Instrument panel skeleton structure and method for controlling the flatness of the outer surface of the instrument panel panel

Abstract

The present invention discloses an instrument panel skeleton structure and a method for controlling the flatness of the outer surface of an instrument panel panel. The instrument panel skeleton structure includes an instrument panel skeleton body provided with an airbag bursting opening, and an airbag bracket is installed in the airbag bursting opening. The airbag bracket includes a frame formed by plates and a breakable panel connected to the outer end of the frame. The part of the breakable panel that extends circumferentially beyond the edge of the frame forms a lapping edge. A stepped mounting surface is formed on the edge of the instrument panel skeleton body corresponding to the airbag bursting opening, and the outer surface of the stepped mounting surface gradually rises circumferentially outward from the edge of the airbag bursting opening; the inner surface of the lapping edge is adapted to the stepped mounting surface, and its outer surface is a smooth surface. The present invention can improve the fit between the airbag bracket and the instrument panel skeleton body, reduce problems such as unevenness on the surface of the finished instrument panel skeleton and excessive fit clearance, thereby providing a good foundation for the foaming molding of the inner lining layer and making the surface of the final instrument panel product smooth.

Description

Technical Field

[0001] The present invention belongs to the field of automotive components, and particularly relates to an instrument panel skeleton structure and a method for controlling the flatness of the outer surface of the instrument panel panel. Background Art

[0002] The slush molding process technology of automotive instrument panels has been developed earlier, and the slush molding process is also very mature. The slush molding process is widely used in various vehicle models. The instrument panel product includes an instrument panel skeleton and a soft inner lining layer 3 covering the surface of the instrument panel skeleton. To improve the tactile comfort and aesthetics, the outer surface of the inner lining layer 3 is generally a leather-grained slush skin 32, and the slush skin 32 is bonded to the instrument panel skeleton through a foaming layer 31. The instrument panel skeleton includes an instrument panel skeleton body 1 and an airbag assembly installed thereon. The airbag is installed on an airbag bracket 2 (i.e., an airbag frame), and then is snap-connected to the instrument panel skeleton body 1 to form an instrument panel skeleton. Then, the instrument panel skeleton and the slush skin 32 are simultaneously placed into a foaming mold, and then a foaming material is injected for foaming. After curing, the final product is obtained. Therefore, the smoothness of the surface of the instrument panel skeleton determines the appearance quality of the final product. The installation methods of the hidden airbag brackets adopted by each vehicle factory on the instrument panel skeleton include: bolt fixation, friction vibration welding, snap connection method, and so on. Among them, the snap-connected airbag bracket is used the most due to its low cost. The snap-connected airbag bracket is a structural form in which its own snap structure is designed on the airbag bracket and is stuck on the side wall of the installation hole of the instrument panel skeleton. There is a free-state lap joint between the breakable panel edge of the airbag bracket and the edge of the airbag installation opening on the instrument panel skeleton, and the width of the lap joint is generally about 30 mm. However, when using the traditional snap-connected airbag bracket, in the foaming process, due to factors such as unreasonable assembly structure design, insufficient strength, and the foaming mold itself of the airbag bracket, there will be poor fit between the airbag bracket and the instrument panel skeleton, mainly manifested as uneven surface after the two are assembled or a large gap at the lap joint, and finally resulting in uneven transition on the surface of the foamed product slush skin 32, with protrusions, bulges or depressions, affecting the product quality. Summary of the Invention

[0003] In view of this, one of the purposes of the present invention is to provide an instrument panel skeleton structure.

[0004] The technical solution is as follows:

[0005] An instrument panel skeleton structure includes an instrument panel skeleton body provided with an airbag blasting opening, and an airbag bracket is installed in the airbag blasting opening. The airbag bracket includes a frame body surrounded by plates and a breakable panel connected to the outer end of the frame body. A part of the edge of the breakable panel extending circumferentially beyond the frame body forms a lapping edge. The key lies in that a stepped mounting surface is formed on the edge of the instrument panel skeleton body corresponding to the airbag blasting opening, and the outer surface of the stepped mounting surface gradually rises circumferentially outward from the edge of the airbag blasting opening;

[0006] The inner surface of the lapping edge is adapted to the stepped mounting surface, and its outer surface is a smooth surface.

