Interference bushing press-in method

Abstract

The invention discloses an interference bushing press-in method which comprises the following steps: S1, designing and manufacturing a bushing press-in device matched with a to-be-mounted metal part in shape and structural characteristics; s2, the lining device is placed in liquid nitrogen to be frozen for 20-30 minutes, so that the magnitude of interference generated by low-temperature shrinkage of the lining device is reduced, and follow-up assembly is facilitated; s3, a to-be-mounted metal part is fixed to the stable platform, the frozen lining device is connected with the to-be-mounted metal part, and a bolt of the lining device penetrates through the to-be-mounted metal part; s4, press-in operation is conducted through the lining device, so that the shoulder lining of the metal part to be installed is attached to a gasket of the lining device, and the nut is screwed down; and S5, after press-in is completed, the lining device is removed, visual detection is conducted on the shoulder lining, and whether deflection exists or not is determined. Through the designed press-in tool, the pressure applied to the bushing can be accurately controlled, the problem that the bushing deflects due to uneven hammering force is solved, and therefore the accuracy and reliability of installation are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of interference bushing press-in of metal parts, and in particular relates to an interference bushing press-in method. Background Art

[0002] Interference fit is a common method in mechanical assembly. It generates a clamping force through the size difference between the shaft and the hole, ensures the stability of the bushing during operation, and can transmit loads such as torque and axial force. The traditional bushing press-in method usually uses a hammer to directly hit the bushing so that it gradually enters the mounting hole. Although this method is simple, it has many disadvantages: first, it is difficult to accurately control the size and direction of the striking force, which can easily cause the bushing to deflect, leading to uneven wear and reduced service life; second, the impact force generated during the hammering process may cause damage to the surface of the bushing and the mounting hole, especially for high-precision parts. This damage may cause fatigue cracks and eventually cause component failure. In addition, in an environment with limited space, traditional tools and methods are often difficult to use, making the installation of interference bushings particularly difficult. Therefore, finding a more precise, safe and narrow space-adaptable interference bushing press-in method has become an urgent need in the industry. Summary of the invention

[0003] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide an interference bushing press-in method to solve multiple problems existing in traditional installation methods. It not only improves the installation quality and efficiency, but also provides a new solution for interference fit in complex environments, which has important practical application value.

[0004] To solve the above problems, the technical solution adopted by the present invention is as follows: a method for pressing an interference sleeve, comprising the following steps:

[0005] S1: Design and manufacture a press-fit bushing device that matches the shape and structural features of the metal part to be installed;

[0006] S2: freezing the bushing device in liquid nitrogen for 20-30 minutes to reduce the interference caused by low-temperature shrinkage of the bushing device, so as to facilitate subsequent assembly;

[0007] S3: Fixing the metal part to be installed on a stable platform, and connecting the frozen bushing device to the metal part to be installed, so that the bolt of the bushing device passes through the installation metal part;

[0008] S4: performing a press-in operation through the bushing device to make the shoulder bushing of the metal part to be installed fit with the gasket of the bushing device, and tightening the nut;

[0009] S5: After the press-in is completed, the bushing device is removed and the shoulder bushing is visually inspected to confirm whether there is any deflection.

[0010] Compared with the prior art, the beneficial effects of the present invention are: through a specially designed pressing tool, the pressure applied to the bushing can be accurately controlled, avoiding the problem of bushing deflection caused by uneven hammering force, thereby improving the accuracy and reliability of installation, and using liquid nitrogen freezing technology to cold-treat the bushing installation tool, thereby improving the hardness and wear resistance of the mold, effectively avoiding damage to the bushing and the surface of the mounting hole caused by the impact force, and maintaining the original performance and life of the component. At the same time, the pressing method proposed in this application is particularly suitable for occasions with limited space, such as the interior of aviation equipment, and the installation of the interference bushing can be successfully completed even in a narrow space, greatly expanding the scope of application. Moreover, the entire installation process does not require a complex fixing device, and only a simple platform and weights are needed to fix the metal parts, which reduces the difficulty of operation and improves work efficiency.

[0011] In the above-mentioned pressing method, the bushing device is made of Q2235 steel.

