A special welding positioning device and positioning welding method for a straight pipe assembly of a ventilation box

Abstract

The application discloses a special welding positioning device and positioning welding method for an aero-engine accessory oil tank ventilation tank straight pipe assembly, and the welding positioning device comprises a cylinder body, a positioning pin, a first positioning block and a second positioning block. The positioning welding of the ventilation tank straight pipe assembly is carried out by adopting the method and the device, so that the positioning and welding time of parts is greatly reduced, the consistency and welding quality of the assembly after welding are effectively controlled under the guarantee of the device, the production cycle is greatly shortened, the appearance quality of the product is improved, and the one-time welding qualified rate of the assembly is ensured by the mistake-proof design of the device.

Description

Technical Field

[0001] This invention belongs to the field of welding technology, specifically a special welding positioning device and positioning welding method for straight pipe assemblies of lubricating oil tank ventilation boxes for aircraft engines, applicable to the positioning welding of straight pipe welding assemblies. Background Technology

[0002] Ventilation box straight pipe assemblies are typical components of lubricating oil tank series products. Ventilation box straight pipe assemblies are widely used in the field of aerospace equipment manufacturing, especially in the manufacturing of lubricating oil tank ventilation box straight pipe assemblies in aero-engine cooling systems. Due to the structural requirements of the ventilation box straight pipe assembly itself, there are certain relative positional requirements between the parts. Furthermore, because each part needs to be fixed in position without limit design, it is difficult to guarantee the consistency of the welded ventilation box straight pipe assembly.

[0003] like Figure 2 The diagram shows a typical structure of a straight pipe assembly for a ventilation box. It mainly consists of three pipes of different diameters that are coaxially fitted together. The innermost pipe is the longest and has multiple holes on its surface. The two outermost pipes are axially misaligned (i.e., the end faces of the two pipes are not aligned). The right end of the smaller diameter pipe has a small end cap. Figure 2 The right end of the middle pipe), the left end of the larger diameter pipe is the large end cap (middle right end). Figure 2 (Middle left end).

[0004] Currently, the welding positioning method for each part in the straight pipe assembly of the ventilation box is usually manual scribing positioning (i.e., relying solely on measuring tools to determine the relative positions of each part). This method involves many scribing operations and relies on the experience of operators for assembly and welding. There are no fixed assembly and welding steps. The assembly process requires the cooperation of one welder and one sheet metal worker. The manual scribing positioning method has large positioning errors, and the stability of sheet metal worker-assisted positioning is not good. It is completely dependent on the experience of different operators, resulting in poor positioning consistency, long processing cycle, low efficiency, poor assembly welding consistency, and easy welding of incorrect parts, leading to product rework and repair. Summary of the Invention

[0005] This invention aims to provide a dedicated welding positioning device and positioning welding method for straight pipe assemblies of ventilation boxes, in order to solve the problem of difficulty in ensuring the design dimensions of various parts of the straight pipe assembly during the welding process, to rationalize the welding process, improve the accuracy of key dimensions of the straight pipe assembly after welding and the consistency of the welded products, to eliminate the errors caused by manual scribing and positioning, and to shorten the part positioning time, thereby improving the product qualification rate and production efficiency and reducing production costs.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A special welding positioning device for a ventilation box straight pipe assembly, the special welding positioning device comprises,

[0008] A cylinder body, the cylinder body is circular ring section, an inner hole formed by an inner ring of the cylinder body constitutes a first positioning hole, a cylindrical surface formed by an outer ring of the cylinder body is provided with a second positioning hole, an axis of the second positioning hole is perpendicular to an axis of the first positioning hole, a first positioning shaft is arranged on an axial first annular end surface of the cylinder body, an axis of the first positioning shaft is parallel to the axis of the first positioning hole, a plurality of positioning bosses are arranged on an axial second annular end surface of the cylinder body, the plurality of positioning bosses are distributed on a circumference coaxial with the first positioning hole, and the positioning bosses extend along a direction parallel to the axis of the first positioning hole;

