JPH0813376B2 - Camber forming method for leaf spring for vehicle suspension and camber forming apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camber forming method and a camber forming apparatus for leaf springs used in suspension springs for automobiles.

[0002]

2. Description of the Related Art Bending of a leaf spring material into an arc shape or a shape close to it while heating is called camber molding. The camber of the leaf spring for vehicle suspension has a curved shape which is continuous with a substantially constant curvature from the central portion in the longitudinal direction of the spring to both ends. A carving roll method is known as a conventional camber molding method. The carving roll method is a method in which a heated leaf spring material is sandwiched and passed between a rotating roll and a template to form an arc shape of the leaf spring material. Problems with this carving roll method include difficulty in automation, skill required for work, difficulty in accurately copying the shape of the template, variation in shape, and deformation of the template due to heat.

Further, a pushing piece pressing device 1 as shown in FIG.
A molding method using is also known. In this device 1, a plurality of pressing pieces 2 press the leaf spring material A against the curved surface 4 of the template 3 to impart a camber having a curvature corresponding to the curved surface 4. Each push piece 2 is shown in FIG.
As shown in FIG. 3, the leaf spring material A is moved by the actuators 5 each using a hydraulic cylinder or the like in a direction synchronous with each other and parallel to each other.
It is pressed against the curved surface 4.

[0004]

In the conventional camber molding method using the pressing piece pressurizing device 1, when the number of the pressing pieces 2 is small, it becomes difficult to follow the shape of the curved surface 4 of the mold plate 3, and thus the shape of the curved surface 4 of the template 3 becomes difficult to follow. A gap may be formed between the template 3 and the leaf spring material A at an intermediate position between the adjacent pushing pieces 2 and 2, and the arc shape may be deformed or the shape may be varied. In particular, when forming a leaf spring whose radius of curvature is not constant and whose curvature changes in the middle, or when the thickness of the leaf spring changes in the longitudinal direction, the formability is poor.

Further, when the above-mentioned conventional apparatus 1 is used, since a relatively large springback occurs after molding, the radius of curvature of the leaf spring A'after molding is slightly smaller than the radius of curvature of the curved surface 4 of the template 3. growing. Especially, the leaf spring material A is used as the template 3
When the pressing time is short, the amount of springback is large, and therefore the shape of the template 3 must be formed in anticipation of the springback amount, which also causes deterioration of the shape accuracy.

Further, in the case of a leaf spring having a deep camber, the pushing piece 2a located near the end of the leaf spring material A is
Since a relatively large lateral load is applied, even if the pushing piece 2a and the actuator 5 have a large rigidity, the pushing piece 2a and the actuator 5 are
There is a tendency to bend outward as shown by an imaginary line, and the gap between the pressing pieces 2a and 2b is widened, which causes a defective shape. Incidentally, US Pat. No. 4,603,567
Like the arm forming device described in the specification, a thin plate spring-like arm (thickness of about 0.05 to 0.08 mm)
There is also a device for bending the material into a “claw” shape, in which one end of the material (thin leaf spring arm) is clamped and one side is cold pressed by a roller from the center of the material. In the device, it is impossible to camber a spring having a very large thickness (a thickness of about 4 to 13 mm) like a leaf spring for vehicle suspension into an arc shape over its entire length. Further, as in the iron plate bending device described in Japanese Patent Laid-Open No. 62-179820, a device for forming a material into a polygonal shape, and a pressurizing die having V-shaped two-faced surfaces, The material is set between a pair of right and left cylindrical pressure supporting rolls, and the sharp bending point between the two surfaces of the pressure mold presses the center bending point of the material and the pressure supporting roll. It has been proposed to repeatedly perform the approaching or separating operation with respect to the bending point. However, in such a conventional technique, although a part of the material can be bent into an L shape, it is necessary to bend the entire material length in an arc shape and smoothly like a camber of a leaf spring for vehicle suspension. It is impossible to mold the camber.

Therefore, an object of the present invention is to make a large leaf spring, such as a leaf spring for vehicle suspension, which is thick and difficult to bend. It is an object of the present invention to provide a camber molding method and a camber molding apparatus that can impart a shaped camber, have little influence of springback, etc., and can accurately mold a deep camber.

[0008]

SUMMARY OF THE INVENTION A camber molding apparatus of the present invention developed to achieve the above object has a template having a curved surface corresponding to the curvature of the camber of a leaf spring to be molded, and a template of the template. A central pressing piece that is provided so as to face the central portion in the longitudinal direction of the curved surface and is capable of pressing the longitudinal central portion of the leaf spring material against the curved surface of the template, and the leaf springs are arranged on both sides of the central pushing piece. A pair of movable pressing pieces having rollers capable of pressing the material on the curved surface of the template, and pressing these moving pressing pieces against the leaf spring material respectively to press the material on the curved surface and The pushing piece driving means is provided for squeezing the surface of the leaf spring material while moving the opposite ends of the leaf spring material in opposite directions in synchronization with each other.

