JP5286506B2 - Pipe bending machine - Google Patents

Description

The present invention relates to a pipe bending apparatus , and more particularly to a pipe bending apparatus by press bending.

About the bending method of pipe by press bending, as a means that can be processed by changing the bending radius for each part in one processing process, and can also handle tapered metal pipes and metal pipes with irregular cross-sectional shapes A technique is known in which a press die is divided into a plurality of pieces and set in a press machine, and the plurality of press dies are sequentially moved up and down or laterally moved to sequentially bend different portions in the pipe length direction. (Patent Documents 1 and 2).
JP 2003-236617 A JP 2004-098139 A

On the other hand, when bending a pipe by bending a press so that a single target bend angle, in the conventional method, once with a single mold bend with a radius commensurate with that single target bend angle The press bending process is performed.
However, in particular, in the press bending process using a high-strength steel pipe (that is, a steel pipe having a tensile strength of 780 MPa or more), not only the bending angle of the product after unloading but also the accuracy of the profile is required. The desired product shape may not be obtained by a single press bending. If a mold with an appropriate bending radius is set, the desired product shape may be obtained. However, if the material characteristics of the pipe vary widely, press bending a steel pipe with multiple material characteristics with a single mold. It is difficult.

  In addition, the upper and lower molds for hydroforming are used to sandwich the pipe and press-bend, and the hydroforming process is often performed as it is. However, it may be impossible to sandwich the upper and lower molds when the member is long. . If the bending accuracy is poor, biting by the mold occurs when it is put into a hydroforming mold, resulting in molding failure. Even if no biting occurs, there is material restraint due to inappropriately strong contact with the mold, and in hydroforming, breakage often occurs in the vicinity of the place where the restraint occurred.

As described above, the conventional press bending technique has a problem in that the accuracy of the product profile is not good when a high-strength steel pipe is processed into a single bending angle. An object of the present invention is to solve this problem and to provide a pipe bending apparatus capable of improving the accuracy of a product profile when a high-strength steel pipe is press-bended at a single bending angle.

The present invention made to achieve the above object is as follows .

1. A pipe bending apparatus that press-bends a pipe, which is a high-strength steel pipe, at a single bending angle, and reduces a shape error caused by a springback of the press-bended material, and the pipe is connected to two support points. A pipe support that can be rotated in the same plane with a point in the vicinity of each support point as a rotation center, and a pipe support holding base that holds the pipe support, and has a different predetermined R A mold holding pedestal capable of holding a plurality of dies at the press bending position of the pipe, and supporting the two mold holding pedestals and / or the pipe support holding pedestal in the plane of rotation of the pipe support One or more press bending drive means for moving a predetermined stroke along a vertical bisector connecting the lines connecting the points;
The mold holding pedestal fixedly holds a mold set in which the plurality of molds are arranged side by side, and the mold holding pedestal is moved in the side-by-side direction to move the mold set in the mold set. A mold switching means capable of switching the position of an arbitrary mold to the press bending execution position of the pipe;
2. The pipe bending apparatus according to claim 1, wherein the plurality of molds are used in later rounds, and the bending radius R is reduced and the caliber diameter is increased.

  According to the present invention, even when the characteristics of the material pipe vary, correction is easy and accuracy can be easily obtained by using a plurality of dies having different bending radii in a specific order. As a result, it is possible to prevent restraint due to improperly strong contact with the mold in hydroforming, and breakage associated therewith. Further, even in the case where there are a plurality of material strength levels (for example, 980 MPa class and 780 MPa class) due to the difference in the target vehicle type, it is possible to cope with the same member for an automobile.

FIG. 1 is a schematic side view showing an example of an embodiment of a press bending method using the present invention (apparatus) . In this example, there is shown a case where the pipe 10 is subjected to press bending a total of two times using two dies 1 and 2 having different Rs (R is a bending radius; the same applies hereinafter).
First, assuming that the pipe 10 is supported by the pipe support 3 arranged one by one at two support points separated by a distance L between the pipe support points, a mold with R = R ₁ (R ₁ mold) When 1 is raised from below the pipe 10, the mold 1 is arranged so as to first contact the center between the support points of the pipe 10 in the assumed state (FIG. 1A). Thereafter, the pipe 10 is placed on the mold 1, and the mold 1 is raised by a predetermined stroke to perform press bending (FIG. 1 (b)). Here, each pipe support 3 can be rotated in the same plane around a suitable point in the vicinity of each support point, and can support the pipe 10 in a slidable manner. It is also possible not to slide.

Next, instead of the R ₁ mold 1, when the mold (R ₂ mold) 2 of R = R ₂ (R ₂ <R ₁ ) is raised from below the pipe 10, the mold 2 is It arrange | positions so that it may contact the center part between the support points of the pipe 10 of the said assumption state first (FIG.1 (c)). Thereafter, the pipe 10 is transferred from the mold 1 to the mold 2, and the mold 2 is raised by a predetermined stroke to perform press bending (FIG. 1 (d)).
Thus, in the present invention, the R of the plurality of dies used sequentially is made smaller as it is used later. That is, in all press bending of N (N ≧ 2) times, the R of the mold used for the Ith (I ≦ N) times is made smaller than the R of the mold used for the I-1th time (example of FIG. 1). Then, R ₁ > R ₂ ). Here, for a predetermined stroke set for each mold, an appropriate value corresponding to the R of the mold to be used is determined by a preliminary experiment or the like.