[0007] In one embodiment, the above-mentioned stepped mounting surface includes a first mounting step surrounding the airbag blasting opening and a second mounting step surrounding the first mounting step;

[0008] The inner edge of the lapping edge is thinned to form a fitting step, and the thinned part of the edge of the lapping edge forms a fitting edge;

[0009] The fitting edge abuts against the second mounting step to form a first sealant surface, and the fitting step cooperates with the first mounting step to form a second sealant surface.

[0010] In one embodiment, at least one circumferential protrusion is integrally formed on the horizontal support surface of the above-mentioned first mounting step, the circumferential protrusion is arranged around the airbag blasting opening, and the inner surface of the lapping edge lies on the circumferential protrusion.

[0011] In one embodiment, the outer surface of a part of the lapping edge near its edge is an inclined surface, the fitting edge is lower than the surface height of the instrument panel skeleton body around the second mounting step, and the height difference therebetween is d, and d ranges from 0.3 mm to 0.6 mm;

[0012] The inner surface of the fitting edge and the horizontal support surface of the second mounting step are in interference fit, and the interference amount is 0.1 to 0.3 mm.

[0013] In one embodiment, the minimum thickness of the edge of the fitting edge is 1.2 to 2 mm, and the width of the fitting edge is 3 to 8 mm;

[0014] The width of the lapping edge is 40 to 70 mm.

[0015] In one embodiment, the above-mentioned airbag bracket is injection-molded from a thermoplastic polyolefin elastomer material, and the flexural modulus of the material after curing is above 400 MPa.

[0016] The second object of the present invention is to provide a method for controlling the flatness of the outer surface of the instrument panel panel.

[0017] A method for controlling the flatness of the outer surface of an instrument panel panel, the instrument panel panel including the instrument panel skeleton structure as described above, characterized in that the instrument panel skeleton body and the airbag bracket are respectively formed, the airbag bracket is installed on the instrument panel skeleton body to form an instrument panel skeleton, and then the two are integrally installed on the upper mold of the foaming mold, the slush skin is installed in the inner cavity of the lower mold of the foaming mold and laid flat; then the mold is closed, a foaming cavity is formed between the instrument panel skeleton and the slush skin, foaming material is injected into the foaming cavity to generate a foaming reaction, and after curing, a foaming layer is formed between the slush skin and the instrument panel skeleton, and this foaming layer is simultaneously bonded to the outer surfaces of the slush skin and the instrument panel skeleton; finally, the instrument panel panel is demolded;

[0018] Wherein, a slider assembly is arranged at the position of the airbag bracket corresponding to the foaming mold, the slider assembly includes a slider, the slider is used to press against the airbag bracket, the slider is connected with a guiding mechanism and a locking driving mechanism, and the locking driving mechanism is used to drive the slider to move between the forming position and the demolding position along the guiding direction of the guiding mechanism, and when the slider is located at the forming position, the locking driving mechanism prevents the slider from retracting under the foaming pressure;

[0019] During the foaming and forming process of the foaming layer, the locking driving mechanism is always located at the forming position.

[0020] In an embodiment, the above-mentioned locking driving mechanism includes a linear telescopic mechanism, a first connecting rod and a second connecting rod, the ends of the first connecting rod and the second connecting rod are hinged to each other, and are connected between the slider and a first fixed seat located behind the slider;

[0021] A second fixed seat is arranged outside the connection line of the first connecting rod and the second connecting rod, one end of the linear telescopic mechanism is hinged to the second fixed seat, and the other end is hinged to the hinge point of the first connecting rod and the second connecting rod;

[0022] When the slider is located at the forming position, the first connecting rod and the second connecting rod are on the same straight line, and the linear telescopic mechanism is perpendicular to this straight line, so as to lock itself.

