A method for spraying zinc on the surface of a zinc-sprayed porous flat tube

Abstract

The present invention relates to a method for spraying zinc on the surface of a porous flat tube. A spraying robot is used to perform the zinc spraying operation on the porous flat tube, and a high-frequency self-vibration mechanism is used to clamp the porous flat tube and apply high-frequency vibration to the porous flat tube. The high-frequency self-vibration mechanism includes a chuck, a square plate, two excitation mechanisms for applying excitation to the square plate, a turntable for rotating the square plate and the excitation mechanisms, a driving mechanism for driving the turntable to rotate, and a movable support mechanism arranged between the square plate and the turntable. The excitation mechanism includes a vibrator and a damper. The present invention improves the zinc spraying quality by optimizing the zinc spraying process for the porous flat tube. The six-axis robot is used to control the arc spraying machine, with higher automation degree, flexible and variable zinc spraying angles, and no spraying dead angles. The high-frequency self-vibration mechanism applies high-frequency vibration to the clamped porous flat tube, significantly improving the compactness of the zinc spraying layer, with better salt spray resistance performance, stronger corrosion resistance, and higher spraying quality of the zinc spraying layer.

Description

Technical Field

[0001] The present invention relates to a method for spraying zinc on the surface of a zinc-sprayed porous flat tube, belonging to the technical field of zinc spraying for porous flat tubes. Background Art

[0002] A porous flat tube is a multi-channel aluminum tube (referred to as "porous flat tube") made of refined aluminum rods, through hot extrusion and surface zinc spraying for anti-corrosion treatment.

[0003] For example: Using continuous extrusion technology, an aluminum flat tube is produced from a round rod material through a continuous extrusion device, and zinc is sprayed online at the same time.

[0004] The formation process of an arc spraying coating is divided into three stages: droplet formation, droplet atomization, and particle deposition. During the droplet formation process, the droplets are accelerated and atomized into extremely fine particles by the atomizing air flow and leave the spray gun to form a jet. The atomization effect directly affects the quality of the coating. Particle deposition: The droplets formed in the arc zone, after atomization and accelerated flight, will impact the substrate surface at a very high speed. At this time, the kinetic energy of the droplets will be converted into heat energy and deformation energy. When the droplets impact the substrate, the cooled substrate will quickly transfer its heat, and the droplets will be cooled and solidified instantly during deformation, forming disk-shaped thin sheets, that is, flat particles. And the process of droplet impact, deformation, cooling, and solidification is called the flattening process, and its time is extremely short. Next, the following droplets are continuously flattened and stacked on it to form a thermal spray coating.

[0005] After the thermal spray coating is formed, its structure includes three parts: flat particles, an oxide layer, and voids. Flat particles are formed by the high-speed impact of atomized droplets on the substrate and deformation and solidification. Due to rapid solidification, the hardness of flat particles is significantly higher than that in the casting state. Pores are an important structural feature of the thermal spray coating, and the size of the porosity will directly affect the bonding strength, corrosion resistance, oxidation resistance, and wear resistance of the coating.

[0006] However, for current porous flat tubes, especially micro-channel aluminum tubes, the requirements for the zinc spraying layer are high. When the existing thermal spraying equipment sprays, the oxidation of zinc particles is serious and the porosity is relatively high, resulting in the salt spray test often not meeting the design requirements. Multiple sprays are required and the spraying environment needs to be strictly controlled, and the qualified rate of products is very low.

[0007] Based on this, the present invention is proposed. Summary of the Invention

[0008] Aiming at the deficiencies existing in the prior art, the present invention provides a method for spraying zinc on the surface of a zinc-sprayed porous flat tube. The specific technical solution is as follows:

[0009] A method for spraying zinc on the surface of a zinc-sprayed porous flat tube uses a spraying robot to perform zinc spraying operations on the porous flat tube, and uses a high-frequency self-vibration mechanism to clamp the porous flat tube and apply high-frequency vibration to the porous flat tube;

[0010] The spraying robot is a combination of a six-axis robot and an arc spraying machine. The six-axis robot drives the arc spraying machine to perform zinc spraying operations. The arc current of the arc spraying machine is 85 A, the arc voltage is 27 V, the wire feeding speed is 68 - 72 mm / s, the spraying distance is 150 mm, and the air pressure of the compressed air passed through is 5.5 MPa.

