KR20220073284A - Method of manufacturing a torsion beam for a vehicle suspension and torsion beam for a vehicle suspension - Google Patents

Abstract

The present invention relates to a method for manufacturing a torsion beam for a vehicle suspension capable of simultaneously achieving weight reduction while reinforcing the strength of a torsion beam weak region, and a torsion beam of a vehicle suspension, comprising a first coil wound with a first steel plate having a first thickness. A coil preparation step of arranging a second coil wound on both sides of a second steel plate having a second thickness thicker than the first thickness, and uncoiling the first coil and the second coil on both sides of the first steel plate A welding step of forming a welded steel plate by welding a boundary portion between the first steel plate and the second steel plate in a longitudinal direction after disposing the second steel plate, and a cutting step of cutting the welded steel plate to a predetermined length And, by roll forming the cut welded steel sheet, a first part having a circular closed cross-section of the first thickness and formed on both sides of the first part to have a circular closed cross-section of the second thickness A pipe making step of forming a pipe making pipe formed of a second part, and hydroforming the pipe pipe pipe, so that the second part of the pipe pipe can be formed with a larger diameter than the first part. It may include a pipe expansion step of expanding the second part and a beam forming step of forming a torsion beam having a closed cross-section of a “V” or “U” shape by press-molding at least a portion of the pipe making pipe.

Description

TECHNICAL FIELD The present invention relates to a method of manufacturing a torsion beam for a vehicle suspension and a torsion beam for a vehicle suspension.

The present invention relates to a method for manufacturing a torsion beam of a vehicle suspension and to a torsion beam for a vehicle suspension, and more particularly, to a method for manufacturing a torsion beam of a vehicle suspension capable of simultaneously achieving weight reduction while reinforcing the strength of a weak region of the torsion beam, and for vehicle It relates to the torsion beam of the suspension.

The suspension of a passenger car is an essential part of vehicle operation that connects the body, powertrain, driving parts and wheels. Such a suspension is divided into a front wheel and a rear wheel. The rear suspension has fewer parts compared to the multi-link type and has a simple structure, so the torsion beam axle (CTBA), which is advantageous in manufacturing cost, is mainly used for small and semi-medium vehicles. has been widely adopted.

In general, the configuration of the torsion beam axle is composed of a trailing arm that can be connected to a wheel and a vehicle body, and a torsion beam that crosses by connecting the center of the left/right trailing arm. Such a torsion beam is an important part that controls the attitude of the wheel through the torsion action of the movement of the wheel that occurs during vehicle driving. It can be classified into two types of beam types. While the combination of V-beam and torsion bar has excellent torsional resistance, due to the increase in weight of parts, it is recently trending to be specified for reasons such as vehicle weight reduction, and tubular beam that can maximize vehicle weight reduction. type is mainly used.

However, this conventional torsion beam of the tubular beam type is advantageous for vehicle weight reduction, but has a low torsional resistance in its structure. There was a problem that occurred easily. In addition, if the material strength and thickness of the torsion beam are reinforced in order to solve these problems and secure a durable life, there is a problem in that the weight of the vehicle cannot be reduced due to an increase in the weight of the parts.

The present invention is to solve various problems including the above problems, and to provide a method of manufacturing a torsion beam for a vehicle suspension capable of simultaneously achieving weight reduction while reinforcing the strength of a torsion beam weak region, and a torsion beam of a vehicle suspension aim to However, these problems are exemplary, and the scope of the present invention is not limited thereto.

According to one embodiment of the present invention, there is provided a method for manufacturing a torsion beam of a suspension for a vehicle. In the method for manufacturing a torsion beam of a vehicle suspension, a coil in which a second coil having a second thickness thicker than the first thickness is wound on both sides of a first coil wound around a first steel sheet having a first thickness preparatory stage; After uncoiling the first coil and the second coil so that the second steel plate is disposed on both sides of the first steel plate, the boundary portion between the first steel plate and the second steel plate is welded along the longitudinal direction. A welding step of forming a welded steel sheet; a cutting step of cutting the welded steel sheet to a predetermined length; By roll forming the cut welded steel sheet, a first portion having a circular closed cross-section of the first thickness and a second portion formed on both sides of the first portion and having a circular closed cross-section of the second thickness A pipe making step of forming a pipe making pipe that is formed in parts; An expansion step of expanding the second part by processing the pipe pipe by hydroforming, so that the second part of the pipe pipe has a larger diameter than the first part; and a beam forming step of forming a torsion beam having a closed cross-section of a “V” or “U” shape by press-molding at least a portion of the pipe making pipe.

