Device and method for controlling edge precision of friction stir extrusion solid-phase additive deposition layer

Abstract

The present invention relates to a device and method for controlling the edge precision of a stir friction extrusion solid-phase additive deposition layer, which belongs to the field of additive manufacturing technology, and includes a hollow stirring head, which can rotate, and a through hole is arranged at the central axis thereof for filling raw materials; four split sleeves are sleeved around the hollow stirring head, and the four split sleeves can move up and down independently. The present invention restricts the side wall forming of the additive layer, suppresses the generation of flash, arc-shaped side walls and semi-cylindrical materials at both ends of the additive layer, thereby reducing the subsequent cutting amount and achieving near-net forming of the component; by restricting the flow of plasticized material to the surroundings, the additive layer at the center and the edge is made denser, and the mechanical properties of the additive layer as a whole and the side wall are improved; it can realize multi-layer additives in the vertical plane and multi-pass additives in the horizontal plane, and can also realize precise forming of the side wall without changing the device, thereby improving the flexibility of the device.

Description

Technical Field

[0001] The invention relates to a device and method for controlling edge accuracy of a friction stir extrusion solid-phase additive deposition layer, belonging to the technical field of additive manufacturing. Background Art

[0002] Additive manufacturing is a manufacturing technology that forms an integrated component by accumulating layers from the bottom up. Compared with traditional subtractive manufacturing, additive manufacturing is simpler in process, can greatly improve production efficiency, and can also reduce the amount of material removed in subsequent cutting steps to avoid material waste.

[0003] At present, the metal additive manufacturing processes based on melting mainly include arc additive manufacturing, electron beam selective melting, laser near-net shaping, laser selective melting, etc. Since the material melting and solidification process occurs during the additive process, the additive components are prone to thermal cracks, pores and alloy element evaporation. In addition, the additive process has a high temperature, and repeated heat accumulation can easily cause the workpiece to deform and generate large residual stress.

[0004] Since the processing temperature of solid-phase additive manufacturing is lower than the melting point, it can effectively avoid the inherent defects of melting-based additive processes. At present, the main solid-phase additive methods include ultrasonic additive manufacturing, cold spray additive manufacturing and stir friction additive manufacturing. Ultrasonic additive manufacturing uses ultrasonic vibration to cause severe plastic deformation and recrystallization at the interface between thin plates to achieve metallurgical bonding, which is similar to a thin plate lamination process. The production efficiency of this additive method is limited by the power of the ultrasonic transducer, and subtractive processing is still required to achieve the target accuracy in the future. Cold spray additive manufacturing accelerates the powder to supersonic speed and then hits the substrate, causing plastic deformation and deposition on the surface of the substrate to achieve additive. However, there are many pores inside the parts deposited by this method, and it is difficult to achieve complete bonding between particles, resulting in poor mechanical properties of the parts.

[0005] Stir friction additive manufacturing is based on the principle of stir friction welding. According to the process characteristics, it is divided into stir friction additive manufacturing process with plate as raw material, stir friction deposition process with rod or powder as raw material, and friction surface deposition additive manufacturing process with consumable rod as raw material. Among them, the principle of stir friction additive manufacturing process with plate as raw material is the same as stir friction lap. The stirring action of the stirring head causes plastic deformation of the interface between the plates to obtain metallurgical bonding. This additive method also has the problem of low material utilization rate, and each feeding needs to be re-clamped. After the additive is completed, subtractive processing is required, and the additive efficiency is low. The friction surface deposition additive manufacturing process generates heat by rotating the consumable rod and the substrate to plasticize the end of the rod, and deposits it on the substrate under the extrusion of the axial force. However, if the diameter of the consumable rod is to be reduced to improve the additive accuracy, the reduction of friction heat generation will lead to molding difficulties, and the slender rod is prone to instability under the extrusion of the axial force, resulting in instability in the additive process. Therefore, it is difficult for this process to achieve high additive accuracy.

[0006] The friction stir deposition additive manufacturing process uses a hollow stirring head. The raw material passes through the through hole on the axis of the hollow stirring head and enters under the shoulder under the extrusion of the axial forging force. The friction heat generated by the rotating shoulder is used to plasticize the raw material, and an additive layer is formed under the extrusion of the shoulder. Since the friction heat generated by the shoulder is the main source of heat, there is no limit on the diameter of the raw material, which can be a rod, wire or powder. However, since the plasticized material is not constrained around during the additive process, the plasticized material will expand to the surroundings to form a loose arc-shaped side wall, resulting in weak bonding of the edge and accompanied by the generation of flash. At the same time, the two ends of the additive layer of the friction stir deposition are usually semi-cylindrical materials, which cannot be effectively utilized, resulting in the need to remove flash, uneven side walls and semi-cylinders through subsequent cutting in production, which undoubtedly reduces production efficiency and causes material waste. Therefore, it is urgent to develop a side wall precision forming method to reduce the subsequent cutting amount and achieve near-net forming of friction stir deposition components.

