive (meaning that there can be additional items) and / or to be construed as functionally open-ended (meaning that an item or items can have additional functions), unless otherwise indicated.

[0029] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0030] The specific embodiments of the present application will be described below with reference to the accompanying drawings.

[0031] As shown in FIGS. 1-3, the present embodiment provides a support-free 3D printing method 100 applied in the field of metal 3D printing to print a metal printed part in a support-free manner. It can be understood that in other embodiments, the support-free 3D printing method 100 of the present application can also be applied in the field of non-metal printing, and the application field is not limited in the present application. The support-free 3D printing method 100 comprises the following steps.

[0032] S1, along a first direction, divide a three-dimensional model of a to-be-printed part 1 into a plurality of printing units 10, the first direction being parallel to the height direction of the three-dimensional model of the to-be-printed part 1, and along the first direction, further divide each printing unit 10 into a first zone 11 and a second zone 12.

[0033] In this step, the structures of the plurality of printing units 10 are substantially the same, and the plurality of printing units 10 all have a suspended structure and a non-suspended structure. The first zone 11 is the non-suspended structure of the printing unit 10, and the second zone 12 is the suspended structure of the printing unit 10.

[0034] In the embodiment, the shape of the to-be-printed piece 1 is cylindrical, and the to-be-printed piece 1 is divided into a plurality of printing units 10 along the height direction thereof, and the shape of each printing unit 10 is also cylindrical. The first section 11 is a cylindrical structure with both ends open and hollow inside, and the second section 12 is arranged on the top end surface of the first section 11, and the opening of the top end of the first section 11 is closed by the second section 12. The shape of the second section 12 is a circular disc, and along the first direction, the top end surface and the bottom end surface of the second section 12 are arranged parallel to each other, and the normal lines of the top end surface and the bottom end surface of the second section 12 are parallel to the first direction, that is, the second section 12 is a 0° large-format overhanging structure.

[0035] It can be understood that in other embodiments, the to-be-printed piece 1 can also have only one 0° large-format overhanging structure or other structures, and the structure of the to-be-printed piece 1 provided by the present application is only used to illustrate the printing principle of the 0° large-format overhanging structure of the present application, and according to the printing principle of the 0° large-format overhanging structure provided by the present application, a person skilled in the art can realize the printing of the to-be-printed piece 1 with a 0° large-format overhanging structure of other shapes or structures.

[0036] S2, sequentially print the plurality of printing units 10 from bottom to top along the first direction, and when printing each printing unit 10, first print the first section 11, and after printing the first section 11, divide the second section 12 into at most two printing layers along the first direction, and the lowermost printing layer of the at most two printing layers is scanned and formed at a first scanning power, a first scanning speed, and a first scanning pitch; wherein the bulk energy density of the lowermost printing layer in each printing unit 10 is set as E1, the bulk energy density of the second section 12 in each printing unit 10 is set as E2, and 0.25*E1≤E2.

[0037] In the embodiment, the first section 11 is a non-overhanging structure of the printing unit 10, which is a conventional printing piece, and the first section 11 can be printed and formed by using the existing printing method, and the printing method and the plurality of parameters involved are not limited in the present application.

[0038] After printing the first section 11, the second section 12 is continuously printed with the first section 11 as the base after powdering on the top end surface of the first section 11, that is, the second section 12 as a 0° large-format overhanging structure is continuously printed on the basis of the printed and formed first section 11.

[0039] In the embodiment, the second section 12 is divided into two printing layers, and the two printing layers are stacked along the first direction. After printing the first section 11, the lowermost printing layer is first printed, and after printing the lowermost printing layer, the other printing layer above it is printed, thereby completing the printing of the entire second section 12.

[0040] The lowermost printing layer is the forming layer of the overhanging surface, and it needs to be printed on the open end of the first section 11 which is open at both ends and hollow inside. Therefore, when printing the lowermost printing layer, it is necessary to reasonably control a plurality of parameters during printing to ensure that the lowermost printing layer after forming does not have problems such as warping or delamination from the first section 11.

