CS254815B1 - Apparatus for manufacturing bent parts from a tubular blank - Google Patents

Abstract

The device for the production of bent parts from a tubular blank consists of mandrels for axial compression and a mold in which a transverse bending jaw and shaping jaws are located. Two mandrels are linearly slidably mounted against each other in the mold and are provided with a pressure medium supply. The device for the production of bent parts from a tubular blank is mainly usable in mechanical engineering production.

Description

BACKGROUND OF THE INVENTION The present invention relates to an apparatus for manufacturing bent parts from a tubular blank.

Up to now, cross-sectional changes have been observed in the manufacture of tube parts by molding, characterized by a reduction in flow rate and an increase in hydraulic resistance. Due to the longitudinal and transverse deformations, the shape of the cross-section and the wall thickness of the tube in the deformed region change. In order to overcome these drawbacks, the tubes are filled by various means, such as sand, easily fusible metals, metal mandrels or plastics, during molding. The latest in this field is an apparatus utilizing a method of manufacturing pipe components, wherein the pipe is filled with liquid and is simultaneously compressed and bent. A disadvantage of this device is that the forming tools do not move in a straight line with respect to each other and the device is complex. The disadvantage of all the devices used up to now is the great laboriousness, the deformation of the cross-section, damage to the inside of the pipe and the limitation of the geometric dimensions.

These drawbacks are overcome by a device for manufacturing bent parts from a tubular blank consisting of axial compression mandrels and a mold in which a transverse bending jaw and forming jaws are disposed according to the invention. It is based on the fact that the two mandrels are displaceably disposed in opposition to one another in the mold and are provided with a pressure medium supply.

Thus, in the apparatus for producing bent parts from tubular blanks according to the invention, the tube is filled with a pressurized liquid which prevents both the loss of tube stability and deforms the tube in the radial direction. The liquid pressure inside the tube can be controlled during the process. At the same time as internal pressure

- 2 254 815 and externally forming forces exert an axial force on the tube end which compresses the tube, while the axial force exerting pins maintain alignment. By simultaneously combining the magnitude of the internal pressure and the axial force, the stress pattern in the plastic region changes and allows | is to increase ductility. By controlling the ratio of the forming parameters, more complex shapes of the molded part can be achieved, by controlling the wall thickness and inducing large deformations, and by regulating the wall thickness.

The invention and its effects are explained in more detail in the description of an exemplary embodiment thereof according to the attached drawing, which shows schematically an apparatus for producing bent parts from a tubular blank according to the invention.

In the mold 1, the transverse bending jaw 2 and the shaping jaws 2 are located. In the mold 1, the mandrels provided with a pressure medium supply 6 are also arranged in a straight line.

After inserting the straight tube 6 into the split mold 1 and closing it, the lateral mandrels 4 exert an axial pressure sufficient to seal the inner space of the tube 6. At the beginning of the plastic deformation the transverse bending jaw 2 begins to move. The mandrels 2 move the mandrels 4 so as to ensure tightness and that the pressure of the mandrels 4 contributes to the shaping of the tube 6. Inside the tube 6, a pressure medium, preferably a liquid pressure medium, is supplied through the inlet 5 in the mandrel. During shaping, the fluid pressure inside the tube 6 is controlled. This liquid is important in that it reinforces the tube 6 during bending and prevents the wall from collapsing. The shaping jaws, either one or both, ensure the shape of the bent parts to be accurate. The ends of the tubes 6 to be produced are always positioned opposite each other in the two parts of the mold 1, as can be seen from the attached drawing.

The apparatus for producing bent parts from a tubular blank according to the invention can be used in particular for the mechanical production of bent parts which can serve as a whole or as a semi-finished product which can be divided into individual parts containing

- 3 254 815 one to four bends. The device is advantageous for producing arches and elbows with small bend radii.

Claims (1)

SUBJECT OF THE INVENTION Apparatus for producing bent parts from a tubular blank consisting of axial compression mandrels and a mold in which a transverse bending jaw and shaping jaws are located, characterized in that the two mandrels (4) are displaceably disposed in opposition to each other in the mold (1) and are provided with a pressure medium supply (5).