A barrel inner surface modification device

Abstract

The present application relates to a kind of barrel inner surface modification device, including two explosion guns and two plasma accelerators;Two plasma accelerators are in with reaction chamber, and the open end section is formed with one end of reaction chamber;Two reaction chambers are connected at open end section;Two explosion guns are respectively assembled in two ends of two reaction chambers;Wherein, explosion gun is connected to nozzle by auxiliary pipe and movable pipeline, and insulator, rod electrode and current lead are installed on the axis of reaction chamber;Insulator is assembled in the end of two reaction chambers;Axial electrode is built into reaction chamber, and two ends pass through insulator and are connected with current lead;The present application is simple in structure, ingenious in design, mainly used for the modification of the inner surface of cylindrical workpiece, and the focusing of plasma in pipe is used to increase energy density to ensure modification effect.

Description

Technical Field

[0001] This invention relates to the field of surface engineering technology, and in particular to a device for modifying the inner surface of a cylinder. Background Technology

[0002] Existing Patent ①: A device for localized heating. IPC: B23K1 / 005. Russian Patent No. 2025234. It serves as a heat source for heating the surface of a workpiece in brazing technology. The device includes a process nozzle comprising a hollow cylinder for supplying gas, a medium, or a substance to its front end, and at least one coaxial hollow cylinder for removing evaporation products. The nozzle is mounted along the axis of a reflector. An inner reflective surface covers a ring-shaped light source and forms a converging surface with the outer reflective surface in a rotating manner, concentrating the radiant energy of the heat source in the heating area onto the workpiece surface.

[0003] The drawback of this device is its low energy density, which prevents the preparation of coatings for refractory metals and alloys by rapidly heating the inner surface of the product.

[0004] Another known type of ion-plasma processing device ②: A device for preparing coatings via gas discharge plasma. IPC: C23C14 / 34. Russian Patent No. 2110606; This device can be effectively applied to various coating materials. It is economical and can process long workpieces in batches. The device includes a vacuum chamber, a working gas source, and a reactive gas source, with a circular plate coaxially mounted inside the vacuum chamber. The device also includes: an electrically insulating plate, a cylindrical target, a composite thermionic cathode consisting of several modules fixed to the circumference of the insulating plate, an annular anode fixed between the insulating plates, and a workpiece holder.

[0005] This device can deposit single or multi-element coatings using different targets, and utilizes ion or electron bombardment-assisted surface treatment to sputter target atoms onto the surface-activated workpiece surface. During operation, a rotating mechanism causes the workpiece to rotate around an axis to ensure uniform surface processing.

[0006] This invention can be used to prepare protective coatings, optical coatings, decorative coatings, and other coatings on the surfaces of metal, glass, and ceramic workpieces. It can be applied to the manufacture of components for solar energy absorption devices and medical, industrial, and household products.

[0007] The disadvantages of this device are that it requires processing in a vacuum environment, which reduces efficiency due to the inability to concentrate energy density, and it cannot use compact electrodes to prepare high-quality coatings; its disadvantages also include the need to heat the entire workpiece, making it impossible to process the workpiece surface or local areas.

[0008] A known method and apparatus for plasma explosion processing of metal products ③: European Patent, Application No.: 91907287.6INT.cl. 5C23C 4 / 00, B05B 7 / 20. Publication No.: 0531527A1; According to this invention, a pulsed plasma generator has two combustion chambers—a reaction chamber and a detonation chamber—filled with a combustible gas mixture and metal powder materials of elements from Groups III, IV, V, and VI of the periodic table. A spark plug is fixed in the detonation combustion chamber and can periodically ignite the combustible gas mixture at the gas mixture. In the reaction chamber, the detonation combustion mode takes place in an electromagnetic field generated by the conversion current of the combustion products. This invention processes metal surfaces through a high-energy jet of combustion products and powder materials. Simultaneously, the powder materials and plasma compounds are deposited on the metal surface. Due to rapid heating and cooling, recrystallization and dispersion alloying occur on the metal surface. This device can be used to harden the worn surfaces of mechanical parts and tools.

