Deformation control clamp for automatic welding of aircraft guide pipe and welding method

Abstract

The embodiment of the invention discloses a deformation control fixture and a welding method for automatic welding of aircraft conduits, and in the deformation control fixture, a core shaft 17 with a central shaft hole and a screw rod 4 arranged in the core shaft 17 are adopted; a connecting pin 15 connected with the end, located in the mandrel 17, of the screw 4 extends out of a kidney-shaped hole which extends out of the mandrel 17 in the radial direction and then is fixedly connected with a first taper sleeve 12 arranged outside the mandrel 17 in a sleeving mode, and a first expansion block 11 is installed outside the first taper sleeve 12 in a matched mode. The threaded sleeve 3 matched with the threaded rod 4 rotates to drive the threaded rod 4 to move in the axial direction of the mandrel 17, so that the first taper sleeve 12 is driven to move in the axial direction, and the first expansion block 11 is shrunk or expanded. On the basis of the structure, a connection mode of the pulling plug 5 and the second taper sleeve 10 which are in threaded connection outside the mandrel 17 is adopted, and the pulling plug 5 is rotated to move axially so as to drive the second taper sleeve 10 to move axially, so that the second expansion block 9 is shrunk or expanded. According to the deformation control clamp provided by the embodiment of the invention, the inner wall of the guide pipe is supported during welding through the expansion block state of the expansion block, and the excess weld metal in the welding process is controlled in cooperation with filling of the protective gas into the guide pipe, so that the welding quality of the guide pipe is improved, and the fatigue life of the guide pipe is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of but not limited to the technical field of catheter welding, and in particular to a deformation control fixture and a welding method for automatic welding of aircraft catheters. Background Art

[0002] Aircraft ducts play a key role in aircraft structure, responsible for transporting hydraulic oil, fuel, air, etc., and are essential for the normal operation of the aircraft. Aircraft ducts are not only numerous, but also require precise layout and connection to ensure the effective operation of the ducts in the aircraft system. In aircraft manufacturing, welded ducts account for a certain proportion, especially in aircraft duct parts with special product structures.

[0003] For welded conduits, weld reinforcement refers to the height of the metal protruding from the line connecting the two weld toes on the weld surface. Weld reinforcement refers to the deposited metal that bulges out from the surface of the parent material or the part above the connecting line at the end of the fillet weld. The existence of weld reinforcement destroys the continuity of the geometric shape of the weld surface, and will produce additional bending moment due to the sudden change in shape, resulting in higher local stress. These crack sources caused by weld defects will accelerate the expansion under the action of local stress until they break.

[0004] How to control the weld excess height of the pipe welding seam has become an important problem affecting the weld quality in the welded pipe. For the circumferential weld and local ear welding of small-diameter pipes, many mechanisms supporting the inner wall of the pipe cannot be used due to the limited space structure. In addition, the tooling used for welding also requires a ventilation protection groove to be opened at the weld of the aircraft pipe, which leads to the problem that the weld excess height of the aircraft welded pipe is difficult to control. Summary of the invention

[0005] Purpose of the present invention: In order to solve the above technical problems, the embodiments of the present invention provide a deformation control fixture and a welding method for automatic welding of aircraft ducts, so as to solve the problem that the welding of the circumferential weld and local ear piece of the small diameter duct cannot be used due to the limitation of the spatial structure, thus making the weld height of the aircraft welded duct difficult to control.

[0006] Technical solution of the present invention: In the first aspect, the embodiment of the present invention provides a deformation control fixture for automatic welding of aircraft ducts, comprising: a duct plug 1, a nut 2, a mandrel 17, a screw 4, a threaded sleeve 3, a connecting pin 15, a positioning sleeve 16, a mandrel 17, and at least one set of cone sleeves and expansion block components;

[0007] The positioning sleeve 16 has a stepped hole at one end and a stepped shaft at the other end. The mandrel 17 is coaxially fixedly mounted in the stepped hole of the positioning sleeve 16 via a positioning connection flange at its end.

[0008] The mandrel 17 is provided with a central axis hole along its axis, a catheter plug 1 is sleeved on the outer side of one end of the mandrel 17, and the outer end of the catheter plug 1 is pressed by a nut 2 screwed on the mandrel 17 to axially position the catheter plug 1; the screw rod 4 is inserted into the central axis hole of the mandrel 17 from one end, and one end of the screw rod 4 located in the mandrel 17 is threadedly connected with a connecting pin 15 radially perpendicular to the axis of the mandrel 17, and the threaded rod of the screw rod 4 located outside the mandrel 17 is threadedly connected with a threaded sleeve 3, and the end of the threaded rod is set as a square prism, and the square prism is clamped and the threaded sleeve 3 is screwed to drive the screw rod 4 to move axially in the mandrel 17;

[0009] The first group of cone sleeve and expansion block assembly includes: a first cone sleeve 12 and a first expansion block 11 which are arranged as a circumferential split structure; the first cone sleeve 12 is sleeved on the outside of the shaft body of the core shaft 17 and has an outer conical surface, and the first expansion block 11 is sleeved on the outside of the cone sleeve and has an inner conical surface matching the outer conical surface of the first cone sleeve 12; the first expansion block 11 is fixedly connected to the limiting structure in the middle part of the shaft body of the core shaft 17; the connecting pin 15 at one end of the screw rod 4 passes through the first waist-shaped hole at one end of the shaft body of the core shaft 17, and is connected to the first cone sleeve 12 by a screw, so as to drive the first cone sleeve 12 to move axially through the connecting pin 15 when the screw rod 4 moves axially, thereby realizing the contraction or expansion of the first expansion block 11.

[0010] Optionally, the deformation control fixture for automatic welding of aircraft ducts as described above further includes a second set of cone sleeve and expansion block assembly, including: a second expansion block 9 and a second cone sleeve 10; the second cone sleeve 10 is sleeved on the outside of the core shaft 17 and has an outer conical surface, and the second expansion block 9 is sleeved on the outside of the second cone sleeve 10 and has an inner conical surface matching the outer conical surface of the second cone sleeve 10; the second expansion block 9 is fixedly connected to the limiting structure in the middle of the shaft body of the core shaft 17;

[0011] The deformation control fixture also includes: a pull bolt 5 and a connecting component;

[0012] The pull bolt 5 is configured as a sleeve structure, which is integrally sleeved and connected to the outside of the shaft body of the core shaft 17 near the catheter plug 1. One end of the pull bolt 5 is provided with an internal threaded hole, and the other end is provided with a stepped through hole, and the end of the stepped through hole has an annular convex shoulder, and the outer wall of the middle part of the pull bolt 5 is configured as a hexagonal prism; the pull bolt 5 is threadedly connected to the outside of the shaft body of the core shaft 17 near the plug 1 through its internal threaded hole, and the end face of the annular convex shoulder of the pull bolt 5 is fitted on the outer end face of the second cone sleeve 10, and the annular convex shoulder of the pull bolt 5 is fixedly connected to the second cone sleeve 10 through a connecting component;

[0013] By screwing the hexagonal column structure in the middle of the pull bolt 5 , the pull bolt 5 is moved axially along the core shaft 17 , and the second cone sleeve 10 is driven to move axially, thereby realizing the contraction or expansion of the second expansion block 9 .