[0009] A first positioning block, an axial first end surface of the first positioning block is provided with a first O-shaped groove and a plurality of positioning bosses, the plurality of positioning bosses are distributed on a circumference coaxial with the first positioning block, the first O-shaped groove is coaxial with the first positioning block and has an inner diameter less than or equal to a diameter of the circumference where the plurality of positioning bosses are located, the positioning bosses extend along a direction parallel to an axis of the first positioning block, a bottom surface of the first O-shaped groove is provided with a second O-shaped groove, the second O-shaped groove is coaxial with the first O-shaped groove, and a second positioning shaft is arranged on a region of the bottom surface of the first O-shaped groove other than the second O-shaped groove, an axis of the second positioning shaft is parallel to the first positioning block;

[0010] A second positioning block, the second positioning block is circular ring section, an inner hole formed by an inner ring of the second positioning block constitutes a third positioning hole, a cylindrical surface formed by an outer ring of the second positioning block is provided with a fourth positioning hole, an axis of the fourth positioning hole is perpendicular to an axis of the third positioning hole, a plurality of positioning bosses are arranged on an axial first annular end surface of the second positioning block, the plurality of positioning bosses extend along a direction parallel to an axis of the third positioning hole, and a third positioning shaft is arranged on one of the positioning bosses, an axis of the third positioning shaft is parallel to the axis of the third positioning hole;

[0011] A positioning pin, the positioning pin is a stepped cylindrical shaft type pin, and the positioning pin is detachably inserted into the second positioning hole and the fourth positioning hole.

[0012] As an option, the axial second annular end surface of the cylinder body is provided with a first positioning boss, a second positioning boss and a third positioning boss with a central angle of 120°;

[0013] The axial first end surface of the first positioning block is provided with a fourth positioning boss, a fifth positioning boss and a sixth positioning boss with a central angle of 120°;

[0014] The axial first annular end surface of the second positioning block is provided with a seventh positioning boss and an eighth positioning boss with a central angle of 180°, the third positioning shaft is arranged on the seventh positioning boss, and a central angle between the seventh positioning boss and the fourth positioning hole is 90°.

[0015] Further, the cylinder, the first positioning block, the second positioning block and the positioning pin are made of H62 material.

[0016] Further, the positioning pin comprises two cylindrical portions, one of which is a smooth cylindrical portion with a small outer diameter, and the other is a cylindrical portion with an anti-slip net pattern on the surface and a large outer diameter.

[0017] A positioning and welding method of a ventilation box straight pipe assembly, the ventilation box straight pipe assembly mainly comprises a first straight pipe, a second straight pipe and a third straight pipe which are coaxially and misalignedly assembled with increasing diameters, a large end cover is arranged between the first straight pipe and the third straight pipe, a small end cover is arranged between the first straight pipe and the second straight pipe, holes are formed in the large end cover, the small end cover and the first straight pipe, supports are arranged between the outer wall of the first straight pipe and the inner wall of the second straight pipe, and between the outer wall of the second straight pipe and the inner wall of the third straight pipe, and the positioning and welding method of the ventilation box straight pipe assembly comprises the following steps:

[0018] Step one, positioning and welding the small end cover on the surface of the first straight pipe by the positioning device;

[0019] Step two, positioning and welding the support on the surface of the first straight pipe by the positioning device;

[0020] Step three, assembling the second straight pipe on the outer surface of the first straight pipe, then welding the second straight pipe with the small end cover in step one, and then positioning and welding the support on the surface of the second straight pipe by the positioning device;

[0021] Step four, positioning and welding the large end cover on the surface of the first straight pipe by the positioning device.

[0022] Further, the positioning and welding method of the ventilation box straight pipe assembly further comprises step five, sleeving the third straight pipe on the outer side of the second straight pipe and welding it with the large end cover.

