Engine frame welding frame and use method

Abstract

The present invention belongs to the field of aerospace engine technology, and is particularly concerned with an engine frame welding jig and a method for using the same. The engine frame welding jig comprises an assembly welding platform, a frame small-end positioning bracket, a plurality of large-end joint positioning seats, a plurality of servo mechanism joint positioners, and a plurality of main columns. The assembly welding platform is processed with a plurality of connection grooves. Each group of connection grooves comprises a plurality of T-slots, which are open on the side and upper end surfaces of the assembly welding platform and extend from the side toward the middle of the assembly welding platform. The main columns, the large-end joint positioning seats, and the servo mechanism joint positioners are all fixedly connected to the assembly welding platform, and the main columns, the large-end joint positioning seats, and the servo mechanism joint positioners can all be adjusted along the T-slots so as to be closer to or farther from the middle of the assembly welding platform. The frame small-end positioning bracket is fixedly mounted on the plurality of main columns. The jig adopts a modular design concept, has strong versatility, is easy to use, and has high welding quality.

Description

Technical Field

[0001] The invention belongs to the technical field of aerospace engines, and in particular to an engine frame welding jig and a use method thereof. Background Art

[0002] The rocket engine frame is a crucial component of the rocket engine structure, securing the connection between the rocket engine and the rocket body. The existing engine frame welding jig had no fixed structure or method of use. It relied on traditional marking and positioning, resulting in poor positioning accuracy and insufficient overall rigidity. This required sufficient machining allowance at each locating end of the frame to meet docking requirements, making it suitable only for spatial positioning and welding of small-volume, small-scale engine frames. With the advancement of aerospace and rocket engine technology, the existing frame welding method was no longer able to meet mission requirements. Summary of the Invention

[0003] The technical problem to be solved by this invention is to overcome the above-mentioned shortcomings of the prior art and provide an engine frame welding jig and its use method with strong structural versatility, good installation performance, high strength, and long service life. This frame welding jig and its corresponding use method improve the welding quality and efficiency of the engine frame.

[0004] In order to solve the above technical problems, the technical solution of the present invention is:

[0005] An engine frame welding jig includes an assembly welding platform, a frame small end positioning bracket, a plurality of large end joint positioning seats, a plurality of servo mechanism joint positioners and a plurality of main columns;

[0006] The assembly welding platform is processed with multiple groups of connection grooves; each group of the connection grooves includes a plurality of T-shaped grooves, the T-shaped grooves are open on the side and upper end surface of the assembly welding platform, and extend from the side to the middle of the assembly welding platform;

[0007] The main column, the large end joint positioning seat, and the servo mechanism joint positioner are all fixedly connected to the assembly welding platform by T-shaped bolts and T-shaped slots. The main column, the large end joint positioning seat, and the servo mechanism joint positioner can be adjusted along the T-shaped slots to move closer to or away from the middle of the assembly welding platform.

[0008] The small-end positioning bracket of the rack is fixedly installed on a plurality of main columns.

[0009] In the above-mentioned engine frame welding jig, each group of connecting grooves includes two T-shaped grooves, and the two T-shaped grooves are parallel to each other.

[0010] In the above-mentioned engine frame welding jig, the large end joint positioning seat includes a base, a slider and a stop pin assembly;

[0011] The base is machined with a plurality of second U-shaped grooves, and the base is connected to the assembly welding platform by using T-shaped bolts, the second U-shaped grooves and the T-shaped grooves; a V-shaped groove is provided on the upper side of the base, and two pin holes are machined on the bottom surface of the V-shaped groove;

[0012] The stop pin assembly includes two pin shafts, and the two pin shafts are respectively installed in the two pin holes;

[0013] The slider is slidably mounted in the V-shaped groove and can move closer to or farther from the middle of the assembly welding platform; the slider is located on one side of the pin shaft facing the middle of the assembly welding platform.

[0014] In the above-mentioned engine frame welding jig, the slider is provided with two assembly measurement reference holes, and the connecting line of the two assembly measurement reference holes and the center line of the V-shaped groove are in the same plane.