[0009] The disadvantages of this invention are that using powder materials to modify the workpiece surface alters its geometric parameters. Furthermore, the modified surface is heated using plasma jet heating, and the heating rate is limited due to the convection mechanism of the heat transfer medium. Therefore, the heating and cooling rates of the workpiece surface are insufficient for recrystallization and the formation of nanocrystalline materials. Uneven introduction of combustion products in the reaction chamber leads to uneven discharge in the electrode gaps, resulting in localized corrosion of the electrode surfaces. The device cannot prepare a hardened layer on the cylinder surface, which limits its application range.

[0010] Therefore, it is necessary to improve upon the above-mentioned issues. Summary of the Invention

[0011] The main objective of this patent is to provide a device for modifying the inner surface of a cylinder, which can prepare a hardened layer on the inner surface of a workpiece in a pulsed plasma atmosphere without the need for pretreatment such as cleaning; improve the hardening effect of the device on the metal surface, improve the uniform distribution of alloying elements, and improve the modification quality and productivity of the inner surface of the workpiece.

[0012] To achieve the above objectives, the technical solution adopted by this invention is as follows: a cylindrical inner surface modification device, comprising two explosive guns and two plasma accelerators; each of the two plasma accelerators has a reaction chamber, one end of which has an open end section; the two reaction chambers are connected at the open end section; the two explosive guns are respectively mounted at both ends of the two reaction chambers; wherein, the explosive guns are connected to nozzles through auxiliary pipes and movable pipes, and an insulator, a rod-shaped electrode, and a current lead are installed on the axis of the reaction chamber; the insulator is mounted at the end of the two reaction chambers; the axial electrode is built into the reaction chamber, and its two ends pass through the insulator and are connected to the current lead.

[0013] As a preferred embodiment of the present invention, the cross-section of the opening end of the reaction chamber is acute.

[0014] As a preferred embodiment of the present invention, the sectional angle of the open end of the reaction chamber is 45°.

[0015] In a preferred embodiment of the present invention, the nozzle is aligned with the opening end of the explosive gun, and the nozzle introduces one or more alloying elements or compounds into the explosive gun.

[0016] As a preferred embodiment of the present invention, the explosive gun has a single gas supply source and detonation source, and the two explosive guns are placed symmetrically and closely fitted with the closed part of the reaction chamber.

[0017] In a preferred embodiment of the present invention, the axial electrode is coaxial with the axis of the reaction chamber, and its axial movement is compensated as its end is consumed, and it is cooled by airflow.

[0018] In a preferred embodiment of the present invention, the axial electrode is mounted along the axis of the reaction chamber and its surface contains alloying elements.

[0019] As a preferred embodiment of the present invention, the alloying element is an element of Group III, IV, V, or VI of the periodic table; the alloying element is placed on the end of the reaction chamber and the surface of the axial electrode in the form of a regenerable coating.

[0020] In a preferred embodiment of the present invention, two axial electrodes are provided, and the axial electrodes are installed along the axis of the reaction chamber.

[0021] As a preferred embodiment of the present invention, it further includes a robotic gripper for rotating and moving the cylindrical workpiece 360° horizontally, the robotic gripper being located at the upper end of the cylindrical workpiece.

[0022] The beneficial effects of this invention are:

[0023] 1. This invention has a simple structure and ingenious design. It is mainly used for the modification of the inner surface of cylindrical workpieces. The modification effect is ensured by increasing the energy density through the focusing of plasma inside the tube.

[0024] 2. In this invention, the reaction chamber openings of the two plasma accelerators have acute-angled cross-sections, with their protruding portions connected end-to-end. A rod-shaped axial electrode or two rod-shaped composite electrodes serve as the anode. A plasma explosive gun is symmetrically placed at the closed end of the plasma accelerator reaction chamber. The explosive gun has a combustible gas supply system and an ignition system, achieving new technical effects. These effects include: filling the explosive gun and the two pulsed plasma accelerators with a combustible mixture; the shock wave generated after detonation is accelerated by current through the plasma-filled electrode gap until the leading edge of the shock wave converges at the edge of the reaction chamber's cross-section. When the shock waves converge, a shock compression region with increased conductivity is formed; current passes through this region to the cathode (cylinder surface), causing plasma energy to accumulate and increasing energy density.

[0025] 3. The present invention involves periodically inputting a combustible gas (propane-butane) into the electrode gap of a pulsed plasma accelerator, thereby changing the resistance of the plasma jet; preferentially depositing compounds during one pulse cycle, and heating the condensed layer and substrate by pulsed current (electron flux) during subsequent plasma pulses.

