Manufacturing method of front pillar for vehicles and front pillar for vehicles

Abstract

To provide a manufacturing method of a front pillar for vehicles and a front pillar for vehicles characterized in that superb manufacturability and a high rust-prevention capability can be attained.SOLUTION: A manufacturing method of a front pillar 1 for vehicles includes a retention step S1 of using a jig 111 to retain a foam material 21, which is too big to pass through an opening 19, at a predetermined position of an outer panel 7, a joint step S2 of joining a flange 5 of an inner panel 6 and an outer panel 7 so that the jig 111 can pass through the opening 19, a detainment step S3 of placing the foam material 21 inside a closed section structure 11 by pulling the jig 111 out of the opening 19, an electrodeposition coating step S4 of forming an electrodeposition coat over the front pillar 1 for vehicles through electrodeposition coating, and a heating step S5 of forming an electrodeposition coating film 13 by curing the electrodeposition coat through heating in a heating furnace, and forming a foam 15 by foaming the foam material 21.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] Embodiments of the present invention relate to a method for manufacturing a vehicle front pillar and a vehicle front pillar.

Background Art

[0002] There is known a foaming member for a hollow structure for attaching a foaming material to a hollow structure. This foaming member for a hollow structure is produced by attaching a weldable welding piece to a foaming material for forming a foam that fills the internal space of a pillar as the hollow structure. Then, in order to fix the foaming member for a hollow structure to the pillar, the welding piece attached to the foaming material is spot-welded to the inner panel of the pillar. Therefore, most of the mating surface between the welding piece and the inner panel, that is, the non-welded portion, has minute gaps.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since the rust prevention treatment process is carried out in a state where the welding piece and the inner panel of the pillar are in contact with each other, minute gaps on the mating surface between the spot-welded welding piece and the inner panel cannot be filled with the rust preventive agent and become rust prevention untreated portions. Even if the inside of the pillar is filled with a foaming material, water may enter. In this case, if rainwater or the like remains inside the pillar, the water enters the minute gaps on the mating surface due to capillary action. Therefore, there is a risk that corrosion progresses from the mating surface that has become a rust prevention untreated portion. Note that the rust prevention treatment process is, for example, an electrodeposition coating process. Also, the rust preventive agent is, for example, an electrodeposition paint.

[0005] In addition, when fixing the foaming member for the hollow structure to the front pillar for a vehicle in which the internal space is relatively narrow among the pillars, since the welding piece for the foaming material is large, it becomes difficult to position the welding piece with respect to the inner panel. Therefore, the manufacturability is significantly reduced, and in fact, the applicable part of the foaming member for the hollow structure is limited.

[0006] Therefore, an object of the present invention is to provide a manufacturing method for a front pillar for a vehicle and a front pillar for a vehicle that have high rust prevention properties while being excellent in manufacturability.

Means for Solving the Problems

[0007] A manufacturing method for a front pillar for a vehicle according to an embodiment of the present invention for solving the above problems includes an inner panel having a flange portion, an outer panel joined to the flange portion, and an electrodeposition coating film formed over the entire inner peripheral surface of a closed cross-sectional structure formed by joining the flange portion and the outer panel, and a foam filling the inside of the electrodeposition coating film on the inner periphery of the closed cross-sectional structure. At the lower end of the closed cross-sectional structure, there are provided a closed portion blocked by the flange portion and an opening portion that is open without being blocked, and it is a manufacturing method for a front pillar for a vehicle disposed in front of an opening for a front door of a vehicle. The manufacturing method for a front pillar for a vehicle includes a holding step of holding a foaming material having a size that cannot pass through the opening portion at a predetermined position of the outer panel using a jig, a joining step of joining the flange portion and the outer panel so that the jig penetrates the opening portion, a leaving step of pulling out the jig from the opening portion and leaving the foaming material inside the closed cross-sectional structure, an electrodeposition coating step of forming an electrodeposition coating film on the front pillar for a vehicle by electrodeposition coating, and a heating step of heating in a heating furnace to cure the electrodeposition coating film to form the electrodeposition coating film and to foam the foaming material to form the foam.

