Abstract
The present invention relates to a processing method for bearing rollers, specifically to a processing method for large tapered rollers with a length to diameter ratio less than 1. The machining process involves using spiral guide wheels at different angles to grind the outer circle of the roller multiple times, gradually grinding the outer circle of the roller to the required angle; Heat treatment of rollers between soft and rough grinding processes; Grind the roller end face when the half of the roller does not exceed 6 ° between two rough grinding operations; When grinding the roller ball base surface with a medium soft grinding wheel between rough and fine grinding. By adopting the processing method of the present invention, the surface of the roller can be ground uniformly without defects such as black skin, and the accuracy is high. This greatly reduces the noise of the matching bearings during operation and improves their service life.
Description
The machining method of large tapered rollers with a length to diameter ratio less than 1
Technical field
The present invention belongs to the field of rolling bearing manufacturing and relates to a processing method for bearing rollers. Specifically, it relates to a processing method for a large tapered roller with a length to diameter ratio less than 1.
Background technology
The half of a general tapered roller is within the range of 1 ° to 4 °, and those with a half exceeding 4 ° are called large tapered rollers. In addition, the length of a tapered roller is generally larger than the diameter (referring to the larger end diameter of a tapered roller), that is, the ratio of length to diameter is greater than 1. However, some special tapered rollers have a length smaller than the diameter and are called tapered rollers with a length to diameter ratio less than 1.
When the tapered roller has a large and a length to diameter ratio of less than 1, its machining difficulty is much greater than that of ordinary rollers, mainly manifested in the following aspects:
(1) Difficulty in positioning the cold pier roller blank. The concave die used for cold forging such roller blanks has a large and shallow depth. After the cylindrical material section is placed in the concave die cavity, the stability of positioning is poor and it is prone to deviation, which often leads to the blank being offset.
(2) Difficulty in forming raw materials. The diameter difference between the large and small ends of this type of roller is significant and relatively short. When cold heading the blank, both the large and small ends need to undergo significant deformation in order to have the same shape as the inner cavity. Therefore, it is possible that the small end may experience severe cold work hardening due to high extrusion pressure, while the large end may experience cracks due to excessive deformation.
(3) Difficulty in grinding the outer circle. When grinding the outer circle of this type of roller on a centerless grinding machine, the roller is positioned by a spiral guide wheel, which drives the roller to rotate and move forward. During rough grinding, jumping and stopping may occur due to the large of the roller, thereby affecting the machining quality.
(4) Difficulty in grinding both end faces. When grinding the large and small end faces of this type of roller on a double end face grinder, the roller is brought into the grinding area through a feeding plate. Due to the large of the roller, its positioning in the loading space of the feeding plate is unstable, and the difference in grinding forces on the two end faces causes the roller to tilt, thereby affecting the machining accuracy.
(5) Difficulty in grinding the ball base surface. According to the needs of the bearing, the curvature radius of the base surface ball of this type of roller is designed to be relatively small. When grinding the ball base surface, the amount of wear on the edge of the ball base surface is much larger than that in the middle, which can easily cause burns on the edge of the ball base surface during grinding.
Due to the above reasons, if large tapered rollers with a length to diameter ratio of less than 1 are processed using conventional processing methods, quality defects such as insufficient material or cracks on the surface of the rollers, inadequate grinding of the outer circle with black skin, burning of the ball base surface, and different axes at both ends of the rollers may occur. As a result, it leads to a high scrap rate and low production efficiency.
Summary of the invention
To solve the above-mentioned technical problems, the present invention proposes a processing method specifically for large tapered rollers with a length to diameter ratio of less than 1. This method avoids the processing difficulties caused by the large of the rollers in each process. The roller blank is first cold-rolled into a 4 ° half cone angle, and then gradually processed into the required half through processes such as soft grinding, rough grinding, and precision grinding. This method can reduce the processing difficulty of large tapered rollers with a length to diameter ratio of less than 1, achieve the goal of reducing scrap rate and improving production efficiency.