[0007] Patent document CN117428316A discloses a static shoulder friction stir additive device with a discharge cavity. By setting a fan-shaped cavity outlet on the static shoulder of the wire feeding friction stir additive device to limit the extrusion of the additive layer from the outlet, a more compact additive layer can be formed, and the side wall of the additive layer can be accurately formed, avoiding the formation of arc-shaped side walls. However, since both sides of the additive layer are restricted, this method cannot perform lateral multi-pass deposition, nor can it solve the problem of material waste of the semi-cylinders at both ends of the additive layer. At the same time, the fan-shaped cavity outlet is closer to the center due to the narrow end, which is easy to cause material blockage. Summary of the invention

[0008] In view of the shortcomings of the prior art, the present invention provides a device and method for controlling the edge accuracy of a stir friction extrusion solid-phase additive deposition layer, which limits the side wall forming of the additive layer, suppresses the generation of flash, arc-shaped side walls and semi-cylindrical materials at both ends of the additive layer, thereby reducing the subsequent cutting amount and achieving near-net forming of the component; by limiting the flow of plasticized material to the surroundings, the additive layer in the center and the edge is made denser, and the mechanical properties of the additive layer as a whole and the side wall are improved; it can realize multi-layer additive in the vertical plane and multi-pass additive in the horizontal plane, and can also realize precise forming of the side wall without changing the device, thereby improving the flexibility of the device.

[0009] The present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a device for controlling edge accuracy of a deposited layer of a friction stir extrusion solid-phase additive material, comprising a hollow stirring head, the hollow stirring head being rotatable under the drive of a main shaft, a through hole being arranged at the central axis thereof for filling raw materials such as rods, wires or powders;

[0011] Four split sleeves are sleeved around the hollow stirring head. The four split sleeves can move up and down independently under the control of the screw transmission mechanism on the main shaft housing, and the translation in other directions is restricted. The split sleeve includes a cavity wall part and a matching part. The cavity wall part is a quadrangular prism structure; the matching part is a triangular prism structure, including cylinder A, cylinder B and a 1 / 4 cylindrical surface, wherein cylinder A overlaps with the cavity wall part, cylinder B is exposed to the outside, and the 1 / 4 cylindrical surface is smoothly connected to the cavity wall part; the four split sleeves are connected end to end in a way that the cylindrical surface B of the matching part overlaps with the cavity wall part to form the entire sleeve;

[0012] The height difference between the bottom of the cavity wall portion and the bottom of the matching portion is the thickness of one additive layer.

[0013] Preferably, the through hole of the hollow stirring head is a circular through hole or a square through hole.

[0014] Preferably, the lower end surface of the hollow stirring head is a shaft shoulder, which is the main part that generates heat by friction with the raw material during the friction stirring deposition process;

[0015] In order to prevent the plasticized material from being blocked at one end of the through hole close to the shaft shoulder, the end of the through hole close to the shaft shoulder is configured to expand outwards to reserve space for the deformation of the plasticized material.

[0016] Preferably, adjacent split sleeves are clearance-fitted, and 1 / 4 cylindrical surfaces of the four split sleeves constitute a circular cavity of the entire sleeve, that is, a complete cylindrical surface, and the circular cavity is clearance-fitted with the outer side surface of the hollow stirring head.

[0017] Preferably, the up and down movement of the four split sleeves is switched only between two heights, namely an initial height and a non-forming height. The initial height is switched to the non-forming height by upward movement, and the height difference between the initial height and the non-forming height is the thickness of one additive layer.

[0018] Preferably, when the split sleeve is at an initial height, the lower bottom surface of the triangular prism of the split sleeve mating part and the shoulder of the hollow stirring head are in the same plane, and the lower end surface of the cavity wall part of the split sleeve and the upper surface of the substrate or the previous additive layer are in the same plane; in the entire sleeve, the bottom inner walls of the four split sleeve cavity wall parts, the bottom surface of the mating part, the upper surface of the substrate or the additive layer, and the lower end surface of the hollow stirring head constitute a closed cavity with a right parallelepiped having a square bottom surface, the height of the cavity is equal to the thickness of an additive layer, and the side length of the cavity is equal to the diameter of the hollow stirring head.

[0019] Preferably, when the split sleeve is at a non-forming height, the lower end surface of the cavity wall portion of the split sleeve and the shoulder of the bottom surface of the hollow stirring head are in the same plane.

[0020] In a second aspect, the present invention provides a working method based on the above-mentioned stir friction extrusion solid phase additive deposition layer edge precision control device, which can realize multi-layer additive manufacturing in a vertical plane, comprising the following steps:

[0021] (1) At the initial moment, the four split sleeves are all at the initial height, that is, the bottom of the cavity wall parts of the four split sleeves are all in contact with the substrate, and the bottom inner wall of the cavity wall parts of the four split sleeves, the bottom surface of the matching part, the upper surface of the substrate, and the lower end surface of the hollow stirring head constitute a closed cavity. The raw material in the hollow stirring head is pressed into the closed cavity under the extrusion of the axial upsetting force, and the raw material is plasticized by the friction heat generated by the rotation of the shaft shoulder and the raw material. The plasticized material is extruded and formed under the constraint of the cavity wall;

[0022] (2) Before the first additive layer starts to be fed, the split sleeve on the side opposite to the feeding direction moves upward to the non-forming height to avoid hindering the backward movement of the additive layer during feeding. Then, the hollow stirring head and the four split sleeves start to feed as a whole to complete the deposition of the first additive layer;

[0023] (3) After the first feeding is completed, the other three split sleeves and the hollow stirring head move upward at the same time by a displacement equal to the thickness of the additive layer. At this time, the four split sleeves have reached the initial height of the second additive layer, and the plasticized material is again enclosed in the closed cavity for extrusion molding;

[0024] (4) Before the second layer starts to be fed, the split sleeve on the side opposite to the feeding direction moves upward to the non-forming height, and then starts to feed to complete the deposition of the second additive layer;

[0025] (5) Repeat steps (2) to (4) until the sum of the thicknesses of all additive layers reaches the target height, completing multi-layer additive manufacturing in the vertical plane.

