JPS6328692B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for bending a metal strip with a large bending radius or bending it to form an arbitrary curve.

[Conventional technology]

When bending metal strips, a widely used device is to pass the metal strip to be bent through a narrow heating device such as a high-frequency inductor that can heat the material at high temperatures. Alternatively, an appropriate point in the middle is clamped to a bending arm that is rotatable and conforms to the bending radius, and the strip is continuously and straightly propelled while being heated by the heating device and immediately cooled to a predetermined temperature. There is a hot bending device that applies a bending moment to the strip and causes it to undergo continuous plastic deformation in its heating zone.

[Problem that the invention seeks to solve]

This device has the advantage of being able to efficiently bend metal strips, but it is extremely difficult to bend with a large bending radius of several tens of meters, which is not equal to the length of the bending arm. In the past, bending arms with the same length were specially prepared and bent for bending radii of 20 to 30 meters, but when the bending radius exceeded that length,
It is now almost impossible to bend with the above device, and the only option is to use push rolls instead of bending arms. However, this method has the disadvantage that a large flattening phenomenon occurs in the bent portion of the metal strip, and as a result, it is difficult to control the bending radius. Therefore, it would be extremely useful if the hot bending apparatus could be modified so that it could bend metal strips with a large bending radius or bend them to form arbitrary curves.

[Means for solving problems]

The present invention was made against the background of the above-mentioned circumstances, and consists of a device that continuously and straightly propels a metal strip to be bent, and a device that propels the propelled strip in a narrow width and at a high temperature. A hot heating device that is equipped with an annular heating device that heats the strip and cools it immediately after heating, and a rotatable bending arm that clamps the tip or intermediate portion of the strip and guides the strip in the bending direction. In the bending device, a swing boom is provided that is swingable about a pivot at a fixed position in a plane parallel to the plane of rotation of the bending arm, and the center of rotation of the bending arm is mounted on the boom so that the center of rotation of the bending arm can be moved. , the center of rotation of the bending arm is moved along the swing boom at a speed at which the ratio of the propulsion speed v ₁ of the metal strip to be bent and the rotational speed ω of the bending arm is maintained at a predetermined value. It is characterized by the following.

[Effect]

That is, the present invention enables bending by appropriately displacing or allowing the center of rotation of the bending arm in the conventional hot bending device in the feeding direction X of the material and the direction Y perpendicular thereto within the rotation plane. This is for bending to an arbitrary radius that is different from the effective radius of the arm.In particular, to perform bending with a large radius of several tens of meters, the feed guide device of the existing hot bending machine is used. In addition, by adding a device that displaces the center of rotation of the bending arm in the X and Y directions, it is possible to perform perfect circular bending with a temporarily large bending radius as well as bending into arbitrary curved shapes. be.

〔Example〕

Next, an example of implementation of the present invention will be explained with reference to the drawings.

In Fig. 1, 1 is the metal pipe to be bent;
2 is a bent portion thereof; 3 is a rotatable bending arm that fixes the tip or an appropriate intermediate point of the raw pipe 1 and guides the raw pipe 1 in the bending direction; 4 is a feed guide device for the raw pipe 1; 5 6 is a guide roller, and 6 is a swinging boom that moves the center of rotation 7 of the bending arm 3 at a controlled speed v ₂ that is slower than the feed speed v ₁ of the strip 1 and swings around the pivot 8. The rotation center 7 of the arm 3 is controlled by a motor 10 so that a speed v ₂ is given by the chain 9, and the chain 9 is moved to the right by the thrust due to the feeding speed v ₁ of the raw pipe 1. This gives the center of rotation 7 of the bending arm 3 a velocity v ₂ which is slower than v ₁ against the tension. Although not shown, a worm reducer and a one-way clutch (the advantage is that a simple clutch such as a one-way clutch is sufficient) are provided between the motor 10 and the chain 9. When processing is finished,
It is returned to the right end at high speed by the motor 11 via the clutch. This clutch has play during forward rotation and operates only when reverse rotation. In addition, in the figure, H
is an annular heating device that heats the propelled metal tube 1 to a high temperature in a narrow width and cools it immediately after heating.

