Method and device for forming rubber bag of frame plate part for spaceflight

Abstract

The invention belongs to the field of aerospace sheet metal part processing, and particularly relates to a rubber bag forming method of a frame plate part for aerospace, which comprises the following steps: S1, designing two sets of forming dies; s2, a part unfolding material is determined according to the part appearance and the basic sheet metal part unfolding rule; s3, forming a rubber bag in the pass 1; s4, forming a rubber bag in the second pass; and S5, checking the obtained part to obtain a qualified part. According to the method, two sets of tire-cover plate molds are designed, part unfolding blanks are reasonably arranged, and a complex frame plate part with the characteristics that the flange is convex in different directions, the flange is provided with a recess and a notch and a web is provided with a protrusion is formed through rubber bag flexible forming equipment, so that the problems of wrinkling, cracking and the like when the frame plate part is formed are solved; the forming efficiency, the surface quality and the product consistency of the frame plate parts are improved, the percent of pass is increased to 100%, the manual intervention degree in the forming process is reduced, and the labor intensity of workers is reduced.

Description

Technical Field

[0001] The invention belongs to the field of aerospace sheet metal processing, and in particular relates to a rubber bag forming method and device for aerospace frame plate parts. Background Art

[0002] Sheet metal forming plays an irreplaceable role in the field of modern manufacturing, especially in the aerospace field. With the continuous changes in product demand, the new generation of sheet metal parts are required to be light in weight, high in strength, high in performance and low in manufacturing cost. This requires continuous exploration of new materials, new processes and new equipment to shorten the product manufacturing cycle and achieve efficient, fast, flexible and precise forming.

[0003] At present, a large number of sheet metal parts are used in liquid rocket products, including frame plates, which are mainly used for bearing and supporting. These parts are not only complex in shape, but also of various types and small batches. For these parts that are difficult to form, the mold forming method is generally used. Manual forming has low production efficiency, high labor intensity, and poor surface quality and consistency of parts. The schematic diagram of the frame plate parts is shown in the attached figure. Figure 1 As shown in the figure, the frame plate parts mainly have the following structural features: 1) convex curved edges in different directions; 2) sunken notches at the curved edges; 3) convex structures at the webs. The complex structure of the frame plate determines that most forming methods are not suitable for forming this part, and the advantage of the rubber bag flexible forming method is that it can form this type of curved curved edge products.

[0004] In the existing rubber bladder forming technology, the patent with publication number CN112828118A is named as a method for controlling wrinkling of parts with convex bending structure characteristics during rubber bladder forming, which mainly controls wrinkling by appropriately increasing process expansion margin and side pressure blocks; the patent with publication number CN108237168B is named as a method for forming a rubber bladder of an aircraft convex bending reinforcement frame part, which mainly achieves the effect of mold sticking and wrinkle prevention of convex bending parts by increasing the expansion process surplus and the mold suction groove structure; although the above two inventions solve the problem of rubber bladder forming of convex bending parts, their part structures are simple, only involving one-way convex bending, and their expansion materials have process surplus that needs to be removed later. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method and device for forming a rubber bag of aerospace frame plate parts. The method reduces the degree of manual intervention in the forming process, reduces the labor intensity of workers, solves the problems of wrinkling and rupture during the forming of the curved edge rubber bag, improves the parts production efficiency, product surface quality and product consistency, and increases the pass rate to 100%.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for forming a rubber bag of an aerospace frame plate part comprises the following steps:

[0008] S1. Design two sets of forming molds according to the shape and size of the parts. Positioning holes corresponding to the unfolding of the parts need to be opened on both the tire and the cover plate;

[0009] S2. Determine the unfolded material of the part according to the part shape and the basic rules for unfolding sheet metal parts, adjust the size of the notch to make it shrink toward the center of the notch, and open positioning holes on the unfolded material of the part;

[0010] S3, rubber bag forming in pass 1, placing the unfolded sheet obtained in step S2 on the first forming die, starting the rubber bag device to apply pressure to the sheet to form it, and taking out the semi-finished parts after forming;

[0011] S4, rubber bag forming of pass 2, placing the semi-finished part with half-bent edge and protrusion at the web obtained in S3 on the second forming die, starting the rubber bag equipment, and forming the other side of the different-direction bent edge;

[0012] S5. Check the parts obtained in S4 to obtain qualified parts.

[0013] Preferably, in S2, the notch is adjusted to shrink by 0.5-1 mm toward its center line, and the shrinkage decreases from the edge to the center.

