JPS6241808B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for better bending a tube.

Traditionally, bent pipes have been used for gas and water piping for ships and buildings, fuel supply for chemical plants, etc.
They are widely used in various equipment and plants, such as various types of piping for reaction systems, and bending the pipes to produce bent pipes is much more complicated than bending flat plates, and is always difficult due to the degree of processing. It falls under the processing category.

In pipe bending, plate thickness, pipe diameter, bending radius,
Depending on the material and processing conditions, it may or may not be easy. For example, the relative relationship between the plate thickness and the pipe diameter is a particularly important factor; for the same pipe diameter, a thicker wall is easier to bend, and for the same wall thickness, a smaller pipe diameter is easier to bend. . In addition, the material has high ductility and elongation,
The softer the material, the easier it is to bend, and the harder and more elastic the material, the more difficult it is to bend. Furthermore, during processing, the smaller the bending radius, the more difficult the bending becomes. Difficulty in bending means that during bending, tensile and compressive deformation acts on the outside diameter and inside diameter of the pipe, causing buckling deformation, uneven thickness, or wrinkles in the pipe cross section, which significantly impairs processing quality. This means that a breakage or the like occurs due to obstruction or deformation.

In the past, various methods have been used for pipes that are difficult to bend. For example, there are methods to control cross-sectional deformation by filling the inside of the pipe with a mandrel made of lead, solder, or sand. It is taken. Such conventional methods have the following problems. First, the method of pouring molten metal such as lead or solder into a tube requires a short melting time before bending.
There are problems in terms of processing cost due to the increased removal time, problems in workability when considering the fact that the metal is melted, and problems such as difficulty in completely removing the molten metal after processing.

Methods of enclosing the mandrel include methods of compressing and inserting a coil spring, methods of inserting a cylindrical core made by flexibly connecting spherical or other rigid bodies, and methods of inserting a laminated plate. In any case, pulling out the mandrel after bending requires considerable force and is not an easy task.

The next method is to fill the tube with powder such as sand, but this method attempts to control the cross-sectional deformation of the tube by the frictional resistance of the powder packed inside the tube. It is possible to perform a suitable bending process if one is done properly. However, powder is usually fluid and has voids between particles, so unless the conditions are set very properly, the powder will flow as the tube is bent, and the desired resistance will not be achieved. There are disadvantages that cannot be obtained. Furthermore, the sand encapsulation method is usually ineffective unless it is sufficiently packed by reducing the void space while vibrating, and it takes a long time to fill the sand.
Moreover, it is very difficult to take them out after bending.

The present invention has been developed in view of the above-mentioned conventional problems.
This method provides a method for easily bending a tube and obtaining a high-quality bent tube.The method involves encapsulating ferromagnetic particles in the tube to be bent.
It is characterized in that these particles are bound together by magnetic force during bending.

Therefore, since powder particles are enclosed in the tube, workability is good, and during bending, these particles are bonded by magnetic force, so the rigid particles restrain cross-sectional deformation of the tube. Tube buckling, wrinkles,
Breakage etc. will be resolved. Furthermore, by changing the magnetic force, the bonding force of the particles can be adjusted, and control such as changing the rigidity of the particles by bending, especially the bending radius, can be easily realized.