[0012] In the above-mentioned pressing method, the bushing device needs to be quenched before being subjected to liquid nitrogen cryogenic treatment in step S2, the quenching temperature range is 750° C.-860° C., and the holding time is 10-15 minutes.

[0013] In the above-mentioned pressing method, in the freezing treatment of liquid nitrogen in step S2, the cooling rate is 1°C / min-5°C / min, so that the austenite stability in the bushing device is gradually reduced.

[0014] In the above-mentioned pressing method, the freezing treatment temperature range of the liquid nitrogen in step S2 is -150°C to -196°C.

[0015] In the above-mentioned pressing method, in the freezing treatment of liquid nitrogen in step S2, the bushing device can be kept at -196°C for more than or equal to 24 hours to promote the transformation of the retained austenite to martensite.

[0016] In the above-mentioned pressing method, the bushing device includes two washers, two nuts and the bolt, the two washers are respectively located at the two ends of the bolt, and the two nuts are respectively located at the upper end surface and the lower end surface of the two washers.

[0017] In the above-mentioned press-fitting method, the diameter of the gasket of the bushing device is 30 mm larger than the diameter of the shoulder bushing of the metal part to be installed.

[0018] In the above-mentioned pressing method, the gasket is sleeved on the bolt

[0019] In the above-mentioned pressing method, the nut is screwed to the bolt. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the steps of the pressing method according to an embodiment of the present invention;

[0021] Figure 2 It is a structural schematic diagram of the connection between the bushing device and the metal part to be installed according to the embodiment of the present invention;

[0022] Figure 3 It is a structural schematic diagram of a bushing device according to an embodiment of the present invention;

[0023] Description of reference numerals: 100 metal part to be installed, 110 bushing with shoulder, 200 bushing device, 210 bolt, 220 washer, 230 nut. DETAILED DESCRIPTION

[0024] The embodiments of the present invention are described in detail below. Figures 1 to 3 The embodiment of the present invention provides an interference bushing press-in method, comprising the following steps: S1: designing and manufacturing a press-in bushing device 200 that matches the shape and structural features of a metal part 100 to be installed; S2: freezing the bushing device 200 in liquid nitrogen for 20-30 minutes to reduce the interference caused by the low-temperature shrinkage of the bushing device 200, so as to facilitate subsequent assembly; S3: fixing the metal part 100 to be installed on a stable platform, and connecting the frozen bushing device 200 to the metal part 100 to be installed, so that the bolt 210 of the bushing device 200 passes through the metal part 100 to be installed;

[0025] S4: Perform a press-in operation through the bushing device 200 to make the shoulder bushing 110 of the metal part 100 to be installed fit with the gasket 220 of the bushing device 200, and tighten the nut 230; S5: After the press-in is completed, remove the bushing device 200 and visually inspect the shoulder bushing 110 to confirm whether there is any deflection. The specially designed press-in tool can accurately control the pressure applied to the bushing, avoid the bushing deflection problem caused by uneven hammering force, and thus improve the accuracy and reliability of installation. In addition, the bushing device 200 is cold-treated by liquid nitrogen freezing technology, which improves the hardness and wear resistance of the mold, effectively avoids damage to the bushing and the surface of the mounting hole caused by the impact force, and maintains the original performance and life of the component. At the same time, the press-in method proposed in this application is particularly suitable for occasions with limited space, such as inside aviation equipment, and the installation of the interference bushing can be successfully completed even in a narrow space, greatly expanding the scope of application. Moreover, the entire installation process does not require complicated fixing devices. Only a simple platform and heavy objects are needed to fix the metal parts, which reduces the difficulty of operation and improves work efficiency.

