JP2011255749A - Vehicle body structure and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent a contact portion of dissimilar metal from being electrically eroded with a simple structure.SOLUTION: In a vehicle body structure and its manufacturing method, a vehicular structure (a shock absorbing member 3) for a vehicle made of an aluminum alloy casting material is coupled to a vehicle body side member (a rear side frame 1) made of a ferrous material. The vehicular structure is provided with a mounting flange 19 connected to the vehicle body side member through a connection member (a connecting bolt 18) and a bobbin-like member 31 formed of ferrous material having a through hole of the connection member. The body of the bobbin-like member 31 is cast in the mounting flange 19 with the end surface of the bobbin-like member 31 projected outward from the end surface of the mounting flange 19.

Description

  The present invention relates to a vehicle body structure in which a vehicle structure made of an aluminum alloy casting is connected to a vehicle body side member made of an iron-based material, and a method for manufacturing the same.

  Conventionally, in order to improve the fuel efficiency of automobiles and to reduce the environmental load accompanying this, the thickness of the steel plate constituting the vehicle body is reduced, or instead of the steel plate material, an aluminum plate material or extruded material It has been attempted to reduce the weight of the vehicle body, for example, by using a cable. For example, as shown in Patent Document 1 below, the thickness of the hollow portion made of an aluminum alloy casting is changed continuously or partially along the axial direction, so that it is constant during a vehicle collision. An impact-absorbing member made of an aluminum alloy casting has been known that has excellent shock-absorbing ability by being plastically deformed in a bellows shape in the axial direction in a deformation mode, and can be easily formed in a single casting process. Yes.

JP 2002-39245 A

  As disclosed in Patent Document 1 above, when a vehicle structure made of an impact absorbing member formed of an aluminum alloy casting material is connected to a rear side frame that is a vehicle body side member made of an iron-based material, etc. In addition, since there is a possibility that electric corrosion occurs due to the current flowing through the portion where these different metals are in contact, by forming an electrodeposition coating on the contact surface between the vehicle structure and the vehicle body side member, Prevention of the occurrence of electrolytic corrosion is being carried out. For example, before connecting the vehicle structure and the vehicle body side member, electrodeposition coating is applied in separate steps, or the vehicle structure and the vehicle body side member are temporarily fixed to separate them. In this state, after the electrodeposition coating is performed by immersing them in the electrodeposition coating liquid, the vehicle structure and the vehicle body side member are firmly connected, but these operations are complicated. Therefore, there are problems such as high manufacturing costs.

  The present invention has been made in view of the above-described problems, and an object thereof is to effectively prevent the occurrence of electrolytic corrosion at a contact portion of different metals with a simple structure.

  The invention according to claim 1 is a vehicle body structure in which a vehicle structure body made of an aluminum alloy casting material is connected to a vehicle body side member made of an iron-based material, and the vehicle structure body includes the vehicle body side member. A mounting flange connected through the connecting member and a bobbin-shaped member made of an iron-based material having an insertion hole for the connecting member are provided, and the end surface of the bobbin-shaped member is outward from the end surface of the mounting flange. The body portion of the bobbin-like member is cast into the mounting flange in a state of protruding in the shape.

  According to a second aspect of the present invention, in the vehicle body structure according to the first aspect, a vehicle body side member comprising a side frame in which the vehicle structural body extends in the front-rear direction of the vehicle, a bumper reinforcement extending in the vehicle width direction, and The shock absorbing member is disposed between the mounting flanges of the shock absorbing member and connected to the side frame via connecting bolts.

  According to a third aspect of the present invention, in the vehicle body structure according to the first or second aspect, an electrodeposition coating film is formed on each of the end surface of the mounting flange and the wall surface of the vehicle body side member facing the mounting flange. It is.

  The invention according to claim 4 is the vehicle body structure according to any one of claims 1 to 3, wherein a plurality of recesses are formed on the back surface of the mounting flange.

  The invention according to claim 5 is a method of manufacturing a vehicle body structure in which a mounting flange of a vehicle structure made of an aluminum alloy casting material is connected to a vehicle body side member made of the iron-based material by a connecting member. A bobbin-shaped member made of an iron-based material having an insertion hole for the connecting member is disposed in a flange forming space formed between a movable mold and a fixed mold constituting the metal mold, and the end surface thereof is flanged A mold closing step of closing the movable mold and the fixed mold in a state protruding from the molding space; and a molten aluminum alloy is injected into the cavity of the vehicle structure mold to A casting step of casting the structural body, a connecting step of connecting a mounting flange of the vehicle structural body cast in the casting step to the vehicle body side member by a connecting member, an end surface of the mounting flange, and a vehicle body opposite thereto side By advancing the electrodeposition coating fluid between the wall of those having a electrodeposition coating step of forming an electrodeposition coating film on each side.

