JP6191648B2 - Resin body built-in frame structure for vehicle and manufacturing method thereof - Google Patents

Description

  The present invention relates to a resin body built-in frame structure for a vehicle and a manufacturing method thereof.

  In some vehicles, as shown in Patent Document 1, in order to reinforce a frame while suppressing an increase in weight, a resin body having a rib structure is incorporated in a closed cross section of the frame. Patent Document 2 discloses one in which a void is formed in order to eliminate the thermal distortion of the resin around the metal body during insert molding.

JP 2001-191947 A Japanese Patent Laid-Open No. 05-124058

  When the resin body is built in the closed cross section of the frame, it is not preferable to join the resin body to the frame with an adhesive from the viewpoints of rust prevention and quality. For this reason, it is conceivable that the resin body is directly joined to the frame without using an adhesive, for example, by insert molding. The joining of the resin body to the frame by the insert molding is not particularly problematic as long as it is used as it is.

  However, in the case of a vehicle, the entire vehicle body including a frame incorporating a resin body is usually electrodeposited to prevent rust. In this case, since the paint is dried in the drying furnace after the electrodeposition coating, the coating is subjected to a heating action at a considerably high temperature (for example, heating at a temperature of about 150 ° C. for about 20 minutes). When subjected to a heating action, a large stress concentration occurs due to a large difference in thermal expansion between the resin body and the frame, and cracks are likely to occur near the joint surface to the frame on the side wall surface of the resin body. When this crack occurs, moisture and air enter from the cracked part, which causes rust.

  The present invention has been made in view of the above circumstances. The first object of the present invention is to apply the resin body to the frame even if it is subjected to a heating action when the resin body is directly joined to the frame. It is an object of the present invention to provide a vehicle built-in resin body frame structure capable of preventing the occurrence of cracks at a joint portion. The second object of the present invention is to provide a method for manufacturing a resin body built-in frame structure for a vehicle that can achieve the first object.

In order to achieve the first object, the following solution is adopted in the present invention. That is, as described in claim 1,
A resin body built-in frame structure for a vehicle in which a reinforcing resin body is disposed in a closed cross section of the frame,
The resin body is directly bonded to the frame without using an adhesive,
The side wall surface of the resin body at the joint portion between the frame and the resin body is formed so as to become thinner as the position of the upper edge portion of the side wall surface is set as the reference position, and away from the reference position. , It is formed in a curved shape so that the degree of thinning is large at a position close to the reference position and small at a position far from the reference position .
It is like that. According to the above-described solution technique, the shape of the side wall surface of the resin body can be appropriately set as a shape that does not generate a large stress concentration that causes cracks when heated. Can prevent cracking when receiving. Further, in order to prevent cracks, it is only necessary to set the shape of a curved shape, which is preferable for easy implementation and for preventing an increase in cost.

Preferred embodiments based on the above solution are as described in claims 2 to 6. That is,
The curved shape is configured to substantially coincide with a curve of a stress intensity factor between the resin body and the frame (corresponding to claim 2). In this case, it is preferable to sufficiently exhibit the effect corresponding to the first aspect.

  The resin body is insert-molded in the frame (corresponding to claim 3). In this case, the resin body having a predetermined curved shape and the joining of the resin body to the frame can be simultaneously performed by insert molding.

The resin body is a rib structure having a substrate portion joined to the frame, and a plurality of rib portions extending from the substrate portion and extending in a direction in which a closed cross section of the frame is crushed and deformed when a vehicle collides,
The side wall surface of the substrate part is formed in the curved shape,
(Corresponding to claim 4). In this case, it is preferable to effectively absorb energy at the time of collision while reducing the weight and reducing the amount of resin used by utilizing the rib structure. Further, it is also preferable for making the substrate portion as thin as possible for preventing cracks.

The frame on which the resin body is disposed is connected to another frame having a closed cross section;
The resin body is disposed so as to straddle the connecting portion between the frame on which the resin body is disposed and the other frame.
(Corresponding to claim 5). In this case, it is preferable when reinforcing the connection part of frames.

The frame on which the resin body is disposed is a roof side rail,
The other frame is a pillar connected to the roof side rail.
(Corresponding to claim 6). In this case, it is preferable to reinforce the connecting portion between the roof side rail and the pillar, and to effectively absorb energy by the resin body particularly at the time of a side collision.