[0011] For further improvement, the high-frequency self-vibration mechanism includes a chuck, a square plate located below the chuck, two groups of excitation mechanisms for applying excitation to the square plate, a turntable for rotating the square plate and the excitation mechanisms, a driving mechanism for driving the turntable to rotate, and a movable support mechanism arranged between the square plate and the turntable. The bottom of the chuck is fixedly connected to the center of the square plate. One group of excitation mechanisms is arranged along the length direction of the square plate, and the other group of excitation mechanisms is arranged along the width direction of the square plate. The excitation mechanism includes a vibrator and a damper. The vibrator is located on one side of the square plate, and the damper is located on the other side of the square plate. The base of the vibrator is fixedly connected to the edge of the turntable, and the base of the damper is fixedly connected to the edge of the turntable.

[0012] For further improvement, the movable support mechanism includes a central movable column and four auxiliary columns symmetrically distributed around the central movable column. A hemispherical protrusion one is arranged at the upper end of the central movable column, and a hemispherical first groove adapted to the protrusion one is arranged at the center of the bottom of the square plate; a spherical segment-shaped protrusion two is arranged at the upper end of the auxiliary column, and a spherical segment-shaped second groove is arranged at the bottom of the square plate. The radius corresponding to the second groove is larger than the radius corresponding to the protrusion two.

[0013] For further improvement, a push plate is installed at the excitation end of the vibrator, and the push plate abuts against the outside of the square plate.

[0014] For further improvement, the driving mechanism includes an anti-vibration rotating shaft installed at the center of the bottom of the turntable, a first bevel gear installed at the lower end of the anti-vibration rotating shaft, a second bevel gear meshing with the first bevel gear, and a motor for driving the second bevel gear to rotate.

[0015] For further improvement, the anti-vibration rotating shaft successively includes a circular tube, a reduced-diameter part, and a square shaft from top to bottom. The upper end of the circular tube is fixedly connected to the center of the bottom of the turntable. The outer periphery of the reduced-diameter part is a single-sheet hyperboloid structure. The reduced-diameter part is integrally connected with the circular tube, and the reduced-diameter part is integrally connected with the upper end of the square shaft. The lower end of the square shaft is fixedly connected to the center of the first bevel gear.

[0016] For further improvement, a bearing and a fixing plate are arranged below the turntable. The bearing is sleeved outside the circular tube, the upper end of the circular tube is fixedly connected to the inner ring of the bearing, and the bearing is embedded in the middle of the fixing plate.

[0017] For further improvement, the difference between the radius corresponding to the second groove and the radius corresponding to the second protrusion is x, where 3 mm ≤ x ≤ 6 mm.

[0018] For further improvement, the method for spraying zinc on the surface of the zinc-sprayed porous flat tube includes the following steps:

[0019] Step S1: Clean the surface of the porous flat tube 40, and then insert it into the chuck 70.

[0020] Step S2: Start the turntable 10, and the rotation speed of the turntable 10 is 10 - 12 r / min. The excitation mechanism applies excitation to the X-direction and Y-direction of the square plate 30. The X-direction of the square plate 30 is the length direction of the square plate 30, and the Y-direction of the square plate 30 is the width direction of the square plate 30. The frequency of the excitation mechanism applying excitation to the X-direction of the square plate 30 is 3200 - 3300 Hz, and the frequency of the excitation mechanism applying excitation to the Y-direction of the square plate 30 is 95 - 105 Hz.

