Machining method of spaceflight porous structural part

Abstract

The invention discloses a processing method of a spaceflight porous structural part. The processing method comprises the following steps: calculating the size of an unfolded material; preparing an unfolding material by using a laser cutting machine; performing manual incremental forming; correcting: correcting by using a rubber bag forming machine and a correcting mold; and measuring the size of the corrected part, checking whether the part is qualified or not, and if not, adjusting the size of the unfolded material according to a measurement result and repeating the previous steps. The method is very suitable for single-piece production, the die cost is low, and only one set of simple local forming concave-convex die for a forming press and a half die for shape correction are needed; according to the manual incremental forming method, the problem of springback of the part can be conveniently solved by increasing forming passes, and mold repairing is avoided; the universality is high, and one set of local forming concave-convex die can be used for various parts with different thicknesses and similar molded surfaces; and the wall thickness uniformity and the thinning condition are better than those of spinning, deep drawing and traditional incremental forming, and the surface is free of wrinkles and is better than that of die stamping forming.

Description

Technical Field

[0001] The invention belongs to the technical field of sheet metal forming and relates to a method for processing aerospace porous structural parts. Background Art

[0002] The arc plate is a 2mm thick stainless steel spherical crown structure sheet metal. It is an important structural component in the new rocket tank energy absorber assembly. It plays the role of buffering fluid and evenly distributing leakage. There are many normal openings distributed on it. In order to ensure the structural strength, each layer of small holes is not concentric radial openings. Instead, each outward layer requires the reference holes of the circular array to be staggered 90° and arranged outward in an alternating manner.

[0003] Similar structural parts are common in the home appliance and kitchenware industry. Metal products are usually thinner, with a thickness of no more than 1mm. The processing method of spinning + die punching is generally used, while plastic products are usually processed by injection molding. However, in the aerospace field, arc plate parts are produced in very small batches and are single-piece production. If the traditional processing method is used, the mold investment cost is too high and punching is difficult. If the method of lower hole blank + deep drawing or progressive forming + trimming is used, the hole deformation degree is large, micro cracks are easily generated at the edge of the hole, the wall thickness consistency is poor, and materials are wasted. If the method of lower hole blank + die stamping is used, due to the small radius and large depth of the part, circumferential compression instability and wrinkling are very likely to occur, resulting in serious deformation of the small hole and reduced structural strength. Therefore, for the above-mentioned arc plate parts, it is necessary to propose a processing method with low processing cost and unaffected structural strength. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for processing aerospace porous structural parts.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for processing aerospace porous structural parts comprises the following steps:

[0007] S1. Calculate the size of the unfolded material. The unfolded radius size is calculated according to ((part neutral layer area / π) 1 / 2 +(part maximum projected area / π) 1 / 2 ) / 2, the pitch circle and short axis of the small hole in the developed material are scaled according to the developed shape diameter / arc length of the half-section line, and the long axis of the small hole is scaled according to the pitch circle radius on the part / the pitch circle radius of the developed material;

[0008] S2, using a laser cutting machine to prepare the unfolded material;

[0009] S3, manual progressive forming: Use a forming press, hold the outer edge of the unfolded material with both hands, and rotate and unfold it with each forming interval of the press, hold it alternately, and evenly and progressively cooperate, starting from the center of the blank, and expanding outward layer by layer until the outermost layer;

[0010] S4, shape correction: use a rubber bag forming machine and a shape correction mold to correct the shape;

[0011] S5, measure the size of the parts after the correction, and check whether they are qualified. If they are unqualified, adjust the size of the unfolded material according to the measurement results and repeat steps S1 to S4.

[0012] As a preferred method, in step S3, during the manual progressive forming process, the press is paused and the forming condition is judged using a template inside the cut surface. If the bending degree of a certain circle is insufficient, the forming passes of the circle and adjacent areas are increased in the order of gradually forming from the unfolded material near the middle area to the outer area, so that the material flows to the outer edge.