In order to achieve the second object, the following solution is adopted in the present invention. That is, as described in claim 7,
A method of manufacturing a resin body-embedded frame structure for a vehicle in which a reinforcing resin body is disposed in a closed cross section of the frame,
A first step of joining the resin body directly to the frame without using an adhesive by insert molding a resin body into the frame;
A second step of electrodepositing the frame together with the resin body after the first step;
After the second step, a third step of drying the paint in a drying furnace;
With
At the time of insert molding in the first step, the side wall surface of the resin body at the joint portion between the frame and the resin body is separated from the reference position when the position of the upper edge portion of the side wall surface is set as the reference position. It is formed as a curved shape so that the degree of thinning is large at a position close to the reference position and small when it is far from the reference position .
It is like that. According to the above solution, it is possible to provide a method for manufacturing a resin body built-in frame structure for a vehicle that exhibits the effects corresponding to claims 1 and 3.

A preferred embodiment based on the above solution is as described in claim 8. That is,
The curved shape is formed so as to substantially match the curve of the stress intensity factor between the resin body and the frame (corresponding to claim 8). In this case, it is possible to provide a method for manufacturing a resin body built-in frame structure for a vehicle that exhibits the effect corresponding to claim 2.

  According to the present invention, when the resin body is directly joined to the frame, it is possible to prevent the occurrence of cracks at the joining portion of the resin body to the frame even when subjected to a heating action.

The side view which shows the vehicle body frame | skeleton part of the vehicle to which this invention was applied. The principal part side view which shows the example of arrangement | positioning to the roof side rail of a resin body. FIG. 3 is a cross-sectional view corresponding to line X3-X3 in FIG. 1. FIG. 4 is a cross-sectional perspective view of a main part in a state where an inner panel portion is removed from the state of FIG. 3 and a resin body is exposed. The figure which shows the characteristic line of a stress intensity factor. The principal part expanded sectional view which shows the example of curve shape of the side wall surface of a resin body. The figure which shows the effect of this invention typically.

  In FIG. 1 showing a body (frame) portion of an automobile as a vehicle, 1 is a side sill, 2 is a hinge pillar, 3 is an A pillar (front pillar), 4 is a B pillar (center pillar), 5 is a C pillar (rear pillar), 6 is a roof side rail and 7 is a roof. The opening between the A pillar 3 and the B pillar 4 is a front side opening 8 for getting on and off the front seat occupant, and the opening between the B pillar 4 and the C pillar 5 is getting on and off the rear seat occupant. The rear side opening 9 is used.

  A resin body 20 described later is disposed in the roof side rail 6. The resin body 20 is elongated in the front-rear direction and is disposed so as to straddle the B pillar 4.

  FIG. 3 shows an example of a connecting portion between the upper part of the B pillar 4 and the roof side rail 6. In FIG. 3, the roof side rail 6 has a closed cross section D <b> 1 formed by an inner panel 31 and an outer panel 32. Further, the inner panel 41 of the B pillar 4 is joined to the lower portions of the panels 31 and 32. Further, the outer panel 42 of the B pillar 4 is joined to the upper part of the inner panel 31 and the outer panel 32 to form a closed section D <b> 2 between the outer panel 32. Further, the reinforcement 43 of the B pillar 4 is joined to the outer surface side of the outer panel 32. Thus, the roof side rail 6 is configured as a structure having double closed cross sections D1 and D2 using the B pillar 4 as well.

  An outer edge portion of the roof 7 in the vehicle width direction is joined to the upper portion of the roof side rail 6. In addition, a cross member 35 joined to the lower surface of the roof 7 is joined to the upper portion of the roof side rail 6 via a connection bracket 36.

  A resin body 20 is disposed in the closed cross section D1. The resin body 20 is formed of a thermosetting resin reinforced with reinforcing fibers (glass fibers or carbon fibers). As shown in FIG. 4, the resin body 20 includes a substrate portion 21 directly joined to the outer panel 32 and vertical and horizontal rib portions 22 and 23 extending from the substrate portion 21 toward the inner side in the vehicle width direction. Have. A rectangular box-shaped space is formed by the vertical rib portion 22 extending substantially in the vertical direction and the horizontal rib portion 23 extending substantially in the horizontal direction. Each rib portion 22, 23 extends to the immediate vicinity of the inner panel 31.

  As described above, the resin body 20 has a rib structure so that the rigidity toward the vehicle width direction is large while reducing the weight and reducing the cost (reducing the amount of resin material and reinforcing fibers used). Is formed. Further, since the resin body 20 has a rib structure, the rib portions 22 and 23 are crushed and deformed when receiving a large external force from the outer side in the vehicle width direction at the time of a collision (at the time of a side collision). Energy absorption is effectively performed.

