JPS62192214A - Pipe bending machine - Google Patents

Abstract

PURPOSE:To form a straight pipe in good-shaped bent pipe by straightening a pipe bend deformation part without any defect, by inserting the insertion member that almost equal outer diameter correction member is linked with a fine linking member into the straight pipe inner hole which is restrained to a bending die and by drawing out the insertion member after the pipe bend. CONSTITUTION:A straight pipe 3 is fastened to a bending die 1 and bound with a die 2. The core metal 4 composed of the insertion member 4a that the straightening member 4b of the globular body, etc., having the outer diameter about equal to the inner diameter of the straight pipe 3 is inserted into the inner hole of the straight pipe 3. The straight pipe 3 is bent in the prescribed curvature by pulling around a pressure die 6 along the bending die 1 curved face. Thereafter, the straightening member 4b is pulled out by drawing the insertion member 4a to form the pipe material deformed inner part in the circular inner hole having no such defect as wrinkle, etc. This chain 5 may be formed in a flexible body or oscillatable rigid body.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention provides a method for bending a pipe located between a bending die and a clamping die, by positioning a core metal inside the pipe and bending the pipe around the bending die. The present invention relates to a pipe bending machine having a mechanism for bending along a surface.

[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 during bending so that the outside of the bent part approaches the inside of the bent part, resulting in the final pipe shape. This is to prevent the shape from becoming an inappropriate shape that is significantly different from the shape before bending.

In conventional pipe bending machines, the following metal core is positioned inside the pipe to be bent.

That is, as shown in FIG.
The insertion member (41a) has a substantially spherical shape whose outer diameter corresponds to the inner diameter of the tube to be bent (3) and is movable along the axial direction of the tube to be bent (3). Element(
41b) coupled in a swingable manner, or, as shown in FIG. 8, a plurality of (three in the figure) correction members (41b) for the insertion member (41a). A core metal (41) was used in which the beads were directly connected in the form of beads.

[Problem that the invention seeks to solve]

When using a conventional pipe bending machine that bends the core metal (41) while positioning it inside the pipe to be bent (3), the pipe to be bent (3) is bent when the core metal (41) is bent. Due to the presence of the bending part, the outside of the bent part and the inside of the bent part are hardly deformed so that they become close to each other, and it is possible to prevent the final pipe shape from becoming inappropriate. There is a problem in that wrinkle-like defects occur due to large compressive stress acting on the inside of the bent portion.

SUMMARY OF THE INVENTION An object of the present invention is to provide a tube bending machine that can solve these problems and also prevent the final tube shape from becoming inappropriate as in conventional tube bending machines.

[Means for solving problems]

The pipe bending machine according to the present invention has a mechanism for bending a pipe to be bent located between a bending die and a clamping die along the circumferential surface of the bending die while positioning a core metal inside the pipe. In the pipe bending machine, the core metal is connected to an insertion member whose outer diameter corresponds to the inner diameter of the pipe to be bent and which is movable along the axial direction of the pipe to be bent, and to the insertion member. a substantially spherical correction member that is spaced apart from each other and has an outer diameter corresponding to the inner diameter of the tube to be bent, and connects the insertion member and the correction member to a connecting member that is thinner than the tube to be bent. The present invention is characterized in that the correction member is connected in a bendable manner and further includes a moving means for forcibly moving the correction member toward the insertion member.

The connecting member may be made of a chain-like body, a flexible body, or a rigid body with an insertion member and a correction member swingably connected to the connecting member. It will be done.

[For production]

When bending a pipe using a pipe bending machine having such a configuration, the insertion member and the straightening member separated from each other are positioned in the pipe to be bent as a core metal, and then the pipe to be bent is bent. , the straightening member is moved toward the insertion member to straighten the bent pipe after the bending deformation, and the pipe bending process is completed.

In this way, when bending a pipe, at the stage of causing bending deformation in the pipe to be bent, only the insertion member and the straightening member spaced apart from each other are placed in the pipe to be bent, and the pipe to be bent is placed between these two members. Since there is nothing to maintain the shape from the inside, the pipe to be bent undergoes deformation such that the outside of the bent portion approaches the inside of the bent portion. Then, the bent tube that has undergone the above deformation is later corrected by a straightening member into a desired tube shape.

By the way, the outer side of the bent portion of the pipe to be bent is in a state where tensile stress is applied, while the inner side of the bent portion is in a state where compressive stress is applied.

There is a neutral point at the boundary of the image area where neither tensile stress nor compressive stress is acting. In this case, it will be in a state where it is deviated more inward than before.