[0023] As an option, the positioning and welding method of the ventilation box straight pipe assembly implements steps one to four by using the aforementioned special welding positioning device, wherein:

[0024] In the step one, the cylinder is sleeved on the axial first end of the first straight pipe through the first positioning hole, the cylinder is rotated and translated until the second positioning hole is aligned with the hole position on the surface of the first straight pipe, then the positioning pin is inserted into the second positioning hole until the positioning pin enters the hole position on the surface of the first straight pipe, then the small end cover is sleeved into the first straight pipe and positioned by cooperating the hole position of the small end cover with the first positioning shaft of the cylinder, when the end face of the small end cover is attached to the axial first annular end face of the cylinder, the welding of the first straight pipe and the small end cover is implemented;

[0025] In the second step, the positioning pin is pulled out, the cylinder is removed from the first straight pipe, the cylinder is sleeved on the axial second end of the first straight pipe through the first positioning hole again, and it is ensured that the positioning boss on the cylinder points to the small end cover. The cylinder is rotated and translated until the second positioning hole is aligned with the hole position on the surface of the first straight pipe. Then, the positioning pin is inserted into the second positioning hole until the positioning pin enters the hole position on the surface of the first straight pipe. At this time, the bracket is pressed tightly on the positioning boss of the cylinder and abuts against the second annular end face. The welding of the bracket on the surface of the first straight pipe is performed.

[0026] In the third step, the positioning pin is pulled out, the cylinder is removed from the first straight pipe, the second straight pipe is sleeved on the outside of the first straight pipe, and it is ensured that the bracket is in good contact with the inner wall of the second straight pipe. The welding of the second straight pipe and the small end cover is performed. The first positioning block is sleeved on the small end cover side of the first straight pipe. The second positioning shaft of the first positioning block is matched with the hole position on the small end cover to realize positioning. The first positioning block is moved until the surface of the first O-shaped groove bottom surface of the first positioning block abuts against the surface of the small end cover. At this time, the bracket is pressed tightly on the positioning boss of the first positioning block and abuts against the axial first end face of the first positioning block. The welding of the bracket on the surface of the second straight pipe is performed.

[0027] In the fourth step, the first positioning block is removed, the large end cover is sleeved on the axial second end of the first straight pipe, then the second positioning block is sleeved on the axial second end of the first straight pipe through the third positioning hole, the second positioning block is rotated and translated until the fourth positioning hole is aligned with the hole position on the surface of the first straight pipe. Then, the positioning pin is inserted into the fourth positioning hole until the positioning pin enters the hole position on the surface of the first straight pipe. The large end cover is rotated and translated until the third positioning shaft on the second positioning block enters the hole position on the large end cover. When the end face of the large end cover abuts against the end face of the positioning boss on the axial first annular end face of the second positioning block, the welding of the large end cover and the first straight pipe is performed.

[0028] Further, the positioning and welding method of the straight pipe assembly of the ventilation box further includes a fifth step of removing the second positioning block, sleeving the third straight pipe on the outside of the second straight pipe, and performing the welding of the third straight pipe and the large end cover.

[0029] Compared with the prior art, the positioning and welding method of the straight pipe assembly of the ventilation box and the welding positioning device have the following characteristics:

[0030] (1) The welding positioning device utilizes the original hole position of the straight pipe assembly for positioning, and is relatively simple to manufacture, fast to assemble during use, and simple to use;

[0031] (2) The welding positioning device that has passed inspection greatly improves the consistency of the welded ventilation box straight pipe assembly;

[0032] (3) The welding positioning device meets the design size requirements and installation requirements, has good use effect, and has stable quality;

[0033] (4) Welding positioning device uses the original hole position on the small end cover, large end cover and first straight pipe as welding positioning hole, cancels the metal worker's assistance in welding process, reduces the labor operation amount;

[0034] (5) Realize the integration of positioning and welding (positioning welding) function, small error;

[0035] (6) The welding positioning method is reasonable in sequence, reduces the correction process and rework repair probability under the premise of meeting the dimensional tolerance technical requirement. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 It is assembly schematic view of special welding positioning device in the application;

[0037] Figure 2 It is straight pipe assembly schematic view of ventilation box;

[0038] Figure 3 It is cylinder schematic view;

[0039] Figure 4 It is positioning pin schematic view;

[0040] Figure 5 It is first positioning block schematic view;

[0041] Figure 6 It is second positioning block schematic view;

[0042] In the drawing: 1. Cylinder; 2. Positioning pin; 3. First positioning block; 4. Second positioning block; 5. First straight pipe; 6. Second straight pipe; 7. Third straight pipe; 8. Small end cover; 9. Large end cover. DETAILED DESCRIPTION

[0043] The application will be further described below in combination with the drawings and specific embodiments, but it should not be understood that the scope of the subject matter described in the application is limited to the following embodiments, and any modification, replacement and change made according to the ordinary technical knowledge and conventional means in the art without departing from the above technical idea of the application are included in the scope of the application.

