Solid boriding strengthening method and device for inner hole of small-size titanium alloy cylindrical part

Abstract

The invention provides a solid boriding strengthening method and device for an inner hole of a small-size titanium alloy cylindrical part, and belongs to the technical field of metal surface strengthening treatment. The device comprises a positioning assembly and a clamping assembly which are packaged at the two ends of a cylindrical part, a heating assembly penetrating through an inner hole of the cylindrical part is fixed through the positioning assembly and the clamping assembly, and an annular cavity with the uniform radial thickness is formed between the wall face of the inner hole of the cylindrical part and the peripheral face of the heating assembly and used for being filled with a boronizing agent; and the temperature of the boronizing agent is controlled by the heating assembly in real time. The invention solves the problem that the device used in the current surface boronizing technology is difficult to enable the inner hole of the cylindrical part to reach a proper boronizing temperature in the treatment process.

Description

Technical Field

[0001] The invention belongs to the technical field of metal surface strengthening treatment, and in particular relates to a method and a device for strengthening the inner hole of a small-sized titanium alloy cylindrical part through solid boronizing. Background Art

[0002] Stainless steel is the main material used in flight control systems. This material has excellent processing properties such as welding performance, cold deformation performance, polishing performance, and high corrosion resistance and certain mechanical properties such as hardness and strength. Since the surface of stainless steel has a passivating chromium-rich oxide film, stainless steel has better acid and alkali resistance, formability, toughness, heat resistance and corrosion resistance. However, when used as a cylindrical material for flight control systems, stainless steel has higher requirements for wear resistance, so it is necessary to strengthen the surface of stainless steel to improve its wear resistance.

[0003] Surface strengthening treatment technology is a technology that uses surface coating, surface modification and several processing techniques to obtain or improve various properties of the body surface by changing the chemical composition, organizational structure and stress state of the body surface after pretreatment of the substrate. Commonly used surface strengthening treatment technologies include surface quenching, shot peening, spray coating, surface nitriding, surface boriding, etc., but the former two have no obvious effect on the surface strengthening of the material. The coating has poor bonding strength with the substrate. For cylinders below 60mm, the spraying process is complicated and the cost is high. Moreover, for cylinders with complex internal structures, it is almost impossible to achieve ideal results by spraying. For small and medium-sized cylinders with large aspect ratios in the flight control system, the nitriding process is affected by airflow and the effect is very poor. The solid boriding process has simple equipment requirements and simple process. The surface is easy to clean after boriding. For cylinders with complex internal structures, such as cylinders with step holes, the solid boriding process can also obtain ideal treatment results. In summary, the use of solid boriding process to strengthen the surface of stainless steel cylindrical parts can meet the lightweight requirements of the flight control system and is an ideal surface strengthening treatment method.

[0004] At present, traditional surface boronizing technology mostly uses box-type resistance furnaces, high-frequency equipment or protective atmosphere furnaces for heating. The devices used make it difficult to make the inner hole of the cylindrical part reach a suitable boronizing temperature during the processing process, which limits the application scenarios of the boronizing process. Therefore, it is urgent to design a solid boronizing device for the inner hole of the cylindrical part. Summary of the invention

[0005] Technical issues to be solved:

[0006] In order to avoid the shortcomings of the prior art, the present invention provides a method and device for solid boronizing strengthening of the inner hole of a small-sized titanium alloy cylindrical part. The heating component is fixed to the inner hole of the cylindrical part to be treated by the cooperation of the positioning component and the clamping component, and a boronizing agent of equal thickness is filled between the inner wall of the cylindrical part and the heating component to ensure that the boronizing agent is in full contact with the cylindrical part to prevent insufficient boronizing of the stepped hole or edge position of the cylindrical part; by controlling the temperature of the heating component, the inner hole of the cylindrical part is surface boronized at a set temperature. The present invention solves the problem that the device used in the current surface boronizing technology is difficult to make the inner hole of the cylindrical part reach a suitable boronizing temperature during the treatment process.

[0007] The technical solution of the present invention is: a solid boronizing strengthening device for the inner hole of a small-sized titanium alloy cylindrical part, including a positioning assembly and a clamping assembly encapsulated at both ends of the cylindrical part, and a heating assembly passing through the inner hole of the cylindrical part is fixed by the positioning assembly and the clamping assembly, and an annular cavity with uniform radial thickness is formed between the wall surface of the inner hole of the cylindrical part and the outer peripheral surface of the heating assembly, which is used to fill a boronizing agent; the temperature of the boronizing agent is controlled in real time by the heating assembly.