  In the invention according to claim 1, in order to reduce the weight of the vehicle body, the vehicle structure is formed of an aluminum alloy casting material, and the vehicle structure is connected to a vehicle body side member made of an iron-based material. The vehicle structure includes a mounting flange coupled to the vehicle body side member via a coupling member, and a bobbin-shaped member made of an iron-based material having an insertion hole for the coupling member, and the bobbin Since the body portion of the bobbin-shaped member is cast in the mounting flange in a state where the end surface of the cylindrical member protrudes outward from the end surface of the mounting flange, the vehicle body side member made of the iron-based material and the aluminum alloy Both members can be firmly connected by the connecting member while preventing direct contact with the mounting flange of the vehicle structure made of a cast material. There is an advantage that the cast material and the iron-based material and electrolytic corrosion due to a current flows through the contact portion of the dissimilar metals consisting occurs can be effectively prevented.

  In the invention according to claim 2, the vehicle body side member is disposed between the side frame extending in the front-rear direction of the vehicle and the bumper reinforcement extending in the vehicle width direction. Since the mounting flange is configured to be connected to the side frame via a connecting bolt, the side frame made of iron-based material and the mounting flange of the shock absorbing member made of aluminum alloy casting material are prevented from coming into direct contact with each other. Both members can be firmly connected by the connecting bolt and effectively prevent the occurrence of electrolytic corrosion due to current flowing in the contact portion of the dissimilar metal composed of the side frame and the shock absorbing member. There is an advantage that you can.

  In the invention which concerns on Claim 3, since the electrodeposition coating film was formed in the end surface of the said mounting flange and the wall surface of the vehicle body side member facing this, respectively, the end surface of the said mounting flange and the vehicle body side member which opposes this Even when rainwater or the like enters between the wall surface, by preventing current from flowing between the mounting flange made of an aluminum alloy casting and the vehicle body side member made of an iron-based material using the rainwater or the like as a medium, There is an advantage that generation of the electric corrosion can be effectively suppressed.

  In the invention according to claim 4, since the plurality of recesses are formed on the back surface of the mounting flange, the side frame of the shock absorbing member can be set by increasing the plate thickness without increasing the weight of the mounting flange so much. There is an advantage that a sufficient mounting strength can be secured and the mounting state can be stably maintained.

  In the invention according to claim 5, the end face of the mounting flange is opposed to the end face of the mounting flange in the electrodeposition coating process by utilizing a gap formed between the end face of the mounting flange and the wall surface of the vehicle body side member facing the mounting flange. Since an electrodeposition coating can be formed on the wall surface of the vehicle body side member, before connecting the mounting flange of the vehicle structure to the vehicle body side member, both are electrodeposited in separate steps. Or after being immersed in an electrodeposition coating solution and temporarily electrodeposited so that a gap is formed between the vehicle body side member and the mounting flange of the vehicle structure. The electrodeposition coating film is applied to the end surface of the mounting flange and the wall surface of the vehicle body side member without requiring complicated operations such as final connection between the vehicle body side member and the mounting flange of the vehicle structure. Easy and proper shape There is an advantage that it can be.

It is side surface sectional drawing which shows 1st Embodiment of the vehicle body structure which concerns on this invention. It is a top view which shows the principal part of the said vehicle body structure. It is the III-III sectional view taken on the line of FIG. It is a perspective view which shows the specific structure of an impact-absorbing member. It is an end view which shows the specific structure of an impact-absorbing member. It is the VI-VI sectional view taken on the line of FIG. It is plane sectional drawing which shows the manufacturing process of an impact-absorbing member. It is a perspective view which shows the comparative example of an impact-absorbing member. It is a perspective view which shows the 1st modification of an impact-absorbing member. It is a perspective view which shows the 2nd modification of an impact-absorbing member. It is a graph which shows the correspondence of the deformation amount of an impact-absorbing member, and a load. It is a table | surface which shows the maximum displacement amount and plastic deformation amount of an impact-absorbing member. It is a plane sectional view showing a 2nd embodiment of a vehicle body structure concerning the present invention.

  1 and 2 show a first embodiment of a vehicle body structure according to the present invention. The vehicle body includes a vehicle body side member including a pair of left and right rear side frames 1 extending in the longitudinal direction of the vehicle body on both left and right sides of the rear vehicle body, and rear end portions of the rear side frames 1 on the rear side of the rear side frame 1. A bumper reinforcement 2 extending in the vehicle width direction is provided so as to be connected, and a pair of left and right shock absorbing members 3 are disposed between the rear side frame 1 and the bumper reinforcement 2.