[0023] In an embodiment, the above-mentioned linear telescopic mechanism is a cylinder, the housing of the cylinder is hinged to the first fixed seat, and the extending end of the piston rod of the cylinder is hinged to the hinge point of the first connecting rod and the second connecting rod.

[0024] In an embodiment, the above-mentioned guiding mechanism includes two guiding rods, the two guiding rods are connected in parallel at the tail end of the slider, and two fixing blocks are arranged on the mold, and one of the guiding rods is movably penetrated through each fixing block;

[0025] The second connecting rod is connected to the middle of the end face of the slider, and the two guide rods are respectively located on both sides of the second connecting rod.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: the strength and stiffness are enhanced through the structural design at the lap joint between the airbag bracket and the instrument panel skeleton body, a higher-strength injection molding material is selected to reduce deformation, improve the fitting state, make the fitting more precise, the surface of the finished instrument panel skeleton is smoother, and the problems of unevenness on the product surface and excessive fitting gaps are minimized as much as possible, providing a good foundation for the foaming layer during foaming molding; in addition, by improving the structure of the driving mechanism of the demolding slider of the airbag bracket, the position of the slider is always kept stable during the foaming process, and the quality of the foamed product is improved. All of these improve the quality of the final instrument panel product and minimize the defects of unevenness of the slush molding skin as much as possible. In addition, due to the more precise stepped fitting structure, the foaming anti-overflow seal strip between the overlapping edge of the traditional structure and the overlapping part of the instrument panel skeleton body can be cancelled, simplifying the process and reducing the cost. Brief Description of the Drawings

[0027] Figure 1 It is a schematic diagram of the mutual cooperation between the traditional snap-type airbag bracket and the instrument panel skeleton body, and the figure shows the perspective of the outer surface;

[0028] Figure 2 It is a schematic diagram of the installation structure between the traditional airbag bracket and the instrument panel skeleton body, and the figure shows the inner lining layer formed by the foaming layer and the slush molding skin;

[0029] Figure 3 It is a schematic diagram of the overlapping structure between the overlapping edge of the traditional airbag bracket and the instrument panel skeleton body;

[0030] Figure 4 It is a schematic diagram of the overlapping structure between the airbag bracket of the present invention and the instrument panel skeleton body;

[0031] Figure 5 It is an exploded structure schematic diagram of the airbag bracket of the present invention and the instrument panel skeleton body;

[0032] Figure 6 It is a schematic diagram of the structure of the airbag bracket of the present invention;

[0033] Figure 7 It is a schematic diagram of the structure of the slider assembly, and the slider is in the demolding position in the figure;

[0034] Figure 8 It is a schematic diagram of the structure of the slider assembly, and the slider is close to the molding position in the figure;

[0035] Figure 9 For Figure 8 Another perspective schematic diagram;

[0036] Figure 10Schematic diagram of foaming to form a foamed layer in a foaming mold. Detailed implementation mode

[0037] The present invention will be further described below in conjunction with embodiments and the accompanying drawings.

[0038] The installation structure of the traditional snap-type airbag bracket 2 on the instrument panel skeleton body 1 is as shown in Figure 1 、 2 and 3. The overlapping edge abuts against the outer side of the edge of the airbag installation opening, and the breakable panel can sink and fit to be flush with the surface of the instrument panel skeleton body 1. After assembly, the instrument panel skeleton and the slush molding skin 32 are foamed in a foaming mold, and a foamed layer 31 is formed after foaming. The foamed layer 31 bonds the instrument panel skeleton and the slush molding skin 32 together to obtain an instrument panel product. However, the surface of the slush molding skin 32 of the instrument panel product is prone to uneven defects. Since the inner lining layer 3 is a soft coating layer, its unevenness is mainly caused by the instrument panel skeleton. Through research and analysis, the main reasons for the formation of the uneven defects are as follows:

[0039] First, the internal stress during the foaming process is released after demolding, and the product deforms. During the foaming process, if the instrument panel skeleton is not level or there is an assembly gap problem, the pressure generated by the reaction of the foaming A and B materials will flatten the unevenness between the two or fill the gap and push up the airbag bracket 2. After demolding, the product loses restraint and returns to its free shape, showing uneven defects or gap problems; or due to the limitation of the mold cavity shape, the surface shape of the foamed product is maintained, but when the mold is opened, the external restriction of the product is removed, and the force on the airbag bracket 2 in the mold will be released and deformed, returning to the state during assembly, manifested as unevenness on the surface of the instrument panel product.

[0040] Second, the surface strength of the airbag bracket product is insufficient. Since the airbag bracket 2 has requirements for blasting functionality, thermoplastic polyolefin elastomer (TPE) materials are generally selected for injection molding. However, due to its material characteristics, the surface stiffness and product strength of the injection-molded product are relatively low; when the airbag bracket 2 is assembled onto the instrument panel skeleton for foaming, if there is a gap between the slider used to press against the airbag bracket and the support surface of the airbag bracket or the slider is not in the theoretically designed position, the surface of the airbag bracket 2 will also be deformed (outward convex or inward concave) due to the pressure generated by the reaction of the A and B materials during the foaming process; after the product is cured and the mold is opened, the external restriction of the product is removed, and the airbag bracket 2 returns to the state during assembly, and outward convex or inward concave problems will also appear on the surface of the instrument panel product.

[0041] Thirdly, there is the influence of foaming pressure. During the foaming process, the slider used to press against the airbag bracket retracts. After the product is foamed and the mold is opened, the airbag bracket product rebounds again, causing convex problems on the surface of the instrument panel product. The foaming process involves the chemical reaction of mixing two materials, polyether and isocyanate, in a certain proportion. A large amount of gas is generated during the reaction, and pressure will be generated in the closed space of the foaming mold. Generally, the B side of the instrument panel skeleton will closely adhere to the upper mold of the foaming mold, and the upper mold supports the instrument panel skeleton. However, due to the inconsistent angles between the airbag assembly angle and the demolding angle of the instrument panel product, the foaming mold generally has a separate demolding slider for the airbag bracket to press against the airbag bracket, as Figure 10 shown (the difference between the demolding angle of the instrument panel product and the demolding slider angle is not shown in the figure); if the airbag bracket slider of the foaming mold has no self-locking structure after mold closing, the airbag bracket and the airbag slider will move backward under the influence of the pressure generated during foaming during the foaming process; after the product is foamed and the mold is opened, the airbag bracket product rebounds again, causing convex problems on the surface of the instrument panel product.

[0042] In response to the above problems and the reasons for these problems in different aspects, the product design and process have been improved.

[0043] As Figure 3 and 4 shown, an instrument panel skeleton structure includes an instrument panel skeleton body 1 provided with an airbag blasting opening 11. An airbag bracket 2 is installed in the airbag blasting opening 11. The airbag bracket 2 includes a frame body 21 formed by plates and a breakable panel 22 connected to the outer end of the frame body 21. The part of the edge of the breakable panel 22 extending circumferentially beyond the frame body 21 forms a lapping edge 23. A stepped mounting surface is formed on the edge of the instrument panel skeleton body 1 corresponding to the airbag blasting opening 11, and the outer surface of the stepped mounting surface 12 gradually rises circumferentially outward from the edge of the airbag blasting opening 11. The inner surface of the lapping edge 23 is adapted to the stepped mounting surface 12, and its outer surface is a smooth surface. In this way, after the airbag bracket 2 is assembled with the instrument panel skeleton body 1, the frame body 21 is inserted into the airbag blasting opening 11, and the breakable panel 22 covers the airbag blasting opening 11. And because the stepped mounting surface sinks downward as a whole, the surface of the breakable panel 22 is flush with the surface of the instrument panel skeleton body 1.