[0015] In the above-mentioned engine frame welding jig, a flat section is processed on the outer side wall of the pin shaft, and the flat section is parallel to the axis of the pin shaft.

[0016] In the above-mentioned engine frame welding jig, the servo mechanism joint positioner includes a servo lower positioning seat, a servo upper positioning seat and a positioning shaft;

[0017] The bottom of the servo lower positioning seat is processed with a plurality of first U-shaped grooves for cooperating with the T-shaped grooves, and the servo lower positioning seat and the assembly welding platform are fixedly connected by T-shaped bolts;

[0018] The servo upper positioning seat is fixedly mounted on the servo lower positioning seat;

[0019] The positioning shaft is fixedly mounted on the servo upper positioning seat, and a slot is provided at one end of the positioning shaft to position the engine frame servo joint; an external thread is provided at the end of the positioning shaft away from the servo upper positioning seat, and a nut is used to cooperate with the external thread to limit the axial displacement of the engine frame servo joint.

[0020] In the above-mentioned engine frame welding frame, the main column includes a lower connecting seat and a support seat;

[0021] The bottom of the lower connecting seat is processed with a plurality of third U-shaped grooves, and the third U-shaped grooves, T-shaped grooves and T-shaped bolts are used in conjunction with each other to connect and fix the lower connecting seat to the assembly welding platform;

[0022] The support is fixed on the upper end of the lower connecting seat; and the small end positioning bracket of the frame is fixedly installed on the support.

[0023] The method for using the engine frame welding frame includes the following steps:

[0024] Step 1: Install the big end connector locating seat;

[0025] After determining the position of each large end joint locating seat according to the design requirements, tighten and assemble the welding platform and the large end joint locating seat;

[0026] After tightening, process the positioning cone holes of the large end joint positioning seat and the assembly welding platform and insert the conical pins to ensure that the relative positions remain unchanged;

[0027] Step 2: Install the main column;

[0028] Using the large end joint positioning seat as a reference, determine the position of the main column and then fasten the main column and the assembly welding platform;

[0029] After tightening, process the positioning taper holes of the main column and the assembly welding platform, as well as the positioning taper holes of the lower connecting seat and the support, and insert conical pins to ensure that the relative positions remain unchanged;

[0030] Step 3: Install the small end positioning bracket of the rack;

[0031] Install the small end positioning bracket of the rack on the main column and complete the fastening of the small end positioning bracket of the rack;

[0032] Step 4: Install the servo mechanism joint positioner;

[0033] Assemble the servo mechanism joint positioner, install the servo upper positioning seat onto the servo lower positioning seat and tighten it, install the positioning shaft onto the servo upper positioning seat and tighten it;

[0034] After the assembly is completed, the servo mechanism joint positioner is moved to the assembly welding platform, and the position of the servo mechanism joint positioner on the assembly welding platform is adjusted and tightened;

[0035] Adjust the servo lower locating seat and locating shaft to the design requirements, then machine the locating tapered holes of the servo lower locating seat and the assembly welding platform, as well as the locating tapered holes of the servo upper locating seat and the locating shaft, and insert conical pins to ensure that the relative positions remain unchanged;

[0036] Step 5: Weld the engine frame;

[0037] Fix the big end joint, small end joint and servo joint of the engine frame respectively on the big end joint positioning seat, the frame small end positioning bracket and the servo mechanism joint positioner;

[0038] After the fixation is completed, the connecting pipes of the engine frame are repaired and the engine frame is welded.

[0039] In the above usage,

[0040] When positioning the small end joint of the engine frame before welding, insert a pad between the contact surface of the main column and the small end positioning bracket of the frame. After the engine frame welding is completed, remove the pad to release the frame welding shrinkage stress.

[0041] Before welding the frame, the cylindrical surface of the pin is pressed against the slider to achieve precise positioning of the large end joint of the engine frame; after welding, the pin is rotated so that its flat surface faces the slider to release the frame welding shrinkage stress.

