JPH04220120A - Method for bending pipe in minimum radius of curvature - Google Patents

Abstract

PURPOSE:To keep a circular sectional shape without generating collapse of a bent part in spite of bending a pipe to right angles in a radius smaller than the diameter of the pipe. e.g. in a radius of the minimum curvature smaller than about 1.0DR. CONSTITUTION:The tip part of the work is pressed and held by a clamping die to a bending die 2, held in the pipe grooves of the bending die 2 and the clamping die, the rear end part of the work is pressed by the operation of a pipe pressurizing cylinder of a booster device, the bending die 2 is turned to bend the bent part of the work so that it draws an arc of 90 deg., in such a bending time the work is bent as it slides and moves forward in the clamp part composed of the bending die 2 and the clamping die.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides a pipe with a diameter of approximately 1.0 DR.
This invention relates to a method of bending a pipe to a minimum radius of curvature as described below.

0002

[Prior Art] Conventionally, bending was performed by pressing and holding the tip of a workpiece against a bending die using a clamp die, but in this bending method, the workpiece was bent at a radius larger than the diameter of the pipe (approximately 2.0 DR). When machining, it can be sufficiently machined, but conversely, if the radius is smaller than the diameter of the pipe, for example about 1.
When bending to a minimum radius of curvature of 0DR or less, the tip of the workpiece slides backwards while the bending die rotates, making it impossible to maintain the circular cross-sectional shape of the bent part, resulting in the workpiece being crushed. .

On the other hand, a bending method has been used in which two pipes are cut at 45 degrees and the cut surfaces are joined by welding, but since the bent part is a right-angled joint, the liquid (oil) passing through the pipe , water, etc.), gas (cooler gas, etc.),
This method has disadvantages in that pressure loss occurs, the inner surface of the pipe is abraded, the wall thickness of the pipe is thinned, and liquid and gas leak, and this phenomenon occurs particularly at welded parts.

[0004] Therefore, by increasing the pressing force of the clamp type,
Bending is now performed by holding the tip of the workpiece in a bending die, and although this bending method is somewhat improved compared to the former method, the relationship between forces still remains, as shown in Figure 3. This has the disadvantage that the outside of the bent part stretches while the inside shrinks, causing the bent part to collapse.The bent workpiece is then inserted into several types of core-shaped correction tools from both ends to restore the collapsed bent shape. As a result, the restoration work is more expensive than the bending work.
It had the disadvantage that the amount of work was about 0 times as much.

[0005] In the above-mentioned bending method, the above-mentioned drawbacks occur greatly depending on the material of the pipe, such as steel pipes and stainless steel pipes. Specifically, the cross-sectional deformation of the bent part is large and buckling occurs on the inner pipe wall. At the same time, the outer tube wall was broken.

[0006] With the first method, bending is almost impossible, and although bending is possible with the second method, it requires a large number of steps and operations, so the third method is The front end of the workpiece is fixedly held (retained) in the bending die, and the rear end of the workpiece is pressed by a booster device. With this bending method, the crushing phenomenon caused by the force relationship at the bending part is somewhat eliminated. Although attempts were made to balance the pulling force with the bending mold and the pushing force with the booster device, the details are unknown, but during the actual bending process, as shown in Figure 4, the seat on the inner wall of the pipe It has the disadvantage that it has a large bend and still requires work to restore the collapse.

[0007] In addition, recent trends include the mechanical parts of automobile engine compartments and coolers, as well as various mechanical devices becoming more complex, requiring auxiliary equipment, and becoming smaller. As piping space decreases, its placement position is limited, and the number of cases in which pipes are bent at right angles along walls, for example, increases.As a result, pipes bent to an extremely small radius of curvature are used more frequently, and the bending process becomes more difficult. There is a growing demand for a simple method.

[0008]

[Problems to be Solved by the Invention] The present invention provides a method for bending a pipe at right angles to a radius smaller than the diameter of the pipe, for example, a minimum radius of curvature of about 1.0 DR or less, without causing the bent portion to collapse and maintain a circular cross-sectional shape. The present invention aims to provide a method for bending a pipe with an extremely small radius of curvature.