〔Effect of the invention〕

Therefore, the area on the inner side of the bent portion on which the compressive stress acts becomes smaller, and the compressive stress itself becomes smaller, so that the occurrence of wrinkle-like defects as in the conventional case can be suppressed. Furthermore, since the bent tube that has undergone the above-described deformation is later corrected by the straightening member, it is possible to prevent the final tube shape from becoming inappropriate.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 schematically shows a bending section of a pipe bending machine according to the present invention in plan view, with a bending surface formed on the outer periphery and facing the processing surface of a bending die (1). The straight pipe to be bent (3) can be fastened so that it can move toward and away from the bending mold (1) by pressing the mold (2) onto the pipe to be bent (3). 1), (2) are clamped and fixed, and the pressure mold (6), which rotates relative to the bending mold (1) around its center of curvature, is tightened on the same side as the mold (2). This pressure mold (
6), the pipe to be bent (3) is bent along the processing surface of the bending die (1). and,
In the present invention, as shown in FIG. 2, the core bar (4) placed inside the tube to be bent (3) in the process of causing bending deformation has an outer diameter that is smaller than that of the tube to be bent (3). an insertion member (4a) having an inner diameter size and movable along the axial direction of the tube to be bent (3); The insertion member (4a) and the correction member (4b) are connected by a chain body (51). They are connected in a flexible manner by a member (5). Furthermore, in order to forcibly move the correction member (4b) toward the insertion member (4a) after the bending deformation occurs, the insertion member (4a) is inserted into the bent pipe (3).
It is configured to be pulled toward the distal end.

When performing pipe bending using a pipe bending machine having such a configuration, the insertion member (4a) and the correction member (4b) are spaced apart from each other.
) is positioned as a core metal (4) in the tube to be bent (3), and after causing bending deformation in the tube to be bent (3), the correction member (4b) is placed on the side of the insertion member (4a). The bent pipe (3) is forcibly moved to correct the bent pipe (3) after the bending deformation, and the pipe bending process is completed. Note that the straightening of the bent pipe (3) may be performed after the step of causing the deformation is completely completed, or may be performed slightly later while the step of causing the deformation is in progress. good.

When bending a pipe in this way, at the stage where the pipe to be bent (3) is deformed, the pipe to be bent (3) undergoes deformation such that the outside of the bent part approaches the inside of the bent part, as shown in FIG. The cross-sectional shape will be as shown.

At this stage, the neutral point 1f (3a) is deviated more inward than before. Then, the bent pipe (3) which has undergone the above deformation is later corrected by a straightening member (4b) to have a desired pipe cross-sectional shape as shown in FIG.

[Another example]

In the above-mentioned embodiment, the connecting member (5) that connects the insertion member (4a) and the correction member (4b) in a flexible manner is composed of a chain-like body (51). (5) may consist of a flexible body (52) as shown in FIG. Further, the connecting member (5) is the sixth
As shown in the figure, it is composed of a rigid body (53), and the insertion member (4a) and the correction member (4b) are connected to the connecting member (5) by a universal joint (54).

(54) or the like may be used to swingably connect them.

Furthermore, the tightening shown in Fig. 1 is performed by rotating the die (2) together with the bending die (1) while holding the pipe (3) to be bent between the die (2) and the bending die (1). The present invention can be applied to a pipe bending machine configured to bend a pipe (3) to be bent.

[Brief explanation of drawings]

Figures 1 to 6 show an embodiment of the pipe bending machine according to the present invention, with Figure 1 being a schematic plan view showing the main parts (before bending deformation is applied), and Figure 2 showing the main parts. Schematic cross-sectional view (state after applying bending deformation), Figure 3 is a cross-sectional view of the pipe at the bent part before correction, Figure 4 is a cross-sectional view of the pipe at the bent part after correction, and Figures 5 and 6 are separate. It is a schematic sectional view showing an example. FIGS. 7 and 8 are schematic sectional views showing conventional examples. (1)...Bending mold. (2)...Tightening is done by mold, (3)...Bent pipe, (4)...
Core metal, (4a)...Insert member, (4b)...
... Correction member, (5) ... Connection member, (51
)... Chain body, (52)... Flexible body,
(53)...Rigid body.

Claims (1)

[Scope of Claims] [1] A pipe to be bent (3) located between a bending die (1) and a tightening die (2) is bent while a core metal (4) is positioned inside the pipe. In the pipe bending machine having a mechanism for bending along the circumferential surface of 1), the core bar (4) has an outer diameter corresponding to the inner diameter of the pipe to be bent (3) and a pipe to be bent. an insertion member (
4a), and a substantially spherical straightening member (4b) which is arranged in a spaced manner with respect to the insertion member (4a) and whose outer diameter corresponds to the inner diameter of the bent pipe (3), The insertion member (4a) and the correction member (4b) are bendably connected by a connection member (5) that is thinner than the tube to be bent (3), and the correction member (4b) is connected to the insertion member (4b). 4
A pipe bending machine equipped with a moving means for forcibly moving the pipe to the a) side. [2] The pipe bending machine according to claim 1, wherein the connecting member (5) is a chain body (51). [3] The tube bending machine according to claim 1, wherein the connecting member (5) is made of a flexible body (52). [4] The connecting member (5) is made of a rigid body (53), and the insertion member (4a) is connected to the connecting member (5).
) and the straightening member (4b) are coupled together in a swingable manner.