Manufacturing method of bell-shaped aluminum alloy pipe parts

Abstract

The present invention proposes a method for manufacturing "bell-mouth" shaped aluminum alloy pipe parts, and belongs to the technical field of sheet metal parts processing for aviation aircraft. The present invention realizes the accurate manufacturing of "bell-mouth" shaped aluminum alloy pipe parts by newly designing a set of spinning dies for spinning and a set of molds for manual forming, and optimizing the process flow of single flaring forming or deep drawing forming to "spinning-manual forming". Compared with deep drawing and flaring forming, which have high manufacturing costs and difficult to control production processes, the spinning dies and molds used in "spinning-manual forming" are simple in structure, low in manufacturing cost, and require low skill levels of operators during the production process. In addition, the sheet material flows evenly during spinning, avoiding the problem of uneven thickness changes causing the inner diameter of the tube wall to not conform to the design drawing, thereby improving the processing quality of parts and reducing scrap rate.

Description

Technical Field

[0001] The invention belongs to the technical field of aviation aircraft sheet metal parts processing, and relates to a method for manufacturing a "bell-mouth" shaped aluminum alloy pipe part. Background Art

[0002] In the military aircraft scientific research model project, there is a special structure conduit in the aircraft fuel system, which is used for the installation of the fuel tank supply system. Different from the traditional conduit, the typical feature of this type of conduit is that the straight section is coupled with the "bell-mouth" shaped pipe end. The conduit size is small, the total length of the part is 60mm, the inner diameter of the straight section is φ30mm, the "bell-mouth" size is φ60mm, and the center normal of the "bell-mouth" flange is not on the same straight line as the normal of the straight section, and there is a certain degree of offset. For this type of conduit, the straight end needs to be connected with other conduits, so the design drawing requires that the inner diameter size of the pipe wall must be φ30mm after forming, otherwise there will be a thickness step difference inside the conduit when it is connected to other pipes, and the pipe wall is prone to rupture under the long-term action of high-pressure liquid. The processing methods for this type of parts include conduit expansion processing, sheet metal deep drawing forming, etc. Among them, for the conduit expansion processing, a conduit with an inner diameter of φ30mm needs to be used for expansion. Since the flange size of the "bell-mouth" shaped pipe end is large, the expansion deformation is large, resulting in excessive thinning of the thickness of the "bell-mouth" or even rupture and damage, which cannot meet the size requirements specified in the design drawing. For deep drawing, the material needs to shrink and flow to form a "straw hat" shaped structure, and then the bottom wall is removed to obtain the final part. Since the normal line of the "bell-mouth" tube end is not on the same straight line as the normal line of the straight segment, under the premise of ensuring that the straight segment and the stamping equipment remain vertical, the time when the material enters the die during the deep drawing process is different, and the forming process is difficult to control. It is easy to have uneven thickness of the straight segment tube wall, which makes it impossible to ensure the consistency of the inner diameter size after installation with the adjacent conduit, so the scrap rate of parts is high. In addition, deep drawing has high requirements for tooling design and manufacturing, and the gap between the convex and concave dies is difficult to accurately control, which also affects the effect of deep drawing to a certain extent. The above reasons make it difficult to produce such "bell-mouth" shaped aluminum alloy tube parts. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a method for manufacturing "bell-mouth" shaped aluminum alloy pipe parts, which manufactures a set of spinning dies for spinning and a set of molds for manual forming, and optimizes the single expansion forming or deep drawing forming process to "spinning-manual forming", thereby realizing accurate manufacturing of "bell-mouth" shaped aluminum alloy pipe parts. The spinning dies and molds used in the present invention can realize the manufacture of "bell-mouth" shaped aluminum alloy pipe parts, and can improve the processing quality of parts and reduce the scrap rate.

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

[0005] A method for manufacturing a "bell-mouth" shaped aluminum alloy pipe part comprises three processes: numerical milling, spinning and manual forming.

[0006] The first process: cutting by numerical milling.

[0007] The medium used for cutting by numerical milling is a two-dimensional unfolded data set. In the present invention, spinning forming is a rotational motion, which essentially relies on the peripheral material to flow toward the center to form a bulge, so the required rough material should be circular, and the outer contour size is a "trumpet-shaped" unfolded size, and the peripheral margin can be appropriately increased.

[0008] The second process: spinning.

[0009] Since the normal line of the "bell mouth" pipe end of the part is not on the same straight line as the normal line of the straight segment, it is an irregular structure and cannot be directly formed by spin forming. In the present invention, a spinning process part is designed to simplify the "bell mouth" pipe end into a regular flange whose normal line coincides with the normal line of the straight segment, and the process part is formed by the spin forming method. The tooling used for spin forming is a spinning die, which includes a carcass A1 and a top plate 2.

