A method and device for viscous friction jointing of a low plasticity metal tube blank

Abstract

The application discloses a kind of low plasticity metal pipe blank viscous medium circumferential progressive expansion joining method and device, belong to pipe plate expansion joining technical field.Utilize plunger movement extrusion viscous medium, and through the rotation of mandrel, the pressure that plunger provides viscous medium is circumferentially progressively applied to pipe blank, let pipe blank locally occur deformation, embed the recess that is opened inside pipe plate hole, after mandrel rotates multiple times, pipe blank gradually with pipe plate recess is fitted, form firm mechanical lock, complete expansion joining process.The application solves the current low plasticity metal pipe blank expansion joining deformation difficult, expansion joining after pull-off force small and so on, can effectively improve the connection quality of low plasticity metal pipe blank-pipe plate.Using viscous medium circumferential progressive expansion joining method, wall thickness distribution is uniform during plastic deformation of pipe blank, stress state is reasonable, increase the service life of connected joint.

Description

Technical Field

[0001] This invention belongs to the field of tube sheet expansion technology, specifically relating to a method and apparatus for circumferential progressive expansion of a low-plasticity metal tube blank with a viscous medium. Background Technology

[0002] Tube sheet-tube connections are a crucial component of heat exchangers, and their strength and quality are key indicators of heat exchanger quality. However, low-plasticity metal tube blanks, such as aluminum alloy tubes and titanium alloy tubes, are prone to severe localized thinning or even cracking during the expansion process, affecting their manufacturing.

[0003] Currently, the expansion joint process between low-plasticity metal tube blanks and tube sheets involves using a tube expander to squeeze the end of the tube blank in the tube sheet hole, causing the tube blank to plastically deform and generate a certain extrusion force with the tube sheet. This process has advantages such as ease of use, low energy consumption, and easy control of expansion pressure. However, it also has problems such as easy damage to the tube wall and poor tube wall surface quality.

[0004] Due to their poor plasticity and small deformation, low-plasticity metal tube blanks are prone to wall rupture during expansion jointing, which affects the connection quality of low-plasticity metal tube blanks-tube sheets. Therefore, it is urgent to develop new methods for connecting low-plasticity metal tube blanks-tube sheets. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method and apparatus for circumferential progressive expansion jointing of low-plasticity metal tube blanks with viscous media. The apparatus is simple, easy to operate, and effectively improves the forming performance of low-plasticity tube blanks, resulting in high connection strength, uniform tube blank wall thickness distribution, and resistance to detachment.

[0006] This invention is achieved through the following technical solution:

[0007] This invention discloses a method for circumferential progressive expansion jointing of a low-plasticity metal tube blank with a viscous medium, comprising the following steps:

[0008] S1: Based on the structure and dimensions of the tube blank and tube sheet to be connected, process a mandrel with several medium injection holes on its sidewall; process several annular grooves on the inner wall of the tube sheet's hole; insert the mandrel into the tube blank, inject the viscous medium into the cavity inside the mandrel, and install the plunger at the open end of the mandrel; place the assembled mandrel and tube blank into the hole of the tube sheet, with the medium injection holes of the mandrel corresponding to the annular grooves on the inner wall of the tube sheet's hole;

[0009] S2: Apply force F1 to the plunger to make the plunger move and squeeze the viscous medium, squeezing the viscous medium into the medium injection hole on the mandrel, forming local pressure. The tube blank is squeezed by the local pressure and deformed. The local deformation of the tube blank is embedded in the annular groove on the tube sheet.

[0010] S3: Fix the axial position of the mandrel, apply a circumferential angular velocity ω1 to the mandrel, and at the same time, the plunger continues to apply force F1. The mandrel rotates around the axis several times, and the tube blank produces circumferential deformation, thus initially connecting the tube sheet.

[0011] S4: Keep the mandrel and tube blank in the same axial position in the tube sheet hole, apply force F2 to the plunger, so that the plunger moves to the right to squeeze the viscous medium, and the tube blank is subjected to local pressure to produce secondary deformation;

[0012] S5: Fix the axial position of the mandrel, apply a circumferential angular velocity ω2 to the mandrel, and keep the force F2 applied by the plunger constant. The mandrel rotates around the axis several times, and the tube blank produces a secondary circumferential deformation, forming a stable lock with the tube sheet.

