JPH0724870B2 - Pipe bending machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a pipe to be sandwiched, which is located between a bending die and a clamping die, with a core metal being located inside the pipe, and a peripheral surface of the bending die. The present invention relates to a pipe bending machine having a mechanism for bending along a pipe.

[Conventional technology]

In the pipe bending machine, the core metal is positioned inside the pipe to be bent during bending, because the pipe to be bent is deformed such that the outside of the bent portion and the inside of the bent portion come close to each other during processing, and the final pipe shape is This is to prevent an improper shape that is significantly different from the shape before bending.

In the conventional pipe bending machine, the following core bar is positioned in the pipe to be bent.

That is, as shown in FIG. 7, the outer diameter dimension is the bent pipe (3).
Of the insertion member (41a) corresponding to the inner diameter of the pipe to be bent (3) and having an outer diameter corresponding to the inner diameter of the pipe to be bent (3). Material (41
b) A mandrel (41) that is swingably connected, or the 8th
As shown in the figure, a cored bar (41) was used in which a plurality of (three in the figure) correction members (41b), ... Are directly connected in a bead to the insertion member (41a).

[Problems to be Solved by the Invention]

When using a conventional pipe bending machine that bends the cored bar (41) inside the pipe to be bent (3), the pipe to be bent (3) is bent at the time of bending. Due to the presence, the outer side of the bent portion and the inner side of the bent portion are hardly deformed, and it is possible to prevent the final tube shape from becoming an inappropriate shape. There is a problem that wrinkle-like defects are generated because a large compressive stress acts on the inside of the bent portion.

An object of the present invention is to provide a tube bending machine that can solve such problems and can prevent the final tube shape from becoming an inappropriate shape, as in the conventional tube bending machine.

[Means for Solving the Problems]

The pipe bending machine according to the present invention is provided with a mechanism for bending a pipe to be bent located between a bending die and a clamping die along a peripheral surface of the bending die while positioning a core metal in the pipe. In the tube bending machine described above, the core metal has an outer diameter dimension corresponding to the inner diameter dimension of the pipe to be bent, and an insertion member having a cylindrical peripheral surface to be inserted and extracted along the axial direction of the pipe to be bent, The insert member and the corrective member are composed of a corrective member that is disposed in a state of being separated from the insert member on the inner side of the pipe in the insertion direction and has an outer diameter dimension substantially corresponding to the inner diameter dimension of the pipe to be bent. And, which are thinner than the inner diameter of the bent pipe, and are bendably connected by a connecting member that is longer than the pipe axial direction length on the pipe inner peripheral side at the center of curvature of the pipe axis in the bent portion of the bent pipe, and , A moving means for forcibly moving the correction member to the insertion member side Further, in the bending die, an arcuate guide surface that is located outside the pipe on the side of the center of curvature of the pipe axis in the bent portion of the bent pipe and is formed concentrically with the curvature circle of the pipe axis of the bent portion. It is characterized by the provision of.

The connecting member may be a chain member, a flexible member, or a rigid member in which an inserting member and a correcting member are swingably coupled to the connecting member. To be

[Work]

When performing pipe bending using the pipe bending machine with the above configuration,
The bending pipe is bent and deformed while the insertion member and the correction member separated from each other are positioned inside the bending pipe as a core metal. After that, the straightening member is straightened to the insertion member side to straighten the bent pipe after the bending deformation, thereby completing the pipe bending process.

When performing pipe bending in this way, at the stage of causing bending deformation in the pipe to be bent, only the insert member and the correction member, which are separated from each other, are arranged as the core metal in the pipe to be bent, and between the members. There is nothing that keeps the shape of the bent pipe from the inside. Therefore, the bent pipe is deformed such that the outside of the bent portion and the inside of the bent portion approach each other. Then, the bent pipe subjected to the above-mentioned deformation is later corrected by a correction member to have a desired bent pipe shape.

By the way, tensile stress is applied to the outside of the bent portion of the bent pipe that has been bent and deformed, while compressive stress is applied to the inside of the bent portion. And, there is a neutral point where neither tensile stress nor compressive stress acts on the boundary between the two parts, but the position of the neutral point caused the above deformation by using the pipe bending machine of the present invention. In this case, the state is more inward than the conventional one.

〔The invention's effect〕

Therefore, the region where the compressive stress acts on the inside of the bent portion becomes smaller and the compressive stress itself also becomes smaller. As a result, the conventional wrinkle-like defect is generated. Moreover, since the bent pipe that has been deformed as described above is straightened later by the straightening member, it is possible to prevent the final bent pipe shape from becoming an inappropriate shape.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows a bending action part of a pipe bending machine according to the present invention in a plan view, and a bending work surface is brought into contact with the work surface of a bending die (1) formed on an outer peripheral portion. A straight bending pipe (3) is brought into contact with a bending die (1) by a clamping die (2) which can be moved closer to and away from the bending die (1), so that the bending pipe (3) is pressed. , (2) are held and fixed, and the pressure die (6) which is relatively rotated with respect to the bending die (1) with its center of curvature as an axis is positioned on the same side as the tightening die to be held and fixed. While being pressed against the straight bendable pipe (3), the relative rotation with respect to the bending die (1) allows the bending die (3) to slidably contact the pressure die (6). The bent pipe (3) is configured to be bent along the processing surface of the bending die (1). The bending die (1) is provided with an arcuate guide surface (1a) located outside the tube on the curvature center side of the bendable tube axis and concentric with the bend circle of the bendable tube axis.

