A control method of a laser cladding gun head

Abstract

The present application relates to the technical field of laser cladding, and particularly relates to a control method of a laser cladding gun head, comprising the following steps: in the process of axial movement of the laser cladding gun head along a screw rod, the laser cladding gun head moves radially along the screw rod to compensate for the change amount of the outer diameter of the screw ridge; and the lens moves in the vertical direction to adjust the spot area of the laser formed on the screw ridge to compensate for the change amount of the screw ridge width. The method further divides the screw ridge into a first zone and a second zone on the basis of the conical structure of the processed screw rod, and the screw ridge width of the two zones gradually decreases along the axial direction. The control method can compensate for the changes of the outer diameter and the width of the screw ridge in real time by the radial movement of the laser cladding gun head and the vertical adjustment of the lens while the screw rod rotates and the gun head moves axially, effectively avoids uneven cladding or defects caused by the changes of geometric dimensions, realizes the formation of a uniform cladding layer on the surface of the screw rod, and further improves the wear resistance and service life of the screw rod.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser cladding, in particular to a control method of a laser cladding gun head. BACKGROUND

[0002] As an important equipment for plastic product forming processing, the extruder plays a core role in the plastic particle melting, mixing and forming process. Among them, the screw is the most critical part of the extruder, and its performance directly determines the efficiency of plastic melting, the uniformity of plasticizing, and the quality and yield of the final product.

[0003] The existing extruder screw is usually composed of a shaft and a screw rib arranged on the outer wall of the shaft. When the screw rotates at high speed in the barrel, on the one hand, it needs to push the plastic particles to move forward along the axial direction, and on the other hand, it relies on the screw rib to exert shear and stirring action on the material to realize plasticizing. In the processing process, the screw works in a complex environment, not only bearing high temperature, high pressure and high torque, but also resisting corrosive gas generated by decomposed molten plastic. Therefore, the screw is prone to problems such as screw rib wear, cross-section reduction and increased gap with the barrel during long-term service, resulting in decreased extrusion efficiency, increased plastic backflow, uneven plasticizing effect, and even causing grain or significant yield reduction on the product surface.

[0004] In order to prolong the service life of the screw, a wear-resistant coating or alloy layer is usually prepared on the surface of the screw rib in the prior art. However, due to the complex geometry of the screw surface and the presence of many irregular structures, manual spray welding is currently commonly used for surface strengthening. This method not only takes a lot of time and effort, and is highly dependent on the operator's technical skills, but also has poor consistency of finished products, making it difficult to meet the stable and batch production requirements.

[0005] In addition, the screw rib structure of most existing screws is relatively fixed, and the outer diameter and width change little along the axial direction. In plastic processing, especially for materials such as PVC that require high uniformity of plasticizing, the traditional screw has certain limitations in material conveying, mixing and shearing, and it is difficult to balance the processing requirements of efficient mixing and stable plasticizing. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the deficiencies in the prior art and provide a control method of a laser cladding gun head.

[0007] The present application is implemented by the following technical solutions:

[0008] A screw of an extruder, comprising a shaft and a screw rib arranged on the outer wall of the shaft, the outer diameter of the screw rib changes along the axial direction of the shaft, so that the screw rib has a tapered structure.

[0009] Preferably, the screw rib comprises a first zone and a second zone arranged along the axial direction;

[0010] the first zone has a decreasing width along the axial direction, the width of the first zone near the larger end of the outer diameter of the flight is greater than the width of the first zone near the smaller end of the outer diameter of the flight;

[0011] the second zone has a decreasing width along the axial direction, the width of the second zone near the larger end of the outer diameter of the flight is greater than the width of the second zone near the smaller end of the outer diameter of the flight.

[0012] Preferably, the first zone is near the larger end of the outer diameter of the flight, and the second zone is near the smaller end of the outer diameter of the flight.

[0013] the width of the flight of the first zone is less than the width of the flight of the second zone.