[0008] A further technical solution of the present invention is: the positioning assembly includes a base with a limiting structure and a main shaft for fixing the heating assembly, and the cylindrical part and the heating assembly are coaxially positioned on the base through the limiting structure respectively; the base is provided with a plurality of radial fasteners along the circumference to limit and fix the cylindrical part; the rod portion of the main shaft sequentially passes through the base, the center hole of the heating assembly, and the clamping assembly, and an external thread is provided at the end to connect with a nut, and the axial limiting and fixing of the base, the heating assembly, and the clamping assembly are completed through the cooperation of the main shaft head and the nut.

[0009] A further technical solution of the present invention is: three layers of annular stepped grooves are opened on the upper end surface of the base, the bottom of the groove located at the center position is the first layer, which serves as the positioning surface of the heating component, and the radial position of the heating component is limited by a layer of stepped side walls; the annular stepped surface adjacent to the bottom of the groove is the second layer, which serves as the bottom surface of the annular cavity filled with the boronizing agent; the annular stepped surface adjacent to the bottom surface of the annular cavity filled with the boronizing agent is the third layer, which serves as the positioning surface of the cylindrical part, and the radial position of the cylindrical part is limited by three layers of stepped side walls, and a plurality of radial threaded holes are opened on the circumferential surface of the three layers of stepped side walls, and the cylindrical part is radially pressed and fixed by adjusting the depth of the screws; a stepped through hole is opened on the lower end surface of the base at a position relative to the center of the positioning surface of the heating component, and its stepped surface is used to limit the axial position of the spindle head, and the small diameter end of the stepped hole is used to pass through the spindle rod.

[0010] A further technical solution of the present invention is: the heating component includes a heater, a high-temperature thermal resistance wire, a heat transfer body and a temperature sensor; the heater is a columnar structure with a central through hole, on which the high-temperature thermal resistance wire is evenly distributed, and a heat transfer body is sleeved on its periphery, and a temperature sensor is arranged on the heat transfer body; the temperature of the heat transfer body is collected by the temperature sensor, and the collected data is sent to the control system, and the control system adjusts the power of the heater, thereby adjusting the temperature of the heat transfer body to achieve the ideal temperature of the boronizing treatment.

[0011] A further technical solution of the present invention is: the heating assembly is of modular design, and the number of heating assemblies to be installed is selected according to the axial length of the cylindrical member. The total axial height of the required number of heating assemblies is greater than the axial height of the annular cavity filled with the boronizing agent, so as to fully heat the boronizing agent in the annular cavity.

[0012] A further technical solution of the present invention is: the clamping assembly includes a cylinder cover, a gasket, a cover plate, and an annular cover plate; the cover plate has the same radial cross-section and size as the heating assembly, is mounted on the main shaft and cooperates with a nut to press and fix multiple groups of heating assemblies on the base; the cylinder cover is an annular structure, the inner ring surface of which is consistent with the inner hole diameter of the cylindrical member, and is coaxially installed on the top of the cylindrical member. By installing the cylinder cover, the axial height of the annular cavity filled with the boronizing agent is greater than the axial height of the cylindrical member, so as to achieve sufficient boronization of the inner hole of the cylindrical member; the gasket is pressed onto the boronizing agent as the top surface of the annular cavity filled with the boronizing agent; the inner hole of the annular cover plate is a stepped hole, the large diameter end of which is coaxially mounted on the cover plate, and the small diameter end is used to pass through the end of the main shaft rod, and multiple screws pass through different circumferential positions of the annular cover plate, the screws opposite to the stepped surface of the annular cover plate are used to fix the annular cover plate and the cover plate, and the screws opposite to the gasket and the cylinder cover are used to apply axial pressing force to the gasket and the cylinder cover.

[0013] A further technical solution of the present invention is: the outer edge of the annular surface adjacent to the cylinder cover and the cylindrical member extends along the direction of the cylindrical member to obtain a radial limiting boss of the cylindrical member, and the limiting boss has multiple radial threaded holes along the circumferential direction, and the cylindrical member is radially compressed and fixed by adjusting the depth of the screw.