[0021] Step S3: Use a spraying robot to perform zinc spraying operation on the porous flat tube 40.

[0022] For further improvement, the maximum amplitude of the excitation mechanism applying excitation to the X-direction of the square plate is 8 mm, and the maximum amplitude of the excitation mechanism applying excitation to the Y-direction of the square plate is 1 mm.

[0023] Advantages of the present invention:

[0024] 1. By optimizing the zinc spraying process for the porous flat tube, the zinc spraying quality is improved.

[0025] 2. The six-axis robot is used to control the arc spraying machine, with higher automation, flexible and variable spraying angles, and no spraying dead angles.

[0026] 3. The high-frequency self-vibration mechanism is used to apply high-frequency vibration to the clamped porous flat tube, significantly improving the compactness of the zinc spraying layer, with better salt spray resistance, stronger corrosion resistance, and higher spraying quality of the zinc spraying layer; the spraying qualification rate of each batch exceeds 98%, and the defective rate of the product is low. Description of the Drawings

[0027] Figure 1 It is a schematic structural diagram of the high-frequency self-vibration mechanism described in the present invention;

[0028] Figure 2 It is a schematic connection diagram of the movable support mechanism and the square plate described in the present invention;

[0029] Figure 3 It is a schematic structural diagram of the square plate described in the present invention. Detailed Embodiments

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] In the description of the present invention, it should be noted that unless otherwise specified, the meaning of "a plurality of" is two or more; the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0032] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations. Embodiment 1

[0033] As Figure 1 shown, for the method of spraying zinc on the surface of the zinc-sprayed porous flat tube, a spraying robot is used to perform zinc spraying operations on the porous flat tube 40, and a high-frequency self-vibration mechanism is used to clamp the porous flat tube 40 and apply high-frequency vibration to the porous flat tube 40;

[0034] The spraying robot is a combination of a six-axis robot and an arc spraying machine. The six-axis robot drives the arc spraying machine to perform zinc spraying operations. The arc current of the arc spraying machine is 85 A, the arc voltage is 27 V, the wire feeding speed is 68-72 mm / s, the spraying distance is 150 mm, and the air pressure of the compressed air passed is 5.5 MPa.

[0035] Parameters such as the arc current, arc voltage, wire feeding speed, spraying distance, and air pressure of the compressed air passed through the arc spraying machine will all affect the spraying quality. Among them, the arc current affects the bonding strength of the sprayed zinc layer. When the arc current is too low, the arc power is insufficient, and the spraying particles cannot be fully melted, resulting in low bonding strength. When the arc current is too large, the melting amount of zinc further increases, and the liquid zinc droplets become larger. Due to the constant compressed air pressure, the atomization effect is poor, the particle size of the sprayed liquid zinc becomes larger, and the bonding with the workpiece surface is not good, and sputtering occurs. Moreover, it will also cause the temperature of the molten metal to be too high and the oxidation phenomenon to be serious.

[0036] The influence of the spraying voltage on the bonding strength of the sprayed zinc layer is relatively small. When the voltage is too low, it is not easy to strike an arc, and the arc temperature after striking an arc is also low. The spraying material is not completely melted, and the spraying process becomes discontinuous.

[0037] The smaller the spraying distance, the worse the atomization of the zinc droplets, the more serious the sputtering phenomenon, and the lower the bonding strength. When the spraying distance is relatively large, although the atomization effect of the zinc droplets is good, due to the long flying distance, the temperature of the liquid zinc particles is relatively low, their fluidity becomes poor, and their movement speed also decreases. Therefore, after contacting the surface of the specimen, the contact tightness is poor, and pores are easily formed between the particles, reducing the bonding strength.

