Welding process method for fuel header pipe

Abstract

The invention provides a welding process method of a fuel manifold. The welding process method comprises the following steps: polishing, reaming in groups, measuring holes at a to-be-welded part of a semi-ring, and recording a measured value; measuring the actual size of a to-be-welded hole of the oil inlet joint, and recording a measured value; measuring the actual size of a to-be-welded hole of the semi-ring assembly, and recording a measured value; according to the measurement result, the machining size of each matching part hole is given, it is guaranteed that the diameter gap between the matching part hole and the semi-ring is within 0.09-0.2 mm, a label is tied to each part, and the size machining range of each part matching hole is recorded on the label; reaming in groups according to the required size of the label; cutting a brazing sheet, drawing lines, presetting the brazing sheet, performing positioning spot welding and performing vacuum brazing. The method has the advantages that part welding gaps are well guaranteed, welding seam forming is good, the percent of pass of the fuel manifold assembly is remarkably improved, and economic benefits are greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of aviation engine welding, and in particular to a welding process method for a fuel main pipe. Background Art

[0002] The welding technology of the fuel manifold of an aircraft engine is one of the most complex technologies in engine manufacturing technology. The design requires the welding of the half ring of the fuel manifold with multiple tees. In traditional processing, the welding technology of the fuel manifold usually adopts argon arc welding positioning technology. Due to the limitations of process characteristics, there are many problems such as low welding efficiency, large weld points, oxidation at the weld points and difficulty in removal, affecting the flow of brazing material, low weld point strength, easy damage to the substrate, and poor welding quality. In addition, since the fuel manifold is a straight-side tee structure assembled with a bent pipe, and the chord drop of the bent pipe is large, the assembly gap is large, resulting in the flow of brazing material, insufficient filling of the brazing material in the conduit, extremely low X-ray inspection pass rate, and poor quality of the formed welding fillet. In addition, the production cycle of the repair welding process is long, and even scrapping occurs. Seriously affecting the delivery task of parts. Therefore, it is urgent to improve the existing process methods. Summary of the invention

[0003] The purpose of the present invention is to effectively ensure the welding qualification rate of the fuel main pipe assembly, break through the bottleneck that the welding quality of the conduit parts cannot be guaranteed, and effectively reduce the huge economic and manpower losses caused by the scrapping of parts due to unqualified welding of parts. A welding process method for a fuel main pipe is specially provided.

[0004] The present invention provides a welding process method for a fuel main pipe, comprising the following parts:

[0005] (1) Control of the surface condition of the parts to be welded

[0006] If there are impurities such as oil, carbon deposits, oxide film, etc. on the surface of the parts to be welded, the brazing filler metal will often condense into balls on the surface of the parts, making it difficult to wet the base of the parts, resulting in deterioration of the welding performance between the brazing filler metal and the parts. Before welding, the parts should be cleaned and polished with a special grinder. Not only the surface to be welded should be polished, but also the position 12 to 15 mm away from the welded part should be polished at the same time, which is more conducive to the wetting of the brazing filler metal. This grinding method not only removes the oxide film, but also improves the roughness of the part surface, which is more conducive to the capillary action of the brazing filler metal and improves the welding quality.

[0007] (2) Parts assembly clearance control

[0008] The assembly gap of parts directly affects the welding quality. If the gap is too large, the capillary effect will be weakened, causing the solder to flow. If the gap is too small, it will hinder the solder filling. The fuel main pipe is a straight-side tee structure assembled with an elbow, and the chord drop of the elbow is large, so the assembly gap cannot be guaranteed. The group reaming method is adopted to determine the optimal assembly gap through experiments, and the tolerance range of the corresponding accessories is obtained.

[0009] (3) Development of pre-setting solder method

[0010] Due to the inconsistent assembly gap of the fuel manifold assembly, the traditional coating method is difficult to meet the welding quality requirements. A coating scheme using foil strip solder sheets and paste solder is adopted. At the same time, the present invention clarifies the cutting requirements and presetting method of foil strip solder, as well as the key points of coating paste solder.

[0011] (4) Determination of part positioning method

[0012] The traditional argon arc welding positioning method has many problems, such as low welding efficiency, large weld spots, oxidation at the weld spots and difficulty in cleaning, affecting the flow of solder, low weld spot strength, easy damage to the substrate, poor welding quality, etc. The use of energy storage spot welding for positioning effectively solves the above problems, and the strength of the weld spots is well guaranteed.

[0013] (5) Determination of vacuum brazing temperature curve

[0014] (a) Determination of vacuum brazing temperature

[0015] Vacuum brazing temperature is one of the important factors affecting welding quality. When the temperature is low, the brazing material has not yet reached the required temperature, and the fluidity and wettability of the brazing material are poor, which is prone to defects such as internal pores in the brazing seam, discontinuity in the brazing seam, and cold welding, which reduces the strength of the brazed joint, causes leakage due to the pressure-bearing capacity not meeting the standard, and even tears in severe cases; when the temperature is high, the brazing material is completely melted and the fluidity is too large, which is prone to oxidation of the brazing material to form pores and poor capillary force on the weld, causing defects such as brazing material loss, melting, and product bending. Combined with the brazing material parameters, pay attention to the flow point of the brazing material to determine the optimal vacuum brazing temperature parameters. Make the liquid solder have good wettability and dispersion to the part matrix, can better fill the brazing gap under the action of capillary force, and can produce good alloying effect with the surface of the part to form a high-strength joint.

