Fastening structure of copper clad aluminum material

Abstract

The utility model discloses a fastening structure of copper clad aluminum material in the technical field of fastener, including bolt and setting first conical washer, conical pipe, second conical washer and nut on bolt in assembly direction in proper order, the head of bolt and first conical washer are located one end of copper clad aluminum material, second conical washer and nut are located the other end of copper clad aluminum material, and conical pipe is located inside copper clad aluminum material. This fastening structure adopts the symmetrical structure of "bolt + conical washer + conical pipe + conical washer + nut", and through conical pipe and upper and lower conical washer constitutes clearance compensation unit, when aluminum matrix produces plastic deformation because of high temperature, conical pipe fills the clearance through axial slight expansion, and lower conical washer taper surface self -locking effect locks residual pre -tightening force simultaneously, forms the closed -loop control of deformation -compensation -locking, realizes stress self -adaptive adjustment through the geometric adaptation of rigid taper surface, and it has good application prospect in the fastening of copper clad aluminum material.

Description

Technical Field

[0001] This utility model relates to the field of fasteners, specifically to a fastening structure made of copper-clad aluminum material. Background Technology

[0002] In copper-clad aluminum busbars, the aluminum matrix is ​​prone to creep under high temperatures (≥120℃) and continuous stress. When fixed with ordinary bolts, it is prone to loosening under harsh conditions such as extreme cold and heat, electric current surges, and repeated temperature rises and falls during long-term service. Furthermore, the thermal expansion coefficients of copper and aluminum differ by as much as 35%. In the thermal cycling process from -60℃ to 150℃, the difference in expansion and contraction between the two can reach 30%. This difference causes the bolt preload to continuously decrease at a rate of 1.2% to 1.5% per cycle through the bolt connection, resulting in periodic alternating stress at the connection site, which cannot maintain the long-term stability of the connection.

[0003] CN103697046A discloses a novel fastening bolt, comprising a nut, a bolt, and an anti-loosening washer. The surface of the anti-loosening washer near the nut is tapered, and a radial groove is provided on the outer wall of the bolt shaft. An axial through hole is provided at the center of the bolt. When the bolt is tightened, the tapered surface deforms, acting as an elastic washer to prevent the bolt from loosening. However, ordinary nut-washer combinations (flat washer + spring washer) are not suitable for copper-clad aluminum busbars, which are prone to forming connection gaps at high temperatures due to creep characteristics, resulting in failure with a tightening force loss exceeding 35%, and thus failing to meet the service requirements in extreme environments.

[0004] CN207687140U discloses a pull-out type multi-stage expansion bolt, comprising a bolt body, a rotating nut, a micro-connecting expansion tube, a tapered tube, and at least one section of tapered expansion tube. The micro-connecting expansion tube, the tapered expansion tube, and the tapered tube are sequentially fitted onto the bolt body. One end of the tapered expansion tube is a tapered end, and the other end is an expansion end. Both ends of the micro-connecting expansion tube are expansion ends. The tapered end of the tapered expansion tube is inserted into the expansion end of the head of the micro-connecting expansion tube, and the tapered tube is inserted into the expansion end of the tapered expansion tube. After installation, the hole wall is tightened bidirectionally. Multi-stage expansion is achieved according to the hole wall depth and tensile and seismic requirements. After each stage of expansion is completed, the next stage begins to expand, and the entire hole wall is uniformly expanded and stressed at the front, middle, and rear sections. However, this expansion bolt is used in wall and ground applications, where there is no material creep problem. The above structure lacks a dynamic gap compensation mechanism and cannot be applied to the fixing of copper-clad aluminum materials. Utility Model Content

[0005] The purpose of this invention is to provide a fastening structure for copper-clad aluminum material, which solves the problem that existing fastener structures lack an active compensation mechanism and cannot maintain a long-term stable connection.