[0008] In addition, a vehicle front pillar according to an embodiment of the present invention for solving the above problems includes an inner panel having a flange portion, an outer panel joined to the flange portion, an electrodeposition coating film formed over the entire inner periphery of a closed cross-sectional structure formed by joining the flange portion and the outer panel, and a foam filling the inside of the electrodeposition coating film on the inner periphery of the closed cross-sectional structure. At the lower end of the closed cross-sectional structure, a closed portion blocked by the flange portion and an opening portion that is open without being blocked are provided.

Advantages of the Invention

[0009] The present invention provides a method for manufacturing a vehicle front pillar and a vehicle front pillar that can have high rust prevention performance while being excellent in manufacturability.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

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Figure 4

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Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

DETAILED DESCRIPTION OF THE INVENTION

[0011] The manufacturing method of the vehicle front pillar which concerns on this embodiment and the vehicle front pillar are demonstrated with reference to FIGS. 1-11. In addition, the same code | symbol is attached | subjected to the same or equivalent structure in a some drawing.

[0012] FIG. 1 is a schematic diagram which shows an example of the vehicle structure 100 provided with the vehicle front pillar 1 manufactured by the manufacturing method of the vehicle front pillar 1 which concerns on embodiment of this invention. In addition, in FIG. 1, the vehicle structure 100 is a vehicle structure on the right side seen from the vehicle interior. In addition, in FIG. 1, the arrow X shows the front-back direction of the vehicle. The front-back direction of the vehicle shown by the arrow X may be simply called the front-back direction X below.

[0013] As shown in FIG. 1, the vehicle structure 100 is a frame member which comprises a vehicle body. The vehicle structure 100 is provided with the vehicle front pillar 1 arrange | positioned in front of the front door opening part 101 of a vehicle in the front-back direction X. In the example of FIG. 1, the vehicle front pillar 1 includes the 1st front pillar 3 far from the front door opening part 101, and the 2nd front pillar 4 near the front door opening part 101. Hereinafter, the vehicle front pillar 1 is demonstrated in detail.

[0014] FIG. 2 is a view showing a vehicle front pillar 1 according to an embodiment of the present invention. In FIG. 2, the configuration of a first front pillar 3 is illustrated as the vehicle front pillar 1, and the same shall apply to the subsequent figures. Further, the second front pillar 4 can also have the same configuration as the first front pillar 3, and can be manufactured by the same manufacturing method as the first front pillar 3. In FIG. 2, an arrow Y indicates the extending direction of the vehicle front pillar 1. The extending direction of the vehicle front pillar 1 indicated by the arrow Y may hereinafter be simply referred to as the extending direction Y.

[0015] FIG. 3 is an enlarged view of the A-A cross section of FIG. 2. Note that FIG. 3 is a cross-sectional view taken by cutting the vehicle front pillar 1 of FIG. 2 along the line A-A so as to be orthogonal to the extending direction of the vehicle front pillar 1.

[0016] As shown in FIGS. 2 and 3, the vehicle front pillar 1 includes an inner panel 6 having a flange portion 5, an outer panel 7 joined to the flange portion 5, an electrodeposition coating film 13 formed over the entire inner circumferential surface of a closed cross-sectional structure 11 formed by joining the flange portion 5 and the outer panel 7, and a foam 15 filling the inside of the electrodeposition coating film 13 on the inner circumference of the closed cross-sectional structure 11.

[0017] The inner panel 6 is a panel on the vehicle interior side. The inner panel 6 is a long member extending in the extending direction Y and has a convex shape protruding toward the vehicle interior side. The material of the inner panel 6 is, for example, steel or aluminum (including aluminum alloys).