[0026] Furthermore, the present invention proposes a method for pressing an interference bushing, which ensures the high matching of the tool and the metal part 100 to be installed by designing and manufacturing a press-in bushing device 200 that matches the shape and structural features of the metal part 100 to be installed in step S1, thereby improving the stability and accuracy during the assembly process. In step S2, the bushing device 200 is placed in liquid nitrogen and frozen for 20-30 minutes, and the bushing is shrunk by low temperature, which reduces the interference, making subsequent assembly operations easier and reducing potential damage to the bushing and the surface of the mounting hole. Preferably, the bushing device 200 is subjected to quenching treatment before being subjected to liquid nitrogen cryogenic treatment in step S2, and the quenching temperature range is 750℃-860℃, and the holding time is 10-15 minutes. Quenching treatment is an important means to improve the hardness and strength of the material. It can change the internal structure of the material of the bushing device 200 to form high-strength structures such as martensite or bainite, thereby significantly improving the mechanical properties of the bushing device 200. After quenching, the hardness and wear resistance of the bushing device 200 are greatly enhanced, which helps to reduce wear during the pressing process and extend the service life of the tool. However, the selection of quenching temperature and holding time is crucial. Too high or too low temperature and too long or too short time will affect the final quenching effect. Therefore, setting a quenching temperature range of 750℃-860℃ and a holding time of 10-15 minutes is the best solution to balance energy consumption and production efficiency while ensuring the quenching effect.

[0027] Furthermore, the present invention does not limit the specific material of the bushing device 200. Preferably, the bushing device 200 is made of Q2235 steel. The use of Q2235 steel can ensure that the bushing device 200 will not be deformed or damaged when subjected to a large pressing force, thereby ensuring the smooth completion of the bushing pressing operation. In addition, Q2235 steel has excellent heat treatment performance, and the hardness and toughness can be adjusted through processes such as quenching and tempering to adapt to different working conditions. During the interference bushing pressing process, the bushing device 200 needs to withstand large axial and radial forces, so the use of Q2235 steel can significantly increase the service life of the tool and reduce maintenance costs.

[0028] Furthermore, in the freezing treatment of liquid nitrogen in step S2, the cooling rate is 1°C / min-5°C / min, so that the stability of austenite in the bushing device 200 is gradually reduced. When the cooling rate is too fast, it may cause greater thermal stress inside the material, increasing the risk of cracks; while if the cooling rate is too slow, the transformation process will be prolonged and the production efficiency will be reduced. Therefore, controlling the cooling rate between 1°C / min-5°C / min can not only effectively promote the transformation of austenite to martensite, but also avoid the negative effects caused by improper cooling rate.

[0029] Furthermore, the temperature range of the freezing treatment of liquid nitrogen in step S2 is -150°C to -196°C. The selection of the temperature range is based on the thermophysical properties of the bushing material, especially its shrinkage behavior at low temperatures. Within this temperature range, the bushing will experience significant volume shrinkage, thereby effectively reducing the interference and facilitating subsequent assembly operations. More importantly, the low-temperature treatment at -150°C to -196°C can promote the transformation of the retained austenite inside the bushing material to martensite, which not only increases the hardness and strength of the material, but also improves its dimensional stability and wear resistance.

[0030] Furthermore, in the freezing treatment of liquid nitrogen in step S2, the bushing device 200 can be kept at -196°C for more than or equal to 24 hours to promote the transformation of the retained austenite to martensite. The purpose of this measure is to ensure that all austenite can be fully transformed into martensite, thereby maximizing the hardness, strength and dimensional stability of the bushing device 200. Maintaining it for a long time in a low temperature environment can slow down the movement of atoms inside the material, which is conducive to the formation and development of new phases. Especially at the extremely low temperature of -196°C, the stability of the retained austenite gradually decreases, and the martensitic transformation can be carried out more completely.

[0031] Further, refer to Figure 2 and Figure 3 The bushing device 200 proposed by the present invention includes two washers 220, two nuts 230 and a bolt 210. The two washers 220 are respectively located at the two ends of the bolt 210, and the two nuts 230 are respectively located on the upper end surface and the lower end surface of the two washers 220. This design enables the bushing device 200 to evenly distribute the applied pressure during the pressing process, avoiding the bushing deflection or damage caused by excessive local force. The presence of the washer 220 can not only protect the surface of the bushing and the mounting hole from direct impact, but also play a role in adjusting the pressing depth to ensure that the bushing is correctly embedded in the predetermined position. The combined use of the nut 230 and the washer 220 provides a reliable fixing method, so that in the process of tightening the nut 230, the bushing can fit the mounting hole tightly and achieve a good interference fit. In addition, this structure is simple and easy to operate, does not require complex assembly tools, reduces the difficulty of operation, and improves work efficiency. In practical applications, the design of the above-mentioned bushing device 200 is particularly suitable for interference bushing pressing in a small space, and can ensure the accuracy and reliability of installation even in a restricted environment.