As a result, even when the pipe is a high-strength steel pipe, it is possible to reduce the shape error caused by the springback of the material when press-bending so as to have a single target bending angle, and the product profile after unloading Accuracy can be improved.
The mold used in the present invention preferably has a caliber having a semicircular cross section, for example, as shown in the AA cross section of FIG. The diameter of this semicircle is referred to as the caliber diameter and is represented by the symbol D. In that case, from the viewpoint that the pipe cross-section is flattened by press bending and the pipe diameter in the direction perpendicular to the longitudinal section of the caliber is increased, it is preferable that the die D used is made larger as it is used later.

The present invention (apparatus) is a pipe bending apparatus for executing the above-described press bending method . This device supports a pipe at two support points, and supports a pipe support that can be rotated in the same plane around a suitable point in the vicinity of each support point, and a pipe support holding the pipe support A pedestal, a mold holding pedestal capable of holding a plurality of dies having different predetermined R's at the press bending execution position of the pipe, and supporting the mold holding pedestal and / or the pipe supporter holding pedestal with the pipe What is necessary is just to have one or more press-bending driving means for moving a predetermined stroke along a perpendicular bisector connecting the two support points within the rotation plane of the child.

In the present invention (apparatus), preferably, the mold holding base holds a mold set in which the plurality of molds are arranged side by side, and the mold holding bases are arranged side by side. It has a mold switching means that can be moved in the direction to switch the position of an arbitrary mold in the mold set to the press bending execution position of the pipe.
FIG. 2A is a front view and FIG. 2B is a side view showing an example of the present invention (apparatus).

In this example, the pipe 10 is supported by two support points, and a pipe support 3 that can be rotated in the same plane around a suitable point in the vicinity of each support point, and a pipe that holds the pipe support 3. The support holding base 4 and two molds (R ₁ mold, R ₂ mold) 1 and ₂ where R is R ₁ and R ₂ (R ₁ > R ₂ ), respectively, are used for the press bending execution position of the pipe. And a mold holding pedestal 5 that can be held. Further, as a press bending driving means, the mold holding pedestal 5 is in the direction indicated by the arrow at a predetermined stroke along a perpendicular bisector connecting the two support points in the plane of rotation of the pipe support 3. It has a die pushing cylinder 7 that moves (up or down) 12 (up and down direction).

The mold holding base 5 holds a mold set in which two molds 1 and 2 are arranged side by side. Further, as a mold switching means, the mold holding base 5 is moved in the side-by-side direction (arrow direction 11) to switch the position of any mold in the mold set to the press bending execution position of the pipe. It has a die switching cylinder 6 that is possible.
An example of the execution procedure of the present invention (method) using the apparatus of FIG. 2 is shown below.
(1.1) The mold 1 is moved to the press bending position by the mold switching cylinder 6. At this time, the position in the height direction of the mold holding base 5 is set to a predetermined standby position. Therefore, the pipe 10 is placed on the mold 1.

(1.2) The mold holding pedestal 5 is raised to the height position (press bending start position) at which the pipe support 3 starts to contact the pipe 10 by the mold pushing cylinder 7.
(1.3) The die holding base 5 is further raised by the die pushing cylinder 7 and the die 1 is pushed into the pipe 10 side by the stroke set for the first press bending (first press bending).
(1.4) The mold holding base 5 is lowered by the mold pushing cylinder 7 and returned to the standby position.

(1.5) The die 2 is moved to the press bending execution position by the die changing cylinder 6. Therefore, the pipe 10 is transferred from the mold 1 to the mold 2.
(1.6) The mold holding pedestal 5 is raised to the height position (press bending start position) at which the pipe support 3 starts to contact the pipe 10 by the mold pushing cylinder 7.
(1.7) The die holding base 5 is further raised by the die pushing cylinder 7 and the die 2 is pushed into the pipe 10 side by the stroke set for the second press bending (: second press bending).

(1.8) The mold holding base 5 is lowered with the mold pushing cylinder 7 and returned to the standby position, and the pipe 10 is taken out.
FIG. 3A is a front view and FIG. 3B is a side view showing another example of the present invention (apparatus).
In this example, in the example of FIG. 2, instead of the mold pushing cylinder 7, the pipe support holding pedestal 4 is used as the press bending driving means in the plane of rotation of the pipe support 3. It has a pipe support holding base pushing cylinder 8 that moves (up or down) in a direction indicated by an arrow (vertical direction) 13 with a predetermined stroke along a vertical bisector connecting the lines.

An example of the execution procedure of the press bending method using the apparatus of FIG. 3 is shown below.
(2.1) The die 1 is moved to the press bending position by the die switching cylinder 6. At this time, the height direction position of the pipe support holding base 4 is set to a predetermined standby position. Therefore, the pipe 10 is placed on the mold 1.
(2.2) The pipe support holding base 4 is lowered by the pipe support holding base pushing cylinder 8 to a height position where the pipe support 3 starts to contact the pipe 10 (press bending start position).