[0014] Optionally, in the deformation control fixture for automatic welding of aircraft ducts as described above,

[0015] A swelling block connecting flange is arranged in the middle of the core shaft 17, and the large circular end faces of the first swelling block 11 and the second swelling block 9 are arranged at two ends of the swelling block connecting flange relatively, and are fixedly connected to the swelling block connecting flange by screws respectively. The first swelling block 11 is located between the swelling block connecting flange and the positioning sleeve 16, and the second swelling block 9 is located between the swelling block connecting flange and the catheter plug 1; and the outer circular conical surfaces of the first cone sleeve 12 and the second cone sleeve 10 are in opposite directions.

[0016] Optionally, in the deformation control fixture for automatic welding of aircraft ducts as described above, the end surface of one end of the second cone sleeve 10 connected to the pull bolt 5 is provided with a columnar boss; the connection assembly comprises: a gland 8, a hexagon socket head screw 6 and a flat washer 7;

[0017] The pressure cap 8 is configured as a sleeve structure with a stepped through hole inside. The pressure cap 8 is sleeved on the outside of the pull bolt 5 with its small diameter hole end, and the inner ring of the cover plate at its small diameter hole end rests on the outer end face of the annular boss of the pull bolt 5 to form an axial limiting structure; the large diameter hole end of the pressure cap 8 is integrally sleeved on the annular boss of the pull bolt 5 and the outer side of the columnar boss of the second tapered sleeve 10, and the pressure cap 8 is fixedly connected to the large circular end face of the second tapered sleeve 10 by a flat washer 7 and a hexagon socket head screw 6.

[0018] Optionally, in the deformation control fixture for automatic welding of aircraft ducts as described above, in the first set of cone sleeve and expansion block assembly,

[0019] The first cone sleeve 12 is configured as an outer cone structure with an outer cone surface and an inner circular hole, the first expansion block 11 is configured as an inner cone structure with an outer cylindrical surface and an inner cone surface, and the first expansion block 11 includes a plurality of segment expansion blocks arranged in sections along the circumferential direction;

[0020] The first cone sleeve 12 is sleeved on the core shaft 17 through its inner hole and is in clearance with the core shaft 17. Its outer cone surface is in accordance with the inner cone surface of the first expansion block 11. The inner hole of the first cone sleeve 12 is a step hole. A threaded hole is provided on the step end surface. The connecting pin 15 is connected to the step end surface of the first cone sleeve 12 by a screw, so that the screw rod 4 is connected to the first cone sleeve 12 through the connecting pin 15 and the screw. When the rotating screw rod 4 moves axially under the rotation of the threaded sleeve 3, the first cone sleeve 12 is driven by the screw rod 4 to move axially along the core shaft 17, so that the first expansion block 11 expands or contracts.

[0021] The large circular end face of the first expansion block 11 is connected to the end face of the expansion block connecting flange in the middle of the core shaft 17 facing the positioning sleeve 16, which is used to limit the axial position of the first expansion block 11; and a plurality of guide grooves are radially opened on the large circular end face of the first expansion block 11, which cooperate with the cylindrical pins on the end face of the expansion block connecting flange for guidance, and are used to limit the radial position of the first expansion block 11 when it expands or contracts.

[0022] Optionally, in the deformation control fixture for automatic welding of aircraft ducts as described above, in the second set of cone sleeve and expansion block assembly,

[0023] The second cone sleeve 10 is configured as an outer cone structure with an outer cone surface and an inner circular hole, the second expansion block 9 is configured as an inner cone structure with an outer cylindrical surface and an inner cone surface, and the second expansion block 9 includes a plurality of segment expansion blocks arranged in segments along the circumferential direction;

[0024] The second cone sleeve 10 is sleeved on the core shaft 17 through its inner hole and is in clearance with the core shaft 17. Its outer cone surface is in accordance with the inner cone surface of the second expansion block 9. A cylindrical pin perpendicular to the axis in the radial direction is installed on the inner side of the columnar boss of the second cone sleeve 10. The cylindrical pin is in accordance with the second waist hole on the shaft body of the core shaft 17 to guide the second cone sleeve 10 to move in the axial direction.

[0025] The large circular end face of the second expansion block 9 is connected to the end face of the expansion block connecting flange in the middle of the core shaft 17 facing the catheter plug 1, and is used to limit the axial position of the second expansion block 9; and a plurality of guide grooves are radially opened on the large circular end face of the second expansion block 9, which cooperate with the cylindrical pins on the end face of the expansion block connecting flange for guidance, and are used to limit the radial position of the second expansion block 9 when it expands or contracts.

[0026] Optionally, in the deformation control fixture for automatic welding of aircraft ducts as described above,

[0027] The outer cylindrical surfaces of the first expansion block 11 and the second expansion block 9 are provided with at least one annular groove along the circumferential direction, and a tightening mechanism is placed in the annular groove, so that during the process of shrinking the first expansion block 11 and the second expansion block 9, the tightening mechanism can tighten the multiple ring-segment expansion blocks arranged along the circumferential direction in the radial direction, so as to facilitate the removal of the deformation control fixture from the welded conduit;

[0028] Wherein, the tightening mechanism comprises: a tension spring 14, or a tension spring 14 and a tension spring rod 13;

[0029] In each annular groove of the first expansion block 11 and the second expansion block 9, a tension spring 14 is installed around the circumference, which is used to apply radial pressure to the multiple ring segment expansion blocks around the circumference; or,

[0030] Multiple tension spring rods 13 parallel to the axial direction are pressed into the outer cylindrical surfaces of the first expansion block 11 and the second expansion block 9 along the circumference of each annular groove, and a tension spring 14 is hung between adjacent tension spring rods 13 to apply radial pressure to the multiple ring segment expansion blocks around one circle.

[0031] Optionally, in the deformation control fixture for automatic welding of aircraft ducts as described above,

[0032] The outer cylindrical surfaces of the first expansion block 11 and the second expansion block 9 are provided with triangular grooves for introducing protective gas along the axial direction;

[0033] The positioning sleeve 16 is connected to the three-jaw chuck for welding through its stepped shaft structure. After the catheter is sleeved on the outside of the expansion block of the deformation control fixture, the axial positions of the two ends are respectively limited by the stepped holes of the positioning sleeve 16 and the stepped holes of the catheter plug 1;

[0034] There are a plurality of ventilation holes on the end surface of the conduit plug 1, which are used to introduce protective gas through the ventilation holes during robot welding.