[0038] In this example, the thickness of the sprayed zinc layer is controlled at 0.2 mm. Based on the above requirements, various parameters of the arc spraying machine are strictly controlled to make the quality of the sprayed zinc layer reach the best. Example 2

[0039] In Example 1, as Figure 1 shown, the high-frequency self-vibration mechanism includes a chuck 70, a square plate 30 located below the chuck 70, two sets of excitation mechanisms for applying excitation to the square plate 30, a turntable 10 for rotating the square plate 30 and the excitation mechanisms, a driving mechanism for driving the turntable 10 to rotate, and a movable support mechanism arranged between the square plate 30 and the turntable 10. The bottom of the chuck 70 is fixedly connected to the center of the square plate 30. One set of excitation mechanisms is arranged along the length direction of the square plate 30, and the other set of excitation mechanisms is arranged along the width direction of the square plate 30. The excitation mechanism includes a vibrator 50 and a damper 52. The vibrator 50 is located on one side of the square plate 30, and the damper 52 is located on the other side of the square plate 30. The base of the vibrator 50 is fixedly connected to the edge of the turntable 10, and the base of the damper 52 is fixedly connected to the edge of the turntable 10. Example 3

[0040] In Example 2, as Figures 1 - 3As shown in the figure, the movable support mechanism includes a central movable column 31 and four auxiliary columns 32 symmetrically distributed around the central movable column 31. A hemispherical protrusion 311 is provided at the upper end of the central movable column 31, and a hemispherical first groove 301 adapted to the protrusion 311 is provided at the center of the bottom of the square plate 30. A spherical segment-shaped protrusion 321 is provided at the upper end of the auxiliary column 32, and a spherical segment-shaped second groove 302 is provided at the bottom of the square plate 30. The radius corresponding to the second groove 302 is greater than the radius corresponding to the protrusion 321.

[0041] When the excitation mechanism applies excitation to the square plate 30, the length and width directions of the square plate 30 will vibrate due to low-frequency and high-frequency knocking. Therefore, it is necessary to use the central movable column 31 (preferably a copper column with excellent elasticity) to position the square plate 30. The hemispherical protrusion 311 cooperates with the hemispherical first groove 301, which does not affect small-amplitude displacement while positioning. In addition, since the spherical segment-shaped protrusion 321 cooperates with the spherical segment-shaped second groove 302, it does not affect small-amplitude displacement while supporting, especially when the radius corresponding to the second groove 302 is greater than the radius corresponding to the protrusion 321.

[0042] In particular, the difference between the radius corresponding to the second groove 302 and the radius corresponding to the protrusion 321 is x, and 3mm ≤ x ≤ 6mm. If the value of x is too large, it is very easy to cause large vibration of the square plate 30 in the Z-axis direction, resulting in relatively serious damage to the damper 52. If the value of x is too small, it is very easy to cause serious misalignment when the amplitude becomes larger. Embodiment 4

[0043] In Embodiment 3, a push plate 51 is installed at the excitation end of the vibrator 50, and the push plate 51 abuts against the outside of the square plate 30.

[0044] If the excitation end of the vibrator 50 is directly fixedly connected to the outside of the square plate 30, the load on the vibrator 50 is very large, and it is very easy to cause damage to the vibrator 50 due to overload. Embodiment 5

[0045] In Embodiment 3, the drive mechanism includes an anti-vibration rotating shaft installed at the center of the bottom of the turntable 10, a first bevel gear 64 installed at the lower end of the anti-vibration rotating shaft, a second bevel gear 65 meshing with the first bevel gear 64, and a motor 66 for driving the second bevel gear 65 to rotate.

[0046] Among them, the anti-vibration rotating shaft includes a circular tube 61, a reduced-diameter part 62, and a square shaft 63 from top to bottom. The upper end of the circular tube 61 is fixedly connected to the center of the bottom of the turntable 10. The outer periphery of the reduced-diameter part 62 is a single-sheet hyperboloid structure. The reduced-diameter part 62 is integrally connected to the circular tube 61. The reduced-diameter part 62 is integrally connected to the upper end of the square shaft 63. The lower end of the square shaft 63 is fixedly connected to the center of the first bevel gear 64.

