An additive manufacturing apparatus and an additive manufacturing method

Abstract

This invention provides an additive manufacturing apparatus and an additive manufacturing method. The additive manufacturing apparatus includes a stationary shoulder and a stirring head, with a cavity structure between the stirring head and the stationary shoulder. This cavity structure is connected to a feed channel and a forming port. The tangential force generated by the rotation of the stirring head and the surface texture facilitate the entry of additive material from the feed channel into the cavity. During operation, the stationary shoulder contacts the substrate, leaving only the forming port at the rear edge of the stationary shoulder for the formation of the additive layer. The feed channel in the stationary shoulder structure ensures that the additive material smoothly reaches the cavity structure. The stirring head penetrates the substrate, and through a stirring and friction process, softens and plastically flows the additive material, ensuring full contact with the substrate. As the welding tool moves, an additive layer is formed at the forming port on the rear side of the travel direction.

Description

Technical Field

[0001] This invention relates to the technical fields of friction stir welding and additive manufacturing, and particularly to a friction stir welding tool and method for additive manufacturing using a stationary shoulder structure cavity. Background Technology

[0002] Additive manufacturing, a type of rapid prototyping technology, is a technique that uses digital model files as a basis and employs powdered metals or plastics and other bondable materials to construct objects by printing and stacking layers. It differs significantly from traditional additive manufacturing technologies such as casting, forging, and milling. Currently, metal additive manufacturing primarily uses electric arcs, lasers, and electron beams to melt metal materials and process them layer by layer. However, due to the high coefficient of linear expansion and high thermal conductivity of aluminum alloys, the melt-solidification additive method leads to severe component deformation and difficulty in ensuring dimensional accuracy. Friction stir welding (FSW), as a solid-state joining technology, offers advantages such as high joint quality, minimal welding deformation, a green and pollution-free welding process, high automation, and low welding costs, attracting researchers' attention and leading to the combination of additive manufacturing and friction stir welding.

[0003] During static shoulder friction stir welding, the downward pressure of the shoulder causes some plastic material to enter the gap between the stirring head and the static shoulder, resulting in abnormal rotation of the stirring head. Therefore, a discharge hole is usually provided on the static shoulder. Observation shows that the discharged material is continuous and dense, and its cross-section is similar in shape to the discharge hole. Based on this phenomenon, the discharge hole of the static shoulder is set at the working end of the static shoulder that contacts the substrate. In addition, by controlling the downward depth of the stirring head, a cavity is formed between the conical surface of the stirring head and the inner wall of the static shoulder. This cavity can be used to stir and rub the additive material to plasticize it, and then discharge it through the discharge port to form an additive layer. Summary of the Invention

[0004] The purpose of this invention is to provide an additive manufacturing apparatus and an additive manufacturing method to solve the problems existing in the prior art.

[0005] The technical solution of the present invention is: to provide an additive manufacturing apparatus, including a stationary shoulder, a stirring head, a motor, a robot arm, and a rotating spindle located on the robot arm; the stirring head is mounted on the rotating spindle and disposed in the axial through hole of the stationary shoulder body; an annular cavity structure is provided between the stirring head and the inner wall of the stationary shoulder body; The stationary shoulder includes a shoulder body with an axial through hole for receiving the stirring head to form a welding tool suitable for additive manufacturing. A feed channel is formed within the stationary shoulder body, inclined towards the working end of the stationary shoulder body to ensure that the material to be filled smoothly reaches the outlet and enters the cavity structure. The inlet of the feed channel is located outside the stationary shoulder body, and the outlet is located inside the stationary shoulder body, close to the working end of the stationary shoulder body. The outlet is lower than the inlet. "Close to the working end" means that the outlet of the feeding channel can be connected to the cavity structure, thereby providing material for additive manufacturing; the working end face of the stationary shoulder body has a forming opening, which is a notch structure located on the stationary shoulder body; The cavity structure is connected to the feeding channel at the front end and to the forming port at the rear end. During additive manufacturing, the stirring head rotates to generate tangential force, which promotes the entry of filaments and granules from the feeding channel into the cavity structure. During operation, the stationary shoulder body contacts the substrate, leaving only the forming opening at the rear edge of the stationary shoulder body for the formation of the additive layer; the feed channel in the stationary shoulder structure ensures that the filling material can smoothly reach the cavity structure, and the filling material in the cavity structure can fully contact the substrate to realize the formation of the additive layer on the substrate.

