JP2531971B2 - Aluminum square pipe bending machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Objectives of the Invention (1) Field of Industrial Application The present invention is intended to bend an aluminum square pipe having vertical ribs for reinforcement therein to bend a frame of a motorcycle, for example. A device for forming.

(2) Conventional technology In recent years, as a material for forming a motorcycle frame,
It is known that a wide aluminum square pipe is used in place of the conventional steel pipe having a circular cross section to improve its appearance.

This type of square pipe P has two vertical ribs R for reinforcement inside an aluminum pipe having a flat rectangular cross section, as shown in FIGS. 5 (A) to (C). The vertical rib R and the side wall W form a hollow portion S inside. And the fifth with respect to this square pipe P
By bending in the direction of the arrow in FIG. 5C, a frame having a shape as shown in FIG. 5D is constructed.

However, when bending is performed on the square pipe P by a method of inserting a normal mandrel, as shown in FIGS. 5 (E) and 5 (F), many side walls W, which are inside the bend, are compressed due to compressive stress. Wrinkles a are generated and the appearance is significantly deteriorated.

Therefore, as a method of preventing wrinkles from being generated due to the bending work as described above, a method of bending the pipe in which water is put in a frozen state in advance or a V-shaped portion inside the bend is used. A method of forming a notch and brazing the notch after bending has been proposed.

(3) Problems to be Solved by the Invention However, the method utilizing freezing of water has a problem that the number of steps is increased and the cost is increased. However, there is a problem that not only the number of steps is increased, but also the strength is lowered due to the cut.

The present invention has been made in view of the above-mentioned circumstances, and it is possible to bend an aluminum square pipe without causing wrinkles, and the bending process of an aluminum square pipe does not increase the number of processing steps. The purpose is to provide a device.

B. Structure of the Invention (1) Means for Solving the Problem In order to solve the above problems, the present invention mounts an aluminum square pipe having vertical ribs formed therein on a die, In a device for performing bending by pressing one end of the square pipe against the die with a punch while the other end of the square pipe is fixed, the square pipe has a height equal to or less than the wall thickness and is formed inside the square pipe. In addition, a ridge capable of contacting the outer surface of the hollow portion is provided so as to project along the longitudinal direction of the die.

(2) Action According to the apparatus for bending an aluminum square pipe of the present invention having the above-described configuration, the square pipe fixed on the die is pressed against the die by the punch to bend the square pipe into a predetermined shape. Is given. At this time, wrinkles tend to be generated on the contact surface of the square pipe with respect to the die due to the compressing ability, but the compressive stress is released by forcibly pushing the side wall of the square pipe into the hollow portion by the protruding line protruding on the die. As a result, wrinkles are prevented from being generated on the surface of the square pipe.

(3) Examples Hereinafter, examples of the present invention will be described with reference to the drawings.

1 to 3 show an embodiment of the present invention. FIG. 1 is an overall side sectional view thereof, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. It is explanatory drawing of the effect | action at the time.

As shown in FIGS. 1 and 2, a die 2 that serves as a mold for bending the square pipe P is mounted on the fixed lower die base 1. On the upper surface of this die 2,
A straight supporting surface 3 and a bending surface 4 conforming to a desired motorcycle frame shape are continuously formed, and a lower half portion of the square pipe P is formed in a central portion of the supporting surface 3 and the bending surface 4. The fitting pipe holding groove 5 is recessed over the entire length. Then, one end of a square pipe fitted into the pipe hold groove 5 is brought into contact with the end of the support surface 3 and a stopper 6 is brought into contact therewith.
Are fixed by bolts 7.

On the other hand, a hollow pad holder 9 is fixed to the lower surface of the upper die base 8 located above the lower die base 1 so as to face the supporting surface 3 of the die 2 and slides vertically inside the pad holder 9. The pad 10 movably mounted is urged downward by a spring 11. A pipe hold groove 12 that fits into the upper half of the square pipe P is provided in the center of the lower surface of the pad 10.

Further, a punch holder fixed to the upper die base 8
At the lower end of 13, a punch 15 having a pipe hold groove 14 fitted in the upper half of the square pipe P located at the bending surface 4 of the die 2 is pivotally mounted by a pin 16 so as to be swingable. There is.

As shown in FIG. 3, a ridge 17 is formed over the entire length in the longitudinal direction at the center of the bottom surface of the pipe hold groove 5 of the die 2. The ridge 17 is located corresponding to the outside of the central hollow portion S formed between the two vertical ribs R of the square pipe P, and its height h is the meat of the side wall W of the square pipe P. Thickness t
Is set smaller than. That is, when the wall thickness t of the side wall W of the square pipe P is 2 mm, the height h of the ridge 17 is 20
% Is about 0.4 mm.

Next, the operation of one embodiment of the bending apparatus for an aluminum square pipe according to the present invention having the above-mentioned structure will be described.

