DE1777043A1 - Tool calibration for cold pilger mills - Google Patents

Description

Mannesmann-Meer AG, 4-05 Mönchengladbach, Karmannsstrasse

"Tool calibration for Ealtpxlgerwalzwerke"

As is known, the tools for producing bores on cold pilger mills consist of a pair of external tools in the form of ring rollers or so-called Bakkenwalzen and an inner tool in the form of a rolling mandrel, such recesses are incorporated on the circumference of the rollers that they together have the caliber form, while the rolling mandrel has a corresponding taper has, the length of which gives the so-called working length and corresponds to the development length of the caliber.

Are currently used Calibrations in which the settlement of the outer tool show several conical shoulders over the working length and the inner tool a linear single cone along the working length having.

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It has been shown that local rolling pressure peaks occur at the transitions between the rolling cones of the outer tool, which on the one hand cause locally higher wear and on the other hand the entire rolling mill higher Exposure to loads and stresses, including the unfavorable location of the high degree of hardening contributes.

In addition, the causes linear conical on the working length Course of the dome such a severe rolling-technical capacity limitation due to the resulting large widening, that the application of the cold pilgrimage for the

There are limits to the rolling of carbon steels and liE metals and such pipes are practically not economical to manufacture o

The so-called step-by-step linear calibration of the outer diameter was replaced by the associated curve calibration (Freiberger lorschungshefte 8 88/1964 p. 49 ff), at which the development forms a connected curve, thereby making it more suitable compared to the step-wise linear calibration To ensure deformation conditions and also a higher performance of the roll stand and thus a longer service life to achieve both the tools, as well as the roll stand itself for reasons of lower and more uniform rolling pressures. However, this calibration cannot prevent the large spread.

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All these calibration methods have in common that a certain rolling mandrel, the course of which is fixed, the Wall reduction is superimposed and the course of the roll calibration results from this.

The consequence of this is that with the same shell and finished tube outer diameter, the shell and finished tube walls can vary only a little without also changing roll calibration is required. |

It is therefore worth striving for a tool calibration which, with the outer diameter of the shell and the finished tube, can roll different shell and finished tube inner diameters without changing the wall reduction curve, ie without having to change the outer tool calibration _{or the like}

Such a calibration is given according to the invention if, in contrast to what has been described above, the starting point is not the inner tool, but rather a roller calibration is determined from the shell and finished pipe outer diameter and the roller mandrel is selected so that the appropriate wall reduction curve is achieved. The execution of the calibration of the outer tool and the inner tool, which until then had a linearly conical shape, have a continuously concave, preferably parabolic curve.

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runs over the entire working length with preferably tangential entry into the approximately cylindrical smoothing pass on · The curve of the inner tool has the same mathematical function, preferably with same exponent, with a tangential transition into the smoothing pass the selected curve of a cylindrical basic shape with a finished pipe diameter is superimposed. But it can also a truncated cone, the smallest diameter of which is the finished pipe diameter, can be selected as the basic shape.

The formation of the rolling mandrel after a concave continuous Curve shape with tangential or almost tangential entry into the smoothing pass length causes the size of the Side clearance and thus the width of the pipe at the end of the working length of the outer caliber is so small that the There is no longer any risk of longitudinal cracks in the finished pipe, which is the case with a simple conical rolling mandrel.

By reducing the local conicity of the inner tool due to the course of the curve according to the invention, an increase in the lobe feed per working stroke or stretching can be achieved, whereby the finished pipe output of the cold pilger mill is increased to such an extent that, for example, the rolling of carbon steel and non-ferrous metal Quality pipes on the cold pilger mill can be described as an economical process _o

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As already mentioned, they are preferably parabolic steady curves of the inner tool and the execution of the calibration of the outer tool the same mathematical Function, i.e., for example, the parameters for indoor and external tools have the same exponent.

If one chooses the same mathematical function for the inner tool as for a suitable wall reduction curve, the result is a very favorable external " diameter reduction course with the same mathematical Function, whereby the choice of the mathematical function is free and depends on the deformation properties of the Rolled stock straightened

When using this finding raises the possibility to vary as desired the inside diameter of hollow billet and the finished tube with a constant outer diameter of hollow billet and the finished pipe, without it being required that λ Außenwerk- to change imaging.

In this case, only the internal tool has to be changed will. This not only saves costs, but also saves time when changing tools »

In order to reduce the friction conditions on the outlet side of the working caliber when processing "soft materials" it is customary to choose a minimum taper for the inner tool «

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To this advantage in the calibration according to the invention can be used for the curve, instead of on a cylindrical basic shape with the finished pipe inside diameter to build, also choose a suitable truncated cone as the basic shape, the smallest diameter of which is the inner diameter of the finished pipe is, whereby the tangential entry into the smoothing pass is omitted, but experience has shown that it is of no consequence falls.

The first embodiment is shown schematically in Fig. 1, the second in Fig. 2.

It means:

DL - largest clear diameter of the roller caliber, DF - smallest clear diameter of the roller caliber, dL - largest mandrel diameter,

dF - smallest mandrel diameter,

X - processing of the working caliber,

Y curve of the roller caliber,

Z - curve of the mandrel,

Z ¹ - truncated cone.

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Claims (1)

Claims ι 1. Tool calibration for cold pilger mills, thereby characterized in that the execution of the calibration of the outer tool and the inner tool have a continuous concave, preferably have a parabolic curve shape over the entire working length. 2o tool calibration, in particular according to claim 1, | characterized in that the preferably parabolic continuous curve courses of the inner tool and the development of the outer tool follow the same mathematical function and have the same parabolic exponent _o 3 ο tool calibration according to claim 1, characterized in that that the curve entry into the smoothing caliber takes place tangentially and a cylindrical (Fig, 1) or a conical Basic shape (Fig. 2) is superimposed. / / i.fi I 109830/0690