[0026] Preferably, the present invention can also realize multi-pass additive manufacturing in a horizontal plane, comprising the following steps:

[0027] S1: At the initial moment, the four split sleeves are at the initial height, that is, the bottom of the cavity wall parts of the four split sleeves are all in contact with the substrate, and the bottom inner wall of the cavity wall parts of the four split sleeves, the bottom surface of the matching part, the upper surface of the substrate, and the lower end surface of the hollow stirring head constitute a closed cavity. The raw material in the hollow stirring head is pressed into the closed cavity under the extrusion of the axial upsetting force, and the raw material is plasticized by the friction heat generated by the rotation of the shaft shoulder and the raw material, and the plasticized material is extruded and formed under the constraint of the cavity wall;

[0028] S2: Before the first feed starts, the split sleeve on the side opposite to the feed direction moves upward to the non-forming height, and then starts feeding to complete the deposition of the first additive layer;

[0029] S3: Before turning from the first pass to the second pass, the feeding direction is rotated 90° toward the second pass, and the split sleeve on the side opposite to the feeding direction moves upward to the non-forming height, and then starts feeding to complete the deposition of the transition layer from the first pass to the second pass. At this time, two split sleeves are at the non-forming height;

[0030] S4: Before the second pass starts feeding, the split sleeve in the opposite direction to the second pass feeding direction moves upward to the non-forming height, and then starts feeding to complete the deposition of the second additive layer. At this time, three split sleeves are at the non-forming height; since the split sleeve at the non-forming height during the first additive pass is still at the non-forming height during the second additive pass, and the split sleeve is located on the same side as the second pass feeding direction, the split sleeve cannot suppress the formation of the arc-shaped wall and flash of the second additive layer near the feeding direction end;

[0031] S5: In order to remove the arc-shaped wall and flash formed by the second additive layer, the split sleeve at the initial height is moved upward to the non-forming height while the hollow stirring head is kept rotating. At this time, the four split sleeves are all at the non-forming height. Then, the feeding direction is rotated 90° toward the initial deposition position of the first additive layer, and the four split sleeves and the hollow stirring head are moved to the initial deposition position of the first additive layer.

[0032] S6: The split sleeve on the same side as the second feeding direction moves downward to the initial height, and then the hollow stirring head and the four split sleeves are simultaneously fed to the initial deposition position of the third additive layer, and the arc-shaped wall surface and flash are cut off by using the cavity wall edge of the split sleeve;

[0033] S7: After moving to the initial deposition position of the third additive layer, the split sleeve farthest from the second additive layer moves downward to the initial height to perform initial deposition of the third additive layer;

[0034] S8: Then repeat steps S4 to S7, and complete subsequent material addition by flexibly switching the heights of the four split sleeves until the target size requirement is reached.

[0035] Preferably, the angle between the inner side and the outer side of the cavity wall of the split sleeve cavity wall is α Use right angles or acute angles.

[0036] For any details not provided in the present invention, please refer to the prior art.

[0037] The beneficial effects of the present invention are:

[0038] 1. Compared with the conventional friction stir deposition technology without constraints on all sides, the device of the present invention adopts four split sleeves that can move up and down respectively to form a closed cavity with the upper and lower surfaces, constraining the plasticized material on all sides, making the deposition process similar to an extrusion process, improving the density of the additive layer, inhibiting the formation of arc-shaped walls and flash, forming vertical walls, achieving precise molding of the side walls, and reducing the amount of subsequent cutting.

[0039] 2. The device of the present invention can flexibly switch the heights of the four split sleeves, so that the four sides or three sides of the plasticized material are always constrained by the wall of the additive layer or the split sleeve cavity wall; since the cavity bottom formed by the four split sleeve cavity walls and the upper and lower surfaces is a square, the device can avoid the formation of semi-cylinders at both ends of the additive layer, avoid the generation of invalid volume, and achieve near-net molding of stir friction deposition components.

[0040] 3. The device of the present invention can adapt to different additive paths, such as multi-layer additives in the vertical plane and multi-pass additives in the horizontal plane, without changing the device, because the four split sleeves can move up and down respectively. Continuous additives can be performed without changing the device. For example, when performing multi-pass additives in the horizontal plane, if there is an overlap between adjacent passes, one side of the split sleeve can be at the initial height to limit the side wall forming, and the other side can be at a non-forming height to avoid the split sleeve colliding with the additive layer of the previous pass when moving horizontally.

