CN115846844A - Method for improving batch welding size precision of split diffusion welding parts - Google Patents
Method for improving batch welding size precision of split diffusion welding parts Download PDFInfo
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Abstract
The invention relates to a method for improving the batch welding size precision of split diffusion welding parts, which comprises the following steps: preparing a to-be-welded part; step two: preparing a process base plate; compared with TC4 alloy to-be-welded pieces, the process base plate material has equal or stronger deformation resistance, and compared with a diffusion welding clamp, the deformation resistance of the process base plate is weaker than that of the diffusion welding clamp; step three: pretreating a part to be welded; step four: coating a solder stop agent; step five: assembling and stacking; step six: diffusion welding; step seven: measuring after welding; step eight: calibrating the process base plate; step nine: and (6) evaluating in batches. According to the invention, the process base plate for compensating the height difference is introduced into the multilayer stack diffusion welding, so that the accumulated height difference of the multilayer stack fixture is effectively compensated, and the dimensional accuracy of the blank during the single-furnace multilayer stack diffusion welding is improved.
Description
Technical Field
The invention belongs to the technical field of manufacturing of aeroengine blades, and particularly relates to a method for improving batch welding size precision of split diffusion welding parts.
Background
With the continuous development of aerospace manufacturing technology, the requirements of aircrafts with high thrust and low energy consumption are more obvious, the aircraft design gradually evolves towards equal strength, light weight and integrated multifunction, and a novel design form developed therewith is a structural member with a cavity. Particularly, with the continuous improvement of computer design and virtual simulation technology in recent years, structural topology optimization design technology is increasingly applied to aircraft design. A structural topological optimization design and an aircraft mechanics and aerodynamics design are combined, and cavity structural members with various styles, such as pure cavities based on variable wall thickness design, cavities with single-trend studs, cavity structural members with complex stud forms with topological structure characteristics or bionic structure characteristics and the like, are derived. Through various innovative structural designs, the structural member with the cavity not only can realize equal-strength weight reduction, but also can realize the functions of reducing noise, reducing vibration, insulating heat, transmitting cooling air or heating fuel gas, transmitting fuel oil and the like, and is more and more widely applied to the aerospace manufacturing field and a plurality of manufacturing fields such as chemical industry, ships, satellites and the like.
By inquiring domestic and foreign documents and patent data, the manufacturing method of the cavity structural part mainly comprises the following steps: mechanical connection such as riveting, bolt connection and the like, fusion welding connection such as electron beam welding, argon arc welding and the like, solid phase connection such as friction stir welding, split diffusion welding and the like, superplastic forming/diffusion bonding (SPF/DB) composite process, brazing and the like. The split diffusion welding has the characteristics of a solid phase connection process on one hand, local melting, equal strength of a joint and a base material or the strength close to the base material strength are not generated in the welding process, and on the other hand, the split diffusion welding has the advantages of strong realization capability of a cavity design structure, simple process route, high controllability of the process, no dependence on high-end complex welding equipment (such as positive pressure diffusion connection equipment, hot isostatic pressing equipment and other equipment with complex structures and high values) and the like, and becomes a preferred process method for manufacturing cavity structural members.
The titanium alloy hollow rectification support plate (also called as an air inlet support plate and a fixed support plate) and the adjustable blade of the aircraft engine manufactured by the split diffusion welding process become the substitute products of SPF/DB process products and enter the engineering application stage. With the continuous improvement of the yield of the components, the contradiction and conflict between the production efficiency, the manufacturing cost and the product quality become more and more prominent. The current situation and the existing problems are as follows by combining the actual production of a plurality of part numbers of parts:
the hollow rectifying support plate and the adjustable blade are high-performance parts, and have strict requirements on manufacturing conformity and consistency of wall thickness and inner and outer profile contours, so that a diffusion welding blank must have higher dimensional consistency so as to be convenient for subsequent appearance processing, and a product meeting the use requirement is delivered. As shown in fig. 1, when the multi-layer stack diffusion welding is adopted, the size consistency of diffusion welding blanks produced in continuous batch is poor due to the accumulation of the manufacturing deviation of a fixture, according to the existing data statistics, a certain TC4 alloy air inlet support plate is continuously produced by adopting a multi-layer stack method, the height size deviation of the diffusion welding blanks reaches 0.25mm, which is 3 times of the height size deviation of the blanks after single-layer diffusion welding, and the shape processing of the post-process is seriously influenced by the size deviation of the diffusion welding blanks. In order to compensate for the size deviation of the diffusion welding blank, a processing mode of alternating off-line measurement and machining has to be adopted for appearance processing in the subsequent procedure, namely a customized processing scheme, so that the labor and material cost is greatly increased, and the manufacturing period of the product is also prolonged.
