A residual stress regulation device and method based on rolling and temperature difference stretching

Abstract

The application relates to the field of additive manufacturing, and particularly discloses a residual stress regulation device based on rolling and temperature difference stretching, wherein the device comprises a substrate, a rolling mechanism, a laser beam splitting heating mechanism and a substrate cooling mechanism; the rolling mechanism is used for reciprocating rolling on the component after each layer of additive printing, so as to reduce the residual stress of the component layer by layer; after completing the multi-layer additive printing, the laser beam splitting heating mechanism is used for splitting the laser beam into two beams, and the two beams of laser are used for heating the two sides of the component; meanwhile, the substrate cooling mechanism is used for cooling the middle part of the substrate, so that the middle part and the two sides of the component form a temperature difference, and then a reverse stress field is formed through the temperature difference thermal effect, and the residual stress generated in the additive manufacturing is further eliminated. The rolling and the temperature difference stretching are mutually coordinated, so that the residual stress in the additive component is controlled and improved.

Description

Technical Field

[0001] This application relates to the field of additive manufacturing, and in particular to a residual stress control device and method based on rolling and thermal stretching. Background Technology

[0002] Laser additive manufacturing technology is an advanced manufacturing technology that uses powder as raw material and accumulates it layer by layer through high-power laser melting and rapid solidification to directly produce metal components. It is an unsteady, extremely cold and hot transient process. During the manufacturing accumulation process, local heat input will lead to an uneven temperature field. This local thermal effect is directly manifested in the fact that residual stress is easily formed in the molten pool during solidification and subsequent cooling.

[0003] Roll forming is a common method for reducing residual stress, reducing it layer by layer. However, simply rolling layer by layer can lead to repeated residual stress due to heat accumulation during subsequent additive manufacturing processes. Furthermore, the additive component dissipates heat slowly in the middle and quickly on the sides, causing overall warping deformation. Summary of the Invention

[0004] To address the issue of significant residual stress in components during additive manufacturing, this application provides a residual stress control device and method based on rolling and thermal stretching.

[0005] The residual stress control device based on rolling and thermal stretching provided in this application adopts the following technical solution:

[0006] A residual stress control device based on rolling and thermal stretching includes:

[0007] A substrate for placing the component to be processed, with the powder feeding nozzle on the laser additive printing equipment located above the component;

[0008] The rolling mechanism is used to reciprocate rolling the component after each layer of additive printing in order to reduce the residual stress of the component layer by layer.

[0009] A laser beam splitting heating mechanism is used to split a laser beam coaxial with the powder feeding nozzle into two beams, which heat the two sides of the component respectively; the position of the laser beam splitting heating mechanism in the horizontal plane is adjustable.

[0010] A substrate cooling mechanism is used to cool the middle part of the substrate, so that a temperature difference is formed between the middle part of the component and the two sides.

[0011] Additive printing of components is performed using a powder feeding nozzle. After each layer of additive printing is completed, a rolling mechanism is used to repeatedly roll the surface of the component, ensuring that the pressure is evenly applied to each layer and reducing residual stress layer by layer. After multi-layer additive printing is completed, a laser beam splitting heating mechanism is moved below the laser beam, splitting the laser beam into two beams. The two laser beams heat the two sides of the component respectively, while a substrate cooling mechanism cools the middle of the substrate, creating a temperature difference between the middle and the sides of the component. This temperature difference generates a reverse stress field, further eliminating residual stress generated by additive manufacturing. This application employs rolling and thermal stretching in synergy to control and improve residual stress in additive components.

[0012] Furthermore, the laser beam splitting heating mechanism includes a beam splitter and a reflector assembly. The beam splitter is used to split a laser beam into two beams, and the reflector assembly is used to reflect the two split laser beams and irradiate them perpendicularly onto both sides of the component.

[0013] Furthermore, the beam splitter is a beam splitter, which is used to split a vertical laser beam into two beams, one of which is horizontal and the other is vertical; the reflector includes three plane mirrors, one of which reflects the split horizontal light and illuminates it vertically to one side of the component, and the other two plane mirrors reflect the split vertical light and illuminate it vertically to the other side of the component.

[0014] By using a beam splitter and three plane mirrors, the laser beam is split into two beams, which heat the two sides of the component respectively. In this way, the component can be heated using the laser source of the additive printing equipment without the need for an additional heat source, making the operation more convenient.

[0015] Furthermore, a horizontal first slide rail is provided on one side of the substrate, and a mounting base is slidably disposed on the first slide rail. The beam splitter and the reflector are both fixedly disposed on the mounting base.

