CS252113B1 - Process for the production of hot hollow bottoms - Google Patents

Abstract

For the production of hollow bodies, especially steel cylinders for compressed gases, by hot extrusion, a solid roller of circular or square cross-section is used, from which, after heating to the forming temperature, a suitable preform is pressed onto the die, which is then pressed into the desired product in the extrusion die of another press. To achieve the evenness of the body in the longitudinal direction, either a mandrel is used, which moves inside the body at the same speed as the extruded body, or internal or external traction is applied to the extruded body during the production process.

Description

The present invention provides a process for producing hollow bodies with a base of heat, in particular steel cylinders, not compressed with gases, in which a solid material of appropriate cross-section is used as the starting material.

In the prior art processes for the manufacture of hollow bodies, in particular steel light fittings, either tubes are used as starting material in which the bottoms are formed by forging and welding with an oxyacetylene flame with ice calibration of the bottom or or a solid material from which a heavy-duty hollow body is molded in a die, which is then adjusted to the desired wall thickness by pulling it over the tension rings or pulleys. In the first method, the starting material is costly, in the second the relative manufacturing accuracy, the third method requires a spatially dimensioned production equipment.

The manufacturing method of the present invention removes these drawbacks, since solid material of appropriate cross-section is used as the starting material, simplifies the manufacture itself to extrude the preform and moves within the body at the same speed as the extruded body, mandrel, to achieve straightness of the body.

Said method of production reduces the cost of the starting material, the bottom of the hollow bodies and hence of the non-pressurized gas cylinders is weldless and the entire production is simpler.

The accompanying drawings show an example of a starting hollow body for manufacturing a steel bottle. FIG. 1 shows a preform molded from solid circular material.

Figure 2 shows the shape of a hollow body made by extrusion from a previous preform.

FIG. 2 shows the actual method of extruding a hollow body. The preform 4 heated to the forming temperature is inserted into a die formed by a sleeve 2 and a flow ring 2.

The hollow mandrel 2 is extruded through the press ring 2 ^θ by means of a solid mandrel 1 taking the form of a hollow body. The figure shows a manufacturing process in which the solid mandrel 1 moves at the same speed with the material flowing out, thus ensuring the body is straight with respect to its longitudinal axis. The beginning of the solid mandrel 1 is delayed by the time the extruded hollow body 4 travels a 50 mm path. This eliminates the effect of manufacturing inaccuracies and not longitudinal straightness of the body. With respect to the technological conditions, it is possible to achieve quite the same result with the stationary mandrel 1, that is, the mandrel 1 assumes a stable position in the flow ring 2. rectified by mandrel 1

In practice, however, this result is virtually impossible to achieve, since it is not possible to adhere strictly to the exact technological conditions required by this process. As a result, when the thin-walled hollow bodies are extruded, with a wall thickness to eel length ratio of from 1:50 and higher, the unevenness of the bodies to be extruded relative to their longitudinal axis, so-called saber, occurs. The same effect on the equality of the extruded hollow body as in the previous case can be achieved in the stable mandrel manufacturing process by applying external or internal tension to the extruded body during the manufacturing process. The maximum tensile value is given by the cross-section of the product and the yield point of the material at dB temperature.

The production process could also be used to produce starting hollow bodies for the production of casings which are produced by cold drawing from round circles. This would reduce the cost of starting material and reduce the number of strokes required to make the product. Furthermore, this method of production is less energy-intensive in comparison with the production of tubes by flat rolling and very suitable for completing the robotization of the workplace.

Claims (2)

SUBJECT OF THE INVENTION 1. A process for the production of hot-extruded hollow bodies which are suitable as a starting body for the production of non-pressurized gas cylinders, for the production of cartridges and the like, wherein the starting material used is a solid round or square cross section which is heated. to the forming temperature and to the press face to the preform, which is extruded on the next press by direct hot extrusion into the shape of a hollow body, characterized in that to achieve the flatness of the body with respect to its longitudinal axis a movable mandrel, which moves at the same speed as the leaking body and directs the flow of the body along its entire length. 2. Method according to claim 1, characterized in that the non-extruded body exerts an internal or external tension during the manufacturing process, the maximum value of which is given by the cross-section of the product and the yield strength of the formed material at a given temperature.