JPH0698404B2 - Bending method of pipe with minimum radius of curvature - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for bending a pipe having a minimum radius of curvature of about 1.0 DR or less.

[0002]

2. Description of the Related Art Conventionally, a bending work has been carried out by pressing and holding a tip end of a work into a bending mold by a clamp mold. In such a bending work method, a radius larger than a diameter of a pipe (about
When bending at 2.0DR), it can be processed sufficiently, but on the contrary, a radius smaller than the diameter of the pipe, for example, about 1.0
In the case of bending to a minimum radius of curvature equal to or less than DR, the tip of the work piece slides backward and moves backward during rotation of the bending die, and thus the circular cross section of the bending portion cannot be maintained, and there is a drawback of 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. However, since the bent portion is a right angle joint, a liquid (oil , Water, etc.), gas (cooler gas, etc.) resistance,
There has been a drawback that pressure loss occurs, the inner surface of the pipe is abraded to reduce the wall thickness of the pipe, and liquid and gas leak, and this phenomenon particularly occurs at the welded portion.

Therefore, by strengthening the pressing force of the clamp type,
The tip of the work is fixed to the bending die and held (constrained) to perform bending, and this bending method is somewhat improved compared to the former, but as shown in Fig. 3, the relationship of force is still present. With the drawback that the outside of the bent part extends and the inside shrinks and the bent part is crushed, the bent work shape is restored by inserting several kinds of core metal correction tools from both ends of the bent work. As a result, restoration work is more advantageous than bending work.
It had a drawback that the work load was about 0 times.

In the above-mentioned bending method, the above-mentioned drawbacks occur largely in the case of steel pipes, stainless pipes, etc., depending on the material of the pipes. Specifically, the cross-sectional deformation of the bent portion is large and the inner pipe wall is buckled. As it occurred, the outer tube wall was broken.

Bending is almost impossible with the first method, and bending is possible with the second method, but the number of steps and the number of operations are large. The front end of the work is fixed and grasped (contained) in the bending die, and the rear end of the work is pressed by the booster device. With such a bending method, the crushing phenomenon due to the force relationship of the bending part is slightly eliminated. Attempting to control so that the pulling force with the bending die and the pushing force with the booster device can be balanced, but the details are unknown, but during actual bending, as shown in Fig. 4, the seat of the pipe wall inside the pipe is It had a drawback that it had a large bend and still needed a work to restore the collapse.

Further, as a recent tendency, the mechanical parts of the engine room and the cooler of the automobile are at the forefront, and various machinery and equipment are complicated, auxiliary devices are required, and the size is reduced. As the piping space decreases, the arrangement position is limited, and the number of cases that bend at right angles along a wall surface increases, and as a result, the frequency of use of pipes bent to a minimum radius of curvature increases and There has been a demand for realizing a simple method.

[0008]

SUMMARY OF THE INVENTION According to the present invention, even when bent at a right angle 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 bent portion is not crushed and the circular cross section is maintained. It is intended to provide a bending method of a pipe having a minimum radius of curvature.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in which it is impossible to bend a pipe into a minimum radius of curvature, or in which it is necessary to restore the pipe into a circular cross section. When the bending die is rotated, the work piece slides forward in the clamp part to perform bending, so that even if the pipe is bent at a right angle to the minimum radius of curvature, the bending part does not collapse and the cross-section is circular. The above problem was solved by maintaining it.

[0010]

According to the present invention, when bending is performed at a right angle 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 work is clamped and clamped by the bending die. Then, the back end of the work is pressed by the booster device, and when the bending process is performed by rotating the bending die, the work is slid forward in the clamp part to perform the bending process, and the bending part is not crushed to maintain the circular cross section. Of.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Reference numeral 1 denotes a pipe bender for bending a work W such as a pipe, which is an upper part of a base (not shown) and is rotated forward. A flexible bending mold 2 is installed, a semicircular pipe groove 3 is formed in the bending mold 2, and a clamp mold 5 is installed at a base end portion 4 of the bending mold 2. Equipped with a hydraulic cylinder (not shown), pipe groove 6
Is formed.

Reference numeral 7 denotes a wrinkle removing device which is installed inside the bending die 2 adjacent to the wrinkle removing device 7. A pressure die 8 is slidably installed so as to face the wrinkle removing device 7, and the wrinkle removing device 7 and pressure die Pipe grooves 9 and 9a on the inner surface of 8, respectively
Is formed.

The pressure die 8 is equipped with two hydraulic cylinders (not shown). One hydraulic cylinder presses the pressure die 8 against the wrinkle removing device 7, and the other hydraulic cylinder has pressure. The die 8 is pressed so as to move in the axial direction of the work W, and the wrinkle removing device 7 corrects wrinkles and the like attached to the work W before bending by pressing with the pressure die 8.

Reference numeral 10 denotes a booster device installed in the rear portion of the bending die 2. The booster device 10 is arranged on an extension line of the work W, and a pipe pressure tube 13 is provided at the tip of a rod 12 of a pipe pressure cylinder 11. Along with mounting the rod
A stopper 14 that controls the amount of movement of 12 is installed.

