JPH04183635A - Lightweight door guard bar excellent in strength and stiffness - Google Patents

Abstract

PURPOSE:To improve the strength and the stiffness and secure lightweight construction, and to attempt accordingly the safety and the weight reduction of an automobile by specifying the shape of the body, and connecting a patch to the side wall of the body in the door guard bar of one inverted projection type. CONSTITUTION:The sectional shape of the body 1 of a door guard bar is formed in one projection type and type body comprises a convex part 11 in an inverted projection type and flange parts 12 on both sides of the convex part. And the patch 3 is connected to the side wall of the convex part 11. A stiffening plate 2 is suspended between the flanges 12 on both sides. The dimensions of the above-mentioned respective parts 1-3 are determined to satisfy the following formula. That is, 0.02XL1<=H; 0.5<=H/W<=3.0; H/5<=p<=H-(R1+R2); L1/7<=dL; 0.4Xt1<=t3<=2.5Xt10 where, L1: overall length of the door guard bar, H:height of the door guard bar, W:outside width at the convex part of the body, P:width of the patch, dL:length of the patch, R1: outside curvature at the rise part of the projection part of the body, R2:inside curvature of the projection part of the body, t1:thickness of the body, t3: thickness of the patch.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a door guard bar with excellent strength and rigidity.
More specifically, it has a specific shape and has a tensile strength of 8
0) This relates to a door guard bar that is lightweight and has excellent strength and rigidity by using a steel plate with a rating of "cgf/am" or higher. (Conventional technology and problems to be solved) In recent years, in the automobile industry, safety for automobiles has Due to the increasing demand for automobiles, the use of reinforcing members using high-strength steel plates to protect occupants in the event of a collision is progressing. In recent years, reinforcing beams called door guard bars as shown in Figure 3 have been installed. Conventionally, door guard bars have a tensile strength of 60 to 100.
A door guard bar of the three-way type with a cross-sectional shape as shown in FIG. 4 has been used, using a high-strength steel plate of kgf/mm2. This type of door guard bar is formed by press working into the shape of three peaks, and a contact plate is joined to the top and bottom surfaces of the bar by spot welding. However, due to fuel efficiency regulations for automobiles, there is an increasing demand for lighter automobile bodies, and there is a strong demand for lighter weight even in the three-way type door guard bar, which is a reinforcing member. Furthermore, when such a door guard bar is used in a crush test as shown in Figure 5, there is a problem in that after reaching the maximum load, the load drops suddenly and the shock absorption properties deteriorate. . In other words, such door guard bars are not only required to be lightweight and have rigidity and strength in order to protect occupants from side collisions, but also to have excellent shock absorption properties. In other words, it is required that the absorbed energy be large. In response to this requirement, door guard bars made of hardened pipes are sometimes used, but this pipe shape has a small section modulus, resulting in poor rigidity, and the shape remains the same over the entire length, making it difficult to avoid damage near the ends. has an excess of material in it. Furthermore, there is a problem that warpage is likely to occur during hardening. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and provide a door guard bar that is lightweight and has excellent strength and rigidity. (Means for Solving the Problems) In order to solve the above-mentioned problems, the present inventors have developed a door guard bar that is lightweight, has excellent rigidity and strength, and has excellent shock absorption characteristics. As a result of intensive research in order to obtain a door guard bar, we found that in a single-mounted door guard bar with the cross-sectional shape shown in Figure 1, even when nothing is connected to the main body other than the plate, the thickness, material strength, By adjusting the shape (H/W) and dimensions,
We have found that it is possible to obtain a door guard bar with the same rigidity and strength as conventional ones. However, the present inventors have found that door guard bars, which are used as reinforcing materials against side collisions of automobiles,
We found that not only the absorbed energy but also the rigidity and strength at the initial stage of deformation are important. Therefore, the inventors of the present invention have conducted further research on measures to improve the rigidity and strength at the initial stage of deformation, and have found that the most effective method is to increase the bending rigidity of the side wall of the door guard bar main body. As a result, by joining the batch to the side wall of the main body as shown in Figure 1, it is possible to minimize the increase in product weight and improve the rigidity and strength of the initial deformation. The present invention has been made based on the discovery that it is possible to obtain a door guard bar that has excellent strength and rigidity. That is, in short, the present invention has a main body having a cross-sectional shape consisting of a convex portion having an inverted convex shape and flange portions on both sides of the convex portion,
A patch is joined to the side wall of the convex part of the main body, and the dimensions of each part are the following formula 0 % (1) L1 Nidoor guard overall length H Nidoor guard height W: Outside width of the protrusion of the main body P: Patch width dL :Batch length R1:Outside curvature of the rising part of the convex part of the main body R2:Inner curvature of the convex part of the main body t□:Plate thickness t of the main body::Dimensions that satisfy the plate thickness of the patch, and as the main body The gist of this product is a single-mount type door guard bar with excellent strength and rigidity, which is characterized by using a steel plate with a tensile strength of 80 kgf/ways2 or more. The present invention will be explained in further detail below. (Function) First, in the present invention, the main body has a tensile strength of 80