[0047] In this embodiment, bevel gear transmission is adopted, which can effectively reduce the damage to the gears caused by vibration.

[0048] In addition, it should be noted that: a bearing 12 and a fixing plate 11 are provided below the turntable 10. The bearing 12 is sleeved outside the circular tube 61. The upper end of the circular tube 61 is fixedly connected to the inner ring of the bearing 12. The bearing 12 is embedded in the middle of the fixing plate 11. The fixing plate 11 is connected to other machine frames to play a fixing role.

[0049] When the motor 66 is started, the anti-vibration rotating shaft and the turntable 10 are driven to rotate through the first bevel gear 64 and the second bevel gear 65. If the rotation speed of the turntable 10 is too high, it will significantly affect the bonding strength of the sprayed zinc layer; if it is too low, it will affect the thickness uniformity of the sprayed zinc layer. Therefore, it is necessary to strictly control the rotation speed of the turntable 10 to be 10 - 12 r / min. For example, when the rotation speed of the turntable 10 is 5 r / min, there will be a sprayed zinc layer with an area exceeding 21%, and its thickness error exceeds ±0.1 mm. When the rotation speed of the turntable 10 is 10 - 12 r / min, more than 99% of the area of the sprayed zinc layer has a thickness error not exceeding ±0.01 mm.

[0050] Due to the excitation and vibration at the square plate 30, if the anti-vibration rotating shaft is a solid shaft throughout, the transmitted vibration will cause a significant impact on the first bevel gear 64 (by installing a displacement sensor at the first bevel gear 64 to measure the maximum amplitude, and the maximum amplitude is 1.8 mm). If the anti-vibration rotating shaft is a hollow shaft throughout, it will also cause a great impact (the maximum amplitude is 1.2 mm). For the anti-vibration rotating shaft, first, through the closed structure inside the circular tube 61, it is initially buffered. After passing through the special structure of the reduced-diameter part 62, it can further elastically deform and buffer. The final square shaft 63 is mainly to improve the anti-torsion property. Finally, the impact on the first bevel gear 64 caused by the anti-vibration rotating shaft is relatively small (the maximum amplitude is 0.7 mm). Such a level of impact has a relatively small impact on the bevel gear. Example 6

[0051] In Example 5, the method for spraying zinc on the surface of the zinc-sprayed porous flat tube includes the following steps:

[0052] Step S1: Clean the surface of the porous flat tube 40, and then insert it into the chuck 70;

[0053] Step S2: Start the turntable 10 with a rotation speed of 10 - 12 r / min. The excitation mechanism applies excitation forces to the X - direction and Y - direction of the square plate 30. The X - direction of the square plate 30 is the length direction of the square plate 30, and the Y - direction of the square plate 30 is the width direction of the square plate 30. The excitation frequency applied by the excitation mechanism to the X - direction of the square plate 30 is 3200 - 3300 Hz, and the excitation frequency applied by the excitation mechanism to the Y - direction of the square plate 30 is 95 - 105 Hz. The maximum amplitude of the excitation force applied by the excitation mechanism to the X - direction of the square plate 30 is 8 mm, and the maximum amplitude of the excitation force applied by the excitation mechanism to the Y - direction of the square plate 30 is 1 mm.

[0054] Step S3: Use a spraying robot to perform zinc spraying on the porous flat tube 40. The working parameters of the arc spraying machine are as follows:

[0055] The arc current of the arc spraying machine is 85 A, the arc voltage is 27 V, the wire feeding speed is 68 - 72 mm / s, the spraying distance is 150 mm, and the air pressure of the compressed air passed is 5.5 MPa.

[0056] The six - axis robot has high flexibility and drives the arc spraying machine to perform zinc spraying on the porous flat tube 40.

[0057] Use the "Metallographic Method" to measure the porosity of the zinc - sprayed layer.