The specific steps adopted by the present invention to complete its invention tasks are as follows:
1) Design the structural dimensions of the roller blank: For large tapered rollers with a half greater than 4 °, design the half of the blank uniformly according to 4 °; Calculate the diameter of the large end of the blank according to the dimensions specified in the drawing plus the allowance for grinding the large end; The small head diameter is calculated based on the calculated large head diameter, the length specified in the drawing, and the grinding allowance of the end face, with a half of 4 °; The allowance for large head outer circle grinding and end face grinding is determined based on the roller diameter. For rollers with a diameter of less than 10mm, the allowance for large head outer circle grinding is selected within the range of 0.3-0.35mm, and the allowance for end face grinding is selected as 0.3mm; For rollers with a diameter of 10-20mm, the large end outer circle grinding allowance should be selected within the range of 0.4-0.5mm, and the end face grinding allowance should be selected within the range of 0.4-0.6mm; For rollers with a diameter of 20mm or more, the large end outer circle grinding allowance should be selected within the range of 0.6-0.7mm, and the end face grinding allowance should be selected within the range of 0.6-0.8mm; After designing the structure of the blank according to the above method, although the grinding amount of the small head increased, the problem of cold pier was solved;
2) Design and manufacture cold pier molds according to the and structural dimensions of the designed blank;
3) Stamping roller blanks using designed and manufactured molds on cold heading machines;
4) Place the stamped roller blank on the centerless grinding machine for soft grinding of the outer circle; Using a 4 ° spiral guide wheel for soft grinding, 0.15-0.35mm should be removed from the outer surface, and there should be a margin of 0.15-0.35mm for the large end of the roller after soft grinding;
5) Place the roller that has undergone the first soft grinding of the outer circle on the centerless grinding machine for the second soft grinding of the outer circle; If the half of the roller specified in the drawing is greater than or equal to 5 °, use a 5 ° spiral guide wheel for the second soft grinding of the outer circle; If the half of the roller specified in the drawing is less than 5 °, use a spiral guide wheel with the same half as the roller specified in the drawing for the second soft grinding of the outer circle of the roller; The second soft grinding should remove 0.03-0.05mm from the outer surface of the large end, and there should be a margin of 0.12-0.30mm for the outer surface of the large end of the roller;
6) Place the soft ground rollers in a heat treatment furnace for quenching and tempering; The quenching temperature is 830-840 ℃, and the holding time is 40-60 minutes; The tempering temperature is 150-160 ℃, and the insulation time is 2-2.5 hours; Afterwards, the furnace is cooled to room temperature;
7) Place the quenched and tempered rollers on the centerless grinding machine for the first rough grinding of the outer circle; If the half of the roller specified in the drawing is greater than or equal to 6 °, use a 6 ° spiral guide wheel for rough grinding to remove 0.02-0.05mm of the outer surface of the roller head. After rough grinding, there should be a margin of 0.1-0.25mm for the outer surface of the roller head; If the half of the roller specified in the drawing is less than 6 °, a spiral guide wheel with the same half as the roller specified in the drawing can be used for rough grinding to remove 0.04-0.10mm of the outer surface of the large head. After rough grinding, there should be a margin of 0.08-0.20mm for the outer surface of the large head of the roller;
8) Place the roller that has undergone the first rough grinding on a double end face grinder to grind two end faces; Grind off 0.11-0.35mm on both ends, and there should be a grinding amount of 0.08-0.1mm in the length direction of the roller after grinding; 9) Place the roller that has undergone double end face grinding on the centerless grinding machine for the second rough grinding of the outer circle; If the half of the roller specified in the drawing is greater than or equal to 7 °, use a 7 ° spiral guide wheel for the second rough grinding of the outer circle; If the half of the roller specified in the drawing is less than 7 ° and greater than 6 °, use a spiral guide wheel with the same half as the roller specified in the drawing for a second rough grinding of the outer circle; If the half of the roller specified in the drawing is less than 6 °, the second rough grinding of the outer circle will not be carried out; For rollers with a half of more than 6 °, the second rough grinding should remove 0.02-0.05mm from the outer surface of the large head. After the second rough grinding, there should still be a margin of 0.08-0.20mm left on the outer surface of the large head;