  The rear side frame 1 is formed of a member having a rectangular cross section made of a ferrous material such as a steel plate material having a pair of upper and lower horizontal walls 4 and 5 and a pair of left and right side walls 6 and 7, or a hat-shaped member. The rear end flange 8 is fixed to the rear end portion by means such as spot welding. The shock absorbing member 3 is detachably attached to the rear end flange 8 of the rear side frame 1 by bolting.

  The bumper reinforcement 2 is made of a metal material such as a steel plate having a front wall portion 10 and a rear wall portion 11 opposed to each other in the front-rear direction, and an upper wall portion 12 and a bottom wall portion 13 opposed to each other in the vertical direction. It consists of a square pipe-shaped member or a cross-sectional hat-shaped member. A pair of left and right hook mounting members 17 formed of a cylindrical body in which a screw hole into which a base end portion of the pulling hook 16 is screwed are welded to the upper wall portion 12 of the bumper reinforcement 2. It is fixed by. The shock absorbing member 3 is fixed to the front wall portion 10 of the bumper reinforcement 2 by means such as bolting.

  The impact absorbing member 3 is made of an aluminum alloy casting material, and as shown in FIGS. 3 to 5, the mounting flange 19 connected to the rear end flange 8 of the rear side frame 1 via a connecting bolt 18, and the bumper. The tip wall 21 is connected to the reinforcement 2 via a connecting bolt 20. A hollow portion 26 having an upper wall 22 and a lower wall 23 facing each other in the vertical direction and a pair of left and right side walls 24 and 25 is disposed between the front end wall 21 of the shock absorbing member 3 and the mounting flange 19. Has been. Then, when a rear-end collision such as a collision of another vehicle with the rear portion of the vehicle occurs, the hollow portion 26 of the shock absorbing member 3 is configured to absorb impact energy by plastic deformation or the like. ing.

  The mounting flange 19 is made of a plate-like body having a plate thickness Ft of about 7 mm to 15 mm extending so as to surround the outer periphery of the hollow portion 26, and insertion portions 27 for the connection bolts 18 are provided at the four corners. ing. A plurality of recesses 28 are formed on the back surface of the mounting flange 19, that is, on the joint surface to the rear end flange 8 of the rear side frame 1. In this embodiment, a pair of recesses 28 and 28 are formed between the insertion portions 27 and 27 provided at the four corners of the mounting flange 19, respectively, and the depth of the recess 28 depends on the plate thickness Ft of the mounting flange 19. Is set to about 1/2 to 3/4. Thereby, between the insertion parts 27 and 27 which the mounting flange 19 opposes, the peripheral part and the center part are formed thick, and other parts (installation part of the said recessed part 28) are formed thinly. Has been.

  Further, a thick portion 29 having a plate thickness larger than that of the distal end portion is provided at the proximal end portions of the side walls 24 and 25. In the present embodiment, a thick portion 29 is formed at the base end side portion of the side walls 24 and 25, which is a bulging portion that bulges laterally in a plan view and extends in a vertical direction in a side view. The protruding amount T to the side of the thick portion 29 is set to be approximately the same as the plate thickness t (for example, 3 mm) of the side walls 24 and 25. Further, the front-rear width W of the thick portion 29 is set to about 1/3 to 1/5 of the front-rear length L of the side walls 24, 25.

  The upper wall 22 and the lower wall 23 of the shock absorbing member 3 are provided with a plurality of ribs 30 extending from the end face of the mounting flange 19 toward the distal end side. In the present embodiment, three ribs 30 project from the upper surface of the upper wall 22 and the lower surface of the lower wall 23, respectively. The rib 30 has a front-rear dimension of about 20 mm, a vertical dimension of about 10 mm, and a plate thickness of about 3 mm, and is formed in a tapered triangular shape in side view.

  As shown in FIG. 6, a bobbin-like member 31 made of an iron-based material having an insertion hole for the connecting bolt 18 is disposed in the insertion portion 27 provided in the mounting flange 19 of the shock absorbing member 3. . The bobbin-shaped member 31 has a cylindrical main body portion 32 and donut plate-like flange portions 33 and 34 provided at both front and rear ends thereof. Then, in the state where the end surface of the bobbin-shaped member 31, specifically, the outer wall surface of the flange portions 33 and 34 protrudes outward by about 1 to 3 mm from the end surface of the mounting flange 19, the mounting flange 19. The cylindrical main body portion 32 of the bobbin-shaped member 31 is cast inside.