[0058] Because of the special high - frequency vibration process, during the particle deposition stage of spraying, the high - frequency vibration of the porous flat tube itself and the molten droplets flying at high speed collide with each other, generating more momentum. The flattening process of the impact, deformation, cooling, and solidification of the molten droplets is accelerated. In addition, high - frequency vibration can also force the separation of particles with poor adhesion, and a large number of particles such as oxygen impurities can be removed. Finally, the density of the zinc - sprayed layer is very high. Especially the middle layer is almost a dense layer without voids. In addition, the surface porosity will also be significantly reduced, directly affecting the porosity. The higher the density of the zinc - sprayed layer, the longer the salt spray test time.

[0059] In this embodiment, the thickness of the zinc - sprayed layer is 0.2 mm, its porosity is 5.89%, and the surface is almost void - free. The salt spray test time exceeds 720 hours. The bonding strength between the zinc - sprayed layer and the porous flat tube is 5.91 MPa.

[0060] Comparative Example 1

[0061] The difference between this example and Example 6 is only that during spraying, the excitation mechanism does not work, and the others are the same. Finally, the obtained zinc - sprayed layer has a thickness controlled at 0.2 mm, its porosity is 17.97%, the salt spray test time is 120 hours, and the bonding strength between the zinc - sprayed layer and the porous flat tube is 4.13 MPa.

[0062] Comparative Example 2

[0063] The difference between this example and Example 6 is only that during spraying, when the excitation mechanism is working, the maximum amplitude of the excitation applied by the excitation mechanism to the X-direction of the square plate 30 is 1 mm, and the maximum amplitude of the excitation applied by the excitation mechanism to the Y-direction of the square plate 30 is 8 mm; other conditions are the same. Finally, the obtained zinc spraying layer has a thickness controlled at 0.2 mm, a porosity of 20.11%, a salt spray test time of 135 hours, and the bonding strength between the zinc spraying layer and the porous flat tube is 4.72 MPa.

[0064] Comparative Example 3

[0065] The difference between this example and Example 6 is only that during spraying, when the excitation mechanism is working, the maximum amplitude of the excitation applied by the excitation mechanism to the X-direction of the square plate 30 is 20 mm, and the maximum amplitude of the excitation applied by the excitation mechanism to the Y-direction of the square plate 30 is 20 mm; other conditions are the same. Finally, the obtained zinc spraying layer has a thickness controlled at 0.2 mm, a porosity of 27.02%, a salt spray test time of 96 hours, and the bonding strength between the zinc spraying layer and the porous flat tube is 5.09 MPa.

[0066] Comparative Example 4

[0067] The difference between this example and Example 6 is only that during spraying, when the excitation mechanism is working, the maximum amplitude of the excitation applied by the excitation mechanism to the X-direction of the square plate 30 is 1 mm, and the maximum amplitude of the excitation applied by the excitation mechanism to the Y-direction of the square plate 30 is 1 mm; other conditions are the same. Finally, the obtained zinc spraying layer has a thickness controlled at 0.2 mm, a porosity of 18.13%, a salt spray test time of 135 hours, and the bonding strength between the zinc spraying layer and the porous flat tube is 4.31 MPa.

[0068] Comparative Example 5

[0069] The difference between this example and Example 6 is only that during spraying, when the excitation mechanism is working, the excitation frequency applied by the excitation mechanism to the X-direction of the square plate 30 is 95 - 105 Hz, and the excitation frequency applied by the excitation mechanism to the Y-direction of the square plate 30 is 3200 - 3300 Hz; other conditions are the same. Finally, the obtained zinc spraying layer has a thickness controlled at 0.2 mm, a porosity of 8.21%, a salt spray test time of 360 hours, and the bonding strength between the zinc spraying layer and the porous flat tube is 5.38 MPa.