[0018] The flange portion 5 of the inner panel 6 has a joint surface that contacts the outer panel 7. By joining the flange portion 5 to the outer panel 7, the inner panel 6 and the outer panel 7 are firmly joined. Further, the flange portion 5 has a curved portion 5a that curves and extends at the lower end of the inner panel 6. Note that the distinction between the upper end and the lower end of the inner panel 6 is based on the state in which the vehicle front pillar 1 is provided in the vehicle structure 100.

[0019] The outer panel 7 is a panel on the outdoor side of the vehicle. The outer panel 7 is a long member extending in the extending direction Y and has a convex shape protruding to the outdoor side of the vehicle. The material of the outer panel 7 is usually the same as that of the inner panel 6, and is, for example, steel or aluminum (including aluminum alloy).

[0020] The closed cross-section structure 11 has an internal space F. The internal space F of the closed cross-section structure 11 is filled with a foam 15 from the viewpoint of improving the quietness of the vehicle. At the lower end of the closed cross-section structure 11, there are provided a closing portion 17 closed by the flange portion 5 of the inner panel 6, more specifically, the curved portion 5a of the flange portion 5, and an opening portion 19 that is open without being closed. Note that the lower end of the closed cross-section structure 11 is based on the state in which the vehicle front pillar 1 is provided in the vehicle structure 100. That is, the distinction between the upper end and the lower end of the closed cross-section structure 11, or the distinction between the upper side and the lower side of the closed cross-section structure 11, is based on the state in which the vehicle front pillar 1 is provided in the vehicle structure 100.

[0021] The foam 15 reduces the transmission sound passing through the vehicle front pillar 1 and improves the quietness of the vehicle.

[0022] The electrodeposition coating film 13 improves the rust prevention property of the vehicle front pillar 1. The electrodeposition coating film 13 can be provided by heating and curing an electrodeposition coating film made of an electrodeposition paint formed by electrodeposition coating. As a feature of the vehicle front pillar 1 according to the present embodiment, the electrodeposition coating film 13 is formed over the entire inner peripheral surface of the closed cross-section structure 11.

[0023] In order to fill the inside of a vehicle front pillar, that is, the internal space of a closed cross-section structure, with a foam, a foam material which is a member in a state before the foam is heated and foamed, and a welding piece which is attached to the foam material and can be spot-welded to the inner panel of the pillar are provided. It is conceivable to use a foaming member for a hollow structure.

[0024] However, when electrodeposition coating is performed on a pillar to which this foaming member for a hollow structure is fixed, minute gaps generated at the mating surface between the spot-welded welding piece and the inner panel of the pillar cannot be filled with the electrodeposition paint and become rust-prevention untreated parts. When water enters this rust-prevention untreated part by capillary action, corrosion may progress from the mating surface that has become the rust-prevention untreated part. That is, in a conventional vehicle front pillar using a foaming member for a hollow structure, in fact, an electrodeposition coating film cannot be formed over the entire inner circumference of the closed cross-section structure, and the rust prevention property deteriorates.

[0025] On the other hand, in the case of the vehicle front pillar 1 according to the present embodiment, since the electrodeposition coating film 13 is formed over the entire inner circumference of the closed cross-section structure 11, it can have high rust prevention property.

[0026] Hereinafter, a manufacturing method of the vehicle front pillar 1 capable of forming the electrodeposition coating film 13 over the entire inner circumference of the closed cross-section structure 11 will be described in detail.

[0027] FIG. 4 is a flowchart showing a manufacturing method of the vehicle front pillar 1 according to an embodiment of the present invention.

[0028] FIG. 5(A) is a diagram showing an example of a holding step S1 of the manufacturing method of the vehicle front pillar 1 according to an embodiment of the present invention, and FIG. 5(B) is a diagram showing an example of a leaving step S3 of the manufacturing method of the vehicle front pillar 1 according to an embodiment of the present invention.