The problem of multilayer pile up diffusion welding anchor clamps and make deviation accumulation is solved, not only be of value to improving the diffusion welding blank size uniformity in batches, can reduce mould repair and equipment cost of maintenance to a certain extent simultaneously. According to the prior documents and patents, no relevant information about the dimensional accuracy consistency control of the multi-layer stack diffusion welding is described, and relevant documents are not found in relevant fields such as plastic forming and forging. Therefore, a method for improving the batch welding dimensional accuracy of split diffusion welding parts is needed.
Disclosure of Invention
Aiming at the defects in the prior art, on the basis of systematically researching the high-temperature performance and the high-temperature deformation characteristic of the TC4 titanium alloy and analyzing the heating, loading process and compression deformation rule of the TC4 titanium alloy hollow rectifying support plate and the adjustable blade in diffusion welding, the invention provides a method for improving the batch welding size precision of split diffusion welding parts.
A method for improving the batch welding dimensional accuracy of split diffusion welding parts comprises the following steps:
the method comprises the following steps: preparing a to-be-welded part;
step two: preparing a process base plate;
compared with TC4 alloy parts to be welded, the process base plate material has equal or stronger anti-deformation capability, and compared with a diffusion welding clamp, the anti-deformation capability of the process base plate is weaker than that of the diffusion welding clamp;
step three: pretreating a part to be welded;
step four: coating a solder stop agent;
step five: assembling and stacking;
step six: diffusion welding;
step seven: measuring after welding;
step eight: calibrating the process base plate;
step nine: and (6) evaluating in batches.
In the first step, the roughness Ra of the surface to be welded is less than or equal to 0.8 mu m, the planeness of the outer surface and the surface to be welded is less than or equal to 0.03mm, and the parallelism between the two planes is less than or equal to 0.05mm; if the contour of the curved surface to be welded exists, the degree of the contour of the curved surface to be welded is less than or equal to 0.03mm.
And in the second step, the thickness of the process backing plate is more than or equal to 10mm.
The third step is to pretreat the workpiece to be welded by adopting a conventional acid washing method to remove residual oxides and heterogeneous particle adhesion on the surface; ultrasonically cleaning a to-be-welded part by using deionized water; after cleaning, the surfaces to be welded are inspected to ensure that there are no water spots, scratches or scratches.
And the fourth step of coating the welding stopping agent is to spray the boron nitride welding stopping agent on the contact surface of the diffusion welding fixture and the part and the upper and lower surfaces of the process backing plate, and place and dry the boron nitride welding stopping agent.
The method for assembling and stacking in the fifth step is that a diffusion welding fixture and a piece to be welded are assembled to form a module, wherein the diffusion welding fixture comprises a fixture lower plate, a limiting plate and a fixture upper plate, the fixture lower plate and the fixture upper plate are L-shaped and are oppositely arranged, the piece to be welded is fixed between the fixture lower plate and the fixture upper plate, and the limiting plate is fixed between the fixture upper plate and the fixture lower plate and is positioned at two sides of the piece to be welded; a gap is formed between the upper plate of the clamp and the limiting plate; and uniformly arranging a plurality of groups of assembled modules on an equipment platform of the axial pressurizing vacuum diffusion welding furnace, placing a process base plate on the top of each stack, and contacting an equipment pressure plate of the axial pressurizing vacuum diffusion welding furnace with the top of the process base plate.
And in the sixth step, diffusion welding is carried out by adopting a conventional diffusion welding process.
And seventhly, after diffusion welding, measuring the height of each part in the whole furnace by using a micrometer to obtain the height deviation of the welded parts.
