Draw round diameter 70 mm

Source data.

Pulling workpiece: 40XC material, hardness in pulling operation HB 270;

Hole diameter: D = 70mm, fit H7

Roughness: Ra = 0.32mkm

Sweep length: L = 80mm

Machine: 7A540 electric motor power 40kW, nominal traction force 40 tf.

Nature of production-large-scale

Select a cutting scheme.

To process the cylindrical hole, we select variable cutting rails, which are a variant of the group cutting scheme (as per GOST 2036474 and GOST 2036474. The group cutting scheme is characterized by the fact that the metal layer along the entire profile is removed not by an individual tooth, but by a group or section.

We establish the machinability group:

According to [Table 2 of Annex 3 (5)], 40XC steel and 270HB material hardness belong to the 4th workability group.

We establish the quality group of the swept surface:

The quality group of the stretched surface is determined by one of the technical requirements (surface roughness, accuracy class) At Ra0.32mkm we accept the first quality group. [tab. 2 (1)]

Choose the type of lubricant and coolant.

Depending on the workability group of the stretched material and the quality group of the stretched surface according to [Table 3 (1)], we take AND-activated emulsion-castor oil, soda ash water.

Select the material of the cutting part of the pulling.

The material of the cutting part is assigned taking into account the workability group, the type of production, etc. [Table 7 (1)], we accept the fast-cutting steel P9F5.

The method of connecting the cutting part of the pulling with the shank is selected.

In practice, the pulling shanks are made integral with the cutting part welded and detachable. Links over 40 mm are made welded or with mechanical attachment of the shank. Select a weld joint.

The shank is welded to the cutting part on the neck at a distance of 1525 mm from the beginning of the transition cone.

Calculation and design of round draws (creation and initial data for calculation and graphics work). SPI, Saratov, 1980

Rodin P.R. Metal cutting tools. Kiev. High School, 1980.

Zhigalko N.I., Kiselev V.V. Design and production of cutting tools. Minsk, Higher School, 1975.

GOST 20364-74

GOST 20365-74

Katsev P.G., Epifanov N.P. Directory of the stretcher. M., Mashgiz, 1963.

Shatin V.P. Shatin Yu.V. Handbook of the designer-toolmaker. M., Mechanical Engineering, 1975

Gladilin A.N., Malevsky N.P. Handbook of a young toolmaker on a cutting instrument. M., Higher School, 1973.

Metalworker's handbook (in 5 tons), vol. 3. Ed. A.N. Malova. M., Mechanical Engineering, 1977.

GOST 9126-76

Reference Appendix to the Manual "Calculation and Design of Variable Cutting Circular Rails for Cylindrical Hole Treatment." Saratov. SPI, 1981.

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