[0044] Referring to Figure 2 , the straight pipe assembly of ventilation box is mainly composed of first straight pipe 5, second straight pipe 6 and third straight pipe 7 which are coaxially misassembled with increasing diameter, the large end cover 9 is arranged between the first straight pipe 5 and the third straight pipe 7, the small end cover 8 is arranged between the first straight pipe 5 and the second straight pipe 6, the hole position is opened on the large end cover 9, small end cover 8 and first straight pipe 5, the support is arranged between the outer wall of first straight pipe 5 and the inner wall of second straight pipe 6, and between the outer wall of second straight pipe 6 and the inner wall of third straight pipe 7.

[0045] The use state of the welding positioning device designed in the application is as followsFigure 1 As shown in the drawings, the welding positioning of the parts of the straight pipe assembly of the ventilation box is achieved by combining the cylinder 1, the first positioning block 3 and the second positioning block 4 according to the positioning elements (the spatial positions of the parts, the relative positions between different parts) of the parts of the straight pipe assembly of the ventilation box.

[0046] The positioning elements are shown in the drawings. Figure 2 The device and principle of the present application will be described in detail with the parts of the straight pipe assembly of the ventilation box shown in the drawings as an example. The welding positioning device specifically comprises:

[0047] The cylinder 1, as shown in the drawings, is provided with a first positioning hole and a second positioning hole for positioning the relative positions of the cylinder 1 and the straight pipe parts. Figure 3 The left end face of the cylinder 1 is provided with a first positioning shaft, and the right end face is provided with a first positioning boss, a second positioning boss and a third positioning boss. The first included angle between the first positioning boss and the second positioning boss is 120°, and the second included angle between the first positioning boss and the third positioning boss is 120°, which are used for positioning the spatial positions of the parts to be welded with the straight pipe parts and the relative positions between the parts.

[0048] The positioning pin 2, as shown in the drawings, is provided with an anti-slip textured cylinder at the top for easy assembly and disassembly. The bottom of the positioning pin 2 is provided with a smooth cylinder, and the lower end face of the smooth cylinder is provided with a chamfer C1, which is used in cooperation with the second positioning hole and the fourth positioning hole to position the relative positions of the cylinder 1, the second positioning block 4 and the straight pipe parts. Figure 4 The first positioning block 3, as shown in the drawings, is provided with a first 0-type groove and a second 0-type groove. The first 0-type groove is used in cooperation with the assembly of the straight pipe parts, and the right end face of the second 0-type groove is used to limit the spatial position of the parts. The second positioning shaft is arranged on the interface between the first 0-type groove and the second 0-type groove to determine the relative position of the first positioning block 3 and the straight pipe parts. The right end face of the second 0-type groove is provided with a fourth positioning boss, a fifth positioning boss and a sixth positioning boss. The third included angle between the fourth positioning boss and the fifth positioning boss is 120°, and the fourth included angle between the fourth positioning boss and the sixth positioning boss is 120°, which are used for positioning the relative positions of the parts to be welded with the straight pipe parts.

[0049] Figure 5 The second positioning block 4, as shown in the drawings, is provided with a third 0-type groove and a fourth 0-type groove. The third 0-type groove is used in cooperation with the assembly of the straight pipe parts, and the right end face of the fourth 0-type groove is used to limit the spatial position of the parts. The second positioning shaft is arranged on the interface between the third 0-type groove and the fourth 0-type groove to determine the relative position of the second positioning block 4 and the straight pipe parts. The right end face of the fourth 0-type groove is provided with a seventh positioning boss, an eighth positioning boss and a ninth positioning boss. The fifth included angle between the seventh positioning boss and the eighth positioning boss is 120°, and the sixth included angle between the seventh positioning boss and the ninth positioning boss is 120°, which are used for positioning the relative positions of the parts to be welded with the straight pipe parts.