In general, a hot bending device moves a narrow heating zone relatively in the longitudinal direction of the raw tube at a speed _v1 , and bends the heating zone at an angular speed ω.
The radius of curvature R is defined by the following formula.

R=v ₁ /ω...(1) To be more precise, the length of the raw pipe before and after bending is slightly different, but this difference can be ignored at large bending radii, so There is no problem if formula (1) is left as is.

In the present invention, the bending radius R is increased by keeping the feeding speed v ₁ of the blank pipe constant and adjusting the moving speed v ₂ of the rotation center 7 of the bending arm 3 to reduce the angular velocity ω. .

That is, in Fig. 1, if v ₁ = v ₂ , no bending will occur, R will be infinite, and v ₂ = v 2.
It is clear that if it is set to 0, then R becomes approximately equal to the effective radius of bending arm 3, and if v ₂ is chosen to be a certain value between v ₁ and 0, R becomes infinite and the effective radius of bending arm 3 It is easy to imagine that it may be a certain value between the radius and the radius.

Next, the principle for determining the R will be explained with reference to the diagram shown in FIG.

It should be noted here that in conventional hot bending devices, the center of rotation of the bending arm is always within the plane affected by the heating device, but in the present invention, the center of rotation of the bending arm is always within the plane affected by the heating device. This is not necessary even at the start of bending. Originally, the principle of the device of the present invention is that the bending radius R is given by equation (1), and by calculating v ₁ /v ₂ corresponding to the geometric configuration of the device, the bending radius R is given by equation (1). The purpose is to programmatically control the radius R, so that the bending arm 3
The starting point of the center of rotation 7 may be located anywhere on the XX plane.

The method of programming the value of v ₁ /v ₂ in accordance with the geometric configuration of the device of the present invention will be described as follows.

Figure 2 is a diagram showing the equivalent mechanism in one-to-one correspondence with each part in Figure 1. The solid line indicates the position at which the bending starts, and the dotted line indicates the state where the bending has progressed by an angle θ. As shown, the bending arm 3 has been moved to 3', the boom 6 has been moved to 6', and the center of rotation 7 of the bending arm 3 has been moved to 7'.

In this case, the bending is a perfect circle, and the center point of the bending is a virtual point far away from the device, which is set to 0.

The bent portion 2 of the raw pipe 1 becomes a curved pipe, its length is AB, and ∠AOB=θ.

To simplify the explanation, the swing boom 6 is parallel to the raw pipe 1 at the start, the perpendicular line drawn to the raw pipe 1 at the heating center of the heating device H is designated as AO, and the intersection of AO and the center line of the swing boom 6 is designated as AO. C
, AO=R, AC=l, C-7=m.
Therefore, point C moves to point D after ∠θ bending, and BD
=l, D-7=m. Also, the center of rotation of the swing boom 6 is its pivot point 8, which is naturally to the left of point C, and C-8=
Let it be n.

Assuming that the center 7 moves to 7' while the raw tube 1 is fed a distance AB, and that distance is L,
The moving speed v ₂ of the center 7 is expressed by the following formula.

v ₂ = dL/dt = dL/dθ・dθ/dt ...(2) Here, the origin is the rotation center 8 of the swing boom 6, and consists of the X axis parallel to the raw pipe 1 and the Y axis perpendicular to it. Set coordinates.

Here, if the coordinates of point D are Dx, Dy, then Dx=n+(R-l)sinθ Dy=(R-l)(1-cosθ), and the coordinates of point 7' are 7'x, 7' If y, 7'x=Dx+m cosθ=n+(R-l)sinθ+m co
sθ 7′y=Dy+m sinθ=(R-l)(1-cosθ)+m
becomes sinθ. Therefore, the distances 8-7' and L are respectively 8-7'=√7' ² +7' ² =√{+(-)
+ } ² + {(-) (1-
)+ } ² 8−7′=√7′ ² +7′ ² =√{+(−)
+ } ² + {(-) (1-
)+ } ² L=√{+(-)+ } ² +
{(-)(1-)+} ² ...(3)
becomes.