9) Place the roller that has undergone the second rough grinding on the centerless grinding machine for the third rough grinding of the outer circle; If the half of the roller specified in the drawing is greater than or equal to 8 °, use an 8 ° spiral guide wheel for the third rough grinding of the outer circle; If the half of the roller specified in the drawing is less than 8 ° and greater than 7 °, use a spiral guide wheel with the same half as the roller specified in the drawing for the third rough grinding of the outer diameter; If the half of the roller specified in the drawing is less than or equal to 7 °, the third rough grinding of the outer diameter will not be carried out; For rollers with a half greater than 7 °, the third rough grinding should remove 0.02-0.05mm from the outer surface of the large head. After rough grinding, there should be a margin of 0.06-0.15mm for the outer surface of the large head of the roller;
10) Place the roughly ground rollers on the ball base surface grinder to grind the ball base surface. Use a medium soft grinding wheel. After grinding, the curvature radius of the spherical surface should meet the requirements of the drawing, and the length of the rollers should meet the requirements of the drawing;
11) Place the roller that has been ground on the spherical base surface on the centerless grinding machine to finely grind the outer circle; Using a spiral guide wheel with the same half as the finished roller, the large end outer circle of the roller is left with a tolerance of 0.04-0.08mm after grinding;
12) Place the roller that has been finely ground on the outer circle centerless grinder for final grinding of the outer circle; Using a spiral guide wheel with the same half as the finished roller for final grinding of the outer circle, the outer circle of the roller should reach the size specified in the drawing after final grinding.
The processing principle of the present invention is to first cold upset the blank into a small angle blank with a half of 4 °, then use various different angles of spiral guide wheels to grind the outer diameter of the roller, gradually grinding the half of the roller from small to large, and finally use spiral guide wheels with the same angle as the finished roller to finally grind off all the grinding amount of the outer circle of the roller, forming a large tapered roller with a length to diameter ratio less than 1.
The beneficial effect of the present invention is that by adopting the processing method of the present invention, the outer surface of the roller can be processed uniformly without defects such as cracks, burns, and black skin, and the processing accuracy is high. This reduces the noise of the matching bearings during operation and improves their service life.
Specific implementation methods
The following is an explanation of the processing method of the present invention based on the given implementation examples.
Example 1
The model of the processed tapered roller is 829234
Half cone angle: 5 ° 3 ′
The diameter of the large head is 19.6mm
Length: 15.7mm
The curvature radius of the spherical base is 105mm
The processing method is:
1. Design the structure of the roller blank with a 4 ° half cone angle. After calculation, the diameter of the large end of the blank is 20.1mm, the diameter of the small end is 17.8mm, and the length is 16.5mm.
2. Design and manufacture cold pier molds according to the designed rough and structural dimensions.
3. Stamping roller blanks using designed and manufactured molds on a cold heading machine.
4. Place the stamped roller blank on the cylindrical centerless grinder for soft grinding of the outer circle. Using a 4 ° spiral guide wheel for soft grinding, the large end diameter of the roller after soft grinding is 19.95mm, with a margin of 0.35mm.
5. Place the roller that has undergone the first soft grinding of the outer circle on the centerless grinding machine for the second soft grinding of the outer circle. Using a 5 ° spiral guide wheel for the second soft grinding of the outer circle, the large end diameter of the roller after grinding is 19.85mm, with a margin of 0.25mm.
6. Place the soft ground rollers in a heat treatment furnace for quenching and tempering. The quenching temperature is 830-840 ℃, and the holding time is 40-60 minutes; The tempering temperature is 150-160 ℃, and the insulation time is 2-2.5 hours. Afterwards, the furnace is cooled to room temperature.
7. Place the quenched and tempered rollers on the centerless grinding machine to roughly grind the outer circle. Using a 5 ° 3 'spiral guide wheel grinding, the outer diameter of the large end of the roller after grinding is 19.75mm, with a margin of 0.15mm.
8. Place the roughly ground roller on a double end face grinder to grind two end faces. The length of the roller after grinding is 15.8mm, and there is still a grinding amount of 0.1mm.
9. Place the roughly ground rollers on the ball base surface grinder to grind the ball base surface, using a medium soft grinding wheel. After grinding, the spherical curvature radius should meet the requirements of the drawing, and the roller length should meet the requirements of the drawing.