[0014] A method for strengthening the inner hole of a small-sized titanium alloy cylindrical part by solid boronizing, the specific steps are as follows:

[0015] Install the positioning assembly, embed the bottom end of the cylindrical member into the limiting structure of the positioning assembly and fix it, and install the cylinder cover on the top end of the cylindrical member;

[0016] The number of heating components is selected according to the axial height of the cylindrical component, and each heating component and cover plate are sequentially mounted on the main shaft of the positioning component, and are pressed and fixed on the positioning component by screwing the nut;

[0017] Fill the boronizing agent between the inner hole wall of the cylindrical part and the outer periphery of the heating component to a height greater than the axial height of the cylindrical part, and press the gasket onto the boronizing agent; then coaxially install the annular cover plate on the cover plate, and fasten the two with screws;

[0018] By screwing the screws opposite to the gasket and the cylinder cover, the gasket and the cylinder cover are pressed and fixed;

[0019] The temperature of the heat transfer body is collected by a temperature sensor, and the collected data is sent to the control system, which adjusts the power of the heater, thereby adjusting the temperature of the heat transfer body to achieve the ideal temperature for boriding treatment.

[0020] A further technical solution of the present invention is that the boronizing agent is a fine powder to promote its fluidity in the filling cavity.

[0021] A further technical solution of the present invention is that the total axial height of each heating component is greater than the filling height of the boronizing agent, so that the boronizing agent can be fully heated.

[0022] Beneficial Effects

[0023] The beneficial effects of the present invention are:

[0024] (1) The device of the present invention adopts an internal heating method to carry out the boronizing process of the inner hole of the cylindrical part, which can ensure that the inner hole surface reaches the ideal boronizing temperature;

[0025] (2) The present invention uses a fine powder boronizing agent, which has good fluidity and can fully contact with the surface of the complex inner hole, thereby solving the problem that the surface strengthening technology is difficult to strengthen the complex inner hole surface of the cylindrical part.

[0026] (3) The heating component of the device of the present invention adopts a modular design, and the boronizing requirements of cylindrical parts with different apertures can be met by adding, reducing and replacing modules.

[0027] (4) The device of the present invention uses a stepped base to ensure that the boronizing agent is fully heated, and the edge of the part and the boronizing agent are fully heated.

[0028] The experiment verified that the austenitic stainless steel cylinder was boronized for 11 hours at 910℃, and the present invention and the traditional boronizing device were used for testing respectively. The specific parameters are shown in Table 1. The comparison of microhardness was obtained. Figure 1 It can be seen that the workpiece subjected to boriding treatment using the present invention has a higher maximum microhardness and a thicker boriding layer.

[0029] Table 1

[0030]

[0031] BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of a solid boronizing strengthening device for the inner hole of a small-sized titanium alloy cylindrical part of the present invention;

[0033] Figure 2 This is a comparison chart of microhardness obtained by testing the present invention and the traditional boronizing device.

[0034] Explanation of the accompanying drawings: 1. Base; 2. Heater; 3. Heat transfer body; 4. Cylindrical member; 5. Step hole; 6. Boronizing agent; 7. Cylinder cover; 8. Washer; 9. Screw; 10. Screw; 11. Connecting wire; 12. High-temperature resistance wire; 13. Nut; 14. Screw; 15. Ring cover plate; 16. Cover plate; 17. Resistance wire hole; 18. Screw; 19. Temperature sensor; 20. Screw; 21. Spindle. DETAILED DESCRIPTION

[0035] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0037] Based on the problem that the devices used in the current surface boronizing technology are difficult to make the inner hole of the cylindrical part reach a suitable boronizing temperature during the treatment process, the present invention provides a solid boronizing strengthening device for the inner hole of a small-sized titanium alloy cylindrical part, including a positioning component and a clamping component encapsulated at both ends of the cylindrical part, and a heating component that passes through the inner hole of the cylindrical part is fixed by the positioning component and the clamping component to form an annular cavity with uniform radial thickness between the wall surface of the inner hole of the cylindrical part and the outer peripheral surface of the heating component for filling a boronizing agent; the temperature of the boronizing agent is controlled in real time by the heating component to achieve surface boronizing treatment of the inner hole of the cylindrical part.

[0038] Specifically, the positioning assembly includes a base with a limiting structure and a main shaft for fixing the heating assembly, and the cylindrical member and the heating assembly are coaxially positioned on the base through the limiting structure respectively; the base is provided with a plurality of radial fasteners along the circumference to limit and fix the cylindrical member; the rod portion of the main shaft sequentially passes through the base, the center hole of the heating assembly, and the clamping assembly, and an external thread is provided at the end to connect with a nut, and the axial limiting and fixing of the base, the heating assembly, and the clamping assembly are completed through the cooperation of the main shaft head and the nut.