  Further, as shown in FIGS. 3 and 4, a connecting portion in which an insertion hole for a connecting bolt 20 that connects the tip wall 21 and the bumper reinforcement 2 is formed in the tip wall 21 of the shock absorbing member 3. 35 are provided at the four corners, and a connecting portion 36 having a predetermined width extending in the vertical direction is provided so as to be connected to the front end portion of the upper wall 22 and the front end portion of the lower wall 23.

  In order to manufacture a vehicle structure comprising the shock absorbing member 3 and to connect the shock absorbing member 3 to a vehicle body side member comprising the rear side frame 1, a vehicle body is first constructed as shown in FIG. By closing a casting mold 44 having a fixed mold 42 in which a support pin 41 of the member 31 is protruded and a movable mold 43 installed so as to be able to contact with and separate from the fixed mold 42, the mold is closed. With the end surface of the bobbin-shaped member 31 projecting outward from the flange forming space 45, a shock absorbing member forming cavity having the flange forming space 45 is formed.

  After forming a cavity for forming an impact absorbing member between the fixed mold 42 and the movable mold 43 in the mold closing process, a die casting method in which a molten aluminum alloy is injected into the cavity at a high pressure in the casting process. The impact absorbing member 3 is cast. In place of the die casting method, the impact absorbing member 3 can be cast by a gravity casting method in which a molten aluminum alloy is poured into the cavity of the casting mold 44 by its own weight. From the viewpoint of forming the impact absorbing member 3 appropriately and ensuring its strength sufficiently, it is desirable to use the die casting method.

  After the shock absorbing member 3 manufactured in the casting process is taken out from the casting mold 44 and deburred, etc., the mounting flange 19 of the shock absorbing member 3 is connected to the rear end of the rear side frame 1 in the connecting process. They are fixed to the flange 8 by connecting bolts 18 to connect them. Next, the vehicle body structure having the shock absorbing member 3 and the rear side frame 1 is conveyed to an electrodeposition coating process, and is applied with electrodeposition coating in which a voltage is applied while being immersed in the electrodeposition coating liquid, and is shown in FIG. As described above, the electrodeposition coating liquid is allowed to enter between the end surface of the mounting flange 19 and the wall surface of the vehicle body side member facing the mounting flange 19, that is, the rear surface of the rear end flange 8, and the electrodeposition coating 46 is formed on each surface. To do.

  That is, the mounting flange 19 of the shock absorbing member 3 is cast with the end surface of the bobbin-shaped member 31 protruding outward from the end surface of the mounting flange 19. Even when the rear side frame 1 is firmly connected to the rear end flange 8 of the rear side frame 1, the bobbin-shaped member 31 is disposed between the end surface of the mounting flange 19 and the rear surface of the rear end flange 8 opposed thereto. A gap corresponding to the protrusion amount is formed. Therefore, the electrodeposition coating liquid can surely enter the gap formed between the mounting flange 19 of the shock absorbing member 3 and the rear end flange 8 of the rear side frame 1 in the electrodeposition coating process. Thus, the electrodeposition coating 46 can be easily and properly formed on the end surface of the mounting flange 19 and the rear surface of the rear end flange 8 facing the mounting flange 19, respectively, and the gap can be reliably sealed. It is also possible to prevent electrolytic corrosion due to the end surface coming into contact with the rear end flange 8 of the rear side frame 1 through moisture.

  In addition, since a plurality of recesses 28 are provided on the back surface of the mounting flange 19, the plate thickness Ft can be increased without increasing the weight of the mounting flange 19 so much. Therefore, even if the plate thickness Ft of the mounting flange 19 is set to a relatively large value, for example, about 10 mm, the depth of the concave portion 28 is set to, for example, 1/2 or more of the plate thickness Ft of the mounting flange 19. In addition, it is possible to sufficiently secure the mounting strength of the shock absorbing member 3 to the rear side frame 1 while suppressing the weight of the shock absorbing member 3 from increasing, and to stabilize the mounting state of the shock absorbing member 3. Can be maintained.

  In the vehicle body structure in which the vehicle structure (impact absorbing member 3) made of an aluminum alloy casting is connected to the vehicle body side member (rear side frame 1) made of an iron-based material as described above, it is connected to the shock absorbing member 3. A mounting flange 19 connected to the vehicle body side member via a member (connection bolt 18) and a bobbin-like member 31 made of an iron-based material having an insertion hole for the connection member are provided. Since the cylindrical main body 32 of the bobbin-shaped member 31 is cast in the mounting flange 19 with the end surface protruding outward from the end surface of the mounting flange 19, the vehicle is used to reduce the weight of the vehicle body. Even when the structural body is formed of an aluminum alloy casting material, there is an advantage that it is possible to effectively prevent electric corrosion from occurring in the vehicle body structure with a simple structure.