[0042] In the above-mentioned method of use, in the step of installing the main columns, the two centripetal assembly measurement reference holes of one of the large-end joint positioning seats are used as a reference, and the connection line of the two main columns used to fasten the small-end positioning bracket of the rack coincides with the connection line of the two centripetal assembly measurement reference holes of the large-end joint positioning seat.

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] 1) This engine frame welding frame has good structural versatility;

[0045] For the positioning welding of engine frames of different models and sizes, it is only necessary to make corresponding adjustments to the components of the frame hook according to the actual situation, that is, adjust the positions of the frame small end positioning bracket, multiple large end joint positioning seats, and multiple servo mechanism joint positioners to meet the needs.

[0046] 2) The engine frame welding frame adopts modular design concept;

[0047] The supporting components and positioning components of each part of the engine frame welding frame are all connected by a combination of bolts and conical pin positioning. Therefore, for the frame design of models with small differences in engine frame height, the supporting components of the corresponding parts can be shared, and only the positioning components need to be designed.

[0048] 3) All components of the engine frame welding frame are castings, which greatly improves the structural strength and rigidity, and can meet the welding needs of large-scale and large-size engine frames.

[0049] 4) The large end joint positioning seat of the engine frame welding frame adopts a V-groove and stop pin assembly structure. This structure can not only meet the guide adjustment function, but also release the welding shrinkage stress of the engine frame in the V-groove guide direction by rotating the stop pin assembly after the frame welding is completed, while suppressing the deformation of the engine frame welding in other directions, effectively improving the weld quality and reducing technical risks and manufacturing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a structural diagram of the welding jig of the engine frame;

[0051] Figure 2 It is a structural diagram of the large end joint positioning seat;

[0052] Figure 3 It is a structural diagram of the servo mechanism joint positioner;

[0053] Figure 4 Schematic diagram of the structure of the main column.

[0054] In the picture:

[0055] 1-Assembly welding platform; 11-T-slot; 12-Center positioning hole;

[0056] 2-large end joint positioning seat; 21-base; 22-slider; 23-assembly measurement reference hole; 24-stop pin assembly; 25-V-shaped groove; 26-second U-shaped groove;

[0057] 3-Servo mechanism joint positioner; 31-Servo lower positioning seat; 32-Positioning shaft; 33-Servo upper positioning seat; 34-First U-shaped groove;

[0058] 4- rack small end positioning bracket;

[0059] 5-Large nut;

[0060] 6-main column; 61-lower connecting seat; 62-support; 63-third U-shaped groove. DETAILED DESCRIPTION

[0061] The present invention will be further described below in conjunction with the embodiments.

[0062] The present invention provides an engine frame welding frame and a method of use, such as Figure 1 As shown, the engine frame welding jig includes an assembly welding platform 1, a large-end joint locator 2, a servo mechanism joint positioner 3, a frame small-end positioning bracket 4, and a main column 6. The assembly welding platform 1 serves as a positioning and installation base for the large-end joint locator 2, the servo mechanism joint positioner 3, the frame small-end positioning bracket 4, and the main column 6. The large-end joint locator 2 is used to position and secure the engine frame's large-end joint; the servo mechanism joint positioner 3 is used to position and secure the engine frame's servo mechanism joint; the frame small-end positioning bracket 4 is used to position and secure the engine frame's small-end joint; and the main column 6 is used to position and secure the frame small-end positioning bracket 4. Large nuts 5 securely connect the frame small-end positioning bracket 4 to the main column 6. Once all these components are positioned, installed, and secured according to design requirements, the frame can be welded.