[0044] Different from the structural design in the prior art where the thickness of each part of the overlapping edge 23 is uniform and only bevels are used for transition at the edges to cooperate with the instrument panel skeleton body 1, in this embodiment, a stepped surface matching structure is adopted, which can increase the structural strength of the overlapping parts of the two, thereby enhancing the stiffness of the matching part and improving the state after the two are assembled and matched. At the same time, since the stepped matching is more rigorous, it can prevent the foaming material from squeezing into the product gap during foaming. In this way, the anti-foaming overflow seal strip between the two in the traditional assembly structure can be cancelled, simplifying the process and reducing the process cost.

[0045] The stepped mounting surface can be two-level or multi-level steps. To balance the fitting effect and structural complexity, two-level or three-level steps are preferred.

[0046] Such as Figure 3 and 4 , in this embodiment, the stepped mounting surface includes a first mounting step 12a surrounding the airbag blasting opening 11, and a second mounting step 12b surrounding the first mounting step 12a. The inner edge of the overlapping edge 23 is thinned to form a fitting step 23a, and the thinned part of the edge of the overlapping edge 23 forms a fitting edge 23b. The fitting edge 23b abuts against the second mounting step 12b to form a first sealant surface, and the fitting step 23a cooperates with the first mounting step 12a to form a second sealant surface. In this way, the first sealant surface and the second sealant surface form a two-level sealing structure to prevent the foaming material from entering the frame body 21 of the airbag bracket 2 from the overlapping part during the foaming process.

[0047] To make the first sealant surface fit tightly, an interference fit is provided between the inner surface of the fitting edge 23b and the horizontal supporting surface of the second mounting step 12b, and the interference amount is 0.1 - 0.3 mm.

[0048] To make the second sealant surface fit tightly, at least one circumferential protrusion 12c is integrally formed on the horizontal supporting surface of the first mounting step 12a. The circumferential protrusion 12c is arranged around the airbag blasting opening 11, and the inner surface of the overlapping edge 23 rests on the circumferential protrusion 12c, thus forming a line-surface fitting structure to avoid poor fitting caused by surface accuracy problems in surface-surface fitting.

[0049] Further, different from the design where the overlapping edge 23 of the airbag bracket 2 is completely flush with the outer surface of the instrument panel skeleton body 1, in this embodiment, to prevent the edge of the airbag bracket 2 from warping and deforming upwards beyond the outer surface of the instrument panel skeleton body 1, a gradual change treatment is performed on the edge part of the overlapping edge 23 including the fitting edge 23b, that is, the outer surface of the part of the overlapping edge 23 near its edge is an inclined surface, and the fitting edge 23b is lower than the surface height of the instrument panel skeleton body 1 around the second mounting step 12b, and the height difference between the two is d, and the value of d is 0.3 mm - 0.6 mm.

[0050] In one embodiment, the edge of the bonding edge 23b is sunken into the surface of the instrument panel skeleton body 1 near the edge of the bonding edge 23b by about 0.5 mm to absorb the deformation error of the parts and avoid the problem of the bonding edge 23b being higher than the instrument panel skeleton body 1 next to it after assembly, further reducing the possibility of unevenness on the product surface after foaming.

[0051] The minimum thickness of the edge of the bonding edge 23b is 1.2-2 mm, the width of the bonding edge 23b is 3-8 mm, and the width of the lap edge 236 is 40-70 mm, which is wider than the lap edge 23 of the conventional airbag bracket 2.

[0052] In addition, the airbag bracket 2 can be made of thermoplastic polyolefin elastomer material, for example, material with product number VP 50DNLC is selected for injection molding. After curing, the bending modulus of the material reaches 400MPa or above, preferably 400~450MPa, which is higher than the bending modulus of 350Mpa of general materials, thereby improving its strength and rigidity, thereby further reducing the deformation problem of the foamed product after demolding and before and after assembly, and reducing the probability of uneven surface of the final control panel skeleton.