[0006] This utility model achieves the above objectives through the following technical solutions:

[0007] A fastening structure for copper-clad aluminum material includes a bolt and a first conical washer, a conical tube, a second conical washer, and a nut arranged sequentially on the bolt in the assembly direction. The first and second conical washers are symmetrically arranged at both ends of the conical tube. The head of the bolt and the first conical washer are located at one end of the copper-clad aluminum material, the second conical washer and the nut are located at the other end of the copper-clad aluminum material, and the conical tube is located inside the copper-clad aluminum material.

[0008] The tapered tube includes a tube body and tapered tensioning part one and tapered tensioning part two located at both ends of the tube body. The tapered surfaces of the first tapered gasket and the second tapered gasket face the tapered tensioning part one and the tapered tensioning part two, respectively, and are used to push the tapered tensioning part to deform during tightening.

[0009] As a further improvement to the above-mentioned utility model, the conical tensioning part one and the conical tensioning part two are provided with a number of symmetrical slots.

[0010] As a further improvement to the above-mentioned utility model, the first conical gasket and the second conical gasket are made of steel, and the conical tube is made of copper.

[0011] As a further improvement to the above-mentioned utility model, the taper of the conical surface in both the first conical gasket and the second conical gasket is 150°.

[0012] As a further improvement to the above-mentioned utility model, the taper range of both the first tapered tensioning part and the second tapered tensioning part is 5°-15°.

[0013] As a further improvement to the above-mentioned utility model, the taper of the first and second tapered tensioning parts is 6°.

[0014] As a further improvement to the above-mentioned utility model, the diameter of the tapered end of the first tapered gasket and the second tapered gasket is smaller than the diameter of the end of the tapered tensioning part one and the tapered tensioning part two.

[0015] As a further improvement to the above-mentioned utility model, a spring washer is provided between the second conical washer and the nut.

[0016] The beneficial effects of this utility model are as follows: It adopts a symmetrical structure of "bolt + conical pad + conical tube + conical pad + nut," with the conical tube and upper and lower conical pads forming a gap compensation unit. When the aluminum substrate undergoes plastic deformation due to a high temperature of 150℃, the conical tube fills the gap through slight axial expansion and contraction. Simultaneously, the self-locking effect of the lower conical pad locks the residual preload, forming a closed-loop control of deformation-compensation-locking. This constructs a dual structure of "active compensation for thermal expansion difference - dynamic suppression of creep gap." This structure achieves adaptive stress adjustment through the geometric adaptation of the rigid conical surface. Attached Figure Description

[0017] Figure 1 This is a practical application diagram of the fastening structure of the copper-clad aluminum material of this utility model;

[0018] Figure 2 This is a schematic diagram of the fastening structure connecting the copper-clad aluminum material to the copper-clad aluminum busbar according to this utility model;

[0019] Figure 3 This is an exploded structural diagram of the fastening structure of the copper-clad aluminum material of this utility model.

[0020] Figure 4 This is a schematic diagram of the tapered tube structure of this utility model;

[0021] Figure 5 This is a cross-sectional schematic diagram of the fastening structure of the copper-clad aluminum material of this utility model.

[0022] Figure 6 For the present utility model Figure 5 Enlarged diagram of point A.

[0023] In the diagram: 1. Bolt; 2. First conical washer; 3. Conical tube; 3.1. Tube body; 3.2. First conical tensioning part; 3.3. Second conical tensioning part; 3.4. Groove; 4. Second conical washer; 5. Nut. Detailed Implementation

[0024] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0025] like Figure 3 As shown, the fastening structure of the copper-clad aluminum material in this embodiment includes a bolt 1 and a first conical washer 2, a conical tube 3, a second conical washer 4, and a nut 5 arranged sequentially on the bolt 1 in the assembly direction. After assembly, as shown... Figure 1-2 As shown, the head of bolt 1 and the first conical washer 2 are located at one end of the copper-clad aluminum material, the second conical washer 4 and the nut 5 are located at the other end of the copper-clad aluminum material, and the conical tube 3 is located inside the copper-clad aluminum material. The first conical washer 2 and the second conical washer 4 are symmetrically located at both ends of the conical tube 3 to ensure uniform force transmission during assembly.