[0041] 4. In the present invention, since a closed cavity can be formed during the additive process, when powder is used as raw material, it can prevent the powder from scattering during filling and feeding, thereby avoiding corresponding material loss. In addition, since the closed cavity isolates the metal powder inside from the outside world, the risk of combustion and explosion caused by contact with oxygen is avoided. At the same time, for materials with high porosity such as powder, the limiting effect of the cavity wall on the side wall of the additive layer can ensure that the side wall still forms a dense structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The drawings in the specification, which constitute a part of the present application, are used to provide further understanding of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0043] Figure 1 It is a schematic diagram of the split sleeve structure of the present invention;

[0044] Figure 2 It is a schematic diagram of the combination of four split sleeves;

[0045] Figure 3 It is a schematic diagram of the three-dimensional structure of the device for controlling edge accuracy of a friction stir extrusion solid-phase additive deposition layer in a feeding state after the split sleeve is installed in the present invention;

[0046] Figure 4 It is a cross-sectional view of the device for controlling edge accuracy of a friction stir extrusion solid-phase additive deposition layer in a feeding state after the split sleeve is installed in the present invention;

[0047] Figure 5 Schematic diagram of a multi-layer additive manufacturing method in a vertical plane, wherein (a) is a schematic diagram of the operation path of a device in an embodiment of the present invention; (b) is a schematic diagram of the multi-layer additive effect in a vertical plane without using a split sleeve;

[0048] Figure 6 Schematic diagram of a multi-pass additive manufacturing method in a horizontal plane, wherein (a) is a schematic diagram of the operation path of a device in an embodiment of the present invention; (b) is a schematic diagram of the multi-pass additive effect in a horizontal plane without using a split sleeve;

[0049] Figure 7 The front view and top view of the multi-layer additive effect in the vertical plane without the split sleeve, where (a) is the front view and (b) is the top view;

[0050] Figure 8 The main view and top view of the multi-pass additive effect in the horizontal plane without the split sleeve, where (a) is the main view and (b) is the top view;

[0051] Fig. 9The front view and top view of the multi-layer additive effect in a vertical plane completed by the split sleeve of the present invention, wherein (a) is the front view and (b) is the top view;

[0052] Fig.10 The front view and top view of the multi-pass additive effect in the horizontal plane completed by the split sleeve of the present invention, wherein (a) is the front view and (b) is the top view;

[0053] In the figure, 1-split sleeve A, 2-split sleeve B, 3-split sleeve C, 4-split sleeve D, 5-hollow stirring head, 6-raw material, 7-additive layer, 8-substrate, 9-cavity wall part, 10-matching part. DETAILED DESCRIPTION

[0054] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of the present invention are clearly and completely described below in conjunction with the drawings in the implementation of this specification, but are not limited to this. Anything not fully described in the present invention shall be based on the conventional technology in the art.

[0055] The existing friction stir deposition device will form arc-shaped side walls, flash and semi-cylindrical materials at both ends when adding materials, which not only causes material waste, but also increases the amount of subsequent cutting. In view of the above problems, the present invention proposes a device and method for controlling the edge accuracy of a friction stir extrusion solid-phase additive deposition layer.

[0056] The present invention will now be further described with reference to the accompanying drawings and specific implementation methods.

[0057] It should be noted that the friction stir deposition process of the present invention is completed on a machine tool, which has a spindle and a workbench. When adding materials, the spindle moves in the Z direction relative to the workbench, and the workbench moves in the X direction and Y direction to achieve movement in the three directions of XYZ. Among them, the spindle can rotate under the drive of a three-phase spindle motor, and the motor is fixed on the spindle housing. It is driven by a servo motor, and the reducer drives the ball screw to rotate so that the spindle housing can realize the Z direction movement of the spindle along two rolling guides. It is driven by a servo motor, and the reducer drives the ball screw to rotate, and the axial movement of the screw nut realizes the X direction and Y direction movement of the workbench. When the corresponding screw stops rotating, the absolute position of the spindle in the Z direction and the workbench in the X direction and the Y direction remains unchanged, ensuring the stability during the material addition process.

[0058] The spindle housing is surrounded by a lead screw and a guide rail. The servo motor drives the ball screw to rotate, and the reducer drives the split sleeve that passes through the lead screw to move up and down along the guide rail. Due to the use of a lead screw transmission system, the accuracy of the movement can be guaranteed. After reaching the initial height or the non-forming height, the lead screw stops rotating, and the height of the split sleeve relative to the spindle is fixed, and it will not move up and down, so the stability of limiting the side wall forming can be guaranteed.

[0059] Example 1

[0060] A device for controlling edge precision of a friction stir extrusion solid phase additive deposition layer, such as Figure 1-Figure 4 As shown, it includes a hollow stirring head 5, which can rotate under the drive of the main shaft, and a through hole is set at the central axis thereof for filling raw materials 6 such as rods, wires or powders. In this embodiment, a square rod of AZ31B magnesium alloy with a side length of 10 mm is used as the raw material 6, and the rod is fed into the square through hole of the hollow stirring head 5 through a feeding mechanism. The side length of the square through hole is 10 mm, and the clearance between the rod and the square through hole is matched. The shoulder diameter of the hollow stirring head 5, that is, the diameter of the lower end face of the hollow stirring head 5, is 28 mm.

[0061] Four split sleeves are sleeved around the hollow stirring head 5. The four split sleeves can move up and down independently under the control of the screw transmission mechanism on the main shaft housing, and the translation in other directions is restricted. The split sleeve includes a cavity wall part 9 and a matching part 10. The cavity wall part 9 is a quadrangular prism structure; the matching part 10 is a triangular prism structure, including a cylinder A, a cylinder B and a 1 / 4 cylindrical surface, wherein the cylinder A coincides with the cavity wall part 9, the cylinder B is exposed to the outside, and the 1 / 4 cylindrical surface is smoothly connected to the cavity wall part 9; the four split sleeves are connected end to end in a way that the cylinder B of the matching part 10 coincides with the cavity wall part 9, forming the entire sleeve;

[0062] The height difference between the bottom of the cavity wall part 9 and the bottom of the matching part 10 is the thickness of one additive layer 7. In this embodiment, the thickness of one additive layer 7 is 1 mm. Therefore, before starting to feed, the lower end face of the hollow stirring head 5 is 1 mm away from the upper surface of the substrate 8.

