The production method of precision tapered rollers

Abstract

The present invention discloses a production method for precision tapered rollers, which comprises the following steps: pre processing: cold forging the light drawn steel wire into a roller blank; Soft grinding processing: Soft grinding the outer diameter of the roller blank, grinding in two steps on two centerless grinders, and soft grinding the end face of the roller blank; Heat treatment, hard grinding: The surface treated rollers are subjected to outer diameter hard grinding on a centerless grinder; Base surface: The finely ground rollers are processed on a ball base surface grinder for ball base surface processing; Precision machining: Final grinding of outer diameter on a centerless grinder; Ultra precision machining: The finished tapered roller is obtained by performing ultra precision convexity machining on the precision machined roller. The tapered roller processed by the present invention can stably meet the national standard (GB/T25767-2010) level II standard after testing various indicators. The roughness of the rolling surface, SDW of the ball base surface, roundness and other testing items of the tapered roller can meet the national standard level I standard. The outer diameter generatrix of the roller is convex.

Description

The production method of precision tapered rollers

Technical field

The present invention relates to a production method for precision tapered rollers, belonging to the technical field of tapered roller production and manufacturing.

Background technology

The Chinese tapered roller industry has a history of more than 60 years since the first batch of products was produced in 1948. From the perspective of technological progress and industry development, the development after the reform and opening up is the fastest stage. Currently, the tapered roller industry in China can produce more than 1800 specifications of products, with precision reaching level III in batches and a small amount reaching level II. The products are widely used in bearings, as well as in industries such as machine tools, ships, railways, drilling, engineering machinery, household appliances, automobiles, and agricultural machinery. China has become a country with more tapered roller enterprises in the world and a relatively large production volume.

However, from the current quality status of tapered rollers in China, some of them have approached or reached international advanced levels, but there is still an overall gap. Due to processing technology, high-precision, fatigue resistant, and long-life tapered roller bearings still need to be imported. At present, the differences in the manufacturing process of tapered rollers in China result in significant differences in accuracy, which directly affects the service life of bearings. With the rapid development of China's automotive, railway, and machine tool industries, the accuracy and reliability of tapered roller bearings directly affect the procurement ratio of domestically produced bearings in these industries. Therefore, researching and improving the accuracy and fatigue resistance of tapered rollers is an important development trend in the tapered roller industry.

The traditional production of tapered rollers generally adopts processes such as cold heading, soft grinding, heat treatment, polishing, coarse and fine grinding, ball base grinding, final grinding, and ultra precision machining, but it is not yet possible to produce Grade II and Grade I tapered rollers in large quantities.

Summary of the invention

The purpose of the present invention is to provide a production method for precision tapered rollers to overcome the shortcomings of the prior art.

To achieve the above objectives, the present invention adopts the following technical solution:

A production method for precision tapered rollers, with the following steps:

1) Pre processing:

Cold heading the light drawn steel wire into a roller blank;

2) Soft grinding processing:

The outer diameter of the soft ground roller blank is ground in two steps on two centerless grinders. The first step is to grind 0.20-0.40mm on the first centerless grinder, and the second step is to grind 0.10-0.15mm on the second centerless grinder. The rollers are transported between the two steps using a bearing roller connecting machine; The rough end face of the soft ground roller is processed on a double end face grinder. The tapered roller with the soft ground outer diameter is transported to the double end face grinder for end face processing through a bearing roller connecting machine. The conveying speed of the bearing roller connecting machine is synchronized with the grinding speed;

3) Heat treatment:

After soft grinding, the roller blank is heated and quenched in a controllable protective atmosphere using a mesh belt electric furnace, and then subjected to annealing heat treatment. After the roller blank cools to room temperature, surface treatment is carried out on a surface polishing machine. The treated roller cavities are clean and free of oil stains;

4) Hard grinding:

The surface treated rollers are subjected to outer diameter hard grinding on a centerless grinder. Hard grinding is divided into coarse grinding and fine grinding, with a rough grinding amount of 0.06-0.12mm and a fine grinding amount of 0.03-0.05mm. The rollers are transported between the two grinding steps using a bearing roller connecting machine;

5) Spherical basal plane

Process the finely ground rollers on a ball base surface grinder for ball base surface machining;

6) Precision machining:

Perform the final grinding of the outer diameter on a centerless grinder, which is divided into two steps. The first step involves grinding an amount of 0.01-0.015mm, and the second step involves grinding an amount of 0.005-0.008mm; Roller conveyor between two-step grinding using bearing roller connecting machine for conveying;

7) Ultra precision machining:

The finished tapered roller is obtained by performing ultra precision convexity machining on the precision machined roller.