[0041] In the present embodiment, when printing the lowermost printing layer in the second section 12 of the plurality of printing units, the filling of the overhanging surface is performed in a straight line scanning manner, and the number of scanning times is one. The first scanning power is not less than 180W, the first scanning speed is not greater than 850mm / s, and the first scanning pitch is not greater than 60μm-95μm. Among them, the first scanning pitch is not more than the diameter of one light spot.

[0042] In addition, the volumetric energy density E1 of the lowermost printing layer of the second section 12 in each printing unit 10 is not less than 108J / mm 3 .

[0043] In this way, when printing the lowermost printing layer in the second section 12 of the plurality of printing units, the present application uses higher laser power under the premise of ensuring higher volumetric energy density input, and cooperates with slower scanning speed and relatively smaller scanning pitch to ensure that the plurality of sections of the lowermost printing layer can be closely connected during the forming process and will not have problems such as warping, so as to ensure the smooth forming of the overhanging surface.

[0044] In the present embodiment, if the number of printing units 10 is not more than 5, the volumetric energy density E2 of the second section 12 in each printing unit 10 and the volumetric energy density E1 of the lowermost printing layer in the printing unit 10 satisfy the relationship 0.25*E1≤E2.

[0045] That is, when planning the printing parameters of the second section 12, by controlling the relationship between the total volumetric energy density E2 input by the second section 12 and the volumetric energy density E1 of the lowermost printing layer in the second section 12 during printing, it is ensured that the lowermost printing layer and other printing layers of the second section 12 have good metallurgical bonding effect, and phenomena such as delamination or falling off during printing are avoided.

[0046] For example, the value of E1 only needs to satisfy not less than 108J / mm 3 , and its value can be selected according to the actual printing requirements to input a suitable volumetric energy density. Correspondingly, the value of E2 only needs to satisfy 0.25*E1≤E2, and its value can be selected according to the actual printing requirements to input a suitable volumetric energy density.

[0047] In other embodiments, if the number of printing units 10 exceeds 5, i.e. the number of printing units 10 is 6 or 7 or the like, the first printing unit 10 to the fifth printing unit 10 satisfy the relationship 0.25*E1≤E2.

[0048] In addition, for the convenience of subsequent reading, the volume energy density of the lowest printing layer in the fifth printing unit 10 is set as E 51 The volume energy density of the second section 12 in each printing unit 10 after the fifth printing unit 10 is set as E 52 , 0.25*E 51 ≤E 52 .

[0049] The volume energy density of the lowest printing layer in each printing unit 10 after the fifth printing unit 10 is set as E3, and the volume energy density of the second section 12 in each printing unit 10 after the fifth printing unit 10 is set as E4, 0.55*E 51 ≤E3≤0.9*E 51 , 0.55*E 52 ≤E4≤0.9*E 52 .

[0050] In this way, by controlling the relationship between the total volume energy density input by the second section 12 in the first five printing units 10 and the volume energy density of the lowest printing layer in the second section 12 at the time of printing, the structural stability of the entity formed by the lowest five printing units 10 is ensured to be better, and when the subsequent printing units 10 continue to print on the basis of the entity formed by the five printing units 10, the input of the volume energy density is controlled on the basis of the volume energy density of the second section 12 in the fifth printing unit 10 and the lowest printing layer in the second section 12, ensuring that the formation of the sixth and subsequent printing units 10 is more stable.

[0051] It is worth noting that in planning the printing parameters, in addition to directly controlling the input of the volume energy density according to the above formula of the volume energy density, the volume energy density can also be indirectly changed by controlling other parameters. The specific implementation is described as follows:

[0052] In some embodiments, when printing the lowest printing layer in each printing unit 10 or other sections of the object 1 to be printed, the volume energy density is changed by adjusting the layer thickness of the current printing section. For example, the thickness of the current layer can be increased or decreased by 30-100 μm.

[0053] In some embodiments, after printing the second section 12 in each printing unit 10, the bulk energy density is changed by maintaining the scanning power unchanged and adjusting the spot diameter. For example, the spot diameter is increased to be larger than the range of 60-95 μm corresponding to the first scanning pitch. In this way, the area of the single spot is increased, so that the input bulk energy density is decreased to realize the adjustment of the bulk energy density, while the input of the scanning power is unchanged.

[0054] Both of the above-mentioned control methods should be regarded as an embodiment of the bulk energy density adjustment of the present application.