[0063] Example 2

[0064] A device for controlling edge accuracy of a friction stir extrusion solid-phase additive deposition layer is as described in Example 1, except that the through hole of the hollow stirring head 5 is a square through hole.

[0065] The lower end surface of the hollow stirring head 5 is a shaft shoulder, which is the main part where friction and heat are generated with the raw material 6 during the friction stirring deposition process;

[0066] In order to prevent the plasticized material from being blocked at one end of the through hole close to the shaft shoulder, the end of the through hole close to the shaft shoulder is configured to expand outwards to reserve space for the deformation of the plasticized material.

[0067] Example 3

[0068] A device for controlling the edge precision of a stir friction extrusion solid-phase additive deposition layer, as described in Example 1, except that adjacent split sleeves are clearance-fitted, and the 1 / 4 cylindrical surfaces of the four split sleeves constitute a circular cavity of the entire sleeve, that is, a complete cylindrical surface, and the circular cavity is clearance-fitted with the outer side surface of the hollow stirring head 5.

[0069] The up and down movement of the four split sleeves is only switched between two heights, namely the initial height and the non-forming height. The initial height is switched to the non-forming height by upward movement. The height difference between the initial height and the non-forming height is the thickness of an additive layer 7.

[0070] When the split sleeve is at the initial height, the triangular prism lower bottom surface of the split sleeve matching part 10 and the shoulder of the hollow stirring head 5 are in the same plane, and the lower end surface of the cavity wall part 9 of the split sleeve and the upper surface of the substrate 8 or the previous additive layer 7 are in the same plane; in the entire sleeve, the bottom inner walls of the four split sleeve cavity wall parts 9, the bottom surface of the matching part 10, the upper surface of the substrate 8 or the additive layer 7, and the lower end surface of the hollow stirring head 5 constitute a right parallelepiped closed cavity with a square bottom surface. The height of the cavity is equal to the thickness of one additive layer 7, and the bottom side length of the cavity is 28 mm, which is equal to the shoulder diameter of the hollow stirring head 5.

[0071] When the split sleeve is at the non-forming height, the lower end surface of the cavity wall portion 9 of the split sleeve and the bottom surface of the hollow stirring head 5 are in the same plane.

[0072] In order to avoid the formation of semi-cylindrical materials at both ends of the additive layer 7, it is necessary to place the four split sleeves at the initial height to form a closed cavity, and rotate the hollow stirring head 5 at a speed of 800 rpm. Since the rod used is a square rod and the through hole is a square hole, the hollow stirring head 5 will drive the rod to rotate together. At the same time, the top of the rod is subjected to an axial forging force, and the bottom end of the rod and the upper surface of the substrate 8 generate heat by friction, which gradually softens the rod. As the feed amount increases, the rod contacts and rubs against the shoulder. Due to the increase in friction heat generation, the rod is quickly softened into a plasticized material, and contacts the cavity wall under the action of the extrusion force, and is finally formed into a hexahedron consistent with the shape of the cavity, thereby avoiding the formation of arc-shaped side walls, flash and semi-cylindrical materials at both ends of the additive layer 7.

[0073] When feeding in the horizontal plane, the feeding speed is determined by the feeding speed. When the feeding is stopped, the feeding speed is 0, and the feeding speed is also 0, but the hollow stirring head 5 still keeps rotating to maintain the plasticized state of the material under the shoulder. When the feeding speed is not 0, the feeding speed is calculated according to the continuity equation from the cross-sectional area of ​​the additive layer 7, the cross-sectional area of ​​the rod and the feeding speed. The calculation and control of the feeding speed are existing technologies and will not be repeated here.

[0074] When feeding upward in a vertical plane, the feeding speed is determined by the square bottom area of ​​the hexahedral closed cavity, the cross-sectional area of ​​the rod and the upward feeding speed according to the continuity equation. The calculation and control of the feeding speed are existing technologies and will not be repeated here.

[0075] After the feeding starts, the height of the four split sleeves is flexibly adjusted to maintain the closedness of the cavity while avoiding collision between the split sleeves and the completed additive layer 7. If the closedness of the cavity cannot be maintained, the arc-shaped side wall is cut off by the cavity wall of the split sleeve.

[0076] The feed speed used in this embodiment is 100 mm / min. Since an additive layer 7 having a shape consistent with the cavity is formed before the feed starts, Figure 3 As shown, the split sleeve D 4 moves upward to the non-forming height and then starts feeding. Figure 4 As shown, although one side of the split sleeve D 4 does not constrain the plasticized material, the side wall of the additive layer 7 will continue to constrain the plasticized material to maintain the closedness of the cavity.

