SU984704A2 - Three-jaw self-centring lathe chuck - Google Patents

Description

(S) TRINCULAR SELF-CENTERING LATCH CARTRIDGE

one

The invention relates to a machine tool industry and can be used in metal cutting machines, turning, grinding (for example spiral grinding), and machines with copying mechanisms.

According to the main author. se. No. is a three-cam self-centering lathe chuck with a spiral-rack-and-pinion displacement mechanism — JQ cams, in which an annular undercut with a depth of more than half the working height of the disc and a cylindrical surface of the spiral disc limited to The end of the disk from the side of the working coils and the end of the undercut provides for a gap excluding the contact of 20 of these surfaces in the loaded so tii N 1J ..

The disadvantage of the known cartridge is an increase in the volumetric and surface concentrations of the stresses of the helix-rack mechanism, due to the inconsistency of the algorithm for changing the pitch of the helix in the helix-rack mechanism to the algorithm for changing the load between the supporting elements.

The purpose of the invention is to increase the reliability and durability of the cartridge by matching the algorithm for changing the pitch in the spiral-rack mechanism to the algorithm for changing the load between the supporting elements.

For this purpose, the guide grooves of the spiral disk and the cam rails are made on an involute with a variable depending on the pitch of the spiral evolute.

Evolute of the evolvent is described by the equation

Claims (2)

a | coh5t. Q is the force acting in the engagement. I f is the projection of the lateral surface of the spiral cutting onto the plane perpendicular to the axis; q (z is the intensity of the distribution of axial forces in the section z; W / lvX, j are coefficients depending on the elastic geometric parameters of cutting and the whole joint} I is the height of the spiral disk, E, Bl are the elastic moduli of the cam and disk material, Z is the height of the material considered sections, Rf is the cross-sectional area of the cam, (z) - F, i (z) 7rf H,) is the cross sectional area of the disk. FIG. 1 presents the proposed cartridge, a general view; on Fig - node a in fig, 1 on an enlarged scale /. FIG. 3 is a profile curve; FIG. 4 view B in FIG. 2 - cam. On the sleeve 1, pressed onto the pizza 2 of the body 3 of the cartridge, the spiral disk k with the groove 5 is centered on the seating surface 6 of the disk A. The depth of the groove 5 h in the known inventions is determined as follows: K. 0.6 And, where H is the working height of the disk Between the cylindrical surface 7 of the spiral disk and the seating surface 6 of the sleeve 1, a gap h is made, the value of which can be determined by the expression, 06 N. The presence of the gap h of the undercut 5 causes a uniform distribution / load between the coils when pinned along hyperbolic cosine and curve and the maximum is approached, for example, a circular arc H, where H - the height of the cam. The optimal nature of the load distribution is ensured by deliberately changing the geometrical parameters of the helix, for example, the helix pitch of the involute with a variable evolute, in accordance with the load variation algorithm for the height of make-up. The current coordinates of the point M (x, y) of the profiling curve in this case depend on the algorithm for changing the radius of the evolute a. As a result of the profiling of the guide grooves of the spiral disk and the slats along the evolute with a variable evolute, each load in any section of the spiral-rack mechanism corresponds to its own step change. Variable tensioning height along the height of screwing up favorably affects the load distribution, thereby reducing the bulk and surface stress concentration, increases the reliability and durability of the cartridge. The step change algorithm correlates with the algorithm (And the load changes along the cutting height. Variable step variation along the cutting height in accordance with the load variation between the supporting elements is provided by profiling the spiral disk grooves and the cam slit in a variable with the variable in evolut step. It should be noted that the variable evolute involute has no analogues in the theory of plane curves. The variable evolute involute is characterized by Rs const and r oo, where R is the radius of the fixed circle, r is glad Moving wheel.The proposed spiral has the following positive properties: 5 levels the load between the bearing elements, increases the strength of the cartridge, increases the bearing capacity of the cartridge, expands the technological capabilities of the cartridge. The profiling of the helix along the variable evolute automatically changes the algorithm for changing the pitch of the screwing height according to the actual loading conditions of the supporting elements of the spiral-rack mechanism. This specificity of evolvent with variable evolute must be taken into account when creating precision spiral-rack turning lathe chucks. This profiling of the spiral eliminates the occurrence of additional loads (the calculation does not provide for loads, and, consequently, the constancy of the magnitude and direction of the calculated load is provided. Correlation of the algorithm — changing the helix pattern to the algorithm of changing the load between the load-carrying elements 30%. Claim of the invention 1. A three-cum-cutting self-centering lathe chuck according to the author St. 384b31, characterized in that, in order to increase the reliability and durability of the cartridge, the equal grooves of the spiral disk and the cams of the cam are made on an involute with a variable obstruction from a step that was spun by the evolute. 2. A turner cartridge according to claim 1, distinguished by the fact that the evolution of the voltage is described by an equation. 1 i. a - Tj: jc- CoHefc,. - nominal pitch of the cutting of the spiral disk Q - force of the actuator in the mesh; f is the projection of the lateral surface of the spiral cutting and the plane perpendicular to the axis; t) - intensity of distribution of axial forces in section z, D. a: coefficients depending on the elastic-geometric parameters of cutting and the entire connection H - height of the spiral disk E E - moduli of elasticity of the material of the cam and disk, X - height of the section under consideration, F - cross-sectional area cam sections F, - FW - fiWlirr () is the cross section area of the disk. Sources of information, those in consideration in the examination, USSR Author's Certificate 631, cl. B 23 B 31/16, 1969.