High-precision angular contact ball bearing end face grinding process

Abstract

The invention relates to a high-precision angular contact ball bearing end face grinding process which is technically characterized by comprising the following steps that 1, an inner ring and an outer ring of a bearing to be quenched are prepared, non-equivalent grinding amounts are designed on the end faces of the large sides and the small sides of the inner ring and the outer ring of the bearing to be quenched respectively, and the difference value of the non-equivalent grinding amounts of the end faces of the two sides ranges from 0.08 mm to 0.10 mm; 2, salt bath martensite quenching is adopted; 3, the quenched inner ring and outer ring of the bearing are stacked to form a to-be-ground ring assembly; 4, rough grinding and accurate grinding are conducted in sequence through double independent variable-frequency grinding wheels, specifically, the two independent variable-frequency grinding wheels are different in rotating speed and grinding amount, and the difference value of the non-equal grinding amount is eliminated. The grinding precision and the grinding efficiency are remarkably improved, and the method is suitable for large-scale mass production.

Description

Technical Field

[0001] The present invention relates to the technical field of bearing production and manufacturing, and in particular to a high-precision angular contact ball bearing end surface grinding process. Background Art

[0002] The end faces of bearing rings are typically machined using a double-face grinder or a vertical mill. With a double-face grinder, both end faces of the ring are ground simultaneously as the outer or inner ring quenched piece passes through the grinding wheel, resulting in high processing efficiency and easy parallelism. With a vertical mill, the outer or inner ring quenched piece is placed on a fixed grinding disc. After the grinding wheel grinds one side, the other side is ground in the opposite direction. This method has lower grinding efficiency, but the vertical mill has a wide processing range. For larger widths, double-face grinding results in greater torsional stress, making it easier to maintain size and accuracy using a vertical mill.

[0003] For high-precision angular contact ball bearings, the end faces of the inner and outer rings are asymmetrical and have a large area difference. Especially for closed bearings with sealing rings, the dimensions from the threads on both sides to the end faces must be consistent. However, there are the following problems during grinding: 1. Vertical grinding can better guarantee the grinding amount of both end faces, but for mass production, the low efficiency of vertical grinding seriously affects the production of such bearings; 2. When using a double-end face grinder for grinding, the existing technology is to grind the end faces of a single outer ring or inner ring through double end faces. However, after processing one type of ring, such as the outer ring, when processing the inner ring, although the adjusted size of the equipment meets the tolerance requirements, there is a large size difference between the outer ring and the inner ring. When processing other positions based on its surface, there is a positioning error, which has a certain impact on the interchangeability of high-precision bearing assemblies; furthermore, the tooth mouth to the end face is inconsistent, which affects the installation of the sealing ring, and the sealing ring is uneven, resulting in unqualified products; 3. Foreign countries use physical filling to achieve rigid coupling of the inner and outer rings, that is, the inner and outer rings are positioned by low-temperature filling, and then ground by a double-end face grinder, but this method is complicated and inefficient, and is not feasible for large-scale production. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-precision angular contact ball bearing end face grinding process that solves the above-mentioned problems, significantly improves grinding accuracy and grinding efficiency, and is suitable for large-scale mass production.

[0005] The technical solution of the present invention is:

[0006] A high-precision angular contact ball bearing end surface grinding process, the technical key points of which are as follows:

[0007] Step 1: Prepare the inner and outer rings of the bearing to be quenched: Design unequal grinding amounts on the large and small end faces of the inner and outer rings of the bearing to be quenched, and the difference in the unequal grinding amount of the end faces on both sides is 0.08 to 0.10 mm;

[0008] Step 2, using salt bath martensitic quenching;

[0009] Step 3: The quenched bearing inner ring and outer ring are stacked to form a ring assembly to be ground: the quenched bearing inner ring is placed inside the quenched bearing outer ring, and the end faces of the bearing inner and outer rings with the same grinding amount are oriented in the same direction. Then, the stacked ring assemblies to be ground are placed in the material channel;

[0010] Step 4, using dual independent frequency conversion grinding wheels to perform rough grinding and fine grinding in sequence: the dual independent frequency conversion grinding wheels are composed of two independent frequency conversion grinding wheels arranged on both sides of the material channel, the two independent frequency conversion grinding wheels clamp the ring assembly to be ground and grind the large and small end faces of the ring assembly to be ground respectively, that is, the large and small end faces of the inner and outer rings of the bearing are ground at the same time; the two independent frequency conversion grinding wheels have different rotational speeds and different grinding amounts, thereby eliminating the difference in unequal grinding amounts.