Embodiments according to the present invention will be described below based on the drawings. FIGS. 1 and 2 show a tube bending equipment for carrying out the method according to the present invention, in which 1 is a tube to be processed, 2 is a ferromagnetic particle sealed inside the bent portion of the tube 1, and 3 is a tube to be bent. 4 is a rod connected to the push die 3, 5 is a pressurizing cylinder, 6 is a frame, and 7 is rotatable to support the tube 1. A pulley, 8 is a pedestal supporting the pressure cylinder 5, pulley 7, etc., 9 is a horseshoe-shaped magnet that covers the bent portion of the pipe 1, and 10 is a coil. Since the press die 3 is displaced during the bending process, in order to keep the relative position of the press die 3 and the magnet 9 constant, the press die 3 or the rod 4 and the magnet 9 may be connected by a member not shown. Must be able to travel by other means. In the above apparatus, first, powder particles 2 are packed into the bent portion of the tube 1 to be bent, either before or after setting it in the apparatus. The particles 2 can be stopped at the bent portion by, for example, putting a plug made of styrofoam or the like at one end of the pipe 1 and allowing the particles to flow in from one end. Thereafter, when the coil 10 is energized to generate a magnetic field in the magnet 9, the powder particles 2 are instantaneously magnetized and inter-particle bonding occurs, forming a solid, so-called solid object that no longer has fluidity. Thereafter, when pressure fluid is supplied to the pressurizing cylinder 5, the rod 4 is actuated, and the press die 3 connected to the tip of the rod 4 presses the tube 1 to start bending. Due to the bending action of the pipe 1, a tensile force is applied to the bent outer diameter part, and a compressive force is applied to the bent inner diameter part, and since it is a member with a circular cross section, a complicated stress distribution occurs on the pipe circumference. However, a stress is generated that tends to deform the cross section, but the magnetized and integrated particles 2 as described above restrain the deformation and become a resistor that maintains the circular shape. Therefore, the above-mentioned restraining force does not cause problems such as buckling, wrinkles, and breakage of the tube 1.

Furthermore, after processing, if the current flowing through the electric coil 10 is cut off and the induced magnetic field of the magnet is demagnetized, the binding force between the particles 2 is released and the particles return to their original powder form, so they can be removed from the tube 1. is easily performed.

Depending on the type of pipe to be bent, particles 2 may be
Suitable processing can be performed by adjusting the bonding force between the two.

Next, another embodiment according to the present invention will be described based on FIGS. 3 and 4. 11 is a pipe to be processed; 12 is a magnetizable particle sealed inside the bent portion of the pipe 11; 13 is a bending mold having an outer diameter corresponding to the bending radius and a shape that follows the circumferential surface of the pipe 11;
4 is a tightening die for tightening the pipe 11;
15 is a female thread, 16 is a screw shaft connected to the tightening die 14 and passed through the female thread 15, 17 is a handle connected to the screw shaft 16, and 18 is a screw shaft connected to the tightening die 14 and the screw shaft 16 through the female thread 15. 19 is a tightening die for tightening the pipe 11; 20 is a female thread; 21 is connected to the tightening die 19 and is penetrated by a female thread 20; 22 is a handle connected to the screw shaft 21; 23 is a frame for fixing the tightening die 19 and the screw shaft 21 via the female thread 20; 24 is the pipe 11;
A horseshoe-shaped magnet 25 covers the bent portion of the coil.

Next, the operation will be described. First, prior to processing, powder particles 12 are packed into the tube 11 at the portion that will become the bent portion. Thereafter, when the coil 25 is energized and an induced magnetic field is generated in the magnet 24, the powder particles 12 are instantaneously magnetized and interparticle bonding occurs, forming a solid, so-to-speak, one piece with no fluidity. Thereafter, when the frame 18 is rotated around the bending die 13, the pipe 11 is bent along the circumferential surface of the bending die 13.

The effect of the magnetically coupled particles is the same as in the embodiment shown in FIGS. 1 and 2 above.

The tube bending device according to the present invention is not limited to the thrust bending method or wrap bending method shown in the embodiments, but can be applied to various bending methods such as tension bending and grooved roll bending.

As is clear from the detailed description above, according to the present invention, particles are sealed inside the pipe to be bent,
Since this is magnetized and then bent, the work steps before and after bending are easy, resulting in good work efficiency and improved quality of the processed pipe.

[Brief explanation of the drawing]

1 and 2 show an embodiment according to the present invention, FIG. 1 is a plan view, and FIG. 2 is a -
FIG. FIGS. 3 and 4 show other embodiments of the present invention, with FIG. 3 being a plan view and FIG. 4 being a cross-sectional view taken from FIG. 3. 1...Tube, 2...Particle, 3...Press mold, 5...
Pressure cylinder, 6... Frame, 7... Pulley, 9
...Magnet, 10...Coil.

Claims (1)

[Claims] 1. A tube bending method characterized by enclosing ferromagnetic particles in a tube, magnetizing these particles, and then bending the part containing the particles.