[0014] Preferably, the width of the flight of the first zone near the larger end of the outer diameter of the flight is 10mm, and the width of the flight of the first zone near the smaller end of the outer diameter of the flight is 6mm; and / or

[0015] the width of the flight of the second zone near the larger end of the outer diameter of the flight is 16mm, and the width of the flight of the second zone near the smaller end of the outer diameter of the flight is 14mm.

[0016] A laser cladding gun head for machining the screw rod described above, the laser cladding gun head comprising:

[0017] a powder feeding member for feeding powder to the surface of the flight;

[0018] a light source for emitting laser;

[0019] a lens arranged in front of the light source, the laser emitted by the light source being able to pass through the lens;

[0020] a driving assembly drivingly connected to the lens, the driving assembly being able to adjust the position of the lens to adjust the optical path of the laser passing through the lens.

[0021] Preferably, the driving assembly comprises:

[0022] a first driving member drivingly connected to the lens, the first driving member being able to drive the lens to move in a direction perpendicular to the direction of the laser emitted by the light source;

[0023] a second driving member drivingly connected to the lens, the second driving member being able to drive the lens to move in a direction parallel to the direction of the laser emitted by the light source.

[0024] Preferably, the powder feeding member is in the shape of an isosceles trapezoid.

[0025] The calculation formula of the two-waist included angle of the powder feeding part is:

[0026] ,

[0027] In the formula, is the two-waist included angle (°) of the powder feeding part, is the width of the screw ridge at the larger end of the screw ridge outer diameter (mm), is the width of the screw ridge at the smaller end of the screw ridge outer diameter (mm), is the outer diameter size at the larger end of the screw ridge outer diameter (mm), is the outer diameter size at the smaller end of the screw ridge outer diameter (mm), is the included angle (°) between the powder feeding part and the vertical plane;

[0028] The calculation formula of the length of the narrower bottom edge of the powder feeding part is:

[0029] ,

[0030] In the formula, is the length of the narrower bottom edge of the powder feeding part (mm), is the distance between the powder feeding part and the screw ridge at the initial position of the laser cladding gun head processing (mm).

[0031] A control method of a laser cladding gun head, the laser cladding gun head is the laser cladding gun head described above, the laser cladding gun head is arranged above the screw rod, and the control method comprises the following steps:

[0032] The screw rod rotates circumferentially, the laser cladding gun head moves axially along the screw rod, the powder feeding part feeds powder to the surface of the screw ridge, and the light source emits laser to the powder on the surface of the screw ridge to perform laser cladding processing;

[0033] During the axial movement of the laser cladding gun head along the screw rod, the laser cladding gun head moves radially along the screw rod to compensate for the change amount of the outer diameter of the screw ridge;

[0034] The light source and the lens move radially along the screw rod, and the moving direction of the light source and the lens along the screw rod is opposite to the moving direction of the laser cladding gun head along the screw rod, so that the laser can irradiate on the screw ridge;

[0035] During the axial movement of the laser cladding gun head along the screw rod, the lens moves vertically to adjust the spot area formed by the laser on the screw ridge to compensate for the change amount of the width of the screw ridge.

[0036] Preferably, the initial position of the laser cladding gun head is located at the end of the screw flight with larger outer diameter.

[0037] Preferably, the speed of the screw rod rotating in the circumferential direction is:

[0038] ,

[0039] In the formula, is the speed of the laser cladding gun head moving along the screw flight surface (mm / min), is the outer diameter of the screw flight at the current processing position of the laser cladding gun head (mm);

[0040] The speed of the laser cladding gun head moving along the screw rod in the axial direction is:

[0041] ,

[0042] In the formula, is the speed of the laser cladding gun head moving along the screw rod in the axial direction (mm / min), is the pitch of the screw flight at the current processing position of the laser cladding gun head (mm);

[0043] The speed of the laser cladding gun head moving along the screw rod in the radial direction is:

[0044] ,

[0045] In the formula, is the speed of the laser cladding gun head moving along the screw rod in the radial direction (mm / min), is the outer diameter size of the end of the screw flight with larger outer diameter (mm), is the outer diameter size of the end of the screw flight with smaller outer diameter (mm), is the included angle between the powder feeding part and the vertical plane (°), is the axial length of the screw flight that needs to be processed by laser cladding (mm);

[0046] The speed of the light source and the lens moving along the screw rod in the radial direction is:

[0047] ,

[0048] In the formula, is the speed of the light source and the lens moving along the screw rod in the radial direction (mm / min);

[0049] The speed of the lens moving in the vertical direction is:

[0050] ,

[0051] In the formula, The velocity (mm / min) of the lens moving in the vertical direction. The width (mm) of the screw ridge at the end with the larger outer diameter is [missing information]. The width (mm) of the screw ridge at the smaller end of the screw ridge's outer diameter.

[0052] The beneficial effects of this invention are as follows: By designing the screw ribs as a tapered structure that gradually changes along the central axis, the screw ribs of this invention have a larger outer diameter in the feeding section and a smaller outer diameter in the homogenization section, achieving a smooth transition in the middle section. This allows the material to be gradually subjected to enhanced compaction, mixing, and shearing during the conveying process, which not only significantly improves the uniformity of mixing and plasticizing, reduces material backflow, and increases extrusion efficiency, but is also particularly suitable for PVC processing where high plasticizing effects are required. This effectively improves product quality and meets the needs of different processing conditions.

[0053] Furthermore, based on the conical structure, the screw ribs are further divided into a first zone and a second zone, and the width of the screw ribs in both zones gradually decreases along the axial direction. At the same time, by setting the screw rib width in the first zone to be smaller than that in the second zone, the material can be quickly compacted and stably conveyed in the feeding section, while being subjected to stronger stirring and shearing in the homogenization section. This significantly improves the uniformity of mixing and plasticizing while ensuring efficient conveying, making it particularly suitable for processing materials such as PVC with strict requirements for plasticizing quality. This not only improves product quality but also enhances process adaptability.

[0054] Furthermore, this laser cladding gun head, by incorporating a powder feeding component, a light source, a lens, and a drive assembly with an adjustable lens position, enables the powder to be precisely delivered to the screw surface and efficiently interact with the focused laser, thereby achieving stable formation of the cladding layer. Simultaneously, the adjustable lens position design allows for flexible control of the optical path and focal point, ensuring consistent cladding quality across different screw surfaces. This improves processing accuracy and product consistency while reducing reliance on manual operation techniques, facilitating efficient and mass production of screw surface strengthening treatment.

[0055] Furthermore, by incorporating a first driving component and a second driving component in the drive assembly, the lens can move in directions perpendicular and parallel to the laser direction, respectively. This enables precise positioning of the laser spot on the screw surface and flexible adjustment of the laser focus position and spot size, ensuring uniform heating of the powder and stable formation of the cladding layer. This structure not only improves the accuracy and consistency of the cladding process and reduces manual adjustment errors, but also enhances the equipment's adaptability to different screw structures and processing conditions, contributing to high-quality and high-efficiency screw surface strengthening treatment.

[0056] Further, the control method can compensate the change of the outer diameter and width of the screw flight in real time, ensure that the laser spot is always accurately covered on the screw flight surface powder, effectively avoid uneven cladding or defects caused by geometric size change, and realize the uniform cladding layer forming of the screw surface, improve the machining consistency and stability, and further improve the wear resistance and service life of the screw, so as to meet the batch production and high-quality production requirements. BRIEF DESCRIPTION OF DRAWINGS

[0057] Figure 1 is a structural schematic diagram of the screw of the present application;

[0058] Figure 2 is a structural schematic diagram of the laser cladding gun head and the screw of the present application;

[0059] Figure 3 is a structural schematic diagram of the powder feeding part of the present application;

[0060] Figure 4 is a size schematic diagram of the screw of the present application;

[0061] Figure 5 is a structural schematic diagram of the powder feeding part and the screw of the present application;

[0062] Figure 6 is a structural schematic diagram of the light source and the lens of the present application;

[0063] Figure 7 is a structural schematic diagram of the driving assembly of the present application.