[0014] Preferably, in S3 and S4, the rubber bag forming pressure is 20-50 MPa, and the pressure holding time is 5-30 s.

[0015] A forming mold for a rubber bag forming method of a frame plate part for aerospace use, the forming mold comprising a first forming mold and a second forming mold; the first forming mold comprises a tire A and a cover plate A; the second forming mold comprises a tire B and a cover plate B; the tire A, cover plate A, tire B, and cover plate B are all provided with positioning holes corresponding to the unfolded material, and are positioned using shoulder positioning pins; the tire A, cover plate A, tire B, and cover plate B are all provided with protrusions and corresponding concave structures; the cover plate B is also provided with an avoidance groove and a protrusion avoidance groove. The tire A, cover plate A, and cover plate B are all designed with corresponding protrusions or corresponding concave structures, and the "tire A-cover plate A" plays a role in the problem of protrusion forming in place, and the cover plate B plays a role in auxiliary positioning and giving way to the already formed protrusion structure.

[0016] Preferably, the height of tire A is 15 to 30 mm higher than the height of the part's curved edge, and the height of tire B is 15 to 30 mm higher than the height of the part's curved edge.

[0017] Preferably, the length of the shouldered positioning pin is greater than or equal to the cover plate thickness + blank thickness + 5-10mm; the diameter of the shouldered positioning pin is 0.1-0.3mm smaller than the size of the unfolded positioning hole; the thickness of the shoulder of the positioning pin is 2-5mm, and the surrounding area is in arc transition, so as to avoid fatigue and damage to the rubber bag.

[0018] Preferably, the size of the groove on the cover plate B should cover the size of the bent edge after forming in pass 1. That is, the groove on the cover plate B protects the formed bent edge from the pressure of the rubber bag;

[0019] Preferably, when the first forming device is assembled and formed, the size of the cover plate A at the forming edge is indented 3 to 8 mm inwards compared to the size of the tire A. That is, the curved edge is left free so that the rubber bag is in direct contact with it, which facilitates better forming of the curved edge.

[0020] Preferably, a vent hole is formed at the concave structure of the tire A to discharge the gas that may be present there.

[0021] The present invention has the following advantages:

[0022] 1) Compared with the original manual forming method, the present invention greatly reduces the labor intensity of workers, improves production efficiency, and increases the qualified rate of parts to 100%; compared with manual forming, due to the notch feature at the bending edge, and because the material at the bending edge has space to flow, the stress can be released, so that the mold fit of the parts is greatly improved;

[0023] 2) The parts formed by this method have good surface quality and consistency, avoiding uneven wall thickness and slight cracks caused by uneven force during manual forming, and only slight local trimming is required to meet the part mold fit requirements;

[0024] 3) Compared with manual forming, the method of the present invention can directly open the notch in place when the blank is expanded, avoiding the removal of process margin after forming, reducing the forming process and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the frame plate parts of the present invention;

[0026] Figure 2 It is a schematic diagram of the expansion of the rubber bag forming of the frame plate parts of the present invention;

[0027] Figure 3 This is a schematic diagram of the forming process of pass 1 of the present invention;

[0028] Figure 4 This is a semi-finished product part diagram after forming in pass 1 of the present invention;

[0029] Figure 5 It is a schematic diagram of the forming process of pass 2;

[0030] Figure 6 This is a schematic diagram of cover plate B.

[0031] In the figure: 1. raised structure; 2. notch; 3. depression; 4. different-direction bending edge; 5. parts; 6. tire A; 7. cover A; 8. positioning pin; 9. exhaust hole; 10. raised feature; 11. cover B; 12. tire B; 13. avoidance groove; 14. avoidance raised groove; 15. positioning through hole. DETAILED DESCRIPTION

[0032] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0033] 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.

[0034] Attached Figure 1 It is a typical schematic diagram of frame plate parts. The total length of the frame plate parts is about 950-1200mm. The frame plate parts have a different bending edge structure. The bending edge height is generally 27mm with depression and notch, and the bending edge height on the other side is 45mm. The part is 7A09 aluminum alloy plate with a thickness of 2mm.