In the step eight, the process base plate is calibrated after each furnace is used, specifically: and (3) carrying out plane grinding or milling on the process base plate, so that the flatness of the process base plate and the parallelism of the upper surface and the lower surface are both less than or equal to 0.05mm, and the height difference between the process base plates is less than or equal to 0.05mm.
And step ten, measuring and evaluating the postweld height dimension of the to-be-welded part produced by continuous diffusion welding to obtain the height dimension deviation among furnaces.
The invention has the beneficial effects that: according to the invention, the process base plate for compensating the height difference is introduced into the multilayer stack diffusion welding, so that the accumulated height difference of the multilayer stack fixture is effectively compensated, and the dimensional accuracy of the blank during the single-furnace multilayer stack diffusion welding is improved. The method is adopted to carry out continuous batch production of multilayer stack diffusion welding, and the height size deviation of the blank after diffusion welding is reduced from 0.25mm to 0.11mm, which is reduced by more than 50%.
The invention effectively realizes the control of the size precision of the batch diffusion welding of the split diffusion welding parts, provides a blank with higher height size consistency for the shape processing of the subsequent process, reduces the repeated measurement and clamping work, reduces the difficulty of the shape processing of the process and provides guarantee for the batch production.
Drawings
FIG. 1 is a schematic view of a prior art multi-layer stack diffusion weld;
FIG. 2 is a schematic view of the assembly of a process kit plate provided in the present invention;
FIG. 3 is a schematic view of the principle of compressive stress of the process shim plate provided in the present invention;
FIG. 4 is a schematic time-series diagram of the high compensation principle in the method provided by the present invention;
wherein the content of the first and second substances,
1-equipment platform, 2-equipment pressing plate, 3-clamp lower plate, 4-clamp upper plate, 5-limiting plate, 6-piece to be welded and 7-process base plate.
Detailed Description
For better understanding of the present invention, the technical solutions and effects of the present invention will be described in detail by the following embodiments with reference to the accompanying drawings.
Example 1
In the embodiment, the to-be-welded part 6 is a single TC4 alloy split-structure air inlet support plate, and a method for improving the batch welding dimensional accuracy of split diffusion welding parts specifically includes the following steps:
the method comprises the following steps: preparation of the part to be welded 6
Preparing a to-be-welded part 6, and ensuring that the roughness Ra of the to-be-welded surface is less than or equal to 0.8 mu m, the planeness of the outer surface and the to-be-welded surface is less than or equal to 0.03mm, and the parallelism between the two surfaces is less than or equal to 0.05mm.
Step two: preparation of Process Mat plate 7
In the implementation, the process backing plate 7 is made of a TC4 alloy thick plate, and the size of the process backing plate 7 is larger than or equal to that of the upper clamp plate 4 in the diffusion welding clamp. The size of the process backing plate 7 in the embodiment is 200mm multiplied by 400mm; the upper surface and the lower surface of the technological backing plate 7 are processed by grinding, so that the thickness of the technological backing plate is 30 +/-0.03 mm, and the planeness and the parallelism of the upper surface and the lower surface are both less than or equal to 0.05mm.
The choice of the material of the technological shim plate 7 is extensive, the technological shim plate 7 having equal or greater resistance to deformation than the TC4 alloy to be welded 6, whereas the technological shim plate 7 having less resistance to deformation than the diffusion welding jig, thus acting to compensate for the difference in stack height.
Step three: pretreatment of the parts to be welded 6
Pretreating the surface to be welded by adopting a conventional acid washing method to remove residual oxides on the surface and attach heterogeneous particles; ultrasonically cleaning a to-be-welded part 6 by using deionized water; after cleaning, the surfaces to be welded are inspected to ensure that there are no water spots, scratches or scratches.
Step four: solder stop coating
And spraying boron nitride anti-welding agent on the contact surface of the diffusion welding fixture and the part and the upper and lower surfaces of the process backing plate 7, and placing and airing.