[0013] Preferably, in S1, the outer wall of the tube blank is clearance-fitted with the inner wall of the hole in the tube sheet, and the inner wall of the tube blank is clearance-fitted with the outer surface of the mandrel.

[0014] Preferably, the viscous medium is a high molecular weight polymer with a molecular weight of 400,000 to 700,000 g / mol.

[0015] Preferably, F1 and F2 are determined by the yield strength of the tube blank, and F2 > F1.

[0016] Preferably, ω1 is 0.1 to 0.3 rad / s and ω2 is 0.05 to 0.1 rad / s.

[0017] Preferably, the opening of the annular groove on the tube sheet is provided with a transition fillet.

[0018] The apparatus disclosed in this invention for implementing the above-mentioned method of circumferential progressive expansion of a low-plasticity metal tube blank with a viscous medium includes a mandrel and a plunger; a plurality of medium injection holes are provided on the side wall of the mandrel, the positions of which correspond to the positions of the annular grooves on the inner wall of the tube sheet holes; one end of the mandrel is closed and the other end is open; the plunger is nested in the open end of the mandrel, and the cavity of the mandrel is filled with a viscous medium.

[0019] Preferably, a sealing device is provided between the plunger and the mandrel.

[0020] Preferably, the outer wall of the mandrel is provided with a plurality of annular sealing rings, which are respectively arranged on both sides of the medium injection hole along the mandrel axis.

[0021] Preferably, the medium injection hole is a two-stage stepped hole, with the diameter near the tube blank hole being larger than the diameter near the mandrel inner cavity hole, and the diameter near the tube blank hole being 1.1 to 1.3 times the width of the annular groove on the inner wall of the tube sheet hole.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects:

[0023] This invention discloses a circumferential progressive expansion method for low-plasticity metal tube blanks using a viscous medium. Unlike traditional expansion processes that involve a single large deformation, this method proposes a localized rotational progressive forming approach for the tube blank, dispersing deformation across multiple small, continuous deformation processes. Using a viscous medium as the pressure transmission carrier optimizes the stress state of the low-plasticity metal tube blank during the tube-to-sheet connection, promoting uniform deformation of the tube. The plunger's movement compresses the viscous medium, and the rotation of the mandrel applies the pressure supplied by the plunger to the viscous medium in a circumferential progressive manner to the tube blank, causing localized deformation and embedding the tube blank into grooves created within the tube-to-sheet holes. After multiple rotations of the mandrel, the tube blank gradually conforms to the tube-to-sheet grooves, forming a strong mechanical lock and completing the expansion process. The process parameters and the number of rotations can be flexibly adjusted according to the different materials of the tube blank to improve the forming performance of the low-plasticity tube blank. This invention solves the problems of difficult deformation and low pull-out force after expansion of low-plasticity metal tube blanks, effectively improving the connection quality of low-plasticity metal tube blanks to tube sheets. Using the viscous medium circumferential progressive expansion method, the viscous adhesion of the viscous medium can promote material flow, making the wall thickness distribution of the tube blank uniform and the stress state reasonable during plastic deformation, thus increasing the service life of the connection joint.

[0024] Furthermore, the viscous medium uses high molecular weight polymers in the range of 400,000 to 700,000 g / mol, such as silicone rubber. Viscous media within this molecular weight range exhibit excellent mechanical transfer properties and good flowability. If the molecular weight is too small, the mechanical properties are poor; if the molecular weight is too large, the flowability is poor.

[0025] Furthermore, F1 and F2 are related to the yield strength of the tube blank. As the yield strength of the tube blank increases, the force value increases. Moreover, F2 > F1, which ensures that the tube blank can be completely attached to the mold during the secondary rotation of the mandrel.

[0026] Furthermore, ω1 is 0.1 to 0.3 rad / s. If the mandrel angular velocity is too small, the forming efficiency will be low; if the angular velocity is too large, the deformation of the local working area of ​​the tube blank will be insufficient. ω2 is 0.05 to 0.1 rad / s. If the angular velocity is too small, the forming efficiency will be low; if the angular velocity is too large, the deformation of the local working area of ​​the tube blank will be insufficient.