[0016] When the mounting base slides along the first slide rail, the position of the laser beam splitting heating mechanism in the horizontal plane can be adjusted. During additive printing, the laser beam splitting heating mechanism is moved to one side of the substrate without interfering with the normal printing process of the powder feeding nozzle. After additive printing is completed, the laser beam splitting heating mechanism is moved below the laser beam. Subsequently, the laser beam splitting heating mechanism can move synchronously with the laser beam in the horizontal plane. The laser beam is split into two beams and then heats both sides of the component.

[0017] Furthermore, the substrate cooling mechanism includes a cooling water coil disposed on the bottom surface of the middle part of the substrate, and the cooling water coil is connected to a cooling water source.

[0018] Cooling water flows in the cooling water coil, exchanging heat with the substrate and cooling the middle part of the substrate.

[0019] Furthermore, the width of the substrate cooling area covered by the cooling water coil is smaller than the distance between the two laser beams after beam splitting.

[0020] In this way, the heating zone of the component and the cooling zone of the substrate do not overlap, resulting in a significant temperature difference between the middle and the sides of the substrate, thereby enhancing the effect of thermal stretching.

[0021] Furthermore, a horizontal second slide rail is provided on one side of the substrate, and the rolling mechanism includes a sliding seat slidably disposed on the second slide rail and a roller rotatably disposed on the sliding seat, the axis of the roller being orthogonal to the length direction of the second slide rail.

[0022] As the sliding seat slides along the second slide rail, the roller rotates and moves along the surface of the component, thereby rolling the component.

[0023] Furthermore, a hydraulic device is provided between the sliding seat and the roller for adjusting the height of the roller and the rolling pressure.

[0024] By adjusting the height and rolling pressure of the roller using a hydraulic device, the roller applies appropriate pressure to the surface of the component, thereby effectively reducing the residual stress of the component.

[0025] This application provides a method for controlling residual stress based on rolling and thermal stretching, comprising the following steps:

[0026] (1) Move the laser beam splitting heating mechanism and the roller to the side of the component, and then perform additive printing;

[0027] (2) After each layer of additive printing is completed, use a roller to roll back and forth on the surface of the component once;

[0028] (3) After completing the multilayer additive printing, roll forming is performed according to step (2). Then, the laser beam splitting heating mechanism is moved to the bottom of the laser beam so that the laser is split into two beams to heat the heating areas on both sides of the component. At the same time, the substrate cooling mechanism is started to cool the cooling area in the middle of the substrate.

[0029] Furthermore, in step (3), the temperature difference between the heating zone on both sides of the component and the cooling zone in the middle of the substrate is 70℃-100℃.

[0030] In summary, this application includes at least one of the following beneficial technical effects:

[0031] 1. This application combines rolling and thermal stretching. Rolling is used for single layers to apply pressure evenly to the surface of each layer, gradually reducing the accumulation of residual stress and enhancing the effect of thermal stretching. At the same time, thermal stretching is used for the entire formed component to improve the problem of repeated residual stress caused by heat accumulation in subsequent additive manufacturing processes. The two methods work together to control and improve the residual stress in the additive component.

[0032] 2. By using a beam splitter and multiple plane mirrors, the laser beam is divided into two beams, which heat the two sides of the component respectively. In this way, the component can be heated using the laser source of the additive printing equipment without the need for an additional heat source. The structure is simple and the operation is convenient. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall front view structure of an embodiment of this application;

[0034] Figure 2 This is a schematic side view of the overall structure of an embodiment of this application;

[0035] Figure 3 This is a schematic diagram of the rolling mechanism in an embodiment of this application;

[0036] Figure 4 This is a schematic diagram of the laser beam splitting heating mechanism in the embodiments of this application;

[0037] Figure 5 This is a schematic diagram of the substrate cooling mechanism in an embodiment of this application.

[0038] Reference numerals: 1-Powder feeding nozzle; 2-Clamp; 3-Mounting base; 4-Second slide rail; 5-Hydraulic device; 6-Roller; 7-Bracket; 8-First slide rail; 9-Cooling zone; 10-Heating zone; 11-Base plate; 12-Water-cooled plate; 13-Cooling water inlet; 14-Cooling water outlet; 15-Worktable; 16-Beam splitter; 17-Planar mirror; 18-Cooling water coil; 19-Component; 20-Sliding seat. Detailed Implementation

[0039] The following is in conjunction with the appendix Figure 1-5 This application will be described in further detail.

