KR100591261B1 - method for forming torsion beam and apparatus for forming tortion beam - Google Patents

Abstract

The present invention relates to a torsion beam forming method and a torsion beam forming apparatus of a torsion beam suspension device, comprising: (a) a circular cross-section pipe having a predetermined thickness P) is placed on the upper surface of the central portion 48 of the lower mold, and fixed with the upper punch 44 located in the center of the upper mold 40, (b) the side molds 52, 52 'are lower punch 46 A lower side of the upper mold body 40 and the upper punch 44 to form the pipe P into an oval shape, and (c) both ends of the pipe P are fed to the feeding punch 56. 56 '), and injecting fluid through a hole formed in the center of the feeding punch to apply internal pressure to the pipe P, (d) lowering the upper punch 44 and at the same time the lower punch 46 Including the step of raising, wherein the upper punch 44 corresponds to the U-shape of the inner surface of the U-shaped opening ring It has a U-shaped convex portion, the upper surface of the central portion 48 of the lower mold has a concave portion corresponding to the U-shaped convex portion of the outer surface of the U-shaped opening ring, the upper side surface of the lower punch 46 is the central portion 48 And a device for forming a torsion beam having a U-shaped open ring cross section, which is connected to a recess of a shape so as to form a partial U-shaped recess to form an outer surface of the U-shaped open ring. will be. In the present invention, the shaping of the torsion beam 24 is performed by supplying a high pressure fluid to the inside of the pipe and simultaneously operating the mold, so that the high torsional rigidity, the bending rigidity and the endurance strength are not required without the torsion bar and the reinforcement that are necessarily assembled together in the torsion beam axle. In addition, the number of parts can be reduced, the weight reduction effect can be obtained, and the molding process of the torsion beam can be simplified to facilitate molding.

Description

Torsion beam forming method and torsion beam forming apparatus of torsion beam suspension device {method for forming torsion beam and apparatus for forming tortion beam}

1 is a perspective view showing a conventional torsion beam suspension device;

2 is a perspective view showing a torsion beam axle of a torsion beam suspension according to the present invention;

3 is a perspective view illustrating the torsion beam of FIG. 2;

4 is a cross-sectional view taken along the line A-A in FIG. 3;

5 is a cross-sectional view taken along the line B-B in FIG. 3;

6 is a cross-sectional view taken along the line C-C in FIG.

7 is a state diagram for shaping a torsion beam of the torsion beam suspension device according to the present invention.

<Explanation of symbols for the main parts of the drawings>

22, 22`: trailing arm 24: torsion beam

26, 26`: Joint 28, 28 ': Spindle bracket

32, 32 ': spring seat

The present invention relates to a torsion beam forming method and a torsion beam forming apparatus of a torsion beam suspension system.

Suspension of a vehicle is a device that connects the vehicle body and the wheel, and absorbs the shock or vibration received from the road surface while driving to improve the ride comfort and stability of the vehicle. These suspensions are largely divided into one-piece in which the left and right wheels are connected to the axle and the independent type in which the left and right wheels operate separately. It consists of a shock absorber and an arm or a link that controls the operation of the wheel.

The integrated and independent torsion beam suspension is a combination of left and right trailing arms in one piece called torsion beam or cross beam, which has longer link length and oscillation shaft than strut or double upper body. It has a low number of rubber bushes, low friction hysteresis in suspension stroke, high level of smooth ride, and low production cost and low price, even though the design performance range is not high due to simple components. It has been used in light and quasi-rear suspensions for decades with relatively high running stability relative to mass.

In the conventional torsion beam suspension device, as shown in FIG. 1, a pair of left and right trailing arms 2 and 2 'are connected by the torsion beam 4, and the trailing arms 2 and 2' are separated from each other. The front end pivotally supports the car body (not shown) by the joints 6 and 6` with the rubber bush, and the wheels 8 and 8` are provided at the rear end of the trailing arms 2 and 2 '. It is a combined structure. In addition, a suspension spring (10.10 ') is provided between the trailing arms (2, 2') and the vehicle body, and shock absorbers (12, 12 ') are provided at the rear end of the trailing arms (2, 2'). Is connected.

