WO2008141592A1

WO2008141592A1 - A lead-free self-lubricating bearing and its producing method

Info

Publication number: WO2008141592A1
Application number: PCT/CN2008/071081
Authority: WO
Inventors: Zhihua Sun
Original assignee: Zhejiang Changsheng Sliding Bearing Co., Ltd
Priority date: 2007-05-24
Filing date: 2008-05-26
Publication date: 2008-11-27
Also published as: CA2670200C; CN101074702A; CN101074702B; CA2670200A1

Abstract

A lead-free self-lubricating bearing is mainly made up of a metal base plate, a global porous bronze powder layer bonded on the base plate and a wear-resistance plastic layer which is sintered and covered on the bronze powder layer. A coiling procedure is used during producing the bearing. There is no lead in the bronze powder layer or the plastic layer. And the plastic layer includes powder of PPS, EKONOL, MoS2, PTFE and aramid fiber. A method producing said bearing is also disclosed. It includes bonding the bronze powder layer on the metal plate, producing a viscid spreadable mush of the plastic layer, and rolling after spreading,drying, mid-rolling, bonding, and final-rolling. The bearing has better wear-resistance property and can be applied in the fields such as food, pharmacy, and so on, due to lead-free.

Description

Lead-free self-lubricating bearing and manufacturing method thereof

Technical field

The present invention relates to a plain bearing, and more particularly to a lead-free self-lubricating bearing made of a three-layer composite.

Background technique

The DU bearing, which was introduced as early as the 1970s, is such a three-layer composite bearing, but because its friction layer lining is sintered from a mixture of polytetrafluoroethylene (PTFE) and lead (P _b ). Although it can replace the copper alloy bushing in some application fields and achieve the purpose of reducing cost and improving service life, since it contains metal lead component in the friction layer of the bearing, the lead and lead compounds are toxic substances due to When the bearing is working, it will cause abrasive wear to cause lead-containing powder and lead gas to escape in high temperature, and the recovery of used bearings will cause harm to the human body and the environment. With the improvement of environmental awareness, this product is Use in machinery manufacturing such as automobiles, food, pharmaceuticals, home appliances, fitness, office, beverages, etc. is excluded or restricted. We have noticed that there are corresponding environmental standards in Europe and the United States. For example, the European R0HS heavy metals and hazardous substances standards have specifically requested this.

Similar to DU bearing, the plastic layer, that is, the anti-friction and wear-resistant working layer, is an ideal ideal for traditional products as long as it effectively overcomes the key problem of not containing heavy metals such as lead and harmful substances and achieves satisfactory results. Upgraded product.

The main object of the present invention is to explore and invent the composition of the lining layer (frictional plastic layer) of the bearing, not only to remove the harmful substance-lead used in the DU bearing, but also to use the polymer composed of the following materials instead of the low friction. The lead of the coefficient, at the same time makes the mechanical, physical and friction properties of the bearing better than the DU bearing;

Polytetrafluoroethylene (PTFE), which has excellent friction properties, is the smallest of the plastics. It is often used as a sliding bearing lining lubricant and can be used as a filler with a low coefficient of friction, but if used alone, Mechanical strength and elastic modulus are extremely poor, so there are not many opportunities for using Teflon alone. For practical applications, it is well known that it is necessary to apply wear-resistant fillers and/or other materials that enhance the lining in applications where high-load, low-speed or light-load high-speed motion is required.

Polystyrene, EK0N0I for short, English name: Aromatic Polyester, compared with other engineering plastics, the most characteristic is the metal-like properties and the highest thermal conductivity, in addition to excellent dimensional stability, high compression resistance Creep, abrasion resistance and excellent self-lubricating properties and hardness, these features are just effective in overcoming the problems of using Teflon alone. Polyimide, abbreviated as PI, has similar properties and is therefore an alternative material. Polyphenylene sulfide, referred to as PPS, English name: Polyphenylene Sulfide, is a high temperature resistant thermoplastic polymer. It has excellent heat resistance, corrosion resistance, chemical stability and high adhesion to metals and various powders and fibers. It is the best choice as a high temperature binder. Tests have shown that the plastic friction layer after the addition of polyphenylene sulfide improves the fatigue strength and reduces the cavitation. However, polyphenylene sulfide is first chemically crosslinked. Chemical crosslinking is a mature technology, usually requiring the addition of magnesium fluoride. Equal accelerator, cross-linking time 20 minutes.