[0006] Furthermore, the forming port is obtained by grooving the rear edge of the stationary shoulder body; the forming port is located on the opposite side of the outlet of the feeding channel, so that the material to be filled has enough time and space to be stirred and plasticized in the cavity structure.

[0007] Furthermore, the inlet diameter of the feed channel is greater than or equal to the outlet diameter.

[0008] Furthermore, the stationary shoulder body has a feed channel inclined towards the working end to ensure that the filler material can smoothly reach the working end position; a forming port is provided on the working end face, and the plastic filler material obtained by stirring and friction is deposited on the rear edge of the stationary shoulder body through the forming port to form an additive layer to achieve the purpose of additive manufacturing. The filler material can only be extruded from the forming port to form the additive layer and will not overflow from other positions; the filler material can be confined from the end face sidewall of the stationary shoulder body, and no additional device is needed to prevent the material from flowing out.

[0009] Furthermore, the feed channel is a straight channel or a spiral channel; The spiral channel is a spiral hole offset along the rotation direction of the stirring head, which can promote the filling material to enter the cavity structure from the feeding channel under the rotation and shearing action of the stirring head.

[0010] Furthermore, the outer diameter of the working end of the stationary shoulder is 20-40mm, and the inner diameter is 10-20mm.

[0011] Furthermore, the width of the notched structure in the horizontal direction is 10-20mm; the depth of the notched structure is 2-4mm. The notched structure slopes downwards from the inside out, with an inclination angle of 5-10°.

[0012] Another technical solution of the present invention provides an additive manufacturing method using the above-described additive manufacturing apparatus, comprising the following steps: Step S1: Mount the stationary shoulder and the stirring head onto the main shaft of the friction stir welding equipment, and set the downward pressure of the stirring head; and ensure that the inlet of the feed channel of the stationary shoulder is located in front of the welding tool travel direction, and the forming port is located in the rear of the welding tool travel direction. Step S2: Start the friction stir welding equipment, feed the additive material into the cavity structure through the feeding channel, and achieve a plasticized state through the stirring and friction of the stirring head. Then, the plasticized material is deposited into an additive layer on the rear side of the welding direction through the forming port. Step S3: When the additive layer begins to form, control the movement of the welding tool to form a continuous additive layer.

[0013] Furthermore, the stirring head rotates at a speed of 1500-4000 rpm and the downward thrust is 1-2 mm.

[0014] Furthermore, the welding speed of the stirring head and the stationary shoulder is 300-1500 mm / min; The additive material is a filament with a diameter of 1-3 mm, or a granular material with a particle diameter of 1-3 mm.

[0015] The beneficial effects of the additive manufacturing apparatus and additive manufacturing method provided by this invention are as follows: 1) The static shoulder structure provided by the present invention has a feeding channel inclined towards the working end in the static shoulder body, which can ensure that the filling material can smoothly reach the working end position. There is a forming port on the working end face. The plastic filling material obtained by stirring and friction is deposited on the rear edge of the static shoulder through the forming port to form an additive layer, so as to achieve the purpose of additive manufacturing. The filling material can only be extruded from the forming port to form the additive layer and will not overflow from other positions, resulting in high material utilization.