The torsion beam suspension configured as described above is characterized in that the wheels 8 and 8` are deformed due to the torsional deformation characteristics of the torsion beam 4, and the torsion beam suspension and the position of the trailing arm and the bushing characteristics are bumped. Toe-in: When looking down from the top of the wheel, the distance between the front of the two wheels is smaller than the rear distance.

In a torsion beam suspension, the trailing arm and the torsion beam are connected by welding, which is called a 'torsion beam axle'. The torsion beam axle is partially or completely twisted when the left and right wheels stroke in the opposite direction, and this torsion greatly affects the suspension system and is an important factor in determining the vehicle performance, which is actively used for the suspension function. Therefore, the torsion beam must have a high torsional rigidity against it when rolling the vehicle and a bending rigidity against the lateral force introduced through the tire when the vehicle is turning.

By the way, the conventional torsion beam is a beam manufactured by press-molding the cross section (open cross section), such as X, Y, and U, using a thick iron plate of about 4-5 mm as shown in FIG. Since the conventional torsion beam lacks the torsional rigidity, the bending rigidity, and the oral cavity, the torsion bar for satisfying the torsional rigidity or the bending rigidity and the reinforcing material for satisfying the oral cavity are separately welded to the torsion beam.

However, this type of conventional torsion beam has a problem in that the number of assembly increases according to the increase in the number of parts and the weight of the product increases.

Accordingly, the present invention has been made to solve the above problems, and provides a torsion beam forming method of a torsion beam suspension device that can obtain high torsional rigidity, bending stiffness, and endurance strength without combining additional parts such as torsion bars or reinforcement materials. have.

Another object of the present invention is to provide a torsion beam forming method of a torsion beam suspension device capable of easily forming a torsion beam.

Another object of the present invention is to provide a torsion beam forming apparatus that can easily form a torsion beam.

The torsion beam suspension according to the present invention is a torsion beam suspension device, in which a pair of left and right trailing arms are connected by a torsion beam, and the front end of the trailing arm mounts the vehicle body by a joint. The beam is formed by pressing a pipe of a predetermined thickness over the entire length, and a predetermined section at both ends is a hollow oval cross section, and a predetermined section at the center is a hollow open ring section, and a predetermined distance between the center and both ends. The section is characterized in that the open ring cross section is larger than the central portion of the inner space.

The opening ring of the torsion beam, as shown in Fig. 7 (a, b, c) is a circular pipe on the center 48 of the lower mold 42, the pipe by the upper punch 44 of the upper mold 40 After fixing, both ends of the pipe are fixed by the feeding punches 56 and 56 'as shown in FIG. 7 (e), and then the fluid is injected through the hole 57 in the center of the feeding punches 56 and 56'. After pressurizing the inner wall, the upper mold 40, the upper punch 44, the side mold (52, 52 ') and the lower punch 46 and the central portion 48 is formed by operating in sequence.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

As shown in Fig. 2, a pair of left and right trailing arms 22 and 22 'are connected by a torsion beam 24, and the front ends of the trailing arms 22 and 22' are jointed with rubber bushes. (26, 26 ') pivotally supports the vehicle body (not shown), and the spindle brackets 28, 28' are welded to the rear ends of the trailing arms 22, 22 'to engage the wheels, Spring seats 32, 32 'are welded on the trailing arms 22, 22' between the joint and the spindle bracket so that suspension springs are mounted. The wheels, suspension springs, shock absorbers, and the like are the same as those in FIG.

The trailing arms 22, 22 'are in the form of curved pipes.

The torsion beam 24 is formed by pressure-molding a pipe having a predetermined thickness over its entire length. As shown in the perspective view of FIG. 3 and the cross-sectional views of FIGS. It is an empty oval (or pillow-shaped) cross section (Fig. 6), and a predetermined section (a) at the center thereof is a hollow open ring cross section (Fig. 4), and a predetermined section (b) between the central section and both ends is more inside than the central section. It is a tubular torsion beam having a large open ring cross section (Fig. 5).

4 and 5 are cross-sectional shapes having an outer portion 24a and an inner portion 24b having a predetermined thickness, and may be formed in various forms such as ∧ and ∩. This cross-sectional shape has a large cross-sectional secondary moment and an inertia moment, and thus has high bending rigidity and torsional rigidity.

Both ends of the torsion beam 24 are drilled to be welded in close contact with the outer circumferential surfaces of the trailing arms 22 and 22 '.

