Needle roller annealing process

Abstract

The invention provides a roller pin annealing process which comprises the following steps: putting a roller pin with two planar ends into a pit furnace, setting process parameters such as temperature and slope time, and performing annealing treatment on the roller pin; and the annealed roller pin is subjected to SR machining, the two ends of the roller pin are shifted into spherical surfaces, then smooth treatment and heat treatment are conducted in sequence, and the finished roller pin is obtained. The method has the beneficial effects that the subsequent SR channeling processing time can be shortened through annealing, reduction of the hardness of the roller pin and SR channeling, and the purpose of improving the productivity is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of needle roller annealing process application, and mainly relates to a needle roller annealing process. Background Art

[0002] The original needle roller production process: cutting → SR → smoothing → heat treatment..., such as Figure 1 As shown in the figure, needle roller SR refers to the process of passing a flat needle roller at both ends through a barrel to make the two ends of the needle roller spherical. The needle roller SR value refers to the radius of curvature of the spherical base surface of the needle roller in the needle roller bearing. The size of this value directly affects the contact surface between the needle roller and the inner ring rib of the bearing, and thus affects the load-bearing capacity and fatigue strength of the bearing.

[0003] In the original needle roller SR process, both ends of the blanked needle roller are flat, and the direct SR forming time is long. Taking the Φ2 round head needle roller as an example, the SR forming time takes 80 to 160 hours, which affects the production efficiency. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a needle roller annealing process, especially to use this annealing process for small needle rollers when the rounding time is long and the forming is slow.

[0005] The object of the present invention is achieved through the following technical solution. A needle roller annealing process comprises the following steps:

[0006] Step 1: Place the needle roller with two flat ends into a material frame, place the material frame flat into a pit furnace, set the temperature, ramp time and other related process parameters, anneal the needle roller, and reduce the hardness of the needle roller;

[0007] Step 2: The annealed needle roller is subjected to SR processing to form both ends of the needle roller into a spherical shape, and then subjected to rounding treatment, heat treatment and grinding in sequence to obtain a finished needle roller.

[0008] Furthermore, the step of placing the rollers with flat ends into the pit furnace includes: placing the rollers into a material frame, hoisting the material frame into the pit furnace with a crane, stacking the material frames flatly in the pit furnace, covering the furnace cover and gradually tightening the bolts, and opening the air pipe valve on the furnace cover.

[0009] Furthermore, the step of setting the temperature and ramp time related process parameters includes: setting the annealing temperature, heating rate, and holding time on the temperature controller, starting the circulating fan and the heating switch, and heating the roller according to the preset annealing process route.

[0010] Furthermore, the annealing treatment steps include: heating the needle roller with the furnace for 3 hours, opening the exhaust valve to exhaust oil smoke, heating to 400°C, closing the exhaust valve, and vacuuming; heating to 680°C and keeping warm for 4 hours, cooling to 450°C for 3 hours and keeping warm for 2.5 hours. After annealing is completed, the needle roller is lifted out of the pit furnace.

[0011] Furthermore, the annealing treatment step also includes: during the heating process, adjusting the atmosphere in the pit furnace by vacuuming and flushing with nitrogen, and recording the pressure gauge reading; specifically: vacuuming to a pressure of -0.5 to 1Mpa, closing the vacuum valve, opening the nitrogen flushing valve, and flushing with nitrogen to a pressure of 0Mpa.

[0012] The beneficial effects of the present invention are as follows: the improved production process: blanking → annealing → SR channeling → smoothing → heat treatment..., through annealing, the hardness of the needle roller is reduced, and then SR channeling can shorten the time and achieve the purpose of increasing production capacity. Tests have proved that needle roller annealing can soften the workpiece, shorten the processing time of the subsequent SR channeling by 49%, refine the grains, and improve the organization. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art or ordinary technicians, other drawings can be obtained based on these drawings without paying creative work.

[0014] Figure 1 Schematic diagram of the needle roller before and after SR in the present invention.

[0015] Figure 2 It is a schematic diagram of the annealing process route of the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0017] The needle roller annealing process described in the present invention is suitable for reducing the hardness of the needle roller, shortening the time of SR forming, and improving production efficiency. The method is as follows:

[0018] ⑴ Use a crane to lift the needle rollers into the pit furnace. Stack the needle rollers in each frame. The material frame should be flat and visually straight.

[0019] ⑵ Cover the furnace cover and tighten the bolts gradually (the three screws at the furnace cover opening position and on the opposite side do not need to be tightened), and visually check whether the equipment indicator light is on.