[0026] 4. In this invention, a current of 4000-6000A along the plasma jet will generate a corresponding pulsed magnetic field. Injecting metal vapor and combustible gas into the pulsed plasma can improve its conductivity, as well as the efficiency of plasma chemical synthesis and the deposition efficiency of the synthesis product on the workpiece surface. When the consumable electrode is connected to the anode, metal vapor will be injected into the plasma from the consumable electrode.

[0027] 5. In this invention, the periodic variation of the plasma jet field resistance leads to fluctuations in the plasma jet velocity. The hardened surface in the cathode state connects with the high-resistance plasma in the plasma reaction chamber, resulting in treatment primarily through the precipitation of metal ions and plasma chemical synthesis products. The consuming electrode, acting as the anode, is intensely heated, providing metal vapor to the pulsed plasma. Subsequently, combustible gas (propane) and oxygen are introduced into the electrode gap in the reaction chamber, increasing the temperature, plasma conductivity, and velocity, thereby connecting the hardened surface of the cylinder to the anode. The surface heating effect is primarily enhanced by pulsed electron jets, whose pulse energy can rapidly and effectively heat the surface and create a high temperature gradient. This high-gradient heating of the local surface causes elastoplastic deformation, refines surface grains, and enhances the surface diffusion process.

[0028] 6. The inner surface modification device of the cylinder of the present invention generates strong acoustic vibrations during use, thereby activating phonons and phonon-electron interactions in the metal workpiece, leading to an increase in the thermal conductivity and temperature gradient of the metal. Ultimately, plasma explosion treatment provides effective elastoplastic deformation and nanocrystal formation. The pulsed magnetic field activates magnons, which act similarly to phonons.

[0029] 7. The inner surface modification device of the present invention can form a high-quality nanocrystalline material layer on the inner surface of a metal cylindrical workpiece. It can be used for hardening hydraulic jack cylinders, engine cylinder liners, compressors, pumps, cannon (gun) barrels, and hand drills, etc. Attached Figure Description

[0030] Figure 1 This is a longitudinal sectional view of the inner surface modification device of the cylinder of the present invention;

[0031] Figure 2 This is a schematic diagram of the hardened inner wall of the cylinder in an embodiment of the present invention;

[0032] Explanation of reference numerals in the attached drawings: 1. Plasma accelerator; 2. Explosion gun; 3. Auxiliary tube; 4. Nozzle; 5. Movable pipeline; 6. Reaction chamber; 7. Insulator; 8. Axial electrode; 9. Current lead; 10. Nozzle; 11. Spark plug; 12. Cylindrical workpiece; 13. Robotic gripper; 14. Open end cut surface. Detailed Implementation

[0033] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] This invention relates to a device for modifying the inner surface of a cylindrical workpiece, which achieves this by simultaneously applying elastic deformation, electromagnetic waves, and electric current to the workpiece surface. The device can use elements such as nitrogen, tungsten, chromium, and carbon to alloy the workpiece surface, thus forming a new material with a nanocrystalline structure on the workpiece surface. It is suitable for various workpieces operating under harsh conditions.

[0036] Meanwhile, in a pulsed plasma atmosphere, a hardened layer can be prepared on the inner surface of the workpiece without pretreatment such as cleaning; thereby improving the electromagnetic energy density and the modification efficiency of the inner surface of the cylinder, introducing alloying elements from the evaporation products of the electrode and the gas mixture into the pulsed plasma jet, and preparing a rapidly quenched layer with uniformly distributed alloying elements on the workpiece surface.

[0037] The present invention provides a device for modifying the inner surface of a cylindrical part, which is applicable to the hardening of the inner surface of cylindrical parts in various technical fields, and can also be used for surface modification of cylinders in mechanical engineering, such as hydraulic jacks.

[0038] See Figure 1 This is a longitudinal sectional view of the inner surface modification device of the cylinder of the present invention;

[0039] A device for modifying the inner surface of a cylindrical workpiece includes two explosive guns 2 and two plasma accelerators 1. Each plasma accelerator 1 contains a reaction chamber 6, one end of which has an open end section 14. The two reaction chambers 6 are connected at the open end section 14. An insulator 7, a rod-shaped electrode 8, and a current lead 9 are installed on the axis of the reaction chamber 6. The insulator 7 is assembled at the ends of the two reaction chambers 6. The axial electrode 8 is built into the reaction chamber 6, and its two ends pass through the insulator 7 and are connected to the current lead 9. This invention has a simple structure and ingenious design. It is mainly used for modifying the inner surface of cylindrical workpieces. The modification effect is ensured by increasing the energy density through focusing the plasma inside the tube.