  That is, in the first embodiment, the rear side frame 1 made of an iron-based material such as a steel plate material extending in the longitudinal direction of the vehicle, and the bumper reinforcement 2 made of a metal-based material such as a steel plate material extending in the vehicle width direction. The shock absorbing member 3 disposed between them is formed of an aluminum alloy casting material, and an insertion hole for a connecting bolt 18 connected to the rear end flange 8 of the rear side frame 1 is formed in the mounting flange 19 of the shock absorbing member 3. A bobbin-shaped member 31 made of an iron-based material is provided on the mounting flange 19, and the end surface of the bobbin-shaped member 31 protrudes outward from the end surface of the mounting flange 19. Since the cylindrical main body 32 of the member 31 is configured to be cast, as shown in FIG. 6, the rear end flank of the rear side frame 1 made of the iron-based material is used. 8 and the mounting flange 19 is a direct impact absorbing member 3 made of an aluminum alloy casting material, while preventing the contact, both members can be firmly connected by the connecting bolt 18. Therefore, it is possible to effectively prevent the occurrence of electrolytic corrosion due to current flowing in the contact portion of the dissimilar metal in contact with the impact absorbing member 3 made of the aluminum alloy casting material and the rear side frame 1 made of the iron-based material. can do.

  Further, as shown in the first embodiment, in the mold closing process of closing the fixed mold 42 and the movable mold 43 constituting the casting mold 44, the mold is formed between the fixed mold 42 and the movable mold 43. The bobbin-shaped member 31 made of an iron-based material having the insertion hole for the connecting bolt 18 is disposed in the flange forming space 45, and the end surface thereof protrudes outward from the flange forming space 45. After mounting, the mounting flange 19 of the shock absorbing member 3 cast by injecting molten aluminum alloy into the cavity of the casting mold 44 in the casting process is connected to the rear end flange 8 of the rear side frame 1 by a connecting bolt. FIG. 6 shows a case in which these are transported to the electrodeposition coating process in a state where they are firmly connected to each other and applied to the electrodeposition by applying a voltage while immersed in the electrodeposition coating liquid. As shown The electrodeposition coating fluid between the rear face of the rear end flange 8 the end face of the mounting flange 19 and opposed thereto may be advanced. For this reason, the electrodeposition coating 46 is easily and properly formed on the end surface of the mounting flange 19 and the rear surface of the rear end flange 8 facing the mounting flange 19, and the electrodeposition coating 46 securely seals between the two. Therefore, there is an advantage that the occurrence of the electrolytic corrosion can be effectively prevented.

  That is, the electrodeposition coating liquid 46 can be formed by using the gap formed between the end face of the mounting flange 19 and the rear face of the rear end flange 8 opposite to the end face to form the electrodeposition coating 46. Therefore, before connecting the shock absorbing member 3 to the rear side frame 1, both are separately electrodeposited, or both are formed so that a gap is formed between the rear side frame 1 and the shock absorbing member 3. In the temporarily fixed state, after the electrodeposition coating is performed by dipping in the electrodeposition coating liquid, the above-mentioned mounting is performed without requiring complicated work such as firmly connecting the rear side frame 1 and the shock absorbing member 3. The electrodeposition coating 46 can be easily and properly formed on the end surface of the flange 19 and the rear surface of the rear end flange 8. Even when rainwater or the like enters between the end face of the mounting flange 19 and the rear face of the rear end flange 8 opposed thereto by forming the electrodeposition coating 46, an aluminum alloy is used with the rainwater or the like as a medium. The advantage that current can be prevented from flowing between the mounting flange 19 of the shock absorbing member 3 made of a casting and the rear end flange 8 of the rear side frame 1 made of an iron-based material, thereby effectively suppressing the occurrence of the electrolytic corrosion. There is.

  Furthermore, in the above embodiment, since the plurality of recesses 28 are provided on the back surface of the mounting flange 19 of the shock absorbing member 3 connected to the rear end flange 8 of the rear side frame 1, the above shock absorbing made of an aluminum alloy casting material is used. In addition to being able to effectively suppress plastic deformation during transportation of the member 3 and the like, there is an advantage that the impact energy can be effectively absorbed by sufficiently exerting the function of the shock absorbing member 3 in the event of a vehicle collision. is there.