[0026] Bolt 1, by locking with nut 5, pushes the first conical washer 2 and the second conical washer 4 to forcibly deform the conical tube 3 to complete the locking of the copper-aluminum busbar; and the deformation of the conical tube controls the creep of the aluminum material; after the hot and cold cycle, the preload retention rate of the bolt (M16 specification) reaches 90%, which can effectively solve the loosening problem caused by the synergy of thermal expansion difference and material creep, and is compatible with two-plate / three-plate connection scenarios of copper-clad aluminum materials.

[0027] like Figure 4-5 As shown, the tapered tube 3 includes a tube body 3.1 and tapered tensioning portions 3.2 and 3.3 located at both ends of the tube body 3.1. The tapered surfaces of the first tapered gasket 2 and the second tapered gasket 4 face the tapered tensioning portions 3.2 and 3.3 respectively, and are used to push the tapered tensioning portions to deform during tightening. The taper of the tapered surfaces of the first tapered gasket 2 and the second tapered gasket 4 is 150°. The taper range of the tapered tensioning portions 3.2 and 3.3 is 5°-15°, preferably 6°. The tapered surfaces of the first tapered gasket 2 and the second tapered gasket 4 form a taper angle of 120°-150° with the tapered tensioning portions 3.2 and 3.3 of the tapered tube 3 to transmit the torque of the bolt 1 to the tapered tube 3, causing it to plastically deform and compensating for the creep gap of the aluminum material. This parameter range is determined by the difference in the thermal expansion coefficients of copper and aluminum (copper 17×10). -6 / ℃, Aluminum 23×10 -6 Theoretical calculations and experimental verifications have shown that, within the entire temperature range of -60℃ to 150℃, the axial expansion and contraction difference of copper and aluminum can be precisely offset by 30% through axial expansion and contraction (0.1-0.3mm). Beyond this range, effective compensation may not be possible.

[0028] like Figure 4 As shown, several symmetrical slots 3.4 are provided on the conical tensioning part 1 3.2 and the conical tensioning part 2 3.3. The conical pad will quickly deform the conical tensioning part by pushing it. Figure 6 As shown, the diameter of the conical end of the first conical gasket 2 and the second conical gasket 4 is smaller than the diameter of the ends of the conical tensioning parts 3.2 and 3.3. This allows the conical gaskets to better expand the conical tube. When the conical gaskets move, the ends of the conical tensioning parts can contact the conical surfaces of the conical gaskets, thus sliding smoothly and being expanded, rather than being squeezed and deformed by the conical gaskets, leading to failure of the fastening structure.

[0029] Furthermore, the first conical gasket 2 and the second conical gasket 4 are made of steel, and the conical tube 3 is made of copper. The steel conical gasket pushes the copper conical tube 3 to deform rapidly, encasing the copper-aluminum busbar inside and preventing the aluminum from creeping; thus completing the copper-aluminum busbar bolt locking action.

[0030] Furthermore, a spring washer can be added between the second conical washer 4 and the nut 5 to enhance the tightening force and prevent loosening.

[0031] Example 1:

[0032] Bolt specifications: M16 / 12.9 grade, length 70mm;

[0033] Tapered tube parameters: Material: 304 stainless steel, taper: 6°, length: 42mm, inner diameter: 16.2mm, outer diameter: 17mm; Tapered gasket parameters: Material: 304 stainless steel, thickness: 3mm, diameter: 28mm, taper angle: 150°.

[0034] Copper-clad aluminum busbar parameters: total thickness 40mm, two-plate overlapping structure;

[0035] Assembly process: Use a digital torque wrench and follow the procedure of "pre-tightening force 140N → holding pressure for 30s → re-tightening to 140N". The nut is a grade 8 galvanized hexagonal nut.