Step five: assembled stack
Assembling a diffusion welding fixture and a gas inlet support plate of a 6TC4 alloy split structure of a to-be-welded part to form a module, wherein the diffusion welding fixture comprises a fixture lower plate 3, a limiting plate 5 and a fixture upper plate 4, the fixture lower plate 3 and the fixture upper plate 4 are L-shaped and are oppositely arranged, the to-be-welded part 6 is fixed between the fixture lower plate 3 and the fixture upper plate 4, and the limiting plate 5 is fixed between the fixture upper plate 4 and the fixture lower plate 3 and is positioned at two sides of the to-be-welded part 6; a gap exists between the upper clamp plate 4 and the limiting plate 5. The diffusion welding fixture material is well matched with a diffusion welding process, has good deformation resistance during diffusion welding pressure maintaining, and has deformation resistance meeting the requirements of the diffusion welding process. As shown in fig. 1, a plurality of groups of assembled modules are uniformly distributed on an equipment platform 1 of an axial pressurizing vacuum diffusion welding furnace, and 3 pieces are placed in one layer to form three stacks, wherein 3 layers are formed in each stack; on top of each stack a process shim plate 7 is placed, as shown in fig. 2, and the equipment platen 2 of the axially pressurized vacuum diffusion furnace is brought into contact with the top of the process shim plate 7.
Step six: diffusion welding
The diffusion welding is carried out by adopting a conventional diffusion welding process, in the diffusion welding process, as shown in fig. 3, the axial pressurizing pressure head applies pressure P to the equipment pressure plate 2, the pressure P is transmitted to the equipment platform 1 layer by layer downwards through the stacking module, the equipment platform 1 forms supporting force F, and the external force balance state is achieved, namely P = F. And after the heat preservation of the diffusion welding is finished, keeping the vacuum state until the cooling is finished.
Under the action of the axial pressing pressure of the device, the to-be-welded part 6 generates compression plastic deformation in the axial pressing direction, so that the height of the whole stack is continuously reduced. If the diffusion welding fixture has zero manufacturing deviation, when diffusion welding is finished, the weldment is pressed to be equal to the limiting plate 5 in height under the action of axial pressurizing pressure, the fixture upper plate 4 is in contact with the limiting plate 5 to be assembled, the heights of different stacks are completely consistent, and the height size of the weldment blank after diffusion welding is kept in good consistency. However, manufacturing deviation of the diffusion welding fixture is inevitable, that is, according to the traditional multilayer stack diffusion welding scheme, the upper part of the fixture and the limiting plate 5 cannot realize contact die assembly, and the height of a weldment in a die set which cannot realize contact die assembly is slightly larger than that of other die set which are clamped. It is expected that the inconsistency of the height dimension of the solder pieces will be more serious as the number of stacked layers increases, which is why the deviation of the height dimension of the solder pieces after the multi-layer stack diffusion soldering becomes larger.
The invention places a process shim plate 7 on each stack having an area greater than or equal to the diffusion welding fixture upper plate 4, it is apparent that the process shim plate 7 is under the same axial pressure as the weldment. The process base plate 7 is a solid body, the axial pressure is approximately uniformly distributed and conducted in the process base plate 7, and the generated axial pressure stress is sigma 1; the weldment is a structural member with a cavity, axial pressure of the structural member is transferred through the weld face region, and the cavity region does not take on the axial pressure transfer function, so that axial compressive stress sigma 2 is generated on the weldment, and obviously sigma 1 is less than sigma 2. According to the diffusion welding process scheme and the design characteristics of the machining allowance of the weldment, the area of the welding surface is about 30% -60% of the area of the process backing plate 7, namely, the axial compressive stress level in the process backing plate 7 is far lower than that in the weldment, as shown in fig. 3.