[0035] In a second aspect, an automatic welding method for an aircraft duct is provided, wherein the deformation control fixture for automatic welding of an aircraft duct as described in any one of the above items is used to support the aircraft duct to cooperate with the welding operation; wherein the deformation control fixture includes two sets of cone sleeve and expansion block assemblies, respectively including: a first cone sleeve 12 and a first expansion block 11 used in conjunction with each other, and a second cone sleeve 10 and a second expansion block 9 used in conjunction with each other; the welding method includes:

[0036] Step 1, fix the square prism at the end of the screw rod 4, and drive the screw rod 4 to move in the mandrel 17 toward one end close to the positioning sleeve 16 by screwing the threaded sleeve 3 in a clockwise or counterclockwise direction, thereby driving the connecting pin 15 to pull the first cone sleeve 12 to move synchronously, so that the first expansion block 11 contracts; use a wrench to clamp the hexagonal prism in the middle of the pull bolt 5, and rotate it in a clockwise or counterclockwise direction, so that the pull bolt 5 moves along the mandrel 17 away from the positioning sleeve 16, driving the second cone sleeve 10 to move synchronously, so that the second expansion block 9 contracts; put the conduit 18 to be welded on the outside of the first expansion block 11 and the second expansion block 9 in a contracted state, and one end of the conduit 18 is positioned by the positioning sleeve 16;

[0037] Step 2, the screw rod 4 and the pull bolt 5 are rotated counterclockwise or clockwise respectively, so that the first expansion block 11 and the second expansion block 9 are expanded to fit on the inner wall of the conduit, and the weld to be welded is supported by the first expansion block 11 and the second expansion block 9;

[0038] Step 3, after the catheter is positioned, the catheter plug 1 is mounted on the other end of the catheter 18 to axially limit the catheter 18 through the combination of the catheter plug 1 and the positioning sleeve 16, and the catheter plug 1 is locked with the nut 2.

[0039] Step 4, by programming the operating robot, the arc welding robot performs automatic welding on the weld of the conduit;

[0040] Step 5, after completing the catheter welding, remove the nut 2 and the catheter plug 1, and use a wrench to rotate the screw 4 and the pull bolt 5 clockwise or counterclockwise respectively to reduce the outer diameter of the deformation control fixture, then remove the welded catheter from the deformation control fixture, and then remove the deformation control fixture from the three-jaw chuck to complete the welding.

[0041] Optionally, in the automatic welding method for aircraft ducts as described above,

[0042] In step 4, the circumferential welding position of the conduit supported and fixedly mounted on the welding equipment by the deformation control fixture, or the local ear piece of the conduit, or the cross tube of the T-shaped conduit is welded, and a protective gas is introduced during the welding process to provide gas protection during the welding operation; and during the welding process, the axial position of the core shaft 17 is fixed.

[0043] Beneficial effects of the present invention: for the circumferential weld welding and local ear piece welding of small-diameter ducts in aircraft structures, an embodiment of the present invention provides a deformation control fixture for automatic welding of aircraft ducts, which adopts a core shaft 17 with a central axis hole and a screw 4 arranged inside the core shaft 17, and a connecting pin 15 connected to one end of the screw 4 located in the core shaft 17 extends radially out of the waist-shaped hole of the core shaft 17 and is fixedly connected to a first cone sleeve 12 sleeved on the outside of the core shaft 17, and a first expansion block 11 is installed on the outside of the first cone sleeve 12; the screw 4 is driven to move axially along the core shaft 17 by the rotation of the threaded sleeve 3 matched with the screw 4, thereby driving the axial movement of the first cone sleeve 12 to achieve the contraction or expansion of the first expansion block 11; on the basis of this structure, a connection form of a pull bolt 5 threadedly connected to the outside of the core shaft 17 and the second cone sleeve 10 is adopted, and the pull bolt 5 is rotated to make it move axially, so as to drive the axial movement of the second cone sleeve 10, thereby achieving the contraction or expansion of the second expansion block 9. By using the deformation control fixture provided by the embodiment of the present invention, the catheter can be sleeved in the state of the expansion block being contracted. After the catheter is sleeved, the expansion block is expanded by the axial movement of the screw 4 and the pull bolt 5, and the welding process is carried out in the state of the expansion block. This can meet the requirement of supporting the inner wall of the catheter in the catheter welding process. After the welding is completed, the expansion block is expanded by the axial movement of the screw 4 and the pull bolt 5, and the catheter is taken out in the state of the expansion block being contracted. The deformation control fixture provided by the embodiment of the present invention supports the inner wall of the catheter during welding through the expansion block state of the expansion block, and controls the weld excess height in the welding process by filling the catheter with protective gas, thereby improving the welding quality of the catheter and the fatigue life of the catheter. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present invention and do not constitute a limitation on the technical solution of the present invention.

[0045] Figure 1 A schematic diagram of the appearance structure of a deformation control fixture for automatic welding of aircraft ducts provided by an embodiment of the present invention;

[0046] Figure 2 for Figure 1 A cross-sectional view of a deformation control fixture for automatic welding of aircraft ducts provided by the illustrated embodiment;

[0047] Figure 3 for Figure 1 A schematic structural diagram of a mandrel in a deformation control fixture for automatic welding of aircraft ducts provided by the illustrated embodiment;

[0048] Figure 4 for Figure 1 The structural schematic diagram of the screw rod used in the automatic welding of aircraft ducts provided by the illustrated embodiment;

[0049] Figure 5 To adopt Figure 1 The illustrated embodiment is a schematic diagram of an application of a deformation control fixture for automatic welding of aircraft ducts to support welding of aircraft ducts.

[0050] Description of reference numerals:

[0051] 1-catheter plug, 2-nut, 3-threaded sleeve, 4-screw, 5-pull bolt, 6-hexagon socket head screw, 7-flat washer, 8-pressure cap, 9-second expansion block, 10-second cone sleeve, 11-first expansion block, 12-first cone sleeve, 13-tension spring rod, 14-tension spring, 15-connecting pin, 16-positioning sleeve, 17-core shaft, 18-aircraft catheter. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solution and advantages of the present invention more clear, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other arbitrarily without conflict.

[0053] The above background technology has already explained the important role of aircraft ducts, and explained that welded ducts account for a certain proportion in aircraft manufacturing. Specifically, the proportion of aircraft ducts in aircraft manufacturing is significant, and they play an indispensable role in the structural integrity, function realization and safety of aircraft. In aircraft manufacturing, the proportion of aircraft duct welding is about 25% to 35%, especially in the parts with special aircraft duct product structures. The proportion of duct welding reflects the important position of welding technology in aircraft manufacturing, especially in the manufacture of aircraft ducts, the application of welding technology is very extensive.