[0050] The second positioning block 4, as shown in the drawings, is provided with a third 0-type groove and a fourth 0-type groove. The third 0-type groove is used in cooperation with the assembly of the straight pipe parts, and the right end face of the fourth 0-type groove is used to limit the spatial position of the parts. The second positioning shaft is arranged on the interface between the third 0-type groove and the fourth 0-type groove to determine the relative position of the second positioning block 4 and the straight pipe parts. The right end face of the fourth 0-type groove is provided with a seventh positioning boss, an eighth positioning boss and a ninth positioning boss. The fifth included angle between the seventh positioning boss and the eighth positioning boss is 120°, and the sixth included angle between the seventh positioning boss and the ninth positioning boss is 120°, which are used for positioning the relative positions of the parts to be welded with the straight pipe parts. Figure 6 ​, the second positioning block 4 is provided with a third positioning hole and a fourth positioning hole for positioning the relative position of the second positioning block 4 and the straight pipe part; the left end surface of the second positioning block 4 is provided with a seventh positioning boss and an eighth positioning boss, and the left end surface of the seventh positioning boss is further provided with a third positioning shaft, which, in combination with the left end surface of the seventh positioning boss, determines the relative position between the straight pipe part and the part to be welded thereto.

[0051] The different positioning elements on the cylinder body 1, the first positioning block 3 and the second positioning block 4 can determine the relative positions between the straight pipe part and each part to be welded thereto, and accordingly, the spatial positions of each part are locked.

[0052] Design method of the welding positioning device:

[0053] (1) The first and second positioning holes of the cylinder body 1 are designed according to the diameter of the outer cylindrical surface of the first straight pipe 5 and the position size and hole diameter of the hole on the cylindrical surface, respectively. After the cylinder body 1 is assembled with the first straight pipe 5, the two are concentric, and the distance between the second positioning hole of the cylinder body 1 and the left and right end surfaces is designed according to the spatial positions of the two different parts to be welded, i.e. the bracket and the small end cover 8, and has the functions of being used in both directions;

[0054] (2) The first, second and third positioning bosses of the cylinder body 1 are designed according to the relative position of the small bracket to be welded (i.e. the bracket on the outer surface of the first straight pipe 5, similar to a few characters) and the first straight pipe 5 and the inner profile of the small bracket (i.e. the outer profile of the positioning boss is designed according to the inner profile of the small bracket, which satisfies that the small bracket can be accurately attached to the outer profile of the positioning boss);

[0055] (3) The first positioning shaft of the cylinder body 1 is designed according to the relative position of the hole after the small end cover 8 to be welded is assembled with the first straight pipe 5 and the hole diameter size;

[0056] (4) The positioning pin 2 is designed according to the first positioning hole of the cylinder body 1, the fourth positioning hole of the second positioning block 4 and the hole diameter size of the hole on the cylindrical surface of the first straight pipe 5;

[0057] (5) The second positioning shaft of the first positioning block 3 is designed according to the size of the hole diameter on the small end cover 8 and the relative position after the assembly of the small end cover 8 and the first straight pipe 5, and the spatial position of the first positioning block 3 needs to be inserted into the hole of the small end cover 8, and the first O-shaped groove is locked after the bottom of the first O-shaped groove is attached to the end surface of the straight pipe part to be welded. The first O-shaped groove and the second O-shaped groove are designed according to the outer diameter of the small end cover 8 and the outer diameter of the first straight pipe 5, and after the first positioning block 3 is assembled with the second straight pipe 6, the two are concentric. Specifically, after the first positioning block 3 is assembled with the second straight pipe 6, the first and second O-shaped grooves are concentric with the first straight pipe 5 and the second straight pipe 6;

[0058] (6) The fourth, fifth and sixth positioning bosses of the first positioning block 3 are designed based on the relative position of the large bracket to be welded (i.e. the bracket on the outer surface of the second straight pipe 6, similar to the shape of a zigzag) and the second straight pipe 6 after assembly and the inner surface of the large bracket, so that the surface of the large bracket can fit on the outer surface of the positioning boss.