According to an embodiment of the present invention, in the coil preparation step, the first thickness of the first steel plate and the second thickness of the second steel plate may have a difference of 0.2 mm or more.

According to an embodiment of the present invention, in the pipe making step, the first part having the first thickness and the second part having the second thickness of the pipe making pipe are formed to have an outer diameter of a first diameter. can

According to an embodiment of the present invention, in the pipe expansion step, the second portion of the pipe making pipe is thinner to a third thickness that is thinner than the second thickness, and an outer diameter to a second diameter larger than the first diameter This can be expanded.

According to an embodiment of the present invention, the second diameter may be formed to be 10 mm or more larger than the first diameter.

According to an embodiment of the present invention, in the expansion step, the third thickness of the second part of the expanded pipe making pipe is the same as or thicker than the first thickness of the first part, and the first thickness before expansion It may be thinner than the second thickness of the second part.

According to an embodiment of the present invention, in the beam forming step, the cross-sectional area of the closed cross-section of the second part of the torsion beam may be formed to have a larger area than the cross-sectional area of the closed cross-section of the first part.

According to an embodiment of the present invention, in the welding step, the first steel sheet and the second steel sheet may be welded by a low heat input laser welding process.

According to an embodiment of the present invention, in the welding step, the welding device for welding the first steel sheet and the second steel sheet is a first laser welding machine formed perpendicular to upper surfaces of the first steel sheet and the second steel sheet. ; and a second laser welding machine inclined at a predetermined angle with respect to the upper surfaces of the first and second steel plates.

According to an embodiment of the present invention, in the welding step, the laser beam of the first laser welding machine and the laser beam of the second laser welding machine may be formed to be spaced apart from each other by a predetermined interval.

According to an embodiment of the present invention, in the welding step, the joint surface of the first steel plate and the joint surface of the second steel plate may be disposed to be spaced apart from each other by a predetermined interval.

According to another embodiment of the present invention, a torsion beam of a suspension for a vehicle is provided. The torsion beam of the vehicle suspension may include: the first portion formed to the first thickness and having a closed cross-section of a first area; and the second portion formed to have the third thickness equal to or greater than the first thickness and having a closed cross-section having a second area greater than the first area.

According to an embodiment of the present invention made as described above, a pipe making pipe is formed from a welded steel sheet manufactured by continuously laser welding steel sheets having different thicknesses, and a thick portion of the pipe pipe pipe is confirmed through hydroforming. Then, by manufacturing the torsion beam through pressure forming, the side part of the beam to which the trailing arm that generates torsional moment is attached has a closed cross-section with a large area, and the middle part with relatively little torsion moment has a small area compared to the side part. A torsion beam having a closed cross-section can be manufactured.

Accordingly, it is possible to implement a method for manufacturing a torsion beam of a vehicle suspension and a torsion beam of a vehicle suspension that can simultaneously achieve weight reduction while improving the durability life of parts through strength reinforcement of the durable weak part of the torsion beam. Of course, the scope of the present invention is not limited by these effects.

1 is a process flowchart sequentially illustrating a method of manufacturing a torsion beam of a vehicle suspension according to an embodiment of the present invention.
2 to 9 are cross-sectional views schematically illustrating each manufacturing process of a torsion beam of a vehicle suspension according to the process flowchart of FIG. 1 .

Hereinafter, several preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Examples of the present invention are provided to more completely explain the present invention to those of ordinary skill in the art, and the following examples may be modified in various other forms, and the scope of the present invention is as follows It is not limited to an Example. Rather, these embodiments are provided so as to more fully and complete the present disclosure, and to fully convey the spirit of the present invention to those skilled in the art. In addition, in the drawings, the thickness or size of each layer is exaggerated for convenience and clarity of description.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings schematically illustrating ideal embodiments of the present invention. In the drawings, variations of the illustrated shape can be envisaged, for example depending on manufacturing technology and/or tolerances. Accordingly, embodiments of the spirit of the present invention should not be construed as limited to the specific shape of the region shown in the present specification, but should include, for example, changes in shape caused by manufacturing.

1 is a process flowchart sequentially illustrating a method for manufacturing a torsion beam of a vehicle suspension according to an embodiment of the present invention, and FIGS. 2 to 9 are a torsion beam 100 of a vehicle suspension according to the process flowchart of FIG. Cross-sectional views schematically showing each manufacturing process.

First, as shown in FIG. 1 , the method for manufacturing a torsion beam of a vehicle suspension according to an embodiment of the present invention is largely a coil preparation step (S10), a welding step (S20), and a cutting step (S30). And, it may include a pipe forming step (S40), a tube expansion step (S50), and a beam forming step (S60).