[0016] 2) The additive manufacturing apparatus provided by the present invention includes a stationary shoulder and a stirring head. A cavity structure is provided between the stirring head and the stationary shoulder. The cavity structure is connected to the feed channel and the forming port respectively. The tangential force generated by the rotation of the stirring head can promote the entry of filaments and granules from the feed channel into the cavity. During operation, the stationary shoulder contacts the substrate, and only the forming port at the rear edge of the stationary shoulder is left for the formation of the additive layer. The feed channel in the stationary shoulder structure ensures that the filler material can smoothly reach the cavity structure, and the filler material in the cavity structure can fully contact the substrate to realize the formation of the additive layer on the substrate. Attached Figure Description

[0017] The invention will be further described below with reference to the accompanying drawings: Figure 1 A schematic diagram of a static shoulder structure provided in an embodiment of the present invention; Figure 2 for Figure 1 Cross-sectional view of the stationary shoulder structure; Figure 3 This is a cross-sectional view of the additive manufacturing welding tool of the present invention; Figure 4 This is a cross-sectional view of the additive manufacturing welding tool in use as provided in Embodiment 2 of the present invention; Explanation of reference numerals in the attached figures: 1. Feed channel; 2. Forming port; 3. Cavity structure; 4. Stirring needle; 5. Stationary shoulder body; 6. Substrate; 7. Additive layer. Detailed Implementation

[0018] The additive manufacturing apparatus and method proposed in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise ratios, and are only used to facilitate and clarify the illustration of the embodiments of this invention.

[0019] The present invention provides a stationary shoulder structure, comprising: a stationary shoulder body having an axial through hole; at least one feed channel formed in the stationary shoulder body and inclined toward the working end of the stationary shoulder; and the working end face of the stationary shoulder body having a forming opening.

[0020] In the above-described stationary shoulder structure, the inlet of the feed channel is located outside the stationary shoulder body; the outlet of the feed channel is located inside the stationary shoulder body and close to the working end of the stationary shoulder, and the outlet is lower than the inlet; wherein, close to the working end means that it can be connected to the cavity structure located between the stirring head and the stationary shoulder at the working end, thereby providing material for additive manufacturing.

[0021] In the aforementioned stationary shoulder structure, the inlet diameter of the feed channel can be greater than or equal to the outlet diameter. Furthermore, the feed channel can be a straight channel or a spiral channel.

[0022] In the above-described static shoulder structure, the forming opening is a notch structure located on the static shoulder body. Furthermore, in the above-described static shoulder structure, the notch structure is located on the opposite side of the outlet of the feed channel.

[0023] In the above-mentioned stationary shoulder structure, the outer diameter of the working end of the stationary shoulder can be selected as 20-40mm, and the inner diameter can be selected as 10-20mm.

[0024] In the above-mentioned static shoulder structure, the width of the notched structure in the horizontal direction can be selected as 10-20mm; the depth of the notched structure can be selected as 2-4mm.

[0025] In the above-mentioned static shoulder structure, the notched structure is inclined downward from the inside out, wherein the inclination angle is 5-10°.

[0026] The present invention also provides an additive manufacturing apparatus, including the above-mentioned stationary shoulder and stirring head, wherein the stirring head is disposed in the axial through hole of the stationary shoulder.

[0027] In the above-mentioned additive manufacturing apparatus, there is a cavity structure between the stirring head and the stationary shoulder, and the cavity structure is connected to the feed channel and the forming port respectively.

[0028] In the above-mentioned additive manufacturing apparatus, the outlet of the feed channel is located entirely on the side wall of the cavity structure, wherein the diameter of the outlet of the feed channel is 2-4 mm.

[0029] The additive manufacturing apparatus described above also includes a friction stir welding device with a spindle on which a stationary shoulder welding tool is mounted, wherein the stationary shoulder and the stirring head are mounted on the spindle.

[0030] The present invention also provides an additive manufacturing method using the above-described additive manufacturing apparatus, comprising the following steps: The stationary shoulder and the stirring head are clamped on the main shaft of the friction stir welding equipment, and the downward pressure of the stirring head is set; and the inlet of the feed channel of the stationary shoulder is located in front of the welding tool travel direction, and the forming port is located in the rear of the welding tool travel direction. Start the friction stir welding equipment, feed the additive material into the cavity structure through the feeding channel, and achieve a plasticized state through the stirring and friction of the stirring head. Then, the plasticized material is deposited into an additive layer on the rear side of the welding direction through the forming port. As the additive layer begins to form, the welding tool is controlled to move forward, forming a continuous additive layer.