[0063] The assembly welding platform 1 is preferably a casting, disc-shaped; its upper end face has a certain flatness after processing, which meets the flatness requirements of use. A center positioning hole 12 and multiple groups of connecting grooves are processed on the assembly welding platform 1; the center positioning hole 12 is located in the middle of the assembly welding platform 1, serving as the assembly reference for the large-end joint positioning seat 2, the servo mechanism joint locator 3, the frame small-end positioning bracket 4, and the main column 6. Similarly, structures such as positioning shafts can also be processed on the assembly welding platform 1 to serve as positioning references. Each group of connecting grooves includes a number of T-slots 11, which are open on the side and upper end faces of the assembly welding platform 1 and extend from the side to the interior of the assembly welding platform 1. The number of T-slots 11 included in each set of connecting grooves can be set according to actual needs. The main column 6, the large-end joint positioning seat 2, and the servo mechanism joint positioner 3 cooperate with the T-slots 11 via T-bolts to achieve a fixed connection. The provision of the T-slots 11 allows the main column 6, the large-end joint positioning seat 2, and the servo mechanism joint positioner 3 installed therein to be adjusted in position along the radial direction of the center positioning hole 12. For example, when a set of connecting grooves includes one T-slot 11, the T-slot 11 extends radially along the center positioning hole 12; when a set of connecting grooves includes two T-slots 11, the two T-slots 11 are parallel to each other, and the centerline between the two T-slots 11 extends radially along the center positioning hole 12; similarly, when a set of connecting grooves includes three or more T-slots 11, their centerlines extend radially along the center positioning hole 12.

[0064] like Figure 2 As shown, the big end joint positioning seat 2 includes three parts: a base 21, a slider 22 and a stop pin assembly 24.

[0065] The base 21 is a casting made of QT450-10. Multiple second U-shaped grooves 26 are machined into the base 21. T-bolts, the second U-shaped grooves 26, and the T-shaped grooves 11 cooperate to achieve a removable connection between the base 21 and the assembly welding platform 1. A V-shaped groove 25 is provided in the base 21, extending radially from the center positioning hole 12. Two pin holes are machined into the bottom surface of the V-shaped groove 25. The retaining pin assembly 24 includes two pin shafts, each mounted in one of the two pin holes.

[0066] The material of the slider 22 can be selected from 45 steel. The slider 22 is slidably installed in the V-groove 25 and is located on the side of the pin facing the center positioning hole 12. After the base 21 and the slider 22 are assembled, the slider 22 can slide relative to the base 21 along the radial direction of the center positioning hole 12, and the lateral shaking is small.

[0067] The outer wall of the pin is machined with a flat surface parallel to the pin's axis; the distance between the flat surface and the pin's axis can be adjusted according to positioning requirements. When welding the engine frame, the cylindrical surface of the pin of the retaining pin assembly 24 contacts the slider 22 for welding and positioning. After welding is completed, the pin is rotated to align the flat surface with the end face of the slider 22, allowing the engine frame to contract freely to release welding stress until it contacts the flat surface of the pin.

[0068] The upper side of the slider 22 is machined with several connection holes for connecting to the large end connector of the engine frame. In the assembled state, two assembly measurement reference holes 23 are drilled in the base 21 and slider 22. The line connecting the two assembly measurement reference holes 23 and the centerline of the V-shaped groove 25 are in the same plane.

[0069] like Figure 3 As shown, the servo mechanism joint locator 3 includes a servo lower positioning seat 31, a servo upper positioning seat 33 and a positioning shaft 32. The servo lower positioning seat 31 mainly plays a supporting role, the servo upper positioning seat 33 mainly plays a guiding and positioning role, and the positioning shaft 32 is used to position and fix the frame servo mechanism joint. The bottom of the servo lower positioning seat 31 is processed with multiple first U-shaped grooves 34 to facilitate cooperation with the T-shaped slots 11 of the assembly welding platform 1, and is installed, adjusted and connected and fixed by T-shaped bolts. The servo upper positioning seat 33 is fixedly mounted on the servo lower positioning seat 31 through bolts and other connecting parts. In order to facilitate processing, the servo lower positioning seat 31 and the servo upper positioning seat 33 are both cast. The positioning shaft 32 is fixedly mounted on the servo upper positioning seat 33. The positioning shaft 32 extends horizontally, and a slot is processed at one end of the positioning shaft 32 to position the frame servo joint; the end of the positioning shaft 32 away from the servo upper positioning seat 33 is provided with an external thread, which is tightened with a nut to limit the axial displacement of the engine frame servo joint.