[0027] Furthermore, the opening of the annular groove on the tube sheet is provided with a transition rounded corner, which can promote the flow of the plate and effectively improve the connection force between the tube sheet and the tube.

[0028] The apparatus disclosed in this invention for realizing the above-mentioned method of connecting pipes and plates by utilizing the plastic deformation of pipes has a simple structure, reasonable design, convenient installation, good compatibility with conventional equipment, and is suitable for mass production.

[0029] Furthermore, a sealing device is provided between the plunger and the mandrel to effectively prevent leakage of viscous media.

[0030] Furthermore, the outer wall of the mandrel is provided with several annular sealing rings, which are respectively arranged on both sides of the medium injection hole along the mandrel axis. On the one hand, this can prevent the leakage of viscous medium, and on the other hand, it can make each connection locking area independent, avoiding mutual interference and affecting the connection effect.

[0031] Furthermore, the medium injection hole is designed as a two-stage stepped hole structure, with the diameter near the tube blank hole being larger than the diameter near the mandrel inner cavity hole. This allows sufficient volume of viscous medium to accumulate in the deformation zone and participate in the tube deformation. The diameter near the tube blank hole is 1.1 to 1.3 times the width of the annular groove on the inner wall of the tube sheet hole, ensuring that the viscous medium fully contacts the tube material in the deformation zone, eliminating any suspended areas and promoting uniform material deformation. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0033] Figure 2 for Figure 1 A partial structural sectional view AA;

[0034] Figure 3 This is a schematic diagram of the progressive expansion joint of the tube blank according to the present invention;

[0035] Figure 4 A schematic diagram of the mechanical locking structure formed to complete the connection between the tube sheet and the tube blank.

[0036] In this diagram, 1 is the tube sheet, 2 is the tube blank, 3 is the mandrel, 4 is the viscous medium, 5 is the annular sealing ring, and 6 is the plunger. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. These descriptions are intended to explain the invention and not to limit it.

[0038] like Figure 1 and Figure 2 This document describes a specific apparatus for implementing the circumferential progressive expansion joint method for low-plasticity metal tube blanks with viscous media according to the present invention. This apparatus serves as an example to explain the circumferential progressive expansion joint method for low-plasticity metal tube blanks with viscous media according to the present invention. This explanation does not constitute a limitation on the present invention. The method of the present invention can be implemented using any existing apparatus capable of performing its step-by-step functions.

[0039] The device includes a mandrel 3 and a plunger 6; the mandrel 3 has several medium injection holes on its side wall, and the positions of the medium injection holes correspond to the positions of the annular grooves on the inner wall of the tube sheet 1; one end of the mandrel 3 is closed and the other end is open; the plunger 6 is nested in the open end of the mandrel 3, and the cavity of the mandrel 3 is filled with viscous medium 4.

[0040] The mandrel 3 can rotate under the action of an applied circumferential angular velocity, and its inner and outer parts are connected through a circular injection hole on the shaft. This rotation plays a role in changing the local action position and power direction during the tube blank expansion. The number of medium injection holes opened on the mandrel 3 is determined by the magnitude of the required low-plasticity metal tube blank-tube sheet connection force and the annular groove on the tube sheet 1. When the required connection force is large, the number of medium injection holes can be increased.

[0041] In a preferred embodiment of the present invention, a sealing device is provided between the plunger 6 and the mandrel 3.

[0042] In a preferred embodiment of the present invention, a plurality of annular sealing rings 5 ​​are provided on the outer wall of the mandrel 3, and the plurality of annular sealing rings 5 ​​are respectively arranged on both sides of the medium injection hole along the axis of the mandrel 3.

[0043] In a preferred embodiment of the present invention, the inlet of the medium injection hole is connected to the inner cavity of the mandrel 3. The medium injection hole is a two-stage stepped hole, the diameter of the hole near the tube blank 2 is larger than the diameter of the hole near the inner cavity of the mandrel 3, and the diameter of the hole near the tube blank 2 is 1.1 to 1.3 times the width of the annular groove on the inner wall of the tube plate 1 hole.