[0029] As shown in FIGS. 4, 5(A) and 5(B) in addition to FIGS. 1 to 3, a method for manufacturing a vehicle front pillar 1 according to an embodiment of the present invention includes a holding step S1 of holding a foam material 21 having a size that cannot pass through the opening 19 at a predetermined position of the outer panel 7 using a jig 111, a joining step S2 of joining the flange portion 5 of the inner panel 6 and the outer panel 7 so that the jig 111 penetrates the opening 19, a leaving step S3 of pulling out the jig 111 from the opening 19 at the lower end of the closed cross-section structure 11 and leaving the foam material 21 inside the closed cross-section structure 11, an electrodeposition coating step S4 of forming an electrodeposition coating film on the vehicle front pillar 1 by electrodeposition coating, and a heating step S5 of heating in a heating furnace to cure the electrodeposition coating film to form an electrodeposition coating film 13 and to foam the foam material 21 to form a foam 15. Hereinafter, each step will be described in more detail. In addition, among the respective configurations of the vehicle front pillar 1, when the description overlaps, the overlapping description may be omitted.

[0030] As shown in FIG. 5(A), in the holding step S1, a jig 111 provided with a pin 113 holds a foam material 21 attached and fixed to the tip of the pin 113 at a predetermined position of the outer panel 7 by stretching the pin 113 substantially along the extending direction Y which is also the extending direction of the outer panel 7. The predetermined position of the outer panel 7 where the foam material 21 is held is a position near the lower end of the outer panel 7 and is a position that becomes the internal space F of the closed cross-section structure 11 after joining the outer panel 7 and the inner panel 6. It is assumed that the outer panel 7 has been attached to the vehicle structure 100 before the holding step S1.

[0031] The jig 111 is an automatically controllable device such as a linear actuator, for example, and expands and contracts the pin 113 along the extending direction Y.

[0032] The foaming material 21 foams upon heating to become the foam 15. The foaming material 21 is a member derived from a resin obtained by kneading a thermoplastic resin as a base resin and a heat-decomposable foaming agent. The foaming ratio (expansion ratio) of the foaming material 21 depends on the type and blending amount of the thermoplastic resin, as well as the type and blending amount of the foaming material 21. For example, it is about 2 to 30 times.

[0033] The melting temperature of the thermoplastic resin is, for example, 100 to 120 degrees Celsius. Also, the heat-decomposable foaming agent foams, for example, when heated at 150 degrees Celsius for 20 minutes as the foaming conditions.

[0034] FIG. 6 is a view showing a first example of the foaming material 21 held in the holding step S1 of the manufacturing method of the vehicle front pillar 1 according to the embodiment of the present invention.

[0035] As shown in FIG. 6, the shape of the foaming material 21 is preferably a hollow cylindrical shape. In this case, the foaming material 21 has a first through-hole 23 penetrating in the vertical direction. The tip of the pin 113 of the jig 111 may be inserted into the first through-hole 23 and the pin 113 may be used to hold the foaming material 21. Note that the first through-hole 23 disappears when the foaming material 21 foams and expands upon heating in the heating step S5.

[0036] Next, in the joining step S2 following the holding step S1, the flange portion 5 of the inner panel 6 is joined to the outer panel 7 by spot welding. At this time, the closed cross-sectional structure 11 of the vehicle front pillar 1 is formed. At the lower end of the closed cross-sectional structure 11, an open opening 19 communicating with the internal space F of the closed cross-sectional structure 11 and a closed portion 17 blocked by the flange portion 5 are formed. The pin 113 of the jig 111 penetrates the opening 19 at the lower end of the closed cross-sectional structure 11. That is, the inner panel 6 is joined to the outer panel 7 in a substantially non-contact state with the pin 113 of the jig 111.

[0037] FIG. 7 is a view showing the foam material 21 of the first example immediately after the leaving step S3 of the manufacturing method of the vehicle front pillar 1 according to the embodiment of the present invention. Note that FIG. 7 is a view of the vehicle front pillar 1 immediately after the leaving step S3 as viewed from the outside of the vehicle.