[0077] Example 4

[0078] A working method of the device for controlling edge precision of a friction stir extrusion solid-phase additive deposition layer based on Example 3, as follows: Figure 5 As shown, multi-layer additive manufacturing can be achieved in a vertical plane, including the following steps:

[0079] (1) At the initial moment, the four split sleeves are all at their initial heights, such as Figure 3 The split sleeve A 1, the split sleeve B 2, the split sleeve C 3 and the split sleeve D 4, the bottom of the cavity wall parts 9 of the four split sleeves are all in contact with the substrate 8, the bottom inner wall of the cavity wall parts 9 of the four split sleeves, the bottom surface of the matching part 10, the upper surface of the substrate 8, and the lower end surface of the hollow stirring head 5 constitute a closed cavity, the raw material 6 in the hollow stirring head 5 is pressed into the closed cavity under the extrusion of the axial upsetting force, the raw material 6 is plasticized by the friction heat generated by the rotation of the shaft shoulder and the raw material 6, and the plasticized material is extruded and formed under the constraint of the cavity wall;

[0080] (2) Before the first additive layer 7 starts to be fed, the split sleeve D 4 on the opposite side of the feeding direction moves upward to the non-forming height. At this time, the bottom of the cavity wall part 9 of the split sleeve D 4 is 1 mm away from the upper surface of the substrate 8 to avoid hindering the backward movement of the additive layer 7 during feeding. Then, the hollow stirring head 5 and the four split sleeves start to feed as a whole to complete the deposition of the first additive layer 7;

[0081] (3) After the first feeding is completed, the split sleeve A 1, the split sleeve B 2, the split sleeve C 3 and the hollow stirring head 5 simultaneously move upward by a displacement equal to the thickness of the additive layer 7, i.e., 1 mm. At this time, the four split sleeves all reach the initial height of the second additive layer 7, and the plasticized material is again enclosed in the closed cavity for extrusion molding;

[0082] (4) Before the second layer starts to be fed, the split sleeve B2 moves upward to the non-forming height, and then starts to feed to complete the deposition of the second additive layer 7;

[0083] (5) Steps (2) to (4) are continuously repeated until the sum of the thicknesses of all additive layers 7 reaches the target height, thus completing the multi-layer additive manufacturing in the vertical plane.

[0084] Figure 5 (b) shows a schematic diagram of a vertical plane multilayer additive device and components without a split sleeve. Figure 7 and Fig. 9 From the shape comparison, it can be seen that the use of the split sleeve can achieve precise forming of the side wall by avoiding the formation of arc-shaped side walls, flash and semi-cylinders at both ends of the additive layer 7, and can produce an additive layer 7 with a more regular shape and can be utilized, thereby reducing the subsequent cutting amount and improving material utilization.

[0085] Example 5

[0086] A working method of the device for controlling edge precision of a friction stir extrusion solid-phase additive deposition layer based on Example 3, as follows: Figure 6 As shown, multi-pass additive manufacturing can be achieved in the horizontal plane. In order to enhance the metallurgical bonding between each pass, the overlap amount of adjacent passes is 3 mm, including the following steps:

[0087] S1: At the initial moment, the four split sleeves are at the initial height, that is, the bottom of the cavity wall parts 9 of the four split sleeves are all in contact with the substrate 8, and the bottom inner wall of the cavity wall parts 9 of the four split sleeves, the bottom surface of the matching part 10, the upper surface of the substrate 8, and the lower end surface of the hollow stirring head 5 constitute a closed cavity. The raw material 6 in the hollow stirring head 5 is pressed into the closed cavity under the extrusion of the axial upsetting force, and the raw material 6 is plasticized by the friction heat generated by the rotation of the shaft shoulder and the raw material 6, and the plasticized material is extruded and formed under the constraint of the cavity wall;

[0088] S2: before the first feeding starts, the split sleeve D 4 on the side opposite to the feeding direction moves upward to the non-forming height, and then starts feeding to complete the deposition of the first additive layer 7;

[0089] S3: Before turning from the first pass to the second pass, the feeding direction rotates 90° toward the second pass (the four split sleeves do not rotate), and the split sleeve A1 on the opposite side of the feeding direction moves upward to the non-forming height, and then starts feeding to complete the deposition of the transition layer from the first pass to the second pass. At this time, two split sleeves are at the non-forming height;

[0090] S4: before the second pass starts feeding, the split sleeve B 2 in the opposite direction to the second pass feeding direction moves upward to the non-forming height (only the split sleeve C 3 is at the initial height, and the other split sleeves are at the non-forming height), and then starts feeding to complete the deposition of the second additive layer 7. At this time, three split sleeves are at the non-forming height; because the split sleeve D 4 is still at the non-forming height during the second additive process, and the split sleeve D 4 is located on the same side as the second pass feeding direction, the split sleeve D 4 cannot constrain the side wall of the second additive layer 7 near one end of the feeding direction, and the plasticized material will produce arc-shaped wall surfaces and flash edges under the extrusion of three sides and the upper and lower surfaces;

[0091] S5: In order to remove the arc-shaped wall surface and flash formed by the second additive layer 7, the split sleeve C 3 is moved upward to the non-forming height while the hollow stirring head 5 is kept rotating. At this time, the four split sleeves are all at the non-forming height. Then, the feeding direction is rotated 90° toward the initial deposition position of the first additive layer 7, and the four split sleeves and the hollow stirring head 5 are moved to the initial deposition position of the first additive layer 7.

[0092] S6: the split sleeve D4 on the same side as the second feeding direction moves downward to the initial height, and then the hollow stirring head 5 and the four split sleeves are simultaneously fed to the initial deposition position of the third additive layer 7, and the arc-shaped wall surface and flash are cut off by the cavity wall edge of the split sleeve D4;

[0093] S7: After moving to the initial deposition position of the third additive layer 7, the split sleeve C3 farthest from the second additive layer 7 moves downward to the initial height to perform initial deposition of the third additive layer 7;

[0094] S8: Then repeat steps S4 to S7, and complete subsequent material addition by flexibly switching the heights of the four split sleeves until the target size requirement is reached.