[0070] like Figure 4 As shown, the main column 6 consists of a lower connecting base 61 and a support 62. The lower connecting base 61 primarily serves as a support, with multiple third U-shaped grooves 63 machined into its bottom. These third U-shaped grooves 63, T-shaped slots 11, and T-bolts work together to facilitate the installation, adjustment, and connection of the lower connecting base 61 to the assembly welding platform 1. The support 62 is fixed to the upper end of the lower connecting base 61 by bolts, and the relative position is ensured by two locating pins.

[0071] like Figure 1As shown, the frame small end positioning bracket 4 is installed on the main column 6. Three circular holes and one oblong hole are machined on the four ends of the frame small end positioning bracket 4. The line connecting the centers of the diagonal holes is required to be orthogonal and pass through the center of the center hole of the frame small end positioning bracket 4. The oblong hole is machined to prevent the frame small end positioning bracket 4 from being over-positioned. Two supports 62 of the four main columns 6 are cylindrical and include an optical axis section and a threaded section. The optical axis section is used to position the frame small end positioning bracket 4. The threaded section cooperates with the large nut 5 to fix the frame small end positioning bracket 4. The remaining two main columns 6 only serve to support and connect the frame small end positioning bracket 4. Several connecting slots are also machined on the frame small end positioning bracket 4. The size and shape of the connecting slots are adapted to the appearance of the engine frame small end connector and are used to position the engine frame small end connector.

[0072] The method for using the above-mentioned engine frame welding jig comprises the following steps:

[0073] Step 1: Install the large end connector positioning seat 2;

[0074] Use the upper end surface of the assembly welding platform 1 and the central positioning hole 12 as the installation positioning reference for the large end joint positioning seat 2. After determining the position of each large end joint positioning seat 2 according to the design requirements, tighten the bolts of the assembly welding platform 1 and the large end joint positioning seat 2.

[0075] After the fastening is completed, the positioning tapered holes of the large end joint positioning seat 2 and the assembly welding platform 1 are processed, and the tapered pins are inserted to ensure that the relative positions remain unchanged.

[0076] Step 2: Install the main column 6;

[0077] Using the two centripetal assembly measurement reference holes 23 on the slider 22 and the threaded holes connected to the large end of the frame as reference, position and install the main column 6, ensuring that the line connecting the two large nuts 5 of the main column 6 passes through the threaded holes connected to the large end of the frame and coincides with the line connecting the two centripetal assembly measurement reference holes 23 on a set of sliders 22; after determining the position of the main column 6, tighten the bolts of the assembly welding platform 1 and the main column 6;

[0078] After the fastening is completed, the positioning tapered holes of the main column 6 and the assembly welding platform 1 and the positioning tapered holes of the lower connecting seat 61 and the support 62 are processed, and conical pins are inserted into the corresponding ones to ensure that the relative positions remain unchanged.

[0079] Step 3: Install the small end positioning bracket 4 of the rack;

[0080] Lift the four lifting rings of the small end positioning bracket 4 of the frame and install it on the main column 6 that has been positioned and fixed. Install the bolts that fasten the small end positioning bracket 4 of the frame and the main column 6, and install two large nuts 5 to fasten the small end positioning bracket 4 of the frame.

[0081] Step 4: Install the servo mechanism joint positioner 3;

[0082] Assemble the servo mechanism joint positioner 3 and tighten the connecting bolts between the servo lower positioning seat 31 and the servo upper positioning seat 33; insert the positioning shaft 32 into the servo upper positioning seat 33 and lock it with the set screw;

[0083] Move the assembled servo mechanism joint positioner 3 to the assembly welding platform 1; adjust the position of the servo mechanism joint positioner 3 on the assembly welding platform 1 and the servo lower positioning seat 31 and the positioning shaft 32. After meeting the design requirements, lock the positioning shaft 32 with a set screw, and drill the threaded holes and positioning tapered holes between the servo lower positioning seat 31 and the assembly welding platform 1, the servo lower positioning seat 31 and the servo upper positioning seat 33, and the servo upper positioning seat 33 and the positioning shaft 32. Insert the conical pins and tighten the connecting bolts to ensure that their relative positions remain unchanged.