[0064] In the figure: 1, screw; 11, central shaft; 12, screw flight; 13, first area; 14, second area;

[0065] 2, laser cladding gun head; 21, powder feeding part; 22, light source; 23, lens; 24, first driving part; 25, second driving part. DETAILED DESCRIPTION

[0066] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below in combination with the drawings and the best embodiment. All other embodiments obtained by those skilled in the art on the basis of the embodiments in the application without creative labor belong to the scope of protection of the application.

[0067] In the description of the invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the invention.

[0068] In addition, it should be noted that in the description of the invention, unless otherwise explicitly specified and limited, the terms "mounting", "setting", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the communication between the two elements. For those skilled in the art, the specific meaning of the above terms in the invention can be understood according to the specific circumstances.

[0069] Reference Figure 1 The present application provides a screw 1 of an extruder. The screw 1 comprises a central shaft 11 and a screw flight 12 arranged on the outer wall of the central shaft 11. The outer diameter of the screw flight 12 varies along the axial direction of the central shaft 11, so that the screw flight 12 has a tapered structure. The axial direction of the central shaft 11 is the Y direction in the figure. Figure 1

[0070] Further, the screw flight 12 comprises a first zone 13 and a second zone 14 arranged along the axial direction. The first zone 13 is arranged near the end with larger outer diameter of the screw flight 12, and the second zone 14 is arranged near the end with smaller outer diameter of the screw flight 12.

[0071] The width of the screw flight 12 of the first zone 13 decreases along the axial direction. Specifically, the width of the screw flight of the first zone 13 near the end with larger outer diameter of the screw flight 12 is greater than the width of the screw flight of the first zone near the end with smaller outer diameter of the screw flight 12. More specifically, the width of the screw flight of the first zone 13 near the end with larger outer diameter of the screw flight 12 is 10 mm, and the width of the screw flight of the first zone 13 near the end with smaller outer diameter of the screw flight 12 is 6 mm.

[0072] The width of the screw flight 12 of the second zone 14 decreases along the axial direction. Specifically, the width of the screw flight of the second zone 14 near the end with larger outer diameter of the screw flight 12 is greater than the width of the screw flight of the second zone near the end with smaller outer diameter of the screw flight 12. More specifically, the width of the screw flight of the second zone 14 near the end with larger outer diameter of the screw flight 12 is 16 mm, and the width of the screw flight of the second zone 14 near the end with smaller outer diameter of the screw flight 12 is 14 mm.

[0073] ​The screw 1 adopts a conical design, which can provide more efficient material mixing and plasticizing effect, and is suitable for different processing requirements. The outer diameter of the screw flight 12 is larger at the feeding section of the screw 1, and is smaller at the homogenizing section of the screw 1, and the outer diameter of the screw flight 12 gradually transitions at the middle part. At the same time, the width of the screw flight 12 also gradually changes. In this way, when the material passes through the radial gap between the two screws 1, the stirring and shearing received by the material are very strong, so that the plasticizing of the material is very uniform, and this design is particularly suitable for processing PVC plastic.

[0074] With reference to Figure 2 , the application further provides a laser cladding gun head 2 used for laser cladding processing on the surface of the screw flight 12 of the screw 1. The laser cladding gun head 2 comprises a powder feeding piece 21, a light source 22, a lens 23 and a driving assembly.

[0075] With reference to Figures 3-5 , the powder feeding piece 21 is in the shape of an isosceles trapezoid, and a powder feeding channel is arranged inside the powder feeding piece 21. The smaller-width end of the isosceles trapezoidal powder feeding piece 21 is provided with an opening communicating with the powder feeding channel. When laser cladding processing is performed, the opening is arranged above the screw flight 12, and the powder can be sprayed to the surface of the screw flight 12 through the powder feeding channel and the opening. Further, the powder feeding piece 21 is arranged radially inclined relative to the screw 1 to avoid interference with the laser light path. The radial direction of the screw 1 is the X direction in Figure 4 .