  That is, by providing a plurality of recesses 28 on the rear surface of the mounting flange 19 and increasing its thickness Ft without increasing the weight of the mounting flange 19 so much, the shock absorbing member 3 can be mounted on the rear side frame 1. Since the mounting strength can be sufficiently secured, even when the shock absorbing member 3 is made of an aluminum alloy casting material for the purpose of reducing the weight of the vehicle body and providing sufficient ductility, the mounting state can be maintained. It can be maintained stably. Therefore, when the automobile having the impact absorbing member 3 is loaded and the automobile is transported in a state where the rope connected to the tow hook 16 attached to the bumper reinforcement 2 is fixed to the floor of the hull. In the shock absorbing member 3, it is possible to effectively prevent a large plastic deformation from occurring in the installation portion of the mounting flange 19, which is a portion where the maximum moment load acts.

  When a high load corresponding to the weight of the vehicle is input from the tow hook 16 and the bumper reinforcement 2 to the shock absorbing member 3 in accordance with the shaking of the hull or the like during transportation of the automobile as described above. In addition, it is possible to effectively prevent a large plastic deformation from occurring in the impact absorbing member 3 made of an aluminum alloy casting disposed between the rear side frame 1 and the bumper reinforcement 2. For this reason, the occurrence of a situation where the shock absorbing function of the shock absorbing member 3 is not sufficiently exhibited is effectively suppressed, and when a rear-end collision occurs in which another vehicle collides with the rear portion of the own vehicle, etc. By plastically deforming the hollow portion 26 of the shock absorbing member 3 in a bellows shape, it is possible to effectively absorb the impact energy acting on the rear portion of the vehicle body and reliably suppress the influence of the impact portion to the vehicle interior. There are advantages.

  As a casting material for the impact absorbing member 3, Mn: 1.4 to 1.6, Fe: 0.4 to 0.7, Mg: 0.2 to 0.5, Ti: 0.00. Al-1.5Mn containing ~ 0.2, Si: <0.10, Zn: <0.10, Cu: <0.05, N: <0.05 (wt%), the balance being Al -0.7 Fe die-cast material, 180MPa tensile strength (TS), 90MPa proof stress (YS), and 25% total elongation characteristics (EL) are used. As shown in FIG. 9, the shock absorbing member 3 ′ according to the comparative example in which the plate thickness Ft of the mounting flange 19 is set to 5 mm, and the plate thickness Ft of the mounting flange 19 to 10 mm as shown in FIG. The first modification of the present invention, which is different from the comparative example described above, that is, the first modification of the first embodiment only in that a recess 28... Having a depth of 7.5 mm is formed on the back surface. The shock absorbing member 3a according to the example was cast. And the simulation test which measures the deformation amount by applying a predetermined load to these was performed.

  Specifically, the upper surface of the bumper reinforcement 2 with the impact absorbing members 3 ′ and 3 a according to the comparative example and the first modification disposed between the rear side frame 1 and the bumper reinforcement 2. The pulling hooks 16 attached to the left and right are pulled obliquely outward and rearward at an inclination angle α of about 20 ° in plan view (see FIG. 2), and are pulled obliquely outward and downward at an inclination angle β of about 45 ° in side view. A tensile load was applied (see FIG. 1). Then, as shown in FIG. 11, the tensile load is gradually increased to 7.65 kN to measure the maximum displacement amount of the impact absorbing members 3 ′ and 3a, and after the tensile load is removed, the impact absorbing member 3 is removed. When the amount of plastic deformation generated in 'and 3a was measured, data as shown in FIG. 12 was obtained.

  From the above data, in the shock absorbing member 3 ′ according to the comparative example, a plastic deformation amount of 8.4 mm was generated. On the other hand, in the shock absorbing member 3a according to the first modification of the first embodiment of the present invention, it was confirmed that the amount of plastic deformation can be suppressed to 3.6 mm, which is half or less. Accordingly, for example, the plate thickness Ft of the mounting flange 19 is set to 10 mm so that it is at least twice the thickness of the hollow portion 26 (for example, 3 mm), and a plurality of recesses 28 are provided on the back surface. Thus, without significantly increasing the weight of the shock absorbing member 3a, the shock absorbing member 3a made of an aluminum alloy casting material is effectively suppressed from plastic deformation during transportation or the like, and the shock absorbing member is absorbed during a vehicle collision. It can be seen that the collision energy can be effectively absorbed by fully exerting the function of the member 3a.

  Further, as shown in FIG. 10, a thick portion 29 having a front-rear width W of about 20 mm and a protruding amount T of about 3 mm is provided on the base end side portion of the side walls 24, 25 constituting the hollow portion 26. The impact absorbing member 3b according to the second modified example of the first embodiment of the present invention, which is configured in the same manner as the first modified example except for the above, is cast, and the same load as above is applied. When a simulation test for measuring the amount of deformation was performed, data as shown in FIG. 12 was obtained. From the data, the impact made of an aluminum alloy casting material is obtained by providing a structure in which a thick portion 29 having a plate thickness larger than that of the distal end portion is provided in the proximal end portion of the side walls 24 and 25. It was confirmed that the impact energy can be effectively absorbed by sufficiently exerting the function of the shock absorbing member 3 at the time of a vehicle collision while suppressing the plastic deformation during the transportation of the absorbing member 3b more effectively.

