Aluminum bar bolt connecting structure and aluminum bar machining method

Abstract

The invention discloses an aluminum bar bolt connection structure and an aluminum bar processing method, and relates to the field of power equipment.The aluminum bar bolt connection structure comprises an aluminum bar main body, a first metal functional piece is fixed to the aluminum bar main body, a second metal functional piece is fixed to the face, away from the first metal functional piece, of the aluminum bar main body, and a bolt is arranged on the aluminum bar main body; through holes corresponding to the bolts are formed in the aluminum bar body, and conical locking assemblies are arranged in the through holes in the aluminum bar body. The first metal functional piece is a pure nickel piece with the thickness of 0.1 mm, the second metal functional piece is a nickel-copper alloy piece with the thickness of 0.2 mm, and the bimetal functional pieces are arranged in a differentiated mode, so that functional separation of optimized connection on one side and reinforced supporting on the other side is achieved, the mechanical reliability and the electrical stability of the whole connection structure are optimized, and the service life of the whole connection structure is prolonged. The conical locking assembly provides active mechanical locking and forms double creep-resistant guarantee with the functional piece.

Description

Technical Field

[0001] This application relates to the field of power equipment, and in particular to an aluminum busbar bolt connection structure and an aluminum busbar processing method. Background Technology

[0002] Aluminum busbars are plate-shaped or strip-shaped conductive materials made of aluminum alloy. Due to their good conductivity, high mechanical strength, and lower cost and weight compared to copper, they are widely used in industrial and civil fields that require the carrying of large currents. In power system distribution cabinets, transformers, as well as battery packs for new energy vehicles, industrial calcium carbide furnaces and other equipment, aluminum busbars serve as key conductive busbars, undertaking the important functions of collecting, distributing and transmitting electrical energy.

[0003] In practical applications, aluminum busbars are usually fixed to other conductors electrically and mechanically by bolting. The reliability of this connection method is directly related to the safety and stable operation of the entire power system. An ideal bolted connection should have low and stable contact resistance, strong mechanical connection strength, and the ability to resist environmental factors under long-term use.

[0004] However, existing aluminum busbars generally have high contact resistance when directly bolted. In addition, aluminum itself is relatively soft and is prone to creep deformation under the long-term preload of bolts, which leads to the decay of preload, loosening of the connection, and thus increased contact resistance, local overheating, and even the risk of fire. Summary of the Invention

[0005] The purpose of this application is to address the problem of high contact resistance commonly found in existing aluminum busbars when directly bolted together, as mentioned in the background art. Additionally, aluminum itself is relatively soft and prone to creep deformation under long-term bolt preload, leading to preload attenuation, loosening of the connection, and consequently, increased contact resistance, localized overheating, and even the risk of fire. This application provides an aluminum busbar bolt connection structure and an aluminum busbar processing method.

[0006] To achieve the above objectives, this application specifically adopts the following technical solution: An aluminum busbar bolt connection structure includes an aluminum busbar body, a first metal functional piece fixed on the aluminum busbar body, a second metal functional piece fixed on the side of the aluminum busbar body away from the first metal functional piece, the second metal functional piece having a thickness greater than the first metal functional piece, a bolt provided on the aluminum busbar body, a through hole corresponding to the bolt being provided on the aluminum busbar body, and a conical locking component being provided in the through hole on the aluminum busbar body.

[0007] By adopting the above technical solution, the first metal functional piece is a 0.1mm thick pure nickel sheet, and the second metal functional piece is a 0.2mm thick nickel-copper alloy sheet. The differentiated bimetallic functional pieces achieve functional separation that optimizes connection on one hand and strengthens support on the other, thereby optimizing the mechanical reliability and electrical stability of the overall connection structure. The conical locking assembly provides active mechanical locking, forming a double anti-creep guarantee with the functional pieces.

[0008] Furthermore, the conical locking assembly includes a conical ring disposed on the aluminum busbar body, the conical ring being located in a through hole within the aluminum busbar body, the outer surface of the conical ring having a toothed structure, and a conical block being fixed to the end of the bolt, the inclined surface of the conical block engaging with the inner conical surface of the conical ring.