[0039] Specifically, the upper end surface of the base is provided with three layers of annular stepped grooves, the bottom of the groove located at the center is the first layer, which serves as the positioning surface of the heating component, and the radial position of the heating component is limited by a layer of stepped side walls; the annular step surface adjacent to the bottom of the groove is the second layer, which serves as the bottom surface of the annular cavity filled with the boronizing agent; the annular step surface adjacent to the bottom surface of the annular cavity filled with the boronizing agent is the third layer, which serves as the positioning surface of the cylindrical part, and the radial position of the cylindrical part is limited by the three layers of stepped side walls, and a plurality of radial threaded holes are provided on the circumferential surface of the three layers of stepped side walls, and the cylindrical part is radially pressed and fixed by adjusting the depth of the screws; a stepped through hole is provided on the lower end surface of the base at a position relative to the center of the positioning surface of the heating component, and the stepped surface is used to limit the axial position of the spindle head, and the small diameter end of the stepped hole is used to pass through the spindle rod.

[0040] Specifically, the heating assembly includes a heater, a high-temperature thermal resistance wire, a heat transfer body and a temperature sensor; the heater is a columnar structure with a central through hole, on which the high-temperature thermal resistance wire is evenly distributed, and a heat transfer body is mounted on its periphery, and a temperature sensor is arranged on the heat transfer body; the temperature of the heat transfer body is collected by the temperature sensor, and the collected data is sent to the control system, and the control system adjusts the power of the heater, thereby adjusting the temperature of the heat transfer body to achieve an ideal temperature for boronizing treatment.

[0041] Specifically, the heating assembly is of modular design, and the number of heating assemblies to be installed is selected according to the axial length of the cylindrical member. The total axial height of the required number of heating assemblies is greater than the axial height of the annular cavity filled with the boronizing agent, so as to fully heat the boronizing agent in the annular cavity.

[0042] Specifically, the clamping assembly includes a cylinder cover, a gasket, a cover plate, and an annular cover plate; the cover plate has the same radial cross-section and size as the heating assembly, is mounted on the main shaft and cooperates with a nut to press and fix multiple groups of heating assemblies on the base; the cylinder cover is an annular structure, the inner annular surface of which is consistent with the inner hole diameter of the cylindrical member, and is coaxially installed on the top end of the cylindrical member. By installing the cylinder cover, the axial height of the annular cavity filled with the boronizing agent is greater than the axial height of the cylindrical member, so as to achieve sufficient boronization of the inner hole of the cylindrical member; the gasket serves as the top surface of the annular cavity filled with the boronizing agent and is pressed onto the boronizing agent; the inner hole of the annular cover plate is a stepped hole, the large diameter end of which is coaxially mounted on the cover plate, and the small diameter end is used to pass through the end of the main shaft rod, and multiple screws pass through different circumferential positions of the annular cover plate, the screws opposite to the stepped surface of the annular cover plate are used to fix the annular cover plate and the cover plate, and the screws opposite to the gasket and the cylinder cover are used to apply axial pressing force to the gasket and the cylinder cover.

[0043] Specifically, the outer edge of the annular surface of the cylinder cover adjacent to the cylindrical member extends along the direction of the cylindrical member to obtain a radial limiting boss of the cylindrical member. The limiting boss has multiple radial threaded holes along the circumferential direction, and the cylindrical member is radially compressed and fixed by adjusting the depth of the screws.

[0044] The above technical solution is further described below in conjunction with the accompanying drawings:

[0045] Reference Figure 1 As shown, this embodiment is a small-sized lightweight cylindrical part inner hole solid boronizing strengthening device, including a positioning component, a clamping component, and a heating component.

[0046] The positioning assembly includes a base 1, a spindle 21 mounted on the base 1, and a screw 20. The cylindrical member 4 is placed on the matching base 1. The base 1 is a stepped design. There are three steps that gradually rise from the spindle 21 to the edge of the base 1. From low to high, they correspond to the heater 2 / heat transfer body 3, the boronizing agent 6, and the cylindrical member 4, respectively, which can ensure that the heater 2 / heat transfer body 3 fully heats the boronizing agent 6, and also ensure that the boronizing agent 6 is in full contact with the cylindrical member 4 to prevent insufficient boronization at the bottom of the cylindrical member 4; at this time, the screw 20 is screwed into the screw hole on the base 1 to preliminarily fix the cylindrical member 4 and limit its degree of freedom.