  The resin body 20 is directly bonded to the outer panel 32 without using an adhesive. Specifically, the resin body 20 is formed by insert molding with respect to the outer panel 32, and is joined to the outer panel 32 at the time of this insert molding.

  The thermal expansion coefficient of the resin body 20 and the outer panel 32 to which the resin body 20 is joined are greatly different. For this reason, when it receives the heating action (for example, 20 minutes at 150 degree C) in the drying process in the drying furnace after performing the electrodeposition coating as rust prevention, the joining part to the outer panel 32 in the resin body 20 Cracks are likely to occur at the end portions of these due to stress concentration based on the difference in thermal expansion. That is, the side wall surface of the substrate portion 21 in the resin body 20 is likely to cause the crack.

  In order to prevent the cracks, as shown in FIG. 6, the shape of the portion of the side wall surface 21a of the substrate portion 21 closest to the outer panel 32 is set as a unique curved shape. The curved shape will be described. First, the position of the upper edge portion of the substrate portion 21 is set as the reference position 0. At this time, the side wall surface 21a is formed to be curved so that the thickness from the outer panel 32 decreases as the distance from the reference position 0 increases. In this case, the degree of thinning is increased at a position close to the reference position, and is decreased when the position is somewhat distant from the reference position. In other words, the curved shape is set as a shape that becomes concave toward the surface of the outer panel 32. Such a curved shape is formed over the entire peripheral portion of the substrate portion 21 (the entire peripheral portion of the portion joined to the outer panel 32).

  The curved shape is preferably set so as to substantially match the characteristic line of the stress intensity factor between the resin body 20 and the outer panel 32. The characteristic line α of the stress intensity factor is shown in FIG. 5, and the special line α shown in FIG. 5 is indicated by a broken line in FIG. If the stress intensity factor is 1 or less, cracks at the end of the substrate portion 21 due to a difference in thermal expansion are prevented. In the embodiment, the thickness of the side wall surface 21a is set to be almost completely coincident with the characteristic line α of the stress intensity factor at a position relatively away from the surface of the outer panel 32, and near the surface of the outer panel 32, By making the thickness smaller than the thickness corresponding to the characteristic line α of the stress intensity factor, cracks are more reliably prevented.

  FIG. 7 schematically shows the effect of the present invention. That is, in FIG. 7, the alternate long and short dash line indicates a case where the shape of the side wall surface 21 a of the substrate portion 21 is formed as a bluff shape substantially orthogonal to the outer panel 32 (in FIG. 6, the side wall surface 21 a of the substrate portion 21 is In the case of a shape along the one-dot chain line in FIG. 6 that does not exist in the right part from the reference position 0). In this case, a portion having a stress intensity factor considerably larger than 1 is present, and cracking is likely to occur when subjected to a heating action in the drying process. On the other hand, in the case of the present invention indicated by the solid line in FIG. 7 (when the curved shape as shown in FIG. 6 is adopted), the stress intensity factor becomes 1 or less, and cracking occurs even when subjected to the heating action in the drying process. It will not occur.

  Next, the stress concentration based on the difference in thermal expansion acting on the joint portion of the resin (resin body 20) to the metal (outer panel 32) will be described. In the following description, the subscript “p” indicates the resin (corresponding to the resin body 20), and the subscript “m” indicates the metal (corresponding to the outer panel 32). First, the linear expansion coefficients of the resin and metal are αp and αm, the Young's modulus is Ep and Em, the shape cross-sectional area is Ap and Am, the initial length is L, and the temperature change is ΔT. At this time, elongation amounts ΔLp and ΔLm due to linear expansion of the resin body and the metal are expressed by the following equations (1) and (2).

  The force F acting on both parts of the parts joined by integral joining is balanced at the joining interface with the same magnitude and opposite directions, so that the resin having a large expansion is compressed and the metal is pulled. The elongations Δlp and Δlm of the metal due to the force F are expressed by the following equations (3) and (4) using the Hooke's law. The expression “−” indicates the compression direction.

  The following equation (5) is expressed from the relationship that the amounts of extension of the resin and the metal are equal at the interface between the resin and the metal.

  By substituting Equation (1), Equation (2), Equation (3), and Equation (4) into Equation (5), the following Equation (6) is obtained.

  Equation (6) is transformed to obtain Equation (7).