[0020] ⑶Open the two air pipe valves on the furnace cover.

[0021] ⑷ Set the process parameters such as temperature and ramp time, load them into the temperature controller, turn on the circulating fan, click "Operation Monitoring", click "Start", and turn on the 3 heating switches.

[0022] ⑸ Annealing process route: such as Figure 2 As shown, the steps of annealing treatment include: heating the needle with the furnace for 3 hours, opening the exhaust valve to exhaust oil smoke, heating to 400°C, closing the exhaust valve, and evacuating; heating to 680°C and keeping it for 4 hours, cooling to 450°C for 3 hours and keeping it for 2.5 hours.

[0023] ⑹ Visually check that the sealing ring is intact.

[0024] ⑺ Vacuuming: Close the two air pipes of the furnace cover, turn off the switch of nitrogen flushing, evacuate the pressure to -0.5~1MPa, close all valves and operating buttons, and record the pressure gauge value.

[0025] ⑻ Nitrogen flushing: Close the vacuum valve, open the two nitrogen flushing valves, flush the nitrogen to a pressure of 0MPa, close all valves and operating buttons, and record the pressure gauge value.

[0026] ⑼ Select the process parameters and load them to the temperature controller, turn on the circulating fan, click on the operation monitoring and then click on start, and turn on the 3 heating switches.

[0027] ⑽After completing the process route in item ⑸, lift out the needle roller.

[0028] ⑾Comparison of hardness and metallographic structure before and after annealing, as shown in Table 1-Table 5.

[0029] Needle roller annealing test report (hardness, metallographic structure)

[0030]

[0031] Table 1

[0032]

[0033] Table 2

[0034]

[0035] Table 3

[0036]

[0037] Table 4

[0038]

[0039] Table 5

[0040] The present invention adds an annealing process after blanking and then performs SR, thereby shortening the SR forming time and improving production efficiency.

[0041] Taking the needle roller 2*9.4 as an example, the needle roller data before and after annealing are compared:

[0042] ⑴ The hardness before annealing is 307-332HV1, the metallographic structure is 2-3, and the hardness after annealing is 205-230HV1, the metallographic structure is 2-3. The hardness of the raw material is reduced by about 100HV1, and the metallographic structure remains unchanged.

[0043] (2) The SR time before annealing is 180h, and the SR time after annealing is 92h, which shortens the processing time by about 49%.

[0044] The present invention not only optimizes the annealing effect, but also improves the efficiency of subsequent SR processing.

[0045] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A needle roller annealing process, characterized in that: The following steps are involved: Step 1: Place the needle roller with two flat ends into a material frame, place the material frame flat into a pit furnace, set the temperature, ramp time and other related process parameters, anneal the needle roller, and reduce the hardness of the needle roller; Step 2: The annealed needle roller is subjected to SR processing to form both ends of the needle roller into a spherical shape, and then subjected to rounding treatment, heat treatment, and grinding in sequence to obtain a finished needle roller.

2. The needle roller annealing process according to claim 1, characterized in that: The steps of placing the needle roller into the pit furnace include: placing the needle roller into the material frame, lifting the material frame into the pit furnace with a crane, stacking the material frames flatly in the material frame, covering the furnace cover and gradually tightening the bolts, and opening the air pipe valve on the furnace cover.

3. The needle roller annealing process according to claim 2, characterized in that: The steps of setting the temperature and ramp time related process parameters include: setting the annealing temperature, heating rate, and holding time on the temperature controller, starting the circulating fan and the heating switch, and heating the roller needle according to the preset annealing process route.

4. The needle roller annealing process according to claim 3, characterized in that: The annealing treatment steps include: heating the needle with the furnace for 3 hours, opening the exhaust valve to exhaust oil smoke, heating to 400°C, closing the exhaust valve, and evacuating; heating to 680°C and keeping the temperature for 4 hours, cooling to 450°C for 3 hours and keeping the temperature for 2.5 hours, and after annealing, lifting the needle out of the pit furnace.

5. The needle roller annealing process according to claim 4, characterized in that: The annealing treatment step also includes: during the heating process, adjusting the atmosphere in the pit furnace by vacuuming and flushing with nitrogen, and recording the pressure gauge reading; specifically: vacuuming to a pressure of -0.5 to 1Mpa, closing the vacuum valve, opening the nitrogen flushing valve, and flushing with nitrogen to a pressure of 0Mpa.

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