[0036] Test conditions: The high and low temperature test chamber was subjected to a cycle of -60℃ (holding temperature for 2 hours) → 150℃ (holding temperature for 2 hours) (temperature rise and fall controlled within 2 hours);

[0037] Results: After 30 cycles, the preload retention rate was over 90%. Post-disassembly observation revealed a 0.028mm gap in the aluminum busbar contact surface due to creep.

[0038] Comparative Example 1:

[0039] The difference from Example 1 is that it adopts the traditional connection structure of "bolt + flat washer + spring washer + nut", without the tapered tube and tapered gasket. The flat washer is made of 304 stainless steel (thickness 3mm, diameter 28mm), and the spring washer is 65Mn. The cyclic test conditions (-60℃ (holding for 2h) → 150℃ (holding for 2h) for a total of 30 times) are completely consistent with Example 1.

[0040] Test results: After 30 cycles, the preload retention rate was 62% (30 percentage points lower than in Example 1). Disassembly revealed a 0.12mm gap at the aluminum busbar contact surface due to creep, and the spring pad's elastic coefficient decreased by 40%. This verifies the technical shortcomings of traditional structures in compensating for thermal expansion differences and suppressing creep. The results demonstrate the irreplaceable role of the double-cone gasket in ensuring uniform force transmission and resisting creep.

[0041] The embodiments described above are merely examples of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these modifications and improvements all fall within the protection scope of this utility model.

Claims

1. A fastening structure for copper-clad aluminum material, characterized in that, The assembly includes a bolt (1) and a first conical washer (2), a conical tube (3), a second conical washer (4), and a nut (5) arranged sequentially on the bolt (1) in the assembly direction. The first conical washer (2) and the second conical washer (4) are symmetrically arranged at both ends of the conical tube (3). The head of the bolt (1) and the first conical washer (2) are located at one end of the copper-clad aluminum material, the second conical washer (4) and the nut (5) are located at the other end of the copper-clad aluminum material, and the conical tube (3) is located inside the copper-clad aluminum material. The tapered tube (3) includes a tube body (3.1) and tapered tensioning part one (3.2) and tapered tensioning part two (3.3) located at both ends of the tube body (3.1). The tapered surfaces of the first tapered gasket (2) and the second tapered gasket (4) face the tapered tensioning part one (3.2) and the tapered tensioning part two (3.3) respectively, and are used to push the tapered tensioning part to deform when tightening.

2. The fastening structure for copper-clad aluminum material according to claim 1, characterized in that, The first tapered tensioning part (3.2) and the second tapered tensioning part (3.3) are provided with a number of symmetrical slots (3.4).

3. The fastening structure for copper-clad aluminum material according to claim 1, characterized in that, The first conical gasket (2) and the second conical gasket (4) are made of steel, and the conical tube (3) is made of copper.

4. The fastening structure for copper-clad aluminum material according to claim 1, characterized in that, The taper of the conical surface in both the first conical gasket (2) and the second conical gasket (4) is 150°.

5. The fastening structure for copper-clad aluminum material according to claim 4, characterized in that, The taper range of both the first tapered tensioning part (3.2) and the second tapered tensioning part (3.3) is 5-15°.

6. The fastening structure for copper-clad aluminum material according to claim 5, characterized in that, The taper of the first tapered tensioning part (3.2) and the second tapered tensioning part (3.3) is 6°.

7. The fastening structure for copper-clad aluminum material according to claim 1, characterized in that, The diameter of the tapered end of the first tapered gasket (2) and the second tapered gasket (4) is smaller than the diameter of the end of the tapered tensioning part one (3.2) and the tapered tensioning part two (3.3).

8. The fastening structure for copper-clad aluminum material according to claim 1, characterized in that, A spring washer is provided between the second conical washer (4) and the nut (5).

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