[0040] Specifically, two explosive guns 2 are respectively mounted at both ends of the two reaction chambers 6; the explosive guns 2 are connected to the nozzle 4, ignition switch, and gas supply system (not shown in the figure) via auxiliary pipe 3 and movable pipe 5. The plasma accelerator 1 is constructed as a reaction chamber 6 with a water jacket, the end of which is cut at an acute angle, and its protruding parts are connected together. The insulator 7, rod-shaped electrode 8, and current lead 9 are fixed on the axis of the reaction chamber, and the current lead is connected to the current converter circuit. The combustible gas mixture enters the nozzle through the nozzle 10 for mixing and is ignited by the spark plug 11.

[0041] The plasma accelerator 1 is moved into the cylindrical workpiece 12 from both ends, as shown in the cross-sectional view. Figure 1 The reaction chamber outlet faces the inner surface of the cylinder, and the reactants inside the reaction chamber flow out to form a plasma jet. The robotic gripper 13 can move and rotate the cylinder workpiece 12 to change the working area.

[0042] In this invention, the reaction chamber openings of the two plasma accelerators have acute-angled cross-sections, with their protruding portions connected end-to-end. A rod-shaped axial electrode or two rod-shaped composite electrodes serve as the anode. A plasma explosive gun is symmetrically placed at the closed end of the plasma accelerator reaction chamber. The explosive gun has a combustible gas supply system and an ignition system, achieving new technical effects. These effects include: filling the explosive gun and the two pulsed plasma accelerators with a combustible mixture; the shock wave generated after detonation is accelerated by current through the plasma-filled electrode gap until the leading edge of the shock wave converges at the edge of the reaction chamber's cross-section. When the shock waves converge, a shock compression region with increased conductivity is formed; current flows through this region to the cathode (cylinder surface), concentrating plasma energy and increasing energy density.

[0043] Furthermore, the two axial electrodes 8 of the reaction chamber 6 have the same geometric dimensions, and the energy input from the detonation gun 2 is symmetrical. The two detonation guns 2 also have the same dimensions, and the energy input from the detonation source is also symmetrical; the end of the plasma accelerator's reaction chamber 6 is cut at an acute angle, and its end protrusions are connected together; the axial electrode 8 is a consumable electrode, and the detonation gun 2 is connected to the closed end of the plasma reaction chamber 6, and it is also connected to the system supplying the combustible gas mixture and the electric spark ignition system; this device has two axial electrodes 8, which are mounted along the axis of the reaction chamber 6 and contain alloying elements.

[0044] The axial electrode 8 is made of a rod coaxial with the axis of the reaction chamber, moves linearly as its end is consumed, and is cooled by airflow.

[0045] The device also includes: the metal alloy element is placed in the form of a regenerable coating on the end of the reaction chamber 6 and the surface of the axial electrode 8, in the closed cavity of the reaction chamber 6 and at the entrance of the explosive gun 2, connected to the tangential channel for introducing the alloy element, the tangential channel being connected to the alloy element suspension preparation system, and the alloy element being an element of Groups III, IV, V, and VI of the periodic table.

[0046] This device is equipped with a capacitive sensing current memory, and the electrodes of the device are switched at a frequency of 1–5 Hz by the conductive products of the explosive combustion. During the current commutation gap, a plasma compound formed by plasma elements and consuming electrode elements condenses on the workpiece surface. During each plasma pulse, this plasma compound is periodically melted and bonded to the substrate by the current. Furthermore, the current is switched through the pulsed plasma in the gap between the end of the consuming electrode and the hardened surface, thus causing periodic changes in the plasma jet velocity and processing time. Accompanying the pulsed connection of the hardened surface, it is connected to the cathode in one pulse and to the anode in the next pulse.