[0054] For the widely used welded conduits, the weld reinforcement must be controlled during the welding process to avoid the weld reinforcement destroying the continuity of the weld surface geometry and generating additional bending moment due to sudden changes in shape, resulting in higher local stress and other problems.

[0055] In view of the above-mentioned problems and the demand for controlling the residual height of the weld, an embodiment of the present invention provides a deformation control fixture and a welding method for automatic welding of aircraft ducts, which are used to install the deformation control fixture into the duct to be welded before welding, expand the duct to achieve the function of supporting the inner wall of the duct during welding, so as to control the residual height of the weld; and continuously introduce inert protective gas during the welding process to improve the quality of the weld; the deformation control fixture provided by the present invention can realize automatic welding of the entire process in conjunction with an arc welding robot and a three-jaw chuck.

[0056] The present invention provides the following specific embodiments which can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0057] Figure 1 A schematic diagram of the appearance structure of a deformation control fixture for automatic welding of aircraft ducts provided by an embodiment of the present invention, Figure 2 for Figure 1 The embodiment shown is a cross-sectional view of a deformation control fixture for automatic welding of aircraft ducts. Figure 1 and Figure 2 As shown, the deformation control fixture for automatic welding of aircraft ducts provided in an embodiment of the present invention may include: a duct plug 1, a nut 2, a core shaft 17, a screw 4, a threaded sleeve 3, a connecting pin 15, a positioning sleeve 16, a core shaft 17, and at least one set of cone sleeves and expansion block assemblies.

[0058] like Figure 1 and Figure 2The overall structure of the deformation control fixture shown in the figure is that a step hole is opened on one end face of the positioning sleeve 16, and the other end is set as a step shaft. The positioning sleeve 16 is assembled to the three-jaw chuck of the welding equipment through the step shaft; the core shaft 17 is coaxially fixed in the step hole of the positioning sleeve 16 through the positioning connecting flange set at its end; in the specific implementation, the core shaft 17 and the positioning sleeve 16 can be connected by a hexagon socket head screw 6 and a flat washer 7.

[0059] like Figure 1 and Figure 2 As shown, the core shaft 17 in the embodiment of the present invention has a central axis hole along its axis, a catheter plug 1 is sleeved on the outer side of one end of the core shaft 17, and the outer end of the catheter plug 1 is pressed by a nut 2 screwed on the core shaft 17 to axially position the catheter plug 1. The screw 4 is inserted into the central axis hole of the core shaft 17 from one end, and the end of the screw 4 located in the core shaft 17 is threadedly connected to a connecting pin 15 radially perpendicular to the axis of the core shaft 17, and the threaded rod of the screw 4 located outside the core shaft 17 is threadedly connected to a threaded sleeve 3, and the end of the threaded rod is set as a square prism, and the screw 4 is driven to move axially in the core shaft 17 by clamping the square prism and screwing the threaded sleeve 3. As shown Figure 4 As shown, Figure 1 The illustrated embodiment is a schematic structural diagram of a screw rod used in automatic welding of aircraft ducts.

[0060] The following two specific structural forms are provided for the implementation of the cone sleeve and the expansion block assembly in the embodiment of the present invention.

[0061] Implementation 1:

[0062] The deformation control fixture in this implementation method only has one set of cone sleeve and expansion block assembly, and the first set of cone sleeve and expansion block assembly includes: a first cone sleeve 12 and a first expansion block 11 which are arranged as a circumferential split structure; the first cone sleeve 12 is sleeved on the outside of the shaft body of the core shaft 17 and has an outer conical surface, and the first expansion block 11 is sleeved on the outside of the cone sleeve and has an inner conical surface matching the outer conical surface of the first cone sleeve 12; the first expansion block 11 is fixedly connected to the limiting structure in the middle part of the shaft body of the core shaft 17; the connecting pin 15 at one end of the screw rod 4 passes through the first waist-shaped hole on the shaft body of the core shaft 17, and is connected to the first cone sleeve 12 by a screw, so as to drive the first cone sleeve 12 to move axially through the connecting pin 15 when the screw rod 4 moves axially, thereby realizing the contraction or expansion of the first expansion block 11.

[0063] Implementation 2:

[0064] The deformation control fixture in this implementation is further provided with a second set of cone sleeve and expansion block assembly on the basis of the above-mentioned implementation 1, including: a second expansion block 9 and a second cone sleeve 10; the second cone sleeve 10 is sleeved on the outside of the core shaft 17 and has an outer conical surface, the second expansion block 9 is sleeved on the outside of the second cone sleeve 10 and has an inner conical surface matching the outer conical surface of the second cone sleeve 10; the second expansion block 9 is fixedly connected to the limiting structure in the middle of the core shaft 17 shaft body.

[0065] In addition, in this implementation, the second set of cone sleeves and expansion block components are not driven by a screw rod, but have an independent driving mechanism, that is, the deformation control fixture in this implementation also includes: a pull bolt 5 and a connecting component.

[0066] The pull bolt 5 in this implementation is configured as a sleeve structure, which is integrally sleeved and connected to the outside of the shaft body of the core shaft 17 near the catheter plug 1. One end of the pull bolt 5 is provided with an internal threaded hole, and the other end is provided with a stepped through hole, and the end of the stepped through hole has an annular convex shoulder, and the outer wall of the middle part of the pull bolt 5 is configured as a hexagonal prism. The pull bolt 5 is threadedly connected to the outside of the shaft body of the core shaft 17 near one end of the catheter plug 1 through its internal threaded hole, and this end of the pull bolt 5 is located inside the stepped through hole of the catheter plug 1, and the end face of the annular convex shoulder of the pull bolt 5 is attached to the outer end face of the second cone sleeve 10, and the annular convex shoulder of the pull bolt 5 is fixedly connected to the second cone sleeve 10 through a connecting component.

[0067] In this implementation, the movement form of the second group of cone sleeves and expansion block assemblies is: by screwing the hexagonal column structure in the middle of the pull bolt 5, the pull bolt 5 moves axially along the core shaft 17, and drives the second cone sleeve 10 to move axially, thereby realizing the contraction or expansion of the second expansion block 9.

[0068] In one implementation of the embodiment of the present invention, Figure 3 As shown, Figure 1 The embodiment shown is a schematic diagram of the structure of the mandrel in the deformation control fixture for automatic welding of aircraft ducts. The mandrel 17 is provided with the above-mentioned positioning connection flange at one end, and the positioning connection flange is fixed to the inner end face of the stepped hole of the positioning sleeve 16 by means of a hexagon socket head screw 6 and a flat washer 7; the middle part of the mandrel 17 is provided with an expansion block connection flange, and the large circular end faces of the first expansion block 11 and the second expansion block 9 are relatively arranged at the two ends of the expansion block connection flange, and are fixedly connected to the expansion block connection flange by means of screws respectively, the first expansion block 11 is located between the expansion block connection flange and the positioning sleeve 16, and the second expansion block 9 is located between the expansion block connection flange and the duct plug 1.

