JPH05177261A - Device for bending corrugated pipe - Google Patents

Abstract

PURPOSE:To obtain the required bending curve by always restricting the projecting part of corrugated pipe to the vertical direction against the bending surface of pipe and the center axis of pipe and relatively making so that the un- deformed projecting part of corrugated pipe is made to be easily bent. CONSTITUTION:Because the projecting part of pipe of the pipe 16 to be bent is always restricted with a pipe projecting part restricting means 18, the deforming of sectional shape due to the flatness of pipe 16 during processing the pipe 16 can be almost prevented. Therefore, at the projecting part of pipe 16 being deformed with bending, the reduction of the geometrical moment of inertia is almost eliminated, the side of the increase of machining hardening with the plastic deformation is become larger than the increase of the property to be easily bent with the reduction of the geometrical moment of inertial. So, at the projecting part of deformed corrugate pipe 16, the bending toughness is become larger corresponding to the increase of deformed amount. That is to say, the property to be easily bent of un-deformed projecting part of corrugate pipe 16 is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bending apparatus for preventing concentration of bending on a local portion of a pipe when bending a corrugated pipe.

[0002]

2. Description of the Related Art As shown in FIG. 4, a corrugated pipe having a corrugated cross section in the axial direction of the pipe,
Bending was done manually, relying on intuition and tips. For example, only both ends of the corrugated pipe are gripped by hands. (There is no restraint on the other part at all) Then, apply force with both hands in the pipe bending direction at both ends of the pipe centering on the part you want to bend.
However, in a corrugated pipe, bending is often concentrated at only one place as shown in FIG.

The state of the pipe when it is bent by a pipe bending apparatus that can be simply configured as an apparatus and applies a force only in the direction of rotation of the pipe will be described below. Generally, in bending a straight pipe in which the shape of the cross section in the axial direction of the pipe does not change, the processed portion is supported by the plastic deformation of the material, and therefore the bent portion is difficult to bend due to work hardening. At the same time, the cross section of the machined part is slightly flattened, and the secondary moment of area decreases (the bending ease increases when the secondary moment of area decreases). In other words, in the bending part, regarding ease of bending,
There are two effects, the second moment of area and work hardening. However, since the amount of flattening is small, even if the bending ease increases due to the decrease of the second moment of area, the effect of work hardening due to plastic deformation is much greater, and the bending work due to flattening (reduction of the second moment of area) Has little effect on For this reason, the bendability of the unprocessed part of the pipe becomes relatively large, and if the bending force is applied continuously, the unprocessed part of the pipe deforms.

On the other hand, in bending a corrugated pipe, unlike a general pipe, the shape change accompanying the expansion of the pipe convex portion in the pipe axial direction is responsible for most bending deformation. That is, since the plastic deformation is less than that of a general pipe, the work hardening is less. In addition, the cross section of the deformed pipe protrusion is as shown in FIG.
Due to the large flatness, the second moment of area is greatly reduced compared to the other convex portions. As described above, in the deformed corrugated pipe convex portion, the increase in bending easiness due to the second moment of area becomes larger than the increase in work hardening due to plastic deformation. It becomes easier to bend than the part. If the bending is continued by applying a force only in the bending direction in the state as described above, the bending concentrates on the first deformed corrugated pipe convex portion as shown in FIG. 7 due to the flattening.
Therefore, a corrugated pipe cannot be bent as desired by a pipe bending apparatus that applies a force only in the turning direction of the pipe.

As another bending apparatus, if the concentration of bending can be prevented by suppressing the flatness of the pipe (preventing a decrease in the second moment of area), the member for preventing the flatness of the pipe is simply used to prevent the flatness of the corrugated pipe. It is possible to prevent the concentration of bending. For example, regarding a straight metal pipe in which the shape of the cross section in the axial direction of the pipe does not change, a bending jig for preventing the flatness of the pipe by showing the outer diameter of the pipe along the curved groove is shown in the actual flat plate 1-100616. There is. Consider the case where such a jig is used for bending a corrugated pipe.

First, as shown in FIG. 5, the corrugated pipe is sequentially bent along the curved groove. At this time, the convex portion of the pipe which is in contact with the curved groove is restrained by the curved groove. However, the other convex portions that are not in contact with the curved groove are not restrained. If bending is performed in this state, bending may occur not in the pipe protrusions that are in contact with the bending groove but in the pipe protrusions that are not restrained and have a slightly lower strength. , The pipe wall pressure is thinner than that of the other protrusions. Bending begins to occur in the pipe protrusions with a slightly lower strength.) Bending occurs The pipe protrusions with a lower strength are bent without any restraint. , When it deforms, it becomes flat. In other words, the second moment of area is greatly reduced in the convex portion of the pipe which is bent and has low strength. At this time, in the deformed portion of the corrugated pipe, bending is taken care of by the change in shape of the convex portion of the pipe, so that the amount of plastic deformation is small and the influence of work hardening is small.

