CN111101168A

CN111101168A - Self-lubricating solid soft metal silver-lead alloy coating structure

Info

Publication number: CN111101168A
Application number: CN201811079061.6A
Authority: CN
Inventors: 田振奎
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-09-17
Filing date: 2018-09-17
Publication date: 2020-05-05

Abstract

The invention provides an application technology of an Ag-Pb alloy coating structure on a friction pair of a plunger pump and an inclined shaft type axial plunger variable motor used in mechanical and aeronautical engineering. The damage of the friction pair is caused by that when the inlet of the pump is under negative pressure and the equipment is stopped and restarted, an oil film does not exist between friction surfaces, the oil distribution disc is adhered with copper, the sliding block is broken off from the plunger head, the machine is stopped, the landing gear of the airplane cannot fall off, and the serious accident of machine damage and human death is caused. The solution is that a layer of silver is plated on the friction surface of the plunger cylinder 9 and the slide block 17, then a layer of lead is plated on the friction surface, and an Ag-Pb alloy film is prepared between the two by an electrochemical method, and the film not only can be self-lubricated in oil-free films and vacuum, but also can embed abrasive particles in oil. The soft metal lead can play a good role in running in, is soft and has low strength, is suitable for making up for the defect of the unevenness of the running end surfaces, and adjusts the thickness of an oil film between the running surfaces to the optimal uniform state.

Description

Self-lubricating solid soft metal silver-lead alloy coating structure

Technical Field

The invention relates to an application technology of a silver-lead coating structure Ag, Ag-Pb and Pb in the electrochemical engineering field of physical chemistry on friction pairs of axial plunger pumps and inclined shaft type axial plunger variable motors of hydraulic equipment in mechanical building engineering and aviation engineering.

Background

Axial plunger pumps and axial plunger variable displacement motors of the oblique type are widely used in engineering construction machinery and aircraft hydraulic systems, such as aircraft landing gear, and the volume efficiency of the pump is reduced due to the early wear of two pairs of friction pairs of plunger cylinder-oil distribution disc and slide block-oblique disc, so that the service life of the pump and the motor is shortened.

The Changjiang crane factory moved from Beijing to Sichuan Luzhou in 1966, and with the continuous updating of products, the requirements on the volume efficiency and the service life of hydraulic elements, particularly oil pumps and oil motors, are higher and higher.

1 first axial plunger Pump Life test

The ZBD40 axial plunger oil pump was bench tested for performance and life in 1972 at 12-1973 at 7-month factory research laboratory, run time 2018 hours. The test conditions are as follows: the inlet oil supply pressure is 2-3Kg/cm²Rotation speed 1520 once 1560 r.p.m, oil temperature 35-45 deg.C, and outlet pressure 210Kg/cm². The test result shows that although the full-load operation is carried out for 2018 hours, the volumetric efficiency is still kept above 96%, the abrasion loss of the plunger and the plunger hole is small, the maximum abrasion loss of the plunger is less than 0.002mm, the abrasion loss of the plunger hole is less than 0.015mm, a silver coating layer of the sliding block falls off, a sealing part leaks oil, and the hydraulic part is not damaged. Tests prove that the full-negative operation life is very long under the condition of oil supply pressure.

2 second axial plunger Pump Life test

Considering that when the ZBD40 axial plunger pump produced by our factory is used on a traveling hydraulic automobile crane, the pump works under the conditions that the vacuum degree is 0-100 mm Hg and the rotation speed is 1500-1600 r.p.m under the self-priming working condition, and under the working condition, the performance of the pump is again how, and whether a weak link exists on the structure, in order to obtain practical materials of the aspect, the bench test of the performance and the service life of the self-priming working condition is carried out on the ZBD40 axial plunger pump again from 8 months to 4 months in 1974. The conditions for this test were: vacuum degree of 50-70 mm Hg at inlet of oil pump and pressure at outlet of oil pump

The rotation speed of the oil pump 1520 and 1560r, p and m, and the oil temperature 45-50 ℃.

Problems observed during the whole experiment:

① oil distribution pan surface finish

Down to

And circle-shaped scratches appear gradually and are adhered with copper in the phenomenon of figure 2.

② plunger cylinder has large abrasion loss, the unevenness of end surface is reduced from 0.003-0.005mm to 0.015-0.018mm, and the phenomena of edge collapse and central bulge are presented, and the figure 3 has circle scratch and the depth reaches 0.02 mm.