[0055] In the present embodiment, as mentioned above, each second section 12 is divided into two printing layers. After printing the lowermost printing layer of each second section 12 according to the above-mentioned method, the upper printing layer is continuously printed based on the lowermost printing layer. The upper printing layer is also printed by linear scanning, and is scanned once. In addition, the upper printing layer is scanned to be formed by the second scanning power, the second scanning speed, and the second scanning pitch.

[0056] The second scanning speed is 1000-1250 mm / s, and the second scanning pitch is 0.1-0.12 mm. Both of the second scanning speed and the second scanning pitch are larger than the first scanning speed and the first scanning pitch. This is based on the fact that the lowermost printing layer in the second section 12 has been printed as the main overhanging layer, and the subsequent upper printing layer is continuously printed based on the printed overhanging layer, which can be printed by a faster scanning speed and a larger scanning pitch, so as to improve the printing speed while ensuring the forming quality.

[0057] It can be understood that in other embodiments, if the thickness of the second section 12 is small, the second section 12 can be directly regarded as one printing layer, i.e. the second section 12 is not divided into two printing layers. At this time, when printing the second section 12, the second section 12 can be printed according to the method of printing the lowermost printing layer of the second section 12, which will not be described herein again.

[0058] In the present embodiment, after printing one printing unit 10, at least 30 min is waited before printing the next printing unit 10. After printing one printing unit 10, the heat of the just-printed printing unit 10 is high, and it is necessary to wait for a certain time for heat dissipation before printing the next printing unit 10 based on the printing unit 10, so as to avoid the problem that the second section 12 of the next printing unit 10 is deformed after being heated by the higher-temperature previous printing unit 10 when printing the next printing unit 10, and the next printing unit 10 is warped.

[0059] After printing ten printing units 10 each time, the temperature difference between the second part 12 of the first printing unit 10 and the second part 12 of the last printing unit 10 in the ten printing units 10 is detected. If the temperature difference exceeds 40°C, printing is stopped until the temperature difference does not exceed 40°C, and then printing is resumed. This ensures that the upper and lower parts of the formed workpiece do not deform due to excessive temperature difference.

[0060] In summary, the support-free 3D printing method 100 of the present application ensures that the lowermost printing layer of the second part 12 does not warp due to excessive stress after printing. At the same time, the present application controls the bulk energy density and other printing parameters during printing of the second part 12 to ensure that the formed second part 12 has good bonding effect with other structures, avoiding delamination or falling off, thereby realizing printing of large-format 0° support-free workpieces. In addition, when printing structures with a minimum forming angle of 0° using the support-free 3D printing method 100 of the present application, it is not necessary to print by setting a support structure or controlling the included angle between the laser beam and the formed printing piece. The present application can quickly realize the direct formation of printing pieces with a suspended surface diameter of ≥100mm without adding supports. The present application can be well applied to the case where low-angle parts inside complex structures are not convenient to remove supports, and can improve printing efficiency, reduce material cost, and reduce post-processing time.

[0061] To better illustrate the printing quality of the workpiece formed by the support-free 3D printing method 100 of the present application, the following examples are provided.

[0062] As shown in FIG. 4, the lowermost printing layer of the second part 12 of the printing unit 10 of the formed piece in FIG. 4 has a bulk energy density E1 less than 108 J / mm 3 , resulting in direct cracking of the printing piece.

[0063] As shown in FIG. 5, the lowermost printing layer of the second part 12 of the printing unit 10 of the formed piece in FIG. 5 has a bulk energy density E1 less than 108 J / mm 3 , resulting in problems such as warping of the formed structure due to insufficient tension.

[0064] As shown in FIG. 6, the lowermost printing layer of the second part 12 of the printing unit 10 of the formed piece in FIG. 6 has a bulk energy density E1 greater than 108 J / mm 3However, the second zone 12 in the printing unit 10 has a bulk energy density E2 which does not satisfy the relationship 0.25*E1≤E2 with the bulk energy density E1 of the lowermost printing layer in the printing unit 10, resulting in the problem that the lower surface of the printed part is intact but the solid part is cracked.