[0009]

[Means for Solving the Problems] The present invention is based on the above-mentioned conventional technology, in which it is impossible to bend a pipe to an extremely small radius of curvature, or it is necessary to restore the pipe to a circular cross-sectional shape. During the bending process by rotating the bending die, the workpiece slides forward in the clamp part to perform the bending process, so even if the pipe is bent at right angles to the minimum radius of curvature, the bent part will not collapse and the cross-sectional shape will be circular. This is an attempt to solve the above problem by maintaining the same.

0010

[Operation] In the present invention, when bending at right angles to a radius smaller than the diameter of the pipe, for example, a minimum radius of curvature of about 1.0 DR or less, the tip of the workpiece is pressed and gripped by the bending die with a clamp die. During bending, the rear end of the workpiece is pressed by a booster device and the bending die is rotated. During bending, the workpiece slides forward at the clamp part to perform the bending process, so that the bent part does not collapse and maintains a circular cross-sectional shape. It is.

[0011]

[Embodiment] An embodiment of the present invention will be described below based on the drawings. Reference numeral 1 is a pipe bender for bending a work W such as a pipe. A flexible bending die 2 is installed, and a semicircular pipe groove 3 is formed in the bending die 2. A clamp die 5 is installed at the base end 4 of the bending die 2. In addition to being equipped with a hydraulic cylinder (not shown), the pipe groove 6
is formed.

Reference numeral 7 denotes a wrinkle removing device installed inside the bending die 2 at the rear adjacent to the bending die 2. A pressure die 8 is slidably installed so as to face the wrinkle removing device 7, and the wrinkle removing device 7 and the pressure die There are pipe grooves 9, 9 on the inner surface of 8, respectively.
It forms a.

The pressure mold 8 is equipped with two hydraulic cylinders (not shown), one hydraulic cylinder presses the pressure mold 8 against the wrinkle removing device 7, and the other hydraulic cylinder presses the pressure mold 8 against the wrinkle removing device 7. The mold 8 is pressed so as to move in the axial direction of the workpiece W, and the wrinkle remover 7 corrects wrinkles etc. on the workpiece W before bending by pressing with the pressure mold 8.

Reference numeral 10 denotes a booster device installed at the rear of the bending die 2. The booster device 10 is placed on an extension of the workpiece W, and a pipe pressurizing tube 13 is attached to the tip of the rod 12 of the pipe pressurizing cylinder 11. At the same time, a stopper 14 for regulating the amount of movement of the rod 12 is also attached.

Reference numeral 15 denotes a core rod whose base end is fixed at a fixed position, and the core rod 15 is connected to the stopper 14, the pipe pressurizing cylinder 11, the rod 12, and the pipe pressurizing tube 13.
The tip of the core rod 15 has reached the bending start position of the bending mold 2 within the work W.

The pipe pressurizing cylinder 11 may not be placed on the extension of the workpiece W, but the pipe pressurizing tube 13 may be controlled to advance or retreat via a stay (not shown).

Next, a method of bending a workpiece W such as a pipe to an extremely small radius of curvature using the pipe bender 1 will be described.The tip of the workpiece W is pressed and held against the bending die 2 by the clamp die 5, The workpiece W is held in the pipe grooves 3 and 6 of the bending die 2 and the clamp die 5, and the rear end of the workpiece W is pressed by the operation of the pipe pressurizing cylinder 11 of the booster device 10, and the bending die 2 is rotated. The bending part S is bent to draw a 90 degree radius, and during the bending process, the workpiece W is
slides forward to perform the bending process.

For example, the clamping die 5 is used at a cylinder output of 70 kg, and the pipe pressure cylinder 11 of the booster device 10 is used at an output of 50 kg, and the workpiece W is pushed out by the pipe pressure cylinder 11 at the same time as the bending starts, and the clamp part C The bending process is performed while the workpiece W slides forward.

In the above action, the pressure is higher in the cylinder of the clamp die 5 that presses and grips, but during actual bending, the workpiece W moves in the axial direction, and the action of the conventional clamp die is a fixed grip ( In contrast to the state in which the workpiece W is not movable due to clamping, the action of the clamp die 5 of the present invention is to press and hold, and the workpiece W is movable.