[0016] (b) Determination of holding time

[0017] Based on the structural size characteristics of the fuel main pipe, the time required for the core temperature of the product to be brazed to reach the brazing temperature and the time required for the oxide film to dissipate are evaluated, and the optimal insulation time is determined, effectively avoiding the problems of matrix dissolution and insufficient melting of the brazing material.

[0018] A welding process method for a fuel main pipe, characterized in that it includes the following contents:

[0019] (1) Polishing

[0020] Operation steps: Use a grinder or 240# sandpaper to grind the surface of the parts to be welded and the surrounding area by 12 to 15 mm. The surface of the parts to be welded should show metallic luster after grinding;

[0021] (2) Group reaming

[0022] (a) Measure the hole of the half ring to be welded and record the measured value;

[0023] (b) Measure the actual size of the hole to be welded at the oil inlet joint and record the measured value;

[0024] (c) Measure the actual size of the hole to be welded in the half-ring assembly and record the measured value;

[0025] (d) Based on the above measurement results, the machining dimensions of each mating part hole are given to ensure that the tightness with the half ring is within the range of 0.09 to 0.2 mm of diameter clearance, and a label is attached to each part, recording the machining range of the dimension of each part mating hole on the label;

[0026] (e) Ream holes in groups according to the dimensions required by the label;

[0027] (2) Cutting solder sheets

[0028] According to the characteristics of the welding part of the fuel main pipe and the flow of the brazing sheet into the furnace, the brazing sheet is cut;

[0029] (3) Line drawing

[0030] Mark and draw a line on the center line of the half ring assembly in the vertical direction of the hole;

[0031] For half rings, score both sides of each hole;

[0032] (4) Pre-set solder sheet

[0033] For the half-ring assembly: pre-set the cut solder sheet with holes on the half-ring assembly, the holes on the solder sheet should coincide with the holes on the inner circle of the part, and the solder sheet is not allowed to cover the inner hole;

[0034] For the oil inlet joint: pre-place the cut solder sheet without holes at the oil inlet joint, pre-place from both sides, and pre-place 2 solder sheets;

[0035] (5) Positioning spot welding

[0036] (a) Spot weld 4 to 6 points along the circumference;

[0037] (b) After spot welding on the fixture, the parts are disassembled for reinforcement spot welding, with no less than 6 welding points on each part;

[0038] (6) Vacuum brazing

[0039] Heat to 550±10℃ at a rate of 8~12℃ / min, and keep warm for 10~20min; heat to 940±10℃ at a rate of 8~12℃ / min, and keep warm for 15~30min; heat to 1040±10℃ at a rate of 5~10℃ / min, and keep warm for 8~12min; during the whole heating, heat preservation and brazing process, the vacuum pressure shall not exceed 4×10 -2 Pa; After the parts are cooled to 900℃ with the furnace, they are cooled quickly and filled with argon gas at a pressure of 1 bar. The parts can be taken out below 80℃.

[0040] This invention abandons the traditional argon arc welding technology, adopts energy storage spot welding for positioning, and vacuum brazing for welding. In this invention, the surface state of the parts before welding, assembly gap and other key points are strictly controlled, the winding position of the foil strip brazing sheet and the coating method of the paste brazing material are clarified, and the vacuum brazing temperature curve of the parts is determined. After adopting the present invention, the welding qualification rate of the fuel main pipe is significantly improved.

[0041] Compared with the prior art, the present invention has the following advantages:

[0042] The welding process method of the fuel manifold of the present invention can ensure good welding gap between parts, form good weld seams, and significantly improve the qualified rate of fuel manifold components. It can reduce the loss of waste products by millions of yuan each year, and with the promotion and application of the process method, the economic benefits will be greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments:

[0044] Figure 1 Schematic diagram of the polishing part;

[0045] Figure 2 This is a schematic diagram of the measurement dimensions;

[0046] Figure 3 It is a schematic diagram of cutting solder sheet;

[0047] Figure 4 It is a schematic diagram of the position of the drawing line;

[0048] Figure 5 It is a schematic diagram of the position of the pre-set solder sheet;

[0049] Figure 6 Schematic diagram of the positioning spot welding position. DETAILED DESCRIPTION

[0050] The present invention will be further explained below in conjunction with specific implementation plans, but the present invention is not limited thereto. The structures, proportions, sizes, etc. illustrated in the drawings of the specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the restrictive conditions under which the present invention can be implemented. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0051] (1) Polishing

[0052] Operation steps: Use a grinder or 240# sandpaper to grind the surface of the part to be welded and the surrounding area (12~15) mm. The surface of the part to be welded should show metallic luster after grinding. Grinding with abrasives containing aluminum oxide is not allowed. Figure 1 shown.