[0059] (7) The third and fourth positioning holes of the second positioning block 4 are designed based on the outer diameter of the first straight tube 5 and the position size and diameter of the hole on the cylindrical surface, respectively. After the second positioning block 4 and the first straight tube 5 are assembled, they are concentric.

[0060] (8) The third positioning shaft of the second positioning block 4 is designed based on the relative position and diameter of the hole after the large end cover 9 and the first straight tube 5 are assembled.

[0061] (9) The seventh and eighth positioning bosses of the second positioning block 4 are designed based on the relative position dimensions of the large end cover 9 and the first straight tube 5 after assembly.

[0062] (10) The raw materials of each component of the welding positioning device are H62 brass, which has good insulation with the substrate of the part to be welded. In addition, H62 brass also has good thermal conductivity, which can reduce the welding deformation of the part caused by welding to a certain extent.

[0063] (11) The spatial positions of the cylinder 1 and the second positioning block 4 are locked only after they are assembled with the corresponding first straight pipe 5 and positioning pin 2.

[0064] like Figure 1 As shown, the positioning and welding process of each component in the straight pipe assembly of the ventilation box is as follows:

[0065] (1) Assemble the cylinder 1 with the first straight pipe 5 through the first positioning hole, aligning the second positioning hole of the cylinder 1 with the hole on the first straight pipe 5, insert the positioning pin 2, and then assemble the small end cap 8 to be welded with the cylinder 1 through the first positioning shaft, ensuring that the small end cap 8 to be welded is aligned with the left end face of the cylinder 1 (i.e., Figure 1 The end face of the middle cylinder 1 without the positioning boss is fitted around the circumference, and the inner ring of the small end cap 8 and the first straight pipe 5 are welded together.

[0066] (2) After the small end cap 8 is welded to the first straight pipe 5, the cylinder 1 is disassembled from the first straight pipe 5. After reversing the direction of the cylinder 1, it is reassembled with the other end of the first straight pipe 5 through the first positioning hole, so that the second positioning hole of the cylinder 1 is aligned with the positioning block hole on the first straight pipe 5. The positioning pin 2 is inserted, and then the three brackets to be welded are assembled through the first positioning boss, the second positioning boss and the third positioning boss respectively, ensuring that the three brackets to be welded are aligned with the first positioning boss, the second positioning boss, the third positioning boss and the right end face of the cylinder 1 (i.e. Figure 1 The end face of the positioning boss on the middle cylinder 1 is in contact with it;

[0067] (3) After the bottom surfaces of the three brackets are welded to the cylindrical surface of the first straight pipe 5, the cylinder body 1 is disassembled from the first straight pipe 5, the second straight pipe 6 is sleeved outside the first straight pipe 5, the inner cylindrical surface of the second straight pipe 6 is welded to the outer ring of the small end cover 8 after the two ends of the second straight pipe 6 are respectively aligned with the small end cover 8 and the three welded brackets, and the three brackets only serve as a support structure for assembling and supporting the second straight pipe 6 and are not welded to the second straight pipe 6.

[0068] (4) The first positioning block 3 is assembled with the second straight pipe 6 through the first O-shaped groove, the second positioning shaft is inserted into the hole position provided on the welded small end cover 8, the interface between the first O-shaped groove and the second O-shaped groove is attached to the welded small end cover 8 along the circumference, then the three brackets to be welded are respectively assembled with the fourth positioning boss, the fifth positioning boss and the sixth positioning boss, and the three brackets to be welded are attached to the fourth positioning boss, the fifth positioning boss, the sixth positioning boss and the right end surface of the first positioning block 3 (i.e. the end surface of the first positioning block 3 with the positioning boss), and the bottom surfaces of the three brackets are welded to the outer cylindrical surface of the second straight pipe 6. Figure 1

[0069] (5) After the three brackets are welded to the surface of the second straight pipe 6, the first positioning block 3 is removed from the second straight pipe 6.