Reference numeral 15 denotes a cored bar whose base end is fixed at a fixed position. The cored bar 15 is inserted through the stopper 14, the pipe pressurizing cylinder 11, the rod 12 and the pipe pressurizing tube 13, and the inside of the work W is inserted. And the tip of the core bar 15 is inserted into the work W
Inside, it reaches the bending start position of the bending die 2.

The pipe pressurizing cylinder 11 may not be arranged on the extension line of the work W, but the pipe pressurizing tube 13 may be controlled to move back and forth via a stay (not shown).

Next, a method of bending the work W such as a pipe to a minimum radius of curvature using the pipe bender 1 will be described. The tip end of the work W is pressed and held by the bending mold 2 by the clamp mold 5, It 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 work W is pressed by the operation of the pipe pressurizing cylinder 11 of the booster device 10,
The bending die 2 is rotated to bend the bending portion S of the work W so as to draw a radius of 90 degrees, and the workpiece W slides forward in the clamp portion C formed by the bending die 2 and the clamping die 5 during the bending process. The bending process is performed.

For example, the pressing force of the clamp die 5 is used with the cylinder output of 70 kg and the booster device 10 of the pipe pressurizing cylinder 11 at the output of 50 kg. Then, the work W is bent while sliding forward.

In the above action, the pressure of the cylinder of the clamp die 5 which is pressed and gripped is higher, but the work W is moved in the axial direction during the actual bending process, and the action of the conventional clamp die is fixed and grasped ( While the work is immovable in (holding), the action of the clamp die 5 of the present application is pressing and holding, and the work W is movable.

The tip length L1 of the work W protruding forward from the clamp die 5 before the start of the bending process becomes the post-processing tip length L2 after the bending process is completed, and the lengths of both of them are L2>
There is a relationship of L1, and the dimension of the rear end length L3 of the work W is adjusted by the amount of advance / retreat of the stopper 14.

By such a bending method, the bending can be performed in a state in which the cross-section deformation of the bending portion S of the work W hardly occurs and the inner tube wall of the work W hardly buckles.

Further, in the bending process in FIG. 1, the rear end of the work W before processing protrudes in a triangular shape on the outside corresponding to the bending part S, and this protruding part is pressed by the pipe pressure tube 13. At the time of bending, the inner side shrinks and the outer side expands at the bent portion S, so that the inner portion escapes outward and escapes in the axial direction, and the rear end portion of the work W becomes vertical after the machining is completed.

Finally, the dimensional relationship of the work W bent to have a minimum radius of curvature will be described. Taking the work W of a copper pipe as shown in FIG. 2 as an example, the cross-sectional diameter D of the work W is Φ20 (20 mm). ), When the bending radius R is 15 mm, it is displayed as Φ20 × 0.75 DR, and the comparison between the conventional bending method and the bending method of the present invention will be illustrated below.

For iron, the conventional bending method is 2.0DR
Was the limit, but with the bending method of the present invention, 1.0DR
With copper pipes, 0.7DR is possible. For example, if the cross-sectional diameter D is Φ16, the bending radius R is 11.2 mm.

[0025]

[Table 1]

In the above table, the conventional method is the conventional bending method, and the bending method is to clamp and hold (hold) the clamp, and the conventional method is the conventional bending method, which is the clamp and grasp ( The bending method in which the work W is held and pressed from the rear end, and the method of the present invention is a bending method in which the work W is slid and moved by pressing and grasping with a clamp and pressing from the rear end.

As the material of the work W, those made of iron and copper are shown in the above table, and the one made of copper is a material that can be easily processed. Both materials are according to the method of the present invention.
Bending with a minimum radius of curvature is possible, and in addition to the above materials, there are materials such as brass and aluminum.

[0028]

In summary, according to the present invention, the tip of the work W is pressed and gripped by the bending die 2 by the clamp die 5, the rear end of the work W is pushed by the booster device 10, and the bending die 2 is rotated. At this time, since the work W is slid forward in the clamp part C to perform bending, the bend part S is not crushed,
It is possible to prevent buckling of the inner pipe wall of the work W and perform bending while maintaining the circular cross section.

Therefore, it is possible to manufacture the product as it is by bending once with the pipe bender 1 without requiring welding or restoring work as in the conventional case, and the number of processes, the amount of work, and the cost are remarkably increased. Its practical effect is extremely great.

[Brief description of drawings]

FIG. 1A is a plan view before starting bending by a pipe bender, and FIG. 1B is a plan view after ending bending.

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

FIG. 3 is a plan view of a work in which a conventional work is fixedly grasped (contained) in a bending die and bent.

FIG. 4 is a plan view of a conventional work in which a work is fixed and grasped (contained) in a bending die and is pressed by a rear end portion of the work to be bent.

[Explanation of symbols]

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

Claims (1)

[Claims] 1. A work piece slides forward in a clamp part during bending processing in which a tip end portion of a work is clamped by a clamp die to a bending die and a rear end portion of the work is pushed by a booster device to rotate the bend die. A bending method for a pipe having a minimum radius of curvature, which is characterized in that the bending process is performed.