It is clear that with such a difference in the internal pressure stress of the process shim plate 7 and the weldment and by choosing a suitable process shim plate 7 material the following effects can be achieved: in the diffusion welding process, when axial pressurizing pressure P is applied, pressure stress is generated in the process base plate 7 and the weldment, the process base plate 7 and the weldment generate plastic deformation under the action of the pressure stress, and the process base plate 7 and the weldment have equal or stronger deformation resistance compared with the TC4 alloy to-be-welded part 6, and compared with a diffusion welding clamp, the deformation resistance of the process base plate 7 is weaker than that of the diffusion welding clamp, so that the compression plastic deformation speed and the deformation amount generated by the process base plate 7 are far smaller than those of the TC4 alloy, the TC4 weldment is forced to preferentially reach the preset compression deformation limit of the diffusion welding process, and the clamp upper plate 4 and the limiting plate 5 are matched. The axial pressurizing pressure of the vacuum diffusion welding furnace is continuously kept, and the compression plastic deformation of the weldment in the height direction is not increased. Assuming that the total height of a certain stack is the maximum, the die assembly is realized layer by layer in the diffusion welding pressurization process, so that the diffusion welding clamp upper plate 4, the clamp lower plate 3, the limiting plate 5 and the piece to be welded 6 form a group of relatively rigid bodies; and the process base plate 7 continues to generate compression deformation due to the rigid constraint of the upper clamp plate 4 at the lower part of the process base plate, and the whole stacking height continues to descend. At this time, for the stack with the lower total height of the diffusion welding fixture, because the deformation rate of the process backing plate 7 is lower than that of the TC4 weldment, the TC4 weldment in the un-closed module will continue to deform until each layer of module is closed to form a group of rigid bodies, and so on, the stack with the lower height of the fixture will repeat the above process, as shown in fig. 4, the heights of the three stacks in the embodiment are different before welding, as shown in fig. 4 (a), the height of the leftmost stack is higher than the heights of the two stacks on the right, and the height of the middle stack is the lowest; along with the welding, as shown in fig. 4 (b), the technological base plate 7 is deformed, and the three stacked fixture upper plates 4 and the limiting blocks are sequentially matched; as shown in fig. 4 (c), after the welding is finished, the heights of the three stacks are consistent, the gap between the fixture upper plate 4 and the limiting block in each stack disappears, the die assembly is realized, the heights of the process base plates 7 of the three stacks are different, wherein the thickness of the process base plate 7 in the stack with the highest height before the welding at the leftmost side is the smallest, the thickness of the process base plate 7 in the stack with the lowest height before the welding at the middle part is the lowest, the die assembly of the fixture upper plate 4 and the limiting block is highly compensated by the process base plate 7 due to thermal deformation, the contact die assembly of the fixture upper plate 4 and the limiting block 5 is realized, and the heights of different stacks are completely consistent.
Step seven: post-weld measurement
After diffusion welding, the height of each part in the whole furnace is measured by a micrometer, and the height deviation of the welded parts is less than or equal to 0.07mm.
Step eight: calibration of the process shim plate 7
Because the principle of process backing plate 7 compensation stack difference in height lies in the plastic deformation compensation promptly at diffusion welding in-process, consequently all produce the plastic deformation of different degrees after every stove diffusion welding finishes promptly after using at every turn, in order not to influence the compensation effect, all calibrate process backing plate 7 after every stove uses, it is specific: and (3) carrying out plane grinding on the technological base plate 7, so that the flatness of the technological base plate 7 and the parallelism of the upper surface and the lower surface are both less than or equal to 0.05mm, and the height difference between the technological base plates 7 is less than or equal to 0.05mm.
Step nine: batch evaluation
And measuring and evaluating the height dimension of the TC4 alloy split-structure air inlet support plate produced by continuous diffusion welding after welding, wherein the result is that the height dimension deviation among furnaces is less than or equal to 0.11mm.
Example 2
In the embodiment, the to-be-welded part 6 takes a TC4 alloy split-structure hollow adjustable blade single piece as an example, and the method for improving the batch welding dimensional accuracy of the split diffusion welding parts specifically comprises the following steps:
the method comprises the following steps: preparation of the part to be welded 6
Preparing a to-be-welded part 6, and ensuring that the roughness Ra of the to-be-welded surface is less than or equal to 0.8 mu m, the planeness of the outer surface is less than or equal to 0.03mm, and the profile of the to-be-welded curved surface is less than or equal to 0.03mm.
Step two: preparation of Process Mat 7
In the implementation, the process base plate 7 is made of GH4169 alloy forging blank, the size of the process base plate 7 is larger than or equal to that of the upper clamp plate 4 in the diffusion welding clamp, and the size of the process base plate 7 in the embodiment is 180mm multiplied by 360mm; the upper surface and the lower surface of the technological backing plate 7 are processed by grinding, so that the thickness of the technological backing plate is 10 +/-0.03 mm, and the planeness and the parallelism of the upper surface and the lower surface are both less than or equal to 0.05mm.
