Aluminum alloy covering cap part silica gel packaging and bending forming method

Abstract

A silica gel packaging, bending and forming method for an aluminum alloy covering cap part belongs to the technical field of machinery and comprises the following steps: processing an aluminum alloy plate by adopting a three-axis numerical control processing center to obtain a covering cap part unfolding working procedure piece; manufacturing a mold for silica gel packaging according to the boundary dimension of the opening cover part unfolding process part, and performing silica gel packaging by using the mold; after being packaged and cured through silica gel, the covering cap part unfolding working procedure piece is placed in a pre-forming die, and the covering cap is bent, pressed and formed into an arc-shaped structural piece through die assembly and pressure maintaining forming of a male die and a female die; after the covering cap is preformed, a shape correcting mold is adopted for conducting shape correcting and forming on the covering cap, the shape correcting mold is subjected to cold pressing shape correcting, the forming springback error of the covering cap is eliminated, and therefore the covering cap skin with the consistent boundary dimension is obtained. According to the invention, a multi-layer stacked structure form that the metal covering cap is tightly wrapped by the silica gel material is realized, and the covering cap can be molded, bent and formed by adopting a common metal plate molding, bending and forming process method.

Description

Technical Field

[0001] The invention relates to a silicone encapsulation bending forming method for an aluminum alloy mouth cover part, belonging to the technical field of machinery. Background Art

[0002] The flap skin parts are unfolded and calculated according to the required technical status to obtain the three-dimensional unfolding model of the flap, that is, the flap unfolding process part model. According to this model, the shape and each hole are machined by a three-axis machining center machine tool to obtain the process of the flap unfolding state. The flap unfolding process parts are placed in the silicone encapsulation mold and encapsulated by silicone vulcanization of the mold, that is, the flap unfolding process parts are tightly wrapped with silicone vulcanization. After a period of silicone curing, the flap unfolding process parts after silicone encapsulation are placed in the preforming mold, and the preforming of the flap is completed by compression molding, that is, the preforming of the flap is realized. Next, the preformed flap is taken out of the silicone wrapping sleeve, and the flap shape close to the design size requirements is obtained. The flap is further calibrated using the flap correction mold to eliminate the compression springback deformation and ensure the flap shape size requirements.

[0003] The application of this method can realize the precise forming of complex cover parts of heat-treatable strengthened aluminum alloy, avoiding the process method that such complex parts can only be formed first and then chemically milled to reduce the cavity. The process production cycle of chemically milled to reduce the cavity is long, the cost of chemical milling is high, and the material utilization rate is only 50%. At the same time, there are various uncontrollable quality risks, which can easily cause the size of the cover to be out of tolerance. It solves the problem that the springback deformation after forming is large and the dimensional accuracy cannot be guaranteed due to the inability to use the heating hot forming process method due to material performance requirements. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and provide a silicone encapsulation bending forming method for an aluminum alloy mouth cover part, so as to realize a multi-layer stacking structure in which the silicone material tightly wraps the metal mouth cover, and the mouth cover can be molded and bent by a general sheet metal mold bending forming process method.

[0005] The technical solution of the present invention is: a method for bending and forming an aluminum alloy cover part with silicone encapsulation, comprising:

[0006] According to the three-dimensional model of the unfolding process part of the cover part and its external dimensions, the CNC machining center processing program file is compiled, and the aluminum alloy plate is processed by the three-axis CNC machining center to obtain the unfolding process part of the cover part;

[0007] A mold for silicone encapsulation is manufactured according to the outer dimensions of the unfolded process parts of the cover parts, and the mold is used for silicone encapsulation;

[0008] After the unfolding process of the mouth cover parts is cured by silicone encapsulation, it is placed in the preforming mold, and the male and female molds are closed and pressed to form the arc-shaped structural parts of the mouth cover, so as to complete the preforming of the mouth cover. After the preforming is completed, the silicone sleeve is removed;

[0009] After the mouth cover is preformed, a shaping die is used to shape the mouth cover, and the shaping die is cold-pressed to eliminate the springback error of the mouth cover forming, so as to obtain a mouth cover skin with consistent outer dimensions.

[0010] Furthermore, according to the outer dimensions of the mouth cover skin parts, the neutral layer of the mouth cover is used as a reference for calculation of the mouth cover expansion, and the expanded outer dimensions of the mouth cover are calculated using the parallel line expansion method.