[0009] By adopting the above technical solution, the axial tensile force of the bolt is converted into the radial expansion force on the conical ring. The bolt drives the conical block to squeeze the conical ring, converting the axial force into the radial force. As a result, after the conical ring expands, the toothed structure on its outer surface can penetrate the softer aluminum strip body through the hole wall, forming a strong mechanical self-locking mechanism. This greatly resists loosening caused by vibration and creep, ensuring the long-term stability of the preload.

[0010] Furthermore, the conical ring is provided with a plurality of circumferentially distributed locking blocks, which penetrate the conical ring and are movably connected to the conical ring.

[0011] By adopting the above technical solution, when the conical ring is squeezed by the conical block and expands radially, the locking block can be further embedded in the through hole wall of the aluminum busbar body, which enhances the connection strength between the conical ring and the aluminum busbar body, thereby effectively preventing the connection from loosening due to long-term use or external factors, and further improving the creep resistance performance.

[0012] Furthermore, the outer surface of the second metal functional sheet that contacts the external conductor is provided with a micro-tooth structure.

[0013] By adopting the above technical solution, the micro-tooth structure can increase the contact area and friction between the second metal functional sheet and the external conductor, thereby making the connection more stable and less prone to relative sliding under external force, thus improving the stability and reliability of the overall connection.

[0014] Furthermore, a micro-anchoring layer is provided at the interface between the aluminum busbar body and the first and second metal functional sheets, and the micro-anchoring layer is formed on the surface of the aluminum busbar body by a laser texturing process.

[0015] By adopting the above technical solution, the micro-anchoring layer formed by the laser texturing process can form a micro-level mechanical interlock between the aluminum busbar body and the first and second metal functional pieces, thereby greatly enhancing the bonding strength between them, effectively preventing the peeling between the functional pieces and the aluminum busbar body, and further improving the overall creep resistance and connection strength performance.

[0016] Furthermore, a compensation washer is provided between the head of the bolt and the first metal functional piece, and the compensation washer is an elastic sleeve portion extending into the through hole.

[0017] By adopting the above technical solution, the elastic sleeve part of the compensating washer can undergo elastic deformation when the bolt is pre-tightened, compensating for dimensional changes caused by manufacturing errors or temperature changes, thereby ensuring that the bolt always maintains a suitable pre-tightening force, avoiding loosening or damage to the connection due to insufficient or excessive pre-tightening force, and improving the stability and durability of the connection.

[0018] Furthermore, several protruding structures are fixed on the side of the first metal functional sheet away from the aluminum busbar body.

[0019] By adopting the above technical solution, the protruding structure can increase the contact area and friction between the first metal functional piece and the external connecting parts, making the connection more solid. At the same time, the protruding structure can also play a positioning and guiding role, making it convenient for installation and disassembly, and improving the convenience and reliability of the overall connection.

[0020] A method for processing aluminum busbars, the method being as follows: S1: Surface pretreatment, cleaning and deoxidizing the surfaces of the first and second metal functional pieces to be welded on the aluminum busbar body; S2: Construct a micro-anchoring layer by processing the surface of the first and second metal functional pieces to be welded on the aluminum busbar body using a laser texturing process. S3: Welding functional sheet. An aluminum-silicon alloy brazing foil is placed on the welding surfaces on both sides of the aluminum busbar as a composite intermediate layer. The first metal functional sheet and the second metal functional sheet are precisely aligned and cover the brazing foil. S4: High-frequency induction brazing. Under a hydrogen protective atmosphere, the assembly is heated by high-frequency induction heating while pressure is applied, so that the temperature reaches above the eutectic point of aluminum-silicon alloy up to 620℃±10℃. After holding at the temperature, it is cooled to form a strong metallurgical bond structure. S5: Machining connection holes, machining through holes in the first metal functional piece, the aluminum busbar body and the second metal functional piece on the assembly; S6: Post-processing, imprinting micro-tooth or raised structures on the outer surfaces of the first and second metal functional sheets, and cleaning the finished product.

[0021] In summary, this application includes at least one of the following beneficial effects; 1. In this application, by using differentiated first and second metal functional plates, a 0.2mm nickel plate provides the main compressive strength and creep resistance, while a 0.1mm nickel plate, while ensuring good electrical conductivity, has a relatively higher peel strength at its welding interface with the aluminum busbar. This achieves both optimized connection and enhanced support, thereby optimizing the mechanical reliability and electrical stability of the overall connection structure. At the same time, the design of the conical locking assembly cleverly converts the axial tensile force of the bolt into radial expansion force, allowing the toothed structure on the outer surface of the conical ring to penetrate deeply into the through hole wall of the aluminum busbar body, forming a strong mechanical self-locking mechanism that greatly resists loosening caused by vibration and creep.