[0065] As shown in Figs. 7 and 8, the printed parts in Figs. 7 and 8 are formed by the support-free 3D printing method 100 of the present application and have no cracking problem and no surface lifting.

[0066] It is worth noting that the printing method used by the printed parts in Figs. 4, 5 and 6 above is compared with the support-free 3D printing method 100 of the present application in Figs. 7 and 8, i.e. in addition to the above-mentioned parameters, other printing steps and printing parameters are set the same as the support-free 3D printing method 100 of the present application.

[0067] In the foregoing, the specific embodiments of the present application are described with reference to the accompanying drawings. However, those skilled in the art can understand that various modifications and replacements can be made to the specific embodiments of the present application without deviating from the ratio range defined by the present application. These modifications and replacements are all within the ratio range defined by the present application.

Claims

1. A support-free 3D printing method, comprising: dividing a three-dimensional model of a to-be-printed object into a plurality of printing units along a first direction, the first direction being parallel to a height direction of the three-dimensional model of the to-be-printed object, and each printing unit being further divided into a first section and a second section along the first direction; printing the plurality of printing units in turn from bottom to top along the first direction, and printing the first section first when printing each printing unit, and after the first section is printed, dividing the second section into at most two printing layers along the first direction, and the lowermost printing layer of the at most two printing layers being formed by scanning with a first scanning power, a first scanning speed, and a first scanning pitch; wherein a volume energy density of the lowermost printing layer in each printing unit is set as E1, a volume energy density of the second section in each printing unit is set as E2, and 0.25*E1≤E2.

2. The unsupported 3D printing method of claim 1, wherein, The lowermost printing layer of the second section of each printing unit is printed in a linear scanning manner, and the number of scanning times is one, the first scanning power is not less than 180 W, the first scanning speed is not greater than 850 mm / s, and the first scanning pitch is not greater than 60 μm-95 μm.

3. The free-standing 3D printing method of claim 1, wherein, The body energy density E1 of the lowermost printing layer in each of the printing units is not less than 108 J / mm 3 .

4. The free-standing 3D printing method of claim 1, wherein, In the case that the number of printing units is not more than 5, the volume energy density E2 of the second section in each printing unit and the volume energy density E1 of the lowermost printing layer in the printing unit satisfy the relationship 0.25*E1≤E2.

5. The free-standing 3D printing method of claim 1, wherein, In the case that the number of printing units is more than 5, the first printing unit to the fifth printing unit satisfy the relationship 0.25*E1≤E2. set the volumetric energy density of the print layer in the fifth said printing unit to E 51 set the volumetric energy density of the second section in each said printing unit after the fifth said printing unit to E 52 0.25*E 51 ≤E 52 ; the volumetric energy density of the lowermost printing layer in each of the printing units after the fifth printing unit is set to E3, the volumetric energy density of the second section in each of the printing units after the fifth printing unit is set to E4, 0.55*E 51 ≤ E3 ≤ 0.9*E 51 ; 0.55*E 52 ≤ E4 ≤ 0.9*E 52 .

6. The free-standing 3D printing method of claim 1, wherein, In the case that each second section is divided into two printing layers, the uppermost printing layer in each second section is formed by scanning with a second scanning power, a second scanning speed, and a second scanning pitch. Wherein the second scanning speed is 1000-1250 mm / s, and the second scanning pitch is 0.1-0.12 mm.

7. The free-standing 3D printing method of claim 1, wherein, After printing one printing unit, at least 30 min is waited before printing the next printing unit.

8. The free-standing 3D printing method of claim 1, wherein, During the process of printing the lowermost printing layer in each printing unit or other sections of the to-be-printed object, the volume energy density is changed by adjusting the layer thickness of the current printing section.

9. The free-standing 3D printing method of claim 1, wherein, After printing the second section in each printing unit, the volume energy density is changed by maintaining the scanning power unchanged and adjusting the spot diameter.

10. The free-standing 3D printing method of claim 1, further comprising, after each ten of said printing units are printed, the method further comprising: The temperature difference between the second section of the first printing unit and the second section of the last printing unit of the ten printing units is detected, and in response to the temperature difference exceeding 40℃, the printing is stopped until the temperature difference does not exceed 40℃ and the printing is resumed.

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