[0009]

In the method of the present invention, the center pressing piece is provided facing the central part in the longitudinal direction of the curved surface of the template having the curved surface corresponding to the curvature of the camber of the leaf spring to be molded, and the heated plate is heated. After pressing the central part of the spring material to the central part of the curved surface of the template by the central pressing piece, the leaf spring material is moved to the curved surface of the template by the moving pressing pieces arranged on both sides of the central pressing piece. By simultaneously squeezing each moving push piece in opposite directions toward both ends of the leaf spring material while pressing in the plate thickness direction between and by simultaneously squeezing from the longitudinal center of the material toward both ends, In the present invention, which is characterized by imparting a camber along the curved surface of the template, in order to squeeze the leaf spring material heated by the furnace in the longitudinal direction so as to follow the curved surface of the template by the moving push piece, Move push The material surface on the outside of the curve directly receiving the load of the piece is deformed in the extending direction as compared with the inside of the curve, and this extension assists the curve forming of the material. For this reason, it is easy to bend it into a correct shape along the mold, and the amount of springback generated is extremely small. Since each moving push piece squeezes the material while moving in opposite directions in synchronization with each other toward both ends of the leaf spring material with the central push piece as a boundary, the force acting in the moving direction of each moving push piece cancels out. To be done. Therefore, no load is applied to the central pushing piece in the longitudinal direction of the material, and the material can be prevented from moving in the longitudinal direction. Due to these reasons, the plate thickness is extremely large like a leaf spring for vehicle suspension and the spring length is 400 to 1000 m.
Even a large spring having a plate width of about 40 to 80 mm at around m can accurately form a camber continuous in an arc shape over its entire length.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. The camber molding apparatus 10 of the illustrated example includes a template 11. On the lower surface side of the template 11 in the figure, a convex curved surface 12 is provided with a curvature corresponding to the camber of the leaf spring to be molded. The plate thickness of the template 11 (dimension in the direction orthogonal to the paper surface) may be smaller than the plate width of the leaf spring material A, but in some cases, the leaf spring material A
The plate thickness of the template 11 may be larger than the plate width. Although the curved surface 12 in the illustrated example has a bilaterally symmetrical shape, it may have a bilaterally asymmetrical shape in some cases.

A central pressing piece 15 is provided facing the central portion of the curved surface 12 of the template 11. The central pressing piece 15 presses the central portion of the leaf spring material A in the longitudinal direction against the curved surface 12 of the template 11. This center push piece 15
Is a first actuator 16 using a hydraulic cylinder or the like.
By means of this, it is configured to be reciprocally driven in a direction in which the curved surface 12 is brought into contact with and separated from the curved surface 12 (vertical direction in the drawing).

Moving push piece units 20 and 21 are provided on the left and right sides of the central push piece 15, respectively. The moving push piece units 20 and 21 are symmetrical to each other, and include moving push pieces 22 and 23, respectively. Rollers 25 and 26, which rotatably contact the leaf spring material A, are provided on the respective moving push pieces 22 and 23. The number of rollers 25 and 26 is one or two for each pressing piece 22 and 23.

The movable push pieces 22, 23 are provided with a horizontal shaft 3
It is attached to the tips of the links 32 and 33 by 0 and 31. The bases of the links 32, 33 have support shafts 34, 3
5, the bracket 42 of the movable base 40, 41,
It is rotatably supported by 43.

One of the links 32 is connected to the support shaft 34 by a second actuator 50 using a hydraulic cylinder or the like.
It is designed to be reciprocally rotated around. The moving push piece 22 attached to the link 32 moves in a direction of pressing the leaf spring material A against the curved surface 12 of the template 11 when the rod portion 51 of the actuator 50 moves to the extending side.

The other link 33 is reciprocally rotated about the support shaft 35 by a third actuator 53 using a hydraulic cylinder or the like. This link 33
The moving push piece 23 attached to the plate 53 also presses the leaf spring material A against the curved surface 12 of the template 11 when the rod portion 54 of the actuator 53 moves to the extending side.

The movable bases 40 and 41 can be moved in opposite directions in synchronization with each other by driving mechanisms 60 and 61 that can move back and forth in the horizontal direction. The movable bases 40 and 41 can move in the horizontal direction along the guides 62 and 63 from the movement start position shown in FIG. 2 to the movement end position shown in FIG. The movement start position and the movement end position of the movable bases 40 and 41 can be arbitrarily set by changing a set value input to a controller (not shown) using a computer that controls the drive mechanisms 60 and 61. It is like this. The actuators 50 and 53 and the drive mechanism 6 described above
0, 61, etc. constitute the pushing piece driving means 65.