[0070] Comparative Example 6

[0071] The difference between this example and Example 6 is only that during spraying, when the excitation mechanism is working, the frequency of the excitation applied by the excitation mechanism to the X-direction of the square plate 30 is 95 - 105 Hz, and the frequency of the excitation applied by the excitation mechanism to the Y-direction of the square plate 30 is 95 - 105 Hz; other conditions are the same. Finally, the obtained zinc spraying layer has a thickness controlled at 0.2 mm, a porosity of 9.17%, a salt spray test time of 250 hours, and a bonding strength between the zinc spraying layer and the porous flat tube of 5.51 MPa.

[0072] Comparative Example 7

[0073] The difference between this example and Example 6 is only that during spraying, when the excitation mechanism is working, the frequency of the excitation applied by the excitation mechanism to the X-direction of the square plate 30 is 3200 - 3300 Hz, and the frequency of the excitation applied by the excitation mechanism to the Y-direction of the square plate 30 is 3200 - 3300 Hz; other conditions are the same. Finally, the obtained zinc spraying layer has a thickness controlled at 0.2 mm, a porosity of 8.83%, a salt spray test time of 390 hours, and a bonding strength between the zinc spraying layer and the porous flat tube of 5.57 MPa. Additionally, both the X-direction and Y-direction are high-frequency vibrations, and continuous operation cannot exceed 20 minutes, otherwise the equipment burden is large and the square plate 30 is prone to overheating.

[0074] Comparative Example 8

[0075] The difference between this example and Example 6 is only that during spraying, when the excitation mechanism is working, the frequency of the excitation applied by the excitation mechanism to the X-direction of the square plate 30 is 5000 - 5200 Hz, and the frequency of the excitation applied by the excitation mechanism to the Y-direction of the square plate 30 is 95 - 105 Hz; other conditions are the same. Finally, the obtained zinc spraying layer has a thickness controlled at 0.2 mm, a porosity of 8.19%, a salt spray test time of 210 hours, and a bonding strength between the zinc spraying layer and the porous flat tube of 5.29 MPa.

[0076] Comparative Example 9

[0077] The difference between this example and Example 6 is only that during spraying, when the excitation mechanism is working, the frequency of the excitation applied by the excitation mechanism to the X-direction of the square plate 30 is 3200 - 3300 Hz, and the frequency of the excitation applied by the excitation mechanism to the Y-direction of the square plate 30 is 10 - 15 Hz; other conditions are the same. Finally, the obtained zinc spraying layer has a thickness controlled at 0.2 mm, a porosity of 9.55%, a salt spray test time of 190 hours, and a bonding strength between the zinc spraying layer and the porous flat tube of 5.37 MPa.

[0078] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for spraying zinc on the surface of a zinc-sprayed porous flat tube, characterized in that: A spraying robot is used to spray zinc on the porous flat tube (40), and a high-frequency self-vibration mechanism is used to clamp the porous flat tube (40) and apply high-frequency vibration to the porous flat tube (40). The spraying robot is a combination of a six-axis robot and an arc spraying machine. The six-axis robot drives the arc spraying machine to perform the zinc spraying operation. The arc current of the arc spraying machine is 85 A, the arc voltage is 27 V, the wire feeding speed is 68 - 72 mm / s, the spraying distance is 150 mm, and the air pressure of the compressed air passed is 5.5 MPa. The high-frequency self-vibration mechanism includes a chuck (70), a square plate (30) located below the chuck (70), two groups of excitation mechanisms for applying excitation to the square plate (30), a turntable (10) for rotating the square plate (30) and the excitation mechanisms, a driving mechanism for driving the turntable (10) to rotate, and a movable support mechanism arranged between the square plate (30) and the turntable (10). The bottom of the chuck (70) is fixedly connected to the center of the square plate (30). One group of excitation mechanisms is arranged along the length direction of the square plate (30), and the other group of excitation mechanisms is arranged along the width direction of the square plate (30). The excitation mechanism includes a vibrator (50) and a damper (52). The vibrator (50) is located on one side of the square plate (30), and the damper (52) is located on the other side of the square plate (30). The base of the vibrator (50) is fixedly connected to the edge of the turntable (10), and the base of the damper (52) is fixedly connected to the edge of the turntable (10). The driving mechanism includes an anti-vibration rotating shaft installed at the center of the bottom of the turntable (10), a first bevel gear (64) installed at the lower end of the anti-vibration rotating shaft, a second bevel gear (65) meshing with the first bevel gear (64), and a motor (66) for driving the second bevel gear (65) to rotate. The anti-vibration rotating shaft successively includes a circular tube (61), a reduced-diameter part (62), and a square shaft (63) from top to bottom. The upper end of the circular tube (61) is fixedly connected to the center of the bottom of the turntable (10). The outer circumference of the reduced-diameter part (62) is a single-sheet hyperboloid structure. The reduced-diameter part (62) is integrally connected to the circular tube (61), and the reduced-diameter part (62) is integrally connected to the upper end of the square shaft (63). The lower end of the square shaft (63) is fixedly connected to the center of the first bevel gear (64).