[0011] The above-mentioned high-precision angular contact ball bearing end face grinding process also includes the following steps:

[0012] Step 5: Use the ground large end surfaces of the inner and outer rings of the bearing as reference surfaces to process other positions of the bearing, and perform rough grinding of the inner and outer diameters and grooves respectively;

[0013] Step 6, additional tempering: tempering at 140±20℃×4h to eliminate residual stress from rough grinding;

[0014] Step 7: After the inner and outer rings of the bearing are stacked, they are ground again so that the large end faces and small end faces of the inner and outer rings of the bearing are aligned.

[0015] Step 8: Use the large end faces of the inner and outer rings of the bearing as reference surfaces to fine-grind other positions of the bearing.

[0016] In the above-mentioned high-precision angular contact ball bearing end face grinding process, in step 1, the distance from the large end face side thread edge to the large end face of the inner ring and outer ring of the bearing to be quenched is 1.68±0.05mm, and the distance from the small end face side thread edge to the small end face is 1.78±0.05mm.

[0017] The above-mentioned high-precision angular contact ball bearing end face grinding process, in the step 4, during rough grinding, the speed of the independent variable frequency grinding wheel facing the large end face of the ring assembly to be ground is 200-350r / min, and the speed of the independent variable frequency grinding wheel facing the small end face of the ring assembly to be ground is 350-500r / min, the feed rate of the two independent variable frequency grinding wheels is 0.02-0.04mm / stroke respectively, and the spark-free grinding time is 3-8 seconds; during fine grinding, towards The rotation speed of the independent variable frequency grinding wheel facing the large end face of the ring assembly to be ground is 250~400r / min, and the rotation speed of the independent variable frequency grinding wheel facing the small end face of the ring assembly to be ground is 400~550r / min. The feed rates of the two independent variable frequency grinding wheels are 0.005~0.01mm / stroke respectively, and the spark-free grinding time is 3-8 seconds; the final end face height tolerance is controlled at 0~-0.06mm, and the parallelism difference is controlled within 0.007mm.

[0018] In the above-mentioned high-precision angular contact ball bearing end face grinding process, in step 7, the abrasive particle size used for grinding is W5-W1.5, the grinding wheel linear speed is set to 25-35m / s, and the pressure is set to 0.05-0.15; the rear end face height difference after grinding is controlled within -0.005-0.065mm, and the parallelism error is controlled within 0.002mm.

[0019] The beneficial effects of the present invention are:

[0020] 1. Non-equal grinding amount is designed for the large and small end faces of the inner and outer rings of the bearing to be quenched, that is, the distance from the large end face to the large end face and the distance from the small end face to the small end face are different. This non-equal grinding amount design of the tooth mouth can achieve the equal distance between the two tooth mouths and the end face of the product through equipment frequency modulation and two grindings. The operation is simpler and can be achieved with existing equipment, which greatly improves the qualified rate of the tooth mouth size and significantly improves the grinding accuracy.

[0021] 2. The stacked grinding of the inner and outer ring quenched parts of the bearing can nearly double the processing efficiency compared with the separate grinding, which significantly improves the grinding efficiency.

[0022] 3. Compared with other processes, it is convenient and simple, does not require other auxiliary media, and has low grinding costs.

[0023] 4. After processing, the rear face size and accuracy meet the requirements, and the size difference between the inner and outer rings is within 2μm, ensuring the accuracy of the reference surface. It can achieve high-precision P5 level and above accuracy requirements, and the product meets the interchangeability requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the design of step 1 of the present invention;

[0025] Figure 2 is a schematic diagram of the grinding operation of step 4 of the present invention;

[0026] Figure 3 yes Figure 2 Left view of . DETAILED DESCRIPTION

[0027] The present invention is described in detail with reference to the accompanying drawings.