[0047] The heating assembly includes a modular heater 2, a high temperature resistance wire 12, a modular heat transfer body 3, and a temperature sensor 19. The modular heater 2 is installed on the main shaft 21, and the number of installed modules can be freely selected according to the length of the cylindrical member 4; the heat transfer body 3 is sleeved on the heater 2, and the temperature sensor 19 is installed on the heat transfer body 3, which can monitor and feedback the temperature of the current location of the heat transfer body 3 module in real time. The control device can adjust the power of the heater 2 according to the feedback data, thereby adjusting the temperature of each heat transfer body 3 module, and then adjusting the temperature of the entire inner hole to ensure that the inner hole is at an ideal temperature for boronizing.

[0048] The clamping assembly includes a barrel cover 7, a screw 18, a washer 8, a cover plate 16, an annular cover plate 15, a nut 13, a screw 14 connecting the cover plate and the annular cover plate, a screw 10 installed on the annular cover plate for pressing the washer, and a screw 9 of the barrel cover. After the cylindrical member 4 is installed on the base 1, the matching cylinder cover 7 is installed on the cylindrical member 4, and the screw 18 is screwed into the screw hole on the cylinder cover 7 to fix the cylinder cover 7 on the cylinder body 4; the boronizing agent 6 is added between the heat transfer body 3 and the cylindrical member 4, and the fine powder boronizing agent 6 with good fluidity is selected, which can flow evenly in the gap; the inner diameter of the gasket 8 matches the heat transfer body 3, and the outer diameter matches the cylinder cover 7, which is used to apply pressure to the boronizing agent 6 to ensure that the inside of the cylindrical member 4 is fully in contact with the boronizing agent 6; the cover plate 16 is matched with the main shaft 21 and placed on the top of the heat transfer body 3 and is pressed by the nut 13; the annular cover plate 15 is fixedly connected to the cover plate 16 by the screw 14, and the annular cover plate 15 is provided with a plurality of screw holes along the circumferential direction at the positions corresponding to the gasket 8 and the cylinder cover 7. The screws 9 and 10 are screwed into the screw holes to apply pressure to the gasket 8 and the cylinder cover 7, thereby clamping the cylindrical member 4.

[0049] The specific usage process is as follows:

[0050] (1) The main shaft 21 is connected to the base 1 through the hole at the bottom of the base 1. The cylindrical member 4 is placed on the base 1, and the screws 20 are screwed into the screw holes on the base 1 to fix the cylindrical member 4 on the base 1; the cylinder cover 7 is placed on the cylindrical member 4, and the cylinder cover 7 and the cylindrical member 4 are simply fixed by screwing in the screws 18.

[0051] (2) According to the inner diameter and length of the cylindrical member 4, a suitable heater 2 is selected. The heater 2 has a resistance wire hole 17. The high-temperature resistance wire 12 can be connected to each heater 2 module through the resistance wire hole 17. The connected heater 2 modules are positioned and placed on the base 1 through the main shaft 21; the modular heat transfer body 3 equipped with the temperature sensor 19 is sleeved on the outside of the heater 2 to complete the installation of the heating component.

[0052] (3) Select fine powder boronizing agent 6. After the above heating assembly is installed, add the selected boronizing agent 6 into the gap between the inner hole of the cylindrical member 4 and the heat transfer body 3. When the height of the boronizing agent 6 in the gap is slightly higher than the upper edge of the cylindrical member 4, place the gasket 8.

[0053] (4) The center hole of the cover plate 16 matches the main shaft 21, and the cover plate 16 is placed on the heater 2 and the heat transfer body 3, and the nut 13 is installed on the main shaft 21 and tightened to fix the cover plate 16; the annular cover plate 15 is fixedly connected to the cover plate 16 by screws 14. At this time, screws 18 and screws 20 are removed to prevent damage to the outer edge of the cylindrical member 4 when clamping the cylindrical member 4. Screws 9 and 10 are screwed into the several screw holes arranged along the circumferential direction on the annular cover plate 15 corresponding to the positions of the gasket 8 and the cylinder cover 7. The screw 9 applies pressure to the cylinder cover 7 along the axial direction of the cylindrical member 4, thereby clamping the cylindrical member 4; the screw 10 applies pressure to the gasket 8 along the axial direction of the cylindrical member 4, and the gasket 8 compresses the boronizing agent 6 to flow, eliminating the gap between the boronizing agent 6 and the inner hole of the cylindrical member 4. When the cylindrical member 4 has a stepped hole 5, the stepped hole 5 can also be completely filled with the boronizing agent to prevent uneven boronization. At this point, the assembly of the solid boronizing device for the inner hole of the cylindrical part is completed.