  In particular, as shown in the second modification of the present invention, the thick portion 29, which is a bulging portion that extends in the vertical direction in a side view and bulges in a lateral direction in a plan view, is provided at the base ends of the side walls 24, 25. In the case where the structure is provided on the side portion, without increasing the weight of the shock absorbing member 3b so much, the base end portion of the shock absorbing member 3 where the maximum moment load is generated when the vehicle is transported, that is, the above-described portion. It is possible to effectively suppress the occurrence of large plastic deformation in the mounting flange 19. For this reason, the impact absorbing member 3b is formed of an aluminum alloy casting material to effectively reduce the weight and suppress the deformation at the time of transportation and the like even though the structure can be easily manufactured. There is an advantage that the effect that the function can be sufficiently maintained can be remarkably obtained.

  Further, as shown in FIG. 4, the upper wall 22 and the lower wall 23 constituting the hollow portion 26 of the shock absorbing member 3 have a front and rear dimension of about 20 mm, a vertical dimension of about 10 mm, and a thickness of about 3 mm. Except that the three ribs 30 formed in a tapered triangular shape are installed so as to extend from the end face of the mounting flange 19 toward the tip end side. A simulation test was performed in which the shock absorbing member 3 according to the first embodiment of the present invention configured as described above was cast, and a deformation test was performed by applying the same load as described above. As shown in FIG. was gotten.

  From the above data, by providing ribs 30 extending from the mounting flange 19 toward the tip side on the upper wall 22 and the lower wall 23 of the shock absorbing member 3, plastic deformation of the shock absorbing member 3 made of an aluminum alloy casting material is provided. It is possible to effectively reinforce the connecting portion between the hollow portion 26 and the mounting flange 19, which is a region where the shock absorbing member 3 is likely to occur, and further effectively suppress the plastic deformation of the shock absorbing member 3 during transportation. It has been confirmed that the function of the shock absorbing member 3 can be sufficiently exerted in the event of a vehicle collision. In particular, as shown in the first embodiment, when the rib 30 is formed in a tapered shape in a side view, the connecting portion between the hollow portion 26 and the mounting flange 19 can be formed with a simple and lightweight configuration. By effectively reinforcing the above, there is an advantage that the deformation can be sufficiently suppressed.

  As shown in FIG. 6, the end surfaces of the donut plate-shaped flange portions 33 and 34 provided at the front and rear ends of the cylindrical main body portion 32 constituting the bobbin-shaped member 31 are made to be more than the end surface of the mounting flange 19. Instead of the above-described embodiment in which the cylindrical main body 32 of the bobbin-shaped member 31 is cast in the mounting flange 19 in a state of projecting outward, the end face of the cylindrical member without a flange is mounted on the mounting It is also possible to cast the mounting flange 19 and the cylindrical member integrally with the flange 19 protruding outward from the end face of the flange 19.

  However, as shown in the first embodiment, the cylindrical main body 32 of the bobbin-shaped member 31 provided with the donut plate-like flanges 33 and 34 at both front and rear ends is used. When the cylindrical main body 32 is cast in the mounting flange 19 with the end surface protruding outward from the end surface of the mounting flange 19, the movement restricting function of the flange portions 33 and 34 is used. The bobbin-shaped member 31 can be stably held in the mounting flange 19. For this reason, when connecting the mounting flange 19 of the shock absorbing member 3 to the rear end flange 8 of the rear side frame 1 by the connecting member composed of the connecting bolt 18, the connection strength can be effectively secured with a simple configuration. There are advantages.

  Further, as in the second embodiment shown in FIG. 13, a bobbin-like member 51 made of an iron-based material is attached to the connecting portion 35 a of the tip wall 21 connected to the bumper reinforcement 2 via the connecting bolt 20. The outer wall surface of the flange 52 positioned at least on the bumper reinforcement 2 side (rear side) of the donut plate-shaped flanges 52 and 53 provided at both front and rear ends of the bobbin-like member 51 The cylindrical main body 54 of the bobbin-shaped member 51 may be cast in the mounting flange 19 in a state of protruding outward from the end face of the tip wall 21. Then, by screwing the screw shaft of the connecting bolt 20 into the screw hole formed in the cylindrical main body portion 54 of the bobbin-like member 51, the tip wall 21 of the shock absorbing member 3 is attached to the bumper reinforcement 2. When configured to be connected to the front wall portion 10, the front wall portion 10 of the bumper reinforcement 2 made of an iron-based material such as a steel plate material and the tip wall of the shock absorbing member 3 made of an aluminum alloy casting material 1 Both members can be firmly connected by the connecting bolt 20 while preventing direct contact with each other. Therefore, it is possible to effectively prevent galvanic corrosion caused by current flowing through the contact portion of the dissimilar metal.