[0095] In this embodiment, the angle between the inner side and the outer side of the split sleeve cavity wall part 9 is α Use right angles.

[0096] Figure 6 (b) shows a schematic diagram of a multi-pass additive device and components in a horizontal plane without a split sleeve. Figure 8 and Fig.10 From the shape comparison, it can be seen that no matter what kind of additive method is used, the split sleeve can achieve precise forming of the side wall of the component. Therefore, the device proposed in the present invention can flexibly complete additive manufacturing under various paths without changing the device.

[0097] Example 6

[0098] A working method of a device for controlling the edge precision of a friction stir extrusion solid-phase additive deposition layer, as described in Example 4, except that in this embodiment, powder is used as raw material 6 to complete the vertical plane multi-layer additive manufacturing of aluminum-based composite materials. Before the additive, 94 wt% Al 6061 alloy powder with an average particle size of 58±20 μm and 6 wt% Fe Co Ni powder (wherein Fe, Co, and Ni each account for 2 wt%) with an average particle size of 5.1±2.3 μm prepared by ball milling are fully mixed to prepare Al6061 / Fe Co Ni mixed powder. The prepared powder is filled into the through hole of the hollow stirring head 5 as raw material 6, and the size of the device is still the same as that of Example 4.

[0099] Since there are pores between the particles inside the powder after it is filled into the through hole, in order to ensure that a dense additive layer 7 is obtained, the feeding speed of the powder should be calculated differently from that of the rod or wire. When the continuity equation is used to calculate the feeding speed, the porosity of the powder should be calculated according to the geometric shape of the powder. The required feeding speed is calculated according to the cross-sectional area of ​​the additive layer 7, the cross-sectional area of ​​the through hole, the porosity of the powder and the feeding speed. The calculation and control of the feeding speed are prior art.

[0100] Since the shear force between powders is weaker than that of bulk metal, the deformation resistance when subjected to external force is low, so a process parameter with higher heat input should be selected to compensate for the low plastic deformation heat generation caused by low deformation resistance. Therefore, the rotation speed used in this embodiment is 1200 rpm and the feed speed is 100 mm / min.

[0101] If a split sleeve is not used, due to the high-speed rotation of the hollow stirring head 5 and the plastic material during operation, the strong air flow will cause the powder to scatter everywhere, resulting in a waste of filling materials. At the same time, the dust floating in the air will also affect the health of the operator. If a split sleeve is used, since a closed cavity is formed during the additive process, the powder will not scatter everywhere after filling, which effectively solves the above problems. In addition, since the closed cavity isolates the metal powder inside from the outside world, the risk of combustion and explosion caused by contact with oxygen is avoided. Although the powder has a high porosity, the limiting effect of the cavity wall on the side wall of the additive layer 7 can ensure that the side wall still forms a dense structure.

[0102] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A device for controlling edge precision of a friction stir extrusion solid-phase additive deposition layer, characterized in that: It includes a hollow stirring head, which is rotatable and has a through hole at its central axis for filling rods, wires or powder raw materials; Four split sleeves are sleeved around the hollow stirring head, and the four split sleeves can move up and down independently. The split sleeve includes a cavity wall part and a matching part, and the cavity wall part is a quadrangular prism structure; the matching part is a triangular prism structure, including a cylindrical surface A, a cylindrical surface B and a 1 / 4 cylindrical surface, wherein the cylindrical surface A coincides with the cavity wall part, the cylindrical surface B is exposed to the outside, and the 1 / 4 cylindrical surface is smoothly connected to the cavity wall part; the four split sleeves are connected end to end in a manner that the cylindrical surface B of the matching part coincides with the cavity wall part to form the entire sleeve; The height difference between the bottom of the cavity wall portion and the bottom of the matching portion is the thickness of one additive layer; The up and down movement of the four split sleeves is switched only between two heights, namely the initial height and the non-forming height. The height difference between the initial height and the non-forming height is the thickness of one additive layer. When the split sleeve is at an initial height, the lower bottom surface of the triangular prism of the split sleeve matching part and the shoulder of the hollow stirring head are in the same plane, and the lower end surface of the cavity wall part of the split sleeve and the upper surface of the substrate or the previous additive layer are in the same plane; in the entire sleeve, the bottom inner walls of the four split sleeve cavity wall parts, the bottom surface of the matching part, the upper surface of the substrate or the additive layer, and the lower end surface of the hollow stirring head constitute a closed cavity with a right parallelepiped having a square bottom surface, and the height of the cavity is equal to the thickness of one additive layer.

2. The device for controlling edge precision of a friction stir extrusion solid-phase additive deposition layer according to claim 1, characterized in that: The through hole of the hollow stirring head is a circular through hole or a square through hole.

3. The device for controlling edge precision of a friction stir extrusion solid phase additive deposition layer according to claim 2, characterized in that: The lower end surface of the hollow stirring head is a shaft shoulder, and one end of the through hole close to the shaft shoulder is arranged in an outwardly expanding form.