[0022] 2. In this application, by setting circumferentially distributed locking blocks on the conical ring, these locking blocks can be further embedded into the through hole wall of the aluminum busbar body when the conical ring is compressed and expands radially, thereby enhancing the connection strength with the aluminum busbar body and effectively preventing loosening of the connection due to long-term use or external factors, further improving the creep resistance. Moreover, the micro-tooth structure set on the contact surface between the second metal functional piece and the external conductor increases the contact area and friction, making the connection more stable and less prone to relative slippage, thus improving the overall stability and reliability of the connection.

[0023] 3. In this application, by setting a micro-anchoring layer formed by laser texturing process on the mating surface of the aluminum busbar body and the first and second metal functional pieces, mechanical interlocking at the micro level is achieved, which greatly enhances the bonding strength, effectively prevents the peeling phenomenon between the functional pieces and the aluminum busbar body, and further improves the overall creep resistance and connection strength performance. At the same time, the compensation washer set between the bolt head and the first metal functional piece has an elastic sleeve part that can undergo elastic deformation during pre-tightening to compensate for dimensional changes, ensuring that the bolt always maintains a suitable pre-tightening force, avoiding loosening or damage to the connection, and improving the stability and durability of the connection. Attached Figure Description

[0024] Figure 1 This is a first three-dimensional structural schematic diagram of the aluminum bolt connection structure with anti-creep and high connection strength in this application; Figure 2 This is a second three-dimensional structural diagram of the aluminum bolt connection structure with anti-creep and high connection strength in this application; Figure 3 This is a schematic diagram of the first cross-section of the aluminum bolt connection structure with creep resistance and high connection strength in this application; Figure 4This is a schematic diagram of the second cross-section of the aluminum bolt connection structure with creep resistance and high connection strength in this application; Figure 5 This application Figure 3 Enlarged view of point A in the middle; Figure 6 This application Figure 4 Enlarged diagram of point B in the middle.

[0025] Explanation of reference numerals in the attached figures: 1. Aluminum busbar body; 2. First metal functional piece; 3. Second metal functional piece; 4. Bolt; 5. Conical locking assembly; 51. Conical ring; 52. Toothed structure; 53. Conical block; 54. Locking block; 55. Micro-toothed structure; 6. Through hole; 7. Compensating washer; 8. Protruding structure; 9. Micro-anchoring layer. Detailed Implementation

[0026] The following is in conjunction with the appendix Figure 1 —6 provides further details regarding this application.

[0027] This application discloses an aluminum busbar bolt connection structure and an aluminum busbar processing method.

[0028] Reference Figure 1 , Figure 2 and Figure 3 A creep-resistant, high-connection-strength aluminum strip bolt 4 connection structure includes an aluminum strip body 1, a first metal functional piece 2 fixed on the aluminum strip body 1, a second metal functional piece 3 fixed on the side of the aluminum strip body 1 away from the first metal functional piece 2, the thickness of the second metal functional piece 3 being greater than that of the first metal functional piece 2, a bolt 4 provided on the aluminum strip body 1, a through hole 6 corresponding to the bolt 4 opened on the aluminum strip body 1, and a conical locking component 5 provided in the through hole 6 on the aluminum strip body 1.

[0029] The first metal functional piece 2 is a 0.1mm thick pure nickel sheet, mainly used for connection with the external copper conductor. The second metal functional piece 3 is a 0.2mm thick nickel-copper alloy sheet, mainly used as a back support layer. The conical locking assembly 5 is interference-fitted into the through hole 6 of the aluminum busbar body 1. During assembly, the external conductor is attached to the outside of the first metal functional piece 2. The bolt 4 passes through the first metal functional piece 2, the aluminum busbar body 1, and the second metal functional piece 3, and is tightened with the nut on the external conductor. During the tightening process, the conical locking assembly 5 is activated to further support the aluminum busbar body 1. Through the differentiated bimetallic functional pieces, the function separation of optimizing connection on one hand and strengthening support on the other is achieved, thereby optimizing the mechanical reliability and electrical stability of the overall connection structure. The conical locking assembly 5 provides active mechanical locking, forming a double anti-creep guarantee with the functional pieces.