(2.3) Pipe support holder holding base pushing cylinder 8 is further lowered by pipe support holder holding base pushing cylinder 8 and pipe support 3 is pushed into pipe 10 side by the stroke set for the first press bending (first time) Press bending).
(2.4) The pipe support holding base 4 is raised by the pipe support holding base pushing cylinder 8 and returned to the standby position.

(2.5) The die 2 is moved to the press bending position by the die switching cylinder 6. Therefore, the pipe 10 is transferred from the mold 1 to the mold 2.
(2.6) The pipe support holding base 4 is lowered by the pipe support holding base pushing cylinder 8 to a height position where the pipe support 3 starts to contact the pipe 10 (press bending start position).
(2.7) Pipe support holder pedestal pushing cylinder 8 lowers pipe support holder pedestal 4 further and pushes pipe support 3 toward pipe 10 by the stroke set for the second press bending (: 2nd time) Press bending).

(2.8) The pipe support holding base 4 is raised by the pipe support holding base pushing cylinder 8 and returned to the standby position, and the pipe 10 is taken out.
The present invention (apparatus) is not limited to the examples shown in FIGS. 1 and 2, and the mold set may be a side-by-side arrangement of three or more molds having different Rs, and the press bending driving means. As an example, both the mold pushing cylinder 7 and the pipe support holding base pushing cylinder 8 may be provided.

  A straight steel pipe having a tensile strength of 980 MPa class, an outer diameter of 70 mm, and a wall thickness of 2.6 mm is used as a base pipe. The target shape of the product is a bending angle of 35 degrees and the bending portion (between the pipe support points) has an R of 1000 mm. It was made into a pipe shape, and press bending was performed in two forms described below as an invention example and a comparative example. As a press bending apparatus, the apparatus of FIG. 2 was used, and the distance L between pipe support points was set to 1040 mm.

  In both the inventive example and the comparative example, the quality of the bent shape of the product after unloading was determined using an inspection mold. In this inspection mold, the target pipe shape of the product is marked on a horizontal surface plate, and the length of the figure obtained by adding a margin corresponding to a predetermined accuracy range (here +0.5 mm) to the width of the figure that has been scribed. A vertical wall was erected on the direction outline. If the product can be put into this inspection mold (between two opposing vertical walls), it is acceptable.

(Invention example)
In the form shown in FIG. 1, the mold 1 (R = 900 mm, D = 70 mm) and the mold 2 (R = 400 mm, D = 72 mm) are used in this order, the stroke of the mold 1 is 135 mm, The stroke was 34.5 mm (these stroke values are the optimum values in the two-time press bending obtained in the preliminary experiment), and the press bending was performed twice in total.

The product pipe after unloading was sufficiently close to the target value for both the bending angle and the bending portion R, and was successfully passed into the inspection mold without any problem.
(Comparative example)
Using only the mold 1 (R and D are the same as the invention example), the stroke is 144 mm (this stroke value is the optimum value for the one-time press bending obtained in the preliminary experiment), and the press bending is performed once. It was.

  Although the bending angle of the product pipe after unloading was the same as the target value, the bent portion R was too far from the target value, so it could not be put into the inspection mold and was rejected.

It is a side surface schematic diagram which shows one example of embodiment of the press bending method using this invention (apparatus) . It is (a) front view and (b) side view which show one example (die pressing type) of this invention (apparatus). It is (a) front view and (b) side view which show another example (pipe support pushing type) of this invention (apparatus).

Explanation of symbols

1 Mold (R ₁ mold)
2 Mold (R ₂ mold)
3 Pipe support 4 Pipe support holding base 5 Mold holding base 6 Mold switching cylinder (die switching means)
7 Die pushing cylinder (press bending drive means)
8 Pipe support holder pedestal pushing cylinder (press bending drive means)
10 pipe (high-strength steel pipe)
11,12,13 Arrow direction

Claims (1)

A pipe bending apparatus that press-bends a pipe, which is a high-strength steel pipe, at a single bending angle, and reduces a shape error caused by a springback of the press-bended material, and the pipe is connected to two support points. A pipe support that can be rotated in the same plane with a point in the vicinity of each support point as a rotation center, and a pipe support holding base that holds the pipe support, and has a different predetermined R A mold holding pedestal capable of holding a plurality of dies at the press bending position of the pipe, and supporting the two mold holding pedestals and / or the pipe support holding pedestal in the plane of rotation of the pipe support One or more press bending drive means for moving a predetermined stroke along a vertical bisector connecting the lines connecting the points;
The mold holding pedestal fixedly holds a mold set in which the plurality of molds are arranged side by side, and the mold holding pedestal is moved in the side-by-side direction to move the mold set in the mold set. A mold switching means capable of switching the position of an arbitrary mold to the press bending execution position of the pipe;
2. The pipe bending apparatus according to claim 1, wherein the plurality of molds are used in later rounds, and the bending radius R is reduced and the caliber diameter is increased.

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