[0020]The tip length L1 of the workpiece W, which was protruding forward from the clamp die 5 before the bending process started, becomes the post-processing tip length L2 after the bending process, and the relationship between the two lengths is L2>L1. The length L3 of the rear end of the workpiece W is adjusted by adjusting the amount of movement of the stopper 14.

By using such a bending method, bending can be performed with almost no cross-sectional deformation occurring at the bent portion S of the work W, and with almost no buckling of the inner tube wall of the work W.

In addition, in the bending process shown in FIG. 1, the rear end of the workpiece W before processing protrudes in a triangular shape on the outside corresponding to the bending part S, and this protrusion is pressed by the pipe pressurizing tube 13. During bending, the inner side of the bending portion S contracts while the outer side expands, so that the inner side escapes outward and in the axial direction, and after the bending process is completed, the rear end of the workpiece W becomes vertical.

Finally, to explain the dimensional relationship of the workpiece W that has been bent to an extremely small radius of curvature, taking a copper pipe workpiece W as shown in FIG. 2 as an example, the cross-sectional diameter D of the workpiece W is Φ20 (20mm ), bending radius R is 15mm
is expressed as Φ20×0.75DR, and a comparison between the conventional bending method and the bending method of the present invention will be illustrated below.

[0024] For steel, the conventional bending method is 2.0D.
The bending method of the present invention has a limit of R of 1.0.
DR is now possible, and 0.7 DR is now possible for copper pipes. For example, if the cross-sectional diameter D is Φ16, it is now possible to have a bending radius R of 11.2 mm.

[0025]

[Table 1]

[0026] In the above table, conventional method ① is a conventional bending method in which a clamp is used to fix the bending process. The bending method of the present invention involves grasping (holding) and pressing from the rear end, and the method of the present invention is a bending method in which the workpiece W is slid and moved while being held by a clamp and pressed from the rear end.

As for the material of the workpiece W, iron and copper are shown in the table above, and the copper is easier to process, and both materials can be processed by the method of the present invention.
Bending processing with an extremely small radius of curvature is possible, and in addition to the above-mentioned materials, there are also materials such as brass and aluminum.

[0028]

[Effects of the Invention] In short, the present invention provides a bending process in which the front end of the workpiece W is pressed and held against the bending die 2 by the clamp die 5, the rear end of the workpiece W is pressed by the booster device 10, and the bending die 2 is rotated. At the same time, the workpiece W slides forward at the clamp part C to perform the bending process, so the bending part S does not collapse, preventing the inner tube wall of the workpiece W from buckling and maintaining the circular cross-sectional shape. It can be bent with.

Therefore, it is not necessary to perform welding or restoration work as in the past, and the product can be manufactured as is by bending it once with the pipe bender 1, significantly reducing the number of steps, amount of work, and cost. Its practical effects are enormous, such as being able to reduce the amount of water used.

[Brief explanation of the drawing]

FIG. 1(A) is a plan view before the bending process by a pipe bender starts, and FIG. 1(B) is a plan view after the bending process is completed.

FIG. 2 is a plan view of a workpiece bent by the bending method of the present invention, and is an explanatory diagram of the relationship between the diameter of the workpiece and the bending radius.

FIG. 3 is a plan view of a conventional workpiece that is fixedly gripped (held) and bent by a bending die.

FIG. 4 is a plan view of a conventional workpiece that is fixedly gripped (held) by a bending die and bent by being pressed from the rear end of the workpiece.

[Explanation of symbols]

2 Bending mold 5 Clamp type 10 Booster device W Work C Clamp part C

Claims (1)

[Claims] Claim 1: During bending, the front end of the workpiece is pressed and gripped by a clamp die against the bending die, the rear end of the workpiece is pressed by a booster device, and the bending die is rotated. During bending, the workpiece slides forward in the clamp part. A method for bending a pipe with an extremely small radius of curvature, characterized in that the bending process is performed by bending the pipe with a minimum radius of curvature.