[0076] Further, the shape of the powder feeding piece 21 is related to the shape of the screw flight 12 of the screw 1. Specifically, the calculation formula of the two-waist included angle of the isosceles trapezoidal powder feeding piece 21 is as follows:

[0077] ,

[0078] In the formula, is the two-waist included angle (°) of the powder feeding piece 21, is the width (mm) of the screw flight 12 at the larger-diameter end of the screw flight 12, is the width (mm) of the screw flight 12 at the smaller-diameter end of the screw flight 12, is the outer diameter size (mm) of the larger-diameter end of the screw flight 12, is the outer diameter size (mm) of the smaller-diameter end of the screw flight 12, is the included angle (°) between the powder feeding piece 21 and the vertical plane.

[0079] The calculation formula of the length of the narrower base of the isosceles trapezoidal powder feeding piece 21 is as follows:

[0080] ,

[0081] In the formula, The length of the narrow base of the isosceles trapezoid-shaped powder feeding member 21, i.e. the width of the opening of the powder feeding member 21. The distance between the powder feeding member 21 and the spiral ridge 12 at the initial position (mm), in this example The value is preferably 13-14 mm. The initial position is the position where the laser cladding gun head 2 is located above the larger-diameter end of the spiral ridge 12.

[0082] Generally, And After the determination, the shape of the powder feeding member 21 is determined, and other dimensions do not need to be further limited. Further, in order to ensure that the powder feeding member 21 has a long enough powder feeding channel and does not make the powder feeding member 21 too large, the height H of the isosceles trapezoid-shaped powder feeding member 21 ranges from 20 mm to 30 mm. When , And H are determined, the length of the wide base of the isosceles trapezoid-shaped powder feeding member 21 is also determined.

[0083] Referring to Figure 6 And Figure 7 , the light source 22 is used to emit laser, and the laser acts on the powder on the surface of the spiral ridge 12 to realize laser cladding processing. The lens 23 is arranged between the light source 22 and the screw rod 1, and the laser can be focused after passing through the lens 23. The driving assembly is drivingly connected to the lens 23, and the driving assembly is used to drive the position of the lens 23 relative to the light source 22 to adjust the light path of the laser passing through the lens 23. The driving assembly includes a first driving member 24 and a second driving member 25, both of which are motors. The first driving member 24 can drive the lens 23 to move in a direction perpendicular to the direction in which the light source 22 emits laser, and the first driving member 24 can make the laser passing through the lens 23 towards the powder spot on the surface of the spiral ridge 12. The second driving member 25 can drive the lens 23 to move in a direction parallel to the direction in which the light source 22 emits laser to adjust the focal point of the laser, and further adjust the size of the laser spot on the spiral ridge 12.

[0084] Since the surface width of the spiral ridge 12 in this embodiment is different, the spiral ridge 12 also has a taper, and during laser cladding processing, the movement of the laser cladding gun head 2 needs to be accurately controlled according to the shape of the spiral ridge 12. Therefore, the embodiment also provides a control method of the laser cladding gun head 2.

[0085] During laser cladding processing of the screw rod 1, the opening of the powder feeding member 21 is arranged towards the surface of the spiral ridge 12 to spray powder towards the surface of the spiral ridge 12. The light source 22 emits laser, and the laser passes through the lens 23 and irradiates onto the powder on the surface of the spiral ridge 12 to perform laser cladding processing.

[0086] Simultaneously, the screw 1 rotates circumferentially; in other words, the screw 1 rotates around its own axis. The laser cladding gun head 2 moves axially along the screw 1, so that the opening of the powder feeding part 21 and the laser irradiation position move along the surface of the screw rib 12.

[0087] Furthermore, the circumferential rotational speed of the screw 1 is:

[0088] ,

[0089] In the formula, The speed (mm / min) at which the laser cladding gun head 2 moves along the surface of the spiral ridge 12 is the linear velocity of the laser cladding gun head 2 moving along the spiral line. The outer diameter (mm) of the screw rib 12 at the current processing position of the laser cladding gun head 2. During laser cladding, the cladding linear velocity is one of the cladding process parameters, expressed as... The line represents a range typically between 0.4 and 1.0 m / min; in this example, the preferred speed is... It is 0.4 m / min.