As shown in FIG. 2 , in the coil preparation step S10 , the first steel plate 10 having a first thickness t1 is wound on both sides of the first coil C1 having a thickness greater than the first thickness t1 . A second coil C2 on which a second steel plate 20 having a thickness t2 is wound may be disposed.

For example, in the coil preparation step (S10), in the coil preparation step (S10), in order to simultaneously achieve the improvement of component durability and weight reduction through the increase of the cross-sectional area of the closed section of the durable weak part of the torsion beam in the expansion step (S50) to be described later. It may be preferable that the first thickness t1 and the second thickness t2 of the second steel plate 20, which is a portion to be expanded, have a difference of at least 0.2 mm. These, the steel plates 10 and 20, an ultra-high-strength steel plate may be used, for example, may have a strength of 780Mpa.

Subsequently, as shown in FIG. 3 , in the welding step S20 , the first coil C1 and the second coil C2 are uncoiled to both sides of the first steel plate 10 to the second steel plate 20 . After this arrangement, the boundary portion between the first steel plate 10 and the second steel plate 20 may be welded along the longitudinal direction. At this time, the width W1 of the first steel plate 10 and the width W2 of the second steel plate 20 disposed on both sides of the first steel plate 10 are basically the same, but it is not necessarily limited thereto, and the torsion It can be set in various ways depending on the required strength reinforcement part of the beam or the weight reduction goal.

For example, as shown in FIGS. 4 and 5 showing partial cross-sections taken along the perforated line A-A of FIG. 3 , the first steel plate 10 and the second steel plate 20 in the welding step (S20) are ultra-high-strength steel plates It can be welded by a low heat input laser welding process that is advantageous for securing weldability. In this way, since the first steel plate 10 and the second steel plate 20 are joined by low heat input welding using a laser welding machine, the amount of heat input during welding can be minimized, thereby improving the low-temperature toughness of the welded portion and preventing cracking. can get

More specifically, as shown in Figure 4, in the welding step (S20), the welding apparatus for welding the first steel plate 10 and the second steel plate 20, the first steel plate 10 and the second steel plate ( A first laser welding machine (R1) formed perpendicular to the upper surface of 20 and a second laser welding machine (R2) formed to be inclined at a predetermined angle (a1) with respect to the upper surfaces of the first and second steel plates 10 and 20 ) may be a dual laser welding machine including.

At this time, it may be preferable that the second laser welding machine R2 is inclined at a predetermined angle a1 of 35 degrees to 45 degrees with respect to the upper surfaces of the first and second steel plates 10 and 20, more preferably. It may be most preferable to be inclined at a predetermined angle a1 of 40 degrees.

In addition, the laser beam B1 of the first laser welding machine R1 and the laser beam B2 of the second laser welding machine R2 do not overlap each other on the welding site of the first steel plate 10 and the second steel plate 20 . The distance between the two laser beams B1 and B2 may be equal to the diameter of the two laser beams B1 and B2.

For example, the diameter D of the laser beams B1 and B2 of the first laser welding machine R1 and the second laser welding machine R2 may be 0.8 mm to 1.2 mm, and the laser beam of the first laser welding machine R1 The distance d between (B1) and the laser beam B2 of the second laser welding machine R2 may be 0.8 mm to 1.2 mm. As such, as a result of repeated experiments, for effective welding of the first steel plate 10 and the second steel plate 20, the laser beams B1 and B2 of the first laser welding machine R1 and the second laser welding machine R2 are used. It was shown that the above-mentioned conditions are preferable, and more preferably, the diameter (D) of the laser beams (B1, B2) of 1.0 mm and the distance (d) of the laser beams (B1, B2) of 1.0 mm are the most appeared to be desirable.

Therefore, as shown in FIG. 4 , the first laser welding machine R1 and the second laser welding machine R2 are set under the above-described conditions, and the bonding surface 11 of the first steel sheet 10 and the second steel sheet are set. When welding is performed after arranging the joint surfaces 21 of (20) at intervals of 0.8 mm to 1.2 mm, as shown in FIG. 5, the joint surfaces 11 of the first steel plate 10 and the second The joint surfaces 21 of the two steel plates 20 may be joined with a weld bead (B) interposed therebetween. At this time, when the first steel plate 10 and the second steel plate 20 are welded, the gap G between the joint surface 11 of the first steel plate 10 and the joint surface 21 of the second steel plate 20 ) Most preferably 1.0 mm, equal to the diameter D of the silver laser beams B1 and B2.