[0031] In the above additive manufacturing method, the stirring head rotates at a speed of 1500-4000 rpm and the depth of penetration is 1-2 mm.

[0032] In the above additive manufacturing method, the welding speed of the stirring head and the stationary shoulder is 300-1500 mm / min.

[0033] In the above additive manufacturing method, the material to be filled is a filament with a diameter of 1-3 mm, or a particle with a particle diameter of 1-3 mm.

[0034] Example 1 like Figure 1-2 As shown, this embodiment provides a stationary shoulder structure suitable for additive manufacturing. The stationary shoulder structure includes a stationary shoulder body 5, which has an axial through-hole adapted to receive a stirring head to form a welding tool suitable for additive manufacturing. A feed channel 1 is formed in the stationary shoulder body 5, such as... Figure 2 As shown, the feeding channel 1 can be provided in a straight line and inclined towards the working end of the stationary shoulder body 5. This ensures that the material to be filled can smoothly reach the outlet through the feeding channel 1 and enter the cavity structure between the stirring head and the stationary shoulder body 5 located at the working end. The inlet of the feeding channel 1 is located outside the stationary shoulder body 5, and the outlet of the feeding channel 1 is located inside the stationary shoulder body 5, close to the working end of the stationary shoulder body 5. Furthermore, the outlet is lower than the inlet. "Close to the working end" means that the outlet of the feeding channel 1 can be connected to the cavity structure 3 between the stirring head and the stationary shoulder body 5 located at the working end, thereby providing material for additive manufacturing. The working end face of the stationary shoulder body 5 has a forming opening 2, which is a notch structure located on the stationary shoulder body 5. Preferably, the forming opening 2 is obtained by grooving the rear edge of the stationary shoulder body 5. Figure 2 As shown, the notched structure is located on the opposite side of the outlet of the feed channel 1, so that the material to be filled has enough time and space to be stirred and plasticized in the cavity structure 3.

[0035] The static shoulder structure provided in this embodiment has a feeding channel 1 inclined towards the working end inside the static shoulder body 5, which can ensure that the filling material can smoothly reach the working end position. There is also a forming port 2 on the working end face. The plastic filling material obtained by stirring and friction accumulates on the rear edge of the static shoulder body 5 through the forming port 2 to form an additive layer 7, so as to achieve the purpose of additive manufacturing. The filling material can only be extruded from the forming port 2 to form the additive layer 7 and will not overflow from other positions, resulting in high material utilization. Furthermore, the filling material can be confined with the end face sidewall of the static shoulder body 5, eliminating the need for additional devices such as baffles to prevent material from flowing out.

[0036] As an alternative implementation, in the above-described static shoulder structure, the feed channel 1 can also be configured as multiple channels, which can ensure the feed volume during the additive manufacturing process.

[0037] As an alternative implementation, in the above-described static shoulder structure, the feed channel 1 can also be configured as a curved structure channel, such as a spiral channel. In particular, the spiral channel refers to a spiral hole offset along the rotation direction of the stirring head, which can promote the filling material to enter the cavity structure 3 from the feed channel 1 under the rotation and shearing action of the stirring head.

[0038] As an alternative implementation, in the above-described static shoulder structure, the notched structure may also be located on the side offset from the outlet.

[0039] In the above-mentioned static shoulder structure, the feed channel 1 can be of constant diameter or variable diameter. Variable diameter means that the inlet diameter of the feed channel 1 is larger than the diameter of the inlet, in order to improve feeding efficiency.

[0040] Alternatively, in the above-mentioned stationary shoulder structure, the outer diameter of the working end of the stationary shoulder body 5 at the bottom of the stationary shoulder is 20-40mm, the inner diameter is 10-20mm, the groove width of the forming port 2 in the horizontal direction is 10-20mm, the groove thickness of the forming port 2 in the vertical direction is 2-4mm, the upper surface of the forming port 2 may not have an angle, or it may form an angle of 5-10° with the welding direction, and cooperate with the welding tilt angle to ensure the formation of the additive layer 7 on the substrate 6, which is the material to be welded.