[0053] (2) Group reaming

[0054] (a) 100% measure the actual dimensions of the outer circles ΦA and ΦC on both sides of the semi-ring holes to be welded (9 in total) and the outer circles ΦA at both pipe ends, and record the measured values.

[0055] (b) 100% measure the actual size of the hole ΦD at the oil inlet joint to be welded and record the measured value.

[0056] (c) 100% measure the actual size of the hole ΦE of the half-ring assembly to be welded and record the measured value.

[0057] (d) Based on the above measurement results, the processing dimensions of each mating part hole are given to ensure that the tightness with the half ring is within the range of 0.09 to 0.2 of the diameter gap, and a label is attached to each part, recording the size machining range of each part's mating hole on the label.

[0058] (e) Ream holes in groups according to the size required by the label. Figure 2 shown.

[0059] (2) Cutting solder sheets

[0060] According to the characteristics of the welding part of the fuel main pipe and the flow of the solder sheet into the furnace, the present invention cuts the solder sheet in the following manner. Figure 3 shown.

[0061] (3) Line drawing

[0062] Mark and draw a line on the A side of the half ring assembly along the center line of the hole in the vertical direction.

[0063] For the half ring (1), draw lines on both sides of each hole according to the size ①; (2) draw a line along the center line of the elbow through the center of the hole and intersect with the line in (1). Figure 4 shown.

[0064] (4) Pre-set solder sheet

[0065] For the half-ring assembly: pre-set the cut solder sheet with holes at the position shown in the diagram of the half-ring assembly. The holes on the solder sheet should coincide with the holes on the inner circle of the part. The solder sheet is not allowed to block the inner hole.

[0066] For the oil inlet joint: pre-place the cut solder sheet without holes at the position shown in the diagram of the oil inlet joint, pre-place from both sides, and pre-place 2 solder sheets. Figure 5 shown.

[0067] (5) Positioning spot welding

[0068] (a) Spot weld 4 to 6 points along the circumference as shown in the figure.

[0069] (b) After spot welding on the fixture, the parts are disassembled for reinforcement spot welding. There should be no less than 6 welding points on each part.

[0070] like Figure 6 shown.

[0071] (6) Vacuum brazing

[0072] The invention requires heating to (550±10)℃ at a rate of (8~12)℃ / min and keeping warm for (10~20)min; heating to (940±10)℃ at a rate of (8~12)℃ / min and keeping warm for (15~30)min; heating to (1040±10)℃ at a rate of (5~10)℃ / min and keeping warm for (8~12)min; during the whole heating, keeping warm and brazing process, the vacuum pressure is not more than 4×10 -2 Pa. After the parts are cooled to 900℃ with the furnace, they are quickly cooled and filled with argon gas at a pressure of 1 bar. The parts can be taken out below 80℃.

[0073] Matters not covered by the present invention are known technologies.

[0074] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A welding process for a fuel main pipe, characterized in that: Includes the following: (1) Polishing Operation steps: Use a grinder or 240# sandpaper to grind the surface of the parts to be welded and the surrounding area by 12 to 15 mm. The surface of the parts to be welded should show metallic luster after grinding; (2) Group reaming (a) Measure the hole of the half ring to be welded and record the measured value; (b) Measure the actual size of the hole to be welded at the oil inlet joint and record the measured value; (c) Measure the actual size of the hole to be welded in the half-ring assembly and record the measured value; (d) Based on the above measurement results, the machining dimensions of each mating part hole are given to ensure that the tightness with the half ring is within the range of 0.09 to 0.2 mm of diameter clearance, and a label is attached to each part, recording the machining range of the dimension of each part mating hole on the label; (e) Ream holes in groups according to the dimensions required by the label; (2) Cutting solder sheets According to the characteristics of the welding part of the fuel main pipe and the flow of the brazing sheet into the furnace, the brazing sheet is cut; (3) Line drawing Mark and draw a line on the center line of the half ring assembly in the vertical direction of the hole; For half rings, score each hole on both sides; (4) Pre-set solder sheet For the half-ring assembly: pre-set the cut solder sheet with holes on the half-ring assembly, the holes on the solder sheet should coincide with the holes on the inner circle of the part, and the solder sheet is not allowed to cover the inner hole; For the oil inlet joint: pre-place the cut solder sheet without holes at the oil inlet joint, pre-place from both sides, and pre-place 2 solder sheets; (5) Positioning spot welding (a) Spot weld 4 to 6 points along the circumference; (b) After spot welding on the fixture, the parts are disassembled for reinforcement spot welding, with no less than 6 welding points on each part; (6) Vacuum brazing Raise the temperature to 550±10℃ at a rate of 8~12℃ / min, and keep warm for 10~20min; raise the temperature to 940±10℃ at a rate of 8~12℃ / min, and keep warm for 15~30min; then raise the temperature to 1 040±10℃ at a rate of 5~10℃ / min, and keep warm for 8~12min; During the whole process of heating, heat preservation and brazing, the vacuum pressure is not more than 4×10 -2 Pa; After the parts are cooled to 900℃ with the furnace, they are cooled quickly and filled with argon gas at a pressure of 1 bar. The parts can be taken out below 80℃.

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