The quenching heating temperature in step 3) is 830-860 ℃, and the heating time is 40-80 minutes. The quenching medium is fast quenching oil, and the temperature is 60-80 ℃.

The tempering heating temperature in step 3) is 150-170 ℃, and the holding time is 200-250 minutes.

In step 5), a 60-120 grit rubber grinding wheel is used for the ball base surface, and the isolation disk is rotated at a speed of 1.5-3.5r/min. After processing, the end face runout of the ball base surface is 2-4 μ M.

In step 6), a 100 grit rubber grinding wheel is used for final grinding, with a guide wheel processing speed of 50-130r/min.

In step 7), the ultra precision machining of the rollers adopts several combinations of W14 oilstone, W10 oilstone, W5 oilstone, or W3.5 oilstone arranged with graphite and plastic plates (according to the different specifications of the tapered roller, select the corresponding oilstone and graphite and their arrangement, as shown in the table below). On the outer diameter machining surface of the tapered roller, a low pressure of 0.5-3.5kg/cm2 is applied and a short vibration is performed, which is 1200-2700 times/min, with an amplitude of 1-5mm; At the same time, the ultra precision roller undergoes through grinding at a processing speed of 20-140 grains per minute, and the grinding fluid is ZYS-998 precision grinding fluid.

The present invention has the following beneficial effects: the diameter variation of the roller batch processed by the present invention is 1-2.5 μ m. Single roller roundness error, diameter variation 0.5-1.2 μ m. Batch angle variation of 1-2.5 μ m. Cone angle deviation ± 1 to ± 2.5 μ m. Rolling surface roughness Ra0.08~0.12 μ m. Roughness of spherical base Ra0.10-0.16 μ m. The radius deviation of the spherical base is less than 5mm, and the spherical base jumps 2-4 degrees μ M.

After testing, all indicators of the tapered roller can stably meet the Class II standard of the national standard (GB/T25767-2010). The roughness of the rolling surface, ball base surface runout, roundness and other testing items of the tapered roller can meet the Class I standard of the national standard, and meet the requirements of the National Standard for Fine Tapered Roller Rolling Bearings. The method provided by the present invention has great potential for improving the accuracy of rollers and can be mass-produced.

The pretreatment of the present invention is to process the light drawn steel wire into a roller blank using a multi-station cold heading machine, with a processing allowance of 0.30-0.50mm and a displacement deviation of 0.06-0.15mm; Process the above-mentioned roller blank using a centerless grinder, with a guide wheel processing speed of 50-130r/min; The grinding amount of the roller blank after soft grinding is 0.15~0.20mm, and the centerless grinder is connected by a connecting machine for processing.

After soft grinding, the rollers are processed using a double end face grinder for end face processing, with a grinding amount of 0.3-0.4mm. The double end face machine uses ceramic grinding wheels (with a large head diameter less than 18mm) and resin grinding wheels (with a large head diameter greater than 18mm) for processing, and the feeding plate speed is 2-5r/min. The soft grinding and double end faces are connected by a connecting machine for processing, saving labor, improving production efficiency, effectively avoiding bumps and ensuring stable quality.

The process method adopted in the present invention is based on the existing roller processing technology, by analyzing the factors affecting roller accuracy and service life, selecting reliable and reasonable process methods, and achieving reasonable selection of grinding wheels and auxiliary materials for grinding and grinding. Reasonable process equipment and parameters are selected to improve roller manufacturing accuracy, surface roughness, metallographic structure, and surface hardness, thereby improving roller accuracy.

Illustration

Figure 1 is an actual product processing diagram of Example 1;

Figure 2 is an actual product processing diagram of Example 2;

Figure 3 is an actual product processing diagram of Example 3;

Specific implementation methods

The following will further explain the present invention in conjunction with the accompanying drawings and embodiments.

Example 1: Taking the production process of (32207) roller as an example, the roller material is GCr15, and the steps are as follows:

1) Pre processing:

Process the light drawn steel wire into a blank using a cold heading machine, with a machining allowance of 0.30-0.50mm and a displacement deviation of less than 0.06-0.15mm; Blank size

2) Soft grinding processing:

The outer diameter of the soft grinding roller blank is processed on a centerless grinder, with two steps of grinding. The first step is to grind 0.20mm, and the second step is to grind 0.10mm. The rollers are transported between the two steps using a bearing roller connecting machine; Using 60-80 grit ceramic grinding wheels, with a guide wheel processing speed of 50-130 r/min;