[0038] As shown in FIG. 5(B), in the leaving step S3 following the joining step S2, the jig 111 contracts the pin 113 along the extending direction Y, and the foam material 21 at the tip of the pin 113 is brought into contact with the curved portion 5a of the flange portion 5, that is, the closing portion 17 at the lower end of the closed cross-sectional structure 11, from the inside of the closed cross-sectional structure 11. As shown in FIG. 7 in addition to FIG. 5(B), the foam material 21 that has hit the closing portion 17 is separated from the tip of the pin 113 and is left in a movable state inside the closed cross-sectional structure 11, while the pin 113 from which the foam material 21 has been separated passes through the opening 19 and exits from the internal space F of the closed cross-sectional structure 11. That is, the pin 113 of the jig 111 can pass through the opening 19 of the closed cross-sectional structure 11, and the foam material 21 cannot pass through the opening 19 of the closed cross-sectional structure 11. In other words, the opening shape of the opening 19 of the closed cross-sectional structure 11 encloses the cross-sectional shape of the pin 113 in the cross-section orthogonal to the extending direction Y, and the size and shape of the foam material 21 have portions protruding from the opening shape of the opening 19 when viewed from any direction.

[0039] In the manufacturing method of the vehicle front pillar 1, the foam material 21 that cannot pass through the opening 19 is placed in a location that will become the internal space F of the closed cross-sectional structure 11 in the holding step S1 before the joining step S2 in which the closed cross-sectional structure 11 is formed. Then, in the leaving step S3 following the joining step S2, the foam material 21 is left in the internal space F of the closed cross-sectional structure 11, and the pin 113 of the jig 111 is withdrawn from the closed cross-sectional structure 11 through the opening 19. The foam material 21 left in the internal space F of the closed cross-sectional structure 11 can move around in the internal space F away from the inner circumference of the closed cross-sectional structure 11.

[0040] FIG. 8 is an enlarged view of the A′-A′ cross-section of FIG. 5(B). Note that FIG. 8 is a cross-sectional view taken by cutting the vehicle front pillar 1 in the leaving step S3 shown in FIG. 5(B) perpendicular to the extending direction Y with reference to the line A′-A′.

[0041] As shown in FIG. 8, the foam material 21 immediately after the placement step S3 is placed in the internal space F of the closed cross-sectional structure 11 of the vehicle front pillar 1. Further, the foam material 21 is in a movable state at least within the range of the virtual circle C. At this time, it is preferable that a gap of, for example, between 1.5 millimeters (mm) and 3.0 millimeters (mm) is formed between the outer peripheral surface of the foam material 21 and the inner peripheral surface of the closed cross-sectional structure 11.

[0042] In the electrocoating step S4 following the placement step S3, the vehicle body including the vehicle structure 100 is immersed in, for example, a tank containing an aqueous electrocoating paint, and an electrocoating process for forming an electrocoating film, which is a coating film of the electrocoating paint, on the vehicle body surface is performed. In the electrocoating process, usually, the electrocoating paint in the tank is made positive and the vehicle body is made negative to pass an electric current, and the electrocoating paint is deposited on the surface of the vehicle body to form an electrocoating film. Thereafter, a water washing process for washing the vehicle body on which the electrocoating film has been formed with washing water is performed. The foam material 21 that is placed in the internal space F of the closed cross-sectional structure 11 and has not yet foamed can move away from and rotate around the inner peripheral surface of the closed cross-sectional structure 11. Therefore, in the electrocoating step S4, the entire inner circumference of the closed cross-sectional structure 11 comes into contact with the electrocoating, and the electrocoating paint is deposited over the entire inner circumference of the closed cross-sectional structure 11. As a result, an electrocoating film is formed over the entire inner circumference of the closed cross-sectional structure 11.