[0011] Furthermore, the method of calculating the unfolded shape and unfolded size of the mouth cover by the parallel line unfolding method includes: regarding the surface of the part as being composed of countless mutually parallel element lines, taking the area enclosed by two adjacent element lines and their two ends as a plane, and drawing the true size of each small plane in sequence on the plane to obtain the surface unfolded diagram of the part. The shapes that can be unfolded by parallel lines are all cylinders.

[0012] Further, the use of a mold for silicone encapsulation includes:

[0013] Install the cover expansion process part in the silicone packaging mold, and use the positioning pins and the holes on the cover process part for effective positioning;

[0014] Silicone sealing of the mouth cover.

[0015] Furthermore, the thickness of the silicone between the upper and lower surfaces and the molded stress-bearing forming surface is 8 mm, and the width of the silicone wrapping process in the front, back, left and right directions is 25 mm.

[0016] Furthermore, the silicone encapsulation of the mouth cover includes: taking 5-6 kg of mold silicone, loading 1 / 2 of the silicone that is evenly stirred and has a certain curing effect into the silicone encapsulation mold, installing the mouth cover process parts on the four positioning pins for installation and positioning, and introducing the remaining 1 / 2 of the silicone into the silicone encapsulation mold. Install the silicone encapsulation mold cover plate on the silicone encapsulation mold, use a hydraulic press to compact the silicone encapsulation mold to achieve complete silicone encapsulation of the mouth cover, and remove the packaged mouth cover from the silicone encapsulation mold after curing for 30 minutes.

[0017] Furthermore, the mold silicone and the curing agent are configured in a ratio of 25:1 and are fully stirred evenly, and the curing agent is configured while stirring.

[0018] Furthermore, after the arc surface of the forming mold contacts the outer surface of the silicone, the silicone undergoes volume elastic deformation, and the silicone fully fills the complex mouth cover cavity, thereby avoiding uneven force on the forming surface.

[0019] Furthermore, the springback error of the mouth cover forming is eliminated by cold pressing the shaping mold.

[0020] Furthermore, after the preforming is completed, the silicone sleeve is removed by manually cutting open the silicone sleeve.

[0021] The advantages of the present invention compared with the prior art are:

[0022] The present invention provides a mouth cover skin type part of an aluminum alloy with a complex shape and a lightened cavity. After the processing of the lightened cavity and the ribs is completed in advance, the parts are encapsulated with silicone to form a whole, so as to realize a multi-layer superimposed structure in which the silicone material tightly wraps the metal mouth cover, and the mouth cover can be molded and bent by a general sheet metal die-stamping and bending forming process. The process method of the present invention can realize the efficient and low-cost forming of mouth covers with complex shapes. Due to the use of silicone filling, the mouth cover can be formed by flat die-stamping without lightened cavities and ribs, wherein the mouth cover skin at the lightened cavity obtains effective wrapping support from the silicone material, avoiding the forming deformation of the mouth cover skin forming part without effective support during the molding process, and solving the problem that the mouth cover skin with complex shapes cannot be formed by a simple molding process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0024] Figure 1 A diagram of a mouth cover component of the present invention.

[0025] Figure 2 It is an expanded view of the mouth cover parts of the present invention.

[0026] Figure 3 This is a diagram of a silicone encapsulation mold for the mouth cover part of the present invention.

[0027] Figure 4 This is a silicone packaging diagram of the mouth cover parts of the present invention.

[0028] Figure 5 , 6 It is a diagram of the preforming process of the mouth cover parts of the present invention.

[0029] Figure 7 It is a schematic diagram of a forming die for a mouth cover part of the present invention. DETAILED DESCRIPTION

[0030] In order to better understand the above technical scheme, the technical scheme of the present invention is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical scheme of the present invention, rather than limitations on the technical scheme of the present invention. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0031] The following is a further detailed description of a silicone encapsulation bending forming method for an aluminum alloy cover part provided by an embodiment of the present invention in conjunction with the accompanying drawings of the specification. The specific implementation method may include:

[0032] The solution provided in the embodiment of the present invention includes some processing steps:

[0033] (1) Design calculation and preparation method of the cover expansion process parts.

[0034] According to the dimensions of the cover skin parts, see Figure 1 . Through technical analysis of its technical status requirements and external dimension accuracy requirements, the neutral layer of the flap is used as the basis for the flap unfolding calculation, and the parallel line unfolding method is used to calculate the unfolded external dimensions of the flap. The principle is to regard the surface of the part as composed of countless parallel element lines, and take the area enclosed by two adjacent element lines and the two ends as the plane. As long as the true size of each small plane is drawn on the plane in sequence, the surface unfolding diagram of the part can be obtained. The shapes that can be unfolded by parallel lines are all cylinders. The external dimensions of the unfolded process parts of the flap parts are shown in Figure 2 .

