SU380409A1 - METHOD OF THREAD CUTTING - Google Patents

Description

one

The invention relates to mechanical engineering technology, in particular to thread cutting.

There is a known method of threading with a worm milling cutter, forming a screw pair with the workpiece.

The purpose of the invention is to simplify the manufacturing technology and ensure the cutting of internal threads with an earthen milling cutter.

For this, the axis of the cutter and the workpiece are placed in the same plane, and the point of contact of the centroid of the screw pair is shifted relative to the pole of engagement.

FIG. 1 shows a milling cutter and a workpiece with parallel axes, a radial section; in fig. 2 shows a cylindrical thread cutting circuit; in fig. 3 is a schematic of threading a conic thread; in fig. 4 - internal threading scheme.

Threading the proposed method is possible only when milling. The helical lines of the milling cutter and the thread being cut are obtained in the opposite direction. At the cutting points, the helix lines of the cutter and the threads are in contact (they have a common tangent plane). Therefore, the application of the proposed method does not depend on the angle of the helix of the thread. The method is suitable for cutting both single and multiple threads.

When passing milling to create in the cutting zone the relative sliding speed of the surfaces of the workpiece / and cutter 2, i.e., cutting speed, touch point P, the cutter centroid and threads in the end section are shifted relative to the pole of the engagement PO by increasing the cutter diameter. This ensures in the cutting zone a relative slip speed with a gear ratio between the links equal to one. The source here are the relations:

-,; r + r, A, ri

where TI and Ha are the radii of the thread centroid and cutter, respectively; H2 - gear ratio; L - center distance. The cutting process will be provided if in the cutting zone the speed of relative slip (cutting speed):

I / ,, V, -V ,,

where Vz is the circumferential speed of the milling point; V is the circumferential speed of the thread point.

In accordance with FIG. 1 must be:

With this method it is possible to cut the thread if the radial dimensions of the cutter will significantly exceed the radial dimensions of the cut thread.

Since the worm has a coil, regardless of the cutting method, the number of teeth, the surface of the thread will be faceted. Therefore, the number of teeth should be as large as possible.

The proposed method is also possible cutting and internal threads.

When cutting occurs, the thread surface rushes onto the cut-off, on the surface of the cutter. Therefore, the cutter teeth should have a reverse front surface.

The proposed method requires the profiling of the milling cutter, since the specified profile of the thread coil and its matching profile; the milling cutter;

four

The proposed method of threading can be directly implemented on thread milling semi-automatic machines. When using, for example, turning equipment, an additional tooling in the form of a milling head is required.

Subject invention

The method of threading an earthen milling cutter forming screws with a blank napv, characterized in that, in order to simplify, manufacturing techniques by eliminating axial feed, as well as providing the possibility of cutting an internal thread with an earthen milling cutter, the workpiece and the milling cutter are located in one plane, and the point of contact is the centroid of the screw pair relative to the pole of the cutter and workpiece.

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