Therefore, dL/dθ is obtained by differentiating equation (3) with respect to θ, and dθ/dt is given by dθ/dt=v ₁ /R by differentiating Rθ=v ₁ t, so v ₁ /v ₂ =v ₁ /dL/dθ・V ₁ /R, that is, v ₁ /v ₂ =R/dL/d
θ...(4) becomes.

Since the formula for dL/dθ is complicated, its description is omitted, but the program of v ₁ /v ₂ is determined by formulas (4) and (3).

Note that the bending radius R is very large and θ is approximately
When the angle is less than 10°, the formula (4) is simplified and the following equation is obtained: v ₁ /v ₂ ≒R/R-l (4') The reason for this will be explained with reference to FIG.

In Figure 3, CD≒7-7' AB/CD=R/R-l v ₁ Δt=AB, v ₂ Δt≒CD, so AB/CD≒v ₁ Δt/v ₂ Δt=v ₁ /v ₂ , Therefore, equation (4') holds true.

Note that in implementation, v ₂ /v ₁ may be used.

Therefore, the accuracy of the bending radius R can be determined by examining the ratio of a certain bending angle Δθ per a certain feed length ΔAB from the relationship R=AB/θ=ΔAB/Δt/Δθ/Δt=ΔAB/Δθ. Highly accurate bending can be performed by slightly adjusting v ₂ /v ₁ as necessary. In addition, if it is difficult for the swing boom to rotate, it is of course possible to add auxiliary power and make it swing.

It is possible to argue.

As described above, the present invention performs bending with an arbitrary large bending radius that differs from the length of the bending arm, and the method for bending with an arbitrary bending radius that differs from the length of the bending arm is described in the application filed by the present applicant. Related Japanese Patent Application Publication No. 1973
-83670, but the present invention is not included in this prior art because the device configuration is different. This is because the present invention makes it possible to easily carry out bending with a large bending radius by temporarily renovating a conventionally known existing hot bending device.

〔Effect of the invention〕

According to the present invention, bending with a bending radius of several tens of meters, which conventionally had no choice but to use push rolls, can be performed by utilizing the feed guide device of a conventionally known hot bending device, and by using the feed guide device of a conventionally known hot bending device, and Not only can this be made possible by adding a device that gives or allows an appropriate displacement in the feeding direction X of the material and the direction Y perpendicular to it, but also bending with an arbitrary bending radius different from the length of the bending arm or any arbitrary curve. Since it is also possible to bend shapes, it is suitable as a hot bending device.

[Brief explanation of drawings]

Fig. 1 is a plan view of the device of the present invention, Fig. 2 is a diagram showing the device of Fig. 1, and Fig. 3 is a plan view of the device of the present invention.
It is an explanatory diagram in the case of 10 degrees or less. DESCRIPTION OF SYMBOLS 1...Made pipe, 2...Bent part of the stock pipe, 3...Bending arm, 4...Feed guide device, 5...Guide roller, 6...
Swing boom, 7... Center of rotation of the bending arm.

Claims (1)

[Claims] 1. A device for continuously and straightly propelling a metal strip to be bent; an annular heating device for heating the propelled strip to a high temperature in a narrow width and cooling it immediately after heating; In a hot bending device equipped with a rotatable bending arm that clamps the tip or intermediate portion of a strip and guides the strip in the bending direction, A swing boom is provided that can swing around a pivot, and the rotation center of the bending arm is movably mounted on this boom, and the propulsion speed v ₁ of the metal strip to be bent and the rotation of the bending arm are fixed. speed ω
A hot bending apparatus characterized in that the center of rotation of the bending arm is moved along the swing boom at a speed such that a ratio between the bending arm and the bending arm is maintained at a predetermined value.