[0070] (6) The large end cover 9 to be welded is first sleeved on the first straight pipe 5, the second positioning block 4 is assembled with the first straight pipe 5 through the third positioning hole, the fourth positioning hole of the second positioning block 4 is aligned with the hole position on the first straight pipe 5, the positioning pin 2 is inserted, then the large end cover 9 to be welded is assembled with the second positioning block 4, the hole provided on the large end cover 9 to be welded passes through the third positioning shaft provided on the second positioning block 4, the left end surface of the large end cover 9 to be welded is attached to the left end surface of the seventh positioning boss and the eighth positioning boss (i.e. the end surface of the seventh positioning boss and the eighth positioning boss), and the outer cylindrical surface of the first straight pipe 5 is welded to the inner ring of the large end cover 9. Figure 1

[0071] (7) After the large end cover 9 is welded to the first straight pipe 5, the second positioning block 4 is disassembled from the first straight pipe 5, and finally the third straight pipe 7 is sleeved outside the second straight pipe 6, the third straight pipe 7 is aligned with the large end cover 9 and the three brackets on the surface of the second straight pipe 6, the welding of the outer ring of the large end cover 9 to the inner cylindrical surface of the third straight pipe 7 is performed, and the three brackets only serve as an assembly support structure and are not welded to the third straight pipe 7. At this point, the relative positions of the parts on the straight pipe assembly have been fixed and welded.​​

Claims

1. A dedicated welding fixture for a plenum chamber straight duct assembly, characterized by: The special welding positioning device comprises, A cylinder (1) is provided with a first positioning hole formed by an inner hole of the inner ring of the cylinder (1), a second positioning hole formed by a cylindrical surface of the outer ring of the cylinder (1), and a first positioning shaft arranged on an axial first annular end surface of the cylinder (1), wherein the axis of the second positioning hole is perpendicular to the axis of the first positioning hole, and the axis of the first positioning shaft is parallel to the axis of the first positioning hole; a plurality of positioning bosses are arranged on an axial second annular end surface of the cylinder (1), and the plurality of positioning bosses are distributed on a circumference coaxial with the first positioning hole and extend along a direction parallel to the axis of the first positioning hole; A first positioning block (3) is provided with a first O-shaped groove and a plurality of positioning bosses on an axial first end surface of the first positioning block (3), wherein the plurality of positioning bosses are distributed on a circumference coaxial with the first positioning block (3), the first O-shaped groove is coaxial with the first positioning block (3) and has an inner diameter less than or equal to the diameter of the circumference where the plurality of positioning bosses are located, the positioning bosses extend along a direction parallel to the axis of the first positioning block (3), a second O-shaped groove is formed in the groove bottom surface of the first O-shaped groove, the second O-shaped groove is coaxial with the first O-shaped groove, and a second positioning shaft is arranged on the groove bottom surface of the first O-shaped groove other than the second O-shaped groove, wherein the axis of the second positioning shaft is parallel to the first positioning block (3); A second positioning block (4) is provided with a third positioning hole formed by an inner hole of the inner ring of the second positioning block (4), a fourth positioning hole formed by a cylindrical surface of the outer ring of the second positioning block (4), and a plurality of positioning bosses arranged on an axial first annular end surface of the second positioning block (4), wherein the axis of the fourth positioning hole is perpendicular to the axis of the third positioning hole, and the plurality of positioning bosses extend along a direction parallel to the axis of the third positioning hole; one of the plurality of positioning bosses is provided with a third positioning shaft, and the axis of the third positioning shaft is parallel to the axis of the third positioning hole; A positioning pin (2) is a stepped cylindrical shaft type pin, and the positioning pin (2) is detachably inserted into the second positioning hole and the fourth positioning hole.

2. The special welding positioning device for a straight pipe assembly of a ventilation box according to claim 1, wherein: the axial second annular end surface of the cylinder (1) is provided with a first positioning boss, a second positioning boss and a third positioning boss with a central angle of 120°; the axial first end surface of the first positioning block (3) is provided with a fourth positioning boss, a fifth positioning boss and a sixth positioning boss with a central angle of 120°; the axial first annular end surface of the second positioning block (4) is provided with a seventh positioning boss and an eighth positioning boss with a central angle of 180°, the seventh positioning boss is provided with the third positioning shaft, and the central angle between the seventh positioning boss and the fourth positioning hole is 90°.