A high-strength steel plate of kgf/+am2 or more is used to form a main body having the cross-sectional shape shown in the first VA by press working. The cross-sectional shape of the main body 1 is a single convex type, and is a shape consisting of an inversely convex convex portion 11 and flange portions 1□ on both sides thereof. In addition, if the tensile strength of the main body is less than 80 kgf/am,
This is not preferable because the door guard bar cannot satisfy the strength level required for protecting the occupants. At that time, it is necessary to adjust the height Hl of the door guard bar and the ratio of this height H to +1w of the main body convex portion, H/W, so that it satisfies the following equation (see FIG. 2). 0.02XL1≦H・(1) 0.5≦H/W≦3, Q・= (2
) Here, Ll is the total length of the door guard bar, and this value is regulated by the dimensions of the door to which it is attached. If the height H is smaller than the left side of equation (1), the crushing load will be low and it will not be possible to satisfy the strength required as a door guard bar. Although there is no particular upper limit for the height H, it is desirable to select the largest value within the range that allows installation inside the door. Similarly, if H/W is smaller than the left side of equation (2), the required strength cannot be satisfied, whereas if it is larger than the right side, pressing becomes difficult and crushing occurs. At times, there is a risk that the bar itself will fall sideways. Further, in the present invention, the patch is bonded to the side wall of the main body as shown in FIG. 13. At that time, it is necessary to adjust the width P and length dL of the patch so as to satisfy the following equation. H15≦PSH-(R1+R2)...(3)L
1/7≦dL...(4
)0.4Xt1≦t,≦2.5Xt□...
- (5) That is, when P is smaller than the left side of equation (3), the effect of improving the strength and rigidity of the main body cannot be obtained. On the other hand, if it is larger than the right side, it will be difficult to join the patch to the side wall of the main body, and the bottom of the main body will break when crushed, resulting in a significant drop in shock absorption. Furthermore, if dL is smaller than the left side of equation (4), the effect of improving the body rigidity will not be obtained, and buckling will occur in the region where the patch is not joined, resulting in a decrease in strength. Furthermore, if the plate thickness t3 of the patch is smaller than the left-hand side of equation (5), no improvement in strength or rigidity can be obtained; on the other hand, if it is larger than the right-hand side, the weight will increase and the bottom of the main body will be damaged when crushed. Fracture will occur, and the impact absorption properties will be significantly reduced. A flat plate is used as the backing plate, which is joined to the flange portion of the main body as shown in FIG. Thus, according to the present invention, it is possible to obtain a door guard bar that is lightweight and has excellent strength and rigidity. Note that when molding a single-mounted door guard bar according to the present invention, there is no problem even if the cross-sectional shape of the A-A cross section shown in FIG. 2(b) extends uniformly in the longitudinal direction of the bar. In order to reduce the weight, it is desirable to make the bar narrow at both ends in the longitudinal direction, as shown in FIG. 2(a). Then, the length L of the bottom (convex part) of the bar after squeezing both ends
3 is preferably L3≧0.6XL1 so as not to affect the strength of the entire bar. Similarly, regarding the length L2 of the backing plate, it is desirable that L2≧0.25XL1. Also, how to connect the main body, backing plate, and patch. Spot welding, T-work GW! There is no problem using any welding method, such as contact welding or laser welding, but when using spot welding, which is the most commonly used method in industry, the patch and main body are welded in two rows in the width direction of the patch. The weld pitch in the longitudinal direction is set to 30t or less to prevent openings between the main body and the patch when crushed, and the welding pitch between the main body and the patch plate is set to reduce strength due to openings between the main body and the patch when crushed. In order to prevent this, it is desirable to set the welding pitch to 50 m+e or less. Examples of the present invention are shown below. (Example) Table 1 shows door guard bars having various dimensions. An example of the results of a crush test conducted on these door guard bars using the test method shown in FIG. 5 is shown in FIG. 6 (load displacement curve). In Figure 6, the conventional three-mounted door guard bar (
Compared to conventional example A), comparative example B has the same strength. Comparative Examples C and E, in which a patch was welded to Comparative Example B, have better strength and rigidity than Comparative Examples A and B. However, these devices break at the bottom of the main body after reaching the maximum load, causing a sudden drop in load, and are inferior in shock absorption properties. In addition, in the comparative example, there was almost no effect of improving rigidity, and buckling occurred in the area where the patch was not welded.
There is almost no effect of improving strength. On the other hand, Examples F and G of the present invention have excellent strength and rigidity, and even after reaching the maximum load, the load decreases without causing breakage. Furthermore, regarding the product weight, the increase in weight was kept to a minimum compared to Comparative Example B, and it is clear that the example of the present invention is lightweight and has excellent strength and rigidity.