[0041] In the above-mentioned stationary shoulder structure, the stationary shoulder body 5 has a tapered section, and the feed channel 1 is located within the tapered section. Example

[0042] like Figure 3-4 As shown, this embodiment provides an additive manufacturing apparatus, which includes a stationary shoulder body 5 and a stirring head as described in Embodiment 1, as well as a motor, a robotic arm, and a rotating spindle located on the robotic arm; wherein, the stirring head is mounted on the rotating spindle, and the stirring head is a stirring needle 4-1, wherein the stirring needle 4-1 passes through the axial through hole of the stationary shoulder body 5, as shown. Figure 4As shown, an annular cavity structure 3 is provided between the stirring pin 4-1 and the inner wall of the stationary shoulder body 5. The cavity structure 3 is connected to the feed channel 1 at the front end and to the forming port 2 at the rear end. During additive manufacturing, the tangential force generated by the rotation of the stirring pin 4-1 can promote the entry of filaments and granules from the feed channel into the cavity structure 3. During operation, the stationary shoulder body 5 is in contact with the substrate 6, leaving only the forming port at the rear edge of the stationary shoulder body 5 for the formation of the additive layer. The feed channel 1 in the stationary shoulder structure ensures that the filling material can smoothly reach the cavity structure 3, and the filling material in the cavity structure 3 can fully contact the substrate 6 to realize the formation of the additive layer 7 on the substrate 6. The material is densely formed and not prone to pores. Furthermore, the additive manufacturing apparatus provided in this embodiment only requires optimization design of the existing stationary shoulder structure and does not require modification of other equipment or components, resulting in low cost.

[0043] In the above-mentioned additive manufacturing apparatus, the stirring needle 4-1 penetrates 1-2 mm during the additive manufacturing process. The outlet of the feed channel 1 is located entirely on the side wall of the cavity structure 3, ensuring that the filling material can enter the cavity structure 3, thereby improving the feeding efficiency. The aperture of the outlet of the feed channel can be selected as 2-4 mm.

[0044] In the above-mentioned additive manufacturing apparatus, the feed channel 1 can be of equal diameter, or the hole on the outer surface of the stationary shoulder body 5 can be large and the hole on the inner wall can be small; the hole can be opened radially inward and downward, or the spiral hole can be offset along the direction of rotation of the stirring head. The additive material enters from the feed channel 1 through an external feeder.

[0045] The additive manufacturing method using the additive manufacturing apparatus provided in this embodiment is as follows: Step 1: Polish the surface of substrate 6 to remove surface stains, oxides, etc., and then clean it with acetone; Step 2: Clamp the stirring head 4 and the stationary shoulder body 5 on the main shaft, set the stirring head to a downward depth of 1-2mm, and ensure that the feed channel 1 of the stationary shoulder body 5 is located at the front edge of the stationary shoulder body 5 and the forming port 2 is located at the rear edge of the stationary shoulder body 5. Step 3: Start the friction stir welding machine. The stirring head 4 rotates at 1500-4000 rpm. Then, the additive material is fed into the cavity structure 3 through the feeding channel 1. After being stirred and rubbed by the stirring head 4, it reaches a plasticized state. Then, the plasticized material is deposited and formed on the rear side of the welding direction through the forming port 2 and cooled. Step 4: When the additive layer 7 begins to form, the welding speed is set to 300-1500 mm / min and the material is continuously fed into the cavity structure 3 through the feed channel 1 at a certain speed, resulting in a densely formed additive layer 7 on the rear side of the welding direction.