[0035] According to the three-dimensional model of the unfolding process part of the cover part and its external dimension requirements, a CNC machining center processing program file is compiled, and the aluminum alloy plate is processed by a three-axis CNC machining center to obtain the unfolding process part of the cover part.

[0036] (2) Silicone packaging method

[0037] According to the dimensions of the cover expansion process parts, a silicone encapsulation mold was designed and manufactured. Figure 3 , install the cover expansion process part in the silicone encapsulation mold, use the positioning pin and the hole on the cover process part for effective positioning, to ensure the position and size requirements of the cover expansion process part in the silicone encapsulation after silicone encapsulation, that is, the silicone thickness of the upper and lower surfaces from the molded stress forming surface is 8mm, and the width of the silicone encapsulation process is 25mm. Figure 4 .

[0038] For silicone encapsulation of the mouth cover, take 5-6 kg of mold silicone, and the mold silicone and curing agent are required to be configured in a ratio of 25:1 and fully stirred. The curing agent is required to be configured while stirring. The 1 / 2 silicone that is stirred evenly and has a certain curing effect is loaded into the silicone encapsulation mold. The mouth cover process parts are installed on the four positioning pins for installation and positioning, and the remaining 1 / 2 silicone is introduced into the silicone encapsulation mold. The silicone encapsulation mold cover plate is installed on the silicone encapsulation mold, and the silicone encapsulation mold is pressed by a hydraulic press to achieve complete silicone encapsulation of the mouth cover. After 30 minutes of curing, the encapsulated mouth cover is taken out from the silicone encapsulation mold.

[0039] (3) Cover expansion process parts and forming

[0040] The material of the mouth cover parts is aluminum alloy 2A12-H112, which has a high tensile strength ≥410MPa and an elongation δ5 ≥12%. This material has a large rebound deformation during the cold forming process. In order to further improve the forming contour accuracy and reduce the difficulty of subsequent correction work, the pre-deformation size of the rebound is calculated during the design of the forming process parts, and the forming process parts are designed to a certain pressing size to offset the rebound deformation of the mouth cover. Similarly, in the design process of the mouth cover forming mold and the correction mold, the rebound deformation is pre-designed in the mold structure, and the outer dimensions of the rebound deformation can be obtained through formula calculation as the basis for mold design.

[0041] Factors affecting the springback deformation:

[0042] 1) Mechanical properties of the sheet material. The springback angle is proportional to the yield strength of the material and inversely proportional to the elastic modulus of the material.

[0043] 2) The ratio of bending radius to material thickness R / t<5-10 has a larger springback angle for the molded arc cover, and the fillet radius also changes greatly, so the deformation needs to be considered during the mold design process. The punch fillet radius and forming angle can be calculated according to the calculation method of the elastic modulus and yield strength of the material. Figure 5 shown.

[0044]

[0045] Where r0 is the required forming radius of the part (mm)

[0046] r0=212mm

[0047] R m ——Forming radius of the punch (mm)

[0048] α0——The arc length center angle corresponding to the required forming radius r0 of the part (°)

[0049] α0=100°

[0050] α β ——The arc length center angle corresponding to the forming radius Rm of the punch (°)

[0051] t——Material thickness (mm)

[0052] t=5mm

[0053] σ s ——Material yield strength (MPa)

[0054] σ s =425MPa

[0055] E——Elastic modulus of the material (GPa), E=73GPa

[0056] After algebraic calculation, we get R m =158mm Figure 5 , 6 .

[0057] After the lid parts are cured by silicone encapsulation, they are placed in the preforming mold, and the convex and concave molds are combined to form the arc-shaped structure of the lid. There is an 8mm silicone pad between the outer surface of the lid after silicone encapsulation and the compression-molding stress surface. After the arc surface of the forming mold contacts the outer surface of the silicone, the silicone will produce volume elastic deformation. The silicone can fully fill the complex lid cavity without uneven stress on the forming surface; so that the compression molding force can be evenly transmitted to each point on the lid surface; avoid uneven distribution of forming force due to the complex weight-reducing cavity of the lid shape, and avoid instability or inadequate forming due to uneven stress on the ribs. After the preforming is completed, the silicone cover is removed by manually cutting open the silicone cover.