[Left below]

(Effects of the Invention) As described in detail above, according to the present invention, in a reverse convex single-mount type door guard bar, the shape of the main body is adjusted and a patch is joined to the side wall of the main body, thereby increasing the strength. - It is possible to obtain a door guard bar that is both lightweight and has excellent rigidity. Therefore, it greatly contributes to the safety and weight reduction of automobiles.

[Brief explanation of drawings]

FIG. 1 is a perspective view illustrating the shape of a single-mount type door guard bar according to the present invention, FIG. 2 is a diagram showing the shape of the end of the single-mount type door guard bar according to the present invention, and (a) is a vertical side view. Figure, (b) is (a
), FIG. 3 is an explanatory diagram showing a state in which the door guard bar is attached to an automobile door, FIG. 4 is a diagram showing a cross section of a conventional three-prong type door guard bar, and FIG. 6 is an explanatory diagram showing the procedure for crushing the door guard bar, and FIG. 6 is a diagram showing the load displacement curve after the crushing test of the door guard bar. 1...Body, 1...Body protrusion, 1□...Body flange, 2...Patch plate, 3...Patch. Patent applicant Takashi Nakamura, Patent attorney representing Kobe Steel Corporation '-La procedural amendment dated 1990, January 20, 1990 Patent Application No. 310258 2, Title of Invention, Lightweight Door Guard Bar 3 with Excellent Strength and Rigidity, Relationship with the Person Making the Amendment Case Patent Applicant Address: 1-3-18 Wakihama-cho, Chuo-ku, Kobe Name (1)
19) Kobe Steel, Ltd. 4, Agent address: 5-35 Nishi-Nippori, Arakawa-ku, Tokyo 116 7. Contents of amendments As per the engraving and attachment of the drawings originally attached to the application (no changes to the contents)

Claims (1)

[Claims] (1) A reinforcing beam (hereinafter referred to as a "door guard bar") installed inside an automobile door to protect against side collisions has a main body with a cross-sectional shape consisting of an inversely convex convex part and flanges on both sides of the convex part. A patch is bonded to the side wall of the convex portion of the main body, and the dimensions of each part satisfy the following formula: 0.02×L1≦H...(1) 0.5≦H/W≦3.0...・(2) H/5≦P≦H-(R1+R2)...(3) Li/7≦dL...(4) 0.4×t_1≦t_3≦2.5×t_1...(5 )
Here, L_1: Full length of the door guard bar H: Height of the door guard bar W: External width of the convex part of the main body P: Patch width dL: Patch length R1: Outer curvature of the rising part of the convex part of the main body R2: Outside curvature of the rising part of the convex part of the main body Inner curvature t_1: Plate thickness of main body t_3: Dimensions that satisfy the plate thickness of the patch, and strength and rigidity characterized by using a steel plate with a tensile strength of 80 kgf/mm^2 or more as the main body. A single-mount type door guard bar with excellent durability.