[0013] As a preferred embodiment, in step S2, the cutting sequence is to make holes first and then cut the outer shape, and the hole making sequence is to cut layer by layer from the center of the circle to the outside.

[0014] More preferably, in step S2, the hole making uses a fly cutting function, and nitrogen is used as the cutting auxiliary gas.

[0015] As a preferred method, in step S4, the shaping mold is clamped, the semi-finished part is placed in the center of the shaping mold to ensure symmetry on all sides, a rubber pad is placed on the semi-finished part, the rubber bladder forming machine is started to move the part to the forming area, 35 MPa is applied, and the shaping is completed after the pressure is maintained for 5 seconds.

[0016] As a preferred method, in step S3, the local forming mold is installed on a forming press, the punch of the local forming mold is installed below the unfolded material, and the die of the local forming mold is installed above the unfolded material, the die of the local forming mold is kept stationary, and the punch of the local forming mold moves up and down with the forming press. The upper and lower ends of the die and punch of the local forming mold are provided with interfaces connected to the equipment, and the working surface is a spherical surface considering the rebound of the part, and the spherical radius of the punch is smaller than the spherical radius of the die, which is smaller than the spherical radius of the part.

[0017] The present invention has the following advantages:

[0018] The present invention is very suitable for single-piece production, with low mold cost and only requires a set of simple local forming concave-convex molds for a forming press and a half mold for shape correction; the manual progressive forming method can easily overcome the problem of part springback by increasing the forming passes, thus avoiding the need to repair the mold; it has strong versatility, and a set of local forming concave-convex molds can be used for parts of various thicknesses and similar profiles; and the wall thickness uniformity and thinning are better than those of spinning, deep drawing and traditional progressive forming, with no wrinkles on the surface, which is better than mold stamping. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the principle diagram of the present invention;

[0020] Figure 2 A three-dimensional axonometric view of the finished part;

[0021] Figure 3 It is a schematic diagram of the unfolded material structure;

[0022] Figure 4 It is a schematic diagram of the half-section structure of the forming process;

[0023] Figure 5 This is the cross-sectional change diagram of the part during manual incremental forming;

[0024] Figure 6 This is a schematic diagram of the shape correction mold structure.

[0025] In the figure: 1 is the part, 2 is the unfolded material, 3 is the punch of the local forming mold, 4 is the concave mold of the local forming mold, 5 is the running direction of the concave mold, 6 is the rotation direction of the unfolded material, 7 is the cross-sectional line of the part forming process, 8 is the shaping mold, and 9 is the semi-finished part. DETAILED DESCRIPTION

[0026] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] Example:

[0029] The inner diameter of part 1 is SR300mm, the inner diameter of the mouth is Φ400mm, and the material is 2mm thick 1Cr18Ni9Ti stainless steel plate. The processing method is:

[0030] Step 1: Calculate the size of the unfolded material 2. Considering the extension of the forming material, the unfolded outer radius size is calculated according to ((part surface area / π) 1 / 2 +(part maximum projected area / π) 1 / 2) / 2, the unfolded outer radius size is (214+200) / 2=207, the small hole pitch circle and the small hole minor axis radius are scaled according to the unfolded outer diameter / half-section line arc length, and the small hole major axis is scaled according to the pitch circle radius on part 1 / the pitch circle radius on unfolded material 2.

[0031] Step 2: laser cutting. Use a laser cutting machine to prepare the unfolded material 2. The cutting sequence is to make holes first and then cut the shape. The hole making sequence is to cut layer by layer from the center of the circle to the outside.

[0032] The fly cutting function is used for hole making, which can double the material cutting efficiency. Nitrogen is used as the auxiliary cutting gas, which is helpful to reduce the thermal deformation during cutting.