[0047] Each impact of the pulsed plasma on the workpiece surface is accompanied by an electric current impact. The plasma and current rapidly heat the synthesized product and the workpiece surface to above the phase transition temperature, followed by cooling. The heating and cooling of the workpiece surface layer are simultaneously achieved through pulsed current impact, magnetic field impact, acoustic field impact, and vibration. The pulsed current intensity is 5 × 10⁻⁶. 7 A / m 2 The magnetic field strength is 4 × 10 5 A / m, sound pressure range of 140~150dB, vibration frequency of 20000Hz.

[0048] A rod-shaped consumable electrode is installed along the axis of the reaction chamber to supply alloying elements. Axial movement compensation is possible when the electrode tip is consumed, and the electrode is cooled by airflow. The alloying elements enter the reaction chamber through a tangential channel in the explosive gun, which is connected to an alloying element suspension preparation system. The alloying elements are elements from groups III, IV, V, and VI of the periodic table. The alloying elements are placed on the inner surface of the reaction chamber in the form of a regenerable coating. After the coating material is consumed, it can be re-prepared by thermal spraying.

[0049] The inner surface hardening device for the cylindrical workpiece 12 has known features. A cylindrical cathode and anode, made of the working material, are coaxially mounted and isolated by an insulator. The cathode and the end of the reaction chamber of a plasma explosion device (pulsed plasma) are facing each other and tightly connected, placed on the inner surface of the workpiece capable of linear and circular motion. Furthermore, a discharge power supply with adjustable pulse duration is included. This power supply is connected between the reaction chamber wall (cathode) and the consuming electrode (anode). The device also includes a system for supplying a combustible gas mixture and an electric spark ignition system.

[0050] The working principle of this invention is as follows:

[0051] The reaction chambers 6 of the plasma accelerator 1 are moved into the cylindrical workpiece 12 from both sides. The cylindrical workpiece 12 is fixed on the robotic gripper 13 and can rotate 360° and move horizontally. The protruding parts of the cut surfaces 14 at the opening ends of the left and right reaction chambers 6 are connected. An axial electrode 8 (which may not be solid) is placed inside the reaction chamber. The components of the combustible gas mixture, such as propane-butane, oxygen, and air, are fed into the nozzle 4 through the nozzle 10 in a ratio of 1:4:5 and periodically ignited by the spark plug 11 at a frequency of 2Hz. An explosion mode is initiated in the auxiliary tube 3 and enters the electrode gap of the reaction chamber of the plasma accelerator 1 through the explosion gun 2. In the electrode gap, the explosion wave enters the magneto-pneumatic compression mode through electromagnetic energy. The two pulsed plasma streams generated by the left and right reaction chambers collide with each other under the action of mass force and deflect to the inner wall of the cylindrical workpiece 12. The combined flux (composite plasma jet) generated by the collision of the plasma jets is perpendicular to the hardened surface of the cylindrical workpiece 12.

[0052] The plasma jet is focused by mass dynamics and adheres tightly to the surface of the cylindrical workpiece 12. After the operation is complete, the plasma jet is scattered into the gap between the outer surface of the plasma accelerator reaction chamber wall and the cylindrical workpiece 12; an electric current is supplied to the workpiece surface through the plasma jet. The flow direction of the plasma in the cylindrical workpiece 12 and the reaction chamber is indicated by arrows, while the workpiece is moved and rotated by mechanical clamps 13. The entire device is cooled by circulating cooling water within the plasma gun, electrodes, and detonation gun. Focusing of the plasma flow is achieved by guiding the plasma flow along the current lines from the reaction chamber cut to the electrodes due to the mass dynamic interaction between the plasma flow and the total magnetic field formed on the cross-section of the reaction chamber. The magnetic field direction at each cross-section is perpendicular to the cross-section.

[0053] The magnetic fields generated by two adjacent reaction chambers are perpendicular to their axes. The smaller the sectional angle at the opening of the reaction chamber, the more concentrated and sharply focused the magnetic field becomes. At small sectional angles, the secondary cutting from the plasma accelerator reaction chamber will result in a magnetic field shielding effect; therefore, the sectional angle 14 at the opening of reaction chamber 6 is acute. Preferably, the sectional angle of the sectional angle 14 at the opening of reaction chamber 6 is 45°. At this angle, there is no magnetic field shielding, and the distance between the focal point of the magnetic field and the axis of the reaction chamber is greater than the radius of the reaction chamber, allowing the focal point of the magnetic field to be adjusted to the wall to be strengthened. The large sectional angle of the reaction chamber increases the magnetic flux and reduces the efficiency of mass-dynamic interaction. Furthermore, the plasma flow is deflected by the collision of two pure gas dynamic flows, and the optimal sectional angle of 45° ensures minimal loss when the resulting composite flow passes through.