[0040] Example 1

[0041] This application discloses a residual stress control device based on rolling and thermal stretching. (Refer to...) Figure 1 and Figure 2The residual stress control device based on rolling and thermal stretching includes a worktable 15 and a substrate 11 fixedly mounted on the worktable 15, on which a component 19 to be processed is placed. The powder feeding nozzle 1 of the laser additive printing equipment is located above the component 19, the powder feeding nozzle 1 is coaxial with the laser beam, and the powder feeding nozzle 1 is movable in the horizontal plane.

[0042] Reference Figure 1 and Figure 2 A rolling mechanism is provided above component 19 for reciprocating rolling of component 19 after each layer of additive printing to reduce the residual stress of component 19 layer by layer. A laser beam splitting heating mechanism is provided above component 19 for splitting the laser beam coaxial with the powder feeding nozzle 1 into two beams, which heat the two sides of component 19 respectively; the position of the laser beam splitting heating mechanism in the horizontal plane is adjustable. A substrate cooling mechanism is provided below substrate 11 for cooling the middle part of substrate 11, so that a temperature difference is formed between the middle part and the two sides of component 19.

[0043] Additive printing is performed on component 19 through powder feeding nozzle 1. After each layer of additive printing is completed, a rolling mechanism is used to repeatedly roll the surface of component 19 to ensure that the pressure is evenly applied to each layer surface, thereby reducing residual stress layer by layer. After completing multi-layer additive printing, the laser beam splitting heating mechanism is moved below the laser beam to split the laser beam into two beams, which heat the two sides of component 19 respectively. At the same time, the substrate cooling mechanism cools the middle part of substrate 11, creating a temperature difference between the middle part and the two sides of component 19. This temperature difference heat effect generates a reverse stress field, further eliminating the residual stress generated by additive manufacturing.

[0044] This application combines rolling and thermal stretching. Rolling is used for single layers to apply pressure evenly to the surface of each layer, gradually reducing the accumulation of residual stress and enhancing the effect of thermal stretching. At the same time, thermal stretching is used for the entire formed component to improve the problem of residual stress recurring due to heat accumulation in subsequent additive manufacturing processes. The two methods work together to control and improve the residual stress in the additive component.

[0045] Reference Figure 1 and Figure 2 Two supports 7 are fixedly mounted on the base plate 11, and a horizontal first slide rail 8 and a second slide rail 4 are provided between the two supports 7. A lifting mechanism such as a lead screw can be provided on the supports 7 to adjust the height of the first slide rail 8 or the second slide rail 4 to adapt to the thickness of the component 19.

[0046] Reference Figure 1 , Figure 2 and Figure 3The rolling mechanism includes a sliding seat 20 slidably disposed on the second slide rail 4 and a roller 6 rotatably disposed on the sliding seat 20. The sliding seat 20 is provided with a power mechanism for driving the sliding seat 20 to slide along the second slide rail 4. The axis of the roller 6 is orthogonal to the length direction of the second slide rail 4.

[0047] When the sliding seat 20 slides along the second slide rail 4, the roller 6 rotates and moves along the surface of the component 19, thereby rolling the component 19. To improve the stability of the rolling process, sliding seats 20 can be provided at both ends of the roller 6 axis, and correspondingly, second slide rails 4 can be provided on both sides of the base plate 11. The sliding seats 20 at both ends of the roller 6 slide along the corresponding second slide rails 4, making the roller 6 move smoothly and thus improving the stability of the rolling process.

[0048] Furthermore, refer to Figure 3 A hydraulic device 5 is provided between the sliding seat 20 and the roller 6. The height of the roller 6 and the rolling pressure are adjusted by the hydraulic device 5 so that the roller 6 applies appropriate pressure to the surface of the component 19, thereby effectively reducing the residual stress of the component 19.

[0049] Reference Figure 1 , Figure 2 and Figure 4 A clamp 2 is slidably mounted on the first slide rail 8, and a power mechanism is provided on the clamp 2 to drive the clamp 2 to slide along the first slide rail 8. A mounting base 3 is fixedly mounted on the end of the clamp 2 away from the first slide rail 8. The laser beam splitting heating mechanism includes a beam splitter and a reflector assembly fixedly mounted on the mounting base 3. The beam splitter is used to split a laser beam into two beams, and the reflector assembly is used to reflect the two split laser beams and irradiate them perpendicularly onto both sides of the component 19.