[0010] The spinning die can realize the formation of a cap-shaped structure with a regular flange on the sheet material, that is, a spinning process part, for subsequent manual forming. Among them, the carcass A1 is made of Q235, and the structure is designed according to the spinning process part, that is, the working end diameter is the same as the inner diameter of the spinning process part, and the length is slightly longer than the spinning process part, generally 10-20mm longer; the clamping end diameter is selected to be slightly larger than the working end diameter, which is convenient for the tooling to be clamped on the three-jaw chuck of the spinning lathe. The top plate 2 is made of cloth-reinforced bakelite, and its diameter is the same as the working end diameter of the carcass A1; the center position of the top plate 2 end is designed with a tapered hole with a depth of 6mm and an angle of 60°, which is used to cooperate with the spinning tailstock ejector pin to clamp the spinning workpiece.

[0011] The third process: manual forming.

[0012] The tooling used for manual forming is a mold, which includes a tire body B4, a cover plate 5, a core 6, a positioning pin 7 and a lifting eye screw 8.

[0013] The mold described can realize the forming of the spinning process parts to the final shape of the "trumpet" shape. Among them, the carcass B4 is designed according to the outer surface of the part, and the cover plate 5 is designed according to the inner surface of the "trumpet" of the part. The relative position of the carcass B4 and the cover plate 5 is determined by the positioning pin 7 to ensure that there is no relative displacement between the two during the forming process. The core 6 is manufactured according to the inner shape of the part, and its length is slightly longer than the part. It is used to assist in forming and support the part tube wall from the inside to prevent the tube from deforming or even collapsing during the forming process. The eye screw 8 is installed on the carcass B4 for easy handling.

[0014] Beneficial effects of the present invention: The present invention proposes a new method for manufacturing "bell-mouth" shaped aluminum alloy pipe parts, by designing a set of spinning dies for spinning and a set of molds for manual forming, and optimizing the process of single flaring forming or deep drawing forming to "spinning-manual forming", so as to achieve accurate manufacturing of "bell-mouth" shaped aluminum alloy pipe parts. Although the process flow has increased, compared with deep drawing and flaring forming, which have high manufacturing costs and difficult to control production processes, the spinning dies and molds used in "spinning-manual forming" are simple in structure, low in manufacturing cost, and require low skill levels of operators during the production process. In addition, the sheet material flows evenly during spinning, avoiding the problem of uneven thickness changes causing the inner diameter of the tube wall to not conform to the design drawing, thereby improving the processing quality of parts and reducing scrap rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of the parts to be processed.

[0016] Figure 2 It is a schematic diagram of the structure of the spinning process parts.

[0017] Figure 3 Schematic diagram of the structure of the spinning mold, where (a) is the main view and (b) is the axonometric view.

[0018] Figure 4 It is a schematic diagram of the structure of the tire, where (a) is the main view and (b) is the AA view.

[0019] In the figure: 1 carcass A; 2 top plate; 3 spinning process parts; 4 carcass B; 5 cover plate; 6 core; 7 positioning pin; 8 eye screw; 9 parts. DETAILED DESCRIPTION

[0020] The specific implementation of the present invention is further explained below in conjunction with the examples and drawings, but is not intended to limit the present invention.

[0021] The present invention proposes a method for manufacturing a "bell-mouth" shaped aluminum alloy pipe part. After cutting the material by CNC milling, the method of "spinning forming-manual forming" is adopted. First, a spinning die is used to form a spinning process part with a regular flange and the same inner diameter as the straight section of the part, and then the final shape of the part is formed by manual forming. The specific steps are as follows:

[0022] Step 1: CNC milling and cutting. According to the "bell-mouth" shape expansion size, the surrounding area is appropriately increased to determine the size of the expansion data set, and CNC milling is used to complete the cutting and file and deburr.

[0023] Step 2: Spinning. First, complete the installation of the spinning equipment: install the clamping end of the spinning mold body A1 into the three-jaw chuck of the spinning bed, use a wrench to clamp the spinning die, then place the milled blank on the spinning die, and visually check to ensure that the blank is in the center of the spinning die; push the spinning tailstock, and push the tailstock ejector pin against the spinning die top plate 2 to clamp the blank; manually turn the three-jaw chuck, and use the pointer of the stylus disk to contact the edge of the blank to determine the position of the blank. After completing the above installation, start the motor of the spinning bed, start the rotating spindle of the spinning bed, so that the spindle of the spinning bed drives the spinning die to rotate rapidly, and manually control the control lever of the tool holder to make the rotating wheel or spinning rod fixed on the tool holder realize axial and radial movement, and make the rotating wheel or spinning rod contact the edge of the blank, and realize axial and radial feeding movement. The sheet metal bends under continuous feeding pressure, and gradually covers the surface of the spinning die to form. After the part is formed, manually control the control lever of the tool holder to withdraw the spinning wheel or spinning rod on the tool holder. Turn off the spinning bed and rotate the spindle, loosen the fixing screw of the tailstock, separate the spinning die, and remove the spinning process parts.