[0054] When the device is running, the closed electrodes provide a suitable plasma flow because there is no random disturbance of the magnetic field as the current flows from the edge of the reaction chamber to the end of the first or second cylindrical electrode.

[0055] This device is mainly used for the modification of the inner surface of cylindrical workpieces. The modification effect is ensured by increasing the energy density through focusing the plasma inside the tube.

[0056] By periodically introducing combustible gas (propane-butane) into the electrode gap of the pulsed plasma accelerator, the resistance of the plasma jet changes accordingly; the compound is preferentially deposited during one pulse cycle, and the condensed layer and substrate are heated by pulsed current (electron flux) during subsequent plasma pulses.

[0057] A current of 4000–6000 A along the plasma jet will generate a corresponding pulsed magnetic field. Injecting metal vapor and combustible gas into the pulsed plasma can improve its conductivity, as well as the efficiency of plasma chemical synthesis and the deposition efficiency of the synthesis products on the workpiece surface. When the consumable electrode is connected to the anode, metal vapor will be injected into the plasma from the consumable electrode.

[0058] The periodic variation in the resistance of the plasma jet field leads to fluctuations in the plasma jet velocity. The hardened surface in the cathode state connects with the high-resistivity plasma in the plasma reaction chamber, resulting in treatment primarily through the precipitation of metal ions and plasma chemical synthesis products. The consuming electrode, acting as the anode, is intensely heated, supplying metal vapor to the pulsed plasma. Subsequently, combustible gas (propane) and oxygen are introduced into the electrode gap in the reaction chamber, increasing the temperature, plasma conductivity, and velocity, thereby connecting the hardened surface of the cylinder to the anode. The surface heating effect is enhanced primarily by pulsed electron jets, whose pulse energy rapidly and effectively heats the surface and creates a high temperature gradient. This high-gradient heating of the localized surface leads to elastoplastic deformation, refinement of surface grains, and enhanced surface diffusion processes.

[0059] The inner surface modification device of the cylinder generates strong acoustic vibrations during use, thereby activating phonons and phonon-electron interactions in the metal workpiece, leading to an increase in the metal's thermal conductivity and temperature gradient. Ultimately, plasma explosion treatment provides effective elastoplastic deformation and nanocrystal formation. The pulsed magnetic field activates magnons, which act similarly to phonons. Specific Implementation

[0061] This device offers the following technical advantages: it uses an inexpensive energy carrier to harden the inner wall of the cylinder. A rapidly hardened wear-resistant layer is prepared through rapid surface heating, plasma thermal diffusion saturation, and rapid cooling. Powder is fed into the reaction chamber of a plasma accelerator, where it is deflected onto the cylinder wall due to the collisions with the plasma stream.

[0062] This device can significantly simplify the manufacturing process of parts. For example, after machining, the barrel of a hand-held drill needs to undergo chemical heat treatment, that is, carburizing the inner wall, followed by grinding and honing of the inner wall.

[0063] When using this device, honing can be performed after machining, followed by hardening treatment. A surface with a depth of 150 μm and a hardness of 10000 mN / m can be prepared on the inner wall surface. 2 Rapidly hardening layers, such as Figure 2 As shown.

[0064] (Table 1) Hardening quality test verification of 40X steel bushing with an inner diameter of 50mm.

[0065] The hollow mandrel is mounted on the robotic gripper and has rotary and linear motion drive. Five bushings are fixed inside the hollow mandrel, each bushing being 30mm in length.

[0066] The reaction chamber is pushed into the bushing hole simultaneously from both sides along the axis of the bushing.

[0067] The hardening of the inner wall of the cylindrical workpiece is carried out with a pulse frequency of 2Hz, and the current capacitor has a capacitance of 1200μF and a voltage of 2.5kV.

[0068] Comparative analysis of the hardening results of the inner wall of the bushing (see Table 2) shows that hardening is performed on the closed electrode and the protruding part of the reaction chamber, and the hardening effect depends on the tangential angle of the opening end of the reaction chamber.