[0053] On the clamping structure, the edge of the airbag mounting opening 11 is connected to a limiting plate 13, which is located on the inner side of the instrument panel skeleton body 1. The circumferential outer wall of the frame body 21 is provided with an anti-drop buckle 24, which abuts against the limiting plate 13 to prevent the airbag bracket 2 from falling out of the airbag bursting opening 11.

[0054] In addition to the structural design and material aspects, the present invention also makes improvements from the perspective of the molding method.

[0055] A method for controlling the flatness of the outer surface of an instrument panel, the instrument panel comprising the above-mentioned instrument panel skeleton structure, the method comprising: separately molding the instrument panel skeleton body 1 and the airbag bracket 2, then installing the airbag bracket 2 on the instrument panel skeleton body 1 to form the instrument panel skeleton, and then installing the two as a whole to the upper mold of the foaming mold, installing the slush-molded skin 32 to the inner cavity of the lower mold of the foaming mold, and flattening it, for the convenience of fixing, using a vacuum of a certain pressure to absorb the slush-molded skin 32 through the vacuum hole; then closing the mold, forming a foaming cavity between the instrument panel skeleton and the slush-molded skin 32, injecting a foaming material into the foaming cavity to generate a foaming reaction, and forming a foaming layer 31 between the slush-molded skin 32 and the instrument panel skeleton after curing, and the foaming layer 31 is bonded to the slush-molded skin 32 and the outer surface of the instrument panel skeleton at the same time, such as Figure 10 As shown in the figure, after the foaming molding is completed, the vacuum is released, and finally the instrument panel is demoulded. Among them, the foaming mold is provided with a slider assembly 4 at the position corresponding to the airbag bracket.

[0056] As Figures 7 - 9 shown, the slider assembly 4 includes a slider 41 which is used to press against the inner cavity of the frame body 21. The slider 41 is connected with a guiding mechanism 42 and a locking driving mechanism 43. The locking driving mechanism 43 is used to drive the slider 41 to move between a forming position and a demolding position along the guiding direction of the guiding mechanism 42. And when the slider 41 is located at the forming position, the locking driving mechanism 43 prevents the slider 41 from retracting under the foaming pressure. The forming position and the demolding position define the movement stroke of the slider 41 entering and exiting the mold cavity. During the foaming and forming process of the foaming layer 31, the locking driving mechanism 43 is always located at the forming position. It is easy for those skilled in the art to understand that the so-called prevention of retraction does not mean an absolutely unchanged position, but rather an extremely small retraction amount, preferably within 0.1 mm. The traditional slider driving mechanism is a cylinder, and the cylinder rod drives the slider to enter and exit the mold cavity through telescopic movement. However, under a large foaming pressure, the cylinder rod may retract, while the present invention corrects this problem.

[0057] In this embodiment, the locking driving mechanism 43 includes a linear telescopic mechanism 43a, a first connecting rod 43b and a second connecting rod 43c. The ends of the first connecting rod 43b and the second connecting rod 43c are hinged to each other and are connected between the slider 41 and a first fixed seat 43d located behind the slider 41. A second fixed seat 43e is arranged outside the connection line of the first connecting rod 43b and the second connecting rod 43c. One end of the linear telescopic mechanism 43a is hinged to the second fixed seat 43e, and the other end is hinged to the hinge point of the first connecting rod 43b and the second connecting rod 43c. Both the first fixed seat 43d and the second fixed seat 43e are fixed relative to the mold base.