[0024] Step 3: Cutting the bottom wall of the straight line segment. Use turning or sawing to remove the bottom wall of the straight line segment of the formed spinning process part 3;

[0025] Step 4: Manual forming. Separate the cover plate 5 of the tire, remove the core 6, put the spun process part 3 into the tire body B4, close the cover plate 5, and manually apply pressure to the cover plate 5 to force the cover plate 5 to move toward the tire body B4, so as to achieve the fit between the part and the tire body. The force applied during the forming process of the part will cause the diameter of the straight section tube to deform. The core 6 can be used to assist in the forming and support the part tube wall from the inside to prevent the tube from deforming or even collapsing during the forming process. After the forming is completed, the cover plate 5 is separated. At this time, the part fits tightly with the tire body and is difficult to remove. The part can be pushed out from the bottom of the tire body B4.

[0026] Step 5: Cut the part shape according to the part edge line on the tire body B4, and use a file and sandpaper to ensure that the surface finish meets the design drawing requirements.

[0027] Step 6: Measure the inner diameter of the straight section of the conduit and check whether there are cracks on the "bell mouth"; complete the above steps to obtain the actual part in the final state.

Claims

1. A method for manufacturing a "bell-mouth" shaped aluminum alloy pipe part, characterized in that: The method comprises the following steps: Step 1: CNC milling and cutting According to the "bell-mouth" shape expansion size, the surrounding margin is added to determine the size of the expansion data set, and CNC milling is used to complete the cutting and filing and deburring. Step 2: Spinning A spinning die is used to spin-form a spinning process part, and a "bell-mouth" pipe end is simplified into a regular flange whose normal line coincides with the normal line of a straight line segment; the spinning die comprises a body A (1) and a top plate (2); wherein the working end diameter of the body A (1) is the same as the inner diameter of the spinning process part, and the length is longer than the spinning process part; the clamping end is used for clamping on a three-jaw chuck of a spinning lathe; the top plate (2) has the same diameter as the working end diameter of the body A (1); a conical hole is provided at the center of the top plate (2) end for cooperating with the spinning tailstock ejector pin to clamp the spinning workpiece; During forming, first complete the installation of the spinning equipment: install the clamping end of the spinning die body A (1) into the three-jaw chuck of the spinning bed, use a wrench to clamp the spinning die, then place the milled blank on the spinning die, and visually check to ensure that the blank is in the center of the spinning die; push the spinning tailstock, and push the tailstock ejector pin against the spinning die top plate (2) to clamp the blank; manually rotate the three-jaw chuck, and use the pointer of the stylus disk to touch the edge of the blank to determine the position of the blank; after completing the above installation, start the motor of the spinning bed, and start the main rotation of the spinning bed The spindle of the spinning bed drives the spinning die to rotate rapidly, and the control lever of the tool holder is manually controlled to make the rotating wheel or spinning rod fixed on the tool holder realize axial and radial movement, and make the rotating wheel or spinning rod contact the edge of the blank, and realize axial and radial feeding movement. The sheet metal is bent under continuous feeding and pressure, and gradually covers the surface of the spinning die to form; after the forming is completed, the control lever of the tool holder is manually controlled to withdraw the rotating wheel or spinning rod on the tool holder; the rotating spindle of the spinning bed is turned off, the fixing screw of the tailstock is loosened, the spinning die is separated, and the spinning process parts are removed; Step 3: Cut the bottom wall of the straight line segment The straight line bottom wall of the formed spinning process part is removed by turning or sawing; Step 4: Manual Forming Manual forming is achieved by using a mold, the mold comprising a carcass B (4), a cover plate (5), a core (6) and a positioning pin (7); wherein the carcass B (4) is designed according to the outer profile of the part, and the cover plate (5) is designed according to the "bell mouth" inner profile of the part; the relative positions of the carcass B (4) and the cover plate (5) are determined by the positioning pin (7) to ensure that there is no relative displacement between the two during the forming process; During forming, firstly, the spinning process part is placed in the carcass B (4), the cover plate (5) is closed, and pressure is manually applied to the cover plate (5) to force the cover plate (5) to move toward the carcass B (4), thereby achieving the part and the carcass fitting; during the forming process of the part, the force applied will cause the straight section tube diameter to deform, and the core (6) is used to assist the forming and support the part tube wall from the inside to prevent the tube from deforming or even collapsing during the forming process; after the forming is completed, the cover plate (5) is separated and the part is taken out; Step 5: Cut the part shape according to the part edge line on the mold body B (4), and file and polish with sandpaper to ensure that the surface finish meets the design drawing requirements; Step 6: Measure the inner diameter of the straight section of the conduit, check whether there are cracks on the "bell mouth", and obtain the actual part in its final state.

2. The manufacturing method according to claim 1, characterized in that: The working end of the carcass A (1) is 10-20 mm longer than the spinning process part, and the clamping end has a larger diameter than the working end. The depth of the conical hole at the end of the top plate (2) is 6 mm and the angle is 60°.

3. The manufacturing method according to claim 1 or 2, characterized in that: The tire mold described in step 4 also includes a lifting eye screw (8), which is installed on the tire body B (4) for easy transportation.

4. The manufacturing method according to claim 1 or 2, characterized in that: In the spinning mold, the carcass A (1) is made of Q235, and the top plate (2) is made of cloth-reinforced bakelite.

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