[0035] The present invention provides a forming device and a forming method for a frame plate part for aerospace use with an asymmetric convex curved edge, a sunken notch at the curved edge, and a convex structural feature at the web. The process method mainly comprises the following steps:

[0036] S1, because the part has a convex structure with different bending edges, two sets of "tire-cover plate" molds are designed according to the shape and size of the part, and they are named "tire A-cover plate A" for pass 1 and "tire B-cover plate B" for pass 2. Positioning holes corresponding to the unfolding of the part need to be opened on both the tire and the cover plate;

[0037] S2, determine the unfolded material of the part according to the part shape and the basic rules for unfolding sheet metal parts, pay attention to adjusting the size of the notch so that it shrinks toward the center of the notch, and open positioning holes on the unfolded material of the part;

[0038] S3, placing the unfolded sheet obtained in step S2 on tire A, placing cover plate A on the sheet, and positioning them with shoulder pins, placing tire A-unfolded sheet-cover plate A on the workbench of the rubber bag forming machine in order from bottom to top, starting the rubber bag equipment to apply pressure to the sheet to form, and taking out the semi-finished parts after forming;

[0039] S4, placing the semi-finished part with the half-bend and the protrusion at the web obtained in S3 on the tire B, and placing the cover plate B on the semi-finished part with the half-bend, and the cover plate B is provided with a protective groove to protect the half-bend that has been formed so as not to be affected by the forming pressure; similarly positioning with the shoulder pin, starting the rubber bag device, and forming the other side of the different-direction bend;

[0040] S5, check whether the parts obtained in S4 need to be partially corrected, and if necessary, correct them to obtain qualified parts.

[0041] In the embodiment of the present invention, tire A, cover plate A, and cover plate B are all designed with corresponding protrusions or corresponding concave structures. "Tire A-cover plate A" plays a role in forming the protrusions into place, and cover plate B plays a role in assisting positioning and making way for the protrusions that have formed a row. The above tire A, cover plate A, and cover plate B are all designed with corresponding protrusions or corresponding concave structures. "Tire A-cover plate A" plays a role in forming the protrusions into place, and cover plate B plays a role in assisting positioning and making way for the protrusions that have formed a row. The height of tire A is 15 to 30 mm higher than the height of curved edge 1, and the height of tire B is 15 to 30 mm higher than the height of curved edge 2. Exhaust holes are opened at the concave structure of tire A to exhaust the gas that may exist there.

[0042] In the embodiment of the present invention, the size of the groove on the cover plate B should cover the size of the bent edge after forming in pass 1, that is, the groove on the cover plate B plays a role in protecting the formed bent edge from the pressure of the rubber bag;

[0043] In the embodiment of the present invention, the above-mentioned unfolded material needs to adjust the unfolded shape and size of the curved edge notch based on the theoretical unfolded material, that is, the notch needs to be reduced by 0.5 to 1 mm toward its center line, and the amount of reduction from the edge to the center is from large to small, leaving a material margin for the sunken structure;

[0044] In the embodiment of the present invention, the length of the shouldered positioning pin is greater than or equal to the cover plate thickness + blank thickness + (5-10mm), the diameter of the shouldered positioning pin is 0.1-0.3mm smaller than the size of the unfolded positioning hole, the thickness of the shoulder of the positioning pin is 2-5mm, and the surrounding arc transition is avoided to avoid fatigue and damage to the rubber bag;

[0045] When "tire A-cover plate A" is assembled and formed, ensure that the size of cover plate A at the forming edge is indented 3 to 8 mm inward than the size of tire A, that is, leave the curved edge so that the rubber bag is in direct contact with it, which is convenient for better forming of the curved edge; the rubber bag forming pressure range of pass 1 and pass 2 is 20 to 50 MPa; the holding time range is 5 to 30 seconds.

[0046] The specific forming steps are as follows:

[0047] 1) First, according to the attached Figure 1Designed for the "tire A-cover A" used in the first forming pass and the "tire B-cover B" used in the second forming pass. For specific structure, see the attached Figure 3 And attached Figure 5 ; Both the tire and the cover plate are provided with positioning holes, the size of the positioning holes is φ5.2mm, the thickness of the tire A is 55mm, the thickness of the cover plate A is 18mm, the thickness of the tire B is 70mm, the thickness of the cover plate B is 42mm, and the cover plate B has an avoidance groove structure with a depth of 28mm and a width of 16mm;

[0048] 2) Secondly, according to the attached Figure 1 Parts drawing and sheet metal unfolding rules to draw the parts process unfolding drawing, that is, Figure 2 . Because of the sunken structure at the notch, the notch should be expanded inward by 0.5-1mm when drawing the expansion; note that the process positioning hole on the notch needs to be expanded. Generally, it is φ5.2mm, and the diameter of the shoulder pin is φ5.0mm;