[0058] When the slider 41 is located at the forming position, the first connecting rod 43b and the second connecting rod 43c are on the same straight line, and the linear telescopic mechanism 43a is perpendicular to this straight line, thus self-locking. According to the force analysis, when the linear telescopic mechanism 43a is perpendicular or nearly perpendicular to the first connecting rod 43b and the second connecting rod 43c, the linear telescopic mechanism 43a only needs a relatively small pushing force to enable the slider 41 to bear a great pressure. During the foaming and forming process of the airbag bracket 2, it is almost impossible for the foaming pressure to cause the linear telescopic mechanism 43a to contract. During debugging, it is advisable to ensure that when the slider 41 is in the forming position state, the first connecting rod 43b and the second connecting rod 43c are as close to a straight line as possible, and the included angle formed by the two does not exceed 1° with the designed angle error.

[0059] The linear telescopic mechanism 43a can use various existing mechanical devices. For the convenience of control, in this embodiment, the linear telescopic mechanism 43a is a cylinder. The housing of this cylinder is hinged to the first fixed seat 43d, and the extending end of the piston rod of this cylinder is hinged to the hinge point of the first connecting rod 43b and the second connecting rod 43c.

[0060] The guiding mechanism 42 includes two guiding rods 42b. The two guiding rods 42b are connected in parallel to the tail end of the slider 41. There are two fixing blocks 32a provided on the die, and one guiding rod 42b is movably inserted through each fixing block 32a. The second connecting rod 43c is connected to the middle of the tail end face of the slider 41, and the two guiding rods 42b are respectively located on both sides of the second connecting rod 43c to maintain the balance of the slider 41 during movement.

[0061] Finally, it should be noted that the above description is only the preferred embodiment of the present invention. Under the inspiration of the present invention, those of ordinary skill in the art can make various similar representations without violating the purpose and claims of the present invention, and such transformations all fall within the protection scope of the present invention.

Claims

1. A method for controlling the flatness of the outer surface of an instrument panel, the instrument panel comprising an instrument panel skeleton structure, the instrument panel skeleton structure including an instrument panel skeleton body (1) provided with an airbag bursting opening (11), an airbag bracket (2) being installed in the airbag bursting opening (11), the airbag bracket (2) including a frame body (21) surrounded by plates and a breakable panel (22) connected to the outer end of the frame body (21), a lapping edge (23) being formed by a portion of the edge of the breakable panel (22) extending circumferentially beyond the frame body (21), characterized in that: A stepped mounting surface (12) is formed on the dashboard skeleton body (1) corresponding to the edge of the airbag rupture opening (11), and the outer surface of the stepped mounting surface (12) gradually rises circumferentially outward from the edge of the airbag rupture opening (11). The inner surface of the overlapping edge (23) is adapted to the stepped mounting surface (12), and its outer surface is a smooth surface. It is characterized in that: the dashboard skeleton body (1) and the airbag bracket (2) are respectively formed, the airbag bracket (2) is installed on the dashboard skeleton body (1) to form a dashboard skeleton, and then the two are integrally installed on the upper mold of the foaming mold. The slush molding skin (32) is installed in the inner cavity of the lower mold of the foaming mold and laid flat. Then the mold is closed, a foaming cavity is formed between the dashboard skeleton and the slush molding skin (32), and foaming material is injected into the foaming cavity to generate a foaming reaction. After curing, a foaming layer (31) is formed between the slush molding skin (32) and the dashboard skeleton, and the foaming layer (31) is simultaneously bonded to the outer surfaces of the slush molding skin (32) and the dashboard skeleton. Finally, the dashboard panel is demolded. Wherein, a slider assembly (4) is arranged at the position of the airbag bracket corresponding to the foaming mold. The slider assembly (4) includes a slider (41) which is used to press against the airbag bracket (2). The slider (41) is connected with a guiding mechanism (42) and a locking driving mechanism (43). The locking driving mechanism (43) is used to drive the slider (41) to move between the molding position and the demolding position along the guiding direction of the guiding mechanism (42). And when the slider (41) is located at the molding position, the locking driving mechanism (43) prevents the slider (41) from retracting under the foaming pressure. During the foaming molding process of the foaming layer (31), the locking driving mechanism (43) is always located at the molding position.