[0043] In the heating step S5 following the electrocoating step S4, a draining process is performed to remove the electrocoating paint and the washing water remaining on the vehicle body after the water washing process in the electrocoating step S4 by air blowing. Thereafter, the vehicle body on which the draining process has been performed is moved inside a heating furnace, and in the heating furnace, it is heated, for example, under the conditions of 150 degrees Celsius for 20 minutes or more to cure the electrocoating film to form an electrocoating film 13 and to foam the foam material 21 to form a foam body 15.

[0044] Also, in the placing step S3, it is preferable that the foam material 21 is placed such that the longitudinal direction of the foam material 21 is along the extending direction of the closed cross-section structure 11, that is, the extending direction Y of the vehicle front pillar 1. By doing so, in the subsequent electrodeposition coating step S4, the electrodeposition paint flows through the first through-hole 23 of the foam material 21, suppressing a decrease in the fluidity of the electrodeposition paint inside the closed cross-section structure 11. In the electrodeposition coating step S4, the length in the longitudinal direction of the foam material 21, that is, the height dimension in the vertical direction, is preferably larger than the dimension of the diameter of the virtual circle C so that the orientation of the foam material 21 does not change excessively inside the closed cross-section structure 11 due to the flow of the electrodeposition paint.

[0045] FIG. 9 is a view showing a second example of the foam material 21A held in the holding step S1 of the manufacturing method of the vehicle front pillar 1 according to the embodiment of the present invention.

[0046] As shown in FIG. 9, in addition to the first through-hole 23 penetrating in the vertical direction, the foam material 21A preferably has a plurality of second through-holes 25 penetrating from the outer peripheral surface of the foam material 21A toward the central axis of the foam material 21A. By doing so, in the electrodeposition coating step S4, the electrodeposition paint flows not only through the first through-hole 23 but also through the plurality of second through-holes 25, further suppressing a decrease in the fluidity of the electrodeposition paint inside the closed cross-section structure 11. Note that the second through-hole 25 disappears when the foam material 21A foams and expands when heated in the heating step S5, similar to the first through-hole 23.

[0047] FIG. 10(A) is a view showing a third example of the foam material 21B held in the holding step S1 of the manufacturing method of the vehicle front pillar 1 according to the embodiment of the present invention, FIG. 10(B) is a view showing the third example of the foam material 21B placed inside the closed cross-section structure 11 in the placing step S3 of the manufacturing method of the vehicle front pillar 1 according to the embodiment of the present invention, and FIG. 10(C) is an enlarged view of the A′-A′ cross-section of FIG. 10(A).

[0048] Also, as shown in FIGS. 10(A) to 10(C), the shape of the foam material 21B is preferably a shape that follows the cross-sectional shape of the closed cross-sectional structure 11 in which the foam material 21 is placed. By doing so, when heated in the heating step S5, the foam 15 is surely filled up to the corners of the internal space F of the closed cross-sectional structure 11. The foam material 21B is preferably, for example, in a substantially triangular prism shape having a first through hole 23 penetrating in the vertical direction.

[0049] FIG. 11(A) is a view showing the arrangement of the foam material 21 immediately after the placement step S3 of the manufacturing method of the vehicle front pillar 1 according to the embodiment of the present invention, and FIG. 11(B) is an enlarged view of the B-B cross-section of FIG. 11(A). Note that FIG. 11(B) is a cross-sectional view cut so as to be orthogonal to the extending direction Y with respect to the B-B line of the vehicle front pillar 1 in the placement step S3 shown in FIG. 11(A). Further, in FIG. 11(B), for convenience of explanation, a part of the inner panel 6 shown only in the A'-A' cross-section of FIG. 11(A) is shown by a two-dot chain line.