First, when the square pipe P is placed on the die 2 and its end is brought into contact with the stopper 6, as shown by the solid line in FIG.
The square pipe P fits into the pipe hold groove 5 on the support surface 4 of the die 2, and is separated from the pipe hold groove 5 at the bent surface 4 portion of the die 2. Subsequently, when the upper die base 8 is lowered by a drive device (not shown), the pad
10 is pressed against the square pipe P while compressing the spring 11, and the square pipe P is sandwiched between the pipe hold groove 12 and the pipe hold groove 5 of the die 2. At the same time, as shown by the chain line in FIG. 1, the punch 15 presses the square pipe P along the die 2 while inclining around the pin 16 and between the pipe hold groove 14 and the pipe hold groove 5 of the die 2. The square pipe P sandwiched is bent into a predetermined shape.

At this time, the lower half part of the square pipe P is fitted into the pipe hold groove 5 of the die 2, and the upper half part thereof is fitted into the pipe hold grooves 12 and 14 of the pad 10 and the punch 15, which accompany bending. The lateral expansion of the square pipe P is restricted. Further, wrinkles tend to occur on the lower surface of the square pipe P inside the bend due to the compressive stress, but as shown in FIG. The compressive stress is released by pushing the central portion of the lower surface of the pipe P into the space S. Therefore, wrinkles do not occur on the surface of the square pipe P even after the bending work is completed, and a frame with a beautiful finish can be obtained.

Although the embodiment of the apparatus for bending an aluminum square pipe according to the present invention has been described above in detail, the present invention is not limited to the above-mentioned embodiment and deviates from the present invention described in the claims. Instead, various small design changes can be made.

For example, as shown in FIG.
Three ridges 17 may be formed in accordance with each of the hollow portions S. Further, as shown in FIG. Forming a hollow portion S,
One ridge 17 may be formed corresponding to one of the hollow portions S. In short, if at least one hollow portion S of the plurality of hollow portions S of the square pipe P is formed with the ridges 17, and the ridges 17 allow the compressive stress to escape, wrinkles are prevented from occurring. be able to.

Further, the height of the ridge 17 protruding to the die 2 is not limited to 20% of the thickness of the side wall W of the square pipe P and should be set appropriately, but generally, as the bending curvature increases, the compressive stress also increases. Since it becomes large, it is desirable to increase the height of the ridges 17.

Although the mandrel is not used at the time of bending in the above embodiment, it goes without saying that the bending may be performed with the mandrel inserted in the hollow portion S of the square pipe P.

C. Effect of the Invention According to the bending apparatus for an aluminum square pipe of the present invention described above, the convex pipe is formed along the longitudinal direction of the die to which the square pipe to be bent is pressed, and the convex pipe is formed by this convex line. Since the side wall is pressed toward the hollow portion, the compressive stress acting in the tangential direction of the side wall during bending is released toward the inside. Therefore, it is possible to obtain a beautifully finished square pipe with no wrinkles on the side wall, and it is extremely economical because no special process is required for its processing.

[Brief description of drawings]

1 is an overall side sectional view of an apparatus for bending an aluminum square pipe according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 3 is a sectional view of a square pipe during bending. Cross section,
4 (A) and (B) are sectional views of a square pipe according to another embodiment of the present invention, and FIGS. 5 (A) to 5 (C) are sectional views of the square pipe.
FIG. 5 (D) is a side view of the frame after bending, and FIGS. 5 (E) and 5 (F) are diagrams showing wrinkle generation. P ... Square pipe, R ... Vertical rib, S ... Hollow part, W ...
Side wall, 2 ... die, 15 ... punch, 17 ... projection

Claims (4)

(57) [Claims] 1. An aluminum square pipe (P) having vertical ribs (R) formed therein is placed on a die (2), and one end of the square pipe (P) is fixed and the other end is fixed. Punch (1
In the device for bending by pressing against the die (2) by 5), the side wall (W) of the square pipe (P) has a height equal to or less than the wall thickness, and the inside of the square pipe (P) Characterized in that a ridge (17) capable of contacting the outer surface of the hollow portion (S) formed in the above is provided along the longitudinal direction of the die (2).
Bending machine for aluminum square pipe. 2. A rectangular pipe (P) is provided with two vertical ribs (R) to form three hollow portions (S), and the die (2) is provided with the above-mentioned three.
The apparatus for bending an aluminum square pipe according to the above item (1), characterized in that one convex strip (17) corresponding to the central hollow portion (S) of the individual hollow portions (S) is formed. 3. A rectangular pipe (P) is formed with three hollow portions (S) by two vertical ribs (R), and the die (2) has the above-mentioned three hollow portions (S).
The apparatus for bending an aluminum square pipe according to the above paragraph (3), characterized in that three ridges (17) corresponding to each hollow portion (S) are formed. 4. A hollow pipe (P) having two hollow portions (S) formed by one vertical rib (R), and the die (2) having the above-mentioned two hollow portions (S).
The apparatus for bending an aluminum square pipe according to the above item (1), characterized in that one ridge (17) corresponding to one of the hollow portions (S) is formed.