SU1379032A1 - Arrangement for cutting thread - Google Patents

Abstract

The invention relates to the field of threading internal threads and can be used for machining on lathes. The purpose of the invention is to increase productivity and accuracy by reducing the bending moments from cutting forces acting on the caliper and thread-cutting mandrel. The device consists of a spindle 1 in which a fixed nut 2 is installed with a thread pitch equal to the thread pitch — in part 9, a thread-cutting mandrel 3 with a comb 4, the front end 5 of which is threaded and designed to interact with the nut 2 4 il. (L oo so about so HS

Description

The invention relates to cutting internal threads with a chisel and can be used on lathes.

The purpose of the invention is to increase the productivity and accuracy of the thread being cut by reducing the bending moments from the cutting forces acting on the caliper and thread-cutting mandrel.

Fig. 1 shows a threading device; FIGS. 2-4 are diagrams of the forces acting on the device during the cutting process.

The device consists of a spindle 1, in which a copier nut 2 with a thread pitch equal to the pitch of the thread being cut, a thread-cutting mandrel 3 with a carbide-tipped comb 4, whose front end 5 is threaded, is rigidly connected to it. The mandrel 3 is fixed in the tool holder 6 support 7, In the cartridge 8, mounted on the spindle 1, the workpiece 9 is installed.

Us1, the roegium works as follows.

The threaded mandrel 3 is aligned coaxially with the spindle 1. Spindle 1 rotates and the axial movement of the slide 7 with the cutter 6 is coordinated. At the same time, the slide moves so that for each turn of the spindle it moves by

S, S -c,

where S, is the device setup step; S - thread pitch; c is the value of a given mismatch between the pitch of the thread being cut and the pitch for the device construction.

., -

The nut 2 rotating at the same time with the spindle 1, meeting with the threaded end 5, is screwed onto it, causing, due to the indicated step difference, elastic stretching of the thread-cutting mandrel 3 by the amount for each spindle revolution. It is obvious that the threaded mandrel 3 acquires in this case additional rigidity as

by stretching and by the presence of a second support in the form of a nut 2.

At the same time, bending moments from cutting forces Мр, Мр, and Мрр, caused by radial cutting forces Р ,,, tangédial Р and axial Р are significantly compensated by the moments

Mp, PV y - R y (x,);

M p R: (Heh-C) - P, Z ,;

Mr, P, R, z, + R, y ,,

where Us and, respectively, the ordinate and applicate of the support center plate in the selected coordinate system 4 X (. is the distance from the line of action of the force P applied in the middle of the threaded comb 4 to the center of the support plate 7, i.e. the distance from the threaded comb 4 to the nut 2, taken between the points lying in the middle of their length; R and R are the axle shafts

Z and y.

The magnitude of the tensile force of the thread-cutting mandrel 3 is selected so that it does not exceed the allowable axial force according to the condition of operation of the device (machine) and the accuracy of the cut thread.

Claims (1)

Invention Formula A threading device comprising a spindle with a chuck intended for securing the part and a kinematically associated caliper with a tool holder that is not suitable for a thread-cutting mandrel with a thread chisel, characterized in that, in order to increase productivity and accuracy of the thread being cut, the device is copied A nut mounted in the spindle is threaded at the end of the thread-cutting mandrel in front of the thread cutter and is designed to cooperate with the key nut. : with " Fig.Z FIG .. “-. : - v :: ir: s i FIG.