  Further, in a state where the front wall portion 10 of the bumper reinforcement 2 and the tip wall 21 of the shock absorbing member 3 are firmly connected by the connecting bolt 20, they are conveyed to the electrodeposition coating process, The electrodeposition coating solution is made to enter between the end surface of the tip wall 21 and the front wall surface of the bumper reinforcement 2 facing the end surface of the tip wall 21 by applying a voltage while being immersed in the electrode. In addition, the electrodeposition coating 55 can be formed easily and appropriately. Therefore, even when rainwater or the like enters between the end surface of the tip wall 21 and the front surface of the bumper reinforcement 2 facing the tip wall, the tip wall of the shock absorbing member 3 made of an aluminum alloy casting using the rainwater or the like as a medium. 21 and the front wall portion 10 of the bumper reinforcement 2 made of iron-based material can be reliably sealed with the electrodeposition coating 46 so that no current flows between them. Therefore, there is an advantage that the occurrence of the electrolytic corrosion can be effectively prevented.

  In the above embodiment, the shock absorbing member 3 is connected to the rear end flange 8 of the rear side frame 1 on the vehicle body side member composed of a pair of left and right rear side frames 1 extending in the longitudinal direction of the vehicle body on both left and right sides of the rear vehicle body. Although the example in which the present invention is applied to the vehicle body structure connected via 18 has been described, the vehicle body structure is disposed between the front side frame disposed at the front of the vehicle body and the pan reinforcement at the front side thereof. The present invention can also be applied to a vehicle body structure in which an impact absorbing member to be connected is connected, or other vehicle body structure in which a vehicle structure made of an aluminum alloy casting is connected to a vehicle body side member made of an iron-based material. It is.

1 Rear side frame (vehicle body side member)
3 Shock absorbing member (vehicle structure)
DESCRIPTION OF SYMBOLS 18 Connecting member 19 Mounting flange 28 Recessed part 31 Bobbin-shaped member 42 Fixed mold 43 Movable mold 44 Casting mold 45 Electrodeposition coating 46 Flange molding space

Claims (5)

  A vehicle body structure in which a vehicle structure made of an aluminum alloy casting material is connected to a vehicle body side member made of an iron-based material, and is connected to the vehicle body side member through a connection member. A mounting flange and a bobbin-shaped member made of an iron-based material having an insertion hole for the connecting member are provided, and the mounting flange is in a state in which the end surface of the bobbin-shaped member protrudes outward from the end surface of the mounting flange. A vehicle body structure characterized in that a body portion of a bobbin-like member is cast in.   The vehicle structure is an impact absorbing member disposed between a vehicle body side member comprising a side frame extending in the longitudinal direction of the vehicle and a bumper reinforcement extending in the vehicle width direction, and the mounting of the impact absorbing member The vehicle body structure according to claim 1, wherein the flange is connected to the side frame via a connecting bolt.   The vehicle body structure according to claim 1 or 2, wherein an electrodeposition coating film is formed on each of the end surface of the mounting flange and the wall surface of the vehicle body side member facing the mounting flange.   The vehicle body structure according to any one of claims 1 to 3, wherein a plurality of recesses are formed on a back surface of the mounting flange.   A vehicle body structure manufacturing method in which a mounting flange of a vehicle structure made of an aluminum alloy casting material is connected to a vehicle body side member made of an iron-based material by a connecting member, the movable mold constituting the vehicle structure mold, A bobbin-shaped member made of an iron-based material having an insertion hole for the connecting member is disposed in the flange forming space formed between the fixed mold and its end surface projects outwardly from the flange forming space. A mold closing process for closing the movable mold and the fixed mold in a state of being cast, and a casting process for casting the vehicle structure by injecting a molten aluminum alloy into the cavity in the vehicle structure mold A connecting step of connecting a mounting flange of the vehicle structure cast in the casting step to the vehicle body side member by a connecting member, and electrodeposition coating between an end surface of the mounting flange and a wall surface of the vehicle body side member facing the mounting flange Advance liquid Manufacturing method of the vehicle structure, characterized in that a electrodeposition coating step of forming an electrodeposition coating film on each side by.

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