As described above, even when the jig disclosed in Japanese Patent Application Laid-Open No. 1-100616 is used, in the bending portion of the corrugated pipe, the increase in bending easiness due to the decrease in the second moment of area is due to the plastic deformation. Since it becomes larger than the increase in work hardening, the ease of bending only increases in the convex portion during bending, and the bending concentrates on the convex portion that is not constrained during bending, and the bending curve of the corrugated pipe is not constant. Will occur.

In the present invention, during bending,
By always constraining the corrugated pipe convex portion in the direction perpendicular to the pipe bending surface and the center axis of the pipe, the flatness of the corrugated pipe convex portion is prevented, and increase in bendability due to reduction of the second moment of area is prevented. By increasing only work hardening due to plastic deformation in response to an increase in the amount of bending deformation, the bendability of the relatively undeformed corrugated pipe convex portion is increased, and the convex portion of the undeformed corrugated pipe is increased. The purpose is to evenly bend.

[0008]

[Means for Solving the Problems] A technical means for solving the above-mentioned problems is to provide opposed surfaces that sandwich a plurality of convex portions of a corrugated pipe in a direction perpendicular to the pipe bending surface and the central axis of the pipe. A pipe convex portion restraining means, and two pipe supporting means for respectively supporting the pipe portions located on both sides with respect to the axial direction of the pipe with the sandwiched convex portion as a center and in the vicinity of the convex portion. The pipe supporting means includes at least one driving means for pressing the supported pipe in the pipe bending direction.

[0009]

By the above means, the convex portion of the pipe on which the pipe is bent is always restrained by the convex portion restraining means of the pipe, so that the change in the cross-sectional shape due to the flatness of the convex portion of the pipe is almost prevented during the processing of the pipe. be able to. For this reason, in the convex portion of the pipe that is deformed by bending, there is almost no decrease in the second moment of area, and the increase in work hardening due to plastic deformation is larger than the increase in bendability due to the decrease in second moment of area. Become. Therefore, in the deformed corrugated pipe convex portion, the bending stiffness increases as the amount of deformation increases. That is, the bendability of the undeformed corrugated pipe convex portion becomes relatively large, and the corrugated pipe convex portion of the undeformed portion is bent. Further, at this time, since the undeformed pipe convex portion is always constrained by the corrugated pipe constraining portion, the deformation can be performed without causing the reduction of the second moment of area, and the other deformations are sequentially performed. The convex part of the pipe that is not deformed.

[0010]

Next, a first embodiment of the present invention will be described below with reference to FIGS. 1, 2 and 3. The corrugated pipe that was bent this time is JIS made of aluminum
A3003-H18 material was bulged by high frequency, and a product having a shape as shown in FIG. 1 was used. (Thickness of plain tube 1.2
mm, tube diameter 12.7 mm, bulge spacing 10 mm, bulge diameter 18.0 mm)

The bending operation by the bending apparatus will be described below with reference to FIGS. 1, 2 and 3. As a first step, one end of the corrugated pipe 16 is supported by the chuck 12 of the chuck fixing base 11 to support the pipe 16. The other end of the pipe 16 is supported by the pipe gripping claws 17 on both sides of the pipe, sandwiching a pipe convex portion to be bent.

In the second step, the sliding cylinder 19 is slid so that the resin convex portions 22 on the upper and lower inner walls of the corrugated pipe restraining portion 18 hold the convex portion of the pipe to be bent. Since the corrugated pipe restraining portion 18 is provided with the resin portion 2 at the contact portion with the pipe convex portion, the corrugated pipe restraining portion 18 prevents the pipe convex portion from being scratched when sandwiched. A state in which the corrugated pipe 16 is thus sandwiched in the direction perpendicular to the bending surface is shown in an enlarged manner in FIG.

As the third step, with the corrugated pipe 16 being restrained as shown in FIG. 2, the servo motor 20 is rotated in the direction of arrow A in FIG.
The equipment pedestal 13 provided with the one pipe gripping claw 17 is rotated in the direction of the arrow B in FIG. Then, when a pressing force is applied in the bending direction, the corrugated pipe 16 is deformed and bent at the convex portion at the center of the pipe that is going to be bent. At this time, the pipe convex portion is subjected to a force to flatten it in a direction perpendicular to the bending surface due to bending deformation, but during the bending process, the pipe convex portion is always restrained by the resin portion 22 of the corrugated pipe restraining portion 18. Therefore, the flatness of the pipe diameter is suppressed by the corrugated pipe restraining portion 18, and the change in the cross-sectional shape due to the flatness of the convex portion of the pipe 16 is almost eliminated during bending of the pipe.