10. Place the roller that has been ground on the ball base surface on the centerless grinder to finely grind the outer circle. Using a spiral guide wheel with the same half as the finished roller, the outer diameter of the large end of the roller after grinding is 19.65mm, with a margin of 0.05mm.
11. Place the roller that has been finely ground on the outer circle centerless grinder for final grinding of the outer circle. Using a spiral guide wheel with the same half as the finished roller for final grinding of the outer circle, the outer circle of the roller should reach the size specified in the drawing after final grinding.
Example 2
The processed tapered roller model is 829748
Half cone angle: 6 ° 24 ′
The diameter of the large head is 22.8mm
Length: 18.23mm
The curvature radius of the spherical base is 141mm
The processing method is:
1. Design the structure of the roller blank with a 4 ° half cone angle. After calculation, the diameter of the large end of the blank is 23.4mm, the diameter of the small end is 20.8mm, and the length is 18.83mm.
2. Design and manufacture cold pier molds according to the and structural dimensions of the designed blank.
3. Stamping roller blanks using designed and manufactured molds on a cold heading machine.
4. Place the stamped roller blank on the cylindrical centerless grinder for soft grinding of the outer circle. Using a 4 ° spiral guide wheel for soft grinding, the large end diameter of the roller after soft grinding is 23.15mm, with a margin of 0.35mm.
5. Place the roller that has undergone the first soft grinding of the outer circle on the centerless grinding machine for the second soft grinding of the outer circle. Using a 5 ° spiral guide wheel for the second soft grinding of the outer circle, the large end diameter of the roller after grinding is 23.05mm, with a margin of 0.25mm.
6. Place the soft ground rollers in a heat treatment furnace for quenching and tempering. The quenching temperature is 830-840 ℃, and the holding time is 40-60 minutes; The tempering temperature is 150-160 ℃, and the insulation time is 2-2.5 hours. Afterwards, the furnace is cooled to room temperature.
7. Place the quenched and tempered rollers on the centerless grinding machine to roughly grind the outer circle. Using a 6 ° spiral guide wheel grinding, the outer diameter of the large end of the roller after grinding is 22.95mm, with a margin of 0.15mm.
8. Place the roughly ground roller on a double end face grinder to grind two end faces. The length of the roller after grinding is 18.33mm, and there is still a grinding amount of 0.1mm.
9. Place the roller that has undergone double end face grinding on the centerless grinding machine for the second rough grinding of the outer circle; Using a spiral guide wheel with the same half as the finished roller, the outer diameter of the large end of the roller after grinding is 22.89 mm, with a margin of 0.09mm.
10. Place the roughly ground rollers on the ball base surface grinder to grind the ball base surface, using a medium soft grinding wheel. After grinding, the curvature radius of the spherical surface should meet the requirements of the drawing, and the length of the rollers should meet the requirements of the drawing.
11. Place the roller that has been ground on the ball base surface on the centerless grinder to finely grind the outer circle. Using a spiral guide wheel with the same half as the finished roller, the outer diameter of the large end of the roller after grinding is 22.84, with a margin of 0.04mm.
12. Place the roller that has been finely ground on the outer circle centerless grinder for final grinding of the outer circle. Using a spiral guide wheel with the same half as the finished roller for final grinding of the outer circle, the outer circle of the roller should reach the size specified in the drawing after final grinding.
2024 July 2nd Week WBM Product Recommendation:
Steel Ball Cold Heading Tools：
n the steel ball cold heading process, after barstocks are cut into column-shaped blanks, two ends of the column shaped blanks are rubbed and cut into inversed angel or round angle shapes, and then the blanks are transferred to a cold heading mechanism to be headed into steel ball rough cast; a blank rubbing and cutting mechanism is additionally arranged on the corresponding cold heading machine. The quality and eligibility rate of the steel ball rough cast can be enhanced and the manufacturing cost thereof can be reduced. Furthermore, as the shapes of the blanks entering the cold forging mechanism are regular, the stress born by the cold heading mechanism is equal in the punching process, thus the service life of cold heading dies is prolonged.