[0033] Step 3: Manual progressive forming: install the local forming mold to the Yago pressure forming machine KF665, install the local forming mold convex mold 3 at the bottom, and install the local forming mold concave mold 4 at the top, keep the local forming mold convex mold 3 stationary, and the local forming mold concave mold 4 moves up and down with the equipment, and the concave mold running direction 5 is as follows: Figure 4 As shown, the outer edge of the unfolded material 2 is held by both hands and rotated continuously in one direction. A feasible unfolded material rotation direction 6 is as follows Figure 4 As shown, both hands hold alternately and cooperate evenly and progressively, starting from the center of the unfolded material 2, and expanding outward layer by layer until the outermost layer. The cross-sectional line 7 of the part forming process changes as shown in FIG. Figure 5 During the process, the internal sample of the cut surface is used several times to observe the forming situation. If the bending degree of a certain circle is not enough, the forming passes of the circle and the adjacent areas are increased. The order is to gradually form the area from the center of the unfolded material 2 to the outer area, so that the material flows to the outer edge.

[0034] Step 4, the shaping step, the equipment uses a rubber bag forming machine, clamps the shaping mold 8, places the semi-finished part 9 in the center of the shaping mold 8, ensures symmetry on all sides, puts a rubber pad on the semi-finished part 9, starts the equipment to move the part to the forming area, pressurizes 35MPa and maintains the pressure for 5s to complete the shaping.

[0035] Step 5, take out the calibrated part 1, measure the dimensions, and all dimensions are within the tolerance range, and the part is qualified.

[0036] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A method for processing aerospace porous structural parts, characterized in that: The steps include: S1. Calculate the size of the unfolded material. The unfolded radius size is calculated according to ((part neutral layer area / π) 1 / 2 +(maximum projected area of ​​part / π) 1 / 2 ) / 2, the pitch circle and short axis of the small hole in the developed material are scaled according to the developed shape diameter / arc length of the half-section line, and the long axis of the small hole is scaled according to the pitch circle radius on the part / the pitch circle radius of the developed material; S2, using a laser cutting machine to prepare the unfolded material; S3, manual progressive forming: Use a forming press, hold the outer edge of the unfolded material with both hands, and rotate and unfold it with each forming interval of the press, hold it alternately, and evenly and progressively cooperate, starting from the center of the blank, and expanding outward layer by layer until the outermost layer; S4, shape correction: use a rubber bag forming machine and a shape correction mold to correct the shape; S5, measure the size of the parts after the correction, and check whether they are qualified. If they are unqualified, adjust the size of the unfolded material according to the measurement results and repeat steps S1 to S4.

2. The method for processing aerospace porous structural parts according to claim 1, characterized in that: In step S3, during the manual progressive forming process, the press is paused and the forming condition is judged using the template inside the cut surface. If the bending degree of a certain circle is not enough, the forming passes of the circle and the adjacent areas are increased, and the order is to gradually form the unfolded material from the middle area to the outer area, so that the material flows to the outer edge.

3. The method for processing aerospace porous structural parts according to claim 1, characterized in that: In the step S2, the cutting sequence is to make holes first and then cut the outer shape, and the hole making sequence is to cut layer by layer from the center of the circle to the outside.

4. The method for processing aerospace porous structural parts according to claim 3, characterized in that: In the step S2, the hole is made using the fly cutting function, and the cutting auxiliary gas is nitrogen.

5. The method for processing aerospace porous structural parts according to claim 1, characterized in that: In step S4, the shaping mold is clamped, the semi-finished part is placed in the center of the shaping mold to ensure symmetry on all sides, a rubber pad is placed on the semi-finished part, the rubber bag forming machine is started to move the part to the forming area, 35 MPa is applied, and the shaping is completed after the pressure is maintained for 5 seconds.

6. The method for processing aerospace porous structural parts according to claim 1, characterized in that: In step S3, the local forming mold is installed on the forming press, the male mold of the local forming mold is installed below the unfolded material, and the female mold of the local forming mold is installed above the unfolded material. The female mold of the local forming mold is kept stationary, and the male mold of the local forming mold moves up and down with the forming press.

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