[0069] In addition, if Figure 3As shown, the shaft body of the core shaft 17 of the embodiment of the present invention is provided with two waist-shaped holes opened along the axial direction, wherein the first waist-shaped hole is used to pass the connecting pin 15, and when the connecting pin 15 moves axially driven by the screw 4, it moves under the guidance of the first waist-shaped hole; the second waist-shaped hole is arranged on the fitting surface of the second cone sleeve 10 and the core shaft 17, and is used to guide the axial movement of the second cone sleeve 10. The guiding structure is specifically described in the following embodiment.

[0070] On the basis of the above-mentioned implementation method 2, a columnar boss is provided on the end surface of the second cone sleeve 10 connected to the pull bolt 5; the connection assembly includes: a gland 8, a hexagon socket head screw 6 and a flat washer 7.

[0071] In this implementation, the pressure cap 8 is configured as a sleeve structure with a stepped through hole inside. The pressure cap 8 is sleeved on the outside of the pull bolt 5 with its small diameter hole end, and the inner ring of the cover plate at its small diameter hole end rests on the outer end face of the annular boss of the pull bolt 5 to form an axial limiting structure; the large diameter hole end of the pressure cap 8 is integrally sleeved on the annular boss of the pull bolt 5 and the outer side of the columnar boss of the second tapered sleeve 10, and the pressure cap 8 is fixedly connected to the large circular end face of the second tapered sleeve 10 by a flat washer 7 and a hexagon socket head screw 6.

[0072] By using the deformation control fixture provided in the embodiment of the present invention, the catheter 18 to be welded is integrally sleeved on the outside of the expansion block, one end of the catheter 18 is embedded and installed in the step hole of the positioning sleeve 16, and the other end is embedded and installed in the step hole of the catheter plug 1, so as to axially limit the catheter 18 through the positioning sleeve 16 and the catheter plug 1; for the first group of cone sleeve and expansion block assemblies in the above-mentioned implementation methods 1 and 2, the screw 4 is driven to move axially in the core shaft 17 by screwing the threaded sleeve 3, and the first cone sleeve 12 is driven to move axially through the connecting pin 10, thereby realizing the contraction or expansion of the first expansion block 11; for the second group of cone sleeve and expansion block assemblies in the above-mentioned implementation method 2, the hexagonal column structure in the middle part of the pull bolt 5 is screwed to make the pull bolt 5 move axially along the core shaft 17, and drive the second cone sleeve 10 to move axially, thereby realizing the contraction or expansion of the second expansion block 9.

[0073] It should be noted that in the two sets of cone sleeve and expansion block assemblies in the embodiment of the present invention, the outer conical surfaces of the first cone sleeve 12 and the second cone sleeve 10 are in opposite directions, and the axial movement of the first cone sleeve 12 and the second cone sleeve 10 is driven separately by different structures in the fixture. Before the welding operation, the catheter is sleeved with the expansion block in a contracted state. After the catheter is sleeved, the expansion block is expanded by axially moving the screw 4 and the pull bolt 5 respectively, and the welding process is carried out in the expanded state of the expansion block, which can meet the requirements of supporting the inner wall of the catheter in the catheter welding process. After the welding is completed, the expansion block is expanded by axially moving the screw 4 and the pull bolt 5 respectively, and the catheter is taken out in the contracted state of the expansion block.

[0074] In one implementation of an embodiment of the present invention, the specific structural form of the first group of cone sleeves and expansion block assemblies is as follows: the first cone sleeve 12 is configured as an outer cone structure with an outer conical surface and an inner circular hole, the first expansion block 11 is configured as an inner cone structure with an outer cylindrical surface and an inner conical surface, and the first expansion block 11 includes a plurality of annular expansion blocks arranged in segments along the circumferential direction, for example, including 4-segment expansion blocks.

[0075] In this implementation, the first tapered sleeve 12 is sleeved on the core shaft 17 through its inner circular hole and is loosely matched with the core shaft 17. Its outer circular conical surface is matched with the inner circular conical surface of the first expansion block 11, and the inner circular hole of the first tapered sleeve 12 is a stepped hole, and a threaded hole is opened on the step end surface. The connecting pin 15 is connected to the step end surface of the first tapered sleeve 12 by a screw, so that the screw 4 is connected to the first tapered sleeve 12 through the connecting pin 15 and the screw. When the rotating screw 4 moves axially under the rotation of the threaded sleeve 3, the first tapered sleeve 12 is driven by the screw 4 to move axially along the core shaft 17, thereby causing the first expansion block 11 to expand or contract.

[0076] In this implementation, the large circular end face of the first expansion block 11 is connected to the end face of the expansion block connecting flange in the middle of the core shaft 17 facing the positioning sleeve 16, which is used to limit the axial position of the first expansion block 11; and a plurality of guide grooves are radially opened on the large circular end face of the first expansion block 11, which cooperate with the cylindrical pins on the end face of the expansion block connecting flange for guidance, and are used to limit the radial position of the first expansion block 11 when it expands or contracts.

[0077] In one implementation of an embodiment of the present invention, the specific structural form of the second group of cone sleeves and expansion block assemblies is as follows: the second cone sleeve 10 is configured as an outer cone structure with an outer conical surface and an inner circular hole, the second expansion block 9 is configured as an inner cone structure with an outer cylindrical surface and an inner conical surface, and the second expansion block 9 includes a plurality of annular segment expansion blocks arranged in segments along the circumferential direction, for example, including 4-segment expansion blocks.

[0078] In this implementation, the second tapered sleeve 10 is sleeved on the core shaft 17 through its inner circular hole and is clearance-matched with the core shaft 17. Its outer conical surface is matched with the inner conical surface of the second expansion block 9, and a cylindrical pin radially perpendicular to the axis is installed on the inner side of the columnar boss of the second tapered sleeve 10. The cylindrical pin is matched with the second waist-shaped hole on the shaft body of the core shaft 17 to guide the second tapered sleeve 10 to move axially.

[0079] In this implementation, the large circular end face of the second expansion block 9 is connected to the end face of the expansion block connecting flange in the middle of the core shaft 17 facing the catheter plug 1, which is used to limit the axial position of the second expansion block 9; and a plurality of guide grooves are radially opened on the large circular end face of the second expansion block 9, which cooperate with the cylindrical pins on the end face of the expansion block connecting flange for guidance, so as to limit the radial position of the second expansion block 9 when it expands or contracts.

[0080] In a preferred implementation scheme of the embodiment of the present invention, at least one annular groove is circumferentially arranged on the outer cylindrical surfaces of the first expansion block 11 and the second expansion block 9, and a tightening mechanism is placed in the annular groove, so that in the process of shrinking the first expansion block 11 and the second expansion block 9, the tightening mechanism can tighten the multiple ring-segment expansion blocks arranged circumferentially in the radial direction, so as to facilitate the removal of the deformation control clamp from the welded catheter.

