SU1425051A1 - Method of finish working of machine part surface - Google Patents

Abstract

The invention relates to abrasive machining and can be used for machining parts of spool and plunger friction pairs of hydraulic machines. The purpose of the invention is to improve the performance characteristics of the treated surfaces. For this, the treatment is carried out with a grinding wheel impregnated with amides of stearic and palmitic acids. Into the impregnated casting composition, the active seronases are added, the ayushie additives in the following ratio of ingredients, May. %: amides of saturated fatty acids (stearic and palmitic) p yes С | 6 ... С | 8 65-90; sulfur 5-15; sodium thiosulfate or potassium rhodanate or sodium rhodanate 5-20. Cutting modes: cutting speed, m / s, 0.1-0.17, cutting depth, mm, 0.02-0.03, the number of nursing moves 2-4. As a result, conditions are created for the surface diffusion saturation of the workpiece with sulfur. 1 tab. with s

Description

4: ND SP O JV

The invention relates to abrasive machining and can be used, in particular, for finishing the surface of parts of spool and plunger friction pairs of hydraulic machines.

The aim of the invention is to improve the operational characteristics of the surface of parts machined with a grinding wheel.

j The proposed method of drying is provided with a grinding wheel impregnated with amine: stearic and palmitic acids, while the active seron-saturated additives are introduced into the impregnated composition: sodium thiosulfate or potassium is tribal, or sodium is born at the next, Eat ratio of ingredients, May. %:; Amides of saturated fatty acids (stearic and palmitic) p yes C, in ... C, 865-90

 Sulfur 5-15

: Sodium thiosulfate or Icalium rhodium, or

{sodium Rodanist5-20

I The treatment is carried out on cutting modes that provide the conditions for surface diffusion of sulfur with gray sulfur: Cutting speed, m / s, 0.1-0.17; depth of cut, mm, 0.02-0.03; number of moves 2-4.

Example. Samples are processed; of steel 45 of size 150X30X10 on a surface grinding machine of the model 370 with the 24A25CM16K5 brand for the following cutting modes: wheel speed 4 30 m / s, detail speed V 0.14 m / s, cutting depth, 02-10 m, two nursing strokes. Impregnated composition contains May. %:

Fatty acids / acids (stearic and palmitic) p yes Cifi ... Ci865-90

Sulfur 5-15

Sulfur Additives (sodium thiosulfate or potassium rhodium, or sodium rhodium) 5-20

When checking the efficiency of the method, the output parameters are the durability of the wheel, the specific productivity, grinding power, and the total depth of the diffusion sulfide layer.

The durability of the circles is determined by the number of: table moves during mortise grinding with the depth depth cutter assignment for each stroke under the specified processing conditions from the start of work until blunting - the appearance of burns on the sample surface.

For specific performance take the ratio Omet / Ocher for the period of resistance of the circle.

 - the volume (m) of the removed metal is determined by the product of the area Sm-i

grinding the surface to a depth of the metal: h / d.

Odr - the volume (m) of a worn-out wheel - is defined as the product of the area of the working surface of the circle by the amount of wear along the radius of the circle: Okr-O-B-a, where D is the diameter of the circle, m; B - the width of the circle, m; a - circle wear, m

Grinding power is determined by watts. meter connected to the power wiring of the grinding machine.

The total depth of the diffusion sulfide layer is determined on a scanning X-ray microanalyzer.

The test results are shown in the table.

Since the use of all the additives yielded similar results, the table shows only the data on the treatment with impregnated circles, the sodium-0-thiosulfate serves as a sulfur-containing additive.

Comparative tests have shown that composition 5 is the best option.

In the course of processing, the impregnating composition, enveloping the grains of the circle, ensures a high cooling rate of the cutting grain, chips and the workpiece, reducing the heat intensity of the cutting process. By creating an interlayer between the cutting chips and the material of the circle, this composition prevents the adhesion of chips 0 to the circle, and promotes its removal from the cutting zone under the action of centrifugal forces. Antifriction properties of the composition reduce cutting forces.

Significant and sustained impact on

performance improvement

5 machined surfaces of machine parts

provides diffusion sulfide

“Break-in film 3 microns thick.

Such a film is formed if, during the finishing process, the maximum temperature in the zone of contact of the grinding wheel with the workpiece reaches 800-900 ° C, and the residence time of the surface layer of the part at a temperature above 200 ° C should be more or equal to 0.3 s .

5 These conditions are met when machining parts from various machine-building materials in the modes indicated above. The choice of a particular mode value depends on the thermophysical properties and workability of the material.

0 The choice of the range of cutting depths /: 0.02-0.03 mm is determined by the requirements to the quality of processing (roughness of the surface layer, accuracy), while ensuring the contact temperatures in the range of 800-900 ° C.

At 015 mm, contact temperatures when grinding most engineering materials do not exceed 600-700 ° C.

An increase of / more than 0.035 mm leads to a decrease in the accuracy characteristics of parts by 1-2 quality levels.

The value of V most significantly affects the duration of heat exposure in the cutting zone and, depending on the thermophysical properties and workability of the material, is assigned in the range of l-0.17 m / s.

For example, for the treatment of cast iron, the SC20 is assigned to the Hub 0.1 m / s, for the steel 45 0.14 m / s, for the CHN steel 0.17 m / s.

To ensure the residence time of the surface layer of the material at a temperature above 200 ° C for more than 0.3 seconds, it is necessary from 2 to 4 nursing strokes. An increase in the number of care courses above four leads to an insignificant increase in the thickness of the sulfide run-in film with a significant decrease in productivity.

The combination of such factors as the temperature of 900-1000 ° C and high pressure in the cutting zone, the juvenile surface of the workpiece, the presence in the impregnating composition of active sulfur-containing weights, the duration of heat power effect, due to the low speed of the part (Og 0.1 - 0 , 17 m / s) and the course of care, creates conditions for the occurrence of the chemical-thermal sulphidation process. The thin film (13–15 µm) formed by the diffusion film creates favorable conditions for the burn-in of the machined part.

To study this effect, according to the proposed method, test rollers made of steel 45 were processed for

friction machine SMC-2. The impregnated composition contained 80% acid amides, 10% sulfur, 10% sodium thiosulfate. Processing mode: Uh 30 m / s, 15 m / s / 0.02 mm, two nursing courses.

Metallographic studies of the surface sulfide layer were dried on a microanalyzer.

Tests have shown that the period of running-in of the rollers processed by the proposed method is 4-6 times less than the known one.

Claims (1)

Invention Formula The method of finishing processing the surfaces of machine parts, in which the treatment is carried out with a grinding wheel impregnated with amides of stearic and palmitic acids, at a cutting speed of 0.1-0.17 m / s and a cutting depth of 0.02-0.03 mm, characterized in that, in order to improve the performance characteristics of the treated surfaces, active sodium sulfonate or potassium, or sodium boric acid, is additionally introduced into the impregnating composition in the following ratio of ingredients, May. %: Amides of saturated fatty acids (stearic and palmitic) p yes Ci6 ... Ci865-90 Sulfur 5-15 Sodium thiosulfate or potassium rhodium, or sodium rhodium 5-20 however, the number of care moves is chosen to be 2-4.