[0050] Specifically, refer to Figure 1 and Figure 4 The beam splitter is a beam splitter 16, which is used to split a vertical laser beam into two beams, one of which is a horizontal reflected light and the other is a vertical transmitted light.

[0051] Reference Figure 1 and Figure 4 The reflective assembly includes three plane mirrors 17, each at a 45° angle to the horizontal plane. One of the plane mirrors 17 reflects the split horizontal light and illuminates one side of the component 19 vertically. The other two plane mirrors 17 are located on the same horizontal plane and their reflective surfaces are arranged opposite each other, thereby reflecting the split vertical light and illuminating the other side of the component 19 vertically.

[0052] By using a beam splitter 16 and three plane mirrors 17, the laser beam is split into two beams, which are then perpendicularly irradiated on both sides of the component 19, forming heating zones 10 on both sides of the component 19. In this way, the component 19 can be heated using the laser source of the additive printing equipment without the need for an additional heat source. The structure is simple and the operation is convenient.

[0053] To enhance the heating effect of the laser on component 19, a beam expander can be installed on the optical path that is perpendicular to component 19 after beam splitting, thereby expanding the beam irradiating component 19, increasing the irradiation area, and improving the heating effect.

[0054] As the fixture 2 and mounting base 3 slide along the first slide rail 8, the position of the laser beam splitting heating mechanism in the horizontal plane is adjustable. During additive printing, the laser beam splitting heating mechanism can be moved to one side of the substrate 11 without interfering with the normal printing process of the powder feeding nozzle 1.

[0055] After the additive printing is completed, the powder feeding is stopped, and the laser beam splitting heating mechanism is moved to below the laser beam. Then, by controlling the sliding speed of the fixture 2 on the first slide rail 8, the moving speed of the laser beam splitting heating mechanism can be controlled to keep it consistent with the moving speed of the powder feeding nozzle 1 on the laser additive printing equipment. This allows the laser beam splitting heating mechanism to move synchronously with the laser beam in the horizontal plane, achieving uniform heating of both sides of the component 19.

[0056] To improve the stability of laser beam splitting, first slide rails 8 can be provided at both ends of the mounting base 3. The two ends of the mounting base 3 slide along the corresponding first slide rails 8, thereby improving the stability of the movement of the mounting base 3 and thus improving the stability of the laser beam splitting heating mechanism in splitting the laser beam.

[0057] Reference Figure 1 and Figure 5 The substrate cooling mechanism includes a water-cooled plate 12 fixedly disposed on the bottom surface of the middle part of the substrate 11. An S-shaped winding cooling water coil 18 is disposed through the water-cooled plate 12. The cooling water coil 18 is provided with a cooling water inlet 13 and a cooling water outlet 14, wherein the cooling water inlet 13 is connected to a cooling water source.

[0058] Cooling water flows in the cooling water coil 18, exchanging heat with the substrate 11 and forming a cooling zone 9 in the middle of the substrate 11 to cool the middle part of the substrate 11. Both the water-cooled plate 12 and the cooling water coil 18 are made of materials with good thermal conductivity, such as copper.

[0059] Furthermore, refer to Figure 1 The width of the cooling area 9 of the substrate 11 covered by the cooling water coil 18 is smaller than the distance between the two laser beams after beam splitting. In this way, the heating area 10 of the component 19 and the cooling area 9 of the substrate 11 do not overlap, so that a significant temperature difference is formed between the middle and the sides of the substrate 11, thereby enhancing the effect of temperature difference stretching.

[0060] The implementation principle of the residual stress control device based on rolling and thermal stretching in this application embodiment is as follows: The component 19 is additively printed through the powder feeding nozzle 1. After each layer of additive printing is completed, the roller 6 is used to repeatedly roll the surface of the component 19 once, so that the pressure is evenly applied to each layer surface, reducing residual stress layer by layer. After completing multi-layer additive printing, the laser beam splitting heating mechanism is moved below the laser beam, splitting the laser beam into two beams. The two laser beams heat the two sides of the component 19 respectively. At the same time, the substrate cooling mechanism cools the middle part of the substrate 11, creating a temperature difference between the middle part and the two sides of the component 19. This temperature difference heat effect forms a reverse stress field, further eliminating the residual stress generated by additive manufacturing.

[0061] This application combines rolling and thermal stretching. Rolling is used for single layers to apply pressure evenly to the surface of each layer, gradually reducing the accumulation of residual stress and enhancing the effect of thermal stretching. At the same time, thermal stretching is used for the entire formed component to improve the problem of residual stress recurring due to heat accumulation in subsequent additive manufacturing processes. The two methods work together to control and improve the residual stress in the additive component.