[0030] Reference Figure 2 , Figure 3 and Figure 5 The conical locking assembly 5 includes a conical ring 51 disposed on the aluminum busbar body 1. The conical ring 51 is located in the through hole 6 inside the aluminum busbar body 1. The outer surface of the conical ring 51 is provided with a toothed structure 52. The end of the bolt 4 is fixed with a conical block 53. The inclined surface of the conical block 53 cooperates with the inner conical surface of the conical ring 51. The conical ring 51 is made of high-carbon steel or stainless steel, with a hardness much higher than that of the aluminum busbar body 1. The toothed structure 52 on its outer surface is a one-way helical tooth to prevent reverse rotation during tightening. The conical block 53 is connected to the end of the bolt 4 by thread or welding. When the bolt 4 is tightened, the bolt 4 drives the conical block 53 to move towards the nut. The conical block 53 presses against the inner conical surface of the conical ring 51, converting the axial tension of the bolt 4 into a radial expansion force on the conical ring 51. By having the bolt 4 drive the conical block 53 to press against the conical ring 51, the axial force is converted into a radial force. Thus, after the conical ring 51 expands, the toothed structure 52 on its outer surface can penetrate deeply into the softer aluminum busbar body 1 through hole 6 wall, forming a strong mechanical self-locking, which greatly resists loosening caused by vibration and creep, and ensures the long-term stability of the preload.

[0031] Reference Figure 5 and Figure 6 A conical ring 51 is provided with several circumferentially distributed locking blocks 54. The locking blocks 54 penetrate the conical ring 51 and are movably connected to it. The locking blocks 54 are cylindrical sliders that are embedded in the corresponding sliding grooves of the conical ring 51 and can slide radially within the grooves. When the conical ring 51 is squeezed by the conical blocks 53 and expands radially, it will push the internal locking blocks 54 to move synchronously along the groove towards the hole wall. Finally, the outer surface of the locking blocks 54 is tightly pressed against the hole wall of the through hole 6. By providing locking blocks 54 on the conical ring 51, the locking blocks 54 can be squeezed against the aluminum busbar body 1 when squeezed, thereby increasing the contact and pressure of the aluminum busbar body 1 through hole 6 wall and distributing the concentrated stress to multiple locking blocks 54, further improving the shear resistance and overall reliability of the connection structure, which is especially suitable for high vibration environments.

[0032] Reference Figure 2 , Figure 4 and Figure 6 The outer surface of the second metal functional piece 3 that contacts the external conductor is provided with a micro-tooth structure 55. The micro-tooth structure 55 is formed by precision stamping or laser engraving, and has a ring-shaped serrated or wavy pattern with a tooth height of 0.05-0.1mm. Under the pre-tightening force of the bolt 4, the hard micro-tooths on the surface of the second metal functional piece 3 will be partially embedded into the surface of the external conductor it contacts. By using the micro-tooth structure 55 to destroy the oxide film on the contact surface, the effective contact area can be increased, the contact resistance can be reduced, and a micro-mechanical interlock can be formed, which can effectively suppress the fretting wear of the contact surface under vibration and ensure the long-term stability and safety of the electrical connection.

[0033] Reference Figure 1 and Figure 2 A micro-anchoring layer 9 is provided at the bonding surface between the aluminum busbar body 1 and the first metal functional piece 2 and the second metal functional piece 3. The micro-anchoring layer 9 is formed on the surface of the aluminum busbar body 1 by laser roughening process. A pulsed fiber laser is used to scan the surface of the aluminum busbar body 1 to be welded, forming a rough surface composed of countless micron-level molten protrusions and pits. The arithmetic mean deviation Ra value of its profile is between 3μm and 10μm. Laser roughening is a pretreatment process before welding. Then, brazing is performed on the roughened surface. The brazing filler metal melts and encapsulates these micro-protrusions. By setting the micro-anchoring layer 9 on the surface of the aluminum busbar, the micro-anchoring layer 9 transforms the traditional surface bonding into a three-dimensional mechanical interlocking and metallurgical bonding, thereby increasing the bonding strength of the welding interface by several times and effectively preventing the functional pieces from falling off the aluminum busbar under long-term stress or thermal cycling.