[0069] The optimal facet angle is 45°, which ensures a sufficiently large hardened area, hardened thickness, and microhardness (resulting in the best overall hardening effect). As the facet angle decreases, the size of the heat-affected zone increases, but the thickness of the hardened layer decreases. Increasing the facet angle narrows the gap in the plasma flow and increases the energy density, thus damaging the surface treated with a 75° facet angle. In this case, damage to the edge of the reaction chamber facet can be observed.

[0070] Hardening experiments conducted at both ends of the open electrode and reaction chamber showed that the hardening efficiency decreased sharply when there was a gap between the electrodes (see Table 2). This is due to the electromagnetic field distortion at the edge of the electrode gap caused by the "turbulence" of the plasma flow.

[0071] The optimal process provides good performance, with 240mm at five overlaps and a pulse frequency of 2Hz. 2 / s productivity. In this case, when the thickness of the hardened layer is 100-120 μm, the geometric parameters remain unchanged; when the thickness of the hardened layer is 140 μm, the surface melts.

[0072] Comparative analysis of hardening efficiency shows that, at lower productivity, the hardened layer thickness of a 100mm long bushing is 5–40μm.

[0073] Table 1. Chemical composition (wt%) of 40X steel

[0074]

[0075] Table 2. Test Results

[0076]

[0077] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention; therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0078] Although this document uses numerous reference numerals from the figures, such as plasma accelerator 1, explosion gun 2, auxiliary tube 3, nozzle 4, movable pipeline 5, reaction chamber 6, insulator 7, axial electrode 8, current lead 9, nozzle 10, spark plug 11, cylindrical workpiece 12, robotic gripper 13, and open end section 14, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention.

Claims

1. A device for modifying the inner surface of a cylinder, characterized in that: It includes two explosive guns (2) and two plasma accelerators (1); each of the two plasma accelerators (1) has a reaction chamber (6), and one end of the reaction chamber (6) has an open end section (14); the two reaction chambers (6) are connected at the open end section (14); the two explosive guns (2) are respectively mounted at both ends of the two reaction chambers (6); wherein, the explosive guns (2) are connected to the nozzle (4) through the auxiliary pipe (3) and the movable pipe (5); an insulator (7), an axial electrode (8) and a current lead (9) are installed on the axis of the reaction chamber (6); the insulator (7) is mounted at the end of the two reaction chambers (6); the axial electrode (8) is built into the reaction chamber (6) and its two ends pass through the insulator (7) and are connected to the current lead (9); the plasma is pulsed plasma; the sectional angle of the open end section (14) of the reaction chamber (6) is 45°.

2. The device for modifying the inner surface of a cylinder according to claim 1, characterized in that: The nozzle (4) is aligned with the opening end of the explosive gun (2), and the nozzle (4) introduces one or more alloying elements or compounds into the explosive gun (2).

3. The device for modifying the inner surface of a cylinder according to claim 1, characterized in that: The explosive gun (2) has a single gas supply source and detonation source. The two explosive guns (2) are placed symmetrically and closely cooperate with the closed part of the reaction chamber (6).

4. The device for modifying the inner surface of a cylinder according to claim 1, characterized in that: The axial electrode (8) is coaxial with the axis of the reaction chamber (6), and moves axially to compensate as its end is consumed, and is cooled by airflow.

5. The device for modifying the inner surface of a cylinder according to claim 1, characterized in that: The axial electrode (8) is mounted along the axis of the reaction chamber (6) and its surface contains alloying elements.

6. The device for modifying the inner surface of a cylinder according to claim 2 or 5, characterized in that: The alloying elements are elements from Groups III, IV, V, and VI of the periodic table; the alloying elements are placed in the form of a regenerable coating on the end of the reaction chamber (6) and the surface of the axial electrode (8).

7. The device for modifying the inner surface of a cylinder according to claim 4, characterized in that: Two axial electrodes (8) are provided, and the axial electrodes (8) are installed along the axis of the reaction chamber.

8. The device for modifying the inner surface of a cylinder according to claim 1, characterized in that: It also includes a robotic gripper (13) for rotating and moving the cylindrical workpiece (12) 360° horizontally, the robotic gripper (13) being located at the upper end of the cylindrical workpiece (12).

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