Aramid fiber, trade name kevlar (produced by DuPont, USA), English name: Aramid Fibre, is a high-performance organic fiber with ultra-high strength, ultra-high modulus, high temperature resistance and light weight. Its strength is more than 3 times higher than that of ordinary organic fibers, and the modulus is 10 times that of nylon and 9 times that of polyester. Aramid fiber has good impact and fatigue resistance, good dielectric properties, chemical stability, low expansion, low thermal conductivity, non-combustible, non-melting and so on. Aramid fiber filling in PTFE can greatly enhance the mechanical properties, load bearing capacity and friction and wear properties of the bearing.

Molybdenum disulfide, referred to as MoS ₂ , is a layered structure of hexagonal crystal system, which is easy to slip from layer to layer, so it has good self-lubricating property, and it can be strongly adsorbed on metal surface even when rubbed. It is also not easy to break, so it can withstand higher loads. The data shows that the 2. 5 μm thick MoS ₂ film can withstand pressures above 2800 MP _a while experiencing a friction speed of 40 m/s. After the addition, the friction and wear are significantly improved, and the initial wear of the bearing is reduced, and sometimes the MoS ₂ can be replaced by graphite.

The conventionally used sliding bearing and DU bearing described in the above technical background fully demonstrate the progress of human beings in the development of science and technology. The main object of the present invention is to explore and invent the composition of the lead-free formulation of the self-lubricating bearing friction lining layer, while at the same time making the mechanical, physical and frictional properties of the bearing superior to the DU bearing. The ultimate goal is to find a three-layer composite lead-free self-lubricating bearing and its manufacturing method.

Summary of the invention

The object of the present invention is to provide a lead-free self-lubricating bearing and a manufacturing method thereof. The lead-free self-lubricating bearing can not only work under the lubrication condition of the oil medium, but also has corrosion resistance, and can also be less oily or even less lubricated in lubrication conditions. Working under dry friction, especially its lead and lead-free compounds, can meet the requirements of European R0HS heavy metals and hazardous substances, self-lubricating bearings, can be widely used in automotive, food, pharmaceutical, home appliances, beverages, office medical machinery, etc. In the manufacturing industry.

The object of the present invention is achieved by the following technical solutions: The lead-free self-lubricating bearing is mainly composed of a metal substrate, a spherical porous copper powder layer sintered on the substrate, and a friction-reducing plastic which penetrates and covers the copper powder layer. Layer composition, and adopting a rolling process to manufacture a sliding bearing; characterized in that the spherical bronze powder does not contain lead in the lead and the friction layer plastic formulation; the antifriction and wear resistant plastic layer is the polymerization of the bearing lining layer The material composition is 10-20% by weight of polyphenylene sulfide ultrafine powder, 10~20% of polyphenylene ultrafine powder, 10-20% of aramid fiber, and fiber length of 40~120 μm. Two The ultrafine powder of molybdenum sulfide is 6 to 10%, and the rest is ultrafine powder of polytetrafluoroethylene.

The metal substrate is a steel coil tape made of high-quality low-carbon steel, the width of the steel coil is 150~300 mm, and the thickness is 0. 25~2. 70 let, and copper plating on the surface, copper plating layer The thickness is 4 to 6 μm _; the spherical copper powder grade sintered on the metal substrate is selected to be CuS _n 8P or CuS _n 10 .