The choice of the material of the technological shim plate 7 is extensive, the technological shim plate 7 has an equal or stronger resistance to deformation than the TC4 alloy to be welded 6, whereas the technological shim plate 7 has a resistance to deformation weaker than the diffusion welding jig, thus serving to compensate for the difference in stack height.
Step three: pretreatment of the parts to be welded 6
Pretreating the surface to be welded by adopting a conventional acid washing method to remove residual oxides on the surface and attach heterogeneous particles; ultrasonically cleaning a to-be-welded part 6 by using deionized water; after cleaning, the surfaces to be welded are inspected to ensure that there are no water spots, scratches or scratches.
Step four: solder stop coating
And spraying boron nitride solder stop agent on the contact surface of the diffusion welding fixture and the part and the upper and lower surfaces of the process backing plate 7, and placing and airing.
Step five: assembled stack
Assembling a diffusion welding fixture with an air inlet support plate of a 6TC4 alloy split structure of a to-be-welded piece to form a module, wherein the diffusion welding fixture comprises a fixture lower plate 3, a limiting plate 5 and a fixture upper plate 4, the fixture lower plate 3 and the fixture upper plate 4 are L-shaped and are oppositely arranged, the to-be-welded piece 6 is fixed between the fixture lower plate 3 and the fixture upper plate 4, and the limiting plate 5 is fixed between the fixture upper plate 4 and the fixture lower plate 3 and is positioned at two sides of the to-be-welded piece 6; a gap exists between the upper clamp plate 4 and the limiting plate 5. The diffusion welding fixture material is well matched with a diffusion welding process, has good deformation resistance during diffusion welding pressure maintaining, and has deformation resistance meeting the requirements of the diffusion welding process. As shown in fig. 1, a plurality of groups of assembled modules are uniformly distributed on an equipment platform 1 of an axial pressurizing vacuum diffusion welding furnace, and 3 pieces are placed in one layer to form three stacks, wherein 3 layers are formed in each stack; on top of each stack a process shim plate 7 is placed, as shown in fig. 2, and the equipment platen 2 of the axially pressurized vacuum diffusion furnace is brought into contact with the top of the process shim plate 7.
Step six: diffusion welding
The diffusion welding is carried out by adopting a conventional diffusion welding process, in the diffusion welding process, as shown in fig. 3, the axial pressurizing pressure head applies pressure P to the equipment pressure plate 2, the pressure P is transmitted to the equipment platform 1 layer by layer downwards through the stacking module, the equipment platform 1 forms supporting force F, and the external force balance state is achieved, namely P = F. And after the heat preservation of the diffusion welding is finished, keeping the vacuum state until the cooling is finished.
Under the action of the axial pressing pressure of the device, the to-be-welded part 6 generates compression plastic deformation in the axial pressing direction, so that the height of the whole stack is continuously reduced. If the diffusion welding fixture has zero manufacturing deviation, when diffusion welding is finished, the weldment is pressed to be equal to the limiting plate 5 in height under the action of axial pressurizing pressure, the fixture upper plate 4 is in contact with the limiting plate 5 to be assembled, the heights of different stacks are completely consistent, and the height size of the weldment blank after diffusion welding is kept in good consistency. However, manufacturing deviation of the diffusion welding fixture is inevitable, that is, according to the traditional multilayer stack diffusion welding scheme, the upper part of the fixture and the limiting plate 5 cannot realize contact die assembly, and the height of a weldment in a die set which cannot realize contact die assembly is slightly larger than that of other die set which are clamped. It is expected that the inconsistency of the height dimension of the solder pieces will be more serious as the number of stacked layers increases, which is why the deviation of the height dimension of the solder pieces after the multi-layer stack diffusion soldering becomes larger.