[0032] Of course, the present invention does not limit the specific size of the bushing device 200. Preferably, the diameter of the gasket 220 of the bushing device 200 is 30 mm larger than the diameter of the shoulder bushing 110 of the metal part 100 to be installed. Because during the pressing process, the bushing device 200 needs to provide sufficient support area to ensure that the applied pressure can be evenly distributed around the bushing to prevent the bushing from being deflected or damaged due to local uneven force. Preferably, the gasket 220 is sleeved on the bolt 210, and the nut 230 is screwed with the bolt 210. The sleeve connection not only ensures the relative fixation between the gasket 220 and the bolt 210, but also allows the position of the gasket 220 to be flexibly adjusted during the pressing process to accommodate bushings of different sizes and shapes. The screwing of the nut 230 and the bolt 210 provides a strong clamping force, so that the bushing can be firmly embedded in the mounting hole, achieving an ideal interference fit. The screwing process can not only accurately control the pressing depth, but also ensure that the bushing is evenly pressurized by gradually increasing the tightening force, thus avoiding bushing deflection or damage caused by applying excessive pressure at one time.

[0033] It should be noted that in the description of the present invention, if there are any orientation descriptions, such as up, down, front, back, left, right, etc., the orientations or positional relationships indicated are all based on the orientations or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed or operated in a specific orientation, and cannot be understood as a limitation on the present invention.

[0034] In the description of the present invention, "several" means one or more, "more" means two or more, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used to distinguish the technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0035] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0036] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A method for pressing an interference sleeve, characterized in that: The following steps are involved: S1: Designing and manufacturing a press-fit bushing device (200) that matches the shape and structural features of the metal part (100) to be installed; S2: freezing the bushing device (200) in liquid nitrogen for 20-30 minutes to reduce the interference caused by low-temperature shrinkage of the bushing device (200) to facilitate subsequent assembly; S3: fixing the metal part (100) to be installed on a stable platform, and connecting the frozen bushing device (200) to the metal part (100) to be installed, so that the bolt (210) of the bushing device (200) passes through the installation metal part (100); S4: performing a press-in operation through the bushing device (200) so that the shoulder bushing (110) of the metal part (100) to be installed fits with the gasket (220) of the bushing device (200), and tightening the nut (230); S5: After the pressing is completed, the bushing device (200) is removed and the shoulder bushing (110) is visually inspected to confirm whether there is any deflection.

2. The pressing method according to claim 1, characterized in that: The bushing device (200) is made of Q2235 steel.

3. The pressing method according to claim 1, characterized in that: In the step S2, the bushing device (200) needs to be quenched before being subjected to liquid nitrogen cryogenic treatment, the quenching temperature range is 750° C. to 860° C., and the holding time is 10 to 15 minutes.

4. The pressing method according to claim 1, characterized in that: In the freezing treatment with liquid nitrogen in step S2, the cooling rate is 1°C / min to 5°C / min, so that the austenite stability in the bushing device (200) is gradually reduced.

5. The pressing method according to claim 1, characterized in that: The freezing treatment temperature range of the liquid nitrogen in step S2 is 150° C. to 196° C.

6. The pressing method according to claim 5, characterized in that: During the freezing treatment with liquid nitrogen in step S2, the bushing device (200) can be kept at 196°C for more than or equal to 24 hours to promote the transformation of the retained austenite into martensite.

7. The pressing method according to claim 1, characterized in that: The bushing device (200) comprises two washers (220), two nuts (230) and the bolt (210), the two washers (220) are respectively located at two ends of the bolt (210), and the two nuts (230) are respectively located at the upper end surface and the lower end surface of the two washers (220).

8. The pressing method according to claim 7, characterized in that: The diameter of the gasket (220) of the bushing device (200) is 30 mm larger than the diameter of the shoulder bushing (110) of the metal part (100) to be installed.

9. The pressing method according to claim 7, characterized in that: The gasket (220) is sleeved on the bolt (210).

10. The pressing method according to claim 7, characterized in that: The nut (230) is screwed to the bolt (210).

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