[0034] Reference Figure 2 , Figure 3 and Figure 5 A compensating washer 7 is provided between the head of bolt 4 and the first metal functional piece 2. The compensating washer 7 is an elastic sleeve extending into the through hole 6. The compensating washer 7 is a one-piece structure made of spring steel, with a wave spring at the top and a thin-walled sleeve extending into the through hole 6 at the bottom. The inner diameter of the sleeve is slightly larger than the diameter of bolt 4, and the outer diameter is slightly smaller than the diameter of the through hole 6. When the nut is tightened, the compensating washer 7 is flattened. When the connection loosens slightly due to creep, the elastic restoring force of the wave spring will push bolt 4, automatically compensating for the loss of preload. By setting the compensating washer 7, the required preload of bolt 4 can be maintained for a long time, avoiding the increase in contact resistance and loosening of the connection caused by the decrease in preload, realizing active protection and greatly extending the maintenance cycle.

[0035] Reference Figure 1 , Figure 3 and Figure 5 On the side of the first metal functional piece 2 away from the aluminum busbar body 1, several protruding structures 8 are fixed. The protruding structures 8 are strip-shaped or pyramid-shaped dot arrays formed by precision stamping on the first metal functional piece 2. The dot arrays are distributed around the bolt 4 holes. When the bolt 4 is tightened, these limited, high-strength protrusions will abut against the compensating washers 7 on the bolt 4 head, forming a microscopic mechanical interlock. By allowing the protruding structures 8 to abut against the compensating washers 7 on the bolt 4 head, the stability of the bolt 4 fixing can be further improved.

[0036] A method for processing aluminum busbars, the method being as follows: S1: Surface pretreatment, cleaning and deoxidizing the surfaces of the first metal functional piece 2 and the second metal functional piece 3 to be welded to the aluminum busbar body 1; S2: Construct a micro-anchoring layer 9 by processing the micro-anchoring layer 9 on the surface of the first metal functional piece 2 and the second metal functional piece 3 to be welded on the aluminum busbar body 1 through a laser texturing process. S3: Welding functional sheet. Aluminum-silicon alloy brazing foil is placed on both sides of the aluminum busbar body 1 as a composite intermediate layer. The first metal functional sheet 2 and the second metal functional sheet 3 are precisely aligned and covered on the brazing foil. S4: High-frequency induction brazing. Under a hydrogen protective atmosphere, the assembly is heated by high-frequency induction heating while pressure is applied, so that the temperature reaches above the eutectic point of aluminum-silicon alloy up to 620℃±10℃. After holding at the temperature, it is cooled to form a strong metallurgical bond structure. S5: Machining connection holes, machining through holes 6 on the assembly to connect the first metal functional piece 2, the aluminum busbar body 1, and the second metal functional piece 3; S6: Post-processing, imprinting micro-tooth structure 55 or raised structure 8 on the outer surface of the first metal functional sheet 2 and the second metal functional sheet 3, and cleaning the finished product.

[0037] Working principle: The thinner first metal functional sheet 2 mainly serves as the electrical connection interface with the external conductor, and its properties facilitate the formation of a stable low-resistance contact. The thicker second metal functional sheet 3 acts as a strong backing layer. In addition, in actual assembly, the external conductor can be pressed against the side of the first metal functional sheet 2 or the side of the more robust second metal functional sheet 3 as needed to adapt to different spatial layouts and stress requirements. The micro-tooth structure 55 is embedded in the external conductor under the preload of the bolt 4, which not only destroys the surface oxide film to reduce contact resistance, but also forms a micro-mechanical interlock, effectively resisting fretting wear caused by vibration. When the bolt 4 is tightened, the conical block 53 at its end is pulled to compress the inner conical surface of the conical ring 51, converting the axial tension of the bolt 4 into a force that compresses the conical ring 51. The expansion force causes the toothed structure 52 on the outer surface of the conical ring 51 to penetrate deeply into the wall of the through hole 6 of the aluminum busbar body 1, forming the first mechanical locking. At the same time, the expansion of the conical ring 51 pushes the locking blocks 54 distributed in its inner circumference to move radially outward, pressing tightly against the hole wall, forming the second mechanical locking to disperse stress, which greatly enhances the shear resistance and vibration loosening resistance. The compensation washer 7 located between the bolt head and the first metal functional piece 2 is compressed and stores energy when tightened. When the aluminum material causes a slight loosening of the connection due to the creep effect, the elastic restoring force of the washer will continue to push the bolt 4, automatically compensating for the lost preload. In addition, the protruding structure 8 on the first metal functional piece 2 contacts the compensation washer 7, forming an additional micro-interlock, which further prevents the bolt 4 from rotating and loosening.

