JPS60196228A - Press bending die for metallic pipe - Google Patents

Abstract

PURPOSE:To enable bending to a small diameter by dividing a pressure die among titled dies to two upper and lower parts, forming the two parts into a fitting construction, forming the dies having grooves for fitting a metallic pipe into slide dies and moving the slide dies to the right and left during pressing. CONSTITUTION:An arc-shaped bending die having a groove 3 for fitting a metallic pipe on the outside periphery is the same as in the prior art. A pressure die is divided to the right and left parts each consisting of a slide die 12 having a groove 14 for fitting the metallic pipe and having sliding grooves 15, 15 on both upper and lower side faces and a pressure base die 13 having sliding projections 16, 16 to engage with the grooves 15, 15. Stop plates 17 are projected to the top surface of the dies 13 on the rear of said dies and cushion materials 18 are fitted between said plates and the rear surfaces of the dies 12. Tension springs 19 are extended between the front of the dies 12 and the rear of the dies 13. Bending to a small diameter is made possible by the above-mentioned constitution and the dies are made applicable to bending of an exhaust pipe of an automobile, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a press bending die for metal pipes used for press working of small diameter curved pipes for complex piping into narrow spaces such as engine exhaust pipes.

Conventionally, the press bending method for metal tubes consists of a bending die (1) and a pressure die (2), as shown in Fig. 5, and is an arc-shaped bending method that has a fitting groove (3) for the metal tube on the outer periphery. A mold (1), and left and right pressure molds (2) which are divided into left and right parts and have a metal tube fitting groove (4) on the top surface, and whose left and right ends spring up when pressed by the bending mold with a rotating shaft (5). (2) It was manufactured using a metal tube press bending mold. With such a mold, for example, in a pipe shape bent at 90°, the bent part (7) of the metal pipe (6) is thinned and the diameter is 80° compared to the normal pipe diameter, as shown in Figure 6.
The diameter of the product was 0% or less, and the finish of the product was extremely poor. In particular, for small bending radii (R), R<1.5D
Under these conditions, it was difficult to even ensure that the pipe diameter (D') of the bent portion was 0.8D.

Therefore, it is difficult to bend metal pipes for automobile engine exhaust pipes, and cast pipes have no choice but to be used, which increases manufacturing costs and requires the use of heavy materials.

The mold according to the present invention has R<1, which was extremely difficult in the past.
．． This has been improved to ensure good bending with d>o and gD at the bending part even under 5D conditions.The pressure mold is divided into upper and lower parts, and the upper metal pipe fitting groove part is a sliding type. By moving the slide mold left and right during pressing, the above drawbacks could be solved.

FIG. 1 is a front view of the mold of the present invention, and FIG. 2 is a side view of the same. Figure 3 shows the state when bent at 45°, and Figure 4 shows the state when bent at 90°.
FIG. 41 is a front view showing the state at the time of L.

As is clear from Figures 1 and 2, the bending die (11)
The shape is the same as the conventional one, but the pressure mold is divided into a slide mold (12) and a pressure base mold (13), and the two are fitted into each other.

The arc diameter (RM) of the bending die (11) is, for example, the pipe diameter D=
In the case of 43φ, it was difficult to process when RM = 80XD/2 or less, but sufficient bending can be done even if the RM is reduced to 63XD/2, so if the bending diameter is the same, a smaller bending die is sufficient. There is.

The slide type (12) has a metal tube fitting groove (14) on the top surface like the conventional pressure type, and slide grooves (15) on both lower sides.
) (15), which has a fitting structure with the sliding protrusion (16) (16) of the pressure base type (13).

At the rear of the pressure base mold (13), there is a stop plate (
17) protrudes to the upper surface, and a cushioning material (18) of urethane rubber, natural rubber, or
At the same time as fitting the thick plate, a tension spring (19) is stretched between the front of the slide mold (12) and the rear of the pressure base mold (13). The cushioning material (18) is used to soften the impact during molding, and the tension spring (19) is used to prevent the left and right sliding molds from colliding with each other, and to quickly return the sliding molds to their original state when bending is completed. It is. The movement of the slide die and the pressure base die when bending is performed using the metal tube press bending die of the present invention is as follows.

When the pipe starts to be bent, the pressure of the bending die is applied to the bending center point, and the squeeze bending starts.

Figure 3 shows the state of bending at 45 degrees, where the slide mold moves along the R part of the upper mold without changing its position, and only the pressure base mold moves along the curve RxJEr. It has a similar structure.

Therefore, little shearing force is applied between the bending mold and the sliding mold, and the surface of the metal tube is not roughened. In terms of appearance, the sliding type will remain, and most of the pressure-based types will open to the left and right. Figure 4 shows the state of 90° bending, and the 45° bending state continues to occur up to this point, and there is an increasing difference in the amount of movement between the slide type and the pressure base type, and the tension spring (1
9) grows.

When bending more than 90 degrees, it is necessary to further widen the gap between the pressure base molds, so the sliding effect gradually weakens, and the bending angle is generally limited to about 135 degrees.

In addition, when bending 90 degrees or more, it is advisable to open the pressure base mold beforehand (move it back to the left and right) from the slide mold, if necessary, so that the slide mold and the upper mold do not come into contact with each other. In addition, it goes without saying that the shape, relative size, gap arrangement, etc. of each type are determined by the diameter, plate thickness, bending angle, required bending strain, etc. of the metal tube.

By using the mold described in detail above, the friction between the metal tube and the pressure mold is reduced, and it can be bent easily, making it possible to bend small diameter surfaces of 1.5R or less, which was previously difficult. Moreover, since the press pressure is small, the press machine itself can have a small capacity, which is useful for downsizing and reducing equipment costs.

Furthermore, the obtained processed product with a small diameter R can be applied, for example, to automobile exhaust pipes, so it can replace conventionally expensive and heavy cast products, and is also useful for reducing the weight of engines.

[Brief explanation of drawings]

FIG. 1 is a front view of the mold of the present invention, and FIG. 2 is a side view of the same. FIG. 3 is a front view showing the state when bent at 45 degrees, and FIG. 4 is a front view showing the state when bent at 90 degrees. FIG. 5 is a front view showing a conventional mold. FIG. 6 is a side view of the metal tube after bending. (3) (14) Fitting groove (5) Rotating shaft (6) Metal tube
(7) Bending part of pipe (11) Bending type (12) Slide type (13) Pressure base type (15) Sliding groove (16) Sliding protrusion (17) Stop plate (18) Cushioning material (19) Tension More than a spring

Claims (1)

[Scope of Claims] 1 has an arc-shaped bending mold having a metal tube fitting groove on the outer periphery, and 1 has a metal tube fitting groove on the upper surface that is divided into right and left parts, and has a rotation axis that allows the bending mold to be pressed to the left and right sides. The metal tube press bending mold consists of left and right pressure molds with spring-up ends.The pressure mold is divided into an upper slide mold and a lower pressure base mold. A press bending mold for metal tubes with a matching groove and a pressure base mold and a slide mold that are slidably engaged. 2. A stop plate is provided at the rear of the pressure base mold, a cushioning material is fitted between the stop plate and the rear surface of the slide mold, and a tension spring is stretched between the rear of the pressure base mold and the front of the slide mold. A press bending mold for a metal tube according to item 1.