Soft ground roller blank end face, processed on a double end face grinder. The tapered rollers with soft ground outer diameters are transported to a double end face grinder through a bearing roller connecting machine for end face processing. The two ends are equipped with 60 grit ceramic grinding wheels, and the conveying speed of the bearing roller connecting machine is synchronized with the grinding speed;

3) Heat treatment:

After soft grinding, the roller blank will be heated and quenched in a controllable protective atmosphere using a mesh belt electric furnace. The quenching heating temperature is 840 ℃ and the heating time is 50 minutes. The quenching medium is fast quenching oil and the temperature is 65 ℃. Then, heat treatment is carried out by tempering, with a heating temperature of 155 ℃ and a holding time of 215 minutes. After the roller cools to room temperature, perform surface treatment on the surface polishing machine: the treated roller cavity is clean and free of oil stains;

4) Hard grinding:

Perform outer diameter hard grinding on the surface treated roller on a centerless grinder. Hard grinding is divided into rough grinding and fine grinding, with a rough grinding amount of 0.06mm and a fine grinding amount of 0.03mm. Roller conveyor between two-step grinding using bearing roller connecting machine for conveying;

5) Spherical basal plane

The finely ground rollers are processed on a ball base surface grinder, using an 80 grit rubber grinding wheel with an isolation disc speed of 3.5r/min. After processing, the end face runout of the ball base surface does not exceed 2 μ M.

6) Precision machining

Perform final grinding of the outer diameter on a centerless grinder. The final grinding of the outer diameter is divided into two steps, with a grinding amount of 0.010mm for final grinding one and 0.005mm for final grinding two. The final grinding adopts a 100 grit rubber grinding wheel, and the processing speed of the guide wheel is 130r/min. Roller conveyor between two-step grinding using bearing roller connecting machine for conveying;

7) Ultra precision machining:

The precision machined rollers are processed with ultra precision machines for ultra precision convexity. Ultra precision machining uses W14 oilstone, W10 oilstone, W5 oilstone, W3.5 oilstone, graphite and plastic plate arranged and combined as shown in the table below. On the outer diameter machining surface of the tapered roller, a low pressure of 1.0kg/cm2 is applied and a short vibration of 1800 times/min is performed, with an amplitude of 2.0mm; At the same time, the ultra precision roller undergoes through grinding at a processing speed of 140 grains per minute, and the grinding fluid is ZYS-998 precision grinding fluid.

The diameter variation of the roller processed by the above process is 0.5 μ m. Ball base jumping 2 μ m. Roundness 0.5 μ Surface roughness Ra0.08 μ m. The outer diameter generatrix of the roller is a definite convex shape.

Example 2: Using

Taking the production process of rollers as an example, the roller material GCr15,

1) Pre processing:

Cold heading the light drawn steel wire into a roller blank, with dimensions of the blank

2) Soft grinding processing:

The outer diameter of the soft grinding roller blank is processed on a centerless grinder, with two steps of grinding. The first step is to grind 0.30mm, and the second step is to grind 0.12mm. The rollers are transported between the two steps using a bearing roller connecting machine;

Soft ground roller blank end face, processed on a double end face grinder. The tapered rollers with soft ground outer diameters are transported to a double end face grinder through a bearing roller connecting machine for end face processing. The conveying speed of the bearing roller connecting machine is synchronized with the grinding speed;

3) Heat treatment:

After soft grinding, the roller blank will be heated and quenched in a controllable protective atmosphere using a mesh belt electric furnace. The quenching heating temperature is 845 ℃ and the heating time is 55 minutes. The quenching medium is fast quenching oil and the temperature is 65 ℃. Then, heat treatment is carried out by tempering, with a heating temperature of 160 ℃ and a holding time of 220 minutes. After the roller cools to room temperature, perform surface treatment on the surface polishing machine: the treated roller cavity is clean and free of oil stains;

4) Hard grinding:

Perform outer diameter hard grinding on the surface treated roller on a centerless grinder. Hard grinding is divided into rough grinding and fine grinding, with a rough grinding amount of 0.08mm and a fine grinding amount of 0.04mm. Roller conveyor between two-step grinding using bearing roller connecting machine for conveying;

5) Spherical basal plane

The finely ground rollers are processed on a ball base surface grinder, using an 80 grit rubber grinding wheel with an isolation disc speed of 2.5r/min. After processing, the end face runout of the ball base surface does not exceed 3 μ M.

