SU1609561A1 - Method of producing thread with variable pitch - Google Patents

Abstract

The invention relates to mechanical engineering, in particular to the manufacture of threaded products, and can be used when cutting threads in nuts. The purpose of the invention is to simplify the thread cutting process by reducing the labor intensity of the process of changing the linear dimensions of the workpiece. Before threading, the blank of the nut is compressed by a portion of its height with an axial force, then threading is performed. After removal of the tool, the axial compressive force is removed. Compression force is determined by mathematical dependence. 3 il.

Description

The invention relates to mechanical engineering, in particular to the manufacture of threads, and can be used in threading in-nuts.

The aim of the invention is to simplify the process of threading by reducing the complexity of the process of changing the linear dimensions of the workpiece.

FIG. Figure 1 shows the stress distribution across the threads and the nature of the load distribution across the nut turns; in fig. 2 and 3 - loading the billet nut with a compressive force when cutting the thread according to the proposed method.

In order to relieve the threads of the bolt located at the nut's butt-end, especially its first turn, in which the greatest stress concentration occurs leading to a decrease in fatigue resistance, it is necessary to slightly increase the nut thread pitch in the area of its bearing end. For this, the blank 1 is compressed along the axis by the punch 2, and a compressive force is applied to the part of the nut in height. After that, threading is performed with a tool with a standard step corresponding to the step of the mating bolt.

After threading and removing the tool from the treated nut, relieve the compressive force. The thread obtained will have a variable pitch-standard in the upper part and an enlarged in the lower part, which was under the influence of the compression force.

With the conical shape of the nut or with its small height, the nut should be compressed to its full height, which gives the same effect. But the step in this case will be permanent.

The amount of compression force: determined by the formula

p 1fnf1,

where P is the thread pitch of the tool;

AI - we set the maximum error of the thread pitch of the nut;

Ar - measured maximum error; ness of tool pitch;

SP

with

oh oh you ate

0s

E is the elastic modulus of the nut material;

A is the cross-sectional area of the nut blank, and the sign - is taken if the measured tool pitch is more than the nominal, thread pitch, + - if it is larger.

Claims (1)

Invention Formula A method of manufacturing a variable pitch thread, including changing the linear dimensions of the workpiece along its axis, cutting the thread with a tool with constant pitch, and restoring the linear dimensions of the workpiece, characterized in that, in order to simplify the thread cutting process, changing the linear dimensions of the workpiece applying an axial force of compression to a part of the length of the workpiece, the compression force F being determined by the formula ). where P is the thread pitch; AI - set the error of the thread pitch; Dg is the measured error of the tool pitch; E is the modulus of elasticity of the material of the workpiece; A is the cross-sectional area of the workpiece; H - the height of the workpiece. V ъ lufuu TTii rL DGG V V777 / X ////// 777 ////// l FIG. g Compiled by G.Kanevsky Editor Y. SeredaTehred M. Morgental h f Fiyol one Scientific research institute Fi.Z Proofreader T.Paly