[0050] As shown in FIGS. 11(A) and 11(B), the closed cross-sectional structure 11 is preferably narrowed at a location above the location where the foam material 21 is placed in the placement step S3 so that the foam material 21 cannot pass through. That is, at the location of the B-B cross-section in the closed cross-sectional structure 11, it is preferable that the foam material 21 is narrowed so as to prevent the foam material 21 from moving upward from that location. By doing so, in the electrodeposition coating step S4, the foam material 21 is prevented from being washed away by the electrodeposition coating flowing into the internal space F of the closed cross-sectional structure 11 and excessively moving above the closed cross-sectional structure 11. Therefore, in the heating step S5, the foam material 21 does not foam at an unexpected location in the internal space F of the closed cross-sectional structure 11.

[0051] As described above, the manufacturing method of the vehicle front pillar 1 according to the present embodiment includes a holding step S1 of holding the foam material 21 having a size that cannot pass through the opening 19 at a predetermined position of the outer panel 7 using the jig 111, a joining step S2 of joining the flange portion 5 and the outer panel 7 so that the jig 111 penetrates through the opening 19, a leaving step S3 of pulling out the jig 111 from the opening 19 and leaving the foam material 21 inside the closed cross-section structure 11, an electrodeposition coating step S4 of forming an electrodeposition coating film on the vehicle front pillar 1 by electrodeposition coating, and a heating step S5 of heating in a heating furnace to cure the electrodeposition coating film to form the electrodeposition coating film 13 and to foam the foam material 21 to form the foam 15.

[0052] A series of steps from the holding step S1 to the leaving step S3 until the foam material 21 is left in the internal space F of the closed cross-section structure 11 are carried out by the cooperation of the operator and the jig 111 before and after the operator who is engaged in the vehicle body assembly process of the automobile sets the inner panel 6 to be welded to the outer panel 7. That is, the holding step S1 to the leaving step S3 can be easily and efficiently carried out in the normal flow of the vehicle body assembly process. Therefore, the manufacturing method of the vehicle front pillar 1 and the vehicle front pillar 1 can have excellent manufacturability.

[0053] Also, the foam material 21 left in the internal space F of the closed cross-section structure 11 in the leaving step S3 is in a movable state in the internal space F of the closed cross-section structure 11 until it is heated in the heating step S5. That is, a gap is generated between the foam material 21 and the inner peripheral surface of the closed cross-section structure 11. Therefore, in the electrodeposition coating step S4, the electrodeposition coating material can flow into this gap to form an electrodeposition coating film over the entire inner peripheral surface of the closed cross-section structure 11. In other words, in the heating step S5, when heated, the vehicle front pillar 1 can be provided with the electrodeposition coating film 13 formed over the entire inner peripheral surface of the closed cross-section structure 11. Therefore, the vehicle front pillar 1 manufactured by the manufacturing method of the vehicle front pillar 1 according to the present embodiment can have high rust prevention properties.

[0054] Furthermore, the manufacturing method of the vehicle front pillar 1 according to the present embodiment includes a placing step S3 of placing a foam material 21 having a hollow cylindrical shape and having a first through hole 23 such that the longitudinal direction of the foam material 21 is along the extending direction Y of the closed cross-sectional structure 11. Therefore, in the subsequent electrodeposition coating step S4 of the manufacturing method of the vehicle front pillar 1, it is possible to suppress a decrease in the fluidity of the electrodeposition coating inside the closed cross-sectional structure 11 as the electrodeposition coating flows through the first through hole 23 of the foam material 21.

[0055] Also, the manufacturing method of the vehicle front pillar 1 according to the present embodiment includes a placing step S3 of placing a foam material 21A having a plurality of second through holes 25 penetrating from the outer peripheral surface toward the central axis such that the longitudinal direction of the foam material 21A is along the extending direction Y of the closed cross-sectional structure 11. Therefore, in the subsequent electrodeposition coating step S4 of the manufacturing method of the vehicle front pillar 1, it is possible to further suppress a decrease in the fluidity of the electrodeposition coating inside the closed cross-sectional structure 11 as the electrodeposition coating flows through the first through hole 23 and the second through holes 25 of the foam material 21A.

