A friction-assisted plate-pipe connection method and device

Abstract

The present invention discloses a plate-pipe connection method and device based on friction assistance, which belongs to the field of material connection technology. The friction-assisted method is adopted, under the pre-tightening force of the upper mold on the plate, the upper mold rotates and rubs the plate, so that friction heat is generated on the surface of the plate, and a gradient temperature distribution is generated in the contact area between the plate and the upper mold, thereby reducing the deformation resistance of the plate deformation area and improving its plasticity, thereby greatly reducing the extrusion force of the upper mold and reducing the requirements for equipment; when the plate is at a certain temperature, the plastic flow of the material under the extrusion is more sufficient, and after the plate-pipe locking structure is formed, the gap between the plate and the pipe is smaller, the connection is more firm, and the connection strength is higher. The present invention solves the problems of high connection force and easy breakage and crushing of the connection structure of low-plasticity, high-strength plate and strong pipe.

Description

Technical Field

[0001] The present invention belongs to the technical field of material connection, and in particular relates to a plate-pipe connection method and device based on friction assistance. Background Art

[0002] Lightweight metal plate-tube connection structures are increasingly used in the automotive, chemical, food, and pharmaceutical industries, playing an important role in energy conservation, emission reduction, and cost reduction.

[0003] However, the application of lightweight, high-strength materials presents challenges to traditional manufacturing methods. For example, when welding, aluminum alloys have high thermal conductivity, a high melting point, and a large coefficient of expansion, which can easily lead to significant welding deformation and welding difficulties. Magnesium alloys are also prone to forming oxide films during welding, which can easily lead to inclusions in the weld.

[0004] In recent years, plastic joining has seen rapid development due to its environmentally friendly and high-strength properties. Its working principle is to mechanically lock sheets and pipes through plastic deformation to achieve connection. However, the plastic joining process still has certain limitations when it comes to the poor plasticity and high strength of titanium, magnesium, and aluminum alloys. This can easily lead to fracture and crushing during connection, and the high deformation resistance and high connection force can easily cause sheet warping, placing high demands on equipment load and control. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a plate-pipe connection method and device based on friction assistance, which solves the problems of high connection force and easy breakage and crushing of the connection structure between low plasticity, high strength plate and strong pipe.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention discloses a friction-assisted plate-pipe connection method, comprising the following steps:

[0008] S1: Put the pipe into the center hole of the lower die, and keep the lower die fixed;

[0009] S2: Based on the outer diameter of the tube, the center of the plate is hole-machined, and then it is sleeved onto the outside of the tube, and the plate is in contact with the upper surface of the lower die;

[0010] S3: An upper die with a tapered hole in the middle of the upper end and an annular protrusion at the lower end is placed on the outside of the pipe. The annular protrusion of the upper die is downwardly moved at a speed V1 to the upper surface of the plate and then stopped. A preload force F is applied to the plate.

[0011] S4: The upper die rotates at a constant angular velocity w. The plate generates heat energy due to the friction between the upper die and the plate, and the heat energy is transferred inside the plate and the tube. When the preset temperature T0 is reached, the upper die stops rotating.

[0012] S5: The upper die moves downward at a speed of V2 to extrude the sheet material. The sheet material undergoes plastic flow in the radial direction. The flowing sheet material squeezes the tube, causing the tube to neck inward and gradually form a mechanical lock. The upper die stops when it descends to the preset position.

[0013] S6: The upper die moves upward at a speed of V3 to the initial position and removes the sheet-to-pipe connector.

[0014] Preferably, the plate and the tube are made of titanium alloy, aluminum alloy or magnesium alloy.

[0015] Preferably, the thickness of the plate is 3 to 10 times the wall thickness of the tube, and the outer diameter of the tube is 0.9 to 0.98 times the inner diameter of the annular protrusion.

[0016] Preferably, the height of the annular protrusion is 1 to 2 times the thickness of the plate, and the width of the annular protrusion is 0.2 to 1 times the height of the annular protrusion.

[0017] Preferably, the lower surface of the annular protrusion is a plane.

[0018] Preferably, the tapered hole has a taper of 5° to 20°.

[0019] Preferably, in S3, the preload force F is 2-10 kN.

[0020] Preferably, in S4, the angular velocity w is 500-1600 rpm, and the preset temperature T0 is (0.4-0.7)T m , T m is the melting point of the sheet material.

[0021] Preferably, V1 = 1 to 5 mm / s, V2 = 0.2 to 1 mm / s, and V3 = 1 to 3 mm / s.

[0022] The device disclosed in the present invention for realizing the above-mentioned friction-assisted plate-pipe connection method includes an upper mold and a lower mold; a through hole is opened in the middle of the lower mold; a tapered hole is opened in the middle of the upper end of the upper mold, and an annular protrusion is provided at the lower end.