[0038] 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. An aluminum busbar bolt connection structure, comprising an aluminum busbar body (1), characterized in that: A first metal functional piece (2) is fixed on the aluminum busbar body (1). A second metal functional piece (3) is fixed on the side of the aluminum busbar body (1) away from the first metal functional piece (2). The thickness of the second metal functional piece (3) is greater than that of the first metal functional piece (2). A bolt (4) is provided on the aluminum busbar body (1). A through hole (6) corresponding to the bolt (4) is opened on the aluminum busbar body (1). A conical locking component (5) is provided in the through hole (6) on the aluminum busbar body (1).

2. The aluminum strip bolt connection structure according to claim 1, characterized in that: The conical locking assembly (5) includes a conical ring (51) disposed on the aluminum busbar body (1). The conical ring (51) is located in the through hole (6) inside the aluminum busbar body (1). The outer surface of the conical ring (51) is provided with a toothed structure (52). The end of the bolt (4) is fixed with a conical block (53). The inclined surface of the conical block (53) is engaged with the inner conical surface of the conical ring (51).

3. The aluminum strip bolt connection structure according to claim 2, characterized in that: The conical ring (51) is provided with a plurality of circumferentially distributed locking blocks (54), which penetrate the conical ring (51) and are movably connected to the conical ring (51).

4. The aluminum strip bolt connection structure according to claim 2, characterized in that: The outer surface of the second metal functional sheet (3) that contacts the external conductor is provided with a micro-tooth structure (55).

5. The aluminum strip bolt connection structure according to claim 1, characterized in that: The aluminum busbar body (1) is provided with a micro-anchoring layer (9) at the interface between it and the first metal functional piece (2) and the second metal functional piece (3). The micro-anchoring layer (9) is formed on the surface of the aluminum busbar body (1) by laser texturing process.

6. The aluminum strip bolt connection structure according to claim 1, characterized in that: A compensation washer (7) is provided between the head of the bolt (4) and the first metal functional piece (2), and the compensation washer (7) is an elastic sleeve extending into the through hole (6).

7. The aluminum strip bolt connection structure according to claim 6, characterized in that: The first metal functional piece (2) has several protruding structures (8) fixed on the side away from the aluminum busbar body (1).

8. A method for processing aluminum busbars, characterized in that: This processing method is applicable to the aluminum bolt connection structure described in any one of claims 1-7 above, and the processing method is as follows: S1: Surface pretreatment, cleaning and deoxidation treatment of the surfaces of the first metal functional piece (2) and the second metal functional piece (3) to be welded on the aluminum busbar body (1); S2: Construct a micro-anchoring layer (9), which is formed on the surface of the first metal functional piece (2) and the second metal functional piece (3) to be welded on the aluminum busbar body (1) by laser texturing process. S3: Welding functional sheet. Aluminum-silicon alloy brazing foil is placed on both sides of the aluminum busbar body (1) as a composite intermediate layer. The first metal functional sheet (2) and the second metal functional sheet (3) are precisely aligned and covered on the brazing foil. S4: High-frequency induction brazing. Under a hydrogen protective atmosphere, the assembly is heated by high-frequency induction heating while pressure is applied, so that the temperature reaches above the eutectic point of aluminum-silicon alloy up to 620℃±10℃. After holding at the temperature, it is cooled to form a strong metallurgical bond structure. S5: Machining connection holes, machining through holes (6) for the first metal functional piece (2), the aluminum busbar body (1), and the second metal functional piece (3) on the assembly. S6: Post-processing, imprinting micro-tooth structure (55) or raised structure (8) on the outer surface of the first metal functional sheet (2) and the second metal functional sheet (3), and cleaning the finished product.

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