[0046] The contents not described in detail in this specification are prior art known to those skilled in the art. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. An additive manufacturing apparatus, characterized in that, It includes a stationary shoulder, a stirring head, a motor, a robotic arm, and a rotating spindle located on the robotic arm; the stirring head is mounted on the rotating spindle and disposed within an axial through hole in the body of the stationary shoulder; there is an annular cavity structure between the stirring head and the inner wall of the body of the stationary shoulder; The stationary shoulder includes a shoulder body with an axial through hole for receiving the stirring head to form a welding tool suitable for additive manufacturing. A feed channel is formed within the stationary shoulder body, inclined towards the working end of the stationary shoulder body to ensure that the material to be filled smoothly reaches the outlet and enters the cavity structure. The inlet of the feed channel is located outside the stationary shoulder body, and the outlet is located inside the stationary shoulder body, close to the working end of the stationary shoulder body. The outlet is lower than the inlet. "Close to the working end" means that the outlet of the feeding channel can be connected to the cavity structure, thereby providing material for additive manufacturing; the working end face of the stationary shoulder body has a forming opening, which is a notch structure located on the stationary shoulder body; The cavity structure is connected to the feeding channel at the front end and to the forming port at the rear end. During additive manufacturing, the stirring head rotates to generate tangential force, which promotes the entry of filaments and granules from the feeding channel into the cavity structure. During operation, the stationary shoulder body contacts the substrate, leaving only the forming opening at the rear edge of the stationary shoulder body for the formation of the additive layer; the feed channel in the stationary shoulder structure ensures that the filling material can smoothly reach the cavity structure, and the filling material in the cavity structure can fully contact the substrate to realize the formation of the additive layer on the substrate.

2. The additive manufacturing apparatus as described in claim 1, characterized in that, The forming port is obtained by grooving the rear edge of the stationary shoulder body; the forming port is located on the opposite side of the outlet of the feed channel so that the material to be filled has enough time and space to be stirred and plasticized in the cavity structure.

3. The additive manufacturing apparatus as described in claim 1, characterized in that, The inlet diameter of the feed channel is greater than or equal to the outlet diameter.

4. The additive manufacturing apparatus as described in claim 1, characterized in that, The stationary shoulder body has a feed channel inclined towards the working end to ensure that the filler material can smoothly reach the working end position. There is a forming port on the working end face. The plastic filler material obtained by stirring and friction accumulates on the rear edge of the stationary shoulder body through the forming port to form an additive layer to achieve the purpose of additive manufacturing. The filler material can only be extruded from the forming port to form the additive layer and will not overflow from other positions. The filler material can be confined from the end face sidewall of the stationary shoulder body, without the need for additional devices to prevent material from flowing out.

5. The additive manufacturing apparatus as described in claim 1, characterized in that, The feeding channel is a straight channel or a spiral channel; The spiral channel is a spiral hole offset along the rotation direction of the stirring head, which can promote the filling material to enter the cavity structure from the feeding channel under the rotation and shearing action of the stirring head.

6. The additive manufacturing apparatus as claimed in claim 1, characterized in that, The outer diameter of the working end of the stationary shoulder is 20-40mm, and the inner diameter is 10-20mm.

7. The additive manufacturing apparatus as claimed in claim 1, characterized in that, The notched structure has a horizontal width of 10-20mm and a depth of 2-4mm. The notched structure slopes downwards from the inside out, with an inclination angle of 5-10°.

8. An additive manufacturing method using the additive manufacturing apparatus as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Step S1: Mount the stationary shoulder and the stirring head onto the main shaft of the friction stir welding equipment, and set the downward pressure of the stirring head; and ensure that the inlet of the feed channel of the stationary shoulder is located in front of the welding tool travel direction, and the forming port is located in the rear of the welding tool travel direction. Step S2: Start the friction stir welding equipment, feed the additive material into the cavity structure through the feeding channel, and achieve a plasticized state through the stirring and friction of the stirring head. Then, the plasticized material is deposited into an additive layer on the rear side of the welding direction through the forming port. Step S3: When the additive layer begins to form, control the movement of the welding tool to form a continuous additive layer.

9. The additive manufacturing method as described in claim 8, characterized in that, The stirring head rotates at 1500-4000 rpm and the downward thrust is 1-2 mm.

10. The additive manufacturing method as described in claim 8, characterized in that, The welding speed of the stirring head and the stationary shoulder is 300-1500 mm / min; The additive material is a filament with a diameter of 1-3 mm, or a granular material with a particle diameter of 1-3 mm.

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