[0054] (5) During operation, an external current flows through the high-temperature resistance wire 12 in the heater 2, and the electrical energy is converted into thermal energy, causing the heater 2 to start heating. The heat of the heater 2 is transferred to the boriding agent 6 through the heat transfer body 3, gradually heating the boriding agent 6 to reach the temperature required for the boriding process. The temperature sensor 19 installed on the heat transfer body 3 can monitor and feedback the temperature of the boriding agent 6 at its location in real time. The control device can adjust the power of the heater 2 of the corresponding module according to the feedback data, thereby changing the local temperature of the boriding agent 6 to ensure that each part of the inner hole of the cylindrical member 4 is at the ideal boriding temperature.

[0055] Figure 2 The figure shows the change of microhardness of the cylindrical part with depth after the austenitic stainless steel is treated by the present invention and the conventional boronizing device. Table 1 shows the specific parameters and results of the experiment. It can be seen that the microhardness of the cylindrical part treated by the boronizing device of the present invention is greater than that of the cylindrical part treated by the conventional boronizing device, and the thickness of the nitriding layer is thicker. This is because the present invention can ensure that the temperature of the contact part between the inner surface of the cylindrical part and the boronizing agent reaches the preset temperature, while the boronizing temperature set by the conventional boronizing device does not match the actual temperature of the workpiece surface. From the data in Table 1, it can be seen that the thickness of the boronized layer of the workpiece treated by the present invention is increased by about 16.7%.

[0056] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A solid boronizing strengthening device for the inner hole of a small-sized titanium alloy cylindrical part, characterized in that: It includes a positioning component and a clamping component encapsulated at both ends of the cylindrical member. The heating component that passes through the inner hole of the cylindrical member is fixed by the positioning component and the clamping component, and an annular cavity with uniform radial thickness is formed between the wall surface of the inner hole of the cylindrical member and the outer peripheral surface of the heating component for filling a boronizing agent; the temperature of the boronizing agent is controlled in real time by the heating component.

2. According to claim 1, a small-sized titanium alloy cylindrical part inner hole solid boronizing strengthening device is characterized in that: The positioning assembly includes a base with a limiting structure and a main shaft for fixing the heating assembly. The cylindrical member and the heating assembly are coaxially positioned on the base through the limiting structure respectively. The base is provided with a plurality of radial fasteners along the circumference to limit and fix the cylindrical member. The rod of the main shaft sequentially passes through the base, the center hole of the heating assembly, and the clamping assembly, and an external thread is provided at the end to connect with a nut. The axial limiting and fixing of the base, the heating assembly, and the clamping assembly are completed through the cooperation of the main shaft head and the nut.

3. According to claim 2, a small-sized titanium alloy cylindrical part inner hole solid boronizing strengthening device is characterized in that: The upper end surface of the base is provided with three layers of annular stepped grooves, the bottom of the groove located at the center is the first layer, which serves as the positioning surface of the heating component, and the radial position of the heating component is limited by a layer of stepped side walls; the annular stepped surface adjacent to the bottom of the groove is the second layer, which serves as the bottom surface of the annular cavity filled with the boronizing agent; the annular stepped surface adjacent to the bottom surface of the annular cavity filled with the boronizing agent is the third layer, which serves as the positioning surface of the cylindrical part, and the radial position of the cylindrical part is limited by the three layers of stepped side walls, and a plurality of radial threaded holes are provided on the circumferential surface of the three layers of stepped side walls, and the cylindrical part is radially pressed and fixed by adjusting the depth of the screws; a stepped through hole is provided on the lower end surface of the base at a position relative to the center of the positioning surface of the heating component, and the stepped surface is used to limit the axial position of the spindle head, and the small diameter end of the stepped hole is used to pass through the spindle rod.