A method of manufacturing a lead-free self-lubricating bearing, the method comprising:

A. Select the steel plate with SAE1010 or SAE1008 and SPCC as the metal substrate;

B, the lead-free spherical bronze powder layer is sintered on the metal substrate of the steel coil with a spherical diameter of 60~140 μ πι and a sintered thickness of 0. 25~0.

C. A spreadable paste-like software for making anti-friction and wear-resistant layers:

(1) Polyphenylene sulfide chemical cross-linking, because it is a well-known mature technology, it will not be described in detail here;

(2) powder and fiber ingredients, powdered according to the aforementioned weight ratio;

(3) stirring, mixing the good powder with the fiber and stirring at least three times, each time 5 to 10 minutes, into a mixture, the speed of the mixer is 2000~4000r/min, at least three times, and the mesh is more than 100 mesh;

(4) Preparing a spreadable soft body, mixing 1000 g of the mixture powder with 800 g of a solid content of 60% polytetrafluoroethylene emulsion, stirring in a mixer of 20 to 60 r/min for 5 to 10 min, and the ambient temperature is suitable at 15 ~25 ° C;

(5) In order to make the paste-like soft body have good ductility of the roll on the ball powder sintering belt, the powder mixture and the polytetrafluoroethylene emulsion must be added with 4~6 % ethanol in an appropriate amount to make the software. More soft.

D. Paving and rolling, the paste-like soft body is automatically rolled on the copper powder layer of the two-layer composite porous ball powder belt on the assembly line, so that a part of it penetrates into the pores of the porous spherical bronze powder and leaves a layer of lining covering the ball. The thickness of the cover layer is usually 0. 20mm;

E, drying, baking at 220-280 ° C for 15-25 minutes, the water in the polytetrafluoroethylene emulsion is completely volatilized;

F, medium rolling, the dried sheet is subjected to a single rolling, the rolling amount is 0. 015-0. 03mm, to increase the density and bonding force of the polytetrafluoroethylene in the pores of the copper ball powder;

G, sintering, sintering of the plastic friction layer in the channel type nitrogen gas protection sintering furnace, followed by three processes of preheating, heating and heat preservation; sintering heating temperature 380-390 ° C, total time 15-25 min, wherein sintering preheating The temperature is in the range of 8 to 10 min. In order to prevent the strip from being oxidized during the sintering process, nitrogen is used as a shielding gas in the furnace, and the purity thereof is 99.9 % or more, and the flow rate of the different sintering furnaces is not oxidized to a minimum flow rate;

H, the final rolling, the strip after the sintering, the final rolling to the finished sheet, the minimum rolling 0. 02mm or more;

I. Winding, the completed three-layer composite lead-free self-lubricating finished strip is neatly received on the winder, and is unloaded after being bundled and fixed; J. Stripping material with strips, according to the bearing specification requirements, for the large-volume products, the corresponding three-layer composite lead-free self-lubricating coils should be selected and unwound into strips of the same width or different width and rolled into coils;

κ, bearing manufacturing, according to the requirements of the cutting into strips of the three-layer composite lead-free self-lubricating bearing processing on the automatic molding machine; for small batch products, not suitable for operation on the automatic molding machine, you can follow the routine The rolling bearing manufacturing process uses a conventional equipment to complete the three-layer composite lead-free self-lubricating bearing finished product.

The invention sinters a layer of lead-free spherical bronze powder on the metal substrate of the steel coil, and the sintering furnace adopts a channel type hydrogen-nitrogen mixed atmosphere protection furnace, the hydrogen is 50%, the nitrogen is 50%, and the sintering time is 880~900°. 8 to 10 minutes in C; during the powder and fiber compounding process, it is possible to add a pigment which has a certain color to the bearing finished lining layer and is resistant to 400 ° C sintering;

The material composition of the anti-friction and wear-resistant plastic layer is further optimized as described above, in particular, the high-performance organic fiber kevlar is added, and the friction and wear, fatigue strength and bearing capacity of the bearing are greatly improved.