[0028] The high-precision angular contact ball bearing end face grinding process includes the following steps:

[0029] Step 1, see Figure 1 Prepare the inner and outer rings of the bearing to be quenched: Design unequal grinding allowances on the large and small end faces of the inner and outer rings, with the difference in grinding allowances being 0.08 to 0.10 mm. In this embodiment, the distance from the large end face of the outer ring to the large end face is 1.68 ± 0.05 mm, and the distance from the small end face to the small end face is 1.78 ± 0.05 mm. The inner ring is configured in the same manner.

[0030] The above design, based on the characteristics of double-end face grinding machines, does not achieve equal grinding of the large and small end faces, even at maximum frequency. Therefore, the inner and outer ring end faces are designed with unequal grinding. During grinding, frequency conversion increases the grinding of the small end face and reduces the grinding of the large end face, achieving equal distances from both teeth to the corresponding end faces.

[0031] Step 2: salt bath martensitic quenching is used to reduce quenching strain.

[0032] Step 3, see Figure 2 、 Figure 3 The quenched bearing inner ring 4 and outer ring 3 are stacked to form a ring assembly to be ground: the quenched bearing inner ring 4 is placed inside the quenched bearing outer ring 3, and the end faces of the bearing inner and outer rings with the same grinding amount are oriented in the same direction. Then, the stacked ring assemblies to be ground are placed in the material channel, wherein the upper surface of the material channel is inclined at a certain angle to facilitate the ring assembly to be ground to enter and exit the material channel 2.

[0033] Step 4, using dual independent frequency conversion grinding wheels to perform rough grinding and fine grinding in sequence: the dual independent frequency conversion grinding wheels are composed of two independent frequency conversion grinding wheels 1 and 5 arranged on both sides of the material channel 2, and the two independent frequency conversion grinding wheels 1 and 5 clamp the ring assembly to be ground and grind the large and small end faces of the ring assembly to be ground respectively, that is, the large and small end faces of the inner and outer rings of the bearing are ground at the same time; the two independent frequency conversion grinding wheels have different rotation speeds and different grinding amounts, thereby eliminating the difference in unequal grinding amounts.

[0034] In this embodiment, during rough grinding, the rotational speed of the independent variable frequency grinding wheel facing the large end face of the ring assembly to be ground is 200-350r / min, and the rotational speed of the independent variable frequency grinding wheel facing the small end face of the ring assembly to be ground is 350-500r / min. The feed rates of the two independent variable frequency grinding wheels are 0.02-0.04mm / stroke respectively, and the spark-free grinding time is 3-8 seconds; during fine grinding, the rotational speed of the independent variable frequency grinding wheel facing the large end face of the ring assembly to be ground is 250-400r / min, and the rotational speed of the independent variable frequency grinding wheel facing the small end face of the ring assembly to be ground is 400-550r / min. The feed rates of the two independent variable frequency grinding wheels are 0.005-0.01mm / stroke respectively, and the spark-free grinding time is 3-8 seconds; finally, the end face height tolerance is controlled within 0-0.06mm, and the parallelism difference is controlled within 0.007mm.

[0035] Step 5: Use the ground large end faces of the inner and outer rings of the bearing as reference surfaces to process other positions of the bearing, and perform rough grinding of the inner and outer diameters and grooves respectively.

[0036] Step 6, additional tempering: tempering at 140±20℃×4h to eliminate residual stress from rough grinding.

[0037] In step 7, the inner and outer rings of the bearing are stacked and ground again, and the large end faces and small end faces of the inner and outer rings of the bearing are in the same direction. In this embodiment, in step 7, the abrasive particle size used for grinding is W5-W1.5, the grinding wheel linear speed is set to 25-35m / s, and the pressure is set to 0.05-0.15; the height difference of the rear end faces after grinding is controlled at -0.005-0.065mm, and the parallelism difference is controlled within 0.002mm.