The invention places a process shim plate 7 on each stack having an area greater than or equal to the diffusion welding fixture upper plate 4, it is apparent that the process shim plate 7 is under the same axial pressure as the weldment. The process base plate 7 is a solid body, the axial pressure is approximately uniformly distributed and conducted in the process base plate 7, and the generated axial pressure stress is sigma 1; the weldment is a structural member with a cavity, axial pressure of which is transmitted through the weld face area, and the cavity area does not take on the axial pressure transmission function, so that axial compressive stress sigma 2 is generated on the weldment, and obviously sigma 1 < sigma 2. According to the diffusion welding process scheme and the design characteristics of the machining allowance of the weldment, the area of the welding surface is about 30% -60% of the area of the process backing plate 7, namely, the axial compressive stress level in the process backing plate 7 is far lower than that in the weldment, as shown in fig. 3.
It is clear that with such a difference in the internal pressure stress of the process shim plate 7 and the weldment and by choosing a suitable process shim plate 7 material the following effects can be achieved: in the diffusion welding process, when axial pressurizing pressure P is applied, pressure stress is generated in the process backing plate 7 and the weldment, the process backing plate 7 and the weldment generate plastic deformation under the action of the pressure stress, and the process backing plate 7 and the weldment generate equal or stronger deformation resistance compared with a TC4 alloy weldment 6, and compared with a diffusion welding clamp, the deformation resistance of the process backing plate 7 is weaker than that of the diffusion welding clamp, so that the compression plastic deformation speed and the deformation quantity generated by the process backing plate 7 are far smaller than those of the TC4 alloy, the TC4 weldment is forced to reach the preset compression deformation limit of the diffusion welding process preferentially, and the upper plate 4 and the limiting plate 5 of the clamp are matched. The axial pressurizing pressure of the vacuum diffusion welding furnace is continuously kept, and the compression plastic deformation of the weldment in the height direction is not increased. Assuming that the total height of a certain stack is the maximum, the die assembly is realized layer by layer in the diffusion welding pressurization process, so that the diffusion welding clamp upper plate 4, the clamp lower plate 3, the limiting plate 5 and the piece to be welded 6 form a group of relatively rigid bodies; and the process base plate 7 continues to generate compression deformation due to the rigid constraint of the upper clamp plate 4 at the lower part of the process base plate, and the whole stacking height continues to descend. At this point, for stacks with lower total height of the diffusion welding fixture, because the aforementioned process shim plate 7 deforms at a rate lower than the TC4 weldment, the TC4 weldment in the unmated die sets will continue to deform until each layer of die sets is mated to form a set of rigid bodies, and so on, the above process will be repeated for stacks with lower fixture height, as shown in fig. 4.
Step seven: post weld measurement
After diffusion welding, measuring the height of each part in the whole furnace by adopting a micrometer, wherein the height deviation of the welded parts is less than or equal to 0.05mm.
Step eight: calibration of the process shim plate 7
Because the principle of process backing plate 7 compensation stack difference in height lies in the plastic deformation compensation promptly at diffusion welding in-process, consequently all produce the plastic deformation of different degrees after every stove diffusion welding finishes promptly after using at every turn, in order not to influence the compensation effect, all calibrate process backing plate 7 after every stove uses, it is specific: and (3) performing plane milling on the technological base plate 7 to ensure that the planeness and the parallelism of the upper surface and the lower surface of the technological base plate 7 are both less than or equal to 0.05mm, and the height difference between the technological base plates 7 is less than or equal to 0.05mm.
Step nine: batch evaluation
And measuring and evaluating the height dimension of the welded TC4 alloy split-structure hollow adjustable blade produced by continuous diffusion welding, wherein the result is that the height dimension deviation among furnaces is less than or equal to 0.10mm.
The method is adopted to carry out multilayer stack diffusion welding continuous batch production, the deviation of the height dimension of the blank after diffusion welding is not more than 0.11mm, the control of the batch diffusion welding dimension precision of the diffusion welding parts is effectively realized, and the blank with higher height dimension consistency is provided for the appearance processing of the subsequent process; the repeated measurement clamping work is reduced, the processing difficulty of the process appearance is reduced, and the guarantee is provided for batch production.