Comparison of the volumetric efficiency of the pump over time in two tests fig. 4. Analysis of the results of the two life tests: as can be seen from fig. 4, the volumetric efficiency of the pump does not change much with the operating time under the condition of the supply oil pressure, that is, the life of the oil pump is long, and is estimated to be more than 1 ten thousand hours. And under the working condition that the inlet vacuum degree is 50-70 mmHg, the volumetric efficiency is reduced from 96% to 87.4% after 2000 hours of operation. From the ZBD40 oil-soft double performance and life test conditions, it can be seen that the conditions are the same except for the inlet pressure, and it can be inferred that the volumetric efficiency reduction is due to the self-priming condition. When the oil pump inlet supplies oil pressure

Fall to self-suction working condition

The oil film itself is known by calculation to have a push-away force

Down to

The difference between two aspects

. When the ZBD oil pump is in a self-priming working condition, the thickness of the oil film is also thinned due to the reduction of the pushing force of the oil film, the axial pressure of the end face of the plunger cylinder is high, the bearing capacity of the oil film cannot resist the pressure of the plunger cylinder, the direct contact between the end face of the plunger cylinder and the oil distribution disc is changed into dry friction, high temperature is generated at high rotating speed, and therefore a friction pair generates gluing, copper on the end face of the plunger cylinder is easily adhered to the oil distribution disc, and the reason that a ring-shaped groove is formed on the friction end faces of the oil distribution disc and the plunger cylinder under the self-priming working condition and the copper is adhered to the oil distribution disc is generated, so that the external leakage of the pump is rapidly increased, and the volumetric efficiency of the pump.

3 third axial plunger pump life test

According to the analysis of the results of the previous two life tests, the materials of the plating layers on the plunger cylinder and the sliding block are required to have small friction coefficient, good gluing resistance, strength and embedding property, high thermal conductivity, large allowable load, large allowable sliding speed and large limit PV value on the iron-based alloy, and are shown in the tables 1 and 2.

Pure metallic silver and lead were selected according to these conditions, and a silver film of 0.02 to 0.03mm thickness was coated on the friction end face of the plunger cylinder, and then a lead film of 0.01 to 0.02mm thickness was coated immediately on the surface of the silver. To verify the effect, ZBD40 axial plunger pumps were bench tested for performance and life between 1979 and 1980,

month

5 and 20, run time 2289.9 hours, test conditions: the inlet vacuum degree is 50-70 mm Hg, the rotation speed is 1520 and 1560rpm, the oil temperature is 45-50 ℃, and the outlet pressure is 210kg/cm². The test pieces were disassembled at 100 hours, 300 hours, and 800 hours … … 2289.9 hours, and precision measurements were made. From several times of disassembly, the silver coating on the end face of the plunger cylinder is hardly worn, the surface of the oil distribution plate is also hardly worn, only slight ring particles are worn, and the phenomena of silver adhesion and silver removal layer are avoided, so that the pump operates for 2289.9 hoursThe volumetric efficiency is still over 93 percent, the change curve of the volumetric efficiency is shown in figure 5, the surface condition of the oil distribution disc after 2289.9 hours of operation under the self-priming working condition is shown in figure 6, and the surface condition of the plunger cylinder is shown in figure 7. The ZBD40 oil pump three life test conditions and results are shown in tables 3 and 4.

Disclosure of Invention

The present invention provides a self-lubricating solid soft metal silver-lead alloy coating to prevent serious accidents of mechanical damage and death caused by oil film loss when the friction pair is under self-priming negative pressure and started instantly.

The invention solves the problem by adopting the technical method. Since lubrication is a solid surface effect, the ability to adsorb and retain an oil film can be improved by forming a silver-lead alloy layer on the surface of silver. The specific technological process includes electroplating silver layer of 0.02-0.03mm thickness on the end of plunger cylinder and obtaining current density

Using high current impact and current density in the last five minutes of silver plating

Forming coarse porous crystals on the surface of the silver layer; then immediately plating a 2-3 minute lead layer. Thus, a silver-lead alloy of fig. 8 was produced.

The invention has the beneficial effects that: pumping ZBD40 from August of nine-seven and nine-years to Q₂And (4) carrying out practical condition examination on the-5 type hydraulic automobile crane until no problem is found. The ZBD75 pump was mounted on a QY8, QY16 crane, and the actual work was over five years, which was good from the present point of view and was put into mass production. The friction pair composed of the sliding block 17, the figure 1 and the sloping cam plate 18 is characterized in that a silver-lead film is plated on the end face of the sliding block, and the friction pair is disassembled and checked after working for ten years, so that the silver adhesion phenomenon is not found, and the friction pair has good effect. In addition to the two friction pairs mentioned above, a pair of friction pairs consisting of a rubber sealing ring 20 and a hard chromium-coated driving sleeve 3 (fig. 1) is provided on the ZBD40 pump, which pairs during operation are found to be rough groove scuffing due to wear of the driving sleeveThe rubber sealing ring is a long-standing problem, the friction pair has the effect of sealing oil without oil leakage, dry friction is inevitably generated at the position, the rotating speed of the transmission shaft sleeve is high, the shaft sleeve is easy to wear, in order to prolong the service life of the friction pair, the oil leakage is not quickly worn, a layer of soft metal silver film is plated on the friction surface of the transmission shaft sleeve, and the transmission shaft sleeve runs for 1111.3 hours under rated load without oil leakage. The oil pump is disassembled and the contact part of the shaft sleeve and the sealing lip edge is observed to have a smooth annular zone with the width of about 1.5mm and the depth of 0.015mm, and the sealing lip edge is not damaged, which indicates that the application effect of the electroplated soft metal silver film on the friction pair is satisfactory.