[0044] The method for circumferential progressive expansion of low-plasticity metal tube blanks with viscous media according to the present invention includes:

[0045] like Figure 3 S1: Based on the structure and dimensions of the tube blank 2 and tube sheet 1 to be connected, process a mandrel 3 with several medium injection holes on its sidewall; process several annular grooves on the inner wall of the hole in the tube sheet 1; insert the mandrel 3 into the tube blank 2, inject the viscous medium 4 into the cavity inside the mandrel 3, and install the plunger 6 at the open end of the mandrel 3; place the assembled mandrel 3 and tube blank 2 into the hole in the tube sheet 1, with the medium injection holes of the mandrel 3 corresponding to the annular grooves on the inner wall of the hole in the tube sheet 1.

[0046] S2: Apply force F1 to the plunger 6 to make the plunger 6 move and squeeze the viscous medium 4, squeezing the viscous medium 4 into the medium injection hole on the mandrel 3, forming local pressure. The tube blank 2 is squeezed by the local pressure and deformed. The local deformation of the tube blank 2 is embedded in the annular groove on the tube sheet 1.

[0047] S3: Fix the axial position of the mandrel 3, apply a circumferential angular velocity ω1 to the mandrel 3, and at the same time, the plunger 6 continues to apply force F1. The mandrel 3 rotates around the axis several times, and the tube blank 2 produces circumferential deformation, initially connecting the tube sheet 1.

[0048] S4: Keep the mandrel 3 and tube blank 2 in the axial position of the hole in tube plate 1 unchanged, apply force F2 to plunger 6, so that plunger 6 moves to the right to squeeze viscous medium 4, and tube blank 2 is subjected to local pressure to produce secondary deformation.

[0049] S5: Fix the axial position of the mandrel 3, apply a circumferential angular velocity ω2 to the mandrel 3, and keep the force F2 applied by the plunger 6 constant. The mandrel 3 rotates around the axis several times, and the tube blank 2 undergoes secondary circumferential deformation, forming a stable lock with the tube sheet 1, such as... Figure 4 .

[0050] In a preferred embodiment of the present invention, in S1, the outer wall of the tube blank 2 is clearance-fitted with the inner wall of the hole in the tube sheet 1, and the inner wall of the tube blank 2 is clearance-fitted with the outer surface of the mandrel 3.

[0051] In a preferred embodiment of the present invention, the viscous medium 4 is a high molecular weight polymer with a molecular weight of 400,000 to 700,000 g / mol, such as silicone rubber.

[0052] In a preferred embodiment of the present invention, F1 and F2 are determined by the yield strength of the tube blank 2, and F2 > F1.

[0053] In a preferred embodiment of the present invention, ω1 is 0.1 to 0.3 rad / s and ω2 is 0.05 to 0.1 rad / s.

[0054] In a preferred embodiment of the present invention, the opening of the annular groove on the tube sheet 1 is provided with a transition fillet.

[0055] Example 1

[0056] The tube blank 2 is made of 6061T6 aluminum alloy, the tube sheet 1 is made of 304 stainless steel, the value of F1 is 200KN, the value of F2 is 300KN, and under the conditions of ω1 being 0.1rad / s and ω2 being 0.05rad / s, the mandrel 3 only needs to rotate two revolutions to allow the 6061T6 tube blank to undergo plastic deformation and completely fit into the 304 stainless steel tube sheet, thus completing the expansion joint process.

[0057] Example 2

[0058] The tube blank 2 is made of TC4 titanium alloy, the tube sheet 1 is made of 2205 duplex stainless steel, the value of F1 is 400KN, the value of F2 is 600KN, and under the conditions of ω1 being 0.1rad / s, ω2 being 0.05rad / s, and ω3 being 0.05rad / s, the mandrel 3 needs to rotate three times to make the TC4 titanium alloy tube blank completely fit into the groove inside the hole of the 2205 duplex stainless steel tube sheet, thus completing the expansion joint process.

[0059] It should be noted that the present invention is not limited to the above embodiments, and any obvious improvements or modifications made by those skilled in the art to the above embodiments will not exceed the scope of the concept of the present invention and the protection scope of the appended claims.