  Since the fracture is controlled by the resin, the stress σ for the fracture acting on the resin is expressed by the following equation (8).

  In the resin end portion in the integral molding joining, the joining end portion exists as a singular point, and stress expansion occurs. In the stress concentration distribution by FEM analysis, the stress value σe at the joint interface end where the stress is the largest is obtained by the following equation (9) using the equation (8) and the stress intensity factor k.

  From the above equation (9), the shape of the joint end of the resin (the curved shape of the side wall surface) is made to substantially coincide with the stress intensity factor k, thereby preventing cracks at the resin end due to the difference in thermal expansion. Will be. In other words, if the thickness of the joint end portion of the resin is set so that the stress intensity factor is 1 or less, cracking is prevented.

  Although the embodiments have been described above, the present invention is not limited to the embodiments, and appropriate modifications can be made within the scope of the claims. As a frame in which the resin body 20 is built, in addition to the roof side rail 6, a side sill 1, a hinge pillar 2, an A pillar 3, a C pillar 4, various cross members, and other appropriate strength members constituting a closed cross section are used. Can do. As the arrangement position of the resin body 20, it is preferable to select a connection portion with another frame, and in particular, the resin body 20 is arranged so as to straddle another frame (extend in a direction intersecting with the extending direction of the other frame). It is preferable to do this. The resin bodies 20 are not long continuous ones, and a plurality of short ones may be arranged in series at intervals, and the size, shape, arrangement position, number of arrangements, and the like can be selected as appropriate. Of course, the object of the present invention is not limited to what is explicitly stated, but also implicitly includes providing what is substantially preferred or expressed as an advantage.

  The present invention can provide a frame reinforcing structure suitable for a vehicle.

4: B pillar (other frames)
6: Roof side rail 20: Resin body 21: Substrate part 21a: Side wall surface (curved shape)
22: Rib part (vertical)
23: Rib part (horizontal)
D1: Closed section α: Characteristic line of stress intensity factor

Claims (8)

A resin body built-in frame structure for a vehicle in which a reinforcing resin body is disposed in a closed cross section of the frame,
The resin body is directly bonded to the frame without using an adhesive,
The side wall surface of the resin body at the joint portion between the frame and the resin body is formed so as to become thinner as the position of the upper edge portion of the side wall surface is set as the reference position, and away from the reference position. , It is formed in a curved shape so that the degree of thinning is large at a position close to the reference position and small at a position far from the reference position .
A frame structure with a built-in resin body for a vehicle. In claim 1,
A frame structure with a built-in resin body for a vehicle, wherein the curved shape is a shape that substantially matches a curve of a stress intensity factor between the resin body and the frame. In claim 1 or claim 2,
A resin-embedded frame structure for a vehicle, wherein the resin body is insert-molded in the frame. In any one of Claims 1 thru | or 3,
The resin body is a rib structure having a substrate portion joined to the frame, and a plurality of rib portions extending from the substrate portion and extending in a direction in which a closed cross section of the frame is crushed and deformed when a vehicle collides,
The side wall surface of the substrate part is formed in the curved shape,
A frame structure with a built-in resin body for a vehicle. In any one of Claims 1 thru | or 4,
The frame on which the resin body is disposed is connected to another frame having a closed cross section;
The resin body is disposed so as to straddle the connecting portion between the frame on which the resin body is disposed and the other frame.
A frame structure with a built-in resin body for a vehicle. In claim 5,
The frame on which the resin body is disposed is a roof side rail,
The other frame is a pillar connected to the roof side rail.
A frame structure with a built-in resin body for a vehicle. A method of manufacturing a resin body-embedded frame structure for a vehicle in which a reinforcing resin body is disposed in a closed cross section of the frame,
A first step of joining the resin body directly to the frame without using an adhesive by insert molding a resin body into the frame;
A second step of electrodepositing the frame together with the resin body after the first step;
After the second step, a third step of drying the paint in a drying furnace;
With
At the time of insert molding in the first step, the side wall surface of the resin body at the joint portion between the frame and the resin body is separated from the reference position when the position of the upper edge portion of the side wall surface is set as the reference position. It is formed as a curved shape so that the degree of thinning is large at a position close to the reference position and small when it is far from the reference position .
A method of manufacturing a resin-built-in frame structure for a vehicle, characterized in that: In claim 7,
The method of manufacturing a resin body-embedded frame structure for a vehicle, wherein the curved shape is a shape that substantially matches a curve of a stress intensity factor between the resin body and the frame.

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