SU837806A1 - Work-lapping method - Google Patents

Description

The invention relates to abrasive machining and can be used in fine-tuning parts from diamond, sapphire, ruby, corundum, and other fragile materials. The known method of finishing the parts, in which the relative movement of parts and ground grinding is carried out and one of the processing parameters 1 is changed. However, due to cycling changes in the speed of moving parts along the grinding, a high quality of the surface layer of the parts satisfying the technical conditions . The purpose of the invention is to show the quality of processing. The goal is achieved by the fact that in the quality of the varying processing parameter, the stiffness characteristic is chosen at least ONE priter, based on the following equation: (... itO where k (t) is the stiffness value of priter; t is time; and are proportionality coefficients The stiffness characteristic of the priter can vary according to a stepwise, linear, exponential law. A change in the stiffness characteristic may be accompanied by an additional change in the speed of the relative movement of the part along the priter (priter), back to prop The drawing shows the scheme for implementing the method. The priter consists of a finishing disc 1 connected to the priter base 2 by means of chassis screws 3. An elastic system of variable stiffness is placed between the disk 1 and the priter base 2, which is a set of springs 4 of various sizes As the disc 1 approaches to the ground of the lap 2 due to the tightening of the screws 3, the hardness of the lap changes by changing the springs of different heights in turn. This provides a stepwise law of variation in stiffness values depending on the approach. Numerous experimental data confirm the dependence of the refinement process on the elastic characteristics of the machine-ground-detail elements included in the system. Physically, this is due to the fact that the compliance of the grinding-abrasive part-of-part grain, which is part of the machine-grinding-part system, depends on the physical and mechanical properties of the system. The elastic moduli of the two elements of the system determine the wear resistance of the third element of the system. For a number of combinations of materials, there is a tendency to increase the energy required to destroy the materials of one of the element systems, i.e. an increase in the wear resistance of a BQ or priping part B with an increase in the sum of the elastic moduli values of the materials of the other two elements of this system, Tables 1 and 2 A large sum of elastic moduli for a system of bodies indicates its small compliance with the stored elastic energy strain in the system. This means that the likelihood and role of the brittle fracture of the elements of the system decreases and the energy consumption for the destruction of materials increases relatively, which is accompanied by an increase in the values of Vl (or B ,,). The results of the analysis of the experiments on wear of silicon on cast iron pritir are presented in Table 3. Thus, with the nature of the abrasive 24A unchanged, an increase in its graininess (from M7 to M28) contributes to an increase in the compliance of the body-abrasive-part system (due to greater absolute deformation of abrasive grains) . Therefore, a larger supply of elastic energy 4 appears in it and, consequently, the action of the brittle mechanism of destruction is enhanced, which is accompanied by a decrease in the values of BO and BP, the same is observed when using diamond. A similar pattern can be found when comparing data for corundum 2AA (M14) and diamond (AFM 10/7) of approximately the same grain size. In the latter case, with a higher modulus of elasticity of a diamond, its deformation (all other things being equal, less than for corundum, a smaller amount of elastic energy, a brittle fracture mechanism more pronounced and a larger value B. However, under these conditions This is due to the manifestation of a special kinetically brittle fracture, primarily for the weakest link of the system, the grinding and abrasive interlayer. For these conditions, the cast iron grinding is the weakest element, because The process of debugging causes forced oscillations in the machine-grinding-detail system in the direction perpendicular to the machined planes. The formulas for determining the amplitude and frequency of these oscillations are as follows: A g ..., °,;, (k-mp) (i-p2 / u}) where Hell is the static deviation of the mass m (lapped) under the action of the force Р „ГС the frequency of its own coefficients Im. oscillations in the absence of attenuation; the rigidity of the system; the attenuation coefficient. The lesser rigidity (greater flexibility) of the system leads due to an increase amplitudes and decreasing frequencies to increase oli mikrovykalyvani material removal in the workpiece, which means less wear resistance, and high rigidity reduces the amplitude and increases the frequency, which leads to an increase in the proportion microcutting and, consequently, wear resistance increased. Numerous studies show that surfaces treated with a predominance of micro-gouging are significantly inferior in terms of the accuracy of the shape and depth of the broken layer of surfaces with a predominance of micro-cutting.

5 8378066

Dependence of wear resistance of cast iron - ECJ at Р .39.2 kPa, Vcp 1.18 m / s.

foot priter Bp from the modulus of elasticity O material sample Her and mineral table.1.

19.6 m / s is presented on

Table I

1-50

Silicon (24AM28)

220

Steel Dependence of wear resistance of a steel sample Vl on the Modulus of elasticity of materials of the primer Ep and mineral ЕU

Glass 80 Corundum 280 360 323

Cast iron PO Diamond 280 390 362 Changes in values of B and B for silicon specimen and cast iron gapper depending on the properties of the mineral

Corundum (abrasive) 24 AM7

PC.

24AM14

Corundum. 280

430

52

500

93.2 (24AM28) (24AM28)

Table 3

28.9132.4

19,467.7 at P 39.2 kPa,. 0.67 m / s, motx Yu mAs is presented in Table 2. Table 2 (abrasive) when V «var, 39.2 kPa, 1.18 m / s, 19.6 m / s are presented in table 3

Diamond (abrasive) AFM 10/7% ... ACM 20/14

Corundum (abrasive) 24AM7

24AM14 24AM28

Diamond (abrasive) ACM 10/7

X - Pasta

Claims (5)

XX - Suspension, claims 1. The method of finishing parts, in which the relative movement of parts and groundings is carried out and one of the processing parameters is changed, so that, in order to improve the quality of processing , as the variable processing parameter, select the stiffness characteristic of at least one priter based on the following equation: n kCt) (/ -. a, - where k (t) is the stiffness value of the priter; t is the time; a: - coefficients of proportionality. 2. Method POP1, characterized in that Continued table. 3 14.1 83.4 7.8 161.9 99.1 97.1 108.9 kyu of stiffness is changed stepwise. 3. The method according to claim 1, so that the stiffness characteristic is changed according to a linear law. 4. Method according to claim 1, characterized in that the stiffness characteristic is changed exponentially. 5. The method according to claim 1 is also distinguished by the fact that it additionally changes the speed of relative motion. The pritier details are inversely proportional to the characteristics of rigidity. Sources of information taken into account in the examination 1. Author sivdedelstvo USSR № 327989, cl. B 24 B 7/04, 1970. WITH