4. According to claim 3, a small-sized titanium alloy cylindrical part inner hole solid boronizing strengthening device is characterized in that: The heating assembly includes a heater, a high-temperature thermal resistance wire, a heat transfer body and a temperature sensor; the heater is a columnar structure with a central through hole, on which the high-temperature thermal resistance wire is evenly distributed, and a heat transfer body is sleeved on its periphery, and a temperature sensor is arranged on the heat transfer body; the temperature of the heat transfer body is collected by the temperature sensor, and the collected data is sent to the control system, and the control system adjusts the power of the heater, thereby adjusting the temperature of the heat transfer body to achieve an ideal temperature for boronizing treatment.

5. According to claim 4, a small-sized titanium alloy cylindrical part inner hole solid boronizing strengthening device is characterized in that: The heating assembly is of modular design. The number of heating assemblies to be installed is selected according to the axial length of the cylindrical member. The total axial height of the required number of heating assemblies is greater than the axial height of the annular cavity filled with the boronizing agent, so as to fully heat the boronizing agent in the annular cavity.

6. The device for strengthening the inner hole of a small-sized titanium alloy cylindrical part by solid boronizing according to claim 5, characterized in that: The clamping assembly comprises a cylinder cover, a gasket, a cover plate and an annular cover plate; the cover plate has the same radial cross section and size as the heating assembly, is sleeved on the main shaft and cooperates with a nut to press and fix multiple groups of heating assemblies on the base; the cylinder cover is an annular structure, the inner annular surface of which is consistent with the inner hole diameter of the cylindrical member, and is coaxially installed on the top end of the cylindrical member. By installing the cylinder cover, the axial height of the annular cavity filled with the boronizing agent is greater than the axial height of the cylindrical member, so as to achieve sufficient boronization of the inner hole of the cylindrical member; the gasket is pressed onto the boronizing agent as the top surface of the annular cavity filled with the boronizing agent; the inner hole of the annular cover plate is a stepped hole, the large diameter end of which is coaxially sleeved on the cover plate, and the small diameter end is used to pass through the end of the main shaft rod, and multiple screws pass through different circumferential positions of the annular cover plate, the screws opposite to the stepped surface of the annular cover plate are used to fix the annular cover plate and the cover plate, and the screws opposite to the gasket and the cylinder cover are used to apply axial pressing force to the gasket and the cylinder cover.

7. The device for strengthening the inner hole of a small-sized titanium alloy cylindrical part by solid boronizing according to claim 6, characterized in that: The outer edge of the annular surface of the cylinder cover adjacent to the cylindrical member extends along the direction of the cylindrical member to obtain a radial limiting boss of the cylindrical member. The limiting boss is circumferentially provided with a plurality of radial threaded holes, and the cylindrical member is radially compressed and fixed by adjusting the depth of the screws.

8. A method for strengthening the inner hole of a small-sized titanium alloy cylindrical part by solid boronizing, which is implemented based on the device for strengthening the inner hole of a small-sized titanium alloy cylindrical part by solid boronizing according to any one of claims 1 to 7, characterized in that The specific steps are as follows: Install the positioning assembly, embed the bottom end of the cylindrical member into the limiting structure of the positioning assembly and fix it, and install the cylinder cover on the top end of the cylindrical member; The number of heating components is selected according to the axial height of the cylindrical component, and each heating component and cover plate are sequentially mounted on the main shaft of the positioning component, and are pressed and fixed on the positioning component by screwing the nut; Fill the boronizing agent between the inner hole wall of the cylindrical part and the outer periphery of the heating component to a height greater than the axial height of the cylindrical part, and press the gasket onto the boronizing agent; then coaxially install the annular cover plate on the cover plate, and fasten the two with screws; By screwing the screws opposite to the gasket and the cylinder cover, the gasket and the cylinder cover are pressed and fixed; The temperature of the heat transfer body is collected by a temperature sensor, and the collected data is sent to the control system, which adjusts the power of the heater, thereby adjusting the temperature of the heat transfer body to achieve the ideal temperature for boriding treatment.

9. A method for strengthening the inner hole of a small-sized titanium alloy cylindrical part by solid boronizing according to claim 8, characterized in that: The boronizing agent is in the form of fine powder, which promotes its fluidity in the filling cavity.

10. The method for strengthening the inner hole of a small-sized titanium alloy cylindrical part by solid boronizing according to claim 8, characterized in that: The total axial height of each heating component is greater than the filling height of the boronizing agent, so the boronizing agent can be fully heated.

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