[0062] Example 2

[0063] This application discloses a method for controlling residual stress based on rolling and thermal stretching, comprising the following steps:

[0064] (1) Move the laser beam splitting heating mechanism and roller 6 to the side of component 19, and then perform additive printing;

[0065] (2) After each layer of additive printing is completed, the roller 6 is used to roll the surface of component 19 back and forth once. During rolling, the hydraulic device 5 provides a pressure of 50kN.

[0066] (3) After each ten-layer additive printing is completed, roll forming is performed according to step (2). Then, the laser beam splitting heating mechanism is moved to the bottom of the laser beam. The moving speed of the laser beam splitting heating mechanism is then controlled to keep pace with the moving speed of the powder feeding nozzle 1 on the laser additive printing equipment. This allows the laser beam splitting heating mechanism to move synchronously with the laser beam in the horizontal plane. The laser is split into two beams, and the two laser beams heat the heating areas 10 on both sides of the component 19 to 150°C. At the same time, the substrate cooling mechanism is activated to cool the cooling area 9 in the middle of the substrate 11 to 80°C.

[0067] (4) Additive manufacturing ends, shut down the device.

[0068] The above are all preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A residual stress control device based on rolling and thermal tension, characterized in that: include: A substrate for placing the component to be processed, with the powder feeding nozzle on the laser additive printing equipment located above the component; The rolling mechanism is used to reciprocate rolling the component after each layer of additive printing in order to reduce the residual stress of the component layer by layer. A laser beam splitting heating mechanism is used to split a laser beam coaxial with the powder feeding nozzle into two beams, which heat the two sides of the component respectively; the position of the laser beam splitting heating mechanism in the horizontal plane is adjustable. A substrate cooling mechanism is used to cool the middle part of the substrate, so that a temperature difference is formed between the middle part and the two sides of the component; The laser beam splitting heating mechanism includes a beam splitter and a reflector. The beam splitter is used to split a laser beam into two beams, and the reflector is used to reflect the two split laser beams and irradiate them perpendicularly onto both sides of the component. The beam splitter is a beam splitter used to split a vertical laser beam into two beams, one of which is horizontal and the other is vertical. The reflector includes three plane mirrors, one of which reflects the split horizontal light and illuminates one side of the component vertically, and the other two plane mirrors reflect the split vertical light and illuminate the other side of the component vertically.

2. The residual stress control device based on rolling and thermal tension according to claim 1, characterized in that: A horizontal first slide rail is provided on one side of the substrate, and a mounting base is slidably disposed on the first slide rail. The beam splitter and the reflector are both fixedly disposed on the mounting base.

3. The residual stress control device based on rolling and thermal tension according to claim 1, characterized in that: The substrate cooling mechanism includes a cooling water coil disposed on the bottom surface of the middle part of the substrate, and the cooling water coil is connected to a cooling water source.

4. The residual stress control device based on rolling and thermal tension according to claim 3, characterized in that: The width of the substrate cooling area covered by the cooling water coil is smaller than the distance between the two laser beams after beam splitting.

5. The residual stress control device based on rolling and thermal tension according to claim 1, characterized in that: A horizontal second slide rail is provided on one side of the substrate. The rolling mechanism includes a sliding seat slidably disposed on the second slide rail and a roller rotatably disposed on the sliding seat. The axis of the roller is orthogonal to the length direction of the second slide rail.

6. The residual stress control device based on rolling and thermal stretching according to claim 5, characterized in that: A hydraulic device is provided between the sliding seat and the roller to adjust the height of the roller and the rolling pressure.

7. A method for controlling residual stress based on rolling and thermal stretching, characterized in that: The residual stress control device based on rolling and thermal tension as described in any one of claims 1-6 includes the following steps: (1) Move the laser beam splitting heating mechanism and the rolling mechanism to the side of the component, and then perform additive printing; (2) After each layer of additive printing is completed, the surface of the component is rolled back and forth once using a rolling mechanism; (3) After completing the multilayer additive printing, the laser beam splitting heating mechanism is moved to the bottom of the laser beam so that the laser is split into two beams to heat the heating areas on both sides of the component; at the same time, the substrate cooling mechanism is started to cool the cooling area in the middle of the substrate.

8. The residual stress control method based on rolling and thermal stretching according to claim 7, characterized in that: In step (3), the temperature difference between the heating zone on both sides of the component and the cooling zone in the middle of the substrate is 70℃-100℃.

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