As shown in Figure 5, in the welding step (S20), the weld bead (B) formed in the welding portion of the first steel plate 10 and the second steel plate 20, the width (W4) of 1.0mm to 2.5mm ) and may have a tow angle a2 of 135 degrees to 145 degrees with respect to the first steel plate 10 side. At this time, in order to effectively join the first steel plate 10 and the second steel plate 20, which are formed with different heights due to the thickness difference, in the welding step (S20), the weld bead (B) has a width of about 2.0 mm. It may be most desirable to be created to have a toe angle a2 of about 140 degrees.

Next, as shown in FIG. 6 , the first steel plate 10 and the second steel plate 20 formed on both sides of the first steel plate 10 are joined to obtain a welded steel plate 30 having a predetermined width W3. can be formed. This, the welded steel sheet 30 may be cut to a predetermined length (L) through the cutting step (S30). At this time, the predetermined length L at which the welded steel sheet 30 is cut may be determined in consideration of the circumference of the pipe making pipe 40 to be piped in a pipe making step ( S40 ) to be described later.

Then, as shown in Figure 7, in the pipe making step (S40), the welded steel sheet 30 cut to a predetermined length (L) by roll forming (Roll forming), the circular closed end of the first thickness (t1) A first part (S1) having a surface and formed on both sides of the first part (S1) to form a pipe making pipe (40) formed of a second part (S2) having a circular closed cross-section of a second thickness (t2) can

For example, the welded steel sheet 30 cut to a predetermined length (L) in the pipe making step (S40) is rolled up little by little through a roll forming step of going through several stages of rollers to form a round shape, and finally the abutting surface is joined by high frequency welding By doing so, the pipe making pipe 40 can be formed. At this time, in the pipe making step (S40), the first part S1 having a first thickness t1 and the second part S2 having a second thickness t2 of the pipe making pipe 40 have a first diameter ( It may be formed to have an outer diameter of D1).

Then, as shown in FIG. 8, in the pipe expansion step (S50), by hydroforming the pipe pipe 40, the second part S2 of the pipe pipe 40 is the first part S1 ) It is possible to expand the second part (S2) to form a larger diameter.

For example, by applying strong water pressure to the inside of the pipe making pipe 40 to expand the second part S2, the second part S2 of the pipe pipe 40 has a third thickness that is thinner than the second thickness t2. As the thickness decreases, the outer diameter may be expanded to a second diameter D2 larger than the first diameter D1.

In this, the expansion step (S50), the second diameter (D2) of the expanded second part (S2) is to be formed with a diameter greater than 10 mm than the first diameter (D1) of the non-expanded first part (S1). can In addition, the third thickness of the expanded second part S2 is equal to or thicker than the first thickness t1 of the non-expanded first part S1, and the second of the second part S2 before expansion It may be formed thinner than the thickness t2.

At this time, preferably, the third thickness of the expanded second part (S2) is formed to have the same thickness as the first thickness (t1) of the non-expanded first part (S1), and finally the expansion step (S50) ), the tube pipe 40 is expanded to a second diameter D2 that is 10 mm larger than the first diameter D1 of the first part S1 and the first part S1 that is not expanded, and the second part S2 ) may be most preferably formed with the same thickness.

Subsequently, as shown in FIG. 9 , at least a portion of the pipe pipe 40 in which the second part S2 is expanded is press-molded with a press device P so that at least a portion is “V”-shaped or “U” It is possible to mold the torsion beam 100 having a closed cross-section of the shape.

Accordingly, in the torsion beam 100 press-formed in the beam forming step ( S60 ), the cross-sectional area of the closed cross-section of the expanded second part ( S2 ) is larger than the cross-sectional area of the closed cross-section of the unexpanded first part ( S1 ) area can be formed.

Therefore, according to the method for manufacturing a torsion beam of a vehicle suspension according to an embodiment of the present invention, the first portion S1 and the first portion ( S1) formed on both sides of the third thickness equal to or thicker than the first thickness t1, has a closed cross-section with a second area larger than the first area, and can be connected to the wheels and body of the vehicle It is possible to manufacture the torsion beam 100 of the vehicle suspension including the second part S2 to which the trailing arm is coupled.

Therefore, according to the method for manufacturing a torsion beam of a vehicle suspension and the torsion beam of a vehicle suspension according to an embodiment of the present invention, a welded steel sheet manufactured by continuously laser welding steel sheets 10 and 20 having different thicknesses ( 30) to form a pipe 40, expand the thick part of the pipe 40 through hydroforming, and then manufacture the torsion beam 100 through press forming, a trail in which torsional moment occurs The side portion of the beam to which the ring arm is attached has a large closed cross-section, and the middle portion in which a torsion moment is relatively small may be manufactured to have a closed cross-section of a small area compared to the side portion. Accordingly, it is possible to implement a vehicle suspension that can simultaneously achieve weight reduction while improving the durability of parts through strength reinforcement of the durable weak part of the torsion beam 100 .