[0081] The tightening mechanism in this implementation includes: a tension spring 14 , or a tension spring 14 and a tension spring rod 13 .

[0082] One form is that a tension spring 14 is installed around the circumference in each annular groove of the first expansion block 11 and the second expansion block 9, so as to apply radial pressure to a plurality of ring-segment expansion blocks around the circumference.

[0083] Another form is: a plurality of tension spring rods 13 parallel to the axial direction are pressed into the outer cylindrical surface of the first expansion block 11 and the second expansion block 9 along the circumference of each annular groove, and a tension spring 14 is hung between adjacent tension spring rods 13 to apply radial pressure to the multiple ring segment expansion blocks surrounding one circle.

[0084] Furthermore, the outer cylindrical surfaces of the first expansion block 11 and the second expansion block 9 of each embodiment of the present invention are axially provided with triangular grooves for introducing shielding gas; the positioning sleeve 16 is connected to the three-jaw chuck for welding through its step shaft structure, and after the conduit sleeve is mounted on the outside of the expansion block of the deformation control fixture, the axial positions of the two ends are respectively limited by the step holes of the positioning sleeve 16 and the step holes of the conduit plug 1; furthermore, a plurality of ventilation holes are provided on the end face of the conduit plug 1 for introducing shielding gas through the ventilation holes during robot welding.

[0085] In view of the circumferential weld welding and local ear piece welding of small-diameter ducts in aircraft structures, an embodiment of the present invention provides a deformation control fixture for automatic welding of aircraft ducts, which adopts a core shaft 17 with a central axis hole and a screw 4 arranged inside the core shaft 17. A connecting pin 15 connected to one end of the screw 4 located inside the core shaft 17 extends radially out of the waist-shaped hole of the core shaft 17 and is fixedly connected to a first cone sleeve 12 sleeved on the outside of the core shaft 17. A first expansion block 11 is installed on the outside of the first cone sleeve 12; the screw 4 is driven to move axially along the core shaft 17 by the rotation of the threaded sleeve 3 that cooperates with the screw 4, thereby driving the axial movement of the first cone sleeve 12 to achieve the contraction or expansion of the first expansion block 11; on the basis of this structure, a connection form of a pull bolt 5 threadedly connected to the outside of the core shaft 17 and a second cone sleeve 10 is adopted, and the pull bolt 5 is rotated to make it move axially, so as to drive the axial movement of the second cone sleeve 10, thereby achieving the contraction or expansion of the second expansion block 9. By using the deformation control fixture provided by the embodiment of the present invention, the catheter can be sleeved in the state of the expansion block being contracted. After the catheter is sleeved, the expansion block is expanded by the axial movement of the screw 4 and the pull bolt 5, and the welding process is carried out in the state of the expansion block. This can meet the requirement of supporting the inner wall of the catheter in the catheter welding process. After the welding is completed, the expansion block is expanded by the axial movement of the screw 4 and the pull bolt 5, and the catheter is taken out in the state of the expansion block being contracted. The deformation control fixture provided by the embodiment of the present invention supports the inner wall of the catheter during welding through the expansion block state of the expansion block, and controls the weld excess height in the welding process by filling the catheter with protective gas, thereby improving the welding quality of the catheter and the fatigue life of the catheter.

[0086] Based on the deformation control fixture for automatic welding of aircraft ducts provided in the above embodiments of the present invention, the embodiments of the present invention further provide an automatic welding method for aircraft ducts, and the deformation control fixture for automatic welding of aircraft ducts provided in any of the above embodiments can be used to support the aircraft duct to cooperate with the welding operation; in the embodiments of the present invention, for example, Figure 1 and Figure 2 The deformation control fixture shown includes two sets of cone sleeves and expansion block assemblies, which respectively include: a first cone sleeve 12 and a first expansion block 11 used in conjunction with each other, and a second cone sleeve 10 and a second expansion block 9 used in conjunction with each other. The welding method provided by the embodiment of the present invention includes the following implementation steps:

[0087] Step 1, fix the square prism at the end of the screw rod 4, and drive the screw rod 4 to move in the core shaft 17 toward one end close to the positioning sleeve 16 by screwing the threaded sleeve 3 in a clockwise or counterclockwise direction, thereby driving the connecting pin 15 to pull the first cone sleeve 12 to move synchronously, so that the first expansion block 11 contracts; use a wrench to clamp the hexagonal prism in the middle of the pull bolt 5, and rotate it in a clockwise or counterclockwise direction to move the pull bolt 5 along the core shaft 17 away from one end of the positioning sleeve 16, driving the second cone sleeve 10 to move synchronously, so that the second expansion block 9 contracts; put the conduit 18 to be welded on the outside of the first expansion block 11 and the second expansion block 9 in a contracted state, and one end of the conduit 18 is positioned by the positioning sleeve 16.

[0088] like Figure 5 As shown, the Figure 1 The illustrated embodiment is a schematic diagram of an application of a deformation control fixture for automatic welding of aircraft ducts to support welding of aircraft ducts. Figure 5 Taking the T-shaped catheter as an example, the cross tube of the deformation control fixture is sleeved on the outside of the expansion block. At this time, the inner diameter of the entire fixture is smaller than the inner diameter of the T-shaped welding catheter. The cross tube part to be welded is sleeved on the outside of the first expansion block 11 and the second expansion block 9. One end of the catheter 18 is positioned in the step hole of the positioning sleeve 16, and the positioning sleeve 16 is clamped on the three-jaw chuck of the welding equipment.

[0089] Step 2, rotate the screw rod 4 and the pull bolt 5 counterclockwise or clockwise respectively, so that the first expansion block 11 and the second expansion block 9 are expanded to fit on the inner wall of the conduit, and the weld to be welded is supported by the first expansion block 11 and the second expansion block 9.

[0090] like Figure 5 On the inner wall of the T-shaped welded transverse tube in the illustrated embodiment, support is provided at the weld, such as the intersection line or the circumferential weld of the welded T-shaped tube.

[0091] Step 3, after the catheter is positioned, the catheter plug 1 is mounted on the other end of the catheter 18 to axially limit the catheter 18 through the combination of the catheter plug 1 and the positioning sleeve 16, and the catheter plug 1 is locked with the nut 2.

[0092] Step 4, by operating the programming of the robot, the arc welding robot is enabled to perform automatic welding on the weld of the conduit.

[0093] Step 5, after completing the catheter welding, remove the nut 2 and the catheter plug 1, and use a wrench to rotate the screw 4 and the pull bolt 5 clockwise or counterclockwise respectively to reduce the outer diameter of the deformation control fixture, then remove the welded catheter from the deformation control fixture, and then remove the deformation control fixture from the three-jaw chuck to complete the welding.