Next, the operation of the camber molding apparatus 10 having the above structure will be described. As shown in FIG. 2, the central pushing piece 15 is driven toward the extension side by the first actuator 16, and the central portion of the leaf spring material A in the longitudinal direction is moved to the center of the curved surface 12 of the template 11 by the central pushing piece 15. It is pressed against the department. Further, the links 32 and 33 are connected to the actuator 5
By rotating the support shafts 34 and 35 in the ascending direction by 0 and 53, the rollers 2 of the moving push pieces 22 and 23 are rotated.
5, 5 and 26 are pressed against the leaf spring material A, and the leaf spring material A is pressed against the curved surface 12 of the template 11. The leaf spring material A is preheated by a furnace (not shown).

In the above state, the movable bases 40 and 41 are moved in the plate end direction in synchronization with each other by the drive mechanisms 60 and 61. As a result, while the leaf spring material A is pressed against the curved surface 12 of the template 11, the lower surface side (outer surface of the curve) of the leaf spring material A is strongly urged from the central blow to the plate end side by the rollers 25 and 26. Be scared. At this time, the rollers 25,
26 rotates and rolls in the longitudinal direction of the leaf spring material A. In this way, the leaf spring material A is formed on the curved surface 12 of the template 11 in an arc shape according to the curvature.

As described above, the lower surface side of the heated leaf spring material A, that is, the outer surface of the curved camber is the roller 2.
Since it is molded while being squeezed by the rollers 5, 26, the surface on the side receiving the roller load (outside the curve) is longer by ΔL than the surface on the side not receiving the roller load (inside the curve). A leaf spring A ′ having a camber with a very high precision is obtained, which conforms well to the R shape of the curved surface 12 of 11 and thus causes almost no springback.

[0020]

According to the present invention, an accurate camber is applied along the curved surface of the template while squeezing the surface of the leaf spring material from the central portion of the leaf spring toward both ends by the moving push piece. The camber shape has little variation. Further, since the springback after molding is small, the difference between the curvature of the curved surface of the template and the curvature of the camber actually molded can be small. And the leaf spring of the camber,
A leaf spring having a small radius of curvature can also be formed. Further, various camber shapes can be dealt with only by numerically controlling the setting of the movement start position and the movement end position of the pushing piece by the computer.

[Brief description of drawings]

FIG. 1 is a front view of a camber molding apparatus according to an embodiment of the present invention.

FIG. 2 is a front view showing a state where a push piece of the device shown in FIG. 1 has moved.

FIG. 3 is a front view showing a movement ending position of a pushing piece of the device shown in FIG.

FIG. 4 is a front view showing a conventional camber molding apparatus.

5 is a front view showing an operation mode of the conventional apparatus shown in FIG.

[Explanation of symbols]

A ... Leaf spring material, 10 ... Camber forming device, 11 ... Template, 12 ... Curved surface, 15 ... Central pushing piece, 22, 23 ... Moving pushing piece, 25, 26 ... Roller, 40, 41 ... Movable base.

Claims (2)

[Claims] 1. A center pressing piece is provided so as to face a central portion in the longitudinal direction of the curved surface of a template having a curved surface corresponding to the curvature of the camber of the leaf spring to be molded, and the center of the heated leaf spring material. Part is pressed against the central part of the curved surface of the template by the central pressing piece, and then the leaf spring material is moved between the curved surface of the template by the moving pressing pieces arranged on both sides of the central pressing piece. By simultaneously squeezing each moving push piece toward opposite ends of the leaf spring material while pressing in the plate thickness direction and simultaneously squeezing from the longitudinal center of the material toward both ends, A method for forming a camber for a leaf spring for vehicle suspension, which comprises applying a camber along a curved surface. 2. A template having a curved surface corresponding to the curvature of the camber of the leaf spring to be molded, and a central portion in the longitudinal direction of the leaf spring which is provided so as to face the central portion in the longitudinal direction of the curved surface of the template. A central pressing piece capable of pressing the portion against the curved surface of the template, and a pair of movable pressing pieces disposed on both sides of the central pressing piece and having rollers capable of pressing the leaf spring material against the curved surface of the template. , The moving pressing pieces are pressed against the leaf spring material to press the material against the curved surface, and the moving pushing pieces are moved in opposite directions toward both ends of the leaf spring material in synchronization with each other. A camber forming device for a leaf spring for vehicle suspension, comprising: a pushing piece driving means for squeezing the surface of the.