As described above, since the flatness on the bent surface of the pipe is eliminated, the second moment of area is hardly reduced at the convex portion of the corrugated pipe 16 at the deformed portion, and the second moment of area at the convex portion of the corrugated pipe 16 is almost eliminated. The increase in work hardening due to plastic deformation of the pipe is larger than the increase in bendability due to the decrease in. That is, in the deformed convex portion, the bending stiffness increases corresponding to the increase in the bending deformation amount, and the relatively undeformed pipe convex portion is easily deformed. Therefore, as the bending is continued, the undeformed pipe convex portions are sequentially bent. At this time, the convex portion of the corrugated pipe 16 which is deformed sequentially,
Since it is constrained by the corrugated pipe constraining portion 18, it can be deformed without causing a decrease in the second moment of area, and the bending deformation of the pipe gradually moves to the outer convex portion. In this way, a desired bending curve can be obtained without the bending of the corrugated pipe being partially biased.

After bending at one bending point, as a fourth step, the sliding cylinder is slid to remove the corrugated pipe restraining portion 18 from the pipe. Then, attach the chuck base 11 to the ball screw 2
The corrugated pipe 16 is moved to the next bending position by moving the corrugated pipe 16 in the direction of the arrow C in FIG. After the movement, if necessary, the chuck 12 is rotated to change the bending direction of the pipe 16. After that, returning to the second step, bending is performed, and the corrugated pipe 16 can obtain a predetermined bent shape as shown in FIG.

Further, in this embodiment, since the bent groove is not brought into contact with the inner side of the bent surface of the pipe and the convex portion of the corrugated pipe is restricted only in the holding direction, the flatness of the pipe is prevented. The flatness can be suppressed without impairing the flexibility of the curve.

[0017]

According to the present invention, the convex portion of the corrugated pipe is always constrained in the direction perpendicular to the bending surface of the pipe and the central axis of the pipe to prevent the flatness of the corrugated pipe and reduce the second moment of area. The increase in bending ease of the corrugated pipe in the undeformed portion is increased by preventing the increase in bending ease and increasing only the work hardening due to plastic deformation in response to the increase in the amount of bending deformation. By doing so, it is possible to prevent the bending of the corrugated pipe from being concentrated locally.

[Brief description of drawings]

FIG. 1 is a top view and a side view showing a corrugated pipe bending apparatus according to the present invention.

FIG. 2 is a side view showing a state in which the corrugated pipe 16 is restrained by a corrugated pipe restraining portion 18.

FIG. 3 is a side view showing the shape of a corrugated pipe used in the present invention.

FIG. 4 is a side view of the corrugated pipe showing that the bending is locally concentrated by the conventional technique (manual bending).

FIG. 5 is a top view showing a bending operation of a corrugated pipe according to a conventional technique (bending using a jig).

FIG. 6 is a cross-sectional view of a flat corrugated pipe convex portion that has been bent by a conventional technique and is flat.

FIG. 7 is a top view of a corrugated pipe in which bending is performed according to a conventional technique and the bending is concentrated.

[Explanation of symbols]

 11 ・ ・ ・ Chuck fixing base 12 ・ ・ ・ Chuck (for pipe fixing and rotation) 13 ・ ・ ・ Equipment pedestal 14 ・ ・ ・ Chuck fixing base slide rail 15 ・ ・ ・ Bending control unit 16 ・ ・ ・ Corrugated pipe 17 ・..Pipe gripping claws 18 ... Corrugated pipe restraint portion 19 ... Cylinder for sliding the restraint portion 20 ... Bending servo motor 21 ... Ball screw for moving chuck fixing base 22 ... Resin portion

Claims (1)

[Claims] 1. A pipe convex portion restraining means having opposing surfaces for sandwiching a plurality of convex portions of a corrugated pipe in a direction perpendicular to a pipe bending surface and a central axis of the pipe, and the sandwiched convex portions. The two pipe supporting means which are located on both sides with respect to the axial direction of the pipe and which respectively support the pipe portions in the vicinity of the convex portion;
An apparatus for bending a corrugated pipe, comprising at least one driving means for pressing the supported pipe in a pipe bending direction.