[0090] Furthermore, during the processing, for every 360° rotation of the screw 1 around its own axis, the corresponding circumferential rotation speed n of the screw 1 corresponds to the cladding optical head needing to travel one pitch along the Y direction to ensure that the cladding position is precisely clad on the screw edge surface. Therefore, based on this logical relationship, the speed at which the laser cladding gun head 2 moves along the axial direction of the screw 1 can be obtained as follows:

[0091] ,

[0092] In the formula, The speed (mm / min) at which the laser cladding gun head 2 moves along the axial direction of the screw 1. The pitch (mm) of the screw thread 12 at the current processing position of the laser cladding gun head 2.

[0093] Furthermore, the initial processing position of the laser cladding gun head 2 is located at the end with the larger outer diameter of the first region 13 of the screw ridge 12, and the opening of the powder feeding component 21 is located directly above the screw ridge 12. Since the outer diameter of the screw ridge 12 decreases and the powder feeding component 21 is tilted, if the relative position of the powder feeding component 21 and the screw ridge 12 remains unchanged during the axial movement of the laser cladding gun head 2 along the screw 1, the powder sprayed by the powder feeding component 21 cannot fall onto the screw ridge 12. Therefore, during the axial movement of the laser cladding gun head 2 along the screw 1, the laser cladding gun head 2 needs to move radially along the screw 1 so that the opening of the powder feeding component 21 always faces the surface of the screw ridge 12. The formula for calculating the radial movement speed of the laser cladding gun head 2 along the screw 1 is:

[0094] ,

[0095] wherein, is the speed of the laser cladding head 2 moving along the radial direction of the screw rod 1 (mm / min), is the outer diameter size of the larger end of the outer diameter of the screw ridge 12 (mm), that is, the outer diameter size of the screw ridge 12 at the starting position of the laser cladding head 2. is the outer diameter size of the smaller end of the outer diameter of the screw ridge 12 (mm), that is, the outer diameter size of the screw ridge 12 at the end position of the laser cladding head 2. is the included angle between the powder feeding member 21 and the vertical plane (°), is the axial length of the screw ridge 12 that needs to be processed by laser cladding (mm).

[0096] Further, when the laser cladding head 2 moves along the radial direction of the screw rod 1, the light source 22 and the lens 23 need to move reversely so that the laser can irradiate on the screw ridge. Specifically, the light source 22 and the lens 23 move along the radial direction of the screw rod 1, and the direction in which the light source 22 and the lens 23 move along the radial direction of the screw rod 1 is opposite to the direction in which the laser cladding head 2 moves along the radial direction of the screw rod 1. Moreover, the speed at which the light source 22 and the lens 23 move along the radial direction of the screw rod 1 is the same as the speed at which the laser cladding head 2 moves along the radial direction of the screw rod 1, that is:

[0097] ,

[0098] wherein, is the speed of the light source and the lens moving along the radial direction of the screw rod (mm / min).

[0099] Further, since the width of the screw ridge 12 changes during the axial movement of the laser cladding head 2 along the screw rod 1, the lens 23 needs to move along the vertical direction to adjust the spot area of the laser formed on the screw ridge 12 to compensate for the change amount of the width of the screw ridge 12. Specifically, the speed at which the lens 23 moves along the vertical direction is:

[0100] ,

[0101] wherein, is the speed of the lens 23 moving along the vertical direction (mm / min), is the width of the screw ridge 12 at the larger end of the outer diameter of the screw ridge 12 (mm), that is, the width size of the screw ridge 12 at the starting position of the laser cladding head 2. is the width of the screw ridge 12 at the smaller end of the outer diameter of the screw ridge 12 (mm), that is, the width size of the screw ridge 12 at the end position of the laser cladding head 2.