Although the present invention has been described with reference to the embodiments shown in the drawings, which are merely exemplary, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical protection scope of the present invention should be determined by the technical spirit of the appended claims.

10: first steel plate
20: second steel plate
30: welded steel plate
40: pipe making
100: torsion beam
C1: first coil
C2: second coil
S1: first part
S2: second part
R1: 1st laser welding machine
R2: 2nd laser welding machine

Claims (12)

a coil preparation step of arranging a second coil wound on a second steel plate having a second thickness greater than the first thickness on both sides of the first coil wound on the first steel plate having a first thickness;
After uncoiling the first coil and the second coil so that the second steel plate is disposed on both sides of the first steel plate, the boundary portion between the first steel plate and the second steel plate is welded along the longitudinal direction. A welding step of forming a welded steel sheet;
a cutting step of cutting the welded steel sheet to a predetermined length;
By roll forming the cut welded steel sheet, a first portion having a circular closed cross-section of the first thickness and a second portion formed on both sides of the first portion and having a circular closed cross-section of the second thickness A pipe making step of forming a pipe making pipe that is formed in parts;
An expansion step of expanding the second part by processing the pipe pipe by hydroforming, so that the second part of the pipe pipe has a larger diameter than the first part; and
a beam forming step of forming a torsion beam having a closed cross-section of a “V” or “U” shape by press-molding at least a portion of the pipe making pipe;
A method of manufacturing a torsion beam of a vehicle suspension comprising a. The method of claim 1,
In the coil preparation step,
The first thickness of the first steel plate and the second thickness of the second steel plate have a difference of 0.2 mm or more, a method of manufacturing a torsion beam for a vehicle suspension. The method of claim 1,
In the manufacturing step,
The method for manufacturing a torsion beam for a vehicle suspension, wherein the first portion having the first thickness and the second portion having the second thickness of the tube pipe are formed to have an outer diameter of a first diameter. 4. The method of claim 3,
In the expansion step,
The second portion of the pipe making pipe is thinner to a third thickness that is smaller than the second thickness, and the outer diameter is expanded to a second diameter larger than the first diameter, the torsion beam manufacturing method of a vehicle suspension. 5. The method of claim 4,
In the expansion step,
The second diameter is formed to be 10 mm or more larger than the first diameter, the method of manufacturing a torsion beam for a vehicle suspension. 5. The method of claim 4,
In the expansion step,
The third thickness of the second part of the expanded pipe making pipe is the same as or thicker than the first thickness of the first part, and is thinner than the second thickness of the second part before expansion of the suspension for a vehicle A method of manufacturing a torsion beam. The method of claim 1,
In the beam forming step,
A method of manufacturing a torsion beam for a vehicle suspension, wherein a cross-sectional area of a closed cross-section of the second portion of the torsion beam is formed to be larger than a cross-sectional area of a closed cross-section of the first portion. The method of claim 1,
In the welding step,
The method of manufacturing a torsion beam for a vehicle suspension, wherein the first steel plate and the second steel plate are welded by a low heat input laser welding process. 9. The method of claim 8,
In the welding step,
A welding device for welding the first steel plate and the second steel plate,
a first laser welding machine formed perpendicular to upper surfaces of the first and second steel plates; and
a second laser welding machine inclined at a predetermined angle with respect to upper surfaces of the first and second steel plates;
A method of manufacturing a torsion beam of a vehicle suspension comprising a. 10. The method of claim 9,
In the welding step,
The laser beam of the first laser welding machine and the laser beam of the second laser welding machine are formed to be spaced apart from each other by a predetermined interval. 9. The method of claim 8,
In the welding step,
The joint surface of the first steel plate and the joint surface of the second steel plate are spaced apart from each other by a predetermined interval, the method of manufacturing a torsion beam for a vehicle suspension. In the torsion beam of a vehicle suspension manufactured by the method for manufacturing a torsion beam of a vehicle suspension according to any one of claims 1 to 11,
The torsion beam is
the first portion formed to the first thickness and having a closed cross-section of a first area; and
the second portion having a closed cross-section having a second area greater than the first area and having a third thickness equal to or greater than the first thickness;
Including, a torsion beam of a vehicle suspension.

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