4. The device for controlling edge precision of a friction stir extrusion solid-phase additive deposition layer according to claim 3, characterized in that: There is a clearance fit between adjacent split sleeves, and 1 / 4 cylindrical surfaces of the four split sleeves form a circular cavity of the entire sleeve, and the circular cavity is clearance-fitted with the outer side surface of the hollow stirring head.

5. The device for controlling edge precision of a friction stir extrusion solid-phase additive deposition layer according to claim 4, characterized in that: The side length of the cavity is equal to the diameter of the hollow stirring head.

6. The device for controlling edge precision of a friction stir extrusion solid-phase additive deposition layer according to claim 5, characterized in that: When the split sleeve is at a non-forming height, the lower end surface of the cavity wall portion of the split sleeve and the shaft shoulder of the bottom surface of the hollow stirring head are in the same plane.

7. A working method of the device for controlling edge accuracy of a friction stir extrusion solid-phase additive deposition layer according to claim 6, characterized in that: It is possible to realize multi-layer additive manufacturing in a vertical plane, including the following steps: (1) At the initial moment, the four split sleeves are all at the initial height, that is, the bottom of the cavity wall parts of the four split sleeves are all in contact with the substrate, and the bottom inner wall of the cavity wall parts of the four split sleeves, the bottom surface of the matching part, the upper surface of the substrate, and the lower end surface of the hollow stirring head constitute a closed cavity. The raw material in the hollow stirring head is pressed into the closed cavity under the extrusion of the axial upsetting force, and the raw material is plasticized by the friction heat generated by the rotation of the shaft shoulder and the raw material. The plasticized material is extruded and formed under the constraint of the cavity wall; (2) Before the first additive layer starts to be fed, the split sleeve on the side opposite to the feeding direction moves upward to the non-forming height to avoid hindering the backward movement of the additive layer during feeding. Then, the hollow stirring head and the four split sleeves start to feed as a whole to complete the deposition of the first additive layer; (3) After the first feeding is completed, the other three split sleeves and the hollow stirring head move upward at the same time by a displacement equal to the thickness of the additive layer. At this time, the four split sleeves have reached the initial height of the second additive layer, and the plasticized material is again enclosed in the closed cavity for extrusion molding; (4) Before the second layer starts to be fed, the split sleeve on the side opposite to the feeding direction moves upward to the non-forming height, and then starts to feed to complete the deposition of the second additive layer; (5) Repeat steps (2) to (4) until the sum of the thicknesses of all additive layers reaches the target height, completing multi-layer additive manufacturing in the vertical plane.

8. The working method of the device for controlling edge accuracy of a friction stir extrusion solid-phase additive deposition layer according to claim 7, characterized in that: Capable of multi-pass additive manufacturing in a horizontal plane, including the following steps: S1: At the initial moment, the four split sleeves are at the initial height, that is, the bottom of the cavity wall parts of the four split sleeves are all in contact with the substrate, and the bottom inner wall of the cavity wall parts of the four split sleeves, the bottom surface of the matching part, the upper surface of the substrate, and the lower end surface of the hollow stirring head constitute a closed cavity. The raw material in the hollow stirring head is pressed into the closed cavity under the extrusion of the axial upsetting force, and the raw material is plasticized by the friction heat generated by the rotation of the shaft shoulder and the raw material, and the plasticized material is extruded and formed under the constraint of the cavity wall; S2: Before the first feed starts, the split sleeve on the side opposite to the feed direction moves upward to the non-forming height, and then starts feeding to complete the deposition of the first additive layer; S3: Before turning from the first pass to the second pass, the feeding direction is rotated 90° toward the second pass, and the split sleeve on the side opposite to the feeding direction moves upward to the non-forming height, and then starts feeding to complete the deposition of the transition layer from the first pass to the second pass. At this time, two split sleeves are at the non-forming height; S4: Before the second pass starts feeding, the split sleeve in the opposite direction to the second pass feeding direction moves upward to the non-forming height, and then starts feeding to complete the deposition of the second additive layer. At this time, three split sleeves are at the non-forming height; since the split sleeve at the non-forming height during the first additive pass is still at the non-forming height during the second additive pass, and the split sleeve is located on the same side as the second pass feeding direction, the split sleeve cannot suppress the formation of the arc-shaped wall and flash of the second additive layer near the feeding direction end; S5: In order to remove the arc-shaped wall and flash formed by the second additive layer, the split sleeve at the initial height is moved upward to the non-forming height while the hollow stirring head is kept rotating. At this time, the four split sleeves are all at the non-forming height. Then, the feeding direction is rotated 90° toward the initial deposition position of the first additive layer, and the four split sleeves and the hollow stirring head are moved to the initial deposition position of the first additive layer. S6: The split sleeve on the same side as the second feeding direction moves downward to the initial height, and then the hollow stirring head and the four split sleeves are simultaneously fed to the initial deposition position of the third additive layer, and the arc-shaped wall surface and flash are cut off by using the cavity wall edge of the split sleeve; S7: After moving to the initial deposition position of the third additive layer, the split sleeve farthest from the second additive layer moves downward to the initial height to perform initial deposition of the third additive layer; S8: Then repeat steps S4 to S7, and complete subsequent material addition by switching the heights of the four split sleeves until the target size requirement is reached.

9. The working method of the device for controlling edge accuracy of a friction stir extrusion solid-phase additive deposition layer according to claim 8, characterized in that: The angle between the inner side and the outer side of the cavity wall of the split sleeve cavity wall part α Use right angles or acute angles.

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