[0084] Step 5: Weld the engine frame;

[0085] After all the components are installed in place according to the design requirements, the large-end joint, small-end joint and servo mechanism of the frame can be fixed on the frame welding frame, and then the connecting pipes can be repaired and the frame can be welded into shape; before the frame is welded, the cylindrical surface of the pin shaft of the stop pin assembly 24 is against the slider 22. After the welding is completed, the pin shaft is rotated so that its flat surface is facing the slider 22; when positioning before welding the small end of the frame, a pad should be inserted into the contact surface between the main column 6 and the frame small end positioning bracket 4. After the frame welding is completed, the pad will be removed to release the frame welding shrinkage stress and improve the weld quality.

[0086] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the scope of protection of the technical solutions of the present invention.

Claims

1. An engine frame welding jig, characterized by: It comprises an assembly welding platform (1), a frame small end positioning bracket (4), a plurality of large end joint positioning seats (2), a plurality of servo mechanism joint positioners (3) and a plurality of main columns (6); The assembly welding platform (1) is processed with multiple groups of connection grooves; each group of the connection grooves includes a plurality of T-shaped grooves (11), and the T-shaped grooves (11) are open on the side and upper end surface of the assembly welding platform (1) and extend from the side to the middle of the assembly welding platform (1); The main column (6), the large end joint positioning seat (2), and the servo mechanism joint positioner (3) are all matched with the T-shaped slot (11) through T-shaped bolts to achieve fixed connection with the assembly welding platform (1). The main column (6), the large end joint positioning seat (2), and the servo mechanism joint positioner (3) can all be adjusted along the T-shaped slot (11) to approach or move away from the middle of the assembly welding platform (1); The small-end positioning bracket (4) of the frame is fixedly mounted on a plurality of main columns (6); The large end joint positioning seat (2) comprises a base (21), a slider (22) and a stop pin assembly (24); The base (21) is machined with a plurality of second U-shaped grooves (26), and the base (21) is connected to the assembly welding platform (1) by using T-shaped bolts, the second U-shaped grooves (26) and the T-shaped grooves (11); a V-shaped groove (25) is provided on the upper side of the base (21), and two pin holes are machined on the bottom surface of the V-shaped groove (25); The stop pin assembly (24) includes two pin shafts, and the two pin shafts are respectively installed in the two pin holes; The slider (22) is slidably mounted in the V-shaped groove (25) and can be moved closer to or farther from the middle of the assembly welding platform (1); the slider (22) is located on the side of the pin facing the middle of the assembly welding platform (1); A flat section is processed on the outer side wall of the pin shaft, and the flat section is parallel to the axis of the pin shaft.

2. The engine frame welding jig according to claim 1, characterized in that: Each group of connecting grooves comprises two T-shaped grooves (11), and the two T-shaped grooves (11) are parallel to each other.

3. The engine frame welding jig according to claim 1, characterized in that: The slider (22) is provided with two assembly measurement reference holes (23), and the connecting line of the two assembly measurement reference holes (23) and the center line of the V-shaped groove (25) are in the same plane.

4. The engine frame welding jig according to claim 1, characterized in that: The servo mechanism joint positioner (3) comprises a servo lower positioning seat (31), a servo upper positioning seat (33) and a positioning shaft (32); The bottom of the servo lower positioning seat (31) is processed with a plurality of first U-shaped grooves (34) for cooperating with the T-shaped grooves (11) and fixing the servo lower positioning seat (31) and the assembly welding platform (1) with T-shaped bolts; The servo upper positioning seat (33) is fixedly mounted on the servo lower positioning seat (31); The positioning shaft (32) is fixedly mounted on the servo upper positioning seat (33), and a slot is provided at one end of the positioning shaft (32) to position the engine frame servo joint; an external thread is provided at one end of the positioning shaft (32) away from the servo upper positioning seat (33), and a nut is used to cooperate with the external thread to limit the axial displacement of the engine frame servo joint.