Claims (10)
1. A method for improving the batch welding dimensional accuracy of split diffusion welding parts is characterized by comprising the following steps:
the method comprises the following steps: preparing a to-be-welded part;
step two: preparing a process base plate;
compared with TC4 alloy to-be-welded parts, the process base plate material has equal or stronger deformation resistance, and compared with a diffusion welding clamp, the process base plate has weaker deformation resistance than the diffusion welding clamp;
step three: pretreating a part to be welded;
step four: coating a solder stop agent;
step five: assembling and stacking;
step six: diffusion welding;
step seven: measuring after welding;
step eight: calibrating the process base plate;
step nine: and (6) evaluating in batches.
2. The method for improving the batch welding dimensional accuracy of the split diffusion welding parts according to claim 1, wherein the method comprises the following steps: in the first step, the roughness Ra of the surface to be welded is less than or equal to 0.8 mu m, the planeness of the outer surface and the surface to be welded is less than or equal to 0.03mm, and the parallelism between the two planes is less than or equal to 0.05mm; if the contour of the curved surface to be welded exists, the contour degree of the curved surface to be welded is less than or equal to 0.03mm.
3. The method for improving the batch welding dimensional accuracy of the split diffusion welding parts according to claim 1, wherein the method comprises the following steps: and the thickness of the process cushion plate in the second step is more than or equal to 10mm.
4. The method for improving the batch welding dimensional accuracy of the split diffusion welding parts according to claim 1, wherein the method comprises the following steps: the third step is to pretreat the workpiece to be welded by adopting a conventional acid washing method to remove residual oxides and heterogeneous particle adhesion on the surface; ultrasonically cleaning a to-be-welded part by using deionized water; after cleaning, the surfaces to be welded are inspected to ensure that there are no water spots, scratches or scratches.
5. The method for improving the batch welding dimensional accuracy of the split diffusion welding parts according to claim 1, wherein the method comprises the following steps: and the fourth step of coating the welding stopping agent is to spray the boron nitride welding stopping agent on the contact surface of the diffusion welding fixture and the part and the upper and lower surfaces of the process backing plate, and place and dry the boron nitride welding stopping agent.
6. The method for improving the batch welding dimensional accuracy of the split diffusion welding parts according to claim 1, wherein the method comprises the following steps: the method for assembling and stacking in the fifth step is that a diffusion welding fixture and a piece to be welded are assembled to form a module, wherein the diffusion welding fixture comprises a fixture lower plate, a limiting plate and a fixture upper plate, the fixture lower plate and the fixture upper plate are L-shaped and are oppositely arranged, the piece to be welded is fixed between the fixture lower plate and the fixture upper plate, and the limiting plate is fixed between the fixture upper plate and the fixture lower plate and is positioned at two sides of the piece to be welded; a gap is formed between the upper plate of the clamp and the limiting plate; and uniformly arranging a plurality of groups of assembled modules on an equipment platform of the axial pressurizing vacuum diffusion welding furnace, placing a process base plate on the top of each stack, and contacting an equipment pressure plate of the axial pressurizing vacuum diffusion welding furnace with the top of the process base plate.
7. The method for improving the batch welding dimensional accuracy of the split diffusion welding parts according to claim 1, wherein the method comprises the following steps: and in the sixth step, conventional diffusion welding technology is adopted for diffusion welding.
8. The method for improving the batch welding dimensional accuracy of the split diffusion welding parts according to claim 1, wherein the method comprises the following steps: and seventhly, after diffusion welding, measuring the height of each part in the whole furnace by using a micrometer to obtain the height deviation of the welded parts.
9. The method for improving the batch welding dimensional accuracy of the split diffusion welding parts according to claim 1, wherein the method comprises the following steps: in the step eight, the process base plate is calibrated after each furnace is used, specifically: and (3) carrying out plane grinding or milling on the process base plate, so that the flatness of the process base plate and the parallelism of the upper surface and the lower surface are both less than or equal to 0.05mm, and the height difference between the process base plates is less than or equal to 0.05mm.
10. The method for improving the batch welding dimensional accuracy of the split diffusion welding parts according to claim 1, wherein the method comprises the following steps: and step ten, measuring and evaluating the postweld height of the to-be-welded part produced by continuous diffusion welding to obtain the height size deviation among furnaces.
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