[0049] 3) Start the rubber bag equipment, open the workbench, place "tire A - part unfolded material - cover plate A" on the workbench in order from bottom to top, and position it with shoulder pins. Place a rubber plate for protecting the equipment bag on the cover plate, set the forming pressure to 40MPa, and hold the pressure for 20s; under the action of pressure, the blank gradually forms a convex curved edge 1 with a sunken and notched shape and a convex structure. The forming process and results are shown in the attached Figure 3 And attached Figure 4 ;

[0050] 4) After the holding time is over, open the workbench, take out the semi-finished parts and tire A cover A, and place "tire B-semi-finished parts-cover B" on the workbench from bottom to top, and position them with shoulder pins; cover B avoids the groove to protect the formed bend, set the forming pressure to 40MPa, hold the pressure for 20s, and form the other side of the bend in the opposite direction to the original bend under the pressure of the rubber bag; the structure of cover B is shown in the attached figure. Figure 6 , the forming process is shown in the attached Figure 5 ;

[0051] 5) Take out the formed parts and place them on tire A and tire B. Check the gap between the curved corners and the tires. If it is greater than 0.5mm, make manual corrections. Generally, the gap requirements are met and manual corrections are rarely required.

[0052] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for forming a rubber bag of a frame plate part for aerospace use, characterized in that: The following steps are involved: S1. Design two sets of forming molds according to the shape and size of the parts. Positioning holes corresponding to the unfolding of the parts need to be opened on both the tire and the cover plate; S2. Determine the unfolded material of the part according to the part shape and the basic rules for unfolding sheet metal parts, adjust the size of the notch to make it shrink toward the center of the notch, and open positioning holes on the unfolded material of the part; S3, rubber bag forming in pass 1, placing the unfolded sheet obtained in step S2 on the first forming die, starting the rubber bag device to apply pressure to the sheet to form it, and taking out the semi-finished parts after forming; S4, step 2 rubber bag forming, placing the semi-finished part with half-bent edge and protrusion at the web obtained in S3 on the second forming die, starting the rubber bag equipment, and forming the other side of the different-direction bent edge; S5. Check the parts obtained in S4 to obtain qualified parts.

2. A method for forming a rubber bag of a frame plate part for aerospace use according to claim 1, characterized in that: In S2, the notch is adjusted to shrink by 0.5 to 1 mm toward its center line, and the shrinkage from the edge to the center decreases from large to small.

3. The method for forming a rubber bag of a frame plate part for aerospace use according to claim 1, characterized in that: In S3 and S4, the rubber bag forming pressure is 20 to 50 MPa, and the holding time is 5 to 30 seconds.

4. A forming die for a rubber bag forming method of aerospace frame plate parts according to any one of claims 1 to 3, characterized in that: The forming mold includes a first forming mold and a second forming mold; the first forming mold includes a tire A and a cover plate A; the second forming mold includes a tire B and a cover plate B; the tire A, cover plate A, tire B, and cover plate B are all opened with positioning holes corresponding to the unfolded material, and are positioned using shoulder positioning pins; the tire A, cover plate A, tire B, and cover plate B are all provided with protrusions and corresponding recessed structures; the cover plate B is also provided with an avoidance groove and an avoidance protrusion groove with a positioning function.

5. A forming die according to claim 4, characterized in that: The height of the tire A is 15 to 30 mm higher than the height of the part's curved edge, and the height of the tire B is 15 to 30 mm higher than the height of the part's curved edge.

6. A forming die according to claim 4, characterized in that: The length of the shouldered positioning pin is greater than or equal to the cover plate thickness + blank thickness + 5 to 10 mm; the diameter of the shouldered positioning pin is 0.1 to 0.3 mm smaller than the size of the unfolded positioning hole; the thickness of the shoulder of the positioning pin ranges from 2 to 5 mm, and is surrounded by arc transitions.

7. A forming die according to claim 4, characterized in that: The size of the groove opened on cover plate B should envelop the size of the bent edge sinking after forming in pass 1.

8. A forming die according to claim 4, characterized in that: When the first forming device is assembled and formed, the size of the cover plate A at the forming edge is retracted inward by 3 to 8 mm compared to the size of the tire A.

9. A forming die according to claim 4, characterized in that: An exhaust hole is formed at the concave structure of the tire A.

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