One end portion 32a, 32'a of the spring sheet 32, 32 'is welded to the upper outer surface of the b and c sections (shown in FIG. 3) of the torsion beam 24, and the other end thereof. Is deposited on the spindle bracket side of the trailing arms 22, 22 '.

The tubular torsion beam 24 is made of a material having a high fatigue limit and sufficient strength so as to independently support the load supported by the conventional torsion beam, the reinforcement and the torsion bar. Therefore, since the yield strength and tensile strength of the tubular torsion beam 24 are high, it is difficult to form the product, and then pressurizes the inner wall by injecting fluid into the pipe as shown in FIGS. 7A to 7E. Mold.

First, the pipe P forms a central portion of the lower mold 42 and is seated on the central portion 48 whose upper portion is concavely recessed in a U shape. The recess formed in the upper surface of the central portion 48 corresponds to the U-shaped appearance of the open ring. Next, the pipe P is fixed with the upper punch 44 of the upper mold 40. The upper punch 44 has a convex shape in order to mold the U-shaped interior of the open ring, and is inserted into a bowl formed at the center of the upper mold 40 body so that the lower protrusion 40 descends as the upper mold 40 descends. 45) are formed.

Next, the side molds 52 and 52 'are moved to be in close contact with the side surface of the lower punch 46 of the lower mold 42, and then the upper mold 40 is pushed down to lower the body. The circular pipe is shaped into an oval. Section c forming in Fig. 3 is finished at this stage. In this case, the height of the ellipse (the smallest diameter of the ellipse) is appropriately 0.5 to 0.7 times the diameter of the circular pipe. As shown in Fig. 7 (b), the curved surface 47 of the inner groove of the upper mold 40 main body, the convex portion of the upper punch 44, the inner surface of the side mold 52, the upper and lower surfaces of the lower punch 46 are formed. The top surface of the central portion 48 of the mold 42 is used to form an ellipse, respectively, and defines an ellipse. As shown in Figure 7 (b), the upper surface of the side mold (52, 52 ') is matched with the groove 49 formed in the lower portion of the upper mold 40, whereby the side mold (52, 52') so as not to open It is fixed. Thus, before forming the U-shaped open ring, it is possible to form an open ring without breakage by molding the pipe into an ellipse.

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Then, both ends of the pipe P are fixed with the feeding punches 56 and 56 ', as shown in Fig. 7E, and then fluid is injected through the hole 57 in the center of the feeding punch to pressurize the inner surface of the pipe. do. The fluid is an incompressible fluid, and water, oil, and the like can be used. The internal pressure of the pipe is adjusted according to the material and thickness of the pipe, and 4MPA to 12MPA is suitable. Since the inner space of the pipe changes as the forming of the pipe proceeds, it is important to install a servovalve (not shown) in the line for supplying the fluid to thereby maintain the internal pressure of the pipe during the forming process. In this case, it is possible to prevent the molded part of the pipe from being broken during the molding by the upper punch 44 and the lower punch 46 as follows.
Next, the central part 48, the side molds 52 and 52 'and the upper mold 40 body, which are positioned at the center of the lower punch 46, are fixed, and the feeding punches 56 and 56' at both ends of the pipe are fixed at both ends. At the stage, the upper punch 44 is lowered and the lower punch 46 is raised at the same time in the axial direction to the pipe center to form the outer portion 24a and the inner portion 24b of the torsion beam. The upper side surface of the lower punch 46 has a shape corresponding to the outside of the U-shape, and is connected to the upper surface of the central portion 48 to form a complete U-shape. The feeding punches 56 and 56 'can be formed into a U-shaped open ring without any breakage by pressing in the axial direction. In particular, in Fig. 3, the connecting portions of the sections a, b and c are smoothly formed.
For example, as a result of testing using a pipe having a diameter of 90 mm and a length of 1,100 mm, the axial pressurization of such feeding punches 56 and 56 'and the pressurization by the fluid inside the pipe resulted in the step (c) of FIG. After completion the length of the pipe was reduced by 12 mm. During molding, the feeding punches 56 and 56 'are pressurized only in the axial direction and should be fixed so as not to move up, down, left, and right in the axial direction. The upper punch 44 and the lower punch 46 may be integrally formed to form sections a, b, and c of FIG. 3 at one time.