[0094] In an implementation of the embodiment of the present invention, the placement positions of the first expansion block 7 and the second expansion block 15 in step 2 are, for example, the circumferential welding positions of the two catheters, or the position 13 of the local ear piece of a single catheter.

[0095] Correspondingly, in step 4, the circumferential welding position of the conduit supported and fixedly mounted on the welding equipment by the deformation control fixture, or the local ear piece of the conduit, or the cross tube of the T-shaped conduit is welded, and a protective gas is introduced during the welding process to provide gas protection during the welding operation; and during the welding process, the axial position of the core shaft 17 is fixed.

[0096] Although the embodiments disclosed in the present invention are as above, the contents are only embodiments adopted to facilitate understanding of the present invention and are not intended to limit the present invention. Any technician in the field to which the present invention belongs can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A deformation control fixture for automatic welding of aircraft ducts, characterized in that: include: A catheter plug (1), a nut (2), a screw (4), a threaded sleeve (3), a connecting pin (15), a positioning sleeve (16), a core shaft (17), and at least one set of a cone sleeve and a swelling block assembly; Wherein, one end surface of the positioning sleeve (16) is provided with a stepped hole, and the other end is provided as a stepped shaft; the core shaft (17) is coaxially fixedly installed in the stepped hole of the positioning sleeve (16) through a positioning connection flange provided at its end; The core shaft (17) is provided with a central axis hole along its axis, a catheter plug (1) is sleeved on the outer side of one end of the core shaft (17), and the outer end of the catheter plug (1) is pressed by a nut (2) screwed on the core shaft (17) to axially position the catheter plug (1); the screw rod (4) is inserted into the central axis hole of the core shaft (17) from one end, and one end of the screw rod (4) located in the core shaft (17) is threadedly connected to a connecting pin (15) radially perpendicular to the axis of the core shaft (17), and the threaded rod of the screw rod (4) located outside the core shaft (17) is threadedly connected to a threaded sleeve (3), and the end of the threaded rod is set as a square prism, and the square prism is clamped and the threaded sleeve (3) is screwed to drive the screw rod (4) to move axially in the core shaft (17); The first group of cone sleeve and expansion block components includes: a first cone sleeve (12) and a first expansion block (11) which are arranged as a circumferential split structure; the first cone sleeve (12) is sleeved on the outer side of the shaft body of the core shaft (17) and has an outer conical surface, and the first expansion block (11) is sleeved on the outer side of the cone sleeve and has an inner conical surface matching the outer conical surface of the first cone sleeve (12); the first expansion block (11) is fixedly connected to a limiting structure in the middle part of the shaft body of the core shaft (17); the connecting pin (15) at one end of the screw rod (4) passes through the first waist-shaped hole at one end of the shaft body of the core shaft (17), and is connected to the first cone sleeve (12) by a screw, so as to drive the first cone sleeve (12) to move axially through the connecting pin (15) when the screw rod (4) moves axially, thereby realizing the contraction or expansion of the first expansion block (11).

2. The deformation control fixture for automatic welding of aircraft ducts according to claim 1 is characterized in that: It also includes a second set of cone sleeve and expansion block assembly, including: a second expansion block (9) and a second cone sleeve (10); the second cone sleeve (10) is sleeved on the outside of the core shaft (17) and has an outer conical surface; the second expansion block (9) is sleeved on the outside of the second cone sleeve (10) and has an inner conical surface matching the outer conical surface of the second cone sleeve (10); the second expansion block (9) is fixedly connected to the limiting structure in the middle of the shaft body of the core shaft (17); The deformation control fixture further comprises: a pull bolt (5) and a connecting component; The pull bolt (5) is configured as a sleeve structure, which is integrally sleeved and connected to the outside of the shaft body of the core shaft (17) near the catheter plug (1), one end of the pull bolt (5) is provided with an internal threaded hole, the other end is provided with a stepped through hole, and the end of the stepped through hole has an annular boss, and the outer wall of the middle part of the pull bolt (5) is configured as a hexagonal prism; the pull bolt (5) is threadedly connected to the outside of the shaft body of the core shaft (17) near one end of the plug (1) through its internal threaded hole, the end face of the annular boss of the pull bolt (5) is fitted on the outer end face of the second cone sleeve (10), and the annular boss of the pull bolt (5) is fixedly connected to the second cone sleeve (10) through a connecting component; By screwing the hexagonal column structure in the middle of the pull bolt (5), the pull bolt (5) is moved axially along the core shaft (17), and the second cone sleeve (10) is driven to move axially, thereby achieving the contraction or expansion of the second expansion block (9).

3. The deformation control fixture for automatic welding of aircraft ducts according to claim 2 is characterized in that: A swelling block connecting flange is arranged in the middle of the core shaft (17); the large circular end surfaces of the first swelling block (11) and the second swelling block (9) are arranged at two ends of the swelling block connecting flange opposite to each other and are fixedly connected to the swelling block connecting flange by screws respectively; the first swelling block (11) is located between the swelling block connecting flange and the positioning sleeve (16); the second swelling block (9) is located between the swelling block connecting flange and the catheter plug (1); and the outer circular conical surfaces of the first cone sleeve (12) and the second cone sleeve (10) are in opposite directions.

4. The deformation control fixture for automatic welding of aircraft ducts according to claim 3 is characterized in that: The end surface of one end of the second cone sleeve (10) connected to the pull bolt (5) is provided with a columnar boss; the connection assembly comprises: a gland (8), a hexagon socket head screw (6) and a flat washer (7); The pressure cover (8) is configured as a sleeve structure with a stepped through hole inside. The pressure cover (8) is sleeved on the outside of the pull bolt (5) with its small diameter hole end, and the inner ring of the cover plate at its small diameter hole end abuts against the outer end face of the annular boss of the pull bolt (5) to form an axial limiting structure; the large diameter hole end of the pressure cover (8) is integrally sleeved on the annular boss of the pull bolt (5) and the outer side of the columnar boss of the second cone sleeve (10), and a flat washer (7) and a hexagon socket head screw (6) are used to fix the pressure cover (8) on the large circular end face of the second cone sleeve (10).