Claims

1. A method for circumferential progressive expansion joint of a low-plasticity metal tube blank with a viscous medium, characterized in that, The apparatus employing a low-plasticity metal tube blank viscous medium circumferential progressive expansion method includes a mandrel (3) and a plunger (6); the mandrel (3) has several medium injection holes on its side wall, the positions of which correspond to the positions of the annular grooves on the inner wall of the tube sheet (1); one end of the mandrel (3) is closed and the other end is open; the plunger (6) is nested in the open end of the mandrel (3), and the cavity of the mandrel (3) is filled with viscous medium (4); a sealing device is provided between the plunger (6) and the mandrel (3); several annular sealing rings (5) are provided on the outer wall of the mandrel (3), and the several annular sealing rings (5) are respectively arranged on both sides of the medium injection hole along the axis of the mandrel (3); the medium injection hole is a two-stage stepped hole, the diameter of the hole near the tube blank (2) is larger than the diameter of the hole near the inner cavity of the mandrel (3), and the diameter of the hole near the tube blank (2) is 1.1 to 1.3 times the width of the annular groove on the inner wall of the tube sheet (1); Includes the following steps: S1: Based on the structure and dimensions of the tube blank (2) and tube sheet (1) to be connected, process a mandrel (3) with several medium injection holes on its sidewall; process several annular grooves on the inner wall of the hole of the tube sheet (1); insert the mandrel (3) into the tube blank (2), inject the viscous medium (4) into the cavity inside the mandrel (3), and install the plunger (6) at the open end of the mandrel (3); place the assembled mandrel (3) and tube blank (2) into the hole of the tube sheet (1), with the medium injection hole of the mandrel (3) corresponding to the annular groove on the inner wall of the hole of the tube sheet (1); S2: Apply force F1 to the plunger (6) to make the plunger (6) move and squeeze the viscous medium (4), squeeze the viscous medium (4) into the medium injection hole on the mandrel (3) to form local pressure. The tube blank (2) is squeezed by the local pressure and deformed. The tube blank (2) is embedded in the annular groove on the tube sheet (1) by the local deformation. S3: Fix the axial position of the mandrel (3), apply a circumferential angular velocity ω1 to the mandrel (3), and at the same time, the plunger (6) continues to apply force F1. The mandrel (3) rotates around the axis several times, and the tube blank (2) produces circumferential deformation, and the tube sheet (1) is initially connected. S4: Keep the mandrel (3) and tube blank (2) in the axial position of the hole in the tube sheet (1) unchanged, apply force F2 to the plunger (6) so that the plunger (6) moves to the right to squeeze the viscous medium (4), and the tube blank (2) is subjected to local pressure and produces secondary deformation; S5: Fix the axial position of the mandrel (3), apply a circumferential angular velocity ω2 to the mandrel (3), apply a constant force F2 to the plunger (6), rotate the mandrel (3) around the axis for several revolutions, and the tube blank (2) produces a secondary circumferential deformation, forming a stable lock with the tube sheet (1).

2. The method for circumferential progressive expansion joint of low-plasticity metal tube blanks with viscous media according to claim 1, characterized in that, In S1, the outer wall of the tube blank (2) is clearance-fitted with the inner wall of the hole of the tube sheet (1), and the inner wall of the tube blank (2) is clearance-fitted with the outer surface of the mandrel (3).

3. The method for circumferential progressive expansion joint of low-plasticity metal tube blanks with viscous media according to claim 1, characterized in that, The viscous medium (4) is a high molecular weight polymer with a molecular weight of 400,000 to 700,000 g / mol.

4. The method for circumferential progressive expansion joint of low-plasticity metal tube blanks with viscous media according to claim 1, characterized in that, F1 and F2 are determined by the yield strength of the tube blank (2), and F2 > F1.

5. The method for circumferential progressive expansion joint of low-plasticity metal tube blanks with viscous media according to claim 1, characterized in that, ω1 is 0.1 to 0.3 rad / s, and ω2 is 0.05 to 0.1 rad / s.

6. The method for circumferential progressive expansion joint of low-plasticity metal tube blanks with viscous media according to claim 1, characterized in that, The opening of the annular groove on the tube sheet (1) is provided with a transition fillet.

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