Further, in the present invention, as shown in FIG. 2, the core metal (4) arranged in the bent pipe (3) in the process of causing bending deformation has an outer diameter dimension of the bent pipe (3). ), And an insertion member (4a) having a cylindrical peripheral surface which is movable in the insertion / removal direction along the axial direction of the bent pipe (3),
The straightening member (4b) is arranged in a state of being separated from the insertion member (4a) and has a substantially spherical outer diameter corresponding to the inner diameter of the bent pipe (3).

The insertion member (4a) and the correction member (4b) are flexibly connected by a connecting member (5) made of a chain (51). The chain-like body (51) forming this connecting member (5) is
It is smaller than the inner diameter of the bendable tube and longer than the length of the bent portion of the bendable tube on the inner circumference side of the tube on the center side of the curvature in the tube axis direction. Furthermore, after the bending deformation is generated, the insertion member (4a) is pulled toward the tip side of the bent pipe (3) in order to forcibly move the correction member (4b) to the insertion member (4a) side. It is configured.

When pipe bending is performed using the pipe bending machine having such a configuration, the insertion member (4a) and the correction member (4b) which are separated from each other.
Is positioned in the pipe to be bent (3) as a core metal (4), and after causing bending deformation in the pipe to be bent (3), the correction member (4b) is moved to the insertion member (4a) side. The pipe to be bent (3) after the bending deformation is forcibly moved to be straightened to complete the pipe bending process. The straightening of the bendable pipe (3) may be performed after the step of causing the deformation is completely completed, or may be slightly delayed while the step of causing the deformation is in progress. .

Thus, when the pipe bending process is performed, the bendable pipe (3) is deformed such that the outside of the bent portion and the inside of the bent portion come close to each other at the stage of causing the deformation of the bent pipe (3). The cross-sectional shape is as shown. At this stage, the neutral position (3
In the case of a), it is more inwardly displaced than in the past. The bent pipe (3) which has undergone the above-mentioned deformation is later corrected by the correction member (4b) to have a desired pipe cross-sectional shape as shown in FIG.

[Another embodiment]

In the embodiment described above, the connecting member (5) for connecting the insertion member (4a) and the correction member (4b) in a bendable manner is composed of the chain body (51). (5) may be composed of a flexible body (52) as shown in FIG. Further, as shown in FIG. 6, the connecting member (5) is composed of a rigid body (53), and the inserting member (4a) and the correcting member (4b) can be freely attached to the connecting member (5). The joints (54), (54) and the like may be used so that they can be swung.

Further, while holding the pipe to be bent (3) with the clamping die (2) and the bending die (1) shown in FIG. 1, the clamping die (2) is rotated together with the bending die (1) to bend the pipe to be bent. The present invention can be applied even to a pipe bending machine configured to perform the bending process of (3).

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

1 to 6 show an embodiment of a pipe bending machine according to the present invention, FIG. 1 is a schematic plan view showing a main part (state before bending deformation), and FIG. 2 shows a main part. Schematic cross-sectional view (state after bending deformation), FIG. 3 is a cross-sectional view of the bent portion before straightening, FIG. 4 is a cross-sectional view of the bent portion after straightening, and FIGS. 5 and 6 are different. It is a schematic sectional drawing which shows an Example. 7 and 8 are schematic sectional views showing a conventional example. (1) …… Bending die. (1a) ... Arc guide surface, (2) ...
… Tightening type, (3) …… Bendable tube, (4) …… Core bar,
(4a) …… Insert member, (4b) …… Correcting member, (5) ……
Coupling member, (51) …… chain, (52) …… flexible body, (5
3) ... Rigid body.

Claims (4)

[Claims] 1. A bendable pipe (3) located between a bending die (1) and a clamping die (2), wherein a cored bar (4) is placed in the pipe, and the circumference of the bending die (1). A pipe bending machine having a mechanism for bending along a surface, wherein the core metal (4) has an outer diameter corresponding to an inner diameter of the bent pipe (3) and the bent pipe (3). An insertion member (4a) having a cylindrical peripheral surface that is inserted and removed along the axial direction of, and is arranged in a state of being separated from the insertion member (4a) on the inner side of the pipe in the insertion direction and having an outer diameter dimension as described above. It is composed of a substantially spherical correction member (4b) corresponding to the inner diameter of the bent pipe (3), and the insertion member (4a) and the correction member (4b) are connected to each other by the inner diameter of the bent pipe (3). A connecting member (5) which is thinner than the inner peripheral side of the pipe on the curvature center side of the pipe axis at the bent portion of the bent pipe (3) and which is longer than the length in the pipe axial direction. The bending member (1) is connected to the bending member (1) and is provided with a moving unit for forcibly moving the correction member (4b) to the insertion member (4a) side. Located outside the pipe on the side of the center of curvature of the pipe axis in the bent part of
A pipe bending machine provided with an arcuate guide surface (1a) formed concentrically with a circle of curvature of a pipe axis of a bent portion. 2. The pipe bending machine according to claim 1, wherein the connecting member (5) is composed of a chain body (51). 3. The pipe bending machine according to claim 1, wherein the connecting member (5) comprises a flexible body (52). 4. The connecting member (5) is made of a rigid body (53), and the inserting member (4a) and the correcting member (4b) are swingably connected to the connecting member (5). The pipe bending machine according to claim 1.