SU897410A1 - Expanding mandrel - Google Patents

Description

(54) EXTENSION FRAMING

I

The invention relates to metalworking and can be used to fasten cylindrical parts.

A known expanding mandrel has a cavity in its casing, which forms thin-walled sections and is filled with working medium fI.

With this design, the accuracy of centering is low, since under the action of the pressure of the working medium, the thin-walled sections become barrel-shaped.

The purpose of the invention is to improve the accuracy of centering.

The goal is achieved by the fact that the cavity is made along a helix, forming the profile sections that are differentiated in any cross section.

This embodiment increases the accuracy of centering as a result of the uniform deformation of thin-walled sections located along a helix.

Figure 1 shows a schematic representation of the proposed mandrel, a general view; figure 2 - section aa in figure 1; on fig.Z - section bb in figure 1.

The mandrel consists of a housing 1, in which a cavity 2 is formed along a helical line, forming profile sections which are differentiated in any cross section. The cavity 2 is filled with a working medium, such as oil. In each subsequent section (Fig. 2), the direction of displacement of cavity 2 relative to the axis of body 1 is different from the previous one, and the geometrical position of the lines connecting the centers 3 of cavity 2 and center of gravity 4 in sections (with an infinitely large amount of section) is a helical surface.

The mandrel works as follows.

Claims (2)

Under the influence of the working medium in the mandrel, bending forces arise that are directed along the lines connecting the centers of gravity 4 with the centers of the 3 cavities. 2. But since the locus of these lines is a helical surface, the bending forces are also distributed along the body 1 along the helix. Under the action of these forces, the centers of curvature of the bends are in the opposite position with respect to the direction of displacement of the cavity 2. In working condition (when exposed to the working medium), its transverse overall size increases due to the total helical deformation of the rectilinear body 1, and this deformation is uniform in length, and the magnitude of the deformation is proportional to the applied pressure. Thus, when pre-fitting to the working part of the mandrel of the required part, it turns out to be evenly clamped along the entire length due to the choice of the landing clearance by the mandrel with a force proportional to the internal pressure of the working medium. If the mandrel is grinded at a certain degree of deformation (at 4 a certain pressure value; it will have high centering properties, moreover over its entire length. The tightness and amount of clamping force provided constructively can reach practically any desired values. The effect of the introduction is to improve the accuracy of the centering. Claims of the Invention The expanding mandrel, in the body of which a cavity is formed, forming thin-walled sections and filled with a working medium, is different This is due to the fact that, in order to improve the accuracy of centering, the cavity is made along a helix, forming profile sections that are differentiated in any cross-section.Sources of information taken into account in the examination I. M. Anserov Adaptations for turning and circular grinding machines. L., 1953, pp. 195-196, figure 177.