The metal substrate of the present invention adopts a steel coil, and the manufacturing process of the entire three-layer composite material realizes the flow of water. The whole coil of steel tape ordered from the steel mill is copper plated and installed on the unwinder. After leveling, the copper powder is automatically laid, sintered and rolled into a two-layer composite porous ball powder belt; After the soft anti-friction and wear-resistant plastic layer is dried, medium-rolled, sintered, and finally rolled until winding, the whole process of three-layer composite self-lubricating bearing material flow production is completed.

A three-layer composite self-lubricating lead-free bearing made as described above, named CSB-50.

The invention overcomes the shortcomings of the composite bearing friction plastic layer which is not suitable for use in automobile, food, pharmaceutical, home appliance, office, beverage and other mechanical manufacturing industries because of lead-containing; has the advantages of simple product structure, good use effect, long service life and manufacturing process Simple, reasonable and so on. The CSB-50 three-layer composite lead-free self-lubricating bearing of the invention is compared with the DU bearing on the market under the same three test conditions, and the test results are as follows:

(1) Contrast under M2000 friction and wear tester (F=196N, V=0. 4m/s, time 120 minutes)

(2) Comparison under the MMU-12 end face friction and wear tester (dry friction P=8N/mm ² , V=0. 2m/s, time 180 minutes)

Bearing type friction coefficient ( ) Temperature ( °C ) Wear amount ( μ m) DU 0. 13 93 16 on the market CSB-50 0.12 87 11

(3) Ultrasonic versus PTFE friction layer weight loss test

Vibration frequency 20KHz, amplitude 50μπι, medium: water, gap 1.3 let, time 10 minutes.

From the above three different test results, the friction wear performance of CSB-50 lead-free self-lubricating bearings is significantly better than that of DU bearings on the market.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view of the process flow of the present invention.

detailed description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The present invention is mainly composed of a metal substrate, a spherical porous copper powder layer sintered on the substrate, and a friction-reducing and wear-resistant plastic layer which penetrates and covers the copper powder layer, and Using a rolling process to produce a sliding bearing; the spherical bronze powder does not contain lead in the lead and friction layer plastic formulation; the friction reducing wear resistant plastic layer is the polymer material of the bearing lining layer, by weight It is 10~20% of polyphenylene sulfide ultrafine powder, 10~20% of polyphenylene ultrafine powder, 10~20% of aramid fiber, fiber length is 40~120μπι, molybdenum disulfide ultrafine powder 6~ 10%, the rest is ultra-fine powder of polytetrafluoroethylene.

The metal substrate is a steel coil made of high-quality low-carbon steel. The width of the steel coil is 150~300mm, the thickness is 0.25~2.70, and the surface is plated with copper. The thickness of the copper plating layer is 4~ 6μπι _; the spherical copper powder grade sintered on the metal substrate is selected as CuS _n 8P or CuS _n 10 .

The method for manufacturing a lead-free self-lubricating bearing according to the present invention comprises the following steps, as shown in FIG. 1:

B. Sintering a lead-free spherical bronze powder layer with a spherical diameter of 60~140μπι and a sintered thickness of 0.25~0.40 on the metal substrate of the steel coil, and the sintering furnace adopts a channel type hydrogen-nitrogen mixed atmosphere protection furnace, and the hydrogen gas is 50. %, nitrogen is 50%, sintering time is 880~900 °C for 8~10 minutes;

(1) chemical crosslinking of polyphenylene sulfide;

(2) Powder and fiber ingredients, powders are added according to the above weight ratio, and if necessary, a pigment which has a certain color and a 400 ° C sintering resistance can be added; (3) stirring, mixing the mixture of the powder and the fiber three times, each time for 5 to 10 minutes, into a mixture, the speed of the mixer is 2000~4000r/min, three times of sieving, and the mesh size is above 100;

I. Winding, the completed three-layer composite lead-free self-lubricating finished strip is neatly received on the winder, and is unloaded after being bundled and fixed;

J. Stripping material with strips, according to the bearing specification requirements, for the large-volume products, the corresponding three-layer composite lead-free self-lubricating coil material should be selected and unrolled into strips of the same width or different width and rolled into coil materials;

K, bearing manufacturing, according to the requirements of the slitting into a strip of material on the automatic molding machine to complete the three-layer composite lead-free self-lubricating bearing processing process; for small batch products, not suitable for automatic molding machine operation, you can follow the routine The rolling bearing manufacturing process uses a conventional equipment to complete the three-layer composite lead-free self-lubricating bearing finished product.

