SK288269B6 - Method of pipes expansion and device for carrying out this method - Google Patents

Abstract

In the method of pipes expansion, a pipe is inserted into a divided draw die and in the pipe is plugged a draw punch with a elastic draw punch. The inserted pipe is compressed by another draw punch at the current pressing of the elastic draw punch. Also is described a device for carrying out this method.

Description

Technical field

BACKGROUND OF THE INVENTION The present invention relates to a method for expanding pipes allowing to maintain a constant thickness of the pipe while changing its diameters, and to an apparatus for carrying out the method.

BACKGROUND OF THE INVENTION

The expansion of pipes is currently provided by pressing. The pipe is inserted into the punch, using an elastomer which is compressed to compress the punch to compress the pipe.

In another technology, instead of an elastomer, a fluid is used which compresses and ensures the expansion of the pipe.

Said methods provide for changing the diameters by expanding the pipe and changing its thickness. Larger diameters change beyond the plasticity of the pipe and the pipe rupture and therefore expansion has to be ensured by several operations.

Expansion of the pipe with liquid entails a number of problems with sealing the space in which the liquid is located. As in the previous case, the wall thickness of the expanded pipe changes during expansion.

SUMMARY OF THE INVENTION

The above-mentioned drawbacks are eliminated by the method of pipe expansion, in which the pipe is inserted into the split punch and the elastic punch is inserted into the pipe by the punches and the other punches are pressed together. For compressing the pipe, the inner diameter of the pipe compressing punch and the outer diameter of the flexible elastomer punch are sliding and have a diameter equal to or less than the inner diameter of the expanded pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

The figure shows a tube expansion die with a split punch with a tube inserted and a punch inserted with a flexible punch before and after expansion.

DETAILED DESCRIPTION OF THE INVENTION

The tube expansion die is shown in the figure and consists of a divided punch 5 and 6, bodies 7 and 8, punches 5 and 6, punches 1 and 2, a flexible punch 3, a guide 4, a flexible punch 3 and an expanded pipe 9.

The punches 5 and 6 form a punch and are radially or axially divided so that the expanded tube 9 can be removed from the die after being expanded and is housed in the bodies 7 and 8.

In the punch 1 a guide 4 of a flexible punch 3 is guided by a guide 10 on which the resilient punch 3 is supported. The punch 2 is guided by the punch 1 and allows the pipe 9 to be compressed. The punches 1 and 2 are independently controlled.

After insertion of the pipe 9 into the punches 5 and 6 by the puncher 1, the flexible puncher 3 is inserted into the pipe 9. Puncher 2 compresses the pipe 9 and punches the elastic puncher 3.

The pipe 9 is stressed on the strut and the expansion of the resilient pusher 3 leads to a loss of stability of the pipe 9.

With the simultaneous action of the punches 1 and 2, the pipe 9 extends between the resilient punch 3 and the punches 5 and 6, thereby maintaining the same pipe thickness 9 in the expanded portion of the pipe 9.

Claims (3)

PATENT CLAIMS 1. A method of expanding pipes, characterized in that the pipe is inserted into a split punch and a punch with a resilient punch is inserted into the pipe and the punch is compressed by the other puncher while pressing the resilient punch. Device for carrying out the method according to claim 1, comprising bodies, punches, punches, resilient punch and resilient punch guide, characterized in that the axis of movement of the punch (2) coincides with the punch axis of movement (1). Device according to claim 2, characterized in that the outer diameter of the punch (1) and the inner diameter of the punch (2) are slidably mounted and their diameter is equal to or smaller than the inner diameter of the expanded pipe (9).