[0023] Compared with the prior art, the present invention has the following beneficial technical effects:

[0024] The present invention discloses a friction-assisted plate-to-pipe connection method. The friction-assisted method is used. Under the pre-tightening force of the upper die on the plate, the upper die rotates and rubs the plate, so that friction heat is generated on the surface of the plate, and a gradient temperature distribution is generated in the contact area between the plate and the upper die, thereby reducing the deformation resistance of the plate deformation area and improving its plasticity, thereby greatly reducing the extrusion force of the upper die and reducing the requirements for equipment. The friction-assisted method is used. At a certain temperature, the plastic flow of the plate material under the extrusion is more sufficient. After forming a plate-to-tube locking structure, the gap between the plate and the pipe is smaller, the combination is more firm, and the connection strength is higher. This method can be used to connect plates with low plasticity, high strength, and high brittleness. Compared with traditional plastic connection processes, it reduces the occurrence of cracks, crushing, and stress concentration in the material during the connection process, and avoids problems such as warping and tilting of the plate after large deformation. At the same time, this method can also achieve connections between thick plates and pipes, further promoting the application range of thick plate-to-pipe connectors.

[0025] Furthermore, the method is particularly suitable for low-plasticity, high-strength materials such as titanium alloys, aluminum alloys, and magnesium alloys.

[0026] Furthermore, the height of the annular protrusion is 1 to 2 times the thickness of the plate, and the width of the annular protrusion is 0.2 to 1 times the height of the annular protrusion. If the height value is too large, processing will be difficult, mold accuracy will be difficult to ensure, and the lifespan will be short. If it is too small, the size of the extruded plate will be too small, resulting in a smaller mechanical lock, which will have a greater impact on the joint strength.

[0027] Furthermore, the taper of the tapered hole is 5° to 20°. If it is too small, the contact area with the pipe during friction rotation cannot be guaranteed, causing the plasticity of the pipe to increase due to friction heat, which affects the internal buckle of the joint. If it is too large, the rigidity of the upper mold cannot be guaranteed, which increases the instability during rotation.

[0028] Furthermore, the preset temperature T0 is 0.4 to 0.7 times the melting point of the sheet material. When the preset temperature T0 is too high, the material softens significantly, causing the upper die to squeeze the sheet, causing the material to flow out of the gap between the upper die and the tube, resulting in a poor joint. When the preset temperature T0 is too low, the material softens less, and the rotation time is too short. Heat is not yet transferred to the contact area between the sheet and the tube, resulting in less softening of the tube and a less significant reduction in the upper die extrusion force.

[0029] The device disclosed in the present invention for realizing the above-mentioned method of connecting pipes and plates by utilizing plastic deformation of pipes has a simple structure, reasonable design, convenient installation, good compatibility with conventional equipment, and is suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is the initial state diagram of the present invention;

[0031] Figure 2 This is a schematic diagram of the upper mold applying pre-tightening force to the plate in the present invention;

[0032] Figure 3 Schematic diagram of the upper mold rotation movement and plate temperature distribution of the present invention;

[0033] Figure 4 This is a schematic diagram of the upper die moving downward to extrude a plate according to the present invention;

[0034] Figure 5 This is a diagram showing the upper die of the present invention stopping extrusion and moving upward;

[0035] Figure 6 This is a schematic diagram of the upper mold of the present invention moving upward to the initial position;

[0036] Figure 7 It is a schematic diagram of the plate and pipe connection structure after the connection is completed according to the present invention.

[0037] Among them, 1 is the upper die, 2 is the plate, 3 is the lower die, 4 is the pipe, 5 is the annular protrusion, and 6 is the tapered hole. DETAILED DESCRIPTION

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, which are intended to explain the present invention rather than to limit it.

[0039] like Figure 1 , in order to realize a specific set of devices of the present invention, this example is used to explain the friction-assisted plate-pipe connection method of the present invention in detail, which does not constitute a limitation of the present invention. The method of the present invention can be realized by using any existing device that can realize its step-by-step functions.

[0040] The device comprises an upper die 1 and a lower die 3; a through hole is provided in the middle of the lower die 3; a tapered hole 6 is provided in the middle of the upper end of the upper die 1, and an annular protrusion 5 is provided at the lower end.

[0041] like Figures 2 to 6 When the above device is used, it includes the following steps:

[0042] S1: Put the pipe 4 into the center hole of the lower mold 3, and keep the lower mold 3 fixed;

[0043] S2: Based on the outer diameter of the tube 4, a hole is machined in the center of the plate 2, and then the plate 2 is sleeved onto the outside of the tube 4, and the plate 2 is brought into contact with the upper surface of the lower die 3;

[0044] S3: The upper die 1 having a tapered hole 6 in the middle of the upper end and an annular protrusion 5 at the lower end is placed on the outside of the tube 4. The annular protrusion 5 of the upper die 1 is downwardly moved at a speed V1 to the upper surface of the plate 2 and then stopped. A preload force F is applied to the plate 2.

[0045] S4: The upper die 1 rotates at a constant angular velocity w. The sheet 2 generates heat energy due to the friction of the upper die 1 and is transferred inside the sheet 2 and the tube 4. When the preset temperature T0 is reached, the upper die 1 stops rotating.