2. A method for spraying zinc on the surface of a zinc-sprayed porous flat tube according to claim 1, characterized in that: The movable support mechanism includes a central movable column (31) and four auxiliary columns (32) symmetrically distributed around the central movable column (31). A hemispherical protrusion one (311) is arranged at the upper end of the central movable column (31), and a hemispherical first groove (301) adapted to the protrusion one (311) is arranged at the center of the bottom of the square plate (30). A spherical segment-shaped protrusion two (321) is arranged at the upper end of the auxiliary column (32), and a spherical segment-shaped second groove (302) is arranged at the bottom of the square plate (30). The radius corresponding to the second groove (302) is larger than the radius corresponding to the protrusion two (321).

3. A method for spraying zinc on the surface of a zinc-sprayed porous flat tube according to claim 1, characterized in that: A push plate (51) is installed at the excitation end of the vibrator (50), and the push plate (51) abuts against the outside of the square plate (30).

4. A method for spraying zinc on the surface of a zinc-sprayed porous flat tube according to claim 1, characterized in that: A bearing (12) and a fixing plate (11) are arranged below the turntable (10). The bearing (12) is sleeved outside a round tube (61). The upper end of the round tube (61) is fixedly connected to the inner ring of the bearing (12). The bearing (12) is embedded and installed in the middle of the fixing plate (11).

5. A method for spraying zinc on the surface of a zinc-sprayed porous flat tube according to claim 2, characterized in that: The difference between the radius corresponding to the second groove (302) and the radius corresponding to the second protrusion (321) is x, where 3 mm ≤ x ≤ 6 mm.

6. A method for spraying zinc on the surface of a zinc-sprayed porous flat tube according to claim 1, characterized in that, It includes the following steps: Step S1: Clean the surface of the porous flat tube (40), and then insert it into the chuck (70); Step S2: Start the turntable (10). The rotation speed of the turntable (10) is 10 - 12 r / min. The excitation mechanism applies excitation to the X direction and Y direction of the square plate (30). The X direction of the square plate (30) is the length direction of the square plate (30), and the Y direction of the square plate (30) is the width direction of the square plate (30). The frequency of the excitation mechanism applying excitation to the X direction of the square plate (30) is 3200 - 3300 Hz, and the frequency of the excitation mechanism applying excitation to the Y direction of the square plate (30) is 95 - 105 Hz; Step S3: Use a spraying robot to perform zinc spraying operation on the porous flat tube (40).

7. A method for spraying zinc on the surface of a zinc-sprayed porous flat tube according to claim 6, characterized in that: The maximum amplitude of the excitation mechanism applying excitation to the X direction of the square plate (30) is 8 mm, and the maximum amplitude of the excitation mechanism applying excitation to the Y direction of the square plate (30) is 1 mm.

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