[0056] Also, the manufacturing method of the vehicle front pillar 1 according to the present embodiment includes a placing step S3 of placing the foam material 21 inside the closed cross-sectional structure 11 that is narrowed so that the foam material 21 cannot pass through at a location above the location where the foam material 21 is placed, such that the longitudinal direction of the foam material 21 is along the extending direction Y of the closed cross-sectional structure 11. Therefore, in the electrodeposition coating step S4, the foam material 21 is prevented from being washed away by the electrodeposition coating flowing into the internal space F of the closed cross-sectional structure 11 and excessively moving above the closed cross-sectional structure 11. Therefore, in the heating step S5 of the manufacturing method of the vehicle front pillar 1, it is possible to prevent the foam material 21 from deviating from the location where it was placed in the placing step S3 and foaming at an unexpected location above the closed cross-sectional structure 11.

[0057] Therefore, according to the manufacturing method of the vehicle front pillar 1 and the vehicle front pillar 1 according to the present embodiment, it is possible to improve the rust prevention property while having excellent manufacturability.

[0058] Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0059] 1... Vehicle front pillar, 3... First front pillar, 4... Second front pillar, 5... Flange portion, 5a... Curved portion, 6... Inner panel, 7... Outer panel, 11... Closed cross-sectional structure, 13... Electrodeposition coating film, 15... Foam, 17... Closed portion, 19... Opening, 21, 21A, 21B... Foaming material, 23... First through hole, 25... Second through hole, 100... Vehicle structure, 101... Opening for front door, 111... Fixture, 113... Pin, C... Virtual circle, F... Internal space, S1... Holding process, S2... Joining process, S3... Retention process, S4... Electrodeposition coating process, S5... Heating process, X... Arrow (front-rear direction), Y... Arrow (extending direction).

Claims

1. An inner panel having a flange portion, An outer panel joined to the flange portion, An electrodeposition coating film formed over the entire inner peripheral surface of a closed cross-sectional structure formed by joining the flange portion and the outer panel, A foam filling the inside of the electrodeposition coating film on the inner periphery of the closed cross-sectional structure, and comprising: A method for manufacturing a vehicle front pillar disposed in front of an opening for a vehicle front door, wherein a closed portion closed by the flange portion and an open portion that is open without being closed are provided at a lower end of the closed cross-sectional structure, A holding step of holding a foam material having a size that cannot pass through the opening at a predetermined position of the outer panel using a jig, A joining step of joining the flange portion and the outer panel so that the jig penetrates the opening, A leaving step of pulling out the jig from the opening and leaving the foam material inside the closed cross-sectional structure, An electrodeposition coating step of forming an electrodeposition coating film on the vehicle front pillar by electrodeposition coating, A heating step of heating in a heating furnace to cure the electrodeposition coating film to form the electrodeposition coating film and to foam the foam material to form the foam, the method for manufacturing a vehicle front pillar including the steps.

2. The shape of the foam material is a hollow cylindrical shape, In the leaving step, the foam material is left so that the longitudinal direction of the foam material is along the extending direction of the closed cross-sectional structure. The method for manufacturing a vehicle front pillar according to claim 1.

3. The foam material has a plurality of through holes penetrating from an outer peripheral surface of the foam material toward a central axis of the foam material. The method for manufacturing a vehicle front pillar according to claim 2.

4. The manufacturing method of a vehicle front pillar according to claim 2, wherein the closed cross-section structure is narrowed so that the foam material cannot pass through at a position above the position where the foam material is placed.

5. An inner panel having a flange portion, An outer panel joined to the flange portion, An electrodeposition coating film formed over the entire inner circumference of the closed cross-section structure generated by joining the flange portion and the outer panel, A foam that fills the inside of the electrodeposition coating film on the inner circumference of the closed cross-section structure, and A vehicle front pillar provided with a closed portion closed by the flange portion and an opening portion that is open without being closed at the lower end of the closed cross-section structure.

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