2. The method for making the outer surface of the control instrument panel flat according to claim 1, wherein: The locking driving mechanism (43) includes a linear telescopic mechanism (43a), a first connecting rod (43b) and a second connecting rod (43c). The ends of the first connecting rod (43b) and the second connecting rod (43c) are hinged to each other and are connected between the slider (41) and a first fixed seat (43d) located behind the slider (41). A second fixed seat (43e) is arranged outside the connection line of the first connecting rod (43b) and the second connecting rod (43c). One end of the linear telescopic mechanism (43a) is hinged to the second fixed seat (43e), and the other end is hinged to the hinge point of the first connecting rod (43b) and the second connecting rod (43c). When the slider (41) is located at the molding position, the first connecting rod (43b) and the second connecting rod (43c) are on the same straight line, and the linear telescopic mechanism (43a) is perpendicular to this straight line, so as to be self-locked.

3. The method for making the outer surface of the control instrument panel flat according to claim 2, characterized in that: The linear telescopic mechanism (43a) is a cylinder. The housing of the cylinder is hinged to the first fixed seat (43d), and the extending end of the piston rod of the cylinder is hinged to the hinge point of the first connecting rod (43b) and the second connecting rod (43c).

4. The method for making the outer surface of the control instrument panel flat according to claim 2, wherein: The guiding mechanism (42) includes two guiding rods (42b), and the two guiding rods (42b) are parallelly connected to the tail end of the slider (41). Two fixing blocks (32a) are arranged on the mold, and one of the guiding rods (42b) is movably inserted through each of the fixing blocks (32a); The second connecting rod (43c) is connected to the middle of the tail end surface of the slider (41), and the two guiding rods (42b) are respectively located on both sides of the second connecting rod (43c).

5. The method for making the outer surface of the control instrument panel flat according to claim 1, characterized in that: The stepped mounting surface includes a first mounting step (12a) surrounding the airbag burst opening (11), and a second mounting step (12b) surrounding the first mounting step (12a); The inner edge of the overlapping edge (23) is thinned to form a fitting step (23a), and the thinned part of the edge of the overlapping edge (23) forms a fitting edge (23b); The fitting edge (23b) abuts against the second mounting step (12b) to form a first sealing surface, and the fitting step (23a) cooperates with the first mounting step (12a) to form a second sealing surface.

6. The method for making the outer surface of the control instrument panel flat according to claim 5, wherein: At least one circumferential protrusion (12c) is integrally formed on the horizontal support surface of the first mounting step (12a). The circumferential protrusion (12c) is arranged around the airbag burst opening (11), and the inner surface of the overlapping edge (23) rests on the circumferential protrusion (12c).

7. The method for making the outer surface of the control instrument panel flat according to claim 5 or 6, characterized in that: The outer surface of the part of the overlapping edge (23) close to its edge is an inclined surface. The fitting edge (23b) is lower than the surface height of the instrument panel skeleton body (1) around the second mounting step (12b), and the height difference therebetween is d, and d ranges from 0.3 mm to 0.6 mm; The inner surface of the fitting edge (23b) and the horizontal support surface of the second mounting step (12b) are in interference fit, and the interference amount is 0.1 to 0.3 mm.

8. The method for making the outer surface of the control instrument panel flat according to claim 7, characterized in that: The minimum thickness of the edge of the fitting edge (23b) is 1.2 to 2 mm, and the width of the fitting edge (23b) is 3 to 8 mm; The width of the overlapping edge (23) is 40 to 70 mm.

9. The method for making the outer surface of the control instrument panel flat according to claim 1 or 5 or 6, characterized in that: The airbag bracket (2) is injection-molded from a thermoplastic polyolefin elastomer material, and the flexural modulus of the material reaches 400 MPa or more after curing.

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