6) Precision machining

Perform final grinding of the outer diameter on a centerless grinder. The final grinding of the outer diameter is divided into two steps, with a grinding amount of 0.012mm for final grinding one and 0.006mm for final grinding two. The final grinding adopts a 100 grit rubber grinding wheel, and the processing speed of the guide wheel is 100r/min. Roller conveyor between two-step grinding using bearing roller connecting machine for conveying;

7) Ultra precision machining:

The precision machined rollers are processed with ultra precision machines for ultra precision convexity. Ultra precision machining uses W14 oilstone, W10 oilstone, W5 oilstone, W3.5 oilstone, graphite and plastic plate arranged and combined as shown in the table below. On the outer diameter machining surface of the tapered roller, a low pressure of 2.0kg/cm2 is applied and a short vibration of 2000 times/min is performed with an amplitude of 2.5mm; At the same time, the ultra precision roller undergoes through grinding at a processing speed of 110 grains per minute, and the grinding fluid is ZYS-998 precision grinding fluid.

The diameter variation of the roller processed by the above process is 0.8 μ m. Ball base jumping 3 μ m. Roundness 0.8 μ Surface roughness Ra0.10 μ m. The outer diameter generatrix of the roller is a definite convex shape.

Example 3: Using

(32313) Taking the production process of rollers as an example, the roller material GCr15,

1) Pre processing:

Cold heading the light drawn steel wire into a roller blank, with dimensions of the blank

2) Soft grinding processing:

The outer diameter of the soft grinding roller blank is processed on a centerless grinder, with two steps of grinding. The first step is to grind 0.40mm, and the second step is to grind 0.15mm. The rollers are transported between the two steps using a bearing roller connecting machine;

Soft ground roller blank end face, processed on a double end face grinder. The tapered rollers with soft ground outer diameters are transported to a double end face grinder through a bearing roller connecting machine for end face processing. The conveying speed of the bearing roller connecting machine is synchronized with the grinding speed;

3) Heat treatment:

After soft grinding, the roller blank will be heated and quenched in a controllable protective atmosphere using a mesh belt electric furnace. The quenching heating temperature is 845 ℃ and the heating time is 65 minutes. The quenching medium is fast quenching oil and the temperature is 65 ℃. Then, heat treatment is carried out by tempering, with a heating temperature of 160 ℃ and a holding time of 240 minutes. After the roller cools to room temperature, perform surface treatment on the surface polishing machine: the treated roller cavity is clean and free of oil stains;

4) Hard grinding:

Perform outer diameter hard grinding on the surface treated roller on a centerless grinder. Hard grinding is divided into rough grinding and fine grinding, with a rough grinding amount of 0.12mm and a fine grinding amount of 0.05mm. Roller conveyor between two-step grinding using bearing roller connecting machine for conveying;

5) Spherical basal plane

The finely ground rollers are processed on a ball base surface grinder, using an 80 grit rubber grinding wheel with an isolation disc speed of 1.5r/min. After processing, the end face runout of the ball base surface does not exceed 4 μ M.

6) Precision machining

Perform final grinding of the outer diameter on a centerless grinder. The final grinding of the outer diameter is divided into two steps, with a grinding amount of 0.015mm for final grinding one and 0.008mm for final grinding two. The final grinding adopts a 100 grit rubber grinding wheel, with a guide wheel processing speed of 50r/min. Roller conveyor between two-step grinding using bearing roller connecting machine for conveying;

7) Ultra precision machining:

The precision machined rollers are processed with ultra precision machines for ultra precision convexity. Ultra precision machining uses W14 oilstone, W5 oilstone, graphite and plastic plates arranged and combined as shown in the table below. On the outer diameter machining surface of the tapered roller, a low pressure of 3.5kg/cm2 is applied and a short vibration of 2500 times/minute is performed, with an amplitude of 3.0mm; At the same time, the ultra precision roller undergoes through grinding at a processing speed of 110 grains per minute, and the grinding fluid is ZYS-998 precision grinding fluid.

The diameter variation of the roller processed by the above process is 1.0 μ m. Ball base jumping 4 μ m. Roundness 1.0 μ Surface roughness Ra0.12 μ m. The outer diameter generatrix of the roller is a definite convex shape.

The main technical accuracy meets the requirements of national level I rollers. The fatigue life of the roller bearing made by the present invention can be increased by 1.5 to 2 times, meeting the advanced fatigue life requirements of foreign bearings, by comparing the bearing samples made by the original process and the roller sleeve made by the present invention with actual use.

The present invention technology can be applied to the tapered roller production industry, and can produce tapered rollers with Class II accuracy in large quantities and Class I accuracy in small quantities.

Although the specific embodiments of the present invention have been described in conjunction with the accompanying drawings, it is not a limitation of the scope of protection of the present invention. Those skilled in the art should understand that various modifications or deformations that can be made without creative labor on the basis of the technical solution of the present invention are still within the scope of protection of the present invention.

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