3. A special welding positioning device for a straight duct assembly of a ventilation box according to claim 1, characterized in that: The cylinder (1), the first positioning block (3), the second positioning block (4) and the positioning pin (2) are made of H62 material.

4. A special welding positioning device for a straight duct assembly of a ventilation box according to claim 1, characterized in that: The positioning pin (2) comprises two cylindrical parts, one part is a smooth cylindrical body with a smaller outer diameter, and the other part is a cylindrical body with an anti-slip net pattern on the surface and a larger outer diameter.

5. A method of tack welding a plenum chamber straight tube assembly, characterized by: The special welding positioning device of claim 1 is used to implement steps one to four, wherein: Step one, the cylinder (1) is sleeved on the axial first end of the first straight pipe (5) through the first positioning hole, the cylinder (1) is rotated and translated until the second positioning hole is aligned with the hole position on the surface of the first straight pipe (5), then the positioning pin (2) is inserted into the second positioning hole until the positioning pin (2) enters the hole position on the surface of the first straight pipe (5), and then the small end cover (8) is sleeved on the first straight pipe (5) and positioned by the hole position of the small end cover (8) and the first positioning shaft of the cylinder (1), when the end face of the small end cover (8) is attached to the axial first annular end face of the cylinder (1), the welding of the first straight pipe (5) and the small end cover (8) is implemented; Step two, the positioning pin (2) is pulled out, the cylinder (1) is removed from the first straight pipe (5), the cylinder (1) is sleeved on the axial second end of the first straight pipe (5) again through the first positioning hole, and it is ensured that the positioning boss on the cylinder (1) points to the small end cover (8), the cylinder (1) is rotated and translated until the second positioning hole is aligned with the hole position on the surface of the first straight pipe (5), then the positioning pin (2) is inserted into the second positioning hole until the positioning pin (2) enters the hole position on the surface of the first straight pipe (5), at this time, the bracket is pressed tightly on the positioning boss of the cylinder (1) and abuts against the second annular end face, and the welding of the bracket on the surface of the first straight pipe (5) is implemented; Step three, the positioning pin (2) is pulled out, the cylinder (1) is removed from the first straight pipe (5), the second straight pipe (6) is sleeved on the outside of the first straight pipe (5) and it is ensured that the bracket is in good contact with the inner wall of the second straight pipe (6), the welding of the second straight pipe (6) and the small end cover (8) is implemented, the first positioning block (3) is sleeved on the small end cover (8) side of the first straight pipe (5), the positioning is realized by the cooperation of the second positioning shaft of the first positioning block (3) and the hole position on the small end cover (8), the first positioning block (3) is moved until the non-second O-shaped groove surface of the first O-shaped groove bottom surface of the first positioning block (3) is tightly attached to the surface of the small end cover (8), at this time, the bracket is pressed tightly on the positioning boss of the first positioning block (3) and abuts against the axial first end face of the first positioning block (3), and the welding of the bracket on the surface of the second straight pipe (6) is implemented; Step four, the first positioning block (3) is removed, the large end cover (9) is sleeved on the axial second end of the first straight pipe (5), then the second positioning block (4) is sleeved on the axial second end of the first straight pipe (5) through the third positioning hole, the second positioning block (4) is rotated and translated until the fourth positioning hole is aligned with the hole position on the surface of the first straight pipe (5), then the positioning pin (2) is inserted into the fourth positioning hole until the positioning pin (2) enters the hole position on the surface of the first straight pipe (5), the large end cover (9) is rotated and translated until the third positioning shaft on the second positioning block (4) enters the hole position on the large end cover (9), when the end face of the large end cover (9) is tightly attached to the end face of the positioning boss on the axial first annular end face of the second positioning block (4), the welding of the large end cover (9) and the first straight pipe (5) is implemented.

6. A method of tack welding a plenum chamber straight duct assembly according to claim 5 wherein: Also included is a step five, removing the second positioning block (4), sleeving the third straight pipe (7) outside the second straight pipe (6), and implementing welding of the third straight pipe (7) and the large end cover (9).

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