5. The engine frame welding jig according to claim 1, characterized in that: The main column (6) includes a lower connecting seat (61) and a support seat (62); The bottom of the lower connecting seat (61) is processed with a plurality of third U-shaped grooves (63), and the third U-shaped grooves (63), T-shaped grooves (11) and T-shaped bolts are used in conjunction with each other to connect and fix the lower connecting seat (61) to the assembly welding platform (1); The support (62) is fixed to the upper end of the lower connecting seat (61); and the small end positioning bracket (4) of the frame is fixedly installed on the support (62).

6. The method for using the engine frame welding jig according to any one of claims 1 to 5, characterized in that: The following steps are included: Step 1: Install the large end connector locating seat (2); After determining the position of each large end joint positioning seat (2) according to the design requirements, the welding platform (1) and the large end joint positioning seat (2) are fastened and assembled; After the fastening is completed, the positioning taper holes of the large end joint positioning seat (2) and the assembly welding platform (1) are processed and the taper pins are inserted to ensure that the relative positions remain unchanged; Step 2: Install the main column (6); After determining the position of the main column (6) with the large end joint positioning seat (2) as a reference, the main column (6) and the assembly welding platform (1) are fastened; After the fastening is completed, the positioning taper holes of the main column (6) and the assembly welding platform (1) and the positioning taper holes of the lower connecting seat (61) and the support (62) are processed and conical pins are inserted to ensure that the relative positions remain unchanged; Step 3: Install the small end positioning bracket (4) of the rack; Install the small end positioning bracket (4) of the rack on the main column (6) and complete the fastening of the small end positioning bracket (4) of the rack; Step 4: Install the servo mechanism joint positioner (3); Assemble the servo mechanism joint positioner (3), install the servo upper positioning seat (33) on the servo lower positioning seat (31) and tighten it, and install the positioning shaft (32) on the servo upper positioning seat (33) and tighten it; After the assembly is completed, the servo mechanism joint positioner (3) is moved to the assembly welding platform (1), and the position of the servo mechanism joint positioner (3) on the assembly welding platform (1) is adjusted and tightened; Adjust the servo lower positioning seat (31) and the positioning shaft (32) to the design requirements, then process the positioning taper holes of the servo lower positioning seat (31) and the assembly welding platform (1) as well as the positioning taper holes of the servo upper positioning seat (33) and the positioning shaft (32) and insert conical pins to ensure that the relative positions remain unchanged; Step 5: Weld the engine frame; The big end joint, small end joint and servo joint of the engine frame are respectively fixed on the big end joint positioning seat (2), the frame small end positioning bracket (4) and the servo mechanism joint positioner (3); After the fixation is completed, the connecting pipes of the engine frame are repaired and the engine frame is welded.

7. The method of use according to claim 6, characterized in that: When positioning the small end joint of the engine frame before welding, insert a pad between the contact surface of the main column (6) and the frame small end positioning bracket (4), and remove the pad after the engine frame welding is completed to release the frame welding shrinkage stress; Before the frame is welded, the cylindrical surface of the pin is used to abut against the slider (22) to achieve accurate positioning of the large end joint of the engine frame; after welding is completed, the pin is rotated so that its flat section faces the slider (22) to release the frame welding shrinkage stress.

8. The method of use according to claim 7, characterized in that: In the step of installing the main columns (6), the two centripetal assembly measurement reference holes (23) of one of the large end joint positioning seats (2) are used as a reference, and the connection line of the two main columns (6) for fastening the small end positioning bracket (4) of the frame coincides with the connection line of the two centripetal assembly measurement reference holes (23) of the large end joint positioning seat (2).

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