[0046] S5: The upper die 1 moves downward at a speed V2 to squeeze the sheet 2. The sheet 2 undergoes plastic flow in the radial direction. The flowing sheet 2 material squeezes the tube 4, causing the tube 4 to neck inward and gradually form a mechanical lock. The upper die 1 stops when it descends to the preset position.

[0047] S6: The upper die 1 moves upward to the initial position at a speed of V3 and takes out the sheet-tube connector. Figure 7 .

[0048] In a preferred embodiment of the present invention, the plate 2 and the tube 4 are made of titanium alloy, aluminum alloy or magnesium alloy.

[0049] In a preferred embodiment of the present invention, the thickness t1 of the plate 2 is 3 to 10 times the wall thickness t2 of the tube 4 , and the outer diameter d1 of the tube 4 is 0.9 to 0.98 times the inner diameter d of the annular protrusion 5 .

[0050] In a preferred embodiment of the present invention, the height h of the annular protrusion 5 is 1 to 2 times the thickness t1 of the plate 2 , and the width l of the annular protrusion 5 is 0.2 to 1 times the height h of the annular protrusion 5 .

[0051] In a preferred embodiment of the present invention, the lower surface of the annular protrusion 5 is a plane.

[0052] In a preferred embodiment of the present invention, the taper angle θ of the tapered hole 6 is 5° to 20°.

[0053] In a preferred embodiment of the present invention, in S3, the preload force F is 2-10 kN.

[0054] In a preferred embodiment of the present invention, in S4, the angular velocity w is 500-1600 rpm, and the preset temperature T0 is (0.4-0.7)T m , T m is the melting point of the material of plate 2.

[0055] In a preferred embodiment of the present invention, V1 = 1-5 mm / s, V2 = 0.2-1 mm / s, and V3 = 1-3 mm / s.

[0056] It should be noted that the present invention is not limited to the above-mentioned embodiments, and any obvious improvements or changes to the above-mentioned embodiments made by those skilled in the art will not exceed the concept of the present invention and the scope of protection of the appended claims.

Claims

1. A friction-assisted plate-to-pipe connection method, characterized in that: The following steps are involved: S1: The pipe (4) is placed in the center hole of the lower die (3), and the lower die (3) is fixed; S2: Based on the outer diameter of the tube (4), the center of the plate (2) is hole-machined, and then the plate (2) is placed outside the tube (4), and the plate (2) is brought into contact with the upper surface of the lower die (3); the thickness of the plate (2) is 3 to 10 times the wall thickness of the tube (4); the plate (2) and the tube (4) are titanium alloy, aluminum alloy or magnesium alloy; S3: An upper die (1) having a tapered hole (6) in the middle of the upper end and an annular protrusion (5) at the lower end is placed on the outside of the pipe (4), the tapered hole (6) having a taper of 5° to 20°, the annular protrusion (5) of the upper die (1) pointing downward, and moving downward at a speed V1 to the upper surface of the plate (2) and then stopping, and applying a pre-tightening force F to the plate (2), the pre-tightening force F being 2 to 10 kN; S4: The upper die (1) rotates at a constant angular velocity w, which is 500~1600rpm. The plate (2) generates heat energy under the friction of the upper die (1) and is transferred in the plate (2) and the tube (4). When the preset temperature T0 is reached, the upper die (1) stops rotating. The preset temperature T0=(0.4~0.7)T m , T m is the melting point of the material of the plate (2); S5: The upper die (1) moves downward at a speed V2 to extrude the plate (2), and the plate (2) undergoes plastic flow in the radial direction. The flowing plate (2) material extrude the tube (4), and the tube (4) undergoes inward necking and gradually forms a mechanical lock. When the upper die (1) descends to a preset position, it stops. S6: The upper die (1) moves upward to the initial position at a speed of V3 and removes the sheet-to-pipe connector.

2. The friction-assisted plate-to-pipe joining method according to claim 1, characterized in that: The outer diameter of the pipe (4) is 0.9 to 0.98 times the inner diameter of the annular protrusion (5).

3. The friction-assisted plate-to-pipe connection method according to claim 1, characterized in that: The height of the annular protrusion (5) is 1 to 2 times the thickness of the plate (2), and the width of the annular protrusion (5) is 0.2 to 1 times the height of the annular protrusion (5).

4. The friction-assisted plate-to-pipe joining method according to claim 1, wherein: The lower surface of the annular protrusion (5) is a plane.

5. The friction-assisted plate-to-pipe joining method according to claim 1, characterized in that: V1=1~5mm / s, V2=0.2~1mm / s, V3=1~3mm / s.

6. A device for implementing the friction-assisted plate-to-pipe connection method according to any one of claims 1 to 5, characterized in that: The upper mold (1) comprises an upper mold (1) and a lower mold (3); a through hole is provided in the middle of the lower mold (3); a tapered hole (6) is provided in the middle of the upper end of the upper mold (1), and an annular protrusion (5) is provided at the lower end.

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