In the specific implementation of the present invention, the preferred data is as follows:

The material formula is 10-15% by weight of polyphenylene sulfide powder; 10-15% of polyphenylene powder; 15~20% of aramid fiber; 7-8 % of molybdenum disulfide; the rest is polytetrafluoroethylene powder.

Dry the humidity at 250-280 ° C and bake for 15-25 minutes, depending on the optimum point of the water in the PTFE emulsion. The sintering is carried out in a nitrogen-protected sintering furnace at a sintering temperature of 380-390 ° C, a sintering time of 10-20 minutes, and a nitrogen gas purity of 99.9% or more. For different sintering furnaces, the nitrogen flow rate and pressure are also different. It is preferred that the steel substrate is not oxidized.

Claims

Claim

1. A lead-free self-lubricating bearing, which is mainly composed of a metal substrate, a spherical porous copper powder layer sintered on the substrate, and a friction-reducing and wear-resistant plastic layer which penetrates and covers the copper powder layer, and is manufactured by a rolling process. a sliding bearing; characterized in that the spherical bronze powder does not contain lead in a lead-free and friction layer plastic formulation; the friction-reducing and wear-resistant plastic layer, that is, a polymer material composition of a bearing lining layer, is polyphenylene sulfide by weight Ether ultrafine powder 10~20%, polyphenylene ultrafine powder 10~20%, aramid fiber 10~20%, fiber length 40~120 μ πι, molybdenum disulfide ultrafine powder 6~10 % The rest are ultra-fine powder of polytetrafluoroethylene.

2. The lead-free self-lubricating bearing according to claim 1, wherein the metal substrate is a steel reel made of high-quality low-carbon steel, and the width of the steel reel is 150 to 300 mm, and the thickness is 0. 25~2. 70mm, and copper plating on the surface, the thickness of the copper plating layer is 4~6 μππ _; the spherical copper powder grade sintered on the metal substrate is selected as CuS _n 8P or CuS _n 10 .

3. A method of manufacturing a lead-free self-lubricating bearing according to claim 1 or 2, characterized in that:

(1) chemical crosslinking of polyphenylene sulfide;

(5) The powder mixture and the polytetrafluoroethylene emulsion must be added with 4~6 % ethanol in an appropriate amount during stirring;

015-0. 03让;; F, medium rolling, the sheet after the drying is carried out once, the rolling amount is 0. 015-0. 03 let;

G, sintering, sintering of the plastic friction layer in the channel type nitrogen gas protection sintering furnace, followed by three processes of preheating, heating and heat preservation; sintering heating temperature 380-390 ° C, total time 15-25 min, wherein sintering preheating The temperature is 8~10min;

-1- The nitrogen gas is used as a shielding gas in the furnace, and the purity thereof is 99.9% or more, and the flow rate of different sintering furnaces is not oxidized to a minimum flow rate;

4. The method of manufacturing a lead-free self-lubricating bearing according to claim 3, wherein: a layer of lead-free spherical bronze powder is sintered on the metal substrate of the steel coil, and the sintering furnace adopts a channel type hydrogen-nitrogen mixed atmosphere. The protection furnace has a hydrogen content of 50%, a nitrogen gas of 50%, and a sintering time of 880 to 900 ° C for 8 to 10 minutes. During the powder and fiber compounding process, it can be added as needed to make the finished product lining layer have a certain color. Resistant to 400 ° C sintered pigment.

-2-