Drawings

FIG. 1 shows a ZBD type plunger pump

1 tensioning bolt, 2 spring, 3 transmission shaft sleeve, 4 bearing, 5 transmission shaft, 6 bearing, 7 pump body, 8 thrust plate, 9 plunger cylinder, 10 plunger, 11 spring, 12 positioning sleeve, 13 bearing, 14 adjusting pad, 15 spherical hinge, 16 pressure plate, 17 sliding block, 18 swash plate, 19 pump cover, 20 oil seal

FIG. 2 shows the oil distribution disc in a self-priming condition after 2000 hours of operation

FIG. 3 is a diagram of the plunger cylinder oil distribution end surface condition after 2000 hours of pump operation in self-priming operation

FIG. 4 shows that the oil pump of ZBD40 is at the oil supply pressure of 2-3Kg/cm²Comparison graph of volumetric efficiency under working condition and volumetric efficiency under self-priming (vacuum degree of 50-70 mm Hg) working condition with variation of running time

FIG. 5 is a graph showing the change in volumetric efficiency

FIG. 6 is a live view of the port plate after 2289.9 hours of operation in a self-priming condition

FIG. 7 shows the plunger cylinder end surface condition after 2289.9 hours of pump operation in self-priming operation

FIG. 8 is a graph showing the relationship between the microstructure of the silver plating layer and the properties of the input current and the magnitude of the current density, 80

TABLE 1 Properties of bearing metals

TABLE 2 Properties of Soft metals

TABLE 3 ZBD40 oil Pump three-time Performance and Life test conditions

TABLE 4 ZBD40 oil Pump three-time Performance and Life test results

Detailed Description

Silver-lead electroplating process

1 silver plating process flow

Working conditions

TABLE 1

Bearing material	Resistance to gluing	Oiliness property	Corrosion resistance	Strength of	Melting Point	Embeddability	Degree of binding
								Bus alloy	3	2	1	4	3	1	1
Cadmium-based alloy	3	3	3	3	2	2	2
								Copper-lead alloy	2	1	2	2	1	3	3
Pure plating	1	4	1	1	1	3	4
								Silver-lead alloy	1	2	1	1	1	3	5

The larger the number, the worse the performance.

TABLE 2

TABLE 3

TABLE 4

Claims

1. The self-lubricating solid soft metal silver-lead coating structure (Ag, Ag-Pb, Pb) comprises a self-lubricating solid soft metal silver and lead coating, and a layer of (Ag-Pb) alloy phase is arranged in the middle, and is characterized in that: the transition silver-lead (Ag-Pb) self-lubricating solid soft metal alloy coating is prepared between the bottom silver film and the surface lead film, the performance of the coating is superior to that of a silver coating and a lead coating, the silver-lead alloy coating not only can self-lubricate in a dry friction vacuum without an oil film, but also can embed abrasive particles in hydraulic oil, and the surface of a friction pair is prevented from generating a circular scratch; the soft metal lead has good gluing resistance and oiliness, prevents the friction pair from being sintered and seized, can play a good grinding role in the running-in process, is soft and low-strength metal, can adapt to running to make up the defect of unevenness of end faces, and can adjust the thickness of an oil film between grinding faces to an optimal uniform state.

2. A layer of 0.02-0.03mm thick silver layer is plated on the friction end face of a plunger cylinder of a ZBD type axial plunger pump in a figure 1 and the friction end face of a plunger cylinder of an inclined axial plunger variable motor, and then a layer of 0.01-0.02mm thick self-lubricating solid soft metal lead is plated immediately, and the composite plating layer is characterized in that scratches with the depth of 0.02mm or internal leakage caused by high-low pressure hydraulic oil circulation due to grooves at 8 in a figure 1 of an oil distribution disc and the friction end of the plunger cylinder can be prevented, so that the volumetric efficiency of the pump is reduced.

3. A self-lubricating solid soft metal lead with the thickness of 0.01-0.02mm is plated immediately after a silver layer with the thickness of 0.02-0.03mm is plated on a sliding block friction surface 17 in a ZBD type axial plunger pump and a sliding block friction surface of an inclined axial variable motor, and the self-lubricating solid soft metal lead is characterized in that the composite metal film not only can self-lubricate in an oil-free film or vacuum, but also can embed abrasive particles in oil, the higher parts are ground off, the lower parts are left, and the thickness of an oil film between the running-in surfaces is adjusted to the optimal state.