[0038] Step 8: Use the large end faces of the inner and outer rings of the bearing as reference surfaces to fine-grind other positions of the bearing.

[0039] The embodiments of the present invention are described in detail above, but the contents described are only preferred embodiments of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A high-precision angular contact ball bearing end face grinding process, characterized in that: The steps include: Step 1: Prepare the inner and outer rings of the bearing to be quenched: Design unequal grinding amounts on the large and small end faces of the inner and outer rings of the bearing to be quenched, and the difference in the unequal grinding amount of the end faces on both sides is 0.08 to 0.10 mm; Step 2, using salt bath martensitic quenching; Step 3: The quenched bearing inner ring and outer ring are stacked to form a ring assembly to be ground: the quenched bearing inner ring is placed inside the quenched bearing outer ring, and the end faces of the bearing inner and outer rings with the same grinding amount are oriented in the same direction. Then, the stacked ring assemblies to be ground are placed in the material channel; Step 4, using dual independent frequency conversion grinding wheels to perform rough grinding and fine grinding in sequence: the dual independent frequency conversion grinding wheels are composed of two independent frequency conversion grinding wheels arranged on both sides of the material channel, the two independent frequency conversion grinding wheels clamp the ring assembly to be ground and grind the large and small end faces of the ring assembly to be ground respectively, that is, the large and small end faces of the inner and outer rings of the bearing are ground at the same time; the two independent frequency conversion grinding wheels have different rotational speeds and different grinding amounts, thereby eliminating the difference in unequal grinding amounts.

2. The high-precision angular contact ball bearing end surface grinding process according to claim 1, characterized in that: The following steps are also included: Step 5: Use the ground large end surfaces of the inner and outer rings of the bearing as reference surfaces to process other positions of the bearing, and perform rough grinding of the inner and outer diameters and grooves respectively; Step 6, additional tempering: tempering at 140±20℃×4h to eliminate residual stress from rough grinding; Step 7: After the inner and outer rings of the bearing are stacked, they are ground again so that the large end faces and small end faces of the inner and outer rings of the bearing are aligned. Step 8: Use the large end faces of the inner and outer rings of the bearing as reference surfaces to fine-grind other positions of the bearing.

3. The high-precision angular contact ball bearing end surface grinding process according to claim 1, characterized in that: In step 1, the distance from the large end face side thread edge to the large end face of the inner ring and outer ring of the bearing to be quenched is 1.68±0.05 mm, and the distance from the small end face side thread edge to the small end face is 1.78±0.05 mm.

4. The high-precision angular contact ball bearing end surface grinding process according to claim 1, characterized in that: In the step 4, during rough grinding, the rotational speed of the independent variable frequency grinding wheel toward the large end face of the ring assembly to be ground is 200-350 r / min, and the rotational speed of the independent variable frequency grinding wheel toward the small end face of the ring assembly to be ground is 350-500 r / min, the feed rates of the two independent variable frequency grinding wheels are 0.02-0.04 mm / stroke, and the spark-free grinding time is 3-8 seconds; during fine grinding, the rotational speed of the independent variable frequency grinding wheel toward the large end face of the ring assembly to be ground is 250-400 r / min, and the rotational speed of the independent variable frequency grinding wheel toward the small end face of the ring assembly to be ground is 400-550 r / min, the feed rates of the two independent variable frequency grinding wheels are 0.005-0.01 mm / stroke, and the spark-free grinding time is 3-8 seconds; finally, the end face height tolerance is controlled within 0-0.06 mm, and the parallelism difference is controlled within 0.007 mm.

5. The high-precision angular contact ball bearing end surface grinding process according to claim 1, characterized in that: In step 7, the abrasive particle size used for grinding is W5-W1.5, the grinding wheel linear speed is set to 25-35 m / s, and the pressure is set to 0.05-0.15; the height difference of the rear end surface after grinding is controlled at -0.005-0.065 mm, and the parallelism difference is controlled within 0.002 mm.

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