[0058] (4) Moulding and shaping of the cover

[0059] In order to further completely eliminate the influence of the pre-forming springback deformation of the cover parts on the outer dimensions of the cover and ensure the accuracy of the cover surface, a special correction mold is used after the cover is pre-formed. Figure 7 , and perform mouth cover shaping. By cold pressing the shaping die to shape, the springback error of the mouth cover can be eliminated, so as to obtain a mouth cover skin with consistent external dimensions.

[0060] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0061] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A method for bending and forming an aluminum alloy cover part with silicone encapsulation, characterized in that: include: According to the three-dimensional model of the unfolding process part of the cover part and its external dimensions, the CNC machining center processing program file is compiled, and the aluminum alloy plate is processed by the three-axis CNC machining center to obtain the unfolding process part of the cover part; A mold for silicone encapsulation is manufactured according to the outer dimensions of the unfolded process parts of the cover parts, and the mold is used for silicone encapsulation; After the unfolding process of the mouth cover parts is cured by silicone encapsulation, it is placed in the preforming mold, and the male and female molds are closed and pressed to form the arc-shaped structural parts of the mouth cover, so as to complete the preforming of the mouth cover. After the preforming is completed, the silicone sleeve is removed; After the mouth cover is preformed, a shaping die is used to shape the mouth cover, and the shaping die is cold-pressed to eliminate the springback error of the mouth cover forming, so as to obtain a mouth cover skin with consistent outer dimensions.

2. The method for bending and forming an aluminum alloy cover part with silicone encapsulation according to claim 1, characterized in that: According to the outer dimensions of the mouth cover skin parts, the neutral layer of the mouth cover is used as the basis for the mouth cover expansion calculation, and the parallel line expansion method is used to calculate the expanded outer dimensions of the mouth cover.

3. The method for bending and forming an aluminum alloy cover part with silicone encapsulation according to claim 2, characterized in that: The method of using the parallel line development method to calculate the unfolded shape and unfolded size of the mouth cover includes: regarding the surface of the part as composed of countless mutually parallel element lines, taking the area enclosed by two adjacent element lines and the two ends as a plane, and drawing the true size of each small plane in sequence on the plane to obtain the surface unfolded diagram of the part. The shapes that can be unfolded by parallel lines are all cylinders.

4. The method for bending and forming an aluminum alloy cover part with silicone encapsulation according to claim 1, characterized in that: The use of a mold for silicone encapsulation includes: Install the cover expansion process part in the silicone packaging mold, and use the positioning pins and the holes on the cover process part for effective positioning; Silicone sealing of the mouth cover.

5. The method for bending and forming an aluminum alloy cover part with silicone encapsulation according to claim 4, characterized in that: The thickness of the silicone between the upper and lower surfaces and the molded stress-bearing forming surface is 8mm, and the width of the silicone wrapping process in the front, back, left and right directions is 25mm.

6. The method for bending and forming an aluminum alloy cover part with silicone encapsulation according to claim 4, characterized in that: The silicone encapsulation of the mouth cover includes: taking 5-6 kg of mold silicone, loading 1 / 2 of the silicone that has been stirred evenly and has a certain curing effect into the silicone encapsulation mold, installing the mouth cover process parts on four positioning pins for installation and positioning, and introducing the remaining 1 / 2 of the silicone into the silicone encapsulation mold. Install the silicone encapsulation mold cover plate on the silicone encapsulation mold, use a hydraulic press to compact the silicone encapsulation mold to achieve complete silicone encapsulation of the mouth cover, and take the packaged mouth cover out of the silicone encapsulation mold after curing for 30 minutes.

7. The method for bending and forming an aluminum alloy cover part with silicone encapsulation according to claim 6, characterized in that: The mold silicone and curing agent are configured in a ratio of 25:1 and are fully stirred evenly, while the curing agent is configured while stirring.

8. The method for bending and forming an aluminum alloy cover part with silicone encapsulation according to claim 1, characterized in that: After the arc surface of the forming mold contacts the outer surface of the silicone, the silicone undergoes volume elastic deformation, and the silicone fully fills the complex mouth cover cavity to avoid uneven force on the forming surface.

9. The method for bending and forming an aluminum alloy cover part with silicone encapsulation according to claim 1, characterized in that: By cold-pressing the shaping die to correct the shape, the springback error of the cover forming can be eliminated.

10. The method for bending and forming an aluminum alloy cover part with silicone encapsulation according to claim 1, characterized in that: After preforming is completed, the silicone sleeve is removed by manually cutting open the silicone sleeve.

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