Fig. 7 (d) shows all the molding processes of Figs. 7 (a), (b) and (c), and arrows indicate the force applied to each mold. After completion of Fig. 7 (c), the upper punch 44 is removed to the top, and the lower punch 46 is retracted downward. In this case, the curved portion 47 of the upper mold body and the central portion 48 of the lower mold serve as a rejector so that the formed U-shaped pipe is easily separated from the mold.

According to the torsion beam shaping method according to the present invention, by replacing the torsion beam with a tubular torsion beam having an open ring shape and an elliptical cross section having a hollow space, the torsion beam has a large cross section secondary moment and polar moment of inertia. It has high bending stiffness and non- rigidity stiffness. Therefore, high torsional rigidity, bending rigidity, and endurance strength can be obtained without the torsion bar and the reinforcement that are necessarily assembled together in the conventional torsion beam axle, thereby reducing the number of parts and reducing the weight.

Then, the torsion beam can be completely formed in one continuous process by the above-described forming method and forming apparatus, and in particular, first forming the pipe into an elliptical shape, and then pressurizing the pipe P with a fluid therein and feeding By forming the U-shape while pressing the punches 56 and 56 'in the axial direction, it is possible to form without depressions or breakage portions.

  Although the present invention has been described above with reference to specific embodiments, it should be construed that modifications of the present invention fall within the scope of the present invention as long as they are included in the claims.

Claims (7)

In the method for forming a torsion beam having a hollow U-shaped cross section, (a) placing a circular cross-section pipe (P) of a predetermined thickness on the upper surface of the central portion 48 of the lower mold and fixing it with an upper punch 44 located in the center of the upper mold 40, (b) contacting the side molds 52 and 52 'with the side of the lower punch 46 and lowering the upper mold body 40 and the upper punch 44 to form the pipe P in an elliptical shape, (c) sealing both ends of the pipe (P) with feeding punches (56, 56 ') and injecting fluid through a hole formed in the center of the feeding punch to apply internal pressure to the pipe (P), (d) lowering the upper punch 44 and raising the lower punch 46 at the same time, The upper punch 44 has a U-shaped convex portion corresponding to the U-shape of the inner surface of the U-shaped opening ring, the upper surface of the central portion 48 of the lower mold U-shaped convex portion of the outer surface of the U-shaped opening ring A U-shaped opening, having a corresponding recess, wherein the upper side of the lower punch 46 is connected to the recess of the central portion 48 to form a partial U-shaped recess to form the outer surface of the U-shaped opening ring. Method for forming torsion beam with ring cross section The torsion beam of claim 1, further comprising, after step (c), pressing the feeding punches 56, 56 ′ from both ends of the pipe along the axial direction of the pipe P to the center of the pipe. How to mold The shaping method according to claim 1 or 2, wherein the internal pressure of the pipe in step (c) is 4 MPA to 12 MPA. The method of claim 3, wherein the internal pressure of the pipe is maintained at a constant internal pressure by a servovalve. 3. The method of claim 1 or 2, wherein the smallest diameter of the oval shaped pipe in step (b) is 0.5 to 0.7 times the diameter of the circular pipe.  In the apparatus for forming a torsion beam having a circular open section of U-shaped hollow pipe (P), Body 40 of the upper mold formed in the slit in the center, An upper punch 44 inserted into a slit in the center of the upper mold main body 40 and having a U-shaped convex portion corresponding to the U-shaped shape of the inner surface of the U-shaped opening ring; The central portion 48 of the lower mold having a concave portion whose upper surface corresponds to the U-shaped convex portion of the outer surface of the U-shaped opening ring, A lower punch 46 which is operated up and down along both sides of the central portion 48 of the lower mold, and has a partial U-shaped recess to be connected to the recess of the central portion 48 to form an outer surface of the U-shaped opening; , Located on both sides of the lower punch 46 and includes side molds (52, 52 ') for supporting the outer surface of the long diameter of the elliptical when the pipe is formed into an elliptical, Torsion is formed in the upper mold body 40 has an inner curved surface 47 for forming the pipe in an elliptical shape and a groove 49 for fixing the upper portions of the side molds 52 and 52 'at the time of joining. Beam forming equipment  7. The apparatus of claim 6, wherein the upper punch 44 forms a torsion beam having a protrusion 45 formed thereon so that the main body of the upper mold descends.

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