5. The deformation control fixture for automatic welding of aircraft ducts according to claim 4, characterized in that: In the first set of cone sleeve and expansion block assembly, The first cone sleeve (12) is configured as an outer cone structure with an outer cone surface and an inner circular hole, the first expansion block (11) is configured as an inner cone structure with an outer cylindrical surface and an inner cone surface, and the first expansion block (11) comprises a plurality of segment expansion blocks arranged in sections along the circumferential direction; The first cone sleeve (12) is sleeved on the core shaft (17) through its inner circular hole and is loosely matched with the core shaft (17). Its outer circular conical surface is matched with the inner circular conical surface of the first expansion block (11). The inner circular hole of the first cone sleeve (12) is a stepped hole, and a threaded hole is provided on the stepped end surface. The connecting pin (15) is connected to the stepped end surface of the first cone sleeve (12) by a screw, so that the screw rod (4) is connected to the first cone sleeve (12) through the connecting pin (15) and the screw. When the rotating screw rod (4) moves axially under the rotation of the threaded sleeve (3), the first cone sleeve (12) is driven by the screw rod (4) to move axially along the core shaft (17), so that the first expansion block (11) expands or contracts. The large circular end face of the first expansion block (11) is connected to the end face of the expansion block connecting flange in the middle of the core shaft (17) facing the positioning sleeve (16), and is used to limit the axial position of the first expansion block (11); and a plurality of guide grooves are radially opened on the large circular end face of the first expansion block (11), which cooperate with the cylindrical pins on the end face of the expansion block connecting flange for guiding, and are used to limit the radial position of the first expansion block (11) when it expands or contracts.

6. The deformation control fixture for automatic welding of aircraft ducts according to claim 5, characterized in that: In the second set of cone sleeve and expansion block assembly, The second cone sleeve (10) is configured as an outer cone structure with an outer cone surface and an inner circular hole, the second expansion block (9) is configured as an inner cone structure with an outer cylindrical surface and an inner cone surface, and the second expansion block (9) comprises a plurality of segment expansion blocks arranged in sections along the circumferential direction; The second cone sleeve (10) is sleeved on the core shaft (17) through its inner circular hole and is loosely matched with the core shaft (17). Its outer circular conical surface is matched with the inner circular conical surface of the second expansion block (9). A cylindrical pin perpendicular to the axis in the radial direction is installed on the inner side of the columnar boss of the second cone sleeve (10). The cylindrical pin is matched with the second waist-shaped hole on the shaft body of the core shaft (17) to guide the second cone sleeve (10) to move in the axial direction. The large circular end face of the second expansion block (9) is connected to the end face of the expansion block connecting flange in the middle of the core shaft (17) facing the catheter plug (1), and is used to limit the axial position of the second expansion block (9); and a plurality of guide grooves are radially opened on the large circular end face of the second expansion block (9), which cooperate with the cylindrical pins on the end face of the expansion block connecting flange for guidance, and are used to limit the radial position of the second expansion block (9) when it expands or contracts.

7. The deformation control fixture for automatic welding of aircraft ducts according to any one of claims 2 to 6, characterized in that: The outer cylindrical surfaces of the first expansion block (11) and the second expansion block (9) are provided with at least one annular groove along the circumferential direction, and a tightening mechanism is placed in the annular groove, so that during the process of shrinking the first expansion block (11) and the second expansion block (9), the tightening mechanism can tighten the multiple ring-segment expansion blocks arranged along the circumferential direction in the radial direction, so as to facilitate the removal of the deformation control fixture from the welded conduit; Wherein, the tightening mechanism comprises: a tension spring (14), or a tension spring (14) and a tension spring rod (13); In each annular groove of the first expansion block (11) and the second expansion block (9), a tension spring (14) is installed around the circumference, which is used to apply radial pressure to the multiple ring segment expansion blocks around the circumference; or, A plurality of tension spring rods (13) parallel to the axial direction are pressed into the outer cylindrical surfaces of the first expansion block (11) and the second expansion block (9) along the circumference of each annular groove, and a tension spring (14) is hung between adjacent tension spring rods (13) for applying radial pressure to the plurality of annular expansion blocks surrounding the ring.

8. The deformation control fixture for automatic welding of aircraft ducts according to any one of claims 2 to 6, characterized in that: The outer cylindrical surfaces of the first expansion block (11) and the second expansion block (9) are provided with triangular grooves along the axial direction for introducing protective gas; The positioning sleeve (16) is connected to the three-jaw chuck for welding through its stepped shaft structure. After the catheter sleeve is mounted on the outside of the expansion block of the deformation control fixture, the axial positions of the two ends are respectively limited by the stepped holes of the positioning sleeve (16) and the stepped holes of the catheter plug (1). Wherein, a plurality of ventilation holes are provided on the end surface of the conduit plug (1), which are used to introduce protective gas through the ventilation holes during robot welding.

9. An automatic welding method for aircraft ducts, characterized in that: The deformation control fixture for automatic welding of aircraft ducts according to any one of claims 1 to 8 is used to support the aircraft duct to cooperate with the welding operation; The deformation control fixture comprises two sets of cone sleeve and expansion block assemblies, respectively comprising: a first cone sleeve (12) and a first expansion block (11) used in conjunction with each other, and a second cone sleeve (10) and a second expansion block (9) used in conjunction with each other; the welding method comprises: Step 1, fix the square prism at the end of the screw rod (4), and drive the screw rod (4) to move in the mandrel (17) toward one end close to the positioning sleeve (16) by screwing the threaded sleeve (3) in a clockwise or counterclockwise direction, thereby driving the connecting pin (15) to pull the first cone sleeve (12) to move synchronously, so that the first expansion block (11) contracts; use a wrench to clamp the hexagonal prism in the middle of the pull bolt (5), and rotate it in a clockwise or counterclockwise direction, so that the pull bolt (5) moves along the mandrel (17) away from one end of the positioning sleeve (16), driving the second cone sleeve (10) to move synchronously, so that the second expansion block (9) contracts; put the conduit 18 to be welded on the outside of the first expansion block (11) and the second expansion block (9) in a contracted state, and one end of the conduit 18 is positioned by the positioning sleeve (16); Step 2, rotating the screw rod (4) and the pull bolt (5) counterclockwise or clockwise respectively, so that the first expansion block (11) and the second expansion block (9) are expanded to fit on the inner wall of the conduit, and the weld to be welded is supported by the first expansion block (11) and the second expansion block (9); Step 3, after positioning the catheter, put the catheter plug (1) on the other end of the catheter 18 to axially limit the catheter 18 through the combination of the catheter plug (1) and the positioning sleeve (16), and lock the catheter plug (1) with a nut (2). Step 4, by operating the programming of the robot, the arc welding robot performs automatic welding on the weld of the conduit; Step 5, after completing the catheter welding, remove the nut (2) and the catheter plug (1), and use a wrench to rotate the screw (4) and the pull bolt (5) clockwise or counterclockwise respectively to reduce the outer diameter of the deformation control fixture, then remove the welded catheter from the deformation control fixture, and then remove the deformation control fixture from the three-jaw chuck to complete the welding.

10. The automatic welding method for aircraft ducts according to claim 9, characterized in that: In step 4, the circumferential welding position of the conduit supported and fixedly mounted on the welding equipment by the deformation control fixture, or the local ear piece of the conduit, or the cross tube of the T-shaped conduit is welded, and protective gas is introduced during the welding process to provide gas protection during the welding operation; and during the welding process, the axial position of the core shaft (17) is fixed.

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