[0102] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the protection scope of the present application.

Claims

1. A control method of a laser cladding gun head, the laser cladding gun head being arranged above a screw rod, the control method comprising: the screw rod comprising a central shaft and screw flights arranged on the outer wall of the central shaft, the outer diameter of the screw flights varying along the axial direction of the central shaft, so that the screw flights have a tapered structure, the screw flights comprising a first region and a second region arranged along the axial direction, the screw flight width of the first region decreasing along the axial direction, the screw flight width of the first region near the end with the larger outer diameter of the screw flights being greater than the screw flight width of the first region near the end with the smaller outer diameter of the screw flights, the screw flight width of the second region decreasing along the axial direction, the screw flight width of the second region near the end with the larger outer diameter of the screw flights being greater than the screw flight width of the second region near the end with the smaller outer diameter of the screw flights; the laser cladding gun head comprising: a powder feeder configured to deliver powder to the surface of the screw flights; a light source configured to emit laser light; a lens arranged in front of the light source, the laser light emitted by the light source being capable of passing through the lens; a drive assembly drivingly connected to the lens, the drive assembly being capable of adjusting the position of the lens to adjust the optical path of the laser light passing through the lens; the drive assembly comprising: a first drive member drivingly connected to the lens, the first drive member being capable of driving the lens to move in a direction perpendicular to the direction in which the light source emits laser light; and a second drive member drivingly connected to the lens, the second drive member being capable of driving the lens to move in a direction parallel to the direction in which the light source emits laser light; the control method comprising the following steps: rotating the screw rod in the circumferential direction, moving the laser cladding gun head in the axial direction of the screw rod, delivering powder to the surface of the screw flights by the powder feeder, and emitting laser light from the light source to the powder on the surface of the screw flights to perform laser cladding processing; during the movement of the laser cladding gun head in the axial direction of the screw rod, moving the laser cladding gun head in the radial direction of the screw rod to compensate for the variation in the outer diameter of the screw flights; moving the light source and the lens in the radial direction of the screw rod, the direction of movement of the light source and the lens in the radial direction of the screw rod being opposite to the direction of movement of the laser cladding gun head in the radial direction of the screw rod, so that the laser light can irradiate the screw flights; during the movement of the laser cladding gun head in the axial direction of the screw rod, moving the lens in the vertical direction to adjust the spot area of the laser light formed on the screw flights to compensate for the variation in the screw flight width; the speed of rotation of the screw rod in the circumferential direction being: the speed of movement of the laser cladding gun head in the axial direction of the screw rod being: the speed of movement of the laser cladding gun head in the radial direction of the screw rod being: the initial position of the laser cladding gun head being located at the end with the larger outer diameter of the screw flights; the speed of movement of the light source and the lens in the radial direction of the screw rod being: and the speed of movement of the lens in the vertical direction being: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ， In the formula, is the speed of the laser cladding gun head moving along the spiral surface, in mm / min, is the outer diameter of the spiral at the current processing position of the laser cladding gun head, in mm; ​ ， wherein is the speed of the laser cladding gun head moving along the screw rod axis, in mm / min, is the pitch of the screw ridge at the current processing position of the laser cladding gun head, in mm; ​ ， wherein, is the speed of the radial movement of the laser cladding gun head along the screw, in mm / min, is the outer diameter size of the larger end of the outer diameter of the screw ridge, in mm, is the outer diameter size of the smaller end of the outer diameter of the screw ridge, in mm, is the included angle between the powder feeding part and the vertical plane, in °, is the axial length of the screw ridge that needs to be processed by laser cladding, in mm.

2. The control method according to claim 1, characterized by, ​ 3. The control method according to claim 2, characterized by, ​ ， wherein V is the speed of the light source and the lens in the radial direction of the screw, in mm / min. ​ ， In the formula, is the speed of the lens moving in the vertical direction, in mm / min, is the width of the screw ridge at the larger end of the screw ridge outer diameter, in mm, is the width of the screw ridge at the smaller end of the screw ridge outer diameter, in mm.

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